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DRV8210: PWM mode control

Sakhan
Intellectual 270 points
Part Number: DRV8210
Other Parts Discussed in Thread: MSP430FR6043

Hello Community,

To operate the valve, I'm using the DRV 8210 DSG. I'm generating PWM1 (TB0.1) and PWM2 (TB0.4) from the MSP430FR6043. By using ADC I am sensing the supply voltage Vs to achieve the required dc to run the motor.

        i,e DC= (5 (required voltage) / Vs)* 100;

For PWM Mode, I connected the MODE to GND in Driver.

1. I verified the PWM generation at the MCU end; a) IN1 = 0 and IN2 = 1 (PWM) (Reverse); b) IN1 = 1 (PWM) and IN2 = 0 (Forward).

2. Next, I connect the MCU's PWM1 and PWM2 pins to the driver IN1 and IN2 ports. I checked the output from OUT1 and OUT2 and it is as expected.
                 a) OUT1 =Low and OUT2=PWM (Reverse)
                 b) OUT1=PWM and OUT2=Low (Forward)

A channel =OUT1 and B channel =OUT2

3. When I connect the motor to OUT1 and OUT2, let's assume I'm doing reverse operation, OUT1 = PWM (75% DC) and OUT2 = PWM (25% DC), it appears to be in complimentary mode.why?

A channel =OUT1 and B channel =OUT2

I conducted the Test with various voltage, for some voltage the parallel voltage at OUT1 and OUT2 is 0. i,e (close) Vs=9V OUT1 =4.1v and OUT2=4.8v.

Please look the below table for your reference,

PWM generation from the MCU end is happening as predicted, however after I connect the motor to the DRV, the issues listed above start to occur.

How to fix these problems.

Thanks in advance,

Sarwath

  • 0
    TI__Mastermind 37683 points

    Hi Sarwath,

    Can you try switching your control logic? Instead of going from Reverse or Forward driving to Coast decay, can you switch to Brake (low-side slow decay). To accomplish this, set the non-switching input HIGH and inverse the duty cycle of the switching input. Does this fix the issue?

    Regards,

    Pablo Armet

  • 0 in reply to Pablo Armet
    Intellectual 270 points

    Hi Pablo Armet,

    Thanks for your Response.

    1.When I set the non-switching input to HIGH and inverse the duty cycle of the switching input, the output voltage from the driver (OUT1 and OUT2) varies like (3 v to 11V) but I want constant 5v. By adjusting the PWM duty cycle, I want to manage my driver's output voltage so that it delivers a consistent 5 volts to my motor. This method not worked as per my requirement.

    2.When I set the non-switching input to LOW and inverse the duty cycle of the switching input, the output voltage from the driver (OUT1 and OUT2) is  constant 5v. So I am fixing this set up.

    3. Previously I made transition from Reverse to Coast or Forward to coast, Now I changed the transition from Reverse to Brake or Forward to Brake. But still I am facing the same issues.

    I am using a CWX Mini Motorised valve with an operating voltage range of 3V to 6V. The motor is running at 6 volts and 7 volts, but the output terminal voltage difference is less than the required level of 5 volts, therefore the valve opens and closes slowly, but it works.

    However, if I raise the voltage over 9 volts, the motor stops since there is no voltage difference at the output terminal. Please refer to the excel sheet table that has been attached above.

    Transition based on my logic,


    Brake --     Open Valve -- Reverse -- OUT2 to OUT1 --- Brake

    Brake -- Close Valve -- Forward -- OUT1 to OUT1 --- Brake

    I tested the above transition at the MCU and driver ends and it works perfectly. When I connect the motor to the driver, it does not function as expected.

    Regards,

    Sarwath

  • 0 in reply to Sakhan
    TI__Mastermind 37683 points

    Sa Khan,

    I suspect the valve load you are using may be causing the issue. Have you tried using a simple resistive load to verify that the problem is on the load side? 

    Regards,

    Pablo

  • 0 in reply to Pablo Armet
    Intellectual 270 points

    Yes Pablo Armet.

    I tried with a resistive load and received a steady 5 volts at the DRV 8210 output terminal across the entire voltage range (6v to 11v).

    Every 1ms, I read the adc data and load the compare value for Timer_B.

    Regards,

    Sarwath

  • 0 in reply to Sakhan
    TI__Mastermind 37683 points

    Hello Sarwath,

    It seems your load is affecting the output voltage. Can you share the part number of the load you are using? 

    Sometimes motors with low inductance can have issues similar to what you are observing.

    Regards,

    Pablo Armet

  • 0 in reply to Pablo Armet
    Intellectual 270 points

    Hello Pablo Armet,

    I'm using a CWX mini motorised valve CWX-15N MODE CR05. The inductance is 9.87mH and the resistance is 10 ohms.

    Regards,

    Sarwath

  • 0 in reply to Sakhan
    TI__Mastermind 44835 points

    Hi,

    Thank you for your question. Monday September 4th is national holiday in US. Pablo feedback to you when back to office.

    regards

    Shinya Morita

  • 0 in reply to Shinya Morita
    TI__Mastermind 37683 points

    Hello Sarwath,

    The inductance and resistance of you load seems okay to me. I don't think it is the root cause. 

    From the IC standpoint, everything is working fine when the load is not connected. You have to understand why the load is causing the unstable output. If possible, I suggest reaching out to the load manufacturer. Is this possible?

    Pablo Armet