High Voltage Circuit Abnormality Detection via Square Wave Pulse
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Solution Overview
Problem
Conventional methods for detecting ground faults in high-voltage circuits of electric vehicles cannot detect loosening of fastening sections that mechanically fix electric wires or terminals, leading to potential electrical issues.
Innovation Solution
An abnormality detecting apparatus and method that uses a first capacitor connected to the positive terminal of a direct-current power source and a series connection circuit with a switch between the inverter circuit and ground, employing a square wave pulse signal to measure voltage differences at different phases to detect ground faults and loosening of fastening sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional ground fault detection methods are used, then ground faults can be detected, but loosening of fastening sections cannot be detected
Solution Approach 1:
The patent applies dynamics by making the switch means changeable between opened and closed states. This dynamic configuration allows the detection system to adapt between detecting ground faults (switch opened) and detecting loosening of fastening sections (switch closed), thereby expanding detection versatility while maintaining detection precision through the same voltage measurement mechanism
Solution Approach 2:
The patent changes the electrical parameter configuration by switching the switch means between opened and closed states. This parameter change enables the same detection apparatus to measure different electrical characteristics: insulation resistance when opened, and voltage division characteristics when closed, thus detecting both ground faults and fastening section loosening
2Device complexity
If a single detection method is used, then the detection system remains simple, but both ground faults and loosening cannot be detected
Solution Approach 1:
The patent implements multi-functionality by enabling the same detection apparatus to perform two distinct detection functions: ground fault detection and loosening detection. The switch means acts as a function selector, allowing one apparatus to universally detect multiple types of abnormalities, thereby improving reliability without proportionally increasing device complexity
Solution Approach 2:
The patent applies preliminary action by detecting loosening of fastening sections before complete disconnection occurs. The voltage measurement in the closed switch state can identify loosening conditions early, allowing preventive maintenance before the connection fails completely, thus enhancing system 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
Accurately detects both ground faults and loosening of fastening sections, enabling early recognition and maintenance before complete disconnection, thereby ensuring reliable operation of high-voltage circuits.
Implementation Method 1
a first capacitor whose one end is connected to a positive terminal of a direct-current power source, and whose other end is designated as a measuring point, is provided; a square wave pulse signal is outputted to the measuring point
Implementation Method 2
a first voltage occurring at the measuring point is measured at a time when a phase of the square wave pulse signal becomes a first phase; a second voltage occurring at the measuring point is measured at a time when the phase of the square wave pulse signal becomes a second phase different from the first phase
Data Source
Figure 1
Figure 2
Figure 3~4(c)
AI summary
Disclosed are abnormality detecting apparatus and method for a high-voltage circuit (A), in which: a square wave pulse is outputted to a measuring point (p1) with a switch (SW1) set off, the switch (SW1) provided between an inverter circuit (2) and the ground, a difference voltage (Vp-p) between a voltage (Vh) detected at a phase of T/2 and a voltage (V1) detected at a phase of T is obtained, the occurrence of a ground fault is detected based on the size of the difference voltage (Vp-p); and the square wave pulse is outputted to the measuring point (p1) with the switch (SW1) set on, and it is judged that a loosening of a fastening section (p2) occurs when the difference voltage (Vp-p) exceeds a reference voltage (Vref2).