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MOSFET (Si/SiC) Forum Discussions

Rakesh_rp
Level 3
First solution authored 10 replies posted 10 questions asked
Level 3

Hi,

I am  testing the Infineon's  code  of  3.3kW semi - bridgeless dual boost PFC . In the code I found 3 lookup table  which is used for I_REF factor and DCM factor calculation. I didn't  understand the way lookup table is calculated . I want to calculate new Lookup  table for a different inductor value.  Below are the Lookup tables.

Rakesh_rp_0-1651834267985.png

Rakesh_rp_5-1651835036941.png

Rakesh_rp_6-1651835080464.png

 

 

 

 

 

 

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1 Solution
Vinay
Moderator
Moderator First like given 10 solutions authored 10 likes received
Moderator

Hello @Rakesh_rp,

Good Day!

 

The second lookup table reference current factor calculation (g_Iref_Factor) shall not change since the input voltage is greater than 195 V. Please refer to the Software and control implementation section in the application note High-efficiency 3 kW bridgeless dual-boost PFC

 

The first lookup table reference current factor calculation (g_Iref_Factor) will change with respect to N_VIN, please refer to the 'G' column of the excel sheet attached. The Input voltage sensitivity and the input current sensitivity can be seen in the "Schematic of the digital controller daughter card" section in the application notes High-efficiency 3 kW bridgeless dual-boost PFC

 

For an input voltage sensitivity of 469.44V/2.5v --> N_VIN = 938.88V

For an input voltage sensitivity of 106.667V/1v --> N_VIN = 533.335V

 

The third lookup table Duty ratio factor calculation (g_DCM_Factor) will change with respect to N_VIN and L, please refer to the 'K' column of the excel sheet attached.

 

Please try testing with the values present in the G and K columns in the excel sheet attached for the first and third lookup tables.

 

Thank you!

 

Best regards,

Vinay

Best Regards,
Vinay

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Vinay
Moderator
Moderator First like given 10 solutions authored 10 likes received
Moderator

Hi @Rakesh_rp,

 

Thanks for posting your question in Infineon Community.

 

The Lookup tables are calculated for the inductor 240e-6H.

 

What is the inductor value, you are testing for 3.3 Kw semi-bridgeless dual boost PFC?

 

Whether you are replacing the 240 uH inductor with a new inductor in the evaluation board?

 

Best regards,

Vinay

Best Regards,
Vinay
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Rakesh_rp
Level 3
First solution authored 10 replies posted 10 questions asked
Level 3

Thanks for replying,

I am working on a customized power board, where the  sensitivity of voltage sense and current sense are different . The inductor value is  265uH . The sensitivity for input voltage sense is  1v/106.667VAC  . The sensitivity for input current sense is 1v/7.5A. So we want to modify all three lookup table.

 

Regards ,

Rakesh 

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Vinay
Moderator
Moderator First like given 10 solutions authored 10 likes received
Moderator

Hello Rakesh,

 

What is the input voltage range you are using for your testing?

 

Best regards,

Vinay

Best Regards,
Vinay
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Rakesh_rp
Level 3
First solution authored 10 replies posted 10 questions asked
Level 3

Thanks for replying,

The input AC RMS voltage is between 200v to 250 v.

Regards,

rakesh

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Rakesh_rp
Level 3
First solution authored 10 replies posted 10 questions asked
Level 3

Hi,

Waiting for your reply

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Vinay
Moderator
Moderator First like given 10 solutions authored 10 likes received
Moderator

Hello @Rakesh_rp,

Good Day!

 

The second lookup table reference current factor calculation (g_Iref_Factor) shall not change since the input voltage is greater than 195 V. Please refer to the Software and control implementation section in the application note High-efficiency 3 kW bridgeless dual-boost PFC

 

The first lookup table reference current factor calculation (g_Iref_Factor) will change with respect to N_VIN, please refer to the 'G' column of the excel sheet attached. The Input voltage sensitivity and the input current sensitivity can be seen in the "Schematic of the digital controller daughter card" section in the application notes High-efficiency 3 kW bridgeless dual-boost PFC

 

For an input voltage sensitivity of 469.44V/2.5v --> N_VIN = 938.88V

For an input voltage sensitivity of 106.667V/1v --> N_VIN = 533.335V

 

The third lookup table Duty ratio factor calculation (g_DCM_Factor) will change with respect to N_VIN and L, please refer to the 'K' column of the excel sheet attached.

 

Please try testing with the values present in the G and K columns in the excel sheet attached for the first and third lookup tables.

 

Thank you!

 

Best regards,

Vinay

Best Regards,
Vinay
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Rakesh_rp
Level 3
First solution authored 10 replies posted 10 questions asked
Level 3

Thanks for replying,

Thanks for the excel sheet.

In the present PFC code ,the first Lookup table( VIN_RMS_TAB1)  is used  when Vin >195v and second  Lookup table ( VIN_RMS_TAB2)  is used  when Vin<195v. Both  lookup table is calculated  by taking  N_VIN= 938.88v  as sensitivity  . So for N_VIN =533.33V  all Lookup table needs to be modified.

In the excel sheet , the values are calculated by taking  resolution as 0.91v which I feel is wrong .  For  N_VIN  = 533.33V , the  resolution should be 0.52 as per  formula given above the lookup table in present PFC code. 

Regards,

Rakesh

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Vinay
Moderator
Moderator First like given 10 solutions authored 10 likes received
Moderator

Hi @Rakesh_rp ,

Good Day!

 

Yes, you are correct, the first lookup table ( VIN_RMS_TAB1) and the second lookup table ( VIN_RMS_TAB2) shall change with respect to N_VIN. But as the input voltage range is 200 to 250 Vrms, the reference current factor shall be taken from the first lookup table. So if you calibrate the second lookup table for N_VIN = 533.33V, the reference current factor shall be taken from the first lookup table as the input voltage is greater than 195 Vac. If you want to change the second lookup table, you can follow the same procedure as the first, but you can use the denominator (200*N_VIN_RMS) instead of (V_IN_RMS^2).

 

Yes, the resolution for N_VIN = 533.33V is 0.52V. Resolution is used in V_IN_RMS increment steps. As the input voltage range ( 200V to 250 V) is within V_IN_RMS (59.59V……280.56V) range, we don’t want to change the resolution, as it will increase the number of values of V_IN_RMS thereby increasing the number of values of UIN_RMS_TAB1.

 

Thank you!

 

Best regards,

Vinay

Best Regards,
Vinay
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