Electric Motor Torque Transition Control for Smooth Vehicle Deceleration
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Solution Overview
Problem
Existing vehicle control systems for electric motor-powered automobiles experience deteriorated responsiveness and early deceleration impact when drivers perform deceleration operations, as the torque rate change is not differentiated between acceleration and deceleration regions, leading to compromised ride comfort and drivability.
Innovation Solution
A vehicle control device that adjusts the torque rate of the electric motor, making it smaller on the deceleration side than on the acceleration side, and smoothly transitions near zero torque, allowing for optimized torque rate control to reduce responsiveness deterioration and deceleration impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the torque rate is increased to improve responsiveness during deceleration, then the driver feels better responsiveness, but impact occurs due to early rise of deceleration
Solution Approach 1:
The patent applies local quality by differentiating the torque rate control between two distinct regions: the positive torque region (acceleration) and the negative torque region (deceleration). Specifically, a first torque rate is applied in the positive region while a second, smaller torque rate is applied in the negative region. This localized differentiation allows the system to optimize responsiveness where needed while minimizing harmful impacts during deceleration, rather than applying a uniform torque rate across all operating conditions.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the torque rate parameter based on the current torque region. The control unit changes the torque rate from the first value (higher) when torque is positive to the second value (lower) when torque is negative. This parameter adaptation allows the system to balance responsiveness and impact reduction by modifying the torque change rate according to the operational context.
2Object-affected harmful factors
If the torque rate is decreased to reduce impact during deceleration, then impact is reduced, but responsiveness deteriorates such that the driver still feels acceleration
Solution Approach 1:
The patent resolves this contradiction by applying different torque rate characteristics to different operational regions. In the positive torque region, a higher torque rate maintains responsive acceleration feel, while in the negative torque region, a lower torque rate reduces deceleration impact. This spatial differentiation of control parameters allows simultaneous optimization of both responsiveness and impact reduction without compromise.
Solution Approach 2:
The system dynamically adapts the torque rate based on the real-time torque sign and magnitude. The control unit continuously monitors the torque region and adjusts the torque rate parameter accordingly, transitioning between the first torque rate (for responsiveness) and the second torque rate (for impact reduction). This dynamic adaptation enables the system to maintain optimal performance across varying operational conditions.
Data Source
AI summary
A vehicle control device configured to control an automobile traveling with an electric motor as a power source includes a control unit configured to control the electric motor. When a torque of the electric motor decreases from a region on a positive side of the torque in a direction in which the torque of the electric motor accelerates the automobile to a region on a negative side of the torque in a direction in which the torque of the electric motor decelerates the automobile, the control unit controls the electric motor so that a torque rate in the region on the negative side of the torque is smaller than a torque rate in the region on the positive side of the torque, the torque rate being a change rate of the torque per unit time.