| 摘要 |
A commutation control circuit for a conventional brushless DC motor. The circuit reduces power supply noise normally induced when current is switched from one pair of motor windings to the next. The motor conventionally includes a number of windings, each of which includes a terminal connected to a common center tap. The commutation circuit includes a first voltage-controlled current switch that is connected to the second terminal of a first one of the windings to control current through the first winding. Similarly, the second terminal of a second on of the windings is connected to a second voltage-controlled current switch. When a commutation is initiated to switch the current flow from the first to the second winding, the commutation circuit turns the second voltage-controlled switch fully on to quickly increase the current level through the second winding. A feedback network then monitors the current through the second winding and controls the current through the first winding via the first voltage-controlled switch so that the current through the first winding decreases at the same rate that the current through the second winding increases. Once the current through the first winding is approximately zero, the output of the feedback circuit is switched to the control terminal of the second current switch. <IMAGE> |
