Inductive Power Transfer Pick-Up Circuits with Segmented Switches
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Solution Overview
Problem
Inductive power transfer (IPT) systems face challenges in high power applications due to excessive switch stress, as the required ratings for peak switch voltage and current rise significantly with increasing circuit Q, leading to costly and inefficient designs, especially in parallel and series tuned AC processing topologies.
Innovation Solution
The introduction of new controller topologies for IPT systems, including a modified parallel-tuned and series-tuned resonant controller, which reduce switch stress by adjusting the impedance of inductor-capacitor pairs and using additional reactive elements to control power delivery, allowing for sinusoidal AC output and independent switch voltage control, thereby lowering switch VA ratings and minimizing harmonic distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If standard parallel or series tuned AC processing topologies are used in high power IPT applications, then power and voltage output requirements can be met, but switch ratings become prohibitively high and expensive
Solution Approach 1:
The patent divides the single high-stress switch into multiple switches arranged in series and parallel configurations. Each switch handles a portion of the total voltage and current stress, allowing the use of lower-rated, more cost-effective switches while maintaining the required power output capability.
Solution Approach 2:
The patent transitions from traditional single-switch topologies to multi-switch arrangements, adding dimensional complexity to the circuit architecture. This enables distribution of stress across multiple components, fundamentally changing how voltage and current are managed in the circuit.
2Power
If circuit Q, output power, and output voltage increase in standard topologies, then power transfer capability improves, but switch technology limitations become increasingly difficult to design around
Solution Approach 1:
By segmenting the switch network into multiple units, the patent enables higher output power and voltage while keeping individual switch ratings within available technology limits. The segmented architecture distributes the electrical stress that would otherwise exceed component capabilities.
Solution Approach 2:
The patent changes the electrical parameters (voltage, current, Q) that individual switches must handle by reconfiguring the overall circuit topology. This allows the system to operate at higher power levels while individual components remain within their reliable operating ranges.
3Ease of operation
If AC switch is directly in parallel with resonant inductor to control circuit Q, then power control is achieved, but switch VA rating must be at least 2Q² times the minimum required for power control
Solution Approach 1:
The patent segments the single high-VA switch into multiple lower-VA switches configured in series-parallel networks. This segmentation maintains the ability to control circuit Q and regulate power while reducing the VA rating requirement for each individual switch by a factor related to Q².
Solution Approach 2:
The patent employs dynamic switching strategies where multiple switches are activated and deactivated in coordinated sequences. This dynamic operation allows effective power control and Q regulation while keeping instantaneous VA demands on individual switches well below the static requirement of 2Q² times minimum power control rating.
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
These new topologies result in up to 3.8 times lower switch VA ratings, improved efficiency, and reduced RFI and harmonic distortion, enabling more cost-effective and efficient power transfer in high-power IPT systems.
Implementation Method 1
Inductive power transfer (IPT) systems
Implementation Method 2
parallel tuned AC controller circuits
Implementation Method 3
the AC switch is directly in parallel with the resonant inductor and must therefore be rated to survive the peak resonant inductor current
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
An inductive power transfer (IPT) pick-up circuit for receiving power from a primary conductor has a pick-up coil (L2) and a compensation capacitor (C2) so that the pick-up coil (L2) may be resonant at the system operating frequency, a switch (S1, S2), and a plurality of reactive elements (L3, C3) whereby when the switch is in one of an on state or an off state the additional reactive elements (L3, C3) are resonant at the operating frequency to reduce power being supplied to an output of the pick-up circuit.