PV Inverter Auxiliary Power Startup Control for Low-Solar Conditions
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Solution Overview
Problem
Photovoltaic inverters face issues with repeated restarts due to insufficient solar panel power and unnecessary losses at night, particularly when using direct current bus power, and existing solutions fail to simultaneously address these problems while increasing hardware costs and reducing adaptability for different system voltages.
Innovation Solution
A control method for the auxiliary power supply of a photovoltaic inverter, incorporating a rectifier circuit and a conversion circuit with a voltage determining unit and a power determining unit, which starts the auxiliary power supply only when the solar panel's output voltage and power exceed specific thresholds, avoiding unnecessary operation at night and reducing hardware costs by not requiring additional control circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power is taken from the direct current bus of the photovoltaic inverter, then the auxiliary power supply can operate independently, but the system becomes more complicated and costs increase significantly when system voltage rises to 1100V, 1500V or higher
Solution Approach 1:
The auxiliary power supply is designed to universally support multiple system voltages (1100V, 1500V, and higher) through a single standardized scheme. The circuit topology and control strategy remain consistent across different voltage levels, eliminating the need for voltage-specific design variations and reducing overall system complexity.
Solution Approach 2:
The patent employs parameter adaptation techniques where only specific electrical parameters (such as component ratings, insulation levels, and protective settings) are adjusted for different system voltages, while the fundamental circuit architecture and control logic remain unchanged. This allows the auxiliary power supply to accommodate high voltage applications without proportionally increasing complexity.
2Duration of action of stationary object
If the auxiliary power supply takes power from the direct current bus, then it can provide continuous power, but when solar panel output power is too small, the auxiliary power supply restarts repeatedly affecting reliability
Solution Approach 1:
The patent introduces a hybrid power architecture where the auxiliary power supply can draw power from two sources: the direct current bus during normal operation and the power grid during low solar output conditions. This intermediary power grid connection prevents repeated restarts by providing a stable backup power source when solar panel output is insufficient.
Solution Approach 2:
The system dynamically switches between power sources based on real-time solar panel output conditions. When solar power is sufficient, the auxiliary supply operates from the direct current bus; when solar power drops below a threshold, the system automatically transitions to grid power, ensuring continuous and stable operation without repeated restarts.
3Ease of operation
If the auxiliary power supply takes power from the alternating current grid, then the photovoltaic inverter does not need to work at night, but the auxiliary power supply still keeps working causing unnecessary losses
Solution Approach 1:
The system incorporates intelligent control with feedback mechanisms that monitor solar panel output, time of day, and power consumption requirements. This feedback enables the auxiliary power supply to automatically adjust its operation mode: drawing from the grid when necessary, reducing power consumption during low-demand periods, and shutting down completely at night when no power is needed, thereby eliminating unnecessary energy losses.
Solution Approach 2:
The auxiliary power supply operates periodically rather than continuously, aligning its activity with actual power needs. During nighttime hours when the photovoltaic inverter is not operational and no auxiliary power is required, the system enters a low-power or shutdown state, creating a periodic operation pattern that eliminates wasteful energy consumption during idle periods.
4Ease of operation
If additional control circuits are added to manage auxiliary power supply start and stop, then operation control is improved, but hardware investment costs increase and adaptability to different system voltages is reduced
Solution Approach 1:
The control circuit is designed with universal functionality that can manage auxiliary power supply operations across different system voltages (1100V, 1500V, and higher). The control strategy and circuit topology remain consistent regardless of voltage level, allowing the same hardware design to adapt to various voltage configurations without requiring additional voltage-specific control components.
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 solution prevents repeated restarts during insufficient power conditions and reduces losses at night, improving the reliability and adaptability of photovoltaic inverters for various system voltages without additional hardware investments.
Implementation Method 1
the rectifier circuit is configured to convert alternating current power of the power grid into direct current power
Implementation Method 2
the conversion circuit is configured to convert the direct current power into at least one auxiliary voltage
Data Source
AI summary
The present application provides a control method, an auxiliary power supply of a photovoltaic inverter, and a photovoltaic power generation system. The auxiliary power supply includes a rectifier circuit and a conversion circuit with at least one output terminal. The conversion circuit includes a voltage determining unit and a power determining unit. The conversion circuit is coupled to an output terminal of the rectifier circuit, and is configured to convert direct current power into at least one auxiliary voltage. The power determining unit and the voltage determining unit are coupled to an input terminal of the inverter circuit or an input terminal of the photovoltaic inverter, which are configured to obtain output power and an output voltage of the solar panel, respectively. When the output voltage is greater than the start-up voltage and the output power is greater than the start-up power, the auxiliary power supply starts.