Electric Vehicle Controller Coupling Disconnection Detection
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Solution Overview
Problem
In electric vehicles driven by multiple induction motors, detecting coupling disconnection without a speed sensor is challenging, as conventional methods rely on detecting rotational speed differences, which is not feasible in speed sensorless control systems.
Innovation Solution
A drive control system that includes a current detector to measure total motor currents and a controller that calculates an estimated torque value based on total current and voltage command values, allowing for coupling disconnection detection through a coupling disconnection detecting unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If speed sensorless control is used to simplify the system, then device complexity is reduced, but the ability to detect coupling disconnection is lost
Solution Approach 1:
The patent replaces the mechanical speed sensor-based detection method with an electrical measurement method using current detectors. By measuring motor currents and calculating torque values through electrical parameters, the system can detect coupling disconnection without requiring mechanical speed sensors, thus simplifying the overall system while maintaining detection capability.
Solution Approach 2:
The patent introduces torque command values and estimated torque values as intermediary parameters to detect coupling disconnection. By comparing the torque command value (electrical signal) with the estimated torque value (calculated from current measurements), the system can indirectly detect coupling status without direct mechanical measurement, enabling detection in sensorless control systems.
2Measurement precision
If conventional torque control is used, then control precision is improved, but the detection of coupling disconnection becomes difficult without speed sensors
Solution Approach 1:
The patent implements a feedback mechanism where the estimated torque value (calculated from measured currents) is compared with the torque command value. This feedback loop allows the controller to continuously monitor the actual torque output against the commanded torque, enabling detection of coupling disconnection while maintaining precise torque control through the sensorless control system.
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
Enables easy detection of coupling disconnection in electric vehicles using speed sensorless control, ensuring continued operation by stopping the affected drive group and preventing unintended large currents.
Implementation Method 1
a current detector that detects a total current that is a sum of motor currents flowing to corresponding ones of the induction motors
Implementation Method 2
an estimated torque value calculated on the basis of the total current and the voltage command value
Data Source
AI summary
A drive control system controls travel of an electric vehicle, the drive control system including a plurality of induction motors, one inverter that drives the plurality of induction motors, and a controller that controls the inverter. The controller includes a coupling disconnection detecting unit that calculates an estimated torque value on the basis of a total current and a voltage command value at the start of the induction motors, and detects disconnection of a coupling provided between the induction motors and a drive mechanism of the electric vehicle on the basis of the estimated torque value calculated and a torque command value.