Magnetron switch-mode power supply circuit, e.g. for microwave oven - controls rectifier so that only one magnetron is driven by mains power at any time

摘要

The unit supplies two magnetrons (6.1, 6.2). A mains driven rectifier (1) supplies a direct current to a step-up transformer (3,4) via an energy storage coil arrangement (2). The transformer (3,4) has a primary winding (10) and at least one secondary main winding (13). The current through the primary winding (10) is controlled by two semiconductor switches (7). These are alternately driven by a drive unit (30) with 50-100 per cent overlap. The secondary winding (13) has two parallel connected opposing rectifier diodes (51, 52) whose cathodes are connected. The cathode of the first magnetron (6.1) is connected to the anode of a third rectifier diodes (53). This diodes cathodes is connected to the anode of the first diode (51). The cathode of the second magnetron (6.2) is connected to the anode of a fourth diode (54) whose cathode is connected to the anode of the second diode (52). The anodes of both magnetrons (6.1, 6.2) are connected to each other and to the cathodes of the first and second diodes (51, 52). Alternatively a rectifier arrangement (22) may be connected to the secondary winding (13). This provides a direct current fed separately to the magnetrons (6.1, 6.2) via different semiconductor switches (23, 24). The switches (23, 24) are alternately switched by a controller (25) for equal or unequal on-times. ADVANTAGE - A simple, reliable, circuit which meets requirements for high efficiency, and low interference.