Four-switch Three-phase Inverter Research Articles

Dual-Vector-Based Predictive Torque Control for Fault-Tolerant Inverter-Fed Induction Motor Drives With Adaptive Switching Instant

Four-switch three-phase inverter (FSTPI) is widely applied as a fault-tolerant topology of six-switch three-phase inverter (SSTPI) with an open-phase fault or as a cost-effective topology due to the reduced semiconductor power switches. However, conventional single-vector-based predictive torque control (SV-PTC) for FSTPI-fed induction motor (IM) presents poor steady-state performance and requires high sampling frequency. To address these issues, a dual-vector-based PTC (DV-PTC) for FSTPI-fed IM with adaptive switching instant is proposed in this article. Therein, two optimal voltage vectors are determined in each sampling period, and a simplification strategy for selecting the optimal voltage vectors is established. A switching instant adaptation scheme is developed to improve the steady-state performance of machine control. An optimized overmodulation strategy is proposed to improve the transient-state performance of machine control and reduce the computational burden in digital implementation. Extensive experimental studies validate the effectiveness and superiority of the proposed DV-PTC scheme.

Modulated Model Predictive Torque Control for Fault-Tolerant Inverter-Fed Induction Motor Drives With Single DC-Link Voltage Sensor

Four-switch three-phase inverter (FSTPI) is widely used as a cost-effective fault-tolerant topology of six-switch three-phase inverter with an open-phase fault. To solve the inherent dc-link capacitor voltage offset (CVO) issue of FSTPI, two dc-link capacitor voltage sensors are required in conventional model predictive torque control (MPTC) strategies. To improve the reliability and reduce the cost of induction motor (IM) drives, a modulated MPTC (M-MPTC) for FSTPI-fed IM with single dc-link voltage sensor is proposed in this article. Therein, the relationship of the CVO and the load current is established to obtain the fundamental component of CVO. The two capacitor voltages are reconstructed by single dc-link voltage sensor and the fundamental component of CVO. To suppress the CVO, a cost function that only contains the output voltage vector is designed. The inner relationship between the proposed M-MPTC with single dc-link voltage sensor and the conventional M-MPTC with two dc-link voltage sensors is derived. To retain the load current within the allowed range, a current constraint scheme is proposed and integrated into the M-MPTC. Various simulation and experimental studies are carried out to verify the effectiveness of the proposed strategy.

A Quasi-Z-Source Four-Switch Three-Phase Inverter With Null Vector Capability

In this paper, a novel structure for a four-switch three-phase inverter with the ability of creating a null vector is proposed. This structure utilizes a symmetrical quasi-Z-source network and generates zero output voltage during the shoot-through state, which is similar to the null vector in the conventional six- switch inverter. This vector is used for the remaining time for each switching period. This means that the proposed structure has several advantages over the conventional four-switch inverter, in which two active vectors with opposite directions are necessary for synthesizing a null vector. These two vectors increase the switching losses due to the current circulation through these active states. Moreover, the number of switching states increases because of applying two opposite vectors. However, this problem does not exist in the proposed topology. To decrease the output current distortion and to minimize the number of switching events per each cycle, a new switching pattern is proposed, too. Also, fluctuations of the two split capacitors in the dc-link are considered in the closed-loop modulation method, which balances the output voltages and decreases current THD by 0.7%. To validate the proposed topology and the given pulse width modulation approach, its mathematical analyses are given here. Also, simulations and experimental verification have been performed on a 1 kW prototype inverter.

Utilization of a Reduced Switch-Count Topology in Regenerative Cascaded H-Bridge (CHB) Medium-Voltage Drives

This article employs a reduced switch-count topology in regenerative cascaded H-bridge (CHB) motor drives. Conventional regenerative CHB drive employs six-switch voltage source converters in the front end of each power cell to capture and utilize the regenerated energy. This solution is accompanied by a high number of switches, gate drives, and control circuits, especially when the number of levels increases. This causes high switching power losses, and increase in the cost, size, and weight of the overall system. This article utilizes a four-switch three-phase inverter active front end to reduce the switch count of the CHB power cell. The utilization of the four-switch inverter creates several challenges in terms of voltage imbalance on the capacitors and harmonics on the grid side. First, these challenges in medium-voltage operation are analyzed and addressed. Then, a new phase alternation connection method and two carrier phase-shifting techniques are proposed in this article to address the input current harmonics and comply with the grid connection standards. The performance of the proposed configuration and control techniques is analyzed theoretically and with simulation studies. The feasibility of the proposed configuration is validated experimentally on a scaled-down seven-level regenerative CHB drive.

Soft-switching inverter investigation for three-phase IM drive as wind turbine emulator design

Thanks to their high reliability, minimum maintenance and reduced cost, induction motors (IM) are commonly used in industry applications especially in renewable energy field. In this paper, a three-phase IM drive based on soft-switching structure is investigated for wind profile emulation. A specific space vector modulation (SVM) for the four-switch three-phase inverter (FSTPI) is applied to select the appropriate three vectors which synthesize the desired output voltage. Although this technique seems to be complicated in terms of hardware implementation since no zero vector is used and only three active vectors are considered, it has less total harmonic distortion, larger linear modulation range and better DC bus use. The proposed approach based on compensation, which ensures a feasible alternative for low-cost motor drives, fed the IM to react effectively as a wind turbine emulator in research laboratory by controlling the speed waveform. Software and hardware results show that the system has a good static and dynamic performance. The presented curves demonstrate the control scheme accuracy for trajectory tracking under sudden load variation.

A NEW MULTI-MOTOR DRIVE SYSTEM BASED ON FOUR-SWITCH THREE-PHASE INVERTER TOPOLOGIES

Vietnam encourages greenhouse technology applications for high-tech agricultural production. The microclimate of greenhouses is the key factor for better plant growth. The greenhouse microclimate can be improved by control actions, such as heating, ventilation, and carbon dioxide enrichment to provide appropriate environmental conditions for crops. The multi-motor drive systems using six-switch three-phase inverter topologies are applied for greenhouse fans. In order to decrease to size and cost of effectiveness drive systems, the paper proposes a new multi-motor drive system based on four-switch three-phase inverter topologies which are applied to two-level hysteresis current controllers. The proposed solution has been tested to a four-permanent-magnet synchronous motor (PMSM) drive system. The simulation results are carried out to show the effectiveness of the proposed solution.

Hybrid Switching of Four-Voltage-Vector Model-Free Predictive Current Control for Four-Switch Three-Phase Inverter-Fed SynRM Drive Systems

Conventional model-based predictive current control (MBPCC) suffers from common drawbacks of high reliance on system model parameters and the use of a single input voltage vector that result in large pulsating current ripples and prediction errors. In the case of a four-switch three-phase inverter (FSTPI) topology, the implementation of the predictive controller is exacerbated due to limited numbers of candidate voltage vectors. This paper presents an integrated model-free predictive current control with a hybrid switching mechanism to solve the problem. The proposed method introduces the combined switching mechanism of input voltage vectors with fixed and variable modulations by increasing the number of switching voltage vectors. The four basic voltage vectors generated in the four-switch three-phase inverter create twenty-four new synthesized voltage vectors through fourfold linear expansions of the space vector plane. The switching durations of input voltage vectors are determined by calculating their optimal duty ratios. As a result, the proposed method improved the prediction accuracy by increasing the iteration calculations of current differences every sampling period. The proposed method, known as the hybrid switching of four-voltage-vector model-free predictive current control (HS-4VV-MFPCC), is practically tested <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">via</i> simulation and experimental works to evaluate its effectiveness and performance improvement.

A SVPWM algorithm based on four-switch three-phase inverter for PMSM under the imbalance of bus capacitor voltage

A SVPWM algorithm based on four-switch three-phase inverter for PMSM under the imbalance of bus capacitor voltage

Optimized Sliding Mode Control of Three-Phase Four-Switch Inverter BLDC Motor Drive Using LFD Algorithm

This paper presents a low-cost Brushless DC (BLDC) motor drive system with fewer switches. BLDC motors are widely utilized in variable speed drives and industrial applications due to their high efficiency, high power factor, high torque, low maintenance, and ease of control. The proposed control strategy for robust speed control is dependent on two feedback signals which are speed sensor loop which is regulated by Sliding Mode Controller (SMC) and current sensor loop which is regulated by Proportional-Integral (PI) for boosting the drive system adaptability. In this work, the BLDC motor is driven by a four-switch three-phase inverter emulating a three-phase six switch inverter, to reduce switching losses with a low complex control strategy. In order to reach a robust performance of the proposed control strategy, the Lévy Flight Distribution (LFD) technique is used to tune the gains of PI and SMC parameters. The Integral Time Absolute Error (ITAE) is used as a fitness function. The simulation results show the SMC with LFD technique has superiority over conventional SMC and optimization PI controller in terms of fast-tracking to the desired value, reduction speed error to the zero value, and low overshoot under sudden change conditions.

DRNN Robust DTC for Induction Motor Drive Systems Using FSTPI

In this paper, a self-tuning PI speed controller based on diagonal recurrent neural network is (DRNN) investigated and simulated to increase the robustness of the direct torque control (DTC) scheme for three-phase low-power IM drive system using a Four Switch Three-Phase Inverter (FSTPI). The drive is subjected to different system inputs and disturbances, step changes in speed under different load conditions, abrupt loading at high speed and speed reversal. Furthermore, the robustness of the controller is evaluated by varying motor parameter, stator resistance and moment of inertia. A comparison of classical and self-tuning PI speed controllers was presented to determine the effectiveness of the proposed controller. It is concluded based on simulation results using Matlab/Simulink. that the self-tuning PI speed controller provides the best performance by reacting rapidly and adaptively.

A new configuration for four-switch three-phase inverters based on aswitched-capacitor step-up cell for electric vehicles application

This paper proposes a new configuration for four-switch three-phase inverters based on a step-up switchedcapacitor cell, which is called switched-capacitor four-switch three-phase inverter (SCFSTPI). This converter includes eight power switches and two DC-link capacitors. Voltage step-up feature, high efficiency, integrated structure, and bidirectional power flow are the main contribution of this new configuration. A modified space vector modulation (SVM) strategy is presented to generate appropriate pulses for the converter. This modulation method also eliminates the effect of capacitors voltage imbalance problem on the inverter output voltage and current. Simulation and experimental results are presented and investigated to confirm the performance of this topology. Results validate the operation of the proposed topology and its modulation. SCFSTPI is applicable in electric vehicle (EV) drive systems and similar applications that need step-up inverters.

Rotor Position Alignment of FSTPI Based PMSM Drive Using Low Frequency Signal Injection

A PMSM drive with an incremental encoder or using sensorless control requires alignment to a predetermined rotor position (initial position) or initial rotor position detection at start-up. It is desired to lock the rotor to a known state (usually zero angle) at start-up if the initial rotor position detection is not available or difficult to obtain. In this work, a simple and proper zero angle initial rotor position alignment of four-switch three-phase (FSTP) inverter-based PMSM drive is proposed. Low-frequency voltage signal is applied to the d-axis voltage reference of the open-loop FSTPI based PMSM drive scheme without requiring complex trigonometric calculations, PI current regulators and current sensing. Therefore, fluctuated capacitor voltages at the DC-link are obtained allowing current flown through phase a locking the rotor with zero angle, properly. The proposed method has been implemented using a low-cost FSTP voltage source inverter (VSI) for PMSM drive with a floating-point TMS320F28335 DSP. The effectiveness and the feasibility of the proposed zero angle initial rotor position alignment method for PMSM driven by FSTP inverter have been demonstrated through experimental results.

Speed Control Using Fuzzy Controller for a Four Switch Sensorless BLDC Motor

- Brushless Direct Current (BLDC) motors are highly efficient motors with high reliability and a longer life span. The advent of sensor less technology has improved the performance and reliability of BLDC motor drives. This work is to analyze a drive system for BLDC motor with Four-Switch Three-Phase Inverter (FSTPI). Back Electromotive Force (EMF) Zero Crossing Detection (ZCD) method is used to estimate the rotor position. Speed control of motor is achieved by using Fuzzy Logic Controller (FLC) based closed loop control system. The Simulation was carried out using MATLAB software and motor the performance was analyzed with FLC for motor speed regulation.

A Simplified MPFC With Capacitor Voltage Offset Suppression for the Four-Switch Three-Phase Inverter-Fed PMSM Drive

This paper proposes a simplified model predictive flux control (S-MPFC) for a four-switch three-phase inverter (FSTPI)-fed permanent-magnet-synchronous-motor (PMSM) drive system with the consideration of capacitor voltage offset suppression. A stator flux compensator is introduced to fulfill the capacitor voltage offset suppression. A reference stator flux vector is obtained to represent the reference flux, the reference torque, and the capacitor voltage offset based on the ${\boldsymbol i}_{\boldsymbol d}$ = 0 control mode. Therefore, the flux vector is taken as the only control term in the cost function without any dreary weighting factor tuning work. Moreover, an offset flux error is defined according to the inherent features of the FSTPI, therefore, the optimal voltage vector can be selected in the stationary reference frame using a simple sector division and only one prediction calculation. Experimental results validate the effectiveness of the proposed S-MPFC.

Low-Cost Position Sensorless Speed Control of PMSM Drive Using Four-Switch Inverter

A low-cost position sensorless speed control method for permanent magnet synchronous motors (PMSMs) is proposed using a space vector PWM based four-switch three-phase (FSTP) inverter. The stator feedforward d q -axes voltages are obtained for the position sensorless PMSM drive. The q-axis current controller output with a first order low-pass filter formulates the rotor speed estimation algorithm in a closed-loop fashion similar to PLL (Phase Lock Loop) and the output of the d-axis current controller acts as the derivative representation in the stator feedforward voltage equation. The proposed method is quite insensitive to multiple simultaneous parameter variations such as rotor flux linkage and stator resistance due to the dynamic effects of the PI current regulator outputs that are used in the stator feedforward voltages with a proper value of K gain in the q-axis stator voltage equation. The feasibility and effectiveness of the proposed position sensorless speed control scheme for the PMSM drive using an FSTP inverter are verified by simulation and experimental studies.

Three-Switch Three-Phase Inverter With Improved DC Voltage Utilization

This paper proposes a new DC-AC converter with a less number of semiconductor switches and therefore gate drive and control circuit components. A salient feature of this inverter is its pure sinusoidal line-to-line voltages with no need for output filter. Also, the proposed inverter improves the voltage utilization factor of the input dc supply compared to four-switch three-phase inverter (first best topology in the literature from the number of switches point of view) and standard six-switch inverter with sine PWM. The proposed inverter is capable of operating with a wide range of output voltages from zero to the full value of the dc input voltage by appropriately altering instantaneous duty-cycle. For the first time to our knowledge, in this paper, a three-phase universal inverter with only three power-switch has been proposed. For the purpose of providing a good compromise between fast transient response and stability, a model predictive controller is proposed. All the design expressions have been derived. A comparison with other DC-AC converters is given to show the merits of the proposed converter. Finally, satisfactory circuit operation is confirmed by experimental results from a laboratory prototype.

Power Factor Correction of Four-Switch Three-Phase Inverter-Fed Sensorless Induction Motor Drives with Partial Electrical Free Measurement

In this article, a novel partial electrical free measurement method to improve the power-factor of four-switch three-phase (B4) inverter for sensorless induction motor drives is proposed. This method uses a simple-free of measuring current or voltage for the power factor correction circuit. The proposed controller of the B4 inverter improves the power factor to be closed to a unity with a high power quality performance and with a minimum total harmonic distortion of the supply current. The complete drive system is carried out utilizing Matlab/Simulink. Also, it is executed in real-time using a prototype system composed of a dSPACE DS-1104 digital control board and a laboratory 1.1 kW three-phase squirrel cage induction motor. The simulation and experimental waveforms prove the efficacy of the proposed drive system under various operating conditions. It is found that the proposed drive system has a reduced number of switches and sensors with a minimum cost which suitable for low commercial power applications. Moreover, it enhances noise isolation between power circuit and controller.

Hybrid predictive control strategy for a low‐cost converter‐fed IM drive

The converter consisting of a single-phase half-bridge rectifier and four-switch three-phase inverter is a low-cost power converter with complicated operating constraints. It is difficult to control by the conventional strategies. This study proposes a hybrid predictive control strategy with dual loops for this converter. In the outer loop, a proportional–integral controller is designed to regulate the dc-link voltage, capacitor voltage balancing, and the speed and flux of induction motors (IM). Also, in the inner loop, the finite set model predictive control is employed to control the ac input current and stator currents of the IM. The major advantages of the control strategy include: (i) easy to deal with complicated constraints and manage multiple control targets; (ii) without the need of modulators; (iii) good dynamic response. The simulation and experimental results indicate that the proposed method can guarantee the stable operation and good performance.

Simplified MPCC for four‐switch three‐phase inverter‐fed PMSM

A simplified model predictive current control (MPCC) for four-switch three-phase inverter (FSTPI)-fed permanent magnet synchronous motor (PMSM) considering the periodic fluctuation of the capacitor voltages is proposed. After analysing the inherent features of the FSTPI-fed PMSM system, an offset voltage vector and an ideal reference voltage vector are defined, which allows to deal with the reference voltage in the ideal voltage vector plane. Thus, the sector division is simplified. Furthermore, a concept of virtual duty cycle is introduced to employ an equivalent null vector in the MPCC in order to reduce the current ripples. Combining with a simple sector division, the active voltage vector and its virtual duty cycle are determined with only one prediction. Comparative experimental studies between the conventional and the proposed MPCC are executed to validate the feasibility of the proposed simplified MPCC.

Direct Torque and Flux Control of a Four-Switch Three-Phase Inverter-Fed Synchronous Reluctance Motor Drives

This paper presents an application of direct torque and flux control (DTFC) for a four-switch three-phase inverter (FSTPI)-fed synchronous reluctance motor (SynRM) in which the saturation and iron losses' effects are involved in the machine control modeling. The DTFC switching technique for the SynRM fed by FSTPI in low-power and low-cost applications is implemented by imitating the six-switch three-phase inverter (SSTPI). By considering equal effective vectors depicted in SSTPI, the αβ stationary reference frame is represented by using six sectors. Similarly, the voltage space vector formation is constructed in FSTPI. Accordingly the SynRM performance under DTFC is precisely analyzed by considering the saturation and iron losses' effects. The DTFC behavior based on SSTPI- and FSTPI-fed SynRM is evaluated using Simulink benchmark. At different operating conditions, further simulation and experimental results of DTFC based on FSTPI dynamically confirm the effectiveness of the proposed control application on the SynRM.