Gradient Coil Power Control via Voltage Gradient Monitoring
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Solution Overview
Problem
Conventional gradient magnetic field power supplies in MRI apparatuses face complexity due to handling numerous analog signals, leading to inefficient current assignment and voltage drops, especially when prioritizing channels for high output, resulting in excessive voltage drops in active channels.
Innovation Solution
The implementation of a software-controlled power control circuitry that monitors voltage gradients and adjusts current ratios dynamically among channels, using a look-up table and feedback control to prioritize channels based on voltage changes, ensuring stable power supply to gradient coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hardware control is used for current assignment in conventional gradient magnetic field power supply, then the system can operate with simple control logic, but the configuration becomes complicated due to handling a large number of analog signals
Solution Approach 1:
The patent replaces hardware-based analog signal control with software-based digital control. The power control circuitry uses software to monitor output voltages and dynamically assign current ratios among channels, eliminating the need for complex hardware analog signal handling while maintaining control functionality
Solution Approach 2:
The system dynamically changes the current ratio parameter assigned to each channel based on real-time voltage monitoring. By adjusting the current ratio software-controlled, the system adapts to varying load conditions without requiring complex hardware reconfiguration
2Device complexity
If current assignment is based only on output voltage drop monitoring, then the control method is simple, but the voltage drop of active channels increases to extreme levels
Solution Approach 1:
The power control circuitry implements feedback control by monitoring the output voltage of each channel and using this information to dynamically adjust current assignment. The system calculates voltage gradients and uses this feedback to prevent excessive voltage drops by redistributing current to channels with smaller voltage drops
Solution Approach 2:
The system transitions from static current assignment to dynamic current ratio adjustment. The current ratios are continuously modified based on real-time voltage monitoring, allowing the system to adapt to changing load conditions and maintain voltage stability within acceptable ranges
3Power
If charging current is supplied to non-active channels to enable large output on one channel, then the output capability is improved, but the voltage drop on the active channel increases significantly
Solution Approach 1:
The system performs preliminary monitoring of voltage gradients in all channels before making current assignment decisions. By anticipating voltage drop trends through gradient calculation, the system can prevent excessive voltage drops before they occur, rather than reacting after the problem arises
Data Source
AI summary
According to one embodiment, a magnetic resonance imaging apparatus includes amplifiers, processing circuitry, and a power supplier. The amplifiers supplies power for each of a plurality of channels of gradient coils. The processing circuitry obtains, for each of the channels, a voltage gradient that represents a temporal change of a power supply voltage for supplying a current to the amplifiers. The power supplier supplies the power to an amplifier corresponding to a specific one of the channels on a priority basis in accordance with the voltage gradient.