Hydrogen Engine Hybrid Power Control With Electric-Assist Compression
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Solution Overview
Problem
Hydrogen combustion engines in hybrid power systems face challenges in managing transient power demands while maintaining optimal engine operation, as they tend to produce undesirable NOx emissions and require modifications to engine design and control strategies.
Innovation Solution
The method involves combusting gaseous hydrogen fuel in multiple engine cylinders and operating an electrical generator. An electric-assist compressor is used to increase airflow into the engine based on increased power demands, while a power flow control unit manages the airflow and fuel injection to maintain a stoichiometrically lean air-fuel ratio, limiting NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine increases power output to satisfy transient load demands, then the power output is improved, but the NOx emissions increase
Solution Approach 1:
The electric-assist compressor provides advance action by increasing airflow to the engine before the transient load demand fully manifests. This preliminary airflow increase allows the engine to meet power demands without exceeding NOx emission limits, as the leaner air-fuel ratio is established in advance through compressor-assisted airflow management.
Solution Approach 2:
The electric-assist compressor acts as an intermediary between the engine and the transient load demands. It mediates the relationship by providing the additional airflow needed for power increases while maintaining the lean air-fuel ratio that limits NOx emissions, thus resolving the contradiction between power output and emissions.
2Object-generated harmful factors
If the engine operates in a narrow range of speed and load to optimize combustion and aftertreatment, then the emissions performance is improved, but the response to transient power demands deteriorates
Solution Approach 1:
The system dynamically adjusts the electric-assist compressor operation in response to transient load demands. The compressor motor command is varied based on real-time power flow control, allowing the engine to temporarily operate outside its narrow optimal range without compromising emissions performance. This dynamic adjustment enables rapid response while maintaining emissions control.
Solution Approach 2:
The system changes operating parameters by using the electric-assist compressor to modify airflow and maintain lean air-fuel ratios during transient conditions. This parameter change allows the engine to respond quickly to power demands while keeping NOx emissions controlled through maintained lambda ratio, effectively decoupling response speed from emissions performance.
3Power
If the electric-assist compressor is used to increase airflow for transient power demands, then the power response is improved, but the use of energy increases
Solution Approach 1:
The power flow control unit implements feedback control by continuously monitoring engine operating conditions and adjusting the electric-assist compressor motor command accordingly. The controller determines the optimal balance between using compressor power and engine power based on real-time conditions, ensuring the electric-assist compressor is used only when necessary to meet transient demands, thus minimizing energy consumption while maintaining power response capability.
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 effectively increases engine power output to satisfy transient load demands, reduces NOx emissions by maintaining a lean air-fuel ratio, and compensates for limited exhaust energy by using electric-assist compressor power, thereby enhancing the efficiency and emissions performance of hydrogen combustion engines in hybrid systems.
Implementation Method 1
operating an electric-assist compressor to supply an increased airflow into the engine based on the increased engine power demand
Implementation Method 2
combusting a gaseous hydrogen fuel in a plurality of cylinders in an engine
Data Source
AI summary
Operating a hybrid power system for a machine includes combusting a direct injected gaseous hydrogen fuel in an engine operating an electrical generator, and increasing a load demand of the hybrid power system. Operating the hybrid power system further includes operating an electrical-assist compressor to supply an increased airflow into the engine based on an increased engine power demand to satisfy the increased load demand. Air-fuel equivalence ratio of the engine (so-called “lambda”) is maintained at a ratio of about 2 or greater to limit NOx emissions, and between a hydrogen fuel misfire limit and a hydrogen fuel preignition limit. Related apparatus and control logic is also disclosed.