Hi, I'm currently building a motor controller for a 2.5HP DC Motor that runs at 6700 RPMs @ 130V DC. This motor was pulled from a treadmill, and I'm currently in the process of building an electric go-kart, which the motor will be used in. I'm controlling the polarity of the motor using a relay, and controlling the speed of the motor via PWM signal, with N-Channel MOSFETs. I am using 3x RJH2009 MOSFETs to drive the motor. I'm also using an ER506 Superfast recovery diode as a snubber. At 64V DC input to the motor, there are no noticeable EMF spikes measured at the positive terminal of the battery (96V, 2.5Ah Lead Acid Battery); however, when moving up to 72V, EMF spikes of up to 1000+VDC leak through... this is obviously a problem, and it's obvious my diode is not sufficient. I feel a bit limited in terms of diode options at this point. I tried an HVR-1X-3 high voltage, ultra fast recovery diode pulled from a microwave, which supports up to 12,000V Peak, but the EMF spikes worsened, appearing at only 48V input.
I'm looking for a way to eradicate the EMF and work my way up to 96VDC input to the motor. I've seen others use a capacitor and low resistance resistor in parallel, but coming across a capacitor that can handle voltage spikes of 1000+ V also seems difficult. I'm by no means an expert, and am still learning and doing this as a hobby, so please go easy on me. I'm always willing to learn.
Here's a rough schematic of what I have set up, let me know if more information is needed, and I will definitely provide it
I'm looking for a way to eradicate the EMF and work my way up to 96VDC input to the motor. I've seen others use a capacitor and low resistance resistor in parallel, but coming across a capacitor that can handle voltage spikes of 1000+ V also seems difficult. I'm by no means an expert, and am still learning and doing this as a hobby, so please go easy on me. I'm always willing to learn.
Here's a rough schematic of what I have set up, let me know if more information is needed, and I will definitely provide it