all home built solar system

Author	Message
wiseguy Guru Joined: 21/06/2018 Location: Australia Posts: 1267	Posted: 02:10am 30 Apr 2021         nickskethisniks said   What I also read was negative bias and gate drive supply above 12V is not necessary wanted because of the higher energy needed for making the transitions. It's low impedance you want, but only with good PCB layout, I think the 20-25khz is still quite forgiving. What you probably want in a new design is dedicated Roff and Ron resistors, MOSFETs have different toff and ton timings so why not using them, to get the same timing. Also ssing the parallel diode approach could possibly stress the driver. - we could discuss this for 1000 pages - 1000 pages?? I wont be discussing this further after this post. I always only use 12V for Mosfet drive. I always use a 4R7 (or sometimes smaller) with parallel diode, but depending on application I may not install the speed up diode. In my inverter each group of 4 x HY4008 use just ~ 15mA of average drive current. With all 16 FETs being driven the total including all the wasted power of negative bias sucks a measly total current of just 58mA from the 12V supply, when including the idling current of the 4 x opto driver ICs and the small isolated dc to dc converter it was 98mA total. I don't think this energy level will overstress the drivers too much. My inverter Gate Waveforms are reproduced here for interest. Please note the 100nS time scale and the total absence of gate bounce and ringing & oscillations.  For interest here here is how my waveforms used to look before finding the cure that solved both my 12V & 48V inverter issues. Edited 2021-05-01 09:02 by wiseguy