| 摘要 |
A control for a clothes dryer with an induction drive motor and an electric resistance heater element. A single sense winding is threaded through sensors monitoring drive motor current and heater current, generating an output voltage each time the alternating motor or heater current passes through a zero-crossing. The control monitors the ON/OFF condition of the heater and samples the lagging phase angle of the motor current, to provide an improved means of detecting when the clothes load is dry by measuring variation in motor torque due to minute differences in the way that the clothes load is tumbling from one drum revolution to the next revolution, ignoring cyclical, repetitive variation due to uneven drum rotational friction. The control provides a clothes cooldown period with controlled moisture regain as per the user dryness selection. In addition, numerous diagnostic conditions are monitored at the start of each cycle, or, throughout each cycle, including: 208 or 240 VAC service voltage identification; motor start detection; drum acceleration detection; empty drum detection; motor or heater open/short circuit detection; open door detection; broken belt detection; and restricted air flow detection.
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