Hitachi RAS-E08H2A Service Manual page 44

3. Intelligent power module circuit (IPM circuit)
Fig. 3-1 shows peripheral circuits of intelligent power
module (IPM).
In the diagram, U + ,V + and W + are called the
"upper arm", U - , V - and W - , the "lower arm".
Fig. 3-1 System power module circuit (U + is ON, V - is ON)