Inverter Motor Research Articles

Analysis of Bootstrap Circuit Operation With an Inverted PWM Drive Scheme for a Three-Phase Inverter for a Brushless DC Motor Drive

A bootstrap circuit for operating the high-side insulated-gate bipolar transistor of a three-phase inverter for a brushless dc motor drive is analyzed theoretically to avoid under voltage lockout by minimizing the discharge of a bootstrap capacitor (BSC). Unlike various methods of reducing the discharge of BSCs, which limits the controllability of the motor speed/torque, a proposed inverted PWM driving scheme has no limit to the controllability while maintaining the proper voltage level for a BSC. This method is verified experimentally in this paper.

Parametric identification algorithm for asynchronous electric motor inverter on the switching intervals of power transistors

The authors propose an algorithm for identifying the parameters of a controlled asynchronous electric drive in real time, which provides calculation of stator and rotor resistances which change as a function of temperature. The algorithm is based on the analysis of a current tube of electric motor phase with the subsequent calculation of resistances.

Vibration control of inverter motor by dynamic absorbers

Vibration control of inverter motor by dynamic absorbers

A Novel Open-Circuit Fault Diagnosis Method for Voltage Source Inverters With a Single Current Sensor

For the purpose of reducing cost and volume, as well as to increase reliability in hostile environments, techniques of reconstructing three-phase current through a single current sensor have been reported for a three-phase alternating current motor vector control system. Based on the phase current reconstruction method, this paper proposes a novel open-circuit fault diagnosis method for the low-power voltage source inverter in the three-phase permanent-magnet synchronous motor drive. Other than sampling the single dc-link current sensor, the zero voltage vector sampling method (ZVVSM) is adopted to implement the fault diagnosis. By placing the single current sensor at a special position, ZVVSM is able to sample current during the two zero voltage vectors and reconstruct the three-phase currents. The reconstructed three-phase currents are used to generate the diagnostic variables that can detect and locate the faulty power switches. The PWM modulation strategy remains unchanged in this method and the reconstructed phase currents are with less waveform distortion and less harmonic contents, which are suitable for the fault diagnosis. The effectiveness of the proposed method is verified by experiments.

A Simple Multimode Hybrid Energy Storage System and factional order control strategy

In order to overcome shortcomings of battery as a single energy source for electric vehicles and improve performance of electric vehicles, a simple multimode hybrid energy storage system (HESS) with battery and supercapacitor (SC) is proposed in this paper. The proposed simple multimode HESS can achieve boost mode when energy flows from power sources to motor inverter to supply power and buck mode when the energy flows from the motor inverter to the SC to recover power. The flexible power management can be achieved with the simple multimode HESS. Meanwhile, a small number of switches and a simple structure is helpful to design control strategy. In addition, taking into account the fractional characteristics of the HESS circuit, a fractional model of the HESS operation mode is established, and a novel fractional sliding mode control strategy is proposed based on the above model. Simulations are presented to verify the effectiveness of the proposed simple multimode HESS. Results show that the fractional order control strategy has better dynamic performance when compared with integer-order control strategy under the condition of system startup and parameters changes.

Control of integrated single‐phase PFC charger for EVs

This study discusses a converter structure appropriate for charging the batteries of an electric vehicle (EV). The structure is obtained by a transformation of a conventional three-phase inverter, which is already present in an EV's power-train system. Since the motor inverter's semiconductor components and the electric motor's windings form the battery charger's circuit, a reduction in the power-train system's size and weight is achievable. The proposed fully integrated battery charger operates alternately in two modes, buck and boost, while providing power factor (PF) correction capability continuously. This study also proposes an input current control strategy that ensures smooth operating mode transitions, which occur during the operation of a battery charger. The control is entirely implemented within a microcontroller and ensures operation with a high PF and low total harmonic distortion of the input current. The performance of the discussed converter using the proposed control scheme was verified experimentally.

Integrated single-phase PFC charger for electric vehicles

This paper discusses a converter structure appropriate for charging the batteries of an electric vehicle. The structure is obtained by a transformation of a conventional three-phase inverter, which is already present in an electric vehicle’s powertrain system. Since the motor inverter’s semiconductor components and the electric motor’s windings form the battery charger’s circuit, a reduction in the powertrain system’s size and weight is achievable. The proposed fully integrated battery charger can operate in buck and boost modes, while providing power-factor correction capability continuously. This paper also proposes an input current control strategy which ensures smooth operating mode transitions, which occur during the operation of the battery charger. The control is entirely implemented within a microcontroller and ensures operation with a high power factor and low total harmonic distortion of the input current. The performance of the discussed converter using the proposed control scheme was verified experimentally.

A Cascaded Multilevel Inverter Using Only One Battery with High-Frequency Link and Low-Rating-Voltage MOSFETs for Motor Drives in Electric Vehicles

Cascaded H-bridge (CHB) multilevel inverters are widely used in industrial applications, such as medium-voltage conversion and motor drives. However, the DC bus voltage in the electric vehicles is limited and it might not meet the requirements of the inverters for conventional motor drives. This paper presents a solution to drive the conventional motor (3Φ/AC 220 V) with inadequate DC bus voltage (DC 144 V) in an electric vehicle without any extra step-up circuits. The solution consists of a CHB inverter as a motor drive and a high-frequency (HF) transformer to balance the voltage. The multilevel CHB inverter improves the voltage and the current waveforms. High-frequency link (HFL) is used to create several isolated DC sources for the system and it can improve the power density. Besides, it replaces bulky line-transformers in the conventional CHB inverters, and the volume is reduced. Also, the inverter has bidirectional power flow ability, which can improve the efficiency in motor drives. As a result, the reduction of the step-up circuits is achieved and the topology can be used in the electric vehicles that are powered by only one 144 V-battery. The details and the principles of the control algorithm is discussed and an experiment based on a four-level CHB inverter with one DC 30 V power source is carried out to validate the proposed characteristics.

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.

A Combined Frequency Converter for Soft Acceleration of Induction Electric Drives with Heavy Starting Conditions

The usability of a thyristor frequency converter with a supplementary controlled series compensator for soft starting of induction motors with high torque of inertia of actuating mechanisms is considered as an alternative to transistor converters. It is shown that the supplemental device, in the form of a transistor–capacitor convertor, can be considered as an adjustable capacitor, the equivalent capacitance of which can be varied from very large values (to a maximum of infinitely large) to some fixed minimum value. The voltage of an adjustable series capacitor provides the desired switching conditions of thyristor inverter, and the capacitive reactance ensures the compensation of reactive power consumed by the induction motor and thyristor inverter, reducing the current load of the motor and converter. The addition of a thyristor current converter with a controlled series compensator of reactive power in the form of a transistor–capacitor unit makes it possible to carry out a soft start of induction motors similar to the starting modes of synchronous machines. Simulation results confirming the achievement of the desired effect are presented. It is shown that the supplemental device in the form of transistor–capacitor converter is a robust system well adaptable to various conditions of electric-drive operation. The functional equivalence of a transistor frequency converter and thyristor frequency converter with a supplemental transistor–capacitor unit with a substantially lower cost of the latter makes possible a new mechanism for soft starting of powerful electric drives with induction motors under conditions of high torques of inertia of actuating mechanisms.

Improved Field-Oriented Control for PWM Multi-level inverter-Fed Induction Motor Drives

<p class="Abstract"><em><span lang="EN-US">T</span></em><span lang="EN-US">his paper proposes a new approach to ensure the torque decoupled to the rotor flux of an induction machine based on the Field Oriented Control (FOC). The suggested method consists of inserting into the conventional d-q synchronous current controller, coupling terms of motor and multi-level inverter models. Making, the dynamic response of stator current components decoupled as well as the rotor flux and torque. In this paper, the mathematic model of an induction motor and multi-level inverter are first derived. Then, the synchronous current controller and modulation strategy for high power inverters are investigated. Finally, the validation through implementation and simulation of a 4.16 kV electric drive with MATLAB/Simulink and SimPowerSystems is performed. The model simulated in this paper includes an induction motor, nine-level cascaded H-bridge inverter and a carrier based space vector pulse-width-modulation.</span><span lang="EN-US">The results of the simulations of each method has been recorded and the comparison results reveal that the proposed method effectively maintains the rotor flux decoupled to the torque.</span></p>

Hybrid Spindle – An approach for a milling machine tool spindle with extended working range for HSC and HPC

Commercial motor-driven spindles for milling machine tools are generally developed for specific machining operations, such as HPC (High Performance Cutting) or HSC (High Speed Cutting). HPC and HSC require significantly different working ranges regarding spindle speed and torque. E.g. in HPC operations, high torque at low spindle speeds is needed. The two working ranges are covered only limited by a conventional spindle so far. However, a spindle system that can switch the working range allows cost-effective manufacturing of a wider range of materials within the same machine tool. The spindle bearings and the power electronics supply are challenges, when switching between both working ranges. HPC operation requires high bearing stiffness in order to transmit high forces occurring during the cutting process. However, the associated high bearing preload leads to high frictional losses at high speeds for HSC operations. Furthermore, the wide operating range generates contrary requirements for the motor winding. To increase the spindle speeds with a winding being assembled for high torques, the current has to be increased. For this purpose, expensive and non-standardized motor inverters are required. This paper introduces a concept to overcome these challenges. Firstly, an approach to adjust the bearing preload is presented, using a compact, electrically controlled bearing preload element, which is suitable for industrial applications. Next, an approach for a reconfigurable winding design of the spindle motor is shown. This allows electrical switching between the working ranges using conventional motor inverters. Finally, an analysis of the conditions of use of the hybrid spindles is presented.

Hybrid Artificial Intelligence based Fault Diagnosis of SVPWM Voltage Source Inverters for Induction Motor

Induction motors are widely used in various industries for production processes due to their inherent characteristics like high reliability, robustness, low cost and ease of construction and operation. However, while in operation they face harsh and severe conditions imposed on them by the electrical, mechanical, thermal and environmental stresses which give rise to abnormalities in machine parameters such as voltages and currents. If the motor drive is allowed to continue to run under such situations, it will lead to catastrophic failure of the motor disrupting the production process and huge loss of revenue. Hence, an intelligent drive control method based on Hybrid Artificial Intelligence (AI) technique of Neuro-Genetic Algorithm is proposed in this paper for condition monitoring, fault diagnosis and evaluation of induction motor without any additional information. The hybrid architecture of Back Propagation Neural Network (BPN) to get the desired output fast and with Genetic Algorithm to overcome the computational complexity and time consuming process involved in BPN.

A PV FED Three Phase Switched Z-source Multi Level Inverter for Induction Motor Drives

<p>Generally induction motor drives posses higher harmonic contents in line voltage and current due to high switching frequency used in inverters. Conventional induction motor drives employ two level voltage source inverters which has THD in level of 50%. This paper presents a switched z-source multilevel inverter which has voltage boosting capability and has lesser THD level in comparison with conventional two level voltage source inverters. This drive is fed from a photo voltaic source because of its voltage boosting capability. A single phase five level switched z-source inverter is initially designed and considered as single cell and three such cells are created for powering three phase induction motor. The proposed three cell PV source switched z-source multilevel inverter for three phase induction motor is simulated in MATLAB/Simulink software to verify merits of proposed IM drive</p>

Vibration control of inverter motor by dynamic absorbers

Vibration control of inverter motor by dynamic absorbers

Topology and Capacitor Voltage Balancing Control of a Symmetrical Hybrid Nine-Level Inverter for High-Speed Motor Drives

In order to increase the output voltage levels and reduce the isolated dc sources, a symmetrical hybrid nine-level inverter for high-speed motor drive applications is presented in this paper. Each phase of this inverter is composed of a five-level dc/dc converter cell and an H-bridge cell. The dc/dc converter is operated at high frequency with low-voltage devices and the H-bridge is operated at fundamental frequency with high-voltage devices. The three phases are connected to a common dc-link and each drives an isolated winding of an open-winding motor. The operating principles and modulation method are introduced. A detailed analysis of the average currents through the flying capacitor and neutral point of the dc-link is presented and a capacitor voltage balancing method based on phase-shifted pulse-width modulation is proposed. Simulation and experimental results are presented to demonstrate the feasibility of this topology and control method.

Total volume evaluation of high‐power density non‐isolated DC–DC converters with integrated magnetics for electric vehicles

One of the main problems in electric vehicles is the volume of their electrical systems because their bulky components carry additional mass and high cost to the total system. On this topic, interleaving-phases and magnetic coupling techniques have been reported as effective methods for increasing the power density of the DC–DC converters that work between the storage unit and the motor inverter. In that sense, a volume assessment of these topologies would provide a better understanding of the problems to be faced when an electric power train is designed. In this paper, a volume modelling methodology is introduced with the purpose of comparing four different DC–DC converters: Single-Phase Boost, Two-Phase Interleaved with non-coupled inductors, Loosely Coupled Inductor (LCI), and Integrated Winding Coupled Inductor (IWCI). The analysis considers the volume of magnetic components, power devices (conventional and next-generation), cooling devices and capacitors. The methodology can be used as a part of an optimization procedure to minimize the volume of DC–DC converters. Conclusively, LCI and IWCI were found effective to miniaturize power converters with a power density of 8.4 W/cc and 9.66 W/cc, respectively. Moreover, a maximum efficiency of 98.04% and 97.61% was obtained for a 1kW LCI and IWCI prototypes, respectively.

Method for Diffusing Carrier Noise under Zero‐Speed Condition using a Zero‐Sequence Voltage

SUMMARYIn this paper, a technique is proposed to reduce the carrier noise of pulse width modulation (PWM) inverters for a permanent magnet motor drive. The carrier noise is generated by the motor and the reactor driven by the inverter and affected by the switching frequency. When a motor rotates and drives a machine, the carrier noise is hidden by the machine noise. However, when the motor speed is approximately zero, the carrier noise becomes dominant and raucous. The typical method to reduce the noise employs a switching frequency higher than the audible frequency of human hearing. However, the increase in switching frequency results in the inverter suffering a higher switching loss and lower efficiency. In particular, when the permanent magnet motor operates at approximately zero‐speed and full‐load, for example, in the hill‐start conditions of electric vehicles and the start and stop conditions of elevators, the current flows in specific power devices and the switching loss further increases. The proposed technique uses a zero‐sequence voltage, which is generated randomly with the M‐sequence signal, and diffuses the frequency components of the ripple contained in the current. The technique is able to reduce the noise without increasing the switching frequency of the inverter when the motor speed is almost zero. Simulation and experimental results show that the proposed technique can diffuse the carrier noise and the cycle of the M‐sequence signal changes the diffusion effect of the carrier noise.

Effect of different methods of pulse width modulation on power losses in an induction motor

We consider the calculation of modulation power losses in a system “induction motor–inverter” for various pulse width modulation (PWM) methods of the supply voltage. Presented values of modulation power losses are the result of modeling a system “DC link - two-level three-phase voltage inverter - induction motor - load”. In this study the power losses in a system “induction motor - inverter” are computed, as well as losses caused by higher harmonics of PWM supply voltage, followed by definition of active power consumed by the DC link for a specified value mechanical power on the induction motor shaft. Mechanical power was determined by the rotation speed and the torque on the motor shaft in various quasi-sinusoidal supply voltage PWM modes. These calculations reveal the best coefficient of performance (COP) in a system of a variable frequency drive (VFD) with independent voltage inverter controlled by induction motor PWM.

Fault-Tolerant Multilevel Topology Based on Three-Phase H-Bridge Inverters for Open-End Winding Induction Motor Drives

In this paper, a multilevel inverter based on three-phase H-bridge inverters for an open-end winding induction motor drive is presented and its fault-tolerance capability is investigated. The multilevel topology is obtained using three wye-connected three-phase H-bridge inverters to supply open-end winding induction motors. This topology has the ability to extend the maximum voltage applied to the motor windings up to two times the dc supply voltage of the three-phase inverters. For a given induction motor voltage, the topology allows the use of dc sources with a lower voltage rating. Consequently, faster power semiconductors can be used. This multilevel topology can be directly controlled by modifying known modulation concepts, such as sinusoidal pulse width modulation (PWM). In this study, two sinusoidal PWM modulation techniques will be implemented: the level-shifted carriers (phase disposition) and the phase-shifted modulator. Fault-tolerant operation under an open-switch fault without adding any extra components and without changing the modulation strategy is also proposed, adding fault-tolerant capability to the new topology. Experimental results of this multilevel inverter in normal operation and in fault tolerant mode are presented. The obtained results confirm the fault effectiveness of the proposed multilevel topology.