You are here

can't reach the maximum speed

4 posts / 0 new
Last post
kingpon
Offline
Last seen: 6 years 7 months ago
Joined: 2017-10-25 05:11
Posts: 1
can't reach the maximum speed

Hi,

   I use VESC and other esc drive my motor,i found that vesc is lower speed than other esc when in full throttle.How can i increase the speed?

frank
Offline
Last seen: 1 month 5 days ago
VESC BronzeVESC FreeVESC GoldVESC OriginalVESC PlatinumVESC Silver
Joined: 2016-12-27 20:19
Posts: 847

What HW version do you use? HW 4.12 is limited to 60K ERPM and VESC 6 can go up to 150K ERPM. Basically the speed of your motor is determined by the KV value of your motor.

If you go beyond the limits of the controller (e.g. HW 4.xx >> 60K ERPM), you risk damaging your ESC. The VESC-Tool allows you to set max ERPM limits for safe use.

The VESC runs advanced control modes that need to keep track to the rotor and switch the motor phases accordingly, controlling the voltage and the currents at all times. VESC based controllers use current control and not simple voltage control. It is a real time computation game that relies on real time precision measurement of the rotor position in reference to the spools. Going to high ERPM is the trick and it is possible with the new VESC 6 hardware, monitoring all three motor phases. The big advantage of the VESC is the precise control of your motor (RPM, output power, torque, control over amp draw and voltage supply), which is not possible with simple voltage control algorithms. A prime example of the possibilities this system offers is running your motor in FOC-mode (sinosidal). The matter is highly complex but you can find a lot of information about it on the internet.

Search for four quadrant operation and control of BLDC motors, sinusoidal motor control, FOC etc.

Frank

 

benjamin
Offline
Last seen: 1 month 3 days ago
VESC FreeVESC OriginalVESC Platinum
Joined: 2016-12-26 15:20
Posts: 490

It can depend on many thinks. Pure FOC compared to pure block commutation gets slightly lower top speed as the sine voltages would be distorted otherwise as they are in block commutation. Also, the VESC is limited to 95 % modulation and the other ESC might come a bit closer to 100%. Another thing might be that the other esc has high timing advance.

I'm working on a field weakening feature to get a bit higher top speed at the cost of efficiency, but the best option is to increase the input voltage if possible.

elektrinis
Offline
Last seen: 9 months 3 weeks ago
Joined: 2018-04-08 10:03
Posts: 2

kingpon: cheap and dirty ESCs do basic trapezoidal drive, with higher effective voltage than sinusoidal drive, like VESC. It's a small tradeoff in speed, but has has no decrease i efficiency.

 

Ben: how's that field weakening coming? Looking forward to that a lot. On commercial EVs, speed increase of up to 4x is possible.