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I am designing an H-Bridge for my arduino board to control a dc motor with PWM signals. I have a few issues with my design:

There is a spike current of 120A the first miliseconds of my simulation and then cools down as it is expected. Where does it come from and how do I fix it?

Also, how do I calculate the current I am getting through the motor based on Vcc?

Is there anything I have not taken in mind for my design?

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  • \$\begingroup\$ I would guess that current spike is due to charging of that capacitor. \$\endgroup\$ – Hearth Feb 4 at 0:16
  • \$\begingroup\$ This design is not workable for a bunch of reasons, including the fact that you can never turn the PFET's off with a 5v or 3v3 MCU and the lack of shoot-through protection. You should probably use an IC bridge or a circuit designed by someone aware of these issues if you need higher current than an IC bridge can handle. \$\endgroup\$ – Chris Stratton Feb 4 at 0:30
  • \$\begingroup\$ @ChrisStratton Could you point out how I can solve these issues? I do want to design it myself because my goal is to learn something by doing it, not just get it done with an IC from the shop. \$\endgroup\$ – atkristin Feb 4 at 0:48
  • \$\begingroup\$ Speaking ONLY of the spike, if you add a realistic series resistance to your power supply, it will likely reduce the spike to an acceptable level. \$\endgroup\$ – mkeith Feb 4 at 1:49
  • \$\begingroup\$ Typical way to do this would be with a dedicated H-bridge driver or two half-bridge drivers. Depending on the voltage, and switching frequency, etc, you MIGHT be able to do it with high-voltage logic. But you need to build in some dead time to avoid shoot-through. \$\endgroup\$ – mkeith Feb 4 at 1:51

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