Driving apparatus and method of three phase induction motor

• US 20040075414A1
• Filed: 04/16/2003
• Published: 04/22/2004
• Est. Priority Date: 10/17/2002
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Lee, Jae-Choon
• Granted Patent: US 6,876,171 B2
• Time in Patent Office: Days
• US Class Current: 318/767
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 5/458 using semiconductor devices only
• CPC Class Codes: H02P 2201/11 Buck converter, i.e. DC-DC step down converter decreasing the voltage between the supply and the inverter driving the motor general aspects of plural converters in cascade H02M
• CPC Class Codes: H02P 29/50 Reduction of harmonics

Abstract

A driving apparatus of a three-phase induction motor includes: a three-phase power supply unit for supplying three-phase power; a rectifier for rectifying the three phase voltage supplied from the three phase power supply unit; a voltage reducing unit for reducing a DC voltage generated from the rectifier and outputting a stabilized DC voltage; and an inverter unit for varying the DC voltage outputted from the voltage reducing unit to a three-phase AC voltage and driving a three-phase induction motor. A power-factor degradation generated during supplying a DC voltage to the inverter to drive the three-phase induction motor is prevented, a harmonic wave is removed, and because a high-priced inverter component is not necessary, its relevant expense is reduced.

Claims

1. A driving apparatus of a three-phase induction motor comprising:

a three-phase power supply unit for supplying three-phase power;

a rectifier for rectifying the three phase voltage supplied from the three phase power supply unit;

a voltage reducing unit for reducing a DC voltage generated from the rectifier and outputting a stabilized DC voltage; and

an inverter unit for varying the DC voltage outputted from the voltage reducing unit to a three-phase AC voltage and driving a three-phase induction motor.

2. The apparatus of claim 1, wherein the voltage reducing unit comprises:

an integrated circuit unit for measuring a voltage generated from the rectifier and outputting a control signal to control the DC voltage outputted from the rectifier to the inverter unit;

a gate driving unit for generating a drive signal to drive the inverter unit according to the control signal outputted from the integrated circuit unit;

a DC stabilizer for reducing the DC voltage generated from the rectifier according to the drive signal of the gate driving unit, and generating a stabilized DC voltage;

a DC link unit for linking the DC voltage generated from the DC stabilizer; and

a load unit for supplying the DC voltage applied to the DC link unit to the inverter unit.

3. The apparatus of claim 2, wherein the DC voltage inputted to the inverter unit 23 is a harmonic wave generation-restrained and reduced voltage.

4. The apparatus of claim 2, wherein the integrated circuit unit measures a current supplied from the rectifier to the DC stabilizer and turns off output of a control signal if the supplied current is an overcurrent.

5. The apparatus of claim 2, wherein the voltage reducing unit comprises a voltage measuring unit for measuring a voltage linked to the DC link unit through the DC stabilizer.

6. The apparatus of claim 2, wherein the voltage reducing unit further comprises a switch unit for selectively supplying power applied from the outside to the integrated circuit unit.

7. The apparatus of claim 2, wherein the DC stabilizer comprises:

a transistor turned on when a drive signal is inputted from the gate driving unit; and

a condenser and a resistance connected in series to each other and connected in parallel to the transistor.

8. The apparatus of claim 7, wherein when the transistor is turned on by the drive signal inputted from the gate driving unit as a control signal is outputted from the integrated circuit unit, the DC stabilizer reduces the DC voltage of the rectifier applied to the condenser and the resistance and links it to the DC link unit.

9. The apparatus of claim 4, wherein the integrated circuit unit turns off output of the control signal if the voltage supplied to the DC link unit is above a reference value.

10. The apparatus of claim 2, wherein the gate driving unit comprises:

a photocoupler turned on/off according to a control signal outputted from the integrated circuit unit;

a first NPN transistor turned off when the photocoupler is turned on;

a first PNP transistor turned off when the photocoupler is turned on; and

a second NPN transistor turned on when the first NPN transistor is turned off.

11. The apparatus of claim 10, wherein, in order to increase a strength of a current outputted through a drive signal, the gate driving unit further comprises a second photocoupler, a second NPN transistor, a second PNP transistor, a fourth NPN transistor and a third PNP transistor, each corresponding to the first photocoupler, the first NPN transistor, the first PNP transistor and the second NPN transistor.

12. The apparatus of claim 10, wherein, in the gate driving unit, a voltage outputted from the photocoupler is divided by first and second resistances and applied to a base of the first NPN transistor, a third resistance is connected to a collector;

connection terminal of a base of the second NPN transistor and a base of the first PNP transistor is connected to a collector of the first NPN transistor;

an emitter of the second NPN transistor is connected to a fourth resistance;

a diode is connected in parallel to the fourth resistance;

an emitter of the second NPN transistor is connected in series to an emitter of the first PNP transistor.

13. A driving method of a three-phase induction motor comprising:

a rectifying step of rectifying a three-phase voltage;

a measuring step of measuring a size of the voltage rectified in the rectifying step; and

a rectified voltage size controlling step of controlling a size of a rectified voltage supplied to an inverter unit which drives a three-phase induction motor according to the size of the voltage measured in the measuring step.

14. The method of claim 13, wherein the rectified voltage size controlling step comprises:

measuring a size of a current applied current in order to apply a voltage to the inverter unit, and accordingly controlling a size of the rectified voltage supplied to the inverter.

15. A driving method of a three-phase induction motor comprising:

a power supplying step of supplying three-phase power;

a rectifying step of rectifying the supplied three-phase voltage;

a voltage reducing step of reducing the DC voltage generated in the