SBAS951B August 2019 – April 2020 AMC1336
Isolated ΔΣ modulators are widely used in frequency inverter designs because of their high AC and DC performance. Frequency inverters are critical parts of industrial motor drives, photovoltaic inverters (string and central inverters), uninterruptible power supplies (UPS), and other industrial applications.
Figure 50 shows a simplified schematic of a frequency inverter application with the AMC1336 used for the DC-link and output phase voltage sensing. In this example, the ground reference point for the microcontroller is not connected by any means to the power stage. This configuration is usually the case in systems with the microcontroller located on a dedicated control card or PCB.
Current feedback is performed with shunt resistors (RSHUNT) and TI's AMC1306M25 isolated modulators. Depending on the system design, either all three or only two motor phase currents are sensed.
Depending on the overall digital processing power requirements and with a total of eight ΔΣ modulator bitstreams to be processed by the microcontroller (MCU), a derivate from either the low-cost single-core TMS320F2807x or the dual-core TMS320F2837x families can be used in this application.
Figure 51 shows an additional example of the AMC1336 used for input phase and DC-link voltage sensing. Also in this case, the microcontroller is located on a dedicated control card and the AMC1306M25 is used for shunt-based current sensing.