Wireless Power Receiver Discharging Circuit Voltage Jump Suppression
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Solution Overview
Problem
In wireless power transmission systems, such as those conforming to the Qi and PMA standards, the rectified voltage in power receivers can periodically jump due to modulation, leading to unstable operation and potential overvoltage issues, especially when transitioning from low to medium power levels.
Innovation Solution
A wireless power receiver is designed with an overvoltage detecting circuit and a discharging circuit that can be switched between enable and disable states, discharging the smoothing capacitor during modulation periods to suppress voltage jumps and prevent overvoltage protection malfunctions, thereby stabilizing circuit operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the modulator changes the parallel resonance frequency of the receiving antenna during communication, then information can be transmitted to the power transmitter, but the rectified voltage periodically jumps up causing unstable operation
Solution Approach 1:
A discharging circuit is introduced as an intermediary component between the smoothing capacitor and ground. This circuit includes a discharge transistor that provides a controlled discharge path for the capacitor during modulation periods, preventing voltage jumps without interfering with the normal power transfer function.
Solution Approach 2:
The discharging circuit is activated periodically during communication periods when the modulator changes the resonance frequency. The control circuit detects modulation events and triggers the discharging circuit only during these specific time windows, allowing information transmission while suppressing voltage jumps at critical moments.
2Adaptability or versatility
If the rectified voltage is allowed to jump up during modulation, then communication can proceed, but overvoltage protection circuits may malfunction
Solution Approach 1:
The discharging circuit performs preliminary anti-action by proactively discharging the smoothing capacitor during modulation periods before overvoltage conditions can develop. This preventive measure counteracts the voltage jumps that would otherwise occur during frequency changes, protecting the overvoltage protection circuit from malfunctioning.
3Reliability
If a discharging circuit is added to suppress voltage jumps, then operation stability improves, but device complexity increases
Solution Approach 1:
The discharge transistor in the discharging circuit is controlled by the existing control circuit that already manages the modulator and communication protocols. This existing control infrastructure is extended to also control the discharge transistor, allowing the new component to be integrated without requiring a completely separate control system.
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 effectively suppresses rectified voltage jumps and maintains stable operation by discharging the smoothing capacitor during communication periods, preventing overvoltage issues and ensuring reliable power transmission across varying power levels.
Implementation Method 1
The receiving coil 302 receives the power signal S2 from the transmitting coil 202
Implementation Method 2
The rectifying circuit 304 and the smoothing capacitor 306 rectify and smooth a current S4 induced in the receiving coil 302
Implementation Method 3
The modulator 310 changes a parallel resonance frequency of the receiving antenna 301 based on the control data S3 including the power control data
Data Source
AI summary
A wireless power receiver that receives a power signal from a wireless power transmitter includes: a receiving antenna including a receiving coil for receiving the power signal; a rectifying circuit configured to rectify an alternating current flowing through the receiving antenna; a smoothing capacitor configured to smooth an output of the rectifying circuit; an overvoltage detecting circuit configured to compare a rectified voltage generated in the smoothing capacitor with an overvoltage threshold; a modulator configured to change a parallel resonance frequency of the receiving antenna; and a discharging circuit configured to be switched between an enable state and a disable state and configured to enter the enable state during a communication period by the modulator to discharge the smoothing capacitor.