Demodulator with Parallel Units for Qi Wireless Power
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Solution Overview
Problem
The dynamic change in bias point of coil current or coil voltage due to load current variations in wireless power transmission systems affects packet reception rates, leading to instability in communication protocols, particularly in systems optimized for predetermined bias points.
Innovation Solution
A demodulator with multiple demodulating units, each with different characteristics operating in parallel, and a signal processing unit that selects the correctly received baseband signal based on checksum error detection, ensuring stable packet reception across varying load conditions by employing the optimal demodulating unit for the current load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a demodulator is optimized for a predetermined bias point, then packet reception rate is improved at that specific bias point, but packet reception rate deteriorates when load current varies and bias point changes
Solution Approach 1:
The demodulator is divided into multiple demodulating units (first, second, and third units) with different circuit configurations optimized for different bias point ranges. Each unit has distinct characteristics (e.g., different capacitor values, resistor configurations) that make it suitable for specific load current conditions. The signal processing unit segments the overall demodulation task by selecting which unit to activate based on the current operating conditions.
Solution Approach 2:
The demodulator dynamically adapts to changing load conditions by switching between different demodulating units based on the detected bias point. The signal processing unit monitors the operating conditions and activates the most appropriate demodulating unit in real-time, making the system dynamic rather than static. This allows the demodulator to maintain optimal performance across varying load currents.
2Adaptability or versatility
If multiple demodulating units with different characteristics are used, then adaptability to varying load conditions is improved, but device complexity increases
Solution Approach 1:
Multiple demodulating units with different characteristics are merged into a single demodulator structure, sharing common components such as the signal processing unit, bias point detection circuitry, and control logic. This merging approach allows the system to benefit from multiple optimized configurations while avoiding the full complexity of completely separate demodulators. The shared infrastructure reduces overall component count and simplifies the system architecture.
Solution Approach 2:
The signal processing unit serves multiple functions: it detects the bias point, determines which demodulating unit to activate, switches between units, and processes the demodulated signal. This multi-functionality reduces the need for separate dedicated circuits for each function, thereby reducing overall device complexity while maintaining the capability to handle multiple operating conditions.
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 configuration ensures stable and high-reception rate packet delivery even with changes in load current, maintaining optimal performance by selecting the appropriate demodulating unit for the current bias point, thereby improving the reliability of wireless power transmission systems.
Implementation Method 1
The driver 204 applies a driving signal S1, which is configured as a driving current or otherwise a driving voltage, to the transmission coil 202 such that the transmission coil 202 generates an electric power signal S2 in an electromagnetic field
Implementation Method 2
The reception coil 302 receives the electric power signal S2 from the transmission coil 202
Data Source
AI summary
A demodulator is mounted on a wireless power transmitter that conforms to the Qi standard, and demodulates an amplitude modulated signal superimposed on a coil current ICOIL that flows through a primary coil of a transmission antenna, or otherwise on a coil voltage across both ends of the primary coil. Multiple demodulating units are each configured to have respectively different configurations, to operate in parallel, to extract a demodulated component from the coil current ICOIL or otherwise from the coil voltage, and to generate baseband signals as demodulated signals. A signal processing unit employs a baseband signal that is correctly received, from among the multiple baseband signals generated by the multiple demodulating units, based on an error detection result obtained using a checksum.