Three-phase Three-level Rectifier Research Articles

A Fast Processing Discontinuous Control Strategy for Vienna Rectifier

In this paper, Vienna rectifier has been inspected as one of the prominent topologies among three-level switched-mode rectifiers. A fast processing discontinuous modulation strategy has been proposed with the aim of improving the rectifier’s performance. The proposed method not only takes advantage of special properties available in three-phase three-level rectifiers, but also reduces the control design complexity and the switching loss. Moreover, neutral point voltage balancing is inherently realized. To achieve these goals, the rectifier is decoupled into two 2-level boost converters in every defined region, leading to simple modulation algorithm and fast processing control strategy. The validity of the proposed technique has been verified via simulation and experimental results conducted on a laboratory prototype.

An SiC MOSFET and Si Diode Hybrid Three-Phase High-Power Three-Level Rectifier

The utilization of wide bandgap devices such as silicon carbide (SiC) diode and mosfet can significantly increase the power density and the efficiency of rectifier circuits. However, SiC-based circuits always suffer from the high cost of their power stage. In this paper, a highly efficient low-cost hybrid three-phase three-level rectifier is proposed. Instead of using SiC diode and Si IGBT, it consists of SiC mosfet and Si diode. It presents extremely low switching losses because the reverse recovery losses of all the Si diodes are eliminated. At the same time, the total device cost of this rectifier is much lower than the all-SiC-based rectifiers. Furthermore, half-bridge modules can be used to comprise the rectifier circuit, which makes it suitable for high-power applications. In this paper, the circuit operational analysis, simulation, and experimental results are given. A comparison is given to show the advantages of the proposed rectifier.

Parameter Plane Synthesis and Performance Investigation of a Three-Phase Three-Level Bidirectional Rectifier

Abstract In this paper, parameter plane synthesis of a three-phase neutral-point clamped bidirectional rectifier has been performed. The converter involves one outer-loop PI voltage controller and two inner-loop PI current controllers for the closed-loop control. D-partition technique has been employed for the precise design of the voltage controller. An experimental prototype of the converter has been developed, and the experimental investigation of the converter performance in closed loop has been carried out. DSP DS1104 of dSPACE has been used for real-time implementation of the designed controller. The converter gives a very good performance in steady state and dynamic state (for rectification as well as inversion modes of operation) using the designed controller parameters.

Average and hysteresis current-controlled three-phase three-level unity power factor rectifier operation and performance

Three-phase three-level rectifier (TPTL) is popular in present days for high-power application owing to its low blocking-voltage stress on the power switches (half of dc-link voltage). Such a rectifier can also operate as unity power factor (PF) converter as presented in this work. The rectifier input current controller can be operated with either fixed frequency or random frequency both with their advantages and shortcomings. In this study, the current controller is implemented with: (a) conventional hysteresis current control (random frequency) and (b) average current control (fixed frequency). The design issues and the performance of the two current modulation strategies are investigated and compared. Rectifier performance parameter, that is, THD and PF are evaluated and confirmed through hardware prototype results.

DSP-based implementation of capacitor voltage balancing strategy for a three-phase three-level bidirectional rectifier

Digital signal processing (DSP)-based implementation of a modified space-vector modulation strategy for balancing the DC-bus capacitor voltages of a three-phase neutral-point clamped bidirectional converter is presented. The proposed modulation strategy is simple in nature. It first identifies the switching states responsible for the unbalancing of capacitor voltages and then, based on the knowledge of polarity of capacitor voltage difference and direction of power flow, uses the appropriate redundant switching vectors to achieve the balancing of capacitor voltages. The analysis and control of the converter is described. The proposed control algorithm is validated through experimental results obtained on a laboratory prototype of the converter. The performance of the converter is found excellent in terms of the line-side and load-side power quality. A perfect balancing of the DC-bus capacitor voltages is achieved under balanced as well as unbalanced load conditions. The performance of converter is also investigated with distorted mains voltages and found satisfactory. DSP of dSPACE has been used for real-time simulation and implementation of the proposed control algorithm.

Enhanced Control Scheme for Three-Phase Three-Level Rectifiers at Partial Load

A prominent boost-type three-level topology (VIENNA Rectifier I), which proved to represent a cost-effective and highly efficient solution for switched-mode rectifiers is inspected toward its operation at discontinuous conduction mode (DCM). This mode of operation occurs not only at high input voltage in conjunction with low load currents but even at medium loading in the vicinity of mains voltage zero crossings. When this circuit is operated in DCM, additional measures are required for improved behavior to avoid conflicts with requirements on total harmonic distortion and regulations as well as safe operation in terms of voltage balancing and overvoltage protection. A detailed analysis of DCM and associated states is performed enabling determination and location of error voltages. Basic rules for the location of error voltages can be found. This leads to a novel optimized modulation and control scheme, facilitating designs without additional inductance. Selected simulation and measurement results prove the enhanced modulation scheme.

Unidirectional three-phase rectifier with high power factor

A three-phase three-level rectifier with less power switches is proposed. Four power switches with voltage stress of half DC bus voltage are used in the circuit. A carrier-based current control strategy is proposed to draw the sinusoidal line currents with nearly unity power factor. The switching signals for power switches are derived from the DC bus voltage controller and neutral point voltage compensator. The mathematical model of the rectifier is derived and the control scheme is provided. To verify the proposed operation scheme, performance characteristics are given by experimental results.