Mains Filter Capacitor Isolation for Low-Standby Appliance EMI Control
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Solution Overview
Problem
Existing line filter devices for household appliances are inefficient in terms of energy consumption and costly due to continuous power supply requirements for discharge circuits, and they fail to effectively isolate capacitors from the power supply when the appliance is turned off, posing a risk of electric shock.
Innovation Solution
A line filter device with a control device that detects the power supply connection and uses a switching device to isolate the filter capacitor from the input when disconnected, utilizing an energy storage device for the control unit to ensure operation without continuous power, thus preventing electric shocks and reducing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a discharge circuit with active components is used to discharge filter capacitors when disconnected, then safety against electric shock is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the discharge function from a complex active circuit and implements it using a simple passive resistor component connected in parallel with the filter capacitor. This resistor automatically provides discharge functionality without requiring additional control circuits, microcontrollers, or active discharge components, thereby maintaining safety while reducing device complexity and cost.
Solution Approach 2:
The patent employs a simple resistor as a disposable, low-cost component to achieve the discharge function. Instead of using expensive and complex active discharge circuits with multiple components, a single resistor provides the necessary safety function at minimal cost and with minimal complexity.
2Reliability
If a resistor is connected in parallel with the filter capacitor to enable discharge, then safety is improved, but energy consumption increases during standby mode
Solution Approach 1:
The patent makes the discharge resistance dynamic by connecting it through a switching device that is controlled based on the operational state of the household appliance. During standby mode, the switching device disconnects the resistor to minimize energy consumption. When the appliance is fully powered on or during specific operational phases, the resistor is connected to provide discharge functionality, thus balancing safety requirements with energy efficiency.
3Reliability
If the filter capacitor remains connected to the power supply during standby, then filtering performance is maintained, but energy loss increases
Solution Approach 1:
The patent dynamically controls the connection between the filter capacitor and the power supply using a switching device. During standby mode, the switching device disconnects the filter capacitor from the power supply to eliminate continuous energy loss. When the appliance enters active operation, the switching device reconnects the capacitor to restore electromagnetic filtering performance. This dynamic switching approach resolves the contradiction between maintaining filtering performance and reducing energy loss.
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 provides a cost-effective and energy-efficient operation of the line filter device by ensuring safe disconnection of capacitors from the power supply, preventing electric shocks and meeting electromagnetic compatibility standards while minimizing energy usage.
Implementation Method 1
the filter capacitors can be discharged immediately using a current sink, for example, an electrical resistor or a load
Implementation Method 2
the filter capacitors can be discharged immediately using a current sink, for example, an electrical resistor or a load
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a mains filter device (2) for a household appliance (1) comprising an input (4) which can be electrically connected to a power supply (5), an output (7) which can be electrically connected to electrical components (8) of the household appliance (1), a filter device (9) for filtering electromagnetic interference, wherein the filter device (9) has at least one capacitor, a switching device (10) and a control device (11) for detecting an electrical connection of the input (4) with the power supply (5) and for controlling the switching device (10) depending on the electrical connection of the input (4) with the power supply (5), wherein the switching device (10) is configured to control an electrical connection between the input (4) and the filter device (9).