Wireless Inductive Power Transfer Asymmetric Communication
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Solution Overview
Problem
Current wireless power transfer systems, particularly those adhering to the Qi standard, face challenges in bidirectional communication, with unidirectional communication from the power receiver to the transmitter being insufficient, leading to issues like interference, reduced reliability, and sensitivity to load variations, especially in scenarios with motor-driven appliances.
Innovation Solution
A wireless power transfer system incorporating a power transmitter with a separate communication link for receiving data from the power receiver, using a second communication coil with a range exceeding that of the power transfer coil, to enable asymmetric communication and reduce interference, while ensuring that only messages from appropriately positioned power receivers control the power transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a unidirectional communication link from power receiver to power transmitter is used, then the power receiver can provide information to adapt the power transmitter, but bidirectional communication is not supported leading to reduced reliability and interference issues
Solution Approach 1:
The communication system is segmented into two separate communication links: a first communication link for power transfer and a second communication link for data communication. This segmentation allows each link to be optimized independently, with the second link providing reliable bidirectional communication without interfering with the power transfer function of the first link.
Solution Approach 2:
A separate second communication link acts as an intermediary channel between the power transmitter and power receiver. This intermediary link handles data communication tasks, allowing the primary power transfer link to focus on power transmission while maintaining reliable bidirectional communication through the secondary channel.
2Device complexity
If the communication link uses the same coil as the power transfer coil, then communication can be integrated, but interference between power transfer and communication occurs
Solution Approach 1:
The system segments the electromagnetic coupling functions into two separate coils: a first coil dedicated to power transfer and a second coil dedicated to communication. This physical segmentation eliminates interference between power transfer and communication operations while maintaining a relatively simple integrated system architecture.
Solution Approach 2:
While using separate coils, the system merges the power transfer and communication functions into a single unified wireless interface. The first coil handles power transfer while the second coil handles communication, creating a combined system that provides both functions through a single wireless coupling mechanism between the transmitter and receiver.
3Reliability
If a separate communication link with extended range is used, then communication reliability improves, but the risk of receiving messages from incorrectly positioned power receivers increases
Solution Approach 1:
The system implements feedback mechanisms where the power receiver provides information about its positioning and coupling status through the second communication link. The power transmitter uses this feedback to verify that the power receiver is correctly positioned and to adjust power transfer accordingly, ensuring that extended-range communication does not lead to power transfer to incorrectly positioned devices.
Solution Approach 2:
Before initiating power transfer, the system performs preliminary communication through the second link to establish proper coupling and positioning. This preliminary action includes verifying the power receiver's position and coupling status before enabling full power transfer, preventing power transfer to incorrectly positioned devices even though the communication range is extended.
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 communication reliability, reduces interference between power transfer operations, and improves safety by ensuring that only messages from correctly positioned power receivers control the power transfer, thereby maintaining robust and flexible power transfer operations.
Implementation Method 1
a transmit power transfer coil for transferring power to a power receiver via a power transfer signal
Implementation Method 2
a first communication unit for communicating messages to the power receiver on a first communication link using a first communication coil
Implementation Method 3
a second communication unit arranged to receive data from the power receiver on a second communication link not using the first communication coil and having a range exceeding the range of the first communication link
Data Source
AI summary
A power transmitter (101) is arranged to transfer power to a power receiver (105) via a wireless inductive power transfer signal transmitted from a transmit coil (103) to a power receiver (105). A first communication unit (305) communicates a message to the power receiver (105) on a first communication link A second communication unit (307) receives data from the power receiver (105) on a separate second communication link having a longer range. The power receiver (105) comprises a third communication unit (405) which receives the first message. A response generator (407) generates a response message to the message and a fourth communication unit (409) transmits the response message to the power transmitter (103) over the second communication link. The power transmitter (103) determines an expected response message to the message and a power controller (303) controls the power level of the power transfer signal dependent on whether a message is received on the second communication link corresponding to the expected response message.