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The Vdrive voltage in the below circuit is supplied from rectified mains, including filter caps. The problem is that filter caps for this kind of application get expensive really fast, so I am considering including only two 1000 uF caps.

With that, there would be up to 20 V ripple on Vdrive at max load.

My question is if I can get away with that. I am especially worried about the driver circuit for the high side IGBTs. Would this circuit be able to switch the transistors in spite of the high ripple?

circuit

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  • \$\begingroup\$ It looks like to work. I haven't check the numbers in the datasheet, but looked at the example circuit in the datasheet. Meantime, what I can guess is: Are you building a H bridge to control the direction? \$\endgroup\$
    – jay
    Commented Nov 22, 2021 at 21:24
  • \$\begingroup\$ @jay yes, the purpose of this H Bridge is to control the direction. I also intend to use it for controlling a motor's speed with PWM. \$\endgroup\$
    – rubemnobre
    Commented Nov 22, 2021 at 21:32
  • \$\begingroup\$ So, you are controlling PWM by SD, just curious? What you would check is the drive capability (V & I) of HO, LO, HO-VS for Q1, and LO-COM for Q2, The device high-side drive circuitry is interesting. The internal block diagram does not detail it. \$\endgroup\$
    – jay
    Commented Nov 22, 2021 at 21:47
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    \$\begingroup\$ Hey, I read the datasheet, looking for how VB gets biased, but could not find it. You may want to test the device on a bread board. Meantime, in my experience, it is better to synchronize to the line, though it depends on your applications. That case, there are better solutions. You can use thyristors, too. \$\endgroup\$
    – jay
    Commented Nov 22, 2021 at 22:19
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    \$\begingroup\$ Oh, the PWM can be synchronized to the Line frequency. That removes aliasing with the line frequency. Think about it, since you cannot give enough filtering, you possibly see harmonics, could be any frequency noticeable. \$\endgroup\$
    – jay
    Commented Nov 22, 2021 at 22:41

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