MRI Gradient Power Architecture With Shared DC Bus Isolation
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Solution Overview
Problem
Traditional MRI systems face challenges in providing accurate, high-power currents to gradient coils due to bulky designs, high insulation requirements, and potential for cross-talk and short circuits in power architectures, which affect the precision and reliability of spatial encoding in MRI images.
Innovation Solution
The implementation of a High-Frequency Power Distribution Unit (HFPDU) with a single semiconductor bridge design and shared DC bus architecture, utilizing high-voltage wide band-gap devices, reduces power losses and energy storage needs, and simplifies the amplifier design by eliminating cross-bridge connections, providing galvanic insulation and improved grounding to prevent common-mode voltage stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional power architecture with multiple isolated power supplies and cross-bridge connections is used, then galvanic insulation is provided, but device complexity and insulation requirements increase
Solution Approach 1:
The patent merges multiple isolated power supplies into a single shared DC bus architecture. Instead of having separate power supplies for each gradient coil axis, the invention uses one power supply that serves all axes through a common DC bus, eliminating the need for multiple isolations while maintaining safety through differential signaling and balanced bridge circuits.
Solution Approach 2:
The invention extracts the galvanic insulation function from the power supply architecture itself and relocates it to the control signaling layer. By using differential signals and balanced bridge circuits, the patent achieves electrical isolation through control methods rather than through multiple physical isolation barriers.
2Reliability
If multiple isolated power supplies are used for each gradient coil axis, then galvanic insulation is maintained, but power losses and energy storage needs increase
Solution Approach 1:
The patent combines multiple isolated power supplies into a single shared DC bus, allowing all gradient coil axes to draw power from a common source. This eliminates redundant power conversion stages and reduces overall power losses by sharing the power supply infrastructure across all axes while maintaining electrical isolation through differential control signals.
3Power
If cross-bridge connections are used in amplifier design, then power distribution is achieved, but potential for short circuits and electrical stress increases
Solution Approach 1:
The invention removes cross-bridge connections from the power distribution architecture and replaces them with a shared DC bus combined with differential signaling. This extraction eliminates the short circuit risks associated with cross-bridge connections while maintaining effective power distribution to all gradient coil axes through the common bus.
Solution Approach 2:
The patent introduces differential signaling as an intermediary between the shared DC bus and the gradient coil drivers. This intermediary layer provides electrical isolation and protects against short circuits by using balanced differential pairs that reject common-mode noise and prevent ground loops, while still enabling effective power and control signal transmission.
4Power
If traditional low-frequency transformer architecture is used, then power conversion is achieved, but system footprint and cost increase
Solution Approach 1:
The patent changes the operating frequency parameter of the power conversion system from low-frequency (50/60 Hz) to high-frequency operation. By using high-frequency switching power conversion instead of traditional low-frequency transformers, the system achieves the same power conversion function with much smaller magnetics components, significantly reducing the footprint and cost while maintaining effective power distribution.
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
This solution results in a more compact, efficient, and reliable gradient power architecture that reduces insulation requirements, minimizes electrical stress, and enhances the accuracy of spatial encoding in MRI systems, allowing for flexible packaging and improved imaging fidelity.
Implementation Method 1
a high-frequency transformer, which provides galvanic insulation
Implementation Method 2
The semiconductor bridge may receive the intermediate DC signal of the rectifier and generate a high frequency AC power signal
Implementation Method 3
A shield of the transformer may be coupled to a safety ground
Implementation Method 4
providing galvanic insulation and improved grounding to prevent common-mode voltage stress
Data Source
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AI summary
Power systems and circuitry for generation of gradient magnetic fields in magnetic resonance imaging MRI systems 10 are discussed herein. Embodiments may include the use of multiple gradient amplifiers 106 that share a high-frequency power distribution unit 104, that may perform power distribution and power supply roles. The high-frequency power distribution unit may allow the use of a single power supply to drive multiple gradient amplifiers via a shared power bus 107. The gradient amplifiers may make use of modern semiconductor materials that provide high-frequency, high voltage performance, and maybe implemented using single semiconductor bridges 350.