Wireless Power Receiver Rectification With Current-Phase Switching
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Solution Overview
Problem
Existing non-contact power transmission systems suffer from inefficiencies in rectification operations and require excessive cooling due to distorted current waveforms caused by rectification elements turning on only when a predetermined threshold is met, leading to reduced rectification efficiency.
Innovation Solution
A non-contact power transmission system that includes a power reception unit with a coil, a power conversion unit with switching and rectification elements, and a control device that synchronously drives the switching elements based on current phase and threshold detection, allowing for synchronous rectification when the current exceeds a predetermined threshold, and switching to a standby state when it falls below.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rectification elements are not turned on until current reaches a predetermined threshold, then device protection is improved, but current waveform becomes distorted and rectification efficiency deteriorates
Solution Approach 1:
The patent applies dynamics by switching between two rectification modes based on current conditions: synchronous rectification mode for high current (above threshold) and natural rectification mode for low current (below threshold). This dynamic adaptation allows the system to optimize rectification efficiency at high currents while protecting devices at low currents, resolving the contradiction between efficiency and protection.
Solution Approach 2:
The patent changes the operating parameter (rectification mode) based on the current magnitude. When current exceeds the predetermined threshold, synchronous rectification is activated; when it falls below, natural rectification takes over. This parameter-based switching resolves the contradiction by adapting the rectification strategy to the actual operating conditions.
2Loss of energy
If synchronous rectification is continuously executed, then rectification efficiency is improved, but cooling capability requirements increase
Solution Approach 1:
The patent applies partial action by executing synchronous rectification only when necessary (when current exceeds the predetermined threshold) rather than continuously. This selective application reduces the cumulative heat generation while maintaining efficiency when high current flows, thereby resolving the contradiction between rectification loss reduction and cooling requirements.
3Reliability
If rectification elements switch based on current threshold, then device protection is improved, but current waveform distortion increases
Solution Approach 1:
The system dynamically switches between synchronous rectification (which maintains sinusoidal waveform) and natural rectification (which provides device protection) based on current magnitude. This dynamic approach allows the system to maintain good waveform shape during high-current operation while still providing protection during low-current conditions.
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 system reduces losses and cooling requirements by optimizing rectification operations, maintaining efficient power conversion even with moving vehicles, and enabling appropriate operation switching during transitions.
Implementation Method 1
a power reception unit that has a coil for receiving AC power transmitted in a non-contact manner from a power transmission device
Implementation Method 2
a power conversion unit that has a plurality of switching elements and a plurality of rectification elements connected to the coil and converts the AC power received by the power reception unit into DC power
Data Source
AI summary
A non-contact power transmission system includes a power reception unit, a received power conversion unit, a current sensor, and a control device. The power reception unit includes a secondary side coil for receiving AC power transmitted in a non-contact manner from a primary side coil of a power transmission device. The received power conversion unit converts AC power received by the power reception unit into DC power. The current sensor detects a current flowing between the power reception unit and the received power conversion unit. The control device executes a synchronous rectification operation by synchronously driving a plurality of switching elements of the received power conversion unit in accordance with a phase of the current when a detection value of a current output from the current sensor is equal to or larger than a predetermined threshold.