Can AC synchronous motors be controlled with VESC?

Question

I want to drive something like these ac synchronous motors:

Small Mige:

https://www.alibaba.com/product-detail/Small-Mige-130-series-1KW-best_60394196285.html?spm=a2700.7724838.2017115.13.6f2a2896JUGbXc

or Kollmorgen: (let's say 52k, doesn't mattter ultimately)

https://www.kollmorgen.com/en-us/products/motors/servo/akm-series/akm-series-ac-synchronous-motors/ac-synchronous-servo-motors/#tab2

So is driving these possible with VESC? I downloaded vesc software and there is a FOC mode which uses sine waves. But this is still a BLDC drive, not BLAC (PMSM)?

Oh yea since i'm confused about driving BLDC and PMSM. Can you drive PMSM with trapezodial (theoretical square wave)? BLDC can be driven with ac so I'm curious, and there are no straight answers on the internet.

Edit: My plan is to use vesc torque control. The motor would not spin above, let's say 500 RPM. The torque is the most important to me.

Position feedback would be done with incremental encoder.

I will feed the data to vesc using another microcontroller. Haven't decided how to do it yet.

Answer 1

Both {BLDC, PSMS} have PM on rotor, but the difference is the distribution of stator windings.

BLDC's are cheaper, better slightly more transient torque, when you do not need any precise position control unless you have a position encoder feedback then other specs determine which is better like EMI, THD, current crest factor, but generally any Sine wave drive gives better servo control for smooth torque, and position control such as using a low cost (<0.3$/W) VFD with some kV/RPM and computer control.

There are MANY types of position feedback encoders with different cost and resolutions. Cheapest and least accurate are Hall Sensors but adequate for commutation in most cases.

Both can be 2 phase quadrature or 3 phase Y ( or more phases ). ( You are considering 3 phase.)

Both tend to be 82% of no load speed at max rated power and 66% of no-load speed at max torque.

BLDC tend to be DC power with DC to Neutral or full bridge while PSMS are full bridge such as simple velocity+ acceleration controlled or AC input power.

Both use full-bridge PWM control. Feedback options include: current , and back EMF while BLDC tend to use HALL Sensors and PSMS tend to use more precise position feedback ( 3 types). ( Although I once use a micro-sized brush motor with 1000:1 gear reduction to turn a sin-cos Bourns pot for PLL vector rotation of a TEK XY vector display of an eddy current signal with 100 ppm resolution on impedance in XY planes at 100k,200kHz in late '70's) PSMS may offer active brake after coil power is off as a safety feature, while BLDC needs more active coil power for static torque.

Both can use 6 step Scalar control (quasi-sine) or FOC linear Vector true sine.

Both can have a variety of sensor feedback or used in sensorless control, depending on position accuracy and torque-phase jitter of control needed.

For high-performance Servo's with PSMS are best for resolution, the linearity of current and THD of power and thus lower eddy current losses.

Depending on cost, performance compromises, BLDC can be better such as using inexpensive ESC controllers.

It all depends on your error tolerance for every spec. {Position, velocity, acceleration, EMI, power distortion, dynamic control specs {step response, overshoot, load regulation)

Kollmorgenoffers best in class Servo solutions with at least 3 different servo feedback solutions, Sin/Cos resolver, RS485 digital incremental encoder with 20 bit resolution or

BLDC

• Trapezoidal back emf
• Square wave current
• Concentrating winding

More efficient , less servo position accuracy, more harmonic distortion

PMSM

• Sinusoidal back emf
• Sinusoidal current
• Distributed winding

If I made any errors in generalizations ( please suggest corrections) TYVM.

Answer 2

PMSM and BLDC are almost identical, except the one outputs sine wave back EMF while the other trapezoidal back EMF, respectively.

VESC is a more broad abbrevation for a moto speed control. A BLDC usally uses six-step commutation technique with the use of hall feedback sensors, or it can be sensorless with the help of back EMF sensing. At each time only two coils are energized, the third one is floating and used as antenna for BEMF sensing.

The FOC is used for control of PMSM, the injected current is sinewave, At the same time all three phases are energized. However with few tricks it is still possible to measure the BEMF if needed. A FOC needs at least sensing of two phases currents and absolute position of the rotor, last one can be estimated by use of some sensorless methods: BEMF sensing, PLL observer, Cordic, high frequency injection.

The FOC and PMSM is suitable for control speed, position and torque from zero speed up to max speed. While BLDC and VESC is usually limited to speed control which can be unstable at low speed if not using hall feedback, the same is also for the FOC - a sensorless control without an encoder feedback is not reliable at low speeds.

P.S. : the Kollmorgen motor from link is a PMSM with sinewave BEMF suitable for FOC. Some manufacturers use the incremental encoder, thus the absolute rotor position is unknown. For this purpose, the rotor initial position is estimated during startup an then counted with incremental encoder, which also has a zero mark (or many of them) used to set the true zero position.

Answer 3

As near as I can tell the lack of straight answers is because the terminology is not completely settled.

On the plus side, the worst that'll happen is that your motor will be inefficient, and run warm. If you don't start out by driving the thing at high speed under load, your learning experience should only be expensive in the sense of having unwanted parts, not slagged parts.

But, also as near as I can tell:

• Permanent magnet synchronous machine (PMSM) is a general term for BLDC or BLAC. It's probably mostly used to be synonymous with BLAC.
• Brushless DC is a PMSM with trapezoidal (or nearly so) back-EMF. So it's easier to drive.
• Brushless AC is a PMSM with sinusoidal (or nearly so) back-EMF.

Nobody is going to have perfectly trapezoidal back-EMF. Nobody is going to have perfectly sinusoidal back-EMF. If you really want to know for sure, get a datasheet that shows the back-emf, or that gives specifications for it.