| 摘要 |
<p>A ROM circuit (14A,14B) produces output signals sin theta and cos theta from a phase signal generated from a PLL circuit (13), a first multiplier (15A,15B) multiplies a load current detection signal by the output signals sin theta and cos theta , an integrator (16A,16B) integrates the output signal of the first multiplier, and a sample-holding circuit (17A,17B) holds the integrated value to produce peak values of valid current component and invalid current component for constituting the basic wave component of the load current, a second multiplier (18A,18B) multiplies the peak values by the output signals sin theta and cos theta , and a PWM control circuit (11) for PWM controls the input current of the active filter with a harmonic current signal obtained as the difference between a basic wave current signal of the load current during a period of next one period of the single-phase A.C. power source and the load current detection signal by utilizing as the basic wave current signal of the load current of the period of next one period of the single-phase A.C. power source the basic wave current signal obtained by combining the valid current component and the invalid current component of the basic wave component outputted from the second multiplier (18A,18B).</p> |
