Charge equalization apparatus and method

Abstract

The present invention relates, in general, to a battery voltage equalization apparatus and method, and, more particularly, to a charge equalization apparatus and method, which decrease the withstand voltages of semiconductor switching elements while maintaining charge equalization performance, thus making it easy to implement the secondary windings of transformers while reducing the costs of the charge equalization apparatus. The charge equalization apparatus includes N first transformers (T 1 to Tn) connected in series with N series-connected batteries (B 1 to Bn) and adapted to decrease voltages of overcharged batteries among the N batteries. A charge storage device (Cdump) stores energy supplied from the first transformers. A second transformer (TS) redistributes energy stored in the charge storage device to the N series-connected batteries. A voltage detection and drive signal generation unit ( 20 ) detects voltages of N respective series-connected batteries, and generates a first drive signal and a second drive signal.

1 . A charge equalization apparatus, comprising:
 N first transformers connected in parallel to N series-connected batteries and adapted to decrease voltages of overcharged batteries among the N batteries;   a charge storage device for storing energy supplied from the first transformers;   a second transformer for redistributing energy stored in the charge storage device to the N series-connected batteries; and   a voltage detection and drive signal generation unit for detecting voltages of N respective series-connected batteries, and for generating a first drive signal, required to discharge energy from overcharged batteries, and a second drive signal, required to supply the energy stored in the charge storage device to the second transformer.   
     
     
         2 . The charge equalization apparatus according to  claim 1 , further comprising:
 N discharge switches connected in series with primary windings of the N first transformers, respectively, and operated in response to the first drive signal;   N first semiconductor switching elements connected between first ends of secondary windings of the N first transformers and an cathode of the charge storage device;   a redistribution switch connected between a second end of a primary winding of the second transfonner and a anode of the charge storage device, and operated in response to the second drive signal; and   a second semiconductor switching element connected between a first end of a secondary winding of the second transformer and an cathode of a first battery of the N series-connected batteries.   
     
     
         3 . The charge equalization apparatus according to  claim 1 , wherein, in each of the first transformers, a turns ratio of a primary winding to a secondary winding is N 1 :N 2 , N 2  being greater than N 1 . 
     
     
         4 . The charge equalization apparatus according to  claim 3 , wherein, in the second transformer, a turns ratio of the primary winding to the secondary winding is N 2 :N 3 , N 3  being greater than N 2 . 
     
     
         5 . The charge equalization apparatus according to  claim 4 , wherein the second transformer has a capacity larger than that of the first transformers. 
     
     
         6 . The charge equalization apparatus according to  claim 1 , wherein the second end of the secondary windings of the N first transformers are connected in common to the anode of the charge storage device. 
     
     
         7 . The charge equalization apparatus according to  claim 1 , wherein each of the first transformers and the second transformer is implemented such that a dot formed on a primary winding and a dot formed on a secondary winding are located at different sides. 
     
     
         8 . The charge equalization apparatus according to  claim 1 , wherein each of the first transformers and the second transformer is implemented such that a dot formed on a primary winding and a dot formed on a secondary winding are located at a same side. 
     
     
         9 . The charge equalization apparatus according to  claim 1 , wherein the charge storage device has a capacity proportional to a number of overcharged batteries. 
     
     
         10 . The charge equalization apparatus according to  claim 9 , wherein the charge storage device is a capacitor. 
     
     
         11 . The charge equalization apparatus according to  claim 9 , wherein the charge storage device is a battery for vehicles. 
     
     
         12 . The charge equalization apparatus according to  claim 2 , wherein each of the first semiconductor switching elements and the second semiconductor switching element is formed of any one of a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), a Bipolar Junction Transistor (BJI), a relay, and a diode. 
     
     
         13 . The charge equalization apparatus according to  claim 12 , wherein each of the first semiconductor switching elements and the second semiconductor switching element is a diode. 
     
     
         14 . The charge equalization apparatus according to  claim 2 , wherein each of the discharge switches and the redistribution switch is formed of anyone of a MOSFET, a BJT, and a relay. 
     
     
         15 . The charge equalization apparatus according to  claim 14 , wherein each of the discharge switches and the redistribution switch is an N-type MOSFET. 
     
     
         16 . The charge equalization apparatus according to  claim 1 , wherein the voltage detection and drive signal generation unit comprises:
 a sensing unit for detecting voltages of the N batteries;   a microprocessor for determining ON/OFF time of the discharge switches and the redistribution switch on a basis of the voltages detected by the sensing unit; and   a switch driving circuit unit for generating a first drive signal and a second drive signal, required to drive the discharge switches and the redistribution switch in response to a signal input from the microprocessor.   
     
     
         17 . A charge equalization apparatus, comprising:
 N transformers connected in parallel to N series-connected batteries, respectively, and adapted to decrease voltages of overcharged batteries among the N series-connected batteries;   a charge storage device for storing energy supplied from the transformers;   a voltage detection and drive signal generation unit for detecting voltages of N respective series-connected batteries and generating a drive signal required to discharge energy from overcharged batteries;   N discharge switches connected between primary windings of the N transformers and anodes of the N batteries, and operated in response to the drive signal; and   N semiconductor switching elements respectively connected between first ends of the secondary windings of the N transformers and an cathode of the charge storage device.   
     
     
         18 . The charge equalization apparatus according to  claim 17 , wherein the secondary windings of the N transformers have second end connected to a anode of the charge storage device. 
     
     
         19 . The charge equalization apparatus according to  claim 17 , wherein each of the transformers is implemented such that a dot formed on a primary winding and a dot formed on a secondary winding are located at different sides. 
     
     
         20 . The charge equalization apparatus according to  claim 17 , wherein each of the transformers is implemented such that a dot formed on a primary winding and a dot formed on a secondary winding are located at a same side. 
     
     
         21 . The charge equalization apparatus according to  claim 17 , wherein the charge storage device is a battery for vehicles. 
     
     
         22 . The charge equalization apparatus according to  claim 17 , wherein the charge storage device is a capacitor. 
     
     
         23 . The charge equalization apparatus according to  claim 17 , wherein each of the discharge switches is formed of a MOSFET, a BJT, and a relay. 
     
     
         24 . The charge equalization apparatus according to  claim 23 , wherein each of the discharge switches is an N-type MOSFET. 
     
     
         25 . The charge equalization apparatus according to  claim 17 , wherein each of the semiconductor switching elements is formed of anyone of a MOSFET, a BJT, a relay, and a diode. 
     
     
         26 . The charge equalization apparatus according to  claim 25 , wherein each of the semiconductor switching elements is a diode. 
     
     
         27 . A charge equalization method, comprising the steps of:
 (a) detecting voltages of N series-connected batteries;   (b) comparing the detected voltages with a first reference voltage, discharging energy from overcharged batteries, which are charged to voltages greater than the first reference voltage, and storing the energy supplied from the overcharged batteries in a charge storage device; and   (c) detecting voltage of the charge storage device, comparing the detected voltage with a second reference voltage, and redistributing the detected voltage to the N series-connected batteries when the detected voltage is equal to the second reference voltage, thus recharging energy drawn from the overcharged batteries in the N series-connected batteries.   
     
     
         28 . The charge equalization method according to  claim 27 , wherein the step (b) comprises discharging energy from the overcharged batteries, and storing the energy supplied from the overcharged batteries in a capacitor. 
     
     
         29 . The charge equalization method according to  claim 27 , wherein the step (b) comprises discharging energy from the overcharged batteries, and storing the energy supplied from the overcharged batteries in a battery for vehicles. 
     
     
         30 . A charge equalization method, comprising the steps of:
 (a) detecting voltages of N respective series-connected batteries;   (b) comparing the detected voltages with a reference voltage, and discharging energy from overcharged batteries, which are charged to voltages greater than the reference voltage and   (c) storing the energy supplied from the overcharged batteries in a charge storage device.   
     
     
         31 . The charge equalization method according to  claim 30 , wherein the reference voltage is a mean voltage of the voltages of the N series-connected batteries. 
     
     
         32 . The charge equalization method according to  claim 30 , wherein the reference voltage is a voltage of a battery having a lowest voltage among the N series-connected batteries.