| 摘要 |
PURPOSE:To make an insulating circuit unnecessary, by a method wherein either one output signal between respective output signals of short-circuit preventing circuits of upper and lower arms is selected in accordance with the directions of current to detect an output voltage. CONSTITUTION:Transistors T1, T4 of a voltage type inverter 1, supplying electric power to a load 2, are driven through short-circuit preventing circuits 5A, 5B and driving circuits 4A, 4B by driving signals from a switching pattern generating circuit 7. The ON/OFF signals (an output A) of the switching element T1 of the upper arm and the ON/OFF signals (output B) of the switching element T4 of the lower arm are inputted into a data selector 8 to detect the voltage of the inverter 1 while the direction of current is decided by a comparator 9 and the result of the decision is used as the control signal of the data selector 8. According to this method, the ON/OFF signal is used by switching in accordance with the direction of the current; therefore, voltage detection may be effected during short-circuit preventing period and an insulating circuit may become unnecessary.
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