N-Phase Open Phase Detection in Three-Phase Power Supply
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Solution Overview
Problem
In a three-phase four-wire power supply system, existing technologies fail to reliably detect an open phase of the N-phase when a power conversion module converts output power using only the R-phase, S-phase, and T-phase, leading to continuous operation of the power conversion module despite a lack of power supply to the main control unit.
Innovation Solution
A power supply system with an N-phase open phase detection unit connected to the N-phase to detect open phases, allowing for reliable detection of open and reverse phases by monitoring the voltage between the N-phase and other phases, ensuring the power conversion module stops operation when an open phase occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a power conversion module uses only R-phase, S-phase, and T-phase from a three-phase four-wire power supply, then the noise filter structure is simplified, but the ability to detect N-phase open phase is lost
Solution Approach 1:
The patent introduces an N-phase open phase detection unit as an intermediary component that specifically monitors the N-phase wire. This detection unit acts as a mediator between the simplified power conversion module (which doesn't use N-phase) and the power supply system, enabling open phase detection without requiring the power conversion module to be connected to all four wires. The detection unit includes voltage detection circuitry that measures voltage between the N-phase and other phases to determine open phase conditions.
2Quantity of substance
If the power conversion module is disconnected from the N-phase, then the filter capacitor count is reduced, but the main control power generation unit cannot operate
Solution Approach 1:
The patent segments the power supply system into distinct functional modules: a power conversion module that handles R-phase, S-phase, and T-phase for motor control, and a separate main control power generation unit that handles N-phase and one other phase for generating control power. This segmentation allows each module to be optimized independently - the power conversion module uses fewer capacitors while the control power generation unit ensures proper operation and detection.
3Device complexity
If existing detection methods are used, then the system structure is simple, but open phase detection is unreliable when power conversion module and main control power generation unit coexist
Solution Approach 1:
The patent applies local quality by implementing a specialized detection function specifically for the N-phase open phase condition. Rather than using a general-purpose detection method, the system incorporates a dedicated N-phase open phase detection unit with specific detection logic tailored to identify N-phase failures. This localized detection approach ensures high accuracy for the specific problem of N-phase open phase detection in the coexisting module architecture.
Data Source
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AI summary
A power converter (1) includes: a three phase detection unit (14) that detects an open phase and a reverse phase of each phase based on a phase difference between two phases of three-phase three wires 3 having an R-phase, an S-phase, and a T-phase; a module control power supply unit (13) that generates drive control power for driving a power conversion module from the three-phase three wires 3; and an N-phase open phase detection unit (15) that detects an open phase of an N-phase by using the drive control power.