BLDC motor load performance

In summary: As for the pedal, it has a high load and the motor can't lift it up with the desired speed. The motor can lift it up with the desired speed accurately, but while going downward, the pedal just goes down freely overcoming the output speed of the motor. In summary, the motor can lift the pedal with the desired speed accurately, but while going downward, the pedal just goes down freely overcoming the output speed of the motor.
  • #1
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Hi,
I am using Sensored BLDC motors for some robotic movements. I am driving my motors using motor drivers. I am using ball screw mechanism for lifting a pedal up and down. On the pedal, there will be always a very high load, placed on it.

Now, my motor can lift up the pedal with my desired speed accurately but while going downward, the pedal just goes down freely overcoming the output speed of the motor.

Picture1.jpg


In summery I would like to say, when the motors are on downward rotation, they can’t hold the weight of the load and fail to conform to the desired downward velocity; instead they just let the pedal goes down freely until it reaches the lower threshold.


If you have any questions please let me know

thanks in advance
 
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  • #2
If the motors were standard brushed dc motors, there are two ways they can be connected; series connected (stator in series with armature), and shunt connected (stator in parallel with armature). I believe connecting them in shunt mode, with a voltage applied to the stator and a load (or short) connected to armature, the motor will act as a brake.

If the motor is a brushless dc motor (BLDC) with a permanent magnet rotor, then shorting the stator MAY cause the motor to act like a brake, depending on details of driver circuit. The cogging in BLDC motors may hold depending on load, but it may creep. The stator WILL act as a brake if the stator windings can be excited at a dc voltage, without commutation.
 
  • #3
Going down, your machine is acting as a generator. It will have retarding toque in proportion to the load seen at the electrical terminals. This means you need either a 4-quadrant drive for regenerative braking, or a dynamic brake circuit which essentially puts a resistor across the terminals, and the heating is the load. Short-circuiting the terminals makes braking torque during rotation, but it is not controllable.
 

1. What is a BLDC motor?

A BLDC (Brushless DC) motor is an electronically commutated motor that uses permanent magnets instead of brushes to control the motor's rotation. This type of motor is widely used in various applications due to its high efficiency, low maintenance, and precise control.

2. What is load performance of a BLDC motor?

Load performance refers to the ability of a BLDC motor to maintain a constant speed and torque when subjected to a varying load. It is an important factor to consider when selecting a BLDC motor for a specific application as it determines the motor's efficiency and overall performance.

3. How is load performance measured for a BLDC motor?

The load performance of a BLDC motor is typically measured by conducting a load test. This involves running the motor at a constant speed and gradually increasing the load until the motor stalls or reaches its maximum torque. The results of this test are then used to determine the motor's load performance characteristics.

4. What factors affect the load performance of a BLDC motor?

Several factors can affect the load performance of a BLDC motor, including the motor's design and construction, the quality of its components, the load inertia, and the control algorithm used. Other external factors such as temperature and humidity can also impact the motor's load performance.

5. How can load performance of a BLDC motor be improved?

The load performance of a BLDC motor can be improved by optimizing its design, choosing high-quality components, and using advanced control algorithms. Other measures such as reducing the load inertia and maintaining proper operating conditions can also help improve the motor's load performance.

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