Direct voltage converting method for inverter, involves controlling switching using function from values representing voltage and point, and determining variation and difference between thresholds based on value representing another voltage

摘要

The method involves opening and closing an electrical contact between an output (12) and a direct voltage line (3) for creating a variable output voltage between the output and a reference point (16) e.g. neutral. The voltage is measured for determining a value representing another output voltage. Switching is controlled using a hysteresis function having hysteresis negative and positive thresholds, from values representing the voltage and a variable reference point. Variation and difference between the thresholds are determined based on the value representing the latter voltage. Independent claims are also included for the following: (1) a direct current converting device comprising a commutator (2) an inverter comprising an alternating voltage converting unit.