Electric power unit

Claim 2

An electric power unit, comprising: a rectifier circuit receiving AC power from an AC power source on at least first and second input terminals, providing rectified power on at least one output terminal, and having a voltage-multiplying rectification function and a non-voltage-multiplying rectification function, said rectifier circuit comprising a voltage-multiplying circuit and switch means for selectively rendering operative said voltage-multiplying circuit; a switching circuit coupled to said rectifier circuit for selecting as an operating rectification function one of said voltage-multiplying rectification function and said non-voltage-multiplying rectification function of said rectifier circuit; switching control circuit means for controlling said switching circuit according to a reference potential of an AC input voltage derived from said AC power or said rectifier circuit, said switching control circuit control means comprising a diode having a first terminal coupled to said first input terminal, a capacitor having a first terminal coupled to a second terminal of said diode and a second terminal connected to said second input terminal, a Zener diode having a first terminal coupled to said second terminal of said diode, and an amplifying transistor having a base coupled to a second terminal of said Zener diode and an output electrode coupled to an input of said switching circuit; and an auxiliary power source circuit for establishing a voltage for powering said switching control circuit.

Claim 3

The electric power unit of claim 1, wherein said switching circuit comprises a second transistor having a base coupled to a collector of said firstmentioned transistor and an emitter coupled to a control input of said switch means.

Claim 4

The electric power unit of claim 2, wherein said auxiliary power source is coupled to receive AC input power from an AC input source different than an AC input source supplying said AC input voltage to said rectifier circuit.

Claim 5

The electric power unit of claim 3, wherein said switch means comprises a triode AC switch.

Claim 6

An electric power unit comprising: a bridge rectifier circuit having first and second input terminals coupled to a first AC source, output terminals of said bridge rectifier circuit being coupled to corresponding first and second output terminals; a first capacitor having a first terminal coupled to said first output terminal; a second capacitor having a first terminal coupled to a second terminal of said first capacitor and a second terminal coupled to said second output terminal; a first resistor having a first terminal coupled to said first output terminal; a second resistor having a first terminal coupled to a second terminal of said first resistor and a second terminal of said first capacitor and a second terminal coupled to said second output terminal; a triode AC switch having a first main terminal coupled to said second input terminal and a second main terminal coupled to said second terminal of said first capacitor; a first transistor having an emitter coupled to a control terminal of said triode AC switch; a third resistor having a first terminal coupled to said second input terminal and a second terminal coupled to said emitter of said first transistor; a fourth resistor coupled between a base and a collector of said first transistor; a second transistor having a collector coupled to said base of said first transistor; a fifth resistor coupled between said collector of said first transistor and a base of said second transistor; a sixth resistor coupled between a base and an emitter of said second transistor; a Zener diode having an anode coupled to said base of said second transistor; a seventh resistor having a first terminal coupled to a cathode of said Zener diode; a diode having an anode coupled to said first input terminal and a cathode coupled to a second terminal of said seventh resistor; a third capacitor coupled between said cathode of said diode and said emitter of said second transistor; and a DC power supply for providing a DC voltage between said collector of said first transistor and said emitter of said second transistor.

Claim 7

An electric power unit comprising: a bridge rectifier circuit having first and second input terminals coupled to a first AC source, output terminals of said bridge rectifier circuit being coupled to corresponding first and second output terminals; a first capacitor having a first terminal coupled to said first output terminal; a second capacitor having a first terminal coupled to a second terminal of said first capacitor and a second terminal coupled to said second output terminal; a first resistor having a first terminal coupled to said first output terminal; a second resistor having a first terminal coupled to a second terminal of said first resistor and a second terminal of said first capacitor and a second terminal coupled to said second output terminal; a triode AC switch having a first main terminal coupled to said second input terminal and a second main terminal coupled to said second terminal of said first capacitor; a first transistor having an emitter coupled to a control terminal of said triode AC switch; a third resistor having a first terminal coupled to said second input terminal and a second terminal coupled to said emitter of said first transistor; a fourth resistor coupled between a base and a collector of said first transistor; a second transistor having a collector coupled to said base of said first transistor; a fifth resistor coupled between said collector of said first transistor and a base of said second transistor; a sixth resistor coupled between a base and an emitter of said second transistor; a Zener diode having an anode coupled to said base of said second transistor; a seventh resistor having a first terminal coupled to a cathode of said Zener diode; a diode having an anode coupled to said first input terminal and a cathode coupled to a second terminal of said seventh resistor; a third capacitor coupled between said cathode of said diode and said emitter of said second transistor; and a DC power supply for providing a DC voltage between said collector of said first transistor and said emitter of said second transistor.

Claim 8

The electric power unit of claim 5, wherein said DC power supply comprises a transformer having a primary coupled to a second AC source different from said first AC source coupled to said first and second input terminals; a second diode having an anode coupled to a first terminal of a secondary of said transformer and a cathode coupled to said collector of said first transistor; and a fourth capacitor having a first terminal coupled to said cathode of said second diode and a second terminal coupled to a second terminal of said secondary and said second input terminal.