Dusan Janik

Control of primary voltage-source active rectifiers of traction converter with medium-frequency transformer: Advantages of control unit combining DSP and FPGA

This paper investigates traction converter with medium-frequency transformer intended for modern suburban units. It describes proposed control of primary voltage-source active rectifiers with PR-controller completed by harmonic compensator. Developed control was implemented in control unit combining DSP and FPGA. Proposed control system properties are analyzed by experiments made on developed down-scale traction converter.

Universal precharging method for dc-link and flying capacitors of four-level Flying Capacitor Converter

This paper investigates universal start-up procedure for Flying Capacitor Converter (FLC). Main part of this procedure is pre-charging of the dc-link and flying capacitors. This method is usable for voltage pre-charging in rectifier as well as inverter mode of the multilevel FLC converter. This specific feature is based on use of converter topology and modification of converter switching pulses control. The proposed control improvements are designed to control particularly multilevel converters. The control system is implemented in development platform Multi Level Converter (MLC) interface for a four-level multilevel converter with flying capacitors. Its performance is investigated and evaluated by selected experiments made on a developed converter prototype of the rated power of 30 kVA. This paper also discusses behaviour of converter on occurrence of safe restart and shut-down procedure.

Complete development platform for multi-level converters and complex control algorithms

This paper describes the modular development control platform including dedicated supporting tools. The platform was specially designed for the multi-level converters control therefore it provides up to 48 (plus 24 optional) of PWM outputs thanks to additional FPGA utilization. The combination of DSP enabled microcontroller and the FPGA allowed us to split the computational tasks between these parts which significantly helps with highly complex algorithms implementation. Fast application development is supported thanks to the software drivers covering broad range of elemental functions including communication, DMA transfers, AD service routines and basic user interface. Also an enhanced set of FPGA entities featuring various modulator functionalities are provided. Dedicated tools involves fully insulated JTAG interface with developed software allowing the platform to be programmed by a single JTAG emulator. An application example based on four level FLC converter is presented.

Implementation of SVPWM algorithm without trigonometric functions

This paper investigates topologically independent vector modulation for multilevel converters. The investigate vector modulation is Space Vector PWM (SVPWM) which was implemented in FPGA and also tested in development board MLC interface with low-voltage prototype of three-level Neutral Point Clamped (3L-NPC) converter. The main advantages and disadvantages which were found out during implementation and hardware tests are also described in this paper.

Active voltage balancing control with phase disposition PWM for 4-level flying capacitor converter

This contribution investigates three-phase four-level FLC based indirect frequency converter supplied from a 6kV AC-grid. It describes proposed active voltage balancing control of both output voltage-source inverter and input active rectifier with PD-PWM. The results are verified by experiments made on down-scale prototype of converter of rated power of 35kVA.

Complete solution of 4-level flying capacitor converter for medium-voltage drives with active voltage balancing control with phase-disposition PWM

This paper presents three-phase four-level FLC based electric motor drive for mining application supplied directly from a 6 kV ac-grid. It describes complete control algorithms of the drive with active voltage balancing control. The proposed control is verified by experiments carried out on down-scale drive prototype of rated power of 35 kVA.

Modulator for 4-level flying capacitor converter with active voltage balancing control with P controllers

This paper presents modulator with active voltage balancing control for three-phase four-level FLC converter based electric motor drive for applications supplied directly from a 6 kV ac-grid. It describes modulation algorithm of the drive with phase shifted PWM modulation with balancing voltage of flying capacitor by using P controllers in the closed loop. The proposed control is verified by experiments carried out on down-scale drive prototype of rated power of 35 kVA.

Synchronization of grid-connected converters for single-phase systems

Single-phase grid-connected converters need to be synchronized with voltage/current fundamental component. This paper investigates and deeply evaluates four real-time estimators based on DFT, adaptive filter, least squares and SOGI, designed for high-quality 1st harmonic extraction. Presented theoretical results are confirmed by extensive experimental research made on developed converter prototypes.

Simulation and control of FLC converters for UPS systems

This paper is focused on simulation of the diesel or gas electric central, which is used for uninterruptible power supply (UPS) with permanent magnet synchronous generator (PMSG) and flying capacitor converters (FLC).

Modulator for 4-level Flying Capacitor Converter with Balancing Control in the Closed Loop

This paper presents a modulator with an active voltage balancing control for the three-phase fourlevel FLC converter based electric motor drive for applications supplied directly from a 6 kV ac-grid. It describes a modulation algorithm of the FLC converter by using the phase shifted PWM modulation with balancing voltage of the flying capacitor by using P controllers in the closed loop. The proposed control was verified by experiments carried out on the down-scale drive prototype of the rated power of 35 kVA.