| 摘要 |
An electric motor speed controller circuit comprises at least one power transistor (12) (or thyristor or triac) in series between the motor (14) and a power supply (10) to form a power circuit such that current flows between the power supply and the motor through the transistor only when a signal current is supplied to the base (12a) of the transistor and which further comprises a control circuit (F) for supplying a signal to the base of the transistor which signal is pulse width modulated so that the width of the pulse is proportional to the value of a variable resistance (20), inductance or capacitance of the speed control. Such pulse width modulation is performed by comparing a voltage proportional to the variable resistance, capacitance or inductance of the speed control with a sawtooth or triangular waveform and providing pulses when such voltage is higher than the waveform voltage. The circuit and method of use thereof is particularly suitable for use with motors used to power electric vehicles. <IMAGE> |
