Wireless Power Receiver Synchronous Rectifier Reverse Current Control
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Solution Overview
Problem
Conventional power receiving devices using semiconductor switching elements for synchronous rectification face challenges in improving rectification efficiency and reducing conduction losses.
Innovation Solution
A power receiving device with a secondary coil, a synchronous rectifier circuit including a switching element unit, a smoothing circuit, and a control circuit that turns off the switching element unit when the current is below a threshold, along with a full-bridge circuit configuration and a reverse flow suppression circuit using a shunt resistor and comparator to manage current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If synchronous rectifier circuit using semiconductor switching elements is employed, then rectification efficiency is improved, but conduction losses increase and control complexity increases
Solution Approach 1:
The control circuit monitors the current flowing from the synchronous rectifier circuit to the smoothing circuit and uses this feedback information to determine when to turn off the switching elements. The control circuit compares the monitored current with a predetermined threshold value and adjusts the switching element operation accordingly, creating a closed-loop control system that optimizes rectification efficiency while managing complexity.
Solution Approach 2:
The synchronous rectifier circuit uses its own output current information to control its switching elements. The current flowing through the circuit itself serves as the control signal reference, eliminating the need for external control signals from the power transmission device. This self-control mechanism simplifies the overall system complexity while maintaining efficient rectification.
2Power
If switching element unit operates continuously, then power transmission efficiency is maintained, but reverse current flow occurs causing energy loss
Solution Approach 1:
The operating state of the switching element unit is dynamically adjusted based on real-time current conditions. The control circuit continuously monitors the current and changes the switching element state (on/off) accordingly. This dynamic control allows the system to adapt to varying load conditions and prevent reverse current flow while maintaining optimal power transmission efficiency during normal operation.
Solution Approach 2:
The control circuit is configured to turn off the switching element unit proactively when the current falls below the threshold value, before reverse current flow can occur. This preliminary action prevents the harmful reverse current condition from developing, thereby avoiding energy losses associated with reverse conduction.
3Loss of energy
If current threshold control is implemented, then reverse current flow is suppressed, but device complexity increases
Solution Approach 1:
The control circuit combines multiple functions into a single integrated unit: current monitoring, threshold comparison, and switching element control. Rather than adding separate circuits for each function, the design merges these operations into one compact control circuit that handles all tasks using the current information already present in the system.
Solution Approach 2:
The control circuit acts as an intermediary between the synchronous rectifier circuit and the switching element unit. It receives current information from the rectifier circuit, processes this information by comparing it with the threshold value, and generates appropriate control signals for the switching elements. This intermediary approach simplifies the overall control architecture while achieving effective reverse current suppression.
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 solution enhances synchronous rectification efficiency, suppresses reverse current flow, and reduces conduction losses compared to diode-based rectification, improving power transmission efficiency and simplifying device configuration.
Implementation Method 1
a secondary coil that receives alternate current power wirelessly transmitted from a primary coil
Data Source
AI summary
A power receiving device includes a secondary coil, a synchronous rectifier circuit, a smoothing circuit, and a reverse flow suppression circuit. The secondary coil receives the alternate current power wirelessly transmitted from the primary coil. The synchronous rectifier circuit includes a switching element unit that rectifies the alternate current power received by the secondary coil into direct current power. The smoothing circuit smooths the direct current power rectified by the synchronous rectifier circuit. The reverse flow suppression circuit controls the switching element unit. For example, the reverse flow suppression circuit turns off the switching element unit of the synchronous rectifier circuit when a current flowing from the synchronous rectifier circuit to the smoothing circuit is smaller than a predetermined current threshold value.