Hoang M. Nguyen

Input Power Factor Compensation Algorithms Using a New Direct-SVM Method for Matrix Converter

An input filter is necessary for a matrix converter (MC) system to improve the input current quality with low harmonic components, as well as to reduce the input voltage distortion supplied to the MC. However, the input filters characteristics make the input power factor (IPF) obtained at unity only in the presence of high output loads, and the IPF degrades significantly under light-load conditions. In this paper, we propose a new direct space vector modulation (DSVM) method to achieve the required displacement angle between the input voltage and input current of the MC. A new switching strategy is introduced based on the maximum compensated angle. Then, power factor compensation algorithms using the new DSVM method to achieve the maximum IPF are presented, in which compensation algorithm I is based on using the input filter and power supply parameters to estimate the optimal compensated angle. Compensation algorithm II is subsequently proposed using a proportional-integral controller to overcome drawbacks presented in compensation algorithm I. Simulation and experimental results are shown to validate the effectiveness of the proposed compensation algorithms.

An adaptive carrier-based PWM method for four-switch three-phase inverter

This paper proposes an adaptive carrier-based pulse width modulation (PWM) for four-switch three-phase inverter. The balanced output currents are guaranteed by this proposed method instead of voltage oscillations across two dc-link capacitors. The linear over-modulation can be easily obtained with this new approach. Simulation and experimental results are shown to validate the feasibility of the proposed method.

A novel method of common-mode voltage reduction in matrix converters

This article proposes a novel direct space vector modulation (DSVM) strategy that can restrict the common-mode voltage of a three-phase-to-three-phase matrix converter and maintain sinusoidal input/output waveforms, as well as a unity power factor at the input side. The proposed control method has been developed using active, non-zero space vectors instead of zero space vectors. A new space vector modulation table is also presented with the space vector rearrangement. One advantage of the proposed method is a 42% reduction of the peak value of the common-mode voltage besides the lower harmonic components compared to the conventional DSVM method. Furthermore, the maximum voltage transfer ratio is unaffected by the proposed method. Simulation and experimental results are shown to validate the advantages of the proposed DSVM method.

New direct-SVM method for matrix converter with main input power factor compensation

Since the input filters characteristics design for matrix converter system: to reduce the high harmonic components at the main power supply current and to improve the input voltage distortion for matrix converter, the unity power factor at the main power supply side is only achieved at the high output load and decreases greatly at the light load conditions. This paper proposes a new direct space vector modulation (DSVM) method to achieve the required displacement angle between input voltage and input current of matrix converter. Firstly, this proposed DSVM method introduces new switching patterns for the controllable input power factor of matrix converter and secondly, the power factor compensation method is then suggested. Simulation results with inductive load (RL) and 5-HP induction motor are shown to validate the effectiveness of the proposed method.

Implementation of direct torque control method using matrix converter fed induction motor

This paper presents a study on direct torque control method (DTC) using matrix converter fed induction motor. The advantages of matrix converters are combined with the advantages of the DTC technique: under the constraint of unity input power factor, the required voltage vectors are generated to implement the conventional DTC method of induction motor. However, since the first idea about DTC method using MC fed induction motor was suggested by the current researches just focus on some simulation results and a little un-explicit experimental result is carried out. This paper describes the operation of induction motor under the DTC method in steady-state and transient conditions by the experimental results, the discussion about the trend of DTC method using MC is also carried out. Furthermore, the entire system of matrix converter configuration using 7.5 kW IGBT modules (FR35R12KE3V1) is explained in detail.

An investigation on direct space vector modulation methods for matrix converter

This paper presents an alternative direct space vector modulation (DSVM) method of matrix converter for a voltage transfer ratio less than 0.5. The principles of selecting suitable switching configurations based on a new sectors definition are described. Switching table for the alternative DSVM method is developed with the controllable input power factor. There are some advantages of the alternative DSVM method which are deeply considered as compared to the conventional DSVM method: lower total harmonic distortion (THD) of line-to-line output voltage and peak value of common-mode voltage reduced by 42%. Low switching loss is reduced considerably by a minimum number of switching commutations. Simulation and experimental results are shown to verify the effectiveness of the proposed DSVM method.

An approach of sparse matrix converter using Z-source network

This paper presents an approach of sparse matrix converter (SMC) using Z-source network. The SMC is implemented by connecting a controllable rectifier and the traditional inverter through a Z-source network. The Z-source can produce any desired output voltage by controlling the shoot-through time. Compare to the traditional three-phase SMC, the three-phase Z-source SMC has the same number of switches, however, this topology extends output voltage range. In this paper, the new modulation algorithm is applied for the rectifier stage to generate a constant local average dc-link voltage. The input power factor is nearly unity in the whole operating system. Analysis, simulation and experimental results are provided to demonstrate advanced features of three-phase Z-source SMC.

Adaptive Carrier-based PWM for a Four-Switch Three-Phase Inverter under DC-link Voltage Ripple Conditions

This paper proposes an adaptive carrier-based pulse width modulation (PWM) method for a four-switch three-phase (4S3P) inverter under dc-link voltage ripple conditions. The proposed method guarantees balanced output currents despite of the existence of the voltage oscillations across two dc-link capacitors. And also, this new approach achieves a linear over-modulation with calculation time reduction. Simulation and experimental results are given to validate the feasibility of the proposed method.

A study on rotor FOC method using matrix converter fed induction motor with common-mode voltage reduction

Currently, most of researches on matrix converter concerns about indirect rotor flux oriented control (FOC) method use MC indirect space vector modulation (SVM) technique. This paper introduces a direct rotor flux oriented control method using MC fed induction motor with the direct space vector modulation technique. Furthermore, the proposed technique of common-mode voltage reduction in direct space vector has been firstly applied to reduce the bad effect of common-mode voltage on induction motor. The under-rated speed and field-weakening regions has been examined to verify the operation of matrix converter under different load conditions. The experiments are carried out with 5 hp induction motor fed by matrix converter to show the high dynamic performance for the proposed control system.

A novel DTC-SVM method using matrix converter fed induction motor

This paper presents a novel DTC-SVM method for matrix converter fed induction motor. The advantages of DTC method are combined with the advantages of the matrix converter based on the direct space vector modulation (DSVM) technique. This proposed method provides a precious input power factor control capability beside the high control performances. Furthermore, the FFT spectrum analysis of the input current shows the better harmonic contents as compared to the conventional DTC method. The simulation results of 5HP induction motor control at both steady state and transient state are shown to verify the effectiveness of the proposed method.