Stepper to BLDC motor?

Other Hardware Motors, Mechanics, Power and CNC
1

Hi,

i am working on a motion control system that requires the motor to track velocity profiles.
Pertaining to the load, its inertia will be varying depending on its position.
I have a stepper motor at hand, and since it will vibrate or reaching resonance sometimes (i.e. depending on the pulse rate and load inertia), i am thinking of the possibility of converting the stepper to a brushless dc motor.
I have the arduino to generate pulses and direction signals to the stepper driver, and the driver connected to the stepper.
My plan is to add an encoder to the stepper to have the same resolution as the stepper's and feed the encoder's output to the stepper's pulse pin. While the arduino can use its PWM output to a chopper to provide variable dc voltage to the said driver and direction signal to the driver's direction input pin.
The stepper motor is PK564BW-N25 : No Valid PLP Version

The driver is CRD5114P : http://catalog.orientalmotor.com/plp/itemdetail.aspx?cid=1002&categoryname=all-categories&productname=stepping-motor-drivers&itemname=crd5114p&CSR=YES&UserSessionName=Muthu,%20Sam&type=1&pcat=mypage&signin=y&plpver=11

In other words, the entire package (stepper+driver with encoder feedback to the pulse pin) will become a BLDC with a pin for direction (from the stepper driver) and two terminals for voltage source (also from the stepper driver).And it can be controlled as a simple dc motor by changing the voltage to the package (up to the motor's rated value through PWM of arduino and a chopper power amplifier) and
a direction signal from arduino as well.

Is the above mentioned procedures feasible?Or perhaps is it implementable?

Regards,
Sam

2

I'm not seeing how you plan to drive the BLDC motor. This is not a simple "DC" motor but requires careful control of three phase components in order to achieve rotation.

Before heading down this complicated route, consider perhaps driving the stepper motor in a different way through its resonance point. You can try increasing the current at that point, or switching from full-step mode to half-step (or microstep) mode, or wave drive mode, etc. You will need a motor driver that can provide that level of control. Perhaps look at some of the offerings from Geckodrive. Their G210, for example, advertises built-in mid-band resonance damping.

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