Hybrid Engine Duty Cycle Control for Turbocharger Efficiency
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Solution Overview
Problem
Turbochargers in internal combustion engines of series hybrid powertrains typically operate at peak efficiency for only a narrow range of conditions, limiting overall engine system efficiency and increasing running costs due to inefficient duty cycles.
Innovation Solution
A control system that monitors the state of charge of the battery and modulates the engine and turbocharger operation to maintain the engine within a narrow, optimal operating band, ensuring the turbocharger operates at peak efficiency for a majority of the duty cycle by adjusting predefined charge thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the engine operates through a wide range of conditions to meet varying vehicle power demands, then the powertrain system can handle diverse operating scenarios, but the turbocharger operates outside its optimal efficiency range for most of the duty cycle
Solution Approach 1:
The system dynamically adjusts the engine operating point by controlling the duty cycle (on/off timing) to keep the engine and turbocharger within a narrow optimal operating band, rather than allowing operation across a wide range. This dynamic control resolves the contradiction by making the system adaptable through temporal modulation rather than spatial (operating range) variation.
Solution Approach 2:
The controller modifies operational parameters (duty cycle timing, on/off transitions) to constrain the engine operating range. By changing how the parameter (operating range) is utilized—restricting it to an optimal band rather than allowing full range—the system maintains turbocharger efficiency while still meeting power demands through cyclic operation.
2Productivity
If the engine operates at varying conditions to meet power demands, then the system can respond to different vehicle requirements, but the turbocharger operates inefficiently for the majority of the duty cycle
Solution Approach 1:
The system uses periodic on/off cycling of the engine with controlled duty cycles to maintain the turbocharger in its optimal operating range. Instead of continuous operation at varying conditions, the engine operates periodically at a consistent optimal point, resolving the contradiction by maintaining productivity through rhythmic operation rather than continuous variable operation.
Solution Approach 2:
The controller dynamically adjusts the duty cycle parameters (on-time, off-time, transition timing) to ensure the engine operates within the optimal band during active periods. This dynamic control enables the system to maintain both productivity and efficiency by adapting the timing and duration of operational cycles rather than allowing free variation in operating conditions.
3Adaptability or versatility
If the engine duty cycle covers a wide operating map, then the system can meet diverse vehicle power demands, but the turbocharger efficiency is compromised across most of the duty cycle
Solution Approach 1:
The controller uses feedback from the powertrain system state to adjust the duty cycle and keep the engine operating within the optimal band. This feedback mechanism enables the system to maintain turbocharger efficiency while still responding to varying vehicle power demands, as the controller continuously monitors and adjusts operational parameters based on current conditions.
Solution Approach 2:
The system dynamically modulates the duty cycle parameters in response to varying power demands, keeping the engine operating point within the optimal efficiency band. This dynamic adjustment resolves the contradiction by enabling adaptability through real-time parameter modulation rather than through expansion of the operating range.
Data Source
AI summary
A powertrain system includes an engine coupled to a turbocharger and a timer, a motor generator coupled to the engine and a battery, and a controller. The controller is structured to receive data indicative of a state of charge from the battery, determine whether the state of charge is at or below a high predefined threshold, modulate control on the engine and the timer in response to determining the state of charge is above the high predefined threshold, determine whether the state of charge is above a low predefined threshold in response to the state of charge being at or below the high predefined threshold, and modulate control of the engine and the timer in response to determining the state of charge is at or below the low predefined threshold.