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Original question:

[FAQ] MSP-EM-DESIGN-CENTER: Announcing the new Energy Measurement Design Center (EMDC) and Software Library for MSP430 MCUs...

CCS/MSP-EM-DESIGN-CENTER: Inaccuracy current, power, PF in lower PF (ex: PF = -0.7 [CF=2.5], PF = 0.5 [CF=3.5]) in EMDC and EVM430-i2040S

Bob Liao
Prodigy 70 points
Part Number: MSP-EM-DESIGN-CENTER
Other Parts Discussed in Thread: EVM430-I2040S, MSP430I2040, MSP430I2041, , MSP430F5529, MSP-ISO

Tool/software: Code Composer Studio

Hi,

We use EVM430-i2040S with EMDC to test its measurement accuracy, and the results are as follows.
We observe there are inaccurate current, power, PF in lower PF (ex: PF = -0.7 [CF=2.5], PF = 0.5 [CF=3.5]).
We also try to change sample frequency to 8K or 16K in EMDC, and the result are similar as the default 4K sample frequency.

Could anyone please solve this problem ?

Thanks.

test condition EVM430-i2040S meter:CP268 error
freq V I PF V I W PF V I W PF V err I err W err PF err
50 220 2 1 220.486 1.991412 436.845148 0.9959 220.6882 1.99146 436.4825 0.993153 -0.09% 0.00% 0.08% 0.28%
50 220 2 -0.7(CF=2.5) 220.509 1.946683 289.958774 0.9887 220.769 1.969176 290.3304 0.6678361 -0.12% -1.14% -0.13% 48.05%
50 220 2 0.5(CF=3.5) 220.486 1.873552 207.367171 0.9901 220.7694 1.947448 205.0663 0.4769683 -0.13% -3.79% 1.12% 107.58%

Environment:

1. Use the default EVM430-i2040S_1V_1C_50Hz config in EDMC to generate CCS codes

2. The EVM is EVM430-i2040S, but MSP430i2041 is replaced by MSP430i2040

3. The source is CIF-1030EP, the loader is PG32612, and the meter is CP-268

4. The error value is got by ( test value - meter value) / meter value / 100

  • 0
    TI__Genius 10860 points

    Hi Bob,

    thanks for reaching out to us in order to troublehoot this issue.

    Please let me clarify some of the information you shared above.

    You stated that instead of using the MSP430i2041 you are using the MSP430i2040. Is this correct? Please note that the new Energy Measurement Design Center does not support MSP430i2040.

    Please let me know if you see the same problem when using one of the supported devices, such as MSP430i2041 for example.

    Thanks and best regards,

    Britta

  • 0 in reply to Britta Ruelander
    Prodigy 70 points

    Dear Britta Ruelander

    Because we don't have MSP430i2041 chip currently and we will use MSP430i2040 instead of MSP430i2041 to develop codes in the future, we use MSP430i2040 to test measurement accuracy.

    The following steps are our changes for MSP430i2040, and are these changes OK for MSP430i2040 in EDMC ?

    Thanks.

    1. Generate CCS project codes with the device is MSP430i2041

    2. Change the device of the project from MSP430i2041 to MSP430i2040 in CCS

    3. Change the 'Set C system stack size' of the project from 256 to 128 in CCS

    4. Build codes and burn it to the EVM

  • 0 in reply to Bob Liao
    TI__Mastermind 49692 points
    Hello Bob,

    I'm happy to see that you're using the new MSP-EM-DESIGN-CENTER. Also, thanks for clearly describing what you've done.

    First, I'll echo what has already recommended. When you get a chance, order some MSP430i2041 devices to try. We don't support the MSP430i2040 out-of-the-box since the RAM requirements exceed 1KB and the Flash requirements are over 90% of 16KB. Thus, we recommend users use the MSP430i2041. Since you've adjusted the C system stack size, the code will fit on the MSP430i2040, but this could be causing an issue and affecting the accuracy. Switching to MSP430i2041 will help us rule this out.

    Alternatively, you may need to re-calibrate the device. The provided EVM430-i2040S_1V_1C_50Hz example project includes default calibration factors that were based on my calibration of an EVM430-i2040S board using our high voltage test equipment, MTE PTS3.3C, at 230Vrms, 1Arms for gain calibration (0 degrees, PF = 1) and phase calibration (+60 degrees, PF = 0.5). Keep in mind that these calibration factors are just a basis for getting started. There are system-level (e.g. passives, PCB, sensor) differences and device-level (e.g. silicon) differences that could be causing this accuracy error on your EVM. Since you have test equipment, please try recalibrating the EVM430-i2040S and check the accuracy again.

    Regards,

    James

    MSP Customer Applications
  • 0 in reply to James Evans
    Prodigy 70 points
    Hi, James

    Thanks for your reply.

    We will use MSP430i2041 to calibrate and test the device later.
  • 0 in reply to Bob Liao
    Prodigy 70 points

    Hi James,

     

    We used EVM430-i2040S with MSP430i2041 in EMDC.

    But its accuracy results were similar as previous test results.

    Could you please solve this problem ?

    Thanks.

     

    Step:

    1. Used MSP430i2041 instead of MSP430i2040 in EVM430-i2040S
    2. Used the default EVM430-i2040S_1V_1C_50Hz config in EDMC to generate CCS codes
    3. Burned the CCS codes to EVM430-i2040S
    4. Calibrated gain at 220V, 8A, and PF =1
    5. Calibrated phase at 220V, 8A, and PF = 0.5
    6. Tested the accuracy

    test condition

    EVM430-i2040S (MSP430i2041)

    meter:CP268

    error

    Freq

    V

    I

    PF

    V

    I

    W

    PF

     V

    I

    W

    PF

    V

    I

    W

    PF

    50

    220

    1

    1

    220.055

    0.985214

    217.206386

    0.9838

    220.7668

    0.9840003

    214.0663

    0.9854153

    -0.32%

    0.12%

    1.47%

    -0.16%

    50

    220

    1

    -0.7

    220.102

    0.943761

    140.331727

    0.9888

    220.8243

    0.9559787

    136.9152

    0.6485696

    -0.33%

    -1.28%

    2.50%

    52.46%

    50

    220

    1

    0.5

    220.149

    0.885298

    89.877288

    0.8966

    220.8611

    0.9262328

    94.89674

    0.4638867

    -0.32%

    -4.42%

    -5.29%

    93.28%

    50

    220

    2

    1

    220.008

    1.993733

    439.997791

    0.9782

    220.652

    1.992659

    436.9918

    0.9938766

    -0.29%

    0.05%

    0.69%

    -1.58%

    50

    220

    2

    -0.7

    220.079

    1.952358

    298.325925

    0.9885

    220.7397

    1.969811

    290.253

    0.6675314

    -0.30%

    -0.89%

    2.78%

    48.08%

    50

    220

    2

    0.5

    220.102

    1.880478

    195.478303

    0.9033

    220.7941

    1.948259

    205.1427

    0.4768941

    -0.31%

    -3.48%

    -4.71%

    89.41%

    50

    220

    8

    1

    219.56

    8.029211

    1762.980086

    0.9722

    219.7857

    8.0243

    1761.559

    0.9988278

    -0.10%

    0.06%

    0.08%

    -2.67%

    50

    220

    8

    -0.7

    219.678

    7.952989

    1233.671698

    0.9876

    220.0602

    8.011916

    1205.658

    0.683827

    -0.17%

    -0.74%

    2.32%

    44.42%

    50

    220

    8

    0.5

    219.796

    7.781553

    817.186722

    0.9067

    220.2778

    8.00466

    856.2625

    0.4856164

    -0.22%

    -2.79%

    -4.56%

    86.71%

     

     

     

     

  • 0 in reply to Bob Liao
    TI__Mastermind 49692 points

    Bob Liao said:

    We used EVM430-i2040S with MSP430i2041 in EMDC.

    But its accuracy results were similar as previous test results.

    Thanks for trying this.

    As I mentioned in the other post, I'm not sure that you're calibrating the EVM accurately, especially if the source is changing at different currents. I've got several other priorities that I'm working on at the moment, but in the next week, I'll try to find some time in the lab with the EVM430-i2040S and our test setup to rule out any EMDC issues.

    How are you powering the EVM430-i2040S? What are your jumper settings? Are you using the recommended MSP-ISO and MSP430F5529 LaunchPad for the communication with EMDC? If so, you may have conflicting power domains because we made a mistake in the MSP-ISO connections. Essentially, there's a possibility that the device is getting powered by the MSP-ISO through the UART pins or from the isolated 3.3V supply on the MSP-ISO. We've revised the connection tables and asked user's to remove J3. You can find the updated connection tables in the following thread.

    Regards,

    James

    MSP Customer Applications

  • 0 in reply to James Evans
    Prodigy 70 points

    How are you powering the EVM430-i2040S? What are your jumper settings? Are you using the recommended MSP-ISO and MSP430F5529 LaunchPad for the communication with EMDC? If so, you may have conflicting power domains because we made a mistake in the MSP-ISO connections. Essentially, there's a possibility that the device is getting powered by the MSP-ISO through the UART pins or from the isolated 3.3V supply on the MSP-ISO. We've revised the connection tables and asked user's to remove J3. You can find the updated connection tables in the following thread.

    We use optoisolators to connect EVM430-i2040S and MSP430F5529 LaunchPad, so EVM430-i2040S can't get powered through the UART channel.

  • 0 in reply to Bob Liao
    TI__Mastermind 49692 points
    Hi again Bob,

    Thanks for the additional details. I haven't been able to get into the lab yet due to equipment availability, but I'm planning to spend some time testing in the lab to check for these inaccuracies. I'll keep you posted.

    Regards,

    James

    MSP Customer Applications
  • 0 in reply to Bob Liao
    TI__Mastermind 49692 points

    Hello Bob,

    I've finally been able to complete the testing in the lab. Using EMDC and the EVM430-i2040S, I was able to get strong performance and couldn't replicate the inaccuracies that you're observing.

    For your reference, here's a table similar to yours indicating the error that I observed. Based on these findings, I would recommend getting an accurate test setup rather than using another off-the-shelf meter and a possibly inaccurate source as a reference.

    test condition         EVM430-i2040S (MSP430i2041) PTS 3.3C error
    Freq V I PF ○ V I W PF  V I W PF = cos(○) V I W PF
    50 220 1 1 0 220.031 1.001 220.162 1 220 1 220 1 0.01% 0.10% 0.07% 0.00%
    50 220 1 -0.7 -45 220.055 1.001 155.686 0.7069 220 1 155.5635 0.7071068 0.03% 0.10% 0.08% -0.03%
    50 220 1 0.5 60 220.031 1.001 110.139 0.5001 220 1 110 0.5 0.01% 0.10% 0.13% 0.02%
    50 220 2 1 0 220.079 2.001 440.349 1 220 2 440 1 0.04% 0.05% 0.08% 0.00%
    50 220 2 -0.7 -45 220.031 2.001 311.504 0.7076 220 2 311.127 0.7071068 0.01% 0.05% 0.12% 0.07%
    50 220 2 0.5 60 220.031 2.002 220.074 0.4995 220 2 220 0.5 0.01% 0.10% 0.03% -0.10%
    50 220 8 1 0 220.055 7.999 1759.71 1 220 8 1760 1 0.03% -0.01% -0.02% 0.00%
    50 220 8 -0.7 -45 220.055 7.998 1244.84 0.707 220 8 1244.508 0.7071068 0.03% -0.02% 0.03% -0.02%
    50 220 8 0.5 60 220.031 7.999 879.628 0.4998 220 8 880 0.5 0.01% -0.01% -0.04% -0.04%

    I used the same calibration point that you did as well.

    Calibration          
    Type Freq V I PF Phase Angle
    Gain 50 220 8 1 0
    Phase 50 220 8 0.5 60

    Regards,

    James

    MSP Customer Applications

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