Inductive Power Transfer Control With Resonant Soft Switching
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Solution Overview
Problem
Inductive power transfer (IPT) systems for electric vehicle charging face challenges in efficiently managing grid frequency fluctuations and maintaining power transfer efficiency due to misalignment and load variations, which affect the stability and efficiency of the charging process.
Innovation Solution
A novel IPT power controller using Boolean operators to vary energy injections and synchronize switching logic with resonant frequency, implemented on FPGA hardware, enabling zero current switching (ZCS) and zero voltage switching (ZVS) for efficient power transfer and grid stabilization, with the ability to adjust charging levels from 1 to 32.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If inductive power transfer systems are used for electric vehicle charging, then charging convenience and grid-to-vehicle power transfer capability are improved, but voltage and frequency fluctuations on the electric grid increase, causing stability issues
Solution Approach 1:
The controller continuously monitors the resonant frequency of the IPT system and dynamically adjusts the switching frequency of the converter to maintain synchronization. This feedback mechanism allows the system to respond to load variations and misalignment conditions, maintaining stable power transfer and reducing adverse impacts on grid voltage and frequency stability
Solution Approach 2:
The system dynamically changes operating parameters including switching frequency, pulse width modulation (PWM) duty cycle, and energy injection timing to optimize power transfer efficiency under varying conditions. By adjusting these parameters in real-time, the system maintains efficient charging while minimizing grid disturbances
2Loss of energy
If the converter's switching is synchronized with the IPT system's resonant frequency to achieve soft switching conditions, then conversion efficiency is improved, but control complexity increases
Solution Approach 1:
The controller automatically detects the resonant frequency of the IPT system and self-adjusts the converter switching frequency to maintain synchronization. This self-service capability eliminates the need for complex external control systems while achieving soft switching conditions (ZCS and ZVS) for high efficiency operation
Solution Approach 2:
The system performs preliminary detection and adjustment of the resonant frequency before power transfer begins. By pre-synchronizing the converter switching with the IPT resonant frequency, the system ensures soft switching conditions are met from the start, reducing computational complexity during operation
3Adaptability or versatility
If multi-power level control with 32 discrete charging levels is implemented, then adaptability to varying power demands is improved, but control algorithm complexity increases
Solution Approach 1:
The 32 discrete power levels are segmented into manageable control states by dividing the power range into multiple quantized levels. Each level corresponds to specific combinations of positive and negative energy injection pulses, allowing the controller to select appropriate power levels through simplified logic rather than complex continuous control algorithms
Solution Approach 2:
The controller uses periodic pulse patterns with varying durations and frequencies to represent different power levels. By encoding power level information in the temporal characteristics of periodic energy injection pulses, the system achieves multi-power level control through time-based modulation rather than complex voltage or current regulation
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 provides high grid-to-battery efficiency, enhances power grid stability by responding to frequency fluctuations, and simplifies power level control, ensuring reliable and efficient inductive charging across varying conditions.
Implementation Method 1
Inductive power transfer (IPT) systems have garnered attention recently for charging applications including EVs, scooters, electric aircraft, wheelchair, and the like.
Implementation Method 2
The synchronization of the converter's switching with the IPT system's resonant frequency can allow the soft switching condition (both zero current switching (ZCS) and zero voltage switching (ZVS)) to be met, resulting in a highly efficient converter.
Data Source
AI summary
Power controllers (e.g., inductive power transfer (IPT) power controllers) and methods of making and using the same are provided. An IPT power controller can be implemented on direct alternating current (AC)-AC converters and can use only current and voltage measurements to produce multi-power level IPT controller and design switching logic. Using Boolean operators (e.g., AND, OR, Not) applied on a resonant current signal, varying positive energy injections (e.g., 1 to 16 pulses), and varying negative energy injections (e.g., 1 to 16 pulses), up to 32 different active states can be designed.