Battery charging system for vehicle and control method of the same

A battery charging system for a vehicle includes a generator, a battery, a DC/DC converter converting the electrical power generated by the generator and supplying the converted electrical power to the electrical device of the vehicle and supplying the electrical power to an electrical device, and charging the battery, an energy storage device storing the electrical power generated from the generator and providing the stored electrical power to the DC/DC converter, and an engine control unit controlling the generator to charge the energy storage device by providing regenerative power generated by the generator in a deceleration driving section of the vehicle, calculating a low-voltage control amount determined to correspond to a state of the battery connected to the DC/DC converter and whether the electrical device of the vehicle operates, and controlling the DC/DC converter to charge the electrical power in the battery based on the calculated low-voltage control amount.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority of Korean Patent Application Number 10-2011-0072344 filed Jul. 21, 2011, the entire contents of which application is incorporated herein for all purposes by this reference.

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to a battery charging system for a vehicle and a control method of the same, and more particularly, to a battery charging system for a vehicle that charges a battery by controlling a generator and a DC/DC converter, and a control method of the same.

2. Description of Related Art

The battery charging system applied to a vehicle in the related art performs constant charging control regardless of a driving state for low-voltage battery control as shown inFIG. 4A. However, in the control method, fuel is needlessly consumed due to constant charging.

In addition, the battery charging system for the vehicle in the related art controls voltage according to the driving state for low-voltage battery control as shown inFIG. 4B. However, this method burdens an electrical device due to heavy voltage fluctuation.

SUMMARY OF INVENTION

Various aspects of the present invention are directed to provide a battery charging system for a vehicle and a control method of the same that can improve fuel efficiency by reducing a charging amount as compared with a constant charging control method by holding a charging amount of the battery at a predetermined level and improve an electrical device depending on voltage fluctuation by reducing the number of times of voltage fluctuation as compared with voltage control depending on a driving pattern in the related art.

Some aspects of the present invention are directed to provide a battery charging system for a vehicle. Exemplary battery charging systems for a vehicle according to the present invention may include a generator generating electrical power by driving the vehicle, a battery mounted on the vehicle and charging and discharging the electrical power, a DC/DC converter connected to the battery and electrical devices of the vehicle, converting the electrical power generated by the generator and supplying the converted electrical power to the electrical devices of the vehicle, and supplying the electrical power to the battery, an energy storage device storing the electrical power generated from the generator and providing the stored electrical power to the DC/DC converter, and an engine control unit controlling the generator to charge the energy storage device by providing regenerative power generated by the generator in a deceleration driving section of the vehicle, calculating a low-voltage control amount determined to correspond to a state of the battery connected to the DC/DC converter and whether the electrical device of the vehicle operates, and controlling the DC/DC converter to charge the electrical power in the battery based on the calculated low-voltage control amount.

The engine control unit may include a plurality of controlling modules, including but not limited to an energy storage device controlling module and a number of first voltage controlling modules.

The engine control unit may include a first voltage controlling module determining the low-voltage control amount as a first low-voltage control value according to a battery temperature among states of the battery when a high-load electrical device among the electrical devices of the vehicle operates.

The engine control unit may further include a second voltage controlling module determining the low-voltage control amount as a second low-voltage control value higher than the first low-voltage control value according to the battery temperature among the states of the battery when a low-load electrical device among the electrical devices of the vehicle operates.

The engine control unit may also or further include a third voltage controlling module determining the low-voltage control amount to correspond to an State of Charge (SOC) value and a battery temperature among states of the battery when the electrical devices of the vehicle do not operate and the SOC value among the states of the battery is higher than a predetermined SOC set value.

The engine control unit may also or further include a fourth voltage controlling module determining the low-voltage control amount to correspond to a battery temperature among states of the battery when the electrical devices of the vehicle do not operate and the SOC value among the states of the battery is not higher than the predetermined SOC set value or the DC/DC converter is faulty.

Other aspects of the present invention are directed to provide a control method of a battery charging system for a vehicle, which may include a generator, a battery, an energy storage device storing electrical power generated from the generator, and a DC/DC converter connected to the battery and an electrical device of the vehicle. Exemplary control methods according to the present invention may include controlling the generator to charge the energy storage device by providing regenerative power generated by the generator in a deceleration driving section of the vehicle, calculating a low-voltage control amount determined to correspond to a state of the battery connected to the DC/DC converter and whether the electrical device of the vehicle operates, and controlling the DC/DC converter to charge the electrical power in the battery based on the calculated low-voltage control amount.

Calculating of the low-voltage control amount may include determining the low-voltage control amount as a first low-voltage control value according to a battery temperature among states of the battery when a high-load electrical device among the electrical devices of the vehicle operates, and determining the low-voltage control amount as a second low-voltage control value higher than the first low-voltage control value according to the battery temperature among the states of the battery when a low-load electrical device among the electrical devices of the vehicle operates.

Calculating of the low-voltage control amount may also or further include determining the low-voltage control amount to correspond to an SOC value and a battery temperature among states of the battery when the electrical devices of the vehicle do not operate and the SOC value among the states of the battery is higher than a predetermined SOC set value, and determining the low-voltage control amount to correspond to the battery temperature when the electrical devices of the vehicle do not operate and the SOC value is not higher than the predetermined SOC set value or the DC/DC converter is faulty.

According to various aspects of the present invention, fuel consumption depending on overcharging can be reduced as compared with the related art by performing charging control of a battery to correspond to whether a control module of an energy storage device and an electrical device operate and the state of the battery, and side effects transferred to the electrical device of a vehicle can be reduced due to small voltage fluctuation as compared with the related art.

DETAILED DESCRIPTION

Hereinafter, a battery charging system1for a vehicle according to various embodiments of the present invention will be described with reference to the accompanying drawings.

Referring toFIG. 1, battery charging system1for a vehicle according to the various embodiments of the present invention may include a generator10, a battery20, an energy storage device30, a DC/DC converter40, and an engine control unit50. Engine control unit50may be expressed as an ECU which is an abbreviation of an engine control unit.

Generator10may be constituted by an alternator and a regulator regulating a generation amount of the alternator. Generator10is operated by controlling engine control unit50and generates electrical power by driving the vehicle.

Battery20is mounted on the vehicle to serve to supply power to an electrical device of the vehicle together with generator10and electrical power is charged by controlling engine control unit50.

Energy storage device30is connected with generator10and DC/DC converter40as shown inFIG. 1to store the electrical power generated from generator10and transfer the stored electrical power to DC/DC converter40.

DC/DC converter40is connected to battery20and the electrical device of the vehicle as shown inFIG. 1to convert the electrical power generated by generator10and supply the converted electrical power to the electrical device of the vehicle, and supply the electrical power to charge the battery.

Engine control unit50controls generator10to charge energy storage device30by providing regenerative power generated by generator10in a deceleration driving section of the vehicle. Further engine control unit50calculates a low-voltage control amount determined to correspond to a state of battery20connected to DC/DC converter40and whether the electrical device of the vehicle operates.

Signals regarding the state of battery20and whether the electrical device operates are inputted into engine control unit50as shown in dotted lines a1and a2as shown inFIG. 1. Engine control unit50controls DC/DC converter40to charge the electrical power in battery20based on the calculated low-voltage control amount. That is, as shown in a solid line a7ofFIG. 1, DC/DC converter40is controlled by a control signal outputted to DC/DC converter40from engine control unit50.

Hereinafter, referring toFIG. 2, engine control unit50according to various embodiments will be described in detail. Engine control unit50may include a plurality of controlling modules. Engine control unit50may include an energy storage device controlling module52, a first voltage controlling module54, a second voltage controlling module56, a third voltage controlling module58, and a fourth voltage controlling module59as shown in FIG. Herein, first voltage controlling module54, second voltage controlling module56, third voltage controlling module58, and fourth voltage controlling module59may be operated when voltage of energy storage device30is stored to reach a predetermined set value of the energy storage device by an operation of the energy storage device.

Energy storage device controlling module52charges energy storage device30by providing the regenerative power generated by generator10in the deceleration driving section of the vehicle and providing the regenerative power to energy storage device30.

That is, by monitoring a voltage value of energy storage device30through dotted line a4shown inFIG. 1, generator10is controlled through a solid line a6shown inFIG. 1until the monitored voltage value reaches the predetermined set value of the energy storage device.

First voltage control module54may operate after energy storage device controlling module52operates. First voltage controlling module54determines the low-voltage control amount as a first low-voltage control value according to a battery temperature among the states of the battery when a high-load electrical device such as lamps, a wiper, or a blower among the electrical devices operates.

That is, first voltage controlling module54determines whether or not the electrical device through dotted lines a2shown inFIG. 1and determines the battery temperature through dotted lines a1, and calculates the first low-voltage control value which is the low-voltage control amount based thereon. Engine control unit50charges battery20by controlling DC/DC converter40through solid line a7shown inFIG. 1based on the calculated first low-voltage control value.

Second voltage controlling module56may operate after energy storage device controlling module52operates. Second voltage controlling module56determines the low-voltage control amount as a second low-voltage control value larger than the first low-voltage control value according to the battery temperature among the states of battery20when a low-load electrical device among the electrical devices of the vehicle operates.

That is, second voltage controlling module56determines whether or not the electrical device through dotted lines a2shown inFIG. 1and determines the battery temperature through dotted lines a1, and calculates the second low-voltage control value which is the low-voltage control amount based thereon. Engine control unit50charges battery20by controlling DC/DC converter40through solid line a7shown inFIG. 1based on the calculated second low-voltage control value.

Third voltage controlling module58may operate after energy storage device controlling module52operates. Third voltage controlling module58determines the low-voltage control amount to correspond to an State of Charge (SOC) value and the battery temperature when the electrical device of the vehicle does not operate and the SOC value among the states of battery20is higher than a predetermined SOC set value.

That is, third voltage controlling module58determines the SOC value of the battery and the battery temperature through dotted lines a1shown inFIG. 1and calculates the low-voltage control amount based thereon. Engine control unit50charges battery20by controlling DC/DC converter40through solid line a7shown inFIG. 1based on the calculated low-voltage control amount.

Fourth voltage controlling module59may operate after energy storage device controlling module52operates. Fourth voltage controlling module59determines the low-voltage control amount to correspond to the battery temperature among the states of battery20when the electrical device of the vehicle does not operate and the SOC value among the states of battery20is not higher than the predetermined SOC set value in third voltage controlling module or DC/DC converter40is faulty.

That is, fourth voltage controlling module59determines the battery temperature through dotted lines a1shown inFIG. 1and calculates the low-voltage control amount based thereon. Engine control unit50charges battery20by controlling DC/DC converter40through solid line a7shown inFIG. 1based on the calculated low-voltage control amount.

According to various embodiments of the present invention, battery charging system1for the vehicle can reduce fuel consumption depending on overcharging as compared with the related art by performing charging control of the battery to correspond to whether energy storage device controlling module52and the electrical device operate and the state of the battery, and reduce side effects transferred to the electrical device of the vehicle due to small voltage fluctuation as compared with the related art.

Hereinafter, referring toFIG. 3, a control method of battery charging system1for the vehicle according to various embodiments of the present invention will be described in detail.

When an engine is operated by starting the vehicle, engine control unit50judges whether voltage of an energy storage device30is larger than a predetermined set value (S305) and controls a generator10to operate when engine control unit50judges that the voltage of energy storage device30is not larger than the set value (S307). In addition, the process returns to step S305.

That is, through step S305and S307, engine control unit50charges energy storage device30by operating generator10until the voltage of energy storage device30reaches the predetermined set value.

When the voltage of energy storage device30reaches the predetermined set value by steps S305and S307, engine control unit50starts to control a DC/DC converter40to operate (S310). Engine control unit50judges whether DC/DC converter40is faulty (S312) and when DC/DC converter40is faulty, engine control unit50activates a fault code corresponding to the fault (S314). In addition, engine control unit50performs a fourth voltage controlling module59(S316) and when the engine is terminated (S350), this control procedure is terminated.

As a judgment result in step S312, when it is judged that DC/DC converter40is not faulty, engine control unit50judges whether an electrical device of the vehicle operates (S320) and when the electrical device operates, control unit50judges whether an SOC value of a battery20is larger than a predetermined SOC set value (S324). As a judgment result in step S324, when the SOC value of battery20is larger than the SOC set value, engine control unit50performs a third voltage controlling module58and when the SOC value of battery20is not larger than the SOC set value, engine control unit50performs a fourth voltage controlling module59which is step.

As a judgment result of step S320, when the electrical device of the vehicle operates, engine control unit50judges whether a high-load electrical device such as lamps, a wiper, or a blower among the electrical devices operates (S330) and when the high-load electrical device does not operate, engine control unit performs second voltage controlling module56(S336) and when the engine is terminated (S350), this control procedure is terminated.

As a judgment result in step S330, engine control unit50performs a first voltage controlling module54when the high-load electrical device operates (S340) and engine control unit50judges whether the engine is terminated (S350), and when the engine is not terminated, the process proceeds to step S312. On the contrary, as a judgment result in step S350, when the engine is terminated, the control procedure is terminated.

As described above, since battery charging system1for the vehicle according to various embodiments targets a configuration commonly applied to all general vehicles, vehicle battery system1can be widely applied to all vehicles regardless of a hybrid vehicle and an electric vehicle in addition to a general vehicle.