Full-Bridge Inverter with LCL Filter

Purpose

Full-bridge voltage source inverter with LCL filter on the AC side

Library

Electrical / Nanostep

Description

This component implements a full-bridge voltage source inverter including an LCL filter on the AC side. The converter offers two configurations:

Sub-cycle average

The gate inputs are floating-point numbers with values between 0 and 1 representing the relative on-times of the controlled semiconductors over one simulation step. This technique is suited for real-time simulation on a CPU or a FlexArray solver.

Nanostep / Switched

The converter is simulated with time steps in the single-digit nanosecond range. The required Nanostep solver is available exclusively on the RT Box. In this configuration, the DC and AC sides are galvanically isolated. Any electrical connection between the two sides outside the component would therefore not reflect the real current and voltage situation and should be avoided. Both sides of the converter have current source behavior and must each be connected directly to a capacitor or a voltage source. The implementation has a weight of 3, which means it occupies an entire Nanostep solver.

For offline simulation, all power semiconductors in the converter are modeled with ideal switches. The individual switches are controlled with instantaneous logical gate signals. A switch is turned on when the corresponding gate signal is true.

Note

The Sub-cycle average and the Nanostep implementation cannot simulate a shoot-through or clamping of the DC side. Therefore, the gate signals for the upper and lower switch in each leg must never both become true at the same time. Also, the applied DC voltage must never become negative.

Parameters

Configuration

Allows you to chose between Sub-cycle average or Nanostep / Switched configuration.

Switch model (CPU code generation)

If the Configuration is set to Sub-cycle average, this parameter selects the switch model when CPU code is generated.

Semiconductor symbol

This setting lets you choose between IGBT and MOSFET for the symbol of the active semiconductor switches. It does not change the electrical behavior of the converter in simulation.

Inductance

A non-zero scalar specifying the inductance \(\mathrm{L}\), in henries \((\mathrm{H})\).

Winding resistance

A scalar specifying the winding resistance \(\mathrm{R_L}\), in ohms \((\Omega)\).

Filter inductance

A non-zero scalar specifying the inductance \(\mathrm{Lf}\), in henries \((\mathrm{H})\).

Filter winding resistance

A scalar specifying the winding resistance \(\mathrm{R_{Lf}}\), in ohms \((\Omega)\).

Filter capacitance

A scalar specifying the capacitance \(\mathrm{Cf}\), in farads \((\mathrm{F})\).

Assertions

When set to on, the block flags an error for combinations of gate signals that cause shoot-through. When set to off, these errors are not checked during real-time simulation.

Probe Signals

Inductor current

The current flowing out of the converter into the CL filter.

Filter capacitor voltage

The voltage across the filter capacitor.

Nanostep Probe Signals

See Fig. 264 for the Nanostep probe signal positions.

Inductor current

The current flowing out of the converter into the CL filter.

Filter inductor current

The current flowing through the filter inductor to the secondary terminals.

DC link current

The current flowing from the DC link into the converter.

Filter capacitor voltage

The voltage across the filter capacitor.

Gate signals

A vector of the gate signals connected to the semiconductor switches.

Fig. 264 Nanostep Probes for the Full-Bridge Inverter with LCL filter