| 摘要 |
<p>PURPOSE:To protect switching elements from being broken, by providing a contact between the neutral point of the primary winding of a power transformer and a DC positive terminal and opening the contact upon application of overvoltage onto either of a pair of switching elements. CONSTITUTION:A gate signal generating circuit 6 causes a pair of switching elements 91, 92 connected to the primary side of a power transformer 5 to be in a high frequency operation. A gate control circuit 10 controls switching elements 131-134 connected to the secondary side of the power transformer 5 thus controlling a power switching element 2 connected in series with a drive motor 3. Upon application of overvoltage onto either of the pair of switching elements 91, 92, an overvoltage detecting circuit 18 turns the power switching element 2 OFF and opens a contact 15. By such arrangement, the switching elements can be protected.</p> |
