| 摘要 |
PURPOSE:To detect a current with a simple configuration by detecting any of the conduction rate of an inverter, the current or a DC voltage of a brushless motor, and calculating the current value not detected from a relation equation of the above three state amounts. CONSTITUTION:A current detecting shunt is arranged in a DC unit of an inverter, and an instantaneous current IDC1 and an average current IDC2 are respectively inputted to the distributors 45 of respective controllers 4 and an A/D converter 41 through an operational amplifier OP having a surge absorbing filter consisting of a resistor R1 and a capacitor C1 and a smoothing filter consisting of a resistor R2 and a capacitor C2 at the output terminal. A position detection signal is applied to the distributors 45 through the waveform shaper 43 of the controllers 4, and a PWM modulation wave generator 44, and supplied to a base drive circuit 5. The reduction rate Df of the inverter is determined by a calculator 42. Then, the motor current IM can be obtained by the detection of the DC current IDC from a relation equation IDC=K1ImDf of the motor current Im, the DC current IDC and the conduction rate Df. |
