KR20190110190A - Minimum Re-start Voltage Presumption Method of Battery for Automotive Vehicles - Google Patents

Abstract

The present invention relates to a method for predicting a starting minimum voltage of a battery when a vehicle engine is restarted, which is capable of accurately predicting a starting minimum voltage. The method of the present invention comprises the steps of: sampling current of a battery per second; calculating voltage at an instant of sampling the current; predicting an internal resistance of the battery; calculating a starting minimum voltage; and continuously updating the starting minimum voltage.

Description

Minimum Re-start Voltage Presumption Method of Battery for Automotive Vehicles}

The present invention relates to a method for predicting the lowest starting voltage of a battery when the vehicle engine is restarted. More specifically, the voltage and the battery temperature of the unloaded state in the vehicle starting with the ISG (Idle Stop & G0) system are initially loaded. The recorded table predicts the minimum starting voltage, and from the next start onwards, the previous starting voltage is continuously updated in the table so that the battery minimum voltage at restart can be accurately predicted. The present invention relates to a method for predicting the minimum starting voltage of a battery when the vehicle engine is restarted so that the starting can not be turned off.

Recently, an idle stop-and-go system (hereinafter, referred to as an 'ISG system') is applied to a vehicle to reduce waste of energy due to engine idling.

The ISG system stops the engine when the vehicle stops and restarts the engine when the driver's willingness to drive is detected or when the engine must be restarted.

In other words, if the vehicle is stopped for traffic signals or other reasons, the start-up is automatically turned off when the requirements of the ISG function are met, and the start-up is automatically taken when certain conditions are met.

The driver's willingness to drive can be ascertained by detecting the driver's releasing the brake or depressing the accelerator pedal.

Since the ISG system stops the engine when the vehicle is stopped, it is possible to reduce unnecessary fuel consumption, reduce the generation of exhaust gas by idling, and improve fuel economy.

In order to apply the ISG system, it is necessary to accurately grasp the state of the battery, and a battery sensor (BS) is used to constantly monitor the state of the battery.

The battery sensor may be classified into an analog battery sensor and an intelligent battery sensor (IBS), and IBS is used for an ISG system.

The battery sensor is mounted on a battery of the vehicle to collect battery voltage, battery current, temperature information of the battery negative terminal, and through this state-of-charge (SOC), state-of-health (SOH) and SOF (state) -of-Function).

In addition, the battery sensor predicts the lowest voltage of the battery required for restarting the engine and provides information to the electronic control unit (ECU).

Accordingly, it is determined whether to stop the engine when the vehicle stops while driving.

However, the conventional method of predicting the lowest voltage at engine restart has a problem that it is difficult to determine the correct starting minimum voltage.

The performance of the battery of the vehicle deteriorates with time, and the temperature of the battery changes due to the change in gravity density of the electrolyte and the heat transfer and heat dissipation during charging and discharging. Does not continuously reflect changes in performance and temperature.

Accordingly, even when the voltage of the battery becomes lower than or equal to the minimum voltage required for restarting due to the temperature change of the battery, there is a problem that the starting is controlled to be turned off when the vehicle is stopped.

Meanwhile, as a result of searching the prior art related to the present invention, a number of patent documents have been searched and some of them are introduced as follows.

Patent document 1 relates to a method of predicting a functional state of a car battery using a battery sensor. The SOF is obtained by using an internal resistance of a battery estimated in real time by applying an RLS technique that can estimate the internal resistance of a battery online. Calculating a load resistance by measuring a battery voltage and a current at start-up to predict the value, so that the ISG system operates smoothly; Estimating an internal resistance of the battery by measuring a battery voltage and a current while driving and applying the same to an RLS technique; Obtaining an expected current by dividing the open voltage (OCV) of the battery by the sum of the load resistance and the internal battery resistance; Calculating a battery lowest voltage at restart using the SOF prediction equation.

In addition, Patent Document 2 relates to "method and apparatus for estimating SOF of a battery sensor", the apparatus for predicting the lowest voltage of the battery, the step of calculating the previous internal resistance of the vehicle, the expected previous internal resistance and the calculated previous internal Comparing the magnitude of the resistance, updating the first aging coefficient of the vehicle with the second aging coefficient according to the comparison result, estimating the current internal resistance of the vehicle based on the second aging coefficient, and According to the step of estimating the lowest voltage using the predicted voltage of the battery.

In addition, Patent Document 3 relates to a "vehicle restart voltage prediction system and method thereof", comprising: a battery capable of charging and discharging; A battery sensor unit measuring current and temperature of the battery; And calculating an internal resistance of the battery using a statistical technique by measuring a voltage reflecting the current collected from the battery sensor unit and a charge / discharge characteristic of the battery for a predetermined period, and cranking test data according to engine and battery conditions. An electronic control unit (ECU) for estimating a battery's lowest voltage at engine restart after an idle stop considering the correlation between the internal resistance and the internal resistance during cranking is included.

KR 10-2017-0052936 A KR 10-2015-0040599 A KR 10-2014-0123838 A

The present invention is to solve the above-mentioned problems of the prior art, by estimating the battery's minimum voltage at restart in the ISG system provided in the vehicle, by calculating the lowest voltage in consideration of the current temperature of the battery, the lowest voltage at restart The purpose is to make it possible to accurately predict.

Another object of the present invention is to enable the ISG system to operate smoothly by accurately predicting the lowest voltage in consideration of the current temperature of the battery at restart.

Still another object of the present invention is to prevent the engine from turning off when the vehicle stops temporarily when the voltage of the battery becomes lower than or equal to the minimum voltage at restart.

)을 계산하는 단계(S20); (c) 상기 S20 단계에서 계산된 순간전압(

)을 현재의 전류로 나눈 값으로 배터리의 내부저항(

)을 예측하는 단계(S30); (d) 시동 최저전압(

)을 계산하는 단계(S40); (e) BMS(Battery Management System) 내부 메모리에 저장된 테이블에, 상기 S40 단계에서 구해진 시동 최저전압을 갱신하는 단계(S50)을 포함하는 것을 특징으로 한다.In order to achieve the above object, the present invention, in the vehicle ISG (Idle Stop & Go) system, a method for predicting the starting voltage of the battery when restarting the vehicle engine, (a) of the battery per second Sampling a current (S10); (b) the voltage at the instant of sampling the current in step S10 (

Calculating (S20); (c) the instantaneous voltage calculated in step S20 (

) Divided by the current to determine the battery's internal resistance (

Predicting (S30); (d) starting minimum voltage

Calculating (S40); (e) updating the starting minimum voltage obtained in the step S40 to the table stored in the battery management system (BMS) internal memory (S50).

In addition, in step S10, the sensor is mounted on the battery pole (Pole), characterized in that the sampling of the current per second.

)은, 공장 출고 직후의 배터리 방전전압(Vccv)에서 현재의 배터리 방전전압(V_now)을 빼서 계산하는 것을 특징으로 한다.In addition, in the step S20, the voltage at the instant of sampling the current (

) Is calculated by subtracting the current battery discharge voltage V _now from the battery discharge voltage Vccv immediately after factory shipment.

)은 상기 S20 단계에서 구해진 순간전압(

)을 현재의 배터리 방전전류(I_now)로 나누어 계산하는 것을 특징으로 한다. In addition, in step S30, the internal resistance of the battery (

) Is the instantaneous voltage (

) Is calculated by dividing by the current battery discharge current (I _now ).

In the step S50, interpolation of the starting minimum voltage obtained in the step S40 is applied to a value corresponding to the temperature in the table, and a deviation value δ for SOC (State of Charge) is applied.

In addition, the starting minimum voltage at the first start is estimated by a table that records OCV (Open Circuit Voltage) and BTM (Battery Temperature Modeling), and the minimum voltage at restart is a table in which the last starting voltage was continuously updated. It is characterized by predicting.

According to the present invention, the ISG system provided in the vehicle has an effect of accurately predicting the starting minimum voltage at the time of restarting.

In addition, it is possible to accurately predict the starting voltage in consideration of the current temperature of the battery when the engine restarts, so that the ISG system can operate smoothly.

In addition, when the voltage of the battery is predicted to be lower than the minimum voltage at the restart, the ISG system is not operated when the vehicle is temporarily stopped, thereby preventing the engine from turning off.

In addition, since the exact state of the battery can be grasped in advance, there is an effect that can extend the life of the battery.

1 is a view showing a concept of a starting minimum voltage.
2 is a flowchart illustrating a method for predicting a starting minimum voltage of a battery according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

)을 계산하는 단계(S20); (c) 상기 S20 단계에서 계산된 순간전압(

)을 현재의 전류로 나눈 값으로 배터리의 내부저항(

)을 예측하는 단계(S30); (d) 부하가 없는 현재의 전압값(OCV_TIME)에서, 배터리의 내부저항(R_BATT)과 현재의 온도에 대한 전류(I_{CRNK _Ad})를 곱한 값을 빼서 시동 최저전압(

)을 계산하는 단계(S40); (e) BMS(Battery Management System) 내부 메모리에 저장된 테이블에, 상기 S40 단계에서 구해진 시동 최저전압을 갱신하는 단계(S50)을 포함하여 이루어진다.As shown in FIG. 2, in the ISG system provided in a vehicle, a minimum starting voltage of a battery when the vehicle engine is restarted is illustrated in FIG. 2. In the method for predicting, (a) sampling the current of the battery per second (S10); (b) the voltage at the instant of sampling the current in step S10 (

Calculating (S20); (c) the instantaneous voltage calculated in step S20 (

) Divided by the current to determine the battery's internal resistance (

Predicting (S30); (d) From the current voltage value (OCV _TIME ) without load, subtract the product of the battery's internal resistance (R _BATT ) and the current (I _{CRNK _Ad} ) for the current temperature to obtain the minimum starting voltage (

Calculating (S40); (e) updating the starting minimum voltage obtained in step S40 to the table stored in the battery management system (BMS) internal memory (S50).

In step S40, V _CRANK Is starting voltage, OCV _TIME Is the current voltage value without load, R _BATT Is the internal resistance of the battery, I _{CRNK _Ad} is Indicates the current value for the current temperature.

That is, in the present invention, the present voltage value without a load is subtracted from the product of the battery's internal resistance and the current temperature, and is predicted as the starting minimum voltage.

In addition, in the step S10, it is preferable to mount a sensor on a battery pole provided on the outside of the battery to sample the current per second.

)은, 공장 출고 직후의 배터리 방전전압(Vccv)에서 현재의 배터리 방전전압(V_now)을 빼서 계산한다.In the step S20, the voltage at the instant of sampling the current (

) Is calculated by subtracting the current battery discharge voltage V _now from the battery discharge voltage Vccv immediately after factory shipment.

)은, 전류를 샘플링하는 순간의 전압(

)을 현재의 배터리 방전전류(I_now)로 나누어 계산한다.In addition, in step S30, the internal resistance of the battery (

Is the voltage at the moment of sampling the current (

) Is calculated by dividing by the current battery discharge current (I _now ).

Further, in step S50, the starting minimum voltage obtained in step S40 is interpolated to a value corresponding to the temperature in the table, and a deviation value δ for SOC (State of Charge) is applied.

In addition, the starting minimum voltage at the first start is predicted by a table in which OCV (Open Circuit Voltage) and Battery Temperature Modeling (BTM) are recorded, and the minimum voltage prediction at restart is predicted by a table updated by interpolation. .

That is, according to the present invention, the starting voltage at restart is continuously updated in the table, and the updated starting voltages are predicted by interpolating the updated values.

Hereinafter, a method of updating table data stored in a BMS memory will be described with reference to Table 1 below.

Table showing Battery Temperature Modeling (BMT) and Starting Low Voltage (V_CRNK) Table BTM vs V_ CRNK  ⇒ Example X X X X1 = 8 ℃ X2 = 22 ℃ X X X X X X Q11 ← 10.2V Q21 ← 10.9V X X X BTM ℃ -30 -20 -10 0 10
X_10 20
X_20 30 40 50 60 Add ℃ Ad10 Ad20 V_ CRNK  V 8 9 9.5 10 10.5 10.7 11 11.3 11.6 11.9

Determination of the starting minimum voltage (V_CRNK) from the table above, starting from the point at which the current occurs below -120A to the first charging mode (+ 1A or more), the highest cranking current point is set to the starting minimum voltage (V_CRNK). ) Value.

In the above example, when a BTM table value exists between X1 and X2, Ad10 and Ad20 are calculated by the following equation.

According to the above equation, when X1 is 8 ° C and the starting minimum voltage is 10.2V, the starting minimum voltage recorded in the BMT 10 ° C column according to the above formula is 10.5V.

In addition, when X2 is 22 ° C and the starting minimum voltage is 10.9V, the starting minimum voltage recorded in the BMT 20 ° C column according to the above formula is 10.7V.

If there is no BTM table value between X1 and X2, check the interpolation by reverse until there is at least one other X section, and then start the minimum voltage corresponding to Ad_BTM by the following equation. The SOC (State of Charge) factor value δ is applied to V_CRNK.

V_ CRNK _10 = Ad_10 / δ

V_ CRNK _20 = Ad_20 / δ

For example, as shown in the following Table 2, a constant factor value δ may be applied corresponding to a state of charge (SOC) state.

Factor value (δ) for SOC

30 40 50 60 70 80 90 100 δ 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

By the above-described method, it is possible to accurately predict the starting minimum voltage by reflecting the factors according to the temperature change of the battery and the state change of the battery.

The starting minimum voltage thus obtained is transferred to the ECU and used for the application of the ISG system.

In a vehicle to which the ISG (Idle Stop & G0) system is applied, the process of stopping the driving of the engine at the stop and restarting the engine at the start is repeated repeatedly.

Therefore, it is very important to know exactly the starting voltage of the battery for restarting the engine.

On the other hand, the battery performance decreases over time, the temperature of the battery is changed from time to time due to factors such as the gravity density of the electrolyte, electrothermal and chemical heat generated during charging / discharging, external temperature.

However, the conventional starting minimum voltage prediction method does not determine the starting minimum voltage in consideration of the above factors.

Accordingly, it is pointed out that it is difficult to accurately predict the starting voltage of the battery when the engine is restarted.

In contrast, in the present invention, as shown in Table 1, the starting voltage of the battery is predicted by a table that records battery temperature modeling (BTM) and the starting minimum voltage (V_CRNK).

In addition, the minimum starting voltage is estimated in consideration of the voltage drop of the battery, and the starting minimum voltage is continuously updated in the table at each restart.

That is, the present invention predicts the minimum voltage at the time of restart in consideration of the characteristics of the battery and the temperature of the battery whose charging performance is deteriorated with time.

Accordingly, even when the battery is used for a long time, it is possible to accurately predict the minimum voltage at the restart.

This allows the ISG system to operate smoothly, and if the battery voltage is predicted to be below the minimum voltage at restart, the ISG system can be disabled when the vehicle is temporarily stopped so that the engine does not turn off when the vehicle is stopped. .

In addition, the charging performance of the battery can be grasped in advance based on the change of the battery starting minimum voltage.

Although the embodiments for illustrating the technical idea of the present invention have been described above, the present invention is not limited to the configuration and operation as described above, and the present invention without departing from the scope of the technical idea described in the claims. Those skilled in the art will appreciate that many variations and modifications to the invention are possible. Accordingly, all such suitable changes and modifications and equivalents should be considered to be within the scope of the present invention.

Claims (6)

In the ISG (Idle Stop & Go) system provided in the vehicle, a method for predicting the starting voltage of the battery upon restart of the vehicle engine,
(a) sampling the current of the battery every second (S10);
(b) the voltage at the instant of sampling the current in step S10 (

Calculating (S20);
(c) the instantaneous voltage calculated in step S20 (

) Divided by the current to determine the battery's internal resistance (

Predicting (S30);
(d) From the current voltage value (OCV _TIME ) without load, subtract the product of the battery's internal resistance (R _BATT ) and the current (I _{CRNK _Ad} ) for the current temperature to obtain the minimum starting voltage (

Calculating (S40);
(e) continuously updating the starting minimum voltage obtained in the step S40 to a table stored in a battery management system (BMS) internal memory (S50), wherein the minimum starting voltage of the battery when the vehicle engine is restarted Prediction Method. The method of claim 1,
In step S10, the sensor is mounted on the battery pole (Pole) and sampling the current per second, characterized in that for starting the minimum voltage of the battery upon restarting the vehicle engine. The method of claim 1,
In the step S20, the voltage at the instant of sampling the current (

) Is calculated by subtracting the current battery discharge voltage (V _now ) from the battery discharge voltage (Vccv) immediately after factory shipment. The method of claim 1,
In step S30, the internal resistance of the battery (

Is the voltage at the moment of sampling the current (

) Is calculated by dividing the current by the current battery discharge current (I _now ), the method for predicting the starting voltage of the battery when the engine restarts. The method of claim 1,
In the step S50, interpolation of the starting minimum voltage obtained in the step S40 to the value corresponding to the temperature in the table, and recording by applying the deviation value (δ) for the state of charge (SOC) A method for predicting the minimum starting voltage of a battery when a vehicle engine is restarted. The method of claim 5,
The starting minimum voltage at the first startup is estimated by a table in which OCV (Open Circuit Voltage) and BTM (Battery Temperature Modeling) are recorded.
The minimum voltage at the time of a subsequent restart is estimated by the table which the last starting voltage was continuously updated, The prediction method of the starting voltage of the battery at the restart of a vehicle engine.

Images