| 摘要 |
A blower motor unit having a variable speed motor and that is suitable for direct, drop-in replacement in a residential HVAC (heating, ventilation, and air conditioning) system that employs a PSC motor. The blower motor unit is provided with a neutral input and two hot AC line connections, one for connection to the heating power source and the other to the cooling power source. The blower motor unit senses which of the inputs is energized by sensing either voltage or current on at least one of the inputs, selects one of at least two reference signals in accordance with which input is energized, and presents the control input of the replacement variable speed motor with the selected reference signal, thereby controlling the speed of the variable speed motor. This motor control unit, and the method by which it selects one of two signals for application to a control input of a motor, are also independently useful to control any type of motor having at least two modes of operation.
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