Add a known load to a DC motor

[Umit45]

Hi everyone,

I have implemented PI control of speed of a PMDC motor under no load condition. I now intend to implement the same with a load added to it.
I want to compare the results with simulation as well. Is there any way of adding a known load to a DC motor. In my set up the dc motor is mounted on a metallic box.

Thanks,

 

[ArticCynda]

An easy way to apply a variable load to any motor is connecting it to a stepper motor and powering up one (or several) of its coils with a controlled current. This controls the holding torque of the stepper, known from its datasheet, and thus provides an easy, cheap and readily available known load to any motor.

 

[BradtheRad]

Theoretically, torque measurement is supposed to be done by attaching a known weight to a rope which is reeled up by the spinning shaft of the motor. The shaft is a known diameter. The resulting torque value is stated in foot-pounds.

This is a difficult measurement to take. It can only be done while the motor is spinning.

An alternative is to apply friction in some manner. (Example, cloth-covered clamp.) This tends to polish surfaces thus reducing friction, making this an unreliable test.

Another way is to create magnetic friction in the form of eddy currents. Attach a plate to the shaft and hold a magnet close to it while it spins. If not done carefully this could disrupt operation within the motor.

Another way to create a load is to make the motor spin a paddle, which is immersed in water to various depths.

 

[jiripolivka]

Haven't heard of a DYNAMOMETER? A common mechanical loading device know since 19th century?

 

[chuckey]

Couple it to another permanent magnet DC motor, which will now act as a generator, load it with resistors to increase load.
Frank