| 摘要 |
<p>Power requirements on a loaded motor for a washing machine are controlled by a feedback circuit which disengage the motor for sufficient intervals during use to prevent overheating when subject to high load effects, e.g. because use for items which are highly absorbent and also too coherent to distribute uniformly around the drum, e.g. napkins or dish cloths. The control circuit involves a microprocessor which compares a signal related to the nominal speed of the drum with a tachegraph signal which indicates the actual speed of the drum. A difference in the signal, due to slowing of the drum by an overload, is converted to a phase angle differential which upon reaching 180 deg. C in response to a predetermined difference, holds a triac circuit open to stop the motor. Allows overall motor size and cost, in respect of the copper windings or their heat dissipation systems, to be reduced below that necessary to cope with occasional anticipated operating overload levels without stopping or overheating.</p> |
