To balance the current between each phase, a high-precise current sensing amplifier INA241 can be used in this proposed design. The INA241 is an ultra-precise, bidirectional current sense amplifier that can measure voltage drops across shunt resistors over a wide common-mode range from –5 approximately 110V, independent of the supply voltage. The high-precision current measurement is achieved through a combination of low offset voltage (±10µV, maximum), ultra-low gain error (±0.01%, maximum) and a high DC CMRR (typical 166dB). The INA241 is designed for high voltage, bidirectional measurements in switching systems that see large common-mode voltage transients at the device's inputs. The enhanced PWM rejection circuitry inside the INA241 to make sure the minimal signal disturbance at the output due to the common-mode voltage transitions at the input. The INA241 is available in five gain options: 10V/V, 20V/V, 50V/V, 100V/V, and 200V/V. Multiple gain options allow for optimization between available shunt resistor values and wide output dynamic range requirements.

For reducing the cost, customers can use the resistance of the inductor to monitor the current of each phase. The ripple voltage of the inductor is a high-frequency alternative voltage and the average value equals 0V, but the direct voltage indicates the current through the inductor. So, a low pass filter can be used to filter the AC component and get DC current for the controller to monitor and adjust the phase current equally. The detailed circuit as shown in Figure 3-2. The current can easily be obtained by Equation 3.