Undervoltage Cut-off Switch for Power Supply Load Disconnection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power supply systems, particularly switching mode power supplies, fail to reduce load voltage to 0 V when the input is cut due to high capacitance capacitors, leading to synchronization errors and unwanted current flow, and existing solutions involving microcontrollers are expensive and delayed.
Innovation Solution
A power supply system comprising a filtering circuit and a switching circuit with a p-MOS transistor and resistors that disconnects the load from the filtering circuit when the output voltage falls below a predefined level, using a p-MOS transistor with resistors to rapidly set the load voltage to 0 V without the need for microcontrollers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a microcontroller is used to control the input voltage and disconnect the filtering capacitor when input voltage is below threshold, then the load voltage can be reduced to 0 V, but the system becomes expensive and experiences delays due to microcontroller speed limits
Solution Approach 1:
The patent extracts the control function from the microcontroller and implements it directly at the transistor level. The discharge transistor's gate is connected to the filtering capacitor output, allowing the transistor itself to sense voltage and automatically disconnect when voltage drops below threshold, eliminating the need for microcontroller-based voltage sensing and control logic
Solution Approach 2:
The discharge circuit is designed to be self-regulating through the transistor's inherent characteristics. When the filtering capacitor voltage drops below the transistor's threshold voltage, the transistor automatically turns off the discharge path, providing self-service voltage monitoring and control without external microcontroller intervention
2Reliability
If a microcontroller is used to control the power supply input voltage, then the load voltage can be reduced to 0 V, but the system experiences delays due to microcontroller speed limits
Solution Approach 1:
The patent replaces the mechanical/software-based microcontroller control system with an electronic transistor-based control system. The transistor responds instantaneously to voltage changes through its electrical characteristics, eliminating the processing delays inherent in microcontroller-based systems and achieving near-instantaneous disconnection when voltage drops
3Stability of the object's composition
If high capacitance capacitors are used in the filtering circuit, then the DC voltage is well-filtered, but the load voltage cannot be reduced to 0 V when input is cut
Solution Approach 1:
The patent segments the filtering function from the voltage reduction function. The high capacitance capacitor continues to perform its filtering function independently, while a separate discharge transistor circuit is added specifically for voltage reduction. This segmentation allows both functions to coexist without interfering with each other
Solution Approach 2:
The discharge transistor acts as an intermediary element between the filtering capacitor and the load. It controls the discharge path of the capacitor, allowing the capacitor to maintain high capacitance for filtering while the transistor mediates the voltage reduction by providing a controlled discharge path when needed
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 allows for rapid disconnection of the load from the power supply, eliminating synchronization errors and reducing system complexity and cost by using only transistors and resistors, ensuring the load voltage reaches 0 V quickly and efficiently.
Implementation Method 1
switching circuit comprises at least one p-MOS type first transistor, the source terminal of which is connected to the output of the filtering circuit and the drain terminal of which is connected to said load
Implementation Method 2
disconnects said load from the output of filtering circuit when voltage level of the output of the filtering circuit is below a predefined level
Implementation Method 3
at least one first resistor which is connected between the gate terminal and the source terminal of the first transistor
Implementation Method 4
at least one second resistor which is connected between the gate terminal of first transistor and the ground
Data Source
Figure 1~2
AI summary
With the present invention, a power supply system that converts an AC voltage to at least one DC voltage to feed at least one load (L) is provided. Said power supply system comprises at least one power supply (P) for converting said AC voltage to at least one DC voltage; at least one filtering circuit (F), which is connected to the output of said power supply (P); and at least one switching circuit (S) which connects said load (L) to an output of said filtering circuit (F) and which disconnects said load (L) from the output of filtering circuit (F) when voltage level of the output of the filtering circuit (F) is below a predefined level.