Patent Description:
Batteries are rapidly popularized not only in mobile devices (e.g., mobile phones, laptop computers, smartphones, and smartpads) but also in electricity-driven vehicles (e.g., electric vehicles (EVs), hybrid electric vehicles (HEV), and plug-in hybrid electric vehicles (PHEVs)), high-capacity energy storage systems (ESSs), etc..

A battery is connected to an external power line through a switch element. The switch element is turned on or off by a control signal.

When the switch element is turned on, charge or discharge of the battery is enabled in association with the power line. Otherwise, when the switch element is turned off, a system connection with the power line is cut and thus the charge or discharge is interrupted.

When the switch element has a failure, the external connection of the battery may not be appropriately controlled. The failure of the switch element is divided into a short circuit failure and an open circuit failure.

The short circuit failure refers to a failure in which the switch element is constantly maintained in a turn-on state irrespective of the control signal. On the other hand, the open circuit failure refers to a failure in which the switch element is constantly maintained in a turn-off state irrespective of the control signal.

Among the above-described failures of the switch element, the short circuit failure is more serious. The short circuit failure results from various causes. For example, in a mechanical switch element such as a relay, a short circuit failure may occur when contact points are fused thereby to be in contact with each other. As another example, in a semiconductor switch such as a solid state relay (SSR), a short circuit failure may occur when insulation is permanently broken because characteristics of a semiconductor material deteriorate and thus a threshold voltage is excessively lowered.

The short circuit failure causes overcharge or overdischarge of the battery. The overcharge and overdischarge not only deteriorate performance of the battery but also cause overheating and, in a worse case, explosion of the battery.

Therefore, a technology of detecting a short circuit failure of a switch element and appropriately solving the short circuit failure is required.

The short circuit failure of the switch element may be easily diagnosed by measuring a voltage of two terminal ends of the switch element. That is, although a turn-off control signal is applied to the switch element, if the voltage between the two terminal ends of the switch element is close to zero, it may be diagnosed that the switch element has a short circuit failure.

The fact that the voltage between the two terminal ends of the switch element is close to zero means that the switch element does not respond to the turn-off control signal and is constantly maintained in a turn-on state.

The above-described failure diagnosis method may have a simple algorithm but may not be applied to a case when a battery is connected to direct current (DC) parallel link nodes and a voltage of the DC parallel link nodes is substantially the same as a voltage of the battery.

An example of the DC parallel link nodes includes parallel connection nodes between two batteries of different types when the two batteries are connected in parallel.

When the battery is connected through the switch element to the DC parallel link nodes, although the switch element is normally turned off, the voltage of the DC parallel link nodes is applied to an outer node of the switch element and the voltage of the battery is applied to an inner node of the switch element. However, since little or no difference is present between the voltage of the DC parallel link nodes and the voltage of the battery, a voltage difference between the two terminal ends of the switch element substantially has a value close to zero. Consequently, even when the switch element does not have a short circuit failure, it may be incorrectly diagnosed that a short circuit failure has occurred.

The present disclosure is designed to solve the problems of the related art, and therefore the present disclosure is directed to providing an apparatus and method capable of easily diagnosing a failure of a switch element used for external connection of a battery.

The present disclosure is also directed to providing an apparatus and method capable of reliably diagnosing a failure of a switch element when a battery is connected through the switch element to direct current (DC) parallel link nodes to which a voltage substantially equal to the voltage of the battery is applied.

The present invention is directed to a vehicle according to claim <NUM> and to a method according to claims <NUM> to <NUM>. Embodiments of the inventions are described in the dependent claims.

In particular, there is provided an apparatus for diagnosing a failure of a switch element provided on a first line between a first electrode of a battery and a first external terminal, the apparatus including a current measuring unit configured to measure a current flowing through a second line between a second electrode of the battery and a second external terminal, a diagnosis resistor and a diagnosis switch provided on a third line to connect an outer node of the switch element and an outer node of the current measuring unit, and connected to each other in series, and a controller configured to apply a control signal for turning on or off the switch element, to the switch element, to turn on the diagnosis switch after the control signal is applied and then receive a measured current value from the current measuring unit, to determine a level of the current flowing through the second line, by using the measured current value, and to diagnose a failure of the switch element by comparing the current level to a reference current level.

According to an aspect, the controller may be configured to apply a control signal for turning off the switch element, to the switch element, and to diagnose that the switch element has a short circuit failure, if the current level is greater than the reference current level.

According to another aspect, the controller may be configured to apply a control signal for turning on the switch element, to the switch element, and to diagnose that the switch element has an open circuit failure, if the current level is less than the reference current level.

The first and second lines are connected to direct current (DC) parallel link nodes to which a voltage equal to a voltage of the battery is applied.

The apparatus according to the present disclosure may further include a first voltage measuring unit configured to measure the voltage of the battery, and a second voltage measuring unit configured to measure the voltage of the DC parallel link nodes.

According to an aspect, the controller may be configured (i) to apply a control signal for turning off the switch element, to the switch element, (ii) to receive a first measured voltage value indicating the voltage of the battery and a second measured voltage value indicating the voltage of the DC parallel link nodes from the first and second voltage measuring units, respectively, and receive the measured current value of the second line from the current measuring unit, (iii) to diagnose that the switch element is normal, if a difference between the first and second measured voltage values is greater than a reference voltage level, and (iv) to diagnose that the switch element has a short circuit failure, if the difference between the first and second measured voltage values is less than the reference voltage level and if the level of the current flowing through the second line is greater than the reference current level.

According to another aspect, the controller may be configured (i) to apply a control signal for turning on the switch element, to the switch element, (ii) to receive a first measured voltage value indicating the voltage of the battery and a second measured voltage value indicating the voltage of the DC parallel link nodes from the first and second voltage measuring units, respectively, and receive the measured current value of the second line from the current measuring unit, (iii) to diagnose that the switch element has an open circuit failure, if a difference between the first and second measured voltage values is greater than a reference voltage level, and (iv) to diagnose that the switch element is normal, if the difference between the first and second measured voltage values is less than the reference voltage level and if the level of the current flowing through the second line is greater than the reference current level.

In the present disclosure, the reference current level used for reference to diagnose a short circuit failure of the switch element includes a plurality of current values having different magnitudes. In this case, the controller may be configured to diagnose that the switch element has a short circuit failure, if the level of the current flowing through the second line is greater than a maximum current value among the current values set as the reference current level.

In addition, the controller is configured to identify a current value corresponding to the level of the current flowing through the second line among the current values set as the reference current level, and to diagnose that the switch element has a pre-defined weak short circuit failure corresponding to the identified current value.

Preferably, the controller may be configured to identify a maximum current value among current values less than or equal to the level of the current flowing through the second line among the current values set as the reference current level, and to diagnose that the switch element has a pre-defined weak short circuit failure corresponding to the identified maximum current value. The weak short circuit failure may be pre-defined in a plurality of stages based on magnitudes of the current values set as the reference current level.

The apparatus according to another aspect of the present disclosure may further include a storage unit configured to store diagnosis information of the switch element, and the controller may be configured to store the diagnosis information of the switch element in the storage unit.

The apparatus according to still another aspect of the present disclosure may further include a display unit configured to display diagnosis information of the switch element, and the controller may be configured to visually output the diagnosis information of the switch element on the display unit.

The apparatus according to still another aspect of the present disclosure may further include a communication interface capable of transmitting or receiving communication data, and the controller may be configured to generate communication data including diagnosis information of the switch element, and to output the generated communication data through the communication interface to an external device.

In another aspect of the present disclosure, there is also provided a method of diagnosing a failure of a switch element provided on a first line between a first electrode of a battery and a first external terminal, the method including (a) providing a current measuring unit configured to measure a current flowing through a second line between a second electrode of the battery and a second external terminal, and a diagnosis resistor and a diagnosis switch provided on a third line to connect an outer node of the switch element and an outer node of the current measuring unit, and connected to each other in series, (b) applying a control signal for turning off the switch element, to the switch element, (c) turning on the diagnosis switch after the control signal is applied and then receiving a measured current value from the current measuring unit, and (d) determining a level of the current flowing through the second line, by using the measured current value, and diagnosing that the switch element has a short circuit failure, if the current level is greater than a pre-defined reference current level.

In another aspect of the present disclosure, there is also provided a method of diagnosing a failure of a switch element provided on a first line between a first electrode of a battery and a first external terminal, the method including (a) providing a current measuring unit configured to measure a magnitude of a current flowing through a second line between a second electrode of the battery and a second external terminal, and a diagnosis resistor and a diagnosis switch provided on a third line to connect an outer node of the switch element and an outer node of the current measuring unit, and connected to each other in series, (b) applying a control signal for turning on the switch element, to the switch element, (c) turning on the diagnosis switch after the control signal is applied and then receiving a measured current value from the current measuring unit, and (d) determining a level of the current flowing through the second line, by using the measured current value, and diagnosing that the switch element has an open circuit failure, if the current level is less than a pre-defined reference current level.

In another aspect of the present disclosure, there is also provided a method of diagnosing a failure of a switch element provided between a first external terminal connected to direct current (DC) parallel link nodes, and a first electrode of a battery, the method including (a) providing a current measuring unit configured to measure a magnitude of a current flowing through a second line between a second electrode of the battery and a second external terminal, first and second voltage measuring units configured to measure a voltage of the battery and a voltage of the DC parallel link nodes, respectively, and a diagnosis resistor and a diagnosis switch provided on a third line to connect an outer node of the switch element and an outer node of the current measuring unit, and connected to each other in series, (b) applying a control signal for turning off the switch element, to the switch element, (c) turning on the diagnosis switch after the control signal is applied, (d) receiving a first measured voltage value indicating the voltage of the battery and a second measured voltage value indicating the voltage of the DC parallel link nodes from the first and second voltage measuring units, respectively, (e) receiving a measured current value from the current measuring unit and determining a level of the current flowing through the second line, by using the measured current value, (f) diagnosing that the switch element has a short circuit failure, if a difference between the first and second measured voltage values is less than a pre-defined reference voltage level and if the level of the current flowing through the second line is greater than a reference current level, and (g) diagnosing that the switch element is normal, if the difference between the first and second measured voltage values is greater than the reference voltage level.

In another aspect of the present disclosure, there is also provided a method of diagnosing a failure of a switch element provided on a first line between a first external terminal connected to direct current (DC) parallel link nodes, and a first electrode of a battery, the method including (a) providing a current measuring unit configured to measure a magnitude of a current flowing through a second line between a second electrode of the battery and a second external terminal, first and second voltage measuring units configured to measure a voltage of the battery and a voltage of the DC parallel link nodes, respectively, and a diagnosis resistor and a diagnosis switch provided on a third line to connect an outer node of the switch element and an outer node of the current measuring unit, and connected to each other in series, (b) applying a control signal for turning on the switch element, to the switch element, (c) turning on the diagnosis switch after the control signal is applied, (d) receiving a first measured voltage value indicating the voltage of the battery and a second measured voltage value indicating the voltage of the DC parallel link nodes from the first and second voltage measuring units, respectively, (e) receiving a measured current value from the current measuring unit and determining a level of the current flowing through the second line, (f) diagnosing that the switch element has an open circuit failure, if a difference between the first and second measured voltage values is greater than a pre-defined reference voltage level, and (g) diagnosing that the switch element is normal, if the difference between the first and second measured voltage values is less than the pre-defined reference voltage level and if the level of the current flowing through the second line is greater than a pre-defined reference current level.

In the present disclosure, the reference current level used for reference to diagnose a short circuit failure of the switch element includes a plurality of current values having different magnitudes. In this case, the diagnosing that the switch element has a short circuit failure includes diagnosing that the switch element has a short circuit failure, if the level of the current flowing through the second line is greater than a maximum current value among the current values set as the reference current level.

In addition, the diagnosing that the switch element has a short circuit failure may include identifying a maximum current value among current values less than or equal to the level of the current flowing through the second line among the current values set as the reference current level, and diagnosing that the switch element has a pre-defined weak short circuit failure corresponding to the identified maximum current value. The weak short circuit failure may be pre-defined in a plurality of stages based on magnitudes of the current values set as the reference current level.

Optionally, the method according to the present disclosure may further include generating failure diagnosis information of the switch element, and storing, displaying, or transmitting the generated failure diagnosis information.

According to the present disclosure, a failure of a switch element used for external connection of a battery may be diagnosed using a simple hardware configuration irrespective of the level of a voltage applied to an external terminal of the battery.

Furthermore, according to the present disclosure, a sensor element used to measure a charge or discharge current of the battery may also be used to diagnose a failure of the switch element and thus costs of a diagnosis apparatus may be reduced.

In addition, according to the present disclosure, occurrence of a weak short circuit failure in the switch element may also be accurately diagnosed.

Moreover, the present disclosure may be useful for a parallel power system in which the external terminal of the battery is connected to another type of battery in parallel.

Therefore, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of the disclosure, so it should be understood that other equivalents and modifications could be made thereto without departing from the scope of the invention, which is defined by the appended claims.

<FIG> is a structural view of an apparatus <NUM> for diagnosing a failure of a switch element <NUM>, according to an embodiment of the present disclosure.

Referring to the drawing, the switch element failure diagnosis apparatus <NUM> according to the present disclosure may diagnose a failure of the switch element <NUM> used to connect or disconnect a first electrode <NUM> and a second electrode <NUM> of the battery <NUM> to or from a first power line P+ and a second power line P- at the outside thereof.

The battery <NUM> is not limited to a particular type and may be, for example, a lithium battery, a lithium polymer battery, a nickel-cadmium battery, a nickel-hydrogen battery, or a nickel-zinc battery.

The battery <NUM> is provided as a pack in which a plurality of battery cells are connected in series or in parallel. Alternatively, the battery <NUM> may include a plurality of the packs.

The first and second electrodes <NUM> and <NUM> of the battery <NUM> may be a positive electrode and a negative electrode, respectively.

The switch element <NUM> is not limited to a particular type and may be a relay switch in which contact points are open or closed by an electromagnet, as shown in the drawing.

It will be understood by those skilled in the art that the switch element <NUM> may be a semiconductor switch, e.g., a solid state relay (SSR) or a metal oxide silicon field effect transistor (MOSFET), other than the relay switch.

On and off states of the switch element <NUM> may be controlled by an external control signal. The control signal may be input from a controller <NUM> to be described below.

When the switch element <NUM> is turned on, the battery <NUM> is electrically coupled to the external first and second power lines P+ and P-. After the electrical coupling is achieved, the battery <NUM> may transmit discharge power to or receive charge power from outside. Otherwise, when the switch element <NUM> is turned off, the electrical coupling between the battery <NUM> and the first and second power lines P+ and P- is released and thus the transmission or reception of power to or from outside is stopped.

The failure of the switch element <NUM> is divided into a short circuit failure and an open circuit failure. The short circuit failure refers to a case when the switch element <NUM> is turned off but is internally constantly maintained in a turn-on state. Such failure occurs when contact points included in the switch element <NUM> are fused thereby to be in contact with each other due to heat. Meanwhile, the open circuit failure refers to a case when the switch element <NUM> is turned on but is internally constantly maintained in a turn-off state. Such failure occurs due to deterioration of an operating mechanism which causes mechanical, electrical, or magnetic contact between the contact points.

An end of the first power line P+ may be electrically connected to a first external terminal T+. The first external terminal T+ is electrically connected to the first electrode <NUM> of the battery <NUM> through the switch element <NUM> provided on a first line L<NUM>. Herein, the first line L<NUM> refers to a line extending from the first electrode <NUM> of the battery <NUM> to the first external terminal T+.

An end of the second power line P- may be electrically connected to a second external terminal T-. The second external terminal T- is electrically connected to the second electrode <NUM> of the battery <NUM> through a second line L<NUM>. Herein, the second line L<NUM> refers to a line extending from the second electrode <NUM> of the battery <NUM> to the second external terminal T-.

The first and second power lines P+ and P- may be used as a conductive path through which a discharge current output from the battery <NUM> flows or a conductive path through which a charge current input to the battery <NUM> flows.

In an embodiment, another end of the first power line P+ may be connected to a positive terminal of a direct current (DC) voltage source <NUM>, and another end of the second power line P- may be connected to a negative terminal of the DC voltage source <NUM>.

A node where the first external terminal T+ meets the first power line P+ and a node where the second external terminal T- meets the second power line P-serve as DC parallel link nodes NDC.

Therefore, the DC voltage source <NUM> is electrically connected to the first and second lines L<NUM> and L<NUM> through the DC parallel link nodes NDC. Then, the DC voltage source <NUM> and the battery <NUM> are in parallel connection to each other through the DC parallel link nodes NDC.

The DC voltage source <NUM> is not limited to a particular type and may be a different type of a battery from the battery <NUM>.

For example, the battery <NUM> may be a lithium battery having a nominal voltage of 12V. The DC voltage source <NUM> may be a lead storage battery having a nominal voltage of 12V.

In another embodiment, the DC voltage source <NUM> may be a high-capacity condenser. The high-capacity condenser may be included in an input side of a power conversion circuit, e.g., an inverter, when the battery <NUM> is connected to a load through the power conversion circuit. In <FIG>, the power conversion circuit and the load are not illustrated.

When the battery <NUM> is electrically connected to the DC voltage source <NUM> through the DC parallel link nodes NDC, the battery <NUM> is in parallel connection to the DC voltage source <NUM>.

Therefore, as long as the DC voltage source <NUM> does not include an active power generating element, a voltage of the battery <NUM> and a voltage of the DC voltage source <NUM> have substantially the same value while the parallel connection is maintained.

In an embodiment, the battery <NUM> and the DC voltage source <NUM> may be mounted in a vehicle as a parallel power system. Herein, the vehicle may be a fossil-fuel vehicle or a hybrid vehicle.

In the above-described example, the DC voltage source <NUM> may be a lead storage battery and may be used to provide power to a start motor to start an engine, and to supply operating power to various electric elements included in the vehicle. The lead storage battery may be charged by power generated by a generator or a regeneration charger while the vehicle is being driven. The battery <NUM> may be a lithium battery and may be used to supplement power of the lead storage battery and to store idle power which is not stored in the lead storage battery but is wasted. When the above-described parallel power system is mounted in the vehicle, the battery <NUM> may contribute to an increase in fuel efficiency of the vehicle.

Preferably, the switch element failure diagnosis apparatus <NUM> according to the present disclosure may include a current measuring unit <NUM>, a diagnosis resistor <NUM>, a diagnosis switch <NUM>, and a controller <NUM> in order to diagnose a failure of the switch element <NUM>.

The current measuring unit <NUM> may measure a current flowing through the second line L<NUM> between the second electrode <NUM> of the battery <NUM> and the second external terminal T- upon a request of the controller <NUM>, and input the measured current value to the controller <NUM>.

In an example, the current measuring unit <NUM> may include a shunt resistor RSHUNT provided on the second line L<NUM>, and an analog-digital converter (ADC) <NUM>.

The ADC <NUM> converts an analog voltage applied to two terminal ends of the shunt resistor RSHUNT when the current flows through the second line L<NUM>, into a digital voltage, and outputs the converted digital voltage to the controller <NUM> as the measured current value.

When the digital voltage is received as the measured current value from the ADC <NUM>, the controller <NUM> may determine a current level ISHUNT flowing through the second line L<NUM> based on the Ohm's Law by using a pre-defined resistance value of the shunt resistor RSHUNT and the measured current value.

In another example, the current measuring unit <NUM> may be replaced with a Hall sensor which is a sort of a current sensor. The Hall sensor may input a voltage value indicating the magnitude of the current flowing through the second line L<NUM>, to the controller <NUM> as the measured current value. Then, the controller <NUM> may determine the current level ISHUNT flowing through the second line L<NUM>, based on pre-defined mathematical calculation by using the voltage value input as the measured current value.

A method of detecting the current level ISHUNT flowing through the second line L<NUM> by using the shunt resistor RSHUNT or the Hall sensor is well known to those skilled in the art and thus will not be further described in detail herein.

Preferably, the diagnosis resistor <NUM> and the diagnosis switch <NUM> may be provided on a third line L<NUM> to connect the first and second lines L<NUM> and L<NUM>, and the diagnosis resistor <NUM> and the diagnosis switch <NUM> may be connected to each other in series.

The diagnosis switch <NUM> may be turned on by receiving a control signal from the controller <NUM> when a failure of the switch element <NUM> needs to be diagnosed, and may be turned off when the failure diagnosis is completed.

Preferably, the third line L<NUM> may be connected to an outer node N+ of the switch element <NUM> and an outer node N- of the current measuring unit <NUM>. Then, an existing resistor used to measure a charge current or a discharge current may also be used as the shunt resistor <NUM>. That is, the shunt resistor <NUM> may be used to measure the magnitude of a charge current or a discharge current, and used to measure the magnitude of a current flowing through the second line L<NUM> in order to diagnose a failure of the switch element <NUM>. This may contribute to a reduction in costs of a diagnosis apparatus. In addition, the reliability of diagnosing a failure of the switch element <NUM> may be increased by increasing the level of a current flowing through the shunt resistor <NUM>.

The switch element failure diagnosis apparatus <NUM> according to an embodiment of the present disclosure may further include a first voltage measuring unit <NUM> and a second voltage measuring unit <NUM> in order to diagnose a failure of the switch element <NUM>.

The first voltage measuring unit <NUM> measures a first measured voltage value V<NUM> indicating a voltage of the battery <NUM> applied between the first and second electrodes <NUM> and <NUM> of the battery <NUM>, and inputs the same to the controller <NUM>.

The second voltage measuring unit <NUM> measures a second measured voltage value V<NUM> indicating a voltage applied to the DC parallel link nodes NDC, and inputs the same to the controller <NUM>.

The first and second voltage measuring units <NUM> and <NUM> may be configured as typical voltage measuring circuits (e.g., differential amplifier circuits) known to those skilled in the art, and thus will not be described in detail herein.

The controller <NUM> applies a control signal for turning on or off the switch element <NUM>, to the switch element <NUM>. After the control signal is applied, the controller <NUM> turns on the diagnosis switch <NUM> and then receives the measured current value from the current measuring unit <NUM>. The controller <NUM> determines the current level ISHUNT flowing through the second line L<NUM> by using the measured current value. The controller <NUM> may diagnose a failure of the switch element <NUM> by comparing the current level ISHUNT to a pre-defined reference current level Ith.

The controller <NUM> may selectively include a processor, an application-specific integrated circuit (ASIC), another chipset, a logic circuit, a register, a communication modem, a data processing unit, etc., which are known to those skilled in the art, in order to execute various control logics to be described below. When the control logics are implemented as software, the controller <NUM> may be implemented as a set of program modules. In this case, the program modules may be stored in a memory and may be executed by a processor. The memory may be provided inside or outside the processor, and may be connected to the processor via various well-known means. Alternatively, the memory may be included in a storage unit <NUM> to be described below. The memory collectively refers to data storage devices irrespective of device types and is not limited to any particular memory device.

According to an aspect, the controller <NUM> may apply a control signal for turning off the switch element <NUM>, to the switch element <NUM>, and diagnose that the switch element <NUM> has a short circuit failure, if the current level ISHUNT determined by using the measured current value input from the current measuring unit <NUM> is greater than the reference current level Ith.

According to another aspect, the controller <NUM> may apply a control signal for turning on the switch element <NUM>, to the switch element <NUM>, and diagnose that the switch element <NUM> has an open circuit failure, if the current level ISHUNT determined by using the measured current value input from the current measuring unit <NUM> is less than the reference current level Ith.

According to still another aspect, the controller <NUM> may apply a control signal for turning off the switch element <NUM>, to the switch element <NUM>.

The controller <NUM> may receive the first measured voltage value V<NUM> indicating the voltage of the battery <NUM> and the second measured voltage value V<NUM> indicating the voltage of the DC parallel link nodes NDC from the first and second voltage measuring units <NUM> and <NUM>, respectively, and receive the measured current value from the current measuring unit <NUM> to determine the current level ISHUNT flowing through the second line L<NUM>.

The controller <NUM> may diagnose that the switch element <NUM> is normal, if a difference between the first measured voltage value V<NUM> indicating the voltage of the battery <NUM> and the second measured voltage value V<NUM> indicating the voltage of the DC parallel link nodes NDC is greater than a reference voltage level Vth.

The controller <NUM> may diagnose that the switch element <NUM> has a short circuit failure, if the difference between the first measured voltage value V<NUM> indicating the voltage of the battery <NUM> and the second measured voltage value V<NUM> indicating the voltage of the DC parallel link nodes NDC is less than the reference voltage level Vth and if the current level ISHUNT of the second line L<NUM> determined by using the measured current value is greater than the reference current level Ith.

According to still another aspect, the controller <NUM> may apply a control signal for turning on the switch element <NUM>, to the switch element <NUM> in order to diagnose an open circuit failure of the switch element <NUM>.

The controller <NUM> may receive the first measured voltage value V<NUM> indicating the voltage of the battery <NUM> and the second measured voltage value V<NUM> indicating the voltage of the DC parallel link nodes NDC from the first and second voltage measuring units <NUM> and <NUM>, respectively, and receive the measured current value from the current measuring unit <NUM> to determine the current level ISHUNT of the second line L<NUM>.

The controller <NUM> may diagnose that the switch element <NUM> has an open circuit failure, if the difference between the first measured voltage value V<NUM> indicating the voltage of the battery <NUM> and the second measured voltage value V<NUM> indicating the voltage of the DC parallel link nodes NDC is greater than the reference voltage level Vth.

The controller <NUM> may diagnose that the switch element <NUM> operates normally, if the difference between the first measured voltage value V<NUM> indicating the voltage of the battery <NUM> and the second measured voltage value V<NUM> indicating the voltage of the DC parallel link nodes NDC is less than the reference voltage level Vth and if the current level ISHUNT of the second line L<NUM> determined by using the measured current value is greater than the reference current level Ith.

In the present disclosure, the reference current level Ith used for reference to diagnose a short circuit failure of the switch element <NUM> may include a plurality of current values Ith(k) having different magnitudes. Herein, k may be a natural number of <NUM> to p, and Ith(k) may increase in proportion to k.

In this case, the controller <NUM> may diagnose that the switch element <NUM> has a short circuit failure, if the current level ISHUNT flowing through the second line L<NUM> is greater than the maximum current value Ith(p) among the plurality of current values Ith(k) set as the reference current level Ith.

The controller <NUM> may identify the maximum current value among current values less than or equal to the current level ISHUNT flowing through the second line L<NUM> among the current values Ith(k) set as the reference current level Ith, and diagnose that the switch element <NUM> has a pre-defined weak short circuit failure corresponding to the identified maximum current value.

Herein, the weak short circuit failure refers to an intermediate state between a fully short-circuited state and a normal state of the switch element <NUM>. The weak short circuit failure may be pre-defined in a plurality of stages based on levels of a resistance value of the switch element <NUM> when the switch element <NUM> is turned off.

The weak short circuit failure may be pre-defined in a plurality of stages based on the magnitudes of the current values Ith(k) set as the reference current level Ith. The current values Ith(k) may be pre-defined through a test based on resistance characteristics of the switch element <NUM>.

For example, the magnitudes of the plurality of current values Ith(k) to be set as the reference current level Ith may be determined by preparing a plurality of switch elements <NUM> having different resistances due to different levels of weak short circuit failures and then measuring the value of the current flowing through the second line L<NUM> when each switch element <NUM> is turned off.

According to still another aspect of the present disclosure, the apparatus <NUM> may further include the storage unit <NUM> configured to store diagnosis information of the switch element <NUM>. In this case, the controller <NUM> may store the diagnosis information of the switch element <NUM> in the storage unit <NUM>. The diagnosis information may include identification code indicating the type of a failure of the switch element <NUM>, and time information when the failure is diagnosed. Preferably, the identification code may include numbers, characters, symbols, or a combination thereof, which indicate the type of the failure of the switch element <NUM>.

The storage unit <NUM> stores programs required when the controller <NUM> executes control logics, data generated when the control logics are executed, and pre-defined data used when the control logics are executed.

The storage unit <NUM> is not limited to a particular type and may be any data storage device such as dynamic random access memory (DRAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory, or a register.

According to still another aspect of the present disclosure, the apparatus <NUM> may further include a display unit <NUM> configured to output the diagnosis information of the switch element <NUM>. In this case, the controller <NUM> may output the diagnosis information of the switch element <NUM> on the display unit <NUM> as a graphic user interface. The diagnosis information may include identification code indicating the type of a failure of the switch element <NUM>, and time information when the failure is diagnosed. Preferably, the identification code may include numbers, characters, symbols, or a combination thereof, which indicate the type of the failure of the switch element <NUM>.

The display unit <NUM> may not always be included in the apparatus <NUM> according to the present disclosure, but may be included in another apparatus. In this case, the display unit <NUM> is connected to the controller <NUM> not directly but indirectly via a control means included in the other apparatus. Therefore, it should be understood that electrical connection between the display unit <NUM> and the controller <NUM> also includes the above-described indirect connection.

When the controller <NUM> may not directly display the diagnosis information of the switch element <NUM> on the display unit <NUM>, the controller <NUM> may provide the diagnosis information to another apparatus including a display. In this case, the controller <NUM> may be data-communicably connected to the other apparatus, and the other apparatus may receive the diagnosis information of the switch element <NUM> from the controller <NUM> and display the received diagnosis information as a graphic user interface on the display connected thereto.

According to still another aspect of the present disclosure, the apparatus <NUM> may further include a communication interface <NUM> capable of transmitting or receiving communication data.

The communication interface <NUM> may support controller area network (CAN), local interconnect network (LIN), FlexRay, or media oriented systems transport (MOST) communication.

The controller <NUM> may generate communication data including the diagnosis information of the switch element <NUM> and then output the generated communication data through the communication interface <NUM>. The communication data may be transmitted through a communication network to an external device <NUM>. The external device <NUM> may receive the communication data, extract the diagnosis information from the communication data, and visually display the extracted diagnosis information on a display connected to the external device <NUM>. For example, the external device <NUM> may be a diagnosis apparatus exclusively used for the switch element <NUM>, or a main control computer of a load having the battery <NUM>, e.g., a vehicle.

<FIG> is a view showing the flow of a current in the circuit of <FIG> when the switch element <NUM> having received a turn-off control signal is normally turned off and the diagnosis switch <NUM> is turned on.

Referring to <FIG>, when the switch element <NUM> is normally turned off, a current flows only in a right closed-loop circuit with respect to the third line L<NUM> and does not flow through the shunt resistor RSHUNT. That is, the current level ISHUNT flowing through the second line L<NUM> is close to zero. In the drawing, the flow of the current is indicated by a dashed dotted arrow.

<FIG> is a view showing the flow of a current in the circuit of <FIG> when the switch element <NUM> having received a turn-off control signal has a short circuit failure and thus is not normally turned off and the diagnosis switch <NUM> is turned on.

Referring to <FIG>, when the switch element <NUM> has a short circuit failure, a current flows in both closed-loop circuits at left and right sides of the third line L<NUM>.

Initially, a current level IL3 flowing through the third line L<NUM> may be determined based on the values of resistance components provided on the third line L<NUM> and the magnitude of a voltage applied to two ends of the third line L<NUM> as shown in Mathematical Formula <NUM>.

In Mathematical Formula <NUM>, IL3 denotes the magnitude of a current flowing through the third line L<NUM>. V<NUM> denotes a second measured voltage value indicating a voltage of the DC parallel link nodes NDC measured by the second voltage measuring unit <NUM>. Rdig denotes a pre-defined resistance value of the diagnosis resistor <NUM>. RSW(on) denotes a pre-defined turn-on resistance of the diagnosis switch <NUM>.

Between the two resistance values included in a denominator of Mathematical Formula <NUM>, compared to Rdig, the value of RSW(on) is negligibly small. Therefore, the current level IL3 flowing through the third line L<NUM> may be approximated to V<NUM>/Rdig.

A current magnitude IRIGHT flowing through a right closed-loop circuit and a current magnitude ILEFT flowing through a left closed-loop circuit may be determined based on a ratio of resistance components included in the right closed-loop circuit to those included in the left closed-loop circuit.

That is, it is assumed that a sum of resistance values of the resistance components included in the right closed-loop circuit is denoted by RRIGHT and a sum of resistance values of the resistance components included in the left closed-loop circuit is denoted by RLEFT.

Then, the current magnitude ILEFT flowing through the left closed-loop circuit may be determined as shown in Mathematical Formula <NUM>, and the current magnitude IRIGHT flowing through the right closed-loop circuit may be determined as shown in Mathematical Formula <NUM>. <MAT> <MAT>.

In Mathematical Formulae <NUM> and <NUM>, RRIGHT denotes a sum of resistance values of resistance components included in a right closed-loop circuit with respect to the third line L<NUM>, and may be represented as shown in Mathematical Formula <NUM>.

In Mathematical Formulae <NUM> and <NUM>, RLEFT denotes a sum of resistance values of resistance components included in a left closed-loop circuit with respect to the third line L<NUM>, and may be represented as shown in Mathematical Formula <NUM>.

In Mathematical Formulae <NUM> and <NUM>, RINT1+, RINT1-, RINT2+, RINT2-, REXT+, and REXT-denote resistance values of resistance components existing on paths through which a current flows. RBAT denotes an internal resistance of the battery <NUM>. RDC_SOURCE denotes an internal resistance of the DC voltage source <NUM>. RRELAY denotes a turn-on resistance of the switch element <NUM>, and RSHUNT denotes a resistance value of the shunt resistor <NUM> of the current measuring unit <NUM>.

The resistance values included in Mathematical Formulae <NUM> and <NUM> may be pre-defined by measuring resistance value between nodes connected to circuit elements by using a resistance meter. The defined resistance values may be pre-stored in the storage unit <NUM>.

In Mathematical Formulae <NUM> and <NUM>, each resistance value may have a small value less than several milliohms. Thus, RRIGNT and RLEFT may be approximated to substantially the same value. In this case, the current level ILEFT flowing through the left closed-loop circuit with respect to the third line L<NUM> may be approximated as shown in Mathematical Formula <NUM>.

The current level ILEFT flowing through the left closed-loop circuit is substantially the same as the current level ISHUNT of the second line L<NUM>, which flows through the shunt resistor <NUM>.

Therefore, according to the present disclosure, a value equal to a current level determined based on Mathematical Formula <NUM> or a value less than the current level determined based on Mathematical Formula <NUM> by a certain degree in consideration of a margin of measurement may be defined as the reference current level Ith.

For the reference current level Ith, V<NUM> indicating the second measured voltage value measured from the two ends of the third line L<NUM> is an only variable, and Rdig denotes a pre-defined resistance value of the diagnosis resistor <NUM>.

Accordingly, if the current level ISHUNT measured by the shunt resistor <NUM> when the diagnosis switch <NUM> is turned on after a control signal for turning off the switch element <NUM> is applied to the switch element <NUM> is greater than the reference current level Ith calculated by using the second measured voltage value V<NUM>, it may be diagnosed that the switch element <NUM> has a short circuit failure. Otherwise, if the current level ISHUNT of the second line L<NUM> measured by the shunt resistor <NUM> is sufficiently less than the reference current level Ith, it may be diagnosed that a function of turning off the switch element <NUM> operates normally.

An open circuit failure of the switch element <NUM> may be diagnosed by turning on the diagnosis switch <NUM> after a control signal for turning on the switch element <NUM> is applied to the switch element <NUM>, and then measuring the current level ISHUNT flowing through the shunt resistor <NUM>.

That is, if the current level ISHUNT flowing through the shunt resistor <NUM> is greater than the reference current level Ith determined by using the second measured voltage value V<NUM>, it may be diagnosed that a function of turning on the switch element <NUM> operates normally. Otherwise, if the current level ISHUNT flowing through the shunt resistor <NUM> is remarkably less than the reference current level Ith determined by using the second measured voltage value V<NUM>, it may be diagnosed that that the switch element <NUM> has an open circuit failure.

According to the present disclosure, a difference between the first and second measured voltage value V<NUM> and V<NUM> measured by using the first and second voltage measuring units <NUM> and <NUM> may be calculated and it may be additionally diagnosed whether the switch element <NUM> operates normally, based on the calculated difference.

For example, if the difference between the first and second measured voltage value V<NUM> and V<NUM> measured by using the first and second voltage measuring units <NUM> and <NUM> after a control signal for turning off the switch element <NUM> is applied to the switch element <NUM> is greater than the preset reference voltage level Vth, it may be diagnosed that a function of turning off the switch element <NUM> operates normally.

As another example, if the difference between the first and second measured voltage value V<NUM> and V<NUM> measured by using the first and second voltage measuring units <NUM> and <NUM> after a control signal for turning on the switch element <NUM> is applied to the switch element <NUM> is greater than the preset reference voltage level Vth, it may be diagnosed that the switch element <NUM> has an open circuit failure and thus a function of turning on the switch element <NUM> does not operate normally.

The above-described method of diagnosing a failure of the switch element <NUM> by using the first and second measured voltage value V<NUM> and V<NUM> may be preliminarily performed before a failure of the switch element <NUM> is diagnosed by using the current level ISHUNT flowing through the shunt resistor <NUM>.

Based on the above description, a method of diagnosing a failure of the switch element <NUM> by using the switch element failure diagnosis apparatus <NUM> according to the present disclosure will now be described in detail.

In the following description, although not particularly mentioned, the method according to the present disclosure is performed by the controller <NUM>.

<FIG> is a flowchart of a method of diagnosing a short circuit failure of the switch element <NUM>, according to the present disclosure.

Referring to <FIG>, initially, the controller <NUM> applies a control signal for turning off the switch element <NUM>, to the switch element <NUM> in order to diagnose a short circuit failure of the switch element <NUM> (operation S10).

Subsequently, the controller <NUM> turns on the diagnosis switch <NUM> provided on the third line L<NUM>, by applying a control signal for turning on the diagnosis switch <NUM>, to the diagnosis switch <NUM> (operation S20).

Then, the controller <NUM> controls the first voltage measuring unit <NUM> and detects a voltage of the battery <NUM> by receiving the first measured voltage value V<NUM> indicating the voltage of the battery <NUM>, from the first voltage measuring unit <NUM> (operation S30).

Thereafter, the controller <NUM> controls the second voltage measuring unit <NUM> and detects a voltage of the DC parallel link nodes NDC by receiving the second measured voltage value V<NUM> indicating the voltage of the DC parallel link nodes NDC, from the second voltage measuring unit <NUM> (operation S40).

Subsequently, the controller <NUM> controls the current measuring unit <NUM> and detects the current level ISHUNT flowing through the second line L<NUM> by receiving a measured current value indicating the current level ISHUNT flowing through the second line L<NUM>, from the current measuring unit <NUM> (operation S50).

Then, the controller <NUM> calculates a difference between the first measured voltage value V<NUM> indicating the voltage of the battery <NUM> and the second measured voltage value V<NUM> indicating the voltage of the DC parallel link nodes NDC, and determines whether the difference value is greater than the preset reference voltage level Vth (operation S60).

Upon determining that the difference between the first and second measured voltage values V<NUM> and V<NUM> is greater than the reference voltage level Vth in operation S60, the controller <NUM> diagnoses that a function of turning off the switch element <NUM> operates normally (operation S90).

Otherwise, upon determining that the difference between the first and second measured voltage values V<NUM> and V<NUM> is less than the reference voltage level Vth in operation S60, the controller <NUM> proceeds to operation S70.

Thereafter, the controller <NUM> determines whether the current level ISHUNT of the second line L<NUM> detected in operation S50 is greater than the preset reference current level Ith (operation S70).

Upon determining that the current level ISHUNT of the second line L<NUM> is greater than the reference current level Ith in operation S70, the controller <NUM> diagnoses that the switch element <NUM> has a short circuit failure and thus the function of turning off the switch element <NUM> does not operate normally (operation S80). Otherwise, upon determining that the current level ISHUNT of the second line L<NUM> is sufficiently less than the reference current level Ith, the controller <NUM> diagnoses that the function of turning off the switch element <NUM> operates normally (operation S90).

For reference, when the switch element <NUM> has a short circuit failure, a current flows through a left closed-loop circuit with respect to the third line L<NUM> (see <FIG>), and the magnitude of the current corresponds to the current level ISHUNT detected in operation S50.

The reference current level Ith used for reference to diagnose a short circuit failure of the switch element <NUM> may include a plurality of current values Ith(k) having different magnitudes. Herein, k may be a natural number of <NUM> to p, and Ith(k) may increase in proportion to k.

In this case, in operation S70, the controller <NUM> may diagnose that the switch element <NUM> has a short circuit failure, if the current level ISHUNT flowing through the second line L<NUM> is greater than the maximum current value Ith(p) among the plurality of current values Ith(k) set as the reference current level Ith.

In an embodiment not shown in the drawing, the controller <NUM> may identify the maximum current value among current values less than or equal to the current level ISHUNT flowing through the second line L<NUM> among the current values Ith(k) set as the reference current level Ith, and diagnose that the switch element <NUM> has a pre-defined weak short circuit failure corresponding to the identified maximum current value.

The weak short circuit failure may be pre-defined in a plurality of stages based on the magnitudes of the current values Ith(k) set as the reference current level Ith. A method of determining the current values Ith(k) through a test has been described above. Information about the plurality of stages of the weak short circuit failure corresponding to the current values Ith(k) may be pre-stored in the storage unit <NUM>.

Although not shown in the drawing, the controller <NUM> may generate diagnosis information of the switch element <NUM>. Herein, the diagnosis information may include time information when the switch element <NUM> is diagnosed, and identification code for identifying a diagnosis result. The identification code includes numbers, characters, symbols, or a combination thereof.

The controller <NUM> may store the generated diagnosis information in the storage unit <NUM>, output the generated diagnosis information on the display unit <NUM> as a graphic user interface, or transmit the generated diagnosis information through the communication interface <NUM> to the external device <NUM>.

In the above-described control logics, it will be understood that the controller <NUM> may skip operation S60 and directly proceed to operation S70.

<FIG> is a flowchart of a method of diagnosing an open circuit failure of the switch element <NUM>, according to the present disclosure.

Referring to <FIG>, initially, the controller <NUM> applies a control signal for turning on the switch element <NUM>, to the switch element <NUM> in order to diagnose an open circuit failure of the switch element <NUM> (operation P10).

Subsequently, the controller <NUM> turns on the diagnosis switch <NUM> provided on the third line L<NUM>, by applying a control signal for turning on the diagnosis switch <NUM>, to the diagnosis switch <NUM> (operation P20).

Then, the controller <NUM> controls the first voltage measuring unit <NUM> and detects a voltage of the battery <NUM> by receiving the first measured voltage value V<NUM> indicating the voltage of the battery <NUM>, from the first voltage measuring unit <NUM> (operation P30).

Thereafter, the controller <NUM> controls the second voltage measuring unit <NUM> and detects a voltage of the DC parallel link nodes NDC by receiving the second measured voltage value V<NUM> indicating the voltage of the DC parallel link nodes NDC, from the second voltage measuring unit <NUM> (operation P40).

Subsequently, the controller <NUM> controls the current measuring unit <NUM> and detects the current level ISHUNT flowing through the second line L<NUM> by receiving a measured current value indicating the current level ISHUNT flowing through the second line L<NUM>, from the current measuring unit <NUM> (operation P50).

Then, the controller <NUM> calculates a difference between the first measured voltage value V<NUM> indicating the voltage of the battery <NUM> and the second measured voltage value V<NUM> indicating the voltage of the DC parallel link nodes NDC, and determines whether the difference value is greater than the preset reference voltage level Vth (operation P60).

Upon determining that the difference between the first and second measured voltage values V<NUM> and V<NUM> is greater than the reference voltage level Vth in operation P60, the controller <NUM> diagnoses that the switch element <NUM> has an open circuit failure and thus a function of turning on the switch element <NUM> does not operate normally (operation P90).

Otherwise, upon determining that the difference between the first and second measured voltage values V<NUM> and V<NUM> is sufficiently less than the reference voltage level Vth in operation P60, the controller <NUM> proceeds to operation P70.

Thereafter, the controller <NUM> determines whether the current level ISHUNT of the second line L<NUM> detected in operation P50 is greater than the preset reference current level Ith (operation P70).

Upon determining that the current level ISHUNT of the second line L<NUM> is greater than the reference current level Ith in operation P70, the controller <NUM> diagnoses that the function of turning on the switch element <NUM> operates normally (operation P80).

Otherwise, upon determining that the current level ISHUNT of the second line L<NUM> is sufficiently less than the reference current level Ith in operation P70, the controller <NUM> diagnoses that the switch element <NUM> has an open circuit failure and thus the function of turning on the switch element <NUM> does not operate normally (operation P90)
For reference, when the switch element <NUM> has an open circuit failure, a current does not flow through a left closed-loop circuit with respect to the third line L<NUM> (see <FIG>) and thus the current level ISHUNT flowing through the second line L<NUM> has a value of or closed to zero.

Although not shown in the drawing, the controller <NUM> may generate diagnosis information of the switch element <NUM> of operation P80 or P90. Herein, the diagnosis information may include time information when the switch element <NUM> is diagnosed, and identification code for identifying a diagnosis result. The identification code includes numbers, characters, symbols, or a combination thereof.

In the above-described control logics, it will be understood that the controller <NUM> may skip operation P60 and directly proceed to operation P70.

It will be also understood that a selective combination of two or more of the various control logics of the controller <NUM> may be implemented as an embodiment of the present disclosure.

Two or more of the various control logics of the controller <NUM> may be combined and the combined control logics may be written based on a computer-readable code system and may be recorded on a computer-readable recording medium.

The recording medium is not limited to a particular type and may be any recording medium accessible by a processor included in a computer. For example, the recording medium includes at least one selected from the group including read-only memory (ROM), random-access memory (RAM), a register, a CD-ROM, magnetic tape, a hard disk, a floppy disk, and an optical data storage device.

The code system may be distributed and stored in computers connected via a network and may be executed by the computers. Also, functional programs, codes, and code segments for implementing the combined control logics can be easily construed by programmers of ordinary skill in the art.

In the above-descriptions of the embodiments of the present disclosure, elements with suffixes such as '-unit' and '-er/-or' should be understood not as physically defined elements but as functionally defined elements. Therefore, each element may be optionally combined with another element or may be divided into sub-elements for efficient execution of control logic(s).

However, even when the elements are combined or divided, it will be understood by those skilled in the art that the combined or divided elements fall within the scope of the present disclosure as long as function identities thereof are shown.

However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the scope of the invention, which is defined by the appended claims, will become apparent to those skilled in the art from this detailed description.

Claim 1:
A vehicle comprising:
a battery (<NUM>);
a DC voltage source (<NUM>); and
an apparatus (<NUM>) for diagnosing a failure of a switch element (<NUM>) provided on a first line (L<NUM>) between a first electrode (<NUM>) of the battery (<NUM>) and a first external terminal (T+), the apparatus comprising:
a current measuring unit (<NUM>) configured to measure a current flowing through a second line (L<NUM>) between a second electrode (<NUM>) of the battery and a second external terminal (T-);
a diagnosis resistor (<NUM>) and a diagnosis switch (<NUM>) provided on a third line (L<NUM>) to connect an outer node (N+) of the switch element and an outer node (N-) of the current measuring unit, and connected to each other in series; and
a controller (<NUM>) configured to apply a control signal for turning on or off the switch element, to the switch element, to turn on the diagnosis switch after the control signal is applied and then receive a measured current value from the current measuring unit, to determine a level of the current flowing through the second line, by using the measured current value, and to diagnose a failure of the switch element by comparing the current level to a reference current level,
wherein the first and second lines are connected to direct current (DC) parallel link nodes to which the DC voltage source (<NUM>) is connected such that the battery (<NUM>) is in parallel connection to the DC voltage source (<NUM>),
wherein the DC voltage source (<NUM>) is a different type of battery which has a same nominal voltage as the battery (<NUM>),
wherein the battery (<NUM>) and the DC voltage source (<NUM>) is a parallel power system mounted in the vehicle and the DC voltage source (<NUM>) is chargeable by a generator or a regeneration charger while the vehicle is being driven,
wherein a voltage of the DC voltage source (<NUM>) has substantially the same value as the battery (<NUM>) while the parallel connection is maintained,
wherein the reference current level comprises a plurality of current values having different magnitudes, and
wherein the controller is configured to apply a control signal for turning off the switch element, to the switch element, to identify a current value corresponding to the current level among the current values set as the reference current level, and to diagnose that the switch element has a pre-defined weak short circuit failure corresponding to the identified current value.