| 摘要 |
PURPOSE:To provide a motor drive circuit for motor vehicle in which overcurrent of motor is prevented under overload. CONSTITUTION:Power is fed to a motor M through motor circuits CP1, TR1-TR4 which compare an accelerator voltage with a triangular wave to produce a driving signal having pulse width variable with the accelerator voltage for PWM controlling power transistors TR1-TR4. The motor control circuit further comprises a current limiting circuit Rs for detecting a battery current being fed to the motor M and lowering the driving signal when thus detected battery current exceeds a reference level, a CP 2, and rotational speed control circuits 2-4 for detecting the rotational speed of motor M and varying the accelerator voltage based on thus detected rotational speed to perform constant speed control of the motor M. The rotational speed control circuit is provided with an overload prevenstion control circuit 10 for controlling the reference level of the current limit circuit when the rotational speed of motor is lower than a predetermined level and lowering the battery current value. |
