| 摘要 |
PROBLEM TO BE SOLVED: To reduce vibration due to output voltage ripple in a direct-current power circuit and further enhance motor efficiency. SOLUTION: In dewatering process, a control circuit sets a reference voltage Vk as a criterion for canceling voltage ripple to the initial value thereof (Step P1) and starts driving of a washing machine motor (Step P2). In this case, interrupt process control is exercised every 0.25 seconds, as shown in Fig. 1 (b). More specifically, the reference voltage Vk at this point of time is divided by output voltage Vdc to determine a command value a and power application data is multiplied by a (Step T1 to Step T3). When the rotational speed of the washing machine motor reaches a target rotational speed (Step P3), the mean Vx of the minimum values of output voltage Vdc is calculated (Step P4) and the mean Vx is subtracted from the present reference voltage Vk. If the result ΔVx of subtraction is less than '-1 V' or greater than '+3 V' (Step P5), the reference voltage Vk is varied (Step P6). |
