Low-side current sensing is featured as using shunt resistor at low side, a differential amplifier, and ADC to measure the load current.
It is straightforward to use this shunt resistor method for DC current. But for a PWM three phase inverter shown in the figure, the current flowing through the shunt resistor will be PWM since it will alternate between the upper switch and the lower switch in the phase leg due to the switching behavior. Then how can this approach serve the purpose of measuring phase currents and do close loop motor control?
By the way, TI high voltage motor control board use this technique to measure phase currents, too.
Can anyone make it clear? Thanks in advance!
It is straightforward to use this shunt resistor method for DC current. But for a PWM three phase inverter shown in the figure, the current flowing through the shunt resistor will be PWM since it will alternate between the upper switch and the lower switch in the phase leg due to the switching behavior. Then how can this approach serve the purpose of measuring phase currents and do close loop motor control?
By the way, TI high voltage motor control board use this technique to measure phase currents, too.
Can anyone make it clear? Thanks in advance!
