Electromagnetic Brake Operation for Stepper Motors compared to Brushless DC motors.

om_tech_support_JS
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Joined: Tue May 10, 2016 4:48 pm

Electromagnetic Brake Operation for Stepper Motors compared to Brushless DC motors.

Postby om_tech_support_JS » Wed May 17, 2017 12:54 pm

Q: I am using the AZD-AD driver and my stepper motor has an electromagnetic brake. I have used your BX2 series in the past and am used to the operation of the brake with this motor. However, for the AZ series, when I complete a motion, I do not hear the electromagnetic brake engage. I want the brake to engage so that it holds my load in its position. Is there something I am doing wrong, or is there a way for me to manually engage the brake?

A: In regards to your question, the electromagnetic brake is a power off type brake and is designed to hold a load when the power has been removed. The operation of the brake is automatically controlled by the driver. The electromagnetic brake will appear to operate slightly differently for our AZ, AR, and RK2 stepper motors compared to the BX2 and BLE brushless speed control motors. This is due to the stepper motors having holding torque.

Holding torque is generated from the current flowing to the motor windings in the stepper motor. The brushless DC speed control motor only has excitation when the motor is instructed to move (*exception being the BX2 series in Servo-lock mode). However, our stepper motors feature a 50% current cutback at standstill. This cutback is an automatic feature of the driver specifically designed to limit the heat generation from the motor. Since the motor has current, the brake is not engaged. In order for the brake to be engaged, the motor’s excitation must be removed. Please see the Timing charts below for the reference of the brake operation of our stepper motors (Referenced from page 155 and 157 of the AZ function manual):

AZ Function Manual:

http://www.orientalmotor.com/products/p ... 60262E.pdf

Timing Chart AZ STOP input with decelertion stop.png
Timing Chart AZ STOP input with decelertion stop.png (90.78 KiB) Viewed 448 times

Timing Chart AZ STOP-COFF input with decelertion stop.png
Timing Chart AZ STOP-COFF input with decelertion stop.png (138.39 KiB) Viewed 448 times


For the AZ and AR closed loop series, there is an additional C-ON input which is used to provide current to the motor. Therefore, when the C-ON input is removed, the motor will lose excitation and the brake will be engaged. When stopping the motor, you will need to use the STOP-COFF option for the Stop input in order for the brake to be engaged. For the RK2 series, there is no C-ON input, therefore, power must be removed from the driver as shown in the RK2 timing chart below (Referenced from page 36 of the RK2 manual):

RK2 Manual:

http://www.orientalmotor.com/products/p ... 234-2E.pdf

Timing Chart RK2 Series.png
Timing Chart RK2 Series.png (95.12 KiB) Viewed 448 times

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