Patent ID: 7190597
Filing Date: 2007-03-13
Classification: H02M

Abstract:
1. A modulation method for a pulse width modulator in the inverter section ( 11 ) of a frequency converter provided with a voltage intermediate circuit, said frequency converter comprising a single-phase mains bridge ( 10 ) to be connected to a single-phase alternating current source (U L , N), a direct-voltage intermediate circuit and a controlled load bridge ( 11 ) for feeding a three-phase alternating voltage (U R , U S , U T ) of varying frequency and amplitude into a load ( 13 ), for controlling the semiconductor switches of the inverter section, in which low-capacitance direct-voltage intermediate circuit the waveform of the intermediate-circuit voltage in a normal load situation follows the absolute value of the supply network voltage, characterized in that, in the modulation, an estimate value of the intermediate-circuit voltage is used to control the semiconductor switches of the inverter section.