Wireless Power Receiver Feedforward Control for Overcurrent Prevention
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Solution Overview
Problem
Existing wireless power transfer technologies face insufficient responsiveness in controlling supply current, leading to excessive received power and potential overcurrent issues, which can damage batteries or cause electromagnetic interference (EMI).
Innovation Solution
A wireless power receiving device employs a feedforward control mechanism to switch between first and second current states based on detected electrical characteristics, using a current switching unit and a control unit to manage current ratios dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control is used to control the period during which current is zero, then the control can accommodate changes in power transmission, but the responsiveness of the control is insufficient leading to excessive received power at transition
Solution Approach 1:
The patent applies preliminary action by using feedforward control to anticipate and respond to power transmission changes before they cause excessive received power. The control unit calculates the required duty ratio based on the transmitted power level in advance, allowing the current control to adjust proactively rather than reactively, thus improving responsiveness while maintaining stability
Solution Approach 2:
The patent combines feedforward control with feedback mechanisms where the control unit continuously monitors the actual current and adjusts the duty ratio accordingly. This hybrid approach maintains the stability benefits of feedback control while adding the responsiveness of feedforward control, resolving the contradiction between the two requirements
2Power
If the amount of power transmitted is abruptly increased, then the power supply capacity is improved, but control on the power receiving device side could not accommodate the increase leading to overcurrent to battery
Solution Approach 1:
The patent applies preliminary action by calculating and setting the appropriate duty ratio before the power transmission increase takes full effect. The control unit uses the relationship between transmitted power and required duty ratio to proactively adjust the current control, preventing overcurrent to the battery while still allowing increased power supply capacity
Solution Approach 2:
The patent applies preliminary anti-action by implementing control measures that counteract the potential harmful effect of abrupt power increases before they can cause damage. The duty ratio adjustment is designed to preemptively prevent overcurrent conditions, protecting the battery from damage while still utilizing the increased power transmission capability
3Power
If the amount of power transmitted is abruptly increased, then the power supply capacity is improved, but the control could not accommodate the increase leading to deterioration of EMI at transition
Solution Approach 1:
The patent applies preliminary action by pre-calculating the duty ratio adjustments needed for different power transmission levels. This allows the control system to smoothly transition between power levels by having the appropriate control parameters ready in advance, preventing abrupt changes that would generate electromagnetic interference
Solution Approach 2:
The patent applies dynamics by making the duty ratio adjustable and responsive to changing power transmission conditions. The control unit dynamically adjusts the duty ratio based on the transmitted power level, enabling smooth transitions that minimize electromagnetic interference while maintaining optimal power supply capacity
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 feedforward control system quickly adjusts current supply to match target values, preventing overcurrent and reducing electromagnetic interference, thereby enhancing system stability and battery life.
Implementation Method 1
a power receiving unit that includes a power receiving coil and receives AC power by magnetic coupling
Data Source
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AI summary
At least a part of AC power received by a power receiving coil (31) at a position where magnetic coupling with a power transmitting coil (51) is possible is supplied from a circuit (331) that functions as a current source to a load (45). At this time, an electrical characteristic of a current source in this circuit is detected, and switching between a first state of supplying a first current from the current source to the load and a second state of supplying a second current smaller than the first current from the current source to the load is performed to feedforward-control a ratio of the first state or the second state to one cycle of the AC power according to the detected electrical characteristic.