| 摘要 |
<p>The circuit comprising a solid state switch connected in series with a motor and an AC supply. The switch is cyclically switched on and off so as to control the supply of current to the motor by controlling the proportion of time for which the solid sate switch is turned on. The magnitude of the current supplied is sensed and the value either of the sensed current or of a function of the current is generated. The period during which the switch is off in each cycle of the supply is controlled to minimise the calculated value, and thereby to increase the efficiency of utilisation of the supplied power.</p> |
