Five-leg Inverter Research Articles

Speed and Position Estimator of Dual-PMSM for Independent Control Drives using Five-Leg Inverter

<p>Nowadays, A lot of industry requires Multi Motor System (MMS)<strong> </strong>applications such as propulsion and traction power, HEV, conveyer and air-conditioner. The Conventional arrangement for MMS usually done by cascading the motors drives which each drives has individual inverter. Part of MMS, Dual-Motor drives fed by a single inverter is being paid attention by the researchers. Dual-motor drives using a single three-leg inverter<strong> </strong>has its limitation in the case of different operating conditions and independent speed control requirement. Therefore, dual-Motor drives using a single Five-leg Inverter (FLI) was proposed for independent control for both motors. In PMSM drives, the information of the feedback speed and rotor angular position is compulsory for variable speed drives. Conventional solution is by using speed sensor which will increase size, cost, extra hardwire and feedback devices, especially for the case of dual-PMSM drives. The best solution to overcome this problem is by eliminating the usage of speed and position sensors for Dual-motor drives. This paper presents a new sensorless strategy using speed and position estimator for Independent Dual- Permanent Magnet Synchronous Machine (PMSM) drives which utilize Five-Leg Inverter (FLI). The proposed strategy is simulated using MATLAB/Simulink to evaluate the overall motor drive performance. Meanwhile the experimental set-up is connected to dSPACE 1103 Board. The experimental results demonstrate that the proposed estimator is successfully managed to control the Dual-PMSM drives for variation of speed and for different direction applications.</p>

철도차량 추진시스템을 위한 FLI(Five-leg Inverter)의 성능 분석

본 논문에서는 철도차량 추진시스템을 위한 3-레그 인버터와 5-레그 인버터의 성능을 비교/분석하고 철도차량에 5-레그 인버터를 적용함에 있어 최적의 동작 조건을 제시한다. 5-레그 인버터는 두 대의 3-레그 인버터에 비해 2개의 스위치가 감소되며, 하나의 제어보드로 두 대의 3상 전동기를 독립적으로 제어할 수 있다. 이로 인해 두 대의 3-레그 인버터를 이용할 경우보다 시스템의 비용 감소와 소형화가 가능하다. 본 논문에서는 먼저 도시철도 차량에서 사용중인 유도전동기 제어 기법과 PWM 방법을 분석한다. 다음으로 5-레그 인버터의 기본 동작과 특징을 분석한다. 이러한 분석을 바탕으로 동일한 유도전동기 제어 기법과 PWM 방법을 3-레그 인버터와 5-레그 인버터에 적용했을 때 유도전동기의 속도와 토크 특성을 비교하고 분석한다. This paper analyzes the performance of two three-leg inverters and a five-leg inverter and proposes the optimal operation conditions in applying the five-leg inverter for the train propulsion system. The five-leg inverter offers a saving of two switches compared with the standard two three-leg inverters and it is possible to control two three-phase motors independently by using a control board. All of these features lead to a potential reduction in capital cost and miniaturization of system. In this paper, first, the analysis of the existing motor control method and PWM method for two-traction motor drive of urban railway is implemented. Next, the operation principle and performance of five-leg inverter is introduced. Through the analysis, when it applies the same motor control method and the same PWM method for three-leg inverter and five-leg inverter, the characteristic of motor's speed and torque is compared.

Direct torque control of five-leg inverter-dual induction motor powertrain for electric vehicles

This paper deals with the adaptation and implementation of an adaptive direct torque control for the five-leg inverter-dual induction machine drive. The expectations are to take advantage of the direct control benefits, which are: sensorless, ease of implementation, and robustness against parameters variation. The application focuses on an electric vehicle with two driving wheels. For this, both induction motors coupled to the driving wheel are fed through a five-leg power inverter. For that purpose, the structure of this vehicle requires an electric differential, which allows maintaining the stability of the vehicle and especially during cornering. For this, the proposed direct control can ensure the separate control and distribute the required torques to the induction motors. Experiments and simulations are carried out to show that the developed independent control of five-leg inverter is effective and provides a simple configuration with good performance in terms of speed and torque responses.

An Integrated Drive for Two PMSMs Involved Automotive Applications and Development of Current Reference Expanded Two Arm Modulation Technique

A five leg inverter (FLI) control is incorporated to drive two independent rated permanent magnet synchronous motors (PMSMs) for automotive applications. Literature evidences many attempts of employing the FLI for controlling two general purpose/special motors, where variety of modulation techniques has been practiced for performance enhancement. Also in these cases one leg of inverter is common to both the motors. The expanded two arm modulation (ETAM) has been generally engaged in FLI. In ETAM the percentage voltage utilization factor (VUF) is calculated based on “αmax”, where “αmax” is the maximum modulation index and equal to and hence it restricts the VUF to 50%. This makes the FLI drives to use the dc link in inefficient way, which is due to the fact that conventional ETAM works with voltage reference. This paper modifies the ETAM in an ingenious way to improve the VUF further through current reference. In addition, the developed current reference expanded two arm modulation (CRETAM) minimizes the current harmonics and torque ripple as well. A detailed comparison of the CRETAM with the conventional ETAM and the competent digital counterpart, space vector pulse width modulation (SVPWM), is also presented. The enhancement in VUF, torque ripple minimization and current total harmonic distortion (THD) reduction are found in the MATLAB based simulation results.

Development of a Three-to-Five-Phase Indirect Matrix Converter With Carrier-Based PWM Based on Space-Vector Modulation Analysis

This paper proposes an indirect matrix converter (IMC) topology to supply a five-phase load directly from three-phase ac power sources without bulky electrolytic capacitors and explains its operating principle. Using the emerging topology, which combines the five-leg inverter into the rectifier stage of the conventional IMC, the three-to-five-phase IMC topology reduces the number of power switches and results in a simpler commutation compared with the conventional three-to-five-phase direct matrix converter. In addition, a simple approach to realize the carrier-based pulsewidth modulation (CBPWM) method for a three-to-five-phase IMC is presented, and the proposed CBPWM method is analyzed based on the space-vector approach. As a result, the IMC with the proposed CBPWM method can be more easily implemented compared with IMCs with the space-vector PWM method. A three-to-five-phase IMC control platform is realized by coordinating a TMS320F28335 DSP (Texas Instruments) with an EPM7128SLC84-15 field-programmable gate array (Altera). The simulation and experimental results are provided to verify the effectiveness of the CBPWM strategy.

A Fault-Tolerant Two-Motor Drive With FCS-MP-Based Flux and Torque Control

Independently controlled multimotor drives are typically realized by using a common dc link and independent sets of three-phase inverters and motors. In the case of an open-circuit fault in an inverter leg, one motor becomes single phase. To enable continued controllable operation by eliminating single phasing, the supply for the motor phase with the faulted inverter leg can be paralleled to a healthy leg of another inverter using hardware reconfiguration. Hence, the two motors are now supplied from a five-leg inverter, which has inherent voltage and current limitations. Theoretically, violating the voltage limit leads to inverter overmodulation and large torque oscillations. It is shown here that the finite-control-set model predictive control, designed to control the machines' stator flux and torque, can consider the inherent voltage limit dynamically in the control loop. Apart from preserving the independent control of the two machines, the additional constraint consideration significantly widens the operating speed ranges of the machines. In particular, it is shown that, whenever the voltage limit is entered, the controller reduces the stator flux level automatically, without requiring external flux reference change. The obtained performance is illustrated using experimental results and is also compared to the conventional two-motor field-oriented control scheme. The control concept is thus fully experimentally verified.

Dual Permanent Magnet Synchronous Motors Fed by a Five-Leg Inverter System Using Maximun Torque per Ampere

In this paper, a maximum torque per ampere (MTPA) control strategy based on space vector pulse width modulation (SVPWM) is adopted in a dual three-phase interior permanent magnet synchronous motors (PMSMs) system with a five-leg inverter. The simulation model is established in Matlab/Simulink based on the mathematics model of PMSM and the current control method. And the simulation results of the proposed current control strategy are compared with those ofid=0 method in order to verify the performances and characteristics of MTPA control stategy.

A Comparative Study of Synchronous Current Control Schemes Based on FCS-MPC and PI-PWM for a Two-Motor Three-Phase Drive

A two-motor drive, supplied by a five-leg inverter, is considered in this paper. The independent control of machines with full dc-bus voltage utilization is typically achieved using an existing pulsewidth modulation (PWM) technique in conjunction with field-oriented control, based on PI current control. However, model predictive control (MPC), based on a finite number of control inputs [finite-control-set MPC (FCS-MPC)], does not utilize a pulsewidth modulator. This paper introduces three FCS-MPC schemes for synchronous current control in this drive system. The first scheme uses all of the available switching states. The second and third schemes are aimed at reducing the computational burden and utilize a reduced set of voltage vectors and a duty ratio partitioning principle, respectively. Steady-state and transient performances are analyzed and compared both against each other and with respect to the field-oriented control based on PI controllers and PWM. All analyses are experimental and use the same experimental rig and test conditions. Comparison of the predictive schemes leads to the conclusion that the first two schemes have the fastest transient response. The third scheme has a much smaller current ripple while achieving perfect control decoupling between the machines and is of low computational complexity. Nevertheless, at approximately the same switching loss, the PI-PWM control yields the lowest current ripple but with slower electrical transient response.

Dual Three-Phase Indirect Matrix Converter With Carrier-Based PWM Method

This paper proposes an indirect matrix converter (IMC) topology with dual three-phase outputs and its effective carrier-based pulse width modulation (PWM) method. The proposed IMC topology can independently supply ac power for two three-phase loads from a single three-phase ac power source. This converter consists of a rectifier stage used in traditional three-phase IMC and a five-leg inverter. Besides a proposed IMC topology, the carrier-based PWM method suitable for this converter is also introduced. The proposed PWM method is easily implemented by using only one symmetrical triangular carrier signal to generate the PWM signals for a rectifier and five-leg inverter. Proposed IMC topology features the advantages of conventional three-phase IMC, such as sinusoidal input/output current waveforms, controllable input power factor, and simple commutation at the rectifier stage. Analysis, simulation, and experimental results are provided to demonstrate the advantages of the proposed IMC topology with dual three-phase outputs and to validate the effectiveness of the applied modulation strategy.

Implementation of Space Vector Two-Arm Modulation for Independent Motor Control Drive Fed by a Five-Leg Inverter

This paper presents the implementation of two-arm modulation (TAM) technique for the independent control of a two-induction motor drive fed by a five-leg inverter (FLI). A carrier-based space vector pulse width modulation technique for TAM is proposed to generate switching signals for FLI. Two independent three-phase space vector modulators are utilized to control two motors. The motor drive system applies two separate indirect field-oriented control methods. The stationary voltage outputs from the vector control are synthesized in the three-phase space vector modulator to generate switching signals for FLI. The performance of the independent control of the motors and the voltage utilization factor are likewise analyzed. Simulation and experimental results verify the effectiveness of the proposed method for the independent control of the two-motor drive system. The proposed technique is successfully validated by dSPACE DS1103 experimental work.

Characteristic of Induction Motor Drives Fed by Three Leg and Five Leg Inverters

This paper aims to compare the performance of three phase induction motor drives using Five Leg Inverter (FLI) and Three Leg Inverter (TLI) configurations. An Indirect Field Oriented Control (IFOC) method using a TLI is well established and incorporated for high performance speed drives in various industries. The FLI dual motor drive system on the other hand shows good workability in the independent control of two induction motor drives simultaneously. In this experiment, the IFOC method is utilized for both drive systems, and Space Vector Pulse Width Modulation (SVPWM) is used to generate pulses for both inverters. For the FLI, the Double Zero Sequence (DZS) Injection technique is used to generate the modulation signal. The complete experiment setup is done by using a DSpace 1103 controller board. The individual motor performances are analyzed using similar schemes, equipment setups and controller parameter values. The results show similar speed performance response capability between the single motor operation using a TLI system and the two motor operation using a FLI system based on the variable speed range either in forward or reverse operation. They also show similar load rejection abilities. However, the single motor with a TLI has a better power quality aspect such as ripple current and total harmonics distortion (THD).

Model Predictive Control of a Two-Motor Drive With Five-Leg-Inverter Supply

Model predictive control (MPC) for a two-motor drive, supplied from a five-leg inverter, is presented in this paper. As an alternative to existing methods, use of MPC in multimachine drives has the advantages of independent fast current control of the machines, elimination of the closed-loop system's cascaded structure, and a reduced number of microcontrollers. A vector control algorithm is required, necessitating state-space modeling, with each machine's direct- and quadrature-axis currents chosen as state variables. Prediction of future states is via a discrete-time model of the five-leg inverter and a piecewise-affine model of two permanent-magnet synchronous motors (PMSMs). A method which eliminates unfeasible switching states inherent in reduced-switch-count inverters while reducing computation and sampling times is proposed. The algorithm is implemented in a TMS320F28335 DSP microcontroller, which controls the five-leg inverter and the two PMSMs. Simulation and experimental results validate the presented control concept.

Independent Position Control of Two Permanent Magnet Synchronous Motor Drives Fed by a Five-Leg Inverter

This paper presents the experimental test results of the independent vector control characteristics of two three-phase permanent magnet synchronous motors (PMSMs) fed by a five-leg inverter (FLI). Recently, the use of PMSM is more and more spreading in industrial field. It has the features of saving-weight and high-efficiency compared with DC motor and induction motor (IM). The maximum feature of the PMSMs is the realization of high performance position control. The independent position control validates for the factory automation (FA) apparatus as machine tool. If the independent position control of two motors with the FLI may be realized, the belt conveyer used at the FA apparatus as machine tool will become possible not only one dimension but also two dimensions with single inverter. In this paper, experimental results are verified for the independent position control of two PMSMs fed by the FLI with the vector control.

A novel PWM technique with switching‐loss reduction for independent drive of two 3‐phase AC motors fed by a five‐leg inverter

AbstractThis paper presents a novel pulse width modulation (PWM) technique with switching‐loss reduction for a five‐leg inverter (FLI). The PWM technique, in which the available maximum voltage for two motors adds up to DC bus voltage, has been proposed as the strategy for the FLI. Therefore, the DC bus voltage is fully available as the PWM strategy. However, the conventional PWM technique requires the frequency, phase, and amplitude of the phase voltage commands of a motor to produce zero‐sequence voltages (ZSVs). The novel PWM strategy has some efficient features. These features are discussed in this paper. The validity of the novel PWM technique will be shown by experimental results. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

PWM Technique of Five-Leg Inverter Applying Two-Arm Modulation

This paper presents the simple pulse width modulation (PWM) technique of a five-leg inverter to drive two three-phase AC motors independently. Normal PWM techniques in three-phase voltage source inverter cannot be used for the five-leg inverter with the independent drive. In this paper, two kinds of simple and novel PWM techniques of the five-leg inverter with two three-phase AC motors are introduced. Experimental results are provided to illustrate the validity of the proposed PWM technique.

High-Performance Control of Two Three-Phase Permanent-Magnet Synchronous Machines in an Integrated Drive for Automotive Applications

The closed-loop control of an integrated dual AC drive system is presented to control two three-phase permanent-magnet motors. A five-leg inverter is employed in the drive system; three of the inverter legs are for a main traction motor, but only two are needed for a three-phase auxiliary motor by utilizing the neutral point of the traction motor. An integrated drive with reduced component count is therefore achieved by eliminating one inverter leg and its gate drivers. A modified current control scheme based on the rotor flux orientation principle is presented. Simulation and experimental results are included to verify the independent control capability of the integrated drive.

Five-leg inverter PWM technique for reduced switch count two-motor constant power applications

Industrial applications often require a number of variable speed electric drives. In the majority of cases, these multi-motor drive systems require independent control of individual motors. Over the past decade, research efforts have been made to reduce the number of power electronic devices required in multi-motor drive systems in order to reduce the overall complexity and hence cost of the drive. It has been shown recently that it is possible to independently control two three-phase induction machines using a five-leg voltage source inverter (VSI) as the supply, with one inverter leg being common to both machines. The existing pulse-width modulation (PWM) methods for this supply topology either limit the amount of DC bus voltage available to each machine or lead to uneven and increased switching frequency across five legs of the VSI. A new PWM method that effectively utilises the standard three-phase modulators in conjunction with appropriate modifications to generate modulation signals for all five legs of the VSI is presented. It enables an arbitrary distribution of the available DC bus voltage between the two machines. The considered supply topology, when utilised in conjunction with the developed PWM technique, is well suited to constant power applications such as centre-driven winders. Verification of the developed modulation method and its applicability to winder systems are demonstrated by experimental testing that includes both steady state and transient operation.

A five-leg inverter for driving a traction motor and a compressor motor

This paper presents an integrated inverter for speed control of a traction motor and a compressor motor to reduce the compressor drive cost in electric vehicle/hybrid electric vehicle applications. The inverter comprises five phase-legs; three of which are for control of a three-phase traction motor and the remaining two for a two-phase compressor motor with three terminals. The common terminal of the two-phase motor is tied to the neutral point of the three-phase traction motor to eliminate the requirement of a third phase leg. Further component reduction is made possible by sharing the switching devices, dc bus filter capacitors, gate drive power supplies, and control circuit. Simulation and experimental results are included to verify that speed control of the two motors is independent from each other.