A Six-Phase Series-Connected Two-Motor Drive With Decoupled Dynamic Control

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.

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.

The interest in multiphase drives has been steadily growing during the last decade due to the promising potentials offered by multiphase machines over conventional three-phase counterpart. In this context, six-phase induction machines are preferably used in many diversified high-power applications. Generally, thanks to its improved flux distribution, the asymmetrical six-phase winding topology fed from two three-phase voltage source inverters (VSIs) is commonly employed with isolated neutral points to prevent the flow of zero sequence currents and to limit the number of current controllers to four instead of five when neutral points are connected. In this paper, an innovative design of a six-phase dc-ac inverter is proposed for such type of six-phase ac machines based on the single-ended primary-inductance converter (SEPIC) topology. The proposed topology employs only four active-legs with eight switches with the same output voltage magnitudes as in conventional VSIs and without the mandatory dead-time between switches in the same-leg. Also, it naturally delivers a pure sinusoidal waveform at the output stage. The principle of operation of the proposed inverter topology is investigated in details and assessed through a detailed simulation study of an open-loop control system.

An efficient control of a series connected two-synchronous motor 5-phase with non sinusoidal EMF supplied by a single 5-leg VSI: Experimental and theoretical investigations

Decoupling control of two-motor dual three-phase permanent-magnet synchronous motor (PMSM) series-connected system can be realized by using proper phase transposition rules with a single supply from a six-phase voltage source inverter (VSI), which solved the control problem of two motors in series. Since the traditional two-vector SVPWM strategy, which is commonly used in three-phase system, exists 5 th and 7 th harmonics in x-y plane, making it hard to realize decoupling control of two-motor dual three-phase PMSM series-connected system. Meanwhile, the DC bus voltage utilization of carrier-based PWM strategy is lower. Thus one method, which adopted a TBTSB-SVPWM strategy with two modulators, was proposed in this paper. It ensures the inverter output voltage only contains two kinds of fundamental components required by the two seriesconnected motors with a single VSI, making it possible to realize decoupling control of two-motor dual three-phase PMSM series-connected system. Simulation results indicate that there is no influence on the other motor while the speed/load of any one motor changed, achieving the decoupling control of series-connected system, and the feasibility and validness of the proposed approach are verified.

In this paper, a standalone solar photovoltaic (SPV) power generating system is designed and modeled using a Cuk dc-dc converter and a single phase voltage source inverter (VSI). In this system, a dc-dc boost con- verter boosts a low voltage of a PV array to charge a battery at 24 V using a maximum power point tracking control algorithm. To step up a 24 V battery voltage to 360 V dc, a high frequency transformer based isolated dc-dc Cuk con- verter is used to reduce size, weight and losses. The dc voltage of 360 V is fed to a single phase VSI with unipolar switching to achieve a 230 Vrms, 50 Hz ac. The main objectives of this investigation are on efficiency improve- ment, reduction in cost, weight and size of the system and to provide an uninterruptible power to remotely located con- sumers. The complete SPV system is designed and it is modeled in MATLAB/Simulink. The simulated results are presented to demonstrate its satisfactory performance for validating the proposed design and control algorithm.

In this paper, the vector control of a parallel-connected two five-phase permanent magnet synchronous machines (PMSMs) drive supplied by a single current-controlled voltage source inverter is presented. This system consists of a two five-phase PMSMs; the stators windings of both machines are connected in parallel in appropriate manner by using of the phase transposition property, which allows a decoupled control of the two machines. Based on the mathematical model of the multi-machine drive system, the decoupled dynamic of each machine from the group is obtained using the vector control algorithm. The independent control is ensured by controlling the stator currents and the speed of each machine under vector control consideration. Selected simulation results are presented to validate the effectiveness of the proposed control method under various dynamic operating conditions.

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.

Multi-phase machines possess additional degrees of freedom, which can be utilised to control other machines within a multi-motor drive system. The stator windings of the multi-phase machines can be connected in series in such a manner as to enable independent control of each machine using vector control principles, although the complete multi-motor drive system is supplied from a single multi-phase voltage source inverter (VSI). One shortcoming of the series arrangement is the need to bring out to the terminal box of an n-phase machine both beginnings and endings of each phase. Parallel connection of machines would circumvent this shortcoming, since the machines can have the neutral point connected within the machine. This paper therefore discusses such a parallel connection of two five-phase machines. The drive configuration and a suitable control scheme are detailed and verification of the concept is provided by simulation. Dynamic model in the stationary reference frame is given and equivalent circuit representation of the parallel-connected five-phase two-motor drive system is developed. It is shown that, due to orthogonal relationship of the two planes that are used for independent control of the two machines, phasor approach can be applied at each of the two fundamental frequencies used to control the two machines. The paper finally explains that, although parallel multi-phase multi-motor drives are feasible and in principle offer the same quality of dynamic performance as series-connected multi-phase multi-motor drive systems, they do not hold a real prospect for industrial applications

This paper proposes a new harmonic elimination PWM (HEPWM) scheme for voltage source inverters (VSI) based on the curve fittings of certain polynomials functions. The resulting equations to calculate the switching angle of the HEPWM require only the addition and multiplication processes; therefore any number of harmonics to be eliminated and the fundamental amplitude of the pole switching waveform (NP1) can be controlled on-line. An extensive angle error analysis is carried out to determine the accuracy of the algorithm in comparison to the exact solution. To verify the workability of the technique, an experimental single phase VSI is constructed. The algorithm is implemented on a VSI using a 16-bit microprocessor. The results obtained from the test rig are compared to the theoretical prediction and the results of the MATLAB simulations.

Multi-phase converters are required mainly for feeding variable speed multi-phase drive systems. This paper discusses one such solution by using direct ac-ac converter (matrix converter) that can be used to supply a six-phase and three-phase two-connected motor drive system. Matrix converter based two-motor drive system is presented for the first time in this paper. Two stator windings of six-phase and three-phase machines when connected in series while the rotors may be connected to different loads. Appropriate phase transposition is introduced while connecting the series stator winding to obtain decoupled control of the two machines. This paper proposes a scalar modulation scheme with three intervals technique of three-phase to six-phase matrix converter supplying series-connected six-phase and three-phase induction machine drive system. The dynamic decoupling of each machine from the group is obtained using the direct vector control algorithm. Mathematical modeling of the series-connected two-machine showed the possibility of independent control of each machine in the group. The independent control is demonstrated by analyzing the characteristics of the stator current references and speed of each machine under direct vector control scheme. The viability of the proposed control techniques is proved using analytically and simulation approach

Three-phase induction machines are today a standard\nfor industrial electrical drives. Cost, reliability, robustness and maintenance free operation are among the reasons these machines are\nreplacing dc drive systems. The development of power electronics\nand signal processing systems has eliminated one of the greatest\ndisadvantages of such ac systems, which is the issue of control. With\nmodern techniques of field oriented vector control, the task of\nvariable speed control of induction machines is no longer a\ndisadvantage. The need to increase system performance, particularly\nwhen facing limits on the power ratings of power supplies and\nsemiconductors, motivates the use of phase number other than three,\nIn this paper a novel scheme of connecting two, three phase\ninduction motors in parallel fed by two inverters; viz. VSI and CSI\nand their vector control is presented.

Many Industrial drives include rectifier-inverter systems. For its simplicity, the voltage source inverter (VSI) is usually used. But, with the on-line generation of carrier based gating signal, the duality between VSI and CSI is extended. Accordingly, feedback control strategies with voltage source inverter, (VSI) such as vector control technique can be applicable with CSI. Moreover, the problems encountered with VSI and its effect on the machine can be avoided. This paper introduces a vector controlled five phase induction motor fed from five-phase PWM-CSI. The input dc-link current to the inverter is the output from a controlled three-phase rectifier through a calculated reference dc-link current from the inverter side. MATLAB/SIMULINK is used as an assessment tool for the proposed system.

태양전지는 일사량, 온도와 부하에 의해 크게 변동하기 때문에 가능한 한 많은 에너지를 얻기 위해서는 태양전지의 출력을 항상 최대로 제어할 필요가 있다. 태양전지의 출력은 직류이므로 교류부하에 적용하기 위해서는 전력변환장치 중 인버터가 필수적이며 단위 역률을 갖는 정현파 전류 및 전압을 부하계통에 공급해 주어야 한다. 본 논문에서는 태양광 발전시스템을 승압 쵸퍼와 단상 PWM(Pulse Width Modultion) 전압형 인버터로 구성하였고, 안정된 변조를 위해서 동기신호와 제어신호를 원칩 마이크로프로세서에 의해서 처리하였다. 전력비교에 따라 시비율을 변화시키지만 태양전지는 전형적인 수하특성을 갖고 있어, 일사량과 온도변화에 관계없이 항상 최대 출력 점을 추적하도록 승압초퍼를 제어하였다. 단상 PWM 전압형 인버터는 태양전지가 연속 발전할 수 없는 단점을 보완하기 위해 일반 상용전원과 연계함으로써 약 $10{\sim}20%$ 전력절감효과를 얻을 수 있는 에너지절약 전원복합형 전력변환장치로 구성되어 있다. 단상 PWM 전압형 인버터와 위상동기를 위해서 계통전압을 검출하여 계통전압과 인버터 출력을 동상 운전하므로 잉여전력을 계통과 연계할 수 있게 하여 고 역률과 저고조파 출력을 유지 하므로써 부하와 계통에 전력이 안정하게 공급될 수 있도록 제어하였다. 【The solar cells should be operated at the maximum power point because its output characteristics were greatly fluctuated on the variation of insolation, temperature and load. It is necessary to install an inverter among electric power converts by means of the output power of solar cell is DC. The inverter is operated supply a sinusoidal current and voltage to the load and the interactive utility line. In this paper, the proposes a photovoltaic system is designed with a step up chopper and single phase PWM voltage source inverter. Synchronous signal and control signal was processed by one-chip microprocessor for stable modulation. The step up chopper is operated in continuous mode by adjusting the duty ratio so that the photovoltaic system tracks the maximum power point of solar cell without any influence on the variation of insolation and temperature for solar cell has typical dropping character. The single phase PWM voltage source inverter is consists of complex type of electric power converter to compensate for the defect, that is, solar cell cannot be develop continuously by connecting with the source of electric power for ordinary using. It can be cause the efect of saving electric power, from 10 to 20%. The single phase PWM voltage source inverter operates in situation, that its output voltage is in same phase with the utility voltage. The inverter are supplies an ac power with high factor and low level of harmonics to the load and the utility power system.】

The development of electrical energy sources continues to grow along with the development of electrical energy, in line with the increasing electricity demand. One of the power plants developed uses a three-phase induction electric machine. Several studies have been conducted on this electric machine because of its many advantages, such as simple construction, easy control, low maintenance, and affordable machine prices. Three-phase induction machine analysis has been carried out. It is necessary to study the effect of rotor rotational speed on the power factor of laboratory-scale induction machines. The trick is to operate a three-phase induction machine with a network-connected operating mode. This research method requires an excitation current in the form of reactive power from the network. The prime mover drives the mechanically connected induction machine by increasing the rotational speed of its rotor. This technique is used to prove the change in the power factor of a three-phase induction machine and its effect when the rotational speed is changed. The results of the study are used to prove the analysis of the research that has been done so that the value of the power factor will be better when the rotational speed of the three-phase induction generator is increased.