Contactless Power Reception Circuit With Resonance Mode Switching
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Solution Overview
Problem
The challenge in contactless electric power transmission systems is maintaining effective power transfer when a movable body, such as a vehicle, changes distance between the power transmission and reception sides due to movement.
Innovation Solution
A contactless electric power transmission system that includes a switching circuit between a resonance capacitor and a coil, controlled by a control portion to switch between resonance and short modes based on predetermined conditions, adjusting the short mode ratio according to the electric power reception device's target power, storage state, and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If contactless electric power transmission is performed using magnetic field coupling, then electric power can be supplied to a movable body without physical contact, but the transmission efficiency becomes unstable when the distance between transmission and reception sides changes due to movement
Solution Approach 1:
The patent applies dynamics by making the resonance capacitor connectable and disconnectable from the coil through a switching circuit. This dynamic configuration allows the system to adapt to changing distances between transmission and reception sides, maintaining stable resonant oscillation and improving transmission efficiency stability during movement while preserving contactless power supply capability.
2Reliability
If the resonance capacitor is always connected to the coil, then resonant oscillation can be maintained, but energy is wasted when high transmission efficiency is not required
Solution Approach 1:
The patent applies periodic action by controlling the switching circuit to connect the resonance capacitor to the coil only during periods when electric power transmission is required. The control portion determines based on reception electric power that the coil should be in resonant oscillation, and only during these periods is the capacitor connected. This periodic connection maintains resonant oscillation when needed while avoiding energy waste during idle periods.
3Reliability
If the switching circuit switches between resonance and short modes frequently, then appropriate power transmission can be maintained during movement, but system complexity increases
Solution Approach 1:
The patent applies feedback by having the control portion determine whether to connect the resonance capacitor based on reception electric power information. This feedback mechanism allows the system to automatically adjust the switching state according to actual transmission needs, maintaining appropriate power transmission during movement while using a relatively simple control logic that monitors reception power levels.
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
Enables appropriate electric power transmission even when the movable body is moving, ensuring efficient and controlled power transfer.
Implementation Method 1
an electric power reception portion that receives electric power by a change of a magnetic field transmitted from the electric power supply device by magnetic field coupling
Implementation Method 2
a resonance capacitor and a coil connected in series... a resonance mode in which electric power is supplied to the resonance capacitor
Data Source
AI summary
A contactless electric power transmission system of an embodiment is a contactless electric power transmission system that supplies electric power in a contactless manner from an electric power supply device provided on a movement path of a movable body to an electric power reception device provided on the movable body, wherein the electric power reception device includes: an electric power reception portion that receives electric power by a change of a magnetic field transmitted from the electric power supply device by magnetic field coupling; and a control portion that controls the electric power reception portion, the electric power reception portion includes: a switching circuit that is connected between a resonance capacitor and a coil connected in series and switches between a resonance mode in which electric power is supplied to the resonance capacitor and a short mode in which electric power is not supplied to the resonance capacitor, and the control portion controls the switching circuit so that the mode is switched in accordance with a predetermined condition.