Power Conversion Circuit With Relay-Switched Noise Filtering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional air conditioners face issues with reactive power consumption due to noise filters and lack of inrush-current limiting in power factor correction circuits, leading to increased costs and board footprint, as well as potential diode failure from inrush currents.
Innovation Solution
A power conversion device with an AC-DC converter, noise reducers, an inrush-current inhibition circuit, and relays that prevent reactive current flow during standby and inhibit inrush currents, using wide band-gap semiconductors to reduce size and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a noise filter with across-the-line capacitor is mounted on the outdoor unit, then noise removal is achieved, but reactive current flows at all times and reactive power cannot be eliminated during standby
Solution Approach 1:
The patent introduces a power feeding relay that opens during standby period to disconnect power supply to the across-the-line capacitor before reactive power consumption occurs, while maintaining the noise filter's noise removal capability when needed
Solution Approach 2:
The patent makes the power supply state dynamic by using a power feeding relay to switch between connected and disconnected states, allowing the across-the-line capacitor to be powered only when needed for noise filtration rather than continuously
2Stability of the object's composition
If the smoothing capacitor capacitance is increased to maintain stabilized operation of the switching power source, then operation stability is improved, but board footprint and cost increase
Solution Approach 1:
The patent changes the operating parameters of the switching power source by using wide band-gap semiconductor devices with higher breakdown voltages and lower on-resistances, allowing reduced capacitor capacitance while maintaining stable operation
Solution Approach 2:
The patent employs thin-film semiconductor structures with wide band-gap materials that enable higher efficiency power conversion, reducing the energy storage requirements and allowing smaller capacitor sizes
3Device complexity
If an inrush-current limiting resistor is not provided in the power factor correction circuit, then circuit simplicity is maintained, but inrush current flows through diodes and reactors causing potential diode failure
Solution Approach 1:
The patent introduces an inrush-current limiting resistor that is temporarily connected during power-on to limit inrush current before being bypassed, preventing diode failure while maintaining circuit simplicity during normal operation
Solution Approach 2:
The patent uses an inrush-current limiting resistor as a temporary intermediary element that protects the circuit during startup and is then removed from the current path, allowing the main circuit to remain simple without compromising reliability
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 reduces reactive power consumption, inhibits inrush currents, and prevents diode failure, achieving power savings, size reduction, and improved efficiency in air conditioner operation.
Implementation Method 1
an alternating current-direct current converter to convert an alternating-current voltage supplied from an alternating-current power source to generate a direct-current voltage
Implementation Method 2
a direct-current-voltage smoother to smooth a direct-current voltage output from the alternating current-direct current converter
Implementation Method 3
a first noise reducer having inductive reactance; a second noise reducer having capacitive reactance
Implementation Method 4
a first noise reducer having inductive reactance; a second noise reducer having capacitive reactance
Data Source
AI summary
A power conversion device includes a first AC-DC conversion section generating DC voltage applied to a compressor drive section, a first DC-voltage smoothing section smoothing DC voltage, a first noise reduction section having one end connected to an AC power source and the other end connected to the first AC-DC conversion section, a second noise reduction section disposed between the first noise reduction section and the first AC-DC conversion section, an inrush-current inhibition circuit (a first inrush-current inhibition resistor and a rectifier diode) connected in parallel with the second noise reduction section and the first AC-DC conversion section for inhibiting inrush current from flowing to the first DC-voltage smoothing section, a first AC power-source relay opening/closing a power supply path to the inrush-current inhibition circuit, and a second AC power-source relay opening/closing a power supply path to the second noise reduction section.