Motor Drive Circuit Troubleshooting

[cyeokpeng]

Hi,

The motor drive circuit in the document attached use the L298 H-bridge driver switch to control the direction and speed of the dc motor, and the free-wheeling diode bridge (L6210) is connected across the motor to protect the transistors from the induced back emf of the coils in the motor.

I have tested the circuit on breadboard, but the water pump seems to be driving slowly, even though I use 80% duty cycle PWM of the ENABLE input, which is already quite high. For the 12 V volatge source, I use the 12V acid battery, while the 5V is provided by passing the 12V through a voltage regulator. The Rsa sense wattage resistor I have used is 0.15 ohms, 3 watts.
What can be the possible problem causing the slowless of the water pump motor?

Thanks,
if you need me to provide some info so as to lead light to the problem, kindly ask me.

 

[NoTime]

Why the fancy circuitry?
According to your attachment the requirements are to pump one direction.
This seems to be a change from the original plans, so it might be time to change the circuitry as well.
And if you are going to assume that there will be an outboard pump to empty the tank, why wouldn't there be an outboard pump to fill the tank?

Also why 80% PWM?
The H-Bridge circuits I am familiar with will go 100% (or simply on/off).
Running at 80% pwm will make the pump run slow, as you seem to have noticed.

 

[ravenprp]

Hi,

Thank you for providing details about your motor drive circuit troubleshooting. Based on the information provided, there could be a few possible reasons for the slow speed of the water pump motor. Here are a few things you can check to identify the problem:

1. Check the voltage output of the voltage regulator: The voltage regulator should be providing a stable 5V output. If the output is lower, it could be affecting the performance of the motor.

2. Check the connections: Make sure all the connections are secure and there are no loose or faulty connections that could be causing a drop in voltage.

3. Check the duty cycle: While 80% duty cycle may seem high, it is still not at 100%. Try increasing the duty cycle to see if it improves the speed of the motor.

4. Check the current rating of the voltage regulator: Make sure the voltage regulator can handle the current required by the motor. If it is not sufficient, it could be limiting the speed of the motor.

5. Check the wattage rating of the wattage resistor: The wattage resistor should be able to handle the current passing through it. If it is not sufficient, it could be overheating and causing a drop in voltage.

I hope these suggestions help you identify and solve the problem with your motor drive circuit. If you need further assistance, please do not hesitate to provide more information and ask for help. Good luck with your troubleshooting!