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I am starting to work on undergraduate project to build electric skateboard. Main thing I will foucus on, will be ESC (electric speed controler) made for a motor 190KV (motor spec.). I got micro-controller STM32F401 Nucleo and expansion board Nucleo low-voltage 3-phase motor driver STSPIN230. But here I got questions. This expansion board got low voltage range between 1.8 to 10v, but BLDC motor will be powered by 24 voltage battery supply. My main idea is to program a low-voltage 3-phase driver and at the outputs(U,V,W) design a circuit which can boost power to my motor.

1.)Is this possible to build a circuit with 6 MOS-FETs at the end of low-volage Nucleo drive to boost output power and current for BLDC motor?

2.)Can this board make a output torque for low speeds?

3.) How hard is to design a smooth operation ESC that will speed smoothly and not have jerky brakes?

My main consern will be at the end, this ESC will power motor which will push heavy load (human 80 kg) down the road. I am trying to come close to a VESC product speciffically made for electric boards. A size of my ESC is not limited.

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    \$\begingroup\$ Given that there have been a million recalls on these kinds of products for overstressed battery fires recent year, you need to know motor DCR and all conduction losses in battery, motor and bridge. Torque = average current, target Speed = average voltage where Pout * t> Work to be done & losses are I^2ESR in each part, with Pd * t=E and thermal resistance for temp rise 'C/W \$\endgroup\$ – Sunnyskyguy EE75 Mar 1 '18 at 22:20
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    \$\begingroup\$ The standard design for the output portion of this type of motor controller would have a DC bus (24V in your case), a half-bridge driver circuitry, and FET's. Adding any extra crap along the way will not really make it work better. You want to follow the standard way to do it. There are also bridge drivers specifically designed for 3-phase motors (such as the DRV8302). The DC bus voltage needs to be chosen based on the motor characteristics. I don't know how you came up with 24V, but you need to make sure it will work well with the motor. \$\endgroup\$ – mkeith Mar 3 '18 at 19:46
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    \$\begingroup\$ Study the VESC. Make your basic architecture similar, but use voltage ratings and whatnot suitable for your board. Trying to take the output of a low voltage ESC and convert it to a high voltage ESC does not make sense. \$\endgroup\$ – mkeith Mar 3 '18 at 19:52
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After taking a closer look at the datasheets of what I recommended and what you have, I think it'd be reasonable to do away with your STSPIN230 and just implement a motor driver with your microcontroller, some FET drivers, and some FETs.

Get three of these (LT1160) half-bridge drivers and six FETs. The half-bridge drivers will allow you to control the FETs with 3.3v or higher logic inputs (from your MCU) and prevent you from shorting your power supply. You could replace the three LT1160s with one DRV8302.

To answer your questions:

  1. You can build a driver circuit that can take inputs from your microcontroller and drive the motor.
  2. That depends on how powerful your battery is and how beefy your FETs are.
  3. If you don't mind it speeding up slowly, then it's easy. Conventional ESCs would have far superior acceleration due to sensor feedback.

"I am trying to come close to a VESC product": I would highly recommend you buy an ESC or duplicate that custom BLDC motor controller project that you linked. Designing a sophisticated, high-power ESC is not an easy task.

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You might consider switching to a motor driver that uses external FETs instead of integrated FETS. For example the STSPIN32F0, which even has a microcontroller in the same chip.

You could add higher-voltage FETs to the output of your driver, but then you'd have to deal with timing to make sure you don't turn on two FETs that short your battery... I highly recommend you use a chip more suitable for your task rather than adapting the one you have.

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  • \$\begingroup\$ How about a Frequency controler: AD9850 DDS, and I build my own FET output circuit to power a motor? \$\endgroup\$ – user45189 Mar 2 '18 at 9:24
  • \$\begingroup\$ @user45189 A frequency controller makes no sense in this context. \$\endgroup\$ – ILoveGit Mar 3 '18 at 17:10

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