Concept of an inductive voltage adder for industrial applications

Summary form only given. We describe the concept of an inductive voltage adder (IVA) which is suitable for industrial pulsed power applications like electroporation (food and beverages, produce / fruits, stark containing products like corn and potatoes, water / wastewater, algae, wet bio material as feedstock for energy applications, etc.), pulsed electrostatic precipitators; pulsed x-ray sources for medical, industrial and security applications; and other novel, environmentally friendly processes. The inductive voltage adder is based on the use of high power semiconductor switch modules which have a longer lifetime, higher reliability and need much less maintenance as conventional spark gaps which are used in today´s Marx generators often used for these applications. The pulse generator is designed to produce a critically damped sinusoidal waveform with a voltage amplitude of up to 250 kV and current amplitude of 10 kA into a matched load, at a pulse duration of typically 1 μs FWHM (full width at half maximum). Thus, the output signal is limited to a bandwidth of around 1 MHz. In contrast to conventional Marx generators, which use spark gaps as switching elements and therefore are limited to pulse repetition rates (PRF) of typically <;50 Hz, the use of solid state technology enables pulse repetition rates far in excess of 100 Hz up to several kHz. Therefore, applications requiring high average power like electroporation of produce, sludge, etc., can be realized much less cost intensive using solid state switching technology than the state-of-the-art Marx generators. Furthermore, the concept of using an IVA at long pulse durations of the order of 1 μs has tremendous advantages over competing designs like Marx generators with solid state switches, or high power modulators using a large number of hard-wired series switches. In the I VA concept, the power is added through vector addition of electromagnetic fields rather than connecting a large num- er of semiconductor switches in series. Therefore, this concept is less prone to device failures, and is easily scalable to almost any desired set of output parameters. On the basis of these simulation results, it is concluded that an inductive voltage adder scheme is feasible for this kind of applications, thus making it possible to introduce pulsed power processes in a large range of industrial applications which were hardly possible up to now due to technical (in particular, lifetime and maintenance) and economic concerns. This work comprises both simulation and experimental work. Fundamental components of the generator like the magnetic coupling (“transformer” section), magnetic isolation and the combining of power have been done on the basis of simulation work using the electromagnetic field simulation program CST. Experimental work based on these simulations comprises the verification of a single pulse module, single IVA stages incorporating several parallel modules, and a multi-module, multi-stage IVA. The IVA concept and results of these simulations and experimental investigations are presented.