Electromagnetic compatibility for brushless motor

[Herro]

Hallo everybody,

i wanted to perform a EMC (Electromagnetic compatibility test) test for a brushless motor. do you any source of documentation or have anybody a expreience in this area ?

Thank you in advance

 

[VEBill]

The nice thing about standards is that there are so many to choose from... Different countries or regions typically have different standards. Military standards are different than consumer standards.

http://en.wikipedia.org/wiki/Electromagnetic_compatibility

Most often if the device wasn't designed to meet a standard, then it is likely not to meet it. Even when it IS designed to meet a standard it often doesn't the first time through...

 

[Warpspeed]

Find out what tests you need to carry out, and as VE1BLL says that will be highly dependent on where you are (in which country), and the environment in which the motor is to operated. If it is to be exported it will need to comply with the destination country as well as your own.

There are basically two quite different requirements. Your motor must not interfere with other nearby equipment, and your motor must not be susceptible to interference from anything else.

Now where the environment part of it comes in.

Suppose your motor is to be used in an electrically quiet location, say a home or an office, it is highly unlikely to be interfered with by nearby equipment. But your motor may cause absolute chaos to a nearby radio, TV or computer. So in the example given, external radiated noise from your motor would be the main concern. Susceptibility to external noise would be extremely unlikely and would not be an issue.

But suppose your motor was to be used in an extremely noisy location, say a welding production line. Nobody cares how much noise your motor makes !! But if your motor is susceptible to electrical interference and malfunctions, that could be a problem, especially if your motor has some human safety implications in its primary function.

So the use and environment in which the motor is to operate will determine which EMC standards are applicable. Some are fairly easy to pass, others can be notoriously difficult, and may require a major redesign to pass.

 

[Herro]

Thank you for your Reply,

the Motor should be used in the automotive Area to drive water Pump. we are develloping the pump with a motor in Belgium. I measured the current of the motor in the Test bed not in the car and seems to be subjected to la oscilation with frequency around 2000 Hz. Is this frequency in the EMC critical range ?

Thank you

 

[Warpspeed]

I am unfamiliar with specific EMC requirements for passenger vehicles, but there certainly will be some written standards available that will show the specific tests required, how to carry them out, and the measurement limits required for compliance.

It will be a case of finding out what is applicable, and if you plan to sell to a major car manufacturer, what they may require as proof that your motor is not going to cause problems in their cars.

 

[VEBill]

"2000 Hz"

Ideal for interfering with car radio/stereo equipment.

 

[Warpspeed]

Yes, 2000Hz sounds rather nasty, but probably is no worse than the full load ripple current from the alternator.

It comes back to environment. A car electrical system definitely falls into the very noisy environment category. So the problem is making everything immune to the unavoidable noise that is already there. Not necessarily trying to make equipment with low noise output, which may be impossible to achieve anyway.

So I would say the problem rests mainly with the audio equipment designers, they will be the ones tearing out their hair.

The car alternator designers can just smile at the problem. I don't expect you will have any difficulties at all getting compliance. But you still need that sheet of paper saying that your motor has been properly tested and passes by X amount.

Basically they will pour all sorts of noise, power surges, and high frequency electrical transients, probably up to several thousand volts peak, into your motor. If it survives and does not misbehave it will have passed. What electrical crap comes out of your motor will most likely be of little or no concern.

That is the basic philosophy.