Hello. My friend has bought a sailboat which has an electric auxiliary motor. The control unit has got water in it and is damaged beyond all hope of repair. The motor and controller are designed to power a car and are very sophisticated and I think that a boat motor probably needs much less sophisticated control. To buy a new controller would cost several thousand dollars, and I want to try to build a new controller for him instead.
This is the motor:
https://www.evworks.com.au/hyper-9-isIt's a three phase permanent magnet assisted synchronous reluctance motor. I believe it needs to be driven by some type of three phase AC. It has encoder outputs, but I haven't been able to investigate exactly what sort of signal they put out.
Could I drive this motor with a three phase square-wave voltage of the kind normally fed to BLDC motors? What would be the down-side of not feeding it a proper sine wave?
I think that I should commutate the voltage to the windings according to the rotor position indicated by the encoders, keeping the angle constant at the position of maximum torque. Would I control the speed of the motor by varying the voltage applied using pulse width modulation?
The batteries are currently rigged to produce 100V and the current that I will need to control might be up to 500A. I'm aware that I will need some sort of transistor switches (probably IGBTs) to control the voltage to the motor. I'm hoping to salvage them from the old controller or else buy them on eBay.
What things do I need to consider in the design of my controller?
Please be gentle, I don't have formal training in electronics. The controller doesn't have to be 100% efficient and it doesn't have to realize the maximum power that the motor and batteries are capable of, it just has to get the boat moving enough to move around in enclosed waters.
Thanks so much. Any help would be greatly appreciated.