The system frequency converter provides a complete solution for medium voltage applications

The system frequency converter provides a complete solution for medium voltage applications PART 1 The WEG MVW3000 Series of variable speed drives has introduced new devices with many functions such as The MVW3000 medium voltage variable speed drive, which has an Efficiency, power density, and extremely high reliability, is sold as a complete system integrated in a distribution cabinet. WEG has also presented in the MVW3000 series of variable speed drives for voltages from 2.3kV to 8kV and power levels from 28 kW to 2,400kW. This family of devices is built with multilevel technology and Cascade H (CHB) bridges. The multilevel topology is based on the serial connection of three to ten low voltage (690 V) power modules with IGBT output converters in H-bridge configuration, depending on the output voltage. This allows reaching voltage levels in the medium voltage range using proven standard low voltage components (diodes, IGBT and plastic film capacitors) in a cost-effective manner. As a special feature, the MVW3000 is supplied as a complete system integrated into a distribution cabinet, including medium voltage isolator, fuses, multilevel power transformer, and frequency converter "The current-voltage and power range is only the first stage in the product evolution. Higher voltages and power levels are now available upon request, `` said Johannes Schwenger, head of Europe's low voltage and medium voltage product control systems at WEG. "

The MVW3000 is a high-performance all-in-one solution that eliminates the need for additional medium voltage switching devices. This variable speed transmission system has excellent input and output parameters, energy efficiency, and high availability, along with easy maintenance, modularity and smooth motor operation, this makes this variable speed drive system the ideal complement for all commercially available medium voltage motors and the perfect choice for retrofit projects thanks to its virtually output voltage sinusoidal ", if you want to know more about these new implements, join us in part 2 of this article. The MVW3000 variable speed drive system provides extremely high driving performance. The network power factor is greater than 0.95 over the entire engine speed range, without any additional harmonic filters or compensation capacitors. The integrated device architecture provides outstanding harmonic distortion figures for current and voltage (THD I / V and TDD) according to IEEE 519, IEC 61800-3 and G5 / 4-1. The device complies with the limits established in these standards, even in its basic configuration. The performance of the inverter, including the transformer, exceeds 95 percent over the entire motor speed range and is greater than 96 percent with load levels exceeding 40 percent. The charging circuit for the multilevel power transformer ensures the magnetization of the transformer core without starting currents and a smooth charge of the DC link capacitors for the inverter stage. 

The power transformer allows the adaptation of the mains voltage to the motor output voltage and the reduction of the common-mode voltage in the motor winding. It also reduces common-mode currents through motor bearings to maximize bearing life. The interfaces between the frequency converter CPU and the power stage for IGBT control, temperature monitoring, Voltage feedback, and current feedback are implemented using fiber optics to increase noise immunity and provide effective isolation between the control and power sections. The power stages (bridges H) are constructed with plastic film capacitors, semiconductor fuses and an automatic bypass function of the inverter to provide greater system availability in case of failure. Virtually sinusoidal output voltage and current reduce power dissipation, vibration and torque pulsation in the motor. In order to improve the reliability and availability of the system, the MVW3000 is equipped with motor protection devices for protection against overload, overheating and blocking of the motor rotor. 

The temperatures of the power stage and the transformer are also constantly monitored. As a packaging system, the MVW3000 simplifies installation and commissioning. The plug power stages facilitate maintenance and quick replacement. With dimensions of 3,900 x 2,210 x 1,100 mm (W x H x D), the variable speed drive system also has a small footprint. In addition, it can optionally be equipped with all the most common industrial communication protocols, including Modbus, Profibus, Devicenet, and Ethernet. 210 x 1,100 mm (W x H x D), the variable speed drive system also has a small footprint. In addition, it can optionally be equipped with all the most common industrial communication protocols, including Modbus, Profibus, Devicenet, and Ethernet. 210 x 1,100 mm (W x H x D), the variable speed drive system also has a small footprint. In addition, it can optionally be equipped with all the most common industrial communication protocols, including Modbus, Profibus, Devicenet, and Ethernet.