Model predictive control of multilevel cascaded converter with boosting capability – experimental results

Abstract

Abstract. The main goal of this paper is to present a five-level converter with the feature of output voltage boosting capability. Thanks to its modular construction and single DC source usage, 5LCHB converter becomes an important alternative for two-level converters operating with DC-DC converters that use bulky inductors. Furthermore, model predictive control (MPC) method is presented, which allows for boosting output voltage of presented converter while providing three-phase load current control and flying capacitor voltage stabilization. The last section describes a 5kVA laboratory model of five-level hybrid converter interfacing RL load and shows experimental results confirming theoretical analysis derived in previous sections. By applying modifications to classic multilevel converter topologies, another branch called hybrid converters was created.Hybrid converters integrate more than one converter topology into one. Each new topology has its own advantages and drawbacks and suits a certain application.The following examples of hybrid converter topologies can be listed out: -5L-HNPC -cascaded connection of 3L-NPC converter[11], -ANCP-5L -3L-NPC converter connected with 3L-FC converter [12], -3L-NPC connected with H-bridge [13], -5L-MLC 2 -[14] This paper presents an investigation of a novel hybrid converter topology -five-level cascaded H-bridge converter (5LCHB) with only one DC source and model predictive controller (MPC). According to [1,15] this converter brings the following features:-generation of boosted output voltage, -good quality of output waveform with low THD, -fast response to reference current change. Utilization of the model predictive controller (MPC) for 5LCHB converter was tested in [1,15]. The advantages of MPC control can be summed up as follows:-simple solution for multilevel converter compared to other control strategies, -elimination of PWM modulator, -simple implementation of capacitor voltage balancing. Among the disadvantages of the MPC control we may list:-requirement of fast processor for on-line optimization, -the knowledge of the load parameters. Previous publication concerning 5LCHB converter with MPC control used only simulation model [1,[15][16][17]. This work examines 5 kVA laboratory model of 5LCHB with the MPC control.

Bulletin of the Polish Academy of Sciences: Technical Sciences

“…Such properties were utilized to control methods presented in this article. With the wide range of possibilities in setting out the cost function, the FCS-MPC algorithm has been used for varied kinds of inverters such as multilevel inverters [10], current source converters [11] and active filters [12].…”

Passivity‐based control of MMC‐based active power filter under non‐ideal conditions

“…1,2 As a result, conventional two-level active power filters are commonly used in low voltage distribution system for its flexibility and relatively high economic value. 7,8 At present, conventional multilevel converter topologies such as flying capacitor converter (FCC), 9 diode neutral point clamped (NPC) converter, and cascaded H-bridge converter (CHB) 10 are used in medium system, which can overcome the drawbacks of two-level structure by improving in the voltage withstand level. 7,8 At present, conventional multilevel converter topologies such as flying capacitor converter (FCC), 9 diode neutral point clamped (NPC) converter, and cascaded H-bridge converter (CHB) 10 are used in medium system, which can overcome the drawbacks of two-level structure by improving in the voltage withstand level.…”

“…[3][4][5][6] However, the voltage withstand level of power electronic switching devices and the accuracy of harmonic compensation limit the application of conventional active power filters in medium/high voltage distribution systems. 7,8 At present, conventional multilevel converter topologies such as flying capacitor converter (FCC), 9 diode neutral point clamped (NPC) converter, and cascaded H-bridge converter (CHB) 10 are used in medium system, which can overcome the drawbacks of two-level structure by improving in the voltage withstand level. Compared with coupling transformer-based APF, the application of multilevel technologies reduces the size and losses of devices significantly.…”

Bulletin of the Polish Academy of Sciences: Technical Sciences

“…Automatic tuning of these controllers are traditional in industry and monitoring loops are commonly available for re-tuning whenever necessary [10][11][12]. Despite earlier efforts, automatic tuning of MPC has experienced little development over the last decades, while excelling in providing optimal solutions to complex systems based on good model predictors [13][14][15][16][17][18][19][20][21]. The tools commonly employed for relating process dynamics to controller parameters are based on academic insight, e.g.…”