JP2014166094A - Transmission apparatus and non-contact power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission apparatus which can prevent the impedance at the output end of an AC power supply from deviating from a desired value by using a variable capacitor of relatively low capacitance, and to provide a non-contact power transmission device including the transmission apparatus.SOLUTION: The ground side apparatus 11 of a non-contact power transmission device 10 includes a high frequency power supply 12, and a transmitter 13 which is supplied with high frequency power from the high frequency power supply 12. Between the high frequency power supply 12 and the transmitter 13, a plurality of impedance converters 31, 32 are provided. In a situation where a high frequency power of the maximum power value is supplied to the second capacitor 32b of a second impedance converter 32, the virtual impedance VZS between both impedance converters 31, 32 is set so that the applied voltage to the second capacitor 32b approaches an allowable maximum voltage.

Description

  The present invention relates to a power transmission device and a contactless power transmission device including the power transmission device.

  Conventionally, as a power transmission device capable of transmitting AC power in a contactless manner to a power receiving device having a secondary side coil, an AC power source and a primary coil to which AC power is supplied from the AC power source Is known (see, for example, Patent Document 1). This type of power transmission device performs non-contact power transmission from the primary coil to the secondary coil by causing magnetic resonance between the primary coil and the secondary coil.

JP 2009-106136 A

  Here, an impedance converter may be provided between the AC power supply and the primary coil so that the impedance of the output terminal of the AC power supply becomes a desired value. In this case, for example, when the relative position of the primary side coil and the secondary side coil changes, the input impedance of the primary side coil may change, and the impedance of the output end of the AC power supply may deviate from a desired value.

  On the other hand, for example, it is conceivable to provide a variable capacitor with a variable capacitance in the impedance conversion unit in order to follow the change in the relative position. In this case, a high-capacity variable capacitor may be required depending on the relationship with a desired value or the like. However, a variable capacitor is generally one having a relatively low capacity, and such a high-capacity variable capacitor is not practical or expensive.

  The present invention has been made in view of the above-described circumstances, and can use a relatively low-capacity variable capacitor to suppress the deviation of the impedance of the output end of the AC power supply from a desired value and An object of the present invention is to provide a non-contact power transmission apparatus including the power transmission device.

  A power transmission device that achieves the above object includes: an AC power source capable of supplying AC power; and a primary side coil to which the AC power is supplied from the AC power source. In the power transmission device capable of transmitting the AC power in a non-contact manner, the power transmission device includes a plurality of impedance conversion units that are provided between the AC power source and the primary coil and perform impedance conversion, and the plurality of impedance conversion units are connected in series. The AC power supplied from the AC power source is supplied to the primary coil through the plurality of impedance converters, and the first of the plurality of impedance converters The first impedance converter closest to the secondary coil has a variable capacitor with at least a variable capacitance, and the first impedance converter The impedance between the first impedance converter and the second impedance converter disposed next to the first impedance converter is the maximum power among the AC power that can be supplied from the AC power source to the elements constituting the second impedance converter. The voltage applied to the element is set so as to approach the maximum allowable voltage in a situation where AC power of a value is supplied to the element.

  According to this configuration, since a plurality of impedance conversion units are provided, the impedance of the output end of the AC power supply can be set to a desired value. In addition, by performing variable control of the capacitance of the variable capacitor, it is possible to follow fluctuations in the input impedance of the primary coil, thereby suppressing the impedance of the output terminal of the AC power supply from deviating from a desired value. Can do.

  The impedance between the first impedance conversion unit and the second impedance conversion unit is such that the AC power having the maximum power value is supplied to the element among the AC power that can be supplied from the AC power source to the element constituting the second impedance conversion unit. In such a situation, the voltage applied to the element is set to approach the maximum allowable voltage. Thereby, the impedance between each impedance conversion part is high within the voltage range in which the element which comprises a 2nd impedance conversion part can operate | move normally. Therefore, the capacitance of the variable capacitor required for impedance conversion can be reduced. Therefore, it is possible to prevent the impedance at the output end of the AC power supply from deviating from a desired value by using a relatively low-capacity variable capacitor.

  In the power transmission device, the element of the second impedance conversion unit may be connected to a power supply line and a ground line that connect the first impedance conversion unit and the second impedance conversion unit. According to such a configuration, when the impedance between the impedance conversion units increases, the applied voltage to the elements connected to both the power supply line and the ground line increases accordingly. And the impedance between each impedance conversion part is set in consideration of the applied voltage to the said element closely related to the impedance between each impedance conversion part in this way. As a result, the capacitance of the variable capacitor can be suitably lowered within a range in which the second impedance converter can operate normally.

  About the said power transmission apparatus, the said permissible maximum voltage is good to set based on the specification of the said element of a said 2nd impedance conversion part. According to such a configuration, the allowable maximum voltage is set based on the specifications of the elements of the second impedance conversion unit, and thus the voltage range in which the second impedance conversion unit can operate normally can be set appropriately. Thereby, the impedance between each impedance conversion part and the capacitance of a variable capacitor can be set up suitably.

  It may be a non-contact power transmission device including the power transmission device and the power receiving device. According to such a configuration, the impedance of the output terminal of the AC power supply can be prevented from deviating from a desired value using a relatively low-capacity variable capacitor in the contactless power transmission device.

  According to the present invention, it is possible to suppress the deviation of the impedance of the output terminal of the AC power supply from a desired value using a variable capacitor having a relatively low capacity.

The circuit diagram which shows the electrical structure of a ground side apparatus and a non-contact electric power transmission apparatus.

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

  The ground side device 11 includes a high frequency power source 12 (AC power source) capable of supplying high frequency power (AC power) having a predetermined frequency. The high-frequency power source 12 is configured to convert system power supplied from a system power source serving as infrastructure into high-frequency power and supply the converted high-frequency power. The high frequency power supply 12 is configured to be able to supply a plurality of types of high frequency power having different power values.

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

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

  According to this configuration, when high-frequency power is supplied to the power transmitter 13 (primary coil 13a), the power transmitter 13 and the power receiver 23 (secondary coil 23a) undergo magnetic field resonance. As a result, the power receiver 23 receives a 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 load 22 is supplied with high-frequency power received by the power receiver 23. Specifically, the load 22 rectifies the high-frequency power received by the power receiver 23, and DC power rectified by the rectifier. Has a vehicle battery. The high frequency power received by the power receiver 23 is used for charging the vehicle battery.

  The ground side device 11 includes a power source side controller 14 that controls the high frequency power source 12 and the like. The power supply side controller 14 determines whether or not high frequency power is supplied from the high frequency power supply 12 and controls the power value of the high frequency power supplied from the high frequency power supply 12.

  The vehicle-side device 21 includes a vehicle-side controller 24 configured to be able to communicate with the power supply-side controller 14 wirelessly. The non-contact power transmission apparatus 10 starts or ends power transmission through the exchange of information between the controllers 14 and 24.

  The non-contact power transmission device 10 includes a plurality of impedance converters (impedance conversion units) 31 to 34. Specifically, the non-contact power transmission apparatus 10 includes a first impedance converter 31 (first impedance conversion unit) and a second impedance converter 32 (second impedance conversion unit) provided in the ground side device 11, a vehicle A third impedance converter 33 and a fourth impedance converter 34 provided in the side device 21 are provided.

  The first impedance converter 31 and the second impedance converter 32 are provided between the high-frequency power source 12 and the power transmitter 13, and both are arranged in series. Specifically, the ground side device 11 is provided with a power line L1 and a ground line L2 that connect the first impedance converter 31 and the second impedance converter 32, and the first impedance converter 31 and the second The impedance converter 32 is connected in series by a power line L1 and a ground line L2.

  The first impedance converter 31 is provided at the position closest to the power transmitter 13 (the most downstream position in the power transmission path between the high-frequency power source 12 and the power transmitter 13). In other words, the first impedance converter 31 is the last-stage impedance converter among the plurality of impedance converters 31 and 32 provided between the high-frequency power source 12 and the power transmitter 13.

  The second impedance converter 32 is disposed next to the first impedance converter 31. In other words, the second impedance converter 32 is directly connected to the first impedance converter 31 by the power supply line L1 and the ground line L2. The high frequency power supplied from the high frequency power supply 12 is supplied to the power transmitter 13 via the second impedance converter 32 and the first impedance converter 31.

  The third impedance converter 33 and the fourth impedance converter 34 are provided between the power receiver 23 and the load 22. The third impedance converter 33 and the fourth impedance converter 34 are arranged in series, and the high frequency power received by the power receiver 23 is loaded via the third impedance converter 33 and the fourth impedance converter 34. 22 is supplied.

  A detailed configuration of each of the impedance converters 31 to 34 will be described. The first impedance converter 31 is composed of an inverted L-type LC circuit having a first inductor 31a and a first capacitor 31b. The second impedance converter 32 is composed of an inverted L-type LC circuit having a second inductor 32a and a second capacitor 32b. Specifically, the second inductor 32 a has one end connected to the power supply line L <b> 1 and the other end connected to the high frequency power supply 12. The second capacitor 32b is closer to the first impedance converter 31 than the second inductor 32a, and is connected to both the power supply line L1 and the ground line L2.

  The third impedance converter 33 is composed of an L-type LC circuit having a third inductor 33a and a third capacitor 33b. The fourth impedance converter 34 is composed of an inverted L-type LC circuit having a fourth inductor 34a and a fourth capacitor 34b.

  In the following description, the first impedance converter 31 and the second impedance converter 32 are converted into the primary side impedance converter group G1, and the third impedance converter 33 and the fourth impedance converter 34 are converted into the secondary side impedance. It is called instrument group G2.

  The secondary impedance converter group G2 performs impedance conversion of the impedance ZL of the load 22 so that the impedance from the output terminal of the power receiver 23 to the load 22 approaches (preferably matches) a predetermined value.

  The predetermined value may be, for example, a value that relatively increases transmission efficiency. Specifically, a specific resistance value Rout having a relatively higher transmission efficiency than other resistance values exists in the real part of the impedance from the output terminal of the power receiver 23 to the load 22. If a virtual load is provided at the input end of the power transmitter 13, the resistance value of the virtual load is Ra, and the resistance value from the power receiver 23 (specifically, the output end of the power receiver 23) to the virtual load is Rb. Then, the specific resistance value Rout is √ (Ra × Rb). The secondary impedance converter group G2 performs impedance conversion so that the impedance from the output terminal of the power receiver 23 to the load 22 approaches (preferably matches) the specific resistance value Rout.

  Here, the power value of the high frequency power supplied from the high frequency power source 12 is the impedance Zp of the input end of the primary side impedance converter group G1, that is, the impedance of the output end of the high frequency power source 12 (from the output end of the high frequency power source 12 to the load). Impedance up to 22) depending on Zp.

  In such a configuration, the primary-side impedance converter group G1 is connected to the input impedance of the power transmitter 13 (impedance from the input end of the power transmitter 13 to the load 22) so that high-frequency power of a desired power value is supplied from the high-frequency power source 12. ) Impedance conversion of Zin.

  For example, the power value of the power supplied from the high-frequency power source 12 required for the power value of the DC power supplied to the vehicle battery of the load 22 to be a power value suitable for charging is the power value suitable for charging. To do. Then, the impedance from the output end of the high frequency power supply 12 to the load 22 for supplying high frequency power having a power value suitable for charging from the high frequency power supply 12 is defined as an input impedance Zt suitable for charging. In this case, the primary-side impedance converter group G1 is configured so that the impedance Zp from the output end of the high-frequency power source 12 to the load 22 approaches (preferably matches) the input impedance Zt suitable for the charging. Impedance conversion is performed on the input impedance Zin.

  In other words, the high frequency power supply 12 is configured to be able to supply high frequency power of a desired power value under the condition that the impedance Zp from the output terminal of the high frequency power supply 12 to the load 22 is the input impedance Zt suitable for the charging. It can be said that it is. The input impedance Zt suitable for the charging corresponds to “specific impedance”.

  Here, when the power transmitter 13 and the power receiver 23 deviate from a predetermined reference position, that is, when the relative position of the power transmitter 13 and the power receiver 23 varies, the input impedance Zin of the power transmitter 13 varies. Then, the impedance Zp from the output terminal of the high frequency power supply 12 to the load 22 may deviate from the input impedance Zt suitable for charging.

  On the other hand, this non-contact electric power transmission apparatus 10 is equipped with the structure for tracking the fluctuation | variation of the said relative position. Specifically, the constant (conversion ratio) of the first impedance converter 31 is configured to be variable. Specifically, the capacitance of the first capacitor 31b of the first impedance converter 31 is variable. The constant of the second impedance converter 32 is fixed. The constant (conversion ratio) can be said to be impedance, inductance, or capacitance.

  Further, the ground side device 11 includes a primary side measuring device 41 provided between the high frequency power source 12 and the second impedance converter 32. The primary side measuring instrument 41 measures the voltage waveform and the current waveform supplied from the high frequency power supply 12 and transmits the measurement results to the power supply side controller 14.

  The power supply side controller 14 calculates the impedance Zp from the output end of the high frequency power supply 12 to the load 22 based on the measurement result of the primary side measuring instrument 41 in a situation where high frequency power is supplied from the high frequency power supply 12. Based on the calculation result, the constant of the first impedance converter 31 (specifically, the capacitance of the first capacitor 31b) is variably controlled. For example, the power supply side controller 14 determines whether or not the calculated impedance Zp is within a predetermined allowable range including the input impedance Zt suitable for charging. Then, when the impedance Zp is outside the allowable range, the power supply side controller 14 performs variable control of the constant of the first impedance converter 31 so that the impedance Zp falls within the allowable range.

  Here, as the impedance between the first impedance converter 31 and the second impedance converter 32 (hereinafter referred to as virtual impedance VZS) increases, a constant required for the first impedance converter 31, specifically, the first The capacitance (capacitance) of one capacitor 31b is lowered. On the other hand, the higher the virtual impedance VZS, the higher the voltage applied to the second capacitor 32b of the second impedance converter 32. That is, the virtual impedance VZS is a parameter that determines the capacitance of the first capacitor 31b and the voltage applied to the second capacitor 32b.

  In this regard, the virtual impedance VZS is the first in a situation where the high frequency power having the maximum power value among the high frequency power that can be supplied from the high frequency power supply 12 to the second capacitor 32b of the second impedance converter 32 is supplied to the second capacitor 32b. The voltage applied to the two capacitors 32b is set (high) so as to approach (preferably match) the allowable maximum voltage. In other words, the virtual impedance VZS is as much as possible within the range where the applied voltage of the second capacitor 32b does not exceed the allowable maximum voltage even when the high frequency power of the maximum power value is supplied to the second capacitor 32b. It is set high. The constants of the impedance converters 31 and 32 are the virtual impedance VZS and the input impedance Zin of the power transmitter 13 so that the impedance Zp from the output terminal of the high frequency power supply 12 to the load 22 becomes the input impedance Zt suitable for charging. It is set corresponding to. The virtual impedance VZS is higher than the impedance Zp (input impedance Zp suitable for charging) from the output end of the high-frequency power supply 12 to the load 22.

  Here, the allowable maximum voltage is set based on the specification of the second capacitor 32b, and is the maximum voltage that can be applied within a voltage range in which the second capacitor 32b can operate normally. As an example of the allowable maximum voltage, for example, a rated voltage (withstand voltage) of the second capacitor 32b or a voltage obtained by subtracting a predetermined margin from the rated voltage can be considered. Further, for example, in the case where a use voltage range in which the second capacitor 32b is normally used is assumed in relation to the rated voltage, the maximum value of the use voltage range or a voltage obtained by subtracting a predetermined margin from the maximum value is used. The allowable maximum voltage may be used.

  The high-frequency power having the maximum power value that can be supplied to the second capacitor 32b is determined based on the specifications of the high-frequency power source 12 and the impedance Zp from the output terminal of the high-frequency power source 12 to the load 22. For example, under the condition that the impedance Zp from the output terminal of the high frequency power supply 12 to the load 22 is constant (input impedance Zt suitable for charging), the power value set in the high frequency power supply 12 is maximized. The power value of the high-frequency power supplied to the second capacitor 32b. Further, in the configuration in which the impedance Zp from the output end of the high frequency power supply 12 to the load 22 can be varied, the impedance Zp from the output end of the high frequency power supply 12 to the load 22 is in a condition where the impedance Zp is the minimum value. This is the power value of the high-frequency power supplied to the second capacitor 32b when the power value set at is the maximum.

Next, the operation of this embodiment will be described.
The impedance Zp from the output terminal of the high frequency power supply 12 to the load 22 becomes the input impedance Zt suitable for charging by impedance conversion by the primary side impedance converter group G1 including a plurality of impedance converters 31 and 32. In such a configuration, since the virtual impedance VZS is set high so that the applied voltage to the second capacitor 32b becomes the allowable maximum voltage in the situation where the high-frequency power of the maximum power value is supplied to the second capacitor 32b, The capacitance of the first capacitor 31b required for conversion is low.

According to the embodiment described in detail above, the following excellent effects are obtained.
(1) The primary side impedance converter group G1 which is provided between the high frequency power supply 12 and the power transmitter 13 and includes a plurality of impedance converters 31 and 32 arranged in series with each other is an output of the high frequency power supply 12. Impedance conversion is performed so that the impedance Zp from the end to the load 22 becomes the input impedance Zt suitable for charging. Thereby, the high frequency power of a desired power value can be supplied from the high frequency power source 12.

  The first impedance converter 31 closest to the power transmitter 13 among the plurality of impedance converters 31 and 32 has a first capacitor 31b (variable capacitor) whose capacitance is variable. And it was set as the structure which performs the variable control of the capacitance of the 1st capacitor 31b according to the fluctuation | variation of the relative position of the power transmission device 13 (primary side coil 13a) and the power receiving device 23 (secondary side coil 23a). As a result, even when the relative position fluctuates, the impedance Zp from the output end of the high frequency power supply 12 to the load 22 can be prevented from deviating from the input impedance Zt suitable for charging.

  And the impedance (virtual impedance VZS) between the 1st impedance converter 31 and the 2nd impedance converter 32 arrange | positioned adjacent to it is the element (2nd capacitor 32b) which comprises the 2nd impedance converter 32. Is set to be as high as possible within the normal operating voltage range. Specifically, the virtual impedance VZS is supplied from the high frequency power supply 12 to the second capacitor 32b in a situation where the maximum power value of the high frequency power that can be supplied to the second capacitor 32b is supplied to the second capacitor 32b. The applied voltage is set to approach (preferably match) the maximum allowable voltage. As a result, the capacitance of the first capacitor 31b can be lowered within a voltage range in which the second capacitor 32b can operate normally. Therefore, it is possible to suppress the impedance Zp from the output terminal of the high-frequency power source 12 to the load 22 from deviating from a desired value (for example, the input impedance Zt suitable for charging) by using a variable capacitor having a relatively low capacitance.

  (2) The second capacitor 32b as an element constituting the second impedance converter 32 is connected to both the power supply line L1 and the ground line L2 that connect the first impedance converter 31 and the second impedance converter 32. ing. In this case, since the voltage applied to the virtual impedance VZS and the voltage applied to the second capacitor 32b are the same, when the virtual impedance VZS increases, the voltage applied to the second capacitor 32b increases accordingly. Become. Further, when the virtual impedance VZS increases, the voltage applied to the second capacitor 32b is likely to be higher than the voltage applied to the second inductor 32a connected only to the power supply line L1. There is.

  In this regard, according to the present embodiment, the virtual impedance VZS is set in consideration of the allowable maximum voltage of the second capacitor 32b that is closely related to the virtual impedance VZS as described above. Thereby, the capacitance of the first capacitor 31b can be suitably reduced within a range in which the second impedance converter 32 can operate normally.

  (3) The allowable maximum voltage is set based on the specification (for example, rated voltage) of the element (in this embodiment, the second capacitor 32b) constituting the second impedance converter 32. As a result, the voltage range in which the second capacitor 32b can operate normally can be set appropriately, and the virtual impedance VZS and the capacitance of the first capacitor 31b can be suitably set accordingly.

(4) The constant of the second impedance converter 32 is a fixed value. Thereby, a relatively high constant can be easily realized.
In addition, you may change the said embodiment as follows.

  In the embodiment, the primary side impedance converter group G1 is configured by the two impedance converters 31 and 32, but is not limited thereto, and may be configured by three or more impedance converters.

  In the embodiment, the second impedance converter 32 is configured with an LC circuit, but is not limited thereto, and may be configured with a transformer. When the primary side impedance converter group G1 is composed of three or more impedance converters as described above, an impedance converter other than the first impedance converter 31 closest to the power transmitter 13 is connected to the transformer. You may comprise. In this case, the virtual impedance VZS may be set based on the maximum allowable voltage of the transformer. The allowable maximum voltage of the transformer is set based on the specification of the transformer.

In the embodiment, the first impedance converter 31 is an inverted L-type LC circuit, but is not limited thereto, and the specific configuration thereof is arbitrary. For example, it may be L-shaped.
In the embodiment, attention is paid to the allowable maximum voltage of the second capacitor 32b, but the present invention is not limited to this, and the allowable maximum voltage of the second inductor 32a may be noted. Specifically, the voltage applied to the second inductor 32a increases as the difference between the impedance Zp from the output terminal of the high-frequency power source 12 to the load 22 and the virtual impedance VZS increases. In this case, depending on the relationship between the impedance Zp from the output terminal of the high frequency power supply 12 to the load 22 and the virtual impedance VZS, the voltage applied to the second inductor 32a before the voltage applied to the second capacitor 32b exceeds the allowable maximum voltage. There may be cases where the voltage exceeds the maximum allowable voltage. Focusing on this point, the virtual impedance VZS may be set so that the voltage applied to the second inductor 32a does not exceed the allowable maximum voltage. In this case, the allowable maximum voltage is set based on the specifications of the second inductor 32a. In short, the element of the second impedance converter is not limited to the second capacitor 32b connected to both the power supply line L1 and the ground line L2, and the second inductor 32a connected only to the power supply line L1 is also included. included. In other words, when there are a plurality of elements constituting the second impedance converter, the virtual impedance VZS may be set in consideration of the allowable maximum voltage of at least one element among the plurality of elements.

  In the embodiment, the second capacitor 32b is provided as an element connected to both the power supply line L1 and the ground line L2. However, the present invention is not limited to this, and an inductor may be provided instead of the second capacitor 32b. . In this case, the virtual impedance VZS may be set based on the maximum allowable voltage of the inductor. Note that the allowable maximum voltage of the inductor is set based on the specification of the inductor.

  The secondary side impedance converter group G2 performs impedance conversion so that the impedance from the output terminal of the power receiver 23 to the load 22 approaches the specific resistance value Rout, but is not limited thereto. For example, in a configuration using a power source as the high-frequency power source 12, impedance conversion is performed so that the impedance from the output end of the power receiver 23 to the load 22 matches the impedance from the output end of the power receiver 23 to the high-frequency power source 12. It may be a thing.

  A constant of at least one of the third impedance converter 33 and the fourth impedance converter 34 may be variable. For example, the constant of the third impedance converter 33 is variably controlled according to the change in the relative position of the power transmitter 13 and the power receiver 23, and the constant of the fourth impedance converter 34 according to the change in the impedance ZL of the load 22. It may be configured to perform the variable control.

O At least one of the third impedance converter 33 and the fourth impedance converter 34 may be omitted.
In the embodiment, the primary impedance converter group G1 is configured to perform impedance conversion so that the impedance from the output terminal of the high-frequency power source 12 to the load 22 approaches the input impedance Zt suitable for charging. For example, the impedance conversion may be performed so that the power factor is improved (reactance approaches 0).

  In addition, when a power source is used as the high frequency power source 12, the primary side impedance converter group G 1 is configured so that the impedance Zp from the output end of the high frequency power source 12 to the load 22 matches the output impedance of the high frequency power source 12. The input impedance Zin of the power transmitter 13 may be impedance-converted. In this case, the primary side measuring device 41 measures the reflected wave power from the power transmitter 13 toward the high frequency power source 12.

The subject of variable control of the capacitance of the first capacitor 31b is arbitrary. For example, the vehicle side controller 24 may be configured to perform the variable control.
The high frequency power supply 12 may be any of a voltage source, a current source, and a power source.

In the embodiment, the resonance frequency of the power transmitter 13 and the resonance frequency of the power receiver 23 are set to be the same. However, the present invention is not limited to this, and may be different within a range in which power transmission is possible.
In embodiment, although the power transmission device 13 and the power receiving device 23 were the same structures, it is not restricted to this, A different structure may be sufficient.

  In embodiment, although the primary side coil 13a and the primary side capacitor | condenser 13b were connected in parallel, it is not restricted to this, You may connect in series. Similarly, the secondary coil 23a and the secondary capacitor 23b may be connected in series.

In the embodiment, the capacitors 13b and 23b are provided, but these may be omitted. In this case, magnetic field resonance is performed using the parasitic capacitances of the coils 13a and 23a.
In the embodiment, magnetic field resonance is used in order to realize non-contact power transmission. However, the present invention is not limited to this, and electromagnetic induction may be used.

  In embodiment, the non-contact electric power transmission apparatus 10 was applied to the vehicle, However, It is not restricted to this, You may apply to another apparatus. For example, it may be applied to charge a battery of a mobile phone.

  The power transmitter 13 may have a configuration including a resonance circuit including a primary side coil 13a and a primary side capacitor 13b, and a primary side coupling coil that is coupled to the resonance circuit by electromagnetic induction. Similarly, the power receiver 23 may include a resonance circuit including a secondary coil 23a and a secondary capacitor 23b, and a secondary coupling coil coupled to the resonance circuit by electromagnetic induction.

Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.
(A) The power transmission device according to any one of claims 1 to 3, wherein the constant of the second impedance converter is a predetermined fixed value.

  (B) The constant of the first impedance converter is variably controlled in accordance with a change in the relative position of the primary coil with respect to the secondary coil. The power transmission equipment described in the section.

  (C) The plurality of impedance converters perform impedance conversion so that the impedance of the output end of the AC power supply becomes a predetermined specific impedance. The power transmission apparatus as described in any one of them.

(D) The power receiving device includes a load to which AC power received by the secondary coil is supplied,
The non-contact power transmission device according to claim 4, wherein the plurality of impedance converters perform impedance conversion so that an impedance from an output terminal of the AC power supply to the load becomes a predetermined specific impedance.

  DESCRIPTION OF SYMBOLS 10 ... Non-contact electric power transmission apparatus, 11 ... Ground side apparatus (power transmission apparatus), 12 ... High frequency power supply, 13a ... Primary side coil, 14 ... Power supply side controller, 21 ... Vehicle side apparatus (power receiving apparatus), 22 ... Load, 23a ... secondary coil, 31 ... first impedance converter, 32 ... second impedance converter, 41 ... primary measuring instrument, L1 ... power supply line, L2 ... ground line.

Claims (4)

AC power supply capable of supplying AC power,
A primary coil to which the AC power is supplied from the AC power source;
In a power transmission device capable of transmitting the AC power in a contactless manner with respect to a power receiving device having a secondary side coil,
Provided between the AC power supply and the primary side coil, comprising a plurality of impedance conversion units for impedance conversion,
The plurality of impedance converters are arranged in series, and the AC power supplied from the AC power supply is supplied to the primary coil via the plurality of impedance converters,
The first impedance converter closest to the primary coil among the plurality of impedance converters has a variable capacitor having at least a variable capacitance,
The impedance between the first impedance converter and the second impedance converter disposed adjacent to the first impedance converter is supplied from the AC power source to the elements constituting the second impedance converter. A power transmission device, wherein a voltage applied to the element is set to approach an allowable maximum voltage in a situation where AC power having a maximum power value is supplied to the element among AC power that can be generated.   The power transmission device according to claim 1, wherein the element of the second impedance converter is connected to both a power line and a ground line that connect the first impedance converter and the second impedance converter.   The power transmission device according to claim 1 or 2, wherein the allowable maximum voltage is set based on a specification of the element of the second impedance conversion unit. The power transmission device according to any one of claims 1 to 3,
The power receiving device;
A non-contact power transmission device comprising: