MODELING OF ELECTRICAL SYSTEMS 1st METHOD Current Law (Kirchoff) Voltage Law 2nd METHOD Current Law Magnetic Energy, Electrical Energy, Virtual Work: Application of Lagrange’s Equation 2nd method is used in this course.
FUNDAMENTAL ELEMENTS OF ELECTRICAL SYSTEMS Passive Elements Active Elements - + L C R Op-Amp Analogy Between Mechanical and Electrical Systems . .. x Displacement (m) Velocity (m/s) Acceleration (m/s2) m Mass (kg) k Spring Stiffness (N/m) c Damping Constant (Ns/m) f Force (N) Generalized Coordinates q Charge (Coulomb) i Current (Amper) L Inductance (Henry) 1/C C:Capacitance (Farad) R Resistance (Ohm) V Voltage (Volt) nt Generalized Charges Lagrange’s Equation
Analogy Between Mechanical and Electrical Systems . .. x Displacement (m) Velocity (m/s) Acceleration (m/s2) m Mass (kg) k Spring Constant (N/m) c Damping Constant (Ns/m) f Force (N) . .. θ Angular Dispalement (rad) Angular Velocity (rad/s) Angular Acceleration (rad/s2) IG Mass moment of inertia (kg-m2) Kr Rotational spring constant (Nm/rad) Cr Rotational damping constant Nm/(rad/s) M Moment (Nm) q Charge (Coulomb) i Current (Amper) L Inductance (Henry) 1/C C:Capacitance (Farad) R Resistance (Ohm) V Voltage (Volt) E2 E1 E1 E2 δW δW
Modeling of Electrical Systems: Current through R1= Example 3.1: V1: Input q and q2 : Generalized charges L C V1 + - R1 R2 Qq Qq2 L=3.4 mH, C=286 µF, R1=3.2 Ω, R2=4.5 Ω D(s)=0.02618s3+26.288s2+11188.81s=0 Eigenvalues: 0, -502.06±418.70i (ξ=0.768)
No current flow through Op-Amp Example 3.2 C1 - + V1 V2 R1 R2 R3 C2 No current flow through Op-Amp Input : V1 Generalized charges: q1, q2, q3 For Op-Amp : V+=V-=0
R1=15.9 kΩ, R2=837 Ω, R3=318 kΩ, C1=C2=0.005 µF Eigenvalues: 0, -628.93±12561.76i (ξ=0.05)
V2 R2 - + V1 R1 GAIN CIRCUIT R2 - + V1 R1 V2 R V2'
INTEGRAL CIRCUIT C R V1 V2 - + Negative sign can be eliminated bu adding an extra gain circuit with gain=1
- + V1 Vc R V2 V3 R V2 V1 - + Vc
PID circuit is used frequently in Control Systems. - + R1 R4 C4 C3 R3 R V1 V2 PID Control Circuit PID circuit is used frequently in Control Systems.