JP5772687B2 - Power transmission system, power transmission device and power reception device, charging facility, and electric vehicle - Google Patents

Description

The present invention relates to a power transmission system , a power transmission device and a power reception device, a charging facility, and an electric vehicle .

Conventionally, as a non-contact power feeding method, an electromagnetic induction method, a radio wave reception method, an electric field coupling method, a magnetic field resonance method, and the like are known. Among these methods, the magnetic field resonance method is a technology in which an LC resonance circuit composed of a coil and a capacitor is provided on the power transmission device side and the power reception device side, and the power is transmitted wirelessly by resonating the magnetic field between the two circuits. (See Patent Document 1 below).
This magnetic field resonance method has a feature that it can realize high-efficiency and long-distance power transmission with a weak magnetic field, compared to a widely used electromagnetic induction method, and can be used for charging mobile terminals, electric vehicles, etc. It is attracting attention as a next-generation wireless power transmission technology.

JP 2011-147271 A

  A non-contact power feeding power transmission system includes a power transmission device that wirelessly transmits AC power supplied from an AC power source via a spatial transmission path, and a power reception device that wirelessly receives AC power via the spatial transmission path. The power receiving apparatus may include a rectifier that rectifies received AC power and converts the received AC power into DC power, and a charger (for example, a DC / DC converter) that performs DC conversion of the DC power output from the rectifier. is there.

When the output of the DC / DC converter is used for charging a storage battery such as a battery, it is desirable that the input impedance of the DC / DC converter is constant during the charging period from the viewpoint of power transmission efficiency. Since the input impedance also varies with the variation of the input current at the time of stopping and at the time of stopping, there is a problem that the matching (matching) of the input impedance cannot be taken and the power transmission efficiency is lowered.
Further, if the input impedance cannot be matched, each component element may be damaged due to excessive electrical stress. Moreover, it does not reach the power that can be originally obtained.

The present invention has been made in view of the above-described circumstances, and provides a power transmission system capable of improving power transmission efficiency and avoiding damage to components, a power transmission device and a power reception device, a charging facility, and an electric vehicle . The purpose is to provide.

 In order to achieve the above object, in the present invention, as a first solving means related to a power transmission system, a power transmission apparatus that converts supplied AC power or DC power into AC power and transmits the AC power via a transmission line; In a power transmission system comprising a power receiving device that receives the AC power via the transmission path, the power receiving device includes a rectifier that rectifies the AC power received via the transmission path and converts the AC power into DC power. A DC converter that performs DC conversion of DC power output from the rectifier, and a current command value in which an input impedance of the DC converter becomes a set value based on an input voltage of the DC converter, and the DC The power receiving side control device that controls the DC converter so that the input current of the converter matches the current command value is adopted.

 In the present invention, as a second solving means related to the power transmission system, in the first solving means, the power transmission device includes an AC converter that converts the supplied AC power or DC power into AC power; A power transmission side control device that controls the amplification degree of the AC power by the amplifier, the power reception side control device transmits the current command value to the power transmission side control device, and the power transmission side control device Based on the current command value received from the receiving side control device, means for controlling the amplification degree of the AC power by the amplifier so that the input power of the DC converter becomes constant is adopted.

Further, in the present invention, as a third solving means related to the power transmission system, in the first or second solving means, the power transmission device magnetically resonates the AC power via a spatial transmission path as the transmission path. A power transmission side resonator for wirelessly transmitting power by a method, and the power reception device includes a power reception side resonator for wirelessly receiving the AC power from the power transmission side resonator via the spatial transmission path Is adopted.
Further, in the present invention, as a fourth solving means relating to the power transmission system, in any one of the first to third solving means, bidirectional power transmission is performed between the power transmission device and the power receiving device. Adopt the means that it is possible.

 According to the present invention, the input impedance of the DC converter provided on the power receiving device side is maintained constant during the operation period of the DC converter (including when the output of the power converter starts and when it is stopped). As a result, matching of input impedance is always achieved, and power transmission efficiency can be improved as compared with the conventional case, and damage to the constituent elements can be avoided. In addition, the maximum power point can be maintained.

It is a schematic block diagram of the electric power transmission system A which concerns on this embodiment. It is a figure which shows the profile of the input voltage of DC / DC converter 23, an input current, and an input impedance during a charge period.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a power transmission system A according to the present embodiment. As shown in this figure, the power transmission system A according to the present embodiment supplies charging power (AC power) from a charging facility 100 installed at a predetermined position such as a parking lot to an electric vehicle 200 through a spatial transmission path 300. It is a non-contact power feeding type power transmission system that wirelessly transmits through the power transmission system 10, and includes a power transmission device 10 mounted on the charging facility 100 side and a power reception device 20 mounted on the electric vehicle 200 side.

 The power transmission device 10 wirelessly transmits AC power supplied from an AC power source 30 (for example, a commercial power source having a single phase of 200 V, a frequency of 50 or 60 Hz) provided on the charging facility 100 side via the spatial transmission line 300. Yes, an amplifier 11 and a power transmission side resonator 12 are provided.

 The amplifier 11 is an AC converter that performs AC / AC conversion of AC power supplied from the AC power supply 30 and outputs the AC power obtained thereby to the power transmission side resonator 12. Specifically, the amplifier 11 includes a rectifier circuit 11a that converts AC power supplied from the AC power supply 30 into DC power, and DC power output from the rectifier circuit 11a into AC power having a predetermined voltage and a predetermined frequency. The inverter 11b which converts and outputs to the power transmission side resonator 12 and the power transmission side control apparatus 11c which controls switching elements, such as MOS-FET which comprises this inverter 11b, are provided.

 The power transmission side control device 11c controls the voltage and frequency of the AC power output from the inverter 11b by controlling the switching elements constituting the inverter 11b. That is, the power transmission side control device 11c controls the amplification degree of the AC power by the amplifier 11 by controlling the switching elements constituting the inverter 11b. The power transmission side control device 11c includes an antenna 11d, and has a function of performing wireless communication with a power reception side control device 23c described later using a short-range wireless communication standard such as Bluetooth (registered trademark). .

 The power transmission side resonator 12 is an LC resonance circuit composed of a spirally wound coil and a capacitor for wirelessly transmitting AC power input from the amplifier 11 through the spatial transmission path 300 by a magnetic field resonance method. In addition, as a capacitor | condenser for comprising the power transmission side resonator 12, the parasitic capacitance of a coil may be utilized or you may provide a capacitor | condenser element separately.

 The power receiving device 20 wirelessly receives AC power wirelessly transmitted from the power transmission device 10 via the space transmission path 200, and converts the received AC power into charging DC power and is mounted on the electric vehicle 200 side. For example, the battery is supplied to a battery 40 such as a lithium ion battery, and includes a power receiving resonator 21, a rectifier 22, and a DC / DC converter 23.

 The power receiving side resonator 21 is an LC resonance circuit composed of a spirally wound coil and a capacitor for wirelessly receiving AC power from the power transmitting side resonator 12 via the spatial transmission path 300. If circuit constants are set so that the resonance frequencies of the resonators 12 and 21 of both the power transmission device 10 and the power reception device 20 are equal, magnetic field resonance is generated between the power transmission side resonator 12 and the power reception side resonator 21. be able to.

 When magnetic field resonance occurs, the AC power output from the amplifier 11 is converted into magnetic energy by the power transmission side resonator 12 and wirelessly transmitted, and the magnetic energy is reconverted to AC power by the power reception side resonator 21. The AC power obtained from the power receiving resonator 21 is output to the rectifier 22 provided in the subsequent stage. The rectifier 22 rectifies the AC power input from the power-receiving-side resonator 21 and converts it into DC power, and outputs the obtained DC power to the DC / DC converter 23.

 The DC / DC converter 23 performs DC conversion (DC / DC conversion) of the DC power input from the rectifier 22 and outputs the DC power obtained by the DC conversion to the battery 40 as charging DC power. Specifically, the DC / DC converter 23 includes a switching circuit 23a for stepping down DC power input from the rectifier 22 by an on / off operation of a switching element such as a MOS-FET, and a gate signal for turning on / off the switching element. A gate drive circuit 23b to be generated and a power receiving side control device 23c for controlling the switching elements of the switching circuit 23a via the gate drive circuit 23b are provided.

 The power receiving side control device 23c monitors the input voltage of the DC / DC converter 23, calculates a current command value at which the input impedance of the DC / DC converter 23 becomes a set value based on the input voltage, and the DC / DC converter 23 The switching element of the switching circuit 23a is controlled so that the input current is equal to the current command value. The power receiving side control device 23c includes an antenna 23d and has a function of performing wireless communication with the power transmission side control device 11c using a short-range wireless communication standard such as Bluetooth (registered trademark). .

 The power receiving side control device 23c has a function of transmitting the current command value calculated as described above to the power transmission side control device 11c via the antenna 23d, and the power transmission side control device 11c performs the reception side control via the antenna 11d. Based on the current command value received from the device 23c, the amplifier 11 has a function of controlling the degree of AC power amplification so that the input power of the DC / DC converter 23 is constant.

Next, the operation of the power transmission system A according to this embodiment configured as described above will be described in detail.
First, when the electric vehicle 200 stops near the installation position of the charging facility 100, the power transmission side control device 11c of the power transmission device 10 starts control of the switching elements constituting the inverter 11b, and the alternating current output from the inverter 11b. The voltage and frequency of power are controlled to predetermined values. Here, the power transmission side control device 11c performs control so that AC power having a frequency that matches the resonance frequency of the power transmission side resonator 12 is output from the inverter 11b.

 Thereby, on the power transmission device 10 side, AC power having a voltage and frequency suitable for power transmission by the magnetic field resonance method is output from the amplifier 11 (inverter 11b) to the power transmission resonator 12, and the power transmission resonator 12 and the power reception resonance. Magnetic field resonance occurs with the vessel 21. When the magnetic field resonance occurs, the AC power output from the amplifier 11 is transmitted (wireless power transmission) from the power transmission side resonator 12 to the power reception side resonator 21. On the power receiving device 20 side, the AC power received by the power receiving resonator 21 is converted into DC power by the rectifier 22 and input to the DC / DC converter 23.

The power receiving side control device 23c of the power receiving device 20 monitors the input voltage of the DC / DC converter 23 (input voltage of the switching circuit 23a), and the input impedance of the DC / DC converter 23 becomes a set value based on the input voltage. Calculate the current command value. For example, when the input voltage of the DC / DC converter 23 is V, the input impedance setting value is Z (for example, 45Ω), and the current command value is I, the current command value I can be calculated by the following equation (1).
I = V / Z (1)

  Then, the power receiving side control device 23c starts controlling the switching elements of the switching circuit 23a so that the input current of the DC / DC converter 23 (the input current of the switching circuit 23a) matches the current command value I. It is desirable to monitor the input current of the DC / DC converter 23 and feedback control the switching element of the switching circuit 23a so that the input current matches the current command value I.

  As a result, the DC / DC converter 23 starts operating, an input current that matches the current command value I flows, the input impedance of the DC / DC converter 23 is held at the set value Z, and the DC / DC converter 23 The battery 40 starts to be charged by the output DC power.

 Thereafter, the power receiving side control device 23c monitors the input voltage V of the DC / DC converter 23 at a constant control cycle until the charging of the battery 40 is completed, and the DC / DC converter 23 is based on the input voltage V each time. The current command value I at which the input impedance becomes the set value Z is calculated, and the switching circuit 23a is controlled so that the input current of the DC / DC converter 23 matches the current command value I.

 FIG. 2A is a schematic diagram showing profiles of the input voltage, input current, and input impedance of the DC / DC converter 23 during the charging period of the battery 40, that is, during the operation period of the DC / DC converter 23. FIG. 2B is a schematic diagram showing a profile of input voltage, input current, and input impedance of a DC / DC converter in the prior art.

 As shown in these figures, in the conventional technique, the input impedance of the DC / DC converter fluctuates during the charging period, whereas in the present embodiment, during the charging period (including the transition time at the start and stop of charging). ), The input impedance of the DC / DC converter 23 is maintained constant (set value Z), and the input impedance is always matched.

  Further, the input power W of the DC / DC converter 23 is expressed as input voltage V × input current I (= current command value). However, depending on the value of the current command value I, the input power W is not necessarily DC / DC. It does not necessarily match the standard value of the converter 23. In order to maintain good power conversion efficiency in the DC / DC converter 23, it is desirable that the input power W of the DC / DC converter 23 be as close to the standard value as possible.

  Therefore, in the present embodiment, the power transmission side control device 11c controls the amplification degree of the AC power by the amplifier 11 so that the input power W of the DC / DC converter 23 is constant (standard value). That is, the power transmission side control device 11c controls the voltage of the AC power output from the inverter 11b so that the input power W of the DC / DC converter 23 becomes a standard value. As a result, the input voltage V of the DC / DC converter 23 changes, and the input power W of the DC / DC converter 23 matches the standard value.

 As described above, according to the present embodiment, during the charging period of the battery 40, that is, during the operation period of the DC / DC converter 23 (when the output starts (when charging starts) and when the output stops (when charging stops)) In other words, the input impedance of the DC / DC converter 23 provided on the power receiving device 20 side is kept constant, so that the input impedance is always matched, and the power transmission efficiency is higher than that of the conventional technology. Improvements can be realized and damage to the components can be avoided. Note that, according to the present embodiment, the input impedance of the DC / DC converter 23 can be kept constant even when a constant change of the LC circuit occurs due to a temperature change in a steady state.

In addition, this invention is not limited to the said embodiment, The following modifications are mentioned.
(1) In the above embodiment, the non-contact power feeding type power transmission system A that wirelessly transmits the charging power (AC power) from the charging facility 100 to the electric vehicle 200 via the spatial transmission path 300 is illustrated. However, the present invention is not limited to this. For example, the present invention can be applied to a power transmission system in which power is transmitted to a mobile terminal by a non-contact power feeding method and a battery of the mobile terminal is charged.

(2) In the above embodiment, the case where power transmission is performed between the power transmission device 10 and the power reception device 20 using the magnetic field resonance method is illustrated, but the present invention is not limited to this, and other than the magnetic field resonance method. A non-contact power feeding method (for example, an electromagnetic induction method) may be used.

(3) In the above embodiment, the non-contact power feeding type power transmission system A that wirelessly transmits AC power between the power transmission device 10 and the power reception device 20 via the spatial transmission path 300 is illustrated, but the present invention is not limited to this. However, the present invention can be applied to a power transmission system in which AC power is wired and transmitted between a power transmission device and a power reception device via a wired transmission path.

(4) The amplifier 11 may be provided with a PFC as necessary. Moreover, although the case where the power supply provided in the charging equipment 100 side is the alternating current power supply 30 was illustrated in the said embodiment, when this power supply is a DC power supply, that is, DC power is supplied to the power transmission apparatus 10 from a power supply. In this case, the rectifier circuit 11a may be deleted from the amplifier 11. Further, a system configuration in which AC power or DC power is supplied from other than the power source may be employed. Moreover, it is good also as a structure in which bidirectional | two-way electric power transmission is possible between the power transmission apparatus 10 and the power receiving apparatus 20. FIG.

  DESCRIPTION OF SYMBOLS A ... Electric power transmission system, 10 ... Power transmission apparatus, 11 ... Amplifier (alternating current converter), 11c ... Power transmission side control apparatus, 12 ... Power transmission side resonator, 20 ... Power reception apparatus, 21 ... Power reception side resonator, 22 ... Rectifier DESCRIPTION OF SYMBOLS 23 ... DC / DC converter (DC converter), 23c ... Power-receiving side control apparatus, 30 ... AC power supply, 40 ... Battery, 100 ... Charging equipment, 200 ... Electric vehicle, 300 ... Spatial transmission line

Claims (11)

In a power transmission system including a power transmission device that converts AC power or DC power supplied into AC power and transmits the power via a transmission line, and a power reception device that receives the AC power via the transmission line,
The power receiving device is:
A rectifier that rectifies the AC power received via the transmission line and converts the AC power into DC power;
A DC converter that performs DC conversion of DC power output from the rectifier;
A current command value at which an input impedance of the DC converter becomes a set value is calculated based on an input voltage of the DC converter, and the DC converter is set so that an input current of the DC converter matches the current command value. A power receiving side control device for controlling
With
The power transmission device is:
An AC converter for converting the supplied AC power or DC power into AC power;
A power transmission side control device for controlling the amplification degree of the AC power by the AC converter;
With
The power receiving side control device transmits the current command value to the power transmission side control device,
The power transmission side control device controls the amplification degree of the AC power by the AC converter so that the input power of the DC converter becomes constant based on the current command value received from the power reception side control device. A power transmission system characterized by that. The power transmission device includes a power transmission side resonator for wirelessly transmitting the AC power by a magnetic field resonance method through a spatial transmission path as the transmission path,
2. The power transmission system according to claim 1, wherein the power reception device includes a power reception side resonator for wirelessly receiving the AC power from the power transmission side resonator via the spatial transmission path.   The power transmission system according to claim 1, wherein bidirectional power transmission is possible between the power transmission device and the power reception device. An amplifier that controls the power supplied from a predetermined power source and outputs AC power;
A resonator that transmits the AC power input from the amplifier to a power receiving device;
An antenna for receiving the current command value transmitted from the power receiving device;
The antenna based on the current command value received, have a, a control device for controlling the amplification degree of the AC power the amplifier output,
The control device controls the amplification degree of the AC power output by the amplifier based on the current command value so that the input power to the DC power converter provided in the power receiving device is constant. A power transmission device of a power transmission system. The power transmission device of the power transmission system according to claim 4, wherein the resonator transmits the AC power input from the amplifier to the power receiving device by a magnetic field resonance method . The charging equipment installed in the parking lot characterized by including the power transmission apparatus of the electric power transmission system described in Claim 4. A resonator that receives AC power transmitted from the power transmission device;
A rectifier connected to the resonator and converting AC power to DC power;
A converter for performing a direct current conversion of the direct current power and outputting;
A current command value at which the input impedance of the converter becomes a predetermined value is calculated based on an input voltage input to the converter, and the converter is controlled based on the current command value. A control device having a function of transmitting to the power transmission device;
A power receiving device for a power transmission system. The power receiving device of the power transmission system according to claim 7, further comprising an antenna that transmits the current command value output from the control device toward the power transmitting device. The power receiving system according to claim 7, wherein the control device has a function of transmitting the current command value to the power transmitting device using a short-range wireless communication standard. The power receiving device of the power transmission system according to claim 7, wherein the resonator receives AC power from the power transmitting device by a magnetic field resonance method. A power receiving device of the power transmission system according to claim 7,
A battery connected to the converter;
An electric vehicle comprising:

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