Three Phase Inverter Examples
In this section we show the basic components required to model three phase inverters In the fifth section various implementations per converter type are available for download
Overview
First we have a look at the components and where they are located in the library.Mosfet and IGBT
We start with building a three phase inverter with resistive inductive load. First we use discrete Mosfets, IGBTs and diodes for building the inverter. Next we use a single component that models the inverter and finally we replace this component with an averaged model.Modulation and Control
In the next level we include the modulation and control by using a generic modulation and control blocks. PWM and SVM are explored and the basic building blocks for current control are given. Clarke and Park transformations as well as PI controllers are discussed.Losses and Thermal
In the third level, we will add heatsink model and look at the losses of the inverter.Detailed semiconductor models
Finally in the fourth level, we use a gatedriver IC and a more detailed semiconductor model to model the on and off switching of the Mosfets and we add parasitic components that are responsible for ringing around the switching node.Various implementations
For each type of converter various implementations are shown. The levels are mixed and different aspects of modeling are demonstrated.
Overview
Overview
All components are grouped in three main sections. The discrete components such as R, L and C and the discrete semiconductors like Mosfet, IGBT and Diodes can be found in the Components/Circuit section. The complete inverter models are inside the Components/Library/PowerConverters/Inverter section. The control blocks are inside the Components/Library/PowerConverters/InverterControl section. Here you will find all components required for making a threephase inverter with control and passive(RL) load.
Mosfet & IGBT
In this first section we discuss how to build the inverter circuit and how to generate three phase currents in an resistive-inductive load. The inverter is without any feedback, the output frequency and modulation index of the switching Mosfets is constant. Only a few components are required and the open loop is merely to justify component size and voltage, current and power levels.
Mosfet & IGBT [discrete components]
For building the inverter we will start with using the discrete components. The circuit components like the Mosfets, IGBT's and diodes as well as the load resistors and inductors are coming from the components/circuit section
Mosfet & IGBT [modulation]
To start we will use a simple centerline modulation and create a sinusoidal three phase output voltage.
Modulation and Control
In the sections shown below we will find all components required for building the inverter. Please note that there are various control methods and the Math blocks should be taken from the Components/Blocks/Math section. The transformation blocks re available as scalar and as vector models. Interface between them is done using the vector2scalar and scalar2vector blocks form the Components/Library/PowerConverters/InverterControl/Interface section.
Control [modulation]
The modulation blocks are always needed when building a three phase inverter simulation. Typically you would need the ScalingVdc, SVM and Centerline block to go from the control output α, β to the gating signals. The centerline block can be omitted if an averaged inverter block is used and in that case the outputs from the SVM block directly connect to the modulation inputs of the averaged inverter block.
Losses and Thermal
The switching and conduction losses from the IGBTs and diodes are coupled with the thermal model. There are dedicated thermal models in the section Components/Library/Thermal that can be connected to the inverter models. Parameters are from the manufacturer datasheet for semiconductor modules can directly be entered.
Detailed semiconductor models
To model the behavior around the semiconductors it is wise to model a single leg of the inverter using a detailed gate driver model and a detailed semiconductor model. It will show the transient voltage overshoot, the rise and fall of currents and voltages as well give an indication on the generated EMI. The gate drivers are found in the Components/Library/Semiconductor/IC/GateDriver section as well as in the Components/Library/Breadboard/IC/GateDriver section. The detailed models for the Mosfet are in the Components/Library/Semiconductor/Mosfet section. In the example below the nMosfet can be used, which is a very simple model, as well as the VDMOS which contains a complete non-linear thermal model.
