Latest news from the LinkedIn Digital Power Electronics Control Group

What is the latest news from the Linkedin Digital Power Electronics Control group?

The group now has over 600 members. To join the group please click here.

In the group we have lively discussions with people contributing their knowledge and experience. To all who have contributed and made the group so much fun – a really big thank you.

In the group we have had discussions that cover

  • Digital PWM modulators
  • ADC (analogue to digital converters)
  • Choosing the number of bits in a digitally controller,
  • Implementing digital filters,
  • Processor choices and coding.

How many bits are required in digital control of power electronics

Recently the how many bits are required was brought up and addressed in this way by John S.

There are two aspects to selecting the number of bits: measurement resolution and control variable resolution. For measurement resolution, the ADC resolution is the deciding factor, and this can be increased by oversampling.

In a current control application I was recently working on, I required 14 bits of resolution to meet a target requirement of +-1% of ADC quantitization error at 10% current. This resolution was relatively simple to achieve by oversampling the 12 bit ADC in the uC.

The resolution of the control variable, e.g. uC timer resolution, is just as critical in fast systems. If the resolution is too coarse, jitter in the control variable will appear at the output. With slower system dynamics, e.g. in voltage controlled systems, jitter in the control variable causes less jitter in the output variable because of the smoothing effect of the output capacitor. Ideally the resolution of the control variable should match that of the measured variable.

Thanks John.

Thanks also to all the other contributors.

Other discussions cover measuring stability of power converters, what is the effect of PWM timer quantisation and what is the best converter for isolated bi-directional DC to DC.

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