JP6535894B2 - Contactless power transmission device - Google Patents

Description

The present invention relates to a contactless power transfer apparatus that performs power transfer contactlessly.

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

In the non-contact power transmission device using such electromagnetic field resonance coupling, the resonance frequency changes due to the difference in the facing positions of the power transmission coil and the power reception coil or the difference in the air gap between them, and the energy transmission The efficiency may deteriorate. (Patent Document 2)

Therefore, in Patent Document 1, matching circuits are inserted on the power transmission side and the power reception side, impedance matching is attempted, and energy transmission efficiency is degraded due to a change in the distance of the air gap between the coils and a change in the resonance frequency due to positional deviation. What has been described to prevent. Further, in Patent Document 2, there are a plurality of power transmission units provided with power transmission coils corresponding to positional displacement between coils, and among them, a power transmission coil having the highest power supply efficiency is selected. Is described.

Unexamined-Japanese-Patent No. 2012-130061 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, adjustment of impedance matching is complicated and processing time is long. In the contactless power transmission described in Patent Document 2, a plurality of power transmission units are provided in the power transmission device to cope with the displacement of the position where the power transmission coil and the power reception coil face each other. The

An object of the present invention is to provide a contactless power transmission device capable of high energy transmission efficiency without increasing the size and cost of the device.

The noncontact power transmission device according to the present invention is a noncontact power transmission device for noncontact power transmission between a power transmission coil of a power transmission circuit and a power reception coil of a power reception circuit by electromagnetic field resonance coupling. Measuring means for measuring an electrical parameter of the received power, a power receiving side communication means for transmitting the electrical parameter measured by the measuring means to the outside as a wireless signal, and a power transmission side for receiving a wireless signal from the power receiving side communication means The electric parameter is obtained from the communication means and the wireless signal received by the power transmission side communication means, and the load connected to the power receiving circuit is calculated based on the comparison between the upper limit value and the lower limit value of the electric parameter desired. frequency settings for controlling the switching time of the desired two or more switching frequencies that sandwich the frequency in the intermediate and 2 or more switching frequency of the AC voltage supplied to the coil Means, two or more switching pulse generating means for outputting switching pulses for generating an AC voltage based on a command of the frequency setting means, and any one of the switching pulses outputted from the two or more switching pulse generating means And pulse switching means for switching according to the switching time and supplying the power to the power transmission coil.

According to this configuration, the displacement of the position where the transmitting coil and the receiving coil are opposed is prevented, the influence of the resonance frequency fluctuation due to the difference of the air gap is avoided, the resonance state is maintained, and the power transmission with high energy efficiency Make it possible.

It is a block diagram showing composition of an embodiment of the present invention. It is a perspective view which shows the example of arrangement | positioning of the power transmission coil of this invention, and a receiving coil. It is a flowchart which shows a process of a power transmission side and a 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 by the side of power transmission. 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 showing a basic configuration of the contactless power transmission device 1 according to the embodiment. The non-contact power transmission device 1 of the present invention comprises a power transmission circuit 10 and a power reception circuit 20. The power transmission circuit 10 is connected to a DC power supply 2 serving as a power source to be supplied, and the power reception circuit 20 is connected to a load 3 for supplying received power, such as an electric toothbrush or a charging device of a smartphone or tablet terminal. Ru.

As shown in FIG. 1, the power transmission circuit 10 includes a power transmission coil 100, a capacitor 101, an inverter circuit 102, a diode 106, an inductance 107, a smoothing capacitor 108, and a transformer circuit 105 including a switching transistor 109, and frequency setting. A power transmission side infrared communication module 114 including a section 111, a first pulse generation section 112a and a second pulse generation section 112b, a pulse switching section 113, a power transmission side infrared light emitting / receiving section 115, and a power transmission side infrared communication driver 116 A control unit 117 and a power transmission side control unit 118 are provided.

The power transmission coil 100 is obtained by planarly winding a conducting wire 152 around a plate-like magnetic core 151 as shown in FIG. The capacitor 101 is connected in series to the power transmission coil 100 to form a resonant 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 of repeating ON and OFF of the gate current supplied to the switching transistor 109 in FIG. The change of the cycle is performed by the transformation control unit 117, and is controlled by an instruction from the power transmission side control unit 118.

The DC voltage generated by the transformer circuit 105 is converted by the inverter circuit 102 into an AC voltage. The DC voltage supplied from the transformer circuit 105 is converted into an AC voltage by an inverter circuit 102 configured by combining four switching MOSFETs (Metal Oxide 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 controlled to be conductive at different timings by combining two each (103a and 103d and 103b and 103c), alternating voltage between point A and point B in FIG. Occurs.

To change the amplitude of the AC voltage or stop the generation, change the time width of the switching pulse applied to the gates of the two sets of switching MOSFETs 103a, 103d and 103b, 103c, or stop the applied switching pulse. Can be realized by 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 a pulse switching unit in which one of the switching pulses generated by the first pulse generating unit 112a and the second pulse generating unit 112b is used. Provided by The frequencies of the switching pulses generated by the first pulse generator 112 a and the second pulse generator 112 b are both set by the frequency setting unit 111.

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

The power transmission side infrared communication driver 116 exchanges data with the power reception side control unit 210 described later via the power transmission side infrared light reception and emission unit 115 and the power reception side infrared light reception and emission unit 207 of the power transmission side control unit 118. Interface unit.

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 a direct current voltage required for the power supply desired by the load 3. Therefore, a command of the cycle that the transformation control unit 117 gives the switching transistor 109, the power transmission coil 100 and the capacitor And a command to set the switching frequency to be supplied to the resonance circuit consisting of 101 in the frequency setting unit 111, and the power transmission side infrared communication module 114 consisting of the power transmission side infrared light emitting / receiving section 115 and the power transmission side infrared communication driver 116 Exchange data, etc.

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 infrared light emitting / receiving unit 207, and a power receiving infrared communication driver. A power receiving side infrared communication module 206, and an external output switch 209, and a power receiving side control unit 210.

The power receiving coil 200 is obtained by planarly winding a conducting wire 262 around a plate-like magnetic core 261 as shown in FIG. The capacitor 201 is connected in series to the power receiving coil 200 to constitute a resonant circuit.

The rectifier 202 rectifies the power from the power receiving coil 200 and converts it into a DC power supply. The capacitor 203 is a capacitor for smoothing and noise removal.

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. The power reception side control unit 210 stores in advance information of power required by the load 3 (charging device such as an electric toothbrush, a smartphone, a tablet terminal, etc.) connected to the output terminals 211 and 212. The information of the power required by the load 3 and the current value A detected by the current measurement unit 204 described above are received via the power receiving side infrared communication module 206 including the power receiving side infrared light emitting / receiving unit 207 and the power receiving side infrared communication driver 208. Then, data communication is performed with the power transmission side control unit 118 by wireless communication. Furthermore, control of the output changeover switch 209 is also performed, which switches between the execution and the stop of the power supply to the load 3.

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

The flowcharts of FIGS. 3 to 5 show control of the non-contact power transmission device of the present embodiment. The left side of the figure represents the processing of the power reception 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 sends to the inverter circuit 102 supplied by the first control pulse generation unit 112 a and the second pulse generation unit 112 b, the transformation control unit 117 that sets the DC voltage output by the transformation circuit 105. The command given to the frequency setting unit 111 that determines the frequency of the switching pulse is turned off to perform initialization. (S101)

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

With regard to the infrared light emitting and receiving unit (115, 207) used here, the directivity of the infrared light is strong and the directivity angle is narrow, so that the optical axis needs to be sufficiently aligned in order to establish communication. Therefore, by aligning the position of the optical axis so that the infrared light emitting and receiving units (115, 207) on the power transmitting side and the power receiving side can communicate, the power transmitting side infrared light emitting and receiving unit 115, the power transmitting coil 100, and the power receiving side infrared receiver Since the physical positional relationship between the light emitting unit 207 and the power receiving coil 200 is the same, as a result, it is possible to make the facing positions of both the coils (100, 200) match. Therefore, by establishing infrared communication, it is ensured that the power transmission coil 100 and the power reception coil 200 are in a facing positional relationship.

The power transmission side control unit 118 determines whether the received power supply condition to the load 3 can be supplied by the power transmission circuit 10, and in the case of the impossible condition (“NO” in S103), the process ends.

On the other hand, in the case where the power supply condition is possible ("YES" in S103), initialization is performed under the condition matched to the power to be transmitted (S104).

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

Returning to FIG. 3, the power receiving control unit 210 waits until receiving the completion of the initial setting from the power transmission control unit 118 (“NO” in S202), but there is no response within a predetermined time (“YES” in S203) ) Ends as it is. If there is a response (“YES” in S202), the current measurement unit 204 measures the current value A after the power receiving coil 200 receives an AC voltage and is converted to 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).

In the power transmission side control unit 118 that has received the notification, the process of determining the switching frequency for controlling the inverter circuit 102 (S105) is performed.

As shown in FIG. 5, in the process of determining the switching frequency (S105), the current value A (n) of the power receiving circuit 20 received by the power receiving side control unit 210 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 and the switching frequency fb of the second pulse generation unit and the switching time ta thereof Determine tb and output. Here, n indicates the number of times the power transmission side control unit 118 has received.

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

As a result of 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 generation unit is set to the current value f (n) (S161) End.

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 previously received current value A (n-1) and the upper limit value A comparison (S162) is performed.

Here, when the current value A (n-1) is equal to or less than the upper limit (S162 is "NO"), the switching frequency fa of the first pulse generation unit 112a is increased by df (S165), and power reception side control is performed again. It waits for the current value A to be transmitted from the unit 210, and repeats the determination (S160) as to whether or not it is within the desired current value range.

If the current value A (n-1) is larger than the upper limit (S162 is "YES"), the switching frequency fa of the first pulse generation unit 112a is set to the current f (n) (S163), and the second pulse is generated The switching frequency fb of the generator 112b is set to the frequency f (n-1) immediately before (S164). Subsequently, the switching time of the output pulse of the two pulse generation units 112a and 112b described above is set (S170), one of them is switched, and input to the gate of the inverter circuit 102 (S171). Details of will be described later.

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

Next, the current value A (n-1) received last time is compared with the lower limit value (S166), and if the current value A (n-1) is equal to or more than the lower limit value (S166 is "NO") The switching frequency fa of the pulse generation unit 112a is decremented by df (S169), and waiting for current value A to be transmitted again from the power reception side control unit 210, and determination as to whether or not within the desired current value range (S160) repeat.

If 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 is generated. The switching frequency fb of the generator 112b is set to the frequency f (n-1) immediately before (S168). Subsequently, the switching time of the output pulse of the above-mentioned two pulse generation units 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 pulse of the 1st pulse generation part 112a and the 2nd pulse generation part 112b is explained. Assuming that the ratio of 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 measurement unit 204 of the power reception 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 indicates a switching unit time.

The advantages of switching the switching frequencies fa and fb alternately will be described. In order to bring the current A generated by the power reception circuit 20 closer to the target current value Atg, it is necessary to finely set df for adjusting the switching frequency of the pulse generation unit. However, the switching frequency to which the power transmission side control unit 118 can output is limited in resolution, and df depends on the resolution. Therefore, the switching frequency increases or decreases in df units, there are cases where the desired current value Atg or the upper limit value, Sui etching frequency ftg that generates a current in the range of the lower limit can not be achieved.

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

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 (S106).

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

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

Even 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.

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

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

After recognizing the power transmission stop (S208 is "NO"), the power receiving side control unit 210 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 field resonance coupling according to the present embodiment, the power transmission side infrared light emitting / receiving unit with strong directivity at the position where the power transmission coil 100 and the power reception coil 200 face each other. Since the optical axes of the power receiving side infrared light emitting and receiving unit 207 and the power receiving side infrared receiving and emitting unit 207 relatively coincide with each other, the positional deviation can be prevented. In addition, in order to adjust the switching frequency optimum for the electromagnetic field sharing coupling based on the value of the current generated by the power receiving circuit 20 at the stage before supplying power to the load 3, it is possible to cope with the change of the air gap between the coils. Become. Furthermore, by alternately giving two switching frequencies fa and fb close to the desired current value Atg generated by the power receiving circuit 20, the desired current value is obtained even when the resolution of the settable switching frequency is low. Power transmission is possible in the tolerance range of Atg (Atg-dA to Atg + dA in FIG. 6). Therefore, a small-sized, inexpensive, and non-contact power transmission device capable of high energy transmission efficiency is realized.

The present invention is not limited to the embodiment described above, and various modifications and applications are possible without departing from the scope of the present invention. For example, it is also possible to use the voltage value and the power value as the measurement by the current measurement unit 204 as the measurement by the voltage measurement unit or the power measurement unit.

DESCRIPTION OF SYMBOLS 1 contactless power transmission apparatus, 2 DC power supply, 3 load, 10 power transmission circuit, 20 power receiving 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 generation unit (switching pulse generation unit), 112b second pulse generation unit (switching Pulse generation means), 113 pulse switching portion (pulse switching means), 114 power transmission side infrared communication module (power transmission side communication means), 115 power transmission side infrared light emitting and receiving portion, 116 power transmission side infrared communication driver, 11 Transformation control unit 118 power transmission side control unit 119, 120 input terminal 200 power receiving coil 201 capacitor 202 rectifier 202 capacitor 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 emitting and receiving unit, 208 Power receiving side infrared communication driver, 209 External output switch, 210 Receiving side control unit, 211, 212 Output terminal

Claims (3)

A contactless power transmission device for transmitting power contactlessly through 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 the power generated in the power receiving circuit;
Power reception side communication means for transmitting the electric parameter measured by the measurement means to the outside as a wireless signal;
Power transmitting communication means for receiving the wireless signal from the power receiving communication means;
The electric parameter is acquired from the wireless signal received by the power transmission side communication means, and calculation is performed based on the comparison between the upper limit value and the lower limit value of the electric parameter desired by the load connected to the power receiving circuit, Frequency setting means for setting two or more switching frequencies sandwiching a desired frequency of the AC voltage supplied to the power transmission coil in between and switching time of the two or more switching frequencies;
Two or more switching pulse generating means each outputting a switching pulse for generating the alternating voltage based on a command from the frequency setting means;
Noncontact power transmission characterized by comprising: pulse switching means for switching any one of the switching pulses output from the two or more switching pulse generating means according to the switching time and supplying the same to the power transmission coil apparatus.
The contactless power transmission device according to claim 1, wherein the electrical parameter includes any one of a current value, a voltage value, and a power value. The transfer of the wireless signal between the power transmission side communication unit and said power receiving side communication means, the non-contact power transmission apparatus according to claim 1 or 2, characterized in that due to infrared rays.