Control.com - Nerds in Control

Hello,
I just made a single phase inverter for squirrel cage motor based on this link:

http://www.freescale.com/webapp/sps/site/overview.jsp?nodeId=02nQX GrrlPglzQ0763

The MOSFET drivers based on the following design ideas:

http://www.edn.com/contents/images/52704di.pdf

The microcontroller CY8C29466 can generate 3KHz sinewave PWMs with phase shift 90 degree. MOSFET gate pair has suitable charge and discharge on
oscilloscope check.

However, when I supply the power to the motor, the uC is stop. Shutdown this power, the uC runs again without any failures. I use the same
ground from negative high voltage rectifier power, MOSFET drivers and microcontroller. I think the ground is the problem but I do not know how to separate power ground and uC ground. Please advise how to solve this ground problem. Thanks.

Best regards,
Hung Lam

You have to keep the power systems separate. The easiest place to do this would be at the gate drive using optoisolators. The whole power end then would then be line powered referred to it's ground and an isolated supply would be used for the control section. This will also greatly enhance the reliability of the driver electronics as the line environment in association with inductive and perhaps briefly regenerative, loads, is isolated from the low level electronics.

Regards
cww