JP2000217398A - Generator - Google Patents

Abstract

[PROBLEMS] To connect a plurality of inverter devices in series or in parallel and to stabilize the output of each inverter device at that time. SOLUTION: A conduction angle detection unit 25 takes in the conduction angle of a thyristor included in a DC power supply of two inverter generators, that is, a converter. The larger of these conduction angles is extracted and input to the deviation detector 26. Deviation detector 26
Detects a deviation of the input value from the target conduction angle, and based on the deviation, a new target rotation speed is stored in the target rotation speed storage unit 2.
8 is set. The throttle control unit 32 controls the throttle opening so that the actual speed converges on the target speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a generator, and more particularly to a generator provided with a dual voltage inverter having two inverters.

[0002]

2. Description of the Related Art A generator having an inverter for converting a direct current into an alternating current having a desired frequency is known. Further, two inverters are provided for one generator and connected in parallel to each other. There is also known a generator that obtains twice as much electric power. For example, JP-A-8-205543
In the publication, an inverter operating device is described in which two inverter devices can be stably operated in parallel.

[0003]

By the way, there is a demand for obtaining a two-stage output voltage in the generator having the inverter device. In a generator having an inverter device, two types (two stages) of AC output voltages, for example, 120 volts and 240 volts, can be obtained by switching the output of the rectifier, that is, the DC voltage input to the inverter, into two stages. is there.

However, when the DC voltage is switched in two stages as described above, the withstand voltage and the output current capacity of the inverter must correspond to the higher output voltage, that is, 240 volts in the above-described example. And so-called power components such as electrolytic capacitors and choke coils also increase in size.

Therefore, it is conceivable to obtain a two-stage AC output voltage by operating two inverters in series. FIG. 7 is a connection diagram when two inverters are connected in series to obtain an alternating current. As shown in FIG. 7, two-stage output voltages of 120 V and 240 V are obtained by serially connecting inverter devices A and B capable of outputting 120 V AC based on the electric power generated by the generator G. be able to. However, in such a series operation, the two inverter devices A and B depend on how to take a load.
Output may be out of balance.

[0006] When the generator is driven by the engine, a control method (referred to as "eco-throttle control") for adjusting the engine speed to an optimum value depending on the load may be adopted. For example, when the electronic governor is set so that this eco-throttle control is performed by the CPU of one of the inverter devices, if a large load is connected to an inverter device that is not the side where the electronic governor is provided, the balance between the two inverter devices will be lost and sufficient There is a problem that the output voltage cannot be secured.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a generator capable of obtaining a well-balanced two-stage output voltage when two inverter devices are connected.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems and to achieve the object, the present invention provides a converter circuit for converting alternating current to direct current by controlling conduction of a semiconductor rectifying element, and converting the direct current to a predetermined frequency. A generator having two systems of inverter devices each comprising an inverter circuit for converting into an alternating current, a generator body for generating the alternating current, an engine for driving the generator body, and one of the two systems of inverter devices. Master / slave setting means for determining the other as a slave, rectifying element driving means for controlling the conduction angle of the semiconductor rectifying element so that the output voltage of each converter circuit becomes a target value, and An conduction angle of the determined converter circuit is detected, and an engine for controlling the engine speed is controlled so that the detected conduction angle converges to a target value. There is a first feature in that comprising a down control unit.

According to the first feature, when the two inverter devices are connected and used, the engine speed is changed so that the conduction angle converges to a target value.
Therefore, for example, by setting the target value to 80% of the full opening, the generator can be operated with a margin of 20%.

The present invention also provides a power generation system having two inverter devices each including a converter circuit for converting an alternating current to a direct current by controlling conduction of a semiconductor rectifier and an inverter circuit for converting the direct current to an alternating current having a predetermined frequency. A generator main body for generating the AC, an engine for driving the generator main body, master / slave setting means for determining one of the two inverter devices as a master and the other as a slave, Rectifier driving means for controlling the conduction angle of the semiconductor rectifier so that the output voltage of each converter circuit becomes a target value; and conduction angle determination means for determining which of the conduction angles of the converter circuits is larger. And engine control means for controlling the engine speed such that the larger conduction angle converges to a target value. There are two features.

According to the second feature, the engine speed is controlled based on the inverter having the larger conduction angle, that is, the inverter having the larger load, of the two systems of inverters. Therefore, even when a large load is connected to the inverter device on which the engine control means is not provided, there is no possibility that a sufficient output voltage cannot be secured because the balance between the two inverter devices is lost.

Further, according to the present invention, the conduction angle determining means and the engine control means are set as control means of the inverter device determined as the master.
A third feature is that a communication port for transmitting the conduction angle on the slave side from the slave side to the conduction angle determination means provided on the master side is provided.

According to the third feature, the conduction angle of the semiconductor rectifying element in the side where the engine control means is not provided, that is, in the slave inverter device is communicated to the master through the communication port, and the master side determines the conduction angle. The processing is executed.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 is a sine-wave inverter generator (hereinafter simply referred to as “generator”) according to one embodiment of the present invention.
FIG. In the figure, a generator 1 includes an engine 2, a generator body 3 driven by the engine 2, two-system inverter devices 4 and 5 for converting the output of the generator body 3 into a sine wave, and an inverter device 4. , 5 are connected in series or in parallel. That is, the output terminals T41, T41 and T51, T51 of the inverter devices 4, 5 are drawn out to the external terminals T1, T2, T3 via the series / parallel switching unit 6.

The generator body 3 has a three-phase output winding (not shown) wound around a stator. A rotor (not shown) composed of a multi-pole permanent magnet is provided corresponding to the three-phase output winding, and the rotor is rotated by the engine 2.

The inverter device 4 includes a thyristor circuit 40
DC power supply circuit including converter 0a and capacitor 400b, ie, converter circuit 400, and inverter circuit 4
And a control section 41 for converting the output of the generator body 3 into a sine wave. Similarly, the inverter device 5 includes a thyristor circuit 50
DC power supply circuit 50 including capacitor 0a and capacitor 500b
0, a power unit including an inverter circuit 501 and a filter circuit 502, and a control unit 51 that converts the output of the generator body 3 into a sine wave.

Further, voltage detecting circuits 7, 8 for measuring output voltages and output currents of the inverter devices 4, 5 and current detecting circuits 9, 10 are provided. Control unit 41,
Reference numeral 51 denotes a microcomputer, which is connected to each other by the communication line 11. A control signal, a synchronization signal, and the like for operating the inverter devices 4 and 5 synchronously with each other are transmitted and received through the communication line 11.

Each of the thyristor circuits 400a and 500a has a thyristor, which is a semiconductor rectifier, assembled in a bridge, and rectifies a high-frequency three-phase alternating current input from the generator body 3 by controlling conduction of the thyristor. . The DC voltage obtained by the rectification is controlled by the conduction angle of the thyristors included in the thyristor circuits 400a and 500a. That is, when the output voltage of the converter circuit is lower than a preset target value, the conduction angle of the thyristor is increased. Capacitor 400b, 500b
Smoothes the output rectified by the thyristor circuits 400a and 500a.

One of the control units 41 and 51 operates as a master, and the other operates as a slave. The master / slave relationship is determined by setting a communication port in advance.
Let 1 be a slave. An electronic governor function for controlling the rotation of the engine 2 is provided in the control unit 41 serving as a master.

The inverter circuits 401 and 501 are connected to the control unit 4
DC voltage according to the reference waveform signal from
Modulate. Specifically, the four full-bridge-connected power MOSFETs are switched based on pulse signals from the control units 41 and 51. Inverter circuit 40
The output of 1,501 is a large power signal including a sine wave component.

Filter circuits 402 and 502 demodulate signals output from inverter circuits 401 and 501. Specifically, it is an LC low-pass filter composed of a choke coil and a capacitor. This filter circuit 40
The carrier wave component of the PWM modulation is removed by 2502, and a 50 Hz or 60 Hz sine wave is output.

The configuration of the control units 41 and 51 will be specifically described. FIG. 3 is a block diagram showing a main configuration of the control unit, and the same reference numerals as those in FIG. 2 indicate the same or equivalent parts. In addition,
Since the control units 41 and 51 have the same function except for a part, the configuration of the control unit 41 will be mainly described here. However, since the control units 41 and 51 have functions associated with each other, it is needless to say that both of them will be described with respect to that part.

In FIG. 3, the output of the engine 2 is controlled by the opening of the throttle 2a.
Is set by the stepping motor 2b.
The opening control of the throttle 2a will be described later with reference to FIG. The control unit 41 includes an oscillating unit 12, a frequency dividing circuit 13, a sine wave generating circuit 14, an electronic volume 15, a low-pass filter (LP
F) 16, a pulse width modulation circuit (PWM circuit) 17, a rectangular wave conversion circuit 18, a phase difference detection circuit 19, and a start-up circuit 20. As specific examples of these circuits, those disclosed in JP-A-5-244726 can be used.

The oscillating section 12 has a crystal oscillator for performing an original oscillation of, for example, 5 MHz. The original oscillation is frequency-divided by a frequency dividing circuit 13 and inputted to a sine wave circuit 14 as a clock signal. The sine wave generating circuit 14 generates a step-like sine wave signal based on the clock signal, and the sine wave signal is transmitted through the electronic volume 15 and the LPF 16 to the PWM circuit 17.
, And the pulse width-modulated pulse is output from the PWM circuit 17 using the sine wave signal as a target waveform signal.

The electronic volume 15 is, as described later,
In the case of overload, the attenuation of the sine wave signal is controlled, and the LPF 16 smoothes the step-like sine wave output from the electronic volume 15. In accordance with the pulse output from the PWM circuit 17, the gate of the power MOSFET forming the bridge of the inverter circuit 401 is controlled, and the alternating current corresponding to the sine wave signal of the reference frequency, which is the target waveform signal, is output from the output terminals T41 and T41. Is done.

The rectangular wave conversion circuit 18 converts the output signal of the LPF 16 into a square wave, and outputs the converted signal to the communication port 2
1 is input. The signal input to the communication port 21, that is, the reference sine wave clock is input to the communication port of the other inverter device 5 through the communication line 11. The phase difference detection circuit 19 is connected to the inverter device 5 through the communication port 21.
, The reference sine wave clock received from the input terminal, and its own reference sine wave clock is input from the square wave conversion circuit 18.

The phase difference detection circuit 19 compares the phase of the reference sine wave clock of the inverter device 4 with the phase of the reference sine wave clock of the inverter device 5 to detect the advance or delay of the phase, and advances the detection result. The signal is input to the oscillation unit 12 as a phase signal or a delayed signal. When the phase is advanced, based on the leading signal or the retarding signal, the oscillating unit 12 thins out the reference sine wave clock every predetermined period (for example, 1 kHz) by a predetermined number of pulses (for example, one pulse) to slightly increase the frequency. On the other hand, when the phase is delayed, the frequency is slightly reduced by adding a predetermined number of pulses (for example, one pulse) to the reference sine wave clock. This frequency adjustment is performed by both the inverter devices 4 and 5. That is, two inverter devices 4, 5
Are controlled so as to approach each other and adjust the output.

The start circuit 20 includes a start determination circuit 2
When the detection signal from the control circuit 2 is input, the PWM circuit 17 is energized, and the inverter circuit 401 is driven to generate power.
That is, the start-up circuit 20 outputs a start-up signal to the PWM circuit 17 in response to the rise of the reference sine wave clock when the inverter devices 4 and 5 have completed the power generation preparation. Further, the starting circuit 20 detects the rising of the reference sine wave clock input from the inverter device 5 based on the reference sine wave clock, and outputs a starting signal to the sine wave generating circuit 14.

The start possible / impossible judgment circuit 22 outputs a detection signal indicating that the power generation preparation is completed when the rotation speed of the engine 2 and / or the power supply voltage of the inverter devices 4 and 5 reach a predetermined value and the reference sine wave clock is synchronized. Output. Completion of the power generation preparation of the inverter device 5 is determined by a signal (described later) input from the communication port 21. The start possibility determination circuit 22 outputs a generator ready completion detection signal to the communication port 21 when both the output voltage and the engine speed detected by the voltage detection circuit 7 reach predetermined values.

The comparison circuit 23 outputs a detection signal when the current detected by the current detection circuit 9 is larger than the threshold value.
The detection signal is sent to the electronic volume 15 and the protection circuit 24.
Is input to The protection circuit 24 has a timer that is activated in response to the detection signal from the comparison circuit 23, and outputs an overload detection signal to the activation circuit 20 after the timer times out. The electronic volume 15 controls the attenuation of the sine wave signal in response to the overload detection signal.

Next, the electronic governor, that is, the output control function of the engine will be described. The electronic governor is realized as a function of the control unit 41 designated as a master. FIG.
FIG. 2 is a block diagram illustrating functions of an electronic governor. In thyristor circuits 400a and 500a, the conduction angle of the thyristor is controlled by thyristor driving means (not shown) so that the output voltage of converter circuit 400 or 500 becomes the target output voltage. The conduction angle of the thyristor circuit 400a of the DC power supply circuit 400 and the conduction angle of the thyristor circuit 500a of the DC power supply circuit 500 are input to the conduction angle detection unit 25. The conduction angle of the thyristor circuit 500a of the slave device, that is, the thyristor circuit 500a of the inverter device 5 is communicated to the master device, that is, the inverter device 4 via the communication line 11, and is input to the conduction angle detection unit 25. The conduction angle is continuously detected at a predetermined cycle, and the average is calculated. It is preferable that the average conduction angle is a moving average of continuous data of predetermined times (for example, 10 times). The conduction angle detector 25 determines the magnitude of the load factor based on the magnitude of the conduction angle. The conduction angle detector 25 compares the conduction angles of the master and the slave with each other, and outputs the larger one as the detected conduction angle. As a result, the engine output is controlled in accordance with the higher load factor of the inverter devices 4 and 5.

The conduction angle detected by the conduction angle detector 25 is input to a deviation detector 26, which detects a deviation from the target conduction angle. That is, based on this deviation, it is determined whether or not the generator 1 is operated in a state where the output has a margin. For example, the target conduction angle is set to 80%. This target conduction angle should have a constant hysteresis, like a general control target value. Note that the target conduction angle may be a fixed value, or may be variable according to the temperature of the engine 2 or the like. For example, when the temperature of the engine 2 is low, the target conduction angle is smaller than when the temperature of the engine 2 is high. Thus, the rotation speed of the engine 2 is controlled so that the deviation detected by the deviation detecting unit 26 becomes “0”, and the state where the generator 1 has a margin is maintained.

The target rotation speed updating section 27 outputs the rotation speed adjustment amount, and can be constituted by a table storing the rotation speed adjustment amount corresponding to the deviation. The rotation speed adjustment amount is stored in the target rotation speed storage unit 2
Enter 8 The target rotation speed storage unit 28 adds the rotation speed adjustment amount input from the target rotation speed update unit 27 to the already stored target rotation speed to obtain a new target rotation speed.

The target rotational speed is updated within the range of the maximum rotational speed and the minimum rotational speed set in the limit rotational speed setting section 29. When the target rotation speed is out of this range, the target rotation speed is limited to the maximum rotation speed or the minimum rotation speed. Note that the minimum rotation speed is specified so that the conduction angle of the thyristor does not impair stability under no load or light load by reacting to a slight change in rotation speed.

The rotation speed detecting section 30 detects the rotation speed of the generator body 3. The control amount calculation unit 31 sets the deviation of the actual rotation speed from the target rotation speed to “0” based on the actual rotation speed input from the rotation speed detection unit 30 and the target rotation speed read from the target rotation speed storage unit 28. Is calculated by a known appropriate method (for example, proportional / integral / differential). The throttle control unit 32 supplies the stepping motor 2b with a number of pulses corresponding to the calculation result of the control amount calculation unit 31. The stepping motor 2b rotates according to the number of supplied pulses, and changes the opening of the throttle 2a.

When the throttle 2a is fully opened and the engine output has no margin, the engine 2 stops. To prevent this, the amplitude of the inverter circuits 401 and 501 is limited when the throttle is fully opened. preferable. Therefore, the amplitude is limited as follows. A full-open detector 33 for monitoring the opening of the throttle 2a is provided.
The full-open detector 33 outputs a detection signal to the amplitude limiter 34 when the throttle opening is fully open. The amplitude limiter 34 sends a limit signal to the electronic volume 15, and the electronic volume 15 responds to the limit signal to
1 is limited to a preset limit value. Further, the amplitude limiter 34 inputs a limit signal to a predetermined port of the communication port 21 in order to limit the amplitude of the slave circuit, that is, the inverter circuit 501 of the inverter device 5. This restriction signal is transmitted to the communication port 21a of the inverter device 5 through the communication line 11, and is taken into the control unit 51.

FIG. 4 is a diagram showing the correspondence between the communication ports of the inverter devices 4 and 5. In the figure, a communication port 21 of the inverter device 4 and a communication port 21a of the inverter device 5 transmit and receive a reference sine wave clock,
Green light emitting diode (LED) light transmission and reception, red LE
It has D light transmission and reception, amplitude limited transmission and reception, conduction angle transmission and reception ports, and a master / slave setting port, a common (COM) port, and a ground (GND) port. As shown in the figure, the inverter device 4 is set as a master and the inverter device 5 is set as a slave here. These ports are communication lines 11
Are connected as described above.

The green and red LED light transmission / reception ports are used to communicate the operating states of the inverter devices 4 and 5 to the other in the light emitting state of the green LED and the red LED. Green LE when inverter device 5 is not ready for power generation
Both D and the red LED are low (unlit) and high (lit) when power generation preparation is completed or when power is generated. When an overload is detected, the red LED is turned on.

Inverter device 4 and inverter device 5
When both of them have completed the power generation preparation, the start possibility determination circuit 22 notifies the activation circuit 20 of the completion of the power generation preparation and keeps the green LED on. That is, when the AND condition of the green LED output is satisfied, the power generation preparation is completed. When an overload is detected in any of the inverter devices 4 and 5 during power generation,
A start command is output from the starting circuit 20 to the PWM circuit 17. That is, when the OR condition of the red LED output is satisfied, the power generation is stopped.

Next, a power generation start process of the power generator will be described with reference to a flowchart of FIG. In FIG. 5, in step S1, it is determined whether or not the self (inverter device 4) is ready for power generation based on whether or not its own engine speed and / or power supply voltage exceeds a predetermined value. If this determination is affirmative, the process proceeds to step S2 to determine whether or not the reference sine wave clock from the inverter device 5 has been detected. If this determination is affirmative, step S3
, And starts outputting its own (inverter device 4) reference sine wave clock in synchronization with the zero-cross point (starting point) of the reference sine wave clock of the inverter device 5, and then proceeds to step S6. When the reference sine wave clock from the inverter device 5 is not detected, the process proceeds to step S4 to start outputting the reference sine wave clock. In step S5, it is determined whether or not the reference sine wave clock from the inverter device 5 has been detected. If this determination is affirmative, step S
Proceed to 6.

In step S6, the inverter devices 4, 5
It is determined whether or not the phase difference of the reference sine wave clock is equal to or smaller than a predetermined value. If this determination is negative, the process proceeds to step S7, and the starting point is corrected by finely adjusting the frequency of the reference sine wave clock. When the starting point is corrected and the phase difference becomes equal to or less than the predetermined value, the process proceeds to step S8, and the green LED is turned on to display the completion of the power generation preparation. In step S9,
The state of the green LED light from the inverter device 5 is determined, and it is also determined whether the inverter device 5 is also ready for power generation. If step S9 is positive, the process proceeds to step S10,
A start command is output to the PWM circuit 17 in synchronization with the zero cross point (start point) of the reference sine wave clock.

Next, switching of the series / parallel connection of the inverter devices 4 and 5 will be described. FIG. 5 is a circuit diagram showing details of the series / parallel switching unit 6 of the inverter devices 4 and 5. In the figure, the series / parallel switching unit 6 can be constituted by a toggle switch. When the switch is switched to the contact a side, between the output terminals T1 and T2,
An output voltage (for example, 120 V) of the inverter device 4 is output, and the inverter device 5 is connected between the output terminals T2 and T3.
(For example, 120 V) is output, and as a result, an output voltage (240 V) that is twice the output voltage of the inverter devices 4 and 5 is obtained between the output terminals T1 and T3. That is, the inverter devices 4 and 5 are connected in series.

When the switch is switched to the contact b side, no voltage is output between the output terminals T1 and T2, and the output voltage of the inverter devices 4 and 5 is applied only between the output terminals T2 and T3. (For example, 120 V) is output. As a result, the output voltage (120 V) of each of the inverter devices 4 and 5 is output as it is between the output terminals T2 and T3, and the output (for example, 2 kW) is doubled (4 k
W). That is, the inverter devices 4 and 5
Are connected in parallel.

When two inverters are connected in parallel, the phase difference between the output voltages of the other inverters is detected based on the phase difference between the output voltage and the output current of the inverter, and the output frequency is changed. A generator that eliminates the phase difference or falls within the predetermined range is disclosed in more detail in a previous patent application filed by the present applicant (see JP-A-5-244726).

[0045]

As is apparent from the above description, according to the first aspect of the present invention, eco-throttle control can be realized in a generator having two inverter systems. According to the second and third aspects of the present invention, in the generator having two inverter systems, the conduction angle of the larger load is controlled so as to converge to the target value. A well-balanced power generation can be performed even when an electronic governor including an engine speed control means is provided in any one of the above, and it is possible to cope with various loads when two systems of inverter devices are connected in series. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an electronic governor of a generator according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating an entire configuration of a generator according to an embodiment of the present invention.

FIG. 3 is a block diagram showing main functions of a control device of the generator according to the embodiment of the present invention.

FIG. 4 is a diagram illustrating a configuration example of a communication port.

FIG. 5 is a diagram illustrating a connection example of a series / parallel switching unit.

FIG. 6 is a flowchart showing start control of the inverter circuit.

FIG. 7 is a schematic diagram of two series inverter devices connected in series.

[Explanation of symbols]

1 ... generator, 2 ... engine, 3 ... generator body,
4, 5 ... inverter device, 6 ... series / parallel switching unit,
7, 8 ... voltage detection circuit, 9, 10 ... current detection circuit,
11: communication line, 21, 21a: communication port, 25:
Conduction angle detection unit, 30: rotation speed detection unit, 31: control amount calculation unit, 400: converter

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) FB02 FB05 FC14 FC15 FC22 FC26 GA02 GA06 GA10 GB05 HA01 HA02 HA04 HA10 HA18 HA27 HB14 HB18 JA02 JA06 JA08 JA12 JA13 JA14 JA19 JB02 JB14 JB15 JB18 KK02

Claims (3)

[Claims] 1. A generator having two systems of inverter devices each comprising a converter circuit for converting an alternating current to a direct current by controlling conduction of a semiconductor rectifying element and an inverter circuit for converting the direct current to an alternating current having a predetermined frequency. A generator body for generating alternating current; an engine for driving the generator body; master / slave setting means for determining one of the two inverter devices as a master and the other as a slave; A rectifier driving means for controlling the conduction angle of the semiconductor rectifier so that the output voltage of the converter becomes a target value; and detecting the conduction angle of the converter circuit on the side determined by the master, and detecting the conduction angle as the target value. And an engine control means for controlling the number of revolutions of the engine so as to converge. 2. A generator having two systems of an inverter device comprising a converter circuit for converting an alternating current into a direct current by controlling conduction of a semiconductor rectifying element and an inverter circuit for converting the direct current into an alternating current having a predetermined frequency. A generator body for generating alternating current; an engine for driving the generator body; master / slave setting means for determining one of the two inverter devices as a master and the other as a slave; Rectifier driving means for controlling the conduction angle of the semiconductor rectifier so that the output voltage of the semiconductor rectifier becomes a target value; conduction angle determination means for determining which of the conduction angles of the converter circuits is greater; Engine control means for controlling the number of revolutions of the engine such that the conduction angle of the engine converges to a target value. Generator. 3. The conduction angle judging means and the engine control means are set as control means of the inverter device determined as the master, and the conduction angle on the slave side is set from the slave side to the conduction side provided on the master side. 3. The generator according to claim 2, further comprising a communication port for transmitting to the angle determining means.