Documentation

Inverter (Five-Phase)

Implements five-phase inverter model for five-phase PM Synchronous motor drive

Library

Electric Drives/Fundamental Drive Blocks

Description

The Inverter (Five-Phase) block models a standard five-leg, two-level inverter model when set to detailed mode or an average-value inverter model when set to average mode.

Detailed mode

In detailed mode, this block consists of five Universal Bridge models configured as single-leg (one leg with two switches), force-commutated converters and connected in parallel.

Average Mode

In average mode, the Inverter (Five-phase) block implements an average-value inverter model where the inverter is represented using current and voltage sources, as shown in the figure.

The average-value model is composed of one controlled current source on the DC side and four controlled current sources and four controlled voltage sources on the AC side. The DC current source allows the representation of the average DC bus current behavior following the equation

Idc = (Pac + Plosses) / Vin,

with Plossesbeing the AC side instantaneous power, Plosses the losses in the power electronics devices, and Vin the DC bus voltage.

On the AC side, the current sources represent the average phase currents fed to the motor. Because the regulation is fast, the current values are set equal to the current references sent by the current regulator. A small current is injected to compensate for the current drawn by the five-phase load.

During loss of current tracking due to insufficient inverter voltage, the currents are fed by four controlled voltage sources. These voltage sources represent the square wave mode and allow good representation of the phase currents during inverter saturation. Each voltage source outputs either Vin or 0, depending on the values of the pulses (1 or 0) sent by the current controller. This mode of operation is detected by the Saturation detection block using the DC bus voltage and the counter electro-motive force generated by the AC machine.

Parameters

Model detail level

Specify the model detail level to use:

  • Detailed (default)

  • Average

Sample Time

The sample time of the inverter, in seconds. The default value is 2e-6.

Snubber resistance Rs (Ohms)

The snubber resistance, in ohms. Set the Snubber resistance Rs parameter to inf to eliminate the snubbers from the model. The default value is 500.

Snubber capacitance Cs (F)

The snubber capacitance, in farads. Set the Snubber capacitance Cs parameter to 0 to eliminate the snubbers or to inf to get a resistive snubber. The default value is 1e-9.

Power electronic device

Select the type of power electronic device to use in the inverter.

  • GTO / Diodes (default)

  • MOSFET / Diodes

  • IGBT / Diodes

Resistance Ron (Ohms)

Internal resistance of the switch, in ohms. The default value is 1e-3.

Forward voltages (V) [Vf, Vfd]

Forward voltages, in volts, of the forced-commutated devices (GTO, MOSFET, or IGBT) and of the antiparallel diodes. The default value is [1.2,1.2].

Fall time and tail time (s) [Tf, Tt]

Fall time Tf and tail time Tt, in seconds, for the GTO or the IGBT devices. The default value is [1e-6,2e-6].

Source Frequency (Hz)

Synchronous frequency of the machine (Hz). This parameter is visible only when the Model detail level parameter is set to Average. The default value is 60.

Inductance (H)

The armature inductance of the sinusoidal model with round rotor (Ld is equal to Lq). This parameter is visible only when the Model detail level parameter is set to Average. The default value is 1350e-6.

Flux induced by magnets (Wb)

The constant flux, in weber, per pole pairs induced in the stator windings by the magnets of the machine. This parameter is visible only when the Model detail level parameter is set to Average. The default value is 0.05.

Stator resistance Rs (ohm)

The stator phase resistance Rs, in ohms, of the motor. This parameter is visible only when the Model detail level parameter is set to Average. The default value is 0.12.

Pairs of poles

The number of pole pairs of the machine controlled by the inverter. This parameter is visible only when the Model detail level parameter is set to Average. The default value is 4.

Inputs and Outputs

g

The gate input for the controlled switch devices. Pulses are sent to upper and lower switches of inverter legs A, B, C, D, and E. This input is visible only when the Model detail level parameter is set to Detailed.

ctrl

Control signals from the PMSM vector controller. In average mode, the three-phase inverter no longer receives pulses for each switch. The control signals are the AC current references for each phase along with pulses (0 or 1) to enable square wave operating mode. This input is visible only when the Model detail level parameter is set to Average.

+

The positive terminal on the DC side.

-

The negative terminal on the DC side.

A, B, C, D, E

The five-phase terminals on the AC side.

Examples

The Inverter (Five-Phase) block is used in the AC8 block of the Electric Drives library.

References

[1] Bose, B. K. Modern Power Electronics and AC Drives, NJ: Prentice-Hall, 2002.

Introduced in R2015b

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