| 摘要 |
A.C. motor powering arrangement with means for limiting the power delivered to an A.C. motor in which: the A.C. motor (18) is connected into a transistor bridge (6) which includes a small current sensing resistor (24); the bridge (6) is operated to supply alternating half cycles of current to the A.C. motor (18) and resistor (24), and the voltage drop across the resistor (24) is compared in a comparator (26) with a reference voltage (Vo-aVin) which is equal to a fixed voltage minus a percentage of the bridge D.C. supply voltage, and when the voltage drop across the resistor (24) exceeds the reference voltage (Vo-aVin) a gate means (30, 32, 34) is closed to render the bridge transistors (10, 12, 14, 16) non-conductive. |
