Slide 1

Motors Discussion D10.2 Chapter 15 Slide 2 Hans Christian Oersted (1777 1851) Ref: http://chem.ch.huji.ac.il/~eugeniik/history/oersted.htmhttp://chem.ch.huji.ac.il/~eugeniik/history/oersted.htm 1822 In 1820 he showed that a current produces a magnetic field. X Slide 3 Andr-Marie Ampre (1775 1836) French mathematics professor who only a week after learning of Oersteds discoveries in Sept. 1820 demonstrated that parallel wires carrying currents attract and repel each other. attract repel A moving charge of 1 coulomb per second is a current of 1 ampere (amp). Slide 4 What do Maxwells Eqs. Predict? B = magnetic flux density (magnetic induction) magnetic permeability B Magnetic field lines must be closed loops Force on moving charge q Lorentz force Slide 5 Vector Multiplication Scalar (Dot) Product A B Vector (Cross) Product A B Direction of C given by "Right- hand rule" (into the screen) Slide 6 Force on current in a magnetic field Force on moving charge q -- Lorentz force Current density, j, is the amount of charge passing per unit area per unit time. N = number of charges, q, per unit volume moving with mean velocity, v. j Force per unit length on a wire is Slide 7 Rotating Machine B i i X Force in Force out + - Slide 8 Rotating Machine B i i X Force in Force out + - Slide 9 Rotating Machine B i i X Force in Force out + - brushes commutator Slide 10 What do Maxwells Eqs. Predict? Corresponds to Faradays law of electromagnetic induction A changing magnetic flux B density induces a curl of E Slide 11 B i i X Force in Force out + - X r B l a b Back emf Slide 12 B i i X Force in Force out + - a b Back emf Slide 13 B i i X Force in Force out + - brushes commutator Slide 14 Armature with four coil loops X X X X N S Slide 15 Motor Circuit Power and Torque Slide 16 Armature Current, Speed, Power and Torque Slide 17 FF-130 Series Motors Slide 18 Slide 19 Slide 20 Slide 21 Slide 22 Maximum Power Slide 23 Slide 24 Generator Circuit Slide 25 Motor Driver Circuit Slide 26 G3VM-61B1 MOS FET Relays Slide 27 Pulse-Width Modulation Slide 28 module pwm(clk,clr,duty,pwm); input clk; input clr; input [3:0] duty; output pwm; reg [3:0] count; reg pwm; wire set, reset; // 4-bit counter always @(posedge clk or posedge clr) if(clr == 1) count