Low Voltage Experimental And Signal Analysis Of Mechanical Stress Wave Induced By IGBT Switch

With the development of energy technology,the performance requirements of power electronics equipment are becoming higher and higher.As the core component of power electronics equipment,IGBT’s reliability directly determines the normal operation of electrical energy saving,new energy generation,and smart grid systems.The failure or aging of IGBT will pose a hazard to the reliable operation of the power system and the system using power electronic equipment,and will cause huge economic losses in severe cases.Therefore,the operating status of the IGBT should be monitored online.Most of the existing state monitoring methods for IGBT devices are based on the extraction and analysis of th e characteristic parameters of the electro-magnetic-thermal stress information inside the device.It is difficult to meet the requirements of fast,non-invasive and real-time online detection to reflect the status of the IGBT device at the same time.In the states of switching and faults,the coupling of multiple physical fields such as electromagnetic thermal forces inside the IGBT device will generate mechanical stress waves that reflect the states and faults,the detection of the corresponding stress wave can be used as a potential IGBT state monitoring scheme.In this thesis,the mechanical stress wave of IGBT switch is studied by means of mechanism analysis,experimental verification and signal processing.Firstly,the structure of IGBT is introduced,and the mechanism of internal mechanical stress wave generation and propagation under different operating conditions is analyzed from the microscopic level,which lays a theoretical foundation for later experimental research.Then from the principle of the measurement platform,the principle of the mechanical stress wave test circuit,the drive circuit and the multichannel signal measurement platform are introduced,and the physical c onstruction is completed.At the same time,the mechanical stress wave signals generated in the IGBT under different conditions are measured online in real time.Finally,the time and frequency domain analysis of the collected signals was used to quickly extract the characteristic parameters of the mechanical stress wave.It was found that the IGBT will generate an acoustic emission signal when it is turned on and off.The signal amplitude at the time of turn-on is positive,and the signal amplitude is turned off.It is negative.The signal is mainly concentrated around 50-150Khz and 2.7Mhz.At the same time,the acoustic emission signal is composed of electromagnetic wave signals and low-frequency stress wave signals.When the collector-emitter voltage V_CE is unchanged,the trigger pulse width is changed.The amplitude of the pulse peak of the acoustic emission signal is unchanged,and the low-frequency and high-frequency acoustic emission signals have the same characteristics,and the change of the pulse width has basically no effect on the frequency range of the mechanical stress wave,but only the superposition time of the time-domain waveform is changed,resulting in the time-domain waveform.Inconsistent;when the trigger pulse width is the same,the amplitude of the acoustic emission signal pulse peak at the time of opening inc reases with the increase of V_CE,which shows a linear growth trend,and the low-frequency and high-frequency acoustic emission signals also have the same characteristics.Shape has basically no effect,but only changes the signal amplitude;IGBT will also Acoustic emission signal is generated,and the high frequency portion of the acoustic emission signals related V_CE,and found relevant when the breaking current,the energy of the acoustic emission signal is significantly increased.In this thesis,a fast,non-intrusive,real-time on-line mechanical stress wave measurement and characteristic parameter extraction method is established through the study of IGBT switch mechanical stress waves.The final purpose is to establish the relationship between IGBT parameters and the characteristic parameters of mechanical stress wave of switch.Research on the reliability evaluation and performance improvement of large-capacity power electronics equipment provides theoretical and technical support.