Reinforced Isolated Phase Current Sensing Reference Design with Small Delta-Sigma Modulator

This reference design implements a reinforced isolated three-phase inverter subsystem using isolated IGBT gate drivers and isolated current/voltage sensors. This design uses the AMC1306E25 delta-sigma modulator for accurate shunt-based inline motor phase current sensing. The modulator output is Manchester encoded, simplifying clock and data signal routing between the MCU and the modulator. The modulator's high CMTI helps suppress inverter switching noise transients from causing data corruption on the controller side. A compact solution is achieved using a small size modulator. TIDA-00914 provides an interface to an external MCU or FPGA so that a SINC digital filter can be used to demodulate the AMC1306E25 output bit stream. This reference design uses the F28379D Delfino control card, which is connected to the card described in the reference design via an adapter card for current sensing using SINC filters.

characteristic

• ● Manchester encoded data output simplifies clock routing to delta-sigma modulator
• ● Small pin count (8) enables compact solution
• ● Modulator features high CMTI (>50kV/us), resulting in improved noise immunity to switching transients
• ● Short circuit response time is less than 1.5µs
• ● Calibrated full-scale accuracy <0.5% over temperature range 0 ^° C to 55 ^{° C}
• ● Nominal phase current measurement range is 28Arms, peak measurement range is +/-80Apk