4Q VFD         

Principle:

The Medium Voltage Frequency Converter produced by RXPE adopts the excellent performance, mature technology, safe and reliable power cell series connected multi-level technology.

Three-phase Medium Voltage AC power is supplied to a number of power cells via one dry type phase-shifting isolated transformer. After the wave superposition of power cells on each phase, adopt Y-shaped connection, will form a medium voltage high-quality sine wave output with low dv/dt. Even the motor is running at low speed, the high-quality sine wave output is guaranteed. The power loss of the motor due to the current harmonic distortion is greatly reduced, and the vibration of the motor induced by torque ripple is relieved. Fiber optic isolating technology is used for the control connection between control cabinet and power cabinet in order to prevent electromagnetic interference caused by energized devices, cables and so on.

                                                         Topology

Main Components:

Dry Type Phase-Shifting Isolated Transformer 

Dry type phase-shifting isolated transformer has the features such as maintenance proof structural design, air-forced cooling, cabinet installation and being equipped with temperature monitoring and overheating warning.

The voltage is stepped down from one Y-connected primary winding to multi- delta phase-shifting secondary windings which have certain phase displacement one another. The connection between these secondary windings to the front ends of drive enables a multi--pulse rectification. By this means, harmonics and the variation to the grid side which is caused by switch-on and switch-off actions of power devices are significantly reduced.

Advanced Controller

The controller of RXPE medium voltage drive is based on 32-bit DSP and FPGA. It contains different functional PCBs such as CPU board, digital board, analog board and so on.

Interconnection between controller and power cells are fiber optics, which isolates electro-magnetic interference. The reliability of system is improved significantly.

Power Cell

The type of power cell is AC-DC-AC, IGBT power devices are used as core power components, the most mature PWM technology is applied. The dynamic response of the system is fast, the switching loss of IGBT is low.

VSD