Principle and design of PFC-level circuit based on TMS320LF2407A DSP - Power Circuit - Circuit Diagram

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Low-cost, high-performance digital signal processor (DSP) with integrated peripherals such as A/D converters (ADCs) and pulse width modulators (PWMs), in areas such as motor control, uninterruptible power supplies (UPS) and motion control Get a wider range of applications. Low-cost DSPs provide new tools for power supply designers in controlling power conversion functions.

Compared to traditional analog control, DSP controllers have many outstanding advantages, such as multi-platform standard hardware design, low sensitivity to aging and environmental changes, excellent noise immunity, ease of implementation of advanced control algorithms, and flexibility in design changes. And single-chip solutions for control and communication functions. However, the use of DSP in power supply design faces new challenges for many analog designers who must try to change the design to accommodate the new digital environment.

This article takes the average current-type power factor correction (PFC) boost converter controlled by Texas Instruments TMS320LF2407A 16-bit fixed-point DSP as an example to illustrate the difference from the traditional analog design. Different control loop parameters in the field of analog control must be redefined to their digital fulfillment, then loop analysis is performed, and the required voltage and current loop compensators are given. Finally, the discreteness of these compensators and their introduction are introduced. Execution in software. Taking the PFC-level digital controller design as an example, the basic difference between analog and digital control can be identified.

2. PFC stage circuit controlled by TMS320LF2407A

Figure 1 shows the PFC stage circuit controlled by the TMS320LF2407A. The topology is an AC-DC boost converter that requires three signals, namely the rectified input voltage Vin, the inductor current Iin, and the DC bus (output capacitor Co) voltage V, in order to fulfill the control algorithm (algorithm).

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