in a pulse width modulation controlled three - phase voltage - source inverter having three legs , each leg including two transistors coupled serially between the terminals of a power source and providing a respective drive output , each leg further including a shunt resistor between one of the two transistors and one of the terminals , in which control pulses are applied to each leg during a sequence of pulse periods , and the inverter has a neutral current , a method for determining the phase current for each phase . the method includes the following steps . first , it is determined which two legs have the longest on time for the lower power transistors . the current through the shunt resistors for the determined legs is determined , to obtain a value representative of the phase current for the legs . finally , the phase current for the leg not sampled during the sector is derived by subtracting the determined phase currents from the neutral current .