Hello,
Does any one has built this IGBT gate driver circuit?
How do I do using the iso5500EVM to drive single 100A, 1200V IR or Ixys IGBT?
Secondary,
For driving a high-power IGBT safely, there is a high carrier frequency modulated into baseband tightly together.
In the iso5500EVM, there is no any information mentioned about it.
Could you please give me mor information for a testing circuit using the iso5500EVM?
Thanks a lot.
Hi Richard, here is a PWM circuit for your needs. You can use a lower cost quad op-amp with rail-to-rail capability though, such as the LM614 (I think)..
U1 is configured as an integrator and U2 as a comparator. For good stabiliity use a low-cost 2.5V reference (i.e.REF2925). The comparator hysteresis is given with Vhys = VF1 x R2/R3 and is symmetric around Vref. The upper and lower limit of this hysteresis window determine the switching levels of the comparator. When the comparator output switches it forces the integrator to integrate up- or downwards. Once the integrator output voltage hits the comparator switching levels the comparator output changes. The square wave and the triangular wave are swinging around Vref and close to the supply rails (see waveforms below).
U4 is also configured as a comparator without hysteresis. Here your analog input voltage is compared to the triangular voltage, thus resulting in the final PWM output. In order to center a single-ended input voltage (referenced to ground) around Vref, I used a difference amplifier (U3) with a gain of 0.8 (G = R4/R6) and biased it with Vref. Its output voltage is given with: VF4 = (VF3 - Vref) x R4/R6 + Vref. This way a 5V input voltage swing is reduced to 4V and centered around the 2.5V reference at the output (again see waveforms below).
Hope this helps. Regards, Thomas
