Study Of General Characteristics Measuring System Of PTCR

The main performance characteristics of PTC(Positive Temperature Coefficient)thermal resistance (PTCR) contain R-T, V-I and thermal characteristic etc. The V-I characteristic can also be compartmentalized into two parts in more detail: the zero power V-I characteristic which we generally call it Voltage Effects and static V-I characteristic. The determination of the properties of PTCR materials is very important for their theoretical study and application. This dissertation gives a detailed discussion on the measuring principles and methods of PTCR's R-T and zero power V-I characteristic. Using the high gain data acquisition card PCI-1710HG which based on the computer's PCI slot and combining with the computer automated test technology, we show out the design scheme of how to measure the R-T and zero power V-I characteristic synchronously.This testing system uses short-time DC pulse as the voltage source, in the dissertation, different parts of the system are discussed in modules including the way of gain controllable DC pulse, the drive and control of the PCI-1710HG card, the way of expanding I/O port by using the technology of time multiplexing,means of improving the ability of the system's anti-interference. Through the combination of power electron technology, we give a detail discussion on the use of IGBT (Isolated Gate Bipolar Transistor) in the PTCR testing system, we also show out the specific circuit of IGBT's drive and RCD bumper guard.Besides,the dissertation gives an individual discuss on the software part of the system such as the interface code of the application program, the temperature control code, the code of the data acquisition's drive, automatic shift measure code and data process code and so on. All the codes are programmed under the VC++ platform.From the experimental results, according to some correlative theories, we discuss the PTCR's Voltage Effect under different temperature, and the R-T characteristic under different pulse voltage, and we also compare the similarities and differences between different kinds of PTCR. What we have done may be significant for the study of PTCR's voltage effect and other principles.