Documentation

Three-Level NPC Converter

Implement three-phase, three-level Neutral-Point Clamped (NPC) power converter

Library

Fundamental Blocks/Power Electronics

Description

The Three-Level NPC Converter block implements a three-phase, three-level neutral-point clamped power converter. You can choose from three model types:

  • Switching devices — The converter is modeled with IGBT/diode pairs controlled by firing pulses produced by a PWM generator. This model provides the most accurate simulation results.

  • Switching function — The converter is modeled by a switching-function model. The switches are replaced with two voltage sources and two diodes on the AC side and with two current sources on the DC side.

    The converter is controlled by firing pulses produced by a PWM generator (0/1 signals) or by firing pulses averaged over a specified period (PWM averaging: signals between 0 and 1). Both modes of operation produce harmonics normally generated by a PWM-controlled converter and also correctly simulate rectifying operation as well as blanking time. This model type is well-suited for real-time simulation.

  • Average model (Uref-controlled) — The converter is modeled using a switching-function model directly controlled by the reference voltage signals (Uref). A PWM generator is not required. This model type provides the fastest simulations. It does not model neutral point voltage balancing.

Parameters

Model type

Specify the model type to use:

  • Switching devices (default)

  • Switching function

  • Average model (Uref-controlled)

Device on-state resistance (Ohms)

Internal resistance of the switching devices, in ohms. This parameter is available only when you set the Model type parameter to Switching devices. The default value is 1e-3.

Snubber resistance Rs (Ohms)

The snubber resistance, in ohms. Set the snubber resistance to inf to eliminate the snubbers. This parameter is available only when you set the Model type parameter to Switching devices. The default value is 1e6.

Snubber capacitance (F)

The snubber capacitance, in farads. Set the snubber capacitance to 0 to eliminate the snubbers. This parameter is available only when you set the Model type parameter to Switching devices. The default value is inf.

Diode on-state resistance (Ohms)

Internal resistance of the diodes, in ohms. This parameter is available only when you set the Model type parameter to Switching function or Average model (Uref-controlled). The default value is 1e-3.

Diode snubber resistance (Ohms)

The snubber resistance, in ohms. Set the snubber resistance to inf to eliminate the snubbers. This parameter is available only when you set the Model type parameter to Switching function or Average model (Uref-controlled). The default value is 1e6.

Diode snubber capacitance (F)

The snubber capacitance in farads. Set the snubber capacitance to 0 to eliminate the snubbers. This parameter is available only when you set the Model type parameter to Switching function or Average model (Uref-controlled). The default value is inf.

Diode forward voltage (V)

Forward voltage, in volts, across the diode when it is conducting. This parameter is available only when you set the Model type parameter to Switching function or Average model (Uref-controlled). The default value is 1e-3.

Current source snubber resistance (Ohms)

The snubber resistance across the two current sources, in ohms. Set the snubber resistance to inf to eliminate the snubbers. This parameter is available only when you set the Model type parameter to Switching function or Average model (Uref-controlled). The default value is inf.

Inputs and Outputs

g

A vectorized gating signal to control the converter. The gating signal contains 12 firing pulses. The first four pulses control the Q1a to Q4a switching devices (phase A of the converter), pulses five to eight control the Q1b to Q4b switching devices (phase B of the converter), and the last four pulses control the Q1c to Q4c switching devices (phase C of the converter). This port is visible only when you set the Model type parameter to Switching devices or Switching function.

Uref

A vectorized signal to control the converter. The signal contains three reference voltages (one for each phase). This port is visible only when you set the Model type parameter to Average model (Uref-controlled).

BL

You can block all firing pulses to the converter by applying a signal value of 1 at the BL input.

Examples

See the Power Converters Modeling Techniques example for a comparison of the three converter modeling techniques.

Introduced in R2015b

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