WO2014045873A1 - Power receiving device and contactless power transmitting equipment - Google Patents

Abstract

A power receiving device (21) is provided with: a secondary coil (23a) that is capable of receiving AC power in a contactless manner from a power transmitting device (11) having a primary coil (13a) to which AC power is inputted; a rectifier (24) that rectifies the AC power received by the secondary coil (23a); and a load (22) to which DC power rectified by the rectifier (24) is inputted. The power receiving device (21) is provided with adjustment unit (2) disposed between the rectifier (24) and the load (22). The adjustment unit (25) adjusts impedance from an output terminal of the rectifier (24) to the load (22) in such a manner that the efficiency of the rectifier (24) increases.

Description

Power receiving device and contactless power transmission device

The present disclosure relates to a power receiving device and a contactless power transmission device.

2. Description of the Related Art Conventionally, as a non-contact power transmission device that does not use a power cord or a power transmission cable, for example, one using magnetic field resonance is known. For example, the non-contact power transmission device of JP 2009-106136 A includes a power transmission device having an AC power supply and a primary side resonance coil to which AC power is input from the AC power supply. The non-contact power transmission device of the document includes a power receiving device having a secondary side resonant coil capable of magnetic field resonance in the primary side resonant coil. As the primary side resonant coil and the secondary side resonant coil perform magnetic field resonance, alternating current power is transmitted from the power transmission device to the power reception device. The AC power transmitted to the power receiving device is rectified to DC power by a rectifier provided in the power receiving device, and is input to the vehicle battery. Thus, the vehicle battery is charged.

JP, 2009-106136, A

In the non-contact power transmission device as described above, improvement of transmission efficiency is required. A parameter on which this transmission efficiency depends is, for example, the efficiency of the rectifier. And, in the non-contact power transmission device, there is still room for improvement in the efficiency of the rectifier.

The above-mentioned circumstances are not limited to the case of performing non-contact power transmission by magnetic field resonance, and the same applies to the case of non-contact power transmission by electromagnetic induction.

An object of the present disclosure is to provide a power receiving device capable of improving the efficiency of a rectifying unit and a contactless power transmission device including the power receiving device.
According to one aspect of the present disclosure, the power receiving device includes a secondary coil capable of receiving the AC power without contact from a power transmitting device having a primary coil to which AC power is input; and the secondary coil A rectifying unit configured to rectify received AC power; and a load to which the DC power rectified by the rectifying unit is input. The power receiving device further includes an adjustment unit provided between the rectification unit and the load, and the adjustment unit is connected from the output end of the rectification unit to the load so that the efficiency of the rectification unit is high. Configured to adjust the impedance.

According to this aspect, the adjustment unit adjusts the impedance from the output end of the rectification unit to the load such that the efficiency of the rectification unit is increased. Thereby, the efficiency of the rectifying unit can be improved.

In one aspect, the adjustment unit is configured to increase the impedance from the output end of the rectification unit to the load in a state where a voltage value applied to an element constituting the rectification unit is smaller than a withstand voltage value. Be done. According to this aspect, the impedance from the output end of the rectifying unit to the load is large in a state where the voltage value applied to the element constituting the rectifying unit is smaller than the withstand voltage value. As a result, the current value of the current flowing through the rectifying unit becomes smaller and the power consumed by the rectifying unit becomes smaller, within the range in which an excessive voltage is not applied to the elements constituting the rectifying unit. Therefore, it is possible to improve the efficiency of the rectifying unit while suppressing the malfunction of the elements constituting the rectifying unit.

In one aspect, the load is configured to vary in impedance, and the adjustment unit is configured to increase the efficiency of the rectification unit in response to the variation in impedance of the load from the output end of the rectification unit. It is configured to adjust the impedance to the load. According to this aspect, according to the fluctuation of the impedance of the load, the impedance from the output end of the rectifying unit to the load is adjusted so that the efficiency of the rectifier becomes high, whereby the rectifying unit accompanying the fluctuation of the impedance of the load It is possible to suppress the decrease in the efficiency of

In one aspect, a power transmission device having a primary coil to which alternating current power is input, a secondary coil capable of receiving the alternating current power without contact from the primary coil, and power reception by the secondary coil A contactless power transfer apparatus comprising: a rectifying unit configured to rectify AC power; and a power receiving device having a load to which the DC power rectified by the rectifying unit is input. According to this aspect, in the non-contact power transmission device, the efficiency of the rectifying unit can be improved.

Other features and advantages of the present disclosure will be apparent from the following detailed description and the accompanying drawings to explain the features of the present disclosure.

The features of the present disclosure which are believed to be novel are, in particular, apparent from the appended claims. The present disclosure, together with objects and advantages, will be understood by reference to the following description of the presently preferred embodiments, taken in conjunction with the accompanying drawings.
FIG. 1 shows a circuit diagram showing the electrical configuration of the contactless power transmission device.

Hereinafter, a contactless power transmission device (contactless power transmission system) according to the present disclosure will be described.
As shown in FIG. 1, the non-contact power transmission device 10 includes a ground-side device 11 provided on the ground and a vehicle-side device 21 mounted on a vehicle. The ground-side device 11 corresponds to a power transmission device (primary device), and the vehicle-side device 21 corresponds to a power reception device (secondary device).

The ground-side device 11 includes a high frequency power supply 12 (AC power supply) capable of outputting high frequency power (AC power) of a predetermined frequency. The high frequency power source 12 is configured to convert system power input from a system power source as an infrastructure into high frequency power and output the high frequency power.

The high frequency power output from the high frequency power source 12 is transmitted to the vehicle-side device 21 in a noncontact manner, and used to charge the vehicle battery 22 as a load provided to the vehicle-side device 21. Specifically, the non-contact power transmission device 10 performs the power transmission between the ground-side device 11 and the vehicle-side device 21. The power transmitter 13 provided in the ground-side device 11 and the vehicle-side device 21 And a power receiver 23 provided on the

The power transmitter 13 and the power receiver 23 have the same configuration and are configured to be capable of magnetic field resonance. Specifically, the power transmitter 13 is configured by a resonant circuit including a primary coil 13a and a primary capacitor 13b connected in parallel. The power receiver 23 is configured of a resonant circuit including a secondary coil 23a and a secondary capacitor 23b connected in parallel. The resonant frequencies of the power transmitter 13 and the power receiver 23 are set to be the same.

According to this configuration, when high frequency power is input to the power transmitter 13 (primary coil 13a), the power transmitter 13 and the power receiver 23 (secondary coil 23a) resonate in a magnetic field. Thus, the power receiver 23 receives part of the energy of the power transmitter 13. That is, the power receiver 23 receives high frequency power from the power transmitter 13.

The vehicle-side device 21 is provided with a rectifier 24. The rectifier 24 as a rectifying unit rectifies the high frequency power received by the power receiver 23. The vehicle-side device 21 is provided with a DC / DC converter 25. The DC / DC converter 25 as an adjustment unit converts the voltage value of the DC power rectified by the rectifier 24 into a different voltage value and outputs the voltage value to the vehicle battery 22. The DC power output from the DC / DC converter 25 is input to the vehicle battery 22 to charge the vehicle battery 22.

Incidentally, the vehicle battery 22 is configured by, for example, connecting a plurality of battery cells. The impedance ZL of the vehicle battery 22 fluctuates according to the power value and the charge amount of the input DC power. That is, the vehicle battery 22 is a fluctuating load in which the impedance ZL fluctuates according to the situation.

The ground-side device 11 is provided with a power-supply-side controller 14 that performs various controls of the ground-side device 11. The power supply side controller 14 includes a power control unit 14 a. The power control unit 14 a determines whether to output high frequency power from the high frequency power supply 12 and performs power value control of the high frequency power output from the high frequency power supply 12. The power control unit 14a is configured to be able to switch the high frequency power output from the high frequency power supply 12 between the charging power and the pushing charging power having a power value different from the power value of the charging power. . The push-in charging power is high-frequency power set so that DC power of a power value suitable for push-in charging is input to the vehicle battery 22. Push-in charging is a charging mode performed to compensate for capacity variations of the battery cells that make up the vehicle battery 22.

The vehicle-side device 21 is provided with a vehicle-side controller 26 configured to be able to wirelessly communicate with the power supply-side controller 14. The non-contact power transmission device 10 starts and ends power transmission and the like through the exchange of information between the power supply side controller 14 and the vehicle side controller 26.

The vehicle-side device 21 is provided with a detection sensor 27. The detection sensor 27 detects the charge amount of the vehicle battery 22. The detection sensor 27 transmits the detection result to the vehicle controller 26. Thereby, the vehicle controller 26 can grasp the charge amount of the vehicle battery 22.

When the detection sensor 27 detects that the charge amount of the vehicle battery 22 has reached a predetermined threshold amount, the vehicle controller 26 sends a notification to that effect to the power controller 14. The power control unit 14a of the power supply side controller 14 switches the output power of the high frequency power supply 12 from the charging power to the charging power based on the reception of the notification. In other words, it can be said that push-in charge is a charge mode performed when the charge amount of the vehicle battery 22 becomes a threshold amount.

The measuring device 28 is provided between the rectifier 24 of the vehicle-side device 21 and the DC / DC converter 25. The measuring device 28 measures a load impedance Z1 which is an impedance from the output end of the rectifier 24 to the vehicle battery 22, and outputs the measurement result to the vehicle controller 26.

The non-contact power transmission device 10 includes a primary impedance converter 31 provided in the ground device 11 and a secondary impedance converter 32 provided in the vehicle device 21. The primary side impedance converter 31 is provided between the high frequency power supply 12 and the power transmitter 13. The primary side impedance converter 31 is configured by, for example, an LC circuit, and is configured such that the constants (inductance and capacitance) of the LC circuit are fixed. The secondary side impedance converter 32 is provided between the power receiver 23 and the rectifier 24. The secondary side impedance converter 32 is configured by, for example, an LC circuit, and is configured such that constants (inductance and capacitance) of the LC circuit are fixed. The constant can be said to be an impedance or a conversion ratio.

Next, the circuit configuration of the rectifier 24 and the DC / DC converter 25 will be described.
The rectifier 24 is configured to receive the high frequency power received by the power receiver 23. The rectifier 24 rectifies the input high frequency power and outputs the rectified power. Specifically, the rectifier 24 includes a diode bridge 41 that full-wave rectifies high-frequency power, and a smoothing circuit 42 that smoothes the full-wave rectified high-frequency power (pulsating current power). The diode bridge 41 reverses a plurality of (two) positive side diodes 41 a used to transmit the positive component of the high frequency power to the smoothing circuit 42 and a negative component of the high frequency power and transmits the inverted component to the smoothing circuit 42. And a plurality of (two) negative side diodes 41 b to be used.

The smoothing circuit 42 includes a choke coil 42 a and two smoothing capacitors 42 b and 42 c. The choke coil 42 a is connected in series to the diode bridge 41. Specifically, the first end of the choke coil 42 a is connected to the output end of the diode bridge 41, and the second end of the choke coil 42 a is connected to the output end of the rectifier 24. The smoothing capacitors 42b and 42c are connected in parallel to the choke coil 42a. Specifically, the first ends of the smoothing capacitors 42b and 42c are connected to the choke coil 42a, respectively, and the second ends thereof are grounded. According to this configuration, when the smoothing circuit 42 smoothes the pulsating current power which is the output power from the diode bridge 41, the pulsating current power is rectified to the direct current power.

The DC / DC converter 25 is a so-called non-insulated step-down chopper. The DC / DC converter 25 includes a switching element 51, a diode 52, a coil 53 connected in series to the switching element 51, and a capacitor 54 connected in parallel to the coil 53.

The switching element 51 is configured of, for example, an n-type power MOSFET. The drain of the switching element 51 is connected to the output end of the rectifier 24 via the input end of the DC / DC converter 25 and the measuring unit 28. The source of the switching element 51 is connected to the first end of the coil 53 and to the cathode of the diode 52. The anode of the diode 52 is grounded. The second end of the coil 53 is connected to the vehicle battery 22 via the output end of the DC / DC converter 25. The first end of the capacitor 54 is connected to the second end of the coil 53, and the second end of the capacitor 54 is grounded.

According to this configuration, when the switching element 51 switches periodically (on / off, chopping), voltage value conversion corresponding to the on / off duty ratio of the switching element 51 is performed. In this case, the load impedance Z1 depends on the on / off duty ratio of the switching element 51. That is, the duty ratio defines the load impedance Z1.

The relationship between the duty ratio and the load impedance Z1 is described in detail below. The voltage value on the output side of the DC / DC converter 25 is the battery voltage value of the vehicle battery 22, and the battery voltage value is uniquely determined by the specifications of the vehicle battery 22. On the other hand, as a result of both the voltage value and the current value of DC power input to DC / DC converter 25 fluctuating according to the duty ratio, load impedance Z1, which is the ratio of the voltage value to the current value, fluctuates. Thus, the duty ratio defines the load impedance Z1.

The vehicle controller 26 includes a duty ratio adjusting unit 26 a that adjusts (controls) the on / off duty ratio of the switching element 51. The duty ratio adjustment unit 26 a adjusts the duty ratio by controlling the gate voltage of the switching element 51. In detail, the duty ratio adjustment unit 26a outputs a pulse signal having a frequency higher than that of the high frequency power to the gate of the switching element 51, and adjusts the duty ratio by performing pulse width modulation of the pulse signal. . If attention is paid to the fact that the load impedance Z1 fluctuates according to the duty ratio, it can be said that the duty ratio adjusting unit 26a adjusts the load impedance Z1 by adjusting the duty ratio.

The duty ratio adjustment unit 26a adjusts the duty ratio so that the efficiency of the rectifier 24 becomes high, taking into consideration the withstand voltage values of the elements (for example, the diodes 41a and 41b and the smoothing capacitors 42b and 42c) that constitute the rectifier 24. Do. Specifically, the efficiency of the rectifier 24 becomes higher as the value of the current flowing through the rectifier 24 (the positive side diode 41 a or the negative side diode 41 b or the like) becomes smaller. The current value of the current flowing through the rectifier 24 decreases as the load impedance Z1 increases. However, if the load impedance Z1 is excessively increased, the voltage value applied to each element constituting the rectifier 24 may become equal to or higher than the withstand voltage value.

On the other hand, the duty ratio adjustment unit 26a sets the duty ratio so that the load impedance Z1 becomes large in the state (within the range) where the voltage value applied to each element constituting the rectifier 24 is smaller than the withstand voltage value. adjust.

The duty ratio adjustment unit 26a adjusts the duty ratio in accordance with the fluctuation of the impedance ZL of the vehicle battery 22. In detail, when the high frequency power output from the high frequency power supply 12 is switched from the charging power to the charging power, the duty ratio adjusting unit 26a configures each of the rectifiers 24 based on the measurement result of the measuring device 28. The duty ratio is adjusted so that the load impedance Z1 becomes as large as possible in a state where the voltage value applied to the element is smaller than the withstand voltage value.

Here, the load impedance Z1 set as large as possible in a state where the voltage value applied to each element constituting the rectifier 24 is smaller than the withstand voltage value is referred to as the maximum load impedance. The maximum load impedance may fluctuate depending on the power value of the high frequency power output from the high frequency power supply 12.

The duty ratio adjustment unit 26a adjusts the duty ratio based on the measurement result of the measuring device 28 such that the load impedance Z1 approaches, preferably matches, the maximum load impedance.

The duty ratio at which the load impedance Z1 becomes the maximum load impedance when the charging power is output from the high frequency power supply 12 is referred to as a first specific duty ratio. Similarly, a duty ratio at which the load impedance Z1 becomes the maximum load impedance in a situation where the high-frequency power supply 12 outputs push-in charging power is referred to as a second specific duty ratio. Then, based on the high frequency power output from the high frequency power supply 12 switching between the charging power and the pressing power, the duty ratio adjustment unit 26a sets the duty ratio to the first specific duty ratio and the second specific duty ratio. It can be said that it is possible to switch to

Next, the operation of the present embodiment will be described.
The DC / DC converter 25 adjusts the load impedance Z1 such that the efficiency of the rectifier 24 is high. In detail, the on / off duty ratio of the switching element 51 is adjusted such that the load impedance Z1 becomes large in a state where the voltage value applied to each element constituting the rectifier 24 is smaller than the withstand voltage value. Thereby, the efficiency of the rectifier 24 is improved.

Further, when the power value of the high frequency power output from the high frequency power supply 12 fluctuates, the duty ratio is adjusted according to the fluctuation so that the load impedance Z1 becomes the maximum load impedance. As a result, even if the power value of the high frequency power output from the high frequency power supply 12 fluctuates, it is possible to prevent the malfunction of the elements constituting the rectifier 24 and to suppress the decrease in the efficiency of the rectifier 24.

The present embodiment described in detail has the following excellent effects.
(1) A DC / DC converter that adjusts the load impedance Z1, which is the impedance from the output end of the rectifier 24 to the vehicle battery 22, so that the efficiency of the rectifier 24 is high, between the rectifier 24 and the vehicle battery 22 25 were provided. Thereby, the efficiency of the rectifier 24 can be improved.

(2) Specifically, the load impedance Z1 is increased in a state where the voltage value applied to each element constituting the rectifier 24 is smaller than the withstand voltage value. As a result, the current value of the current flowing through the rectifier 24 is reduced within a range in which an excessive voltage is not applied to each element constituting the rectifier 24. Therefore, the efficiency of the rectifier 24 can be improved while suppressing malfunction of each element constituting the rectifier 24.

(3) In the embodiment, the on / off duty ratio of the switching element 51 of the DC / DC converter 25 is adjusted. Thus, the load impedance Z1 can be adjusted without providing a high voltage resistant variable capacitor or variable inductor.

(4) The embodiment is configured to adjust the duty ratio in response to the fluctuation of the power value of the high frequency power output from the high frequency power supply 12. Specifically, the duty ratio was adjusted such that the load impedance Z1 was the maximum load impedance. Thereby, the fall of the efficiency of rectifier 24 accompanying the fluctuation of the electric power value of the high frequency electric power outputted from high frequency power supply 12 can be controlled.

The above embodiment may be modified as follows.
The embodiment is configured to adjust the duty ratio so that the load impedance Z1 becomes the maximum load impedance in accordance with the fluctuation of the power value of the high frequency power output from the high frequency power supply 12. However, the embodiment is not limited thereto. For example, the embodiment may be configured such that the load impedance Z1 becomes constant at a specific value by adjusting the duty ratio according to the fluctuation of the power value of the high frequency power output from the high frequency power supply 12. The point is that, as a comparative example, the efficiency of the rectifier 24 may be higher than that of the configuration in which the duty ratio is not adjusted according to the fluctuation of the power value of the high frequency power output from the high frequency power source 12. If the efficiency of the rectifier 24 is increased, the “specific value” may be, for example, the maximum load impedance that can fluctuate depending on the power value of the high frequency power (charging power or push charging power) output from the high frequency power source 12 The minimum value may be used.

In the embodiment, the DC / DC converter 25, in particular, the on / off duty ratio of the switching element 51 is adopted to adjust the load impedance Z 1. However, it is not limited to this as long as the load impedance Z1 can be varied.

The embodiment is configured to follow the fluctuation of the power value of the high frequency power output from the high frequency power supply 12 based on the measurement result of the measuring instrument 28, but is not limited thereto. For example, the measuring device 28 may be omitted. If there is no change in the relative position of the coils 13a and 23a, the second specific duty ratio (the duty ratio at which the load impedance Z1 becomes the maximum load impedance in a state where the high frequency power supply 12 is pressed and the charging power is output) Can be grasped (calculated). Therefore, the second specific duty ratio can be stored in a predetermined memory. In this configuration, when the high frequency power output from the high frequency power supply 12 is switched from the charging power to the charging power, the duty ratio adjustment unit 26a specifies the second specific duty ratio by referring to the memory. The duty ratio may be adjusted based on the result of the identification.

The circuit configuration of the rectifier 24 is not limited to that of the above-described embodiment, and may be arbitrary as long as it can be rectified. For example, a PFC circuit that performs rectification and power factor correction may be used.
Similarly, the circuit configuration of the DC / DC converter 25 is not limited to that of the above-described embodiment, and is arbitrary. For example, a boost circuit may be used.

○ In the embodiment, the timing of switching of the power value of the high frequency power output from the high frequency power source 12 (switching from charging power to pushing charging power) is adopted as an opportunity to adjust the duty ratio. It is not limited. For example, in the embodiment, when the measuring device 28 periodically measures the load impedance Z1, and the measured load impedance Z1 deviates from the maximum load impedance by a predetermined allowable value, the duty ratio is determined. It may be configured to make adjustments.

(Circle) although the constant of each impedance converter 31 and 32 was fixed in embodiment, it is not limited to this and may be variable. In this case, each impedance converter 31 is arranged such that each impedance converter 31, 32 corresponds to the variation of the relative position of each coil 13a, 23a, which is the relative position of the primary side coil 13a to the secondary side coil 23a. , 32 may be variably controlled. Thereby, high transmission efficiency can be maintained even when positional deviation of the coils 13a and 23a occurs.

The relative position of each coil 13a, 23a includes not only the distance between each coil 13a, 23a, but also the axial direction of each coil 13a, 23a, the manner of superposition of each coil 13a, 23a, and the like. The mode of superposition of the coils 13a and 23a is, for example, in the configuration in which the power transmitter 13 and the power receiver 23 are arranged in the vertical direction, the primary coil 13a and the secondary coil 23a when viewed from above Misalignment etc. can be considered.

In the configuration in which the constant of each of the impedance converters 31 and 32 is variable, for example, it has a constant resistance value (impedance) between the secondary side impedance converter 32 and the rectifier 24 regardless of the power value of input power. A fixed resistance is provided. Also, a relay is provided to switch the connection destination of the secondary side impedance converter 32 between the fixed resistor and the rectifier 24. When the constants of the impedance converters 31 and 32 are variably controlled, the connection destination of the secondary side impedance converter 32 is a fixed resistance.

When the constant of each of the impedance converters 31 and 32 is variably controlled, the embodiment may be configured such that the adjustment power for which the power value is smaller than the charging power is output from the high frequency power supply 12 . In this configuration, the resistance value of the fixed resistor may be equal to the impedance from the input end of the rectifier 24 to the automotive battery 22 when the load impedance Z1 is the maximum load impedance.

○ In the real part of the impedance from the output end of the power receiver 23 (secondary coil 23a) to the vehicle battery 22, there is a specific resistance value that provides relatively high transmission efficiency compared to other resistance values Do. In other words, in the real part of the impedance from the output end of the power receiver 23 to the vehicle battery 22, a specific resistance value (second resistance value) at which the transmission efficiency is higher than a predetermined resistance value (first resistance value) Exists. Specifically, when a virtual load is provided at the input end of the power transmitter 13, the resistance value of the virtual load is referred to as Ra1, and the resistance from the power receiver 23 (more specifically, the output end of the power receiver 23) to the virtual load When the value is referred to as Rb1, the specific resistance value is √ (Ra1 × Rb1).

Corresponding to this, the secondary side impedance converter 32 is connected from the input end of the rectifier 24 to the vehicle battery 22 so that the impedance from the output end of the power receiver 23 to the vehicle battery 22 approaches a specific resistance value. The impedance may be impedance transformed.

The primary side impedance converter 31 performs impedance conversion on the impedance from the input end of the power transmitter 13 to the vehicle battery 22 in a state where the impedance from the output end of the power receiver 23 to the vehicle battery 22 approaches a specific resistance value. Do. For example, the primary side impedance converter 31 is an input end of the power transmitter 13 such that the impedance from the output end of the high frequency power source 12 to the vehicle battery 22 is an impedance at which high frequency power having a desired power value can be obtained. The impedance from the above to the vehicle battery 22 may be impedance transformed.

Here, when the load impedance Z1 is set in consideration of the efficiency of the rectifier 24, it is assumed that the impedance from the input end of the rectifier 24 to the vehicle battery 22 deviates from the specific resistance value. On the other hand, by providing the secondary side impedance converter 32 as described above, the efficiency of the rectifier 24 can be improved while bringing the impedance from the output end of the power receiver 23 to the vehicle battery 22 closer to the specific resistance value. Can be

When the maximum load impedance fluctuates due to the fluctuation of the power value of the high frequency power output from the high frequency power supply 12, the impedance from the input end of the rectifier 24 to the vehicle battery 22 fluctuates along with the fluctuation. . Then, the impedance from the output end of the power receiver 23 to the vehicle battery 22 deviates from the specific resistance value.

On the other hand, the embodiment variably controls the constant (conversion ratio) of the secondary side impedance converter 32 in accordance with the fluctuation of the maximum load impedance, from the output end of the power receiver 23 to the vehicle battery 22. The impedance may be configured to be kept close to the specific resistance value.

If the load impedance Z1 is excessively high in consideration of the efficiency of the rectifier 24, the difference between the impedance from the input end of the rectifier 24 to the vehicle battery 22 and the specific resistance value becomes large. Then, the conversion ratio of the secondary side impedance converter 32 becomes excessively large. In this case, the conversion ratio may not be realistic or it may be necessary to use a special element. For this reason, the load impedance Z1 may be set to correspond to the difference with the specific resistance value so that the conversion ratio of the secondary side impedance converter 32 falls within a predetermined range.

○ The primary side impedance converter 31 is connected from the input end of the power transmitter 13 to the vehicle battery 22 so that the impedance from the output end of the high frequency power supply 12 to the vehicle battery 22 matches the output impedance of the high frequency power supply 12 It may be configured to impedance transform the impedance.

Similarly, the secondary side impedance converter 32 is configured such that the impedance from the output end of the power receiver 23 to the high frequency power source 12 matches the impedance from the output end of the power receiver 23 to the vehicle battery 22. The impedance from the input end to the vehicle battery 22 may be impedance converted.

The specific configuration of each impedance converter 31, 32 is arbitrary. For example, each of the impedance converters 31 and 32 may be configured of a π-type or T-type LC circuit. The configuration is not limited to the LC circuit, and a transformer or the like may be used.

In the embodiment, one impedance converter is provided for each of the ground-side device 11 and the vehicle-side device 21. However, the present invention is not limited to this. Two impedance converters may be provided in either or both of the ground-side device 11 and the vehicle-side device 21.

The primary side impedance converter 31 and / or the secondary side impedance converter 32 may be omitted.
The high frequency power supply 12 may be any of a power source, a voltage source and a current source.

In the embodiment, the vehicle battery 22 in which the impedance ZL fluctuates is adopted as the load to which the DC power rectified by the rectifier 24 is input, but the present invention is not limited to this, and other parts may be adopted. Good. In this case, as the load, one having a constant impedance regardless of the power value of the input power may be employed.

The voltage waveform of the high frequency power output from the high frequency power supply 12 may be a pulse waveform, a sine wave, or the like.
The high frequency power supply 12 may be omitted. In this case, the grid power is input to the transmitter 13.

In the embodiment, the capacitors 13 b and 23 b are provided, but these may be omitted. In this case, the primary side coil 13a and the secondary side coil 23a are subjected to magnetic field resonance using the parasitic capacitances of the coils 13a and 23a.

(Circle) in embodiment, although the resonant frequency of the power transmission device 13 and the resonant frequency of the call | power receiving device 23 were set identically, it is not limited to this. In another example, the resonant frequency of the power transmitter 13 and the resonant frequency of the power receiver 23 may be different from each other within the range in which power transmission is possible.

In the embodiment, magnetic field resonance is used to realize non-contact power transmission, but the present invention is not limited to this, and electromagnetic induction may be used.
(Circle) not being limited to this, although contactless energy transfer apparatus 10 was applied to vehicles in an embodiment, it may be applied to other apparatus. For example, the contactless power transmission device 10 may be applied to charge a battery of a mobile phone.

The power transmitter 13 may be configured to have a resonant circuit including the primary coil 13a and the primary capacitor 13b, and a primary induction coil coupled to the resonant circuit by electromagnetic induction. In this case, the resonant circuit is configured to receive high frequency power from the primary side induction coil by electromagnetic induction. Similarly, the power receiver 23 is configured to have a resonant circuit composed of the secondary coil 23a and the secondary capacitor 23b, and a secondary induction coil coupled to the resonant circuit by electromagnetic induction, High frequency power may be extracted from the resonant circuit of the power receiver 23 using an induction coil.

DESCRIPTION OF SYMBOLS 10 Contactless power transmission apparatus 11 Ground side apparatus (power transmission apparatus) 12 High frequency power supply 13a Primary coil 21 Vehicle side apparatus (power receiving apparatus) 22 Vehicle battery (load) 23a ... secondary coil, 24 ... rectifier, 25 ... DC / DC converter, 28 ... measuring instrument, 31 ... primary impedance converter, 32 ... secondary impedance converter, 41 ... diode bridge, 51 ... switching element, Z1-Load impedance.

Claims (6)

A power receiving device,
A secondary coil capable of receiving the AC power without contact from a power transmission device having a primary coil to which AC power is input;
A rectifying unit configured to rectify AC power received by the secondary coil;
And a load to which the DC power rectified by the rectifying unit is input,
The power receiving device further includes an adjusting unit provided between the rectifying unit and the load;
The said adjustment part is a power receiving apparatus comprised so that the impedance from the output end of the said rectification part to the said load may be adjusted so that the efficiency of the said rectification part may become high. The adjustment unit is configured to increase an impedance from an output end of the rectification unit to the load in a state where a voltage value applied to an element constituting the rectification unit is smaller than a withstand voltage value.
The power receiving device according to claim 1. The load is configured to vary in impedance,
The adjusting unit is configured to adjust the impedance from the output end of the rectifying unit to the load such that the efficiency of the rectifying unit is increased according to the fluctuation of the impedance of the load.
The power receiving device according to claim 1. The rectifying unit includes a diode.
The adjustment unit is configured to increase an impedance from an output end of the rectification unit to the load such that a current value of a current flowing to the diode is reduced.
The power receiving device according to claim 1. The adjustment unit includes a switching element that switches periodically.
The adjusting unit is configured to adjust an impedance from an output end of the rectifying unit to the load by adjusting an on / off duty ratio of the switching element.
The power receiving device according to any one of claims 1 to 4. Contactless power transmission device,
A power transmission device having a primary side coil to which AC power is input,
A secondary coil capable of receiving the AC power without contact from the primary coil, a rectifying unit for rectifying AC power received by the secondary coil, and DC power rectified by the rectifying unit A power receiving device having an input load;
In a contactless power transmission device provided with
A noncontact power transmission device comprising the power receiving device according to any one of claims 1 to 5 as the power receiving device.

Images