I require your help regarding a design I am exploring
Description:
Hi folks,
I am sketching out the design of a motor assist system for an otherwise hand-powered system. I am looking at the “roboclaw 2x60a” motor controller and a brushed DC motor. I need to understand the method of control that the motor controller employs so that I can take electromagnetic shielding into consideration. While I might imagine that the controller presents a pulse width modulated power to the motor to effectively manage power delivery, I would like to find out explicitly things like the time/frequency basis so that I can understand the nature of the electromagnetic fields being generated… so that I can determine if I need to provide shielding for my application. I suppose that it would be useful to know if the controller employs an H bridge or if there are any benefits to using multiple isolated battery cells for power control. (I realize that an isolated digital battery is recommended.) the theory of operation is sort of missing from the documentation I have found so far.
Hardware concerned:
“roboclaw 2x60a” motor controller
Actually Page 8 addresses how I control the motor controller, an entirely different question.
I am interested in understanding how the motor controller manages the electrical power to the motor itself. The electrical power delivery to the motor can create electromagnetic fields around the motor power leads. I need to understand how the motor controller controls the motor to understand the shielding requirements I may need to employ on the motor power leads, and potentially around the motor body itself.
Would love to, unfortunately, I am in the process of specifying the components, not building a prototype. So there is no unit in my hands to measure, I was kind of hoping the folks who sell these things would want to sell them bad enough to give me a reply. Our earlier conversations, and the specifications of other units lead me to “guess” at the method, what I can’t quite do responsibly is guess at the base frequency, nor can I guess at if the base frequency is programmable.
No worries, The project will be shelved for a half year or so now, I have time to explore other options rather than trying to convince consumer oriented sales teams to provide designer oriented data…
Next fiscal year… There are several projects moving from a preliminary design toward critical design, We are looking at shaking out similar requirements sets to determine if several of these individual projects will merge into a more generalized solution that will accomplish more than one mission.
In order to determine the electromagnetic field of the system, you need to take a lot into consideration:
Cables used ; the length, is it braided or full core, is it shielded or not
Current going through the cable
Duty cycle of the motor
PWM going to the motor
The motor itself
etc
Obviously, this is something that needs to be calculated by the designer of the project. I can suggest if you want to reduce the electromagnetic field produced by the motor and motor controller to use shielded cables and possibly use a Faraday Cage.
The people who sell them probably don’t know. I’m sure they want to sell them to you but they can only give you information they have. Have you contacted the manufacturer? That’s who would be most likely to have the information.
Why did you approach “consumer oriented” businesses to get data on a part to start with? Seems kind of silly to me. Not to mention unprofessional. If I want to know specs on an NXP processor that aren’t listed on DigiKey’s website, I don’t ask Digikey, I ask NXP. But that’s just me. Perhaps you and your business like to get angry at people more than you like to get answers.
