JP2003259642A - Contactless power supply unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contactless power supply unit capable of controlling a voltage in correspondence with a load fluctuation in a secondary circuit without power loss or with extremely low power loss. <P>SOLUTION: The contactless power supply unit has a primary coil L1 and a secondary coil L2. The power supply unit applies a pulse voltage to the primary coil L1 to induce a secondary voltage in the secondary coil L2 and supplies a voltage to a load 6 installed in a secondary circuit. In the power supply unit, a primary circuit C1 comprises an FET 2 which subjects a direct-current voltage supplied from a direct-current power supply to switching to generate a pulse voltage; a counter electromotive force detection circuit 3 which detects counter electromotive force produced in the primary circuit; and a pulse generation circuit 4 which outputs a pulse signal for switching to the gate of the FET 2 and further performs control so as to change the frequency of the pulse signal or duty ratio according to the counter electromotive force detected by the counter electromotive force detection circuit 3. The primary circuit C1 performs control so that the voltage generated in the primary coil L1 becomes constant. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contactless power supply device for supplying a power supply voltage from a primary side circuit to a secondary side circuit in a non-contact manner, and more particularly to suppressing a voltage change caused by a load change. Regarding technology.

[0002]

2. Description of the Related Art For example, a steering mounted on a vehicle is rotatably attached to a column, and various instrumentation devices are attached to the steering. Need to supply.

As a method of supplying such a power supply voltage, conventionally, there has been proposed a method of supplying a voltage in a non-contact manner by using a transformer. That is, the primary coil of the transformer is installed on the column side, the secondary coil of the transformer is installed on the steering side, the pulse voltage is applied to the primary coil, and the secondary voltage is induced in the secondary coil. Let After that, the power supply voltage can be applied to the various instrumentation devices installed on the steering side by rectifying.

In such a non-contact power supply device, when the power consumption of the load connected to the secondary side changes, the primary side voltage and the secondary side voltage fluctuate. It is necessary to suppress this. . As a method of suppressing the voltage fluctuation, a method of detecting the current value flowing in the secondary side circuit and feeding it back to the primary side circuit to control so that the voltage value of the secondary side circuit becomes constant can be considered. However, in this method, the primary circuit and 2
Since it is necessary to connect the secondary circuit with an electric wire, it becomes complicated to route the electric wire.

Therefore, conventionally, for example, Japanese Patent Laid-Open No. 11-
As described in Japanese Patent No. 341711 (hereinafter referred to as a conventional example), a current flowing in a secondary side circuit is transmitted to a primary side circuit as a load current signal, and this load current signal is
By flowing to the diode and resistor provided in the secondary circuit,
The current value is detected by the current detection circuit. Then, based on this detection result, a method is proposed in which the chopping frequency of the primary circuit is changed to set a small power when the load is small or no load and a large power when the load is large. ing.

[0006]

However, in the method described in such a conventional example, the load current value is detected by passing a current through the diode and the resistor provided in the primary side circuit. Therefore, a loss corresponding to the voltage drop occurs. Therefore, there has been a growing demand for somehow reducing power loss.

The present invention has been made in order to solve such a conventional problem, and an object of the present invention is to generate secondary power with no power loss or with extremely low power loss. An object of the present invention is to provide a non-contact power supply device capable of performing voltage control according to load fluctuation of a circuit.

[0008]

In order to achieve the above object, the invention according to claim 1 of the present application has a primary side coil and a secondary side coil, and is generated in the primary side coil by electromagnetic induction. In a non-contact power supply device that supplies a voltage to a load connected to the secondary side coil by transmitting the voltage to the secondary side coil, a counter electromotive voltage generated in the primary side coil is detected. Accordingly, the frequency or duty ratio of the pulse voltage applied to the primary coil is changed to control the voltage generated in the primary coil to be constant.

According to a second aspect of the present invention, there is provided a primary side coil installed in the primary side circuit and a secondary side coil installed in the secondary side circuit, and the primary side coil has a pulse. In the non-contact power supply device configured to apply a voltage to induce a secondary voltage in the secondary coil and supply the voltage to the load mounted in the secondary circuit, the primary circuit includes: Switching means for switching a DC voltage supplied from a DC power source to generate a pulse voltage, counter electromotive voltage detecting means for detecting a counter electromotive voltage generated in the primary side circuit, and a pulse signal for switching to the switch means. And pulse control means for performing control to change the frequency or duty ratio of the pulse signal in accordance with the counter electromotive voltage detected by the counter electromotive voltage detection means. Means Wherein the voltage generated in the primary coil is controlled to be constant.

According to a third aspect of the present invention, the primary coil has a main coil and an auxiliary coil having a smaller number of windings than the main coil, and the counter electromotive voltage detecting means includes the auxiliary coil. The counter electromotive voltage is detected based on the voltage value generated in the coil.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a non-contact power supply device according to a first embodiment of the present invention. As shown in the figure, the non-contact power supply device 1 has a primary side circuit C.
1 and a secondary side circuit C2, and a primary side coil L1 and a secondary side circuit C2 included in the primary side circuit C1.
The transformer TR1 is formed by the secondary coil L2 included in. That is, the primary circuit C1 and the secondary circuit C2 are connected via the transformer TR1. And
For example, the primary circuit C1 is installed on the column side of the vehicle,
The secondary circuit C2 is installed on the steering side of the vehicle.

The primary circuit C1 includes a primary coil L1 and
The DC voltage Vin applied to the primary side coil L1 is turned on,
An FET (switch means) 2 which is turned off to generate a pulse voltage, a pulse generation circuit (pulse control means) 4 which outputs a pulse signal to the gate of the FET 2 and a counter electromotive voltage generated in the primary side coil L1. And a back electromotive voltage detection circuit (back electromotive voltage detection means) 3 for detecting.

The pulse generation circuit 4 includes a counter electromotive voltage detection circuit 3
Control is performed to change the frequency or duty ratio of the pulse signal to be output in accordance with the magnitude of the back electromotive force detected in.

The secondary circuit C2 includes a secondary coil L2,
A rectifier circuit 5 for rectifying an AC voltage generated in the secondary coil L2 and a load 6 for driving the DC voltage output from the rectifier circuit 5 as a power source are provided.

FIG. 2 is a circuit diagram showing a detailed structure of the primary side circuit C1. As shown in the figure, the counter electromotive voltage detection circuit 3 mounted on the primary side circuit C1 includes a diode D1 and
It is composed of resistors R1, R2 and R3, a capacitor C1 and a zener diode D2. Then, the counter electromotive voltages generated in the primary coil L1 are averaged and output to the pulse generation circuit 4.

The pulse generation circuit 4 is composed of a VCO (voltage control oscillator; voltage controlled oscillator), and the frequency of the pulse signal depends on the magnitude of the voltage output from the counter electromotive voltage detection circuit 3. Process to change. Note that the duty ratio of the pulse signal may be changed instead of the pulse frequency.

Next, the operation of the non-contact power supply device 1 according to this embodiment having the above-described structure will be described. Figure 3
(A) to (c) show that when the counter electromotive voltage is large, that is, when the power consumed by the load 6 of the secondary side circuit C2 is large,
The voltage waveforms at points "A", "B", and "C" shown in FIG. 2 are shown.

When the power consumption of the load 6 of the secondary side circuit C2 is large, as shown in FIG. 3 (a), a counter electromotive voltage of about 100 V is generated in the primary side coil L1. This voltage is applied to the resistors R1 and R through the diode D1.
2, supplied to the circuit composed of the capacitor C1 and averaged. Furthermore, since this averaging voltage has a high voltage value,
A predetermined voltage is subtracted by the Zener diode D2. As a result, a voltage signal as shown in FIG. 3B can be obtained, and this voltage signal is supplied to the pulse generation circuit 4.

The pulse generation circuit 4 changes the frequency of the pulse signal to be output according to this voltage signal. In this case, the frequency is controlled to be low, as shown in FIG. As a result, the ON / OFF cycle of the FET2 becomes longer, and the voltage value generated in the primary side circuit C1 can be reduced. As a result, the voltage generated in the primary side circuit C1 can be stabilized. Further, in the present embodiment, an example in which the frequency of the pulse signal is lowered has been described, but it is also possible to lower the voltage value by reducing the duty ratio of the pulse signal.

Next, a case where the counter electromotive voltage generated in the primary coil L1 is low will be described. 4 (a) to (c)
Is the voltage at points “A”, “B”, and “C” shown in FIG. 2 when the back electromotive force is small, that is, when the power consumed by the load 6 of the secondary side circuit C2 is small. Waveforms are shown respectively.

When the power consumption of the load 6 is small, as shown in FIG. 4A, a back electromotive voltage of about 80 V is generated in the primary coil L1, and this voltage is passed through the diode D1 and the resistor R1. , R2, and the capacitor C1 are supplied to and averaged. Furthermore, since this averaging voltage has a high voltage value, a predetermined voltage is subtracted by the Zener diode D2. As a result, FIG. 4 (b)
It is possible to obtain a voltage signal as shown in, and this voltage signal is supplied to the pulse generation circuit 4.

The pulse generation circuit 4 changes the pulse signal to be output according to this voltage value. In this case, since the input voltage value is small, as shown in FIG.
The frequency of the pulse signal is controlled to be high. As a result, the voltage value generated in the primary side circuit C1 can be increased, and as a result, the voltage can be stabilized. Further, in the present embodiment, an example in which the frequency of the pulse signal is increased has been described, but it is also possible to increase the voltage value by increasing the duty ratio of the pulse signal.

In this manner, the contactless power supply device 1 of this embodiment detects the counter electromotive voltage generated in the primary coil L1 and determines the frequency of the pulse signal according to the magnitude of the counter electromotive voltage. Alternatively, the duty ratio is changed to change the primary side circuit C1.
It is controlled so that the voltage value generated at
No wiring for transmitting a feedback signal from the secondary circuit C2 to the primary circuit C1 is required. Further, unlike the conventional example (Japanese Patent Laid-Open No. 11-341711), no loss occurs in the diode for current detection and the resistor, so that power loss can be reduced.

Next, a second embodiment of the present invention will be described. FIG. 5 is a block diagram showing the configuration of the contactless power supply device according to the second embodiment. As shown in the figure, the non-contact power supply device 11 includes a primary side circuit C11 and a secondary side circuit C12, and further includes a main coil L11a and an auxiliary coil included in the primary side circuit C11. L11b and 2
A transformer TR11 is formed by the secondary coil L12 included in the secondary circuit C12. That is, the primary circuit C1
The primary circuit C12 and the secondary circuit C12 are connected via a transformer TR11.

The primary side circuit C11 is a main coil L11a.
An auxiliary coil L11b, an FET 12 for turning on and off the DC voltage Vin to generate a pulse voltage for the main coil L11a and the auxiliary coil L11b, a pulse generation circuit 14 for outputting a pulse signal to the gate of the FET 12, The counter electromotive voltage detection circuit 13 that detects the counter electromotive voltage generated in the coil L11a.

Here, the number of turns of the auxiliary coil L11b is set to be sufficiently smaller than the number of turns of the main coil L11a.

The secondary side circuit C12 is a secondary side coil L12.
A rectifier circuit 15 for rectifying the AC voltage generated in the secondary coil L12, and a load 16 for driving the DC voltage output from the rectifier circuit 15 as a power source.
In the contactless power supply device 11, the auxiliary coil L1
The counter electromotive voltage generated in 1b is detected, and the pulse signal output to the gate of the FET 12 is controlled by the same operation as in the first embodiment described above. Therefore, similarly to the first embodiment described above, the voltage fluctuation can be suppressed, and
The wiring for transmitting the feedback signal from the secondary circuit C2 to the primary circuit C1 is not required, and the power loss can be reduced.

In addition to this, in the non-contact power supply device 11 according to the second embodiment, since the back electromotive force is detected by using the auxiliary coil L11b, the detected voltage value becomes small and the capacitance of each circuit element, The breakdown voltage can be small.

The contactless power supply device of the present invention has been described above based on the illustrated embodiment. However, the present invention is not limited to this, and the structure of each part is an arbitrary structure having the same function. Can be replaced with one.

For example, in the present embodiment, the transmission of electric power between the column side and the steering side of the vehicle has been described as an example, but the present invention is not limited to this and other uses. Can also be applied to.

[0031]

As described above, according to the present invention,
The counter electromotive voltage generated in the primary coil is detected, and the voltage value generated in the primary coil is controlled to be constant based on the magnitude of this voltage value. That is, the frequency or duty ratio of the pulse signal given to the switch means is controlled. Therefore, the voltage value can be stabilized without using an electric wire for a feedback signal from the secondary side circuit to the primary side circuit. In addition, power loss can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a non-contact power supply device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a detailed configuration of a primary side circuit shown in FIG.

FIG. 3 is an explanatory diagram showing voltage waveforms at respective points when the load power consumption is large.

FIG. 4 is an explanatory diagram showing voltage waveforms at respective points when the load power consumption is small.

FIG. 5 is a block diagram showing a configuration of a non-contact power supply device according to a second embodiment of the present invention.

[Explanation of symbols]

1,11 Non-contact power supply 2,12 FET (switch means) 3,13 Back electromotive voltage detection circuit (back electromotive voltage detection means) 4,14 Pulse generation circuit (pulse control means) 5,15 Rectifier circuit 6,16 load C1, C11 Primary circuit C2, C12 secondary circuit L1 primary coil L2, L12 secondary coil L11a Main coil (primary coil) L11b Auxiliary coil (primary coil) TR1, TR11 transformer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takahiro Shoda             1500 Onjuku, Susono City, Shizuoka Prefecture Yazaki Corporation             Within (72) Inventor Takeshi Harada             1500 Onjuku, Susono City, Shizuoka Prefecture Yazaki Corporation             Within F-term (reference) 5H730 AA14 AS01 AS11 BB23 DD04                       DD32 EE01 FD23 FD24 FF17                       FG05

Claims (3)

[Claims] 1. A primary coil and a secondary coil are provided,
In a contactless power supply device that transmits a voltage generated in a primary coil by electromagnetic induction to a secondary coil to supply a voltage to a load connected to the secondary coil, a reverse coil generated in the primary coil. The electromotive voltage is detected, and the frequency or duty ratio of the pulse voltage applied to the primary coil is changed according to the detection result to control the voltage generated in the primary coil to be constant. Non-contact power supply characterized by. 2. A primary side coil installed in a primary side circuit and a secondary side coil installed in a secondary side circuit, wherein a pulse voltage is applied to the primary side coil, In a contactless power supply device in which a secondary voltage is induced in a secondary coil to supply a voltage to a load mounted in the secondary side circuit, the primary side circuit is a DC voltage supplied from a DC power supply. Switch means for switching a pulse voltage to generate a pulse voltage, a counter electromotive voltage detection means for detecting a counter electromotive voltage generated in the primary side circuit, a pulse signal for switching to the switch means, and Pulse control means for controlling the frequency or duty ratio of the pulse signal in accordance with the counter electromotive voltage detected by the electromotive voltage detection means, wherein the pulse control means comprises the primary side. In the coil Contactless power supply and controls such that the voltage to live is constant. 3. The primary side coil has a main coil and an auxiliary coil having a smaller number of windings than the main coil, and the back electromotive voltage detection means is based on a voltage value generated in the auxiliary coil. The non-contact power supply device according to claim 1, wherein the counter electromotive voltage is detected.