Battery pack and driving method thereof

A battery pack includes: a battery to be charged; a first terminal part including a positive terminal coupled to a positive pole of the battery and a negative terminal coupled to a negative pole of the battery; a charge control switch and a discharge control switch between the positive pole and the positive terminal of the battery; and a protector to measure a voltage of the first terminal part, to control the charge control switch and the discharge control switch to operate normally when the voltage of the first terminal part is greater than or equal to a voltage of a reference power, and to control the charge control switch and the discharge control switch to be turned off when the voltage of the first terminal part is less than the voltage of the reference power.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2015-0023429, filed on Feb. 16, 2015, in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference in its entirety.

BACKGROUND

One or more aspects of example embodiments relate to a battery pack and a driving method thereof.

2. Description of the Related Art

Due to problems of environment destruction, resource exhaustion, and the like, there is an increasing demand for a system capable of efficiently using stored power. Also, there is an increasing demand for new renewable energy that does not cause pollution or causes only little pollution during power generation. An energy storage system is a system that connects new renewable energy, a battery system for storing power, and an existing grid to each other. Much research has been conducted to conform to environmental changes.

One of the important factors for such energy storage system may be efficient management of the battery system including charging, discharging, cell balancing, and the like. A battery may be used for a long time by effectively managing the battery, and power may be provided to a load in a stable manner.

A battery, with switches that control charging and discharging thereof, may be typically provided in the form of a battery pack. Various proposals are being made to efficiently and safely charge and discharge batteries.

SUMMARY

According to an embodiment, a battery pack includes: a chargeable battery; a first terminal part including a positive terminal coupled to a positive pole of the battery and a negative terminal coupled to a negative pole of the battery; a charge control switch and a discharge control switch between the positive pole and the positive terminal of the battery; and a protector configured to measure a voltage of the first terminal part, to control the charge control switch and the discharge control switch to operate normally when the voltage of the first terminal part is greater than or equal to a voltage of a reference power, and to control the charge control switch and the discharge control switch to be turned off when the voltage of the first terminal part is less than the voltage of the reference power.

The protector may be configured to compare a voltage of the positive terminal with the voltage of the reference power.

The battery pack may further include: a charge controller configured to turn on and turn off the charge control switch; a discharge controller configured to turn on and turn off the discharge control switch; and a battery management system configured to control the charge controller and the discharge controller.

The protector may include a comparator configured to compare a voltage of the positive terminal with the voltage of the reference power, and the battery management system may be configured to control the charge controller and the discharge controller in response to a comparison result of the comparator.

The protector may include: a comparator configured to compare a voltage of the positive terminal with the voltage of the reference power, and to generate a control signal when the voltage of the positive terminal is greater than or equal to the voltage of the reference power; and a plurality of controllers coupled to the charge controller and the discharge controller, respectively, the plurality of controllers being configured to couple the charge controller and the discharge controller to the battery management system when the control signal is supplied, and to electrically disconnect the charge controller and the discharge controller from the battery management system when the control signal is not supplied.

The protector may include: a comparator configured to compare a voltage of the positive terminal and the voltage of the reference power, and to generate a control signal when the voltage of the positive terminal is greater than or equal to the voltage of the reference power; and a plurality of controllers coupled to the charge control switch and the discharge control switch, respectively, and configured to couple the charge control switch to the charge controller and the discharge control switch to the discharge controller when the control signal is supplied.

The battery pack may further include: a pre-charger coupled in parallel to the charge control switch and the discharge control switch, and configured to supply current to the first terminal part.

The pre-charger may include: pre-charge switches configured to be turned on when current is supplied to the first terminal part; and a first resistor coupled between the pre-charge switches and the positive terminal.

The first terminal part may be coupled to a second terminal part at an exterior, and the second terminal part may include: a first terminal coupled to the positive terminal; a second terminal coupled to the negative terminal; and a first capacitor coupled between the first terminal and the second terminal.

The pre-charger may be configured to pre-charge the first capacitor to a voltage greater than or equal to the voltage of the reference power.

The voltage of the reference power may be set to a voltage that may be greater than or equal to i/2 when a maximum voltage capacity of the first capacitor is equal to i (where i is a natural number).

According to another embodiment, a method for driving a battery pack including: a first terminal part including a positive terminal coupled to a positive pole and a negative terminal coupled to a negative pole; and a charge control switch and a discharge control switch between the positive pole of the battery and the positive terminal, the method includes: detecting a voltage of the first terminal part; and maintaining the charge control switch and the discharge control switch in a turn off state when the voltage of the first terminal part is lower than a voltage of a reference power.

The detecting of the voltage of the first terminal part may include comparing a voltage applied to the positive terminal with the voltage of the reference power.

DETAILED DESCRIPTION

FIG. 1illustrates an energy storage system according to an embodiment.

Referring toFIG. 1, an energy storage system1according to an embodiment may supply power to a load4by linking with a power generating system2and a grid3.

The power generating system2may be a system that generates power using an energy source. The power generating system2may supply the generated power to the energy storage system1. The power generating system2may include a solar power generating system, a wind power generating system, a tidal power generating system, etc. However, the power generating system2is not limited to the above. For example, the power generating system2may include any suitable power generators using new, renewable energy to generate power, such as solar heat, geothermal heat, etc. For example, a solar cell that generates electrical energy using sunlight may be easy to install at family homes, factories, etc., and may be suitable for the energy storage system1dispersed throughout the homes or factories.

A grid3may include a power plant, a substation, a power line, and/or the like. The grid3, in its normal state, may supply power to the energy storage system1that may be supplied to a load4and/or a battery system20, and the energy storage system1may supply power to the grid3. When the grid3is in its abnormal state, power supply from the grid3to the energy storage system1is stopped, and power supply from the energy storage system1to the grid3is also stopped.

The load4may consume power generated from the power generating system2, power stored in the battery system20, and/or power supplied from the grid3. A family home, a factory, or the like may be an example of the load4.

The energy storage system1may store power generated by the power generating system2in the battery pack20, and/or may supply the generated power to the grid3. Also, the energy storage system1may supply the power stored in the battery pack20to the grid3, and/or store the power supplied from the grid3in the battery pack20. The energy storage system1may include a power conversion system (PCS)10to control power conversion, the battery pack20, a first switch30, and a second switch40.

The PCS10may properly convert and supply power of the power generating system2, the grid3, and the battery pack20to where it is needed. For example, the PCS10may include a power converting unit (e.g., a power converter)11, a direct current (DC) link unit (or a DC link)12, an inverter13, a converter14, and an integrated controlling unit (e.g., an integrated controller)15.

The power converting unit11may include a power converting device located between the power generating system2and the DC link unit12. The power converting unit11may transfer power generated from the power generating system2to the DC link unit12, and may convert an output voltage into a DC link voltage.

The power converting unit11may be configured as a converter, a rectifier circuit, etc., depending on a type (kind) of the power generating system2. When the power generated by the power generating system2includes a DC, the power converting unit11may be configured as a converter for converting a DC into a DC. When the generated power includes an alternating current (AC), the power converting unit11may be configured as a current circuit for converting an AC into a DC. In the case that the power generating system2is a solar power generating system, the power converting unit11may include a maximum power point tracking (MPPT) converter for performing MPPT control so as to maximally obtain power generated by the power generating system2according to a change in solar radiation intensity, temperature, etc.

The DC link unit12may be coupled between the power converting unit11and the inverter13, and may maintain or substantially maintain the DC link voltage steadily. The DC link unit12may include, for example, a high-capacity capacitor, etc.

The inverter13may include a power converting device coupled between the DC link unit12and the first switch30. In a discharge mode, the inverter13may convert a DC link voltage output from the power generating system2and/or the battery pack20into an AC voltage and may output the AC voltage. Also, in a charge mode, the inverter13may convert an AC voltage from the grid3into a DC link voltage and may output the DC link voltage. The inverter13may include a filter for removing high frequencies from the AC voltage, a phase locked loop (PLL) for phase synchronizing, etc.

The converter14may include a power converting device coupled between the DC link unit12and the battery pack20. In a discharge mode, the converter14may DC-DC convert power stored in the battery pack20into the DC link voltage used by the inverter13and may output the DC link voltage. In a charge mode, the converter14may DC-DC convert voltage of the power output from the power converting unit11and/or the inverter13into a voltage that may be stored in the battery pack20(that is, a charge voltage) and may output the voltage.

The integrated controlling unit15may monitor the power generating system2, the grid3, the battery pack20, the load4, etc., and may control operations of the power converting unit11, the DC link unit12, the inverter13, the converter14, the battery pack20, the first switch30, and the second switch40based on monitoring results and pre-configured algorithms, etc.

The first switch30and the second switch40may be coupled in series between the inverter13and the grid3, and may perform ON/OFF operations according to control of the integrated controlling unit15. The first switch30and the second switch40may control flow of a current between the power generating system2and the grid3. ON/OFF states of the first switch30and the second switch40may be determined according to the operating status of the power generating system2, the grid3, and the battery system20.

When power of the power generating system2and/or the battery pack20is supplied to the load4, or when power of the grid3is supplied to the battery pack20, the first switch30may be ON. When the power of the power generating system2and/or the battery pack20is supplied to the grid3, or when the power of the grid3is supplied to the load4and/or the battery pack20, the second switch40is ON. The first switch30and the second switch40may include a switching device, such as a relay, etc., which may be configured to withstand a large current.

The battery pack20may receive and store the power of the power generating system2and/or the grid3, and may supply the stored power to the load4or the grid3.

FIG. 2illustrates a battery pack according to a first embodiment.

Referring toFIG. 2, the battery pack according to the first embodiment may include a battery100, a charge control switch120, a discharge control switch130, a charge controller140, a discharge controller150, a battery management system (BMS)160, a protective unit (e.g., a protector)170, and a first terminal part200.

The battery100may supply stored power to a PCS10via the first terminal part200. Also, the battery100may be charged by a current (e.g., an external current) supplied from the PCS10via the first terminal part200. The battery100may include at least one battery cell111. The battery cell111may be a secondary battery that is capable of being charged, such as a nickel-cadmium battery, a lead storage battery, a nickel metal hydride battery, a lithium ion battery, a lithium polymer battery, and/or the like.

A charge control switch120and a discharge control switch130may control flow of a charge current and a discharge current, respectively. The charge control switch120may control the flow of the charge current, and the discharge control switch130may control the flow of the discharge current.

The charge control switch120may include a first field effect transistor FET1and a first parasitic diode D1. The first field effect transistor FET1may limit current flow from a first terminal part200to the battery100in response to control of the charge controller140. The charge controller140may control the flow of the charge current by controlling the turning ON and turning OFF of the first field effect transistor FET1. The first parasitic diode D1may be coupled to the first field effect transistor FET1to cause the discharge current to flow from the battery100to the first terminal part200.

The discharge control switch130may include a second field effect transistor FET2and a second parasitic diode D2. The second field effect transistor FET2may limit the current flow from the battery100to the first terminal part200in response to the control of the discharge controller150. The discharge controller150may control the flow of the discharge current by controlling the turning ON and turning OFF of the second field effect transistor FET2. The second parasitic diode D2may be coupled to the second field effect transistor FET2to cause the charge current to flow from the first terminal part200to the battery100.

The charge controller140may control the turning ON and turning OFF of the charge control switch120in response to control of the BMS160. The charge controller140may turn ON the charge control switch120at the time of charging the battery100.

The discharge controller150may control the turning ON and turning OFF of the discharge control switch130in response to the control of the BMS160. The discharge controller150may turn ON the discharge control switch130at the time of discharging the battery100.

The BMS160may perform balancing of the battery cell(s)111and the like. The BMS160may control the turning ON and turning OFF of the charge control switch120and the discharge control switch130by controlling the charge controller140and the discharge controller150, respectively. The BMS160may control the charge control switch120and the discharge control switch130to operate in a normal state when a control signal CS is input from a protective unit (e.g., a protector)170, and may control the charge control switch120and the discharge control switch130to be turned OFF when the control signal CS is not input.

The first terminal part200may couple the battery pack to an external device. For example, but without limitation thereto, the first terminal part200may be electrically coupled to a second terminal part210. The second terminal part210may be configured as a terminal part of the converter14, for example. The first terminal part200may be electrically coupled to the PCS10via the second terminal part210.

The first terminal part200may include a positive terminal202and a negative terminal204. The positive terminal202may be coupled to a positive pole of the battery100via the charge control switch120and the discharge control switch130. The negative terminal204may be coupled to a negative pole of the battery100.

The second terminal part210coupled to the first terminal part200may include a first terminal212coupled to the positive terminal202of the first terminal part200, and a second terminal214coupled to the negative terminal204. The second terminal part210may include a first capacitor C1coupled between the first terminal212and the second terminal214. The first capacitor C1may charge a voltage (e.g., a predetermined voltage) due to the power that is supplied from the battery pack and/or the PCS.

The protective unit170may compare the voltage applied to the first terminal part200and a voltage of reference power Vref, and may generate the control signal CS in response to the result of the comparison.

The protective unit170may compare a voltage applied to the positive terminal202(i.e., a voltage between the positive terminal202and the negative terminal204) and the voltage of the reference power Vref. When the voltage of the positive terminal202is greater than or equal to the voltage of the reference power Vref, the protective unit170may generate the control signal CS. Otherwise, the protective unit170may not generate the control signal CS. Here, the control signal CS being generated may refer to a certain voltage, for example, a high voltage being output from the protective unit170. Also, the control signal CS not being generated may refer to a voltage having a voltage level different from (e.g., opposite to) the certain voltage, for example, a low voltage being output from the protective unit170.

The BMS160may set the charge control switch120and the discharge control switch130to a turn OFF state by controlling the charge controller140and the discharge controller150, respectively, when the control signal CS is not input from the protective unit170. The BMS160may control the charge controller140and the discharge controller150, such that the charge control switch120and/or the discharge control switch130may operate in a normal state when the control signal CS is input from the protective unit170.

When the voltage of the positive terminal202is set to a voltage of the reference power Vref or greater, the charge control switch120and the discharge control switch130may be normally controlled. Otherwise, the charge control switch120and the discharge control switch130may be set to a turn OFF state.

When the first terminal part200and the second terminal part210are coupled to each other, the voltage that is stored in the first capacitor C1may be supplied to the positive terminal202. When a high voltage (for example, a voltage of the reference power Vref or greater) is charged in the first capacitor C1, the amount of current does not rapidly (e.g., instantaneously) increase, even though the charge control switch120or the discharge control switch130may be turned ON.

However, if a low voltage (for example, a voltage that is less than the reference power Vref) is charged in the first capacitor C1, the amount of the current rapidly increases in response to the turning ON of the charge control switch120or the discharge control switch130, and accordingly, the charge control switch120or the discharge control switch130may be damaged. Consequently, the voltage of the first terminal part200may be measured using the protective unit170, and operations of the charge control switch120and the discharge control switch130may be controlled in response to the measurement result, thereby securing stability.

The voltage of the reference power Vref may be set to a voltage that is equal to or greater than i/2 when the maximum voltage that can be charged in the first capacitor C1is set to i (where i is a natural number). For example, if the maximum voltage that can be charged in the first capacitor C1is set to 48V, the voltage of the reference power Vref may be set to a voltage that is 24V or greater, for example, 26V.

FIG. 3illustrates an embodiment of the protective unit shown inFIG. 2.

Referring toFIG. 3, a protective unit (e.g., a protector)170according to an embodiment may include a comparator172. The comparator172may compare a voltage of a positive terminal202and a voltage of reference power Vref. When the voltage of the positive terminal202is set to the voltage of the reference power Vref or greater, a control signal CS may be generated. Otherwise, the control signal CS may not be generated.

FIG. 4illustrates a battery pack according to a second embodiment. With reference toFIG. 4, the same or substantially the same elements or components as shown inFIG. 2have the same reference numerals, and the corresponding detailed description may be omitted.

Referring toFIG. 4, the battery pack according to the second embodiment may measure a voltage of a first terminal part200, and may include a protective unit (e.g., a protector)170′ for selectively coupling a charge controller140and a discharge controller150to a BMS160in response to the measured voltage.

The protective unit170′ may compare a voltage of a positive terminal202and a voltage of reference power Vref, and when the voltage of the reference power Vref is greater than the voltage of the positive terminal202, the charge controller140and the discharge controller150may be electrically disconnected (e.g., electrically isolated) from the BMS160. The protective unit170′ may compare the voltage of the positive terminal202and the voltage of the reference power Vref, and when the voltage of the positive terminal202is set to the reference power Vref or greater, the charge controller140and the discharge controller150may be electrically coupled to the BMS160.

When the BMS160and the charge controller140and/or the discharge controller150are electrically coupled to each other, the charge controller140and the discharge controller150may operate in a normal state in response to a signal of the BMS160, and accordingly, a charge control switch120and a discharge control switch130may be turned ON or turned OFF in response to control of the charge controller140and the discharge controller150, respectively.

FIG. 5illustrates an embodiment of the protective unit shown inFIG. 4.

Referring toFIG. 5, a protective unit (e.g., a protector)170′ according to an embodiment may include a comparator174and controlling units (e.g., controllers)176.

The comparator174may compare a voltage of a positive terminal202and a voltage of reference power Vref. When the voltage of the positive terminal202is set to the voltage of the reference power Vref or greater, the comparator174may output a high voltage (that is, a control signal CS), or otherwise may output a low voltage.

The controllers176may be coupled to a charge controller140and a discharge controller150, respectively. The controllers176may couple a BMS160to the charge controller140and the discharge controller150, when the control signal CS is supplied from the comparator174. The controllers176may electrically disconnect (e.g., electrically isolate) the BMS160from the charge controller140and the discharge controller150, when the control signal CS is not supplied from the comparator174. Each of the controllers176may be configured as a switching device or a logic gate, such as an AND gate.

FIG. 6illustrates a battery pack according to a third embodiment. With reference toFIG. 6, the same or substantially the same components or elements as shown inFIG. 2have the same reference numerals, and the corresponding detailed description may be omitted.

Referring toFIG. 6, the battery pack according to a third embodiment may include a protective unit (e.g., a protector)170″ to measure a voltage of a first terminal part200, and to selectively couple a charge controller140to a charge control switch120and a discharge controller150to a discharge control switch130in response to the measured voltage. The protective unit170″ may compare the voltage of the positive terminal202and the voltage of the reference power Vref, and may electrically disconnect (e.g., electrically isolate) the charge controller140and the discharge controller150from the charge control switch120and the discharge control switch130, respectively, when the voltage of the reference power Vref is higher than the voltage of the positive terminal202. The protective unit170″ may electrically couple the charge controller140to the charge control switch120and the discharge controller150to the discharge control switch130when the voltage of the positive terminal202is set to the voltage of the reference power Vref or greater.

When the charge control switch120is coupled to the charge controller140and the discharge control switch130is coupled to the discharge controller150, the charge control switch120and the discharge control switch130may operate in a normal state in response to control of the charge controller140and the discharge controller150.

FIG. 7illustrates an embodiment of the protective unit shown inFIG. 6.

Referring toFIG. 7, the protective unit170″ according to an embodiment may include a comparator175and controlling units (e.g., controllers)177.

The comparator175may compare a voltage of a positive terminal202and a voltage of a reference power Vref. The comparator175may output a high voltage (that is, a control signal CS) when the voltage of the positive terminal202is set to the voltage of the reference power Vref or greater, and otherwise, may output a low voltage.

The controllers177may be coupled to a charge control switch120and a discharge control switch130, respectively. The controllers177may couple the charge controller140and the discharge controller150to the charge control switch120and the discharge control switch130, respectively, when the control signal CS is supplied form the comparator175. The controllers177may electrically disconnect (e.g., electrically isolate) the charge controller140and the discharge controller150from the charge control switch120and the discharge control switch130, when the control signal CS is not supplied form the comparator175. Each of the controllers177may be configured as a switching device or a logic gate, such as an AND gate.

FIG. 8illustrates a battery pack according to a fourth embodiment. With reference toFIG. 8, the same or substantially the same components or elements as shown inFIG. 2have the same reference numerals, and the corresponding detailed description may be omitted.

Referring toFIG. 8, the battery pack according to the fourth embodiment may include a pre-charge unit (e.g., a pre-charger)180that is coupled in parallel to a charge control switch120and a discharge control switch130.

The pre-charge unit180may pre-charge a first capacitor C1using a voltage stored in a battery100. For example, when a first terminal part200and a second terminal part210are coupled to each other, the pre-charge unit180may supply a current (e.g., a predetermined current) to the first terminal part200in response to a voltage of the battery100. The first capacitor C1may be pre-charged in response to the current supplied from the first terminal part200.

When the first capacitor C1is pre-charged using the pre-charge unit180, the likelihood of damaging the charge control switch120and the discharge control switch130due to a sudden current may be reduced. In addition, the voltage of the first terminal part200may be detected using a protective unit (e.g., a protector)170, and operations of the charge control switch120and the discharge control switch130may be controlled in response to the detection results, thereby securing reliability.

The precharge unit180may include a switching unit (e.g., a switching circuit)190and a resistor R1that are coupled in series between the battery100and the positive terminal202.

The switching unit190may include a first pre-charge switch and a second pre-charge switch. The first pre-charge switch may include a third field effect transistor FET3and a third parasitic diode D3. The third field effect transistor FET3may be turned ON due to control of a BMS160. The third parasitic diode D3may be coupled to the third field effect transistor FET3to allow current to flow from the battery100to the positive terminal202.

The second pre-charge switch may include a fourth field effect transistor FET4and a fourth parasitic diode D4. The fourth field effect transistor FET4may be turned ON and/or turned OFF concurrently with the third field effect transistor FET3in response to the control of the BMS160. The fourth parasitic diode D4may be coupled to the fourth field effect transistor FET4to allow a current to flow from the positive terminal202to the battery100.

The resistor R1may be coupled between the switching unit190and the positive terminal202. The resistor R1may limit the flow of the current, thereby preventing or substantially preventing the first pre-charge switch and the second pre-charge switch from being damaged. The pre-charge unit180shown inFIG. 8may be applied to any ones of the battery packs according to the embodiments shown inFIGS. 4 and 6.