Mid-Voltage Rectifier Harmonic Distortion Compensation
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Solution Overview
Problem
Conventional three-phase switch-mode rectifier modules experience dead zones, leading to distortion in the rectifier AC-side phase voltage and increased total harmonic distortion, particularly in mid-high voltage or high-power conditions, due to the phase angle difference between the grid-side phase current and phase voltage, which affects the harmonic of the grid-side phase current.
Innovation Solution
A total harmonic distortion compensation control method is introduced, which includes harmonic detection, adjustment of reactive component reference values, and optimization of phase angle differences to minimize the dead zone and reduce low-order harmonics, thereby improving the power factor and reducing harmonic distortion in the three-phase switch-mode rectifier module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional three-phase switch-mode rectifier module is used, then the structure is simple and cost is low, but dead zones cause distortion and increased total harmonic distortion
Solution Approach 1:
The patent changes the control parameters by introducing a phase angle difference between the grid-side phase current and phase voltage. This parameter adjustment allows the system to operate outside the dead zone region, thereby reducing harmonic distortion while maintaining the simple rectifier structure
Solution Approach 2:
The patent applies preliminary action by pre-adjusting the phase angle of the current relative to the voltage before the dead zone issue occurs. This proactive phase shifting prevents the distortion from happening in the first place, rather than correcting it after the fact
2Object-generated harmful factors
If the phase angle difference between grid-side phase current and phase voltage is reduced, then dead zone is minimized, but reactive component reference value adjustment becomes necessary
Solution Approach 1:
The patent implements feedback control by continuously monitoring the phase angle difference between current and voltage, and automatically adjusting the reactive component reference value to maintain optimal phase alignment. This closed-loop feedback mechanism minimizes dead zone distortion while managing control complexity through automated adjustment
Data Source
AI summary
A mid-voltage variable-frequency driving system and a total harmonic distortion compensation control method are provided in this invention. The mid-voltage variable-frequency driving system includes a total harmonic distortion compensation unit. The total harmonic distortion compensation unit is used to perform an optimal adjustment on a reactive component reference value of a grid-side phase current, such that a harmonic component of the grid-side phase current may be reduced and a power factor of a three-phase switch-mode rectifier module within the mid-voltage variable-frequency driving system may be maintained.