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BQ79731-Q1: Insulation Resistance Test

Louis Huang
Prodigy 50 points
Part Number: BQ79731-Q1


Tool/software:

Hi TI expert,

Insulation resistance test design based on sluab06 application note.
I have some unclear questions to ask.

The dielectric voltage test for 1500V system is 4380V, but why the HV(BAT+/BAT-) and PE need up to 5880V(4380V+1500V)?

There has not define the 5880V test condition in GB/T 34131.

  • 0
    TI__Prodigy 510 points

    Hi Louis,

    GB/T 34131 need 4380V dielectric voltage in 1500V BMS, but while do dielectric voltage test, for example, conducting 4380V  between HV+ and PE, but there is 1500V between HV+ and HV-, so voltage that the circuit actually withstand is 4380V+1500V.

  • 0 in reply to Harrison Yang
    Prodigy 50 points

    Thanks Harrison, I understood your explained.
    In the Figure, the S2 can choose solid state relays or Photo MOS.
    Do you have suggest parts which can withstand 5880V of SSR or Photo MOS?
    And what is the RLn purpose in the fiqure?
    How to compare the SW1/SW2/SW3 in the (2.1.1) test steps for the Figure?

  • 0 in reply to Louis Huang
    TI__Prodigy 510 points

    Q1:We currently just have TPSI2140, 1200V,  you can also choose other reed relay or Photo MOS.

    Q2:RLn purpose: When SSR is disconnected, the resistance of SSR is regarded as infinite and bears too much withstand voltage, and if it has RLn, the withstand voltage on the switch will be much lower.

    Q3:Sorry, you can refer to following step that adapted to picture 2.1 more:

    1. Open S1, S2 and wait voltage at ADC to settles (500us), get VN1, V DC=2VN1.
    2. Close S1 and open S2 (400us delay) , wait until voltage at ADC settles (500us), get VNoff.
    3. Close S1, S2 , wait until voltage at ADC settles (500us), get VNon.