Disconnection Detection in Rotating Electrical Machines
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing disconnection detecting devices for rotating electrical machines face challenges in promptly detecting disconnections, especially at higher rotation speeds, due to the need for longer detection times to avoid erroneous disconnections, which limits the range of prompt detection.
Innovation Solution
A disconnection detecting device that uses a CPU to judge disconnection based on the absolute value of the line current and its rate of change, allowing for earlier detection by differentiating between normal operation and actual disconnection through specific current and rate conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the specified amount of time is set to be relatively long to prevent erroneous disconnection detection in the low-speed range, then the reliability of disconnection detection is improved, but the detection time increases in the high-speed range
Solution Approach 1:
The patent applies dynamics by making the specified amount of time variable rather than fixed. The control device dynamically adjusts the specified amount of time based on the rotation speed of the rotating electrical machine. At low rotation speeds, a longer specified amount of time is used to prevent erroneous detection, while at high rotation speeds, a shorter specified amount of time is used to enable prompt detection. This dynamic adjustment resolves the contradiction between reliability and detection time across different operating conditions.
Solution Approach 2:
The patent changes the parameter of the specified amount of time based on the rotation speed parameter. By establishing a relationship between rotation speed and the specified amount of time, the system adapts the detection criteria to match the operational characteristics at different speeds. This parameter change allows the system to maintain high detection reliability at low speeds while achieving fast detection响应 at high speeds, thereby resolving the technical contradiction.
2Loss of time
If the specified amount of time is set to be short to enable prompt disconnection detection at high speed, then the detection time is reduced, but erroneous disconnection detection may occur in the low-speed range
Solution Approach 1:
The system dynamically adjusts the specified amount of time based on rotation speed. When the machine operates at high speed, a short specified amount of time is applied to enable prompt detection. When the machine operates at low speed, the system automatically extends the specified amount of time to prevent erroneous detection. This dynamic adaptation eliminates the need to choose between fast detection and reliability, as both are achieved under appropriate operating conditions.
Solution Approach 2:
The patent implements parameter changes by making the specified amount of time dependent on the rotation speed parameter. The control device monitors rotation speed and adjusts the time threshold accordingly. This parameter change strategy allows the system to use short time thresholds at high speeds for fast detection while using long time thresholds at low speeds to ensure reliability, thereby resolving the contradiction between detection speed and accuracy.
Data Source
AI summary
A disconnection detecting device that can be applied to a control system of a motor-generator is provided. A disconnection detecting section judges whether logical conjunction (i.e. AND operation) of a condition that both current sensors are operating normally and a condition that the designated torque is equal to or more than a specified torque is true or not. In the event that the disconnection detecting section has determined YES, the disconnection detecting section judges whether the logical conjunction of a condition that the absolute value of the phase current is equal to or less than a specified current (>0) and a condition that the absolute value of the current change rate is equal to or less than a specified value (>0) is true or not. In the event that the disconnection detecting section has determined YES, the disconnection detecting section has determines that the disconnection has occurred.