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8

Q1

ON

D2

Q2

OFF

DC+ BUS

DC- BUS

DC+ BUS

Q1

OFF

D1

D2

DC- BUS

Q2

OFF

Figure 7: Q1 conducting

Figure 8: D2 conducting

Also when the phase current flows from the load back to the inverter (see Figures 9 and 10), and Q4

swings from the positive DC bus voltage to the negative DC bus voltage.

A common problem in today’s high-power switching converters is the transient response of the switch

node’s voltage as the power switches transition on and off quickly while carrying a large current. A typical

half bridge circuit is shown in Figure 6; here we define the power switches and diodes of the inverter.

If the high-side switch (e.g., Q1 in Figures 7 and 8) switches off, while the phase current is flowing to a

load, a current commutation occurs from high-side switch (Q1) to the diode (D2) in parallel with the low-

DC bus voltage to the negative DC bus voltage.

Q1

Q2

D1

D2

DC+ BUS

DC- BUS

Input

Voltage

To

Load

Figure 6: Half Bridge Circuit

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