| 摘要 |
<p>Methods and apparatus are disclosed for determining the polarity of a current of a phase of an inverter, without using a current sensor. Switches of the inverter are connected in series and are switched on and off alternately such that a "dead-time" (62, 64) is produced between each switching during which both switches are off. By detecting the phase voltage (63) at the switches, and determining if that voltage is high or low during each "dead-period" (64), a signal is produced having a first value if the phase voltage (63) is high and a second value if the phase voltage is low. By determining the times of transitions between the first and second values, the invention is able to determine the polarity of the phase current corresponding to that phase voltage. The switches of the inverter are connected in series and respective freewheeling diodes are connected in parallel with the switches. <IMAGE></p> |
