The electronic circuit for supplying a voltage at a common output terminal (KI.U) has a number of supply circuits, each of which includes a source (B1, B2, . . . , Bn) of electric current and transistors (T10,T11; T20,T21; . . . ; Tn0,Tn1) connected with the source (B1, B2) to form an analog switch for gating the electric current, each supply circuit being connected with the common output terminal (KI.U); and a circuit device for controlling a potential at the gate electrodes of the transistors (T10,T11; T20,T21; . . . ; Tn0,Tn1) in each supply circuit, whereby the supply voltage (UV) is provided by a selected one of the supply circuits. In a preferred embodiment the circuit device for controlling the gate electrode potentials includes a switch (Z) connected between a current supply and the gate electrodes of the transistors in each of the supply circuits by means of at least one resistor and a Zener diode arranged in a blocking direction with another transistor (T12) connected between the Zener diode and the at least one resistor.

A battery charger includes a primary side circuit, a transformer, a secondary side circuit and a control circuit. The secondary side circuit includes a first output unit and a second output unit. The battery charges a main battery and an auxiliary battery. The first output unit, which is connected to a main battery, includes an integrated rectifier-converter and a smoothing circuit. The integrated rectifier-converter is formed using MOSFETs. When charging the auxiliary battery with power from the main battery, power from the main battery is converted by the integrated rectifier-converter to AC power which induces power in an output winding of a transformer connected to the auxiliary battery.

A dual voltage supply system supplies high and low voltage electrical power to separate high and low voltage loads. The system includes an AC alternator and first and second rectifier circuits, each connected to the alternator and a corresponding high and low voltage load. The first rectifier circuit commutates the alternator voltage to the high voltage load when the alternator voltage is higher than a voltage of the high voltage load. The second rectifier circuit commutates the alternator voltage to the low voltage load when the alternator voltage is higher than a voltage of the low voltage load and less than some maximum voltage which is less than the maximum voltage that can be tolerated by the low voltage load(s). The second rectifier circuit is turned off whenever the first rectifier circuit is turned on.

A generator system has two modes of operation, such as 120 VAC and 240/120 VAC. The generator system has a permanent magnet generator with two independent sets of windings that each generate a three phase AC voltage. One three phase AC voltage is coupled to a first cycloconverter and the second three phase AC voltage is coupled to a second cycloconverter. Live outputs of each cycloconverter are coupled to each other through a switch, such as a relay, and netural outputs of each cycloconverter are coupled to ground. A controller controls the cycloconverters to provide the modes of operation. In the 120 VAC mode, the switch across the live outputs of the first and second cycloconverters is closed, shorting the live outputs of the first and second cycloconverters together so that the live outputs are in parallel and the controller operates the first and second cycloconverters so their output voltages are in phase with each other. When in the 240/120 VAC mode, the switch across the live outputs of the first and second cycloconverters is open so that the live outputs are in series and the controller operates the first and second cycloconverters so that their output voltages are 180 degrees out of phase. The permanent magnet generator has rotor position sensors that are used by a DC motor drive to drive the generator as a brushless DC motor to start the engine of the generator system and also to develop cosine wave information for use in controlling the cycloconverters.

A generator system in accordance with the invention has two modes of operation, such as 120 VAC and 240/120 VAC modes of operation. The generator system has a permanent magnet generator with two independent sets of windings that each generate a three phase AC voltage. One three phase AC voltage is coupled to a first or master cycloconverter and the second three phase AC voltage is coupled to a second or slave cycloconverter. Live outputs of each cycloconverter are coupled to each other through a switch, such as a relay and neutral outputs of each cycloconverter are coupled to ground. A controller controls the cycloconverters to provide a first voltage, illustratively 120 VAC, across their respective outputs having the same amplitude. When in the 120 VAC mode, the switch across the live outputs of the first and second cycloconverters is closed, shorting the live outputs of the first and second cycloconverters together and the controller operates the first and second cycloconverters so their output voltages are in phase with each other. When in the 240/120 VAC mode, the switch across the live outputs of the first and second cycloconverters is open and the controller operates the first and second cycloconverters so that their output voltages are 180 degrees out of phase. The permanent magnet generator has rotor position sensors that are used by a brushless DC motor drive to drive the permanent magnet generator as a brushless DC motor to start the engine of the generator system and also to develop cosine wave information for use in controlling the cycloconverters.