Control DC motor power

Thread Starter

LeccyStu

Joined Aug 2, 2022
2
I have an electric vehicle with:
  • 250W 24V brushed DC Motor
  • 24V motor controller
  • 5-pin throttle pedal (green, black, red, yellow, orange)
  • 24V battery

I would like to modify this existing setup by digitally (i.e. via an Arduino) creating a temporary 'boost' to the motor power.
I have a 36V battery which other owners of this vehicle assure me can accept a straight-swap of the 24V battery with a 36V battery for added performance.


My questions are:
  1. What kind of control is the throttle with 5-pins? Is it PWM?
  2. Is it best to use an increase in voltageto facilitate the boost?
    1. If so, does this just affect RPM and not Torque as I have read elsewhere?
  3. Which of the following methods is best, and what components would I have to add in to the existing setup to achieve this?
    1. 'Modifying' the signal from the throttle so that during normal use, a fully-pressed throttle would give the same signal to the controller as 66%-pressed pedal. This way, with the 36V battery, I'd get about the same performance as with the 24V. Then, using the Arduino, I can 'unmodify' the throttle signal so that the fully-pressed pedal now outputs 100% again.
    2. A voltage regulator between battery and controller which regulates down to 24V until Arduino does something to enable the boost.
    3. A voltage regulator between the controller and the motor which regulates down to 24V until Arduino does something to enable the boost.
      1. Assuming the throttle is PWM, would this then end up in a DC voltage to the motor which has undergone PWM twice?
        1. Is this a problem?

In assessing the best option, my criteria are: cost, space, electrical efficiency.
So ideally minimal additional components but still efficient.

Thank you.
 
Last edited:

Ya’akov

Joined Jan 27, 2019
6,260
Welcome to AAC.

I have grave concerns about using an Arduino in a safety related role. The design would have to be failsafe such that the Arduino cannot actually operate the throttle itself. These MCUs are not designed for critical systems and a mistake in programming or circuit design could be disastrous.

The act of "unmodifying" must be such that it leaves nothing about the user control changed. That is, the only way to signal the controller to operate the motor must remain the throttle controller itself and not a signal from the MCU.

I can't tell from your description if that is what you intend or how.

Separately, if the ESC expects 24V how will the 36V battery work?
 

Thread Starter

LeccyStu

Joined Aug 2, 2022
2
Welcome to AAC.

I have grave concerns about using an Arduino in a safety related role. The design would have to be failsafe such that the Arduino cannot actually operate the throttle itself. These MCUs are not designed for critical systems and a mistake in programming or circuit design could be disastrous.

The act of "unmodifying" must be such that it leaves nothing about the user control changed. That is, the only way to signal the controller to operate the motor must remain the throttle controller itself and not a signal from the MCU.

I can't tell from your description if that is what you intend or how.

Separately, if the ESC expects 24V how will the 36V battery work?
I believe the 24V controller + 24W motor work with 36V supply (but the motor and/or controller may overheat if used for sustained periods).

I just want to have a sort of 'switch' to switch between the increased power and a power output roughly equal to the "stock" setup (which has a 24v battery).

This 'switch' would be controlled via Arduino – but ideally, as you pointed out, the Arduino wouldn't handle any of the power, it would simply control the 'switch'.
 
Top