Angular speed and angular velocity

[mp252]

hi i have two different systems (i have tried to upload them but they both exceed the size of the upload limit). One is a dc motor block diagram (it has a PID at its controller) the other is a bldc motor model with a PID controller input. The block diagram of the DC motor consists of an armature block a load block this is where the angular velocity is produced at the output of the load block and if the angular velocity is integrated it provides me with the angular position, there is also a back emf from the velocity. The BLDC model has a contolle then has the BLDC T.F. this is where the angular velocity is produced and therefore when integrated gives the angular position. My question is how comes for the BLDC system why does it no need a load block which provides the inertia, which then generates the velocity by divding the torque generated from the motor?

thanks mayur

 

[berkeman]

hi i have two different systems (i have tried to upload them but they both exceed the size of the upload limit). One is a dc motor block diagram (it has a PID at its controller) the other is a bldc motor model with a PID controller input. The block diagram of the DC motor consists of an armature block a load block this is where the angular velocity is produced at the output of the load block and if the angular velocity is integrated it provides me with the angular position, there is also a back emf from the velocity. The BLDC model has a contolle then has the BLDC T.F. this is where the angular velocity is produced and therefore when integrated gives the angular position. My question is how comes for the BLDC system why does it no need a load block which provides the inertia, which then generates the velocity by divding the torque generated from the motor?

thanks mayur

Can you just scan the diagrams and upload them as PDFs? Or take a cell phone picture of them and upload them as JPGs?

 

[mp252]

hi here you are, the DC motor is put into a subsytem i have just shown you the whole block diagram to make it easier to interpret.
Thanks Mayur

 

[DragonPetter]

Hi mp252, the first block diagram is a control system, using a P controller, not a PID controller. This is because the controller is labeled "K" without a pole or zero for PID. This control system includes the model of the BLDC motor called HDD dynamics, which is the block transfer function in that diagram. This single block represents the same information as the entire second block diagram of the DC motor gives.

The second block diagram is not a control system, it is ONLY the model of the motor. The feedback loop in the second block diagram is characteristic of all DC motors, because it is the natural back EMF feedback. When you apply the G/(1-GH) rule to a feedback, you get a closed loop transfer function, and that is what's used in the first block diagram. to represent HDD dynamics This combines the electrical and mechanical poles into one transfer function, and that's why you don't see a load block in the first diagram.

 

[alphysicist]

Angular speed and angular velocity are both measurements of rotational motion, but they have slightly different definitions. Angular speed is the rate at which an object rotates, while angular velocity is the rate of change of the object's angular displacement over time. In other words, angular speed is a scalar quantity, while angular velocity is a vector quantity that includes direction.

In the context of the two systems you have described, the DC motor model and the BLDC motor model, both systems are using a PID controller to regulate the angular velocity of the motor. However, the DC motor model includes a load block, which represents the external load on the motor, and the BLDC motor model does not.

The reason for this difference is due to the different types of motors being modeled. A DC motor is a type of brushed motor, meaning it uses physical brushes to make contact with the commutator and provide power to the armature. This physical contact creates friction, which acts as a load on the motor and affects its rotational motion. Therefore, the load block in the DC motor model is necessary to accurately represent the motor's behavior.

On the other hand, a BLDC motor is a type of brushless motor, meaning it does not have physical brushes and instead uses electronic commutation to control the motor's rotation. Without the physical contact and friction from brushes, there is no external load acting on the motor. Therefore, a load block is not necessary in the BLDC motor model.

In summary, the presence or absence of a load block in a motor model depends on the type of motor being used and how it operates. The important thing is that both models are using a PID controller to regulate the angular velocity, which is the main goal of the systems.