Washing machine with vector control for drive motor

• US 20020189301A1
• Filed: 06/05/2002
• Published: 12/19/2002
• Est. Priority Date: 06/06/2001
• Status: Active Grant

• Current Assignee: Toshiba Lifestyle Products & Services Corporation (Midea Group Co., Ltd)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Nagai, Kazunobu, Ito, Michiaki, Tanaka, Toshimasa, Kawabata, Shinichiro, Hosoito, Tsuyoshi, Okazaki, Yoji, Isono, Futoshi
• Granted Patent: US 7,017,377 B2
• Time in Patent Office: Days
• US Class Current: 68/12.02
• CPC Class Codes: D06F 2103/24 Spin speed; Drum movements
• CPC Class Codes: D06F 2103/46 of the motor driving the drum
• CPC Class Codes: D06F 2105/48 Drum speed
• CPC Class Codes: D06F 33/48 Preventing or reducing imbalance or noise
• CPC Class Codes: D06F 37/304 Arrangements or adaptations of electric motors
• CPC Class Codes: H02P 21/06 Rotor flux based control involving the use of rotor position or rotor speed sensors
• CPC Class Codes: H02P 21/22 Current control, e.g. using a current control loop
• CPC Class Codes: Y02B 40/00 Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers

Abstract

A washing machine includes an electric motor developing torque used for wash, rinse and dehydration operations, a current detector detecting current flowing into the motor, and a torque controller performing a vector control for the motor on the basis of the current detected by the current detector so that the torque developed by the motor is optimum for at least each of the wash and dehydration operations.

Claims

1. A washing machine comprising:

an electric motor developing torque used for wash, rinse and dehydration operations;

a current detector detecting current flowing into the motor; and

a torque controller performing a vector control for the motor on the basis of the current detected by the current detector so that the torque developed by the motor is optimum for at least each of the wash and dehydration operations.

2. A washing machine according to claim 1, further comprising an inverter circuit for driving the motor, the inverter including a plurality of upper arm side switching elements and a plurality of lower arm side switching elements, wherein the current detector detects current flowing through a resistor connected in series to the lower arm side switching elements.

3. A washing machine according to claim 2, wherein the motor has three phases, and the current detector detects current with respect to two of the three phases in which neither phase voltage shows a maximum level, on the basis of an exciting electrical angle with respect to the motor.

4. A washing machine according to claim 2, wherein a plurality of the resistors are connected in series to the lower arm side switching elements so as to form a series circuit, and the current detector switches a detecting position in the series circuit according to a load condition.

5. A washing machine according to claim 1, further comprising a speed controller provided at a stage previous to the torque controller for performing a PI control for a motor speed on the basis of a speed command and a speed of the motor obtained from the current detected by the current detector.

6. A washing machine according to claim 5, wherein the speed controller delivers q-axis and d-axis current command values to the torque controller, and the torque controller performs a PI control on the basis of the q-axis and d-axis current command values and q-axis and d-axis current values of the motor obtained from the current detected by the current detector, thereby generating q-axis and d-axis voltage command values.

7. A washing machine according to claim 5, wherein the speed controller changes a control gain used in the PI control according to a motor speed.

8. A washing machine according to claim 5, wherein the speed controller changes a control gain used in the PI control at least with respect to each of a wash operation and a dehydration operation.

9. A washing machine according to claim 5, wherein the speed controller has a control period set to be less than 50 ms.

10. A washing machine according to claim 1, wherein the torque controller starts control at a time a rotational speed of the motor is increased to a predetermined value.