JP3561613B2 - Power supply circuit - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a power supply circuit, and more particularly to suppression of spike current in an inverter power supply for driving a motor.
[0002]
[Prior art]
Hereinafter, a power supply circuit generally used conventionally will be described with reference to the drawings.
FIG. 3 is a diagram showing a configuration of a conventional general inverter-driven power supply circuit.
As shown in FIG. 3, the circuit includes NPN transistors Q1 to Q6, an inverter 1 including diodes D1 to D6, and a smoothing capacitor C1, and drives a three-phase motor M serving as a load. Circuit.
[0003]
A DC voltage DC is input to this circuit, and is output to the inverter 1 after being smoothed by a smoothing capacitor. DC voltage DC is converted to AC voltage by inverter 1. A predetermined control signal is inputted to each of the transistors Q1 to Q6 constituting the inverter 1, and the phase switching of the motor M, the adjustment of the rotation speed and the rotation direction, and the like are controlled by the control signal. M makes a predetermined rotation.
[0004]
[Problems to be solved by the invention]
The three-phase motor M, which is a load of the above power supply circuit, is composed of three coils L1 to L3 as shown in FIG. 4, and between the coils L1 to L3, mutually shown in FIG. Such parasitic capacitances C3 to C5 exist.
Each time a current flows through the coils L1 to L3 constituting the motor M, these parasitic capacitances C3 to C5 repeat charging and discharging. Therefore, when charge and discharge are performed on the parasitic capacitances C3 to C5, the flowing charge / discharge current rides on the phase current, and a current component having a spike-like waveform as shown in FIG. 5 flows in the phase current, which becomes noise. There was a problem of flying.
[0005]
[Means for Solving the Problems]
The present invention has been made in view of the above-mentioned conventional drawbacks, and is an inverter power supply circuit that converts a DC voltage into an AC and supplies the AC to a motor, and a smoothing capacitor that smoothes the DC voltage, An inverter for converting the DC voltage into AC and supplying the AC to the motor, a spike current reduction circuit provided on a power supply line between the smoothing capacitor and the inverter, and including a diode and a coil connected in parallel. A power supply circuit characterized by having
The motor has first to third coils, each of which is connected to first to third terminals, and the inverter has first to sixth NPN transistors, The emitter of the first NPN transistor is connected to the collector of the second NPN transistor, and this connection is connected to the first terminal of the motor, and the emitter is connected to the emitter of the third NPN transistor. The collector of the fourth NPN transistor is connected, and this connection is connected to the second terminal of the motor, and the emitter of the fifth NPN transistor and the collector of the sixth NPN transistor are connected to each other. Are connected to each other, and this connection is connected to the third terminal of the motor, and the collector of the first NPN transistor, the collector of the third NPN transistor, and the 5 is connected to the positive terminal of the smoothing capacitor via the spike current reducing circuit, and the emitter of the second NPN transistor and the fourth NPN transistor The above problem is solved by a power supply circuit according to the present invention, wherein the emitter of the transistor and the emitter of the sixth NPN transistor are common and are connected to the negative terminal of the smoothing capacitor. Is what you do.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration of an inverter-driven power supply circuit according to an embodiment of the present invention.
As shown in FIG. 1, this circuit includes NPN transistors Q11 to Q16, an inverter 11 including diodes D11 to D16, a smoothing capacitor C11, and a spike provided between the inverter 11 and the smoothing capacitor C11. And a current reduction circuit 12 for converting a DC voltage DC to an AC and driving a three-phase motor M serving as a load.
[0007]
As shown in FIG. 1, the inverter 11 has first to sixth NPN transistors Q11 to Q16, and the emitter of the first NPN transistor Q11 is connected to the collector of the second NPN transistor Q12. The emitter of the third NPN transistor Q13 is connected to the collector of the fourth NPN transistor Q14.
[0008]
The emitter of the fifth NPN transistor Q15 is connected to the collector of the sixth NPN transistor Q16, and the collector of the first NPN transistor Q11, the collector of the third NPN transistor Q13, and the fifth NPN The collector of the type transistor Q15 is common, and is connected to the positive terminal of the smoothing capacitor C11 via the spike current reducing circuit 12.
[0009]
Further, the emitter of the second NPN transistor Q12, the emitter of the fourth NPN transistor Q14, and the emitter of the sixth NPN transistor Q16 are common and are connected to the negative terminal of the smoothing capacitor C11. .
The spike current reduction circuit 12 includes a coil L21 and a diode D21 connected in parallel, and is provided between the inverter 11 and the smoothing capacitor C11.
[0010]
The DC voltage DC is input to the power supply circuit according to the present embodiment, and after being smoothed by the smoothing capacitor C11, is output to the inverter 11 via the spike current reduction circuit 12. A predetermined control signal is input to each of the transistors Q11 to Q16 constituting the inverter 11, and phase switching of the motor M, adjustment of the rotation speed and rotation direction, and the like are controlled by the control signal. Makes a predetermined rotation.
[0011]
Although the motor M has a parasitic capacitance as described with reference to FIG. 5, in the circuit of the present embodiment, a spike current reduction circuit 12 is provided on a power supply line connecting the inverter 11 and the smoothing capacitor C11. Have been.
For this reason, the spike current due to the charging and discharging of the parasitic capacitance is suppressed, and the phase current is smoothed as shown in FIG. 2, and the spike current can be reduced as compared with the conventional example shown in FIG.
[0012]
Therefore, it is possible to suppress the generation of noise caused by the spike current component as much as possible.
[0013]
【The invention's effect】
As described above, according to the present invention, the spike current reduction circuit is provided on the power supply line connecting the inverter and the smoothing capacitor.
For this reason, even if a parasitic capacitance exists in the motor, a spike component riding on the phase current is suppressed, and it is possible to reduce adverse effects such as noise due to the spike current as compared with the related art.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a configuration of a power supply circuit according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating an operation of the power supply circuit according to the embodiment of the present invention.
FIG. 3 is a diagram illustrating a configuration of a conventional power supply circuit.
FIG. 4 is a diagram illustrating a parasitic capacitance parasitic on a three-phase motor.
FIG. 5 is a diagram illustrating a problem of a conventional power supply circuit.
[Explanation of symbols]
11 Inverter 12 Spike current reduction circuit C11 Smoothing capacitor

Claims (2)

An inverter power supply circuit that converts a DC voltage to an AC and supplies it to a motor,
A smoothing capacitor for smoothing the DC voltage,
An inverter that converts the smoothed DC voltage into AC and supplies the AC to the motor;
A spike current reduction circuit that is provided on a power supply line between the smoothing capacitor and the inverter and that includes a diode and a coil connected in parallel, and that reduces a spike current component due to a parasitic capacitance between coils constituting the motor. A power supply circuit comprising: The motor includes first to third coils, each of which is connected to first to third terminals,
The inverter has first to sixth NPN transistors,
An emitter of the first NPN transistor and a collector of the second NPN transistor are connected, and this connection is connected to the first terminal of the motor;
The emitter of the third NPN transistor is connected to the collector of the fourth NPN transistor, and this connection is connected to the second terminal of the motor;
An emitter of the fifth NPN transistor is connected to a collector of the sixth NPN transistor, and this connection is connected to the third terminal of the motor;
A collector of the first NPN transistor, a collector of the third NPN transistor, and a collector of the fifth NPN transistor are common, and a spike current component due to parasitic capacitance between coils constituting the motor. Connected to the positive terminal of the smoothing capacitor via a spike current reducing circuit for reducing
The emitter of the second NPN transistor, the emitter of the fourth NPN transistor, and the emitter of the sixth NPN transistor are common, and are connected to the negative terminal of the smoothing capacitor. The power supply circuit according to claim 1, wherein:

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