Inverter (3-phase)

Three-phase two-level inverter with a fire input per switch.

  • Boolean
  • electrical
  • 3-phase
  • Modelica Standard Library
  • 9 ports
  • 2 parameters
BlockInverter (3-phase)KindthreePhaseInverterLibraryConverters

Description

A three-phase two-level voltage-source inverter: three half-bridge legs across the DC bus, each with an upper and lower transistor and antiparallel diodes. Each switch has its own fire input.

Example

Three-phase inverter A two-level inverter makes 50 Hz three-phase current in a star-connected resistive load.

50 V upper50 V lowerMidpointDuty aPWM aDuty bPWM bDuty cPWM cInverterPhase currentsLoad 10 ΩStarGround (star)
In Gradara, select a Inverter (3-phase) block and press F1, then choose Open example. It opens as a new model in My models, ready to run.

Also in this example:DC voltageGroundSine wavePWM generator3-phase resistorStar point3-phase current sensor

Ports

Inputs 6

  • a+fa_pBoolean

    Phase a upper transistor gate: true connects a to dc_p.

  • b+fb_pBoolean

    Phase b upper transistor gate: true connects b to dc_p.

  • c+fc_pBoolean

    Phase c upper transistor gate: true connects c to dc_p.

  • a−fa_nBoolean

    Phase a lower transistor gate: true connects a to dc_n.

  • b−fb_nBoolean

    Phase b lower transistor gate: true connects b to dc_n.

  • c−fc_nBoolean

    Phase c lower transistor gate: true connects c to dc_n.

Conserving terminals 3

  • dc+dc_pelectrical

    DC bus positive terminal.

  • dc−dc_nelectrical

    DC bus negative terminal.

  • abcac3-phase

    Three-phase output plug carrying phases a, b, and c (the three leg midpoints).

Parameters

  • Transistor on resistanceRonTransistor0.00001 Ω

    ≥ 0

    On resistance of each transistor, in ohms. 0 or more.

  • Diode on resistanceRonDiode0.00001 Ω

    ≥ 0

    On resistance of each freewheeling diode, in ohms. 0 or more.

Equations

Modelica
For phase k: upper on → vk ≈ dc_p.v; lower on → vk ≈ dc_n.v; both off → set by the diodes and the phase current

Implementation

Modelica Standard Library 4.1.0Modelica.Electrical.PowerConverters.DCAC.Polyphase2Level
MSL documentation

Assumptions and limitations

  • Ideal switches: transistors are GTO-type switches that conduct only forward, and diodes switch at 0 V. Off conductance is fixed at 10 µS and knee voltages at 0 V. No switching times, reverse recovery, or conduction voltage drop beyond the on resistance.
  • The upper and lower gates of a phase both true short the DC bus. No dead time is inserted.

Tips

  • Drive each phase pair from one PWM generator (fire to the upper gate, notFire to the lower gate).
  • For a model without switching ripple, use the averaged Inverter.

See also

Select a block in Gradara and press F1 to open its page offline.