Currently, there are three main types of UPS systems on the market: standby, online, and line-interleaved.
Figure 1: Block diagram of standby UPS operation
A standby UPS, also known as an offline uninterruptible power supply, is a backup UPS. It directly supplies power to the equipment and charges the battery (Normal Mode). Once the mains power supply quality is unstable or there is a power outage, the mains power circuit will be automatically cut off, and the DC power from the battery will be converted to AC power to take over the power supply (Battery Mode) until the mains power is restored. "The UPS will only intervene to supply power when the mains power fails." However, the AC power converted from DC power is a square wave, which is only used to supply power to capacitive loads, such as computers and monitors.
Figure 2: Block diagram of online UPS operation
An online UPS operates in a way that isolates the mains power from the electrical equipment. The mains power does not directly supply power to the equipment. Instead, the mains power is converted to DC at the UPS and then split into two paths: one path charges the battery, and the other path converts back to AC power to supply power to the equipment. When the mains power quality is unstable or there is a power outage, the battery switches from charging to supplying power until the mains power is restored. The UPS is involved throughout the entire power consumption process.
Figure 3: Online Interactive UPS Operation Diagram
Line-interactive UPS operates in the same basic way as offline UPS. The difference is that although the line-interactive UPS does not provide power continuously like the offline UPS, it monitors the mains power supply status at all times. It has boost and voltage reduction compensation circuits, which correct the mains power supply status in real time when it is not ideal, reducing unnecessary "Battery Mode" switching and extending battery life.
As mentioned above, all types of UPS systems include an inverter, which can be categorized into push-pull, half-bridge, and full-bridge inverters. The following explanation will focus on the full-bridge inverter.
Figure 4: Full-bridge inverter circuit
In practical applications, driving MOSFETs and similar components requires both high driving capability and adequate isolation. Silicon Labs, a renowned precision mixed-signal supplier distributed by Worldway Electronics, offers the SI823X, which effectively solves this problem. More information and solutions regarding the SI823X can be downloaded from Worldway Electronics' e-commerce platform.
Figure 5: Internal module block diagram of the Worldway SI823X device
The Si823x drivers distributed by Worldway utilize Silicon Labs' proprietary silicon isolation technology, providing a UL1577 compliant 5 kVRMS withstand voltage and a fast 60 ns transmit time. Driver outputs can be connected to the same or separate ground wire for grounding, or to positive or negative voltage. Single control input (Si8230/2/3/5/6) or PWM input (Si8231/4) configurations provide TTL-compatible inputs with >400 mV hysteresis. High integration, low transmit latency, small form factor, and its flexibility and cost-effectiveness make the Si823x series ideal for MOSFET/IGBT gate driver isolation applications.
Therefore, in inverter circuit applications, the Worldway SI823X not only implements isolation and drive functions, but also PWM input and complementary output functions. In addition, it also has multiple protection functions. Specifically, it has the following features:
● Two fully isolated drivers are integrated within a single package;
● Up to 5 kVRMS input-to-output isolation;
● Maximum 1500 VDC peak driver-to-driver differential voltage;
● HS/LS and dual-drive versions;
● Maximum switching frequency of 8 MHz;
● 0.5 A peak output (Si8230/1/2);
● 4.0 A peak output (Si8233/4/5/6);
● Maximum transmission delay of 60 ns;
● Independent HS and LS inputs or PWM input version;
● Transient suppression >30 kV/μs;
● Overlap protection and programmable dead time;
● Operating temperature range: –40 to +125 °C;
● Certified by UL/VDE/CSA;
● Compliant with RoHS standards.
About Shih-Chiang
Founded in 1993, Worldway Advanced Semiconductor is a major distributor in Greater China for globally renowned semiconductor companies and test and measurement instrument companies, including Silicon Labs, Renesas Electronics, Rogers, Melexis, Alliance, Littelfuse, EPSON, Vincotech, Wima, Power Integrations, Shindengen, SMI, TT Electronics, Ricoh Microelectronics, and Keysight. It is also a key supplier to numerous electronics manufacturing and R&D companies. In addition to covering traditional industrial, communications, consumer, and automotive electronics sectors, its product portfolio brings cutting-edge technologies and innovative products to emerging markets such as the Internet of Things (IoT), connected vehicles, wearable devices, and smart mobile terminals.
As a technology-driven distribution company, Worldway also boasts a mature technical support team and systematic service processes, providing customers with professional services tailored to their needs, including new product introductions, rapid sampling, application consulting, solution and software design, development environments, after-sales support, and logistics. Worldway has 17 offices and a subsidiary, Xinhua Long, across China, employing 650 people.
On January 11, 2016, the Worldway Components e-commerce O2O smart hardware innovation service platform was launched, which will provide engineers with comprehensive technical support and a high-quality service experience.
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