| 摘要 |
<p>PURPOSE:To detect a current value for the bidirectional rotations of a motor by mounting a current detecting resistor between a semiconductor switch of a signal common lie side and a signal common line, and connecting an ideal rectifier by a differential amplifier with a semiconductor switch side terminal. CONSTITUTION:FETs 2, 3 are fixed to OFF state, and FET4 is fixed to ON state, and FET1 is switched by pulse width modulation. An ideal rectifier 19 detects the voltage between the terminals of a resistor 14 during the ON period of the FET1, the voltage is then inverted and output as a detected current value. A flywheel current is flowed through the FET4, the resistor 14, a current detecting resistor 13 and a diode 6 during the OFF period of the FET1. At this time, the current flowed to the resistor 14 is detected, but the current flowed to the resistor 13 is ignored by an ideal rectifier 20. Accordingly, the current value can be accurately detected.</p> |
