# PID algorithm for bldc controller

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#### Nihaludeen

##### Member level 2
I want to apply PID algorithm for my bldc drive, But i want to now more about PID concept.

PID concept in motor drives...
1. PID make the system as a closed loop.
2. By calculating the input speed by resulted output speed, output has to be set.

For ex :
If i set the input as 1000 rpm at no load, the output will be considerably OK.
But in load condition, the output will not be 1000 rpm.
So we have to set the output speed according to the input, in load or no load whatever may be.

But in what case we have to use the current value in PID. Is PID is for both for speed and current ?

#### FvM

##### Super Moderator
Staff member
But in what case we have to use the current value in PID. Is PID is for both for speed and current ?
How comes current into play?

You have a basic speed controller, speed setpoint and actual speed (process value) are inputs, the controller output (manipulated value) steers the motor speed. But how is it steered in your application? You can either manipulate the motor voltage or current, or e.g. a PWM duty cycle that translates to voltage or current.

A motor controller may implement additional functions like overcurrent protection, torque limiting etc. More complex controller topologies may be needed to achieve this function.

Nihaludeen

### Nihaludeen

points: 2

#### Nihaludeen

##### Member level 2
Well thats good FvM, then i will go by "speed setpoint and actual speed (process value) are inputs, the controller output (manipulated value) steers the motor speed".

#### Jerryxm

##### Newbie
Don't bother with the "D" component of PID control for a motor. The derivative term is rarely useful in motor control applications.

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