| 摘要 |
In a motor control circuit for an electronically commutated reversible motor used in a ceiling fan, a control is used to reduce the voltage supplied to the motor for variable speed or torque operation. At the same time, a substantially smooth control voltage, dependent on the variable voltage supplied to the motor, is produced. This control voltage, which is used to enhance the adjustment rate, is applied to control a pulse width modulator, which produces output pulses which also control the flow of energy to the motor. When the control voltage reaches a value slightly past the desired minimum speed or torque setting, a signal is generated to change the direction of motor rotation. Means are provided to delay the actual reversal to protect the power switches in the control circuit. When power is first applied, the initial direction of motor rotation is set by a switch on the ceiling fan. The control circuit permits control of motor reversal from a wall location. The control circuitry is designed for use in a maximally integrated ECM control circuit. The invention also concerns a method of controlling an ECM, including reversal, and reversal combined with torque or speed control. |
