Multi-mode Powertrain Extrema Determination
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Solution Overview
Problem
Existing powertrain systems face challenges in efficiently managing torque and acceleration within mechanical, electrical, and thermal constraints, limiting their operational efficiency and reliability.
Innovation Solution
A method is introduced to determine extrema for an objective function by establishing an objective component equation with both linear and nonlinear constraints, allowing for optimal control of powertrain operations by transforming variables into a multi-dimensional space and identifying feasible regions within these constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple torque-generative devices and torque-transfer elements are employed to increase powertrain flexibility and performance, then the system's adaptability and power output are improved, but the device complexity and control difficulty increase
Solution Approach 1:
The powertrain system is segmented into multiple independent torque-generative devices (engine, motor, generator) and torque-transfer elements (clutches, brakes, gear sets), allowing each component to be controlled independently while contributing to the overall system output. This segmentation enables flexible configuration of torque paths without increasing overall system complexity.
Solution Approach 2:
The torque machines are designed with multi-functionality, capable of operating as motors, generators, or being mechanically coupled to the engine. The transmission device serves multiple functions including torque multiplication, direction reversal, and mechanical coupling. This multi-functionality reduces the need for separate dedicated components.
2Reliability
If operating limits are imposed on components to protect them from damage, then component reliability is improved, but the system's operational range and efficiency are reduced
Solution Approach 1:
The operating limits of components are made dynamic rather than static. The control system continuously adjusts torque constraints on each component based on real-time operating conditions, component state, and system demands. This allows the system to operate at maximum efficiency when conditions permit while automatically protecting components when limits are approached.
Solution Approach 2:
The control system implements continuous feedback monitoring of component operating states (temperature, torque, speed, electrical parameters) and adjusts torque distribution in real-time. This feedback mechanism ensures components operate within safe limits while maximizing overall system efficiency by optimizing torque allocation across available torque-generative devices.
3Productivity
If a control system continuously monitors and adjusts torque distribution among multiple devices, then system efficiency and reliability are improved, but the computational complexity and control processing requirements increase
Solution Approach 1:
The control system pre-establishes torque constraints and operating limits for each component based on their mechanical, electrical, and thermal characteristics. These preliminary constraints are incorporated into the optimization algorithm, allowing the control system to focus computational effort on optimizing torque distribution within predefined boundaries rather than calculating all possible operating parameters in real-time.
Solution Approach 2:
The control system transforms the complex multi-variable torque distribution problem into a more manageable form by changing parameters - using torque constraints and Lagrange multipliers to convert inequality constraints into equality constraints that are easier to solve computationally. This parameter transformation simplifies the real-time optimization calculations.
Data Source
AI summary
A powertrain system includes an internal combustion engine, a multi-mode transmission having a plurality of torque machines, and a driveline. A method to determine extrema for an objective function employed to control operation of the powertrain system includes establishing an objective component equation related to an objective function and corresponding to an object component of interest. A plurality of linear constraints and a non-linear constraint are imposed on the objective component equation. The objective component equation is solved in relation to the plurality of linear constraints and the non-linear constraint to determine the extrema for the objective function. The extrema for the objective function are employed to control operation of the powertrain system.