Wireless Power Transmitter Duty Cycling for Low-Load Efficiency
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Solution Overview
Problem
Wireless power transfer systems face inefficiencies due to high operating power requirements for controlling switching elements in transmitters, especially at low power loads, leading to inefficient power transfer to receivers.
Innovation Solution
A controller is implemented in the transmitter control circuitry to vary the duty cycle of the inverter based on detected load signals, enabling selective enabling/disabling of switching elements and reducing power consumption by only operating when a receiver is present, using analog electronics for improved efficiency and compliance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inverter switching elements are continuously operated to ensure power transfer capability, then the system readiness and power transfer capability are improved, but the power consumption increases significantly especially at low power loads
Solution Approach 1:
The patent implements periodic duty cycling of the inverter switching elements, alternating between active and inactive states. The controller periodically enables the switching elements for a defined duty cycle period, then disables them, creating a periodic operation pattern that reduces average power consumption while maintaining intermittent power transfer capability.
Solution Approach 2:
The system uses the receiver's own power requirements to control the transmitter's operation. When the receiver draws power, it creates a detectable load signal that automatically triggers the transmitter to activate. The system serves itself by using the presence of a load to determine when activation is necessary, eliminating the need for continuous operation.
2Productivity
If the transmitter operates continuously to maintain field generation, then the power transfer readiness is improved, but the efficiency deteriorates at low power loads due to high operating power requirements
Solution Approach 1:
The inverter switching elements are operated periodically rather than continuously, with the controller enabling them for specific duty cycles and disabling them during idle periods. This periodic operation maintains power transfer readiness during active periods while significantly reducing energy loss during inactive periods, especially at low power loads.
Solution Approach 2:
The system dynamically adjusts the operational state of the inverter switching elements based on real-time conditions. The controller monitors load signals and dynamically transitions the switching elements between enabled and disabled states, optimizing the balance between productivity and energy efficiency according to actual power transfer needs.
3Difficulty of detecting and measuring
If the switching elements are enabled frequently to detect receiver presence, then the detection capability is improved, but the power consumption increases
Solution Approach 1:
The system performs receiver detection periodically rather than continuously, enabling the switching elements for brief intervals to sense the presence of a receiver, then disabling them. This periodic detection approach maintains the ability to detect receiver presence while minimizing the power consumed during detection operations.
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 the power efficiency of the transmitter and wireless power transfer by reducing average power consumption and extending component lifespan, while being simpler and less expensive to implement than software solutions.
Implementation Method 1
The inverter may include a number of switching elements. A large amount of power may be required to control the switching elements.
Implementation Method 2
In magnetic induction systems, the transmitter has a transmitter coil with a certain inductance that transfers electrical energy from the power source to the receiver, which has a receiver coil with a certain inductance. Power transfer occurs due to coupling of magnetic fields between the coils or inductors of the transmitter and receiver.
Implementation Method 3
Power transfer occurs due to coupling of magnetic fields between the coils or inductors of the transmitter and receiver.
Implementation Method 4
In electrical capacitive systems, the transmitter and receiver have capacitive electrodes. Power transfer occurs due to coupling of electric fields between the capacitive electrodes of the transmitter and receiver.
Data Source
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AI summary
There is provided transmitter control circuitry for controlling a duty cycle of an inverter of a transmitter of a wireless power transfer system based on detection of a load signal at the transmitter. There is further provided receiver control circuitry for controlling operation of a receiver of a wireless power transfer system, the circuitry modifying of the load at the input or output of a rectifier of a receiver of a wireless power transfer system to vary a load signal at the receiver. The transmitter control circuitry may control the duty cycle of the inverter based on detection of the load signal from the receiver.