Buck-Boost UPS Circuit for Voltage-Independent AC Backup
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Solution Overview
Problem
Existing uninterruptible power supplies (UPS) with voltage independent operation, such as those using delta conversion, are bulky due to DC storage requirements for harmonic compensation and complex magnetic flux monitoring, and are less advantageous with advancements in switch technologies like SiC and GaN, while users may only need independent voltage without frequency control.
Innovation Solution
A UPS circuit utilizing a buck-boost voltage converter with two switch arms and an inductance, capable of AC/AC conversion in normal operation and DC/AC conversion during power failures, allowing voltage regulation independent of the input network while maintaining frequency, and featuring toggle switches for polarity reversal to generate alternating voltage from a direct voltage source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If delta conversion with transformer is used for voltage independent UPS operation, then voltage control capability is improved, but device volume and weight increase due to DC storage capacity and transformer
Solution Approach 1:
The invention extracts and eliminates the DC storage capacity component from the delta conversion UPS architecture. By using a buck-boost converter that directly processes AC input voltage without requiring DC link storage, the patent removes the bulky DC capacitor bank while maintaining voltage independent operation capability.
Solution Approach 2:
The invention merges the voltage regulation function and power conversion function into a single buck-boost converter stage. This integration eliminates the need for separate DC storage and transformer components, reducing overall UPS volume while maintaining the ability to provide controlled voltage output independent of input voltage variations.
2Adaptability or versatility
If delta conversion with transformer is used for voltage independent UPS operation, then voltage control capability is improved, but device complexity increases due to magnetic flux monitoring
Solution Approach 1:
The invention extracts and eliminates the magnetic flux monitoring requirement from the control system. By using a buck-boost converter with direct AC input, the patent removes the need to monitor and control transformer magnetic flux, significantly simplifying the control architecture while maintaining voltage independent operation.
Solution Approach 2:
The invention replaces the complex magnetic flux monitoring and control mechanism with a simpler voltage-based control approach. The buck-boost converter uses standard voltage sensing and PWM control instead of requiring magnetic flux measurements, substituting a complex electromagnetic control system with a simpler electrical control system.
3Reliability
If traditional UPS architecture with DC storage is used, then harmonic compensation is achieved, but power density decreases due to bulky DC storage capacity
Solution Approach 1:
The invention extracts and eliminates the bulky DC storage capacity from the UPS architecture. By using a buck-boost converter that operates directly from AC input, the patent removes the large DC link capacitors while maintaining the ability to provide harmonic compensation through the converter's control mechanism.
Solution Approach 2:
The invention changes the operational parameters of the power conversion system by using high-frequency switching in the buck-boost converter. This allows the system to achieve harmonic compensation through controlled switching rather than through large DC storage capacitors, enabling smaller component sizes while maintaining power quality 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
The solution reduces the size and cost of the UPS, increases power density, and allows for flexible frequency control of the output voltage, addressing the bulkiness and complexity issues of prior art while meeting the need for independent voltage operation without frequency modification.
Implementation Method 1
a buck-boost voltage converter (110) having two input terminals (111, 112) and two output terminals (121, 122), the buck-boost voltage converter (110) comprising a first switch arm (B1) comprising a first switch (S1) and a second switch (S1c), a second switch arm (B2) comprising a second switch (S2) and a second switch (S2c), an inductance (L) connected between a midpoint of the first arm (B1) and a midpoint of the second arm (B2)
Implementation Method 2
The uninterruptible power supply circuit (100) may further comprise a set of switches (R1, R2, R3) configured to connect or disconnect the first AC electrical network (30) or the DC voltage source (40) to the buck-boost voltage converter (110)
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to an uninterruptible power supply circuit (100) configured to, in a first mode of operation, supply a second AC power network from a first AC power network (30); and, in a second mode of operation, supply the second AC power network from a DC voltage source (40).Said circuit includes a step-up/step-down voltage converter (110) comprising two input terminals (111, 112) configured to, in the first operating mode, receive between them an alternating voltage (V30) from the first network (30); and, in the second operating mode, receive a direct voltage (V40) from the direct voltage source (40); and two output terminals (121, 122) configured to, in the first and second operating modes, receive between them an alternating voltage (V50) from the second alternating electrical network; said step-up/step-down voltage converter (110) being configured to, in the first operating mode, perform an AC/AC conversion between the first alternating electrical network (30) and the second alternating electrical network.