IGBT 3-Level Half Bridge (NPC)
Purpose
3-level neutral-point clamped IGBT module
Library
Electrical / Power Modules
Description
This power module implements a single leg of a 3-level neutral-point clamped voltage source inverter. It offers two configurations:
Switched All power semiconductors inside the module are modeled with ideal switches. The individual IGBTs are controlled with logical gate signals. An IGBT is on if the corresponding gate signal is not zero. For compatibility with the averaged configuration it is recommended to use the value 1 for non-zero gate signals.
Averaged The module as a whole is modeled with controlled voltage and current sources. The DC side of the inverter bridge has current source behavior and must be connected to capacitors or voltage sources. The phase terminal is typically connected to an inductor. The control inputs are the relative on-times of the IGBTs with values between 0 and 1.
In the average configuration the half bridge can be operated in two ways:
- The control signals are instantaneous logical gate signals having the values 0 and 1.
- The control signals are the duty cycles of the individual IGBTs. They are either computed directly from the modulation index or by periodically averaging the digital gate signals 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 correctly accounts for blanking times, i.e. when during commutation less than two IGBTs are turned on. It also supports discontinuous conduction mode, e.g. when charging the DC link capacitors via the reverse diodes.
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.
Parameter
- Configuration
- Switched or averaged circuit model.