CONTROLLER FOR IMPROVEMENT OF POWER FACTOR OF SINGLE-PHASE INDUCTIVE LOAD

摘要

PURPOSE:To attain the improvement to a power factor of high efficiency for the load by integrating the multiplication values of the current and the voltage by a pi/2 phase shift (given to either one of these current and the voltage) to decide the delayed and advanced power factors and controlling the make and the break of the load to a capacitor via a counter. CONSTITUTION:The load voltage or the load current underwent a pi/2 phase shift via a phase shift circuit 1 and the load current and the load voltage underwent no phase shift via the circuit 1 are processed by a multiplication circuit 2 and an integration circuit 3 respectively. No advance nor delay of a power factor are discriminated and determined when the integration output level of the circuit 3 is equal to zero. Then the advance and the delay of the power factor are discriminated and determined with the positive and negative polarities respectively. Then a counter circuit 6 performs the up- and down-counting actions of timing pulses via a make command discriminating circuit 4 and a break command discriminating circuit 5. A make bank designating circuit 8 controls the connection and cut-off of capacitors C1-C6 to the load. Thus the power factor is improved with high efficiency even with a comparatively small change of the power factor owing to the control carried out based on said delayed and advanced power factors.