LC Coil Circuit Switching for High-Rate Magnetic Stimulation
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Solution Overview
Problem
Existing circuits for generating time-varying magnetic fields for magnetic stimulation suffer from significant energy losses due to resistors and diodes, which prolong charging times and reduce the maximum achievable magnetic pulse repetition rate, and are inefficient for multichannel operations.
Innovation Solution
A circuit design that includes a capacitor bank and an electromagnetic coil forming an LC circuit, with a switch to disconnect the circuit from the power supply during reverse polarity, eliminating the need for resistors and minimizing energy losses, and allowing for efficient multichannel operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If resistors and diodes are used in the circuit for generating time-varying magnetic fields, then the circuit can operate with simple topology, but significant energy losses occur and charging times are prolonged
Solution Approach 1:
The patent removes resistors and diodes from the circuit topology, extracting these components that cause energy losses. The circuit uses a switch configured to disconnect during reverse polarity without requiring resistors for current limiting or diodes for polarity protection, thereby eliminating the associated energy dissipation while maintaining functional simplicity.
Solution Approach 2:
The patent implements periodic disconnection of the circuit during reverse polarity phases through a controlled switch. This periodic action allows the circuit to operate efficiently by being disconnected only when necessary (during reverse polarity), minimizing energy losses while maintaining simple topology during active phases.
2Reliability
If resistors are used to limit reverse polarity current, then the power supply is protected, but charging times are prolonged and pulse repetition rate is reduced
Solution Approach 1:
The patent uses a switch that is triggered in advance to disconnect the circuit from the power supply before reverse polarity current can cause damage. This preliminary action protects the power supply without requiring resistors that would slow down charging, thereby maintaining high pulse repetition rates while ensuring reliability.
Solution Approach 2:
The patent allows the circuit to rapidly charge and discharge by skipping the use of resistive current limiting. The switch provides instantaneous protection by disconnecting during reverse polarity, enabling the circuit to rush through charging cycles quickly and achieve high pulse repetition rates while still protecting the power supply.
3Device complexity
If a single capacitor is used in the circuit, then the circuit structure is simple, but the circuit is inefficient for multichannel operations
Solution Approach 1:
The patent replaces a single capacitor with a capacitor bank consisting of multiple capacitors connected in parallel. This segmentation allows each capacitor to be independently managed and enables efficient multichannel operations while maintaining relatively simple circuit structure. The modular capacitor bank can serve multiple channels simultaneously without requiring complex switching arrangements.
Solution Approach 2:
The capacitor bank design provides multi-functionality by enabling both simple single-channel operation and efficient multichannel operation with the same basic structure. The parallel-connected capacitors can be distributed to serve multiple treatment channels, making the circuit universally applicable while maintaining structural simplicity.
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 circuit achieves efficient generation of time-varying magnetic fields with reduced energy dissipation, improved reliability, and the ability to operate at high pulse repetition rates, suitable for large body area treatments and minimizing electromagnetic emissions.
Implementation Method 1
The physical principle of magnetic stimulation is based on a time-varying current flow passing through an electromagnetic coil, resulting in an equally time-varying (e.g., pulsed) magnetic field around the coil.
Implementation Method 2
When a pulse of the magnetic field passes into the body, the pulse will induce a voltage difference between spatially separated points in and/or on the body. This voltage difference yields an electric field and thus induces electrons to flow between the spatially separated points.
Data Source
Figure 1~2
Figure 3~4
Figure 4A~5A
AI summary
The present invention relates to circuits, apparatuses, and methods for magnetic stimulation. In particular, the application relates to a circuit for generating a time-varying magnetic field for magnetic stimulation. The circuit comprises a capacitor bank comprising at least one capacitor, and a first electromagnetic coil, the capacitor bank and the first electromagnetic coil forming a first LC circuit; a power supply for charging the capacitor bank by applying a charging voltage to the capacitor bank; and a switch configured to electrically disconnect the first LC circuit from the power supply when a voltage across the capacitor bank is reverse in polarity to the charging voltage.