Wireless Power Receiver Dummy Load for Detection
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Solution Overview
Problem
Conventional wireless charging systems face difficulties in accurately detecting a load variation due to impedance differences between a wireless power transmitter and receiver, leading to issues such as faulty detection, overcurrent, and excessive standby power consumption.
Innovation Solution
A wireless power receiver (PRU) is designed to generate a load by converting received signals into a DC signal and applying a constant voltage or controlling current through a dummy load using pulse width modulation (PWM) switching, enabling effective load detection by a wireless power transmitter (PTU).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a small threshold for impedance variation is used for load detection, then detection sensitivity is improved, but faulty detection occurs
Solution Approach 1:
The system performs preliminary actions by generating a dummy load before actual load detection occurs. This dummy load creates a predetermined impedance variation that enables the PTU to detect the PRU's presence and characteristics accurately, preventing both faulty detection and detection failure by establishing a reliable baseline for comparison
Solution Approach 2:
A dummy load is introduced as an intermediary element between the PTU and the actual PRU load. This intermediary generates a controlled impedance variation that facilitates accurate detection without the uncertainties of direct load sensing, acting as a mediator that translates load presence into detectable electrical characteristics
2Reliability
If a large threshold for impedance variation is used for load detection, then detection reliability is improved, but detection failure occurs for small objects
Solution Approach 1:
The dummy load is activated in advance to establish a known impedance baseline. This preliminary action ensures that even small impedance variations caused by small PRUs can be detected above the threshold, maintaining both reliability and sensitivity simultaneously by providing a reference point for comparison
3Device complexity
If impedance difference between PTU without PRU and PTU with PRU is not substantial, then system simplicity is maintained, but load detection fails
Solution Approach 1:
The dummy load serves as an intermediary that amplifies or creates a substantial impedance difference between the PTU with and without a connected PRU. This intermediary element ensures detectable impedance variation without requiring complex system modifications, maintaining simplicity while enabling reliable detection
Solution Approach 2:
The system changes the electrical parameters by introducing a dummy load that modifies the impedance characteristics of the PTU. This parameter change creates a substantial impedance difference that is easily detectable, transforming an undetectable state into a detectable one without altering the fundamental system architecture
4Measurement precision
If more load-pull power is consumed in the amplification unit of PTU, then detection capability is improved, but overcurrent or overvoltage occurs
Solution Approach 1:
The dummy load is activated before full power transmission begins, allowing the PTU to detect the PRU's presence and characteristics under controlled conditions. This preliminary detection enables the system to adjust power levels appropriately, improving detection capability while preventing overcurrent or overvoltage conditions during full-power operation
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 approach enhances the accuracy of load detection, prevents overcurrent issues, and optimizes power consumption by ensuring a stable impedance variation, thereby improving the efficiency of wireless charging.
Implementation Method 1
wireless power transmission/reception... inductive charging (or magnetic induction) transfers electric power between a primary coil and a second coil. Movement of a magnet near a coil induces an electric current that creates a magnetic field on a side of a sender, and a variation in the magnetic field enables an electric current to be induced on a side of a receiver.
Implementation Method 2
Resonant charging transfers electricity within a range of a few meters between a charger and a target. Basically, resonated electromagnetic waves carry electrical energy instead of sound. Resonated electric energy directly transfers only when there is an object having the resonant frequency
Data Source
AI summary
A wireless power receiver (PRU) and a method for generating a load of the PRU for detecting the PRU in a wireless charging system are provided. The method includes receiving a wireless power signal from a wireless power transmitter (PTU), rectifying the received wireless power signal into a direct current (DC) signal, and generating a load for detecting the PRU by controlling a current flowing across a resistor connected in parallel with a load charged with power of the DC signal.