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Objects

Properties

Methods

LabelBlockHE Object

Properties

Methods

Summary

Physical properties of a block for problems of AC magnetics.

Details

The LabelBlockHE object represents physical data applicable to the block label for time-harmonic magnetics problems.

When you need to set or modify some physical parameters for the block label, you have to get the LabelBlockHE object using the Content property of the Label object, modify the LabelBlockHE object using its properties and then put it back in the Label object assigning your LabelBlockHE to the Content property of your Label object.

The LabelBlockHE object inherits methods and properties from its base class LabelBlock. In addition, it provides properties and methods specific for time-harmonic magnetics. Those are:

Properties

Kxx (Absolute)

Get and set the components of magnetic permeability.
If the optional parameter is False or omitted, the value is considered as a relative permeability, otherwise as an absolute value.
Absolute values of magnetic permeability are measured in (H/m)

Kxx (Absolute)

Loading

Gets and sets the amplitude (peak value) of applying field source for the label.
The exact meaning of the Loading value depends upon two factors:
1. Whether the label describes conductive area (Conductivity > 0), and
2. Whether the TotalCurrent flag is set.
See the Remarks section for more details.

LoadingEx

The same as Loading, but allows defining the current (current density, voltage) not only by a value but also by a formula of coordinates.

LoadingPhase

The phase angle (in degrees) for the Loading value.

Conductivity

Gets and sets the electric conductivity for the label in (S). Conductivity should be positive or zero. Zero conductivity is the case if you don't want to simulate eddy current in this area.

ConductivityEx

The same as Conductivity, but allows defining the electrical conductivity not only by a constant number but also by a formula of coordinates. The formula should always give a positive result.

ConductivitySpline

Returns/sets the curve representing the dependency of electrical conductivity on temperature.

NonLinearConductivity

Returns True when the electrical conductivity depends on temperature and False otherwise.

TemperatureEx

Returns and sets the temperature value used for calculating the electrical conductivity. It can be either a number or a formula of coordinates. This value is only used when you do not employ importing temperature from a linked problem, or imported values are not available.

TotalCurrent

Gets and sets the flag modifying the meaning of the Loading value. See the Remarks section for details.

Serial

Gets and sets the flag specifies whether the conductors with total current or voltage applied are connected in series. See the Remarks section for details.

Spline

Returns an equivalent magnetization curve for AC condition, obtained by recalculating from the source magnetization curve for DC condition.

Following properties set/return the values of the magnetic loss coefficients in the formula of the specific volume losses: p = khf B2 + kcf2B2 + ke(f B)1.5 (W/m3). They are optional. Default zero value of any coefficient defines the zero loss of the corresponding type in the ferromagnetic material.

LossHysteresis

Sets and returns kh - hysteresis losses per volume unit of given material.

LossEddy

Sets and returns kc - eddy current losses per volume unit of given material. Eddy current losses may be calculated using this formula for materials with zero electrical conductivity (Conductivity or ConductivityEx) in which QuickField does not calculate the eddy currents, yet the eddy current losses should be taken into account. This may be the case for magnetic cores or laminated materials. If the electric conductivity has non zero value and QuickField calculates the eddy current - this coefficient LossEddy in the loss formula should be left with default zero value.

LossExcess

Sets and returns ke - additional losses in the volume unit for given material, which are not taken into account by eddy current and hysteresis losses.

You always have to set both Kxx and Kyy properties even for isotropic materials. If the Polar property is set to True, the Kxx component is considered as a radial and Kyy - as tangential component of the permeability tensor.

Methods

CreateBHCurve

Creates a new empty magnetization curve, which can be further used as a parameter for the PutDCSpline method.

GetDCSpline

Returns the magnetization curve for DC condition (the source curve).

PutDCSpline (
spline as Spline frequency As Double)

Sets the DC (source) magnetization curve and the frequency value for which the curve should be recalculated.

CreateConductivityCurve

Creates a new empty curve representing the dependency of the electrical conductivity on temperature. Returns a Spline object, which can be assigned to the ConductivitySpline property.

Remarks

The method of applying sources is different for conductors and non-conductive areas. The table below shows the possible options:

Conductive

Non-conductive

TotalCurrent = True

The Loading is the total number of ampere-turns (in A).

The Loading is the total number of ampere-turns (in A).

TotalCurrent = False

The Loading is the voltage (in V) applied to conductor's terminals.

The Loading value is the current density (in A/m2)

When the total numbers of ampere-turns of the voltage is applied, you can specify how QuickField should consider several areas labeled with this label (if any). If the Serial flag is set to True, several conductors will be considered as connected in series. Serial conductors are carrying the same current and calculated current density could be different if their squares are not equal.

Please note that with time-harmonic problems you always specify amplitude (peak) values for all alternating quantities.

With nonlinear AC magnetics problem you give a standard magnetization curve for each soft magnetic material. QuickField automatically calculates the magnetization curve for AC condition keeping in mind the problem frequency. The calculated magnetization curve for AC condition is available for reading by the Spline property.

Conductivity depending on temperature

QuickField can take into account the dependency of the electrical conductivity on temperature. You give the dependency by a table, and QuickField automatically approximates it by a cubic spline. When the conductivity depends on temperature, the material is considered as isotropic.

The temperature value used for conductivity calculation is either imported from the linked problem of heat transfer analysis, or given as a number or a formula in the block label (TemperatureEx property). The imported temperature has higher priority.

The Spline object represents the functional dependency of one variable from another. You use the ConductivitySpline property to get or set the conductivity spline. If the spline does not yet exist, the ConductivitySpline property returns Nothing. In that case you have to first create a new spline using the CreateConductivityCurve and then assign the returned object to the ConductivitySpline property.

The NonLinearConductivity property (of Boolean type, read-only) returns True, when the conductivity depends on temperature for this label.

The TemperatureEx property of type Variant sets/returns a priory known temperature in the block given by a number or a formula of coordinates. The formula should always give positive value.