Chopper (High-Side Switch)

Purpose

Buck converter module

Library

Electrical / Power Modules

Description

This power module implements a chopper used in buck converters. It offers two configurations:

Switched

The power semiconductors inside the module are modeled with ideal switches. The switch is controlled with a logical gate signal; it is on if the gate signal is not zero. For compatibility with the averaged configuration it is recommended to use the value \(1\) for non-zero gate signals.

Sub-cycle average

The module as a whole is modeled with controlled voltage and current sources. The high voltage side of the chopper has current source behavior and must be connected to a positively biased capacitor or voltage source. The low voltage side is typically connected to an inductor. The control input is the relative on-time of the switch with values between \(0\) and \(1\).

In the average configuration the chopper can be operated in two ways:

• The control signal is the instantaneous logical gate signal having the values \(0\) and \(1\).

• The control signal is the duty cycle of the switch. It is either computed directly from the modulation index or by periodically averaging the digital gate signal over a fixed period of time, e.g. using the Periodic Average block. The averaging period does not need to be synchronized with the PWM and can be as large as the inverse of the switching frequency.

In both use cases, the average implementation supports continuous and discontinuous conduction mode.

Since the duty cycle is simulated accurately even with relatively large time steps, the average configuration is particularly well suited for real-time simulations with high switching frequencies.

The sub-cycle average model implementation requires an internal switching element on the low voltage side. When generating code for the power module the switching element is modeled as either an ideal or non-ideal switch. See Ideal and Non-Ideal Switch Models in Electric Circuits for detailed descriptions of the switch model implementations.

Note

The sub-cycle average implementation cannot model clamping of the high voltage side. Therefore, the applied DC voltage must never become negative.

Parameters

Configuration

Switched or averaged circuit model.

Semiconductor symbol

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

Switch model (CPU code generation)

Select the switch model in the generated code.