With this unrivaled expertise in electronics design, control, and manufacture Mitsubishi Electric delivers the highest reliability and highest efficiency in uninterruptible power supplies
Mitsubishi Electric has been at the forefront of technological advances in the design and development of uninterruptible power supplies for the past 25 years. Older UPS installations used transformer designs and Silicon-Controlled Rectifiers (SCRs) as power devices, which limited efficiencies to the 85-90% range. In the decade that followed, Mitsubishi Electric led the charge to drastically improve efficiencies with a series of revolutionary developments. The introduction of Insulated Gate Bi-Polar Transistors (IGBTs) delivered higher switching rates, and, with proper control, a more refined sine wave that provided better response to load transients. Mitsubishi Electric is the only brand of UPS that designs and manufactures its own semiconductors - knowing best how to control its electronics for highest reliability and maximum efficiency. The use of IGBTs inspired the concept of the 3-level topology transformerless UPS, which Mitsubishi Electric pioneered in 2008 with its 9900 series. Later, Mitsubishi Electric extended its development of SiC technologies into the MOSFET power devices used in the SUMMIT, a game-changing UPS introduced in 2015. Mitsubishi Electric's latest advancement has been the launch of the world's first 2 megawatt capacity UPS in 2017, the 9900CX.
Three level topology provides the base building blocks to create UPS products that are capable of >97% true online double conversion efficiency. First introduced to the North American UPS Market in 2008 in the 9900A series 3 phase UPS modules, Mitsubishi Electric now includes 3 level topology in all of its 480V UPS products. Mitsubishi has led the way in this technology and now has over ten years of experience in its design, construction, and operation. For more information on three level topology, see the Three Level Topology White Paper.
After the release of three level topology, Mitsubishi Electric pursued the next major advancement in UPS technology, Silicon Carbide (SiC). As the latest in high power semiconductor devices, SiC is the most disruptive technology in the power electronics industry since the invention of the Insulated Gate Bipolar Transistor (IGBT). UPS module construction utilizing SiC technology coupled with three level topology has led to the creation of the smallest, lightest, and most efficient UPS modules in the world. The SUMMIT Series® UPS features SiC technology. Module efficiencies of up to 99% in true online double conversion are achievable without the use of line interactive technology. For more information on Silicon Carbide Power Electronics, see the SiC White Paper.
The removal of the transformer from UPS modules is the key to achieving superior efficiencies. In order to do this, key elements of UPS design must be reviewed. These include harmonic content, system fault tolerance, negative and zero sequence currents and system grounding stability. Mitsubishi Electric’s Virtual Neutral provides the means to remedy all the adverse conditions that can be caused in a transformerless UPS. It also provides harmonic mitigation that is unparalleled in the UPS industry. This creates the perfect environment for the removal of excess transformers from the critical power path, greatly increasing overall UPS efficiency and reducing UPS footprints. Transformerless White Paper
Double conversion UPS modules provide uninterrupted power to critical loads. They do this by filtering and converting incoming utility power to DC power. They then convert the DC power to a perfect AC output from the inverter. The inverter is also supported by a DC source that may include batteries or flywheels. Through this process, a true double-online conversion UPS protects the critical load from any transient or voltage anomaly including surges, sags, swells and line drops.
Line interactive UPS modules are directly connected to the incoming AC power supply. They have the capability of running in double conversion but are normally operated via a secondary power path. This path provides unregulated power to the critical load and only interacts with the utility in the event it exceeds specified values. They run on utility power until the UPS senses a problem and switches to an alternate power source, typically battery of flywheel. The structure of a line interactive vs true online double conversion UPS leaves your site vulnerable to voltage transients and harmonic issues, and only provides a less than 0.3% efficiency gain over a double conversion Silicon Carbide based UPS module.
The line interactive UPS also tends to call upon the batteries more frequently than double conversion UPS modules, shortening the battery life and leading to costly battery change outs. If reliability is key, then double conversion is the best choice for critical loads.
There are many UPS configurations available when designing a critical load application. The complexity of each design varies based upon budgets, uptime requirements, risk aversion, maintenance plans, and existing infrastructure. These designs are typically broken down into four tiers. Each tier expands on the reliability and maintainability of the previous tier.
Each Tier has different advantages and disadvantages and choosing the right one for you can be difficult.