JP2013215065A - Power transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent damage to a DC converter disposed at the back of a rectifier on a reception device side.SOLUTION: A transmission device includes: an AC converter for AC-converting supplied AC power or DC power; a transmitting side resonance coil for wirelessly transmitting AC power; and a transmitting side control device. The reception device includes: a receiving side resonance coil for wirelessly receiving the AC power; the rectifier for converting the received AC power to DC power; the DC converter for DC-converting the DC power output from the rectifier; a receiving side control device; and a power circuit for generating a control supply voltage from the output voltage of the rectifier to feed the receiving side control device. The receiving side control device measures and transmits to the transmitting side control device the output voltage of the rectifier when started upon the input of the control supply voltage, and the transmitting side control device controls the AC converter such that the output voltage of the rectifier becomes a value suitable as an input voltage to the DC converter, on the basis of the measured result of the output voltage of the rectifier.

Description

 The present invention relates to a power transmission system.

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

  The power transmission system of the non-contact power feeding method (particularly the magnetic field resonance method) amplifies the AC power supplied from the AC power source with an amplifier, and then receives power by the power transmitting resonance coil and the power transmitting resonance coil. The AC power is converted into DC power by a rectifier, and further converted into desired DC power (for example, battery charging power) by a DC converter (DC / DC converter). In some cases, on the power receiving device side, a rectifier and a DC converter are integrally incorporated to form a charger (AC / DC converter).

  When power transmission from the power transmission device to the power reception device is started, if the impedance matching is not achieved (the DC converter is not operating) and the amplifier output voltage on the power transmission device side is increased, the rectifier on the power reception device side The output voltage is higher than the amplifier output voltage due to the influence of the Q value of the LC resonance circuit. Since such a high voltage is applied to the DC converter after the rectifier relatively abruptly (several seconds or less), there is a possibility that the breakdown voltage exceeds the withstand voltage of the DC converter.

  In addition, a high voltage is applied to the DC converter when the power supply (control power supply) of a control device such as a microcomputer for controlling the DC converter is not turned on or when the startup of the control device is unstable. Unexpected troubles such as DC converter runaway may occur. In order to avoid such a runaway DC converter, it is necessary to separately prepare a power storage device such as a battery for supplying control power and a capacitor, which causes an increase in cost.

 The present invention has been made in view of the above-described circumstances, and provides a power transmission system capable of preventing damage to a DC converter provided in a rear stage of a rectifier on the power receiving device side without separately preparing a power storage device. 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 including a power receiving device that receives the AC power via the transmission path, the power transmission device includes an AC converter that performs AC conversion of the supplied AC power or DC power, and the AC conversion. A power transmission side resonance coil for wirelessly transmitting AC power obtained from a power supply by a magnetic field resonance method, and a power transmission side control device for controlling the AC converter, wherein the power reception device includes the power transmission side resonance coil from the power transmission side resonance coil. A power receiving resonance coil for wirelessly receiving AC power, a rectifier that converts the AC power received by the power receiving resonance coil into DC power, and output from the rectifier A direct current converter that performs direct current power conversion, a power reception side control device that controls the direct current converter, a power supply circuit that generates a control power supply voltage from the output voltage of the rectifier and outputs the control power supply voltage to the power reception side control device; The power receiving side control device is activated by receiving the control power supply voltage, and then measures the output voltage of the rectifier and transmits the measurement result to the power transmission side control device. The AC converter is controlled so that the output voltage of the rectifier gradually increases during the period from the start of transmission of the AC power until the measurement result of the output voltage of the rectifier is received, and the measurement result is received. Thereafter, a means for controlling the AC converter so that the output voltage of the rectifier becomes a suitable value as the input voltage of the DC converter based on the measurement result is adopted.

 In the present invention, as the second solving means relating to the power transmission system, in the first solving means, the power receiving side control device is configured such that the output voltage of the rectifier is a value suitable as the input voltage of the DC converter. In such a case, a means for starting the control of the DC converter is adopted.

 According to the present invention, at the start of power transmission, in a state where impedance matching is not achieved (a state where the power converter is not operating), the power converter is damaged by gradually increasing the output voltage of the rectifier. Can be prevented. In addition, by setting the output voltage of the rectifier to a value suitable as the input voltage of the DC converter after the power-receiving-side control device has started up reliably, unexpected troubles such as runaway of the DC converter can be prevented. . Furthermore, it is not necessary to prepare a separate power storage device for preventing the DC converter from running out of control, and an increase in cost can be suppressed.

It is a schematic block diagram of the electric power transmission system A which concerns on this embodiment. Timing chart showing temporal correspondence between output voltage Vr of rectifier 22 (input voltage of DC / DC converter 23), control power supply voltage Vc (output voltage of regulator 23c), and operating state of power receiving side control device 23d. It is.

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 resonance coil 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 resonance coil 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 resonance coil 12 and the power transmission side control apparatus 11c which performs PWM (Pulse Width Modulation) control of 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 PWM-controlling the switching elements constituting the inverter 11b (that is, controlling the duty ratio of the switching elements). . The power transmission side control device 11c has a function of performing wireless communication with a power reception side control device 23d (described later) using a short-range wireless communication standard such as Bluetooth (registered trademark) via the antenna 11d.

 The power transmission side resonance coil 12 is a helical coil wound in a spiral shape for wirelessly transmitting AC power input from the amplifier 11 through the spatial transmission path 300 by a magnetic field resonance method. The power transmission resonance coil 12 forms an LC resonance circuit together with a capacitor (not shown). Note that the parasitic capacitance of the helical coil may be used as a capacitor for configuring the LC resonance circuit, or a capacitor element may be provided 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 resonance coil 21, a rectifier 22, and a DC / DC converter 23.

 The power reception side resonance coil 21 is a helical coil wound in a spiral shape for wirelessly receiving AC power from the power transmission side resonance coil 12 via the spatial transmission path 300. The power receiving resonance coil 21 also forms an LC resonance circuit together with a capacitor (not shown). If circuit constants are set so that both LC resonance circuits of the power transmission device 10 and the power reception device 20 are equal, magnetic field resonance can be generated between the power transmission side resonance coil 12 and the power reception side resonance coil 21.

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

 The DC / DC converter 23 performs direct current / direct current conversion of the direct current power input from the rectifier 22 and outputs the obtained direct current power to the battery 40 as charging direct current power. Specifically, the DC / DC converter 23 includes a step-down 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 for generating a voltage, a regulator (power supply circuit) 23c for generating a control power supply voltage Vc from the output voltage Vr of the rectifier 22 and outputting it to the power receiving side control device 23d, and a step-down switching circuit via the gate drive circuit 23b And a power receiving side control device 23d that performs PWM control of the switching element 23a.

 The power receiving side control device 23d includes an antenna 23e 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. After receiving the control power supply voltage Vc from the regulator 23c and starting up, the power receiving side control device 23d measures the output voltage Vr of the rectifier 22 and transmits the measurement result to the power transmission side control device 11c. On the other hand, the power transmission side control device 11c is configured so that the output voltage of the rectifier 22 gradually increases during the period from the start of AC power transmission until the measurement result of the output voltage Vr of the rectifier 22 is received. After receiving the measurement result, the amplifier 11 is controlled so that the output voltage Vr of the rectifier 22 becomes a value suitable as the input voltage of the DC / DC converter 23 based on the measurement result.

 Next, the operation of the power transmission system A according to the present embodiment configured as described above will be described in detail with reference to FIG. FIG. 2 shows a temporal correspondence relationship between the output voltage Vr of the rectifier 22 (the input voltage of the DC / DC converter 23), the control power supply voltage Vc (the output voltage of the regulator 23c), and the operating state of the power receiving side control device 23d. It is a timing chart which shows.

 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 gradually increases the output voltage Vr of the rectifier 22 from the AC power transmission start time t1 shown in FIG. PWM control of the amplifier 11 is started so as to rise. Thereby, on the power transmission device 10 side, AC power corresponding to the PWM control by the power transmission side control device 11c is output from the amplifier 11 to the power transmission side resonance coil 12, and between the power transmission side resonance coil 12 and the power reception side resonance coil 21. Magnetic field resonance occurs.

 When magnetic field resonance occurs, AC power output from the amplifier 11 is transmitted (wireless power transmission) from the power transmission resonance coil 12 to the power reception resonance coil 21. Then, on the power receiving device 20 side, the AC power received by the power receiving resonance coil 21 is converted into DC power by the rectifier 22 and input to the DC / DC converter 23. Here, as shown in FIG. 2, the output voltage Vr of the rectifier 22 gradually increases with time from the transmission start time t1.

 In FIG. 2, the control power supply voltage Vc output from the regulator 23 is 0 V (ground level) during the period from the transmission start time t1 to the time t2 when the output voltage Vr of the rectifier 22 rises to the operable voltage Vr1 of the regulator 23c. Thus, the power receiving side control device 23d is in an operation stop state. When the output voltage Vr of the rectifier 22 rises to the operable voltage Vr1 of the regulator 23c at time t2, the regulator 23 starts operating at this time t2, and the control power supply voltage Vc is used as the power supply voltage of the power receiving side control device 23d. Stand up to the required 5V.

 When the control power supply voltage Vc of 5V is output from the regulator 23 to the power receiving side control device 23d at time t2, the power receiving side control device 23d starts from the operation stop state, and after time t2, the rectifier 22 has a constant control cycle. The output voltage Vr is measured and the measurement result is transmitted to the power transmission side control device 11c. On the other hand, when the power transmission side control device 11c receives the measurement result of the output voltage Vr of the rectifier 22 from the power reception side control device 23d, the output voltage Vr of the rectifier 22 is used as the input voltage of the DC / DC converter 23 based on the measurement result. The amplifier 11 is PWM-controlled so as to have an appropriate value (operable voltage Vr2 of the DC / DC converter 23).

 Thereby, as shown in FIG. 2, the output voltage Vr of the rectifier 22 increases from the time t2 toward the operable voltage Vr2 of the DC / DC converter 23. When the output voltage Vr of the rectifier 22 reaches the operable voltage Vr2 of the DC / DC converter 23 at time t3, the power receiving side control device 23d performs control of the DC / DC converter 23, that is, charging control of the battery 40. Then, the fact that the output voltage Vr of the rectifier 22 has reached the operable voltage Vr2 of the DC / DC converter 23 is transmitted to the power transmission side control device 11c. Upon receiving this notification, the power transmission side control device 11c performs PWM control on the amplifier 11 so that the output voltage Vr of the rectifier 22 becomes constant at Vr2.

 As described above, according to the present embodiment, the output voltage Vr of the rectifier 22 is gradually increased in a state where impedance matching is not achieved (a state where the DC / DC converter 23 is not operating) at the start of power transmission. By raising it, it is possible to prevent damage to the devices and parts of the entire system including the DC / DC converter 23. Further, after the power-receiving-side control device 23d is reliably started, the output voltage Vr of the rectifier 22 is increased to the operable voltage Vr2 of the DC / DC converter 23, so that an unexpected runaway of the DC / DC converter 23 is caused. Trouble can be prevented. Furthermore, it is not necessary to prepare a separate power storage device for preventing the DC / DC converter 23 from running out of control, and an increase in cost can be suppressed.

In addition, this invention is not limited to the said embodiment, The following modifications are mentioned.
For example, 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 described. 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. Further, the present invention is not limited to the DC / DC converter 23 but can be applied to other secondary devices. 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.

  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 resonance coil, 20 ... Power reception apparatus, 21 ... Power reception side resonance coil, 22 ... Rectifier 23 ... DC / DC converter (DC converter), 23c ... regulator (power supply circuit), 23d ... power receiving side control device, 30 ... AC power supply, 40 ... battery, 100 ... charging equipment, 200 ... electric vehicle, 300 ... spatial transmission Road

Claims (2)

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 transmission device is:
An AC converter for performing AC conversion of the supplied AC power or DC power;
A power transmission side resonance coil for wirelessly transmitting AC power obtained from the AC converter by a magnetic resonance method,
A power transmission side control device for controlling the AC converter,
The power receiving device is:
A power receiving side resonance coil for wirelessly receiving the AC power from the power transmission side resonance coil;
A rectifier that converts the AC power received by the power-receiving-side resonance coil into DC power;
A DC converter that performs DC conversion of DC power output from the rectifier;
A power receiving side control device for controlling the DC converter;
A power supply circuit that generates a control power supply voltage from the output voltage of the rectifier and outputs the control power supply voltage to the power receiving side control device, and
The power receiving side control device, after the control power supply voltage is input and started, measures the output voltage of the rectifier and transmits the measurement result to the power transmission side control device,
The power transmission side control device controls the AC converter so that the output voltage of the rectifier gradually increases during a period from the start of transmission of the AC power until the measurement result of the output voltage of the rectifier is received, After receiving the measurement result, the AC converter is controlled based on the measurement result so that the output voltage of the rectifier becomes a value suitable as the input voltage of the DC converter. .   The power receiving side control device starts control of the DC converter when an output voltage of the rectifier becomes a value suitable as an input voltage of the DC converter. Power transmission system.

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