Will excessive ripple voltage damage a speed controller?

9 years 10 months ago #29528565 by tallan
We at the college have designed a device to teach about speed controllers, pwm, and work. We have taken an exercize bicycle and attached a permanent magnet alternator driving off of the wheel. We have mounted 2 AX2550 controllers run by analog joysticks to control a boom/stick/rotate function similar to a hydraulic excavator. The controllers are running 2 linear actuators and a motor/worm drive swing function.

We have had one of these controllers fail twice now. Here are the specs

12v permanent magnet alternator without a voltage regulator
The linear actuators top out at 12 amps
The voltage from the alternator can reach 20 volts if a studenty pedals hard
There is a 12v battery connected to the control wires to keep the low current side alive but the high current functions drive with only the power from the alternator.

Twice now when we got on to start pedalling, there is a large draw from the alternator. Both times it seems that the controller has a short circuit. I have replaced the first failed controller but it has happened again. Here is my question

I see that the controller is supposed to be good for up to 50vdc and 120A. Our pedalling shouldn't reach these values ever. Is it possible that the lack of a storage battery is causing the controller to fail? Could excessive ripple voltage from an alternator fail the high current side of the controller? I am hesitating to install a battery in this circuit because I want students to feel the power being drawn from the pedals in the form of work being done.

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