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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.

Solved! Go to Solution.

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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

Vinay

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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

Vinay

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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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Hello Rakesh,

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

Best regards,

Vinay

Vinay

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Thanks for replying,

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

Regards,

rakesh

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Hi,

Waiting for your reply

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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

Vinay

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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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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

Vinay