Double Pulse Test Set-up: Hardware Design and Measurement Guidelines

A double pulse test (DPT) is commonly used for characterization of power electronic devices. Usually, the device datasheet provides a detailed information about the device under specific operating conditions. However, the datasheet specified operating conditions may be different from the application specific conditions of the user. A DPT setup helps in characterizing a power electronic device under user-specific operating conditions. Further, it also helps in experimental estimation of the device losses and testing of the gate driver protections. This paper discusses the hardware aspects related to the development of a DPT setup for IGBTs with main focus on reducing the cost and size of the DPT board while ensuring higher measurement accuracy. An appropriate selection of load inductor and dc-bus capacitor are discussed in detail. Conventionally, the double pulse in DPT is generated using commercially available microcontrollers. In this work, a cost-effective double pulse generator (DPG) is developed using two IC 555 timers and an AND gate. The circuit uses variable resistors to alter the pulse duration. For higher measurement accuracy, appropriate method of probe and oscilloscope bandwidth selection is discussed along with a few aspects on reduction of parasitic effects.