Fixed-Frequency Generalized Peak Current Control (GPCC) for Inverters

 ABSTRACT

A fast and robust fixed switching frequency peak current controller for dc-ac converters is presented. The method is specifically elaborated for single-phase grid-connected distributed generation (DG) applications. This method is called generalized peak current control (GPCC) as it can mimic any known pulse width modulation (PWM) strategy. It is shown that additional control objectives can be achieved by adaptive bands of the GPCC, which are proposed to provide active damping for inverters with LCL output filters. The proposed approach features all the advantages of peak current controllers such as simplicity, fast transient, and optimum dynamic response; with the superiority of fixed switching frequency and harmonic free output. Feasibility and performance of the controller is shown by simulations and experimental results.

 KEYWORDS:

  1. Current Control
  2. DC-AC Converters
  3. Generalized Peak Current Control (GPCC)
  4. Switching Scheme
  5. Single-Phase Grid-Connected Inverter

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of the proposed controller along with the cost effective active resonant damping technique.

 

EXPECTED SIMULATION RESULTS:

Fig. 2. (a) Grid current for the LCL filter case when the active damping branch is disabled, (b) Current of inverter and grid with the proposed active damping.

Fig. 3. Dynamic performance evaluation of proposed GPCC. Peak current reference jumps from 1A to 3A at t = 0:1s.

CONCLUSION

A fixed switching frequency Generalized Peak Current Control (GPCC) method for inverters is proposed . While controlling the peak value of the inverters’ current, the proposed approach can mimic any known PWM strategy. As a result, the GPCC features all the advantages of peak current controllers, along with a fixed switching frequency and the clean output harmonic spectrum inheriting from the original PWM scheme. It is shown that the proposed technique is able to obtain additional control objectives by its adaptive bands. As an example, the GPCC is applied to a unipolar PWM scheme and the controller is elaborated for both Land LCL-type output filters. Demonstrating the advantages of resulting controller, a simple active damping strategy based on adaptive bands of the controller is proposed. Simulations and experimental results are presented to validate the method. 

REFERENCES

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