Hybrid Powertrain Control for Electrical Loss Reduction
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Solution Overview
Problem
Existing hybrid powertrain systems face challenges in minimizing electrical losses and achieving a compact, reliable design, particularly due to the limitations of conventional clutch mechanisms and the dependency on electrical machine torque, which restricts torque transfer and increases weight and cost.
Innovation Solution
The method involves a hybrid powertrain with two planetary gears and electrical machines, using coupling devices to connect and disconnect components synchronously, allowing the electrical machines to operate in waiting states to minimize losses and enable torque transfer without torque interruption, and a locking mechanism to adapt for electric operation, reducing the need for conventional clutches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional clutch mechanism is used to disconnect the gearbox input shaft from the combustion engine during shifting, then shifting can be achieved, but this results in heating of clutch discs, wear, increased fuel consumption, and higher weight and cost
Solution Approach 1:
The invention extracts and eliminates the conventional clutch mechanism from the hybrid powertrain system. By using the electrical machine to control torque flow through the planetary gear, the clutch is removed entirely, preventing heating, wear, and energy loss associated with friction-based disconnection mechanisms.
Solution Approach 2:
The invention replaces the mechanical friction-based clutch system with an electrical control system. The electrical machine electronically controls torque distribution through the planetary gear, substituting mechanical friction engagement with electromagnetic torque management to achieve shifting without energy loss.
2Force
If the electrical machine's torque is increased to match the combustion engine's torque, then sufficient reaction torque can be generated for the planetary gear, but this increases the weight and cost of the electrical machine
Solution Approach 1:
The invention makes the electrical machine's torque output dynamic rather than static. The electrical machine's torque capacity is adjusted in real-time based on operating conditions and planetary gear requirements, allowing a smaller, lighter machine to provide sufficient reaction torque when needed without requiring constant high torque capability.
Solution Approach 2:
The invention changes the operational parameters of the electrical machine by controlling its torque output as a variable parameter rather than a fixed maximum. This allows the system to optimize the electrical machine's size and weight while maintaining adequate torque generation capability through intelligent control during different operating modes.
3Speed
If the electrical machine operates continuously to control the planetary gear, then precise speed control is achieved, but electrical losses increase
Solution Approach 1:
The invention implements periodic action by having the electrical machine operate intermittently rather than continuously. The electrical machine is activated only when torque control through the planetary gear is required, and deactivated during periods when mechanical torque transfer suffices, reducing electrical losses while maintaining speed control capability when needed.
Solution Approach 2:
The invention enables the mechanical system to serve itself by allowing direct torque transfer from the combustion engine through the planetary gear without continuous electrical machine intervention. The electrical machine provides assistance only when necessary, allowing the mechanical components to handle torque transfer independently during normal operation, thereby minimizing electrical energy consumption.
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 minimizes electrical losses, achieves a compact and reliable design, and allows for efficient torque transfer across all operating modes without relying on energy storage device power, enhancing the powertrain's efficiency and reliability.
Implementation Method 1
When the vehicle is braked, the electrical machine generates electric power, which is stored in the energy storage device. This is usually referred to as regenerative braking
Implementation Method 2
A gearbox in a hybrid vehicle may comprise a planetary gear. The planetary gearbox usually comprises three components, which are rotatably arranged in relation to each other, namely a sun wheel, a planetary wheel carrier and an internal ring gear
Data Source
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AI summary
The present invention relates to a method to control a hybrid powertrain (3). The method comprises the steps: a) engaging a gear corresponding to the at least one gear pair (G1, 60, 72), which is connected with the first planetary gear (10), in the gearbox (2) or corresponding to the at least one gear pair (G2, 66, 78), which is connected with the second planetary gear (12) and the output shaft (20); b) selecting a gear by connecting two rotatable components (22, 26, 50) in the first planetary gear (10) with each other, via a first coupling device (56); and/or by connecting two rotatable components (28, 32, 51) in the second planetary gear (12) with each other, via a second coupling device (58); and c) controlling a switch (49) connected to the first and the second electrical machines (14, 16), in such a way that the first electrical machine (14) is set into a waiting state, if the second coupling device (58) connects the two rotatable components (28, 32, 51) of the second planetary gear (12) with each other, and in such a way that the second electrical machine (14) is set into a waiting state, if the first coupling device (56) connects the two rotatable components (22, 26, 50) of the first planetary gear (10) with each other. The invention also relates to a vehicle (1) with a hybrid drive line (3), which vehicle (1) comprises a gearbox (2), which is controlled according to the method. The invention also relates to a computer program (P) to control a hybrid powertrain (3) and a computer program product comprising program code for an electronic control device (48) or another computer (53) to implement the method according to the invention.