System and method for rapid charging of a battery

• US 5,233,284 A
• Filed: 05/16/1991
• Issued: 08/03/1993
• Est. Priority Date: 11/25/1988
• Status: Expired due to Fees

• Current Assignee: Bertil Mattsson
• Original Assignee: Bertil Mattsson
• Inventors: Mattsson, Bertil
• Primary Examiner(s): Hickey, R. J.
• Application Number:
  US07/689,771
• Time in Patent Office: 810 Days
• Field of Search: 320/32, 320/39, 320/40, 320/14
• US Class Current: 320/133
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: Y02B 40/00 Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers

Abstract

Method and apparatus for high-rate charging of batteries with sealed cells, whereby through supplied charging current the efficiency the single battery cell is actively influenced such that the charging time and temperature rise of the cell is minimized such that in a first step the battery is discharged to a voltage U_B slightly higher than a first reference voltage (U_o) whereafter in a first recharging step the supplied charging current I_B is controlled progressively increasing according to the function I_B =k(U_B -U_o) where k is an adjusted constant, until the pole voltage has reached a second reference voltage U_B -u where u is maximum batter voltage and in a second charging step the charging current I_B is controlled through voltage feedback such that U_B ≈u whereby the amount of the supplied charging current is determine by the charging state of the battery cells. The first and second charging step can also be repeated with a fixed time interval with a free running time interval without charging current a number of cycles until a state of full charge is reached.

Claims

1. Method for high-rate charging of batteries with sealed cells, whereby through supplied charging current the efficiency the single battery cell is actively influenced such that the charging time and temperature rise of the cell is minimized characterized in that in a first step the battery is discharged to a voltage U_B slightly higher than a first reference voltage (U_O) whereafter in a first recharging step the supplied charging current I_B is controlled progressively increasing according to the function

View Dependent Claims (2, 3, 6)

2. Method according to claim 1 characterized in that in a second recharging step the charging current I_B is controlled through voltage feedback such that

3. Method according to claim 1 characterized in that supplied charge is measured and that the first and second recharging step is followed by a certain time interval disconnected without charging current (T_pause) contained in a charging cycle and carrying out a number of cycles until a state of full charge corresponding to a certain amount of charge (Q_max) is reached.

6. Method according to claim 2 wherein supplied charge is measured and the first and second recharging step is followed by a certain time interval disconnected without charging current (T_pause) contained in a charging cycle and carrying out a number of cycles until a state of full charge corresponding to a certain amount of charge (Q_max) is reached.

4. Apparatus for high-rate charging of batteries with sealed cells whereby through supplied charging current the efficiency of the signal battery cell is actively influenced such that the charging time and temperature rise of the cell is minimized, said apparatus comprising:

a control means in series with a DC current source,

said control means including

a control electrode,

a measuring conductor,

summing circuit, and

a control circuit connected to the control electrode whereby the control circuit comprises a control amplifier and voltage comparators which control circuit controls the charging current in response to signals from the summing circuits which form respectively first and second differential control voltages (U_B -U_o), (u-U_B) where U_o and u are reference voltages corresponding to an initial voltage and a final voltage and U_B the pole voltage of the battery supplied by way of the measuring conductor for pole voltage, one of said comparators giving a level shifted output and the other of said comparators giving a level shifted output at the voltage u for recharging.

5. Apparatus according to claim 4 wherein a control unit contains memory and time generating means which is response to the level shifted outputs of the comparators shifts between first and second recharging levels are effected.

7. In an apparatus for high-rate charging of a battery having a control means comprising an input, output and a control electrode, said input being connected in series with a DC current source and the output of the control means being connectable to a battery for supplying a charging current thereto, the improvement comprising:

a) a source of first voltage reference (U_o);

b) a source of second voltage reference (u);

c) a first summing circuit comprising first and second inputs and an output supplying a first differential control voltage (U_B -U^o) from the first voltage reference and the battery pole voltage;

d) a second summing circuit comprising first and second inputs and an output supplying a second differential control voltage (u-U_B) from the second voltage reference and the battery pole voltage;

e) switch means comprising first and second terminals, an output terminal and a control means, said first and second terminals being connected to respective outputs of said first and second summing circuits;

f) a control circuit containing

g) an amplifier connected to the control electrode of the control means to control the charging current, an input of said amplifier being connected to the output terminal of said switch means;

h) a first voltage comparator having a first input, a second input and an output, said first input of the first voltage comparator being connected to the first reference voltage;

i) a second voltage comparator having a first input, a second input and an output, said first input of the second voltage comparator being connected to the second reference voltage;

j) a battery pole voltage sense line connected to the second inputs of each of said voltage comparators for measuring the battery pole voltage;

k) a control unit comprising first and second inputs and first and second outputs, the control unit including memory and timing circuits to control and measure the energy supplied to the battery, said first input of said control unit receiving the output signal of the first comparator, which signal terminates the first step of a recharging cycle and activates the first output connected to the control means of the switch means, the control means thereby shifting the switch to connect the input of the amplifier to the output of the second summing circuit to complete a recharging cycle in a second step; and

l) discharging means controlled by the control unit to obtain a correct initial reference level for charging, the reference level being referred to as approximately zero charge.