KR20110114024A - Method for charging and discharging of battery using electric vehicle - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a charging and discharging method of a battery of an electric vehicle, and more particularly to a charging and discharging method of a battery of an electric vehicle for controlling charging and discharging of a battery will be. A method for charging a battery of an electric vehicle according to the present invention includes the steps of: a charging unit receiving input of a charging rate unit and a chargeable time for charging an electric vehicle; Determining a charge power for each time period for charging the battery based on the charge rate per unit time and the chargeable time; And controlling charging of the battery using the charging power for each time period.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of charging and discharging a battery of an electric vehicle,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a charging and discharging method of a battery of an electric vehicle, and more particularly to a charging and discharging method of a battery of an electric vehicle for controlling charging and discharging of a battery will be.

Various eco-friendly technologies that reduce pollution emissions in recent years have been applied to the automobile industry, and technologies for using various eco-friendly materials such as electricity or solar heat instead of conventional petroleum-based materials such as gasoline and diesel have been developed as automobile fuel.

As a result, hybrid cars or electric vehicles using electricity and gasoline or light oil at the same time have been developed and produced.

Recently, many methods for increasing the charging efficiency of a battery used in such a hybrid vehicle or an electric vehicle have been proposed.

FIG. 1 illustrates a charging system of an electric vehicle according to the related art. In the conventional charger 1, the output is controlled by the rated voltage and the current, thereby causing the following problems. For example, assume that the actual output of a rated 400V 100A machine is capable of output control to 400V 100A. At this time, if the charger 1 is charged with the output voltage of 400 V to the 380 V battery 2, the battery 2 may be overcharged. As a result, the efficiency of the battery may be reduced and the life of the battery may be shortened. In addition, there is a possibility that a battery may explode and cause a safety accident. In addition, since each battery has unique charging characteristics, optimum charging control is impossible.

Thus, the conventional charger operates in the constant voltage (CV) or constant current (CC) mode with the determined voltage and current. However, it is difficult to efficiently charge a battery pack that incorporates various capacities and a BMS (Battery Management System).

Therefore, it is urgent to develop a charger capable of recognizing BMS information in the battery pack and operating the battery pack in combination, in order to efficiently charge the currently manufactured battery pack.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems, and it is an object of the present invention to provide a battery management device (BMS) in which a charger is provided with battery rating and status information, And a method for optimizing discharge control.

It is another object of the present invention to provide a method of charging and discharging a battery of an electric vehicle that controls charging of the battery in accordance with a short-term electric short-term by using charge state information transmitted from a BMS of an electric vehicle.

A method for charging a battery of an electric vehicle according to the present invention includes the steps of: a charging unit receiving input of a charging rate unit and a chargeable time for charging an electric vehicle; Determining a charging power for each time period for charging the battery on the basis of the charging rate unit and the charging time for each time period; And controlling charging of the battery using the charging power for each time period.

Meanwhile, a method for discharging a battery of an electric vehicle according to the present invention includes the steps of: a charging unit receiving input of a discharge charge unit price and a discharge enable time of each battery for discharging battery of an electric vehicle; Determining a discharge power for each discharge time of the battery based on a discharge charge unit price and a dischargeable time of each discharge cell by time; And controlling the discharging of the battery by using the discharging power by time.

According to the present invention, the battery charger can communicate with the battery management device (BMS) located inside the battery pack to receive the battery rating and status information to more accurately charge the battery.

In addition, the present invention has an effect of optimizing the charging efficiency by controlling the charging of the battery according to the electric short-term by using the charging state information transmitted from the BMS of the electric vehicle.

1 is a diagram illustrating a conventional charging system for an electric vehicle,
2 shows a system to which the present invention is applied,
3 and 4 illustrate charge load distribution of a battery according to the present invention;

In order to fully understand the present invention and the operational advantages of the present invention and the objects achieved by the embodiments of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate embodiments of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings. Like reference symbols in the drawings denote like elements.

2 is a diagram showing a system to which the present invention is applied.

2, a system to which a battery charging and discharging method of an electric vehicle according to an embodiment of the present invention is applied includes a charger 10 and a battery 20 (battery pack).

The charger 10 includes a configuration for optimal charging and discharging control of the battery 20. [ To this end, the charger 10 communicates with the battery management device 30 (BMS) built in the battery 20 to receive battery rating and status information, and controls charging and discharging of the battery based on the information. That is, the charger 10 exchanges information with a battery management device (hereinafter collectively referred to as a BMS) included in the battery 30.

Here, the charger receives battery rating information or charge state information from the BMS 30, and controls the charging and discharging of the battery using the received information.

In the present invention, communication between the charger 10 and the BMS 30 preferably employs CAN communication. The CAN communication is a well-known technology, and a description thereof will be omitted.

The battery 20 is configured to be mounted inside the electric vehicle to supply electric power. The battery 20 takes the form of a package including the above-described battery management device 30 (BMS) and a safety circuit, that is, a battery pack. The configuration of such a battery is well-known, and a detailed description thereof will be omitted.

Hereinafter, a battery charging and discharging method of an electric vehicle according to the present invention will be described in detail using a system having the above-described configuration.

end. Safety and high efficiency charge control

First, the charger 10 is provided with battery rating information and charge status information using the CAN communication with the battery management device 30 (BMS) located inside the battery 20. The charger 10 uses this information to control the charging and discharging of the battery 20. This enables stable and optimal charge control for the battery. Thus, the charger 10 prevents safety accidents that may occur during charging of the battery, and enables charging of a higher efficiency battery.

Here, the charger 10 receives the battery rating information such as the rated voltage and the rated current from the BMS 30, and performs different voltage and current control based on the received battery rating information. Also, depending on the battery capacity, It should be possible.

The charger 10 is also provided with information on the type of battery (nickel-cadmium, nickel-hydrogen, lithium-ion, lithium polymer, etc.) mounted in the vehicle, and charge control optimized for the inherent characteristics of each battery is possible.

Also, the charger 10 receives charging status information such as battery temperature, battery SOC, and charging cable connection status from the BMS 30 during charging, and monitors the charging status information. The charger 10 senses various dangerous phenomena such as overcharging, voltage unbalance, overheating, and cable disconnection, thereby blocking charging and informing the user of the safety, thereby enabling charging of a highly efficient battery.

I. Minimize charge costs Charge control

A battery charging method of an electric vehicle according to the present invention will be described by way of example.

The charging method of a battery of an electric vehicle according to the present invention is characterized in that the charging device 10 is configured to charge the battery of the electric vehicle based on the charging rate per unit time and chargeable time Determining a charging power for each time period for charging the battery, and controlling the charging of the battery using the charging power for each time period.

First, in the battery charging method of an electric vehicle according to the present invention, the charger 10 receives the charging rate unit price (won / kWh) and the chargeable time for charging the battery of the electric vehicle. Charge rate unit price (KRW / kWh) by time of day shall be provided by the utility company. Preferably, the chargeable time includes a charge start time or a charge end time as a desired charge time period.

Here, the charging state information and the like are received by the charger 10 in communication with the battery management device 30 (BMS) of the battery 20. [ The charge state information includes information such as the final charge amount of the battery (current charge amount of the battery) and the like.

The charging state information includes battery temperature, battery SOC, charging cable connection state, and the like. In the step of controlling the charging of the battery of the present invention, it is preferable to prevent the battery from overcharging in accordance with the charging state information.

Next, a method for charging a battery of an electric vehicle according to the present invention determines a charging power for a charging time of a battery based on a charging time unit and a chargeable time by time. That is, the charger 10 communicates with the BMS and utilizes the collected information to determine the minimum cost charging load trajectory (see FIG. 3 or FIG. 4) to achieve the charging target for a given charging time.

Here, the chargeable time preferably includes a charge start time or a charge end time for the battery. Accordingly, in the present invention, it is possible to calculate the charging power for each time period for completing the charging of the battery before the end time of the charging desired by the user, and thereby to charge the battery efficiently.

The optimal control parameter of such a battery can be set as a charging current or a charging power, and it is aimed at minimizing a charging charge during charging. The charger 10 uses the values of the charging current or the charging power as a result of the optimal algorithm to power the battery.

This charging control method can be expressed as an optimal control problem, and the objective function is as follows.

식(1)

Equation (1)

는 충전전력(kW),

는 충전요금 단가(원/kWh),

는 시간간격, k는 충전되는 동안의 시간 단계로서 1부터 시작된다. K는 충전되는 동안의 시간 단계의 최종단계,

는 목적함수이다.
In the above equation (1)

Is the charging power (kW),

Is the charge price (KRW / kWh),

Is the time interval, and k is the time step during which it is being charged. K is the final step of the time step during charging,

Is an objective function.

The method for charging a battery of an electric vehicle according to the present invention further includes receiving minimum and maximum charging power for each time slot. Accordingly, the step of determining the charging power for each of the time zones determines the charging power for each of the time zones for charging the battery based on the charging rate and the charging rate per time zone within the range between the minimum and maximum charging powers . That is, in the battery charging method of the electric vehicle according to the present invention, the following constraints are satisfied including the minimum and maximum charging power for each time slot.

식(2)

Equation (2)

식(3)

Equation (3)

식(4)

Equation (4)

는 k시간 단계에서 전기자동차 배터리의 충전량으로서, 배터리 저장용량으로 나누어 준 값으로 0부터 1까지의 값을 갖는다.In the above equation

Is a charge amount of the electric automobile battery at the k-th time step, and is a value divided by the battery storage capacity and has a value from 0 to 1.

는 충전 초기 즉 k=1에서의 SOC값,

는 충전종료시점 즉, k=K에서의 SOC값,

는 배터리의 최소로 충전 가능한 SOC로서 통상 0.1 내지 0.2를 사용하고,

는 배터리의 최대로 충전 가능한 SOC로서 0.8 내지 0.9가 사용이 된다.

는 k시간 단계에서의 충전전류,

는 k시간 단계에서 배터리가 받아들일 수 있는 최대 전류값을 나타낸다.

Is the SOC value at the beginning of the charge, that is, k = 1,

The SOC value at k = K,

Lt; RTI ID = 0.0 > SOC < / RTI > as the minimum chargeable SOC of the battery,

Is 0.8 to 0.9 as the maximum chargeable SOC of the battery.

Is the charge current at the k time step,

Represents the maximum current value that the battery can accept at time k.

The method for charging a battery of an electric vehicle according to the present invention controls the charging of the battery using charging power for each time period. That is, the charger 10 controls the charging of the battery with the charging current or the charging voltage with time according to the charging locus determined as described above.

The battery charging method of the electric vehicle according to the present invention can be divided into the following steps.

S1: The charger 10 receives the charging rate per unit time, charging time desired by the user, and charging end condition information desired by the user. At this time, the charger 10 collects status information about the battery through communication with the battery BMS.

와 사용자가 원하는 종료조건의

를 산출한다.S2: Current battery

And the end condition desired by the user

.

S3: Calculate the optimum charging load path during the charging period by using the objective function and the constraint condition for optimization, using information such as the maximum charge current according to the SOC.

S4: The optimum charging load result is calculated by converting the charging current using the battery voltage information according to the SOC of the battery.

S5: The charging current or the charging power information according to the elapsed time of the charger is used to supply the charging current value to the battery.

S6: The charger finishes charging at the end of charging.

FIG. 3 and FIG. 4 are views illustrating a charge load distribution of a battery according to the present invention.

A comparative example of the battery charging control according to the present invention will be described.

Referring to FIG. 3, it is assumed that the charge rate is 200 won / kWh for 0-1 hour, 300 won / kWh for 1-2 hour, and 100 won / kWh for 2-3 hours. And the charger will charge the battery for about 2 hours under a constant charge load condition, and the last one hour will show the charge control termination by lowering the charge load.

Referring to FIG. 4, it is assumed that the charge rate is 200 won / kWh for 0-1 hour, 300 won / kWh for 1-2 hour, and 100 won / kWh for 2-3 hours. The charger shows charge control to lower the charge load at the highest charge time and to maintain a higher charge load at other times. That is, this shows the case where the same amount of charge, that is, 7 kWh, is charged at the same time illustrated in FIG.

The charging charge for these two cases is 1,600 won for the case of FIG. 3, and 1,200 won for the case of FIG. 4, which can reduce the charge charge by 25%. Accordingly, it can be seen that the charging method of the battery of the electric vehicle according to the present invention enables efficient charging by controlling the charging power at the time of charging the battery.

All. Maximize Discharge Profit Discharge Control

The battery discharging method of the electric vehicle according to the present invention will be described in more detail. In the description, the description of the configuration overlapping with the battery charging method of the electric vehicle described above will be omitted.

The battery discharging method of an electric vehicle according to the present invention is characterized in that the charger 10 receives a discharge charge unit price and a dischargeable time by time for battery discharge of an electric vehicle, Determining a discharge power by time for discharging the battery; And controlling the discharging of the battery using the discharging electric power by the time unit.

The battery discharging method of an electric vehicle according to the present invention can reverse-transfer electric energy stored in an electric vehicle battery to a power system.

First, in the battery discharge method of the electric vehicle according to the present invention, the charger 10 receives the discharge charge unit price and the dischargeable time by time for battery discharge of the electric vehicle. It is assumed that the unit price of the discharge rate by the time zone can be provided from the electric power company.

The power charge rate unit price information and the discharge enable time for each time slot are inputted in the same manner as the battery charging method described above. The discharge possible time preferably includes a discharge start time or a discharge end time as a desired discharge time period.

Here, the charging status information and the like are received by the charger 10 in communication with the battery management device (BMS) of the battery. The charge state information includes information such as the final charge amount of the battery (current charge amount of the battery) and the like.

The charging status information includes battery temperature, battery SOC, and charging cable connection status, and it is preferable to prevent overcharging of the battery in accordance with the charging status information in the step of controlling charging of the battery.

Next, a battery discharge method of an electric vehicle according to the present invention determines a discharge power for a discharge time of a battery based on a time-based discharge charge unit price and a dischargeable time. That is, the charger 10 communicates with the BMS 30 within the battery 20 and utilizes the collected information to determine the discharge load trajectory of the maximum revenue to achieve the discharge target for a given discharge time.

Here, the dischargeable time preferably includes a discharge start time or a discharge end time for the battery. Accordingly, in the present invention, it is possible to calculate the discharge power by time unit for completing the discharge of the battery before the discharge end time desired by the user, and thereby to discharge the battery efficiently.

According to the determined discharge locus, the charger changes the discharge current signal according to time to control the discharge of the battery. Here, if it is a charger, it is possible to employ a separate DC charger and an on-board charger.

The optimal control parameter of such a battery can be set as a discharging current or a discharging power and aims at maximizing a discharging charge during discharging. The charger 10 discharges electric power from the battery by using the values of the discharge current or discharge electric power resulting from the optimal algorithm.

This optimal control method can be expressed as a charge optimal control problem during discharge. The objective function to be minimized is as follows. Since the minus sign must maximize the revenue from the discharge, it has been minus to apply the minimization algorithm.

식(5)

Equation (5)

는 방전전력(kW),

는 방전요금단가(원/kWh),

는 시간간격, k는 방전되는 동안의 시간단계로서 1부터 시작된다. K는 방전되는 동안의 시간 단계의 최종단계,

는 목적함수이다.
In the above equation (5)

Is the discharge power (kW),

Is the discharge charge unit price (KRW / kWh),

Is the time interval, k is the time step during discharging and starts at 1. K is the final stage of the time step during discharging,

Is an objective function.

Further, the battery discharge method of an electric vehicle according to the present invention further includes a step of receiving the minimum and maximum discharge electric power by time. Accordingly, the step of determining the discharge power for each of the time periods may include determining a discharge power for each discharge time of the battery on the basis of the discharge charge unit price and the dischargeable time per time zone within the range between the minimum and maximum discharge powers . That is, in the battery discharge method of the electric vehicle according to the present invention, the following constraints are satisfied including the minimum and maximum discharge power for each time period.

식(6)

Equation (6)

식(7)

Equation (7)

식(8)

Equation (8)

는 k시간 단계에서 전기자동차 배터리의 충전량으로서, 배터리 저장용량으로 나누어 준 값으로 0부터 1까지의 값을 갖는다. In the above equation

Is a charge amount of the electric automobile battery at the k-th time step, and is a value divided by the battery storage capacity and has a value from 0 to 1.

는 방전 초기 즉 k=1에서의 SOC값,

는 방전종료시점 즉, k=K에서의 SOC값,

는 배터리의 최소로 방전 가능한 SOC로서 통상 0.1 내지 0.2를 사용하고,

는 배터리의 최대로 방전 가능한 SOC로서 0.8 내지 0.9가 사용이 된다.

는 k시간 단계에서의 배터리로부터의 방전전류,

는 k시간 단계에서의 배터리로부터 방출 가능한 최대 전류값을 나타낸다.

The SOC value at the beginning of the discharge, that is, k = 1,

Is the SOC value at the end of discharge, that is, k = K,

Is a minimum dischargeable SOC of the battery, typically 0.1 to 0.2,

Is a SOC capable of discharging the battery to the maximum of 0.8 to 0.9.

Is the discharge current from the battery at k time step,

Represents the maximum current value that can be discharged from the battery at k time step.

The method for charging a battery of an electric vehicle according to the present invention controls the discharge of the battery using a discharge power according to time. That is, the charger controls the discharging of the battery with the discharging current or the discharging voltage with time according to the discharge locus determined as described above.

The battery discharge method of the electric vehicle according to the present invention can be divided into the following steps.

S11: The charger 10 receives the discharge rate unit price by time, discharge time desired by the user, and discharge end condition information desired by the user. At this time, the charger 10 collects status information about the battery through communication with the battery BMS.

와 사용자가 원하는 종료조건의

를 산출한다.S12: Current battery

And the end condition desired by the user

.

S13: The optimum discharge load path is calculated during the discharge period by using the objective function and the constraint condition for optimization by using the information such as the maximum discharge current according to the SOC.

S14: The optimum discharge load result is calculated by converting the discharge current using the battery voltage information according to the battery SOC.

S15: The charger discharges from the battery to the power system using the discharging current information or the discharging power information according to the derived time.

S16: The charger terminates the discharge at the end of the discharge.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. will be. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

10: Charger 20: Battery
30: Battery management device (BMS)

Claims (14)

Receiving a charging rate unit charge amount and a chargeable time period for charging the battery of the electric vehicle;
Determining a charging power for each time slot for charging the battery on the basis of the charging rate per unit time and the charging time; And
And controlling charging of the battery using the charging power for each time period. The method according to claim 1,
Further comprising the step of receiving the minimum and maximum charge power for each time period,
The step of determining the charging power for each time period includes:
And determining a charging power for each of the time zones for charging the battery based on the charging rate unit and the charging time for each of the time zones within a range between the minimum and maximum charging power for each of the time zones . The method according to claim 1,
Wherein the step of receiving the chargeable time comprises:
Wherein the charger communicates with a battery management device (BMS) of the battery to receive charging state information of the battery. The method of claim 3,
The charge state information may include:
Battery temperature, battery SOC, and charging cable connection status,
The step of controlling the charging of the battery includes:
And charging the battery in accordance with the charging state information. The method according to claim 1,
The chargeable time may be,
And a charging end time for the battery. The method according to claim 1,
Wherein the charging power for each time period is calculated by calculating a minimum sum value during a chargeable time of [(charging power) x (charging fee unit) x (time interval)]. The method of claim 6,
Wherein the charging power includes minimum and maximum charging power,
The charging power for each time-
Wherein the power consumption is calculated within a range between the minimum and maximum charging power. Receiving a discharge charge unit price and a dischargeable time by a charger for a battery discharge of an electric vehicle at a time;
Determining a discharge power for each discharge time of the battery on the basis of the discharge charge unit price and the dischargeable time by the time; And
And controlling the discharging of the battery using the discharging power for each time period. The method of claim 8,
Further comprising the step of receiving the minimum and maximum discharge power for each time period,
The step of determining the discharge power for each time-
Wherein the discharge power for the battery is determined based on the discharge charge unit price for the time period and the dischargeable time within a range between the minimum and maximum discharge power for each time period. The method of claim 8,
Wherein the step of receiving the discharge enable time comprises:
Wherein the charger communicates with a battery management device (BMS) of the battery to receive charging state information of the battery. The method of claim 10,
The charge state information may include:
Battery temperature, battery SOC, and charging cable connection status,
The step of controlling the discharging of the battery includes:
And discharging the battery in accordance with the charging status information to prevent over discharge of the battery. The method of claim 8,
The dischargeable time may be,
And a discharge end time for the battery. The method of claim 8,
Wherein the discharge power by time is calculated by calculating a minimum sum value during a dischargeable time of [(discharge power) x (discharge charge unit price) x (time interval)]. 14. The method of claim 13,
Wherein the discharge power includes minimum and maximum discharge power,
The discharge power for each time period
And the maximum discharge power is calculated within a range between the minimum and maximum discharge powers.

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