Signal Processor for Linear Time-Invariant Inverter Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Designing control systems for interconnection inverter systems requires significant effort to achieve quick response times, particularly in restoring output after a momentary voltage drop, due to nonlinear time-varying processes, making it difficult to apply linear control theory.
Innovation Solution
A signal processor is developed to perform equivalent fixed-to-rotating and rotating-to-fixed coordinate conversions while maintaining linearity and time-invariance, using specific transfer functions to process input signals and generate PWM signals for controlling power converter circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional fixed-to-rotating and rotating-to-fixed coordinate conversions are used, then control accuracy is improved, but system complexity and design difficulty increase due to nonlinear time-varying processes
Solution Approach 1:
The patent transforms the control system parameters by introducing a rotating coordinate system that rotates at the fundamental wave frequency. This parameter transformation converts the nonlinear time-varying control problem into a linear time-invariant problem, enabling the use of standard control theory while maintaining control accuracy. The coordinate transformation matrices are designed to rotate the reference frame at synchronous speed, effectively decoupling the control variables.
2Measurement precision
If conventional coordinate conversion methods are used, then control precision is improved, but response time increases due to complex design requirements
Solution Approach 1:
The patent performs preliminary coordinate transformation to convert the three-phase AC control problem into a two-phase rotating reference frame problem before control processing. By pre-transforming the coordinates into a rotating frame that moves with the fundamental frequency, the system eliminates the need for real-time coordinate updates during control processing, thereby reducing response time while maintaining precision.
3Productivity
If linear control theory is applied, then design efficiency is improved, but control accuracy deteriorates due to nonlinear time-varying nature of the system
Solution Approach 1:
The patent introduces a rotating coordinate system as an intermediary transformation layer between the three-phase AC system and the control algorithm. This intermediary rotating reference frame acts as a mediator that converts the nonlinear time-varying control problem into a linear time-invariant problem, allowing linear control theory to be applied effectively while maintaining control accuracy. The rotating frame serves as a bridge that preserves the essential dynamics while enabling simplified control design.
Data Source
AI summary
A signal processor is configured to perform a process equivalent to performing a series of fixed-to-rotating coordinate conversion, a predetermined process and then rotating-to-fixed coordinate conversion, while maintaining linearity and time-invariance. The signal processor performs a process given by the following matrix G:G=[F(s+jω0)+F(s-jω0)2F(s+jω0)-F(s-jω0)2-F(s+jω0)-F(s-jω0)2jF(s+jω0)+F(s-jω0)2]where F(s) is a transfer function representing the predetermined process, ω0 is a predetermined angular frequency and j is the imaginary unit.