Hybrid EV Powertrain Control for DC Bus Voltage During Battery Failure
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Solution Overview
Problem
Hybrid electric vehicles face challenges in maintaining DC bus voltage stability during battery failure, particularly due to limited torque response of internal combustion engines, which can lead to delays and instability during transient events like battery disconnection or vehicle acceleration/deceleration.
Innovation Solution
A control system that operates the motor/generator in different modes based on battery connection status, switching to voltage control mode when the battery is disconnected, and adjusts powertrain parameters to assist the motor/generator in maintaining DC bus voltage, thereby improving response to load changes and transient events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the motor/generator operates in voltage regulation mode during battery failure, then the DC bus voltage can be maintained, but the limited torque response of the engine causes delays and lag in responding to load changes
Solution Approach 1:
The control system performs preliminary action by adjusting engine parameters (such as fuel injection timing, air intake, or throttle position) in advance when a battery failure is detected or predicted. This preparation allows the engine to respond more quickly to subsequent load changes on the DC bus, reducing the torque response delay that would otherwise occur when the motor/generator first enters voltage regulation mode.
Solution Approach 2:
The system dynamically adjusts engine operating parameters based on real-time load conditions on the DC bus. The control system continuously monitors bus voltage and load demands, then dynamically modifies engine torque output characteristics to match the changing electrical load requirements, enabling faster and more precise torque response during battery failure conditions.
2Stability of the object's composition
If the engine operates in speed control mode, then speed stability is maintained, but the torque control resolution is limited due to dead bands and low torque resolution zones in the engine torque map
Solution Approach 1:
The control system changes operating parameters by transitioning the engine from speed control mode to torque control mode during battery failure conditions. This parameter change allows direct control of engine torque output, providing finer torque resolution and eliminating dead bands that exist in speed control mode. The system can precisely modulate torque to match the specific load demands on the DC bus, improving both torque control resolution and overall system responsiveness.
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
The control system enhances the ability to regulate DC bus voltage during battery failure, ensuring continued vehicle operation and improved safety by maintaining voltage stability for critical systems like power steering and accessories.
Implementation Method 1
the motor/generator may operate in a voltage regulation mode to maintain the DC bus voltage
Implementation Method 2
The battery is typically in the form of a battery pack comprising a large number of individual electrochemical cells connected in series and parallel
Data Source
AI summary
Powertrains of hybrid electric vehicles, control systems for controlling the powertrains, and methods for controlling the powertrains are disclosed. The powertrain includes an engine, a motor/generator, a battery and a DC bus. The control system is configured to: operate the motor/generator in a first mode when the battery is connected to the DC bus; operate the motor/generator in a second mode when the battery is disconnected from the DC bus, wherein the second mode is a voltage control mode in which the motor/generator controls a voltage of the DC bus; and adjust at least one parameter of the powertrain to assist the motor/generator in controlling the voltage of the DC bus in the second mode.