Compensation Devices Break the Limit Line of Silicon

Abstract

Today’s lifestyle is no longer conceivable without the generation, distribution and conversion of electrical energy. We daily use numerous electrically driven machines, which draw their energy either from AC or DC rails or from batteries. All of these applications require a power conversion from the input line to the desired output voltage. In the past this task was often accomplished by linear voltage regulators, which in the case of AC/DC conversion used huge, heavy chokes. In times of mobile communication and global business, where products are no longer developed for local markets but rather are sold worldwide, this approch is no longer satisfactory. From the manufacturers point of view, platform strategies have the advantage of reduced production complexity and better purchasing conditions due to increased volume. The other driving force is the mobile use of equipment in countries with different AC power supplies: a mobile phone battery may be refueled today in Germany, tomorrow in the US and next week in Japan. The charger has to supply in all cases the same output voltage and current from substantially different input lines. This requirement is best fulfilled today by switch mode power supplies (SMPS). These power converters work typically in the range of 70 to 100 kHz instead of 50 Hz and may therefore use a small, lightweight transformer. This difference in weight is obvious when a switch mode power supply is compared with a linear regulator. A key component of an SMPS is the high-voltage switch, which typically sustains a blocking voltage in the range of 500 to 800 V depending on the chosen circuit topology. A widespread topology for the low end of the power range of up to 200 W is the flyback converter, which transforms the energy in the blocking phase of the switch. This topology requires transistors with 500 to 600 V blocking capability.