A reduced switch-count SEPIC-based inverter for asymmetrical dual three-phase induction machines

This paper presents an indirect rotor-field oriented control (IRFOC) algorithm for symmetrical six-phase double-winding induction machines with four three-phase sub-winding sets. The presented algorithm introduces the ability to control the power flow between different sub-winding sets. Multiple three-phase induction machines are utilised for critical applications such as more-electric aircrafts, due to their high reliability and fault tolerant capabilities. In this paper, the proposed control scheme is utilising the auxiliary currents of each six-phase sub-motor to achieve full control of the sub-winding sets current amplitudes and consequently the power flow direction for each sub-winding set. A six-phase induction machine with double winding is utilised to validate the proposed control scheme. Four isolated voltage source inverters (VSIs) are used to supply each winding set of the machine. The double-winding six-phase induction machine controlled by the proposed IRFOC algorithm is simulated using Matlab/Simulink. Presented simulation results validate the ability of the algorithm to appropriately control the power flow of each sub-winding set.

Multiphase Induction machine offers numerous advantages compared to the conventional three phase induction machine. Among the different types, the six-phase induction machine is most common, due to the flexibility in converting a three phase to six phase. By splitting the phase belt of a three phase induction machine, a six-phase induction machine is realized. The areas of application of multiphase (>3) machines are enormous, mostly where reliability is paramount. This paper presents the analysis, modeling and simulation of a 5Hp, 50HZ, 4 pole, 24 slots asymmetrical six-phase induction machine for submarine application. With the help of MATLAB software, the models developed are simulated and results in the form of computer traces of the dynamic performance of the machine at start-up are presented and discussed. This investigation shows that the replacement of three phase with a six phase machine is both technically and economically advantageous.

This paper analyzes a six-phase two-motor drive, consisting of a six-phase voltage-source inverter (VSI), a six-phase induction machine, and a three-phase induction machine. Stator windings of the two machines are connected in series in an appropriate manner. This enables full decoupling of the dynamics of the two machines by means of vector control. Detailed mathematical modeling of the system is performed and the set of d-q equations, describing the two machines connected in series to a six-phase VSI, is developed. The resulting model clearly shows the possibility of independent vector control of the two machines, although a single VSI is used as the supply. An experimental rig is constructed and existence of the decoupled dynamic control of the two machines supplied from a single VSI is fully verified by extensive experimental testing.

The proportional–integral (PI) control is usually applied in synchronous reference frame to regulate the output voltage of three-phase voltage source inverter (VSI). However, the PI controller is constrained by the capability of suppressing harmonic and negative sequence components; besides, its direct application in single-phase VSI is limited. While the proportional–resonant (PR) control can track ac reference and achieve harmonic suppression in stationary frame for both single-phase and three-phase VSI. Due to the high order of the resonant controller, lots of efforts are needed during the parameter design to get a satisfactory performance, such as trial-and-error. In this article, the way to approximately reduce the order of the resonant controller in the discrete time domain is presented, and then a method of selective pole placement and cancellation for the PR control design used in VSI is proposed. With the proposed method, the closed-loop pole-zero distribution of the PR control structure used in the VSI is well handled, and the parameters of the feedback controller and the reference feedforward controller are directly calculated by placing the selected poles and zeros in desired positions. The procedure of the parameter design is facilitated, and the performance of the VSI with PR control is improved.

In this paper, a (PF) Power factor correction and power quality (PQ) improvement based BLDC motor drive proposed. Normally the permanent magnet BLDC motor drive connected with the diode bridge rectifier and high value of the capacitor due to which poor power factor and higher THD (Total harmonic distortion) value at the input side To overcome this difficulty SEPIC (Single-ended primary inductance converter) converter use to optimize the PF and THD value. The converter operates in discontinuous conduction mode to get the desired result. This scheme also used for speed control of BLDC motor by controlling the VSI (voltage source inverter) feeding the BLDC drive.

A new switching scheme, which combines conventional space vector modulation (SVM) and carrier-based pulse width modulation (CBPWM), is proposed for a three-phase four-leg voltage source inverter (VSI). The proposed algorithm is simpler than conventional three-dimensional space vector modulation (3-D SVM) and easy in implementation in a real-time DSP system, it avoids the selection of a prism and tetrahedron in a 3-D SVM, therefore alleviates the computation burden of the DSP. Also, the concept of near-state pulse width modulation (NSPWM) method, which is used in a three-phase three-leg inverter to reduce the common mode voltage (CMV) noises, can be adopted in this algorithm so as to reduce the common mode voltage for a three-phase four-leg VSI. The feasibility of the proposed modulation technique is verified by both computer simulation and experimental results.

In this study, a bidirectional DC-to-DC quadratic converter (BDQC) is designed and developed for the motoring and regenerative braking (RB) of a permanent magnet brushless DC (PMBLDC) motor for a light electric vehicle (LEV) application. A PMBLDC motor is deemed more suitable for an electric vehicle (EV) due to its high efficiency and torque density. In the present work, a BDQC of 1 kW is designed to drive a 1.1 HP PMBLDC motor through a conventional voltage source inverter (VSI). An EV’s load cycle is emulated using a highly inertial load driven by a PMBLDC motor during the converter’s boost mode operation. RB is a crucial factor in extending the driving range of EVs by efficiently utilizing battery power. The converter operates in buck mode during RB, and simultaneously, the back electromotive force (EMF) of the PMBLDC machine is boosted by the self-inductance of the PMBLDC motor and the VSI. The braking technique used in this work eliminates the traditional drawback of RB in buck mode, as the power is extracted even when the motor’s back EMF is lower than the battery’s voltage. The control strategy has been implemented using the TMS320F28335 DSP controller for a developed converter prototype of the converter and driving the PMBLDC motor. The experimental results are compared to the simulation results, and a good alignment has been found.

The uses of induction motor is ever-growing day by day because of its superiority and high efficiency over dc machine. So for wide range of use in the industry, this machine requires an efficient driver circuitry arrangement. Currently conventional Voltage Source Inverter (VSI) or Current Source Inverter (CSI) is dealing as key part in the field of induction motor driver circuit. These converters fail to perform at our desire level due to some crucial drawbacks like they can perform as either buck or boost operation and they contain considerable amount of harmonics as well as EMI noise. So we are trying to replace these traditional inverters by PWM control Z-Source Inverter (ZSI) which offers buck-boost operation capability by utilizing shoot through state and provides less EMI noise. This paper presents a comparative study among these three inverters. Firstly three MATLAB simulation model of Induction motor driver by using VSI, CSI and ZSI (having almost same environment) have arranged. Then some important motor characteristics such as rotor speed, electromagnetic torque, rotor current and stator current have observed for three system models at various loading conditions. The model using Z-source inverter exhibits efficient performance in all cases compared to the other models.

Since independent control of an AC machine requires only two currents, additional degrees of freedom that exist in multiphase (n>3) machines can be used for other purposes. One possibility is the series connection of the stator windings, in an appropriate manner, which enables independent control of a set of machines although a single multiphase voltage-source inverter (VSI) is used as the supply. The concept has been explored recently in a considerable depth. This paper examines an alternative to the series connection, parallel connection of a multitude of multiphase machines supplied from a single VSI. This eliminates a shortcoming of the series arrangement, the requirement to have open-end stator winding machines. The general principles of paralleling the multiphase machines to a single multiphase VSI are at first set forth, with the subsequent development concentrating on the two-motor five-phase drive system. Dynamic and steady-state models of the two-motor drive are developed, and the vector control scheme is explained. Theoretical findings are verified by extensive experimental investigation on a laboratory setup. It is shown that parallel-connected multiphase multimotor drives represent an advanced example of the well-known analogy between series and parallel connection in electrical engineering. The quality of dynamic performance is the same as with series-connected drive systems. However, parallel connection suffers from a number of serious shortcomings that will prevent its application in industry.

The major malfunction of Permanent Magnet Synchronous Motor (PMSM) in Electric Vehicle (EV) applications is an open-phase defect, which degrades motor efficiency and increases losses due to unbalanced phase currents. Traditional Fault-Tolerant Control (FTC) techniques, on the other hand, could suffer from the monitoring problems of sinusoidal-shaped current references. In this study, a proposed fault-tolerant approach for open-phase during the driving cycle and starting of the PMSM is suggested, which differs from earlier fault-tolerant techniques by suggesting a proposed compensating transformation matrix for current and voltage references in the d-q rotating reference frame will be translated to the phase current and voltage references of the two healthy remaining phases. The proposed setup enables the EV to be operated under open-phase fault-tolerant (OPFT) with simple controller and high performance. Furthermore, since the proposed system depends on a four-leg inverter, it has a higher fault-tolerance capability than the three-phase Voltage Source Inverter (VSI) technique, to also compensate the possibility of loss of any VSI leg, but for sure with additional cost of the overall drive system. Eventually, the simulation output results supported the suggested fault-tolerant approach under Field-Oriented Control (FOC) for different modes of operations.

Bus-clamping Pulse Width Modulation (PWM) is an effective method to reduce the switching loss in a three-phase voltage source inverter (VSI). In bus-clamping PWM scheme, the phase legs are switched using high frequency PWM signals for two-third of the line cycle, while for the remaining duration of cycle, the pole voltage is clamped to either positive or negative rail of the DC bus. In PWM operation of a half bridge, a dead-time is applied between the gate signals of complementary switches to ensure safe and reliable operation. However, introduction of dead-time leads to poor power quality, increased Total Harmonic Distortion (THD) and variation in actual voltage compared to the intended pole voltage. Moreover, when the bus-clamping technique is used, the PWM has both high frequency switching region and clamped region in a line cycle, and consequently, the undesired effects of dead-time are further aggravated. Therefore, in order to enhance the quality of output voltage, this paper presents a dead-time compensation strategy for a VSI operating with bus-clamping PWM. The proposed method calculates the required compensation term to be added on the modulation signal considering wide range of operating conditions. Additionally, the compensation includes a new strategy for low current conditions near zero-crossing to avoid distortion. The proposed method is verified by simulation and experiments in a three-phase VSI with a switching frequency of 100 kHz and a fundamental frequency of 60Hz.

In power electronics, the alleviation of the converter losses is the major target to accomplish higher efficiency and lower thermal stress that can pave the way to lifetime enhancement of devices. Hence, this paper intends to implement a novel variable switching frequency system for switching loss minimisation in a 3-phase Voltage Source Inverter (VSI). Here, the count of commutations is minimised by varying the switching frequency over the fundamental period. Here, the switching loss is reduced by optimising the modulation index and the reference angle of VSI with a novel hybrid optimisation model. The proposed novel hybrid optimisation model is constructed by hybridising the concept of Group search Algorithm (GSO) and Rider Optimisation Algorithm (ROA) and hence referred to as Bypass updated Group search Algorithm (BU-GSO). Finally, the performance of BU-GSO is evaluated over the traditional models in terms of convergence analysis, Total Harmonic Distortion (THD) as well. Moreover, the evaluation is accomplished with inductive load variation and restive load variation, respectively.

This paper demonstrates improved performance of a three-phase voltage source inverter (VSI) when digital multisampled space vector modulation is used. The modulator and the inverter controller are implemented entirely using a field-programmable gate array platform, thus achieving increased bandwidth with respect to a typical digital signal processor or microprocessor-based controller. Increased controller bandwidth results in lower output voltage harmonic distortion in the frequency range above the fundamental and below the switching frequency. Experimental validation is presented together with the analysis carried out using a state space model of a VSI with an output LC filter.

The sinusoidal pulse-width modulation (SPWM) technique is typically used for three-phase voltage source inverter (VSI) in low-voltage motor drives due to its simplicity and reliability. However, these VSI face increasing challenge to minimize electromagnetic interference (EMI) and increase power quality. This paper proposes a new SPWM switching based on a Bat-like reference signal that has the advantages of minimizing the output-voltage total harmonics distortion (THDv), lowering the switch rate of change in voltage (dv/dt), reducing the number of switching transitions, and increasing the peak and r.m.s. ac output voltage of the three-phase VSI. The proposed switching technique is verified using Matlab/Simulik on a 2-kW, 300-V three-phase VSI connected to an RL load. This technique shows improvement in reducing the output-voltage THDv by 36% and lowering the number of switching transition by 60% as compared to SPWM switching that is based on singlefrequency signal. Moreover, the dv/dt is low and the peak output voltage is increase by approximately 17%.

Nowadays, multiphase induction drives are used in electric vehicle applications to improve reliability and efficiency. These induction motors are controlled by using a multiphase voltage-source inverter (VSI). As the number of phases increases, the number of switching devices used in multiphase VSI also increases, which results in a reduction of the system efficiency and an increase in the cost. Among these multiphase drives, the six-phase drive is used more frequently in electric vehicular industries. A conventional six-phase VSI requires 12 switches to drive the six-phase machine. Also, conventional six-phase VSI requires more dc-link voltage than the boost six-phase VSI to drive the six-phase machine. In order to overcome the problems associated with the conventional six-phase VSI-controlled six-phase induction drives, this article proposes a nine-switch boost inverter (NSBI) for six-phase induction drive applications. The proposed NSBI has a single-input dc voltage source, and it provides six-phase ac output voltages. These six-phase output voltages are regulated by using modified nonsinusoidal pulsewidth modulation (MNSPWM) technique. The proposed NSBI with a six-phase induction motor is simulated using MATLAB/Simulink and validated using a field-programmable gate array (FPGA)-controlled hardware prototype. The verification of the proposed system during load-torque variations and winding-failure conditions is carried out.