Hybrid Motor Reverse Shift Control via Zero-Torque Preliminary Action
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Solution Overview
Problem
Hybrid vehicles driven only by a motor face challenges in achieving responsive reverse gear shifting due to large rotational inertia, leading to user dissatisfaction and increased specification requirements for the transmission, particularly on uphill roads.
Innovation Solution
A backward driving control method that determines the motor's rotation speed and torque to implement reverse gear using a transmission with reduced specification, employing zero-torque control and directional changes to enhance shifting responsiveness, allowing the motor to switch to reverse direction efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the motor is configured with large capacity to drive the hybrid vehicle, then the vehicle can be driven only by the motor, but the rotational inertia of the motor becomes relatively large, causing shift responsiveness to be lowered when reversing
Solution Approach 1:
The control device performs preliminary action by controlling the motor torque to zero before the motor rotates in the reverse direction. This preliminary torque reduction prepares the motor for faster directional change, overcoming the sluggish response caused by large rotational inertia while maintaining the motor's high capacity for vehicle propulsion.
2Device complexity
If the reverse gear stage is implemented by rotating the motor in the reverse direction, then the transmission can implement reverse gear without using the backward driving implementation device, but the large rotational inertia of the motor causes the shift operation to have relatively long response time
Solution Approach 1:
Before the motor rotates in reverse to implement the reverse gear stage, the control device preliminarily controls the motor torque to zero. This preliminary action reduces the motor's rotational inertia effect, enabling faster shift response time while maintaining the simplified transmission structure that uses motor reverse rotation instead of a dedicated backward driving implementation device.
3Reliability
If the transmission is configured with high specification to satisfy backward driving performance on uphill road, then the performance required for backward driving on uphill road is satisfied, but the number of friction members of clutches or brakes increases and line pressure of hydraulic pressure control device must be set relatively high
Solution Approach 1:
The control device performs preliminary torque control to zero before reverse rotation, which reduces the mechanical demands on the transmission system. This allows the transmission to use fewer friction members and lower hydraulic pressure while still achieving reliable backward driving performance on uphill roads, as the preliminary torque control prevents excessive inertial loads during shifting.
4Ease of operation
If zero-torque control is performed to decrease the torque of the motor to zero before changing rotation direction, then the motor can switch to reverse direction, but the shift operation has relatively long response time due to large rotational inertia
Solution Approach 1:
The control device performs preliminary torque reduction to zero, which is necessary for directional switching capability. However, this preliminary action is optimized in duration and magnitude to minimize the time penalty, balancing the need for complete torque reduction with the desire for fast shift response.
Solution Approach 2:
The control device dynamically adjusts the torque control strategy based on real-time motor state and driving conditions. By making the torque reduction process dynamic rather than fixed, the system achieves directional switching capability while minimizing shift operation time, adapting the preliminary action to the specific operational context.
Data Source
AI summary
A backward driving control method for a hybrid vehicle may include a condition determination operation of, when the driver performs a shifting to a reverse gear stage, determining whether the rotation speed of a motor in the forward direction exceeds a reference speed and whether the torque of the motor exceeds a reference torque, a first backward driving operation of, when the rotation speed of the motor exceeds the predetermined reference speed and when the torque of the motor exceeds the predetermined reference torque, implementing the reverse gear stage using a backward driving implementation device of the transmission, a zero-torque control operation of decreasing the torque of the motor to zero, a forward driving conversion operation of shifting the transmission to a forward gear stage, and a second backward driving operation of driving the motor in the reverse direction to implement the reverse gear stage.