Impedance Element for Inductive Power Transmitter Noise Suppression
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Solution Overview
Problem
Inductive power transmitters face challenges in meeting electromagnetic compatibility (EMC) regulations due to electromagnetic noise conducted back into the mains supply, particularly through their mains cables, which can be exacerbated by harmonics and spurious tones generated by nonlinearities in portable devices.
Innovation Solution
Incorporating impedance elements along the electrical path of inductive power transmitters and conduits with high impedance at the fundamental frequency to suppress electromagnetic noise, while maintaining low impedance at DC frequencies to ensure efficient power transmission, thereby reducing noise conducted back into the power source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If shielded mains cable is used to suppress electromagnetic noise, then electromagnetic compatibility is improved, but cost increases prohibitively
Solution Approach 1:
The patent introduces an impedance element as an intermediary component connected along the electrical path between the power source and the field generator. This impedance element acts as a mediator that selectively suppresses electromagnetic noise at the fundamental frequency while allowing power transmission at different frequencies to pass through, thereby resolving the contradiction between noise suppression and cost-effectiveness without requiring expensive shielded cables
Solution Approach 2:
The patent changes the electrical parameters of the system by introducing an impedance element with specific frequency-dependent characteristics. The impedance element is designed to have high impedance at the fundamental frequency of the electromagnetic field to block noise, while maintaining low impedance at other frequencies to allow power transmission, thus achieving noise suppression without the need for expensive shielded cable assemblies
2Object-affected harmful factors
If impedance elements with high impedance at fundamental frequency are added, then electromagnetic noise suppression is improved, but device complexity increases
Solution Approach 1:
The patent extracts the noise suppression function from the main transmitter circuitry and implements it through a separate, dedicated impedance element connected along the electrical path. This separation allows the impedance element to be optimized specifically for noise suppression without complicating the core power transmission circuitry, thereby improving noise suppression while minimizing increases in overall device complexity
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 mitigates electromagnetic noise at the power source, meeting EMC regulations without significantly affecting power transmission to the transmitter, and is cost-effective by avoiding the use of expensive shielded cables.
Implementation Method 1
an inductive power transmitter for transmitting electrical power to an electrical or electronic device by electromagnetic induction
Implementation Method 2
the impedance element or a combination of the impedance elements has a high enough impedance at the fundamental frequency such that, in use, electromagnetic noise experienced at the power source is substantially suppressed
Data Source
AI summary
An inductive power transmitter for transmitting electrical power to a device by electromagnetic induction, the transmitter being configured to receive power conductively by way of a current via an electrical conduit from an external power source, the transmitter including a field generator configured to generate a fluctuating electromagnetic field having a fundamental frequency; and at least one impedance element connected along an electrical path of the transmitter configured to carry said current, the impedance element or a combination of the impedance elements having a high enough impedance at the fundamental frequency such that, in use, electromagnetic noise experienced at the power source is substantially suppressed, such noise arising from coupling between the electromagnetic field and a circuit having said path and linking the power source to the transmitter.