Electric power supply circuit capable of reducing a loss of electric power

• US 4,644,458 A
• Filed: 03/18/1985
• Issued: 02/17/1987
• Est. Priority Date: 03/19/1984
• Status: Expired due to Term

• Current Assignee: NEC Corporation, Nippon Telegraph and Telephone Corporation
• Original Assignee: NEC Corporation, Nippon Telegraph and Telephone Corporation
• Inventors: Yamamoto, Hideki, Yamamoto, Katsuhiko, Harafuji, Yoshihiko
• Primary Examiner(s): Wong, Peter S.
• Application Number:
  US06/712,990
• Time in Patent Office: 701 Days
• Field of Search: 363/15, 363/37, 363/50-58, 363/65, 363/68, 363/71, 363/95-98, 323/271
• US Class Current: 363/65
• CPC Class Codes: H04B 3/44 Arrangements for feeding power to a repeater along the transmission line

Abstract

In an electric power supply circuit comprising a plurality of constant current units each of which is controllable by a control voltage (V_c) to keep a circuit output current (I_OUT) substantially constant and which has no shunt resistor, the control voltage is supplied from a single current to voltage converter (44) operable in response to a control current (I_c) corresponding to the circuit output current. A control unit (39) produces the control current in response to a detection signal supplied from a current detector (37) and representative of a result of detection of the circuit output current. A plurality of current detectors may be coupled to a plurality of control units coupled in common to the single current to voltage converter. The single current to voltage converter may be a saturable reactor, a resistor, or the like. Alternatively, each of the constant current units may comprise a shunt resistor when the shunt resistor is connected in series to a current restriction circuit coupled to an additional winding attached to the current detector.

Claims

1. An electric power supply circuit including a plurality of constant current units connected in series to a pair of terminals for supplying an electric current to a current path which is shared by said constant current units as a load, current detecting means coupled to said current path for detecting said electric current to produce a detection signal having a detection voltage, and control means responsive to said detection signal for producing a control current, each of said constant current units being controllable by a control voltage corresponding to said control current to share said load with the respective constant current units as partial loads of a predetermined distribution, wherein the improvement comprises:

single current to voltage converting means coupled to said control means and responsive to said control current for converting said control current into a converted voltage;

voltage supply means coupled to said current to voltage converting means for supplying said converted voltage to said constant current units in common as said control voltage to control said partial loads in compliance with said predetermined distribution;

said current detecting means comprises;

a plurality of current detectors coupled to said current path for detecting said electric current to produce a plurality of partial detection signals as said detection signal; and

said control means comprising;

a plurality of control circuits coupled to the respective current detectors for supplying a plurality of partial control currents to said single current to voltage converting means as said control current.

2. An electric power supply circuit as claimed in claim 1, wherein said control means comprises:

reference signal producing means for producing a reference voltage;

comparing means responsive to said detection signal and coupled to said reference signal producing means for comparing said detection voltage with said reference voltage to produce a difference voltage signal representative of a difference between said detection voltage and said reference voltage; and

converting means responsive to said difference voltage signal for converting said difference voltage signal into said control current.

3. A constant current unit for use in producing a circuit output current and comprising a controllable current source responsive to a local signal for providing a source current, a resistor for partially making a shunt current flow therethrough to divide said source current into said circuit output current and said shunt current, first current detecting means for detecting current from either said circuit output current or said source current to produce a detection signal, control means responsive to said detection signal for producing a control signal, and means for supplying said control signal as said local signal to said controllable current source, wherein the improvement comprises:

second current detecting means for detecting a second current related to said selected one of the circuit output and the source currents; and

current restriction means connected in series to said resistor for restricting said shunt current with reference to said second current.

4. A constant current unit as claimed in claim 3, wherein said detected current is said circuit output current.

5. A constant current unit as claimed in claim 3, wherein said said detected current is said source current.

6. An electric power supply circuit comprising:

a plurality of constant current units which are connected in series to a pair of terminals in order to supply an electric current to a load in a current path which is shared by said constant current, each of said constant current units comprising a voltage to frequency converter means operated responsive to a voltage signal having a voltage level for converting said voltage signal into a signal having a frequency which is determined by said voltage level, and d.c. to d.c. converting means responsive to a d.c. input signal and to said frequency signal for converting said d.c. input signal into a d.c. output signal with reference to said frequency signal;

current detecting means coupled to said current path for detecting said electric current in order to produce a detection signal having a detection voltage;

control means responsive to said detection signal for producing a control current which is dependent on said detection signal;

current to voltage converting means coupled to said control means for converting said control current into a converted voltage signal; and

voltage supply means coupled to said current to voltage converting means for supplying said converted signal to said constant current units in common.

7. An electric power supply circuit as claimed in claim 6, wherein:

said current detecting means comprises;

a plurality of current detectors coupled to said current path for detecting said electric current to produce a plurality of partial detection signals as said detection signal;

said control means comprising;

a plurality of control circuits coupled to the respective current detectors for supplying a plurality of partial control currents to said single current to voltage converting means as said control current.

8. An electric power supply circuit as claimed in claim 6, wherein said current detecting means comprises:

a single current detector for detecting said electric current to produce said detection signal;

said control means comprising;

a control circuit coupled between said single current detector and said current to voltage converting means for supplying said control current to said current to voltage converting means.

9. An electric power supply circuit as claimed in claim 6, wherein said d.c. to d.c. converting means comprises a serial resonant circuit having a resonant frequency related to said frequency of the frequency signal.