Patent ID: 6844700
Filing Date: 2005-01-18
Classification: H02P

Abstract:
1. An inverter apparatus for converting a DC power converted from an input AC power to an output AC power of a variable frequency and a variable electric power to drive an induction motor at a variable speed, comprising: a rectifying unit for converting said input AC power to said DC power, a filter capacitor for smoothing a DC output of said rectifying unit, an inverter unit having an input connected across said filter capacitor, an input current detector for detecting an input current to said inverter unit and a gate circuitry for driving said inverter unit; an excitation current detection unit for detecting an excitation current of said induction motor from an output signal of said input current detector, a gate signal for driving said gate circuitry and a reference phase command; a setting unit for setting a limitation level of said excitation current; a torque boost voltage command unit for producing a torque boost voltage command according to an inverter frequency command; and a torque boost voltage compensation unit for changing said torque boost voltage command so that said detected excitation current value is smaller than or equal to said limitation level; wherein said torque boost voltage compensation unit outputs a torque boost voltage compensation, a quantity of which is within a predetermined range.