| 摘要 |
PURPOSE:To detect an input current flowing into a switching regulator to protect the regulator when an over-current flows by supplying a DC motor current to an inverter circuit from the switching regulator. CONSTITUTION:When a motor current becomes an over-current, a second integration circuit 58 detects a voltage value between a resistor 56 and an inverter circuit 16, integrates a motor current with a time constant tau2 and provides an output to a current amplifier 64, amplifies integrated motor current and provides an output to PWM 44. In the PWM 44, pulse width of a control pulse to be outputted to a transistor 30 is changed depending on a motor current value. Moreover, when an input current becomes an over-current, it is inputted to a first integration circuit 46 through a second transformer 28, an input current is integrated based on a time constant tau1 and outputted to a current amplifier 64. The integrated input current value is amplified and is sent to PWM 44. Thereby, width of control pulse to be outputted to the transistor 30 is changed depending on an input current value. |
