DC-DC Converter Sliding Mode Control for Hybrid Energy Stability
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Solution Overview
Problem
Existing DC coupled hybrid systems face instability due to limited input voltage and load current ranges, requiring custom design and failing to adapt to changing power sources and loads, which can lead to PV curtailment and increased operating costs.
Innovation Solution
A multi-purpose DC to DC converter system with a non-isolated Buck-Boost converter topology, controlled by a sliding surface mode controller that maintains constant output voltage and adapts to changes in load current and input voltage, allowing seamless transition between power sources and loads without component adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a DC coupled hybrid system uses custom-designed voltage converters with limited input voltage and load current ranges, then the system can maintain stable operation within those ranges, but the system cannot adapt to changing power sources and loads, leading to instability when operating conditions change
Solution Approach 1:
The patent implements dynamic adaptation by continuously monitoring input voltage and load current conditions and automatically adjusting converter operation parameters. The system transitions between different operating modes (buck, boost, or linear mode) based on real-time conditions, allowing the fixed hardware design to adapt dynamically to varying power sources and loads without requiring custom design for each scenario.
Solution Approach 2:
The system changes operational parameters (such as switching frequency, duty cycle, or mode of operation) based on detected input voltage and load conditions. By modifying these parameters dynamically, the converter maintains stable voltage conversion across a wide range of operating conditions despite having a fixed hardware design with limited voltage and current ranges.
2Device complexity
If the system operates with fixed component values and limited voltage ranges, then the converter design is simpler, but the system becomes unstable when input voltage or load current changes outside the defined ranges
Solution Approach 1:
The voltage converter system performs self-diagnosis and self-adjustment by continuously monitoring its own operating conditions (input voltage, load current) and automatically transitioning between operating modes to maintain stability. This self-service capability allows the system with fixed components to reliably handle varying conditions without external intervention or complex redesign.
Solution Approach 2:
The system incorporates feedback mechanisms that detect changes in input voltage and load current conditions and use this information to adjust converter operation in real-time. This closed-loop control enables the fixed-design converter to maintain reliable operation across varying conditions by continuously adapting its operational parameters based on feedback from the operating environment.
3Stability of the object's composition
If AC coupling is used in PV-Diesel hybrid systems to provide stable operation, then the system maintains stable loads, but operating costs increase due to spinning reserve requirements and PV curtailment losses
Solution Approach 1:
The DC-coupled hybrid system uses a universal DC bus that can accommodate multiple power sources (PV arrays, diesel generators, battery banks) and multiple load types without requiring source-specific coupling infrastructure. This multi-functional architecture allows any DC power source to directly serve any DC load, eliminating the need for spinning reserves and reducing PV curtailment losses while maintaining stable operation.
4Reliability
If DC coupled hybrid systems are designed for specific voltage ranges, then the system can operate reliably within those specifications, but any change in DC source or output current destabilizes the system
Solution Approach 1:
The system dynamically adjusts its operational characteristics based on the connected power source and load conditions. When transitioning between different DC sources (PV, generator, battery) or varying load currents, the converter automatically modifies its switching parameters and operating mode to maintain stable voltage conversion, ensuring reliable operation across diverse scenarios without requiring redesign.
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 system ensures stable and efficient operation across a wide range of input voltages and load currents, reducing PV curtailment and operating costs by automatically adjusting to changing conditions, enabling reliable operation with different power sources and loads.
Implementation Method 1
The DC to DC converter typically has a non-isolated Buck-Boost convertor topology and keeps the output voltage constant and ripple free regardless of changes in load current or the input voltage of the power source
Data Source
AI summary
A method is provided for setting an operating parameter for a DC to DC voltage converter. A load is operated, using a controller, with the operating parameter at a first value. A measurement of an actual inductor current at an inductor of the DC to DC voltage converter, a measurement of an actual load current are provided. The method then determines a reference value for the inductor current, based on the actual load current combined with an inductor current adjustment value based on a desired output voltage at the DC load. The reference value for the inductor current is then compared to the actual inductor current, and the operating parameter is maintained at the first value if the reference value is greater than the actual inductor current. The operating parameter is changed to a second value if the reference value is less than the actual inductor current.