SPRACR6 April   2020 TMS320F280023-Q1 , TMS320F280023C , TMS320F280025C , TMS320F280025C-Q1 , TMS320F280041-Q1 , TMS320F280041C , TMS320F280041C-Q1 , TMS320F280048-Q1 , TMS320F280048C-Q1 , TMS320F280049-Q1 , TMS320F280049C , TMS320F280049C-Q1 , TMS320F28384D , TMS320F28384D-Q1 , TMS320F28384S , TMS320F28384S-Q1 , TMS320F28386D , TMS320F28386D-Q1 , TMS320F28386S , TMS320F28386S-Q1 , TMS320F28388D , TMS320F28388S , TMS320F28P650DH , TMS320F28P650DK , TMS320F28P650SH , TMS320F28P650SK , TMS320F28P659DK-Q1

 

  1.   Distributed Power Control Architecture With Multiple MCUs Over FSI
    1.     Trademarks
    2. 1 Introduction
    3. 2 Distributed Power Control Architecture
      1. 2.1 Distributed Power Control Architecture – DC/AC System
      2. 2.2 Distributed Power Control Architecture – AC/DC System
      3. 2.3 Distributed Power Control Architecture – DC/DC System
    4. 3 DC/AC System - Power Topologies
      1. 3.1 MPPT DC/DC Stage
      2. 3.2 DC/AC Inverter Stage
    5. 4 C2000 Controller Configuration for DPCA DC/AC System
    6. 5 Communication Interface – FSI for DPCA DC/AC System
      1. 5.1 FSI Star Connection
      2. 5.2 FSI Daisy Chain Connection
      3. 5.3 FSI Frame
      4. 5.4 FSI Transmission Latencies
    7. 6 Summary
    8. 7 References

3.2 DC/AC Inverter Stage

This section shows two examples of DC/AC inverter topologies used in solar string inverter application. As shown in Figure 10, a single phase two-level DC/AC inverter comprises of a full bridge with four switches, followed by an output filter stage. An inductor capacitor (LCL) output filter is shown in the diagram. To regulate the current feeds into the grid, the C2000 MCU senses the voltages and current signals as indicated in the diagram and then runs the control algorithm to compute the PWM duty ratio for the four switches.

single-phase-dcac-topology-used-in-solar-string-inverter-spracr6.gifFigure 10. Single Phase DC/AC Topology Used in Solar String Inverter

For this kind of inverter each switching device blocks the full DC link voltage Vbus. Therefore for higher power output when the DC link voltage is pushed higher it puts an upper limit because of the switching device blocking voltage rating. Additionally higher DC link voltage means increased switching losses in the traditional MOSFET resulting in decreased efficiency. Because of these limitations at higher power two-level inverters are replaced by three-level inverters.

three-phase-3-level-dcac-inverter-control-using-f2838x-mcu-spracr6.gifFigure 11. Three Phase 3-Level DC/AC Inverter Control Using F2838x MCU

One such three-level topology and its interface to C2000 MCU is shown in Figure 11. The controller used in this case is the TMS320F2838x series MCU. This figure shows a T-type three phase three-level inverter. Two back-to-back switching devices are inserted between the switch nodes and the neutral point of the DC link created by the bulk input capacitors. These two switching devices are placed in a common emitter configuration so that current flow can be controlled by controlling (on/off) one of the two switching devices. Here again, F2838x MCU senses the voltage and current signals as indicated in the diagram, runs the current control algorithm and finally computes the PWM duty ratio for all inverter switches.