AC Motor Inverter Isolation for Brake Torque Interference
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Solution Overview
Problem
Existing control devices for AC rotating machines in electric braking systems fail to prevent abnormalities in one system from interfering with the normal operation of other systems, leading to motor brake torque interference and reduced reliability.
Innovation Solution
A control device with multiple inverters and switching means that detects abnormalities and blocks the circuit between windings and inverters in affected systems, allowing normal control to continue in unaffected systems, thereby preventing interference and maintaining stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the AC rotating machine is driven continuously by the normal system while an abnormality occurs in one system, then the reliability is improved by avoiding abnormality at a specific location, but the reflux current flowing through the current path between the windings and the inverter of the abnormal system may interfere with the control by the normal system
Solution Approach 1:
The patent extracts and removes the harmful reflux current path by opening the circuit between the windings and the inverter in the abnormal system through switching means. This isolation prevents the reflux current from interfering with the normal system's control while allowing the normal system to continue operating, thus resolving the contradiction between maintaining reliability and eliminating harmful interference.
2Stability of the object's composition
If switching elements on the same potential side of respective phases in the inverter of the abnormal system are set to be in the same state as a failure, then the brake torque is made constant regardless of rotation angle and torque pulsation is suppressed, but the motor brake torque generated by the reflux current may still interfere with the control by the normal system
Solution Approach 1:
The patent segments the multi-system AC rotating machine into independent controllable units by using switching means to isolate the abnormal system from the windings. This segmentation allows the abnormal system to maintain stable torque characteristics through controlled switching element states while preventing its reflux current from interfering with the normal system's control, thus resolving the contradiction between torque stability and interference prevention.
Data Source
AI summary
A control device for an AC rotating machine includes: switching control means for controlling inverters and motor relays 15; and abnormality detection means for detecting an abnormality in each system and outputting a result of the detection to the switching control means. When the abnormality detection means detects an abnormality in at least one of the systems, the switching control means causes the motor relay to block a circuit between windings and the inverter in the system in which the abnormality has been detected, and continues normal control in a system other than the system in which the abnormality has been detected.