JP2016021827A - Power feeding system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power feeding system where reduction of power factor caused by positional deviation is improved.SOLUTION: A feeding control part 24 detects power factor of a high frequency power source 40 from AC current and AC voltage detected by a measuring device 23 to transmit the detected power factor to a power reception device 30. A power reception control part 33 of the power reception device 30 adjusts electrostatic capacitance of a power-receiving capacitor 31B according to the detected power factor at a power feeding device 20 side to adjust reactance of the power reception device 30.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power feeding system, and more particularly to a power feeding system that performs non-contact power feeding.

  In recent years, attention has been focused on wireless power feeding without using a power cord or a power transmission cable as a power feeding system for feeding power to a battery mounted on a hybrid vehicle or an electric vehicle. One of the wireless power feeding techniques is known as a magnetic resonance type.

  This magnetic field resonance type power supply system includes a pair of resonance circuits including a coil and a capacitor. One of the pair of resonance circuits is installed on the ground of the power supply equipment, the other is mounted on the vehicle, and resonates when the coils are in the opposite positions, and the resonance circuit installed on the ground of the power supply equipment ( Electric power is supplied in a non-contact manner from a power supply resonance circuit) to a resonance circuit (power reception resonance circuit) mounted on the vehicle.

  In the power feeding system described above, the values of the coil and the capacitor of the power feeding resonance circuit and the power receiving resonance circuit are adjusted so as to resonate when the coils are at the directly facing positions. However, it is difficult to stop the vehicle exactly at the directly facing position, and displacement often occurs. When this misalignment occurs, impedance matching between the power supply resonance circuit and the power reception resonance circuit cannot be achieved, and transmission efficiency between the power supply resonance circuit and the reception resonance circuit decreases.

  Therefore, it is considered to obtain the above transmission efficiency from the amount of reflection from the coil of the power receiving resonance circuit and adjust the values of the coil and capacitor of the resonance circuit to prevent a decrease in transmission efficiency due to positional deviation (patent) References 1, 2).

  By the way, when the position shift occurs, not only the transmission efficiency between the power supply resonance circuit and the power reception resonance circuit is reduced, but also the reactance component seen from the power source supplying AC power to the power supply resonance circuit is changed, and the power factor is reduced. End up. FIG. 5 is a graph showing the relationship between the reactance of the power receiving resonance circuit and the power factor of the power source that supplies AC power to the power supply resonance circuit. In the figure, the solid line shows the relationship between the reactance of the power receiving resonant circuit and the power factor of the power source when no positional deviation occurs, and the dotted line shows the reactance of the power receiving resonant circuit and the power factor of the power source when the positional deviation occurs. The relationship is shown.

  As shown in the figure, when there is no position shift, the reactance component viewed from the power supply side is also 0 near the reactance 0 of the power receiving resonance circuit, so the power factor becomes 100%. On the other hand, when the position shift occurs, the reactance component seen from the power source side increases and the power factor drops to 85% even when the reactance of the power receiving resonance circuit is near zero. In order to keep the effective power transmitted from the power supply resonance circuit constant, the amount of current on the power source side must be increased as the power factor decreases.

  For example, as shown in Table 1, let us consider a case where the power factor PFin is reduced from 0.990 to 0.89, 0.488 due to the position shift. When the power factor PFin is 0.990, 3 Kw can be transmitted if the voltage effective value Vrms = 271.1 V, the current effective value Irms = 11.2 A, and the apparent power 3029 W are supplied from the power source. On the other hand, when the power factor PFin is reduced to 0.89, to transmit 3 Kw, it is necessary to supply the voltage effective value Vrms = 171.1 V, the current effective value Irms = 19.8 A, and the apparent power 3386 W from the power source. There is. When the power factor PFin decreases to 0.488, to transmit 3 Kw, it is necessary to supply a voltage effective value Vrms = 166.3 V, a current effective value Irms = 37.0 A, and an apparent power 6153 W from the power source. When the current of the power supply increases in this way, heat generation in the power supply components increases, and a cooling device is required.

  However, as is apparent from a comparison of FIGS. 5 and 6, the transmission efficiency has a smaller amount of change in accordance with the change in reactance than the power factor. More specifically, as shown in FIG. 6, when the positional deviation occurs, the transmission efficiency hardly fluctuates at a value slightly higher than 90% in a wide range of reactance of −4 to 0. For this reason, when the values of the capacitors and the coils are adjusted based on the transmission efficiency as in the conventional power supply system, the reactance does not change regardless of whether the reactance is −4 or 0, and the reactance may be adjusted to 0. There is. However, when the reactance is adjusted to a range of 0, the power factor is reduced to 80%. That is, the conventional power feeding system has a problem that although the transmission efficiency can be improved, it cannot be improved until the power factor is lowered.

JP2012-135108A JP2013-13274A

  Then, this invention makes it a subject to provide the electric power feeding system which improved the fall of the power factor which arises by position shift.

  According to a first aspect of the present invention, a power receiving unit having a power receiving coil that receives power in a contactless manner and a power receiving capacitor connected to the power receiving coil, and AC power supplied from an AC power source is fed to the power receiving coil in a contactless manner. A power supply unit having a power supply coil and a power supply capacitor connected to the power supply coil, and detecting a power factor of the AC power source, and according to the power factor detected by the power factor detection means And an adjusting means for adjusting reactance of the power feeding unit or the power receiving unit.

  The invention according to claim 2 is characterized in that the power receiving capacitor or the power feeding capacitor is formed of a variable capacitor, and the adjusting means adjusts the reactance by adjusting a capacitance of the variable capacitor. It exists in the electric power feeding system of Claim 1.

  The invention according to claim 3 is characterized in that the variable capacitor is composed of a plurality of capacitors and a switch element provided between the capacitors, and the capacitance changes depending on the on / off state of the switch element. It exists in the electric power feeding system of Claim 2.

  As described above, according to the first aspect of the present invention, it is possible to improve the power factor reduction caused by the displacement.

  According to the invention described in claim 2, the reactance can be easily adjusted.

  According to the invention described in claim 3, the variable range of the capacitance can be freely set.

It is a figure which shows schematic structure of the electric power feeding system of one Embodiment of this invention. It is a figure explaining arrangement | positioning of the electric power feeder and power receiving apparatus with which the electric power feeding system of FIG. 1 is provided. It is a circuit diagram which shows the detail of the receiving capacitor shown in FIG. It is a flowchart which shows the process sequence of the control part shown in FIG. It is a graph which shows the relationship between the reactance of a receiving resonant circuit, and the power factor of the power supply which supplies alternating current power to a electric power feeding resonant circuit. It is a graph which shows the relationship between the reactance of a power receiving resonance circuit, and the transmission efficiency between a power feeding resonance circuit and a power receiving resonance circuit.

  Hereinafter, a power supply system according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a diagram illustrating a schematic configuration of a power feeding system according to an embodiment of the present invention. FIG. 2 is a diagram illustrating the arrangement of the power feeding device and the power receiving device included in the power feeding system of FIG. 1. The power supply system of this embodiment supplies electric power to the vehicle from the ground side in a non-contact manner using a magnetic field resonance type.

  As shown in FIG. 1, the power feeding system 1 includes a power feeding device 20 as a power feeding unit arranged on the ground G (shown in FIG. 2) and a power receiving unit as a power receiving unit arranged in a vehicle V (shown in FIG. 2). Device 30. As shown in FIG. 2, the vehicle V includes a drive unit DRV having an engine and a motor, and a power battery BATT that supplies power to the motor.

  As shown in FIG. 1, the power supply device 20 is a device that supplies AC power from a high-frequency power source 40 to a power receiving device 30 described later in a non-contact manner. For example, the high frequency power supply 40 generates high frequency power from a commercial power supply and supplies the high frequency power to the power feeding device 20. The power supply device 20 includes a power supply unit 21, a matching unit 22, a measuring device 23, a power supply control unit 24, and a power supply communication unit 25.

  The power supply unit 21 is installed on the ground G as shown in FIG. The power supply unit 21 may be embedded in the ground G. In addition, as shown in FIG. 1, the power supply unit 21 includes a power supply coil 21 </ b> A and a power supply capacitor 21 </ b> B.

  The feeding coil 21A and the feeding capacitor 21B are connected in series to form a resonance circuit that resonates at a predetermined resonance frequency. In the present embodiment, the feeding coil 21A and the feeding capacitor 21B are connected in series, but may be connected in parallel.

  The matching unit 22 is a circuit for matching the impedance between the high-frequency power source 40 and a resonance circuit including the feeding coil 21A and the feeding capacitor 21B.

  The measuring device 23 is for detecting the power factor of the high frequency power supply 40, measures the alternating current and the alternating voltage supplied from the high frequency power supply 40, and supplies them to a power supply control unit 24 described later.

  The power supply control unit 24 includes a known microcomputer having a ROM, a RAM, and a CPU, and controls the entire power supply apparatus 20. The power supply control unit 24 performs on / off control of the high-frequency power supply 40 in response to a request for power transmission. Further, the power supply control unit 24 obtains the phase difference between the alternating current and the alternating voltage measured by the measuring instrument 23 and detects the obtained phase difference as the power factor of the high frequency power supply 40. As is clear from this, the measuring instrument 23 and the power supply control unit 24 constitute a power factor detection means.

  The power supply communication unit 25 is for performing wireless communication with a power receiving device 30 described later, and is controlled by the power supply control unit 24. The power supply control unit 24 controls the power supply communication unit 25 to transmit the detected power factor to the power receiving device 30.

  The power reception device 30 includes a power reception unit 31, a rectifier 32, a power reception control unit 33, and a power reception communication unit 34. The power receiving unit 31 is attached to the lower surface of the vehicle V as shown in FIG. As shown in FIG. 1, the power receiving unit 31 includes a power receiving coil 31A and a power receiving capacitor 31B.

  The power receiving coil 31 </ b> A and the power receiving capacitor 31 </ b> B are connected in series to form a resonance circuit that resonates at the same resonance frequency as that of the power supply unit 21. In the present embodiment, the power receiving coil 31A and the power receiving capacitor 31B are connected in series, but may be connected in parallel.

  The power receiving capacitor 31B is composed of a variable capacitor having a variable capacitance. In the present embodiment, as shown in FIG. 3, the power receiving capacitor 31B includes a plurality of capacitors C11 to C16, C21 to C26, and switches SA1 and SA2 as switch elements provided between the capacitors C14 to C16 and C24 to C26. , SB1, SB2, SY1, and SY2. In the power receiving capacitor 31B, the number of capacitors connected to the power receiving unit 31 is switched depending on the on / off state of the switches SA1, SA2, SB1, SB2, SY1, and SY2, and the capacitance changes.

  More specifically, the capacitors C11 to C16 are connected in series with each other. The capacitors C21 to C26 are connected in series with each other. Capacitors C11 to C16 and capacitors C21 to C26 are connected in parallel. The switches SA1 and SA2 are provided between the connection point of the capacitors C15 and C16 and the connection point of the capacitors C25 and C26. The switches SB1 and SB2 are provided between the connection point of the capacitors C14 and C15 and the connection point of the capacitors C24 and C25. The switch SY1 is provided between the connection point of the capacitors C16 and C26 and the connection point of the switches SA1 and SA2. The switch SY2 is provided between the connection point of the switches SA1 and SA2 and the connection point of the switches SB1 and SB2.

  According to the above configuration, when the switches SB1, SB2, SY1, and SY2 are turned on, the number of capacitors is minimized and the capacitance of the receiving capacitor 31B is maximized. Further, when all of the switches SA1, SA2, SB1, SB2, SY1, and SY2 are turned off, the number of capacitors is maximized and the capacitance of the receiving capacitor 31B is minimized.

  The rectifier 32 converts the high frequency power received by the power receiving unit 31 into DC power. For example, a load L such as a charging unit used for charging the power battery BATT mounted on the vehicle V is connected to the rectifier 32.

  The power reception control unit 33 includes a well-known microcomputer having a ROM, a RAM, and a CPU, and controls the entire power reception device 30. The power reception control unit 33 functions as an adjustment unit, and adjusts the capacitance of the power reception capacitor 31 </ b> B according to the power factor transmitted from the power supply device 20.

  The power reception communication unit 34 is for performing wireless communication with the power supply communication unit 25 of the power supply apparatus 20, and is controlled by the power reception control unit 33. The power reception control unit 33 controls the power reception communication unit 34 to transmit a power transmission request to the power supply device 20 and to receive a power factor transmitted from the power supply device 20.

  In the power supply system 1 described above, when a charging operation of the power battery BATT of the parked vehicle V is performed in the power supply facility, the power reception control unit 33 controls the power reception communication unit 34 to make a power transmission request to the power supply device 20. Send. When the power supply control unit 24 of the power supply apparatus 20 receives the power transmission request, the power supply control unit 24 turns on the high-frequency power supply 40 to generate high-frequency power. When the high-frequency power is supplied to the power feeding device 20, the power feeding unit 21 and the power receiving unit 31 perform magnetic field resonance, and power is transmitted from the power feeding unit 21 to the power receiving unit 31 in a contactless manner. The high frequency power received by the power receiving unit 31 is converted into DC power by the rectifier 32 and supplied to the charging unit of the vehicle V, and the power battery BATT is charged by the charging unit.

  In the power feeding system 1, in order to improve the power factor at the time of transmission of the above-described high frequency power, the power feeding control unit 24 sequentially detects and detects the power factor from the alternating current and the alternating voltage measured by the measuring device 23. The power factor is transmitted to the power receiving device 30. Further, the power reception control unit 33 performs a power factor improvement process shown in FIG.

  Hereinafter, the power factor improvement process performed by the power reception control unit 33 will be described. First, the power reception control unit 33 receives and monitors the power factor from the power feeding device 20 (step S1). Next, the power reception control unit 33 determines whether or not the power factor is greater than or equal to a reference value (step S2). If the power feeding coil 21A and the power receiving coil 31A are not misaligned, the power factor is equal to or higher than the reference value. Therefore, the power receiving control unit 33 determines Y in step S2, and returns to step S1 again.

On the other hand, when the power supply coil 21A and the power receiving coil 31A are misaligned, the reactance X on the load L side as viewed from the high frequency power supply 40 increases, and the power factor decreases. By the way, the reactance X includes an inductive reactance XL on the load L side (hereinafter abbreviated as “XL”) and a capacitive reactance XC (hereinafter referred to as “XC”) as seen from the high frequency power supply 40, as shown in the following equation (1). (Abbreviation).
X = XL-XC (1)

  XL is a value that depends on an inductance component on the load L side of the high frequency power supply 40, and XC is a value that depends on a capacitance (capacitance) component on the load L side of the high frequency power supply 40. Here, the fact that the power factor decreases and the reactance X increases means that XL and XC are not equal, and one of them is increased.

  Therefore, when the power factor is lower than the reference value (N in step S2), first, the power reception control unit 33 increases the capacitance of the power receiving capacitor 31B by a certain amount (step S3), and whether or not the power factor has increased. Is determined (step S4). If XC <XL due to misalignment, in step S3 XC increases, reactance X decreases, and the power factor increases. In this case, the power reception control unit 33 determines that the power factor has increased (Y in step S4), and increases the capacitance of the power receiving capacitor 31B (step S5) until the power factor exceeds the reference value (Y in step S5). S3) is repeated.

  On the other hand, when XC> XL due to the positional deviation, XC increases in step S3, the reactance X further increases, and the power factor decreases. In this case, the power reception control unit 33 determines that the power factor has decreased (N in step S4), and then decreases the capacitance of the power reception capacitor 31B by a certain amount (step S6). As a result, XC decreases, reactance X decreases, and the power factor increases. The power reception control unit 33 repeats the decrease in the capacitance of the power reception capacitor 31B (step S6) until the power factor becomes equal to or higher than the reference value (Y in step S7).

  According to the above-described embodiment, the power supply control unit 24 detects the power factor of the high-frequency power source 40 from the AC power source and the AC voltage detected by the measuring device 23 and transmits the power factor to the power receiving device 30. The power reception control unit 33 of the power receiving device 30 adjusts the reactance of the power receiving device 30 by adjusting the capacitance of the power receiving capacitor 31B according to the power factor detected on the power feeding device 20 side. Thereby, the fall of the power factor which arises by position shift can be improved.

  Further, according to the above-described embodiment, the reactance is adjusted by adjusting the capacitance of the power receiving capacitor 31B. Therefore, the reactance can be easily adjusted.

  Further, according to the above-described embodiment, the power receiving capacitor 31B includes the plurality of capacitors C11 to C16, C21 to C26 and the switches SA1, SA2, SB1, SB2, SY1, and SY2, and the switches SA1, SA2, and SB1. , SB2, SY1, and SY2 were changed in electrostatic capacity. For example, a variable capacitor having a variable capacitance may be used as the power receiving capacitor 31B, but the adjustable range is limited by the variable capacitor. On the other hand, according to the configuration of the power receiving capacitor 31B of the present embodiment, the variable range of the electrostatic capacity can be set freely.

  In the above-described embodiment, the reactance is adjusted by making the power receiving capacitor 31B variable. However, the present invention is not limited to this. The present invention only needs to be able to adjust the reactance on the load L side as viewed from the high frequency power supply 40. For example, the power supply coil 21A and the power supply capacitor 21B of the power supply device 20 are variably provided so that the reactance of the power supply device 20 can be adjusted. Also good. Further, the power receiving coil 31 </ b> A of the power receiving device 30 may be variably provided so that the reactance of the power receiving device 30 can be adjusted.

  Further, the above-described embodiments are merely representative forms of the present invention, and the present invention is not limited to the embodiments. That is, various modifications can be made without departing from the scope of the present invention.

1 Power Supply System 20 Power Supply Device (Power Supply Unit)
21A Feed coil 21B Feed capacitor 23 Measuring instrument (Power factor detection means)
24 Power supply control unit (power factor detection means)
30 Power receiving device (power receiving unit)
31A Power receiving coil 31B Power receiving capacitor (variable capacitor)
33 Power reception control unit (adjustment means)
40 High frequency power supply (AC power supply)
C11-C16 capacitor C21-C26 capacitor SA1, SA2 Switch (switch element)
SB1, SB2 switch (switch element)
SY1, SY2 switch (switch element)

Claims (3)

A power receiving unit having a power receiving coil for receiving power in a contactless manner and a power receiving capacitor connected to the power receiving coil, a power feeding coil for feeding AC power supplied from an AC power source to the power receiving coil in a contactless manner, and the power feeding coil A power supply unit having a power supply capacitor,
Power factor detecting means for detecting the power factor of the AC power source;
An adjustment unit that adjusts reactance of the power supply unit or the power reception unit according to the power factor detected by the power factor detection unit. The power receiving capacitor or the power feeding capacitor is composed of a variable capacitor,
The power supply system according to claim 1, wherein the adjusting unit adjusts the reactance by adjusting a capacitance of the variable capacitor. The power supply according to claim 2, wherein the variable capacitor includes a plurality of capacitors and a switch element provided between the capacitors, and the capacitance changes depending on an on / off state of the switch element. system.

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