JP2024082574A - Optical signal transmitting/receiving device and power conversion device - Google Patents

Abstract

[Problem] To provide an optical signal transmitting/receiving device and a power conversion device capable of transmitting and receiving a plurality of signals with different frequencies with a simpler configuration. [Solution] An optical signal transmitting/receiving device is provided that includes an optical transmitting unit that transmits optical signals, an optical receiving unit that is connected to the optical transmitting unit via an optical transmission line, receives the optical signal, and converts it into an electrical signal having a magnitude corresponding to the amount of light emitted by the optical signal, thereby outputting a received signal that is an electrical signal, an emission control unit that receives a first input signal having a predetermined frequency and a second input signal having a lower frequency than the first input signal, generates a superimposed signal by superimposing the second input signal on the first input signal, and inputs the superimposed signal to the optical transmitting unit, thereby causing the optical transmitting unit to transmit an optical signal corresponding to the superimposed signal, and a light receiving control unit that generates a first restored signal corresponding to the first input signal and a second restored signal corresponding to the second input signal, based on the received signal output from the optical receiving unit. [Selected Figure] Figure 1

Description

Embodiments of the present invention relate to an optical signal transmitting/receiving device and a power conversion device.

There is an optical signal transmitting/receiving device that includes an optical transmitting unit that transmits an optical signal, an optical receiving unit that receives the optical signal, and an optical transmission path that connects the optical transmitting unit and the optical receiving unit. Optical signal transmitting/receiving devices are used, for example, in power conversion devices. In power conversion devices, for example, optical signals are used to send and receive signals for the purpose of insulation.

In such optical signal transmitting/receiving devices, multiple signals with different frequencies may be transmitted and received. In such cases, if an optical transmitting section, an optical receiving section, and an optical transmission line section are provided for each of the multiple signals, there is a concern that the number of parts will increase, leading to an increase in the size and cost of the device. For this reason, it is desirable to have an optical signal transmitting/receiving device and a power conversion device using the same that are able to transmit and receive multiple signals with different frequencies with a simpler configuration.

JP 2020-99022 A

Embodiments of the present invention provide an optical signal transmitting/receiving device and a power conversion device that can transmit and receive multiple signals with different frequencies with a simpler configuration.

According to an embodiment of the present invention, an optical signal transmitting and receiving device is provided, which includes an optical transmitting unit that transmits an optical signal, an optical transmission path connected to the optical transmitting unit, an optical receiving unit that is connected to the optical transmitting unit via the optical transmission path, receives the optical signal, and converts it into an electrical signal having a magnitude corresponding to the amount of light emitted by the optical signal, thereby outputting a received signal of the electrical signal, an emission control unit that receives an input of a first input signal having a predetermined frequency and a second input signal having a frequency lower than the first input signal, generates a superimposed signal by superimposing the second input signal on the first input signal, and inputs the superimposed signal to the optical transmitting unit, thereby causing the optical signal corresponding to the superimposed signal to be transmitted to the optical transmitting unit, and a light receiving control unit that restores the first input signal and the second input signal based on the received signal output from the optical receiving unit, thereby generating a first restored signal corresponding to the first input signal and a second restored signal corresponding to the second input signal.

An optical signal transmitting/receiving device and a power conversion device are provided that can transmit and receive multiple signals with different frequencies with a simpler configuration.

1 is a block diagram illustrating an optical signal transmitting and receiving device according to a first embodiment. 4 is a timing chart illustrating an example of an operation of the optical signal transmitting and receiving device according to the first embodiment. FIG. 11 is a block diagram illustrating a power conversion device according to a second embodiment. FIG. 11 is a block diagram illustrating a power conversion device according to a third embodiment. FIG. 2 is a block diagram illustrating a converter.

Each embodiment will be described below with reference to the drawings.
The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as in reality. Even when the same part is shown, the dimensions and ratios of each part may be different depending on the drawing.
In this specification and each drawing, elements similar to those described above with reference to the previous drawings are given the same reference numerals and detailed descriptions thereof will be omitted as appropriate.

First Embodiment
FIG. 1 is a block diagram illustrating an optical signal transmitting and receiving device according to the first embodiment.
As shown in FIG. 1, the optical signal transmitting and receiving device 10 includes an optical transmitting section 11, an optical transmission line 12, an optical receiving section 13, an emission control section 14, and a light reception control section 15.

The optical transmitter 11 transmits an optical signal. The optical transmitter 11 has a light-emitting element such as a light-emitting diode or a laser diode, and transmits an optical signal by turning on and off the light-emitting element. The optical signal has, for example, an emission period and an extinction period. The emission period is, for example, a period during which the light-emitting element is turned on, and the extinction period is, for example, a period during which the light-emitting element is turned off. The extinction period is not limited to a state in which the light-emitting element is turned off, and may be, for example, a state in which the amount of light emitted from the light-emitting element is sufficiently small. In other words, the emission period is a state in which the amount of light emitted from the light-emitting element is equal to or greater than a threshold, and the extinction period is a state in which the amount of light emitted from the light-emitting element is less than the threshold.

One end of the optical transmission path 12 is connected to the optical transmitter 11. The other end of the optical transmission path 12 is connected to the optical receiver 13. In other words, the optical transmission path 12 connects the optical transmitter 11 and the optical receiver 13. The optical transmission path 12 is, for example, an optical fiber. The optical transmission path 12 enables the transmission of the optical signal transmitted from the optical transmitter 11 to the optical receiver 13. The optical transmission path 12 may have, for example, an optical repeater or an optical distributor. The configuration of the optical transmission path 12 may be any configuration that allows the transmission of the optical signal transmitted from the optical transmitter 11 to the optical receiver 13.

The optical receiving unit 13 is connected to the optical transmitting unit 11 via the optical transmission path 12, receives an optical signal, and converts it into an electrical signal whose magnitude corresponds to the amount of light emitted by the optical signal, thereby outputting an electrical reception signal. The optical receiving unit 13 has a light receiving element, such as a photodiode, and converts the optical signal into an electrical reception signal using the light receiving element.

The light emission control unit 14 receives a first input signal having a predetermined frequency and a second input signal having a frequency lower than the first input signal. The first input signal is, for example, a high-frequency signal, and the second input signal is, for example, a low-frequency signal. The frequency of the first input signal is, for example, 1 kHz or more. The frequency of the second input signal is, for example, less than 1 kHz. The first input signal is, for example, a signal having a frequency of 1 kHz or more, and the second input signal is, for example, a signal having a frequency less than 1 kHz. However, the frequencies of the first input signal and the second input signal are not limited to the above and may be any frequency. The frequency of the first input signal may be any frequency higher than the frequency of the second input signal. The frequency of the second input signal may be any frequency lower than the frequency of the first input signal.

The light emission control unit 14 generates a superimposed signal by superimposing the second input signal on the first input signal, and inputs the superimposed signal to the optical transmission unit 11, causing the optical transmission unit 11 to transmit an optical signal corresponding to the superimposed signal.

The light-receiving control unit 15 generates a first restored signal corresponding to the first input signal and a second restored signal corresponding to the second input signal by restoring the first input signal and the second input signal based on the received signal output from the light-receiving unit 13. The light-receiving control unit 15 outputs the generated first restored signal and second restored signal to the outside.

FIG. 2 is a timing chart illustrating an example of the operation of the optical signal transmitting and receiving device according to the first embodiment.
FIG. 2 illustrates an example of each of the first input signal, the second input signal, the superimposed signal, the first restored signal, and the second restored signal.

As shown in FIG. 2, the first input signal and the second input signal are, for example, digital signals having a low voltage state and a high voltage state. The low voltage state (Lo) corresponds, for example, to a digital value of "0," and the high voltage state (Hi) corresponds, for example, to a digital value of "1."

The light emission control unit 14 generates a digital superimposed signal based on the input first input signal and second input signal, and inputs the generated superimposed signal to the optical transmission unit 11. The optical transmission unit 11 transmits an optical signal corresponding to a digital signal, for example, by setting the optical signal to an extinction period when the voltage of the input superimposed signal is low, and setting the optical signal to an emission period when the voltage of the input superimposed signal is high. The extinction period corresponds to, for example, a digital value of "0", and the emission period corresponds to, for example, a digital value of "1". The optical receiving unit 13 converts the optical signal into an electrical signal, thereby outputting a received digital signal.

In this way, the optical signal transmission/reception device 10 converts, for example, a digital signal into an optical signal for transmission, and also restores the optical signal to a digital signal. In other words, the optical signal transmission/reception device 10 is a device for performing digital communication using, for example, an optical signal.

The light emission control unit 14 has, for example, an exclusive OR circuit (XOR circuit) 20. The exclusive OR circuit 20 generates a superimposed digital signal from the first input signal and the second input signal by calculating the exclusive OR of the first input signal and the second input signal of the input digital signal.

In the exclusive OR operation, the digital value of the output signal changes in response to a change in the digital value of one of the first and second input signals. This makes it possible to generate a superimposed signal by superimposing the second input signal on the first input signal. However, the method of generating the superimposed signal is not limited to the method using the exclusive OR circuit 20, and any method capable of appropriately generating a superimposed signal by superimposing the second input signal on the first input signal may be used. The configuration of the light emission control unit 14 may be any configuration capable of generating a superimposed signal from the first and second input signals, inputting the superimposed signal to the optical transmission unit 11, and causing the optical transmission unit 11 to transmit an optical signal corresponding to the superimposed signal.

The light receiving control unit 15 has, for example, a one-shot circuit 30 and a filter circuit 32. The light receiving control unit 15 inputs the received signal output from the optical receiving unit 13 to each of the one-shot circuit 30 and the filter circuit 32.

The one-shot circuit 30 is a circuit that outputs a pulse of a predetermined width in response to a change in the received signal. The one-shot circuit 30 outputs a pulse of a predetermined width in response to the rising edge and falling edge of the received signal, which is, for example, a digital signal. In other words, the one-shot circuit 30 sets the output signal to a high voltage state for a predetermined time in response to the rising edge and falling edge of the received signal, which is, for example, a digital signal.

If the one-shot circuit 30 detects the next change in the received signal before a predetermined time corresponding to the pulse width has elapsed after outputting a pulse, it outputs the next pulse at that point in time, thereby maintaining the high voltage state of the output signal. On the other hand, if the one-shot circuit 30 does not detect the next change in the received signal before a predetermined time corresponding to the pulse width has elapsed after outputting a pulse, it switches the output signal from a high voltage state to a low voltage state as the predetermined time elapses.

In other words, the one-shot circuit 30 is a first restoration circuit that restores the first input signal from the received signal and generates a first restored signal. The light receiving control unit 15 outputs the output of the one-shot circuit 30 as the first restored signal corresponding to the first input signal.

The filter circuit 32 performs a process of attenuating the signal of the frequency component of the first input signal contained in the received signal and passing the signal of the frequency component of the second input signal. In other words, the filter circuit 32 restores the second input signal by outputting only the signal of the frequency component of the second input signal contained in the received signal. The filter circuit 32 is, for example, a low-pass filter. In other words, the filter circuit 32 is a second restoration circuit that restores the second input signal from the received signal and generates a second restored signal. The light receiving control unit 15 outputs the output of the filter circuit 32 as a second restored signal corresponding to the second input signal.

As shown in FIG. 2, the first input signal is, for example, a signal that repeats a high voltage state and a low voltage state at a predetermined period T1. In other words, the first input signal is a pulsed signal that oscillates at a predetermined period T1. The first input signal is, for example, a signal that enables the receiving device to detect an abnormality in the transmitting device. The first input signal is, for example, a heartbeat signal. The receiving device detects an abnormality in the transmitting device when, for example, the signal oscillation stops or the interval between signal oscillations changes from the predetermined period T1.

The second input signal is, for example, a control signal for repeating a high voltage state and a low voltage state at a predetermined period T2 and for controlling by changing the ratio of the high voltage state to the low voltage state. The second input signal is, for example, a control signal for PWM control. The period T2 of the second input signal is longer than the period T1 of the first input signal. The period T2 of the second input signal is, for example, 10 times or more the period T1 of the first input signal.

The one-shot circuit 30 outputs a pulse of width T3 in response to changes in the received signal. The width T3 of the pulse output by the one-shot circuit 30 is set, for example, to be longer than the period T1 of the first input signal and less than half the period T2 of the second input signal. As a result, when the first input signal is normally output at a predetermined period T1, the timing of the next period T1 arrives before the time of width T3 has elapsed, so that the first restored signal, which is the output signal of the one-shot circuit 30, remains in a high voltage state. Then, when the oscillation of the first input signal stops or when the period of the first input signal becomes longer than period T1, the first restored signal goes into a low voltage state.

Therefore, when the first restored signal is in a high voltage state, the receiving device determines that the transmitting device is normal, and when the first restored signal is in a low voltage state, it detects an abnormality in the transmitting device. This allows the one-shot circuit 30 to restore the first input signal and generate a first restored signal corresponding to the first input signal.

In this way, the light receiving control unit 15 does not necessarily have to be configured to restore the shapes of the first input signal and the second input signal as they are. The first restored signal may be any signal that has at least the same function as the first input signal. The second restored signal may be any signal that has at least the same function as the second input signal.

The configuration of the light receiving control unit 15 is not limited to the above. For example, the light receiving control unit 15 may be a high-pass filter that restores the first input signal from the received signal by outputting only the signal of the frequency component of the first input signal contained in the received signal, and generates the first restored signal, as the first restoration circuit. The first restoration circuit and the second restoration circuit may be set appropriately according to the contents of the first input signal and the second input signal, the contents of the superimposed signal, and the like. The configuration of the light receiving control unit 15 may be any configuration that can generate a first restored signal corresponding to the first input signal and a second restored signal corresponding to the second input signal by restoring the first input signal and the second input signal based on the received signal output from the optical receiving unit 13. The configuration of the light receiving control unit 15 may be any configuration that can generate a first restored signal having at least the same function as the first input signal, and can generate a second restored signal having the same function as the second input signal.

As described above, in the optical signal transmitting/receiving device 10 according to this embodiment, the light emission control unit 14 generates a superimposed signal by superimposing the second input signal on the first input signal, and inputs the superimposed signal to the optical transmitting unit 11, causing the optical transmitting unit 11 to transmit an optical signal corresponding to the superimposed signal. The light reception control unit 15 restores the first input signal and the second input signal based on the received signal output from the optical receiving unit 13, thereby generating a first restored signal corresponding to the first input signal and a second restored signal corresponding to the second input signal.

As a result, the optical signal transmitting/receiving device 10 can transmit two signals, a first input signal and a second input signal, over a single optical transmission path 12. Therefore, the optical signal transmitting/receiving device 10 can transmit and receive multiple signals with different frequencies with a simpler configuration than, for example, a configuration in which two optical transmitting units 11, two optical transmission paths 12, and two optical receiving units 13 corresponding to the two signals are provided.

The number of signals superimposed on the superimposed signal is not necessarily limited to two. The light emission control unit 14 may generate a superimposed signal by superimposing three or more signals, for example. The light reception control unit 15 may restore each of the three or more signals. The number of signals superimposed on the superimposed signal is not limited to two, and may be three or more as long as the light reception control unit 15 can appropriately restore the signals. For example, three or more signals with different frequencies may be superimposed, and each signal may be restored by multiple bandpass filters according to the frequency of each signal. The light emission control unit 14 may be configured to generate a superimposed signal by superimposing at least two signals. The light reception control unit 15 may be configured to restore at least two signals according to the number of signals to be superimposed on the superimposed signal.

Second Embodiment
FIG. 3 is a block diagram illustrating a power conversion device according to the second embodiment.
As shown in FIG. 3 , the power conversion device 100 includes a main circuit unit 101 , a control device 102 , and an optical signal transmitting/receiving device 104 .

The main circuit section 101 has a converter 101a, and performs power conversion by the operation of the converter 101a. The control device 102 controls the operation of the main circuit section 101. In other words, the control device 102 controls the operation of the power conversion by the converter 101a. The optical signal transmitting/receiving device 104 performs communication between the main circuit section 101 and the control device 102.

The converter 101a has six switching elements 111-116 connected in a three-phase bridge, six rectifier elements 121-126 connected in anti-parallel to each of the six switching elements 111-116, a charge storage element 130 connected in parallel to each of the six switching elements 111-116, and six drive circuits 131-136 that switch each of the six switching elements 111-116 on and off.

In converter 101a, both ends of each of switching elements 111 to 116 form a pair of DC terminals 106a, 106b, and the connection point between switching element 111 and switching element 112, the connection point between switching element 113 and switching element 114, and the connection point between switching element 115 and switching element 116 form three AC terminals 108a to 108c, respectively. Converter 101a is a so-called three-phase two-level inverter.

The converter 101a is connected to an AC power system via each of the AC terminals 108a to 108c. Each of the AC terminals 108a to 108c is connected to the AC power system, for example, via a circuit breaker or a transformer (not shown). The converter 101a is also connected to a DC power source or a DC load via a pair of DC terminals 106a, 106b. As a result, the main circuit unit 101 converts power by the operation of the converter 101a. The main circuit unit 101 converts DC to AC or AC to DC, for example, by switching each of the switching elements 111 to 116 of the converter 101a.

The optical signal transmitting/receiving device 104, like the optical signal transmitting/receiving device 10 of the first embodiment, has an optical transmitting unit 11, an optical transmission path 12, an optical receiving unit 13, an emission control unit 14, and a light receiving control unit 15. The configurations of the optical transmitting unit 11, the optical transmission path 12, the optical receiving unit 13, the emission control unit 14, and the light receiving control unit 15 are substantially the same as those described in relation to the first embodiment, and therefore detailed description will be omitted.

The light emission control unit 14 is connected to the main circuit unit 101. The light reception control unit 15 is connected to the control device 102. This allows the optical signal transmission/reception device 104 to transmit a signal from the main circuit unit 101 to the control device 102. The optical signal transmission/reception device 104 also has another optical transmission unit, an optical transmission path, and an optical reception unit, which are not shown, and also allows the transmission of a signal from the control device 102 to the main circuit unit 101. The optical signal transmission/reception device 104 electrically insulates the main circuit unit 101 and the control device 102 while enabling, for example, bidirectional communication between the main circuit unit 101 and the control device 102. However, the optical signal transmission/reception device 104 does not necessarily have to enable bidirectional communication. The optical signal transmission/reception device 104 may be configured to perform communication only in one direction, either from the main circuit unit 101 to the control device 102 or from the control device 102 to the main circuit unit 101. For example, the transmission of signals from the control device 102 to the main circuit unit 101 may be performed by an optical signal transmission/reception device other than the optical signal transmission/reception device 104.

The control device 102 transmits a control signal to the drive circuits 131-136 via the optical signal transmitting/receiving device 104. The control signal is, for example, a control signal for controlling the switching of each switching element 111-116 by repeating a high voltage state and a low voltage state at a predetermined cycle and changing the ratio of the high voltage state to the low voltage state. The control signal is, for example, a control signal for PWM control. The control signal is, for example, a digital signal. The control signal may also be called, for example, a gate signal or a gate command.

The drive circuits 131 to 136 switch each of the switching elements 111 to 116 on and off based on a control signal input from the control device 102. Each of the switching elements 111 to 116 has, for example, a pair of main terminals and a control terminal. Each of the switching elements 111 to 116 also has an on state and an off state. The on state is a state in which a current flows between the pair of main terminals. The off state is a state in which the flow of current between the pair of main terminals is blocked. Each of the switching elements 111 to 116 switches between the on state and the off state depending on the voltage between the pair of main terminals and the voltage of the control terminal. Note that the off state is not limited to a state in which no current flows between the pair of main terminals, but may be a state in which a weak current flows between the pair of main terminals within a range that does not affect the operation of the main circuit unit 101. Each of the switching elements 111 to 116 is, for example, a self-excited semiconductor element such as an IGBT or a MOSFET. However, each of the switching elements 111 to 116 is not limited to this and may be any element that can be arbitrarily switched between an on state and an off state.

The control device 102 transmits control signals to each of the drive circuits 131-136 via the optical signal transmitting/receiving device 104, and controls the switching of each of the switching elements 111-116, thereby controlling the power conversion by the main circuit unit 101.

Each drive circuit 131-136 switches between the on and off states of each switching element 111-116 by changing the magnitude of the voltage at the control terminal of each switching element 111-116 in response to a control signal input from the control device 102. For example, when the voltage of the control signal is low, each drive circuit 131-136 turns each switching element 111-116 off by lowering the voltage at the control terminal of each switching element 111-116, and when the voltage of the control signal is high, each drive circuit 131-136 turns each switching element 111-116 on by raising the voltage at the control terminal of each switching element 111-116.

In this way, the magnitude of the voltage at the control terminal of each switching element 111-116 changes in response to the control signal. However, the magnitude of the voltage of the control signal, the magnitude of the voltage at the control terminal of each switching element 111-116, and the on/off relationship of each switching element 111-116 are not limited to the above. The magnitude of the voltage of the control signal, the magnitude of the voltage at the control terminal of each switching element 111-116, and the on/off relationship of each switching element 111-116 may be set appropriately in response to the characteristics of each switching element 111-116.

The optical signal transmitting/receiving device 104 has, for example, a plurality of optical transmitting units 11, a plurality of optical transmission paths 12, a plurality of optical receiving units 13, a plurality of light emission control units 14, and a plurality of light reception control units 15, each of which is provided corresponding to one of the driving circuits 131 to 136. The signals output from each of the driving circuits 131 to 136 are input to the control device 102 via the optical signal transmitting/receiving device 104.

Each of the drive circuits 131 to 136, for example, repeats a high voltage state and a low voltage state at a predetermined cycle, and inputs a heartbeat signal to each of the light emission control units 14 as a first input signal so that the control device 102 can detect an abnormality in each of the drive circuits 131 to 136. The heartbeat signal is, for example, a digital signal.

In addition, each of the drive circuits 131 to 136 measures the voltage of the control terminal of each of the switching elements 111 to 116, for example, and inputs a feedback signal corresponding to the measurement result of the voltage of the control terminal to each of the light emission control units 14 as a second input signal. The voltage of the control terminal may be called, for example, a gate voltage. As described above, the voltage of the control terminal of each of the switching elements 111 to 116 changes according to the control signal. For example, when each of the switching elements 111 to 116 and each of the drive circuits 131 to 136 are normal, the feedback signal is a signal that changes in the same way as the control signal. For example, the feedback signal is a signal that repeats a high voltage state and a low voltage state at a predetermined cycle and changes the ratio of the high voltage state and the low voltage state. The feedback signal is, for example, a PWM signal. The feedback signal is, for example, a digital signal. In other words, the feedback signal is a signal that allows the control device 102 to check whether the control signal has been properly input to the control terminal of each of the switching elements 111 to 116.

In other words, the main circuit unit 101 repeats high voltage and low voltage states at a predetermined cycle, and inputs a heartbeat signal to the light emission control unit 14 as a first input signal so that the control device 102 can detect an abnormality in the main circuit unit 101. The main circuit unit 101 then measures the voltages at the control terminals of the switching elements 111-116, and inputs a feedback signal corresponding to the measurement results of the control terminal voltages to the light emission control unit 14 as a second input signal. As described with reference to FIG. 2 of the first embodiment above, the cycle of the feedback signal (control signal) is longer than the cycle of the heartbeat signal. In other words, the cycle T2 of the second input signal is longer than the cycle T1 of the first input signal.

As a result, the power conversion device 100 according to this embodiment can transmit two signals, a first input signal and a second input signal, over a single optical transmission path 12. Therefore, the power conversion device 100 can transmit and receive multiple signals with different frequencies with a simpler configuration than, for example, a case in which two optical transmitters 11, two optical transmission paths 12, and two optical receivers 13 corresponding to the two signals are provided.

The power conversion device 100 is provided with, for example, a plurality of optical transmitters 11, a plurality of optical transmission paths 12, a plurality of optical receivers 13, a plurality of light emission control units 14, and a plurality of light reception control units 15, each of which corresponds to a respective one of the plurality of drive circuits 131 to 136. In this case, by making it possible to transmit two signals, the first input signal and the second input signal, over one optical transmission path 12, the number of optical transmission paths 12 can be further reduced, and an increase in the number of parts in the power conversion device 100 can be further suppressed.

In this example, the optical signal transmission/reception device 104 is provided separately from the main circuit section 101 and the control device 102. The optical signal transmission/reception device 104 may be incorporated into the main circuit section 101 or the control device 102 without being limited thereto. In other words, the optical signal transmission/reception device 104 may be provided integrally with the main circuit section 101 or the control device 102. The optical signal transmission/reception device 104 may also be provided separately in the main circuit section 101 and the control device 102, for example, by providing the optical transmission section 11 and the light emission control section 14 in the main circuit section 101 and the optical reception section 13 and the light reception control section 15 in the control device 102. In other words, the optical signal transmission/reception device 104 may be provided partially in the main circuit section 101 (for example, each drive circuit 131 to 136) and another part in the control device 102. The configuration of the optical signal transmitting/receiving device 104 is not limited to the above, and may be any configuration that allows appropriate communication between the main circuit section 101 and the control device 102.

Third Embodiment
FIG. 4 is a block diagram illustrating a power conversion device according to the third embodiment.
4, the power conversion device 200 includes a main circuit unit 212, a control device 214, and an optical signal transmission/reception device 216. The power conversion device 200 is used in, for example, a DC power transmission system. The power conversion device 200 is connected to an AC power system 202 and a pair of DC transmission lines 203 and 204 in the DC power transmission system.

The DC transmission system has, for example, a transformer 206. The main circuit section 212 of the power conversion device 200 is connected to the AC power system 202 via the transformer 206. The AC power of the AC power system 202 is three-phase AC power. More specifically, it is symmetrical three-phase AC power. The transformer 206 converts the three-phase AC power of the AC power system 202 into AC power corresponding to the main circuit section 212. The transformer 206 changes the effective value of each phase of the three-phase AC power in accordance with the main circuit section 212. The transformer 206 is a three-phase transformer. The transformer 206 is provided as necessary and can be omitted. The three-phase AC power of the AC power system 202 may be directly supplied to the main circuit section 212.

The power conversion device 200 converts three-phase AC power supplied from the AC power system 202 into DC power, and supplies the converted DC power to the DC transmission lines 203 and 204. The power conversion device 200 also converts DC power supplied from the DC transmission lines 203 and 204 into three-phase AC power, and supplies the converted three-phase AC power to the AC power system 202. In this way, the power conversion device 200 performs AC-to-DC conversion from AC to DC, and from DC to AC.

For example, DC transmission line 203 is a high-voltage side transmission line for DC power, and DC transmission line 204 is a low-voltage side transmission line for DC power. Power conversion device 200 outputs converted DC power to DC transmission lines 203 and 204 so that DC transmission line 203 side is high voltage and DC transmission line 204 side is low voltage.

The main circuit unit 212 is provided between the AC power system 202 and each of the DC transmission lines 203 and 204. The main circuit unit 212 converts three-phase AC power to DC power and converts DC power to three-phase AC power. The main circuit unit 212 is, for example, a multilevel power converter having multiple converters connected in series. The main circuit unit 212 is, for example, an MMC (Modular Multilevel Converter) type power converter. The MMC type main circuit unit 212 has multiple converters connected in series. Each converter has multiple switching elements connected in half-bridge or full-bridge connection, and a charge storage element connected in parallel to each switching element. The main circuit unit 212 converts power by the operation of the multiple converters. The main circuit unit 212 converts AC to DC by, for example, switching each switching element of the multiple converters.

The control device 214 controls the operation of the main circuit section 212. The optical signal transmitting/receiving device 216 communicates between the main circuit section 212 and the control device 214. The control device 214 communicates with the main circuit section 212 via the optical signal transmitting/receiving device 216, and controls the on/off of each switching element to control the conversion of three-phase AC power to DC power and the conversion of DC power to three-phase AC power by the main circuit section 212.

The main circuit section 212 has a pair of first and second DC terminals 220a, 220b, three AC terminals (first to third) 221a to 221c, and six arm sections (first to sixth) 222a to 222f.

The first DC terminal 220a is connected to the high-voltage side DC transmission line 203. The second DC terminal 220b is connected to the low-voltage side DC transmission line 204. As a result, the DC power converted by the main circuit unit 212 is supplied to the DC transmission lines 203 and 204, and the DC power supplied from the DC transmission lines 203 and 204 is input to the main circuit unit 212.

The first arm portion 222a is connected to the first DC terminal 220a. The second arm portion 222b is connected between the first arm portion 222a and the second DC terminal 220b. The first arm portion 222a and the second arm portion 222b are connected in series between the DC terminals 220a and 220b.

The third arm portion 222c is connected to the first DC terminal 220a. The fourth arm portion 222d is connected between the third arm portion 222c and the second DC terminal 220b. The third arm portion 222c and the fourth arm portion 222d are connected in parallel to the first arm portion 222a and the second arm portion 222b.

The fifth arm portion 222e is connected to the first DC terminal 220a. The sixth arm portion 222f is connected between the fifth arm portion 222e and the second DC terminal 220b. That is, the fifth arm portion 222e and the sixth arm portion 222f are connected in parallel to the first arm portion 222a and the second arm portion 222b, and are connected in parallel to the third arm portion 222c and the fourth arm portion 222d.

In the main circuit unit 212, the first leg LG1 is formed by the first arm portion 222a and the second arm portion 222b, the second leg LG2 is formed by the third arm portion 222c and the fourth arm portion 222d, and the third leg LG3 is formed by the fifth arm portion 222e and the sixth arm portion 222f. That is, in this example, the main circuit unit 212 is a three-phase inverter with three legs and six arms. The first arm portion 222a, the third arm portion 222c, and the fifth arm portion 222e are upper arms. The second arm portion 222b, the fourth arm portion 222d, and the sixth arm portion 222f are lower arms. In this way, the main circuit unit 212 has a plurality of arms and a plurality of legs formed by a plurality of switching elements. The main circuit unit 212 may be, for example, a single-phase inverter with two legs and four arms. The number of arms and legs is not limited to the above and can be any number.

The first arm section 222a has a plurality of converters UP1, UP2... _UPM1 connected in series. The second arm section 222b has a plurality of converters UN1, UN2... _UNM2 connected in series. The third arm section 222c has a plurality of converters VP1, VP2... _VPM3 connected in series. The fourth arm section 222d has a plurality of converters VN1, VN2... _VNM4 connected in series. The fifth arm section 222e has a plurality of converters WP1, WP2... _WPM5 connected in series. The sixth arm section 222f has a plurality of converters WN1, WN2... _WNM6 connected in series.

However, in the following, when referring to the converters UP1, UP2... _UPM1 , UN1, UN2... _UNM2 , VP1, VP2... _VPM3 , VN1, VN2... _VNM4 , WP1, WP2... _WPM5 , and WN1, WN2... _WNM6 collectively, they will be referred to as "converter CEL".

In each of the arm sections 222a to 222f, _M1 , _M2 , _M3 , _M4 , _M5 , and _M6 represent the number of converters CEL connected in series. In each of the arm sections 222a to 222f, the number of converters CEL connected in series is, for example, about 100 to 120. However, the number of converters CEL connected in series is not limited to this and may be any number.

The number of converters CEL provided in each arm section 222a to 222f is substantially the same. For example, when multiple converters CEL are connected, the number of converters CEL provided in each arm section 222a to 222f may differ as long as it does not affect the operation of the main circuit section 212. For example, when 100 converters CEL are connected in series to one arm section, the number of converters CEL provided in another arm section may differ by one or two.

Each of the arm sections 222a to 222f further includes a buffer reactor 223a to 223f and a plurality of current detectors 224a to 224f. The power conversion device 200 further includes a voltage detection section 225.

Each of the buffer reactors 223a to 223f is connected in series to each converter CEL in each of the arm sections 222a to 222f. The buffer reactor 223a of the first arm section 222a is provided between the connection point between the first arm section 222a and the second arm section 222b and the converter UP1. The buffer reactor 223b of the second arm section 222b is provided between the connection point between the first arm section 222a and the second arm section 222b and the converter UN1. The buffer reactor 223c of the third arm section 222c is provided between the connection point between the third arm section 222c and the fourth arm section 222d and the converter VP1. The buffer reactor 223d of the fourth arm section 222d is provided between the connection point between the third arm section 222c and the fourth arm section 222d and the converter VN1. The buffer reactor 223e of the fifth arm portion 222e is provided between the connection point between the fifth arm portion 222e and the sixth arm portion 222f and the converter WP1. The buffer reactor 223f of the sixth arm portion 222f is provided between the connection point between the fifth arm portion 222e and the sixth arm portion 222f and the converter WN1.

The current detector 224a is provided in the first arm portion 222a and detects the current flowing through the first arm portion 222a. That is, the current detector 224a detects the arm current of the first arm portion 222a. The current detector 224a is connected to the control device 214 via wiring or the like (not shown). The current detector 224a inputs the detected current value of the first arm portion 222a to the control device 214. As a result, the current value of the first arm portion 222a is input to the control device 214.

Similarly, current detector 224b detects the current flowing through the second arm portion 222b and inputs the detected current value to the control device 214. Current detector 224c detects the current flowing through the third arm portion 222c and inputs the detected current value to the control device 214. Current detector 224d detects the current flowing through the fourth arm portion 222d and inputs the detected current value to the control device 214. Current detector 224e detects the current flowing through the fifth arm portion 222e and inputs the detected current value to the control device 214. Current detector 224f detects the current flowing through the sixth arm portion 222f and inputs the detected current value to the control device 214.

The voltage detection unit 225 detects the AC voltage (phase voltage) of each phase of the AC power system 202 and inputs the detected value to the control device 214. The voltage detection unit 225 may be connected to the primary side or the secondary side of the transformer 206.

In the main circuit section 212, the connection point between the first arm section 222a and the second arm section 222b, the connection point between the third arm section 222c and the fourth arm section 222d, and the connection point between the fifth arm section 222e and the sixth arm section 222f are each an AC output point.

The first AC terminal 221a is connected to the connection point between the first arm portion 222a and the second arm portion 222b. The second AC terminal 221b is connected to the connection point between the third arm portion 222c and the fourth arm portion 222d. The third AC terminal 221c is connected to the connection point between the fifth arm portion 222e and the sixth arm portion 222f. Each of the AC terminals 221a to 221c is connected to, for example, a transformer 206.

Each converter CEL communicates with the control device 214, for example, via the optical signal transmission/reception device 216. The control device 214 controls the operation of the converter CEL by inputting a control signal to the converter CEL via the optical signal transmission/reception device 216. The converter CEL also inputs, for example, control signals and protection signals related to the control and operation protection of the converter CEL to the control device 214 via the optical signal transmission/reception device 216. Note that the communication method between the control device 214 and each converter CEL is not limited to the above. For example, multiple converters CEL connected in series may be daisy-chained, and the control device 214 may communicate only with the converter CEL at one end of the daisy-chain and the converter CEL at the other end. The communication method between the control device 214 and each converter CEL may be any communication method that can appropriately communicate between the control device 214 and each converter CEL.

FIG. 5 is a block diagram that illustrates a schematic representation of a converter.
As shown in FIG. 5, the converter CEL has a plurality of switching elements 241, 242, a plurality of rectifying elements 251, 252, a plurality of driving circuits 261, 262, a pair of connecting terminals 271, 272, a charge storage element 274, a power supply circuit 276, a voltage detection circuit 278, and a control circuit 280.

Each of the switching elements 241 and 242 may be the same as the switching elements 111 to 116 of the second embodiment. Therefore, a detailed description of the element configuration of each of the switching elements 241 and 242 will be omitted.

A pair of main terminals of the switching element 242 is connected in series to a pair of main terminals of the switching element 241. In this example, the converter CEL has two switching elements 241 and 242 connected in series. In this example, the converter CEL is a converter in a half-bridge configuration.

The rectifier element 251 is connected in anti-parallel to a pair of main terminals of the switching element 241. The forward direction of the rectifier element 251 is opposite to the direction of the current flowing between the pair of main terminals of the switching element 241. Similarly, the rectifier element 252 is connected in anti-parallel to a pair of main terminals of the switching element 242. The rectifier elements 251 and 252 are so-called freewheel diodes.

The connection terminal 271 is connected between the switching element 241 and the switching element 242. The connection terminal 272 is connected to the main terminal of the switching element 241 opposite to the main terminal connected to the switching element 242.

The multiple converters CEL in the same arm are connected in series via a pair of connection terminals 271, 272. Power is supplied to the converters CEL via each of the connection terminals 271, 272. The switching element 241 is a so-called low-side switch, and the switching element 242 is a so-called high-side switch.

The control circuit 280 communicates with the control device 214 via the optical signal transmission/reception device 216. The control device 214 transmits a control signal for controlling the on/off of each switching element 241, 242 to the control circuit 280 via the optical signal transmission/reception device 216. The control circuit 280 inputs a drive signal for switching the on/off of each switching element 241, 242 to the drive circuits 261, 262 based on the input control signal.

The drive circuit 261 is connected to the control terminal of the switching element 241. The drive circuit 262 is connected to the control terminal of the switching element 242. The drive circuits 261, 262 switch the on/off of each switching element 241, 242 based on the drive signal input from the control circuit 280. This controls the on/off of each switching element 241, 242 in response to a control signal from the control device 214. The control device 214 generates a control signal for each converter CEL and controls the on/off of each switching element 241, 242 of each converter CEL. This allows the control device 214 to control the conversion of power by the main circuit unit 212.

The configuration of the drive circuits 261, 262 and the control circuit 280 is not limited to the above, and may be any configuration capable of controlling the on/off of each switching element 241, 242. For example, a control signal from the control device 214 may be input directly to the drive circuits 261, 262. In this case, the control circuit 280 can be omitted.

The charge storage element 274 is connected in parallel to the switching element 241 and the switching element 242. The charge storage element 274 is, for example, a capacitor.

When switching element 241 is in the OFF state and switching element 242 is in the ON state, the voltage of charge storage element 274 appears between each connection terminal 271, 272. When switching element 241 is in the ON state and switching element 242 is in the OFF state, each connection terminal 271, 272 is conductive, and the voltage between each connection terminal 271, 272 is substantially zero.

In this way, the converter CEL switches between an output state in which the voltage of the charge storage element 274 is output between each of the connection terminals 271 and 272, a bypass state in which the connection terminals 271 and 272 are conductive, and a stop state in which the switching elements 241 and 242 are turned off, by switching each of the switching elements 241 and 242 based on a control signal from the control device 214.

In each arm section 222a to 222f, the total voltage of the converters CEL that are in the output state becomes the voltage of the arm section 222a to 222f. The main circuit section 212 and the control device 214 perform multi-level power conversion by controlling the number of converters CEL that are in the output state.

When both switching elements 241, 242 are in the off state (when converter CEL is in the stopped state), the voltage between each connection terminal 271, 272 is determined by the direction of the arm current. For example, when the arm current flows from connection terminal 272 to connection terminal 271, rectifier element 251 turns on, and the voltage between each connection terminal 271, 272 becomes substantially zero. Conversely, when the arm current flows from connection terminal 271 to connection terminal 272, rectifier element 252 turns on, charge storage element 274 is charged, and the voltage of charge storage element 274 appears between each connection terminal 271, 272.

The power supply circuit 276 is connected in parallel to the charge storage element 274. The power supply circuit 276 generates a drive power supply for the drive circuits 261, 262 and the control circuit 280 based on the charge stored in the charge storage element 274, and supplies the generated drive power supply to the drive circuits 261, 262 and the control circuit 280. The drive circuits 261, 262 and the control circuit 280 operate in response to the supply of drive power from the power supply circuit 276.

The method of supplying power to the drive circuits 261, 262 and the control circuit 280 is not limited to the above. For example, power may be supplied to the drive circuits 261, 262 and the control circuit 280 from a power source separate from the charge storage element 274. The method of supplying power to the drive circuits 261, 262 and the control circuit 280 may be any method that can appropriately supply power to the drive circuits 261, 262 and the control circuit 280.

The voltage detection circuit 278 is connected in parallel to the charge storage element 274. The voltage detection circuit 278 is connected to the control circuit 280. The voltage detection circuit 278 detects the DC voltage of the charge storage element 274 and inputs the voltage detection value of the DC voltage of the charge storage element 274 to the control circuit 280.

The optical signal transmitting/receiving device 216, like the optical signal transmitting/receiving device 10 of the first embodiment, has an optical transmitting unit 11, an optical transmission path 12, an optical receiving unit 13, an emission control unit 14, and a light receiving control unit 15. The configurations of the optical transmitting unit 11, the optical transmission path 12, the optical receiving unit 13, the emission control unit 14, and the light receiving control unit 15 are substantially the same as those described in relation to the first embodiment, and therefore detailed description will be omitted.

The light emission control unit 14 is connected to the main circuit unit 212. The light reception control unit 15 is connected to the control device 214. This allows the optical signal transmission/reception device 216 to transmit a signal from the main circuit unit 212 to the control device 214. The optical signal transmission/reception device 216 also has another optical transmission unit, an optical transmission path, an optical reception unit, etc., which are not shown, and also allows the transmission of a signal from the control device 214 to the main circuit unit 212. The optical signal transmission/reception device 216, for example, allows two-way communication between the main circuit unit 212 and the control device 214 while electrically insulating the main circuit unit 212 and the control device 214. However, the optical signal transmission/reception device 216 does not necessarily have to allow two-way communication.

The control device 214 transmits a control signal to each converter CEL of the main circuit unit 212 via the optical signal transmitting/receiving device 216. The control signal is, for example, a control signal for controlling the switching of each switching element 241, 242 by repeating a high voltage state and a low voltage state at a predetermined cycle and changing the ratio of the high voltage state and the low voltage state. The control signal is, for example, a control signal for PWM control. The control signal is, for example, a digital signal.

The control circuit 280 of each converter CEL switches each switching element 241, 242 on and off based on a control signal input from the control device 214. The control device 214 transmits a control signal to the control circuit 280 of each converter CEL via the optical signal transmitting/receiving device 216, and controls the switching of each switching element 241, 242, thereby controlling the power conversion by the main circuit unit 212.

The control circuit 280 of each converter CEL switches between the on and off states of each switching element 241, 242 by changing the magnitude of the voltage at the control terminal of each switching element 241, 242 in response to a control signal input from the control device 214. The magnitude of the voltage of the control signal, the magnitude of the voltage at the control terminal of each switching element 241, 242, and the on/off relationship of each switching element 241, 242 can be the same as those described for the second embodiment above.

The optical signal transmitting/receiving device 216 has, for example, a plurality of optical transmitting units 11, a plurality of optical transmission paths 12, a plurality of optical receiving units 13, a plurality of light emission control units 14, and a plurality of light reception control units 15, each of which is provided corresponding to each of the converters CEL. The plurality of light emission control units 14 are, for example, connected to the respective control circuits 280 of each of the converters CEL. The signals output from the respective control circuits 280 of each of the converters CEL are input to the control device 214 via the optical signal transmitting/receiving device 216.

The control circuit 280 of each converter CEL, for example, repeats a high voltage state and a low voltage state at a predetermined cycle, and inputs a heartbeat signal to each light emission control unit 14 as a first input signal so that the control device 214 can detect an abnormality in each converter CEL. The heartbeat signal is, for example, a digital signal.

The control circuit 280 of each converter CEL measures, for example, the voltage of the control terminal of each switching element 241, 242, and inputs a feedback signal corresponding to the measurement result of the voltage of the control terminal to each light emission control unit 14 as a second input signal. The feedback signal is, for example, a signal that repeats a high voltage state and a low voltage state at a predetermined cycle and changes the ratio of the high voltage state to the low voltage state. The feedback signal is, for example, a PWM signal. The feedback signal is, for example, a digital signal. In other words, the feedback signal is a signal that allows the control device 214 to check whether the control signal has been appropriately input to the control terminal of each switching element 241, 242.

In other words, the main circuit unit 212 repeats a high voltage state and a low voltage state at a predetermined cycle, and inputs a heartbeat signal to the light emission control unit 14 as a first input signal so that the control device 214 can detect an abnormality in the main circuit unit 212. The main circuit unit 212 then measures the voltage of the control terminals of each switching element 241, 242, and inputs a feedback signal corresponding to the measurement result of the control terminal voltage to the light emission control unit 14 as a second input signal. As described with respect to FIG. 2 of the first embodiment above, the cycle of the feedback signal (control signal) is longer than the cycle of the heartbeat signal. In other words, the cycle T2 of the second input signal is longer than the cycle T1 of the first input signal.

As a result, the power conversion device 200 according to this embodiment can transmit two signals, a first input signal and a second input signal, over a single optical transmission path 12. Therefore, the power conversion device 200 can transmit and receive multiple signals with different frequencies with a simpler configuration than, for example, a case in which two optical transmitters 11, two optical transmission paths 12, and two optical receivers 13 corresponding to the two signals are provided.

In addition, in the power conversion device 200, for example, a plurality of optical transmitters 11, a plurality of optical transmission paths 12, a plurality of optical receivers 13, a plurality of light emission control units 14, and a plurality of light reception control units 15 are provided corresponding to each of the plurality of converters CEL. In this case, by making it possible to transmit two signals, the first input signal and the second input signal, through one optical transmission path 12, the number of optical transmission paths 12 can be further reduced, and the increase in the number of parts of the power conversion device 200 can be further suppressed. In the power conversion device 200 in which a large number of converters CEL are connected in series, the number of optical parts such as the optical transmitters 11, the optical transmission paths 12, and the optical receivers 13 is also large. Therefore, in such a power conversion device 200, by making it possible to transmit two signals, the first input signal and the second input signal, through one optical transmission path 12 as described above, the increase in the number of parts can be significantly suppressed. For example, the increase in cost due to the increase in optical parts can be significantly suppressed.

As in the second embodiment, the optical signal transmitting/receiving device 216 may be incorporated in the main circuit section 212 or the control device 214. In other words, the optical signal transmitting/receiving device 216 may be provided integrally with the main circuit section 212 or may be provided integrally with the control device 214. The optical signal transmitting/receiving device 216 may be provided separately in the main circuit section 212 and the control device 214, for example, by providing the optical transmitting section 11 and the light emission control section 14 in the main circuit section 212 and the optical receiving section 13 and the light reception control section 15 in the control device 214. In other words, the optical signal transmitting/receiving device 216 may be provided partially in the main circuit section 212 (for example, each converter CEL) and partially in the control device 214. The configuration of the optical signal transmitting/receiving device 216 is not limited to the above, and may be any configuration that can appropriately perform communication between the main circuit section 212 and the control device 214.

In addition, in the MMC type main circuit section 212, the configuration of the converter CEL is not limited to a half-bridge circuit configuration, but may be a full-bridge circuit configuration having four switching elements connected in a full bridge.

In the third embodiment, an MMC type power converter is used for the main circuit unit 212. The main circuit unit 212 is not limited to the MMC type, and may be, for example, another type of power converter in which multiple converters CEL are connected in series.

The power conversion device 200 is not limited to DC transmission systems, but may also be applied to any other system requiring conversion from AC to DC and from DC to AC. The AC/DC conversion by the main circuit unit 212 is not limited to both AC to DC and DC to AC, but may be only AC to DC or DC to AC. The main circuit unit 212 may also be, for example, an AC-AC direct conversion circuit.

The main circuit section 212 may be configured, for example, with multiple arm sections in a star connection, delta connection, or matrix connection. The main circuit section 212 may be, for example, a modular matrix converter. The main circuit section 212 does not necessarily have to have multiple legs. It is sufficient for the main circuit section 212 to have at least multiple arm sections. The main circuit section 212 may be configured in any manner that allows power conversion. The power conversion device may be, for example, a frequency conversion device, a direct current transmission device, a reactive power compensation device, or a power flow control device.

In this way, the configuration of the main circuit unit is not limited to the three-phase two-level inverter configuration shown in the second embodiment above, but may be a configuration in which multiple converters CEL are connected in series. The configuration of the main circuit unit is not limited to a three-phase two-level inverter, but may be a single-phase two-level inverter, a single-phase three-level inverter, a three-phase three-level inverter, etc. The configuration of the main circuit unit is not limited to the configurations shown in each of the above embodiments, but may be any configuration that has a converter and converts power by the operation of the converter.

The above embodiment shows an example in which the optical signal transmission/reception device is applied to a power conversion device. The optical signal transmission/reception device is not limited to being used in a power conversion device, and may be used in any other device.

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims.

10...optical signal transmitting/receiving device, 11...optical transmitting unit, 12...optical transmission path, 13...optical receiving unit, 14...light emission control unit, 15...light reception control unit, 20...exclusive OR circuit, 30...one-shot circuit, 32...filter circuit, 100...power conversion device, 101...main circuit unit, 101a...converter, 102...control device, 104...optical signal transmitting/receiving device, 111-116...switching elements, 121-126...rectifying elements, 130...charge storage elements, 131-136...drive circuits, 200...power conversion device, 202...AC power system, 203, 204...DC transmission line, 206...transformer, 212...main circuit unit, 214...control device, 216...optical signal transmitting/receiving device, 220a...first DC terminal, [0033] 220b...second DC terminal, 221a...first AC terminal, 221b...second AC terminal, 221c...third AC terminal, 222a...first arm portion, 222b...second arm portion, 222c...third arm portion, 222d...fourth arm portion, 222e...fifth arm portion, 222f...sixth arm portion, 223a to 223f...buffer reactor, 224a to 224f...current detector, 225...voltage detection portion, 241, 242...switching element, 251, 252...rectifier element, 261, 262...drive circuit, 271, 272...connection terminal, 274...charge storage element, 276...power supply circuit, 278...voltage detection circuit, 280...control circuit, CEL...converter, LG1...first leg, LG2: 2nd leg, LG3: 3rd leg

Claims (7)

an optical transmitter for transmitting an optical signal;
an optical transmission line connected to the optical transmitter;
an optical receiving unit connected to the optical transmitting unit via the optical transmission line, receiving the optical signal, and converting the optical signal into an electrical signal having a magnitude corresponding to an amount of light emitted from the optical signal, thereby outputting a received signal of the electrical signal;
a light emission control unit that receives a first input signal having a predetermined frequency and a second input signal having a frequency lower than that of the first input signal, generates a superimposed signal by superimposing the second input signal on the first input signal, and inputs the superimposed signal to the optical transmission unit, thereby causing the optical transmission unit to transmit the optical signal corresponding to the superimposed signal;
a light-receiving control unit that generates a first restored signal corresponding to the first input signal and a second restored signal corresponding to the second input signal by restoring the first input signal and the second input signal based on the received signal output from the optical receiving unit;
An optical signal transmitting and receiving device comprising: the first input signal and the second input signal are digital signals having a low voltage state and a high voltage state,
2. The optical signal transmitting and receiving device according to claim 1, wherein the light emission control unit has an exclusive-OR circuit that generates the superimposed signal, which is a digital signal, from the first input signal and the second input signal by calculating the exclusive-OR of the first input signal and the second input signal, which are input digital signals. the first input signal and the second input signal are signals that repeat a high voltage state and a low voltage state at a predetermined cycle,
The period of the second input signal is longer than the period of the first input signal,
the light receiving control unit has a one-shot circuit and a filter circuit, and inputs a reception signal output from the light receiving unit to each of the one-shot circuit and the filter circuit;
the one-shot circuit generates the first restored signal by outputting a pulse of a predetermined width in response to a change in the received signal;
the width of the pulse output by the one-shot circuit is set to be longer than the period of the first input signal and equal to or less than half the period of the second input signal;
3. The optical signal transmitting and receiving device according to claim 2, wherein the filter circuit generates the second restored signal by performing a process of attenuating a signal of a frequency component of the first input signal contained in the received signal and passing a signal of a frequency component of the second input signal. A main circuit unit having a converter and converting power by the operation of the converter;
A control device for controlling the operation of the main circuit unit;
an optical signal transmitting/receiving device for performing communication between the main circuit unit and the control device;
Equipped with
The optical signal transmitting and receiving device comprises:
an optical transmitter for transmitting an optical signal;
an optical transmission line connected to the optical transmitter;
an optical receiving unit connected to the optical transmitting unit via the optical transmission line, receiving the optical signal, and converting the optical signal into an electrical signal having a magnitude corresponding to an amount of light emitted from the optical signal, thereby outputting a received signal of the electrical signal;
a light emission control unit that receives a first input signal having a predetermined frequency and a second input signal having a frequency lower than that of the first input signal, generates a superimposed signal by superimposing the second input signal on the first input signal, and inputs the superimposed signal to the optical transmission unit, thereby causing the optical transmission unit to transmit the optical signal corresponding to the superimposed signal;
a light-receiving control unit that generates a first restored signal corresponding to the first input signal and a second restored signal corresponding to the second input signal by restoring the first input signal and the second input signal based on the received signal output from the optical receiving unit;
A power conversion device having the following: The converter has a switching element and performs power conversion by switching the switching element.
the light emission control unit is connected to the main circuit unit,
The light receiving control unit is connected to the control device,
the main circuit unit inputs a heartbeat signal as the first input signal to the light-emission control unit, and inputs a feedback signal as the second input signal to the light-emission control unit;
the heartbeat signal is a signal that repeats a high voltage state and a low voltage state at a predetermined cycle, and enables the control device to detect an abnormality in the main circuit unit;
the feedback signal is a signal that repeats a high voltage state and a low voltage state at a predetermined cycle and changes the ratio of the high voltage state to the low voltage state,
The power conversion device according to claim 4 , wherein a period of the feedback signal is longer than a period of the heartbeat signal. The converter includes a plurality of switching elements and a plurality of drive circuits that switch on and off the plurality of switching elements, and performs power conversion by switching the plurality of switching elements.
5. The power conversion device according to claim 4, wherein the optical signal transmitting/receiving device has a plurality of the optical transmitting units, a plurality of the optical transmission paths, a plurality of the optical receiving units, a plurality of the light emission control units, and a plurality of the light reception control units, each of which is provided corresponding to one of the plurality of driving circuits. the main circuit unit has a plurality of the converters connected in series,
Each of the plurality of converters comprises:
A pair of connection terminals;
A plurality of switching elements;
a charge storage element connected in parallel to the plurality of switching elements;
and the charge storage element is connected in series via the pair of connection terminals, and is capable of switching between an output state in which a voltage of the charge storage element is output between the pair of connection terminals, a bypass state in which the pair of connection terminals are electrically connected, and a stop state in which the plurality of switching elements are in an off state by switching the plurality of switching elements;
5. The power conversion device according to claim 4, wherein the optical signal transmitting/receiving device has a plurality of the optical transmitting units, a plurality of the optical transmission paths, a plurality of the optical receiving units, a plurality of the light emission control units, and a plurality of the light reception control units, each of which is provided corresponding to a plurality of the converters of the main circuit unit.

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