Contactless Power-Feed Equipment With Parallel Resonant Circuit
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Solution Overview
Problem
Conventional contactless power-feed equipment experiences fluctuations in circuit impedance and requires complex switching operations when powering or cutting off the sub induction line, leading to inefficient power supply and increased costs due to high-rated switches.
Innovation Solution
The implementation of a contactless power-feed system with a main induction line, a sub induction line, a primary coil, a secondary coil forming an insulating transformer, a resonance capacitor, and a switch that resonates at the oscillation frequency of the power-supply device, allowing for simple switching of power supply to the sub induction line without stopping the power-supply device and reducing switch current ratings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the sub induction line is connected to the main induction line to supply power to the sub route, then power can be fed to the carriage on the sub route with a small space and low cost, but the circuit impedance of the power-supply device rapidly changes when power is supplied or cut off, leading to fluctuations in the current of the induction line
Solution Approach 1:
An intermediary circuit comprising a series connection of a capacitor and a switch is introduced between the sub induction line and the main induction line. This intermediary circuit acts as a buffer that isolates the impedance changes of the sub induction line from the power-supply device, allowing the switch to control power supply without causing rapid impedance changes or current fluctuations in the main system.
Solution Approach 2:
The circuit configuration changes the electrical parameters (impedance characteristics) by introducing a capacitor in series with the switch. This parameter change creates a circuit where the switch can open/close the sub induction line connection without directly affecting the main induction line's current, as the capacitor blocks direct current transmission while allowing voltage coupling.
2Reliability
If the power-supply device is stopped and restarted each time power to the sub induction line is supplied or cut off, then the circuit impedance can be stabilized, but the switching operation becomes complicated and productivity decreases
Solution Approach 1:
The intermediary circuit with the capacitor and switch allows the sub induction line to be independently controlled without affecting the main power-supply device operation. The capacitor acts as a buffer that prevents direct coupling between the sub line switching and the main power supply, enabling continuous operation of the power-supply device while allowing frequent switching of the sub line.
3Reliability
If high-rated switches are used to directly control the sub induction line connection, then reliable power supply can be ensured, but the switch cost and device complexity increase
Solution Approach 1:
The capacitor in series with the switch acts as an intermediary that isolates the high-current main induction line from the low-current sub induction line control circuit. This allows the use of a low-rated switch with smaller current capacity to control the sub line, as the capacitor blocks direct current flow through the switch while still allowing voltage coupling for power transmission.
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 configuration maintains stable circuit impedance during power supply and interruption, reducing the load on the power-supply device and minimizing switch costs by allowing power to be supplied or interrupted without stopping the device, while ensuring efficient and safe operation.
Implementation Method 1
a primary coil connected to the main induction line; a secondary coil that forms an insulating transformer with the primary coil and is connected to the sub induction line
Implementation Method 2
a resonance capacitor that is connected to the secondary coil and constitutes a parallel resonant circuit with the sub induction line; wherein circuit constants of an inductance of the sub induction line and of a capacitance of the resonance capacitor are selected such that the parallel resonant circuit has a resonance frequency equal to the oscillation frequency of the power-supply device
Data Source
AI summary
Contactless power-feed equipment includes: a power-supply device that outputs an AC constant current having a predetermined oscillation frequency to a main induction line; a primary coil provided on the main induction line connected to the power-supply device; a secondary coil that forms an insulating transformer with the primary coil and is connected in parallel with the sub induction line, a resonance capacitor that is connected in parallel with the secondary coil and constitutes a parallel resonant circuit with the sub induction line, and a switch provided between the secondary coil and the parallel resonant circuit. In the parallel resonant circuit, the sub induction line and the resonance capacitor have constants such that the parallel resonant circuit has a resonance frequency equal to the oscillation frequency of the power-supply device.