Hybrid Vehicle Controller Strategy for Motor Controllability Loss
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Solution Overview
Problem
Hybrid vehicles with a single electric machine for propulsion and battery charging are vulnerable to inoperable components, leading to potential battery drain and vehicle shutdown when the electric machine loses controllability, especially due to communication losses or speed feedback issues, which can result in inability to maintain traction battery state of charge above a threshold.
Innovation Solution
A controller-programmed strategy that adjusts engine speed and transmission gear to maintain the electric machine's operation within a predetermined range, allowing current flow to the traction battery and transitioning to a limited operating mode to prevent battery depletion, even when the electric machine is uncontrollable, by using the engine and gearbox to charge the battery and manage accessory loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the electric machine is used for propulsion and battery charging, then the hybrid vehicle achieves improved fuel efficiency and reduced emissions, but the vehicle becomes vulnerable to inoperable components leading to battery drain and vehicle shutdown when the electric machine loses controllability
Solution Approach 1:
The system dynamically switches between normal hybrid operation mode and limited operation mode based on the controllability status of the electric machine. When the electric machine becomes inoperable, the controller automatically transitions the vehicle to limited operation mode where the engine directly drives the transmission, bypassing the uncontrollable electric machine, thereby maintaining vehicle operability while preserving the fuel efficiency benefits of hybrid operation when available
Solution Approach 2:
The system changes operational parameters by adjusting the engagement state of the clutch between the engine and transmission. In normal mode, the clutch engages the electric machine for propulsion; in limited mode, the clutch reconfigures to directly couple the engine to the transmission, changing the power flow path to maintain vehicle operation without the uncontrollable electric machine
2Reliability
If the controller prevents operation of the hybrid vehicle when the electric machine becomes inoperable, then vehicle safety is maintained, but the vehicle cannot reach a safe destination and requires immediate towing
Solution Approach 1:
The powertrain system is segmented into independent operable paths: the primary hybrid path using the electric machine for propulsion, and a secondary limited path using direct engine-to-transmission coupling. When the electric machine fails, the system activates the secondary path, allowing the vehicle to continue operating in a limited capacity to reach a safe destination, rather than completely shutting down
3Stability of the object's composition
If the electric machine loses controllability due to communication loss or speed feedback issues, then the system maintains stability, but the traction battery state of charge cannot be maintained above the threshold leading to battery depletion
Solution Approach 1:
The clutch acts as an intermediary mechanism that reconfigures the power flow path when the electric machine becomes inoperable. By engaging the clutch to directly couple the engine to the transmission, the system bypasses the uncontrollable electric machine, preventing it from acting as a harmful load that would drain the battery, while maintaining system stability through controlled engagement
4Quantity of substance
If the vehicle transitions to limited operating mode to maintain battery charge, then the battery state of charge is maintained above threshold, but the vehicle loses electric propulsion capability
Solution Approach 1:
The system dynamically adapts its propulsion capability based on the operational status of the electric machine. In normal mode, the vehicle enjoys full hybrid propulsion versatility with both electric and engine power. In limited mode, the system dynamically switches to engine-only propulsion while maintaining the ability to charge the battery, preserving essential vehicle functionality while adapting to the reduced capability state
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 the hybrid vehicle to maintain limited operation and prevent immediate shutdown, allowing the vehicle to reach a safe destination and maintain traction battery charge levels, thereby avoiding immediate towing and ensuring subsequent drivability.
Implementation Method 1
operate the engine and gearbox to cause current to flow from the electric machine to the traction battery
Data Source
AI summary
A vehicle includes a hybrid powertrain. The hybrid powertrain includes an engine and an electric machine. In response to a loss of controllability of the electric machine, a controller is programmed to operate the powertrain in a limited operating mode. In the limited operating mode, the powertrain is controlled so that a speed of the engine is within a speed range such that the electric machine generates a current to charge a traction battery. In response to a loss of communication with a power inverter that controls the electric machine, the powertrain is controlled so that the speed of the engine is within the speed range and the current flowing to the traction battery is monitored. If the current flow is above a threshold, then the limited operating mode is entered.