公开(公告)号：USRE29275E

公开(公告)日：1977-06-21

申请号：US585082

申请日：1975-06-09

申请人： Herbert Berman ,  Stanley N. Tenen

发明人： Herbert Berman ,  Stanley N. Tenen

IPC分类号： H02P1/18 ,  H02P1/26 ,  H02P27/02

CPC分类号： H02P1/18 ,  H02P1/26 ,  H02P27/02

摘要： A two-phase motor preferably of the induction or hysteresis type is driven from a variable frequency clock circuit by energizing the motor windings in phase quadrature over the frequency range. Speed control is provided by mechanically modulating a light emitting diode (LED) and photoresistor combination that couples to the clock circuit for determining its frequency of operation. The output of the clock circuit in turn couples to a two-phase generator that drives output bridges associated with the motor in phase quadrature. The photo resistor is characterized by a relatively .[.lone.]. .Iadd.low .Iaddend."off" (return to dark resistance) time constant that provides automatic braking when the speed control is set to zero. The system further includes a feedback circuit responsive to motor load fluctuations sensed by monitoring the DC current drawn by output bridge circuit means associated with the motor for controlling the frequency of operation of the clock circuit. This clock control permits the motor to come up to speed quite quickly with little or no synchronous slippage.If a load which would ordinarily stall the motor at the speed indicated by the mechanical control is .[.the speed.]. .Iadd.placed .Iaddend.on the motor the feedback circuit will slow the clock control so that the motor will run at a speed lower than the mechanically indicated speed rather than stall.