JPH11113247A - Power supply circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce spike current, by constituting a power supply circuit so that the power supply circuit is placed in the power line between a smoothing capacitor and an inverter and is provided with a spike current reducing circuit comprising parallel-connected diode and coil. SOLUTION: A power supply circuit is provided with a spike current reducing circuit 12 placed between an inverter 11 and a smoothing capacitor C11. When a direct-current voltage DC is inputted, the direct-current voltage DC is smoothed through the smoothing capacitor C11 and then outputted to the inverter 11 through the spike current reducing circuit 12. Transistors Q11-Q16 comprising the inverter 11 are fed with a specified control signal, respectively, and the phase switching, the adjustment of the rotational speed and direction of a motor M are controlled through the control signal, so that the motor M is rotated as specified. Though there is parasitic capacitance in the motor M, the spike component is suppressed because the spike current reducing circuit 12 is provided. As a result, spike currents can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. 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]

2. Description of the Related Art A conventional power supply circuit will be described below 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, this circuit includes NPN-type 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.
After being smoothed by the smoothing capacitor, it is output to the inverter 1. DC voltage DC by inverter 1
Is converted to an AC voltage. A predetermined control signal is input to each of the transistors Q1 to Q6 constituting the inverter 1, and phase control of the motor M, adjustment of the rotation speed and rotation direction, and the like are controlled by the control signal. M makes a predetermined rotation.

[0004]

The three-phase motor M, which is a load of the above power supply circuit, comprises three coils L1 to L3 as shown in FIG.
And between the parasitic capacitances C3 to C5 as shown in FIG.
Exists. 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 the parasitic capacitances C3 to C5 are charged and discharged, the flowing charge / discharge current rides on the phase current, and a spike-shaped current component as shown in FIG. 5 flows in the phase current, which becomes noise. There was a problem of flying.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and is an inverter power supply circuit for converting a DC voltage into an AC and supplying the AC to a motor, wherein the DC voltage is smoothed. A smoothing capacitor, an inverter that converts the smoothed DC voltage to AC and supplies the AC to the motor, and a diode provided in a power supply line between the smoothing capacitor and the inverter and connected in parallel. A power supply circuit having a spike current reduction circuit composed of a coil and the motor, the motor includes first to third coils, and first to third terminals are connected to each of the first to third coils. And wherein the inverter includes first to sixth NPs.
An N-type transistor, wherein an emitter of the first NPN-type transistor and a collector of the second NPN-type transistor are connected to each other, and the connection portion is connected to the first of the motor;
And 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, and the fifth terminal is connected to the fifth terminal of the motor. The emitter of the NPN transistor is connected to the collector of the sixth NPN transistor, and this connection is connected to the third terminal of the motor, and the collector of the first NPN transistor is connected to the third terminal of the motor. The collector of the NPN transistor and the collector of the fifth NPN transistor are common, and connected to the positive terminal of the smoothing capacitor via the spike current reduction circuit. An emitter, an emitter of the fourth NPN transistor, and an emitter of the sixth NPN transistor are common, and The power supply circuit according to the present invention, characterized in that connected to the negative terminal of the smoothing capacitor is intended to solve the above problems.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing 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 and diodes D11 to D16.
And a smoothing capacitor C11
And a spike current reducing circuit 12 provided between the inverter 11 and the smoothing capacitor C11. The spike current reducing circuit 12 converts a DC voltage DC into an AC voltage and drives a three-phase motor M serving as a load.

As shown in FIG. 1, the inverter 11 has first to sixth NPN transistors Q11 to Q16, and an emitter of the first NPN transistor Q11 and a collector of the second NPN transistor Q12. Are connected, and the emitter of the third NPN transistor Q13 is connected to the collector of the fourth NPN transistor Q14.

Further, 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 collector of the fifth NPN transistor Q15 are common. And connected to the positive terminal of the smoothing capacitor C11 via the spike current reducing circuit 12.

Further, the second NPN transistor Q1
The second emitter, 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.

In the power supply circuit according to the present embodiment, a DC voltage DC is input, smoothed by a smoothing capacitor C11, and then output to an inverter 11 via a spike current reducing circuit 12. A predetermined control signal is input to each of the transistors Q11 to Q16 constituting the inverter 11, 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. Makes a predetermined rotation.

Although the motor M has a parasitic capacitance as described with reference to FIG. 5, in the circuit of this embodiment, a spike current reduction circuit is provided on a power supply line connecting the inverter 11 and the smoothing capacitor C11. 12 are provided.
Therefore, the spike current due to the charging and discharging of the parasitic capacitance is suppressed, 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.

Therefore, it is possible to suppress the generation of noise caused by the spike current component as much as possible.

[0013]

As described above, according to the present invention,
A spike current reduction circuit is provided on a 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 of 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)

[Claims] 1. An inverter power supply circuit for converting a DC voltage to an AC and supplying the AC to a motor, comprising: a smoothing capacitor for smoothing the DC voltage; and a motor for converting the smoothed DC voltage to AC. And a spike current reduction circuit provided in a power supply line between the smoothing capacitor and the inverter, the spike current reduction circuit including a diode and a coil connected in parallel. 2. The motor according to claim 1, wherein the motor includes first to third coils, and first to third terminals are respectively connected to the first and third coils. A transistor, an emitter of the first NPN transistor and the second
Is connected to the first terminal of the motor, and the emitter of the third NPN transistor is connected to the fourth terminal of the third NPN transistor.
Is connected to the second terminal of the motor, and the emitter of the fifth NPN transistor is connected to the sixth terminal of the motor.
And the collector of the NPN transistor is connected to the third terminal of the motor. The collector of the first NPN transistor is connected to the third terminal of the motor.
Of the NPN transistor and the fifth NP
The N-type transistor has a common collector and is connected to the positive terminal of the smoothing capacitor via the spike current reduction circuit. The emitter of the second NPN-type transistor and the fourth
Of the NPN transistor and the sixth NP
2. The power supply circuit according to claim 1, wherein an emitter of the N-type transistor is common and is connected to a negative terminal of the smoothing capacitor.