Aliasing Suppression With Negligible Phase Lag for Multi-Sampled LCL-Type Grid-Tied Inverter

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Abstract
Multisampling is a very effective and direct way to reduce control delay, which can greatly improve the bandwidth and stability margin. However, it will introduce high-frequency switching harmonics (SHs), resulting in low-frequency aliasing in regular sampling PWM. The harmonic suppression of existing filters inevitably brings phase lag, which weakens the advantage of multisampling to reduce delay. To address the challenge of phase lag under multi-sampled aliasing suppression, this paper proposes an antialiasing method with negligible phase lag for LCL-type grid-tied inverter. The analytical expression for the inverter-side current is derived, and the SHs symmetry and phase sequence characteristics are analyzed in detail. According to these characteristics, these SHs is converted into the harmonic components of integral multiple switching frequency after Park transformation. Moving average filter with phase-lead compensation is designed in dq frame to eliminate these harmonics. Theoretical analysis shows that the proposed method hardly introduces phase lag within the effective control frequency band. Finally, the experiment of a single-loop inverter-side current control verifies that the proposed method can effectively filter out the SHs with negligible phase lag, thus improving the dynamic response performance and control stability.
Funding Information
  • National Natural Science Foundation of China (52077197, 52177062)
  • Scientific Research Fund of Zhejiang Provincial Education Department (Y202250854)

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