JP6213485B2 - 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. 9 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. 10A, 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, 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. 10 (b), 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 at 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.

  The main purpose of the power transmission device of the present invention is to prevent abnormal heat generation and failure of the power transmission device by preventing a recovery current from flowing through the diode.

  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 AC power from the inverter to a power reception unit of the power reception device;
Control means for adjusting the AC power by switching control of a plurality of switching elements of the inverter;
With
When the control means detects that the current phase of the output current from the inverter to the power transmission unit is advanced with respect to the output voltage, the frequency of the AC power decreases in the direction in which the advance angle of the current phase decreases. Is a means to adjust the
It is characterized by that.

  In the power transmission device according to the present invention, when it is detected that the current phase from the inverter to the power transmission unit is advanced with respect to the output voltage, the frequency of the AC power from the inverter is reduced in the direction in which the advance angle of the current phase is reduced. Adjust. 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. 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. When the advance angle of the current phase with respect to the output voltage is eliminated, it is possible to prevent a recovery current (short-circuit current) from flowing through the diode at the timing when the switching element is turned on. As a result, abnormal heat generation or failure of the power transmission device due to the recovery current (short-circuit current) can be suppressed. 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 such a power transmission device of the present invention, the control means has 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 the voltage phase, A means for calculating a coupling coefficient between the power reception unit and the power transmission unit, and using the calculated coupling coefficient and the map to adjust the frequency of the AC power in a direction in which the advance angle of the current phase decreases. You can also 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 in which the frequency is adjusted using the coupling coefficient and the map, the control unit may be a unit that calculates 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 calculating. Here, in general, as a method for calculating the coupling coefficient, a method of calculating from the received power and the transmitted power can be cited. However, in this method, it is necessary to transmit information about the received power to the power transmission device side. Arise. On the other hand, the output impedance of the inverter can be calculated only with information in the power transmission device. As a result, communication with the power receiving apparatus becomes unnecessary. Further, in this case, the control means may be means for calculating 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 self-inductance 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 good also as a means which acquires from a power receiving apparatus and calculates the said coupling coefficient. 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 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. 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 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 an example of the map for frequency adjustment. It is explanatory drawing which shows the electric current which flows into an inverter at time T1, T2 of FIG. 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. 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. The filter 144 is configured as a well-known filter that removes high-frequency noise due to a capacitor and an inductor, and removes high-frequency noise of AC power from the inverter 142.

  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. Further, the power transmission ECU 170 outputs a control signal to the AC / DC converter 140, a control signal to the inverter 142, and the like via an 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 non-contact power transmission / reception system 10 configured as described above, particularly the operation when adjusting the frequency of the inverter 142 will be described. FIG. 4 is a flowchart illustrating an example of the frequency adjustment process executed by the power transmission ECU 170. This process is repeatedly executed every predetermined time (for example, every several hundred msec). The frequency of the AC power from the inverter 142 is set to a predetermined frequency Fset that is a resonance frequency as an initial value, and the switching elements Q1 to Q4 are switched so that the AC power of the predetermined frequency Fset is output from the inverter 142. Be controlled.

  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 S100). 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. FIG. 5 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. As shown in the figure, at time T2 when the switching element Q1 is turned on, when the current phase θ is advanced with respect to the output voltage, the output current Is has a positive value, and the current phase θ is When the angle is retarded, the output current Is takes 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 FIG. 5, the detection that the current phase θ is advanced can also be performed by 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. . 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 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.

  As for the inconvenience when the phase θ of the output current from the inverter 142 is advanced with respect to the output voltage, the inverter 142 is configured as described in detail in “Problems to be Solved by the Invention” of this specification. The recovery current flows through the diode D3, which becomes a short-circuit current, which may cause abnormal heat generation or failure of the power transmission device 130.

  When it is not detected that the current phase θ is advanced with respect to the output voltage by detecting whether the current phase θ is advanced with respect to the output voltage in step S100, the frequency is adjusted. It is determined that it is not necessary (step S110), and this 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 output current Is of the inverter 142 from the current sensor 150 and the voltage Vs from the voltage detection unit 152 are input (step S120), and the output impedance Zs from the inverter 142 is determined based on the output current Is and the output voltage Vs. Calculate (step S130). Here, an effective value is used as the output current Is when the impedance Zs is calculated. Then, a coupling coefficient k is obtained based on the output impedance Zs (step S140). 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), that is, the impedance of the power receiving device 30 excluding the power receiving resonance circuit 32. 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. Therefore, the power transmission device 130 includes the self-inductance L2 and the impedance RL (or the self-power transmission device 130). 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 obtained, the frequency adjustment direction and the adjustment amount are determined based on the coupling coefficient k (step S150). 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, when the current phase θ is a positive value, the current phase θ is retarded with respect to the output voltage, and when the current phase θ is a negative value, the current phase θ is advanced. As shown in FIG. 6, 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 S150, 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. 6, 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). Further, when “k = large” in the map of FIG. 6, 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. 6, 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).

  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 S160), 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. 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. 5), 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. 10A at time T1 immediately before switching element Q1 (Q91 in FIG. 10) is turned on in FIG. 5, and switching element Q1 (Q91 in FIG. 10) 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. 10) 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. 10) as shown by the thick arrow in FIG. 10B. 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. 5), the current flows as follows. In the time T1 immediately before the switching element Q1 is turned on in FIG. 5, 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. 5, 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, 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. As described above, the recovery current flowing through the diode D3 at the timing when the switching element Q1 is turned on becomes a short-circuit current. Therefore, the short-circuit current can be prevented from flowing by performing the frequency adjustment process.

  In the power transmission device 130 in the non-contact power transmission / reception system 10 of the embodiment described above, 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 output impedance Zs of the inverter 142 is detected. And the coupling coefficient k is obtained based on the output impedance Zs. Then, 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 current phase θ is reduced. As a result, the advance angle of the current phase θ can be eliminated, and the recovery current can be prevented from flowing through the diode D3 at the timing when the switching element Q1 is turned on. Since the recovery current of the diode D3 at the timing when the switching element Q1 is turned on becomes a short-circuit current, by eliminating this, abnormal heat generation or failure of the power transmission device 130 due to the short-circuit current can be suppressed.

  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. 6, and 0.1 kHz may be used as the adjustment amount when “k = small” in FIG. 6.

  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 an “inverter”, the power receiving resonance circuit 32 corresponds to a “power receiving unit”, the power transmission resonance circuit 132 corresponds to a “power transmission unit”, and the power transmission ECU 170 It 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 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 G, 190 AC power supply, C capacitor, D1-D4, D91-D94 diode, Q1-Q4, Q91-Q94 switching element.

Claims (6)

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 AC power from the inverter to a power reception unit of the power reception device;
Control means for adjusting the AC power by switching control of a plurality of switching elements of the inverter;
With
The control means is configured such that the current phase of the output current from the inverter to the power transmission unit is advanced with respect to the output voltage when the phase reference is set to the positive side of the output voltage of the inverter. Ri means der to adjust repeatedly the AC power frequency in the direction in which the advance is reduced in the current phase until the advance is resolved with respect to the output voltage of the current phase when it detects,
Furthermore,
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 the output voltage, and an output impedance of the inverter is the power transmission unit. Calculating the coupling coefficient between the power receiving unit and the power transmitting unit as a function of the self inductance of the power receiving 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, and the calculated coupling A means for adjusting the frequency of the AC power in a direction in which the advance angle of the current phase decreases using a coefficient and the map;
Power transmission device. The power transmission device according to claim 1 ,
The control means is means for obtaining a frequency adjustment amount from the coupling coefficient and the map and adjusting the frequency of the AC power.
Power transmission device. The power transmission device according to claim 1 or 2 ,
The control means is means for calculating 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 of the power receiving device as constants.
Power transmission device. The power transmission device according to claim 3,
The control means is 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 of the power receiving device, Is a means for calculating the coupling coefficient by acquiring from the power receiving device,
Power transmission device. The power transmission device according to any one of claims 1 to 4 ,
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 any one of claims 1 to 4 ,
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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