3 Experimental verification

The buck converter operation is verified by Texas Instruments LM5170EVM-BIDR evaluation module, as shown in Figure 3-1. The board is modified according to Figure 2-1 to implement the battery equalizer.

Figure 3-1 Test Board (Texas Instruments LM5170EVM-BIDIR Modified)

Figure 3-2 shows the measured buck converter efficiency versus output current.

Figure 3-2 Buck Converter Efficiency

During constant voltage mode of battery equalizer, buck converter should keep constant ratio between input voltage and output voltage. Figure 3-3 shows transition of V_LV depending on V_HV (V_HV = 2 × V_LV).

Figure 3-3 Input Voltage and Output Voltage Waveform in Constant Voltage Mode

During constant current mode of battery equalizer, the buck converter keeps the maximum output current. As shown in Figure 3-4, the output current (I_out) is maintained at 13 A (I_max) approximately. LM5170-Q1 IOUT pin is used to measure output current.

Figure 3-4 Input Voltage and Output Current Waveform in Constant Current Mode

Figure 3-5 Start-up Sequence of Buck Converter