Wireless Power Transmitter Frequency Control for Load Transients
Solution Overview
Problem
Existing wireless power transfer systems face challenges in adapting to rapid load changes, leading to overvoltage and over-current conditions, particularly in high-power applications like kitchen appliances, due to the inherent lag and low response times of control loops.
Innovation Solution
A power transmitter and receiver system that adjusts the operating frequency to a reduced load sensitivity frequency in response to anticipated load changes, suspending the power control loop during the change and resuming it afterward to improve transient performance and reduce voltage/current variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a control loop is used to compensate for load variations and adapt power transmission, then power transfer accuracy is improved, but response time to rapid load changes deteriorates causing overvoltage and over-current conditions
Solution Approach 1:
The system performs preliminary detection of anticipated load changes and proactively adjusts the operating frequency before the actual load change occurs. This preemptive action allows the system to prepare for rapid load transitions by setting appropriate frequency values in advance, eliminating the response time delay inherent in traditional feedback control loops.
Solution Approach 2:
The system dynamically switches between different operating frequencies based on detected load conditions. When a load change is anticipated, the system transitions to a first operating frequency optimized for transient performance; when load is stable, it uses a second operating frequency optimized for power transfer efficiency. This dynamic adaptation resolves the contradiction by having different frequency settings for different operational states.
2Reliability
If operating frequency is adjusted for rapid load changes, then transient performance is improved, but power transfer efficiency during stable operation may deteriorate
Solution Approach 1:
The system implements dynamic frequency switching that adapts to operational conditions. During transient load changes, it uses a first operating frequency that optimizes transient response and minimizes overvoltage/over-current conditions. During stable operation, it switches to a second operating frequency that maximizes power transfer efficiency. This dynamic adaptation ensures optimal performance for each operational state without compromising the other.
Solution Approach 2:
The system changes the operating frequency parameter based on detected load conditions. By having multiple predefined frequency values and selecting the appropriate one based on whether load is changing or stable, the system optimizes both transient performance and steady-state efficiency through parameter adaptation rather than using a single fixed frequency.
3Measurement precision
If control loop response is slowed to reduce noise and improve accuracy, then measurement precision is improved, but ability to handle rapid load changes deteriorates
Solution Approach 1:
The system detects anticipated load changes in advance and proactively adjusts the operating frequency before the actual load transition occurs. This preliminary action bypasses the need for rapid control loop response, allowing the use of slower, more noise-resistant control loops while still achieving fast adaptation to load changes through the predictive frequency adjustment mechanism.
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 load change performance, reduces overvoltage/over-current conditions, and improves system adaptability to load variations, facilitating efficient and stable power transfer even with significant load steps.
Implementation Method 1
a power transmitter for wirelessly providing power to a power receiver via an inductive power transfer signal; an output resonance circuit comprising a transmitter coil and at least one capacitor
Implementation Method 2
an output resonance circuit comprising a transmitter coil and at least one capacitor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A wireless power system comprises a power receiver (105) receiving power from a power transmitter (101) which comprises an output resonance circuit comprising a transmitter coil (103) and a capacitor (303). A driver (301) generates a drive signal for the output resonance circuit to generate an inductive power transfer signal. A frequency determiner (313) provides a reduced load sensitivity operating frequency for the drive signal and a frequency controller (311) changes the operating frequency of the drive signal to the reduced load sensitivity operating frequency in response to receiving a load change message from the power receiver. A transmitter (309) transmits a load change acknowledge message to the power receiver (105) to indicate the change of frequency. The frequency controller (311) changes the operating frequency from the reduced load sensitivity operating frequency to a load dependent operating frequency in response to determining that the power receiver (105) has performed the load change.