Controling ESC, Servo and DC Motor

[emirtnrvr]

Hey, I needed to control a brushless motor(24V) with external ESC, Servo(5V), and brushed DC motor(9V) also I have a 6S battery. Then I designed a PCB. PCB has been received from the manufacturer. I tested it first I thought there was no problem but after 2-3 tries Arduino didn't operate the system properly. Servo, brushed motor and DC motor are opening and suddenly closing. Most of the time even they don't start. I can't upload code to Arduino when it is connected to PCB even PCB is unplugged from the battery. But when I disconnect the Arduino from PCB, Arduino is working well. Also, I can measure 0,5V from the main voltage line when PCB is unplugged from the battery. MOSFET side I am measuring -0,12V from +9V-drain when PCB is unplugged. I tried to attach the diode to the ESC power line but it didn't work. I will try to change MOSFET maybe I damaged the MOSFET. I think something wrong with the DC motor switching circuit. I need help. Thank you.

FCU_DATA: PWM data from Flight Controller Unit
Sacma_Power: ESC power line
Sacma_Data: ESC data line
Titresim_Power: DC motor power line
Ard_regulator: Arduino Voltage Regulator 24Vto12V L7812
Servo 5V: Servo's regulator MP1584 adjusted to 5V
Titresim 9V: DC motor's regulator MP1584 adjusted to 9V
VCC_Batt: 6S Battery
Brushless Motor: 6S 2A
Brushed DC Motor: 9V 2A
Servo:5V 2A
Ignore the 3D model's "TIP120" writing. Parts changed but I didn't change the 3D model.

View attachment 140759

 

[Tony Stewart]

There is not enough attention to details for power switching and flyback clamping in the schematic. This board should have a copper pour for pwr and ground with fat motor traces and more decoupling of supplies.

 

[rjenkinsgb]

The PCB appears to have copper pours, but it's not obvious what component pins are bonded to them?

Have you done a simple multimeter check, to verify the ground pins for all components and connectors are actually connected to each other?

I agree with Tony that there is nowhere near enough decoupling, you don't have any electrolytics for bulk storage and stability.

Post single side copper only images of the board, with copper pours visible??

 

[emirtnrvr]

Thank you for your responses. Every pin is connected to the ground with copper pours. I checked with the multimeter there is no problem what should I do for fixing the problem?

 

[Nigel Goodwin]

For a start, add some decent size electrolytics across the supply rails - you've got pretty well zero supply decoupling.

 

[emirtnrvr]

For a start, add some decent size electrolytics across the supply rails - you've got pretty well zero supply decoupling.

How can I calculate electrolytics size

 

[emirtnrvr]

where should I place electrolytics main voltage line or regulator outputs

 

[rjenkinsgb]

How can I calculate electrolytics size

Just use a decent size - eg. 47uF or larger on the electronics supplies, probably 470 - 1000uF on the servo or motor power & a similar value at the power input.

Is the underside pour connected to one of the power rails, or to ground? You have not shown that side of the actual PCB.

 

[emirtnrvr]

Thanks, I will try a soon as possible.

 

[rjenkinsgb]

ps. If you are using voltage regulator modules from eBay, AliExpress or Amazon etc., note that generally they are only good for around 1/3 the claimed output current in normal use.

The advert ratings seem to often be the momentary peak load before shutdown / failure..

 

[emirtnrvr]

Yes, I know. My output is 1.5A continuously for each.

 

[emirtnrvr]

What do you mean by electronic supplies? I will place 470uF capacitors input and output side of the regulators. except for these should I use other capacitors.

 

[rjenkinsgb]

What do you mean by electronic supplies?

Low power devices, normal ICs & MCUs etc., not motor or high current loads.

That's a generic guide, however the Arduino has it's 5V internally decoupled, so it's all motor and servo stuff for this.

You do still need the small ceramic or film capacitors, as they handle high frequency noise better than electrolytics.

 

[Tony Stewart]

https://www.amazon.ca/s?k=Protoneer+CNC+Shield+v3.51&tag=al05a-20 these are useful cost-effective solutions. ($cdn)

The pro way of driving BLDC and stepper motors is to use N-ch full bridges for each winding and dual if reversible. But comparing the ESR of the motor, capacitor, switch and supply impedance with XL=2pifL you can get an idea for the voltage ripple induced by switched currents.

The a4988 has an Ir*RdsOn = Vds max drop of 650 mV @1.5A. This also dampens the high frequency resonance = f=1/[2pi*(LC)^0.5]. The inductance L of the motor winding and C from both cable and motor interwindings with all the series R. Note that they use a very large cap directly under the IC mounted on a board with headers. I have used this bridge with the Uno and CNC G-code and found excellent results, especially with the trimpot current limit adjustment tradeoff with heat rise.

https://www.allegromicro.com/-/media/files/datasheets/a4988-datasheet.pdf

- read the Application Layout until understood why.

The two input capacitors should be placed in parallel, and as close to the device supply pins as possible with the ceramic one closest. http://weblib.samsungsem.com/mlcc/mlcc-ec-data-sheet.do?partNumber=CL21A226MQQNNW
Note the Self Resonant Frequency (SRF) exists in all caps but may not be published.
General purpose e-caps have an ESR * C = T > 150 us approx in this size range, low tan delta = low ESR < 10 us with 0.5 us near the lowest while ceramic is lower than this..