SLUAB06 January   2025 AMC131M02 , AMC3330 , ISO7731

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Topologies for Insulation Monitoring in ESS
    1. 2.1 Single Switch Topology
      1. 2.1.1 Test Steps
    2. 2.2 Dual Switch Floating Sampling Topology
      1. 2.2.1 Test Steps
    3. 2.3 Dual Switch Sampling in High Voltage Side Topology
    4. 2.4 AC Injection Topology
  6. 3Comparison of Designs
    1. 3.1 Injection Resistance Influence on Accuracy
  7. 4Capacitor Influence on Sampling Time
    1. 4.1 How to Choose Y Capacitor
    2. 4.2 Sampling Time
  8. 5Key Devices
    1. 5.1 BQ79731-Q1
    2. 5.2 UCC33421-Q1
    3. 5.3 AMC131M02
    4. 5.4 AMC3330
    5. 5.5 ISO773x
  9. 6Topos Simulation Result and Conclusion
  10. 7Summary
  11. 8References

2.4 AC Injection Topology

In AC injection method, the insulation resistance of the system is obtained by injecting a low voltage AC signal between the positive and negative terminals of the power battery at a certain frequency. The disadvantage is that the test signal creates ripple interference in the system, which affects the normal operation of the system. AC Injection need high accuracy AD/DA, injection capacitor, current sense. RMS detection, low pass, band pass, analyze detected signal… this can be done in dozens milliseconds. Due to the uncertainty about the accuracy, it does not need to be analyzed in this article.

AC Injection Insulation Test Topology Figure 2-21 AC Injection Insulation Test Topology