EV Shift Control Using Learned Motor Speed to Reduce Shift Shock
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Solution Overview
Problem
Existing electrified vehicle technologies face challenges in reducing shift shock during gear changes when the appropriate rotational speed is unknown, particularly in vehicles converted from gasoline vehicles, where the original vehicle's structure affects the required rotational speed.
Innovation Solution
Incorporating a rotational speed sensor and a control circuit that performs a learning process to detect changes in motor rotational speed during shifts, allowing the control circuit to adjust the motor's rotational speed accordingly, thereby reducing shift shock. This involves detecting first and second rotational speeds, controlling the motor's speed during clutch engagement, and storing shift characteristics for gear stage combinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed target rotational speed is set in the control circuit, then shift shock can be reduced in vehicles with known characteristics, but the system cannot adapt to converted vehicles with unknown appropriate rotational speeds
Solution Approach 1:
The control circuit performs a learning process before normal operation to detect the actual rotational speed change during shift changes. This preliminary detection allows the system to establish vehicle-specific characteristics and store them as reference data, enabling future shift shock reduction without requiring pre-programmed rotational speed values for each vehicle type.
Solution Approach 2:
The system uses a rotational speed sensor to detect actual motor rotational speed during shift changes and feeds this information back to the control circuit. The control circuit compares the detected rotational speed with the target rotational speed, calculates the difference, and stores this as learning data. This feedback mechanism enables the system to adapt to converted vehicles by learning their specific characteristics during initial operation.
2Measurement precision
If the control circuit learns rotational speed characteristics during initial shifts, then accurate control is achieved for converted vehicles, but time is required for the learning process
Solution Approach 1:
The learning process is performed during the initial shift change after vehicle assembly or conversion, before normal operation begins. By conducting this measurement preliminary to regular use, the system captures the actual rotational speed characteristics of the specific vehicle configuration without delaying subsequent operational efficiency.
Solution Approach 2:
The system performs self-calibration by automatically detecting and storing its own rotational speed characteristics during the first shift operation. The control circuit uses the rotational speed sensor data from normal operation to learn and store the appropriate rotational speed changes, eliminating the need for external calibration equipment or manual adjustment procedures.
Data Source
AI summary
An electrified vehicle includes a motor, a clutch, a transmission, a rotational speed sensor configured to detect a rotational speed of the motor, and a control circuit configured to control the motor. The control circuit performs: a learning process of detecting a change in the rotational speed of the motor by the rotational speed sensor when the shift change is performed; and a control process of controlling the rotational speed of the motor based on the change in the rotational speed detected in the learning process, when the shift change is performed after the learning process.