| 摘要 |
PURPOSE:To effectively prevent a switching element which forms a semiconductor power converter from failing in commutation by obtaining the minimum pulse width of a pulse signal for controlling the firing of the element. CONSTITUTION:The outputs of a modulation wave frequency instructing circuit 1, a modulation amplitude instructing circuit 2 and a phase instructing circuit 3 are supplied to a modulation wave signal generator 5, and the output of a carrier frequency instructing circuit 4 is supplied to a carrier signal generator 6. A comparator 7 inputs the outputs of the generators 5 and 6, and supplies a PWM signal to an excessively small pulse preventing circuit 100. This circuit 100 holds the level of the pulse during the prescribed time even if the excessively small pulse is generated, and outputs a PWM signal of the pulse width which might not cause the commutation failure. |
