A rectifier comprising a preregulator (11; 21) and a DC/DC converter (13; 23) is disclosed, comprising means for controlling the output power P.sub.OUT from the DC/DC converter in dependence of the input power to the preregulator. A method of controlling such a rectifier by controlling the output power P.sub.OUT in dependence of the input current I.sub.IN is also disclosed. This ensures that the output power from the rectifier is never higher than what the preregulator can supply. As a result the rectifier according to the invention may be used at any power level and any input conditions. The output power P.sub.OUT may be controlled by controlling the output current I.sub.OUT from the DC/DC converter.
A control system regulates power to a brushless synchronous generator (BSG) (204) having a permanent magnetic generator (PMG)(210), an exciter (208) and a main generator (206) connected to a rotating shaft (212). The generator control unit (GCU) (202) includes a three phase rectifier (214), a PMG voltage regulator (222), a generator control relay (GCR)(220), a GCU power supply (216) with a backup power source (217), a field switch driver (218), a field switch (219), and a free wheeling diode (221). The BSG (204) is connected to the GCU (202) by coupling the PMG (210) of the BSG (204) to the three phase rectifier (214) of the GCU (202) and by coupling the exciter (208) of the BSG (204) to the PMG voltage regulator (222) and the field switch driver (218) of the GCU (202) and the PMG voltage regulator (222) regulates the voltage of the PMG (210).
A process field device for coupling to a two wire process control loop includes a field device circuitry and a switching regulator to power the circuitry. A series regulator provides a regulated supply voltage to the switching regulator. A noise filter reduces the amount of noise from the switching regulator which enters the two wire process control loop.
