Power Supply Device Input Current Estimation via Bus Voltage Rate of Change
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Solution Overview
Problem
Existing power supply devices for household appliances require dedicated current sensors to measure input current, increasing device size, complexity, and manufacturing costs.
Innovation Solution
A power supply device using a quasi-resonant switching converter that estimates input current based on the rate of change of bus voltage during the second switching period, eliminating the need for dedicated current sensors and simplifying the circuit structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated current sensors (current transformer, Hall Effect sensor, shunt circuit) are embedded to measure input current, then measurement precision is improved, but device complexity and manufacturing costs increase
Solution Approach 1:
The patent uses the bus capacitor as an intermediary element to indirectly measure input current. Instead of directly measuring current through dedicated sensors, the voltage across the bus capacitor is monitored, and current is derived from the rate of change of this voltage. This mediator approach eliminates the need for separate current sensing hardware while maintaining measurement capability.
Solution Approach 2:
The bus capacitor, which is already present in the power supply circuit for voltage stabilization, is made to serve an additional function: current measurement. By monitoring the voltage changes across this existing component, the system obtains current information without requiring separate measurement infrastructure, thus making the existing component work for multiple purposes.
2Measurement precision
If dedicated current sensors are embedded to measure input current, then measurement precision is improved, but manufacturing costs increase
Solution Approach 1:
The bus capacitor is designed to perform multiple functions simultaneously: voltage stabilization (its primary function) and current measurement (the new function). This multi-functionality eliminates the need for dedicated current sensing components, reducing part count and manufacturing complexity while maintaining accurate current measurement capability through voltage monitoring.
3Measurement precision
If dedicated current sensors are embedded to measure input current, then measurement precision is improved, but device size increases
Solution Approach 1:
The patent employs voltage across the bus capacitor as an intermediary measurement parameter instead of directly measuring current. This approach allows current information to be derived from voltage changes using existing circuit elements, eliminating the need for additional physical space dedicated to current sensing components and their associated circuitry.
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
Enables cost-effective and simplified manufacturing by using voltage measurements to estimate input current, reducing hardware complexity and maintaining efficient operation.
Implementation Method 1
a bus capacitor (C DC ), which is electrically connected in parallel with the output terminals of said rectifying stage (12), is part of said filtering arrangement
Data Source
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AI summary
The present invention relates to a power supply device (100) for a household appliance which comprises a switching converter comprising an input filtering stage (LD, CD), including at least a filtering inductor (LD) and a rectifying stage (12) that are electrically connected with the mains (10). The switching converter comprises a bus capacitor (CDC), electrically connected in parallel with output terminals of said rectifying stage (12), and a resonant tank (200), electrically connected with said bus capacitor (CDC). The switching converter further comprises a switching device (130) in series with said resonant tank (200), said switching device being operated with a switching cycle (T) that comprises a first switching period (TON), in which said switching device allows the flow of a first current (IS) between said bus capacitor (CDC) and said resonant tank (200), and a second switching period (TOFF), in which said switching device blocks the flow of said first current (IS). The power supply device comprises determining means (161, 161A, 162, 132, 135) configured to obtain estimation data (D3) indicative of the input current (IN) that is adsorbed from the mains (10), on the base of the rate of change of the bus voltage (VDC) across said bus capacitor respectively, during said second switching period.