AC converter in direct current and electric motor controller

摘要

An AC converter in direct current, comprising: a rectifier (2), connected to a single phase AC power supply (1) through a reactor (5); two capacitors (6, 7), connected in series between the output terminals of the rectifier (2); a first switch, connected between an input terminal of the rectifier (2) and a connection point of the capacitors (6, 7); a second switch, connected between the other input terminal of the rectifier (2) and the connection point of the capacitors (6, 7); diodes (10, 11), connected inversely in parallel with the capacitors (6, 7); a voltage detector (21), which detects the voltages of the capacitor terminals (6, 7); a current detector (22), which detects a single-phase current input from the single-phase alternating current power supply (1); and a control means (20), which drives and controls the first switch and the second switch, in which the control means (20) drives and controls the first switch and the second switch such that the terminal voltages of the capacitors (6, 7) are set and the power factor of the power supply is improved using an active power component and a reactive power component obtained by conversion of the detection results of the current detector (22) and of the detection results of the voltage detector (21), characterized in that the control means (20) converts the detection result of the current detector (22) into an active power component current and a component current of reactive power, and performs a control such that the voltages of the capacitor terminals (6, 7) are fixed using the current of the active power component, the control means (20) includes a means (32a, 32b) that eliminates a pulse component that is twice the frequency of that of the single-phase alternating current power supply (1) and that is included in the current of the active power component and the current of the reactive power component, and the control means (20) drives and controls the first switching means (3) and the second switching means (4) based on an active power component (Ip) and a component of reactive power (Iq) which are components that remain after eliminating the pulse component of the current of the active power component and the current of the reactive power component, such that the converter voltage between the input terminals of the rectifier 2 becomes a three-level cutting voltage.