Wireless Power Receiving Device Overvoltage Protection Circuit
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Solution Overview
Problem
Existing wireless power transmission devices face issues with overvoltage malfunctions and power loss due to reactive power generation caused by parasitic capacitance in semiconductor switching elements, which deteriorate the power factor and increase energy consumption.
Innovation Solution
A wireless power receiving device with a power receiving side resonant circuit, rectifier circuit, voltage detecting portion, short circuit with a switching element, and controlling circuit that detects overvoltage and short-circuits the power receiving coil to prevent overvoltage propagation and inserts rectifying elements to cut off current paths to parasitic capacitance, thereby suppressing reactive power generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a semiconductor switching element is used for overvoltage protection, then circuit elements are protected from overvoltage, but parasitic capacitance generates reactive power causing power factor deterioration
Solution Approach 1:
A diode is introduced as an intermediary component between the power receiving coil and the switching element. This diode acts as a one-way valve for current flow, preventing current from flowing through the parasitic capacitance of the switching element during normal operation, thereby eliminating reactive power generation while maintaining overvoltage protection capability
Solution Approach 2:
The circuit configuration creates different operational states: during normal operation, the diode blocks current flow to the switching element's parasitic capacitance (local quality change), while during overvoltage conditions, the switching element activates to provide protection. This local quality differentiation resolves the contradiction between protection and energy loss
2Object-affected harmful factors
If current flows through parasitic capacitance for short circuit protection, then overvoltage is prevented, but power factor deteriorates due to reactive power generation
Solution Approach 1:
The diode serves as a mediator that controls current direction. During normal operation, it prevents current from reaching the parasitic capacitance, eliminating reactive power. During overvoltage events, the system can still utilize the switching element for protection without the continuous energy loss associated with parasitic capacitance charging and discharging
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 solution effectively protects circuit elements from overvoltage and reduces power loss by preventing reactive power generation during normal operation, improving power factor and efficiency.
Implementation Method 1
a power receiving coil wirelessly receiving power from a power feeding side
Implementation Method 2
a power receiving side resonant circuit provided with a power receiving coil wirelessly receiving power from a power feeding side and a power receiving side resonant capacitor connected to the power receiving coil
Implementation Method 3
a rectifier circuit in which the power received by the power receiving coil is rectified to be output to the load
Data Source
AI summary
A wireless power receiving device, for wirelessly receiving electric power from a wireless power feeding device, includes: a power receiving side resonant circuit having a power receiving coil wirelessly receiving power from a power feeding side and a power receiving side resonant capacitor; a rectifier circuit in which the power received by the power receiving coil is rectified to be output to a load; a power receiving side voltage detecting portion for detecting the output voltage of the rectifier circuit; a short circuit having a switching element connected between an output portion of the power receiving side resonant circuit and an output portion of the rectifier circuit, and a rectifying element inserted between the output portion of the power receiving side resonant circuit and the switching element; and a controlling circuit which operates the switching element when a value of the output voltage exceeds a preset reference voltage value.