| Electronics > Projects, Designs, and Technical Stuff |
| 100+kW Motor Controller |
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| Psi:
--- Quote from: marcos_ on April 30, 2019, 03:27:09 am --- :wtf: --- Quote from: Psi on April 30, 2019, 12:35:22 am ---Regenerative braking? --- End quote --- Sure, in field oriented control math its just changing the sign of Iq current. That commands negative torque ("regen") --- End quote --- Interesting, i always thought re-gen required some sort of extra boost step-up system to allow pulling high current out of the motor at slow speed. |
| marcos_:
--- Quote from: Psi on April 30, 2019, 08:41:00 am --- --- Quote from: marcos_ on April 30, 2019, 03:27:09 am --- --- Quote from: Psi on April 30, 2019, 12:35:22 am ---Regenerative braking? --- End quote --- Sure, in field oriented control math its just changing the sign of Iq current. That commands negative torque ("regen") --- End quote --- Interesting, i always thought re-gen required some sort of extra boost step-up system to allow pulling high current out of the motor at slow speed. --- End quote --- You use the motor windings as inductors, the circuit has already the topology to boost. ^random image from the internet, it doesn't represent our motordrive Anyway at low speeds there is not much power available, power = torque*speed so any effort spent in low speed regen performance doesn't give you much gains |
| mac.6:
What is the point/target of this project? just hobby/hacker? Startup with resell exit strategy? Real OEM product? I can't see from the hackaday page... |
| marcos_:
--- Quote from: mac.6 on April 30, 2019, 02:00:50 pm ---What is the point/target of this project? just hobby/hacker? Startup with resell exit strategy? Real OEM product? I can't see from the hackaday page... --- End quote --- We get most revenue from startups needing a quality drivetrain. Helping the enthusiastic crowd and making the popular and open source VESC firmware better is a nice side effect. |
| Siwastaja:
--- Quote from: Psi on April 30, 2019, 08:41:00 am ---Interesting, i always thought re-gen required some sort of extra boost step-up system to allow pulling high current out of the motor at slow speed. --- End quote --- For permanent magnet motors (brushed or BLDC), just output lower PWM duty cycle in two-switch (half bridge) design. Won't work with the simplest freewheeling diode design. With a half bridge, the motor inductance simply acts as a boost converter. Draw it, you'll see it's a bidirectional synchronous buck converter (which is synchronous boost in the opposite direction). If you want to really freewheel, you turn both switches off. For induction motors, it's fundamentally the same, but the control is, of course, a bit more complex. You need to output lower fundamental frequency than what the motor RPM dictates; this changes the sign of slip, causing it to become a generator. For a series-wound brushed motor, regen is a different beast, but these motor types are getting increasingly rare in modern designs. |
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