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DC Motor Drive DC Bus capacitor design

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Hi Guys

Need some advice on designing DC bus capacitors for a 3HP DC motor drive. Any useful articles with proper calculation derivations are appreciated so are any tips and hints from your experience.

I know what the purpose of such capacitors is;
1) Limit the Voltage ripple on DC bus due to stray inductance
2) Limit the high frequency currents flowing in the battery

I have simple calculations that can give me a quick answer but I want to know it from first principles if possible.

Cheers everyone, hoping to get some interesting answers.
 

3 HP translates into a couple kW of power. Are you switching that much current at high frequency?

A DC motor is known to produce spikes/noise due to commutation.

Also fluctuations at supply rails in case the motor draws varying current amounts as it drives a non-constant load.

Since these are not always predictable it makes it hard to predict what size capacitors you need ahead of time.
 

200A (avg) is max current. Switching at 5Khz.

Also fluctuations at supply rails in case the motor draws varying current amounts as it drives a non-constant load.
That is true, but worst case assumption is that you design them for 50% duty cycle where maximum ripple occurs... anyone else got ideas???
 

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