catphish / stm32_vfd

A 3 phase motor controller implemented on an STM32

STM32 variable frequency drive controller

This project aims to be an open source torque controller for AC induction motors.

Hardware

This software runs on an STM32. In addition, the following hardware is required:

• 6 x IGBT or MOSFET
• 6 x Isolated FET drivers
• 3 x Hall effect current sensors
• Rotary encoder
• A large film capacitor

An example schematic can be found here: https://nutty.tk/inverter3.pdf

Overview

The software generates a 3-phase output using PWM. The frequency and voltage are adjusted to create a torque proportional to the "throttle" input.

Algorithm

The algorighm is very simple and is based on setting the slip of the motor. The output frequency is the shaft frequency plus a slip, where the slip is proportional to the throttle input. The current is controlled to keep it proportional to the slip (up to the input voltage).

Testing

So far this has only been tested up to 1A @ 48VDC on a 250W motor. It is my hope that this should scale to larger builds for electric vehicle use. More experimentation will follow.

My low power test build: https://imgur.com/a/IR173Ng

Field oriented control

Previous iterations of this code have implemented FOC, however overall the simple slip based algorithm has produced better results so far.

stm32_vfd's Issues

Could you please update the link to the schematic?

The link to schematic seems broken.