FlowSIM – New Innovative Electrical and Thermal Simulation Method for Power Modules in Inverter Applications
内容简介:
The electrical and thermal simulation of the semiconductors is a powerful tool for optimized component selection.
The goal of the frequency converter simulation project is to run electrical and thermal simulations of power modules.
The electrical simulation yields excitation current and voltage time waveforms for the specific module components taking part in the power conversion process.
The components are characterized in advance to the simulation.
The main properties of the components are described by the static and thermal characteristics and by the switching characteristics for devices that are working in switching mode.
The result of the electrical simulation is fed into the loss calculation module.
The loss calculation gives the excitation for the thermal calculation.
The thermal simulation uses the dynamic thermal characteristics to predict the semiconductor component temperature as a function of time during a period of excitation.
The simulation is based on the averaged model of the switching waveforms.
This means that the real waveforms are substituted with their averaged waveforms where the averaging is done to each cycle of the switching frequency.
So the conduction losses are calculated with the low frequency envelope of input and or output excitation waveforms by using the duty cycle. The switching losses are calculated from the averaging of switching energy losses as a function of excitation current in the switching period. The static and switching losses are added to get the loss excitation as a function of time.
The inputs of the electronic simulation are user application data related to specific parameters of the module application, such as input and output voltages, frequencies (motor, line etc.), switching frequencies (PWM), etc.
The simulation model consists of different topologies like single or 3 phase input, an optional PFC for single phase input, DC link capacitor and variable frequency output modules with single or 3 phase.
The static and switching characteristics are measured and stored in the semiconductor module database as multidimensional arrays.
The static characteristics are dependent on temperature, while the switching characteristics, that is the switching losses depend also on other parameters, like driving conditions and turn off voltage values too.
The complex thermal characteristics of the components are characterized by an equivalent electrical model of concentrated parameter RC leader network.
This Foster type network has the advantage that its parameters are easily extracted from the measured cooling curves of the devices.
The calculation of the chip temperature function over time on steps of the network leader is also easy to calculate by knowing the loss excitation time function.
As the characteristics are temperature dependent the simulator uses a sequence of synchronous loss and temperature calculation in an iterative way to get an accurate temperature waveform of the simulated device.
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发表于 2007-11-12 16:06:30
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