Inductive Power Transfer Control for Load Impedance Switching
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Solution Overview
Problem
Existing wireless power transfer systems using inductive coupling face challenges in maintaining reliable operation when the load impedance of electrical consumers changes rapidly, leading to potential overvoltages and flashovers due to abrupt changes in load impedance, especially in devices like Airfryers with multiple load elements.
Innovation Solution
The method synchronizes the operation of the transmitter and receiver by adjusting the transition frequency and duty cycle of the pulse-width-modulated activation signal before or during load impedance changes, ensuring induced voltages remain within specified threshold values, and temporarily disabling regulation to prevent overvoltages, allowing for synchronized switching of load impedance with minimal impact on induced load voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the load impedance of the electrical consumer changes rapidly, then the power consumption can be adapted to different operational requirements, but overvoltages and flashovers occur due to abrupt changes in load impedance
Solution Approach 1:
The transmitter is informed in advance about the planned load impedance change by the receiver. Based on this preliminary information, the transmitter can prepare appropriate countermeasures such as adjusting the activation signal parameters or temporarily disabling regulation before the load change occurs, thereby preventing overvoltages while allowing load adaptability
Solution Approach 2:
The system uses bidirectional communication between transmitter and receiver to exchange information about load impedance changes. The receiver communicates its planned load changes to the transmitter, which then adjusts its operation accordingly. This feedback mechanism enables coordinated control that maintains reliability while allowing load adaptation
2Measurement precision
If the regulator continuously regulates power output to maintain setpoint, then power precision is improved, but overvoltages occur during load impedance transitions due to regulation delays
Solution Approach 1:
When the transmitter receives information about an upcoming load impedance change, it temporarily disables the regulator or adjusts activation signal parameters before the transition occurs. This preliminary counter-action prevents the harmful overvoltages that would otherwise result from the regulation delay during load changes, while maintaining precise power regulation during normal operation
Solution Approach 2:
The regulation system dynamically adjusts its behavior based on the operational state. During normal operation, the regulator continuously maintains the power setpoint with high precision. During load transitions, the system switches to a different mode where regulation is temporarily disabled or parameters are adjusted, allowing the system to adapt its control strategy to avoid overvoltages while maintaining precision when needed
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 enables fast, synchronized switching of load impedance in receivers while reliably avoiding overvoltages, ensuring safe and efficient power transfer even with abrupt changes in load impedance, thereby maintaining reliable operation and preventing flashovers.
Implementation Method 1
a device (100) for the wireless transmission of energy to an electrical consumer (200) by means of inductive coupling
Data Source
AI summary
A method for operating a system having a device for the wireless transmission of energy to an electrical consumer by means of inductive coupling, and an electrical consumer, wherein the device has: a rectifier for generating a DC voltage from a line voltage, an inverter which is fed from the DC voltage and designed to generate a pulse-width-modulated activation signal, a power coil activated by the pulse-width-modulated activation signal, by means of which an alternating magnetic field can be generated to transmit the energy, a communication device designed to exchange data bi-directionally with the electrical consumer, and a regulator designed to regulate a power output by the inverter to a predetermined setpoint, and wherein the electrical consumer has: a switching device for changing the load impedance of the electrical consumer, and a communication device designed to exchange data bi-directionally with the device, wherein the method comprises the steps: synchronizing the operation of the device and the operation of the electrical consumer in such a way that, during a change in the load impedance of the electrical consumer, a transition frequency and/or a transition duty cycle of the pulse-width-modulated activation signal is/are set in such a way that voltages and/or currents induced in the electrical consumer do not exceed and/or fall below specified threshold values.