| 摘要 |
PURPOSE:To contrive a device to be less influenced by the nonuniformity of each phase current and stabilize the action of the driving control of a compressor, by controlling the operation of the compressor with the average value of at least two of three-phase power source currents. CONSTITUTION:CT transformers 1, 2 detect the currents of the phases R and S of a three-phase power source, respectively. The phase currents detected by the CT transformers 1, 2 are converted to DC voltage by respective rectifying and smoothing circuit 3, 4 each composed of a diode bridge, a capacitor, and a resistor. An averaging circuit 5 is composed of two operational amplifiers for impedance-converting and two resistors connected to the amplifier outputs, and produces the average value of the voltage input to the two operational amplifiers. In other words, the voltage corresponding to the average value of the currents of the phases R and S is generated from the averaging circuit 5, and applied to the input port of an LSI 6. |
