ACS 5000

Based on the successes of the IGCT and PEBB technologies, ABB developed the Voltage Source Inverter Multilevel-Fuseless (VSI-MF) topology.

By combining power electronic building blocks higher voltages can be reached, enabling reliable and efficient operation of motors up to 6.9 kV.

Motor-friendly with low parts count
In order to get a sinusoidal voltage to the motor, the number of switching levels would have to approach infinity. However, too many switching levels decrease reliability and efficiency because the number of components increases.

The ACS 5000 topology provides the optimal solution because it has enough switching levels to enable the use of standard motors while at the same time keeping the parts count to a minimum.

Compared to other available solutions, the VSI-MF topology provides a number of advantages:

• Higher power density and smaller footprint
• Smooth output waveform suitable for standard motors
• Increased reliability
• Higher efficiency

PEBB

The heart of the inverter is the Power Electronic Building Block (PEBB). It replaces complex power electronics circuits with a single, multi-function device.

The very high power density of the PEBB is based on the use of snubberless IGCTs, enabling reduced parts count and a compact mechanical arrangement.

In 1999 ABB launched the ACS 6000, the first PEBB-based variable speed drive for single and multi-motor applications. Since its introduction, the ACS 6000 has gained an excellent reputation for high quality and reliability. As a result, ABB has the largest installed base of medium voltage multidrives worldwide.

Direct Torque Control

Direct Torque Control (DTC) is an optimized motor control method for MV drives that allows direct control of all the core motor variables. This opens up AC drive capabilities never before realized and offers benefits for all applications.

	Typical torque (T) response of a DTC drive, compared with flux vector control and open loop pulse width modulation (PWM). .
What is Direct Torque Control? Direct Torque Control (DTC) is a revolutionary motor control method for MV drives that allows accurate control of both motor speed and torque without pulse encoder feedback from the motor shaft. In DTC, stator flux and torque are used as primary control variables. The motor state calculations are updated 40,000 times a second (i.e. every 25 µs) in the advanced motor software model by the high-speed digital signal processor. Due to the continuous updating of the motor state and the comparison of the actual values to the reference values, every single switching in the inverter is determined separately. Maximized starting torque Precise torque control provided by DTC allows MV drives to provide maximized starting torque that is both controllable and smooth. .
Fast response to mains fluctuations and process side changes The exceptionally fast torque step response of MV drives means that it can respond to process and mains changes extremely fast. This enables easy handling of power-loss situations and sudden load changes. .
Reduced noise Because of the separately determined switching, MV drives have no fixed switching frequency. This eliminates resonances that cause irritating noise associated with MV drives using conventional PWM technology. . .

IGCT Technology

The medium voltage challenge Until now, the power switches for medium voltage drives have been either Gate Turn Off Thyristors (GTO) or Insulated Gate Bipolar Transistors (IGBT). For medium voltage applications, such devices force design trade-offs that increase the cost and complexity of power control systems. ABB is intimately familiar with these trade-offs. We have invested in and further developed these devices for many years. .
IGBT: Conventional transistorized approach Both low voltage and high voltage IGBTs have been used in medium voltage drives. IGBTs are fast switching but conduction losses are high at medium voltage levels and complicated series connections of multiple IGBTs are required. High voltage IGBTs have fewer series-connected devices relative to low voltage IGBTs, but conduction losses are even higher. Overall parts count increases resulting in bigger drives. Costs go up. Reliability goes down. .
GTO: Thyristor standard GTO technology is reliable and conduction losses at medium voltage levels are tolerable. The problem is that non-homogeneous switching requires huge additional circuitry for turn off. Again, parts count increases resulting in larger drives. Costs increase. Reliability decreases. .
IGCT: Specifically designed for medium voltage ABB is keenly aware of the need for a power-switching device that displays: High-speed switching like an IGBT Low-loss conduction like a GTO Reliability in a wide range of medium voltage applications
ABB has developed the simple solution based on proven technology: the Integrated Gate Commutated Thyristor (IGCT). This evolutionary technology consists of a redesigned GTO, which incorporates significant design breakthroughs. The new IGCT delivers fast, homogeneous switching and inherently low losses. The IGCT is used with Voltage Source Inverter (VSI) topology which is intrinsically less complex and more efficient compared to other topologies. The IGCT-based drives meets the complex medium voltage drive challenge. .
Streamlined technology requires fewer parts Depending on the voltage level, an IGCT-based medium voltage drive typically requires as little as one fifth the number of power semiconductor devices as existing low voltage IGBT solutions. IGCT’s lower losses mean less cooling equipment and higher inherent reliability. Fewer parts. Higher reliability. Simple solution. . .

Monitoring and diagnostics

The ACS 5000 is available with an intelligent monitoring and diagnostics system, which allows secure access to the drive from any location in the world. DriveMonitorTM allows remote real-time access to the drive. It supports monitoring, configuration, diagnostics and control of ABB drives independent of the implemented control method, thus also enabling the connection of existent installations. The optional tool consists of a hardware module inside the drive, as well as a software layer that automatically collects and analyses selected drive signals and parameters. Long-term monitoring functions deliver important information on equipment status, tasks needed and possible performance improvements. Diagnostic procedures and trending can cover not only the converter itself but other parts of the shaft train as well - everything according to customer needs and preferences. Benefits: Early detection to avoid costly repairs Reduction of process-critical faults Optimization of maintenance cost and schedule over the product life cycle Long-term statistics for optimization of process performance Easier root cause analysis - reduced Mean Time To Repair (MTTR)