Reactive Pulse Circuit Control for Accurate Electromagnetic Profiles
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Solution Overview
Problem
Existing pulse systems struggle to accurately generate electromagnetic pulses due to the complexity of reactive circuits, particularly in achieving target profiles for current through pulse coils, and face challenges in operational characteristics like switch rate and capacitive discharge element voltage balancing.
Innovation Solution
A method using a discrete-time model and model predictive control (MPC) algorithm is employed to derive an optimised control sequence offline, which minimizes deviations from target profiles by considering cost functions that penalize undesirable operational characteristics and switching states, ensuring accurate and reliable pulse generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a control sequence is derived in real-time using model predictive control, then the electromagnetic pulse can follow the target profile accurately, but the computational complexity becomes prohibitive and cannot be performed within available computational resources
Solution Approach 1:
The control sequence is pre-calculated offline using model predictive control before the actual pulse generation. The offline computation stores the optimal control sequence in memory, eliminating the need for complex real-time calculations during pulse generation while maintaining high accuracy in following the target profile
2Speed
If the switching circuit operates at high switching rates to respond quickly to control signals, then the electromagnetic pulse can be generated rapidly, but the switches and capacitive discharge elements suffer increased stress and reduced reliability
Solution Approach 1:
The control sequence uses periodic switching patterns with strategically timed intervals between switching events. By distributing switching actions across multiple time steps and incorporating rest periods, the scheme reduces the cumulative stress on switches and capacitive discharge elements while maintaining the ability to generate electromagnetic pulses at the required speed
Solution Approach 2:
The model predictive control incorporates feedback about the current state of the reactive circuit and switching elements. This feedback allows the control algorithm to adjust switching rates dynamically, reducing switching frequency when components are under stress and maintaining higher rates when components can handle the load, thereby optimizing both speed and reliability
3Manufacturing precision
If the control sequence aggressively adjusts switching states to minimize deviation from target profile, then the electromagnetic pulse accuracy improves, but the operational characteristics of the switching circuit deteriorate due to excessive switching activity
Solution Approach 1:
The control sequence applies partial switching adjustments at each time step rather than maximizing switching activity. By using just enough switching action to keep the electromagnetic pulse on track toward the target profile without over-correcting, the scheme maintains good accuracy while avoiding excessive switching that would degrade operational characteristics
Solution Approach 2:
The offline optimization adjusts multiple parameters including switching timing, duration, and sequence to find the optimal balance between pulse accuracy and switching circuit operation. By varying these parameters systematically during offline computation, the control sequence achieves both good target profile following and healthy switching circuit operation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method allows for precise electromagnetic pulse generation that closely follows target profiles while preventing component damage and reducing computational complexity, making it suitable for applications like transcranial magnetic stimulation and particle accelerators.
Implementation Method 1
a pulse coil for generating electromagnetic pulses
Data Source
AI summary
Offline prior to operation, an optimised control sequence is derived for a pulse system comprising a reactive circuit for generating electromagnetic pulses, such as a transcranial magnetic stimulation circuit, and cascaded switching modules for switchably connecting capacitive discharge elements to provide a multi-level output voltage for the reactive circuit. A discrete-time model predicts an electrical state of the pulse system. A target profile for an electromagnetic pulse is received. For respective time-steps of the control sequence taken in succession, an optimal path of switching states over a window of time-steps starting with the respective time-step is derived, optimising a cost function having a deviation cost contribution representing deviation of an electrical state of the pulse system predicted by the discrete-time model from the target profile over the window. The switching state of the determined path at the respective time-step is selected for the control sequence.