DC/AC Inverter (3-Phase) Simplified SPICE Behavioral Model

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Contents

1. Model Overview

2. Benefit of the Model

3. Concept of the Model

4. 3-Phase DC/AC Specification (Example)

5. Parameter Settings

6. Input-Output Characteristics6.1 Simulation Circuit and Setting

7. Line-to-Line Output Characteristics7.1 Simulation Circuit and Setting

8. Efficiency Characteristics8.1 Simulation Circuit and Setting

9. Minimum DC Input Voltage9.1 Simulation Circuit and Setting

Library Files and Symbol Files Location

Simulation Index

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1.Model Overview

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• This 3-Phase DC/AC Inverter Simplified SPICE Behavioral Model is for users who require the model of an Inverter as a part of their system.

• The model focuses on the input/output relationships of the Inverter block; therefore, it is not using high frequency models (e.g. oscillator and noise models), and is not based on the electronic topologies of the Inverter.

• The model enables long-term behavior simulation of the system (e.g. in a Photovoltaic system simulation).

2.Benefit of the Model

• Enable Transient Simulation.

• Can be adjusted to your own 3-Phase DC/AC specifications, by editing the

model parameters.

• The simplified model is an easy-to-use, which can be provided without the

circuit detail.

• Time and costs are saved because only the necessary parts are simulated.

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3.Concept of the Model

The model is characterized by parameters n, Vin_min, Vin_max, Vo_ac and Freq that represent the input-output-relationships of the Inverter. Where,

PAC : AC output powerPDC : DC input power

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3-Phase DC/AC Inverter Simplified SPICE Behavioral Model

IN+

IN-

U

N

VIN,MIN~VIN,MAX (Vdc)

IIN IO~

~

V

W

DC

AC

P

PnEfficiency )(

ININ IV

IV OO

)(3POUT(3-phase)

4.DC/AC Specification (Example)

3-Phase DC/AC Inverter with •VIN = 24~250Vdc, •VO, LN = 100VAC, •POUT(3-phase) = 1500W,•and Efficiency = 80%

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3-Phase DC/AC InverterEfficiency (n) = 80%

Operating Input Voltage:VIN,MIN=24 ~ VIN,MAX =250(Vdc)

IN+

IN-

~ POUT(3-phase)

IO~IIN

U

N

V

W

5.Parameter Settings (Example)

VIN_MIN DC minimum input voltage• 0 < VIN_MIN < VIN_MAX• Value = 24V

VIN_MAX DC maximum input voltage• VIN_MAX > VIN_MIN• Value = 250V

VO_AC AC Output Voltage, rms value• e.g. 100V, 220V• Value = 100V

FREQ AC Output Frequency• e.g. 50Hz, 60Hz• Value = 50Hz

N Efficiency in 100%• 0 < N < 1• Value = 0.8 (80% Efficiency)

• From the inverter specification, the model is characterized by setting parameters VIN_MIN, VIN_MAX, VO_AC, FREQ, and N.

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6.Input-Output Characteristics

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3-Phase AC Output Voltage: VO, LN

DC Input Current

DC Input Voltage

3-Phase AC Output Current

6.1 Simulation Circuit and Setting

*Analysis directives: .TRAN 0 100ms 0 10us

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7.Line-to-Line Output Characteristics

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Line-to-Line Output Current

Line-to-Line Output Voltage

DC Input Voltage

DC Input Current

7.1 Simulation Circuit and Setting

*Analysis directives: .TRAN 0 100ms 0 10us

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8.Efficiency Characteristics

Output and efficiency of the Inverter on time domain analysis.Efficiency(n) = PAC/PDC Efficiency = (3*VO(RMS)*IO(RMS)/VIN*IIN)*100, where the output voltage (VO(RMS)) is the inverter spec and the output current (IO(RMS)) is read from the simulation result.

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N = 0.8 Hold the Ctrl key and left click to Calculate RMS value of I(Ru)

8.1 Simulation Circuit and Setting

*Analysis directives: .TRAN 0 50s 0 10ms

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9.Minimum DC Input Voltage

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VO(AC) disable as VIN < VIN ,MIN

3-Phase AC Output Voltage

DC Input Voltage

DC Input Current

24.00ms, 24.00V

9.1 Simulation Circuit and Setting

*Analysis directives: .TRAN 0 250ms 0 10u

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Library Files and Symbol Files Location

1) Copy LIB files from CD to C:\Program Files\LTC\LTspiceIV\lib\sub

2) Copy LTspice symbols files from CD to C:\Program Files\LTC\LTspiceIV\lib\sym

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.LIB

.ASY

Simulation Index

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Simulations Folder name

1. Input-Output Characteristics.............................................

2. Line-to-Line Output Characteristics..................................

3. Efficiency Characteristics.................................................

4. Minimum DC Input

Voltage...............................................

VO_LN

VO_LL

Efficiency

VIN_MIN