Three-Phase Boost Rectifier Circuit for UPS Voltage Balance
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Solution Overview
Problem
Traditional three-phase uninterrupted power supply (UPS) systems using single battery packs require balancing devices to maintain voltage balance, increasing cost, complexity, and reducing efficiency, and are not suitable for modular UPS configurations where multiple modules share battery packs.
Innovation Solution
A three-phase boost rectifier circuit with dual battery packs and a specific configuration of thyristors and inductors that allows voltage balance without additional balancing devices, using a bidirectional thyristor SCR6 to control the bridge circuit and maintain load balance between positive and negative bus voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a balancing device is added to maintain voltage balance between positive and negative bus, then voltage balance is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the balancing function into the existing boost rectifier circuit by using the fourth bidirectional thyristor SCR6 to enable the second inductor L2 to serve dual purposes: as a boost inductor during rectification and as a balancing inductor during battery operation. This eliminates the need for separate balancing devices and reduces circuit complexity while maintaining voltage balance capability.
Solution Approach 2:
The second inductor L2 is designed to perform multiple functions: it acts as a boost inductor in rectifier mode and as a balancing inductor in battery mode. The fourth bidirectional thyristor SCR6 enables the circuit to switch between these modes, allowing the same hardware to maintain voltage balance without requiring additional dedicated balancing components.
2Stability of the object's composition
If a balancing device is added to maintain voltage balance, then voltage balance is improved, but power consumption increases and efficiency decreases
Solution Approach 1:
The balancing function is merged with the existing boost rectifier circuit operations. During battery mode, the fourth bidirectional thyristor SCR6 enables the second inductor L2 to transfer energy between the positive and negative battery packs, achieving voltage balance without requiring additional active balancing devices that would consume extra power.
Solution Approach 2:
The circuit uses its own existing components (second inductor L2 and fourth bidirectional thyristor SCR6) to perform the balancing function during battery operation. The system balances itself by internally redistributing energy between battery packs through the existing inductor, eliminating the need for external power-consuming balancing equipment.
3Adaptability or versatility
If dual battery pack topology is used to enable modular UPS configuration, then adaptability is improved, but device complexity increases due to additional inductors and thyristors
Solution Approach 1:
The patent combines the fourth bidirectional thyristor SCR6 with the existing circuit structure, allowing the second inductor L2 to serve dual purposes. This integration approach enables dual battery pack support for modular UPS configurations while minimizing the increase in device count by sharing common components between rectifier and balancing functions.
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 configuration reduces the number of devices, improves power density and reliability, allows independent boosting of positive and negative bus voltages, and enhances the scope of application by enabling power sharing between modules, while maintaining balanced load distribution without extra balancing devices.
Implementation Method 1
one end of the fourth bidirectional thyristor SCR6 is connected to the zero line of three-phase power; the other end of the fourth bidirectional thyristor SCR6 is connected to one end of the second inductor L2
Implementation Method 2
the cathode of the first unidirectional thyristor SCR4 and the other end of the first bidirectional thyristor SCR1 are both connected to the one end of the first inductor L1; the other end of the second bidirectional thyristor SCR2 and the other end of the fourth bidirectional thyristor SCR6 are both connected to the one end of the second inductor L2
Implementation Method 3
the two outputs of the three-phase fully controlled rectifier bridge are respectively connected to one end of the first capacitor C1 and one end of the second capacitor C2; the other end of the first capacitor C1 and the other end of the second capacitor C2 are both connected to the zero line of three-phase power
Implementation Method 4
the anode of the first unidirectional thyristor SCR4 and the cathode of the second unidirectional thyristor SCR5 are respectively connected to the positive end of the first battery packs BAT+ and the negative end of the second battery packs BAT−
Data Source
AI summary
The invention relates to a three-phase boost rectifier circuit and a control, method thereof, and an uninterrupted power supply which contains at least first battery packs BAT+, second battery packs BAT−, and a boost rectifier module; the boost rectifier module comprises a first bidirectional thyristor SCR1, a second bidirectional thyristor SCR2, a third bidirectional thyristor SCR3, a fourth bidirectional thyristor SCR6, a first unidirectional thyristor SCR4, a second unidirectional thyristor SCR5, a first inductor L1, a second inductor L2, a third inductor L3, a three-phase fully controlled rectifier bridge, a first capacitor C1 and a second capacitor C2. The invention can ensure the balance of positive and negative bus's voltage without the balancing device under battery operated boost mode, while improving the efficiency and reliability of the battery operated boost mode.