Voltage Source Driver for Parallel Resonant Magnetic Field Generator
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Solution Overview
Problem
Existing magnetic field generators face challenges in efficiently producing high-frequency magnetic fields with low inductance coils, as series resonant configurations result in high voltages and complexity, while parallel resonant configurations lead to power loss and voltage spikes due to the use of conventional inductive components.
Innovation Solution
A magnetic field generator using a drive circuit with MOSFET gate drivers, a capacitor array, and a tank circuit, including a sense coil and coil integrator, to manage current spikes and operate at reduced switching speeds, allowing for efficient high-frequency field generation in low inductance coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If series resonant configuration is used, then voltage source can be simple, but high voltage is generated causing insulation problems and corona discharge
Solution Approach 1:
The patent introduces a current source as an intermediary between the power supply and the series resonant circuit. This current source (implemented with MOSFETs Q1-Q4 and current sense resistors) acts as a mediator that provides controlled current to the circuit, preventing the uncontrolled high voltage generation while maintaining the series resonant configuration's simplicity. The current source limits and regulates the current flow, thereby controlling the voltage across the coil without requiring complex insulation or voltage management circuits.
2Speed
If parallel resonant configuration is used, then high frequency operation with low inductance coil is achieved, but conventional inductive components cause power loss and voltage spikes
Solution Approach 1:
The patent replaces conventional inductive components (matching inductors or high-frequency transformers) with an active electronic circuit based on MOSFETs and current sensing. Instead of using passive inductive elements that cause power loss and voltage spikes, the invention uses an active current source implementation that electronically controls the current flow through the coil. This substitution eliminates the need for lossy inductive components while maintaining the parallel resonant configuration's ability to operate at high frequencies with low inductance coils.
3Speed
If parallel resonant configuration is used, then high frequency operation is practicable, but de-tuning results in damaging voltage spikes
Solution Approach 1:
The patent implements a feedback mechanism using current sense resistors (R1, R2) and MOSFETs (Q1-Q4) that continuously monitor and control the current flowing through the coil. This feedback system detects changes in circuit conditions and adjusts the current accordingly, preventing damaging voltage spikes even when the circuit becomes de-tuned from resonance. The feedback control ensures reliable operation at high frequencies by actively managing the electrical parameters rather than relying solely on passive resonant tuning.
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 solution enables efficient generation of high magnetic fields at high frequencies with reduced power loss and voltage spikes, improving scalability and safety by using MOSFET gate drivers and Litz wire coils, which minimize resistive losses and maintain a high Q-factor.
Implementation Method 1
the resonant principle, in which energy passes back and forth at the characteristic resonant frequency between the magnetic field associated with current in a coil and the electric field associated with voltage across a capacitor
Implementation Method 2
a drive capacitor having a first terminal and a second terminal... the first terminal of the drive capacitor is in electrical communication with the output terminal of the MOSFET gate driver such that the output of the MOSFET gate driver drives the drive capacitor
Implementation Method 3
using MOSFET gate drivers and Litz wire coils, which minimize resistive losses and maintain a high Q-factor
Data Source
Figure 1~2B
Figure 3
Figure 4~5
AI summary
A magnetic field generator. In one embodiment, the magnetic field generator includes a drive circuit including a MOSFET gate driver having an output terminal; a drive capacitor having a first and second terminal, a tank circuit including a tank circuit capacitor having a first and second terminal and a field-producing coil having a first and second terminal, wherein the first terminal of the tank circuit capacitor and the first terminal of the field-producing coil comprise the first terminal of the tank circuit, wherein the second terminal of the tank circuit capacitor and the second terminal of the field-producing coil comprise the second terminal of the tank circuit, wherein the first terminal of the drive capacitor is in electrical communication with the output terminal of the MOSFET gate driver, and wherein the second terminal of the drive capacitor is in electrical communication with the first terminal of the tank circuit.