| 摘要 |
A power conversion device (10) of the inverter type for three-phase DC motor (12) includes three parallel pairs of output transistors (Q1 to Q6) between a power supply voltage (20) and the ground potential (22). These pairs provide three upper-stage transistors (Q1, Q3, Q5) and three lower-stage transistors (Q2, Q4, Q6) with diodes (D1 to D6) being coupled thereto. Drivers (24) are connected to the transistors (Q) respectively. A capacitor (C1) for each upper-stage driver (24-1) has an electrode coupled to the power supply voltage and the other electrode coupled to the ground through a corresponding lower-stage transistor (Q2). A controller (30) controls the upper- and lower-stage drivers (24) in response to a pulse width modulation (PWM) signal (Sp) generated by a PWM generator (32) to represent a desired motor rotation speed. The upper-stage transistors (Q1, Q3, Q5) are PWM-driven so that each one turns on and off repeatedly during a 120-degree electrical angle period. While one upper-stage transistor (Q1) is PWM-driven during a 120-degree period, a corresponding lower-stage transistor (Q2) turns on in response to a reverse-phased pulse at the beginning of this period, thereby charging the capacitor (C1). <IMAGE> |
