SDAA096 October 2025 LM51561 , MSPM0G3507 , SN6507
2 Discrete Topo Comparison
Discrete active cell balancing typically has the following topologies: switch capacitor method
- Flying capacitor method
- Inductance energy storage method
- Transformer method
- DC/DC converter with switch matrix method
Among these, the DC/DC converter with switch matrix method stands out due to the high flexibility, allowing for energy transfer between any cell and balancing across modules. The modular design also facilitates maintenance.
Next, take two types of charge and discharge circuit modes as examples to analyze the working modes of the circuit.
Take cell2 charging as an example, turn on PWM2, PWM3, and PWMB:
Figure 2-1 ACB
Working Mode1: Cell2 DischargeTake cell9 discharging as an example. Turn on PWM9, PWM10 and PWMA. The charging path is shown in Figure 2-2. The bidirectional DC/DC operates in boost mode, transferring the excess voltage from the battery cell to the bus.
Figure 2-2 ACB
Working Mode2: Cell9 ChargeBased on the status of the charging and discharging switches, the following operating mode table can be obtained. The bidirectional DC-DC operates in buck mode, transferring energy from the 24V bus to the lower voltage cells.
| Status | Cell | Channel |
|---|---|---|
| Charge | Odd | PWM_A |
| Even | PWM_B | |
| Discharge | Odd | PWM_B |
| Even | PWM_A |