A sequenced PWM controlled power conditioning unit for a regulated bus satellite power system

A P.W.M. power system unit is presented for a modular regulated bus concept. This power system is composed of 4 shunt sections and 2×20 AH, Ag-Cd batteries, with independent charger and discharger functions. All these regulators operate under P.W.M. control at 100 KHz sampling frequency and phase shifted synchronisation for minimising ripple and filtering. The sequence of the operation is the following, from eclipse to sunlight. The regulation is first controlled by the boost dischargers and automatically transferred without logics to the regulating bus battery chargers. The shunts operate when the capacity of the batteries is fully satisfied. Charge control of the battery and limitation characteristic of the bus voltage are automatically performed by imposing a pulse width limitation in the P.W.M. control of the charger and discharger functions, without any external sensor. Every regulator is studied separately, then the description of the complete power system is presented and some performances in static and dynamic mode are given.