At ebm-papst are well known as a fan manufacture so I was keen to see the latest development kit from Microchip, the Motor Control Starter kit DM330015. So I was interested to see how easy it is to setup and use as a development platform for getting used to using Brushless DC motors (BLDC).
BLDC motors or Permanent magnet motors are the best technology when it comes to energy saving and speed control applications due to their design. However you can’t just switch them on and watch them go and that’s because you need electronics to drive it. The motor is constructed from permanent magnets and then a number of coils that can be switched on and off in turn to rotate the magnets, and hence the motor. The speed and timing at which you switch these coils or winding on and off allows for the differences in speed, control of acceleration, breaking and even direction.
The kit comes complete on one PCB in the normal Microchip style of on board programmer and debugger (in this case a PIC24 with USB interface) the main target microcontroller, a dsPIC33 and a small 1,400 rpm three pole BLDC motor. Between the micro and the motor is the key drive circuit which has level shifters and then FETs. The circuit also includes a current and voltage sensing circuit to allow for monitoring of the motor and speed via back EMF. As an addition feature the board also has a capacitive touch slider control that during the demo code can be used to speed control the motor.
So powering up the board was straight forward and I found downloading the example code no problems either, I then complied and programmed the board. The board has the demo code on it, but I like to see that you can compile the code and program it too. This all worked great and as indicated I could start and stop the motor, change speed using the slider and see speed of motor via blinking LEDs.
The kit come with little else however and I needed to go get the user guide and the AN1160 application note to find out more about how the kits works. The user guide was OK from the hardware setting up point of view and also includes all the circuits, parts list etc to go make your own board - almost open source in a way. The Application note was also very good at explaining how BLDC motors work and how to fire the windings and control the PWM again from an electronics point of view.
My only issue was understanding the software. There is good well commented code and its well structured as always with Microchip example code. However I would have liked this written up to explain what function do what. A nice quick guide to the code would allow people to find things like rpm limits or allow for direction of rotation control.
So for an introduction kit I think its quite good as I easily got the board working, including compiling the code myself, in under half an hour. There is plenty of documentation online and if you are willing to dig into the code then I think this is a good way to get started before moving onto the large development BLDC kits that microchip make.
( @monpjc )