| 摘要 |
PROBLEM TO BE SOLVED: To provide a simplified constant-current power supply, having adequate steady characteristic and transient characteristic of the constant current control, and freely setting the frequency of a load current. SOLUTION: The instantaneous value detecting circuit 20 for detecting the instantaneous value of an output current, a current detecting circuit 7 for detecting the effective value or the mean value of an output current and a multiplying circuit 14 for outputting a signal obtained, by multiplying a comparison value between the effective value or means value of the output current detected with the current value detecting circuit 7 and the preset reference value with the reference sine wave voltage of the reference sine wave power supply 15 are provided, and the control circuit 25 controls to vary the on/off ratio of the main switching elements Tr1 to Tr4 to attain the matching between the instantaneous value of output current detected with the instantaneous value detecting circuit 20 with the output value of the multiplying circuit 14 and to set the output current supplied to the load 6, ..., 6 as a constant current. |
