# Boost converter as power supply for H-bridge

I am looking for a way to be able to power the H-brirdge from a boost converter.

I have a voltage source of 13V to 15V and would like to boost that up to around 17V (accuracy isnt that important) at around 4A, to power only the H-bridge.

I currently have the following circuit (please note that there are MOSFET dirvers missing):

simulate this circuit – Schematic created using CircuitLab

If I simulate the following circuit in LTspice I get the following waveforms:

Green line represents the voltage coming from the boost converter and the blue line represents the current through R1.

Here, blue line represents the current through R1, while red (M2, M5) and light blue (M3, M4) lines represent H-bridge switching. There is 1$\mu s$ dead-time between H-bridge switching.

Can someone please explaing what is going on? And what do I need to do to make this work as intended?

edit:

If I get rid of the H-bridge and connect R1 directly to the output of the boost converter I get the deisred result (but I need H-bridge).

R1 represents a speaker.

• How did you intend it to work? – Andy aka Mar 13 '15 at 14:20
• @Andyaka Get a flat ~17V across R1 at all times. – Golaž Mar 13 '15 at 14:21
• But the H bridge is driven at 10kHz so that cannot happen. – Andy aka Mar 13 '15 at 14:41
• @Andyaka Yes I meant with minimum '0V times'. But anyway I get these weird triangle like waveforms from the boost converter and in the current through R1. – Golaž Mar 13 '15 at 14:45
• 40kHz is sufficient, but you'll need a digital compensator. Boost converters have a right half plane zero to watch for, and digital control has transport lag, but you might be able to get your loop closed at 3-4kHz if your micro is capable of the compensation calculations between A/D samples. It's not trivial to get a good response unless you're familiar with DSP and control theory. – John D Mar 13 '15 at 16:51