Hybrid Vehicle Mode Switching Synchronization Control
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Solution Overview
Problem
Hybrid vehicles face challenges in smoothly switching from series-parallel mode to series mode due to synchronization issues between the rotation speeds of the clutch and engine, leading to delayed switching and potential shocks, as well as suboptimal fuel consumption in both modes.
Innovation Solution
A hybrid vehicle configuration with a power transmission unit, differential unit, and controller that synchronizes the rotation speeds of the first and second rotary electric machines with the engine, allowing the clutch to engage smoothly by placing the power transmission unit in a neutral state and controlling the machines to synchronize their speeds before switching modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the clutch is engaged to directly couple the first motor generator to the engine for switching from series-parallel mode to series mode, then the power transmission state changes from transmittable to isolated, but the rotation speed of the clutch elements may not be synchronized, causing delayed switching
Solution Approach 1:
The control device performs preliminary synchronization control before clutch engagement. It adjusts the rotation speed of either the engine or the first motor generator to match the other's speed, ensuring that when the clutch engages, both sides are already synchronized. This preliminary action prevents switching delay and ensures smooth mode transition.
2Object-affected harmful factors
If the engine is completely isolated from the gear mechanism in series hybrid system, then tooth contact noise does not occur, but the entire torque must be converted to electric power and back, resulting in inferior fuel consumption
Solution Approach 1:
The system dynamically switches between series mode (engine isolated from gear mechanism) and series-parallel mode (engine connected to gear mechanism). The control device selects the appropriate mode based on vehicle operating conditions, allowing the engine to be sometimes isolated to avoid noise and sometimes connected to improve fuel efficiency, thus adapting to different situations optimally.
3Ease of operation
If the power transmission unit is placed in neutral state before clutch engagement, then the clutch can engage smoothly, but the rotation speed synchronization must be achieved through active control of the rotary electric machines
Solution Approach 1:
The control device continuously monitors the rotation speeds of the engine and the first motor generator, and adjusts the operation of the rotary electric machines based on feedback from speed sensors. This closed-loop control ensures that the rotation speeds are synchronized before clutch engagement, achieving smooth engagement while managing the complexity through systematic control.
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
Enables seamless switching between series-parallel and series modes, reducing shocks and improving fuel efficiency by ensuring synchronous rotation speeds and controlled torque fluctuations.
Implementation Method 1
a first rotary electric machine MG1 and a second rotary electric machine MG2... Power from the internal combustion engine is transmitted to the first rotary electric machine MG1
Data Source
AI summary
A control process including the following steps is executed. The control process includes, at the time of switching from series-parallel mode to series mode, a step of reducing an engine torque, a step of releasing a clutch, a step of reducing a reaction torque of a first rotary electric machine and a step of increasing a torque of a second rotary electric machine, and, when synchronization is started and a step of increasing a positive torque of the first MG, a step of starting engagement of a clutch, and, when a rotation speed of the first rotary electric machine and a rotation speed of an engine are synchronous with each other, a step of engaging the clutch.