JP7182276B2 - Contactless power supply device - Google Patents

Description

The present invention relates to a non-contact power supply device that supplies power without contacting a power receiving device.

In equipment that supplies power from a power supply device to a power receiving device in a contactless manner, if the primary coil of the power feeding device and the secondary coil of the power receiving device are misaligned, the transmitted power and transmission efficiency will decrease. Compensation for side coil and secondary coil misalignment is important.
In relation to this point, Patent Literature 1 describes a system for adjusting the capacitance of a capacitor using a distance sensor. In this system, a plurality of capacitors are connected in parallel, and the capacitance of each capacitor is adjusted by switching a switch corresponding to each capacitor. The problem is that this system requires the addition of a distance sensor and a large number of capacitors and a large number of switches, and the control accuracy depends on the accuracy of the distance sensor. Furthermore, since the capacitance of the capacitor is varied by switching the parallel connection of the capacitors, the capacitance of the capacitor cannot be varied continuously, and there is a tendency for the accuracy of compensation control to deteriorate.

On the other hand, Non-Patent Document 1 describes a system that employs a capacitor capacitance variable circuit configured by four power semiconductor elements and a capacitor. This system does not require a distance sensor, and can continuously vary the capacitance of the capacitor with respect to the positional deviation of the primary and secondary coils.

Japanese Patent No. 5010061

Takanori Isobe, Kazuyuki Wakasugi, Ryuichi Shimada, "Improving Efficiency of Contactless Power Supply Using Series Compensator MERS", Journal of Power Electronics Society, Vol. 37, pp. 81-88 (2012)

However, the system described in Non-Patent Document 1 requires the addition of four power semiconductor elements (switch elements), and in addition, the capacitor capacity variable circuit is provided in the power receiving device. There is a problem that it is not possible to cope with the case where the power receiving device cannot be provided with a variable capacitor capacitance circuit due to restrictions or other reasons.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a non-contact power feeder equipped with a mechanism for varying the capacitance of a capacitor while suppressing an increase in the number of switch elements.

A non-contact power supply device according to the present invention that meets the above object includes first and third switches connected to a positive side of a DC power supply and second and fourth switches connected to a negative side of the DC power supply. A contactless power supply device that includes a bridge circuit having a switch, a resonance capacitor and a primary coil provided on the output side of the bridge circuit, and supplies power in a contactless manner to a power receiving device that includes a secondary coil, A switch A and a switch B respectively connected to the positive side and the negative side of the DC power supply, and one side connected to the switch A and the switch B and the other side connected to the resonance capacitor via the bridge circuit. A switch C provided between the auxiliary capacitor and the first and second switches on the side of the first switch with reference to the contacts of the auxiliary capacitor and the bridge circuit, and the first and fourth switches And the switch C is turned on, the second and third switches and the switches A and B are turned off, and the current from the positive side of the DC power supply unit is supplied to the first switch and the switch C and a high capacitor mode applied to the primary coil via the resonance capacitor, the fourth switch and the switch A are turned on, and the first, second and third switches and the switches B and C are turned off. a low-capacitor mode in which a current from the positive side of the DC power supply is applied to the primary coil via the switch A, the auxiliary capacitor, and the resonance capacitor, and the control means adjusts the capacitance of the capacitor by changing the ratio of the high capacitor mode and the low capacitor mode.

In the contactless power supply device according to the present invention, since the switch elements added to the conventional equipment are the switches A, B, and C, the number of switch elements can be reduced to three. Then, the control means changes the ratio of the high capacitor mode and the low capacitor mode by switching the first, second, third and fourth switches and the switches A, B and C between ON and OFF states to equivalently Since the capacitance of the capacitor is adjusted, it has a mechanism for varying the capacitance of the capacitor.

1 is a circuit diagram of a non-contact power feeding device according to an embodiment of the present invention; FIG. FIG. 4 is an explanatory diagram showing signals output from each signal output section in a high capacitor mode; (A) is an explanatory diagram showing current paths in the connection state α, and (B) is an explanatory diagram showing current paths in the connection state β. FIG. 4 is an explanatory diagram showing signals output from each signal output section in a low capacitor mode; (A) is an explanatory diagram showing current paths in the connection state γ, and (B) is an explanatory diagram showing current paths in the connection state δ. FIG. 10 is an explanatory diagram showing output signals from each signal output section for setting a high capacitor mode and a low capacitor mode at a ratio of 1:1; 7 is a graph showing the result of simulating the relationship between the ratio of high-capacitor mode and low-capacitor mode and the output voltage of the secondary coil. FIG. 10 is a graph showing the result of a simulation comparing the output voltage of the secondary coil when the capacitance is variable and when the capacitance is fixed under the condition that the mutual inductance is lowered; FIG.

Next, specific embodiments of the present invention will be described with reference to the attached drawings for better understanding of the present invention.
As shown in FIG. 1, a contactless power supply device 10 according to one embodiment of the present invention includes a switch 11 (first switch) and a switch 13 (third switch) connected to the positive side of a DC power supply section 15. switch), a switch 12 (second switch) and a switch 14 (fourth switch) connected to the negative side of the DC power supply unit 15, and a bridge circuit 16 provided on the output side of the bridge circuit 16. It is a device that has a capacitor 17 and a primary coil 18 and supplies power in a non-contact manner to a power receiving device 20 that has a secondary coil 19 . A detailed description will be given below.
Although FIG. 1 is an equivalent circuit and is described as if the non-contact power feeding device 10 and the power receiving device 20 are connected by wire, the non-contact power feeding device 10 and the power receiving device 20 are actually connected by wire. not

As shown in FIG. 1, the contactless power supply device 10 includes a DC power supply unit 15, a bridge circuit 16 to which a DC voltage is applied from the DC power supply unit 15, and a resonance capacitor 17 and a primary coil 18 connected in series. I have.
The DC power supply unit 15 can be composed only of a DC power supply as shown in FIG. 1, but is not limited to this. For example, a DC power supply unit may be employed that includes an AC power supply and a converter that converts an AC voltage output from the AC power supply into a DC voltage. In the present embodiment, a capacitor 21 is connected in parallel with the DC power supply unit 15 to stabilize the AC voltage value applied to the bridge circuit 16 .

The bridge circuit 16 has the switches 11 and 12 connected in series, the switches 13 and 14 connected in series, and the switches 11 and 12 and the switches 13 and 14 arranged in parallel. One end of a conductor 22 is connected between the switches 11 and 12 and the other end of the conductor 22 is connected to one side of the resonance capacitor 17 .
A primary coil 18 magnetically coupled with the secondary coil 19 is connected to the other side of the resonance capacitor 17 .

A switch A and a switch B are connected to the positive side and the negative side of the DC power supply section 15, respectively. The switches A and B are connected in series, and between the switches A and B is one end of a conductor 23 whose other end is connected between the switches 11 and 12 (one end of the conductor 22 in this embodiment). is connected. The conducting wire 23 is provided with an auxiliary capacitor 24 having one side connected to the switches A and B via the conducting wire 23 and the other side connected to the resonance capacitor 17 via the conducting wire 23 and the conducting wire 22 (bridge circuit 16). . That is, the resonance capacitor 17 and the auxiliary capacitor 24 are connected in series.

Between the switches 11 and 12 of the bridge circuit 16, a switch C is provided on the switch 11 side with the other end of the conductor 23 (corresponding to the contact of the auxiliary capacitor 24 and the bridge circuit 16) as a reference.
In the current state of the art, the switches 11, 12, 13, 14 and the switches A, B, C are power semiconductor elements in which valve devices mainly composed of IGBTs and diodes are connected in parallel, respectively.

The diodes of the switches 11, 12, 13, and 14 and the switches A and B are arranged so that the current passes toward the positive side of the DC power supply section 15, and the diode of the switch C is arranged toward the positive side of the DC power supply section 15. are arranged so that no current can pass through them. Hereinafter, for each of the switches 11, 12, 13, 14 and the switches A, B, and C, a state in which the valve device is energized is referred to as an ON state, and a state in which the valve device is not energized (blocked state). The time is called the OFF state.

The non-contact power supply device 10 also includes a control circuit (an example of control means) 25 for switching ON and OFF states of the switches 11, 12, 13, and 14 and the switches A, B, and C, respectively. The control circuit 25 is provided with signal output sections G1, G2, G3, G4, Ga, Gb, and Gc corresponding to the switches 11, 12, 13, and 14 and the switches A, B, and C, respectively. The switch 11 is turned on when a signal of 1 is output from the corresponding signal output section G1, and turned off when a signal of 0 (zero) is output. The same applies to the switches 12, 13, 14 and the switches A, B, C and the corresponding signal output sections G2, G3, G4, Ga, Gb, Gc.

The control circuit 25 switches ON and OFF states of the switches 11, 12, 13, and 14 and the switches A, B, and C to set only the resonance capacitor 17 to resonate with the primary coil 18. and the auxiliary capacitor 24, the direction of the current in the primary coil 18 is switched, the primary coil 18 and the secondary coil 19 are coupled, and energy is transmitted from the primary coil 18 to the secondary coil 19. I do.

When resonating the primary coil 18 and the resonance capacitor 17, the control circuit 25 turns on the switches 11, 14 and the switch C, and turns off the switches 12, 13 and the switches A, B as shown in FIG. The connection state α and the connection state β in which the switches 12, 13 and C are turned ON and the switches 11, 14 and switches A and B are turned OFF are alternately repeated. In FIG. 2 (the same applies to FIGS. 4 and 6), the horizontal axis is the time axis, and the vertical axis means the signals of the signal output sections G1, G2, G3, G4, Ga, Gb, and Gc.
Therefore, in the connection states α and β, the switches A and B are kept OFF, and the switch C is kept ON.

In connection state α, as shown in FIG. , and is sent from the other side of the primary coil 18 to the negative side of the DC power supply section 15 through the switch 14 . Therefore, the auxiliary capacitor 24 is not energized.
Immediately after switching from the connection state α to the connection state β, the energy accumulated in the primary coil 18 generates a current opposite to the applied voltage (at this time, the resonance capacitor 17 is energized). and the auxiliary capacitor 24 is not energized).

After that, in the connection state β, the current follows the applied voltage, and as shown in FIG. , from one side of the primary coil 18 to the negative side of the DC power source 15 via the resonance capacitor 17, the lead wire 22 and the switch 12 in order. Therefore, the auxiliary capacitor 24 is not energized.

Immediately after switching from the connection state β to the connection state α, the resonance capacitor 17 is energized and the auxiliary capacitor 24 is not energized even when a current opposite to the applied voltage is generated.
Therefore, in resonance due to switching between the connection states α and β, the resonance capacitor 17 is energized and the auxiliary capacitor 24 is not energized. Therefore, when the capacitances (capacitances) of the resonance capacitor 17 and the auxiliary capacitor 24 are C1 and Ca, respectively (the same applies hereinafter), the primary coil 18 and the resonance capacitor 17 resonate at the capacitance C1.

On the other hand, when the primary coil 18, the resonance capacitor 17 and the auxiliary capacitor 24 are to be resonated, the control circuit 25 turns on the switch 14 and switch A, switches 11, 12 and 13 and switch 11, 12, 13 and A connection state γ in which B and C are turned off and a connection state δ in which the switches 13 and B are turned on and the switches 11, 12, 14 and switches A and C are turned off are alternately repeated. Therefore, in the connection states γ and δ, the switches 11 and 12 and the switch C are kept OFF.

In the connection state γ, as shown in FIG. 5A, the current from the positive side of the DC power supply section 15 passes through the switch A, the auxiliary capacitor 24 (lead wire 23), the lead wire 22 and the resonant capacitor 17 in this order, and then the primary It is applied to one side of the coil 18 and sent from the other side of the primary coil 18 to the negative side of the DC power supply section 15 through the switch 14 .
When the connection state γ is switched to the connection state δ, a current opposite to the applied voltage is generated immediately after switching. At this time, the resonance capacitor 17 and the auxiliary capacitor 24 are energized.

After that, in the connection state δ, the current follows the applied voltage, and as shown in FIG. 18 to the negative side of the DC power supply unit 15 via the resonance capacitor 17, the lead wire 22, the auxiliary capacitor 24 (lead wire 23) and the switch B in this order.
The resonance capacitor 17 and the auxiliary capacitor 24 are also energized immediately after switching from the connection state δ to the connection state γ when a current opposite to the applied voltage is generated.
Therefore, in the resonance caused by switching the connection states γ and δ, both the resonance capacitor 17 and the auxiliary capacitor 24 are energized, and the capacitance of the primary coil 18, the resonance capacitor 17 and the auxiliary capacitor 24 is Ca×C1/(Ca+C1), that is, It resonates with a combined capacitance obtained by connecting the resonance capacitor 17 and the auxiliary capacitor 24 in series.

In this embodiment, a mode in which the primary coil 18 and the resonance capacitor 17 resonate with the capacitance C1 (a mode in which the connection states α and β are repeated) is called a high-capacitance mode. is called a low-capacitance mode (a mode in which connection states γ and δ are repeated) in which resonates with capacitance Ca×C1/(Ca+C1).
Since the low-capacitor mode has a smaller capacitance than the high-capacitor mode, the Q value is large. When the distance between the primary coil 18 and the secondary coil 19 is fixed, the output voltage of the secondary coil 19 in the power receiving device 20 (the output voltage with respect to the load of the power receiving device 20) increases as the Q value increases. Become.

The control circuit 25 can switch between the high capacitor mode and the low capacitor mode, and can change the ratio (time ratio, duty) of the high capacitor mode and the low capacitor mode. For example, by switching ON and OFF states of switches 11, 12, 13, and 14 and switches A and B as shown in FIG. can.
Then, the control circuit 25 changes the ratio of the high-capacitor mode and the low-capacitor mode to continuously change the Q value together with the electrostatic capacitance (capacitor capacitance) that contributes to the resonance of the non-contact power supply device 10 side, thereby The magnitude of the output voltage of coil 19 is adjusted.

Therefore, the electronic parts and the like added for adjusting the magnitude of the output voltage of the secondary coil 19 are mainly the three switches A, B, and C of the non-contact power supply device 10. and the auxiliary capacitor 24 . Since the power semiconductor elements to be added are as small as three switches A, B, and C, as a result, it is possible to suppress an increase in heat generation in the non-contact power supply device 10 as a whole.
On the other hand, on the power receiving device 20 side, in principle, no additional electronic components or the like are required.
The power receiving device 20 is provided with a resonance capacitor 28 that forms a resonance circuit together with the secondary coil 19 .

In addition, the control circuit 25 includes a zero-cross detection section, a phase calculation section, a PI control section, etc., detects the current value and voltage value of the lead wire 22 (output side of the bridge circuit 16), and detects the respective zero crossings. Phase information is obtained based on the points, and the power factors of the current value and the voltage value are controlled to be 1 (same phase). In the present embodiment, the reference position of the secondary coil 19 with respect to the primary coil 18 is set at a position where the power factor of the current value and voltage value of the lead wire 22 is 1 in the high capacitor mode. The control circuit 25 can detect that the secondary coil 19 is not placed at the reference position from the power factor drop (below 1), and when the power factor drop is detected, the high capacitor mode and the low capacitor mode can be detected. The capacitor mode is switched, and the ratio between the high capacitor mode and the low capacitor mode is adjusted so that the power factor becomes unity.

Next, experiments conducted to confirm the effects of the present invention will be described.
In the first experiment, the relationship between the ratio of high-capacitor mode and low-capacitor mode and the output voltage of the secondary coil was simulated. The simulation results are shown graphically in FIG.
In the simulation, each capacitance of the resonance capacitor and the auxiliary capacitor of the contactless power supply device was set to 68 nF.

In the graph of FIG. 7, the vertical axis is the output voltage of the secondary coil, and the horizontal axis is the ratio of the low capacitor mode to the whole (0 for high capacitor mode only, 1 for low capacitor mode only, high capacitor mode and low capacitor mode 1:1 indicates 0.5).
From the experimental results, it was confirmed that the output voltage of the secondary coil can be adjusted by changing the ratio of the high capacitor mode and the low capacitor mode.

In the second experiment, when the output voltage of the secondary coil was 100 V in terms of effective value (peak value was 141.4 V), the distance between the primary coil and the secondary coil was widened to make the mutual inductance 50%. The output voltage of the next coil was simulated. The simulation is for switching between high-capacitor mode and low-capacitor mode (with a capacitor connection switching circuit, solid line) and for a case where the capacitance of the resonance circuit on the non-contact power supply side is fixed (without a capacitor connection switching circuit, dashed line). I went with The simulation results are shown graphically in FIG.

From the experimental results, when the capacitance of the resonance circuit on the side of the non-contact power supply is fixed, the effective value of the output voltage of the secondary coil is significantly below 100 V, and the resonance capacitor of the non-contact power supply and the power receiving device It is out of the compensation range of the resonant capacitor. On the other hand, it was confirmed that the effective value of the output voltage of the secondary coil could be kept at 100 V when switching between the high capacitor mode and the low capacitor mode.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and all modifications of conditions that do not deviate from the gist of the present invention are within the scope of the present invention.
For example, a plurality of resonance capacitors may be provided on the side of the contactless power supply device.
Further, the first, second, third and fourth switches and the switches A, B and C are not limited to power semiconductor elements in which IGBTs and diodes are connected in parallel. MOSFETs can be employed for the third and fourth switches and the switches A, B, and C, respectively.
Then, the control means may perform control such that the power factor becomes a predetermined value other than 1, or may perform control based on a value other than the power factor.

10: non-contact power supply device, 11, 12, 13, 14: switch, 15: DC power supply unit, 16: bridge circuit, 17: resonance capacitor, 18: primary coil, 19: secondary coil, 20: power receiving device, 21: capacitor, 22: lead wire, 23: lead wire, 24: auxiliary capacitor, 25: control circuit, 28: resonance capacitor, A, B, C: switch, G1, G2, G3, G4, Ga, Gb, Gc: signal Output section

Claims (2)

a bridge circuit comprising first and third switches connected to the positive side of the DC power supply and second and fourth switches connected to the negative side of the DC power supply; In a contactless power supply device that has a resonance capacitor and a primary coil provided and that supplies power in a contactless manner to a power receiving device that includes a secondary coil,
a switch A and a switch B respectively connected to the positive side and the negative side of the DC power supply;
an auxiliary capacitor having one side connected to the switch A and the switch B and having the other side connected to the resonance capacitor via the bridge circuit;
a switch C provided between the first and second switches on the side of the first switch with reference to the contacts of the auxiliary capacitor and the bridge circuit;
The first and fourth switches and the switch C are turned on, the second and third switches and the switches A and B are turned off, and the current from the positive side of the DC power supply unit is A high-capacitance mode applied to the primary coil via the first switch, the switch C and the resonant capacitor, the fourth switch and the switch A are turned on, and the first, second and third switches are turned on. and a low capacitor mode in which the current from the positive side of the DC power supply is applied to the primary coil via the switch A, the auxiliary capacitor and the resonance capacitor by turning off the switches B and C. means and
The non-contact power feeding device, wherein the control means adjusts the capacitance of the capacitor by changing the ratio of the high capacitor mode and the low capacitor mode. 2. The non-contact power supply device according to claim 1, wherein said first, second, third and fourth switches and said switches A, B and C are power semiconductor elements in which valve devices and diodes are connected in parallel, respectively. A contactless power supply device characterized by:

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