Power Converter Startup Control for PV Inverter Undervoltage
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Solution Overview
Problem
Photovoltaic inverters experience startup hiccups under low-light conditions, leading to repeated shutdowns and reduced effective power generation and shortened service life due to undervoltage issues.
Innovation Solution
A power converter and method that control the number of input-side conversion circuits in a power-limited or zero-power state to maintain a stable power supply for the controller, preventing shutdowns by ensuring at least one circuit maintains input voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the photovoltaic inverter is started and connected to the power grid under low-light conditions, then the inverter can begin power generation, but the output voltage of the photovoltaic strings is pulled down causing undervoltage shutdown of the controller
Solution Approach 1:
The patent segments the power supply source for the controller from the photovoltaic string output. By introducing an auxiliary power supply circuit that operates independently from the main photovoltaic conversion circuit, the controller gains a dedicated power source that is not affected by voltage fluctuations in the photovoltaic strings, thus resolving the undervoltage shutdown issue while maintaining power generation capability
Solution Approach 2:
The patent introduces an auxiliary power supply as an intermediary component between the photovoltaic strings and the controller. This auxiliary power supply absorbs the voltage instability and provides a stable power source to the controller, preventing direct transmission of voltage fluctuations from the photovoltaic strings to the controller, thereby eliminating the startup hiccup phenomenon
2Reliability
If the controller shuts down due to undervoltage, then the inverter stops operating to protect the system, but repeated shutdowns and restarts reduce effective power generation and service life
Solution Approach 1:
The patent implements preliminary action by providing the auxiliary power supply that is ready to take over controller power supply before undervoltage conditions occur. The auxiliary power supply circuit is pre-configured and can immediately supply power when main power becomes unstable, preventing the controller shutdown before it happens and avoiding the repeated restart cycle that reduces productivity
Solution Approach 2:
The auxiliary power supply acts as a cushioning mechanism that absorbs the shock of undervoltage conditions before they can affect the controller. By having this backup power source in place beforehand, the system cushions against voltage fluctuations and prevents the harmful effect of repeated shutdowns and restarts, thereby maintaining both reliability and productivity
Data Source
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AI summary
The present application provides a power converter and a starting method therefor. The starting method comprises after a starting instruction is received, at each moment, enabling at least one target input-side conversion circuit to be in a power-limited state or a zero-power state, wherein when the target input-side conversion circuit is in the power-limited state or the zero-power state, the input voltage of the target input-side conversion circuit is not lowered. Therefore, the input voltage of at least one target input-side conversion circuit is not lowered at each moment, that is, decoupling of power supply of a controller and power conversion of the power converter is realized, so that the starting method can avoid the problem of undervoltage shutdown of the controller, and can further avoid the starting hiccup phenomenon of the power converter. Additionally, because the power converter can be a photovoltaic inverter, the starting method can also avoid the starting hiccup phenomenon of the photovoltaic inverter.