Patent ID: 9559630
Date: 2017-01-31
CPC Classifications: H02P

Claim:
1. A method for controlling an inverter, the method comprising: measuring a rotor speed of a motor coupled to the inverter; measuring an observed current level at a fundamental frequency for the inverter; accessing a stored representation of first current level, at the fundamental frequency, versus rotor speed output at which the total harmonic distortion level is less than a threshold total harmonic distortion level, where the total harmonic distortion level can be expressed as a percentage and where the total harmonic distortion level is estimated based on amplitude of one or more harmonic frequencies compared to an amplitude of the fundamental frequency; enabling the inverter to use SVPWM (space vector pulse width modulation) if the observed current level is less the first current level for the measured rotor speed and for the fundamental frequency; and enabling the inverter to use DPWM (discontinuous pulse width modulation) if the observed current level is greater than or equal to the first current level for the measured rotor speed and for the fundamental frequency.