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Home > ANSYS Simplorer教學  > Average vs. Dynamic IGBT Models

 

本文始於2018.08，旨在學習Simplorer內的Average與Dynamic兩種IGBT模型，試著在不同操作條件下比較其時域與頻域結果，進而分析其各別的適用條件。

測試發現Dynamic IGBT模型的開關截止時間較長，且當輕載又較高切換頻率下，切換式電源轉換器輸出電壓"明顯"較高。如果降低開關切換頻率(100k->20k)，或是將輕載改重載(R load 22ohm->2ohm)，Average與Dynamic IGBT就可以得到輸出電壓一致的結果。

也就是需要精確考慮switching loss的情況(輕載且高頻)，建議使用Average IGBT模型。For the case with light loading and high switching frequency (switching loss plays the major role), suggest using average IGBT model.

Simplorer HELP：Dynamic IGBT較能確保動態切換波形的準確，而Average IGBT適用於能量\功率損耗分析。

  1. Average IGBT Model

  2. Dynamic IGBT Model

  3. Buck Converter with Average vs. Dynamic IGBT switching 100kHz

  4. Buck Converter with Average vs. Dynamic IGBT switching 20kHz

  5. Buck Converter with Average vs. Dynamic IBGT switching 100kHz and heavy loading

  6. Q&A

    6.1 Why does dynamic IGBT get higher output voltage than average IGBT in section 3?

  7. Reference

  1. Average IGBT Model 

Simplorer Component HELP : The purpose of the average model is to simulate correct energy loss and junction temperature with least computation. It is most suitable for energy/power loss and temperature estimation over large scale designs or long time-spans.
The average model is a static model. It contains the same static and thermal model as used in dynamic IGBT models, but its switching energy is estimated based on actual working conditions during simulation. As a result, all DC characteristics are accurate, switching energy loss and junction temperature output are also very good approximations, but the switching waveform has no dynamic details.

  1. Dynamic IGBT Model 

Basic dynamic IGBT model

Simplorer Component HELP : The basic dynamic model contains the same static and thermal model as used in average IGBT and advanced dynamic IGBT models. Their difference is in switching dynamics. The basic dynamic model has realistic switching waveforms, and it provides a basic set of dynamic parameters that can shape the switching dynamics to match the switching time and energy of a certain device.

一般不建議使用Advanced dynamic IGBT model

  1. Buck Converter with Average vs. Dynamic IGBT switching 100kHz 

3.1 Schematic

3.2 Spectrum of output voltage

3.3 Conductive EMI

3.4 Output voltage waveform (C1.V) and Inductor current (L1.I) 

3.5 Let's check the drop voltage of free wheel diode in IGBT (IGBT2.VD), it is easy to find IGBT2.VD of dynamic model gets worse waveform (larger turn-off time) than average model. 

  1. Buck Converter with Average vs. Dynamic IGBT switching 20kHz 

4.1 Schematic

4.2 Spectrum of output voltage

4.3 Conductive EMI

4.4 Output voltage waveform (C1.V) and Inductor current (L1.I) 

  1. Buck Converter with Average vs. Dynamic IBGT switching 100kHz and heavy loading 

5.1 Schematic

5.2 Spectrum of output voltage

5.3 Conductive EMI

5.4 Output voltage waveform (C1.V) and Inductor current (L1.I) 

  1. Q&A

6.1 Why does dynamic IGBT get higher output voltage than average IGBT in section 3? 

Ans：Since average IGBT model is good for power loss estimation, and switching loss dominates the power loss in section 3 case (light loading and high switching frequency), the converter with average IGBT will get lower output voltage (more accurate) than dynamic IGBT.

  1. Reference