KR101459449B1 - System and method for restarting voltage prediction of vehicle - Google Patents

Abstract

A system and method for estimating a restarting voltage of a vehicle are disclosed.
A system for predicting a restart voltage of a vehicle for an ISG (Idle Stop & Go) system according to an embodiment of the present invention includes: a battery capable of charge / discharge; A battery sensor unit for measuring current and temperature of the battery; And a controller for measuring a voltage of the current collected by the battery sensor unit and a charge / discharge characteristic of the battery during a predetermined period to calculate an internal resistance of the battery using a statistical technique, And an ECU (Electronic Control Unit) for estimating a battery minimum voltage at the time of engine restart after an idle stop considering a correlation between the internal resistance and internal resistance at the time of cranking.

Description

[0001] SYSTEM AND METHOD FOR RESTARTING VOLTAGE PREDICTION OF VEHICLE [0002]

The present invention relates to a system and a method for predicting a restarting voltage of a vehicle, and more particularly, to a system and method for estimating a restart state of a vehicle that estimates a state of function (SOF) after stopping an engine of an ISG And a method thereof.

In general, researches for improving fuel efficiency of internal combustion engine vehicles are actively conducted.

In particular, in order to suppress the cost required when applying the fuel efficiency improving technology, an idle stop & go (ISG) technology capable of maximizing the fuel efficiency improvement compared to other fuel efficiency improving techniques is being developed without largely changing the layout of the vehicle.

In general, the ISG system means that the engine is started automatically when the vehicle stops while the vehicle is stopped, and the engine is automatically started when the engine is stopped or the engine restart determination is made.

In the existing ISG system, battery voltage, current, and ambient temperature are precisely measured in all areas in a high performance controller such as IBS (Intelligent Battery Sensor) to judge possibility of engine restart after engine stop. The state of charge (SOF) of the battery, the state of health (SOH) of the battery and the state of function (SOF) of the battery at the time of restarting the engine are estimated, ).

Therefore, the ECU judges the battery state information (SOC, SOH, SOF) and the vehicle state information in a comprehensive manner and enters the engine stop, thereby improving the fuel efficiency when the vehicle is stopped.

However, in the case of the IBS used in the conventional ISG system, a high-performance controller for complex algorithm operation is used, which is pointed out as a cause of increase in development cost and vehicle production cost.

In other words, the conventional IBS uses a high-resolution sensor and a high-resolution analog-to-digital converter (ADC) to precisely measure the battery voltage, current and temperature in all areas. Particularly, IBS has to use expensive parts because it must precisely measure not only high current measurement at engine cranking but also low current measurement in idle state in current measurement, which raises the cost of vehicle.

On the other hand, in the case of a general vehicle that does not use IBS to suppress the production cost of the vehicle, the charge and discharge currents other than the large current such as engine cranking are measured by the ECU, SOC, charge / discharge capacity, and other information.

This makes it impossible to accurately measure voltage and current at the time of restarting the engine, thereby reducing the reliability of judging whether or not to restart the engine.

Therefore, a method of judging the possibility of restarting the engine after stopping the engine of the ISG system is desperately required by using the current sensor and the voltage measured only in the limited current range.

Patent Document 1: Japanese Laid-Open Patent Application No. 2010-223215 (published on October 10, 2010)

The embodiment of the present invention estimates the lowest voltage at the time of restarting by using a current sensor and a voltage that are measured only in a limited current range in a vehicle in which voltage and current measurement at the time of engine restart can not be performed, The present invention also provides a system and method for estimating a restart voltage of an economical battery-sensor-based vehicle.

According to an aspect of the present invention, there is provided a system for predicting a restart voltage of a vehicle for an ISG (Idle Stop & Go) system. A battery sensor unit for measuring current and temperature of the battery; And a controller for measuring a voltage of the current collected by the battery sensor unit and a charge / discharge characteristic of the battery during a predetermined period to calculate an internal resistance of the battery using a statistical technique, And an ECU (Electronic Control Unit) for estimating a battery minimum voltage at the time of engine restart after an idle stop considering a correlation between the internal resistance and internal resistance at the time of cranking.

Further, the ECU can calculate the cranking current through the required power and voltage at the engine cranking by the test data.

In addition, the ECU can calculate an average of a plurality of internal resistances based on the battery state measurement using linear regression analysis.

Also, when considering the correlation between the internal resistance and the internal resistance at the time of cranking, the ECU refers to data through at least one engine cranking test among the battery temperature, the remaining capacity, and the degree of aging, The battery's lowest voltage can be estimated at restart.

In addition, the ECU refers to a voltage immediately before cranking determined through testing, and estimates a battery minimum voltage at the time of engine restart after an idle stop, wherein the voltage immediately before cranking is an actually measured voltage, And an open circuit voltage (OCV) value according to the capacity (SOC).

According to an aspect of the present invention, there is provided a method of predicting a restarting voltage of a vehicle for an ISG (Idle Stop & Go) system, comprising the steps of: a) measuring and storing voltage and current reflecting charging and discharging characteristics of a battery; b) calculating the internal resistance of the battery using the statistical technique if the stored voltage and current exceeds a predetermined reference number; c) estimating a battery drop voltage at the time of engine cranking through correlation between the internal resistance and internal resistance at the time of cranking with reference to cranking test data according to the engine and battery condition; And d) estimating the battery minimum voltage upon engine restart after an idle stop with reference to a voltage just before cranking determined through testing.

The step b) may include calculating an internal resistance by linear regression analysis using the reference number of voltages and currents, and calculating a moving average of the plurality of internal resistances determined through the test.

Calculating a cranking current from the required power and voltage at the time of cranking by the test data between the step b) and the step c); And calculating the internal resistance at the time of cranking from the voltage fluctuation value at the time of cranking by the test data and the calculated cranking current.

Also, the step d) may include the step of selecting any one of the actual measured voltage of the battery or the open circuit voltage (OCV) value according to the remaining capacity (SOC) of the battery as the voltage immediately before cranking have.

According to the embodiment of the present invention, even when a current sensor with a large current measurement at the time of cranking is used, or when voltage and current at a very short time cranked by the controller can not be measured, (ISF) system function can be realized by providing a method of estimating the battery low voltage (SOF) at the time of engine restart after an idle stop based on the cranking test data Rm and the cranking test data base.

In addition, it is possible to reduce the cost of building the ISG system and the production cost of the vehicle by eliminating the use of the high-grade IBS (Intelligent Battery Sensor) in the construction of the ISG system and providing the alternative technology.

1 shows a comparison between the configuration of a conventional IBS and a BS used in the present invention.
2 is a block diagram schematically showing a configuration of a system for predicting a restart voltage of a vehicle according to an embodiment of the present invention.
3 is a flowchart illustrating a method for predicting a restarting voltage of a vehicle according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise. Also, the terms " part, "" module," and " module ", etc. in the specification mean a unit for processing at least one function or operation and may be implemented by hardware or software or a combination of hardware and software have.

Now, a system for predicting a restart voltage of a vehicle and a method thereof according to an embodiment of the present invention will be described in detail with reference to the drawings.

1 shows a comparison between the configuration of a conventional IBS and a BS used in the present invention.

An idle stop & go (ISG) system according to an embodiment of the present invention is a system for instantaneously restarting the engine when the vehicle is stopped and the engine is stopped and the brake pedal is released or the accelerator pedal is depressed. The ISG system has a fuel economy improvement effect that can reduce energy waste due to idling occurring in the signal waiting state when the vehicle is running in the city center.

In order to operate the ISG system, the condition of the vehicle is important. However, it is very important to accurately monitor the state of the battery, and the IBS (Intelligent Battery Sensor) is generally responsible for the monitoring.

Referring to FIG. 1 (A), IBS is connected to a negative terminal of a battery and has a built-in high-precision microcomputer and a high-resolution analog digital converter (ADC).

Therefore, the IBS measures the voltage, current, and temperature of the battery, estimates the battery remaining capacity (SOC), the battery health state (SOH), and the battery starting probability (SOF) To the ECU.

In particular, the IBS uses a shunt method in current measurement and can measure the current during cranking, but it has a disadvantage that the cost of the vehicle is increased due to expensive parts.

1B, in the system for predicting the restart voltage of a vehicle according to an embodiment of the present invention, a battery sensor BS is connected to a negative terminal, . The BS then delivers the measured current and temperature to the BS-ECU in analog form (eg, voltage).

The BS-ECU calculates an algorithm capable of estimating the battery state as in the IBS.

However, in the BS-ECU structure according to the embodiment of the present invention, there is a restriction that measurement is possible only in a limited current range. Specifically, in the BS-ECU structure, since the algorithm must be operated in some time tasks (for example, 10 ms tasks) of ECUs used in the past, the sampling time for sensor measurement is relatively long and the instantaneous current at the time of cranking is measured can not do it.

Therefore, in the present invention, in order to overcome the above-mentioned constraint, the cost for applying the ISG system is suppressed through the technology for determining the engine cranking possibility (SOF) after the idle stop of the ISG system in the BS-ECU system structure This paper proposes a system and method for estimating the restarting voltage of an economical battery sensor based vehicle.

2 is a block diagram schematically showing a configuration of a system for predicting a restart voltage of a vehicle according to an embodiment of the present invention.

Referring to FIG. 2, a system for predicting a vehicle restart voltage 100 according to an embodiment of the present invention is a system that can replace an IBS used for implementing an ISG system in a BS-ECU system structure of a vehicle. 110, a battery sensor unit 120, an ECU (Electronic Control Unit) 130, and an engine unit 140.

The battery 110 is a secondary battery capable of charging and discharging, and supplies power to the vehicle load. The battery 110 supplies power for initial engine start of the vehicle and power for restarting the engine according to the ISG function.

The battery sensor 120 is fixedly connected to the negative terminal of the battery as shown in FIG. 1B to measure the current of the battery 110 by the Hole-IC, and the temperature of the battery 110 And transmits it to the ECU 130 as an analog type.

The ECU 130 measures the voltage of the battery 110 directly and stores the voltage of the measured battery 110 and the current and temperature of the battery 110 received from the battery sensor unit 120. [

The ECU 130 measures the voltage and current that reflect the charge / discharge characteristics of the battery 110 for a predetermined period of time or a predetermined number of times using the battery sensor unit 120, which is measured only in a limited current range. The internal resistance Rm of the battery 110 using the linear regression method.

The ECU 130 calculates the cranking current Ic through the required power Pc and the voltage at the engine cranking by the test data.

The battery voltage drop ΔV at the time of engine cranking is calculated through the correlation k between the internal resistance Rm based on the battery state measurement and the internal resistance Rc at the time of cranking, .

The ECU 130 can estimate the battery minimum voltage (SOF) at the time of engine restart after the idle stop by referring to the voltage before cranking determined through the test.

On the other hand, in order to accurately estimate the SOF of the ECU 130, the estimation of the remaining capacity SOC of the battery due to the change in the external environment (e.g., temperature) must be accurate. This is because the accuracy of the SOC is reflected in the accuracy of the open-circuit voltage (OCV) through the SOC.

Since the SOF estimation should be applied not only to the new battery but also to the aged battery, the correlation between the internal resistance Rm based on the battery state measurement defined by the test and the internal resistance Rc at the time of cranking, k ) Can be determined by referring to data from engine cranking test by temperature, SOC, and aging degree of battery.

Also, in order to estimate the battery low voltage (SOF) in accurate cranking, the ECU 130 previously determines the value at the OCV according to the actually measured voltage and the SOC in the selection of the battery voltage just before cranking .

In addition, when the vehicle meets a predetermined stop condition, the ECU 130 generates an idle stop signal to stop the engine 140. When the engine 130 senses the user's intention to travel after the engine 140 is stopped, A signal can be generated and restarted.

Referring to FIG. 3, a method for predicting a restart voltage based on the configuration of a vehicle restart voltage predicting system according to an embodiment of the present invention will be described with reference to the ECU 130 as a main body.

3 is a flowchart illustrating a method for predicting a restarting voltage of a vehicle according to an embodiment of the present invention.

Referring to FIG. 3, the ECU 130 periodically measures and stores the voltage and current that reflect the charging and discharging characteristics of the battery (S10). At this time, the ECU 130 can collect the measured battery current using the battery sensor unit 120, and directly measure the battery voltage.

The ECU 130 repeats until the number of data of the obtained voltage and current of the battery exceeds the predetermined reference number n determined by the test (S20: NO) (S20; YES), the internal resistance Rm_x by the linear regression analysis of the statistical method is calculated using n voltages and currents (S30).

Then, the ECU 130 calculates a moving average Rm of the m internal resistances determined through the test (S40)

The ECU 130 calculates the cranking current Ic from the required power Pc and the voltage Vc at the time of cranking by the test data (Ic = Pc / Vc) The cranking internal resistance Rc is calculated from the variation value? Vc and the calculated cranking current Ic (Rc =? Vc / Ic) (S50).

ECU 130 estimates a correlation (k) between the moving average (Rm) of the m internal resistances and the cranking internal resistance (Rc) which have been established in advance through the test (Rc = k * Rm) (ΔV = Ic * Rc = Ic * k * Rm) (S60) by applying a correlation between the moving average Rm of the resistance and the cranking internal resistance Rc, .

ECU 130 selects the voltage before cranking determined by the test (V = V_m or V_ocv) and calculates the lowest voltage SOF of the battery at the time of cranking (SOF = V -? V) (S70).

According to the embodiment of the present invention as described above, even when a current sensor with limited large-current measurement at the time of cranking is used, or when voltage and current at a very short time cranked by the controller can not be measured, It is possible to implement the ISG system function by providing a method of estimating the battery low voltage (SOF) during the engine restart after the internal resistance Rm and idle stop based on the cranking test data base.

In addition, it is possible to reduce the cost of building the ISG system and the production cost of the vehicle by eliminating the use of the high-grade IBS (Intelligent Battery Sensor) in the construction of the ISG system and providing the alternative technology.

The embodiments of the present invention are not limited to the above-described apparatuses and / or methods, but may be implemented through a program for realizing functions corresponding to the configuration of the embodiment of the present invention, a recording medium on which the program is recorded And such an embodiment can be easily implemented by those skilled in the art from the description of the embodiments described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

100: vehicle restart voltage prediction system 110: battery
120: ECU 130: battery sensor unit
140: engine section

Claims (9)

A system for estimating a restart voltage of a vehicle for an ISG (Idle Stop & Go) system of a vehicle in which voltage and current measurement at the time of engine restart without an IBS (Intelligent Battery Sensor)
A chargeable and dischargeable battery;
A battery sensor unit for measuring a current and a temperature of a limited range of the battery; And
The internal resistance of the battery using the statistical technique is measured by measuring the voltage of the current collected by the battery sensor unit and the charging / discharging characteristic of the battery during a predetermined period, and the cranking test data according to the engine and battery condition And an ECU (Electronic Control Unit) for estimating a battery minimum voltage at an engine restart after an idle stop considering a correlation between the internal resistance and an internal resistance at the time of cranking,
The ECU refers to test data defined by mapping an engine cranking test for each temperature, remaining capacity, and degree of aging of the battery in consideration of the correlation between the internal resistance and the internal resistance at the time of cranking, And estimating a rest time voltage of the vehicle based on the estimated remaining battery voltage. The method according to claim 1,
The ECU includes:
And calculates the cranking current through the required power and voltage at the time of engine cranking by the test data. 3. The method according to claim 1 or 2,
The ECU includes:
A system for estimating a restarting voltage of a vehicle that calculates an average of a plurality of internal resistances based on battery state measurement using linear regression analysis. delete The method according to claim 1,
The ECU includes:
The voltage of the battery immediately before the cranking determined by the test is referred to, and when the engine is restarted after the idle stop,
Wherein the voltage immediately before cranking is selected from one of an actually measured voltage or an open circuit voltage (OCV) value according to a remaining capacity (SOC) of the battery. A method for predicting a restart voltage of a vehicle for an ISG (Idle Stop & Go) system of a vehicle in which voltage and current measurement at the time of engine restart without an IBS (Intelligent Battery Sensor)
a) measuring and storing a voltage and a limited range current reflecting the charge and discharge characteristics of the battery;
b) calculating the internal resistance of the battery using the statistical technique if the stored voltage and current exceeds a predetermined reference number;
c) estimating a battery drop voltage at the time of engine cranking through correlation between the internal resistance and internal resistance at the time of cranking with reference to cranking test data according to the engine and battery condition; And
d) estimating a battery minimum voltage upon engine restart after an idle stop with reference to a voltage just before cranking determined through testing,
In the step c), when considering the correlation between the internal resistance and the internal resistance at the time of cranking, reference is made to the test data defined by mapping through the engine cranking test according to the temperature of the battery, the remaining capacity, and the degree of aging And estimating the battery's lowest voltage when the engine is restarted. The method according to claim 6,
The step b)
Calculating an internal resistance by linear regression analysis using the reference number of voltages and currents and calculating a moving average of a plurality of internal resistances determined through testing. The method according to claim 6,
Between the steps b) and c)
Calculating a cranking current from the required power and voltage at the time of cranking by the test data; And
And calculating the internal resistance at the time of cranking from the voltage fluctuation value at the time of cranking by the test data and the cranking current calculated. The method according to claim 6,
The step d)
Selecting one of an actual measured voltage of the battery or an open circuit voltage (OCV) value according to a remaining capacity (SOC) of the battery as a voltage immediately before the cranking.

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