| 摘要 |
PROBLEM TO BE SOLVED: To provide a high quality PWM pulse generator of a three-level NPC inverter by adding a simplified circuit to the PWM pulse generating circuit of two-level. SOLUTION: In this PWM pulse generating circuit of three-level NPC inverter for connecting in series four switching element per phase, providing two rectifying elements for clamping to the neutral point and generating the PWM pulse signal of four switches from a command voltage, a comparator 4 for generating a PWM pulse phase, a first switch 7 for distributing the PWM pulse signal to the four switch elements and a control signal (3) for controlling such distribution are provided. Thereby, when the modulation rate of the command voltage 1 is small, the control signal and command voltage are switched for each period of carrier and the pulse for outputting a positive bus voltage to a phase voltage output terminal, and the pulse for outputting a negative bus voltage are switched and outputted for each period of carrier. |
