Hybrid EV Drive Mode Control for Torque-Sized Powertrains
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Solution Overview
Problem
Hybrid electric vehicles face challenges in maintaining optimal power transmission system design and ride feeling while varying drive modes, particularly in wide open throttle states, due to torque specification issues in motor-generators.
Innovation Solution
A hybrid electric vehicle system that includes an engine, first and second motor-generators, and a controller to manage drive modes, such as EV and series modes, by setting a reference speed for mode transitions to maintain consistent zero-100 performance and reduce torque specification, thereby optimizing power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the motor-generator torque specification is increased to maintain zero-100 performance in all drive modes, then the vehicle acceleration performance is improved, but the system size and complexity increase
Solution Approach 1:
The patent applies dynamics by making the drive mode selection variable and adaptive based on real-time vehicle speed conditions. The controller dynamically switches between EV mode and series mode depending on whether vehicle speed is above or below a reference speed threshold, allowing the motor-generator torque requirements to be optimized for different operating conditions rather than designed for maximum torque in all conditions
Solution Approach 2:
The patent changes the operational parameters of the powertrain system by introducing a reference speed threshold that determines mode selection. By changing the vehicle speed parameter as the decision criterion, the system achieves consistent zero-100 performance with reduced motor-generator torque specification, as the engine assists the motor-generator only when needed (below reference speed)
2Volume of moving object
If the motor-generator torque specification is reduced to decrease system size, then the vehicle packaging is improved, but the zero-100 performance may be compromised
Solution Approach 1:
The patent applies multi-functionality by having the engine serve dual purposes: as a direct power source in series mode and as a power generation source to assist the motor-generator. This allows the motor-generator to have reduced torque specification while the engine provides supplemental power during low-speed conditions, maintaining overall zero-100 performance without increasing system size
Solution Approach 2:
The controller acts as an intermediary that coordinates between the engine and motor-generator based on vehicle speed conditions. By mediating the power flow and mode selection, the controller ensures that the reduced-torque motor-generator works in conjunction with the engine to maintain consistent acceleration performance across different drive modes
3Stability of the object's composition
If the drive mode is fixed to maintain consistent performance, then the ride feeling is improved, but the adaptability to different driving conditions is reduced
Solution Approach 1:
The patent makes the drive mode selection dynamic rather than fixed, using vehicle speed as the basis for automatic mode switching. This allows the system to adapt to different driving conditions while maintaining consistent zero-100 performance, as the mode changes are triggered by objective speed thresholds rather than subjective ride feeling considerations
Data Source
AI summary
Disclosed is a hybrid electric vehicle comprising an engine configured to generate power by burning a fuel, first and second motor-generators configured to generate power or assist the engine, and a controller. The controller may be configured to set an operation of a first EV mode using the second motor-generator, a second EV mode using the first and second motor-generators, or a series mode of driving the second motor-generator by using power generation of the engine, compare a speed of the vehicle with a reference speed based on that the engine is in an off state, and may be configured to perform a control so that the vehicle drives in the second EV mode when the speed of the vehicle is less than the reference speed.