1 EE462L, Spring 2014 H-Bridge Inverter (partially pre-fall 2009 version)

2 Fuseholders and10A fuses for DC input not shown in this photo 10µF input ripple current capacitor across DC input LC output filter (100µH, 10µF) To minimize your time and produce an inverter that works properly, it is very important that you follow the procedure in the lab document

3 Simultaneously View V GS for A+ and A− (use both scope ground leads) Asymmetrical firing circuit produces slow turn on, fast turn off, to provide blanking A − Off A + On You must avoid overlap in “on” times !

4 Once the H-Bridge is wired, you cannot simultaneously view V DS of A+ and A− (or B+ and B − ) on the scope because their source nodes are not the same But you can simultaneously view V DS on A+, and −V DS on A−, and then V DS on B+, and −V DS on B−, to check for overlap + V DS of A + – – V DS – + A + off A – on A + on A – off + V DS of B + – – V DS – + B + off B – on B + B – off

5 Loaded (with a resistor) and no output filter Load Voltage – No Filter. m a  1. !

6 With Filter Load Voltage – With Filter. m a  1. Very Effective! !

7 The Filter Has a Cutoff Frequency of About 5kHz + Vac output – 10µF, 50V, bipolar, high-frequency capacitor 100µH, 9Aor 10A inductor Point “a” in H-bridge Point “b” in H-bridge a b + Vac output − symbolic

8 Transfer Function + Vac output − + Vac input − L = 100µh C = 10µF R = 12, 8, or 4Ω

9 Your circuit

10 Effect of the carrier frequency

11 Effect of the carrier frequency