Regen LiFePO4 with PM motor

arn0 said:

When in generator (powered by the Diesel engine at 3200 rpm), the PMG132 might turn at approx up to 5800 rpm (reductor between the 2 engines). So I suspect it can generate voltage around 100 V into the controller.

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Hi arn0,

I think this will be a big problem. All of the available controllers for brushed PM motors are basically a buck converter for motor mode and a boost converter for regeneration. In motor mode, V_motor < V_bat. In generator mode, V_motor < V_bat. The same. If the motor voltage (as a generator) exceeds the battery voltage, the controller will fault, meaning shut down to protect itself. When the generator voltage is too high the controller has no means to regulate it.


Options:

• Don't run the generator that fast.
• Use a different controller for the generator designed to operate with high voltage input.
• Change to wound field machine.

I don't think you will be pleased with the durability and service life of that motor running long periods at high RPM. 5800RPM may exceed the mechanical limit for that armature.

Interesting project. Where are you located (what nationality)?

major