JP2016039749A - Non-contact power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact power transmission device enabling high energy transmission efficiency.SOLUTION: A non-contact power transmission device comprises: current measuring means 204 for measuring current occurring in a power reception circuit 20; power reception side communication means 206 for transmitting a current value obtained by the current measuring means 204 as a wireless signal to the outside; power transmission side communication means 114 for receiving the wireless signal from the power reception side communication means 206; frequency setting means 111 for obtaining the current value from the wireless signal received by the power transmission side communication means 114, and controls a switching frequency for generating AC voltage to be supplied to a power transmission coil 100; two switching pulse generation means 112a, 112b for outputting switching pulses for generating AC voltage to be supplied to the power transmission coil 100 on the basis of a command from the frequency setting means 111; and pulse switching means 113 for selecting any of output from the two switching pulse generation means.SELECTED DRAWING: Figure 1

Description

The present invention relates to a contactless power transmission apparatus that performs power transmission without contact.

As a non-contact power transmission device capable of efficiently transmitting energy, a device using electromagnetic resonance coupling is known (Patent Document 1). The electromagnetic resonance coupling means that objects having the same resonance frequency are coupled with each other by an electric field or a magnetic field in the resonance state, so that energy can be transmitted with high transmission efficiency.

In such a non-contact power transmission device using electromagnetic resonance coupling, the resonance frequency changes due to the gap between the opposing positions of the power transmission coil and the power reception coil and the difference in the air gap, which is the distance between the two. Efficiency could be degraded. (Patent Document 2)

Therefore, in Patent Document 1, a matching circuit is inserted on the power transmission side or the power reception side, impedance matching is performed, and energy transmission efficiency is deteriorated due to a change in the distance of the air gap between the coils or a change in the resonance frequency due to a positional deviation. The thing which was made to prevent is described. Further, in Patent Document 2, there are a plurality of power transmission units each having a power transmission coil corresponding to the positional deviation between the coils, and the power transmission coil having the highest power supply efficiency among them is selected. Is described.

JP 2012-130061 A JP 2014-103820 A

However, in the non-contact power transmission of Patent Document 1, since the matching circuit is inserted on the power transmission side or the power reception side, the circuit tends to be complicated. Also, the adjustment of impedance matching is complicated and the processing time is long. In the non-contact power transmission of Patent Document 2, a plurality of power transmission units are provided in the power transmission device to cope with the shift of the position where the power transmission coil and the power reception coil face each other. It was.

This invention makes it a subject to provide the non-contact electric power transmission apparatus which enables high energy transmission efficiency, without causing the enlargement and cost increase of an apparatus.

A non-contact power transmission apparatus according to the present invention is a non-contact power transmission apparatus that transmits power in a non-contact manner by electromagnetic resonance coupling between a power transmission coil of a power transmission circuit and a power reception coil of a power reception circuit, and is generated in the power reception circuit. Measuring means for measuring electrical parameters of the measured power, power receiving side communication means for transmitting the electrical parameters measured by the measuring means to the outside as a wireless signal, and power transmission side for receiving a wireless signal from the power receiving side communication means A frequency setting means for acquiring an electrical parameter from a wireless signal received by the power transmission side communication means and controlling a switching frequency for generating an AC voltage supplied to the power transmission coil based on the electrical parameter; Two or more switches that output a switching pulse for generating an AC voltage to be supplied to the power transmission coil based on the command of the frequency setting means. And Nguparusu generating means, either the output of two or more of the switching pulse generator comprises a pulse switching means for switching a switching pulse for generating the AC voltage supplied to the power transmission coil.

According to this configuration, the position where the power transmission coil and the power reception coil face each other is prevented from being displaced, the influence of the resonance frequency fluctuation due to the difference in the air gap is avoided, the resonance state is maintained, and power transmission is performed with high energy efficiency. Is possible.

It is a block diagram which shows the structure of embodiment of this invention. It is a perspective view which shows the example of arrangement | positioning of the power transmission coil and power receiving coil of this invention. It is a flowchart which shows the process of the power transmission side and the power receiving side control part. It is a flowchart which shows the process which sets the electric power transmission initial value by the side of power transmission. It is a flowchart which shows the process which determines the switching frequency on the power transmission side. It is an example of a graph which shows the relationship between the switching frequency resolution on the power transmission side, and the current value on the power reception side.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram illustrating a basic configuration of a contactless power transmission device 1 according to the embodiment. The contactless power transmission device 1 of the present invention includes a power transmission circuit 10 and a power reception circuit 20. The power transmission circuit 10 is connected to a DC power source 2 as a power source to be supplied, and the power receiving circuit 20 is connected to a load 3 that supplies the received power, such as an electric toothbrush or a charging device for a smartphone or a tablet terminal. The

As shown in FIG. 1, a power transmission circuit 10 includes a power transmission coil 100, a capacitor 101, an inverter circuit 102, a transformer 106 including a diode 106, an inductance 107, a smoothing capacitor 108, and a switching transistor 109, and a frequency setting. Unit 111, first pulse generation unit 112a and second pulse generation unit 112b, pulse switching unit 113, power transmission side infrared light emitting / receiving unit 115, power transmission side infrared communication module 114 including power transmission side infrared communication driver 116, voltage transformation It is comprised from the control part 117 and the power transmission side control part 118. FIG.

As shown in FIG. 2, the power transmission coil 100 is obtained by winding a conducting wire 152 around a plate-shaped magnetic core 151 in a plane. The capacitor 101 is connected in series with the power transmission coil 100 and constitutes a resonance circuit.

In the power transmission circuit 10, a desired DC voltage is generated by the transformer circuit 105 from the DC power supply 2 connected to the input terminals 119 and 120. This is realized by changing the cycle in which the gate current applied to the switching transistor 109 in FIG. 1 is repeatedly turned on and off. The change of the cycle is performed by the transformation control unit 117 and is controlled by a command from the power transmission side control unit 118.

The DC voltage generated by the transformer circuit 105 is converted into an AC voltage by the inverter circuit 102. The DC voltage fed from the transformer circuit 105 is converted into an AC voltage by an inverter circuit 102 configured by combining four switching MOSFETs (Metal 0xide Semiconductor Field Effect Transistors) 103a to 103d in a series-parallel bridge shape. .

When the switching MOSFETs 103a to 103d of the inverter circuit 102 are combined two at a time (103a and 103d and 103b and 103c) and controlled to conduct at different timings, an AC voltage is generated between points A and B in FIG. Occurs.

In order to change the amplitude of the alternating voltage or stop the generation, the time width of the switching pulse applied to the gates of the two sets of switching MOSFETs 103a, 103d and 103b, 103c is changed, or the applied switching pulse is stopped. Can be realized. Here, 104 is a smoothing capacitor.

The switching pulse applied to the gates of the two sets of switching MOSFETs 103a, 103d and 103b, 103c is one of the switching pulses generated by the first pulse generator 112a and the second pulse generator 112b. 113. The frequency of the switching pulse generated by the first pulse generator 112a and the second pulse generator 112b is set by the frequency setting unit 111.

The power transmission side infrared light receiving / emitting unit 115 exchanges data by wireless communication with a power receiving side infrared light receiving / emitting unit 207 described later.

In the power transmission side infrared communication driver 116, the power transmission side control unit 118 exchanges data with a power reception side control unit 210 described later via the power transmission side infrared light reception / emission unit 115 and the power reception side infrared light reception / emission unit 207. It is an interface part for.

The power transmission side control unit 118 includes a CPU, a RAM, a ROM, an I / O, and the like. As described above, the power transmission side control unit 118 generates the DC voltage required for the power supply desired by the load 3, so that the cycle command given to the switching transistor 109 by the voltage transformation control unit 117, the power transmission coil 100 and the capacitor A command for setting the switching frequency supplied to the resonance circuit composed of 101 in the frequency setting unit 111, and a power receiving circuit 20 via a power transmission side infrared communication module 114 composed of a power transmission side infrared light emitting / receiving unit 115 and a power transmission side infrared communication driver 116, Exchange data.

On the other hand, the power receiving circuit 20 includes a power receiving coil 200, a capacitor 201, a rectifier 202, a capacitor 203, a current measuring unit 204, a current monitoring resistor 205, a power receiving side infrared light emitting / receiving unit 207, and a power receiving side infrared communication driver. The power receiving side infrared communication module 206 including 208, the external output switch 209, and the power receiving side control unit 210 are configured.

As shown in FIG. 2, the power receiving coil 200 is obtained by winding a conductive wire 262 in a plane on a plate-like magnetic core 261. The capacitor 201 is connected in series with the power receiving coil 200 to form a resonance circuit.

The rectifier 202 rectifies the electric power from the power receiving coil 200 and converts it into a DC power source. The capacitor 203 is a smoothing and noise removing capacitor.

The current measuring unit 204 measures the potential difference generated at both ends of the current monitoring resistor 205, and detects the current value A supplied to the power receiving side based on the result.

The power receiving side control unit 210 includes a CPU, a RAM, a ROM, an I / O, and the like. In the power receiving side control unit 210, information on the power required by the load 3 (charging device such as an electric toothbrush, a smartphone, and a tablet terminal) connected to the output terminals 211 and 212 is stored in advance. Information on the power required by the load 3 and the current value A detected by the current measuring unit 204 are received via a power receiving side infrared communication module 206 including a power receiving side infrared light receiving and emitting unit 207 and a power receiving side infrared communication driver 208. Thus, data communication is performed with the power transmission side control unit 118 by wireless communication. Further, it controls the output changeover switch 209 that switches between execution and stop of power supply to the load 3.

Next, the operation of the non-contact power transmission apparatus according to the embodiment will be described based on flowcharts and graphs.

The flowcharts of FIGS. 3 to 5 show the control of the non-contact power transmission apparatus of this embodiment. The left side of the figure represents the processing of the power receiving side control unit 210, and the right side represents the processing of the power transmission side control unit 118.

In FIG. 3, the power transmission side control unit 118 is supplied to the inverter circuit 102 supplied by the voltage transformation control unit 117 that sets the DC voltage output from the voltage transformation circuit 105, and the first pulse generation unit 112a and the second pulse generation unit 112b. Initialization is performed by turning off the command given to the frequency setting unit 111 that determines the frequency of the switching pulse. (S101)

On the other hand, the power receiving side control unit 210 transmits, via the power receiving side infrared communication module 206, power supply conditions such as the amount of supplied power, the current value, and the voltage value that match the specifications of the load 3 to be fed to the power transmission side control unit 118. (S201). At this time, the power transmission side control unit 118 waits for a transmission notification from the power reception side control unit 210 via the power transmission side infrared communication module 114 (S102).

Regarding the infrared light receiving / emitting units (115, 207) used here, since the directivity of infrared rays is strong and the directivity angle is narrow, in order to establish communication, it is necessary that the optical axes coincide with each other sufficiently. Therefore, by aligning the optical axes so that the infrared transmission / reception units (115, 207) on the power transmission side and the power reception side can communicate with each other, the power transmission side infrared reception / emission unit 115, the power transmission coil 100, and the power reception side infrared reception / reception are performed. Since the physical positional relationship between the light emitting unit 207 and the power receiving coil 200 matches, as a result, the opposing positions between the coils (100, 200) can be matched. Therefore, establishment of infrared communication ensures that the power transmission coil 100 and the power reception coil 200 are in a positional relationship facing each other.

The power transmission side control unit 118 determines whether or not the received power supply condition to the load 3 can be supplied by the power transmission circuit 10, and if the condition is not possible ("NO" in S103), the process ends.

On the other hand, when the power supply condition is possible (“YES” in S103), initial setting is performed under a condition that matches the power to be transmitted (S104).

As an initial setting under conditions matching the transmission power, as shown in FIG. 4, first, a DC voltage required for power transmission is generated from the DC power source 2 by switching of the switching transistor 109. A control pulse to be input to is generated by the transformation control unit 117 (S150). Next, in order to determine the AC voltage applied to the power transmission coil 100, the frequency setting unit 111 sets the switching frequency fa of the first pulse generating unit 112a to the initial value f1 (S151), and the pulse switching unit 113 is set to the first. The pulse generator 112a is set (S152). Finally, the power transmission side control unit 118 transmits completion of initial setting of the power transmission circuit 10 to the power reception side infrared communication module 206 via the power transmission side infrared communication module 114, and notifies the power reception side control unit 210 (S153).

Returning to FIG. 3, the power receiving side control unit 210 waits until the initial setting completion is received from the power transmission side control unit 118 (“NO” in S202), but if there is no response within a predetermined time (“YES” in S203). ) Ends as it is. When there is a response (“YES” in S202), the current measuring unit 204 measures the current value A after the power receiving coil 200 receives the AC voltage and is converted into a DC voltage by the rectifier 202. The current value A is transmitted to the power transmission side infrared communication module 114 via the power reception side infrared communication module 206 and notified to the power transmission side control unit 118 (S204).

The power transmission side control unit 118 that has received the notification executes a switching frequency determination process (S105) for controlling the inverter circuit 102.

As shown in FIG. 5, in the switching frequency determination process (S105), the current value A (n) of the power receiving circuit 20 received by the power receiving side control unit 210 and the power transmission side control unit 118 and the load 3 connected to the power receiving circuit 20 By comparing the upper limit value Atg + dA and the lower limit value Atg−dA of the desired current value Atg, the switching frequency fa of the first pulse generation unit, the switching frequency fb of the second pulse generation unit, and the switching time ta and tb is determined and output. In addition, n shows the frequency | count which the power transmission side control part 118 received.

First, the current value A (n) received by the power transmission side control unit 118 is compared with the upper limit value Atg + dA and the lower limit value Atg + dA of the current value Atg desired by the load 3 connected to the power receiving circuit 20 (S160). DA represents the current fluctuation allowable value of the load 3.

As a result of the comparison, when the current value A (n) is within the desired current value range (S160 is “YES”), the switching frequency fa of the first pulse generator is set to the current value f (n) (S161). To finish.

On the other hand, if the current value A (n) is less than the lower limit value of the desired current value (S160 is “less than the lower limit value”), the current value A (n−1) received last time and the upper limit value Comparison (S162) is performed.

Here, when the current value A (n−1) is equal to or lower than the upper limit value (S162 is “NO”), the switching frequency fa of the first pulse generator 112a is increased by df (S165), and the power receiving side control is performed again. Waiting for the current value A to be transmitted from the unit 210, the determination of whether or not the current value is within the desired current value range (S160) is repeated.

When the current value A (n−1) is larger than the upper limit value (S162 is “YES”), the switching frequency fa of the first pulse generator 112a is set to the current f (n) (S163), and the second pulse The switching frequency fb of the generator 112b is set to the previous frequency f (n-1) (S164). Subsequently, the switching time of the output pulses of the above-mentioned two pulse generators 112a and 112b is set (S170), and either of them is switched and input to the gate of the inverter circuit 102 (S171). Details of this will be described later.

Again, the load 3 connected to the power receiving circuit 20 receives the current value A (n) received by the power transmission side control unit 118 and compares it with the upper limit value Atg + dA and lower limit value Atg + dA of the desired current value Atg. A process when n) is larger than the desired upper limit of the current value (S160 is “greater than the upper limit”) will be described.

Next, the current value A (n-1) received last time is compared with the lower limit value (S166). If the current value A (n-1) is equal to or higher than the lower limit value (S166 is "NO"), the first Decrease the switching frequency fa of the pulse generator 112a by df (S169), wait for the current value A to be transmitted from the power receiving side controller 210 again, and determine whether or not it is within the desired current value range (S160) repeat.

When the current value A (n−1) is less than the lower limit (S166 is “YES”), the switching frequency fa of the first pulse generator 112a is set to the current f (n) (S167), and the second pulse The switching frequency fb of the generator 112b is set to the previous frequency f (n-1) (S168). Subsequently, the switching time of the output pulses of the above-described two pulse generators 112a and 112b is set (S170), one of them is switched and input to the gate of the inverter circuit 102 (S171).

Here, the switching time setting (S170) of the output pulses of the first pulse generator 112a and the second pulse generator 112b will be described. When the ratio of the time for outputting the switching frequency fa of the first pulse generator 112a and the switching frequency fb of the second pulse generator 112b is ta and tb, ta and tb are set by the following equations.
ta = (A (fb) −Atg) / (A (fb) −A (fa)) · dt (1)
tb = (Atg−A (fa)) / (A (fb) −A (fa)) · dt (2)
Here, A (fa) and A (fb) are measured by the current measuring unit 204 of the power receiving circuit 20 when the inverter circuit 102 is switched by the output pulse of the switching frequency fa and the output pulse of the switching frequency fb, respectively. Indicates the current value. dt represents a switching unit time.

The advantage of switching the switching frequencies fa and fb alternately will be described. In order to bring the current A generated in the power receiving circuit 20 closer to the target current value Atg, it is necessary to finely set df for adjusting the switching frequency of the pulse generator. However, the switching frequency that can be output by the power transmission side control unit 118 is limited in resolution, and df depends on the resolution. Therefore, when the switching frequency is increased or decreased in units of df, there are cases where the desired current value Atg or the switching frequency ftg for generating a current value within the range of the upper limit value and the lower limit value cannot be achieved.

Therefore, the switching frequencies fa and fb (fa> ftg> fb) closest to ftg among the switching frequencies that can be output by the power transmission side control unit 118 are set in the first pulse generation unit 112a and the second pulse generation unit 112b, respectively. By switching the pulse switching unit 113 every unit time and alternately outputting the same, it is possible to obtain the same effect as when the desired switching frequency ftg is output.

Returning to FIG. 3, the power transmission side control unit 118 drives the inverter circuit 102 by constant current control at the switching frequencies fa to fb (S <b> 106).

Here, when the difference between the desired current value Atg and the measured current value A remains within a predetermined range for a predetermined time, it is determined that the constant current control is being performed stably (“YES” in S107). ”), And transmits to the power receiving side infrared communication module 206 via the power transmitting side infrared module 114 (S108).

Upon receiving notification that the constant current control is stable (“YES” in S206), the power receiving side control unit 210 switches the external output switch 209 to the ON state (S207), and starts the non-contact power supply to the load 3. .

After that, the power transmission side control unit performs constant current control by adjusting the output frequency according to the fluctuation of the load 3.

The stop of power supply is determined by the power transmission side control unit 118 to stop power supply (S109), and power transmission to the power receiving circuit 20 is stopped (S110). Directly, the pulse output to the power transmission switching MOSFETs 103a to 103d is stopped, and the gate current supply to the switching transistor is stopped.

Next, the power transmission side control unit 118 notifies the power reception side control unit 210 via the power transmission side and the power reception side infrared communication modules 114 and 206 (S111) and ends.

The power receiving side control unit 210 recognizes that power transmission is stopped (S208 is “NO”), and then switches the external output switch 209 to OFF (S209) and ends.

As described above, in the non-contact power transmission device 1 using the electromagnetic resonance coupling according to the present embodiment, the power transmitting side infrared light receiving / emitting unit having a strong directivity is located at the position facing the power transmitting coil 100 and the power receiving coil 200. Since the optical axis of 115 and the power-receiving-side infrared light receiving / emitting unit 207 are relatively coincident with the coincident positions, it is possible to prevent positional deviation. In addition, since the switching frequency optimum for electromagnetic field covalent coupling is adjusted based on the current value generated in the power receiving circuit 20 in the previous stage of supplying power to the load 3, it is possible to cope with changes in the air gap between the coils. Become. Furthermore, by alternately providing two switching frequencies fa and fb in which the current value A generated in the power receiving circuit 20 is close to the desired current value Atg, the desired current value can be obtained even when the resolution of the settable switching frequency is low. Power transmission can be performed within the allowable range of Atg (Atg-dA to Atg + dA in FIG. 6). Therefore, a non-contact power transmission device that is small, inexpensive, and capable of high energy transmission efficiency is realized.

The present invention is not limited to the above-described embodiments, and various modifications and applications can be made without departing from the gist of the present invention. For example, the measurement by the current measuring unit 204 may be a voltage value or a power value as a measurement by a voltage measurement unit or a power measurement unit.

DESCRIPTION OF SYMBOLS 1 Non-contact power transmission apparatus, 2 DC power supply, 3 Load, 10 Power transmission circuit, 20 Power reception circuit, 100 Power transmission coil, 101 Capacitor, 102 Inverter circuit, 103a, 103b, 103c, 103d Switching MOSFET, 104 Smoothing capacitor, 105 Transformer circuit, 106 diode, 107 inductance, 108 smoothing capacitor, 109 switching transistor, 111 frequency setting unit (frequency setting unit), 112a first pulse generating unit (switching pulse generating unit), 112b second pulse generating unit (switching) Pulse generation means), 113 pulse switching section (pulse switching means), 114 power transmission side infrared communication module (power transmission side communication means), 115 power transmission side infrared light receiving / emitting section, 116 power transmission side infrared communication driver, 11 Transformer control unit, 118 Power transmission side control unit, 119, 120 Input terminal, 200 Power receiving coil, 201 Capacitor, 202 Rectifier, 203 Capacitor, 204 Current measuring unit (measuring means), 205 Current monitoring resistor, 206 Power receiving side infrared communication module (Power-receiving-side communication means), 207 power-receiving-side infrared light receiving / emitting unit, 208 power-receiving-side infrared communication driver, 209 external output switch, 210 receiving-side control unit, 211, 212 output terminal

Claims (4)

A non-contact power transmission device that transmits power in a non-contact manner by electromagnetic resonance coupling between a power transmission coil of a power transmission circuit and a power reception coil of a power reception circuit,
Measuring means for measuring an electrical parameter of power generated in the power receiving circuit;
The power receiving side communication means for transmitting the electrical parameter measured by the measurement means to the outside as a wireless signal;
Power transmission side communication means for receiving a wireless signal from the power reception side communication means;
The frequency setting means for obtaining the electrical parameter from the wireless signal received by the power transmission side communication means, and setting a switching frequency for generating an AC voltage supplied to the power transmission coil based on the electrical parameter;
Two or more switching pulse generating means for outputting a switching pulse for generating an AC voltage supplied to the power transmission coil based on a command of the frequency setting means;
A non-contact power transmission apparatus comprising pulse switching means for switching an output of any of the two or more switching pulse generating means as a switching pulse for generating an AC voltage supplied to the power transmission coil. The non-contact power transmission device, wherein the electrical parameter includes any one of a current value, a voltage value, and a power value.   2. The non-contact power transmission apparatus according to claim 1, wherein transmission / reception of a wireless signal between the power transmission side communication unit and the power reception side communication unit is performed by infrared rays.   The switching of the two or more switching pulse generating means is desired to be generated in the power receiving circuit and the value of the electric parameter of the power generated in the power receiving circuit measured by the measuring means at each switching pulse output time. The contactless power transmission device according to claim 1, wherein the contactless power transmission device is performed in a time set in accordance with a difference between the electric parameter value and the electric power value.