Method and device for controlling speed of a washing machine motor
AssigneeGoldstar Co., Ltd.
InventorsDal Ho Cheong, Doo Whan Sang
Life of this patent
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Abstract
This invention relates to a method and apparatus for controlling the speed of a washing machine motor by varying the number of revolutions and changing direction of rotation of the motor to control the water current of the washing machine. The invention detects the actual speed of the washing machine motor at every half cycle of ordinary use power frequency, determines speed error by comparing the detected actual speed with an ordered speed, determines a speed state from the speed error, calculates a proportional integration value according to the determined speed state, and scales the calculated proportional compensation value into an angular value. The washing machine's motor speed is controlled using the scaled angular value.
Claims25
A method for controlling speed of a washing machine motor, comprising the steps of:
- determining an order speed of the washing machine motor based on a quantity of laundry;
- driving the washing machine motor at the determined order speed:
- detecting an actual speed of the wishing machine motor at every half cycle of ordinary use power frequency;
- determining a speed error by comparing the detected actual speed with determined order speed;
- determining a speed state using the determined speed error, the speed state determining step including the steps of
- determining the speed state to be overspeed if the speed error is greater than a preset allowance,
- determining the speed state to be underspeed if the speed error is smaller than the allowance, and
- determining the speed state to be normal if the speed error is within the allowance;
- calculating a proportional integration compensation value according to the determined speed state, the proportional integration compensation value calculation step including
- an underspeed proportional integration compensation value calculation step for calculating an underspeed proportional integration compensation value if underspeed is a result of the speed state determination step, and
- an overspeed proportional integration compensation value calculation step for calculating an overspeed proportional integration compensation value if overspeed is a result of the speed state determination step;
- determining an occupancy angle based on the calculated proportional integration compensation value;
- and
- controlling the speed of the washing machine motor using the occupancy angle.
An apparatus for controlling speed of a washing machine motor, comprising:
- current detection means for detecting a current intensity of the washing machine motor;
- speed detection means for detecting a number of rotations of the washing machine motor;
- a microcomputer including means for determining an amount of load from the detected current intensity, means for determining an initial order speed by applying a phase angle pattern based on the determined amount of load, means for determining a speed of the washing machine motor based on the number of rotations from the speed detection means, means for determining an occupancy angle by comparing the determined speed with the determined initial order speed, and means for generating order signals to control rotation speed, rotation direction, and stoppage of the washing machine motor based on the number of rotations of the washing machine motor;
- digital/analog conversion means for converting the speed order signal from the microcomputer into an analog signal;
- triangular wave generation means for generating triangular pulses from a zero crossing point of an indirect voltage from a power source;
- comparing means for generating trigger pulses by comparing the analog signal from the digital/analog conversion means with the triangular pulses from the triangular wave generation means;
- motor driving means for supplying an indirect current power source to the washing machine motor to drive the washing machine motor using the trigger pulses from the comparing means and the rotation direction and stoppage order signals from the microcomputer;
- and
- phase angle detection means for detecting phase angle using the indirect current supplied by the motor driving means and the rotation direction order signal from the microcomputer, and applying the detecting phase angle to the triangular wave generation means to generate the triangular pulses according to the detected phase angle.
Dependencies are inferred from the claim text.