Hybrid Drive Motor Control via Transmission Error Maps
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Solution Overview
Problem
Hybrid vehicles face limitations in precise torque control and driving performance when the rotor position sensor malfunctions, as sensorless control methods offer lower precision, leading to potential vehicle shutdowns during fail-safe driving.
Innovation Solution
A method and system that directly connect a drive motor to a transmission via a clutch, using an error map to determine the transmission stage, allowing the drive motor to operate outside excessive error areas by adjusting torque and speed commands based on estimated rotor position values, ensuring precise control even without a functional rotor position sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensorless control method is used when rotor position sensor malfunctions, then fail-safe driving is enabled, but rotor position detection precision deteriorates
Solution Approach 1:
The transmission acts as an intermediary mechanical system to compensate for the imprecise sensorless control. By selecting appropriate transmission stages, the system mediates between the imprecise motor control and the required precise vehicle torque control, enabling fail-safe operation while maintaining acceptable performance through mechanical assistance rather than relying solely on imprecise electrical control
Solution Approach 2:
The system changes operating parameters by selecting different transmission stages based on the current operating conditions and error maps. When sensorless control is activated, the controller references pre-stored error maps to determine optimal transmission stage selections, thereby adjusting the mechanical transmission ratio to compensate for control precision limitations and maintain reliable vehicle operation
2Reliability
If sensorless control method is used, then vehicle can continue operating without rotor position sensor, but torque control precision deteriorates
Solution Approach 1:
The transmission serves as a mechanical intermediary that compensates for the precision loss in sensorless torque control. By strategically selecting transmission stages based on error map data, the system uses mechanical gear ratios to fine-tune the actual torque output, thereby achieving acceptable torque control precision even when the electrical control precision is degraded due to sensorless operation
Solution Approach 2:
The system performs preliminary action by pre-storing error maps that characterize the relationship between transmission stage selections and torque control accuracy under sensorless conditions. These pre-computed error maps enable the controller to proactively select optimal transmission stages before torque control errors become problematic, maintaining continuous operation with acceptable precision
3Manufacturing precision
If transmission stage is adjusted to compensate for sensorless control errors, then torque control precision is improved, but device complexity increases
Solution Approach 1:
The system implements self-service by using the existing transmission mechanism to compensate for control precision issues without requiring additional dedicated precision control hardware. The error maps and control logic utilize already-present components (transmission stages, existing sensors for other parameters) to achieve the compensation, thereby improving torque control precision while avoiding increased device complexity
Solution Approach 2:
The transmission system performs multiple functions: its primary function of speed and torque multiplication is augmented with a secondary function of precision compensation under sensorless conditions. By selecting appropriate stages, the transmission universally serves both its conventional power transmission role and the additional role of fine-tuning torque control accuracy, eliminating the need for separate compensation mechanisms
Data Source
AI summary
A method and a system for driving a hybrid vehicle are provided for determining whether the hybrid vehicle is driven in a sensorless control mode or not by estimating a rotor position value based on electric current and voltage of a drive motor. Such a hybrid vehicle is capable of controlling the drive motor to operate by using a transmission in an area in which precise torque control of the drive motor is possible, without using information detected by a stator position sensor provided in the drive motor of the hybrid vehicle. Accordingly, a drive motor control precision is improved when a rotor position sensor does not operate normally, thereby preventing a vehicle shutdown from occurring.