| 摘要 |
PROBLEM TO BE SOLVED: To provide a motor driving apparatus including compact and low-cost overvoltage protection means for protecting an apparatus from momentary overvoltage.SOLUTION: In an overvoltage protection circuit 50, when a control unit 40 turns off transistors Q3a to Q5b of both upper and lower arms at occurrence of overvoltage, the overvoltage is divided and applied to respective both ends of two switching elements connected to each other in series and overvoltage applied to one switching element (transistors Q3a to Q5b, diodes D3a to D5b) is reduced to a half of voltage applied when either one of the switching elements is actuated, so that the switching elements can be protected from breakage. Further the control unit 40, when a detection value of a second voltage detection unit 43 is lowered to a predetermined value or less during control of overvoltage, electrically intercepts a power supply line 801 through a first switch 11 so that a DC voltage Vdc is not applied to the respective switching elements of the upper and lower arms to protect the switching elements from overvoltage. |
