Introductory Chapter: Emerging Electric Machines - Advances, Perspectives and Applications

*Ahmed F. Zobaa, Shady H.E. Abdel Aleem and Ahmed M. Zobaa*

### **1. Introduction**

With increasing attention on modern energy conversion (EC) systems, electrical machinery (EM) has been given more and more attention to developing new topologies and innovative drives to realize the increasing advantages of current industrial needs. Direct current (DC) machines, induction machines (IMs), and synchronous machines (SMs) were conventional most commonly used EMs in the industry in the past. Still, IMs, mainly the squirrel-cage IM (SCIM) types, are the most widely used EMs because they provide many advantages like effortless simple control, easy but efficient repair, high efficiency, and low cost and sizes [1].

EMs' energy consumption in the industry is 40% plus of the total generated energy worldwide [2]; thus, improving the machines' design and efficiency, even the conventional types, can considerably save energy. However, new EMs and their drives are industrialized with many extra features to meet the recent application areas, for example, electric vehicles (EVs), electric ships (ESs), aircraft machines, robotics, wind power generation, automated propulsion systems, and others [3].

These machines have to cope with numerous new applications under uncertain operating conditions, e.g. fixed or variable speed, uncertain loads (fixed or variable loads), and alteration of the supply voltage (whether constant or variable supply) [1].

#### **2. Emerging Electric Machines**

Several factors affect EC systems' efficiency, motor-system efficiency, and the system's performance (from the perspective of power quality (PQ ), energy efficiency, or reliability). For instance, all stakeholders should pay much attention to harmonic distortion problems associated with the variable frequency drives (VFDs), power electronic-based equipment, and nonlinear loads [4], oversizing of equipment distribution losses and power factor of the motors [5], variation of the loading conditions and load management practice (matching between motors and loads at any loading level), maintenance practices (for electrical, electronic and mechanical parts alike, and transmission system issues [6].

Despite the importance of these critical factors, they are often disregarded in practice. Considering these factors can significantly improve efficiency and enhance the motor systems' power quality and reliability performance.

In [3], the conventional brushed-type EMs is categorized as:

i.Series or shunt delf-excited DC machines,

ii.Separately-excited DC (field or permanent-magnet (PM), and

iii.Synchronous or induction (wound-rotor and double-fed types).

Also, the brushless EMs can be categorized as:

i.Synchronous (wound-rotor type),

ii.Induction (squirrel-cage type),

iii.Brushless PM, and

iv.Advanced magnetless machines.

The traditional brushless PM can have more than one machine – surface (SPM), inserted, and double-salient, so-called IPM, and DCPM, respectively. However, there are a lot of new PM machines, which have different flux distribution than the traditional brushless PM machines [3], such as hybrid-excited, memory, vernier, doublestator, double-rotor, magnetic-geared, linear, axial, and transverse PM machines.

The advanced magnetless machines can also have many types associated with the DC field excitation, such as the switched reluctance (SR), vernier reluctance (VR), and flux switching and reversal machines.

**Figure 1** illustrates the various control strategies for EMs [7]. The control strategies can be applied with both types of machines (traditional and emerging machines). Besides, they can be adopted to be suitable for both types. The control strategies include:

**3**

**Abbreviations**

**Figure 2.**

AC Alternating current DC Direct current DCPM Double-salient PM

*Features and merits of emerging EMs.*

*Introductory Chapter: Emerging Electric Machines - Advances, Perspectives and Applications*

i.Model predictive control associated with the finite-control set

The corresponding merits that these emerging EMs can fulfill with these various

From the application point of view, conventional EMs are usually dedicated to industrial applications, power generation, renewable energy generation, conversion, and domestic home appliances usage. However, emerging EMs are by default dedicated to new high-performance, innovative applications and intelligent devices besides their potential to be used in conventional applications. This is because of the weakness issues of traditional EMs, such as their need for regularly scheduled maintenance, complicated control and narrow speed range (particularly in alternating current (AC) machines), the complexity of operation and management in

On the other side, the emerging EMs also have some weakness issues because of their exceptional design and necessary control. The difficulty of manufacture and

control strategies are shown in **Figure 2** [3, 8]. These merits allow them to efficiently and effectively operate with different emerging applications such as robotics

high-speed operation, low efficiency, and low capability to be overloaded.

*DOI: http://dx.doi.org/10.5772/intechopen.97604*

ii.Control using field-orientation (FOC),

iii.Direct torque-based control (DTC),

iv.Sensorless-based control (SC), and

v.Hybrid control techniques (HC).

the high cost are examples of these demerits.

(FCS-MPC),

and EVs.

**Figure 1.** *Control strategies for EMs.*

*Introductory Chapter: Emerging Electric Machines - Advances, Perspectives and Applications DOI: http://dx.doi.org/10.5772/intechopen.97604*


*Emerging Electric Machines - Advances, Perspectives and Applications*

i.Series or shunt delf-excited DC machines,

Also, the brushless EMs can be categorized as:

i.Synchronous (wound-rotor type),

ii.Induction (squirrel-cage type),

iv.Advanced magnetless machines.

(VR), and flux switching and reversal machines.

iii.Brushless PM, and

control strategies include:

In [3], the conventional brushed-type EMs is categorized as:

ii.Separately-excited DC (field or permanent-magnet (PM), and

iii.Synchronous or induction (wound-rotor and double-fed types).

The traditional brushless PM can have more than one machine – surface (SPM), inserted, and double-salient, so-called IPM, and DCPM, respectively. However, there are a lot of new PM machines, which have different flux distribution than the traditional brushless PM machines [3], such as hybrid-excited, memory, vernier, doublestator, double-rotor, magnetic-geared, linear, axial, and transverse PM machines. The advanced magnetless machines can also have many types associated with the DC field excitation, such as the switched reluctance (SR), vernier reluctance

**Figure 1** illustrates the various control strategies for EMs [7]. The control strategies can be applied with both types of machines (traditional and emerging machines). Besides, they can be adopted to be suitable for both types. The

**2**

**Figure 1.**

*Control strategies for EMs.*


The corresponding merits that these emerging EMs can fulfill with these various control strategies are shown in **Figure 2** [3, 8]. These merits allow them to efficiently and effectively operate with different emerging applications such as robotics and EVs.

From the application point of view, conventional EMs are usually dedicated to industrial applications, power generation, renewable energy generation, conversion, and domestic home appliances usage. However, emerging EMs are by default dedicated to new high-performance, innovative applications and intelligent devices besides their potential to be used in conventional applications. This is because of the weakness issues of traditional EMs, such as their need for regularly scheduled maintenance, complicated control and narrow speed range (particularly in alternating current (AC) machines), the complexity of operation and management in high-speed operation, low efficiency, and low capability to be overloaded.

On the other side, the emerging EMs also have some weakness issues because of their exceptional design and necessary control. The difficulty of manufacture and the high cost are examples of these demerits.

**Figure 2.** *Features and merits of emerging EMs.*

## **Abbreviations**


#### *Emerging Electric Machines - Advances, Perspectives and Applications*


## **Author details**

Ahmed F. Zobaa1 \*, Shady H.E. Abdel Aleem2,3 and Ahmed M. Zobaa4

1 College of Engineering, Design and Physical Sciences, Brunel University London, Uxbridge, United Kingdom

2 Technology and Maritime Transport, Electrical Energy Department, College of Engineering and Technology, Arab Academy for Science, Smart Village Campus, Giza, Egypt

3 Power Quality Solutions Department, ETA Electric Company, El Omraniya, Giza, Egypt

4 Electrical Power Department, Cairo University, Giza, Egypt

\*Address all correspondence to: azobaa@ieee.org

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**5**

*Introductory Chapter: Emerging Electric Machines - Advances, Perspectives and Applications*

[8] K. T. Chau, C. C. Chan, and C. Liu, "Overview of permanent-magnet brushless drives for electric and hybrid electric vehicles," IEEE Trans. Ind. Electron., vol. 55, no. 6, pp. 2246-2257, 2008, doi: 10.1109/TIE.2008.918403.

*DOI: http://dx.doi.org/10.5772/intechopen.97604*

[1] M. Ćalasan, M. Micev, Z. M. Ali, A. F.

Zobaa, and S. H. E. A. Aleem, "Parameter estimation of induction machine single-cage and double-cage models using a hybrid simulated annealing-evaporation rate water cycle algorithm," in *Mathematics*, vol. 8, no. 6,

Elsevier, 2020, pp. 185-217.

[2] R. D. Cepoi, F. F. Jașcău, and L. Szabó, "Current trends in energy efficient electrical machines," J. Electr. Electron. Eng., vol. 10, no. 2, pp.

[3] C. Liu, "Emerging electric machines and drives - An overview," IEEE Trans. Energy Convers., vol. 33, no. 4, pp. 2270-2280, 2018, doi: 10.1109/

[4] S. H. E. A. Aleem, A. F. Zobaa, M. E. Balci, and S. M. Ismael, "Harmonic overloading minimization of frequencydependent components in harmonics polluted distribution systems using harris hawks optimization algorithm," IEEE Access, vol. 9, pp. 100824-100837,

[5] M. Khodapanah, A. F. Zobaa, and M. Abbod, "Estimating power factor of induction motors at any loading conditions using support vector

regression (SVR)," Electr. Eng., vol. 100,

[6] A. De Almeida, P. Bertoldi, and W.

[7] A. H. Abosh, Z. Q. Zhu, and Y. Ren, "Reduction of torque and flux ripples in space vector modulation-based direct

no. 4, pp. 2579-2588, 2018.

Leonhard, *Energy efficiency improvements in electric motors and drives*. Springer Science & Business

torque control of asymmetric permanent magnet synchronous machine," IEEE Trans. Power Electron., vol. 32, no. 4, pp. 2976-2986, 2017, doi:

10.1109/TPEL.2016.2581026.

Media, 2012.

**References**

13-18, 2017.

TEC.2018.2852732.

2019, doi: 10.1109/ ACCESS.2019.2930831. *Introductory Chapter: Emerging Electric Machines - Advances, Perspectives and Applications DOI: http://dx.doi.org/10.5772/intechopen.97604*

## **References**

*Emerging Electric Machines - Advances, Perspectives and Applications*

FCS-MPC Finite-control set model predictive control

DTC Direct torque-based control

FOC Field-orientation-based control

EC Energy conversion EM Electrical machinery ESs Electric ships EVs Electric vehicles

IMs Induction machines

SC Sensorless-based control

SCIM Squirrel-cage IM SG Synchronous generator SMs Synchronous machines

SR Switched reluctance VFDs Variable frequency drives VR Vernier reluctance

SPM Surface PM

IPM Inserted PM HC Hybrid control PM Permanent-magnet PQ Power quality

\*, Shady H.E. Abdel Aleem2,3 and Ahmed M. Zobaa4

1 College of Engineering, Design and Physical Sciences, Brunel University London,

2 Technology and Maritime Transport, Electrical Energy Department, College of Engineering and Technology, Arab Academy for Science, Smart Village Campus,

3 Power Quality Solutions Department, ETA Electric Company, El Omraniya, Giza,

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

4 Electrical Power Department, Cairo University, Giza, Egypt

\*Address all correspondence to: azobaa@ieee.org

provided the original work is properly cited.

**4**

**Author details**

Ahmed F. Zobaa1

Giza, Egypt

Egypt

Uxbridge, United Kingdom

[1] M. Ćalasan, M. Micev, Z. M. Ali, A. F. Zobaa, and S. H. E. A. Aleem, "Parameter estimation of induction machine single-cage and double-cage models using a hybrid simulated annealing-evaporation rate water cycle algorithm," in *Mathematics*, vol. 8, no. 6, Elsevier, 2020, pp. 185-217.

[2] R. D. Cepoi, F. F. Jașcău, and L. Szabó, "Current trends in energy efficient electrical machines," J. Electr. Electron. Eng., vol. 10, no. 2, pp. 13-18, 2017.

[3] C. Liu, "Emerging electric machines and drives - An overview," IEEE Trans. Energy Convers., vol. 33, no. 4, pp. 2270-2280, 2018, doi: 10.1109/ TEC.2018.2852732.

[4] S. H. E. A. Aleem, A. F. Zobaa, M. E. Balci, and S. M. Ismael, "Harmonic overloading minimization of frequencydependent components in harmonics polluted distribution systems using harris hawks optimization algorithm," IEEE Access, vol. 9, pp. 100824-100837, 2019, doi: 10.1109/ ACCESS.2019.2930831.

[5] M. Khodapanah, A. F. Zobaa, and M. Abbod, "Estimating power factor of induction motors at any loading conditions using support vector regression (SVR)," Electr. Eng., vol. 100, no. 4, pp. 2579-2588, 2018.

[6] A. De Almeida, P. Bertoldi, and W. Leonhard, *Energy efficiency improvements in electric motors and drives*. Springer Science & Business Media, 2012.

[7] A. H. Abosh, Z. Q. Zhu, and Y. Ren, "Reduction of torque and flux ripples in space vector modulation-based direct torque control of asymmetric permanent magnet synchronous machine," IEEE Trans. Power Electron., vol. 32, no. 4, pp. 2976-2986, 2017, doi: 10.1109/TPEL.2016.2581026.

[8] K. T. Chau, C. C. Chan, and C. Liu, "Overview of permanent-magnet brushless drives for electric and hybrid electric vehicles," IEEE Trans. Ind. Electron., vol. 55, no. 6, pp. 2246-2257, 2008, doi: 10.1109/TIE.2008.918403.

**Chapter 2**

**Abstract**

Brushless Electric Machines

**Keywords:** brushless electric machine, axial gap electric machine,

electromagnetic power, permanent magnet, cylindrical magnet,

segment magnet, diamagnetic anchor

practice confirms this trend [8–12].

**1. Introduction**

**7**

discrete commutation, multiphase electric machine, electromagnetic moment,

Low-and medium-power electric drives based on brushless electric machines are widely used both in industrial applications and in special-purpose products (space, medicine, robotics). Traditionally, brushless electric machines with a radial magnetic flux are used for this purpose. This is due to the good specific energy indicators of these electric machines, well-established technology of their production [1–7].

Recently, brushless electric machines with axial magnetic flux (BMAMF) have been increasingly used for these purposes. These electric machines are actively developing, and we can talk about the formation of a new class of brushless electric drives that are competitive with traditional brushless electric drives. There is a process of transition from the design of individual products to the development of an industrial range of electric machines of this type. International and domestic

An analysis of electric machines with axial magnetic flux is given. First, the effect of commutation on the electromagnetic moment and electromagnetic power is analyzed. Two types of discrete switching are considered. The analysis is performed for an arbitrary number of phases. The first type of switching involves disabling one phase for the duration of switching. The second type of switching involves the operation of all phases in the switching interval. The influence of the pole arc and the number of phases on the electromagnetic moment and electromagnetic power is investigated. The conclusion is made about the advantage of the second type of switching. It is recommended to increase the number of phases. Next, the classification of the main structures of the axial machine is carried out. Four main versions are defined. For each variant, the equation of the electromagnetic moment and electromagnetic power is derived. This takes into account the type of commutation. The efficiency of the selected structures is analyzed. The comparative analysis is tabulated for choosing the best option. The table is convenient for engineering practice. This chapter forms the basis for computer-aided design of this class of machines.

with Axial Magnetic Flux:

Analysis and Synthesis

*Sergey Gandzha and Dmitry Gandzha*

## **Chapter 2**
