JP7140629B2 - Contactless power transmission/reception system - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power receiving device, and more particularly to a power receiving device that supplies electric power received from a power transmission device in a contactless manner to an electric load.

Conventionally, a power receiving device of this type includes a power receiving unit having a power receiving coil capable of contactlessly receiving power from a power transmitting coil of a power transmitting device and a first capacitor connected in series to the power receiving coil, and a power receiving unit connected to the power receiving unit. and a voltage doubler rectifier circuit that has a second capacitor connected in parallel to the diode bridge circuit, rectifies and boosts the power from the power receiving unit, and supplies it to the power storage device. (See Patent Document 1, for example). In this power receiving device, by using the voltage doubler rectifier circuit, the step-up ratio between the power receiving coil side and the power storage device side is increased as compared with the case of using the rectifier circuit only with the diode bridge circuit (without the second capacitor). This increases the adjustable range of the impedance of the power receiving device.

JP 2016-82707 A

In the power receiving device described above, when the voltage of the power storage device is low, the impedance on the output side (battery side) of the power receiving coil is greater than when the voltage is high. It is necessary to increase the current flowing through the power transmission coil. As the current flowing through the power transmission coil increases, the copper loss in the power transmission coil increases, and the charging efficiency decreases when power is supplied to the power storage device due to contactless power transmission and reception between the power transmission device and the power reception device. easier.

A main object of the power receiving device of the present invention is to suppress a decrease in efficiency when power is supplied to an electrical load with contactless power transmission and reception between the power transmitting device and the power receiving device.

The power receiving device of the present invention employs the following means in order to achieve the main object described above.

The power receiving device of the present invention is
A power receiving device that supplies power received contactlessly from a power transmitting device to an electrical load,
a power receiving resonance circuit having a power receiving coil capable of contactlessly receiving power from the power transmitting coil of the power transmitting device, and a first capacitor connected to the power receiving coil;
A diode bridge circuit connected to the power receiving resonance circuit, and a second capacitor unit connected in parallel to the diode bridge circuit and having a variable capacitance, which rectifies and boosts the power from the power receiving resonance circuit. and a voltage doubler rectifier circuit for supplying to the electrical load;
a control unit that controls the capacitance value of the second capacitance unit to be smaller when the voltage of the electric load is less than a predetermined voltage compared to when the voltage of the electric load is equal to or higher than the predetermined voltage;
The gist is to provide

In the power receiving device of the present invention, a power receiving coil capable of contactlessly receiving power from the power transmitting coil of the power transmitting device, a power receiving resonance circuit having a first capacitor connected to the power receiving coil, and a power receiving resonance circuit and a second capacitance unit connected in parallel to the diode bridge circuit and having a variable capacitance, which rectifies and boosts the power from the power receiving resonance circuit and supplies it to the electric load. and a voltage doubler rectifier circuit. Then, when the voltage of the electric load is less than the predetermined voltage, the capacitance value of the second capacitor is controlled to be smaller than when the voltage of the electric load is equal to or higher than the predetermined voltage. Therefore, when the voltage of the electrical load is less than the predetermined voltage (when the current flowing through the power transmission coil increases and the copper loss of the power transmission coil increases), the capacitance value of the second capacitor is set to a relatively small value. By doing so, it is possible to improve the power factor of the power transmission coil and the power receiving device, and improve the efficiency when supplying power to an electrical load with contactless power transmission and reception between the power transmission device and the power receiving device. can. The present inventors confirmed this by analysis and the like. Further, when the voltage of the electric load is equal to or higher than the predetermined voltage, the current flowing through the power transmission coil does not need to be increased so much, so the copper loss of the power transmission coil does not increase so much. Therefore, at this time, by setting the capacitance value of the second capacitor to a relatively large value, it is possible to stably supply electric power against the voltage fluctuation of the electric load.

In such a power receiving device of the present invention, the diode bridge circuit has first to fourth diodes, and the first and second diodes are connected to the positive line and the negative line connected to the electrical load. The third and fourth diodes are connected in series and their connection point is connected to one side of the power receiving coil, and the third and fourth diodes are connected in series to the positive line and the negative line and may be connected to the other side of the power receiving coil. The second capacitive section has first to fourth capacitors and a switch, and the first and second capacitors are connected in series to the positive line and the negative line, and A connection point is connected to a connection point of the third and fourth diodes, the third and fourth capacitors are connected in series to the positive line and the negative line, and the switch is connected to the first capacitor. , and the connection point of the second capacitor and the connection point of the third and fourth capacitors may be connected and disconnected.

A non-contact power transmission/reception system according to a modification of the present invention is summarized as including the power reception device according to any one of the aspects described above and a power transmission device. Since the power receiving device according to any one of the aspects described above is provided in this manner, the effects of the power receiving device described above, such as contactless power transmission between the power transmitting device and the power receiving device when the voltage of the electrical load is less than a predetermined voltage, can be achieved. It is possible to achieve the same effect as the effect of improving the efficiency when supplying power to an electric load in conjunction with power reception.

In the contactless power transmission/reception system of the modified example of the present invention, the power transmission device includes a power transmission unit having the power transmission coil, and a power transmission side control section that controls the power transmission unit, and the power transmission side control section When the voltage of the electric load rises from less than the predetermined voltage to the predetermined voltage or more and the power receiving device increases the capacitance value of the second capacitance unit, the power transmission coil and the power receiving coil are not connected to each other. The power transmission unit may be controlled such that power reception is interrupted. By doing so, the second capacitor can be protected.

1 is a configuration diagram showing an outline of a configuration of a contactless power transmission/reception system 10 including a power reception device 30 as an embodiment of the present invention; FIG. 2 is a configuration diagram showing an example of a voltage doubler rectifier circuit 40, particularly a capacitor circuit 44; FIG. 4 is a flowchart showing an example of a power transmission side processing routine executed by a power transmission ECU 170; 4 is a flowchart showing an example of a vehicle-side processing routine executed by a vehicle ECU 70; An example of the relationship between the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 and the power factor of the power transmission coil 141 when it is assumed that the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 can be changed arbitrarily is shown below. It is an explanatory diagram showing. Explanation showing an example of the relationship between the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 and the power factor of the power receiving device 30 when it is assumed that the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 can be arbitrarily changed. It is a diagram. FIG. 4 is an explanatory diagram showing an example of the relationship between the voltage Vba and the charging power Pba of the battery 22 of the example and the comparative example when the same current is passed through the power transmitting coil 141 in the example and the comparative example. 3 is an explanatory diagram showing an example of a relationship between a coupling coefficient between a power transmission coil 141 of a power transmission device 130 and a power reception coil 33 of a power reception device 30 and a power factor of the power transmission coil 141; FIG. An example of the relationship between the coupling coefficient between the power transmitting coil 141 of the power transmitting device 130 and the power receiving coil 33 of the power receiving device 30 and the current to be applied to the power transmitting coil 141 in order to charge the battery 22 with relatively large power is shown. It is an explanatory diagram showing.

Next, a mode for carrying out the present invention will be described using examples.

FIG. 1 is a configuration diagram showing a schematic configuration of a contactless power transmission/reception system 10 including a power receiving device 30 as one embodiment of the present invention. The contactless power transmission/reception system 10 of the embodiment includes, as shown in FIG. Prepare.

The power transmission device 130 includes a power transmission unit 131 connected to an AC power supply 190 such as a household power source (for example, 200 V, 50 Hz), and a power transmission electronic control unit (hereinafter referred to as a “power transmission ECU”) that controls the power transmission unit 131. 170 , and a communication unit 180 that communicates with the power transmission ECU 170 and wirelessly communicates with a communication unit 80 (described later) of the vehicle 20 .

The power transmission unit 131 includes an AC/DC converter 132 , an inverter 134 , a filter circuit 136 and a power transmission resonance circuit 140 . AC/DC converter 132 is configured as a known AC/DC converter that converts AC power from AC power supply 190 into DC power of any voltage.

The inverter 134 has four switching elements S11 to S14 and four diodes D11 to D14 connected in parallel in opposite directions to the four switching elements S11 to S14, respectively. As the switching elements S11 to S14, for example, MOSFETs (a type of field effect transistor: metal-oxide-semiconductor field-effect transistor) are used. The switching elements S11 to S14 are arranged in pairs so as to be on the source side and the sink side with respect to the positive line and the negative line on the output side of the AC/DC converter 132, respectively. A first output terminal 134a provided (connected) at the connection point of the two switching elements S11 and S12, and a second output terminal 134a provided (connected) at the connection point of the two switching elements S13 and S14. The output terminal 134b is connected to a power transmission side first line 144a and a power transmission side second line 144b connected to one side and the other side of a power transmission coil 141 (described later) of the power transmission resonance circuit 140, respectively. Inverter 134 converts the DC power from AC/DC converter 132 into AC power of a desired frequency by controlling switching of switching elements S11 to S14 by power transmission ECU 170 by pulse width modulation control.

The filter circuit 136 is configured as a low-pass filter, and the coil 137 provided in the power transmission side first line 144a and the coil 137 in the power transmission side first line 144a are closer to the power transmission resonance circuit 140 (power transmission coil 141 side) than the coil 137 is. ) and a capacitor 138 connected to the power transmission side second line 144b. This filter circuit 136 removes high frequency noise from the AC power from the inverter 134 .

The power transmission resonance circuit 140 has, for example, a power transmission coil 141 installed on the floor of a parking lot or the like, and a capacitor 142 connected in series to the power transmission coil 141 . The power transmission resonance circuit 140 is designed so that the resonance frequency is a predetermined frequency Fset (about several tens to several hundred kHz). Therefore, inverter 134 basically converts the DC power from AC/DC converter 132 into AC power having a predetermined frequency Fset.

Although not shown, the power transmission ECU 170 is configured as a microprocessor centered on a CPU. In addition to the CPU, the power transmission ECU 170 includes a ROM that stores processing programs, a RAM that temporarily stores data, an input/output port, and a communication port. Prepare. Signals from various sensors are input to power transmission ECU 170 via input ports. Signals input to the power transmission ECU 170 include, for example, the output voltage Vco of the AC/DC converter 132 from the voltage sensor 160 attached between both terminals on the output side of the AC/DC converter 132 and the output voltage Vco of the AC/DC converter 132. The output current Ico of the AC/DC converter 132 from the current sensor 162 attached to the negative line between the inverter 134 can be mentioned. Further, the output current Iin of the inverter 134 from the current sensor 163 attached to the inverter 134 side (the second output terminal 134b side) of the connection point with the capacitor 138 in the power transmission side second line 144b, and the power transmission side second line The current Itr flowing through the power transmission coil 141 from the current sensor 164 attached to the power transmission resonance circuit 140 side (power transmission coil 141 side) of the connection point with the capacitor 138 in 144b can also be cited. Various control signals are output from power transmission ECU 170 via an output port. Signals output from power transmission ECU 170 include, for example, control signals to AC/DC converter 132 and switching control signals to switching elements S11 to S14 of inverter .

The vehicle 20 is configured as an electric vehicle or a hybrid vehicle provided with a motor for running, and includes a battery (electric load) 22 that exchanges power with the motor, a power receiving unit 31 connected to the battery 22, and a control unit for controlling the entire vehicle. and a communication unit 80 that communicates with the vehicle ECU 70 and wirelessly communicates with the communication unit 180 of the power transmission device 130 . Note that the power receiving unit 31, the vehicle ECU 70, and the communication unit 80 mainly correspond to the "power receiving device" of the embodiment.

The power receiving unit 31 includes a power receiving resonance circuit 32 , a filter circuit 36 , a voltage doubler rectifier circuit 40 , and a smoothing capacitor 48 . The power receiving resonance circuit 32 includes, for example, a power receiving coil 33 installed on the bottom surface (floor panel) of the vehicle body, and a capacitor (first capacitance section) 34 connected in series to the power receiving coil 33 . One side of the power receiving coil 33 is connected to the first input terminal 40a of the voltage doubler rectifier circuit 40 via the capacitor 34 and the vehicle side first line 35a, and the other side is connected to the voltage doubler via the vehicle side second line 35b. It is connected to the second input terminal 40 b of the voltage rectifier circuit 40 . The power reception resonance circuit 32 is designed to have a resonance frequency (ideally, the predetermined frequency Fset) near the predetermined frequency Fset (resonance frequency of the power transmission resonance circuit 140).

The filter circuit 36 is configured as a low-pass filter, and the coil 37 provided in the vehicle-side first line 35a and the power-receiving resonance circuit 32 side (power-receiving coil 33 side) of the coil 37 in the vehicle-side first line 35a ) and the vehicle-side second line 35b, a capacitor 39 connected to the voltage doubler rectifier circuit 40 side of the coil 37 in the vehicle-side first line 35a and the vehicle-side second line 35b, have The filter circuit 36 removes high-frequency noise from the AC power received by the power reception resonance circuit 32 .

The voltage doubler rectifier circuit 40 has a diode bridge circuit 42 and a capacitance circuit (second capacitance section) 44 connected in parallel to the diode bridge circuit 42 . The diode bridge circuit 42 has four diodes D21-D22. The four diodes D21 to D24 are arranged in series in pairs of two diodes for each of the positive line and the negative line connected to the battery 22 . A first input terminal 40a provided (connected) at the connection point of the two diodes D21 and D22, and a second input terminal 40a provided (connected) at the connection point of the two diodes D23 and D24. 40b are connected to the vehicle-side first line 35a and the vehicle-side second line 35b, respectively.

FIG. 2 is a configuration diagram showing an example of the voltage doubler rectifier circuit 40, particularly the capacitor circuit 44. As shown in FIG. The capacitive circuit 44 has four capacitors C21 to C24 and a switch S21, as shown in FIG. The four capacitors C21 to C24 are arranged in series in two pairs for each of the positive line and the negative line connected to the battery 22 . A connection point between the two capacitors C21 and C22 is connected to a connection point between the two diodes D23 and D24. Switch S21 is controlled by vehicle ECU 70 to connect and disconnect a connection point between two capacitors C21 and C22 and a connection point between two capacitors C21 and C22.

In this capacitor circuit 44, when the switch S21 is turned off, the capacitance (hereinafter referred to as "first capacitance") Cd1 between the second input terminal 40b and the positive electrode line becomes the capacitance of the capacitor C21, and the second input terminal A capacitance (hereinafter referred to as a “second capacitance”) Cd2 between 40b and the negative line is the capacitance of the capacitor C22. Also, when the switch S21 is on, the first capacitance value Cd1 is the sum of the capacitances of the capacitors C21 and C23, and the second capacitance value Cd2 is the sum of the capacitances of the capacitors C22 and C24. In this embodiment, the capacitors C21 and C22 have the same capacity, and the capacitors C23 and C24 have the same capacity. Therefore, both the first and second capacitance values Cd1 and Cd2 when the switch S21 is off are relatively small values Cdlo, and both the first and second capacitance values Cd1 and Cd2 when the switch S21 is on are compared with each other. Cdhi is relatively large.

The voltage doubler rectifier circuit 40 configured in this manner rectifies and boosts the AC power received by the power receiving coil 33 of the power receiving resonance circuit 32 and supplies the power to the battery 22 . By using the voltage doubler rectifier circuit 40 having the diode bridge circuit 42 and the capacitor circuit 44, the voltage fluctuation of the battery 22 can be reduced as compared with the case of using the rectifier circuit having only the diode bridge circuit 42 (without the capacitor circuit 44). can be stably charged.

As shown in FIG. 1 , the smoothing capacitor 48 is connected to the positive line and the negative line on the battery 22 side of the voltage doubler rectifier circuit 40 . Although not shown, the vehicle ECU 70 is configured as a microprocessor centered on a CPU. In addition to the CPU, the vehicle ECU 70 includes a ROM that stores processing programs, a RAM that temporarily stores data, an input/output port, and a communication port. Prepare. Signals from various sensors are input to the vehicle ECU 70 through input ports. Signals input to the vehicle ECU 70 include, for example, the voltage Vba of the battery 22 from the voltage sensor 60 attached between both terminals of the battery 22, and the power received from the connection point with the capacitor 38 in the vehicle-side second line 35b. A current Ire flowing through the power receiving coil 33 from the current sensor 62 attached to the power receiving resonance circuit 32 side (power receiving coil 33 side) can be mentioned. In addition, the current Ifi flowing through the filter circuit 36 from the current sensor 63 attached between the connection point with the capacitor 38 and the connection point with the capacitor 39 in the vehicle-side second line 35b and the current Ifi attached to the output terminal of the battery 22 are detected. The charge/discharge current Iba of the battery 22 from the current sensor 64 (positive value when the battery 22 is charged) can also be mentioned. The vehicle ECU 70 outputs a control signal to the switch S21 of the capacitance circuit 44 and the like through the output port. The vehicle ECU 70 calculates the charging power Pba of the battery 22 as the product of the voltage Vba of the battery 22 and the charging/discharging current Iba, and calculates the charging ratio SOC of the battery 22 as the integrated value of the charging/discharging current Iba of the battery 22. .

Next, the operation of the non-contact power transmission/reception system 10 configured in this manner, in particular, the operation of non-contact charging for charging the battery 22 with non-contact power transmission/reception between the power transmission device 130 and the power reception device 30. explain. Note that contactless charging is performed when automobile 20 is parked such that power receiving coil 33 of power receiving device 30 substantially faces power transmitting coil 141 of power transmitting device 130, and the user instructs the execution of contactless charging. be FIG. 3 is a flow chart showing an example of a power transmission side processing routine executed by the power transmission ECU 170, and FIG. 4 is a flow chart showing an example of a vehicle side processing routine executed by the vehicle ECU 70. As shown in FIG. At the start of the routine of FIG. 4, the switch S21 of the capacitance circuit 44 is off, and the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 are relatively small values Cdlo.

First, the power transmission side processing routine in FIG. 3 will be described. When this routine is executed, the power transmission ECU 170 acquires various data through communication with the vehicle ECU 70 and checks vehicle information and charging information (step S100). Here, in collation of vehicle information, for example, it is determined whether or not the automobile 20 is a vehicle capable of performing non-contact charging. Also, in the collation of charging information, for example, it is determined whether or not the battery 22 of the automobile 20 is fully charged based on the voltage Vba of the battery 22 .

Subsequently, minimum values fmin and Dmin for control are set to the drive frequency (frequency of carrier wave (carrier frequency) in pulse width modulation control) f and duty D of inverter 134 (steps S110 and S120). As the value fmin, for example, 78 kHz, 79 kHz, 80 kHz, etc. are used. As the minimum value Dmin, for example, several percent is used.

Then, the charging power command Ps for the battery 22 is received by communication from the vehicle ECU 70 (step S130), and the received charging power command Ps for the battery 22 is limited by the allowable charging power command Pslim (upper limit guard). A charging power command Ps* for control is set (step S140). Here, the allowable charging power command Pslim is set to a relatively large initial value at the start of execution of this routine, and then becomes smaller when the process of step S250, which will be described later, is executed.

After setting the control charging power command Ps* for the battery 22 in this manner, it is determined whether the set control charging power command Ps* is positive or has a value of 0 (step S150), and when the control charging power command Ps* is positive, It is determined that power transmission device 130 will supply power to power reception device 30, and drive control is performed on AC/DC converter 132 and inverter 134 using control charging power command Ps* and drive frequency f and duty D of inverter 134 (step S160). .

Next, the voltage Vba of the battery 22, the charging power Pba, and the error information flag F are received by communication from the vehicle ECU 70 (step S170). The error information flag F is set to a value of 0 by the vehicle ECU 70 when no error (abnormality) has occurred in the vehicle 20, and is set to a value of 1 when an error has occurred.

Then, the value of the error information flag F is checked (step S180), and when the error information flag F is 0, it is determined that no error has occurred in the automobile 20, and the current value of the voltage Vba of the battery 22 is equal to or higher than the threshold value Vref. Also, it is determined whether or not the previous value is less than the threshold value Vref (step S190). Here, for the threshold Vref, for example, a value that is several tens of volts lower than the full charge voltage Vfl of the battery 22 is used. The process of step S190 is a process of determining whether or not it is immediately after the voltage Vba of the battery 22 reaches the threshold value Vref or higher.

In step S190, when the current value of the voltage Vba of the battery 22 is equal to or greater than the threshold Vref or the previous value is less than the threshold Vref, it is determined that it is not immediately after the voltage Vba of the battery 22 reaches the threshold Vref or more, and the battery 22 is controlled. It is determined whether or not there is a divergence between the charging power command Ps* for use and the charging power Pba (step S200). This determination is made, for example, by comparing the difference between the charging power command Ps* for control of the battery 22 and the charging power Pba with a threshold value. When the charge power command Ps* for control of the battery 22 and the charge power Pba do not deviate, the process returns to step S130.

When there is a discrepancy between the charging power command Ps* for control of the battery 22 and the charging power Pba in step S200, the duty D of the inverter 134 is updated by increasing it by a predetermined value ΔD (step S210). is compared with the allowable duty Dlim (step S220). Here, the predetermined value ΔD is set in advance by analysis or the like based on the specifications of the inverter 134 or the like. For example, 50% is used as the allowable duty Dlim. When the duty D of the inverter 134 is equal to or less than the allowable duty Dlim, it is determined that the duty D is within the allowable range, and the process returns to step S130.

When the duty D of the inverter 134 is greater than the allowable duty Dlim in step S220, the drive frequency f of the inverter 134 is updated by increasing it by a predetermined value Δf (step S230), and the updated drive frequency f is compared with the allowable frequency flim. (step S240). Here, the predetermined value Δf is set in advance by analysis or the like based on the specifications of the inverter 134 or the like. For example, 89 kHz, 90 kHz, and 91 kHz are used as the allowable frequency flim.

When the drive frequency f of the inverter 134 is equal to or lower than the allowable frequency flim in step S240, the process returns to step S120. On the other hand, when drive frequency f of inverter 134 is higher than allowable frequency flim, allowable charging power command Pslim is decreased by predetermined value ΔPs (step S250), and the process returns to step S110. Here, the predetermined value ΔPs is set in advance by analysis or the like based on the specifications of the power transmission device 130 or the like.

In step S190, when the current value of the voltage Vba of the battery 22 is equal to or more than the threshold Vref and the previous value is less than the threshold Vref, it is determined that the voltage Vba of the battery 22 has just reached the threshold Vref or more, and the AC/DC converter 132 and the inverter 134 are stopped (step S260), and the vehicle ECU 70 is requested to switch the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 (step S270). After receiving a switching completion signal from vehicle ECU 70 indicating that the first and second capacitance values Cd1 and Cd2 of capacitance circuit 44 have been switched (step S280), the process returns to step S130. That is, when the vehicle ECU 70 switches between the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44, driving of the AC/DC converter 132 and the inverter 134 is stopped, thereby stopping non-contact charging. be. Thereby, the non-contact charging can be interrupted to switch the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44, so that the capacitance circuit 44 can be protected. It should be noted that this driving stop time is a sufficiently short time compared to the non-contact charging time (for example, about several hours).

When the control charge power command Ps* is 0 in step S150, it is determined that power transmission device 130 will not supply power to power reception device 30, AC/DC converter 132 and inverter 134 are stopped (step S290), and this routine exit. As a result, contactless power transmission/reception between the power transmitting device 130 and the power receiving device 30 ends, and contactless charging ends.

When the error information flag F is 1 in step S180, it is determined that an error has occurred in the automobile 20, and the AC/DC converter 132 and the inverter 134 are driven regardless of the charging power command Ps* for control of the battery 22. It stops (step S290) and ends this routine. As a result, contactless power transmission/reception between the power transmitting device 130 and the power receiving device 30 ends, and contactless charging ends.

Next, the vehicle-side processing routine of FIG. 4 will be described. When this routine is executed, the vehicle ECU 70 checks vehicle information and charging information (step S300). The collation of vehicle information and charging information is performed in the same manner as in the process of step S100 described above.

Subsequently, it is determined whether switching of the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 is requested by the power transmission ECU 170 (step S310). When not requested, the voltage Vba of the battery 22 is compared with the full charge voltage Vfl (step S340).

Then, when the voltage Vba of the battery 22 is less than the full charge voltage Vfl, the charging power command Ps of the battery 22 is set (step S350). Here, the charging power command Ps for the battery 22 is set, for example, so as to increase as the charging power Pba for the battery 22 decreases. The smaller the charging power Pba of the battery 22 (the larger the difference between the charging power command Ps and the charging power Pb of the battery 22), the higher the vehicle height of the vehicle 20 or the position of the power transmission coil 141 mounted on the vehicle 20. This is because the coupling coefficient between the power transmission coil 141 and the power reception coil 33 is considered to be low due to the position being deviated from the optimum position for non-contact charging (the position sufficiently facing the power reception coil 33). .

Next, the voltage Vba of the battery 22, the charging/discharging current Iba, the current Ire flowing through the power receiving coil 33, and the current Ifi flowing through the filter circuit 36 are input from various sensors (step S360). It is determined whether or not the discharge current Iba, the current Ire flowing through the power receiving coil 33, and the current Ifi flowing through the filter circuit 36 are all within the allowable range (step S370).

When the voltage Vba of the battery 22, the charging/discharging current Iba, the current Ire flowing through the power receiving coil 33, and the current Ifi flowing through the filter circuit 36 are all within permissible ranges, it is determined that no error has occurred in the vehicle 20, and error information is provided. The flag F is set to 0 (step S380), the charging power Pba of the battery 22 is calculated as the product of the voltage Vba of the battery 22 and the charging/discharging current Iba (step S390), and the error information flag F and charging of the battery 22 Electric power Pba is transmitted to power transmission ECU 170 as charging information (step S410), and the process returns to step S310.

If at least one of the voltage Vba of the battery 22, the charging/discharging current Iba, the current Ire flowing through the power receiving coil 33, and the current Ifi flowing through the filter circuit 36 is outside the allowable range in step S370, it is determined that an error has occurred in the automobile 20. , the error information flag F is set to 1 (step S400), the error information flag F is transmitted to the power transmission ECU 170 as charging information (step S410), and the process returns to step S310. When power transmission ECU 170 receives error information flag F of value 1, power transmission ECU 170 stops driving AC/DC converter 132 and inverter 134 as described above (step S290). As a result, contactless power transmission/reception between the power transmitting device 130 and the power receiving device 30 ends, and contactless charging ends.

When the power transmission ECU 170 requests switching of the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 in step S320, the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 are changed from a relatively small value Cdlo. Switch to a relatively large value Cdhi (step S320). This switching is performed by turning the switch S21 from off to on. Then, when this switching is completed, a switching completion signal is transmitted to power transmission ECU 170 (step S330), and the processes after step S340 are executed. As described above, when the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 are switched, the AC/DC converter 132 and the inverter 134 of the power transmission device 130 are stopped, so that non-contact charging is performed. Since it is interrupted, the capacitor circuit 44 can be protected.

When the voltage Vba of the battery 22 is equal to or higher than the full charge voltage Vfl in step S340, it is determined that the non-contact charging of the battery 22 is finished, and the charging power command Ps for the battery 22 is set to 0 (step S430). exit. When power transmission ECU 170 receives charge power command Ps of value 0, power transmission ECU 170 stops driving AC/DC converter 132 and inverter 134 as described above (step S290). As a result, contactless power transmission/reception between the power transmitting device 130 and the power receiving device 30 ends, and contactless charging ends.

That is, in the embodiment, at the start of non-contact charging, the vehicle ECU 70 sets the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 to a relatively small value Cdlo. When the voltage Vba of the battery 22 reaches the threshold value Vref or more and the power transmission ECU 170 requests the vehicle ECU 70 to switch the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44, the vehicle ECU 70 switches the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44. The second capacitance values Cd1 and Cd2 are switched to a relatively large value Cdhi. The reason for this will be explained below.

FIG. 5 shows the first and second capacitance values Cd1 and Cd2 when it is assumed that the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 can be changed arbitrarily instead of in two stages (values Cdlo and Cdhi). FIG. 4 is an explanatory diagram showing an example of a relationship between power transmission coil 141 and power factor. FIG. 6 is an explanatory diagram showing an example of the relationship between the first and second capacitance values Cd1 and Cd2 and the power factor of the power receiving device 30, assuming the same as in FIG. 5 and 6 also show the values Cdlo and Cdhi. As shown in FIG. 5, the lower the first and second capacitance values Cd1 and Cd2 are, the higher the power factor of the power transmitting coil 141 is. As shown in FIG. 6, the lower the first and second capacitance values Cd1 and Cd2 are. The power factor of the power receiving device 30 increases (efficiency improves) as the value increases. These tendencies were confirmed by the present inventors through analysis and the like. Based on this tendency, it can be said that the charging efficiency can be improved when the first and second capacitance values Cd1 and Cd2 are decreased.

When the voltage of the battery 22 is low, the impedance on the output side (battery 22 side) of the power receiving coil 33 is greater than when the voltage of the battery 22 is high. It is necessary to increase the current Itr flowing through the coil 141 . As the current flowing through power transmission coil 141 increases, the copper loss of power transmission coil 141 increases, and the charging efficiency during non-contact charging tends to decrease.

In consideration of these, in the embodiment, the vehicle ECU 70 sets the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 to a relatively small value Cdlo at the start of non-contact charging, and continues non-contact charging. When the voltage Vba of the battery 22 rises and reaches or exceeds the threshold Vref, the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 are switched to a relatively large value Cdhi. As a result, the voltage Vba of the battery 22 is less than the threshold Vref, compared to the case where the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 are set to a relatively large value Cdhi regardless of the voltage Vba of the battery 22. Sometimes, it is possible to improve the power factor of the power transmitting coil 141 and the power receiving device 30 and improve the charging efficiency. Note that when the voltage Vba of the battery 22 is high, the current flowing through the power transmission coil 141 does not have to be so large, so the copper loss of the power transmission coil 141 does not become so large. Therefore, at this time, by setting the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 to a relatively large value Cdhi, the voltage fluctuation of the battery 22 can be suppressed as compared to holding a relatively small value Cdlo. can be stably charged.

FIG. 7 is an explanatory diagram showing an example of the relationship between the voltage Vba and the charging power Pba of the battery 22 of the example and the comparative example when the same current is passed through the power transmitting coil 141 in the example and the comparative example. be. In the figure, the solid line indicates the example, and the dashed-dotted line indicates the comparative example. In the comparative example, the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 are set to a relatively large value Cdhi regardless of the voltage Vba of the battery 22 . The tendency (appearance) of FIG. 7 was confirmed by the present inventors through analysis or the like. As shown in FIG. 7, in the region where the voltage Vba of the battery 22 is less than the threshold value Vref, the charging power Pba of the battery 22 is larger in the embodiment than in the comparative example.

FIG. 8 is an explanatory diagram showing an example of the relationship between the coupling coefficient between the power transmission coil 141 of the power transmission device 130 and the power reception coil 33 of the power reception device 30 and the power factor of the power transmission coil 141 . FIG. 9 is an explanatory diagram showing an example of the relationship between this coupling coefficient and the current that should flow through the power transmission coil 141 in order to charge the battery 22 with relatively large power. As shown in FIG. 8, the lower the coupling coefficient, the lower the power factor of the power transmission coil 141. This tendency was confirmed by the present inventors through analysis and the like. 8, in order to charge the battery 22 with relatively large power, it is necessary to increase the current to be supplied to the power transmission coil 141 as the coupling coefficient is lower, as shown in FIG. Therefore, when the coupling coefficient is low, the copper loss of power transmission coil 141 increases, so the significance of implementing the present invention increases.

In the power receiving device 30 of the embodiment described above, at the start of non-contact charging, the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 are set to a relatively small value Cdlo, and the voltage of the battery 22 is reduced as the non-contact charging continues. When Vba rises and reaches or exceeds the threshold Vref, the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 are switched to a relatively large value Cdhi. As a result, the voltage Vba of the battery 22 is less than the threshold Vref, compared to the case where the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 are set to a relatively large value Cdhi regardless of the voltage Vba of the battery 22. charging efficiency can be improved.

Further, in the power transmission device 130 of the embodiment, when switching the first and second capacitance values Cd1 and Cd2 of the capacitance circuit 44 of the power reception device 30, the AC/DC converter 132 and the inverter 134 are stopped. As a result, the non-contact charging is interrupted, so that the capacitance circuit 44 can be protected.

The correspondence relationship between the main elements of the embodiments and the main elements of the invention described in the column of Means for Solving the Problems will be described. In the embodiment, the power receiving resonance circuit 32 having the power receiving coil 33 and the capacitor 34 corresponds to the "power receiving resonance circuit", and the voltage doubler rectifier circuit 40 having the diode bridge circuit 42 and the capacitor circuit 44 corresponds to the "voltage doubler rectifier circuit". , and the vehicle ECU 70 corresponds to a "control unit".

Note that the correspondence relationship between the main elements of the examples and the main elements of the invention described in the column of Means for Solving the Problems is the Since it is an example for specifically explaining the mode for solving the problem, it does not limit the elements of the invention described in the column of the means for solving the problem. That is, the interpretation of the invention described in the column of Means to Solve the Problem should be made based on the description in that column, and the Examples are based on the description of the invention described in the column of Means to Solve the Problem. This is only a specific example.

Although the embodiments for carrying out the present invention have been described above, the present invention is not limited to such embodiments at all, and can be modified in various forms without departing from the scope of the present invention. Of course, it can be implemented.

INDUSTRIAL APPLICABILITY The present invention can be used in the power receiving device manufacturing industry and the like.

REFERENCE SIGNS LIST 10 contactless power transmission/reception system 20 automobile 22 battery 30 power receiving device 31 power receiving unit 32 power receiving resonance circuit 33 power receiving coil 34 capacitor (first capacity unit) 35a vehicle side first line 35b vehicle side second line, 36 filter circuit, 37 coil, 38, 39 capacitor, 40 voltage doubler rectifier circuit, 40a first input terminal, 40b second input terminal, 42 diode bridge circuit, 44 capacity circuit (second capacity section), 48 smoothing capacitor 60 voltage sensor 62,63,64 current sensor 70 vehicle ECU 80 communication unit 130 power transmission device 131 power transmission unit 132 AC/DC converter 134 inverter 134a first output terminal 134b second second Output terminal 136 Filter circuit 137 Coil 138 Capacitor 140 Power transmission resonance circuit 141 Power transmission coil 142 Capacitor 144a Power transmission side first line 144b Power transmission side second line 160 Voltage sensor 162, 163, 164 Current sensor, 170 Power transmission ECU, 80, 180 Communication unit, 190 AC power supply, C21 to C24 Capacitors, D11 to D14, D21 to D24 Diodes, S11 to S14 Switching elements, S21 Switch.

Claims (1)

A contactless power transmission/reception system comprising: a power transmission device; and a power reception device that supplies power received from the power transmission device in a contactless manner to an electrical load,
The power transmission device includes a power transmission unit having the power transmission coil, and a power transmission side control section that controls the power transmission unit,
The power receiving device
a power receiving coil capable of contactlessly receiving power from the power transmitting coil; and a power receiving resonance circuit including a first capacitor connected to the power receiving coil;
A diode bridge circuit connected to the power receiving resonance circuit, and a second capacitor unit connected in parallel to the diode bridge circuit and having a variable capacitance, which rectifies and boosts the power from the power receiving resonance circuit. and a voltage doubler rectifier circuit for supplying to the electrical load;
a control unit that controls the capacitance value of the second capacitance unit to be smaller when the voltage of the electric load is less than a predetermined voltage compared to when the voltage of the electric load is equal to or higher than the predetermined voltage;
with
When the voltage of the electrical load rises from less than the predetermined voltage to the predetermined voltage or more and the power receiving device increases the capacitance value of the second capacitance unit, the power transmission side control unit controls the power transmission coil and controlling the power transmission unit such that power transmission and reception with the power receiving coil is interrupted;
Contactless power transmission and reception system .

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