Motor Drives And Control

Brushless dc (BLDC) motor drives have gained significant attention due to their merits such as high efficiency, high dynamic response, high reliability etc. From the literatures, it is understood that there has been remarkable developments evolved in application of the feedback controllers for both the BLDC motor drive's speed and current loops. The recent investigation and innovations in the pulse width modulation (PWM) methods are not encompassed in BLDC drives. The conventional PWM results mechanical vibration and acoustic noise, and limit the application scope the BLDC drives. This is due to the incapability of deterministic PWM in spreading the harmonic power. This paper presents random pulse width modulation (RPWM) for BLDC motor drive with better harmonic power distribution. The randomness is introduced in carrier wave by toggling between triangular wave (+fc) and its inverted form (-fc). The performance of the proposed RPWM is validated by using MATLAB software and results such as harmonic spread factor (HSF), total harmonic distortion (THD), and acoustic noise spectrum are presented. The comparison of results with the conventional PWM demonstrates the superiority of the proposed PWM.

Multilevel inverters have gained significant attention in recent years due to their ability to achieve higher voltage and lower harmonic distortion compared to conventional two-level inverters. Pulse width modulation (PWM) techniques play a crucial role in controlling multilevel inverters by generating the required switching signals for their power electronic devices. This paper presents a comprehensive comparative analysis of various PWM techniques employed in multilevel inverters, including sinusoidal pulse width modulation (SPWM), space vector pulse width modulation (SVPWM), carrier-based pulse width modulation (CBPWM), and selective harmonic elimination (SHEPWM). Each PWM technique's advantages, limitations, and suitability for different multilevel inverter topologies are discussed. Furthermore, recent advancements and hybrid PWM techniques are also examined to explore potential improvements in performance and efficiency. This paper aims to provide researchers, engineers, and practitioners with valuable insights into selecting the most appropriate PWM technique for their specific multilevel inverter applications, considering factors such as performance requirements, cost constraints, and ease of implementation.

This paper proposes the pulse width modulation (PWM) technique for the five-phase open-end winding induction motor (FPOEWIM) drive fed from five-phase dual inverter (FPDI) with a single dc source. The selected method gives the advantages of reduced switching losses specifically for induction motor drives working with higher power factors with the elimination of common-mode current (CMC). The method also reduces the computational burden over the processing unit. The proposed PWM technique is explained in detail with the implementation algorithm. The algorithm is used to select the proper switching states based on the reference vector location. Further, the proposed PWM technique is analyzed for the switching losses. The reduction in the switching losses is supported with the switching loss function (SLF) analysis. The SLF for the proposed PWM technique is plotted and compared with the conventional sinusoidal PWM (SPWM) technique. The presented method is simulated and the results are given. The validation of simulated results is done using the experimental results.

In this paper, a feedforward proportional carrier-based pulsewidth modulation (PWM) is proposed for the dc link control of the single-phase cascaded H-bridge multilevel photovoltaic inverter. The conventional carrier-based PWM techniques, such as the phase-shifted PWM and the level-shifted PWM, require multiple individual dc voltage controllers for the individual maximum power point tracking (MPPT). Thus, the control structure and the controllers' designs are quite complex. Several noncarrier-based PWM techniques, such as the feedforward space vector modulation, the sorting-algorithm-based modulation, and the lookup table-based modulation, have the capability of individual dc voltage regulation. Although these noncarrier-based PWM techniques require only one total dc voltage controller in the outer voltage loop, the implementations of them are much more complicated than those of the carrier-based PWM techniques. In this paper, with the proposed feedforward proportional carrier-based PWM, each individual modulation signal is directly generated by multiplying the current loop controller's output and the modulation signal's feedforward proportional factor. With the feedforward PWM and the total dc voltage control, the individual dc voltage regulation is achieved. This carrier-based PWM combines the strengths of both the traditional carrier-based PWM and the noncarrier-based PWM. It is not only easy for implementation, but also requires only one total dc voltage controller in the outer voltage loop. The detailed description, derivation, and analysis of this modulation are included in this paper. In addition, the simulations and experiments demonstrate the performance of the dc link control and the individual MPPT using the proposed PWM and the control strategy.

There are several types of motors to choose from when selecting motors for large HP (2000 HP - 10.000 HP) cement plant applications including; squirrel cage induction motors, wound rotor induction motors, PAM induction motors, synchronous motors, and DC motors, all of which have their own advantages and disadvantages. This paper will compare the operational characteristics of the induction, synchronous and DC motors to demonstrate how to apply the different speed-torque-current characteristics of each when driving typical cement plant loads. This paper will compare several different starting methods for AC motors such as across the line starting, autotransformer, solid state starting, and Adjustable Speed Drive (ASD) and discuss the limiting factors of each method such as starting current requirements and cage heating. A comparison of the operating characteristics of induction and synchronous motors will demonstrate how the power factor and efficiency advantage of synchronous motors can be applied to lower the energy cost of a cement plant. The variable speed operation of induction and synchronous motors operating on adjustable speed drives will be compared with the operational characteristics of DC motors which vary speed without the use of a drive.

The Flying Capacitor Multi Level Inverter (FCMLI) has a great advantage with respect to the availability of voltage redundancies. This work proposes a switching pattern for a modified inverter structure. It is used to improve the performance of chosen single phase five level H-bridge type FCMLI as compared to conventional FCMLI. The chosen multi level inverter is simulated for various multicarrier based Pulse Width Modulation(PWM) techniques for a resistive load. The PWM techniques include Phase Disposition (PD) PWM, Phase Opposition and Disposition (POD) PWM, Alternative Opposition and Disposition (APOD) PWM, Carrier Overlapping (CO) PWM, Phase Shift (PS) PWM and Variable Frequency (VF) PWM and the harmonics of the output voltages are observed for various modulation indices. The performance of chosen FCMLI is confirmed through MATLAB-SIMULINK based simulation. It is observed that sinusoidal reference with PODPWM provides output with relatively low distortion. Its also seen that COPWM strategy is found to perform better since it provides relatively higher fundamental RMS output voltage.

This paper presents a novel switching sequence for Space Vector Advanced Pulse Width Modulation generation for Z source inverter. The Performances of an inverter depends on what type of modulation strategies is used to switch. There exists different types of classical and advanced Pulse Width Modulation (PWM) techniques to switch the traditional Voltage Source Inverter (VSI).The advanced PWM techniques are superior to classical PWM techniques in respect of load current ripple, Total Harmonic Distortions, switching losses. The same concept of advanced PWM techniques for VSI is applicable for Z-Source Inverter. This paper proposes certain vector sequences based on advanced PWM techniques for ZSI. The proposed vector sequences are analyzed in respect of load/line current ripple based on stator flux ripple concept. The superiority of the advanced PWM techniques over classical is verified by simulation study of a ZSI in PSim9.1.1 Environment for R-L and different motor load conditions.

In order to test control algorithms for DC and AC motors, under a variable speed configuration, is necessary to provide a regulated load torque. Moreover, it is desirable to adjust on-line this quantity in order to simulate practical scenarios and nonlinear loads. Thus, with this objective in mind, the design and closed-loop torque control strategies for an absorbing dynamometer are detailed in this paper. This device is constructed using a permanent-magnet DC motor and a two-quadrant DC-DC chopper, and it is designed to operate independently of the motor velocity orientation. Two nonlinear control schemes are presented to regulate accurately the torque provided by the dynamometer. Finally, simulation and experimental results are illustrated for a 2HP DC motor test-bed.

Recently, many studies on mechatronics experiment system are conducted. In this paper, unique educational experiment systems are proposed for undergraduate students to be able to efficiently learn basic mechatronics techniques. The first system is used to learn input/output port operations, periodically LED lights ON/OFF and a stepping motor control. The second system is effective to learn A/D conversion for several sensor information, D/A conversion for DC motor control and a PID control method. Also, the third system is designed by using a robot arm with 4-DOFs to learn PWM (Pulse Width Modulation) control of a DC motor and force control of an end-effector. Further, the fourth system is designed using multiple mobile robots in which a subsumption control architecture is incorporated. Each of the systems individually has an important factor which students should acquire, so that it is expected that the combination will yield promising results. The effectiveness of the proposed systems is evaluated through experimental lectures in the department of mechanical engineering, Tokyo University of Science, Yamaguchi.

The increasing integration of renewable energy sources such as solar and wind energy into modern power grids necessitates advanced power conversion technologies. Solid-state transformers (SSTs) play a critical role in this context, particularly in the low/medium-voltage dc to medium-voltage ac conversion stage. However, the performance of SST is heavily influenced by the employed pulse width modulation (PWM) technique used in switching of the power converter. Conventional PWM methods often lead to significant harmonic distortion and power losses, limiting overall system efficiency and thermal stability. This work presents an advanced trapezoidal-triangular carrier-based PWM technique designed to reduce the total harmonic distortion (THD) and power loss of the cascaded H-bridge (CHB) multilevel inverter (MLI) used in SST. The proposed approach is evaluated through comprehensive simulations in MATLAB/Simulink and PLECS, achieving an unfiltered output voltage THD of 16% and total power loss of 10.76 kW for a 300 kW CHB inverter, both improvements over existing PWM techniques. A scaled-down laboratory prototype is developed and tested to experimentally validate the simulation results. The findings confirm that the proposed PWM strategy effectively enhances the performance of the CHB inverter deployed in the SST, making it a promising solution for efficient and reliable renewable energy integration into the power grid.

The five-phase loads with Multi-Level Inverters (MLI) are preferred by industries in high and medium power applications due to lower switching loss, voltage stress across switches, etc. The controlling of a five-phase motor drive is done by Pulse Width Modulation (PWM) techniques. This paper discusses different multi carrier PWM techniques, such as Level Shifting Carrier (LSC) PWM and Phase Shifting Carrier (PSC) PWM techniques available for controlling the inverter drive. The simulation is carried out for all PWM techniques and load voltage, voltage THD, Common Mode Voltage (CMV), and DC-link voltages are noted and compared among the PWM techniques.

This study compares Field-Oriented Control (FOC) and trapezoidal control techniques for Permanent Magnet Synchronous Motors (PMSMs) in modern industrial variable-speed applications. Traditionally, variable-speed applications have relied on DC machines, which have inherent drawbacks such as increased maintenance, spark losses, higher inertia, and overall higher costs. This FOC has emerged as a sophisticated method that enables independent control of torque and magnetization flux in AC motors, allowing for precise regulation of torque and speed tailored to the motor's electromagnetic state. FOC leverages Sinusoidal Pulse-Width Modulation (SPWM) and Space Vector Pulse Width Modulation (SVPWM) techniques to enhance DC voltage utilization and minimize switching and harmonic losses. In contrast, the paper presents a detailed model of a PMSM drive system based on electronic components rather than standard mathematical blocks, leading to more realistic simulation results. All simulation modules, including the inverter and PWM generator, were custom-built, allowing for performance comparison under varying speed and torque conditions. Brushless DC (BLDC) motors, which are typically categorized as PMSMs with trapezoidal back-EMF waveforms, have gained traction due to their simplicity and cost-effectiveness. The trapezoidal control technique, also known as six-step commutation, simplifies the control process by aligning motor phase switching with the rotor position, resulting in a quasi-square-wave current. However, this method introduces torque ripple and presents control challenges, particularly in low-speed applications. Given the rising economic constraints and stringent governmental standards, there is an increasing demand for efficient, low-interference, and adaptable electrical systems. This study demonstrates that FOC provides a more robust and efficient solution for high-performance applications than the trapezoidal control technique in PMSMs.

Carrier-based sinusoidal pulse-width modulation techniques for flying capacitor modular multi-level cascaded converter

One of the popular AC motor drive available in drive industry is permanent magnet synchronous motor (PMSM) drive. A novel approach of PMSM drive control using space vector pulse width modulation (SVPWM) technique is proposed based on the principle of field oriented control (vector control). In MATLAB / Simulink platform the whole system is implemented in which two control loops are used-inner current loop and outer speed loop. Beside continuous-time control, digital control using shift operator and delta operator is also presented. It is shown that the delta operator control scheme provides a unified frame-work and converges to the continuous-time control at high sampling frequency. However, the shift operator based control scheme does not leads to satisfactory result as the sampling speed increases. Simulation results verified the above facts.

The theoretical developments are described which form the basis for specifying the most appropriate reference signal that should be used in the carrier-based pulse width modulation (PWM) technique at any given carrier frequency and fundamental voltage. The load current distortion factor is used to compare the performances of various reference signals. The performances of the traditional carrier-based PWM techniques, using sinusoidal reference signals, are established to provide a means for comparison. A modified square-wave reference is shown to provide a low current distortion at very low carrier frequencies. A modified PWM technique can be adopted to lower the current distortion at very low carrier frequencies and also at large fundamental magnitudes. The reference signal that minimizes the current distortion is shown to be dependent upon the fundamental magnitude and the carrier frequency. >