Fast Model Predictive Pulse Pattern Control for Converter Transients
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing control methods for electrical converters, such as MP3C, face challenges in achieving fast transient responses and minimizing flux errors during dynamic conditions due to uneven switching transitions and low switching frequencies, leading to potential over-current trips and harmonic distortion.
Innovation Solution
A method that determines an error value based on the difference between estimated and reference output values, switching to a modified pre-calculated switching sequence or an alternative control scheme like hysteresis-based control when errors exceed a defined band, and inserting additional switching transitions to minimize flux errors quickly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If optimized pulse patterns with low switching frequencies are used, then harmonic current distortions are minimized, but transient response becomes sluggish and settling time increases
Solution Approach 1:
The control system dynamically switches between two operating modes: optimized pulse pattern mode for steady-state operation (minimizing harmonic distortions) and alternative control mode for transient conditions (maximizing response speed). This dynamic adaptation resolves the contradiction by allowing the system to optimize for different objectives at different times.
Solution Approach 2:
The switching frequency parameter is changed based on operating conditions. During transients, the frequency is increased to improve response speed; during steady-state, it is reduced to minimize harmonic distortions. This parameter adaptation allows the system to achieve optimal performance in both regimes.
2Object-generated harmful factors
If switching transitions are unevenly distributed in time, then optimized pulse patterns are achieved, but flux error correction is delayed during transients
Solution Approach 1:
The controller predicts future flux errors and takes preliminary corrective action by switching to alternative control mode before the flux error becomes significant. This anticipatory approach prevents large errors from developing, reducing both harmonic losses and correction time delay.
Solution Approach 2:
The system continuously monitors flux error and uses this feedback to determine when to switch between control modes. Real-time feedback ensures that the system responds appropriately to changing conditions, maintaining low harmonic losses while enabling timely flux error correction.
3Speed
If additional switching transitions are inserted to speed up transient response, then flux error correction improves, but switching losses increase
Solution Approach 1:
Instead of continuously operating at high switching frequency, the system applies partial action by using the alternative control mode only when and where needed (during transients). This selective approach provides sufficient flux error correction speed while avoiding excessive switching losses during steady-state operation.
Data Source
AI summary
A method for controlling an electrical converter comprises the acts of determining an error value based on a difference between an estimated output value and a reference output value, the estimated output value being based on measurements in the electrical converter; comparing the error value with an error band and in the case of the error value exceeds the error band, controlling the electrical converter by switching to a different control scheme. The converter is controlled with the modified pre-calculated switching by determining a pre-calculated switching sequence for the converter based on an actual state of the electrical converter, the switching sequence comprising a sequence of switching transitions of the converter; modifying the pre-calculated switching sequence by modifying transition times of switching transitions of the pre-calculated switching sequence, such that the error value is minimized; and applying at least a part of the modified switching sequence to the electrical converter.