Apparatus to control multiple parallel batteries to share load current

• US 6,208,039 B1
• Filed: 08/17/1999
• Issued: 03/27/2001
• Est. Priority Date: 08/17/1999
• Status: Expired due to Term

• Current Assignee: Space Systems/Loral Incorporated (Loral Space and Communications Incorporated)
• Original Assignee: Space Systems/Loral Incorporated (Loral Space and Communications Incorporated)
• Inventors: Canzano, Steven M., Mendelsohn, Aaron J.
• Primary Examiner(s): FLEMING, FRITZ M
• Application Number:
  US09/375,871
• Time in Patent Office: 588 Days
• Field of Search: 307/44, 307/48, 307/52, 307/69, 320/3, 320/6, 320/21, 320/61, 340/636, 340/660, 340/661
• US Class Current: 307/52
• CPC Class Codes: H02J 7/0018 using separate charge circuits
• CPC Class Codes: H02J 7/0024 Parallel/serial switching of connection of batteries to charge or load circuit

Abstract

Circuit apparatus for controlling a plurality of parallel connected batteries to equally share a common load is shown that includes an n parallel batteries connected to a common load element through a load current monitor that monitors the current through the load element, a battery current monitor for each battery, and a plurality of DC/DC converter circuits having outputs connected in series with each battery respectively. The load current output signal of the load current monitor is scaled down by 1/n, where n is the number of batteries, by a scale down amplifier circuit and distributed as a reference voltage to summing circuits where the scaled down load current is compared to the output of the battery current monitors. The outputs of the summing circuits are respectively connected as control signals to each of the DC/DC converters that are connected to each battery. Each DC/DC converter circuit adjusts it'"'"'s output voltage to regulate the battery currents to I1 . . . In of each of the n batteries to be equal to the reference voltage from the load current monitor.

Claims

1. Apparatus for controlling a plurality of parallel connected batteries to share the load current of a common load element comprising:

a plurality of n batteries connected in parallel to a common load element;

a plurality of n DC/DC converter circuits, and a plurality of n battery current monitor circuits, one DC/DC converter circuit and one battery current monitor circuit connected in series with one of the n batteries;

a single load current monitor circuit connected in series between the outputs of the plurality of n battery current monitors and the load element to provide an output signal representative of the load current of the load element, the output signal of the load current monitor circuit being connected to each of the n DC/DC converter circuits and connected to a single scale amplifier circuit to scale down the output signal from the load current monitor wherein the scaled down load current output signal from the scale amplifier circuit is fed back and connected to each of the n DC/DC converter circuits;

a plurality of n summing circuits, each having a first input connected to the output of the scaling amplifier, and a second input connected to the output of a separate one of the n battery current monitor circuits wherein each summing circuit provides an output control signal, and wherein the output control signal from each of the n summing circuits is connected to a separate one of the n DC/DC converter circuits connected in series with each of the n batteries for controlling the battery current of each battery wherein each battery shares the load current.

2. The apparatus of claim 1 wherein each of the n batteries is comprised of N battery cells.

3. Apparatus for controlling a plurality of parallel connected batteries to share the load current of a common load element comprising:

a plurality of n batteries connected in parallel to a common load element;

a plurality of n DC/DC converter circuits, and a plurality of n battery current monitor circuits, one DC/DC converter circuit and one battery current monitor circuit connected in series with one of the n batteries;

a load current monitor circuit connected in series with the load element to provide an output signal representative of the load current of the load element, the output signal of the load current monitor circuit being connected to each of the n DC/DC converter circuits and connected to a scale amplifier circuit to scale down the output signal from the load current monitor;

a plurality of n summing circuits, each having a first input connected to the output of the scaling amplifier, and a second input connected to the output of a separate one of the n battery current monitor circuits wherein each summing circuit provides an output control signal, and wherein the output control signal from each of the n summing circuits is connected to a separate one of the n DC/DC converter circuits connected in series with each of the n batteries for controlling the battery current of each battery wherein each battery shares the load current;

wherein the scale amplifier circuit scales down the output signal from the load current monitor by a factor of n, where n is the number of batteries connected in parallel.

4. Apparatus for controlling a plurality of parallel connected batteries to share the load current of a common load element comprising:

a plurality of n batteries connected in parallel to a common load element;

a plurality of n DC/DC converter circuits, and a plurality of n battery current monitor circuits, one DC/DC converter circuit and one battery current monitor circuit connected in series with one of the n batteries;

a load current monitor circuit connected in series with the load element to provide an output signal representative of the load current of the load element, the output signal of the load current monitor circuit being connected to each of the n DC/DC converter circuits and connected to a scale amplifier circuit to scale down the output signal from the load current monitor;

a plurality of n summing circuits, each having a first input connected to the output of the scaling amplifier, and a second input connected to the output of a separate one of the n battery current monitor circuits wherein each summing circuit provides an output control signal, and wherein the output control signal from each of the n summing circuits is connected to a separate one of the n DC/DC converter circuits connected in series with each of the n batteries for controlling the battery current of each battery wherein each battery shares the load current;

wherein each DC/DC converter circuit is responsive to the output signal of the summing circuit connected thereto to adjust its output voltage to be equal to the reference voltage from the load current monitor by regulating the current through the battery connected in series therewith.