Maxwell Circuit Editor

Table of Contents

1. Using the Maxwell Circuit Editor Schematic Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 The Schematic Editor Window . . . . . . . . . . . . . . . . . . . . . 1-2

Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4 Dedicated Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4 Commutator Bar and Commutator Bar Model . . . . . . . . . 1-4 Winding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

Passive Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6 Diode & Diode Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6 Capacitor (CAP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9 Resistor (Res) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10 Inductor (IND) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10 Mutual Inductance (IndM) . . . . . . . . . . . . . . . . . . . . . . . . 1-11 Current Controlled Switch (SW_I) . . . . . . . . . . . . . . . . . . 1-12 Voltage Controlled Switch (SW_V) . . . . . . . . . . . . . . . . . 1-13 Transformer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-14

Probes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-15 Ammeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-15 Voltmeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-15 Voltmeter with One Pin Grounded (VoltmeterG) . . . . . . . 1-16

Current and Voltage Sources . . . . . . . . . . . . . . . . . . . . . . 1-16 Contents-1

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Maxwell Circuit Editor Online Help

DC Current Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-17 Exponential Current Source . . . . . . . . . . . . . . . . . . . . . . . 1-18 Pulse Current Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-20 Piecewise Linear Current Source . . . . . . . . . . . . . . . . . . 1-22 Frequency-Modulated Sinusoidal Current Source . . . . . 1-23 Sinusoidal Current Source . . . . . . . . . . . . . . . . . . . . . . . . 1-24 DC Voltage Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-25 Exponential Voltage Source . . . . . . . . . . . . . . . . . . . . . . . 1-26 Pulse Voltage Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-28 Piecewise Linear Voltage Source . . . . . . . . . . . . . . . . . . 1-30 Frequency-Modulated Sinusoidal Voltage Source . . . . . 1-31 Sinusoidal Voltage Source . . . . . . . . . . . . . . . . . . . . . . . . 1-32

Placing Components in the Maxwell Circuit Editor Schematic 134 Assigning Component Properties in Maxwell Circuit Editor 1-35 Callback Scripting Using PropHost Object . . . . . . . . . . . . 1-36 Opening the Online Help for Circuit Components . . . . . . . 1-37 Setting Up an External Circuit . . . . . . . . . . . . . . . . . . . . . . 1-38 Add the Circuit Elements . . . . . . . . . . . . . . . . . . . . . . . . . . Connect the Circuit Elements in Series . . . . . . . . . . . . . . Export the Netlist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Save the Maxwell Circuit Editor Project . . . . . . . . . . . . . . Assign the External Circuit . . . . . . . . . . . . . . . . . . . . . . . .

1-38 1-40 1-40 1-41 1-41

Renaming a Source in Maxwell Circuit Editor . . . . . . . . . . 1-42 Applying the Commutating Bar Element . . . . . . . . . . . . . . 1-43

Contents-2


1 Using the Maxwell Circuit Editor

To open Maxwell Circuit Editor:

•

Click Start>Programs>Ansoft>Maxwell 12>Maxwell Circuit Editor.

The following menus are available in Maxwell Circuit Editor: File menu Edit menu View menu Project menu Draw menu Schematic menu Maxwell Circuit menu Tools menu Window menu Help menu Related Topics: Schematic Editor Maxwell Circuit Editor Component Models Placing Components in the Maxwell Circuit Editor Schematic Assigning Component Properties in Maxwell Circuit Editor

Using the Maxwell Circuit Editor 1-1



Schematic Editor The Schematic editor is the Ansoft tool for creating circuit schematics, or designs for a transient solution type. A design graphically represents and captures the electrical structure and characteristics of a circuit. You create such a design by starting the schematic editor and placing components, ports, connectors, and wires into a default empty schematic.

The Schematic Editor Window The Schematic Editor window allows you to place components and wire them together. You can move components by simply selecting and dragging them. Copy and paste can be used on components and their wires within the schematic editor. As you place the cursor near a pin of a component, it changes from an arrow to an X. This indicates that the schematic editor is in the wiring mode. In the wiring mode, click to start drawing a wire. Click again to end the wire.

1-2 Using the Maxwell Circuit Editor



Commonly used items such as ports, n-port black boxes, grounds, and page connectors can be placed in the schematic by clicking their toolbar icons or by using the Draw menu. View controls to zoom in, zoom out, and fit the drawing to the editor window are available on the View menu, and on the shortcut menu that opens when you right-click in a schematic. The arrow keys scroll the view up, down, left, or right in small increments. The page up and page down keys scroll the view up or down in larger increments. If you scroll so far that no objects are in the view, select Fit Drawing from the View pull-down on the Maxwell top menu bar (or press Ctrl+D) to re-center the entire design, resized to fill the window.




Components A number of components are available in the Circuit simulator. To view the Components window in the project tree, click the Components tab. (The Project tab is visible by default when you first open Maxwell Circuit Editor.) To expand a component subgroup, double-click its book icon. To read about a specific component, double-click its information icon in the Help topic tree. The following types of elements are available in Maxwell Circuit Editor:

• • • •

Dedicated Elements Passive Elements Probes Sources

Once components are placed in the schematic for a project, they appear in the project tree beneath the Project Components branch. The most recently placed components also appear under the Most Recently Used branch in the project tree. You can also set Favorites that can be accessed from the project tree. Related Topics: Placing Components in the Maxwell Circuit Editor Schematic Assigning Component Properties in Maxwell Circuit Editor

Dedicated Elements Three dedicated elements are available in the Maxwell Circuit Editor project tree:

• • •

BarC: Commutator Bar BarC_Model: Model Data for Commutator Bar Winding: Winding

The text before the colon (:) represents the component name and can be changed in the Properties window once the component is placed in the schematic. Related Topics: Assigning Component Properties in Maxwell Circuit Editor

Commutator Bar and Commutator Bar Model The commutator bar element is intended to be used for the motor model with a commutator. This element models the variable (periodic) contact resistance between the brush and the commutator bars, as well as the switching (commutation of the current) that occurs when the brush makes contact with the two adjacent commutator bars. The element itself must always be used together with the corresponding commutator bar model. The commutator bar model can be dropped on the sheet anywhere and needs no connections. Only




the commutator bar element itself should be connected as required by the application. The commutator bar elements need to reference the applicable commutator model.

Once the commutator bar element has been dropped on the sheet, you can double-click it to access the properties (make sure the Parameter Values tab is selected). Specify the applicable commutator bar model name in the MOD line and also the Lag parameter in degrees. Lag identifies the angle the commutator bar has to rotate from TIME = 0 in the chosen sense of rotation until it is perfectly aligned with the brush. By defa1ult, the element ID and lagging angle in degrees are displayed next to the element. The commutator bar model needs to be dropped on the circuit sheet. It is unique for every commutator bar element. The commutator bar model contains the following parameters:

• •

Model name that has to be referenced by all the commutator bar elements;

• •

WidB is the brush width in mechanical degrees;

•

R, the full contact resistance between brush and commutator bar, regardless of which of the two is wider; WidC is the commutator bar width in mechanical degrees (does not include the insulation between two adjacent bars); Period is the angular periodicity of the positive (or negative) brushes; use 360 for a two pole machine, 180 for a four pole machine with lap winding, etc.

Related Topics: An Application of the Commutating Bar Element.

Winding The winding element is used in the Maxwell Circuit Editor to create the necessary connection between the finite element model (the type of solution that supports the concept of winding, such as the transient type of analysis, with or without motion) and the driving circuits. It is necessary that the name(s) assigned for the winding(s) in the finite element model are matched exactly in the driving circuit created in Maxwell Circuit Editor. Windings can be placed on the design sheet at any moment while you are creating the circuitry to be used to drive the finite element windings.




To change the name of the winding placed on the sheet, click the winding symbol on the sheet, and change the name of the component in the property window (Value field in the DeviceName line, with the Param Values tab selected).

Note

The dot next to the winding symbol is used as the positive reference for the initial current (positive current is oriented from the "dotted" terminal towards to "un-dotted" terminal of the winding, through the winding).

Passive Elements Thirteen passive elements are available in the Maxwell Circuit Editor project tree:

• • • • • • • • • • • • •

Cap: Capacitor DIODE: Diode DIODE_Model: Diode Model Data Ind: Inductor IndM: Mutual Inductance Res: Resistor SW_I: Current Controlled Switch SW_I4: Current Controlled Switch with Controlling Port SW_IModel: Model Data for Current Controlled Switches SW_V: Voltage Controlled Switch SW_V4: Voltage Controlled Switch with Controlling Port SW_VModel: Model Data for Voltage Controlled Switches Transformer: Ideal Transformer


Diode & Diode Model Diode element must always be used together with a diode model. One diode model element can be used as reference for multiple diodes, as needed. Thus, once a diode is placed on the design sheet, a 1-6 Using the Maxwell Circuit Editor



corresponding model must also be present on the sheet. Once both needed elements (diode and diode model) have been placed on the sheet, right mouse click the diode model and specify the parameters as required by the application. Then, right mouse click the diode and create the reference to the corresponding model by entering the name of the model in the MOD line (Parameter Values tab should be selected). If you select the Show Hidden check box, the AREA diode parameter (used below in the model definition) becomes visible. The default value of the AREA parameter is 1. The diode model used by Maxwell Circuit Editor is a static model as described by the following equation:

– ( V d + BV )V t Vd ⁄ Vt ⎛ ⎛ ⎞ + v d ⋅ g min⎞ id = is ⋅ e – 1 – i bv ⋅ e ⎠ ⎝ ⎠ ⎝




where gmin = 1E-8 (fixed value) is added to improve convergence.

A

+

id rs

vd

-

K

-

v t = N ⋅ ( kT ) ⁄ q q = 1.6022 ⋅ 10 k = 1.3807 ⋅ 10

– 19

– 23

C

(J ⁄ K)

T is temperature in K, fixed at 300 K




i s = IS ⋅ AREA ⋅ e

( T ⁄ ( TNOM – 1 ) ) ⋅ ( EG ) ⁄ v t

T ⋅ ⎛ ---------------------------------⎞ ⎝ 273 + TNOM⎠

XTI --------N

i bv = IBV ⋅ AREA RS r s = --------------AREA

The model parameters are as follows:

• • • • • • • •

IS is the saturation current in Amps. RS is contact resistance in Ohms. N is the emission coefficient. EG is the barrier height at 0 K, in volts. XTI is the diode saturation current temperature coefficient. BV is the magnitude of the reverse breakdown voltage in volts. IBV is the magnitude of the reverse breakdown current in amps. TNOM is the reference temperature in Celsius.

Capacitor (CAP) A capacitor is assumed to be ideal (without losses or inductance) and is defined by the value of its capacitance (in the unit chosen by the user) and the corresponding initial condition (initial voltage). The straight bar of the capacitor symbol is used as the positive reference, and the curved bar of the capacitor symbol is used as a negative reference for the initial voltage (expressed in volts). The




default value of the initial voltage for all capacitors is zero. By default, the capacitance and element ID are displayed next to the component.

Resistor (Res) Resistor is assumed to be ideal (without inductive or capacitive effects) and is defined by the value of its resistance (in the unit chosen by the user, Ohm by default. By default the resistance and element ID are displayed next to the component.

Inductor (IND) Inductor is assumed to be ideal (without resistive or capacitive effects) and is defined by the value of its inductance (in the unit chosen by the user) and the corresponding initial condition (initial current). Note that the dot next to the inductor symbol is used as the positive reference for the initial current (positive current is oriented from the "dotted" terminal towards to "un-dotted" terminal of the inductor, through the inductor). The dot is also used to specify the mutual inductance between two or more inductors and thus determines the "polarized" terminals of the inductors. The default




value of the initial current for all inductors is zero. By default the inductance and element ID are displayed next to the component.

Mutual Inductance (IndM) Mutual inductance is used to specify the inductive coupling between inductors. It is defined by specifying the IDs of the coupled inductors (always in pairs) and the coupling coefficient, a number between -1 and 1. The default value of the coupling coefficient is 0.95.




Current Controlled Switch (SW_I) The current controlled switch comes in two flavors: with controlling port and without a controlling port. In either case a model data for the current controlled switch needs to be specified, similarly to the case of the diode.

Right-click the current controlled switch model and select Properties. With the Parameter Values tab selected, specify the switch model name (in the MOD line) as well as the ID of the controlling element: either an ammeter or a voltage source. In the later case the controlling quantity is the current through the voltage source. (Note that an ammeter is a voltage source with zero voltage, i.e. a short circuit). The current controlled switch with controlling port allows for the controlling quantity to be wired directly using connections with wires. In this case a reference arrow in the controlling port is displayed and is internally used as current reference (positive current flow as indicated by the arrow). In the model for the current controlled switch the following parameters are used:

• • •

Ron is the resistance of the switch in the on state (0.001 ohms default value). Roff is the resistance of the switch in the off state (1,000,000 ohms default value). Ion is the "on" value of the controlling current in amps. If I>Ion, then R=Ron.




•

Ioff is the "off" value of the controlling current in amps. If I
Setting ROFF = 0 in the voltage or current controlled switch model data changes the behavior of the device into a controlled conductance, according to the following equation:

1 G ( P ) = ------------ ⋅ f control ( P ) R ON where:

f control ( P ) is a function describing the controlling signal -- a time, position, or speed dependent current source or voltage source. Equation (1) clearly shows that the magnitude of the conductance is dictated by both the value of RON and the magnitude of the control signal, while the time / position / speed dependency is dictated by the control signal itself.

Voltage Controlled Switch (SW_V) The voltage controlled switch comes in two flavors: with controlling port and without a controlling port. In either case a model data for the voltage controlled switch needs to be specified, similarly to the case of the diode and current controlled switches.

Right-click the voltage controlled switch model and select Properties. With the Parameter Values tab selected, specify the switch model name (in the MOD line) as well as the ID of the controlling element: either a voltmeter or a current source. In the later case the controlling quantity is the voltage across the current source. (Note that a voltmeter is a current source with zero current, i.e. an open circuit). Using the Maxwell Circuit Editor 1-13



The voltage controlled switch with controlling port allows for the controlling quantity to be wired directly using connections with wires. In this case the reference for the voltage across the controlling port is displayed by "+" and "-" symbols and the two symbols are internally used as voltage reference. In the model for the voltage controlled switch the following parameters are used:

• • • •

Ron is the resistance of the switch in the on state (0.001 ohms default value). Roff is the resistance of the switch in the off state (1,000,000 ohms default value). Von is the "on" value of the controlling voltage in volts. If V>Von, then R=Ron. Voff is the "off" value of the controlling voltage in volts. If V
Setting ROFF = 0 in the voltage or current controlled switch model data changes the behavior of the device into a controlled conductance, according to the following equation:

1 G ( P ) = ------------ ⋅ f control ( P ) R ON where:

f control ( P ) is a function describing the controlling signal -- a time, position, or speed dependent current source or voltage source. Equation (1) clearly shows that the magnitude of the conductance is dictated by both the value of RON and the magnitude of the control signal, while the time / position / speed dependency is dictated by the control signal itself.

Transformer The transformer is an ideal element of infinite power without resistive or capacitive effects and linear. It is defined the values of the primary and secondary inductances and the coupling coefficient between the two windings.




Probes Three types of probes are available in the Maxwell Circuit Editor project tree:

• • •

Ammeter: Ammeter Voltmeter: Voltmeter VoltmeterG: Voltmeter with One Pin Grounded


Ammeter The ammeter is an ideal element (equivalent with an ideal voltage source with zero voltage). An arrow is attached to the symbol so that a positive current measured by the ammeter flows as indicated by the arrow. No numerical value is needed, just the element ID and name may by altered by the user.

Voltmeter The voltmeter is an ideal element with two pins (equivalent with an ideal current source with zero current). A plus sign is attached to the voltmeter symbol so that a reference for the voltage measured by the voltmeter is possible. No numerical value is needed, just the element ID and name may by altered by the user.




Voltmeter with One Pin Grounded (VoltmeterG) The voltmeter with one pin grounded is an ideal element with one pin, equivalent with an ideal current source with zero current. A plus sign is not necessary since it is assumed that the grounded pin (not available for connection in the circuit) is the negative one while the pin available for connection is the positive one. Thus, the reference for the voltage measured by the voltmeter is possible. No numerical value is needed, just the element ID and name may by altered by the user.

Current and Voltage Sources Sources available in the Maxwell Circuit Editor can be defined such that in general the dependency of the current or voltage can be made function of time, position, or speed. The type of dependency is part of the properties of the respective source and is always user-selectable. Thus, in the equation defining the behavior of the source (when specified), the variable "t" can mean TIME or POSITION or SPEED as selected by the user for each application. The default dependency type is TIME. Twelve types of sources are available in the Maxwell Circuit Editor project tree:

• • • • • • • • • • • •

IDC: DC Current Source IExp: Exponential Current Source IPulse: Pulse Current Source IPWL: Piecewise Linear Current Source ISffm: Sinusoidal Current Source ISin: Sinusoidal Current Source VDC: DC Voltage Source VExp: Exponential Voltage Source VPulse: Pulse Voltage Source VPWL: Piecewise Linear Voltage Source VSffm: Sinusoidal Voltage Source VSin: Sinusoidal Voltage Source

The text before the colon (:) represents the component name and can be changed in the Properties window once the component is placed in the schematic. Related Topics: 1-16 Using the Maxwell Circuit Editor



Assigning Component Properties in Maxwell Circuit Editor

DC Current Source This is an independent (DC) current source. The default value of the current is zero. The arrow symbol shows the direction of the positive current flow through the current source.

Right-click the DC current source on the sheet, and select Properties to edit the features of the element:

•

On the Parameter Values tab, you can edit the value of the current and the status; status can be active (default) but can be changed to Inactive_open or Inactive_short if desired.

•

On the General tab, you can set general features such as component name, component ID, symbol name, etc.

• •

On the Symbol tab, you can change the component color, location and spatial orientation, On the Property Displays tab, you can edit the displayed features; by default the component value (current in this case) and ID are displayed.




Exponential Current Source This is an independent current source with an exponential waveform of the current as function of time as shown in the figure below. The arrow symbol shows the direction of the positive current flow through the current source.

I Tan2

I2 x Te

Te xt

Y-Axis

t

Tan1

I1 I1 Td1

Td2 X-Axis

t

Thus, the parameters of this exponential source are:

• • •

Initial current in Amps, I1; Peak current in Amps, I2; Rise time delay, Td1:




• • • • •

I •

I2

In geometry units if type is POSITION and type of motion is translational; In rpm if type is SPEED and type of motion is rotational; In geometry units per second if type is SPEED and type of motion is translational; In seconds if type is TIME In degrees if type is POSITION and type of motion is rotational; In geometry units if type is POSITION and type of motion is translational; In rpm if type is SPEED and type of motion is rotational; In geometry units per second if type is SPEED and type of motion is translational;

Fall time delay, Td2:

• • • • • •

In degrees if type is POSITION and type of motion is rotational;

Rise time constant, Tau1:

• • • • • •

In seconds if type is TIME

In seconds if type is TIME In degrees if type is POSITION and type of motion is rotational; In geometry units if type is POSITION and type of motion is translational; In rpm if type is SPEED and type of motion is rotational; In geometry units per second if type is SPEED and type of motion is translational;

Fall time constant, Tau2:

• • • • •





Pulse Current Source

Y Axis

This is an independent current source with a trapezoidal waveform of the current as a function of time. The arrow symbol shows the direction of the positive current flow through the current source.

I1

Pw

Tr Td

Tf t

X-Axis

Period

The parameters of a pulse current source are the following:

• •

Initial current in Amps, I1; Peak current in Amps, I2;




•

Initial delay time, Td:

• • • • • •

In rpm if type is SPEED and type of motion is rotational; In geometry units per second if type is SPEED and type of motion is translational; In seconds if type is TIME In degrees if type is POSITION and type of motion is rotational; In geometry units if type is POSITION and type of motion is translational; In rpm if type is SPEED and type of motion is rotational; In geometry units per second if type is SPEED and type of motion is translational; In seconds if type is TIME In degrees if type is POSITION and type of motion is rotational; In geometry units if type is POSITION and type of motion is translational; In rpm if type is SPEED and type of motion is rotational; In geometry units per second if type is SPEED and type of motion is translational;

Pulse width, Pw:

• • • • • •

In geometry units if type is POSITION and type of motion is translational;

Fall time Tf:

• • • • • •


Rise time, Tr:

• • • • • •



Pulse period, Period:

• • • • •





Piecewise Linear Current Source This is an independent current source with a piecewise linear waveform of the current as a function of time. The arrow symbol shows the direction of the positive current flow through the current source.

Y-Axis

I

(T2,I2)

(T1,I1)

(T4,I4)

(T3,I3)

X-Axis

t

A piecewise linear current source is described by up to 20 pairs (Ti, Ii), where every pair of values specifies the value Ii in Amps of the current at time Ti in the following units:

• •

In seconds if type is TIME. In degrees if type is POSITION and type of motion is rotational.




• • •

In geometry units if type is POSITION and type of motion is translational. In rpm if type is SPEED and type of motion is rotational. In geometry units per second if type is SPEED and type of motion is translational.

Frequency-Modulated Sinusoidal Current Source This is an independent current source with a single frequency modulated sinusoidal waveform of the current as a function of time. The arrow symbol shows the direction of the positive current flow through the current source.

The equation describing the waveform is:

I ( t ) = I 0 + I a ⋅ sin [ ( 2π ⋅ F C ⋅ t ) + M di ⋅ sin ( 2π ⋅ F S ⋅ t ) ] where:

• • • • •

Io is Offset current in Amps. Ia is the peak amplitude in Amps. FC is the carrier frequency if type is TIME. Mdi is the modulation index. FS is the signal frequency if type is TIME.

If the type is POSITION, the frequency should be calculated based on the respective spatial periodicity, taking into account the fact that "t" in the above equation is measured in degrees for rotational type of motion and in the user-defined geometry units for translational type of motion. If the type is SPEED, the frequency should be calculated based on the respective speed periodicity, taking into account the fact that "t" in the above equation is measured in rpm for rotational type of motion and in the user-defined geometry units per second for translational type of motion.




Sinusoidal Current Source This is an independent current source with an exponentially damped sinusoidal waveform of the current as a function of time. The arrow symbol shows the direction of the positive current flow through the current source.

Y-Axis

I

e

–Df ⋅ t

Ta Io t Td

X-Axis





I ( t ) = I0 + Ia ⋅ e

– Df ( t – T d )

⋅ sin [ 2 ⋅ π ⋅ IFreq ⋅ ( t – T d ) – Phase ]

where:

• • • • • •

Io is Offset current in Amps. Ia is the peak amplitude in Amps. IFreq is the signal frequency if type is TIME. Td is the delay time in seconds if type is TIME. Phase is the signal phase delay if type is TIME. Df is the damping factor in 1/seconds if type is TIME.

If the type is POSITION, the frequency should be calculated based on the respective spatial periodicity, taking into account the fact that "t" in the above equation is measured in degrees for rotational type of motion and in the user-defined geometry units for translational type of motion. The delay and damping factor should also be interpreted accordingly. If the type is SPEED, the frequency should be calculated based on the respective speed periodicity, taking into account the fact that "t" in the above equation is measured in rpm for rotational type of motion and in the user-defined geometry units per second for translational type of motion. The delay and damping factor should also be interpreted accordingly.

DC Voltage Source This is an independent (DC) voltage source. The default value of the voltage is zero. The source exhibits a positive node, marked with the "+" sign, and a negative node, marked with the "-" sign. The positive current flows from the "+" node to the "-" node through the voltage source.

Right-click the DC voltage source on the sheet, and select Properties to edit the features of the element:

•

On the Parameter Values tab, you can edit the value of the voltage and the status; status can be active (default) but can be changed to Inactive_open or Inactive_short if desired.

•

On the General tab, you can set general features such as component name, component ID, Using the Maxwell Circuit Editor 1-25



symbol name, etc.

• •

On the Symbol tab, you can change the component color, location, and spatial orientation. On the Property Displays tab, you can edit the displayed features; by default the component value (voltage in this case) and ID are displayed.

Exponential Voltage Source This is an independent voltage source with an exponential waveform of the voltage as a function of time. The "+" and "-" symbols are used to mark the polarity of the source.

V Tan2

V I22 V x Te

Te xt

Y-Axis

t

Tan1

I1 V1 Td1

Td2 X-Axis

t




The parameters of an exponential voltage source are the following:

• • •

Initial voltage in Volts, V1. Peak voltage in Volts, V2. Rise time delay, Td1:

• • • • • •

In geometry units if type is POSITION and type of motion is translational; In rpm if type is SPEED and type of motion is rotational; In geometry units per second if type is SPEED and type of motion is translational; In seconds if type is TIME In degrees if type is POSITION and type of motion is rotational; In geometry units if type is POSITION and type of motion is translational; In rpm if type is SPEED and type of motion is rotational; In geometry units per second if type is SPEED and type of motion is translational;

Fall time delay, Td2:

• • • • • •


Rise time constant, Tau1:

• • • • • •



Fall time constant, Tau2:

• • • • •





Pulse Voltage Source This is an independent voltage source with a trapezoidal waveform of the voltage as a function of time. The "+" and "-" symbols are used to mark the polarity of the source.

V

Y Axis

V2

V1

Pw

Tr Td

Tf t

X-Axis

Period

The parameters of a voltage pulse source are the following:

• •

Initial voltage in Volts, V1. Peak voltage in Volts, V2.




•

Initial delay time, Td:

• • • • • •

In rpm if type is SPEED and type of motion is rotational; In geometry units per second if type is SPEED and type of motion is translational; In seconds if type is TIME In degrees if type is POSITION and type of motion is rotational; In geometry units if type is POSITION and type of motion is translational; In rpm if type is SPEED and type of motion is rotational; In geometry units per second if type is SPEED and type of motion is translational; In seconds if type is TIME In degrees if type is POSITION and type of motion is rotational; In geometry units if type is POSITION and type of motion is translational; In rpm if type is SPEED and type of motion is rotational; In geometry units per second if type is SPEED and type of motion is translational;

Pulse width, Pw:

• • • • • •

In geometry units if type is POSITION and type of motion is translational;

Fall time Tf:

• • • • • •


Rise time, Tr:

• • • • • •



Pulse period, Period:

• • • • •





Piecewise Linear Voltage Source This is an independent voltage source with a piecewise linear waveform of the voltage as a function of time. The "+" and "-" symbols are used to mark the polarity of the source.

Y-Axis

V

(T4,V4)

(T2,V2) (T1,V1)

(T3,V3)

X-Axis

t

A piecewise linear voltage source is described by up to 20 pairs (Ti, Vi), where every pair of values specifies the value Vi in Volts of the voltage at time Ti in the following units:

• • •

In seconds if type is TIME. In degrees if type is POSITION and type of motion is rotational. In geometry units if type is POSITION and type of motion is translational.




• •

In rpm if type is SPEED and type of motion is rotational. In geometry units per second if type is SPEED and type of motion is translational.

Frequency-Modulated Sinusoidal Voltage Source This is an independent voltage source with a single frequency modulated sinusoidal waveform of the voltage as a function of time. The "+" and "-" symbols are used to mark the polarity of the source.


V ( t ) = V 0 + V a ⋅ sin [ ( 2π ⋅ F C ⋅ t ) + M di ⋅ sin ( 2π ⋅ F S ⋅ t ) ] where:

• • • • •

Vo is Offset voltage in Volts. Va is the peak amplitude in Volts. FC is the carrier frequency if type is TIME. Mdi is the modulation index. FS is the signal frequency if type is TIME.

If the type is POSITION, the frequency should be calculated based on the respective spatial periodicity. taking into account the fact that "t" in the above equation is measured in degrees for rotational type of motion and in the user-defined geometry units for translational type of motion. If the type is SPEED, the frequency should be calculated based on the respective speed periodicity, taking into account the fact that "t" in the above equation is measured in rpm for rotational type of motion and in the user-defined geometry units per second for translational type of motion.




Sinusoidal Voltage Source This is an independent voltage source with an exponentially damped sinusoidal waveform of the voltage as a function of time. The "+" and "-" symbols are used to mark the polarity of the source.

Y-Axis

V

e

–Df ⋅ t

Ta Vo t Td

X-Axis





V ( t ) = V0 + Va ⋅ e

– Df ( t – T d )

⋅ sin [ 2 ⋅ π ⋅ IFreq ⋅ ( t – T d ) – Phase ]

where:

• • • • • •

Vo is Offset voltage in Volts. Va is the peak amplitude in Volts. IFreq is the signal frequency if type is TIME. Td is the delay time in seconds if type is TIME. Phase is the signal phase delay if type is TIME. Df is the damping factor in 1/seconds if type is TIME.

If the type is POSITION, the frequency should be calculated based on the respective spatial periodicity, taking into account the fact that "t" in the above equation is measured in degrees for rotational type of motion and in the user-defined geometry units for translational type of motion. The delay and damping factor should also be interpreted accordingly. If the type is SPEED, the frequency should be calculated based on the respective speed periodicity, taking into account the fact that "t" in the above equation is measured in rpm for rotational type of motion and in the user-defined geometry units per second for translational type of motion. The delay and damping factor should also be interpreted accordingly.




Placing Components in the Maxwell Circuit Editor Schematic To place a circuit component: 1.

Click the Components tab. The Components window appears in the project tree.

2.

In the project tree, expand the Maxwell Circuit Elements branch.

3.

Expand the branch containing the component you want to place. The choices are Dedicated Elements, Passive Elements, Probes, and Sources.

4.

Click to select the name of the component you want to place.

5.

Drag the component to the Schematic window. A diagram of the component appears connected to the mouse pointer.

6.

Release the mouse button to place the component in the location you prefer.

7.

To place a second component of the same type, move the mouse pointer to another location, and release it again.

8.

To exit from placement mode, do one of the following

• • Hint

To place the component a final time before exiting, press ENTER. To exit without placing the component again, press SPACE. To access these commands, you can also right-click and select one of the following from the shortcut menu:

• •

Place and Finish Finish

Related Topics: Assigning Component Properties in Maxwell Circuit Editor




Assigning Component Properties in Maxwell Circuit Editor Once a component has been placed in the Schematic window, do the following to edit its properties: 1.

Double-click the component. The Properties window opens.

2.

Make the desired edits on the following four tabs:

• • • • Note

Parameter Values General Symbol Property Displays Variables may be assigned to parameter values in the circuit by entering a variable name in the parameter value field and assigning a value in the Add Variable dialog box. Variables assigned in Maxwell Circuit Editor will be exported with the circuit and are available for modifying when the circuit is imported into another Ansoft application.

3.

Optionally, you can select or clear the Show Hidden check box on any of the Properties window tabs.

4.

Click OK.

The specific properties differ per component, as seen in the help topics describing each circuit component. Each tab of the Properties window contains a list of parameters (each individual row) and properties you need to set for each parameter (each column is a property). Related Topics: Placing Components in the Maxwell Circuit Editor Schematic Callback Scripting Using PropHost Object




Callback Scripting Using PropHost Object Callback scripts are scripts that can be set in the Property Dialog for individual properties by clicking the button in the Callback column and choosing a script that is saved with the project. Callback scripts can contain any legal script commands including general Ansoft script function calls (e.g. GetApplication(), …). In addition, they can call functions on a special object named PropHost. The PropHost represents the PropServer (owner of properties) that contains the Property that is calling the Callback script. Therefore, the Callback script can use the PropHost's functions to query or set other properties in the same PropServer. Refer to the Property Level scripting commands for more information. Related Topics: Scripting Guide: Property Level Commands




Opening the Online Help for Circuit Components To start the online help for any component from the schematic editor: 1. In the Schematic editor, double-click the component for which you want to view help. The Properties dialog box opens. 2. Click the Parameter Values tab. 3. Select the Value radio button. 4. In the Info row, click the button in the Value column, as shown below for COAXSTEP:

The help viewer opens to display the component’s specifications.




Setting Up an External Circuit Note

One use for an external circuit can be to supply an excitation to a coil terminal, rather than using a voltage type of excitation.

The driving circuit for the winding in this design consists of a voltage source in series with a resistor and with the winding. When complete, the circuit should look similar to the figure below.

To set up the external circuit, follow this general procedure: 1.

Add the circuit elements.

2.

Connect the circuit elements in series.

3.

Export the netlist.

4.

Save the Maxwell Circuit Editor project.

5.

Assign the external circuit.

Add the Circuit Elements To add the circuit elements in Maxwell Circuit Editor: 1.

Open the Maxwell Circuit Editor: Click Start>Programs>Ansoft> Maxwell>Maxwell Circuit Editor. The Maxwell Circuit Editor program opens.

2.

Click Project>Insert Maxwell Circuit Design.




The circuit sheet appears.

3.

Click the Components tab in the project tree.

4.

Place the winding circuit element on the sheet:

5.

6.

a.

In the project tree, under Maxwell Circuit Elements/Dedicated Elements, select the Winding element.

b.

Drag it onto the sheet.

c.

Right-click, and select Finish to place the component.

d.

To view the properties, double-click the component in the Schematic window. The Properties window appears.

e.

Change the Name to currentwinding, the same name you used when defining the winding in the Maxwell design.

f.

Click OK.

g.

Click Draw>Rotate, and position the winding vertically.

Place a resistor on the sheet: a.

In the project tree, under Passive Elements, select Resistor.

b.

Drag the resistor onto the sheet.

c.

Right-click, and select Finish to place it where desired.

d.

Double-click the symbol of the resistor, change the value of the resistor, R, to 3.09, keep the Unit value set to ohm, and click OK. The default is 100 Ohms.

Place a voltage pulse on the sheet: Using the Maxwell Circuit Editor 1-39



a.

In the project tree, under Sources select a VPulse element (Pulse Voltage Source).

b.

Drag it to the sheet, and then right-click and select Finish to place it onto the sheet.

c.

Double-click the source element symbol on the sheet, and then specify the following source characteristics:

d.

Parameter

Value

Description

V1

0

Initial voltage

V2

5.97

Peak voltage

Tr

0.001

Rise time

Tf

0.001

Fall time

Pw

1

Pulse width

Period

2

Leave the other fields set to the default values, and click OK.

Connect the Circuit Elements in Series To connect the circuit elements in series: 1.

From within the Maxwell Circuit Editor, click Draw>Wire.

2.

Click each terminal.

3.

When done, place the Ground symbol: Click Draw>Ground (or click the Ground symbol on the toolbar), place the Ground symbol on the sheet, right-click, and select Finish to place the symbol.

4.

Connect the ground to the circuit: Click Draw>Wire, and draw the final wire.

Export the Netlist To export the netlist: 1.

From within the Maxwell Circuit Editor, click Maxwell Circuit>Export Netlist. The Netlist Export dialog box appears.

Note 2.

To view the netlist before exporting it, click Maxwell Circuit>Browse Netlist.

Select the folder where you want to save the external circuit file.

3.

Type a name for the circuit in the File name box.

4.

Click Save. The Netlist Export dialog box closes and the Maxwell Circuit Editor reappears.




Save the Maxwell Circuit Editor Project To save the project and exit Maxwell Circuit Editor: 1.

Click File>Save, type a name for the project, and click Save to save the Maxwell Circuit Editor project.

2.

Click File>Exit to close the Maxwell Circuit Editor program.

Assign the External Circuit To assign the circuit in Maxwell (which should still be open): 1.

Click Maxwell>Excitations>External Circuit>Edit External Circuit. The Edit External Circuit dialog box appears.

2.

Click Import Circuit. The Select File dialog box appears.

3.

Select Designer Net List Files (*.sph) from the Files of type pull-down list.

4.

Browse to the location where you saved the circuit, select it, and click Open to import it.

5.

Click OK to close the Edit External Circuit dialog box.




Renaming a Source in Maxwell Circuit Editor To rename a source that is drawn in the Schematic: 1.

Double-click the source. The Properties dialog box appears.

2.

Click the Parameter Values tab (which should be the default tab visible).

3.

Change the text value in the Name row.

4.

Click OK. The new name appears for the source label in the Schematic.




Applying the Commutating Bar Element This paragraph describes how to apply the commutating bar element to simulate the commutating process of brush-type DC machines. A two-pole 12-slot PMDC motor, as shown in Fig. 1, is used as an example. The flux direction inside the S pole permanent magnet is from the air gap to stator yoke, and that of the N pole is from the stator yoke to the air gap.

Fig. 1 The cross-section geometry of a PMDC motor

The DC winding is of lap type with coil pitch of 5 slots. The flat-out extensional drawing of the motor indicating the relationship of permanent magnets, coils, commutating bars, and brushes at the initial position is shown in Fig. 2. With the rotation direction shown in Fig. 2, the brush aligned with the S pole is positive, and the brush aligned with the N pole is negative. The "go" terminal of




coil0 connects to bar0, and its return terminal connects to bar1; the "go" terminal of coil1 connects to bar1, and its return terminal connects to bar2; and so on.

Rotation direction

coil0 coil1

S

coil2

N

coil3

bar0

+

bar1

bar3

-

bar2 Fig. 2 The flat-out extension of DC motor components

At the initial time, bar0 lags the positive brush by 15 mechanical degrees (a half commutating bar pitch), and it lags the negative brush by 195 mechanical degrees; bar1 lags the positive brush by -15 mechanical degrees, or 345 degrees, and it lags the negative brush by 165 mechanical degrees; and




so on. The functional connection of each commutating bar with the positive brush or negative brush is modeled by BarC (commutating bar) elements, as shown in Fig. 3 with ID number from 37 to 60.

To positive brush

To negative brush

Fig. 3 The external circuit with no-load operation




In Fig. 3, elements with ID numbers of 37 to 48 represent the functional connections of bar0 to bar11 with the positive brush, respectively. Elements with ID numbers of 49 to 59 and 60 give the functional connections of bar1 to bar11, and bar0 with the negative brush, respectively. The additional inductor in series with each coil inductance represents the end turn effect that is desirable to consider in a 2D model and possibly also in a 3D model that does not include the end turn geometry. The additional series resistor in series with each coil represents the global resistance of the coil and needs to be included in both 2D and 3D simulations. The values between the BarC element symbols and ID numbers are the respective lagging angles in mechanical degrees. The element parameters can be edited by double-clicking on the element, as shown in Fig. 4.

Fig. 4 Parameters for BarC element




In Fig. 4, the input value "ComModel" for MOD is the model name that defines the parameters of commutating bars and brushes. The parameters of ComModel can be edited by double-clicking the BarC_Model element, as shown in Fig. 5.

Fig. 5 Parameters for BarC_Model element

Note

As a rule, each BarC element references a unique BarC_Model element.

In this design, the commutator diameter is 24mm, and the brush width is 8mm. Therefore, the brush width in mechanical degrees is the following:

WidB = 2 * arcsin(8/24) = 38.9 (deg) The number of commutator bars is 12 (the same as the number of slots), and the commutator insulation thickness is 0.5mm. Therefore, the commutator bar width in mechanical degrees is the following:

WidC = 360/12 - 2 * arcsin(0.5/24) = 27.6 (deg)




The electric conductance between a commutating bar and a brush varies with the rotor position and can be derived from the model parameters, as shown in Fig. 6, where Gmax = 1 / R.

G LagAngle

Period |WidC-WidB|

Gmax

b

c

a 0

d Position

WidC+WidB Fig. 6 Electric conductance as a function of rotor position

In Fig. 6, LagAngle is treated as a BarC element parameter because it is different for different commutating bars. All other values (Gmax, WidB, WidC, and Period) can be obtained from BarC_Model parameters. Positions a, b, c, and d correspond to the positions when one side of a commutating bar (solid color) aligns to one side of a brush, as shown in Figs. 7 and 8.

(a)

(b)

(c)

(d)

Fig. 7 Different conducting position when WidB > WidC

(a)

(b)

(c)

(d)

Fig. 8 Different conducting position when WidB < WidC 1-48 Using the Maxwell Circuit Editor



The computed no-load induced voltage, taking into account the commutating process, is shown in Fig. 9.

Fig. 9 No-load induced voltage






Index

E editing an external circuit 1-40 exporting a netlist 1-40

N netlist exporting 1-40

Index-1


Maxwell Circuit Editor

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