| 摘要 |
PURPOSE:To control the suppression amount of a low order harmonic wave component to the optimum value and to simplify the construction of a control circuit by forming a basic frequency triangular wave and a pulse carrier triangular wave with the basic frequency of an oscillator as a reference. CONSTITUTION:An output of an oscillator 1 is supplied to triangular wave generators 2a, 2b and a Johnson counter 3. Means for synchronizing with a basic frequency by the generator 2b, the counter 3 and an amplitude regulator 6 connected with them to form a pulse carrier triangular wave having a period faster than the basic frequency and amplitude-modulated is formed. Means for forming a basic frequency triangular wave having the same period as the basic frequency and amplitude-modulated by the generator 2a, a set voltage 8, a multiplier 4 and an inverting amplifier 5 is formed. The output of the regulator 6 is input to comparators 7a, 7b which respectively compare it by the outputs of the multiplier 4 and the amplifier 5 to output a drive signal of a semiconductor switch. |
