SLUAAX2 July   2024 TMS320F280039 , TMS320F28P550SJ , TMS320F28P650DK

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Three-Phase-Shift (TPS) With Varying Frequency
  6. 3Solution in PLECS
  7. 4Conclusion
  8. 5References

3 Solution in PLECS

In the demo model of PLECS, there is an SPS-controlled DAB model which has a single-shift module, as shown in Figure 3-1, based on which a multi-phase-shift module can be built.

As shown in Figure 3-2, the module is modified with S1 as the base driver and S3 as the phase-shifted Sita1 on the basis of S1. According to this method, you can obtain the driving signal at different angles of phase-shift on the basis of S1 so that the drive of the multi-phase-shift is no longer a problem, but now the only problem is figuring out how to realize varying frequency while changing the phase-shift angle.

TMS320F28P650DK TMS320F28P550SJ TMS320F28P650DK PMP41042 Single-Phase-Shift Function Module in Demo Model Figure 3-1 Single-Phase-Shift Function Module in Demo Model
TMS320F28P650DK TMS320F28P550SJ TMS320F28P650DK PMP41042 Modified Single-Phase-Shift Function Module Figure 3-2 Modified Single-Phase-Shift Function Module

As seen from Figure 3-1, there are two carriers (On carrier and Off carrier) used as reference signals, so by changing the frequency of the carriers in real time, you can achieve varying frequency and phase-shift at the same time.

The carriers provided in this demo cannot achieve real-time frequency changes, so you need to find a new way to implement the frequency conversion carriers. Note that the two carriers also have a phase-shift of 1/2 period to make sure the generated duty cycle is 50%, which also increases the difficulty of building the module.

This paper now proposes a way to generate two carriers with varying frequency, while at the same time, the two carriers have a phase-shift of 1/2 period. Simulations built this way are faster than simulations with delays.

As shown in Figure 3-3, the integration (1/s) is used to generate a sawtooth wave, and the external initial condition of the integration is used to generate another sawtooth wave with a 1/2-period phase-shift. The figure also shows the settings for external initial condition and how to connect blocks.

TMS320F28P650DK TMS320F28P550SJ TMS320F28P650DK PMP41042 Schematic Diagram of the Implementation of a Variable Frequency Sawtooth Wave Figure 3-3 Schematic Diagram of the Implementation of a Variable Frequency Sawtooth Wave

Figure 3-4 shows the switching frequency varies from 300kHz to 100kHz for the clk and clk2 waveforms with no problems.

TMS320F28P650DK TMS320F28P550SJ TMS320F28P650DK PMP41042 Detailed Waveforms When Changing Switching Frequency Figure 3-4 Detailed Waveforms When Changing Switching Frequency