Coreless Gate Driver Transformer With Resonant Load-Independent Output
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Solution Overview
Problem
Existing gate drivers for MRI systems face challenges in minimizing transformer parasitic capacitance and size while maintaining sufficient insulation and magnetic coupling, especially with the increasing use of wide bandgap power semiconductors that generate higher dv/dt.
Innovation Solution
The implementation of a coreless transformer with a single turn primary winding and a secondary winding wound about a toroid-shaped, non-magnetic body, along with a resonance converter to compensate for leakage inductance, enables the gate driver power supply to generate an output voltage independent of load and reduce capacitance coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ferromagnetic cores are eliminated to avoid saturation in high magnetic fields, then compatibility with high magnetic fields is improved, but coupling is reduced and transformer size increases
Solution Approach 1:
The patent changes the operating parameters by using high-frequency switching (enabled by wide bandgap semiconductors) to achieve the required power transfer without ferromagnetic cores. This frequency parameter change allows the air-core transformer to maintain compact size while avoiding magnetic saturation issues
Solution Approach 2:
The patent uses magnetic coupling through air (electromagnetic field copying) instead of direct ferromagnetic core coupling. The primary and secondary windings are coupled through electromagnetic induction in air, eliminating the need for ferromagnetic material while maintaining functional coupling
2Loss of energy
If wide bandgap power semiconductors are used to increase power density, then power efficiency is improved, but dv/dt increases and transformer parasitic capacitance becomes more problematic
Solution Approach 1:
The patent extracts and eliminates the ferromagnetic core from the transformer structure, removing the source of magnetic saturation and associated parasitic effects. This leaves only the essential electromagnetic coupling through air, which has lower parasitic capacitance and is unaffected by magnetic saturation
Solution Approach 2:
The patent accepts the transient high dv/dt effects as temporary tolerable conditions during switching, using the air-core transformer's low parasitic capacitance to minimize the duration and impact of these transients. The design tolerates brief high-stress periods in exchange for overall system efficiency
3Object-generated harmful factors
If transformer parasitic capacitance is minimized to reduce common mode noise, then electromagnetic interference is reduced, but insulation requirements become more stringent
Solution Approach 1:
The patent introduces air as an intermediary medium between primary and secondary windings, replacing ferromagnetic core material. This air gap acts as a natural insulator with extremely low parasitic capacitance, providing both electrical isolation and magnetic coupling without the conflicting properties of ferromagnetic materials
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 provides high power efficiency, load insensitivity, and a compact size for the gate driver, while maintaining compatibility with high magnetic fields and wide bandgap semiconductor technologies.
Implementation Method 1
a coreless transformer including a primary winding and a secondary winding
Implementation Method 2
a resonance converter coupled to the coreless transformer, wherein the resonance converter is configured to compensate for leakage inductance
Data Source
AI summary
A gate driver circuit includes an isolated gate driver power supply circuit. The isolated gate driver power supply circuit includes a coreless transformer including a primary winding and a secondary winding. The secondary winding is wound about a toroid-shaped, non-magnetic body and the primary winding is a single turn primary winding to reduce capacitance coupling between the primary winding and the secondary winding. The isolated gate driver power supply circuit also includes a resonance converter coupled to the coreless transformer, wherein the resonance converter is configured to enable the isolated gate driver power supply circuit to generate an output voltage independent of load.