Hybrid EV Torque Split Control Without Belt-Slip Loss
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Solution Overview
Problem
Hybrid electric vehicles face challenges in efficiently distributing driving power between motors in HEV mode due to limitations in the hybrid starter generator, such as belt slip, reduced responsiveness, and difficulty in precise control.
Innovation Solution
A method and system for controlling a hybrid electric vehicle that involves determining the engine operating point and calculating the first and second motor torques based on engine torque, required torque, and transmission input speed, ensuring efficient power distribution and optimizing system efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hybrid starter generator is connected to the engine through a pulley and belt, then the engine can be started and electric power can be generated, but belt slip occurs and responsiveness deteriorates
Solution Approach 1:
The patent extracts the hybrid starter generator from the traditional belt-pulley connection to the engine crankshaft and repositions it to connect to the transmission input shaft. This separation removes the source of belt slip and responsiveness issues while preserving the essential functions of engine starting and power generation.
Solution Approach 2:
The transmission input shaft serves as an intermediary element between the hybrid starter generator and the powertrain system. By connecting through this intermediate point rather than directly to the engine crankshaft, the system achieves reliable power transmission without belt slip while maintaining responsiveness.
2Ease of operation
If the hybrid starter generator is connected through a pulley and belt, then engine starting function is achieved, but precise control becomes difficult
Solution Approach 1:
The patent removes the hybrid starter generator from the complex belt-pulley-engine crankshaft system and relocates it to the transmission input shaft. This extraction simplifies the control architecture by eliminating the intermediate belt transmission elements that complicate precise control while maintaining all essential functions.
3Speed
If the engine shaft pulley is smaller than the motor shaft pulley, then the motor RPM is higher than engine RPM, but the hybrid starter generator hardly generates substantial output when engine RPM is high
Solution Approach 1:
The transmission input shaft acts as a mediator that decouples the rotational speed relationship between the engine and motor. By connecting the hybrid starter generator to this intermediate point, the system can achieve high motor RPM for efficient operation while the transmission gearing handles the speed conversion, allowing substantial power generation even when engine RPM is high.
Data Source
AI summary
A hybrid vehicle and a method of controlling the same, are configured for more efficiently distributing driving power for respective driving sources. The method of controlling a hybrid electric vehicle may include determining an engine operating point in a hybrid electric vehicle (HEV) mode, and determining first torque for a first motor and second torque for a second motor based on engine torque according to the engine operating point, required torque, and a speed of an input end of a transmission, the first motor may be directly connected to the engine, the second motor may be directly connected to the input end of the transmission, and the first motor and the second motor may be connected in the predetermined drive mode using driving power of the engine.