SNVAA30 December   2021 LM5170-Q1

 

  1.   Trademarks
  2. 1Introduction
    1. 1.1 Commercial Vehicle Power System
    2. 1.2 Operation of Battery Equalizer
  3. 2Designing Buck Converter with LM5170-Q1
    1. 2.1 VHV to VLV Buck Converter with 13-A Maximum Output Current
    2. 2.2 Inner Current Loop Design
    3. 2.3 Outer Voltage Loop Design
    4. 2.4 Implementation of Current Limit
  4. 3Experimental verification
  5. 4Conclusion
  6. 5References

1.2 Operation of Battery Equalizer

Battery equalizer has two modes to support stable power for both 12-V and 24-V loads.

Constant voltage mode

Figure 1-2 shows constant voltage operation of battery equalizer. When 12-V loads are low-powered, namely Iload ≪ Imax, the 24-V load becomes the main load of the two batteries. The battery equalizer keeps Batt_B voltage to be right at 50% of the total voltage of the two series batteries, such that the two battery capacities get well-balanced.

GUID-20211201-SS0I-6PRM-QFZC-MRVXMPVMTHFN-low.gifFigure 1-2 Constant Voltage Mode of Battery Equalizer

Constant current mode

Figure 1-3 shows constant current operation of battery equalizer. When 12 V loads consume high power, Batt_B is consumed faster than Batt_T. The battery equalizer will produce 12-V load current to prevent Batt_B from being discharged, therefore the two batteries remains the voltage balance. Obviously, the battery equalizer should provide Iout = Imax.

Figure 1-3 Constant Current Mode of Battery Equalizer