Bus Capacitor Auxiliary Power for Safe Converter Shutdown
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Solution Overview
Problem
Conventional power conversion systems require additional energy storage devices and discharging resistors to ensure safe shutdown, increasing cost and volume, and they need auxiliary power sources at both AC and DC sides to operate independently.
Innovation Solution
A power conversion system with AC and DC auxiliary sources connected to a bus capacitor, discharging it via an auxiliary source to energy consumption equipment when shutdown, eliminating the need for additional storage devices and resistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional energy storage devices such as UPS are disposed to address low-voltage crossover, then the power conversion system can operate during voltage fluctuations, but the cost and volume of the system increase
Solution Approach 1:
The bus capacitor is designed to serve dual functions: its primary function of filtering DC voltage is supplemented by a secondary function of providing auxiliary power during low-voltage crossover events. This eliminates the need for separate UPS devices while maintaining operation continuity.
Solution Approach 2:
The patent combines the auxiliary power supply function with the existing bus capacitor, merging two previously separate functions (voltage filtering and auxiliary power supply) into a single component, thereby reducing overall system volume and cost.
2Adaptability or versatility
If multiple auxiliary sources are disposed for different operation modes, then the power conversion system can operate in all modes, but the device complexity increases
Solution Approach 1:
The bus capacitor is designed as a universal auxiliary power source that can serve all operation modes (grid-connected, off-grid, and AFE modes) through a single unified configuration, eliminating the need for mode-specific auxiliary sources.
Solution Approach 2:
The bus capacitor automatically provides auxiliary power to the control board during system shutdown without requiring external intervention or multiple dedicated auxiliary sources, as it utilizes its own stored energy.
3Reliability
If a discharging resistor is disposed to discharge the bus capacitor, then the safety requirement is met, but the cost and volume increase
Solution Approach 1:
The discharge function is merged with the existing bus capacitor by utilizing its inherent capacitance to provide controlled discharge through the PFC circuit during shutdown, eliminating the need for a separate discharging resistor.
Solution Approach 2:
The PFC circuit acts as an intermediary that enables the bus capacitor to discharge its energy safely during shutdown by converting it to AC power, replacing the need for a direct resistive discharge path.
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
Reduces cost and volume by eliminating the need for additional energy storage and discharging resistors, while ensuring safe shutdown and providing auxiliary power to critical components.
Implementation Method 1
a bus capacitor, and a first auxiliary source. The AC port receives or provides an AC voltage, and the DC port provides or receives a DC voltage
Implementation Method 2
The first auxiliary source has an input terminal electrically connected to the bus capacitor for receiving a capacitor voltage across the bus capacitor
Implementation Method 3
discharging the bus capacitor by supplying power to the energy consumption equipment when the capacitor voltage across the bus capacitor is higher than a first preset value or the power conversion system is shut down
Data Source
AI summary
A power conversion system and an auxiliary power supplying method thereof are provided. The power conversion system includes AC and DC ports, an AC-DC converter, a bus capacitor, and a first auxiliary source. The AC port receives or provides an AC voltage, and the DC port provides or receives a DC voltage. The AC-DC converter has an AC terminal and a DC terminal electrically connected to the AC port and the DC port respectively. The bus capacitor is electrically connected to the DC terminal. The first auxiliary source has an input terminal electrically connected to the bus capacitor for receiving a capacitor voltage across the bus capacitor.