Converter Device Dual-Filter Circuit for Open-Phase Detection
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Solution Overview
Problem
Conventional power supply devices face difficulties in detecting an open-phase in booster circuits, particularly when using reactors with small inductance values, due to the long time constant of RC filters used for current detection.
Innovation Solution
A converter device is designed with a rectifier circuit, a booster circuit comprising multiple reactors and switching elements, a smoothing capacitor, a current detection circuit, a first filter circuit with a longer time constant for normal operations, and a second filter circuit with a shorter time constant for open-phase detection, along with a control unit to manage the switching elements and detect open-phases accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a single RC filter with a long time constant is used for current detection, then noise filtering is improved, but open-phase detection capability deteriorates
Solution Approach 1:
The patent divides the single filter function into two separate filter circuits with different time constants. The first filter circuit uses a longer time constant for noise filtering during normal operation, while the second filter circuit uses a shorter time constant for rapid open-phase detection. This segmentation allows each filter to be optimized for its specific function without compromising the other.
Solution Approach 2:
The patent dynamically switches between different filter circuits based on operational conditions. During normal operation, the first filter circuit with longer time constant is used for noise filtering. When open-phase detection is needed, the system switches to the second filter circuit with shorter time constant, enabling rapid response to phase loss conditions.
2Object-generated harmful factors
If a single RC filter with a long time constant is used for current detection, then noise filtering is improved, but detection response speed deteriorates
Solution Approach 1:
The patent segments the filtering function into two distinct filter circuits with different time constants. The first filter circuit provides strong noise filtering with a longer time constant, while the second filter circuit provides fast response with a shorter time constant. This segmentation enables the system to achieve both noise filtering and fast detection response by selecting the appropriate filter circuit based on operational needs.
Solution Approach 2:
The system dynamically selects which filter circuit to use based on the operational state. During normal stable operation, the first filter circuit with longer time constant is used for optimal noise filtering. When rapid detection is required (such as during startup or fault conditions), the system switches to the second filter circuit with shorter time constant, achieving fast response speed without sacrificing noise filtering capability 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 converter device effectively detects open-phases in booster circuits regardless of reactor values, preventing damage and ensuring continuous operation of devices like air conditioners and refrigerators while improving energy efficiency.
Implementation Method 1
a rectifier circuit to rectify an AC voltage output from an AC power supply
Implementation Method 2
a booster circuit including a plurality of reactors, a plurality of switching elements, and a plurality of backflow prevention elements to boost an output voltage of the rectifier circuit
Implementation Method 3
a smoothing capacitor to smooth an output voltage of the booster circuit
Implementation Method 4
a first filter circuit having a first filter time constant; a second filter circuit having a second filter time constant shorter than the first filter time constant
Data Source
AI summary
A converter device includes a rectifier circuit to rectify an AC voltage output from an AC power supply, a booster circuit including a plurality of reactors, a plurality of switching elements, and a plurality of backflow prevention elements to boost an output voltage of the rectifier circuit, a smoothing capacitor to smooth an output voltage of the booster circuit, a bus-current detection circuit to detect a value of a current that flows between the rectifier circuit and the booster circuit, a first filter circuit having a first filter time constant, a second filter circuit having a second filter time constant shorter than the first filter time constant, and a control unit to control an operation of the switching elements as a current value detected by the bus-current detection circuit is input to the control unit via the first filter circuit and the second filter circuit.