PFC Inductor value estimation

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sudip_k
Level 2
Level 2
25 sign-ins 10 replies posted 10 questions asked

Hi I have IMC30A eval board and I want to use the PFC feature to provide  pfc and universal input voltage. But I cannot find any resources to calculate the required inductance for the application. 

Design requirement:

Input voltage: 85 to 240VAC(50-60Hz)

load current max 2.5A(RMS)

Please help!

 

 

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1 Solution
psb
Moderator
Moderator
Moderator
250 sign-ins 25 solutions authored 100 replies posted

Hello @sudip_k , 

For calculating the value of PFC Inductor, you can follow the following steps, in case it is a boost converter. 

  1.  Fix a value for the maximum peak current with ripple allowed. For this please fix or back calculate the percentage (say, k) of current for maximum allowable peak to peak inductor current ripple. Typically peak to peak ripple as 20% of inductor current should be ok. 
  2. Is the maximum rms current of 2.5A calculated for the minimum voltage ? What is the full load power ranges of the PFC for the given voltage range ? These things must be duly noted. 
  3. Say that at input voltage, with peak equal to Vinpeak, the maximum current of 2.5A rms is specified, then the peak to peak current ripple at the peak of the current is
                                          Iripple = 0.01*k*2.5*sqrt(2) = [(Vinpeak)*(duty ratio)/(fsw*Inductance)],
    where all the quantities are in the SI units. 
  4. The value of Inductance should be back calculated from the above expression. 
  5. The value of Inductance must always be back calculated from the ripple current at the peak of maximum current. 

Hope this helps !

Best Regards,
Sai

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1 Reply
psb
Moderator
Moderator
Moderator
250 sign-ins 25 solutions authored 100 replies posted

Hello @sudip_k , 

For calculating the value of PFC Inductor, you can follow the following steps, in case it is a boost converter. 

  1.  Fix a value for the maximum peak current with ripple allowed. For this please fix or back calculate the percentage (say, k) of current for maximum allowable peak to peak inductor current ripple. Typically peak to peak ripple as 20% of inductor current should be ok. 
  2. Is the maximum rms current of 2.5A calculated for the minimum voltage ? What is the full load power ranges of the PFC for the given voltage range ? These things must be duly noted. 
  3. Say that at input voltage, with peak equal to Vinpeak, the maximum current of 2.5A rms is specified, then the peak to peak current ripple at the peak of the current is
                                          Iripple = 0.01*k*2.5*sqrt(2) = [(Vinpeak)*(duty ratio)/(fsw*Inductance)],
    where all the quantities are in the SI units. 
  4. The value of Inductance should be back calculated from the above expression. 
  5. The value of Inductance must always be back calculated from the ripple current at the peak of maximum current. 

Hope this helps !

Best Regards,
Sai
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