Battery stack balancing apparatus
Disclosed is a balancing apparatus capable of performing balancing without wasting power and of rapidly transmitting power. A battery stack balancing apparatus for balancing a battery stack including a plurality of battery modules connected to each other in series includes a series resonant circuit including a first capacitor and a first inductor connected to the first capacitor in series, a polarity change circuit including a second inductor and a polarity change switch connected to the second inductor in series so as to be selectively turned on or off, and connected to the first capacitor in parallel, a plurality of transmission lines having ends, respectively, electrically connected to a plurality of nodes provided at a low-potential end of the battery stack, at a high-potential end of the battery stack, and between the plurality of battery modules connected to each other in series, and other ends connected to the series resonant circuit, a plurality of transmission switches provided on the plurality of transmission lines so as to be selectively turned on or off, and a control unit configured to control the plurality of transmission switches and the polarity change switch.
1. A battery stack balancing apparatus for balancing a battery stack comprising a plurality of battery modules connected to each other in series, the apparatus comprising:
a series resonant circuit comprising a first capacitor and a first inductor connected to the first capacitor in series;
a polarity change circuit comprising a second inductor and a polarity change switch connected to the second inductor in series so as to be selectively turned on or off, wherein an entirety of the polarity change circuit is connected to the first capacitor in parallel;
a plurality of transmission lines, each transmission line having a first end electrically connected to one of a plurality of nodes, including a first transmission line electrically connected to a first node at a low-potential end of the battery stack, a second transmission line electrically connected to a second node at a high-potential end of the battery stack, and at least a third transmission line electrically connected between the plurality of battery modules connected to each other in series, and each transmission line having a second end connected to the series resonant circuit;
a plurality of transmission switches, including a first transmission switch provided on the first transmission line, a second transmission switch provided on the second transmission line, and a third transmission switch provided on the third transmission line, wherein each transmission switch is configured to be selectively turned on or off; and
a control unit configured to:
control the plurality of transmission switches and the polarity change switch, and
control the polarity change circuit and each of the transmission switches to perform cell balancing of the plurality of battery modules.
2. The battery stack balancing apparatus of claim 1 , further comprising a fourth transmission line directly electrically connected between the plurality of battery modules connected to each other in series and a fourth transmission switch provided on the fourth transmission line.
3. The battery stack balancing apparatus of claim 2 , wherein the control unit is configured to selectively control each transmission switch to perform zero current switching or zero voltage switching in accordance with a half period of a resonance period of the series resonant circuit by opening the first and third transmission switches and closing the second and fourth transmission switches.
4. The battery stack balancing apparatus of claim 2 , wherein the control unit controls the polarity change switch in such a manner that zero current switching or zero voltage switching is performed in accordance with a half period of a resonance period of a parallel resonant circuit formed by the first capacitor and the second inductor by turning on the polarity change switch and turning off the first, second, third and fourth transmission switches.
5. The battery stack balancing apparatus of claim 1 , wherein the control unit is configured to control the polarity change switch and the plurality of transmission switches by comparing a polarity of a voltage of at least one battery module among the plurality of battery modules for supplying power to the series resonant circuit, to a polarity of a voltage charged in the first capacitor.
6. The battery stack balancing apparatus of claim 5 , wherein the control unit is configured to control the polarity change switch to be turned on and control all of the plurality of transmission switches to be turned off, when the polarity of the voltage of the at least one battery module for supplying power to the series resonant circuit equals the polarity of the voltage charged in the first capacitor.
7. The battery stack balancing apparatus of claim 2 , wherein the control unit is configured to control the polarity change switch and the plurality of transmission switches by comparing a polarity of a voltage of at least one battery module among the plurality of battery modules for receiving power supplied from the series resonant circuit, to a polarity of a voltage charged in the first capacitor.
8. The battery stack balancing apparatus of claim 7 , wherein the control unit is configured to control the polarity change switch to be turned off, control the first and third transmission switches connected to two ends of the at least one battery module for receiving power supplied from the series resonant circuit, to be turned on, and control the second and fourth transmission switches to be turned off, when the polarity of the voltage of the at least one battery module for receiving power supplied from the series resonant circuit equals the polarity of the voltage charged in the first capacitor.
9. The battery stack balancing apparatus of claim 7 , wherein the control unit is configured to control the polarity change switch to be turned on and control all of the transmission switches to be turned off, when the polarity of the voltage of the at least one battery module for receiving power supplied from the series resonant circuit differs from the polarity of the voltage charged in the first capacitor.
10. The battery stack balancing apparatus of claim 1 , wherein each of the battery modules is a unit battery cell or an assembly of two or more battery cells.
11. A battery pack comprising the battery stack balancing apparatus of claim 1 .
12. An electric vehicle comprising the battery stack balancing apparatus of claim 1 .
13. The battery stack balancing apparatus of claim 1 , wherein the second end of the first transmission line is directly connected to the first inductor.
14. The battery stack balancing apparatus of claim 13 , wherein the second end of the second transmission line is directly connected to the first capacitor.
15. The battery stack balancing apparatus of claim 14 , wherein the second end of the third transmission line is directly connected to one of the first inductor and the first capacitor.
16. The battery stack balancing apparatus of claim 2 , wherein the second end of the first transmission line is directly connected to the first inductor.
17. The battery stack balancing apparatus of claim 16 , wherein the second end of the second transmission line is directly connected to the first capacitor.
18. The battery stack balancing apparatus of claim 17 , wherein the second end of the third transmission line is directly connected to the first inductor, and
wherein the second end of the fourth transmission line is directly connected to the first capacitor.
19. The battery stack balancing apparatus of claim 1 , further comprising a consumption circuit connected to the first capacitor in parallel,
wherein the consumption circuit includes a consumption resistor and a consumption switch connected in series, and
wherein the controller is further configured to control the consumption switch.