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

2.2.1 Test Steps

  1. Close SW1 and SW3, open SW2, get V+.
  2. Close SW2 open SW1, get V-.
  3. Put V+ and V- into Risop and RisoN calculate formula.

Based on the operating mode of the two circuits, the formula for calculating RisoP and RisoN is as follows:

Equation 3. Rp=VDC+VBn1-VBn1×VBpVBp-VDCVBn1R3+R4+RL1+VBp×VBn1R1+R2×(VBp-VDC)-VDC+VBn1R1+R2+RLh-VBn1R3+R4
Equation 4. Rn=-11R3+R4+RL1+VBpR1+R2×(VBp-VDC)+VBpRp×(VBp-VDC)

The error of the injection resistance, the error of the sampling resistance, and the error of the high voltage detection are taken into account in the calculation formula, the worst accuracy is obtained:

Worst Case for Topo 2Figure 2-14 Worst Case for Topo 2