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1、,Chapter 0 Introduction,Table of Contents,Chapter 0 Introduction to Machinery Principles Chapter 1 DC Machines Chapter 2 Transformers Chapter 3 AC Machinery Fundamentals Chapter 4 Induction Motors Chapter 5 Synchronous Machines,Chapter 0 Introduction,0.1 Electric machines, Transformers, and Daily Li
2、fe 0.2 Materials used in Electric Machines 0.3 The Magnetic Field and Magnetic Circuit (Terms & Quantities；Production of a Magnetic Field；Magnetic Circuit；Magnetic Behaviour of Ferromagnetic Materials） 0.4 Related Laws （Faradays Law (Induced Voltage from a Time- Changing Magnetic Field；Induced Volta
3、ge on a Conductor Moving in a Magnetic Field；Production of Induced Force on a Wire） 0.5 Rotational motion, Newtons Law and Power Relationships 0.6 Real, Reactive and Apparent Power in AC Circuits,An electric machine is a device that can convert either mechanical energy to electrical energy or electr
4、ical energy to mechanical energy. A generator is used to convert mechanical energy to electrical energy, A motor can convert electrical energy to mechanical energy. Since any given electric machine can convert power in either direction, any machine can be used as either a generator or a motor.,0.1 E
5、lectric Machines, Transformers and Daily life,Almost all electrical machines convert energy from one form to another through the action of a magnetic field, and only machines using magnetic fields to perform such conversions are considered in this course.,Fradays Disk 1831，Michael Faraday ,(1791-186
6、7),Transformers (stationary) (Single-phase; Three-phase) DC Machine (rotation) (DC Motor; DC Generator) AC Machine (rotation) Induction Machine (Asynchronous Machine)(Motor; Generator ) Synchronous Machine (Motor; Generator ),Types of Electric Machines,These three types of electric devices play impo
7、rtant roles in our modern daily life. The transformer is an electrical device that is closely to electrical machines. It converts ac electrical energy at one voltage to ac electrical energy at another voltage level. Electric motors in the home run refrigerators, freezers, vacuum cleaners, blenders,
8、air conditioners, and many similar appliances. In the workplace, motors provide the motive power for almost all tools. Generators are necessary to supply the power used by all these motors.,Applications of Electric Machines,LARGE INDUSTRY,SMALL INDUSTRY,RESIDENTIAL,POWER STATION,Reference : http:/ G
9、ENERATION AND TRANSMISSION,11 KV/240 V,132/33 KV,400/132 KV,132/11 KV,Photo Credit: Brian Smith & NREL,（Wind Power),Electric Machines,Transformer,Electrically conductive materials Magnetically permeable (ferromagnetic) materials Insulating materials Structural materials,0.2 Materials used in Electri
10、c Machines,Magnetic fields are the fundamental mechanism by which energy is converted from one form to another in motors, generators and transformers.,0.3 The Magnetic Field and Magnetic Circuit,0.3.1 Terms & Quantities in Magnetic Field,Magnetic flux density Magnetic field intensity Magnetic flux M
11、agnetomotive force（mmf） Reluctance Permeance Flux linkage,1) Flux density B Tesla, T A current-carrying wire can produce a magnetic field in the area around it, and the flux density is used to describe the strength and the direction of the magnetic fields.,2) Magnetic field intensity H Ampere per me
12、ter, A/m H is another quantity used to describe the strength and the direction of the magnetic fields. The relationship between B and H is expressed as,The constant may be further expanded to include relative permeability which can be defined as below:,NOTE: is the magnetic permeability of the mater
13、ial. The permeability of vacuum is the magnetic constant 04107H/m or approximately 1/800000.,The value of relative permeability is dependent upon the type of material used. The higher the amount permeability, the higher the amount of flux induced in the core. Relative permeability is a convenient wa
14、y to compare the magnetizability of materials.,Because the permeability of iron is so much higher than that of air, the majority of the flux in an iron core remains inside the core instead of travelling through the surrounding air, which has lower permeability. The small leakage flux that does leave
15、 the iron core is important in determining the flux linkages between coils.,3) Flux Weber, Wb The total flux flowing in a cross section A is expressed as,Assuming that the flux density B in the cross section of ferromagnetic coreis constant and the cross section A is constant, then:,4) Magnetomotive
16、 force (MMF) F Ampere turn, A A current-carrying coil can produce a magnetic field, if the turns of the coil is N, the current is I, the total Magnetomotive force (MMF) F in the coil can be expressed as:,5) Magnetic reluctance Rm Ampere-turns per Weber, A/Wb, H-1 Reluctance is similar to resistance in the circuit. If the magnetic permeability of the material in the magnetic circuit is , the cross-section
