Motor Drive Feedback Control Novak

[GordonFreeman]

I think I touched on this once a while ago, but mostly go blown off. I'll try again and see if I can explain it better.

I believe they use this kind of motor control in large industial motors. The idea is there is some sort of motor speed feedback to the controller, the controller compared that to the speed it should be spinning. That difference in speed is used is a simple equation to drive to motor to that speed.

The main reason I'm interested in this is for trying to simulate the physical drag of brushed motors in brushless.

Even the New GTB, doesn't act quite like I would expect it to. Sure there are drag brake setting and all, but they dont really come into operation until the trottle is released to neutral.

It is my belive that if the throttle is at 25% and the motor is steady state and I move the throttle to 75% it should some X about of time. If I do the experiment in reverse, start at 75% and drop the throttle ot 25%, the motor should not "coast" to speed, but should be "driven" down to that speed.

Perhaps a new setting needs to be made called "down thottle brake"

[kufman]

This could probably be done, but it may cause more heat in the controller. I know what you are taking about, stock motors have more of it than mods and it is there even when you are going forward. The more timing a motor has, the more of this feeling there is. Motors with laydown brushes also have more of it. I have a feeling that simulating this with a brushless would cause efficiency to go down.

[Jev]

Do you mean a torque adjustment for deceleration?

The mamba was at the other end of the scale and had max torque for any deceleration required.

Is this example the same thing you are talking about?

You are using full throttle and the car is at it's top speed.
You reduce throttle to 25%
The motor limits the braking torque(or none at all) to slow the motor down to the desired rpm of 25% throttle.



I think all brushless motors relate transmitter signal to rpm, which is the same way a brushed motor works. Albeit in a round about way. On a brushed motor it can be left to free wheel and the drag of the brushes add the torque to slow the car down. What you are saying is that you want the brushless esc to simulate this torque by applying some braking across the whole throttle travel?

I think I touched on this once a while ago, but mostly go blown off. I'll try again and see if I can explain it better.

I believe they use this kind of motor control in large industial motors. The idea is there is some sort of motor speed feedback to the controller, the controller compared that to the speed it should be spinning. That difference in speed is used is a simple equation to drive to motor to that speed.

The main reason I'm interested in this is for trying to simulate the physical drag of brushed motors in brushless.

Even the New GTB, doesn't act quite like I would expect it to. Sure there are drag brake setting and all, but they dont really come into operation until the trottle is released to neutral.

It is my belive that if the throttle is at 25% and the motor is steady state and I move the throttle to 75% it should some X about of time. If I do the experiment in reverse, start at 75% and drop the throttle ot 25%, the motor should not "coast" to speed, but should be "driven" down to that speed.

Perhaps a new setting needs to be made called "down thottle brake"

[GordonFreeman]

It's kind of hard to explain, I think you basically get what I'm trying to describe. It is one of the biggest complaints I hear from brushed guys about the way brushless motors drive/race.

It's not exactly "drag" brake per se, but a tendency for brushed motors to drag themselves down to a slower speed if you let off the throttle part way.

And,yea, unless it can be regenerative, it would probable reduce efficiency.

Even with the new GTB, you feel where the "drag brake" kicks in at 0 throttle. And you can feel how the motor still "coasts" when you only bring the throttle back a bit, still not like a brushed motor.

[saskhiker]

It's kind of hard to explain, I think you basically get what I'm trying to describe. It is one of the biggest complaints I hear from brushed guys about the way brushless motors drive/race.

It's not exactly "drag" brake per se, but a tendency for brushed motors to drag themselves down to a slower speed if you let off the throttle part way.

And,yea, unless it can be regenerative, it would probable reduce efficiency.

Even with the new GTB, you feel where the "drag brake" kicks in at 0 throttle. And you can feel how the motor still "coasts" when you only bring the throttle back a bit, still not like a brushed motor.


Just add some sand to the bearings lol. Aren't we always trying to reduce the friction of the drivetrains etc with brushed cars to reduce this effect? I think it is more a matter of adjsting our driving styles the same way that we do going from stock to mod. It just means that you have to back off the throttle more to get the deceleration that you are looking for. Maybe try more exponential on your trasmitter.

[Jev]

Just add some sand to the bearings lol. Aren't we always trying to reduce the friction of the drivetrains etc with brushed cars to reduce this effect? I think it is more a matter of adjsting our driving styles the same way that we do going from stock to mod. It just means that you have to back off the throttle more to get the deceleration that you are looking for. Maybe try more exponential on your trasmitter.

Although you can adjust your driving style, it is nice to have the option to adjust these things.

So what we need is an adjustment to simulate drivetrain/brush friction across the whole throttle travel not just at neutral.