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

1 Introduction

Energy storage power station is a complex industrial system, involving energy storage converters, energy storage batteries and management systems and other electrical equipment, so to avoid system short circuit, Or the leakage current is high, to the user, so the insulation inspection system of the energy storage power station is critical to the safety of the energy storage power station operators. At the same time, insulation monitoring can also avoid insulation failure damage to end equipment, improve the service life of the equipment.

If you can make sure that the insulation is good enough when you touch any two points, then safety can be improved. When the energy storage system is operating, the positive side of Figure 1-1 represents the positive side of the high voltage battery pack, the negative side represents the negative side of the high voltage battery, and the PE represents the enclosure. RisoP is the equivalent resistance between the high voltage negative and the enclosure, RisoN is the high voltage positive and the enclosure equivalent, V1 stands for the voltage between the high voltage negative and the enclosure as monitored by the BMS and V2 stands for the voltage between the high voltage positive and the enclosure as monitored by the BMS; if any one of he resistance values of RisoP or is RisoN is designed for greater than the threshold specified by the national standard, then the human body is safe despite mistakenly touching any two place of the high voltage positive, high voltage negative and enclosure .

Insulation System in Energy Storage SystemFigure 1-1 Insulation System in Energy Storage System

For the system performance of the energy storage system, GB/T34131 gives some indicators on voltage, current, temperature sampling and insulation resistance monitoring:

Table 1-1 Requirements for Voltage, Current, Temperature, Insulation Resistance Accuracy in GB/T34131
ScopeErrorPeriod
Battery cell voltage<5V≤0.005V≤100ms
5 approximately 15V≤0.2%
Battery cluster voltage<500V≤5V≤100ms
≥500V≤1%
Battery cluster current<200A≤2A≤50ms
≥200A≤1%
Cell temperature-20 approximately 65≤1℃≤1s
[-40,-20)U(65,125]≤2℃
Insulation resistor(≥400V)R≤75kΩ≤±15kΩ
R>75kΩ≤±20%

Creepage distances and electrical clearances are also important areas of focus in the design of energy storage insulation monitoring. In the European market in the energy storage sector, suppliers mainly refer to IEC62619, in the North American market, the main supplier reference regulation is UL1973, The electrical clearance and creepage distances sections of both regulations are referenced to IEC60664. This paper therefore summarizes electrical clearance and creepage distances for 1000V/1500V/2000V systems in IEC60664.

Table 1-2 Creepage Distance and Clearance Requirements in 1000V Energy Storage Systems
VoltageTypePollution degreeCTIOVCAltitude/mCLR/mmCRP*/mm
1000VBasicⅡⅠOVC-Ⅱ(6000)<2000m5.55.5
4000m7.17.1
OVC-Ⅲ(8000)<2000m88
4000m10.410.4
ReinforcedOVC-Ⅱ(8000)<2000m88
4000m10.410.4
OVC-Ⅲ(12000)<2000m1414
4000m18.118.1
Table 1-3 Creepage Distance and Clearance Requirements in 1500V Energy Storage Systems
Voltage Type Pollution degree CTI OVC Altitude/m CLR/mm CRP*/mm
1500V Basic Ⅱ Ⅰ OVC-Ⅱ(8000) <2000m 8 8
4000m 10.4 10.4
OVC-Ⅲ(10000) <2000m 11 11
4000m 14.2 15.1
Reinforced OVC-Ⅱ(12000) <2000m 14 15.1
4000m 18.1 18.1
OVC-Ⅲ(16000) <2000m 19.4 19.4
4000m 25.1 25.1

GB/T 34131 also requires insulation voltage tests and dielectric strength test. Take 1500V BMS as an example, Insulation voltage testing refers to following four places(①②③④) shall withstand 1500V DC voltage Lasts one minute and the insulation resistance value shall not be less than 10MΩ.

  • Between the battery-connected acquisition terminal and the ground terminal.
  • Between the communication terminal and the earth terminal.
  • Between the acquisition terminal and the communication terminal.
  • Between the supply terminal and the communication terminal.
Insulation voltage testsFigure 1-2 Insulation voltage tests

Dielectric strength test refers to following five places(①②③④⑤) shall withstand a DC voltage of 4380V for 1 minute, there needs to be no insulation breakdown and flashover and leakage current needs to be less than 10mA.

  • Between the battery-connected sampling terminal and the ground terminal.
  • Between the communication terminal and the ground terminal.
  • Between the sampling terminal and the supply terminal.
  • Between the sampling terminal and the communication terminal.
  • Between the supply terminal and the communication terminal.
Dielectric strength testsFigure 1-3 Dielectric strength tests

Test tips:

  1. Non-electrification, disconnect PE, HV and communication;
  2. While do ① test, between HV(BAT+/BAT-) and PE, circuit needs to withstand 5880V(4380V+1500V), because battery cluster voltage is included in.