Contactless Power Receiver Frequency Control for Battery Protection
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Solution Overview
Problem
Existing power receiving devices in contactless power transmission systems experience unintended power increases due to short circuits formed by switching elements, leading to battery degradation and breakage, despite safety margins that reduce received power.
Innovation Solution
A power receiving device with a control device that executes a short-circuit mode by setting a switching frequency of the rectifier circuit to a value different from the drive frequency of the inverter, using a control unit to manage the short-circuit mode and suppress power increases by alternating phase shifts and power decreases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a short circuit is formed by switching elements in the rectifier circuit to stop charging, then voltage rise is prevented, but power increases unintentionally causing battery degradation
Solution Approach 1:
The patent applies dynamics by making the switching frequency variable rather than fixed. The control device dynamically adjusts the switching frequency of the rectifier circuit based on the drive frequency of the inverter, specifically setting it to a value different from the drive frequency. This dynamic adjustment prevents the resonance condition that causes unintended power increases while maintaining the voltage control function.
Solution Approach 2:
The patent changes the parameter of switching frequency to resolve the contradiction. By setting the switching frequency to a value different from the drive frequency of the inverter, the patent alters the operational parameters of the rectifier circuit to avoid resonant power increases while maintaining effective voltage control during short-circuit operation.
2Reliability
If safety margins are applied to reduce received power, then battery protection is improved, but charging efficiency decreases
Solution Approach 1:
The patent implements feedback by having the control device acquire information about the drive frequency of the inverter and use this information to adjust the switching frequency of the rectifier circuit. This feedback mechanism allows the system to optimize power transfer efficiency while maintaining battery protection, eliminating the need for conservative safety margins.
Solution Approach 2:
By changing the switching frequency parameter based on real-time feedback from the inverter's drive frequency, the system achieves optimal power transfer efficiency without requiring reduced power margins, thus maintaining both battery protection and charging efficiency.
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 effectively prevents unintended power increases during contactless charging, protecting the battery by cyclically reducing power variations through phase shift management, thus ensuring stable power delivery.
Implementation Method 1
a power receiving coil receiving power transmitted in a contactless manner from a power transmission coil of a power transmission device
Data Source
AI summary
A power receiving device includes: a power receiving coil receiving power transmitted from a power transmission coil; a rectifier circuit between the power receiving coil and a load; a smoothing capacitor between the rectifier circuit and the load; and a control device executing a short-circuit mode of short-circuiting between output ends of the power receiving coil. Further, the control device includes an acquisition unit acquiring information indicating a drive frequency of an inverter in the power transmission device, a setting unit setting a switching frequency of the rectifier circuit to a value different from the drive frequency of the inverter, and a control unit executing the short-circuit mode based on the switching frequency set by the setting unit.