JP6323346B2 - Power transmission equipment - Google Patents

Description

  The present invention relates to a power transmission device, and more particularly to a power transmission device that transmits power to a power receiving device in a contactless manner.

  Conventionally, as this type of technology, a system that controls power supply frequency of a power transmission device based on a standardized transmission current in a system that transmits power from a power transmission device to a power receiving device in a contactless manner has been proposed (for example, a patent) Reference 1). The normalized transmission current is defined as the second transmission current with respect to the maximum value of the first transmission current. The first power transmission current is defined as a power transmission current of the power transmission device in a state where the power transmission device and the power reception device are not coupled, and the second power transmission current is a power transmission in a state where the power transmission device and the power reception device are inductively coupled. It is defined as the transmission current of the device. When the normalized transmission current is 1/2 or more, the power supply frequency is set to the resonance frequency, and when the normalized transmission current is less than 1/2, the power supply frequency is variably controlled so that the normalized frequency becomes 1/2. . By controlling in this way, the received power can be increased and the power efficiency can be maximized only by controlling the power supply frequency of the power transmission device.

JP 2014-103754 A

  In many cases, a power transmission device in a non-contact power transmission system includes an inverter that is driven by pulse width modulation (PWM) control in order to adjust the frequency and power of AC power for power transmission. In this case, the inverter is generally composed of four switching elements Q91 to Q94 and four diodes D91 to D94 connected in parallel to the switching elements Q91 to Q94 in the reverse direction, as shown in FIG. Is done. Two switching elements Q91 to Q94 are arranged in pairs so as to be on the source side and the sink side with respect to the positive electrode bus and the negative electrode bus, respectively, and a power transmission coil is connected to each connection point of the paired switching elements. Are connected to each other.

  In a power transmission device including such an inverter, the phase of current may advance (advance) with respect to an alternating voltage by PWM control. FIG. 13 shows an example of the relationship between the on / off states of switching elements Q91 to Q94 and the output voltage and current states of the inverter. In “Inverter output voltage and current” in the figure, the solid broken line indicates the output voltage, and the solid line sine curve indicates the current when the current phase is advanced with respect to the voltage phase. Consider a case where the switching element Q91 shifts from an off state to an on state. At time T1 when switching element Q91 is off, the inverter output voltage has a value of 0, but the current has a positive value because the phase has advanced. At this time, as shown in FIG. 14A, the current flows from the lower power line on the power transmission coil side to the on-state switching element Q94, the on-state switching element Q93 and the diode D93, and the power transmission coil side. It flows in the order of the power lines. At time T2 immediately after the switching element Q91 is turned on, the inverter output voltage has a positive value, and the current maintains a positive value. At this time, as shown in FIG. 14B, the current flows from the positive bus (upper bus) to the power line on the power transmission coil side via the switching element Q91 in the on state, and the power transmission coil side. Flows from the lower power line to the negative bus (lower bus) via the switching element Q94 in the on state. A forward bias is applied to the diode D93 at time T1 when the switching element Q91 is in the OFF state, and a reverse bias is applied at time T2 immediately after the switching element Q91 is turned on. For this reason, due to the recovery characteristics of the diode, a recovery current flows through the diode D93 as shown by the thick arrow in FIG. Since this recovery current is a short circuit current, it may cause abnormal heat generation or failure of the power transmission device.

  In order to deal with such a problem, in the case where a high-frequency noise filter is provided on the output side of the inverter, it is conceivable to delay the current phase by increasing the inductance of the filter. However, since the inductance for phase adjustment differs depending on the coupling coefficient between the power transmission coil and the power reception coil, in some cases, the power factor is significantly deteriorated, making it difficult to transmit the target power.

  The main purpose of the power transmission device of the present invention is to suppress the flow of the recovery current through the diode and more appropriately transmit the target power.

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

The power transmission device of the present invention is
A power transmission device that transmits power to a power receiving device in a contactless manner,
An inverter having a plurality of switching elements and a plurality of diodes, and converting DC power derived from an external power source into AC power;
A power transmission unit that transmits power to the power reception unit of the power reception device;
A filter having a circuit capable of adjusting inductance, and removing high-frequency noise of AC power from the inverter and supplying the power transmission unit;
A control unit that estimates a coupling coefficient between the power receiving unit and the power transmission unit, and adjusts the inductance of the filter so that the inductance increases as the coupling coefficient increases;
It is a summary to provide.

  In the power transmission device of the present invention, the filter that removes the high-frequency noise of the AC power from the inverter and supplies it to the power transmission unit has a circuit that can adjust the inductance. Then, the coupling coefficient between the power reception unit and the power transmission unit is estimated, and the inductance of the filter is adjusted so that the inductance increases as the coupling coefficient increases. This inductance adjustment is for appropriately delaying the phase of the output current from the inverter with respect to the output voltage. When the current phase is advanced with respect to the output voltage, as detailed in “Problems to be solved by the invention”, a recovery current (short-circuit current) flows through the diode at the timing of turning on the switching element, and power transmission It may cause abnormal heat generation or failure of the device. Therefore, such an inconvenience can be avoided by appropriately delaying the phase of the output current with respect to the output voltage. The inductance necessary for appropriately delaying the phase of the output current from the inverter with respect to the output voltage may be relatively small when the coupling coefficient is relatively small, and relatively large when the coupling coefficient k is relatively large. is there. Further, if a large filter inductance is used when the coupling coefficient is relatively small, the power factor is significantly deteriorated, and it may be difficult to transmit and receive target power. Therefore, by adjusting the filter inductance so that the inductance increases as the coupling coefficient increases, the phase of the output current from the inverter can be appropriately delayed with respect to the output voltage, and the power factor deteriorates and the target power It is possible to suppress the difficulty of power transmission / reception.

  In such a power transmission device of the present invention, the filter includes a first inductor connected to one power line of the pair of power lines on the output side of the inverter, and the other power line of the pair of power lines. And a switch connected to the other power line in parallel with the second inductor, and the control means turns off the switch when the coupling coefficient is equal to or greater than a predetermined value. The switch may be a means for turning on the switch when the coupling coefficient is less than the predetermined value. In this way, with a simple configuration, the inductance can be adjusted and the phase of the output current from the inverter can be appropriately delayed with respect to the output voltage.

  In the power transmission apparatus of the present invention, the filter may include a variable inductor, and the control unit may be a unit that controls the variable inductor so that the inductance tends to increase as the coupling coefficient increases. . In this way, the inductance can be varied according to the coupling coefficient.

  In the power transmission device of the present invention, the control means may be means for estimating the coupling coefficient based on an output impedance of the inverter. This is because the output impedance of the inverter can be regarded as a function of the coupling coefficient. In this case, the control means determines that the output coefficient is a function of the self-inductance of the power transmitting unit, the self-inductance of the power receiving unit, the impedance of the power receiving device excluding the power receiving unit, and the coupling coefficient. It can also be a means for estimation. Further, in this case, the control means may be means for estimating the coupling coefficient by treating the self-inductance of the power receiving unit and the impedance of the power receiving device excluding the power receiving unit as constants. This is because when the power receiving device is standardized and the reactance of the power receiving unit and the impedance of the power receiving device excluding the power receiving unit are not changed, these can be treated as constants. Here, the impedance of the power receiving device excluding the power receiving unit means the impedance behind the power receiving unit. Further, the control means is configured to calculate a self-inductance of the power receiving unit and an impedance of the power receiving device excluding the power receiving unit, or a ratio between the self inductance of the power receiving unit and the impedance of the power receiving device excluding the power receiving unit, It is also possible to obtain the coupling coefficient by obtaining from a power receiving device. In this way, even when the power receiving apparatus is not standardized, the output impedance can be calculated more accurately, and the coupling coefficient can be calculated more accurately. Note that the ratio between the self-inductance of the power receiving unit and the impedance of the power receiving device excluding the power receiving unit may be obtained when the output impedance is proportional to the self inductance of the power receiving unit and inversely proportional to the impedance of the power receiving device excluding the power receiving unit. It is because it has a relationship.

  In the power transmission device of the present invention, the control means is means for adjusting the AC power by switching control of a plurality of switching elements of the inverter, and a current phase from the inverter to the power transmission unit is an output voltage. It is also possible to adjust the frequency of the AC power in such a direction that the advance angle of the current phase becomes smaller when it is detected that the advance angle is detected. By performing such adjustment once or a plurality of times, the advance angle of the current phase with respect to the output voltage is eliminated. Therefore, the inconvenience caused by the advance of the current phase with respect to the output voltage, that is, the recovery current (short-circuit current) flows to the diode at the timing when the switching element is turned on, and the inconvenience that causes abnormal heat generation and failure of the power transmission device is suppressed. can do. The control means may be means for adjusting the frequency of the AC power so that the advance angle of the current phase is eliminated.

  In the power transmission device of the present invention in which the frequency adjustment is performed, the control unit defines a relationship between a coupling coefficient between the power reception unit and the power transmission unit, a frequency of the AC power, and the current phase with respect to an output voltage. And calculating a coupling coefficient between the power reception unit and the power transmission unit, and adjusting the frequency of the AC power in a direction in which the advance angle of the current phase is reduced using the calculated coupling coefficient and the map. It can also be a means. This is based on the fact that the frequency and phase characteristics of current in AC power differ depending on the coupling coefficient. Note that the map can be created as a three-dimensional map by obtaining the relationship between the frequency and the current phase while sequentially changing the coupling coefficient by experiment or the like. Thus, since the frequency is adjusted using the coupling coefficient and the map, the advance angle of the current phase can be eliminated more appropriately. In this case, the control means may be means for adjusting the frequency of the AC power by obtaining a frequency adjustment amount from the coupling coefficient and the map.

  In the power transmission device of the present invention, the control means is means for detecting an advance angle of the current phase based on a current value at an ON or OFF timing of any one of the plurality of switching elements. The control means is means for detecting the advance angle of the current phase based on the voltage of the AC power at the timing when the sign of the current from the inverter to the power transmission unit changes. You can also

It is a block diagram which shows the outline of a structure of the non-contact power transmission / reception system 10 provided with the power transmission apparatus 130 of an Example. It is a block diagram which shows the outline of a structure of the non-contact power transmission / reception system 10 provided with the power transmission apparatus 130 of an Example. 3 is a configuration diagram illustrating an example of a configuration of an inverter 142. FIG. 4 is a configuration diagram illustrating an example of a configuration of a filter 144. FIG. It is a flowchart which shows an example of the inductance setting process performed by power transmission ECU170. It is explanatory drawing which shows an example of the time change of the on-off state of the switching elements Q1-Q4 of the inverter 142, and the output voltage and output current of the inverter 142. FIG. It is explanatory drawing which shows the electric current which flows into an inverter at time T1, T2 of FIG. It is a flowchart which shows an example of the frequency adjustment process performed by power transmission ECU170. It is explanatory drawing which shows an example of the map for frequency adjustment. It is explanatory drawing which shows an example of the filter 144B of a modification. It is a flowchart which shows an example of the inductance setting process of a modification. It is a block diagram which shows an example of a structure of the inverter of a prior art example. It is explanatory drawing which shows an example of the on-off state of the switching elements Q91-Q94 of an inverter of a prior art example, and a time change of an inverter output voltage and electric current. It is explanatory drawing which shows the electric current which flows into an inverter at time T1, T2 of FIG.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 and FIG. 2 are block diagrams showing an outline of a configuration of a non-contact power transmission / reception system 10 including a power transmission device 130 as one embodiment of the present invention. As shown in FIGS. 1 and 2, the non-contact power transmission / reception system 10 according to the embodiment includes a power transmission device 130 installed in a parking lot or the like and a power reception device 30 that can receive power from the power transmission device 130 in a contactless manner. And an automobile 20.

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

  The power transmission unit 131 includes an AC / DC converter 140, an inverter 142, a filter 144, and a power transmission resonance circuit 132. The AC / DC converter 140 is configured as a well-known DC / DC converter that converts AC power from the AC power supply 190 into DC power having an arbitrary voltage.

  FIG. 3 shows an example of the configuration of the inverter 142. As illustrated in FIG. 3, the inverter 142 includes four switching elements Q1 to Q4, four diodes D1 to D4 connected in parallel to the switching elements Q1 to Q4 in the reverse direction, and a smoothing capacitor C. ing. As the four switching elements Q1 to Q4, for example, MOSFET (a kind of field-effect transistor: metal-oxide-semiconductor field-effect transistor) can be used. The switching elements Q1 to Q4 are arranged in pairs so as to be on the source side and the sink side with respect to the positive electrode bus and the negative electrode bus, respectively, and transmit power to each connection point of the paired switching elements. Both terminals of the power coil are connected. The inverter 142 converts the DC power from the AC / DC converter 140 into AC power having a desired frequency by pulse width modulation (PWM) control for switching control of the switching elements Q1 to Q4.

  FIG. 4 shows an example of the configuration of the filter 144. As illustrated in FIG. 4, the filter 144 is a filter that removes two-stage high-frequency noise caused by the first filter (inductors L11, L12, capacitor C11) and the second filter (inductors L21, L22, capacitor C21). It is configured. The first filter includes inductors L11 and L12 connected to one of the power lines from the inverter 142 (the upper power line in FIG. 4) and the other power line (the lower power line in FIG. 4), respectively. And a capacitor C11 attached to both power lines on the downstream side (the power transmission resonance circuit 132 side) of the inductor L11 and the inductor L12. In the first filter, a switch SW is attached to the other power line (the lower power line in FIG. 4) in parallel with the inductor L12. The second filter includes inductors L21 and L22 connected to one of the power lines from the first filter (the upper power line in FIG. 4) and the other power line (the lower power line in FIG. 4), respectively. And a capacitor C21 attached to both power lines on the rear stage side (the power transmission resonance circuit 132 side) of the inductor L21 and the inductor L22.

  The power transmission resonance circuit 132 includes, for example, a power transmission coil 134 installed on a floor surface of a parking lot, and a capacitor 136 connected in series to the power transmission coil 134. The power transmission resonance circuit 132 is designed such that the resonance frequency is a predetermined frequency Fset (several tens to several hundreds kHz). Therefore, the inverter 142 basically converts the DC power from the AC / DC converter 140 into AC power having a predetermined frequency Fset.

  Although not shown, power transmission ECU 170 is configured as a microprocessor centered on a CPU, and includes a ROM for storing processing programs, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU. . The power transmission ECU 170 is input with the following current and voltage through the input port. An output current Is from the current sensor 150 that detects the current (output current) Is of the AC power converted by the inverter 142. A voltage Vs from the voltage detection unit 152 that detects the AC voltage from the inverter 142 by converting it into a DC voltage. A current Itr of the power transmission resonance circuit 132 from the current sensor 154 that detects an alternating current flowing in the power transmission resonance circuit 132. A voltage (transmission voltage) Vtr between terminals of the resonance circuit for power transmission 132 from the voltage detection unit 156 that detects the AC voltage between the terminals of the resonance circuit for power transmission 132 by converting it into a DC voltage. The voltage detection units 152 and 156 have a rectifier circuit and a voltage sensor. The power transmission ECU 170 outputs a control signal to the AC / DC converter 140, a control signal to the inverter 142, a drive signal to the switch SW of the filter 144, and the like via the output port.

  The vehicle 20 is configured as an electric vehicle, and includes a traveling motor 22, an inverter 24 for driving the motor 22, and a battery 26 that exchanges electric power with the motor 22 via the inverter 24. A system main relay 28 is provided between the inverter 24 and the battery 26. In addition, the automobile 20 communicates with a power receiving unit 31 connected to the battery 26, a vehicle electronic control unit (hereinafter referred to as “vehicle ECU”) 70 that controls the entire vehicle, and communication with the power transmission device 130. And a communication unit 80 for performing wireless communication with the unit 180.

  The power reception unit 31 includes a power reception resonance circuit 32, a filter 42, and a rectifier 44. The power receiving resonance circuit 32 includes, for example, a power receiving coil 34 installed on the bottom surface (floor panel) of the vehicle body, and a capacitor 36 connected in series to the power receiving coil 34. The power receiving resonance circuit 32 is designed such that the resonance frequency becomes a frequency (ideally, the predetermined frequency Fset) near the predetermined frequency Fset (resonance frequency of the power transmission resonance circuit 132). The filter 42 is configured as a well-known filter that removes one-stage or two-stage high-frequency noise due to a capacitor and an inductor, and removes high-frequency noise of AC power received by the power receiving resonance circuit 32. The rectifier 44 is configured as, for example, a known rectifier circuit using four diodes, and converts AC power received by the power receiving resonance circuit 32 and from which high-frequency noise has been removed by the filter 42 into DC power. The power receiving unit 31 can be disconnected from the battery 26 by a relay 48.

  Although not shown, the vehicle ECU 70 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU. . Data necessary for drive control of the motor 22 is input to the vehicle ECU 70 via an input port. The vehicle ECU 70 also includes a received current Ire from the current sensor 50 that detects the current (received current) Ire rectified by the rectifier 44 and a voltage sensor that detects the voltage (received voltage) Vre of the DC power. The power reception voltage Vre from 52 is input via the input port. From the vehicle ECU 70, a control signal for switching control of a switching element (not shown) of the inverter 24 to drive the motor 22, an on / off signal to the system main relay 28, and the like are output via an output port. The vehicle ECU 70 determines the storage ratio SOC of the battery 26 based on the battery current Ib detected by a current sensor (not shown) attached to the battery 26 and the battery voltage Vb detected by a voltage sensor (not shown) attached to the battery 26. Is calculated.

  Next, the operation of the power transmission device 130 in the thus configured contactless power transmission / reception system 10, particularly when the automobile 20 stops for charging the battery 26 and starts power transmission / reception by the power transmission device 130 and the power reception device 30. The operation will be described. FIG. 5 is a flowchart illustrating an example of an inductance setting process executed by the power transmission ECU 170 before the start of power transmission / reception.

  When the inductance setting process is executed, the power transmission ECU 170 first inputs a coupling coefficient k between the power transmission resonance circuit 132 and the power reception resonance circuit 32 (step S100). The coupling coefficient k is estimated when the positions of the power transmission resonance circuit 132 and the power reception resonance circuit 32 are confirmed. For estimation of the coupling coefficient k, first, the output current Is of the inverter 142 from the current sensor 150 and the voltage Vs from the voltage detection unit 152 are input, and the output impedance from the inverter 142 is based on the output current Is and the voltage Vs. Calculate Zs. An effective value is used as the output current Is when calculating the impedance Zs. Then, the coupling coefficient k is obtained based on the output impedance Zs. The output impedance Zs can be expressed as a function of the coupling coefficient k as shown in the following equation (1). In Equation (1), “ω” is an angular frequency, “L1” is the self-inductance of the power transmission coil 134, “L2” is the self-inductance of the power reception coil 34, and “RL” is behind the power reception resonance circuit 32 (filter). 42 side impedance). Here, the self-inductance L2 of the power receiving coil 34 and the impedance RL behind the power receiving resonance circuit 32 (on the filter 42 side) can be treated as constants. Since the power receiving device 30 is mounted on the automobile 20, the specifications thereof may be different. However, in order to maintain good power transmission / reception efficiency, the power receiving device 30 of a certain standard needs to be used. For this reason, considering the standardized power receiving device 30, the self-inductance L2 and the impedance RL can be treated as constants. In the contactless power transmission / reception system 10 according to the embodiment, the power reception device 30 and the power transmission device 130 communicate with each other through the communication unit 80 and the communication unit 180. The ratio of the inductance L2 and the impedance RL (L2 / RL)) may be acquired from the automobile 20 by communication.

  When the coupling coefficient k is input, the coupling coefficient k is compared with a predetermined value kref (step S110). The predetermined value kref is set as an intermediate value in the range that the coupling coefficient k can take in the design of the power transmission resonance circuit 132 and the power reception resonance circuit 32. Therefore, when the coupling coefficient k is equal to or greater than the predetermined value kref, it can be determined that the coupling coefficient k is relatively large. When the coupling coefficient k is less than the predetermined value kref, it is determined that the coupling coefficient k is relatively small. be able to. When the coupling coefficient k is greater than or equal to the predetermined value kref, the switch SW of the filter 144 is turned off (step S120), and when the coupling coefficient k is less than the predetermined value kref, the switch SW of the filter 144 is turned on (step S130). Exit. The reason why the switch SW is turned on / off in this way is to make the phase θ of the output current Is from the inverter 142 appropriately retarded with respect to the output voltage. When the coupling coefficient k is relatively small, the inductance necessary for appropriately delaying the phase θ of the output current Is from the inverter 142 may be relatively small. Therefore, when the coupling coefficient k is less than the predetermined value kref, the switch SW of the filter 144 is turned on to avoid the inductor L12 of the filter 144 and reduce the inductance of the first filter. If a large inductance is used as the filter 144 when the coupling coefficient k is relatively small, the power factor is significantly deteriorated, and transmission / reception of the target power may become difficult. On the other hand, when the coupling coefficient k is relatively large, the inductance necessary for appropriately delaying the phase θ of the output current Is from the inverter 142 becomes large. For this reason, when the coupling coefficient k is greater than or equal to the predetermined value kref, the switch SW of the filter 144 is turned off to cancel the short circuit of the inductor L12 of the filter 144 and increase the inductance of the first filter. That is, by turning the switch SW on and off in this way, the phase θ of the output current Is from the inverter 142 is appropriately retarded with respect to the output voltage.

  FIG. 6 shows an example of ON / OFF states of the switching elements Q1 to Q4 of the inverter 142 and temporal changes in the output voltage and output current of the inverter 142. In “Inverter output voltage and current” in the figure, the solid broken line indicates the output voltage, the solid line sine curve indicates the current when the current phase θ is advanced with respect to the output voltage, and the dashed sine curve. Indicates the current when the current phase θ is retarded with respect to the output voltage. When the current phase θ is advanced with respect to the output voltage (in the case of the sine curve of the solid line in FIG. 6), the “problem to be solved by the invention” in this specification is described with reference to FIG. So that the current flows. That is, current flows as shown in FIG. 14A at time T1 immediately before switching element Q1 (Q91 in FIG. 14) is turned on in FIG. 6, and switching element Q1 (Q91 in FIG. 14) is turned on. Immediately after time T2, a current flows as shown in FIG. A forward bias is applied to the diode D3 (D93 in FIG. 14) at a time T1 immediately before the switching element Q1 is turned on, and a reverse bias is applied at a time T2 immediately after the switching element Q1 is turned on. Therefore, due to the recovery characteristics of the diode, a recovery current flows through the diode D3 (D93 in FIG. 14) as shown by the thick arrow in FIG. 14B. When the current phase θ is retarded with respect to the output voltage (in the case of the sine curve of the broken line in FIG. 6), the current flows as follows. In the time T1 immediately before the switching element Q1 is turned on in FIG. 6, the current is switched from the power line on the power transmission coil side to the on-state switching element Q3, as shown in FIG. It flows through the element Q4 and the diode D4 to the lower power line on the power transmission coil side. In time T2 immediately after the switching element Q1 is turned on in FIG. 6, the current is supplied from the power line on the power transmission coil side via the switching element Q1 in the on state, as shown in FIG. 7B. And flows from the negative bus on the power supply side to the lower power line on the power transmission coil side via the switching element Q4 and the diode D4 in the on state. Since the reverse bias is applied to the diode D3 both at the time T1 immediately before the switching element Q1 is turned on and at the time T2 immediately after the switching element Q1 is turned on, no recovery current flows. Therefore, the diode SW is turned on and off based on the coupling coefficient k to adjust the inductance of the filter 144 so that the current phase θ is appropriately retarded with respect to the output voltage. It is possible to prevent the recovery current from flowing. As described above, the recovery current that flows through the diode D3 at the timing when the switching element Q1 is turned on becomes a short-circuit current. Therefore, when the switch SW is turned on or off based on the coupling coefficient k, the short-circuit current flows. Can not be.

  Next, the operation | movement at the time of the power transmission / reception of the power transmission apparatus 130 of an Example is demonstrated. The power transmission ECU 170 repeatedly executes the frequency adjustment process illustrated in FIG. 8 every predetermined time (for example, every several hundred msec) during power transmission / reception.

  When the frequency adjustment process is executed, the power transmission ECU 170 first detects from the inverter 142 whether or not the phase (current phase) θ of the output current Is is advanced with respect to the output voltage (step S200). Whether or not the current phase θ is advanced can be detected, for example, by detecting based on the output current Is of the inverter 142 at the timing when the switching element Q1 is turned on. As shown in FIG. 6, at the time T2 when the switching element Q1 is turned on, when the current phase θ is advanced with respect to the output voltage (solid sine curve in FIG. 6), the output current Is is positive. When the current phase θ is retarded with respect to the output voltage (the sine curve of the broken line in FIG. 6), the output current Is becomes a negative value. Therefore, it is possible to detect that the current phase θ is advanced when the output current Is of the inverter 142 is a positive value at the timing when the switching element Q1 is turned on. As can be seen from the sine curve of the solid line in FIG. 6, the detection that the current phase θ is advanced is based on the fact that the output current Is of the inverter 142 at the timing of turning off the switching element Q1 is a negative value. Can also be done. Further, since the switching element Q1 is reversed when the switching element Q3 is turned on / off, the detection of the advancement of the current phase θ can be performed at the timing when the switching element Q3 is turned off or when the switching element Q3 is turned on. . Further, detection of the advance of the current phase θ is based on whether or not the output voltage is 0 when the sign of the output current Is changes (from positive to negative or from negative to positive). Can also be done. Alternatively, detection that the current phase θ is advanced can be performed based on the value of the power factor and the heat generation state of the diode D3.

  Here, the reason why the phase θ of the output current from the inverter 142 is advanced or retarded with respect to the output voltage regardless of the adjustment of the inductance of the filter 144 will be described. The power transmission resonance circuit 132 of the power transmission device 130 is designed so that the resonance frequency becomes the predetermined frequency Fset, and the resonance frequency of the power reception resonance circuit 32 of the power reception device 30 mounted on the automobile 20 also becomes the predetermined frequency Fset. Designed to. For this reason, if there is no manufacturing error of parts, and if the power transmission resonance circuit 132 and the power reception resonance circuit 32 at the time of power transmission / reception are accurately in the design position, the current phase θ advances with respect to the output voltage. There is no corner or delay. However, there are manufacturing errors in the components of the power transmission resonance circuit 132 and the power reception resonance circuit 32, and the frequency / phase characteristics vary depending on the individual. For this reason, the phase θ of the output current Is is advanced or retarded with respect to the output voltage. In addition, the positions of the power transmission resonance circuit 132 and the power reception resonance circuit 32 at the time of power transmission / reception are determined by the parking of the automobile 20, and thus are often not designed positions. If the power transmission resonance circuit 132 and the power reception resonance circuit 32 are displaced during power transmission and reception, the coupling coefficient k and the inductance change, and the frequency / phase characteristics change. For this reason, the phase θ of the output current Is is advanced or retarded with respect to the output voltage. Further, when the inverter 142 is converted to AC power by pulse width modulation control, the rise timing of the output voltage changes due to the change of the duty ratio, so that the current waveform does not change at all. In some cases, the current phase θ is advanced with respect to the voltage. The inconvenience when the phase θ of the output current from the inverter 142 is advanced with respect to the output voltage has been described in detail.

  If it is not detected that the current phase θ is advanced relative to the output voltage by detecting whether the current phase θ is advanced relative to the output voltage in step S200, the frequency is adjusted. If it is determined that it is not necessary, the present process is terminated. On the other hand, when it is detected that the current phase θ is advanced with respect to the output voltage, the frequency is adjusted by the following processing.

  First, the coupling coefficient k between the power transmission resonance circuit 132 and the power reception resonance circuit 32 is input (step S220), and the frequency adjustment direction and adjustment amount are determined based on the input coupling coefficient k (step S230). The frequency adjustment direction is a direction in which the advance angle of the current phase θ with respect to the output voltage decreases, that is, a direction in which the current phase θ is retarded. In the embodiment, the frequency adjustment direction and the amount of adjustment are determined by preliminarily examining the relationship between the coupling coefficient k, the frequency, and the current phase θ through an experiment or the like and storing it as a frequency adjustment map. And the frequency adjustment direction and the adjustment amount are derived. An example of the frequency adjustment map is shown in FIG. In the figure, the current phase θ is a case where the current phase θ is retarded with respect to the output voltage when the value is positive, and the case where the current phase θ is advanced when the value is negative. As shown in FIG. 9, when the coupling coefficient k is large, the current phase θ is retarded when the frequency of the output voltage of the inverter 142 is decreased, and the current phase θ is advanced when the frequency is increased. When the coupling coefficient k is large, the amount of advancement or retardation of the current phase θ is small even when the frequency adjustment amount is relatively large. On the other hand, when the coupling coefficient k is small, the current phase θ is advanced when the frequency of the output voltage of the inverter 142 is decreased, and the current phase θ is retarded when the frequency is increased. When the coupling coefficient k is small, the advance amount and the retard amount of the current phase θ are large even if the frequency adjustment amount is small. In step S230, since the relationship between the frequency and the current phase θ is determined by the coupling coefficient k, the frequency adjustment direction is such that the advance angle of the current phase θ with respect to the output voltage is reduced, that is, the current phase θ is retarded. Can be determined. Further, the adjustment amount can be determined to be a predetermined retardation amount (for example, the retardation amount is 5 degrees, 7 degrees, etc.). For example, when “k = small” in the map of FIG. 9, the frequency adjustment direction is a direction in which the frequency is increased, and the adjustment amount is a slight amount (for example, 0.2 kHz or 0.5 kHz). When “k = large” in the map of FIG. 9, the frequency adjustment direction is a direction in which the frequency is decreased, and the adjustment amount is a relatively large amount (for example, 2 kHz or 5 kHz). When “k = medium” in the map of FIG. 9, the frequency adjustment direction is a direction in which the frequency is increased, and the adjustment amount is an intermediate amount (for example, 1 kHz or 1.5 kHz). The coupling coefficient k has been described in detail.

  When the frequency adjustment direction and the adjustment amount are determined in this way, the frequency of the output voltage of the inverter 142 is adjusted using the determined frequency adjustment direction and adjustment amount (step S240), and this process ends. The frequency of the output voltage of inverter 142 can be adjusted by changing the switching control cycle of switching elements Q1 to Q4.

  If the advance angle of the output current Is of the inverter 142 with respect to the output voltage of the phase θ is not resolved even after performing such frequency adjustment processing, the frequency adjustment process is executed again, and therefore the advance angle of the output current Is with respect to the output voltage of the phase θ. Is resolved. That is, the current phase θ is retarded with respect to the output voltage. Therefore, when the current phase θ is advanced with respect to the output voltage, the frequency adjustment process is performed to eliminate the advance angle of the current phase θ with respect to the output voltage so that no recovery current flows in the diode D3. can do.

  In the power transmission device 130 in the non-contact power transmission and reception system 10 of the embodiment described above, when the coupling coefficient k between the power transmission resonance circuit 132 and the power reception resonance circuit 32 is equal to or greater than a predetermined value kref, the switch SW of the filter 144 is turned off. When the coupling coefficient k is less than the predetermined value kref, the switch SW of the filter 144 is turned on. Thereby, the phase θ of the output current Is from the inverter 142 can be appropriately retarded with respect to the output voltage. As a result, inconvenience due to the advance of the phase θ of the output current Is from the inverter 142 with respect to the output voltage, that is, abnormal heat generation or failure of the power transmission device 130 due to the flow of the recovery current (short-circuit current) of the diode D3. Inconvenience such as can be suppressed.

  Further, in the power transmission device 130 in the non-contact power transmission and reception system 10 of the embodiment, when it is detected that the phase θ of the output current Is of the inverter 142 is advanced with respect to the output voltage, the current based on the coupling coefficient k. The frequency of the output voltage of the inverter 142 is adjusted so that the advance angle of the phase θ decreases. As a result, the advance angle of the current phase θ is eliminated, and the recovery current (short-circuit current) can be prevented from flowing through the diode D3 at the timing when the switching element Q1 is turned on, and the recovery current (short-circuit current) flows through the diode D3. It is possible to suppress abnormal heat generation or failure of the power transmission device 130 due to the flow of current.

  In the power transmission device 130 of the embodiment, the switch SW is mounted in parallel with the inductor L12 on the other power line (the lower power line in FIG. 4) of the first filter of the filter 144, and the switch SW is turned on based on the coupling coefficient k. It was supposed to be off or off. However, a variable inductor Lch may be used in place of the inductor L12 as shown in the filter 144B of the modification of FIG. In this case, after executing the inductance setting process of the modification of FIG. 11 and inputting the coupling coefficient k (step S100), the variable inductor Lch is adjusted so that the inductance increases as the coupling coefficient k increases (step S110B). It should be. Further, two or more pairs of inductors and switches connected in parallel may be attached in series instead of the inductor L12 and the switch SW attached to the other power line. In this case, the switch may be turned on / off so that the inductance increases as the coupling coefficient k increases.

  In the power transmission device 130 according to the embodiment, the frequency adjustment amount is adjusted by a predetermined retardation amount. However, the frequency adjustment amount may be adjusted only by a predetermined frequency (for example, 0.5 kHz or 1 kHz). Further, the predetermined frequency of the adjustment amount may be changed based on the coupling coefficient k. For example, 2 kHz may be used as the adjustment amount when “k = large” in FIG. 9, and 0.1 kHz may be used as the adjustment amount when “k = small” in FIG. 9.

  In the embodiment, the power transmission device 130 in the contactless power transmission and reception system 10 including the power reception device 30 and the power transmission device 130 mounted on the automobile 20 has been described. However, the power reception device and power transmission mounted on a vehicle or a moving body other than the vehicle. It is good also as a form of the power transmission apparatus in the non-contact power transmission / reception system which has an apparatus, or a form of the power transmission apparatus in the non-contact power transmission / reception system which has a power reception apparatus and power transmission apparatus incorporated in facilities other than a moving body.

  The correspondence between the main elements of the embodiment 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 device 30 corresponds to a “power receiving device”, the power transmitting device 130 corresponds to a “power transmitting device”, the switching elements Q1 to Q4 correspond to “a plurality of switching elements”, and the diodes D1 to D4 include “ It corresponds to “a plurality of diodes”, the inverter 142 corresponds to “inverter”, the power receiving resonance circuit 32 corresponds to “power receiving unit”, the power transmission resonance circuit 132 corresponds to “power transmission unit”, and “filter 144” Corresponds to a filter, and the power transmission ECU 170 corresponds to “control means”.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the column of means for solving the problem. Therefore, the elements of the invention described in the column of means for solving the problems are not limited. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problems. It is only a specific example.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  The present invention can be used in the manufacturing industry of a power transmission device of a non-contact power transmission / reception system.

   DESCRIPTION OF SYMBOLS 10 Contactless power transmission / reception system, 20 Car, 22 Motor, 24 Inverter, 26 Battery, 28 System main relay, 30 Power receiving device, 31 Power receiving unit, 32 Power receiving resonance circuit, 34 Power receiving coil, 36 Capacitor, 42 Filter, 44 Rectifier, 48 relay, 50 current sensor, 52 voltage sensor, 70 vehicle electronic control unit (vehicle ECU), 80 communication unit, 130 power transmission device, 131 power transmission unit, 132 power transmission resonance circuit, 134 power transmission coil, 136 capacitor, 140 AC / DC converter, 142 inverter, 144, 144B filter, 150 current sensor, 152 voltage detection unit, 154 current sensor, 156 voltage detection unit, 170 power transmission electronic control unit (power transmission ECU), 180 Communication unit, 190 AC power source, C, C11, C21 capacitor, D1-D4, D91-D94 diode, L11, L12, L21, L22 inductor, Lch variable inductor, Q1-Q4, Q91-Q94 switching element.

Claims (11)

A power transmission device that transmits power to a power receiving device in a contactless manner,
An inverter having a plurality of switching elements and a plurality of diodes, and converting DC power derived from an external power source into AC power;
A power transmission unit that transmits power to the power reception unit of the power reception device;
A filter having a circuit capable of adjusting inductance, and removing high-frequency noise of AC power from the inverter and supplying the power transmission unit;
A control unit that estimates a coupling coefficient between the power receiving unit and the power transmission unit, and adjusts the inductance of the filter so that the inductance increases as the coupling coefficient increases;
A power transmission device comprising: The power transmission device according to claim 1,
The filter includes a first inductor connected to one of the pair of power lines on the output side of the inverter, and a second inductor connected to the other power line of the pair of power lines. A switch connected to the other power line in parallel with the second inductor,
The control means is means for turning off the switch when the coupling coefficient is greater than or equal to a predetermined value, and turning on the switch when the coupling coefficient is less than the predetermined value.
Power transmission device. The power transmission device according to claim 1,
The filter has a variable inductor;
The control means is means for controlling the variable inductor such that the inductance increases as the coupling coefficient increases.
Power transmission device. The power transmission device according to any one of claims 1 to 3,
The control means is means for estimating the coupling coefficient based on an output impedance of the inverter.
Power transmission device. The power transmission device according to claim 4,
The control means estimates the coupling coefficient on the assumption that the output impedance is a function of the self-inductance of the power transmitting unit, the self-inductance of the power receiving unit, the impedance of the power receiving device excluding the power receiving unit, and the coupling coefficient. Is,
Power transmission device. The power transmission device according to claim 5,
The control means is means for estimating the coupling coefficient by treating the self-inductance of the power receiving unit and the impedance of the power receiving device excluding the power receiving unit as constants.
Power transmission device. The power transmission device according to claim 6,
The control unit is configured to calculate a self-inductance of the power receiving unit and an impedance of the power receiving device excluding the power receiving unit, or a ratio between a self inductance of the power receiving unit and an impedance of the power receiving device excluding the power receiving unit. Means for estimating the coupling coefficient obtained from
Power transmission device. The power transmission device according to any one of claims 1 to 7,
The control means is means for adjusting the AC power by switching control of a plurality of switching elements of the inverter, and a current phase from the inverter to the power transmission unit is advanced with respect to an output voltage. A means for adjusting the frequency of the AC power in a direction in which the advance angle of the current phase decreases when it is detected that
Power transmission device. The power transmission device according to claim 8,
The control means includes a map that defines a relationship between a coupling coefficient between the power reception unit and the power transmission unit, a frequency of the AC power, and the current phase with respect to an output voltage, and the coupling between the power reception unit and the power transmission unit. A means for calculating a coefficient and adjusting the frequency of the AC power in a direction in which the advance angle of the current phase is reduced using the calculated coupling coefficient and the map;
Power transmission device. The power transmission device according to claim 8 or 9 , wherein
The control means is means for detecting an advance angle of the current phase based on a current value at an ON or OFF timing of any one of the plurality of switching elements.
Power transmission device. The power transmission device according to claim 8 or 9 , wherein
The control means is means for detecting an advance angle of the current phase based on a voltage of the AC power at a timing when a sign of a current from the inverter to the power transmission unit changes.
Power transmission device.

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