Standby electric supply and a method for controlling the operation of a standby electric supply

• US 7,015,699 B1
• Filed: 11/03/2000
• Issued: 03/21/2006
• Est. Priority Date: 11/05/1999
• Status: Expired due to Fees

• Current Assignee: Delta Energy Systems (Switzerland) AG (Delta Electronics Incorporated)
• Original Assignee: Delta Energy Systems (Switzerland) AG (Delta Electronics Incorporated)
• Inventors: Suntio, Teuvo
• Primary Examiner(s): TIBBITS, PIA FLORENCE
• Application Number:
  US10/111,584
• Time in Patent Office: 1,964 Days
• Field of Search: 324/429, 320/116, 320/122, 307/10.6, 307/64, 307/66
• US Class Current: 324/429
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/00718 in response to charge current gradient
• CPC Class Codes: H02J 7/007184 in response to battery voltage gradient
• CPC Class Codes: H02J 9/06 with automatic change-over , e.g. UPS systems
• CPC Class Codes: Y02B 70/30 Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
• CPC Class Codes: Y04S 20/20 End-user application control systems

Abstract

The standby electric supply comprises an accumulator which comprises multiple interconnected blocks, a switching portion that conditionally connects the accumulator to a load or to a charging current supply and a measurement and control portion that produces measurement results for describing the state of the accumulator and that controls the switching portion on the basis of the measurement results produced. The measurement and control portion is arranged to measure, at an initial time, the initial value of the open cell voltage of each block from the accumulator when charged and to produce a threshold value from the measured block specific initial value of the open cell voltage. The measured open cell voltage at an observed time different from the initial time is compared with the threshold value. If the measured block specific value of the open cell voltage has reached the threshold value, the switching portion is controlled to connect the accumulator to the charging current supply.

Claims

1. A standby electric supply for ensuring the power for a load, comprising:

an accumulator comprising multiple interconnected blocks;

a switching portion that conditionally connects the accumulator to the load or to a charging current supply;

a measurement and control portion that produces measurement results for describing the state of the accumulator and that controls the switching portion on the basis of the measurement results produced;

wherein the measurement and control portion is arranged;

to measure, at an initial time, the block specific initial value of the open cell voltage from the accumulator when charged;

to produce from the measured block specific initial value of the open cell voltage a threshold value;

to compare a measured block specific open cell voltage value at an observed time different from the initial time with the threshold value; and

if the measured block specific open cell voltage value at the observed time has reached the threshold value, to control the switching portion to connect the accumulator to the charging current supply.

2. A standby electric supply according to claim 1 wherein the measurement and control portion is configured:

to measure a charging current change equal to the value of the change of the charging current in relation to time;

to measure a voltage difference change equal to the value of the change of the voltage difference between the blocks in relation to time; and

responsive to the charging current change, returning from a negative limit value approximately to zero and the voltage difference change, returning from a positive limit value approximately to zero, to control the switching portion to disconnect the accumulator from the charging current supply.

3. A standby electric supply according to claim 1 wherein the switching portion is further arranged to conditionally connect the accumulator to the charging current supply.

4. A standby electric supply according to claim 1 wherein the charging current supply is a first charging current supply, and wherein the switching portion is further arranged to conditionally connect the accumulator to a second charging current supply.

5. A standby electric supply for ensuring the power for a certain load, comprising:

an accumulator comprising multiple interconnected blocks;

a switching portion that conditionally connects the accumulator to the load or to a charging current supply;

a measurement and control portion that produces measurement results for describing the status of the accumulator and that controls the switching portion on the basis of the measurement results produced;

wherein the measurement and control portion is arranged;

to measure a charging current change equal to the value of the change of the charging current in relation to time;

to measure a voltage difference change equal to the value of the change of the voltage difference between the blocks in relation to time; and

responsive to the charging current change, returning from a negative limit value approximately to zero and the voltage difference change, returning from a positive limit value approximately to zero, to control the switching portion to disconnect the accumulator from the charging current supply.

6. A method for controlling a standby electric supply, which comprises an accumulator comprising multiple blocks, comprising:

measuring a block specific initial value of the open cell voltage from the charged accumulator at an initial time;

calculating a threshold value based on the measured block specific initial value of the open cell voltage;

measuring a block specific value of the open cell voltage at an observed time different from the initial time;

comparing the block specific value of the open cell voltage at the observed time with the threshold value; and

connecting a charging current to the accumulator if the measured block specific value of the open cell voltage at the observed time has reached the threshold value.

7. A method according to claim 6 wherein calculating the threshold value comprises calculating a threshold value by a formula $u_{\mathrm{Bi},\mathrm{ocv},\min }=u_{\mathrm{Bi},\mathrm{ocv}}$

(t1)+n·

0.23⁢

mVK·

(TB-TB⁡

(t1))-n·

L·

Δ

⁢

⁢

CC·

100,

in which U_Bi,ocv(t1)=open cell voltage of the i;

th monoblock at time t1, n =number of cells in monoblocks,T_B =temperature of the monoblock at the observed time,T_B(t1) =the temperature of the block at time t1,L =a constant, which describes the influence of the percentagechange of the capacity on the cell voltage, and$\frac{\mathrm{\Delta <br><br>}<br><br><br><br>C}{C}<br><br><br><br>100=$the maximum allowed percentile loss of capacity during theobservation period.

8. A method according to claim 6 wherein measuring a block specific initial value of the open cell voltage occurs at least after 24 hours after a previous charging of the accumulator has ended.

9. A method according to claim 6 further comprising connecting a charging current to the accumulator if a predetermined maximum time has elapsed since a previous charging of the accumulator.

10. A method according to claim 6 further comprising:

measuring a charging current change equal to the value of the charging current change in relation to time;

measuring a voltage difference change equal to the value of the change of the voltage difference between the blocks in relation to time; and

responsive to the charging current change, returning from a negative limit value approximately to zero and the voltage difference change, returning from a positive limit value approximately to zero, the accumulator is disconnected from the charging current.

13. A method according to claim 6, characterized in that

wherein measuring a block specific initial value of the open cell voltage comprises measuring the block specific initial value of the open cell voltage individually for each of the blocks of the accumulator and selecting a smallest measured block specific initial value of the open cell voltage corresponding to a lowest voltage block;

wherein calculating a threshold value includes calculating a threshold value equal to the selected smallest measured block specific initial value less a maximum allowed loss of capacity of the block resulting from discharge and corrected for open cell voltage change based on a difference in temperature at the initial time and at the observed time; and

wherein the block specific open cell voltage value of the open cell voltage at the observed time that is compared to the threshold value is measured from the lowest voltage block.

14. A method according to claim 6, characterized in that

wherein measuring a block specific initial value of the open cell voltage comprises measuring the block specific initial value of the open cell voltage individually for each of the blocks of the accumulator separately from the charged accumulator;

wherein calculating a threshold value includes calculating a threshold value based on the measured block specific initial values less a maximum allowed loss of capacity of the block resulting from discharge and corrected for open cell voltage change based on a difference in temperature at the initial time and at the observed time; and

wherein the block specific open cell voltage value of the open cell voltage at the observed time for each block is compared to the threshold value corresponding to the same block.

11. A method for controlling the operation of a standby electric supply comprising an accumulator comprising multiple blocks, comprising:

measuring a charging current change equal to the value of the charging current change in relation to time;

measuring a voltage difference change equal to the value of the change of the voltage difference between the blocks in relation to time; and

responsive to the charging current change, returning from a negative limit value approximately to zero and the voltage difference change, from a positive limit value approximately to zero, the accumulator is disconnected from the charging current.

12. A method according to claim 11 further comprising:

responsive to the voltage difference change between the blocks in relation to time returning to the positive limit value, and responsive to the time elapsed reaching a certain maximum value, disconnecting the accumulator from the charging current.