Hybrid Vehicle Shift Control for Target Speed and Regenerative Braking
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Solution Overview
Problem
Existing hybrid vehicle systems face challenges in efficiently controlling shifting stages, regenerative braking, and engine brake usage to accurately reach a target vehicle speed, particularly when coasting and managing battery state of charge, leading to suboptimal fuel economy and increased wear on brakes and transmissions.
Innovation Solution
A system and method that utilize a shift controller to determine the start of shift control based on travel environment and state, comparing vehicle speed with a target speed, adjusting shifting stages and regenerative braking amounts based on battery state and capacity, and employing engine brakes when necessary, to optimize vehicle speed matching and reduce unnecessary shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If existing automatic transmission predicts deceleration profile for each shifting stage to allow vehicle to travel with shifting stage most advantageous for fuel economy, then fuel economy is improved, but the vehicle speed may not accurately reach the target vehicle speed
Solution Approach 1:
The system dynamically adjusts the shifting stage based on real-time vehicle speed comparisons with target speed. When vehicle speed exceeds target speed, the controller determines to change to a lower shifting stage to increase deceleration. This dynamic adjustment ensures the vehicle reaches the target speed accurately while maintaining fuel economy through optimized shift timing and stage selection.
Solution Approach 2:
The shift controller continuously monitors vehicle speed and compares it with the target vehicle speed. Based on this feedback, the controller determines whether to maintain the current shifting stage or change to a lower stage. This closed-loop control ensures accurate speed matching while preserving fuel-efficient operation by only downshifting when necessary.
2Measurement precision
If the system changes shifting stage to lower stage when regenerative braking amount is equal to or greater than maximum regenerative braking amount, then vehicle speed control accuracy is improved, but the complexity of control system increases
Solution Approach 1:
The control system segments the decision-making process into distinct evaluation steps: first comparing battery state of charge with reference SOC, then comparing regenerative braking amount with maximum regenerative braking amount when SOC is insufficient. This segmented approach manages complexity by breaking down the control logic into manageable, sequential decisions while achieving accurate speed control.
Solution Approach 2:
The system changes the shifting stage parameter based on multiple parameters including battery state of charge, regenerative braking amount, and vehicle speed. By adjusting the shifting stage in response to these parameter changes, the system achieves accurate speed control without requiring overly complex control mechanisms, as each parameter change triggers a predetermined response.
3Loss of energy
If the system increases motor regeneration amount when regenerative braking amount is less than maximum regenerative braking amount, then energy recovery is improved, but the control complexity increases
Solution Approach 1:
The system adjusts the motor regeneration amount parameter based on the battery state of charge and current regenerative braking amount. When SOC is below reference SOC and regenerative braking is below maximum, the controller increases regeneration amount by a specific tuned value. This parameter adjustment approach improves energy recovery while keeping control complexity manageable through clear conditional logic.
4Measurement precision
If the system performs shift control using engine brake when battery state of charge is equal to or greater than reference SOC, then vehicle speed control is improved, but fuel consumption increases
Solution Approach 1:
The system dynamically selects the deceleration method based on battery state of charge. When SOC is sufficient (equal to or greater than reference SOC), the controller uses engine brake for reliable vehicle speed control. When SOC is insufficient, the system dynamically switches to regenerative braking. This dynamic selection achieves accurate speed control while minimizing fuel consumption by using the most efficient available method in each situation.
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
This approach allows for precise matching of vehicle speed to targets, reducing fuel consumption, minimizing shifts, and extending brake and transmission durability by optimizing energy regeneration and shifting strategies.
Implementation Method 1
a battery of the vehicle
Implementation Method 2
motor capacity and a battery capacity
Data Source
AI summary
A system and a method for controlling shifting stage of a hybrid vehicle may include a speed detecting device that detects a vehicle speed, an automatic transmission that changes a shifting stage of the vehicle, and a shift controller connected to the speed detecting device and the automatic transmission. The shift controller is configured to determine a start of shift control based on a travel environment and a travel state of the vehicle, compares the vehicle speed with a target vehicle speed when the start of the shift control is determined, and performs the shift control based on a state of charge of a battery of the vehicle and a regenerative braking amount of the vehicle when the shift controller concludes that the vehicle speed exceeds the target vehicle speed.