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Setting up a PWM output from an ACE to control an IBT-4 drive for a 12 V DC motor

 

In this tutorial, we’ll look at how to control the flow rate of a small 12V DC pump by varying its supply voltage.

  • High-current MOSFET H-bridge drive (50A peak!)
  • Isolated from the PWM signal of the single-chip microcomputer to effectively protect the single-chip microcomputer
  • it can rotate the motor forwards and backwards, the bidirectional PWM input frequency is 200 kHz
  • 3.3 V to 12 V level can be used, fully compatible
  • 5 V to 15 V supply voltage

 

Analysis of the driver supplier’s documentation

  • The maximum power of 50 A is peak! You need to be reasonable with around 10 A for continuous use
  • The PWM input frequency of 200 kHz means that the input state is scanned every 5 µs
  • The PWM input voltage level of 3.3 to 12 V is very wide and suitable for a PLC pull-up output with a 10 kΩ resistor at 12 V
  • The 5 to 15 V supply voltage enables mobile applications such as automotive and agricultural applications

Determining the ideal PWM period

In the absence of recommendations from the manufacturer, systematic tests with a period of 100 µs and a duty cycle of 10, 50 and 100% are performed to check whether the voltage values delivered at the output are close to the target.

In our tests, starting with a period of 100 µs which seemed to be very close to reality. Depending on the equipment, the PWM period can go up to 20,000 µs for a servomotor!

We select 102 µs period, which gave the best response between 0 and 98% duty cycle. The difference between 98% and 100% is a loss of 0.02 V.

Using a period of 102 µs has enabled the gain to be reduced to 10% at low duty cycles.

Note that the voltage delivered under load is about 1V lower than the no-load voltage at 100% duty cycle.

PID regulation with an ACE 1430 successfully completed the project.

 

HMI and vBuilder Flow Chart (Grafcet) projects

dc-motor-driver