Design of combined wave generator by using universal variable method

The impulse wave generator was constructed for evaluation of the electromagnetic compatibility (EMC) of electronic and electrical devices. In the process of test, a combined wave generator is regularly used which can generate not only certain voltage waves, but also certain current waves. However, the design of this circuit is relatively difficult. This paper describes a method to design the combined wave generator. The method introduces two universal variables used to calculate the modulus decays and frequency of the wave, then gets the circuit parameters by calculation. It can be briefly expressed as, waveform parameters are utilized to specify universal variables, which can be used to define the parameters of different circuit elements. The paper also discusses how to select the parameters in two usually adopted circuits. Moreover, the relationships between the parameters of the circuit and wave front and tail are pointed out. At last, the predominate factors which can greatly change the front and tail are found out: the inductors always influence front and the capacitors and resistors influence both front and tail. By the simulation with the Pspice software and the experiments of several impulse circuits, the method is demonstrated to be credible. Conclusions are drawn that, with this method, the selection of generator parameters turns out to be more reasonable and efficient. The method to design a combined wave generator conforms to relative IEC standard, which means the method can be applied for design.