Research On Temperature Rise Suppression Of IGBT Module Based On Random PWM Control Method

Insulated-gate bipolar transistor(IGBT)is a power electronics switching component,which is widely used in various fields such as household appliances and modern industries due to its excellent performance,and its safety has become one of the hot topics of power electronics research.Research has shown that with the increase of power density and the acceleration of switching frequency at work,the chip temperature of IGBT module will be higher,and the failure rate of transistor will ascend exponentially with the temperature rising,and the failure rate of power device caused by high temperature is more than 50%.Therefore,higher demands are placed on the heat dissipation process of the IGBT modules.The current heat dissipation methods for IGBT modules are mostly focused on the development of different types of external heat sinks or the improvement of microchannel etching techniques for chip structures.These methods have satisfied to a certain extent the requirement that the temperature should not be too high in specific working conditions.However,for applications requiring high-frequency operation of IGBT devices,as the switching frequency of IGBTs rises faster,the heat generated remains concentrated inside the chip and cannot be dissipated quickly,and the temperature rise is not effectively suppressed,which also faces the problem of increased failure rate.In addition,the external heat sink components will also make the IGBT module increased body mass,causing inconvenience to the specific hardware circuit design,as well as resulting in a certain economic loss.In view of the above problems,three stochastic pulse width modulation(PWM)techniques are studied and introduced in this paper,namely,stochastic carrier wave frequency PWM,stochastic duty cycle PWM and stochastic deadtime PWM.By analyzing the heat dissipation process of IGBT module and combining the characteristics of the three stochastic PWM methods,the coincidence point between stochastic PWM method and IGBT module switching process is deduced theoretically(that is,the heat generation and heat dissipation time of IGBT module correspond to the high and low level time of PWM wave),and the temperature gradient between IGBT module and external environment under the action of stochastic PWM method is greater than that under the action of nonstochastic PWM method,and it is theoretically concluded that the heat dissipation of IGBT module under the action of stochastic PWM is more.To verify the reliability of the theoretical derivation,experimental verification is then performed.The experimental means of verification is to observe the temperature rise suppression effect of the three stochastic PWM methods on the IGBT module individually,by the following process: during the operation of IGBT modules driving permanent magnet synchronous motor(PMSM),starting the temperature rise measurement from the identical initial temperature for the IGBT module by introducing nonstochastic and three stochastic PWM modulation methods in the same operation time period respectively.Finally,the temperature rise data are analyzed.The experimental results show that the three stochastic PWM methods perform a suppressive effect on the temperature rise of the IGBT module and could reduce the three-phase current distortion ratio for the motor,which has a positive effect on the stability of motor operation and the safety of the IGBT module.At the same time,the stochastic PWM method is a software technology.The stochastic PWM method and the external heat sink jointly promote the heat dissipation process of the IGBT module in the experiment,which has enlightenment for the combined research of different types of heat dissipation methods.