Abstract: A voltage-type inverter device includes a 1/2 V(DC) detecting circuit (31) for detecting a voltage between one end of a DC power supply (3) and an output from an inverter circuit (4); a voltage command value setting means (29) for commanding an output voltage from the inverter circuit; a first arithmetic means (32) for receiving the voltage command from the voltage command value setting means (29) and a detection voltage from the 1/2 V (DC) detection circuit (31) to produce an error voltage; a second arithmetic means (33) for receiving the error voltage from the first arithmetic means (32) and a voltage command value from the voltage command value setting means (29) to produce a voltage corrected command value; and a PWM signal generator (12) for receiving the voltage corrected command value from the second arithmetic means (33) and a frequency command value commanding a frequency command value from the inverter circuit to create a PWM signal for driving the inverter circuit.

Abstract: An inverter apparatus which controls an induction motor, has a forward converting unit, and can be combined with a power regeneration unit. The regenerative power converting unit has circuit arms, each being a parallel connection of a switching element and a diode, that are bridged. As a result, a DC voltage output from a forward converting unit that converts an input from an AC power supply into a DC voltage and outputs the DC voltage is inversely converted into an AC voltage and the AC voltage is returned to the AC power supply. A plurality of inversely converting units also are provided on the DC output side of the forward converting unit, and in each of those units, there are arms, each being a parallel connection of a switching element and a diode, that are bridged.

Abstract: An inverter apparatus having a compact design and a changeable heat sink. The apparatus includes a power module formed in a case having pairs of parallel sides and containing the respective main circuit semiconductor devices for converting an alternating current input into a direct current and then further into an alternating current of variable frequency. The heat sink also has pairs of parallel sides and interfaces with the case in a plane whereon the projections of the sink and the case are coextensive. The apparatus also has a body with pairs of parallel sides that fasten to the case and constitute part of the enclosure of the inverter apparatus. The body, case, heat sink and associated circuit elements have alignment structures that permit easy and reliable disassembly and assembly of the apparatus.