Microcontroller Self-Powering via Internal AC Rectification
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Solution Overview
Problem
Microcontrollers embedded in personal care products, such as shavers, face challenges in receiving efficient DC power due to their location, which can be difficult to power using conventional methods, especially when they require AC power sources like wireless receivers or energy harvesting modules.
Innovation Solution
A microcontroller apparatus with MOSFET switches and a processing module that rectifies AC power to DC power internally, using high-side and low-side switches with body diodes to control the rectification process, allowing the microcontroller to operate without an external DC source, and providing power for itself and control signals for host devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a microcontroller is embedded in a personal care product with limited space, then the device becomes more compact, but providing suitable DC power to the microcontroller becomes difficult
Solution Approach 1:
The patent combines the rectifier circuit functionality into the microcontroller apparatus itself, merging the power conversion function with the control unit. The microcontroller includes internal high-side and low-side switches that directly perform rectification on AC waveforms received from energy harvesting modules or wireless power receivers, eliminating the need for separate external rectifier circuits and reducing overall device volume while maintaining powering capability
Solution Approach 2:
The microcontroller is configured to power itself by receiving AC waveforms from energy harvesting modules or wireless power receivers and internally rectifying them to DC voltage. The apparatus includes a processing module that autonomously controls the switching of high-side and low-side MOSFET switches to perform synchronous rectification, enabling the microcontroller to convert received AC power into usable DC power without requiring external DC power sources
2Reliability
If an external DC power source is used, then the microcontroller can be powered reliably, but the device complexity and external component requirements increase
Solution Approach 1:
The patent extracts the DC power source requirement from the system by enabling the microcontroller to directly accept and rectify AC waveforms. Instead of requiring an external DC power source, the microcontroller apparatus includes internal circuitry that takes the AC input from energy harvesting modules or wireless power receivers and converts it to the necessary DC voltage, removing the need for external DC power sources and associated components
Solution Approach 2:
The microcontroller apparatus is designed with multi-functionality, where the same high-side and low-side switches serve both as control elements for GPIO ports and as active rectifier elements for power conversion. The processing module manages both control signal generation and synchronous rectification, allowing a single integrated circuit to perform multiple functions including power conversion, control, and rectification, thereby reducing external component requirements
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 solution enables efficient self-powering of microcontrollers from AC sources, reducing the need for external components and enhancing power efficiency, making it suitable for compact devices like shaver products with limited space and power constraints.
Implementation Method 1
Each output port has an associated high-side switch electrically connected between the output port and a high-side DC voltage rail and an associated low-side switch electrically connected between the output port and a low-side DC voltage rail, wherein said high-side switches and said low-side switches each comprise a MOSFET switch with a body diode
Implementation Method 2
a capacitance electrically connected to the high-side DC voltage rail
Data Source
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Figure 3
Figure 4~5
AI summary
This application relates to methods and apparatus for powering microcontrollers (104), in particular for powering microcontrollers of a personal care product, such as a shaver product (107). The microcontroller is arranged such that a first output port (206-1) of a plurality of output ports of the microcontroller receives, in use, an AC waveform. Each output port has an associated high-side switch (207) electrically connected between the output port and a high-side DC voltage rail and an associated low-side switch (208) electrically connected between the output port and a low-side DC voltage rail. A processing module (202) of the microcontroller is configured to monitor a phase of the AC waveform and to control switching of the associated high-side and low-side switches of the first output port based on the phase of the AC waveform so as to provide a rectified voltage between the high-side DC voltage rail and the low-side voltage rail for powering the processing module. The processing module (202) also controls switching of the associated switches of at least a further output port to output a control signal for controlling at least one aspect of operation of a host device. The processing module is further configured to maintain the associated high-side switch of the first output port in a turned-off state when a monitored voltage of the AC waveform at the first output port is between zero and a monitored voltage at the high-side DC voltage rail, and to maintain the associated high-side switch of the first output port in a turned-on state when the monitored voltage of the AC waveform at the first output port is greater than the monitored voltage at the high-side DC voltage rail.