Remote battery charging system with dynamic voltage adjustment and method of use

• US 8,138,723 B2
• Filed: 05/26/2008
• Issued: 03/20/2012
• Est. Priority Date: 05/26/2008
• Status: Expired due to Fees

• Current Assignee: Galvion Power Systems Incorporated
• Original Assignee: Steve Carkner
• Inventors: Carkner, Steve
• Primary Examiner(s): Tso, Edward
• Assistant Examiner(s): OMAR, AHMED H
• Application Number:
  US12/126,973
• Publication Number:
  US 20090289604A1
• Time in Patent Office: 1,394 Days
• Field of Search: 320/137
• US Class Current: 320/137
• CPC Class Codes: H02J 7/0071 with a programmable schedule

Abstract

In a remote battery charging system comprising a charging circuit there is always a voltage loss due to inherent resistances in the system from such things as connectors and conductors. These resistances create voltages losses in the system such that charging time are increased substantially. The present invention compensates for voltage losses on the system by generating a dynamic adjustment voltage over the charging period. A voltage translator circuit is used to measure charging circuit output voltage and current over a plurality of incremental time periods during the charging period an calculate a signal proportional to changes in output voltage and current over the incremental time period. The signal is then applied to the charging circuit to offset any voltage losses.

Claims

1. A remote dynamically compensated battery charging system having an dynamic voltage source having a system output voltage V_O and a system output current I_O for charging at least one battery having a maximum voltage V_Batt over a charging time period T, said system comprising:

a. a positive conductor and a ground conductor for connecting said at least one battery to the system, wherein said positive and ground conductors have an undetermined aggregate, and dynamic inherent resistance R_i causing a dynamic inherent voltage loss V_i;

b. a microprocessor for measuring, over incremental time periods t changes to I_o(dI_o /dt) and changes to V_o(dV_o /dt) caused by R_i;

c. said microprocessor generating a signal S proportional to one of dV_o /dt and dI_o /dt;

d. a voltage translator circuit for receiving said signal S and calculating an incremental offset voltage V_off /dt;

e. said voltage translator circuit adding V_off/dt to V_o thereby dynamically compensating for V_i over charging period T.

2. The system of claim 1 wherein T comprises a T_CC and a T_CV during which times the system is in a constant current mode and a constant voltage mode respectively and a transition point between T_CC and T_CV, so that:

a. during T_CC V_off is zero;

b. at said transition point and during T_CV point the microprocessor;

i. measures V_o during time periods t;

ii. calculates dV_o /dt;

iii. measures I_o during said time periods t;

iv. calculates dI_o /dt;

v. calculates dR_i /dt- dV_o /dI_o;

vi. calculates V_off /dt as dR_i/dt X I_o; and

,

c. wherein the voltage translator circuit adds V_off /dt to V_o the result being that V_o is always greater than V_Batt during T_cv.

3. The system of claim 2 wherein the microprocessor includes a first sub-program to reduce V_o during T_CC so that V_o plus V_off is less than that V_Batt.

4. The system of claim 3 wherein the microprocessor includes a second sub-program to sum V_off and V_o during T_CV so that Vo is always greater than V_Batt.

5. The system of claim 1 wherein the system has an undetermined, aggregate and dynamic resistance R_sys causing a dynamic inherent system voltage loss V_sys and wherein the least one battery includes a safety thermistor having an R_therm said system further comprising:

a. a current limiter connected between the dynamic voltage source the positive conductor;

b. a current monitor connected between the dynamic voltage source and the ground conductor;

c. said microcontroller connected to a third conductor through an A/D converter and wherein said third conductor has a biasing current source;

d. wherein said safety thermistor is connected to the microprocessor by the third conductor having a resistance R₃ and a biasing current I_bias wherein R₃ is negligible compared to R_therm and l_bias is negligible compared to I_o and wherein I_bias and R₃ produce a voltage V₃ at said analogue/digital converter;

e. wherein when I_bias is zero. R₃=R_sys so that said microcontroller calculates V_off as a function of R_sys and adds V_off to V_o.

6. The system of claim 5 wherein when the positive conductor comprises a single wire and the ground conductor comprises a first and a second parallel wires, the result being that the resistance in the positive wire is twice the resistance in any of said first and said second wires.

7. The system of claim 6 wherein the at least one battery comprises a thermistor and the microprocessor comprises a mathematical summing node in series with a current monitor and an A/D converter connected to said thermistor by a third conductor having similar resistance to the positive and ground conductors and wherein said current monitor transmits the magnitude of dI_o /dt to said mathematical summing node where it is converted into a control signal S′

for transmission to the adjustable voltage source to determine V_off /dt and adjust V_o dynamically over charge time T in order to optimize I_o and wherein the microprocessor controls a bias current in the third conductor for battery temperature measurement, so that when the microprocessor terminates said bias current, it is able to measure a voltage loss in the third conductor and calculate V_off as twice said voltage loss in the third conductor.

8. A method of dynamically compensating a battery charging system having a charging circuit for generating an dynamic output voltage V_o and a dynamic output current I_O for charging an at least one battery, said at least one battery having a thermistor and a predetermined maximum battery voltage V_Batt said method comprising the steps of:

a. connecting said at least one battery to said charging circuit by a positive conductor and a around conductor wherein said positive and ground conductors have an aggregate inherent resistance R_i causing an aggregate voltage loss V_i at a current level of I_o

b. connecting said thermistor between the second ground conductor and a third conductor;

c. connecting a microprocessor to said third conductor;

d. connecting an A/D converter serially between said third conductor and said microprocessor;

e. applying a bias current I_bias to the third conductor for measuring resistance within the thermistor;

f. terminating I_bias;

g. measuring a voltage loss V₃ in the third conductor;

h. calculating V_off based upon V₃ such that V_off =2V₃ ; and

,

i. dynamically adjusting V_Oby V_Off.

9. A method of dynamically compensating a battery charging system haying a charging circuit for generating an dynamic output voltage V_o and a dynamic output current I_o for charging an at least one buttery during a time T and a current monitor and a voltage monitor, said at least one batter having a predetermined maximum battery voltage V_Batt said system having an approximated aggregate system resistance R_sys said method comprising the steps of:

a. setting said charging circuit to compensate for R_sys;

b. connecting a mathematical summing node in series with said current monitor;

c. measuring the magnitude ofI_o;

d. measuring during time T and at intervals of t, changes in I_o;

e. transmitting changes in I_o to said mathematical summing node;

f. using the mathematical summing mode to convert the changes in I_o into a control signal S′

; and

,

g. transmitting said control signal S′

to said adjustable voltage source to adjust Vo by a V_off based on changes in I_o.

10. The method of claim 9 further comprising the steps of:

a. providing a microprocessor within said charging circuit for measuring during T, at time intervals of t, changes to I_o and V_o;

b. said microprocessor generating a signal S proportional to said changes to I_o and V_o;

c. the microprocessor applying signal S to said charging circuit to generate an variable offset voltage V_off ; and

,

d. the microprocessor summing V_off and V_o during a constant current charging mode so that the sum is always less than V_Batt.

11. A method of dynamically compensating a battery charging system having a charging circuit for generating an dynamic output voltage V_o and a dynamic output current I_O for charging an at least one battery during a time T and a current monitor and a voltage monitor, said at least one battery having a predetermined maximum battery voltage V_Batt said method comprising the steps of:

a. adding a temperature sensitive resistor to said at least one battery for battery temperature measurement;

b. connecting said temperature sensitive resistor between said second ground conductor and a third conductor wherein said third conductor has a resistance similar to the first positive and second ground conductors;

c. providing an analogue to digital converter within the battery charger;

d. connecting said analogue to digital converter between the third conductor and the microprocessor;

e. applying a bias current to the third conductor for measuring resistance within the temperature sensitive resistor;

f. terminating said bias current;

g. measuring V_i in the third conductor;

h. applying said V_i to the first positive and second ground conductors; and

,

i. calculating V_off based upon the V_i, in the first positive and the second ground conductors; and

,

j. adjusting V_o by V_off .