| 摘要 |
PURPOSE:To prevent the influence to an inverter output due to the variation in a DC input voltage by detecting the input voltage and amplitude-modulating a triangular wave for PWM-controlling in response to the detected voltage. CONSTITUTION:A single-phase AC power source 1 is rectified through a rectifier 2 and a smoothing condenser 3 to a DC voltage, which is applied to a single- phase inverter 4 to be converted to a sinusoidal AC of arbitrary frequency, and then supplied to a load 5. The inverter 4 forms a PWM signal by a comparator 9 through a PWM control carrier oscillator 6, a triangular wave generator 7, and a sinusoidal wave reference generator 8, and forms the ON/OFF signal of the inverter 4 through a logic circuit 10. In this case, a DC input voltage detector 11 is added, and input to a triangular wave generator 12 which can vary its slope as an amplitude modulation signal. Thus, when the DC input voltage is high, the ON pulse of the inverter 4 is reduced, while when low, the ON pulse is increased to eliminate the influence of the input voltage to the inverter output. |
