| 摘要 |
PURPOSE: To reduce the variation of GND potential of a motor frame so as to reduce a leaked current by unifying the switching to any one hand such that all the power elements on plus side are off or on and that all the power elements on minus side are on or off, within the second PWM signal cycle. CONSTITUTION: Based on the processing of the command voltage of each U, V, and W phase and the voltage of triangular waves Vc as the first PWM signal in a triangular wave formation part 4, second PWM signals Eu, Ev, and Ew of each U, V, and W phase are generated. Within the cycle of these second PWM signals Eu, Ev, and Ew, the switching condition is made such that all the power elements Q1, Q2, and Q5 on plus side are off and that all the power elements Q2, Q4, and Q6 on minus side are on. Or, the switching condition is made such that all the power elements Q1, Q2, and Q5 on plus side are on and that all the power elements Q2, Q4, and Q6 on minus side are off. These switching conditions are unified to any one hand with a potential ripple measure processing part 1. Accordingly, the leaked currents can be reduced. |
