SWITCHING POWER SUPPLY CIRCUIT

摘要

PROBLEM TO BE SOLVED: To stabilize a DC output voltage and at the same time reduce the harmonic components of an input current accurately and stably over an entire operation range, to improve an input power factor by outputting a signal that is obtained by amplifying a current detection signal with a gain that changes continuously according to the change in a DC output voltage. SOLUTION: A DC output voltage error amplifier 71 obtains the error between a DC output voltage detection signal and a DC output voltage command signal, amplifies the error, and outputs an output voltage error amplification signal. A variable gain amplifier 72 outputs an input current command signal according to the output voltage error amplification signal and an input voltage detection signal. Also, a continuous type detection current gain adjustment circuit 81 inputs a current detection signal and a DC output voltage detection signal and outputs a detection current gain adjustment output signal. A current error amplifier 75 where the detection current gain adjustment output signal and an input current command signal are inputted amplifies the error between both of them and outputs a current error amplification signal. A PWM pulse signal generation circuit 76 inputs the current error amplification signal and outputs a PWM pulse signal for opening and closing a switch element 32.