HIGH DC TO LOW DC VOLTAGE CONVERTER

• US 3,708,742 A
• Filed: 06/30/1971
• Issued: 01/02/1973
• Est. Priority Date: 06/30/1971
• Status: Expired due to Term

• Current Assignee: John B. Gunn
• Original Assignee: John B. Gunn
• Inventors: Gunn, John B.
• Primary Examiner(s): Shoop, Jr., William M.
• Application Number:
  US05/158,173
• Time in Patent Office: 552 Days
• Field of Search: 321/2,15,18 307/150
• US Class Current: 363/62
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps

Abstract

Transformerless high DC to low DC voltage conversion is achieved by alternately charging a plurality of capacitors in series from the input voltage source, and discharging them in parallel into the load. The charging and discharging are effected by transistor switches, which are in turn controlled by the voltage across one of the plurality of capacitors. Charging stops, and discharging begins, when this voltage rises above a first predetermined value; discharging stops, and charging begins, when this voltage falls below a second, lower, predetermined value. During charging, voltage across the load is maintained by a permanently connected reservoir capacitor. The difference between the predetermined voltage values, and hence the ripple on the output voltage, is preselected by certain circuit constants, whereas the mean of the two values is controlled by comparing the DC component of the output voltage with a reference value, so as to maintain the DC load voltage constant despite variations in load current.

Claims

1. A power conversion circuit for converting DC power at an input voltage level to DC power at a lower controlled output voltage level, comprising:

input terminals adapted to receive DC power from a source and output terminals adapted to deliver DC power to a load;

storage means including at least one stage of charge storage means, input switching means of controllable conductance for controllably coupling said at least one stage of charge storage means in series with said input terminals;

output switching means of controllable conductance for controllably coupling said at least one stage of charge storage means in parallel with said output terminals;

first control means for rendering said output switching means non-conductive when said input switching means is conductive and for rendering said output switching means conductive when said input switching means is non-conductive;

second control means for rendering said input switching means conductive when the voltage across said charge storage means falls below one voltage level and for rendering said input switching means non-conductive when the voltage across said charge storage means rises above another voltage level; and

means for establishing said one and another voltage levels.

2. The conversion circuit as set forth in claim 1 further including charge storage means coupled between said output terminals.

3. The conversion circuit set forth in claim 1 wherein said means for establishing said one and another voltage levels is responsive to changes in voltage across said output terminals, whereby said output voltage level is maintained at a predetermined value.

4. A voltage conversion circuit for converting the DC voltage level of a DC input voltage, comprising:

controllable conductance means having a first teRminal coupled to said DC input voltage, a second terminal and control means for controlling the conductance of said controllable conductance means;

storage means having a plurality of stages each including charge storing means with each of said charge storing means arranged to be coupled in series to said second terminal for the charging thereof when said controllable conductance means is in a high conduction condition and coupled in parallel for the discharging thereof when said controllable conductance means is in a low conduction condition; and

means coupling said storage means to the said control means of said controllable conductance means for causing said controllable conductance means to go into a high conduction condition when the voltage level of said storage means falls below a predetermined level.

5. The conversion circuit as set forth in claim 4 wherein said storage means includes further charge storing means coupled to each of said plurality of stages so as to be in the parallel discharge path of each of the said charge storing means thereof.

6. The conversion circuit as set forth in claim 5 wherein said means coupling said storage means includes AC coupling means coupled to one of said charge storing means and DC coupling means coupled to said further charge storing means.

7. The conversion circuit as set forth in claim 5 wherein said means coupling said storage means includes detection means and further includes AC coupling means coupling the AC component from one of said charge storing means to said detection means and DC coupling means for coupling the DC component from said further charge storage means to said detection means.

8. The conversion circuit as set forth in claim 7 wherein said plurality of stages each include diode means which are forwardly biased to connect each of the said charge storing means in series to the said second terminal of said controllable conductance means for the charging thereof when said controllable conductance means is in a high conduction condition and which are reversedly biased to disconnect each of the charge storing means to thereby allow the discharge thereof when said controllable conductance means is in a low conduction condition.

9. The conversion circuit as set forth in claim 8 wherein said plurality of stages each include transistor means coupled between the said charge storing means for each of said stages and said further charge storage means, so that each of said transistor means become forwardly biased when said diode means become reversedly biased to thereby provide respective parallel discharge paths to said further charge storage means for each of said charge storing means.

10. A voltage conversion circuit for converting high voltage DC to low voltage DC, comprising:

switching means having a first terminal coupled to said high voltage DC, a second terminal and a control means for controlling said switching means;

a plurality of storage stages each including storage means all of which are arranged to be coupled in series to said second terminal for the charging thereof when said switching means is turned on and coupled in parallel for the discharging thereof when said switching means is turned off; and

means coupling one of said storage means to said control means to turn said switching means on when the level of stored charge falls below a predetermined level and to turn said switching means off when the level of stored charge rises above a second predetermined level.

11. A voltage conversion circuit for converting a high voltage DC input to a low voltage DC output, comprising:

switching means having a first terminal coupled to said high voltage DC input, a second terminal and a control terminal;

storage means including a plurality of capacitance storage means each coupled to another in series to said second terminal by first means and connected to one another in parallel by second means, said first means being operative to coNnect said capacitance storage means in series when said switching means is conductive and said second means being operative to connect said capacitance storage means in parallel when said switching means is non-conductive; and

means coupling the potential on one of said capacitance storage means to the said control terminal of said switching means to cause said switching means to become conductive when the voltage on said one capacitance storage means discharges to a predetermined voltage level.

12. The voltage conversion circuit as set forth in claim 11 wherein said means coupling include amplitude detection means and AC coupling means for coupling the AC component of the said potential on said one capacitance storage means to said amplitude detection means so that said switching means become conductive when the voltage on said one capacitance storage means discharges to a first predetermined voltage level and become nonconductive when the voltage on said one capacitance storage means charges to a second predetermined voltage level.

13. The voltage conversion circuit as set forth in claim 12 wherein said means coupling include DC coupling means for coupling the DC component of said low voltage DC output to said amplitude detection means whereby regulation of the output voltage is obtained with varying load currents.

14. The voltage conversion circuit as set forth in claim 13 wherein output voltage storage means are coupled to the said second means to connect said capacitance storage means in parallel and to said DC coupling means so as to thereby couple the DC voltage across said output voltage storage means to said amplitude detection means.

15. The voltage conversion circuit as set forth in claim 12 wherein said storage means includes output voltage capacitance storage means coupled to each of said plurality of capacitance storage means through said second means to connect said capacitance storage means in parallel whereby each of said plurality of capacitance storage means discharge in parallel to said output voltage capacitance storage means.

16. The voltage conversion circuit as set forth in claim 15 wherein said coupling means include DC coupling means coupling the voltage across said output voltage capacitance storage means to said amplitude detection means.

17. The voltage conversion circuit as set forth in claim 16 wherein said amplitude detection means includes differential amplifier means for comparing the composite of said AC voltage from said one capacitance storage means and the DC voltage from said output voltage capacitance storage means with a reference voltage so that when said composite is sufficiently different in value from said reference voltage said differential amplifier means acts to cause said switching means to become conductive.

18. The voltage conversion circuit as set forth in claim 17 including feedback means coupling the said second terminal of said switching means to said differential amplifier means.

19. The voltage conversion circuit as set forth in claim 18 wherein said first means are diode means and said second means are transistor means.

20. A voltage conversion circuit for converting a high voltage DC input to a low voltage regulated DC output, comprising:

switching means having a first terminal coupled to said high voltage DC input, a second terminal and control means;

voltage storage means including a plurality of capacitance storage means;

output voltage storage means;

coupling means coupling said plurality of capacitance storage means in series to the said second terminal of said switching means for the charging thereof when said switching means is in a high conduction condition and in parallel to said output voltage storage means for the discharging thereof when said switching means is in a low conduction condition;

compare circuit means coupled to one of said plurality of capacitance storage means and to reference voltage means for comparing the Voltage on said one capacitance storage means with the voltage of said reference voltage means; and

means coupling said compare circuit means to the said control means of said switching means for causing said switching means to enter into said high conduction condition when the voltage on said one capacitance storage means discharges to a first predetermined voltage level with respect to the voltage level of said reference voltage and into a low conduction condition when the voltage on said one capacitance storage means charges to a second predetermined voltage level with respect to the voltage level of said reference voltage.

21. The voltage conversion circuit as set forth in claim 20 wherein said compare circuit means are AC coupled to said one capacitance storage means and DC coupled said output voltage storage means so as to thereby provide voltage regulation at the output against varying load conditions.