Inverter Controller Sequential Capacitor Charging
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Solution Overview
Problem
In power supply systems with multiple inverters connected in parallel, excessive charging currents can flow between capacitors during startup, potentially damaging fuses and other components, and existing solutions to prevent this either increase system size or manufacturing costs.
Innovation Solution
An inverter controller that controls the start-up sequence of switching elements to prevent excessive charging currents by charging all capacitors in parallel inverters sequentially, using AC interconnection switching elements to manage the flow of current and avoid short-circuit currents between capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a circuit for prevention of an overcurrent flowing between capacitors is incorporated into a power supply system, then the overcurrent protection is improved, but the system size increases
Solution Approach 1:
The patent combines the overcurrent protection function with the existing AC interconnection switching elements that are already present in the inverter system. By integrating the protection logic into the control of these existing switches, the patent avoids adding separate protection circuits, thereby preventing increase in system size while still achieving reliable overcurrent protection between capacitors.
Solution Approach 2:
The AC interconnection switching elements, originally designed for connecting inverters to the power system, are made to serve a dual function: both AC interconnection and DC-side overcurrent protection. This multi-functionality eliminates the need for dedicated protection components, resolving the contradiction between protection reliability and system size.
2Reliability
If a circuit for prevention of an overcurrent flowing between capacitors is incorporated into a power supply system, then the overcurrent protection is improved, but the manufacturing costs increase
Solution Approach 1:
The patent merges the overcurrent protection function with existing control circuits for AC interconnection switching elements. By reusing existing hardware and control infrastructure, the patent avoids additional manufacturing costs while achieving reliable protection against capacitor overcurrent.
Solution Approach 2:
The control system uses its own existing switching elements and control logic to provide protection functionality. The inverter controller autonomously manages the charging sequence and overcurrent prevention without requiring external protection devices, thereby eliminating additional manufacturing costs.
3Reliability
If conventional overcurrent prevention circuits are used, then the protection against charging current is improved, but the device complexity increases
Solution Approach 1:
The patent combines the charging current protection function with the existing AC interconnection control logic. By integrating protection functionality into the existing control framework, the patent avoids increasing device complexity while achieving reliable protection during capacitor charging operations.
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
Prevents excessive charging currents from flowing between capacitors, thereby protecting fuses and other components from damage, without increasing the size or cost of the power supply system.
Implementation Method 1
a first start-time controller configured to perform first start-time control of opening all of the AC interconnection switching elements firstly, closing the first switch of a first inverter of the inverters while opening the first switches of the other inverters and turning on at least a first switching element provided at the first inverter to charge the respective capacitors of the inverters
Data Source
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AI summary
An inverter controller (1) is configured to control inverters (2a to 2d) connected in parallel. The inverter controller is configured to close a switch (5pa) of a first inverter (2a) and turn on a first switching element (11a) provided at the first inverter to charge capacitors (6a) of the inverters at the time of starting the inverters, and to close the other switches after the capacitors are charged.