TIDUEZ9B July   2022  – April 2023

 

  1.   Description
  2.   Resources
  3.   Features
  4.   Applications
  5.   5
  6. 1System Description
    1. 1.1 Isolated Current Measurement
    2. 1.2 Band-Pass Filter
    3. 1.3 Analog-to-Digital Conversion
    4. 1.4 Arc Detection Algorithm
    5. 1.5 Key System Specifications
  7. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Current Transformer Circuit
      2. 2.2.2 Analog Band-Pass Filter
      3. 2.2.3 Analog-to-Digital Conversion
      4. 2.2.4 Power Supply
      5. 2.2.5 Debugging and Status Indication Options
    3. 2.3 Highlighted Products
      1. 2.3.1 TPS259474
      2. 2.3.2 TPS562202
      3. 2.3.3 TPS745
      4. 2.3.4 OPAx322
      5. 2.3.5 ADS8363
      6. 2.3.6 REF5025
      7. 2.3.7 TMDSCNCD280049C
  8. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware and Software Requirements
      1. 3.1.1 Hardware
      2. 3.1.2 Software
        1. 3.1.2.1 Arc Detection Theory
        2. 3.1.2.2 Software Implementation
    2. 3.2 Test Setup
      1. 3.2.1 ControlCARD Configuration
      2. 3.2.2 Setup for Hardware and Software Validation
      3. 3.2.3 Setup for Arc Testing
    3. 3.3 Test Results
      1. 3.3.1 Test Results of Hardware and Software Validation
      2. 3.3.2 Testing With Arcs
  9. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
    2. 4.2 Tools and Software
    3. 4.3 Support Resources
    4. 4.4 Trademarks
  10. 5About the Author
  11. 6Revision History

Testing With Arcs

Test results under real arcing conditions vary depending on the system. When no arcing is occurring, the values in AD_Result should be stable. During the arcing event there is a significant increase in the AD_Result value, which indicates the arc. The absolute values can differ depending on the already exiting noise in the system, the selected input method of internal or external ADC and the specified ArcTuningParams. As a starting point, the default values shown in Table 3-5 are recommended. Select B and I in a way that the inverter switching frequency is outside the frequency band defined by B and I. In case there are high AD_Result values also during non-arcing, increase parameter D to 0.1 or 0.2 or adjust the cutoff frequencies of the analog band-pass filter. Detailed testing of different parameters allows for identifying the best settings for each system. After defining these parameters, use the AD_Result value to implement a custom algorithm to detect arcing. This can be done in different ways, for example by simply implementing a threshold for AD_Result or applying some filtering to multiple consecutive values of AD_Result before comparing to the threshold.

Table 3-5 Default Values of ArcTuningParams Structure
NAME VALUE
float32 ArcTuningParams.B 30000
float32 ArcTuningParams.I 30000
float32 ArcTuningParams.F 64
float32 ArcTuningParams.D 0
int16 ArcTuningParams.T N/A
int16 ArcTuningParams.C N/A
float32 ArcTuningParams.ADSampleRate 250000