| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive compensation circuit having a simple constitution without using any expensive detector for detecting the 1/2 level of a DC voltage. SOLUTION: An output voltage compensating circuit is provided with upper and lower arm-on detecting circuits 11 and 12 and an upper and lower arm-off section detecting circuit 15. The compensating circuit is also provided with data selectors 13, 14, and 16 which respectively select an upper arm-on detecting signal when a PWM command pulse is an upper arm-on command, the inverted signal of the PWM command pulse when upper and lower arm-off are detected, and a 1/2 frequency dividing clock when lower arm-on is detected, a pulse difference detecting circuit 6 which detects the output clock of the data selector 16 corresponding to the difference between the PWM command pulse and the output signal of the data selector 14, and an up-down counter 7 which counts the output clock of the circuit 6 in accordance with the difference. In addition, the compensating circuit is also provided with a flip flop 8 which is operated by the digit up/down signals of the counter 7 and a driving circuit 10 which generates the driving signal of an inverter 2 based on the output signal of the flip flop 8. |
