AC induction motor

Discussions regarding the Field Oriented Control (FOC) implementation on the VESC.
rew
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Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.
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Re: AC induction motor

Postby rew » 30 May 2018, 07:01

In vesc_tool, on the terminal tab you can type foc_openloop <somecurrent> <someRPM>.

So when you have your bog-standard 1440RPM 460W asynchronous motor, you could try feeding your VESC with 30V and typing: foc_openloop 2 300 . The 460W specification means that the max current for this motor is 2A (@230V = 460W). Because you cannot achieve the voltage needed for operation at the net frequency of 50Hz, you'll have to restrict yourself to 5Hz, or 300 RPM. This motor runs at electrical cycles per revolution, so it should run at just below 150 RPM in real life. Hmm. That "Just below" with a load that causes the nominal 2A to run should give a slip that is the same as when it is running at net frequency. So the "just below" will translate to "about 60 below". So the motor will not be able to run as efficiently as with the voltages it was designed for. Normally it will run at around 1440/1500 = max 96% efficiency, and now it will only run at max 60% efficiency. (not taking copper losses into account!).

Demonstrating this "in real life" is something that might help people get motivated to work on the firmware for this.


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