New Three-Phase Multilevel Inverter with Shared Power Switches

Ping, Hew Wooi,Rahim, Nasrudin Abd.,Jamaludin, Jafferi The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.5

Despite the advantages offered by multilevel inverters, one of the main drawbacks that prevents their widespread use is their circuit complexity as the number of power switches employed is usually high. This paper presents a new multilevel inverter topology with a considerable reduction in the number of power switches used through the switch-sharing approach. The fact that the proposed inverter applies two bidirectional power switches for sharing among the three phases does not prevent it from producing seven levels in the line-to-line output voltage waveforms. A modified scheme of space vector modulation via the application of virtual voltage vectors is developed to generate the PWM signals of the power switches. The performance of the proposed inverter is investigated through MATLAB/SIMULINK simulations and is practically tested using a laboratory prototype with a DSP-based modulator. The results demonstrate the satisfactory performance of the inverter and verify the effectiveness of the modulation method.

New Three-Phase Multilevel Inverter with Shared Power Switches

Hew Wooi Ping,Nasrudin Abd. Rahim,Jafferi Jamaludin 전력전자학회 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.5

Despite the advantages offered by multilevel inverters, one of the main drawbacks that prevents their widespread use is their circuit complexity as the number of power switches employed is usually high. This paper presents a new multilevel inverter topology with a considerable reduction in the number of power switches used through the switch-sharing approach. The fact that the proposed inverter applies two bidirectional power switches for sharing among the three phases does not prevent it from producing seven levels in the line-to-line output voltage waveforms. A modified scheme of space vector modulation via the application of virtual voltage vectors is developed to generate the PWM signals of the power switches. The performance of the proposed inverter is investigated through MATLAB/SIMULINK simulations and is practically tested using a laboratory prototype with a DSP-based modulator. The results demonstrate the satisfactory performance of the inverter and verify the effectiveness of the modulation method.

Design and Implementation of a New Multilevel DC-Link Three-phase Inverter

Ammar Masaoud,Hew Wooi Ping,Saad Mekhilef,Ayoub Taallah,Hamza Belkamel 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.2

This paper presents a new configuration for a three-phase multilevel voltage source inverter. The main bridge is built from a classical three-phase two-level inverter and three bidirectional switches. A variable DC-link employing two unequal DC voltage supplies and four switches is connected to the main circuit in such a way that the proposed inverter produces four levels in the output voltage waveform. In order to obtain the desired switching gate signals, the fundamental frequency staircase modulation technique is successfully implemented. Furthermore, the proposed structure is extended and compared with other types of multilevel inverter topologies. The comparison shows that the proposed inverter requires a smaller number of power components. For a given number of voltage steps N, the proposed inverter requires N/2 DC voltage supplies and N+12 switches connected with N+7 gate driver circuits, while diode clamped or flying capacitor inverters require N-1 DC voltage supplies and 6(N-1) switches connected with 6(N-1) gate driver circuits. A prototype of the introduced configuration has been manufactured and the obtained simulation and experimental results ensure the feasibility of the proposed topology and the validity of the implemented modulation technique.

Design and Implementation of a New Multilevel DC-Link Three-phase Inverter

Masaoud, Ammar,Ping, Hew Wooi,Mekhilef, Saad,Taallah, Ayoub,Belkamel, Hamza The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.2

This paper presents a new configuration for a three-phase multilevel voltage source inverter. The main bridge is built from a classical three-phase two-level inverter and three bidirectional switches. A variable DC-link employing two unequal DC voltage supplies and four switches is connected to the main circuit in such a way that the proposed inverter produces four levels in the output voltage waveform. In order to obtain the desired switching gate signals, the fundamental frequency staircase modulation technique is successfully implemented. Furthermore, the proposed structure is extended and compared with other types of multilevel inverter topologies. The comparison shows that the proposed inverter requires a smaller number of power components. For a given number of voltage steps N, the proposed inverter requires N/2 DC voltage supplies and N+12 switches connected with N+7 gate driver circuits, while diode clamped or flying capacitor inverters require N-1 DC voltage supplies and 6(N-1) switches connected with 6(N-1) gate driver circuits. A prototype of the introduced configuration has been manufactured and the obtained simulation and experimental results ensure the feasibility of the proposed topology and the validity of the implemented modulation technique.

Switching Functions Model of a Three-phase Voltage Source Converter (VSC)

Fazeli, Seyed Mahdi,Ping, Hew Wooi,Abd Rahim, Nasrudin Bin,Ooi, Boon Teck The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.2

The equivalent circuit of a three-leg, four-wire voltage source converter (VSC) is derived using switching functions. Simulations and experiments are conducted (i) to investigate the effects of the zero sequence on VSCs when a three-phase imbalance exists and (ii) to use the consistency of simulations and laboratory experiments to validate the equivalent circuit. The impact of a three-phase imbalance on the VSC has yet to be fully investigated because of the lack of an equivalent circuit to show rigorously how the zero sequence currents flow through the VSC.

Switching Functions Model of a Three-phase Voltage Source Converter (VSC)

Seyed Mahdi Fazeli,Hew Wooi Ping,Nasrudin Bin Abd Rahim,Boon Teck Ooi 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.2

The equivalent circuit of a three-leg, four-wire voltage source converter (VSC) is derived using switching functions. Simulations and experiments are conducted (i) to investigate the effects of the zero sequence on VSCs when a three-phase imbalance exists and (ii) to use the consistency of simulations and laboratory experiments to validate the equivalent circuit. The impact of a three-phase imbalance on the VSC has yet to be fully investigated because of the lack of an equivalent circuit to show rigorously how the zero sequence currents flow through the VSC.

Self-Tuning Fuzzy-Based Dispatching Strategy for Elevator Group Control Systems

Jafferi Jamaludin,Nasrudin Abdul Rahim,Hew Wooi Ping 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10

Fuzzy logic is recognized as an intelligent approach to complex problems demanding fulfillment of several criteria. A smart solution for an elevator group control system is one complex problem. This paper discusses a fuzzy logic dispatching strategy for elevator group control that uses a self-tuning fuzzy logic controller to tune membership functions and adjust fuzzy rule sets. Computer simulation evaluates, in three traffic peaks, the strategy’ effectiveness. The results, when compared with other strategies that use conventional controllers, show considerable overall improvements in both waiting time and riding time.

Direct Torque Control Permanent Magnet Synchronous Motor Drive with Asymmetrical Multilevel Inverter Supply

M. N. Abdul Kadir,Saad Mekhilef,Hew Wooi Ping 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-

This paper demonstrates the Direct Torque Control Permanent Magnet Synchronous Motor (DTC-PMSM) drive fed by asymmetrical multilevel inverter. The cascaded Hbridges topology with ratio-3 dc voltage sourced cells inverter has been employed. The DTC controller receives a reference torque and flux signals, the torque controller output determines the position of the desired flux vector. The amplitude of this vector is determined by the reference flux amplitude. The reference voltage vector is calculated as a continuous value using a technique developed originally for the SVM controlled drive. In this study, however, the reference voltage vector has been approximated to the nearest voltage vector achievable by one switching state of the multilevel inverter. The performance of two- and three-cells per arm inverter drives has been compared to that of the SVM-inverter drive at two values of the switching intervals. The results reflect the low switching frequency and torque ripple advantages of the proposed scheme.

Dual Vector Control Strategy for a Three-Stage Hybrid Cascaded Multilevel Inverter

Mohamad N. Abdul Kadir,Saad Mekhilef,Hew Wooi Ping 전력전자학회 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.2

This paper presents a voltage control algorithm for a hybrid multilevel inverter based on a staged-perception of the inverter voltage vector diagram. The algorithm is applied to control a three-stage eighteen-level hybrid inverter, which has been designed with a maximum number of symmetrical levels. The inverter has a two-level main stage built using a conventional six-switch inverter and medium- and low- voltage three-level stages constructed using cascaded H-bridge cells. The distinctive feature of the proposed algorithm is its ability to avoid the undesirable high switching frequency for high- and medium- voltage stages despite the fact that the inverter’s dc sources voltages are selected to maximize the number of levels by state redundancy elimination. The high- and medium- voltage stages switching algorithms have been developed to assure fundamental switching frequency operation of the high voltage stage and not more than few times this frequency for the medium voltage stage. The low voltage stage is controlled using a SVPWM to achieve the reference voltage vector exactly and to set the order of the dominant harmonics. The inverter has been constructed and the control algorithm has been implemented. Test results show that the proposed algorithm achieves the desired features and all of the major hypotheses have been verified.

Dual Vector Control Strategy for a Three-Stage Hybrid Cascaded Multilevel Inverter

Kadir, Mohamad N. Abdul,Mekhilef, Saad,Ping, Hew Wooi The Korean Institute of Power Electronics 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.2

This paper presents a voltage control algorithm for a hybrid multilevel inverter based on a staged-perception of the inverter voltage vector diagram. The algorithm is applied to control a three-stage eighteen-level hybrid inverter, which has been designed with a maximum number of symmetrical levels. The inverter has a two-level main stage built using a conventional six-switch inverter and medium- and low- voltage three-level stages constructed using cascaded H-bridge cells. The distinctive feature of the proposed algorithm is its ability to avoid the undesirable high switching frequency for high- and medium- voltage stages despite the fact that the inverter's dc sources voltages are selected to maximize the number of levels by state redundancy elimination. The high- and medium- voltage stages switching algorithms have been developed to assure fundamental switching frequency operation of the high voltage stage and not more than few times this frequency for the medium voltage stage. The low voltage stage is controlled using a SVPWM to achieve the reference voltage vector exactly and to set the order of the dominant harmonics. The inverter has been constructed and the control algorithm has been implemented. Test results show that the proposed algorithm achieves the desired features and all of the major hypotheses have been verified.