Single-Phase Inverter Load Balance via Output Limiting
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Solution Overview
Problem
High-output decentralized energy supply systems using single-phase inverters face issues with asymmetrical power supply and load unbalance due to the high cost and reduced efficiency of three-phase inverters, leading to system shutdown upon inverter failure.
Innovation Solution
Implementing a method that limits the power of intact inverters to prevent system shutdown upon failure of one inverter, using additional failure detection circuits and communication signals to control PWM, allowing the remaining inverters to adjust their output and maintain a balanced power supply within admissible limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If three single-phase inverters are used for high output power supply, then cost is reduced and efficiency is improved, but asymmetrical power supply and load unbalance occur when one inverter fails
Solution Approach 1:
The patent implements a feedback mechanism where the status of each inverter is monitored and communicated to other inverters. When one inverter fails, the other inverters receive feedback signals and automatically adjust their output power to maintain load balance. This feedback loop enables the system to respond dynamically to failures and maintain reliable operation without requiring expensive three-phase inverters.
Solution Approach 2:
The patent makes the inverter system dynamic by enabling real-time adjustment of output power based on operational status. Each inverter can dynamically modify its power output in response to failure conditions of other inverters, transitioning from static fixed-output operation to adaptive variable-output operation. This dynamic capability allows the system to maintain balance despite component failures.
2Reliability
If the entire system is shut down when one inverter fails, then load unbalance is prevented, but current supply availability decreases
Solution Approach 1:
Instead of completely shutting down the system when one inverter fails, the patent applies partial action by reducing the output power of the remaining inverters to compensatory levels. This partial reduction in power output from healthy inverters is sufficient to maintain load balance and prevent harmful unbalance, while allowing the system to continue operating and supplying current to the load.
Solution Approach 2:
The patent prepares for potential failures by implementing beforehand cushioning through the communication network and control mechanisms. When a failure occurs, the system has pre-established protocols and communication channels ready to immediately coordinate power adjustments among remaining inverters, preventing load unbalance without requiring system shutdown.
3Difficulty of detecting and measuring
If additional failure detection circuits are added to each inverter, then failure detection capability is improved, but device complexity increases
Solution Approach 1:
The patent implements universality by designing the additional circuit in each inverter to perform multiple functions: monitoring the status of other inverters, communicating failure information through the communication network, and participating in the coordinated power adjustment process. This multi-functional approach reduces the need for separate dedicated circuits for each function, thereby limiting the increase in overall device complexity while maintaining comprehensive failure detection capability.
Data Source
AI summary
A method of converting a direct voltage generated by a decentralized power supply system into three-phase alternating voltage by means of a plurality of single-phase inverters (WR1-WR3), said alternating voltage being provided for supplying an electric mains, is intended to avoid inadmissible load unbalances using single-phase inverters. This is achieved in that, upon failure of one inverter (WR1-WR3), an asymmetrical power supply distribution is reduced by limiting the output of the other inverters. The method makes it possible to simplify three-phase voltage monitoring.