Noise in DC Motor Driving Circuit

Using Arduino Motors, Mechanics, Power and CNC
1

hi...
I'm still learning English so accept my apologies if I did not describe things well due to poor language.

I wish you can help me to solve my problem.
I'm trying to build a circuit to drive a dc motor using Arduino pro mini and Nextion to control speed and time>
the problem is: noise while starting the motor (running) effect on the PWM signal and I get some transient value from speed sensor since I printed to Nexton screen (like actual speed 1000rpm while i get 4xxx or 6xxx)

Circuit specification:
motor 230 v dc: 400 W brush motor
ultrafast recovery diode ( HFA15PB60).
2sk2843 or 2sk3505 (n-chanal MOSFET)
Optocoupler pc817
supply for Arduino 5v from (Hi-Link)
supply 12 v on pin 4 (Anode) of pc817 to driving the gate of the MOSFET.
the ground of Arduino completely separated from the ground of 12v driving circuit.
230 Vdc was regulated from 220 v ac using kbl406 and 220 uf/450v capacitor.
please see the attachments.
thank you.

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TapScanner 03-18-2021-13.38.pdf (182 KB)

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@mohcis

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3

I see the physical layout as part of the problem. I see long power wires near signal wires. I do not see shielded wires, with one end of the shield grounded, used for signal wires.
Much can be done to minimize the noise level.
Paul

4

Can you post a schematic, not a frizzy drawing showing all power and ground connections as well as interconnections. Provide links to each hardware piece. The potential problem I see in bad grounding. Also power must be kept away from logic signals and best if they are either on separate boards or on the opposite sides.

5

Yeah of course
thank you Gil

6

Paul_KD7HB:
I see the physical layout as part of the problem. I see long power wires near signal wires. I do not see shielded wires, with one end of the shield grounded, used for signal wires.
Much can be done to minimize the noise level.
Paul

I'll try to do what you suggest. but this board (Power supply 300 v dc , 12v dc , 5 v dc ) separated from MCU board and only PWM signal + relay signal inter the power supply boardز
In any case, I will follow your advice.
thank you paul
.

7

I see a massive loop antenna in the way that motor is wired, many inches across. That's
going to be radiating a lot of EMI.

Best to use twisted-pair straight to the terminals, with one ferrite toroid over both wires together,
not on each individually.

There should ideally be a 10nF or so ceramic capacitor (suitable voltage rating) directly
across the motor terminals to reduce spark noise.

All high voltage parts should be heat-shrunk, no live metal exposed.

8

I'm have been placed a 10 nF /1kv ceramic capacitor as shown in the image with orange wire but it is hidden down the black acrylic. Moreover, I tried to do what you mention included twisting the wire but nothing noticed.
also that I'm added 10nF to the single terminal of the motor to reduce the noise effect but not much appear on the Oscilloscope

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