EV Drive Control for Motor Angle Estimation Under Sensor Faults
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Solution Overview
Problem
Existing drive control systems for electric vehicles face challenges in achieving high accuracy in estimating the rotation angle of a traveling motor, especially at low rotation speeds, leading to biased torque and a strange feeling for passengers when the rotation angle sensor is in an abnormal state.
Innovation Solution
A drive control apparatus that includes a controller capable of estimating the rotation angle using a first estimation method when the rotation speed is above a threshold and controlling the engine, transmission, and output clutch differently when the rotation angle sensor is abnormal, maintaining the rotation speed at or above the threshold to ensure accurate estimation and reduce passenger discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a first estimation method is used to estimate rotation angle, then estimation accuracy is improved, but the method can only be executed when rotation speed is at threshold or higher
Solution Approach 1:
The system dynamically switches between different estimation methods based on rotation speed conditions. When rotation speed is at threshold or higher, the first estimation method is used for high accuracy. When rotation speed drops below threshold, the system transitions to the second estimation method, ensuring continuous operational adaptability across all speed ranges.
Solution Approach 2:
The system changes the estimation method parameter based on rotation speed threshold conditions. By monitoring rotation speed and switching estimation algorithms accordingly, the system optimizes accuracy where possible while maintaining functionality across the full operating range.
2Adaptability or versatility
If the rotation angle sensor is in an abnormal state and low rotation speed control is applied, then the system can operate at low speeds, but estimation accuracy deteriorates and torque becomes biased
Solution Approach 1:
The system uses a secondary, less accurate estimation method (second estimation method) as a fallback when the primary high-accuracy method cannot be used. This secondary method sacrifices some accuracy to maintain operational capability when rotation speed falls below the threshold.
Solution Approach 2:
The control system dynamically adapts by switching estimation methods based on real-time rotation speed monitoring, ensuring the vehicle can operate across all speed ranges while optimizing accuracy where conditions permit.
3Adaptability or versatility
If the controller switches between first and second sensorless control methods, then operation is maintained across all speeds, but system complexity increases
Solution Approach 1:
The controller implements dynamic switching between two sensorless control methods based on rotation speed threshold detection. This dynamic adaptation enables continuous operation across all speed ranges while managing complexity through condition-based logic.
Solution Approach 2:
The system uses feedback from rotation speed monitoring to determine which estimation method to apply. By continuously monitoring speed and switching methods based on threshold conditions, the system maintains operational continuity while using straightforward conditional logic to manage complexity.
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
The system extends the period for which the rotation speed is maintained at the threshold, allowing for highly accurate estimation and control of the traveling motor, thereby reducing the feeling of strangeness for passengers even when the rotation angle sensor is abnormal.
Implementation Method 1
In the first sensorless control, the controller performs a drive control of the motor on the basis of a result of estimation of a rotation angle using an induced voltage of the motor.
Implementation Method 2
In the second sensorless control, the controller performs the drive control of the motor on the basis of a result of estimation of the rotation angle using saliency of a rotor.
Implementation Method 3
The controller is configured to control, in a case where the rotation angle sensor is in an abnormal state and a specific driving state is present, one or more of the engine, the transmission, and the output clutch in a manner different from a manner under a control in a case where the rotation angle sensor is in a normal state, and thereby maintain the rotation speed of the traveling motor at the threshold or higher.
Data Source
AI summary
A drive control apparatus for an electric vehicle includes a controller that controls an engine, a traveling motor, a transmission, and an output clutch. The controller estimates the rotation angle of the motor by a first estimation method and controls the motor on the basis of the estimated angle. The estimation method is executable when the rotation speed of the motor is a threshold or higher. When a rotation angle sensor for the motor is in an abnormal state and a specific driving state is present, the controller controls one or more of the engine, the transmission, and the output clutch differently from when the sensor is in a normal state, and thereby maintains the rotation speed at the threshold or higher. The specific driving state is a state in which the rotation speed is lower than the threshold under the control when the sensor is in the normal state.