NEW COMPACT IGBT MODULES WITH INTEGRATED CURRENT AND TEMPERATURE SENSORS

A new family of compact IGBT modules has been developed to bridge the gap between fully integrated IPM devices and basic IGBT modules. The idea of this new family was to give the designer the dynamic control offered by conventional IGBT modules while maintaining the reliability provided by integrated current and temperature sensing. The result is a new family of dual (half-bridge) modules with ratings ranging from 200A to 800A at 600V and 1200V. Introduction Intelligent power modules (IPMs) containing power semiconductors along with low voltage ICs to provide gate drive and protection functions have been widely accepted for general purpose and high performance industrial motor drive applications ranging from 200W to more than 150kW [5][8]. The success of these modules is the direct result of advantages gained through increased integration. Some of these advantages include the following: (1) Reduced design time and improved reliability offered by the factory tested, built-in gate drive and protection functions, (2) Lower losses resulting from simultaneous optimization of power chips and protection functions, (3) Smaller size resulting from the use of bare power die and control chips, and (4) Improved manufacturability resulting from lower external component count and isolated heat sink mounting surface. Unfortunately, in spite of these advantages, sometimes IPMs are not suitable for certain applications having unique requirements or operating conditions. The main reason for this is that the designer looses the capability to optimize the gate drive conditions and protection circuit operating points. In these situations, the IPM’s built-in protection and gate drive circuits may either be ineffective or interfere with the desired operation of the system. As a result the designer is forced to use conventional IGBT modules containing only the power semiconductor devices. With properly designed gate drive and supporting circuits conventional IGBT modules can be reliably implemented in most industrial applications. However, some features of the IPM provide a level of performance that can not be easily duplicated using conventional IGBT New Compact IGBT Modules with Integrated Current and Temperature Sensors By Eric R. Motto and John F. Donlon modules. In particular, the IPM’s use of temperature sensing that is closely coupled to the power devices and IGBT chips with current mirror features enables very effective protection against excessive temperatures and currents. These features are useful in almost all applications as long as the designer is given the ability to decide how the output of these sensors will be used in a given design. This is the basic concept behind the newly developed IGBT modules presented here. Temperature Sensing The most basic of the IPM’s features that is needed in virtually all power electronics applications is temperature sensing. In systems using conventional IGBT modules the temperature is typically monitored using a sensor mounted on the heat sink. The fundamental problem with this approach is that from the thermal point of view the temperature sensor is relatively far from the power semiconductor chips. In order to set the over temperature protection trip point accurately the designer needs perfect knowledge of the worst case losses in the device and the effective thermal impedance between the measurement point and the power semiconductor chips. The worst case losses are influenced by the system operating modes and normal device to device variations in a complex way. In addition, the effective thermal impedance will vary depending on the module mounting conditions and the distance between the sensor and each individual semiconductor element. If the design does not take all these potential variations into consideration the power semiconductor chip may overheat and fail before the heatsink sensor indicates a problem. If all the worst case variations are considered when setting the protection trip point the protection will work effectively. However, if the typical losses and effective thermal impedance are considerably lower than the worst case then the device will be Figure 1: Compact IGBT Large Package Line-Up: Type Voltage Current MG800J2YS50A 600V 800A MG600Q2YS60A 1200V 600A MG400V2YS60A 1700V 400A 125mm X 96mm