Documentation

Active Rectifier

Implement three-phase active (PWM) rectifier model for AC motor drives

Library

Electric Drives/Fundamental Drives

Description

The Active Rectifier block models a standard three-leg (three-phase) PWM rectifier with a controller for regulating the DC bus voltage and AC line currents. It has two operating modes to represent a detailed or an average-value rectifier.

Detailed Mode

In detailed mode, the block is modeled by a Universal Bridge block configured as a three-arm, forced-commutated converter. The rectifier controller is based on a PI regulator connected to the DC bus voltage, as shown in the figure.

The output of this regulator is the direct, that is, active, component of the AC line current. The reactive component of the AC line current is set to zero to operate at unity power factor.

The dq-abc block performs the conversion of the dq current components into abc phase variables. The current regulator is a bang-bang current controller with adjustable hysteresis bandwidth.

Average Mode

Average mode allows fast simulations when the high frequency switching actions of the switches are not required. In average mode, the Active Rectifier block models an equivalent average-value model for three-phase inverters. Refer to the Inverter (Three-Phase) block model of the Electric Drives library for more details. The current regulator in the rectifier controller block generates three-level signals (-1, 0, 1), indicating if the average-value PWM rectifier model is supplied by a negative, zero, or positive line voltage (Vab and Vbc). In detailed mode, the rectifier controller block outputs the actual pulses for the rectifier switches.

Parameters

Model detail level

Specify the model detail level to use:

  • Detailed (default)

  • Average

Base​ ​sample time (s)

The time step used for the simulation, in seconds. The default value is ​2​e-6.

Voltage regulator gains [Proportional, Integral]

The DC bus voltage controller proportional and integral gains. The default value is [10,100].

Low-pass filter frequency (Hz)

The DC bus voltage measurement low-pass filter cutoff frequency, in hertz. The default value is 100.

Output current saturation (A) [Negative, Positive]

The DC bus voltage controller maximum negative and positive output, in amperes. The default value is [-800,800].

Sample time (s)

The DC bus voltage controller sampling time, in seconds. The sampling time must be a multiple of the simulation time step. The default value is 1e-6.

Current hysteresis bandwidth (A)

The current regulator hysteresis bandwidth, in amperes. This value is the total hysteresis bandwidth distributed symmetrically around the current set point. The figure shows a case in which the current set point is Is* and the current regulator hysteresis bandwidth is set to dx.

This parameter is available only when the Model detail level parameter is set to Detailed. The default value is 10.

Snubber [Resistance Rs (Ohms), Capacitance Cs (F)]

The value of the snubber resistance and capacitance of the rectifier. The default value is [4e3,40e-9].

Power electronic device

Specify the type of power electronic device to use in the rectifier:

  • IGBT / Diodes (default)

  • MOSFET / Diodes

  • GTO / Diodes

Resistance Ron (Ohms)

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

Forward voltages (V) [Vf, Vfd]

Forward voltages of the forced-commutated devices (IGBT, MOSFET, or GTO) and of the antiparallel diodes, in volts. 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].

Input choke [Resistance (Ohms), Inductance (H)]

The input choke resistance, in ohms, and inductance, in hertz. The default value is [0.05,1e-3].

DC bus capacitance (F)

The DC bus capacitance, in farad. The default value is 7500e-6.

Inputs and Outputs

Bus_SP

DC bus voltage reference, in volts.

Va, Vb, Vc

Three-phase terminals on the AC side.

Meas

Vector of three measurement signals: DC bus voltage, DC bus current before the DC bus capacitance, and DC bus current after the DC bus capacitance.

crtl2

Vector of three measurement signals: d-axis current reference, DC bus voltage error, and DC bus voltage reference.

V+

Positive terminal on the DC side.

V-

Negative terminal on the DC side.

Examples

The Active Rectifier block is used in the AC5 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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