JP6201388B2 - Contactless power supply system - Google Patents

Description

  The present invention relates to a non-contact power feeding system.

  2. Description of the Related Art Conventionally, as a power feeding system, a contactless power feeding system that supplies power in a contactless manner by magnetic coupling of a pair of coils is known. This non-contact power supply system is being applied to an electric vehicle such as an electric vehicle, for example. One coil connected to an AC power source is installed in a parking space such as a power supply stand, and the electric vehicle is connected to a battery. The other coil is installed. Then, by using the coil on the parking space side as the primary coil and the coil on the electric vehicle side as the secondary coil, the electric power is supplied from the parking space side AC power source to the vehicle side battery by the magnetic coupling of the pair of coils. Can be supplied. Here, on the primary coil side, an inverter that outputs an alternating current corresponding to the drive frequency to the primary coil is provided.

  For example, when the secondary coil is mounted on an electric vehicle, the positional relationship between the coils can change every time the vehicle is parked in order to charge the battery. Will change with this. Thus, for example, Patent Document 1 discloses a non-contact power feeding system that can quickly select an optimal driving frequency at the time of power supply and can reduce the time required for power supply.

  Specifically, the non-contact power feeding system includes an inverter that outputs AC power of a predetermined frequency, a power transmission coil that receives AC power from the inverter, and a frequency (drive frequency) of AC power that is output by the inverter. A power transmission control unit that controls and calculates the inverter efficiency of the inverter. Here, the power transmission control unit calculates the inverter efficiency while lowering the drive frequency from the upper limit frequency, and selects the drive frequency that gives the highest inverter efficiency to supply power.

JP 2013-17254 A

  By the way, in such a system, the condition of the electric power output to the battery via the coil also depends on the state of the battery. That is, the output power characteristic with respect to the drive frequency tends to vary depending on the degree of coupling of the coils, but in a system using a power storage unit such as a battery as a load, the output power characteristic also varies depending on the state of the power storage unit. Therefore, depending on the output power characteristics, the output power may be zero in a high frequency region, and the output power may rise only after reaching a certain small frequency.

  In this regard, according to the technique disclosed in Patent Document 1, the upper limit frequency is set as a fixed value. Therefore, the search for the optimal drive frequency starts with the upper limit frequency as the start of power supply, but depending on the output power characteristics, the period until the optimal drive frequency is selected may not only be long. A situation may occur in which a frequency in a region where the output power is zero is searched for over a long period of time. For this reason, there is an inconvenience that the period in which the output becomes zero at the start of power supply is long, and the initial responsiveness in power supply is reduced.

  This invention is made | formed in view of this situation, The objective is to provide the non-contact electric power feeding system which is excellent in the initial responsiveness at the time of starting electric power supply.

  In order to solve such a problem, the present invention outputs an alternating current corresponding to the drive frequency from the first power converter to the power transmission coil, and the power transmitted from the power transmission coil is received by the power reception coil by magnetic coupling. The second power converter converts the alternating current from the power receiving coil into a direct current, outputs the direct current, and stores the electric power in the power storage means. In this non-contact power supply system, the control unit supplies power by feedback controlling the drive frequency of the first power conversion unit based on the output voltage and output current to the power storage unit and the charge power command to the power storage unit. I do. Further, when starting the power supply, the control unit sets an initial frequency based on the state of the power storage means and the coil coupling coefficient, and starts feedback control using the initial frequency as an initial value of the drive frequency.

  According to the present invention, the initial frequency is appropriately determined based on the state of the power storage means and the coil coupling coefficient. As a result, it is possible to suppress a situation in which the drive frequency at which the output power becomes zero is continuously used for a long time after the feedback control is started. Thereby, the fall of the initial responsiveness in electric power supply can be suppressed.

The block diagram which shows typically the structure of the non-contact electric power feeding system which concerns on 1st Embodiment. Explanatory drawing which shows typically the circuit structure of the non-contact electric power feeding system which concerns on 1st Embodiment, and the structure of a control system. The block diagram which shows typically the inverter control part which concerns on 1st Embodiment Explanatory diagram showing frequency characteristics of output power The block diagram which shows typically the inverter control part which concerns on 2nd Embodiment The block diagram which shows typically the inverter control part which concerns on 3rd Embodiment.

(First embodiment)
FIG. 1 is a block diagram schematically showing a configuration of a non-contact power feeding system according to the present embodiment, and FIG. 2 is an explanatory diagram schematically showing a circuit configuration of the non-contact power feeding system and a configuration of a control system. . The non-contact power supply system includes a power supply device 100 that is a ground-side unit and an electric vehicle (hereinafter simply referred to as “vehicle”) 200 including a vehicle-side unit, and supplies power from the power supply device 100 in a non-contact manner. It is the electric power feeding system which charges the battery 28 provided in.

  The power supply apparatus 100 is installed in a charging stand or the like provided with a parking space for the vehicle 200 and supplies power to the vehicle 200. The power supply apparatus 100 is mainly configured by a power control unit 11, a power transmission coil 12, a wireless communication unit 14, and a control unit 15.

The power control unit 11 has a function for converting AC power transmitted from the AC power source 300 into high-frequency AC power and transmitting the power to the power transmission coil 12. The power control unit 11 includes a rectification unit 111, a PFC (Power Factor Correction) circuit 112, and an inverter 113.

  The rectifying unit 111 is electrically connected to the AC power source 300 and rectifies the output AC current from the AC power source. That is, the rectifying unit 111 converts an alternating current from the alternating current power supply 300 into a direct current and outputs the direct current.

  The PFC circuit 112 is connected between the rectifier 111 and the inverter 113. The PFC circuit 112 includes a boost chopper circuit, for example, and is a circuit for improving the power factor by shaping the waveform of the output current from the rectifying unit 111. The output of the PFC circuit 112 is smoothed by a smoothing capacitor.

  The inverter 113 is a power converter including a smoothing capacitor, a switching element such as an IGBT, and the like. A direct current from the rectifying unit 111 is input to the inverter 113, and an alternating current corresponding to the drive frequency is output to the power transmission coil 12. For example, the inverter 113 generates a PWM pulse from a DC voltage based on a drive signal output from the control unit 15 by PWM control, and thereby applies an equivalent sine wave AC voltage to the power transmission coil 12.

  The power transmission coil 12 is a coil for supplying power in a non-contact manner to the power reception coil 22 on the vehicle 200 side. The power transmission coil 12 is configured by connecting a coil and a resonance capacitor in series, but the connection between the coil and the resonance capacitor may be parallel or series-parallel. The power transmission coil 12 is provided at a target location such as a parking space where the vehicle 200 is parked, and faces the lower side of the power receiving coil 22 on the vehicle 200 side when the vehicle 200 is parked at a specified position in the parking space.

  The wireless communication unit 14 performs bidirectional communication with the wireless communication unit 24 provided on the vehicle 200 side. Since the communication frequency between the wireless communication unit 14 and the wireless communication unit 24 is set to a frequency higher than the frequency used in the vehicle peripheral device such as intelligence ski, the wireless communication unit 14 and the wireless communication unit 24 Even if it communicates between, vehicle peripheral devices are hard to receive the interference by the said communication. For communication between the wireless communication unit 14 and the wireless communication unit 24, for example, various wireless LAN methods are used, and communication methods suitable for long distances are used.

  The control unit 15 has a function of controlling the power supply apparatus 100. As the control unit 15, a microcomputer mainly composed of a CPU, a ROM, a RAM, and an I / O interface can be used. For example, the control unit 15 controls the power control unit 11, the power transmission coil 12, and the wireless communication unit 14. The control unit 15 transmits a control signal for starting power supply to the vehicle 200 side by communication between the wireless communication unit 14 and the wireless communication unit 24, or transmits a control signal for receiving power to the vehicle 200. Or from the side. The control unit 15 performs switching control of the inverter 113 and controls power output from the power transmission coil 12.

  The vehicle 200 includes a power receiving coil 22, a wireless communication unit 24, a charging control unit 25, a rectifying unit 26, a relay unit 27, a battery 28, an inverter 29, a motor 30, and a notification unit 32. Yes.

  The power receiving coil 22 is a coil for receiving power in a non-contact manner from the power transmitting coil 12 on the power supply apparatus 100 side. The power receiving coil 22 is configured by connecting a coil and a resonance capacitor in series, but the connection between the coil and the resonance capacitor may be parallel or series-parallel. The power receiving coil 22 is provided at a target location, for example, between the rear wheels on the bottom surface (chassis) or the like of the vehicle 200, and when the vehicle 200 is parked at a specified position in the parking space, It faces the upper side of the power transmission coil 12.

  The wireless communication unit 24 performs bidirectional communication with the wireless communication unit 14 provided on the power supply apparatus 100 side.

The rectifier 26 is a power converter that is connected to the power receiving coil 22 and converts an alternating current from the power receiving coil 22 into a direct current and outputs the direct current. For example, the rectifier 26 converts the output from the power receiving coil 22 into a direct current through a rectification process by a rectifier circuit and a filter process by a filter circuit.

  The relay unit 27 includes a relay switch that is turned on and off under the control of the charging control unit 25. The relay unit 27 can disconnect the circuit including the battery 28 and the circuit including the power receiving coil 22 and the rectifying unit 26 by turning off the relay switch.

  The battery 28 is a power source of the vehicle 200, and is a power storage unit that is configured by electrically connecting a plurality of secondary batteries, for example, and stores output power from the rectifying unit 26.

  The inverter 29 is a power conversion device including a switching element such as an IGBT, a PWM control circuit, and the like, converts a direct current output from the battery 28 into an alternating current based on the control signal, and converts the alternating current to the motor 30. Supply. The motor 30 is composed of, for example, a three-phase AC motor, and is a drive source for driving the vehicle 200.

  The notification unit 32 includes a warning lamp, a display of a navigation system, a speaker, and the like, and is arranged on an instrument panel or the like in the vehicle interior. The notification unit 32 outputs light, an image, sound, or the like to the user based on the control by the charging control unit 25.

  The charging control unit 25 has a function of controlling charging of the battery 28. As the charging control unit 25, a microcomputer mainly composed of a CPU, a ROM, a RAM, and an I / O interface can be used. For example, the charging control unit 25 receives a control signal for starting power supply from the power supply apparatus 100 side or supplies a control signal for receiving power through communication between the wireless communication unit 24 and the wireless communication unit 14. Or transmitted to the device 100 side.

  Although not shown, the charging control unit 25 is connected to a controller that controls the entire vehicle 200 via a CAN communication network. The controller manages the switching control of the inverter 29 and the state of charge (SOC) of the battery 28. The charging control unit 25 can acquire a charging power command that is a power command for charging the battery 28 from the controller.

  In the non-contact power feeding system according to the present embodiment, power is transmitted between the power transmission coil 12 and the power receiving coil 22 in a non-contact state by electromagnetic induction. That is, when a voltage is applied to the power transmission coil 12 that is the primary coil, magnetic coupling occurs between the power transmission coil 12 and the power reception coil 22 that is the secondary coil, and power is supplied from the power transmission coil 12 to the power reception coil 22. The

  Hereinafter, a specific power feeding control method by the non-contact power feeding system will be described. As illustrated in FIG. 2, the control unit 15 of the power supply apparatus 100 that is a ground-side unit controls the power control unit 11 based on information output from the charging control unit 25 on the vehicle 200 side.

  Specifically, the charging control unit 25 detects the output voltage and output current output from the rectifying unit 26 to the battery 28 through the voltage sensor 261 and the current sensor 262. Further, the charging control unit 25 acquires a charging power command output from a controller (not shown) of the vehicle 200 according to the charging state of the battery 28. Then, the charging control unit 25 converts the charging power command, the output voltage to the battery 28 and the output current into data for wireless communication. When the converted data is transmitted by the wireless communication unit 24 on the vehicle 200 side, the converted data is received by the wireless communication unit 14 on the power supply device 100 side and output to the control unit 15 on the power supply device 100 side.

  The control unit 15 on the power supply apparatus 100 side includes a PFC control unit 151 and an inverter control unit 152 when this is viewed functionally.

  The PFC controller 151 receives the input voltage of the PFC circuit 112 detected by the voltage sensor 114, the input current of the PFC circuit 112 detected by the current sensor 115, and the input voltage of the inverter 113 detected by the voltage sensor 116. Have been entered. Based on such information, the PFC control unit 151 controls the input current of the PFC circuit 112 and the input voltage of the inverter 113 by operating the boost chopper circuit.

  For example, the PFC control unit 151 obtains the input current amplitude target value of the input current of the PFC circuit 112 from the target value of the input voltage of the inverter 113 and the actual input voltage. The PFC control unit 151 calculates a target value waveform of the input current of the PFC circuit 112 using the input current amplitude target value and the detected input voltage of the PFC circuit 112. Then, the PFC control unit 151 compares this target value waveform with the input current of the PFC circuit 112, and operates the duty of the boost chopper so that the input current of the PFC circuit 112 becomes equal to the target value waveform.

  The inverter controller 152 receives the input voltage of the inverter 113 detected by the voltage sensor 116, the charging power command acquired from the vehicle 200 side, and the output voltage / output current to the battery 28. Based on these pieces of information, the inverter control unit 152 performs feedback control of the inverter 113 to supply power. When the inverter control unit 152 obtains the drive frequency of the inverter 113 by feedback calculation, the inverter control unit 152 generates a drive signal for the inverter 113 based on this drive frequency and its duty command value. Here, the duty is defined as the ratio of the positive voltage output time in the output voltage waveform of the inverter 113 to the PWM cycle of one positive / negative cycle.

  FIG. 3 is a block diagram schematically showing the configuration of the inverter control unit 152 according to the present embodiment. The inverter control unit 152 includes an input average voltage calculation unit 152a, an initial frequency calculation unit 152b, a power feedback control calculation unit 152c, a duty calculation unit 152d, a carrier comparison value conversion unit 152e, and a PWM carrier comparison unit 152f. Have.

The input average voltage calculation unit 152a receives the input voltage of the inverter 113. The input average voltage calculation unit 152a calculates an average voltage of input voltages (hereinafter referred to as “input average voltage”) V _PFC0 . For example, the input average voltage calculation unit 152a calculates the input average voltage V _PFC0 using a moving average filter or a low-pass filter. When the input voltage of the inverter 113 can sufficiently follow the target value and control can be performed, the input of the inverter 113 in the PFC control unit 151 is provided instead of providing the input average voltage calculation unit 152a. A target voltage value can also be used.

The initial frequency calculation unit 152 b, and the input average voltage _{V PFC0} from the average input voltage calculation unit 152a, and the output voltage _{V 0} which the battery 28 is input. The initial frequency calculation unit 152b may store the output voltage V0 when the charging electric power command zero, with the stored output voltage V _0, and the input average voltage V _PFC0, on the basis of the coil coupling coefficient k The initial frequency f _{PWM_FF} is calculated by the following equation.

Here, the coil coupling coefficient k takes a value between 0 and 1, and changes depending on the positional relationship between the power transmission coil 12 and the power reception coil 22. In the present embodiment, the initial frequency calculation unit 152b stores in advance the maximum value of the coil coupling coefficient k in the usage state of the power transmission coil 12 and the power reception coil 22, and stores the maximum value in the calculation of the initial frequency f _{PWM_FF} . Use the maximum value.

L ₀ is the self-inductance of the coil, and C is the capacitance of the resonant capacitor. For these values L ₀ and C, values at the time of design are set.

When the initial frequency calculation unit 152b performs the calculation shown in Formula 1 and specifies the frequency, the initial frequency f _{PWM_FF} is set by adding a preset compensation frequency to this value. The compensation frequency is a positive value set in advance, and can compensate for fluctuations in the self-inductance L ₀ and the capacitance C.

The power feedback control calculation unit 152c is input with the charging power command and the output power output from the rectifying unit 26 to the battery 28, which is obtained by integrating the output voltage and the output voltage to the battery 28. As the power feedback control calculation unit 152c, a PI controller can be used. The power feedback control calculation unit 152c compares the charging power command with the output power, and calculates the feedback drive frequency _{fPWM_FB} so that the output power follows the charging power command. For example, when the control deviation obtained by subtracting the output power from the charge power command is positive, the power feedback control calculation unit 152c outputs the feedback drive frequency f _{PWM_FB} that is a negative value so as to decrease the drive frequency f _PWM. To do.

The initial frequency f _{PWM_FF} calculated by the initial frequency calculation unit 152b and the feedback drive frequency f _{PWM_FB} calculated by the power feedback control calculation unit 152 are added by an adder, thereby specifying the final drive frequency f _PWM. Is done. The driving frequency _{f PWM} is output to the carrier comparison value converting unit 152e and the PWM carrier comparison section 152f to be described later. In this way, the initial frequency f _{PWM_FF} is added to the feedback drive frequency f _{PWM_FB} to obtain the final drive frequency f _PWM , so that the initial frequency initial frequency f _{PWM_FF} is driven when power supply is started. Feedback control is started using the initial value of the frequency f _PWM .

The duty calculation unit 152d outputs the duty command value D _cmp to the carrier comparison value conversion unit 152e. For example, the duty command value is set in the duty calculation unit 152d so that the positive and negative output times of the inverter output voltage are equal.

The carrier comparison value conversion unit 152e sets the frequency of the PWM carrier at the drive frequency F _PWM and standardizes the duty command D _cmp to generate a PWM pulse by carrier comparison, thereby comparing the value with the PWM carrier (comparison). Value).

  The PWM carrier comparison unit 152f compares the comparison value with the PWM carrier, and generates a drive signal for controlling on / off of each switching element forming the inverter 113.

Thus, in this embodiment, the non-contact power feeding system includes a power transmission coil 12 that transmits power, and an inverter (first power conversion unit) that receives a direct current and outputs an alternating current corresponding to a drive frequency to the power transmission coil 12. ) 113, a power receiving coil 22 that receives power transmitted from the power transmitting coil 12 by magnetic coupling, and a rectifier 26 (second power converter) that converts an alternating current from the power receiving coil 22 into a direct current and outputs the direct current. And feedback control of the drive frequency of the inverter 113 based on the battery 28 that charges the power output from the rectifier 26, the output voltage and output current of the rectifier 26, and the charge power command to the battery 28. And a control unit 15 that supplies power. Here, when starting the power supply, the control unit 15 sets the initial frequency f _{PWM_FF} based on the state of the battery 28 and the coil coupling coefficient indicating the degree of coupling between the power transmission coil 12 and the power reception coil 22, and Feedback control is started using the initial frequency f _{PWM_FF} as the initial value of the drive frequency f _PWM .

  As shown in FIG. 4, the output power characteristic to the battery 28 with respect to the driving frequency tends to vary depending on the coupling degree of the coil, but in a system using the battery 28 as a load, the characteristic varies depending on the output voltage to the battery 28. Will be shown. The figure shows the output power characteristics to the battery 28 with respect to frequency for relatively different output voltages. In the figure, the output voltage is in a high state in the order of (a), (b), and (c). As shown in the figure, depending on the output power characteristics, it can be seen that the output power becomes zero in the high frequency region, and the output power rises only after reaching a certain small frequency. Also, the width of the zero interval varies.

  In such a situation, when the upper limit frequency is set as a fixed value, depending on the output power characteristics, the frequency may not only extend for a long period of time until the optimum drive frequency is selected, but also the output power becomes zero. The situation of searching for a long term can occur. For this reason, there is an inconvenience that the period in which the output becomes zero at the start of power supply is long, and the initial responsiveness in power supply is reduced.

In this regard, according to the present embodiment, the initial frequency f _{PWM_FF} is variably set based on the state of the battery 28 and the coil coupling coefficient k. Since the drive frequency (output start frequency) at which the output power becomes zero or more depends on the state of the battery 28 and the coil coupling state, feedback control regarding the drive frequency _fPWM is performed by considering these relationships. The initial value that is the starting point in the above can be determined appropriately. Thereby, after starting feedback control, it is possible to suppress a situation in which a frequency at which output power becomes zero is used for a long period of time. Thereby, the fall of the initial responsiveness in electric power supply can be suppressed.

More specifically, in this embodiment, the output voltage V ₀ to the battery 28 is used as the state of the battery 28. In this case, as shown in Formula 1, the control unit 15 variably determines the initial frequency f _{PWM_FF} based on the output voltage V ₀ to the battery 28 and the coil coupling coefficient k. The frequency at which the output power becomes zero or more (output start frequency) increases as the output voltage decreases, and conversely decreases as the output voltage increases. The output start frequency is higher as the coupling coefficient of the coil is higher, and lower as the coupling coefficient is lower. The arithmetic expression shown in the above formula 1 incorporates such a tendency into the arithmetic expression, and determines the initial frequency f _{PWM_FF} so as to approach the rising frequency of the output power based on the resonance frequency. is there. This makes it possible to appropriately determine an initial value serving as a starting point for performing feedback control regarding the drive frequency _fPWM .

Further, as shown in Formula 1, in the present embodiment in which the input voltage V _PFC0 of the inverter 113 can fluctuate, in addition to the output voltage V ₀ to the battery 28 and the coil coupling coefficient k, the input voltage V _PFC0 of the inverter 113 is further _changed to Based on this, the initial frequency f _{PWM_FF} is variably set. This makes it possible to appropriately determine an initial value serving as a starting point for performing feedback control regarding the drive frequency _fPWM . Thereby, after starting feedback control, it is possible to suppress a situation in which a frequency at which output power becomes zero is used for a long period of time. Thereby, the fall of the initial responsiveness in electric power supply can be suppressed.

The condition that the output power to the battery 28 becomes zero or more, that is, the condition that the current flows to the battery 28 depends largely on the magnitude relationship of the voltage. As shown, the initial frequency f _{PWM_FF} can be easily obtained. However, it goes without saying that other parameters may be used as parameters for detecting the state of the battery 28 as long as the control concept described above can be realized, in addition to using the output voltage V ₀ to the battery 28.

Moreover, in this embodiment, the control part 15 has memorize | stored beforehand the maximum value of the coil coupling coefficient k in consideration of the use condition of the power transmission coil 12 and the power receiving coil 22, and uses the said stored maximum value and is the initial frequency. f _Calculation of _{PWM_FF} is performed.

According to such a configuration, the initial frequency f _{PWM_FF} can be appropriately determined within a practical range by using the maximum value that can be taken as the coil coupling coefficient k.

In the present embodiment, the control unit 15 calculates the initial frequency f _{PWM_FF} using the output voltage V ₀ to the battery 28 when the charge power command is zero.

As a result, the initial frequency f _{PWM_FF} used at the start of power supply can be appropriately determined.

The control unit 15 updates the output voltage V ₀ periodically acquired by the while performing the power supply may be performed calculation of the initial frequency f _{PWM_FF} using the output voltage V ₀ which is the update .

According to such a configuration, even when the charge power command is once lowered to near zero (when it is not completely zero) _{during charging} , the initial frequency f _{PWM_FF} is quickly determined by using the updated output voltage V _0. Can be supplied with power.

(Second Embodiment)
FIG. 5 is a block diagram schematically illustrating the inverter control unit 152 according to the second embodiment. The difference between the inverter control unit 152 according to the second embodiment and that of the first embodiment is that the coil coupling coefficient k is estimated. Note that the description of the same components as those in the first embodiment will be omitted, and the following description will focus on the differences.

  The inverter control unit 152 according to the present embodiment has the configuration shown in the first embodiment, that is, an input average voltage calculation unit 152a, an initial frequency calculation unit 152b, a power feedback control calculation unit 152c, a duty calculation unit 152d, a carrier comparison value. In addition to the conversion unit 152e and the PWM carrier comparison unit 152f, a coupling coefficient estimation calculation unit 152g is further included.

  The coupling coefficient estimation calculation unit 152g estimates the coil coupling coefficient k. The coil coupling coefficient k has a correlation with the positional deviation between the power transmission coil 12 and the power receiving coil 22, and the coupling coefficient estimation calculation unit 152g estimates the coil coupling coefficient k based on the positional deviation of the coil. The positional deviation of the coil can be recognized by a method of recognizing the position of the power receiving coil 22 by using, for example, image processing. The coupling coefficient estimation calculation unit 152g acquires a calculation map or the like that defines the relationship between the coil position deviation and the coil coupling coefficient k in advance through experiments and simulations, and holds the calculation map so that the power receiving coil 22 The coil coupling coefficient k can be estimated based on the displacement.

  Further, the coupling coefficient estimation calculation unit 152g may obtain the coil coupling coefficient k by performing a trial power feeding operation in a state where the battery 28 is disconnected by the relay unit 27. In this power feeding operation, when the degree of coupling of the coil is strong, the output voltage of the rectifying unit 26 is high. On the other hand, when the degree of coupling of the coil is weak, the output voltage of the rectifying unit 26 is low. Therefore, the coupling coefficient estimation calculation unit 152g obtains a calculation map or the like that defines the relationship between the output voltage of the rectification unit 26 and the coil coupling coefficient k in advance through experiments and simulations, and holds this. The coil coupling coefficient k can be estimated based on the output voltage of the rectifying unit 26.

The coil coupling coefficient k estimated by the coupling coefficient estimation calculation unit 152g is output to the initial frequency calculation unit 152b. In this case, the initial frequency calculation unit 152b uses the coil coupling coefficient k estimated by the coupling coefficient estimation calculation unit 152g in the calculation of the initial frequency f _{PWM_FF} .

As described above, according to the present embodiment, the coil coupling coefficient k can be reflected in an actual state, so that the calculation accuracy of the initial frequency f _{PWM_FF} can be improved. Thereby, the non-contact electric power feeding system which is excellent in the initial response at the time of starting electric power supply can be provided.

(Third embodiment)
FIG. 6 is a block diagram schematically illustrating the inverter control unit 152 according to the third embodiment. The difference between the inverter control unit 152 according to the third embodiment and that of the second embodiment is that the coil coupling coefficient k is estimated. In addition, suppose that it abbreviate | omits description about the structure which overlaps with 2nd Embodiment, and demonstrates below centering on difference.

In the present embodiment, temperature information detected by a temperature sensor (not shown) that detects the ambient temperature of the power transmission coil 12 is input to the initial frequency calculator 152b. Initial frequency calculation unit 152b, the resonance frequency, i.e., in order to compensate for the temperature characteristics of the self-inductance L ₀ and the capacitance C, and corrects the compensation frequency based on the input temperature information.

According to this configuration, it is possible to compensate for the resonance frequency specification due to temperature, and therefore it is possible to improve the calculation accuracy of the initial frequency f _{PWM_FF} . Thereby, the non-contact electric power feeding system which is excellent in the initial response at the time of starting electric power supply can be provided.

  Note that the method for correcting the compensation frequency by temperature shown in the present embodiment may be applied to the method shown in the first embodiment.

  The contactless charging system of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications are possible within the scope of the invention. The unit on the power receiving coil side of the non-contact power feeding system is mounted on an electric vehicle, but may be a vehicle including a battery such as a hybrid vehicle. Further, the vehicle may include not only the unit on the power receiving coil side but also the power feeding device alone or in combination.

DESCRIPTION OF SYMBOLS 100 Power feeder 11 Power control part 111 Rectification part 112 PFC circuit 113 Inverter 114 Voltage sensor 115 Current sensor 12 Power transmission coil 14 Wireless communication part 15 Control part 151 PFC control part 152 Inverter control part 152a Input average voltage calculation part 152b Initial frequency calculation part 152c Power feedback control calculation unit 152d Duty calculation unit 152e Carrier comparison value conversion unit 152f PWM carrier comparison unit 152g Coupling coefficient estimation calculation unit 200 Vehicle 22 Power receiving coil 24 Wireless communication unit 25 Charging control unit 26 Rectification unit 27 Relay unit 28 Battery

Claims (8)

A power transmission coil for transmitting power;
A first power converter that receives a direct current and outputs an alternating current corresponding to a drive frequency to the power transmission coil;
A power receiving coil that receives power transmitted from the power transmitting coil by magnetic coupling;
A second power converter that converts alternating current from the power receiving coil into direct current and outputs the direct current;
Power storage means for storing power output from the second power converter;
A control unit that performs power supply by feedback-controlling the drive frequency of the first power conversion unit based on an output voltage and output current to the power storage unit and a charge power command to the power storage unit; ,
When starting the power supply, the control unit sets an initial frequency based on a state of the power storage unit and a coil coupling coefficient indicating a degree of coupling between the power transmission coil and the power reception coil of the power storage unit, The contactless power feeding system, wherein the feedback control is started using an initial frequency as an initial value of the driving frequency. The state of the power storage means is an output voltage to the power storage means,
2. The control unit according to claim 1, wherein the control unit sets an initial frequency based on an input voltage of the first power conversion unit in addition to an output voltage to the power storage unit and the coil coupling coefficient. Contactless power supply system.   The control unit stores in advance a maximum value of the coil coupling coefficient in consideration of usage conditions of the power transmission coil and the power reception coil, and performs the calculation of the initial frequency using the stored maximum value. The non-contact electric power feeding system according to claim 1 or 2 characterized by things. An estimation unit for estimating the coil coupling coefficient;
The contactless power supply system according to claim 1, wherein the control unit calculates the initial frequency using the coil coupling coefficient estimated by the estimation unit.   5. The non-contact according to claim 1, wherein the control unit calculates the initial frequency using an output voltage to the power storage unit when the charge power command is zero. Power supply system.   6. The control unit according to claim 5, wherein the control unit periodically acquires and updates the output voltage during power supply, and calculates the initial frequency using the updated output voltage. The described contactless power supply system. The control unit sets the initial frequency by adding a preset compensation frequency to a frequency calculated based on the output voltage, the input voltage, and the coil coupling coefficient. Item 3. A contactless power supply system according to item 2 .

  The contactless power supply system according to claim 7, wherein the control unit corrects the compensation frequency according to an ambient temperature of the power transmission coil.