Parallel Gradient Power Amplifier Control for Circulating Current Reduction
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Solution Overview
Problem
Existing magnetic resonance (MR) systems with parallel gradient power amplifiers (GPAs) face challenges in reducing circulating currents, leading to large and expensive systems with limited control bandwidth, necessitating a solution for low-cost, small-volume GPA systems with enhanced dynamic response performance.
Innovation Solution
A GPA system with a controller that determines control parameters for paralleled GPAs based on total and average current parameters, using algorithms like PI, prediction, or pole assignment, and optionally employs a low-inductance coupler for current sharing control, allowing for efficient current management without a high-inductance coupler.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a high-inductance coupler is used to reduce circulating currents, then circulating currents are reduced, but the system volume and cost increase
Solution Approach 1:
The patent extracts the high-inductance coupler from the system and replaces it with a control method that calculates compensation values based on current differences between paralleled GPAs. This eliminates the need for large physical coupling components while still achieving circulating current reduction through digital signal processing and feedback control.
Solution Approach 2:
The patent replaces the mechanical/physical high-inductance coupler with an electronic control system that uses algorithms to calculate and apply compensation values. This substitutes a physical component-based solution with a software/control-based solution, reducing system volume while maintaining effectiveness.
2Object-generated harmful factors
If a high-inductance coupler is used to reduce circulating currents, then circulating currents are reduced, but the system cost increases
Solution Approach 1:
The patent uses low-cost computational resources and standard electronic components to implement the control algorithm, replacing expensive high-inductance couplers. The solution leverages software processing and standard feedback control mechanisms that are more economical than specialized high-inductance components.
Solution Approach 2:
The patent replaces expensive physical coupling components with a control algorithm implemented in software or firmware. This substitution dramatically reduces system cost by eliminating the need for costly high-inductance couplers while achieving the same circulating current reduction through computational methods.
3Object-generated harmful factors
If a large coupler is used, then circulating currents are reduced, but the control bandwidth decreases
Solution Approach 1:
The patent implements a dynamic control system that continuously calculates compensation values based on real-time current differences between paralleled GPAs. This dynamic feedback approach allows for rapid response and high control bandwidth, unlike static large couplers that inherently limit bandwidth due to their physical characteristics.
Solution Approach 2:
The patent replaces the bandwidth-limited large coupler with a digital control algorithm that can respond instantaneously to current variations. This electronic/control-based solution removes the physical bandwidth constraints imposed by large inductance values, enabling much faster control response.
Data Source
AI summary
Gradient power amplifier (GPA) systems and methods are provided. A GPA system may include a plurality of paralleled GPAs; and at least one controller operably coupled to the plurality of paralleled GPAs. The at least one controller may be configured to perform operations including: obtaining a total current parameter of the plurality of paralleled GPAs; determining, based on the total current parameter and a target current parameter, a first difference value; and determining, based on the first difference value, a first control parameter of a first GPA of the plurality of paralleled GPAs, wherein the first control parameter is configured to control an output current of the first GPA.