초록 ▼

A speed controller for a DC motor includes a semiconductor switching device connected in series with it in a DC power circuit. The switching circuit is turned on and off with a duty ratio variable as a function of motor load. A time constant circuit including a capacitor is connected in parallel wit

A speed controller for a DC motor includes a semiconductor switching device connected in series with it in a DC power circuit. The switching circuit is turned on and off with a duty ratio variable as a function of motor load. A time constant circuit including a capacitor is connected in parallel with the switching device to develop a voltage which is compared with a reference variable between high and low levels in response to the exceedance of the varaible reference. The switching device is turned on when the voltage developed by the capacitor is higher than the lower reference voltage to energize the motor, and is turned off when the capacitor voltage is lower than the higher reference voltage to de-energize the motor. The on-duty period of the motor is variable as a function of a motor-load representative voltage developed in the switching device during its turn-on period and the off-duty period is variable as a function of a counter-electromotive force generated in the motor as inversely proportional to motor load.

대표청구항 ▼

A speed controller for a DC motor comprising: a semiconductor switching device connected in series with said motor and responsive to a switching control signal applied thereto for switching power to said motor from a voltage source on and off, whereby a current having an amplitude proportional to th

A speed controller for a DC motor comprising: a semiconductor switching device connected in series with said motor and responsive to a switching control signal applied thereto for switching power to said motor from a voltage source on and off, whereby a current having an amplitude proportional to the amount of load on said motor flows in said motor when said power is switched on and a counter-electromotive force inversely proportional to said motor load is generated by said motor when said power is switched off; and switching control means responsive to the amplitude of said current and said counter-electromotive force for generating said switching control signal which turns on said semiconductor switching device for a duration proportional to the amplitude of said current and turns off said switching device for an interval proportional to said counter-electromotive force, said switching control means comprising: a time constant circuit including a capacitor connected in parallel with said switching device so that said switching device establishes a discharge circuit for said time constant circuit when the switching device is turned on and allows said capacitor to develop a first voltage when the switching device is turned off; a variable reference source for generating a reference voltage variable between high and low values in response to said switching control signal; and means for comparing said first voltage with said variable reference for generating an output selectively having high and low voltage levels dependent on the relative value of said first voltage to said variable reference and applying said output to said switching device and to said variable reference source as said switching control signal.