HV_SOLAR_DC_AC_v1.1 2p2z questions.

Jay Hong

Intellectual 865 points

Hi, experts.

I use TMDSHV1PHINVKIT and HV_SOLAR_DC_AC_v1.1 examples it works good.

I have plan to design 3K watt with this reference board design.

The problem is I don't know how to calculate the a0,a1,b0,b1,b2 's floating point parameters.

Please let me know it and where I can get a Biricha Digital PSU Design V1.3?

Best regards.

Jay.

over 13 years ago

0 Shamim Choudhury over 13 years ago

TI__Genius 12225 points

This will be very similar to analog current control loop design of any current source inverter. In this case the control being digital we need to calculate the digital controller coefficients an, bn.

This digital controller design requires information from your power stage schematic. When you have these info (L, C, sampling freq, current sense feedback, Vin etc.) you will use the grid-tie inverter current loop model equations and design the digital controller. I am attaching a matlab script file that contains the model equations for a similar inverter. The only difference is that this model uses L-C-L filter across inverter output. This is needed for achieving low THD and grid-tie capability at the same time. The inverter that you mentioned has a L-C filter only. So to grid tie that inverter you will need to add another L, making it a L-C-L filter and then redesign the current controller.

Pls use this matlab file and change the circuit parameters as per your schematic (3kW design). Then you have to use matlab SISOTOOL to look at the current loop Bode plot (loop gain plot) and design the an, bn coefficients. Attached file gives some tips on SISOTOOL just in case you are not familiar with it.

Shamim

8321.sisotool_4_PFC_loop_v2.pdf

0 Shamim Choudhury over 13 years ago in reply to Shamim Choudhury

TI__Genius 12225 points

Matlab script attached

http://e2e.ti.com/cfs-file.ashx/__key/communityserver-discussions-components-files/171/6886.Grid_5F00_Tie_5F00_Inverter_5F00_with_5F00_LCL_5F00_filter2.7z

0 Jay Hong over 13 years ago in reply to Shamim Choudhury

Intellectual 865 points

Dear Shamim.

I really appreciate your reply. But your information and method is hard to apply to my product for some reason.

What I want to know is how you calculate CNTL_2p2z static parameter.

For example, in case of Current loop for 52e-6 sample time, b2 = -0.3938, b1 = 0.1314, b0 = 0.5253 ,a2 = -0.01, a1 = 1.01, max = 0.4, min = -0.4 as below source.

Could you please support these calculation matlab.m file?

If I get this information I may change LC filter, IGBT, Current sensor to fit 3KW.