Electric Motor Controller Short-Circuit Isolation and Output Continuity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In electric motors with multiple energization systems, short-circuits can lead to erroneous detection of overcurrent or abnormal energization, causing the normal energization system to stop outputting, due to reduced apparent inductance and overshoot in energization current.
Innovation Solution
A controller that detects short-circuits in each energization system and adjusts control parameters for the unaffected system to prevent erroneous operation, executing specific diagnosis processes to identify and manage abnormalities, thereby maintaining normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a short-circuit occurs in one energization system and all switching elements are turned OFF, then the short-circuit is isolated, but loop current is generated that cancels out magnetic flux from normal energization systems
Solution Approach 1:
The control unit applies preliminary anti-action by detecting the short-circuit state and proactively adjusting control parameters of normal energization systems before loop current can cause harmful effects. The controller modifies voltage commands or current limits in advance to compensate for the magnetic flux cancellation effect, preventing the harmful outcome rather than reacting after it occurs.
2Reliability
If loop current cancels out magnetic flux from normal energization systems, then apparent inductance reduces, but this causes overshoot in energization current
Solution Approach 1:
The control unit changes control parameters dynamically based on the detected short-circuit state. It adjusts voltage command values, current limits, or PWM duty cycles for normal energization systems to compensate for the reduced apparent inductance. This parameter adaptation prevents current overshoot while maintaining accurate fault detection capability.
3Measurement precision
If current overshoot occurs in normal energization systems, then false overcurrent detection may happen, but this causes erroneous stopping of normal output
Solution Approach 1:
The control unit implements feedback by continuously monitoring current values in normal energization systems and comparing them against dynamically adjusted thresholds. When a short-circuit is detected in another system, the controller modifies the feedback threshold or evaluation criteria to account for the expected current behavior changes, preventing false overcurrent detection while maintaining genuine fault protection.
4Reliability
If control parameters are adjusted to prevent overshoot, then false fault detection is avoided, but responsiveness to output control is reduced
Solution Approach 1:
The control unit applies dynamics by making control parameters adaptive rather than fixed. It dynamically adjusts voltage commands, current limits, or response thresholds based on the operational state and detected faults. This allows the system to maintain high responsiveness during normal operation while automatically adapting to prevent overshoot and false detections when short-circuits are present, achieving both reliability and speed through state-dependent parameter optimization.
Data Source
AI summary
To provide controller and control method for an electric motor including plural energization systems composed of an inverter and coils corresponding to plural phases. According to the present invention, if any abnormality is detected in one energization system being energized through first diagnosis processing, second diagnosis processing is executed on the energization system having the abnormality detected, which is switched to an unenergized state. Then, if the second diagnosis processing reveals occurrence of a short-circuit, a control gain of a normal energization system is lowered. In addition, a threshold used in the first diagnosis processing on the normal energization system is changed so as to make it difficult to detect an abnormality, hereby keeping the energization control on the normal energization system. Hence, if a short-circuit occurs in at least one of the energization systems, it is possible to avoid stopping the output from the normal energization system.