Electric Motor Controller Dual Diagnosis Fault Isolation
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Solution Overview
Problem
In electric motors with multiple energization systems, a short-circuit in one system can cause overcurrent and abnormality in another normal system, leading to unintended stopping of the inverter and abnormal energization control.
Innovation Solution
A controller with diagnosis processing units that detect abnormalities in energization systems and manage energization control to prevent erroneous stopping of normal systems by executing first and second diagnosis processing to identify and isolate issues, allowing for controlled restart of energization systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the controller stops energization control over one energization system when an abnormality is detected, then the abnormality is isolated, but the electric motor cannot be driven properly since one system is non-operational
Solution Approach 1:
The controller extracts and isolates only the confirmed abnormal energization system from operation while maintaining operation of normal systems. By using the two-stage diagnosis process to accurately identify only the truly abnormal system, the controller extracts the problematic component without unnecessarily taking out normal systems, thereby maintaining motor productivity.
Solution Approach 2:
The controller changes the operational parameter of the abnormal energization system from 'operational' to 'non-operational' only after confirmed abnormality detection. This parameter change is applied selectively based on the two-stage diagnosis results, ensuring that only the necessary system is taken offline while others continue to drive the motor.
2Speed
If the controller uses simple abnormality detection, then the response speed is fast, but loop currents from short-circuits cause false abnormality detection in normal systems
Solution Approach 1:
The controller implements periodic action by executing the two-stage diagnosis process at regular intervals. The first diagnosis processing provides rapid initial detection, and the second diagnosis processing provides periodic confirmation. This periodic two-stage approach maintains fast response while ensuring accurate detection by repeatedly verifying abnormalities before taking action.
Data Source
AI summary
To provide a controller and a control method for an electric motor including plural energization systems each composed of an inverter and coils corresponding to plural phases. The controller performs first diagnosis processing for detecting an abnormality in each system under energization control, and second diagnosis processing for detecting an abnormality in each system not under energization control. When the first diagnosis processing detects an abnormality in one system and the second diagnosis processing detects no abnormality in the one system or when the first diagnosis processing detects an abnormality in one system to thereby stop energization control over the one system and in such a state, an abnormality is detected in another system, the energization control over the one system is restarted to drive the electric motor. It is therefore possible to avoid stopping output from a normal system when some of the systems have an abnormality.