Noise in CY8CKIT-050 PSoC® 5LP Development Kit board

Tip / Sign in to post questions, reply, level up, and achieve exciting badges. Know more

cross mob
Anonymous
Not applicable

 Hi I have the CY8CKIT-050 PSoC® 5LP Development Kit board. With this board I send the PWM signals to switch the Mosfets  in a inverter. The inverter is the source for a three phasic induction motor. The PWM signals are isolated with optocouplers from the psoc board to the Mosfets drivers. When the input voltage of the inverter is 110v, the PSoC stops the modulation, so the inverter is in short circuit. With a scope I see noise in the 5V and 3.3V pins of the board. This noise can reboot the PSoC? or the circuit protection of the board are turning off the digital pins of the board?

0 Likes
5 Replies
Bob_Marlowe
Level 10
Level 10
First like given 50 questions asked 10 questions asked

Having noise on the regulated power rail of your board might come from the power-supply and/or the power mains. Make sure that your motor does not feed mack currents / voltages back to your main supply.

   

 

   

Bob

0 Likes
ETRO_SSN583
Level 9
Level 9
250 likes received 100 sign-ins 5 likes given

What are the levels of the noise you see, frequency, magnitude, etc.. ?

   

 

   

Onboard regulators have a great deal of noise rejection themselves, so

   

you might suspect single turn magnetic coupling from large motor currents.

   

Any pins at high Z e field copupling another possibility.

   

 

   

Layout, are your photo couplers laid out in such a manner that AC noise isolation

   

is compromised, like traces coupling to each other.

   

 

   

Large dI/dT affects in ground bounce affecting board ? Is board galvanic from

   

motor ground or do they share a common DC/AC ground ?

   

 

   

Regards, Dana.

0 Likes
HeLi_263931
Level 8
Level 8
100 solutions authored 50 solutions authored 25 solutions authored

When you designed your circuit so a stopped PSoC lead to a short circuit in your inverter, you did something wrong. You should design it so this never happens.

   

At least you should incorporate a watchdog to restart the PSoC automatically.

0 Likes
ETRO_SSN583
Level 9
Level 9
250 likes received 100 sign-ins 5 likes given

The period used in a watchdog is generally much longer than safe area

   

performance of motor drivers, so real solution is thermal and current

   

limited driver parts that will respond in uS to fault conditions.

   

 

   

Hli is also correct, design UP side for fault situations,  although as stated

   

prior some conditions need to be taken care of by device level protection.

   

 

   

Regards. Dana.

0 Likes
HeLi_263931
Level 8
Level 8
100 solutions authored 50 solutions authored 25 solutions authored

One thing you can do is to take the outputs of the PWM (I presume you have two because otherwise you won't run into the problems described) and lock them (inside the PSoC) so only one can be active at a given time:

   

   

(assuming both outputs are active high)

0 Likes