Multi-Level Rectifier Harmonic Reduction Wireless Power
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current wireless power transfer systems face inefficiencies due to the generation of harmonics in rectified voltage waveforms, which complicates electromagnetic interference compliance and requires bulky filtering components, especially in high-frequency applications like wireless charging.
Innovation Solution
A multi-level rectifier circuit with a synchronous rectifier and a multi-level rectifier control circuit that adjusts switching configurations and timing based on harmonic characteristics, eliminating or reducing low-order harmonics by maintaining a multi-level voltage waveform, thereby simplifying harmonic cancellation and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional rectification circuits are used in high-frequency wireless power transfer systems, then the system can operate at high frequencies, but harmonics are generated in the rectified voltage waveform requiring bulky filtering components
Solution Approach 1:
The patent changes the voltage waveform parameters by implementing a multi-level rectification scheme that produces a rectified voltage waveform with multiple discrete voltage levels instead of a conventional two-level waveform. This parameter change in the voltage waveform structure inherently reduces harmonic content, eliminating the need for bulky filtering components while maintaining high-frequency operation capability
2Device complexity
If conventional rectification circuits are used, then the circuit structure remains simple, but harmonics complicate electromagnetic interference compliance
Solution Approach 1:
The invention changes the voltage waveform parameters through multi-level rectification, producing a rectified voltage waveform with multiple discrete voltage levels. This parameter change inherently reduces harmonic content in the waveform, thereby reducing electromagnetic interference and simplifying compliance with electromagnetic interference standards while maintaining relatively simple circuit structure
3Object-affected harmful factors
If multi-level rectifier control circuit is implemented to reduce harmonics, then electromagnetic interference compliance is simplified, but the control circuit complexity increases
Solution Approach 1:
The patent implements a control circuit that receives feedback regarding the voltage waveform and adjusts the switching of rectification circuit components accordingly. This feedback mechanism enables the control circuit to maintain optimal switching patterns that produce multi-level voltage waveforms with reduced harmonics, achieving electromagnetic interference compliance while managing control circuit complexity through intelligent feedback-based control
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 reduces harmonics, enhancing the efficiency of wireless power transfer and simplifying electromagnetic interference compliance, particularly in high-frequency applications like the 6.78 MHz ISM frequency band, by using a multi-level rectifier circuit that adjusts switching configurations and timing to minimize harmonic generation.
Implementation Method 1
rectifying, via a synchronous rectifier circuit comprising a plurality of switches, the periodic input voltage waveform to produce the output voltage
Implementation Method 2
adjusting the timing of switching between the plurality of different states based on one or more characteristics, the one or more characteristics being of electrical current of the periodic input voltage waveform, or voltage levels of the periodic input voltage waveform, or a combination thereof. The one or more characteristics may correspond to levels of one or more harmonics within the periodic input voltage waveform
Data Source
AI summary
A multi-level rectifier is presented that is suitable for use at high frequencies, including into MHz range such as in the 6.78 MHz band used for wireless power transfer. To maintain the proper timing or switching waveform when operating at high frequencies, a feedback loop is used. The rectification circuit includes a multi-level waveform generator circuit that generates a multi-level control waveform from the input waveform and an indication of its current. The multi-level control waveform is maintained in phase with the input waveform. A control signal generation circuit receives the multi-level control waveform and generates control signals corresponding to levels of the multi-level control waveform. A synchronous rectifier receives the input waveform and includes a plurality of switches to provide an output voltage generated from the input waveform. The switches are coupled to receive the control signals and the output voltage is a function of the multi-level control waveform.