maglev Class Reference [DSim Models]

Magnetic levitation system simulation model. More...

#include <maglev.h>

List of all members.

Public Member Functions
	maglev (dsim_model_setup *setup)
void	initialize_data ()
void	initialization_complete ()
	Finish initialization.
void	initialize_timestep ()
	Computation done prior to numerical integration.
void	rhs (double t, double jd)
void	complete_timestep ()
	Computation done after numerical integration.
Protected Attributes
dsim_variable	a_dsim
	Scale dimension.
dsim_variable	g_dsim
	Acceleration of gravity.
dsim_variable	l0_dsim
	Inductance.
dsim_variable	m_dsim
	Mass.
dsim_variable	i_dsim
	Control current.
dsim_variable	position_dsim
	Position.
dsim_variable	velocity_dsim
	Velocity.

---

Detailed Description

Magnetic levitation system simulation model.

Right hand side for a magnetic levitation system. The input is current.

The equation of motions are:

where f is the force due to the electromagnet. Since the force is proportional to current squared you must start the simulation with a positive offset from the equilibrium position. To compute iEq, the equilibrium current,

where

• Relative permeability
• Permeability of free space
• Wire turns
• Mass
• Acceleration of gravity
• Magnet length
• Magnet area
• xEq Desired equilibrium position

References: Woodson, H. H., J. R. Melcher, "Electromechanical Dynamics", John Wiley & Sons, 1968, pp. 192-200.

Definition at line 52 of file maglev.h.

---

Member Function Documentation

void maglev::initialize_data

(

)

Initialize model data. Create the inputs, parameters, and states. The states are position and velocity.

Definition at line 28 of file maglev.cc.

{               
    // Parameters
    
    const double pi = 3.14159265358979;
    
    double lMagnet = 0.01;                      // Magnet length
    double aMagnet = pi*pow(0.005,2);           // Magnet area
    double mu      = 5000e-6;                   // Transformer steel
    double mu0     = 4e-7*pi;                   // Permeability of free space
    double n       = 100;                       // Wire turns
    
    double a        = sqrt(2.0)*mu0*lMagnet/mu; // Scale factor
    double l0       = mu0*pow(n,2)*2*aMagnet/a; // Inductance
    double m        = 0.01;                     // Mass
    double g        = 9.806;                    // Acceleration of gravity
    double i        = 0;                        // Current
    
    double position = 0;
    double velocity = 0;
    
 
    i_dsim          = create_input("i",                     sd_type_double, &i,         1,1,    "A",        "Current");                 i_dsim.mark_telemetry();
    a_dsim          = create_parameter("a",                 sd_type_double, &a,         1,1,    "Nm/A^2",   "Scale");                   a_dsim.mark_telemetry();
    g_dsim          = create_parameter("g",                 sd_type_double, &g,         1,1,    "m/s^2",    "Acceleration of gravity"); g_dsim.mark_telemetry();
    l0_dsim         = create_parameter("l0",                sd_type_double, &l0,        1,1,    "H",        "Inductance");              l0_dsim.mark_telemetry();
    m_dsim          = create_parameter("m",                 sd_type_double, &m,         1,1,    "kg",       "Mass");                    m_dsim.mark_telemetry();
    position_dsim   = create_integrated_state("position",       sd_type_double, &position,  1,1,    "m",        "Position");                position_dsim.mark_telemetry();
    velocity_dsim   = create_integrated_state("velocity",       sd_type_double, &velocity,  1,1,    "m/s",      "Velocity");                velocity_dsim.mark_telemetry();
 
    configure_timestep(false,true,false);
}

void maglev::rhs	(	double	t,
		double	jd
	)

Computation done during numerical integration. Compute the derivatives for position and velocity.

Definition at line 75 of file maglev.cc.

{
    double a        = a_dsim.value_as_double();
    double l0       = l0_dsim.value_as_double();
    double m        = m_dsim.value_as_double();
    double g        = g_dsim.value_as_double();
    double i        = i_dsim.value_as_double();
    double position = position_dsim.value_as_double();
    double velocity = velocity_dsim.value_as_double();
    
    double f        = -(0.5/a)*l0*pow(i,2)/pow(1 + position/a,2);
    
    double accel    = f/m + g;
   
    position_dsim.set_derivative(velocity);
    velocity_dsim.set_derivative(accel);
}

---

The documentation for this class was generated from the following files:

• maglev.h
• maglev.cc