| 摘要 |
PROBLEM TO BE SOLVED: To secure control range of a high-frequency output over a wide extent by forcibly terminating the turned-on time of at least one switching means in the course of self-exciting drive by means of a saturable current transformer. SOLUTION: In a power unit, DC input terminals (a) and (b) of a high-frequency inverter which outputs a high-frequency voltage across high-frequency output terminals (c) and (d), by alternately turning on and off a pair of switching means Q1 and Q2 through the self-exciting drive by means of a saturable current transformer SCT are connected to a rectifying power source RS, and at the same time, the power unit is provided with an output control means OCM which forcibly terminates the turned-on time of at least one of the switching elements Q1 and Q2 in a time shorter than the self-driving period of the current transformer SCT. When the on-time of the switching means Q2, which works also as the switching means of an active filter, is shortened and when the high- frequency inverter is a composite circuit type provided with an active filter, the DC output voltage of the active filter is dropped. |
