JP2020124033A - Charge control device - Google Patents

Abstract

To provide a charge control device which performs appropriate charging control on individual chargers even in a case where the chargers have variations in performance.SOLUTION: An ECU 10 transmits a command value I* for a charging current which is requested from a charger 3 connected to a battery 11 for a vehicle. The ECU 10 executes a process which makes the command value I* fluctuate after a start of charging and measures a reaction time TR, which is a time difference from the fluctuation of an output Id of the charger 3 in response to the fluctuation of the command value I*, and a process which sets the command value I* on the basis of an upper limit charging amount Win defined by a state of the battery 11 and a margin M from the upper limit charging amount Win defined by the reaction time TR.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a charging control device, and more particularly to a charging control device that controls charging of a power storage device mounted on a vehicle.

International Publication No. 2010/089843 (Patent Document 1) discloses a vehicle charging system including a charging control device that generates a power command value for a charger and controls the charger.

International Publication No. 2010/089843 JP, 2016-021805, A

Some charging standards do not determine the response speed of a charger that charges a vehicle power storage device. Therefore, the response speed of the charger varies depending on the charging stand.

In this case, the charging control device is designed with a margin for the charging current limit value based on the charger with the slowest response speed so that the power storage device can be appropriately charged even if the charger with a slow response speed is used. It is possible to do it. However, if such a configuration is used uniformly, the time required for charging becomes long when a charger having a fast response speed is used, and the convenience for quick charging deteriorates.

The charging control device of the present disclosure is to solve the above-described problems, and an object thereof is to provide a charging control device that performs appropriate charging control for each charger even when there are variations in the performance of the charger. Is to provide.

The present disclosure relates to a charging control device that transmits a command value of a charging current requested to a charger connected to a power storage device for a vehicle. The charging control device varies the command value after the start of charging, measures the time difference with the output fluctuation of the charger in response to the fluctuation of the command value, the upper limit charge amount determined by the state of the power storage device, and the time difference. And a margin from the upper limit charge amount that is set, the processing for setting the command value is executed.

With the above configuration, the charging control device detects the control delay of the charger with respect to the command value of the charging current and calculates the margin according to the amount. With this configuration, when the battery of the vehicle is charged by the quick charging stand, the command value can be calculated while ensuring a margin that prevents the battery from being overcharged by any of the quick charging stands.

According to the charge control device of the present disclosure, it is possible to obtain the convenience of charging the battery as quickly as possible while protecting the battery even when the performance of the charger varies.

It is a figure which shows roughly the whole structure of the charging system which concerns on this Embodiment. It is a figure which shows the structure of a charging system in detail. 5 is a flowchart for explaining charge control executed by the charge control device according to the present embodiment. 4 is a diagram showing changes in a charging current command value I* and an actual charging current Ib when the control of FIG. 3 is executed. FIG. It is a wave form diagram for explaining the modification of charge control.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and the description thereof will not be repeated.

<Structure of charging system>
FIG. 1 is a diagram schematically showing the overall configuration of the charging system according to the present embodiment. Referring to FIG. 1, charging system 9 includes a vehicle 1 of a certain user, charger 3, and charging cable 4 extending from charger 3.

The vehicle 1 is, for example, an electric vehicle equipped with a battery 11 (see FIG. 2). The vehicle 1 is configured to be capable of “external charging” for charging the battery 11 with the electric power supplied from the charger 3 in a state where the vehicle 1 and the charger 3 are electrically connected by the charging cable 4. .. The vehicle 1 may be a plug-in hybrid vehicle or a fuel cell vehicle as long as it can be externally charged.

The charger 3 is installed in, for example, a public charging stand (also called a charging spot or a charging station). Charger 3 converts an AC power source (for example, a 3-phase 200V power source) supplied from a commercial power source into DC power, and supplies the DC power to vehicle 1.

In the present embodiment, charger 3 is a charger compatible with quick charging. However, it is assumed that the charger 3 has characteristics that are not specified in the charging standard for quick charging, for example, that the response speed of the output power with respect to the power command value varies.

FIG. 2 is a diagram showing the configuration of the charging system 9 in more detail. 1 and 2, a vehicle 1 includes a battery 11, a monitoring unit 111, a system main relay (SMR) 121, a power control unit (PCU) 122, and a motor. A generator (MG) 123, a power transmission gear 124, a drive wheel 125, and an ECU (Electronic Control Unit) 10 are provided.

The battery 11 is a rechargeable power storage device and is configured to include a secondary battery such as a lithium ion secondary battery or a nickel hydrogen battery. Battery 11 supplies electric power for generating the driving force for driving vehicle 1 to PCU 122. Further, the battery 11 is charged with electric power generated by the regenerative braking of the motor generator 123 or charged with electric power supplied from the charger 3. It should be noted that instead of the battery 11, a capacitor such as an electric double layer capacitor may be adopted.

The monitoring unit 111 monitors the state of the battery 11. Although not shown in the drawings, the monitoring unit 111 includes a voltage sensor, a current sensor, and a temperature sensor. The voltage sensor detects the voltage Vb of the battery 11. The current sensor detects the current Ib input to and output from the battery 11. The temperature sensor detects the temperature of the battery 11. Each sensor outputs the detection result to the ECU 10. The ECU 10 can calculate the SOC (State Of Charge) of the battery 11 based on the detection result of each sensor.

The SMR 121 is electrically connected between the battery 11 and the PCU 122. The closing/opening of the SMR 121 is controlled according to a command from the ECU 10.

The PCU 122 is an electric power conversion device that converts electric power between the battery 11 and the motor generator 123 according to a command from the ECU 10. The PCU 122 includes an inverter that receives electric power from the battery 11 to drive the motor generator 123, a converter (not shown) that adjusts the level of the DC voltage supplied to the inverter, and the like.

The motor generator 123 is an AC electric motor. Motor generator 123 is driven by an inverter included in PCU 122 to rotate the drive shaft. The torque output from the motor generator 123 is transmitted to the drive wheels 125 via the power transmission gear 124, whereby the vehicle 1 travels. Further, the motor generator 123 receives the rotational force of the drive wheels 125 to generate power when the vehicle is braked. The electric power generated by the motor generator 123 charges the battery 11 through the PCU 122.

Vehicle 1 further includes a charging relay 131, power lines PL and GL, and an inlet 135 as a configuration for quick charging.

The charger 3 includes a control device 30 and a power supply unit 31. The charging cable includes a power line 42, a communication line 43, and a connector 41.

When the battery 11 is rapidly charged, the connector 41 of the charging cable 4 is connected to the inlet 135. Then, the electric power from the charger 3 is supplied to the vehicle 1 through the electric power line 42 in the charging cable 4 and transmitted to the charging relay 131 through the electric power lines PL and GL.

The charging relay 131 and the SMR 121 are electrically connected between the battery 11 and the inlet 135. When the charging relay 131 is closed and the SMR 121 is closed, electric power can be transferred between the inlet 135 and the battery 11.

The ECU 10 is connected to a navigation system 14 and the like by a wired vehicle-mounted network 16 such as a CAN (Controller Area Network), and is configured to be able to communicate with each other. Further, in the state where the vehicle 1 and the charger 3 are connected by the charging cable 4, the ECU 10 can perform bidirectional communication with the control device 30 of the charger 3 via the communication line 43 in the charging cable 4 and the in-vehicle network 16. Configured to be possible.

The navigation system 14 includes a GPS receiver 141 that identifies the current location of the vehicle 1 based on radio waves from artificial satellites. The navigation system 14 acquires position information (GPS information) of the current position of the vehicle 1 by the GPS receiver 141, and uses the acquired position information to execute various navigation processes of the vehicle 1.

The navigation system 14 further includes a display with a touch panel (hereinafter, also referred to as “navi screen”) 142. The navigation screen 142 receives various operations by the user. In addition, the navigation screen 142 displays the current location of the vehicle 1 by superimposing it on a road map or displaying information from the ECU 10. The navigation screen 142 is configured to be able to provide the user of the vehicle 1 with information regarding quick charging.

The ECU 10 includes a CPU (Central Processing Unit) 101, a memory 102, an input/output port (not shown) for inputting/outputting various signals, and the like. The ECU 10 controls each device (SMR 121, PCU 122, charging relay 131, etc.) in the vehicle 1 so that the vehicle 1 is in a desired state. The ECU 10 corresponds to the “charge control device” according to the present disclosure.

<Charging standard>
In rapid charging, a charging standard (new standard) different from conventional charging (so-called normal charging) is adopted. As one of such standards, there is one that is specified so that the command value of the charging current requested from the vehicle side is transmitted to the charger 3 and the charger 3 outputs the requested electric power.

However, the response speed from when the charger 3 receives the command value until it outputs the current corresponding to the command value may not be specified. Therefore, the response speed of the charger 3 varies depending on the manufacturer of the charging stand.

In this case, the ECU 10 uses the charger having the slowest response speed as a reference so that the battery 11 can be appropriately charged even if the charger 3 having a slow response speed is used, and the ECU 10 has a margin for the current determined from the limit value Win of the charging power. It is conceivable that a command value of the charging current is set by providing the above. However, if such a configuration is used uniformly, the time required for charging becomes long when a charger having a fast response speed is used, and the convenience for quick charging deteriorates. In such a case, it is desirable to improve the convenience of the user who uses quick charging.

Therefore, in the present embodiment, the ECU 10 sets the response speed of the charger 3 at the initial stage of charging so that appropriate charging control can be performed for each charger even when the performance of the charger varies. And the command value of the charging current is determined based on the measurement result. More specifically, the ECU 10 transmits the command value I* of the required charging current to the charger 3 connected to the vehicle battery 11. The ECU 10 changes the command value I* after the start of charging, measures the reaction time TR which is the time difference from the change in the charging current Ib from the charger 3 in response to the change in the command value I*, and the battery 11 The command value I* is set based on the upper limit charge amount Win determined by the state and the margin M from the current value (I(Win)=Win/Vb) corresponding to the upper limit charge amount Win determined by the reaction time TR. And the processing to be performed.

<Explanation of charge control>
FIG. 3 is a flowchart for explaining the charging control executed by the charging control device according to the present embodiment. FIG. 4 is a diagram showing changes in the command value I* of the charging current and the actual charging current Ib when the control of FIG. 3 is executed. In FIG. 4, the vertical axis represents current and the horizontal axis represents time. With respect to the current, the charging current is downward and the discharging current is upward from zero.

First, in step S1, charging is started. Then, in step S2, the ECU 10 gradually changes the command value I* of the charging current from 0 to the steady value I0 within a range not exceeding the charging limit value Win (time t1 to t2 in FIG. 4). The charger 3 changes the charging current Ib transmitted to the vehicle so as to follow the command value I*. However, since the response speed is not zero, the charging current Ib changes slightly after the command value I*. At this time, the ECU 10 does not yet know what kind of response speed the charger 3 is connected to.

Subsequently, the ECU 10 changes the command value from the steady value I0 to I1 by changing the charging current by several amperes. Then, in step S4, the reaction time TR up to the actual charging current Ib obtained from the detected value of the current sensor measuring the charging current from the change in the command value I* of the charging current is calculated. In order to improve the accuracy, the ECU 10 executes a check N times (N is a natural number) for obtaining the reaction time TR which is the difference between the timings of the change of the command value I* and the change of the charging current Ib. In step S5, the ECU 10 repeats the processes of step S3 and step S4 until the check is completed N times. At times t3 to t4 in FIG. 4, a case where N=3 is shown.

When the check is completed N times (YES in S5), the ECU 10 determines the overcharge prevention margin M in step S6. The ECU 10 sets the worst value of the reaction times TR1 to TR3 measured a plurality of times as the reaction time TR. Then, the ECU 10 sets the margin M by the following equation.
M=TR×ΔWin/Vb
Here, ΔWin (kW/sec) indicates the amount of change per hour of the charging limit value Win for the battery 11, which is calculated by the well-known method by the ECU 10, and Vb indicates the voltage of the battery 11 at that time. Show. The charge limit value Win is calculated based on, for example, the battery voltage, the SOC, the battery deterioration degree, the temperature, and the like.

After the overcharge prevention margin M is calculated in step S6, thereafter, the command value I* of the charging current in which the margin M is taken into consideration with respect to the charging limit value Win is determined. For example, the command value I* can be set based on the following equation.
I*=Win/Vb-M
In FIG. 4, at time t4, charging of the battery 11 progresses, and control is performed to reduce the charging current in accordance with the SOC reaching a certain value.

When the response speed of the charger 3 is slow, the margin M is set to a large value. Therefore, when Win approaches zero, the command value I* of the charging current is further restricted from the current value corresponding to Win. Therefore, it takes a long time to finish charging. On the other hand, when the response speed of the charger 3 is fast, the margin M is set small, so that the command value I* of the charging current is not so limited from the current value corresponding to Win. Therefore, the time until the end of charging is shortened. In this way, since the charging control that matches the characteristics of the charger 3 is executed, the charging time when using a charger with good performance is shortened.

FIG. 5 is a waveform diagram for explaining a modification of charging control. In the example shown in FIG. 5, the response performance of the stand is tested from the charging start time t1. For example, when the command value I* is increased at the time t1, the reaction time TR11 until the charging current Ib starts to change is measured following the increase. At times t11 to t12, the command value I* is changed stepwise, and the reaction time is measured a plurality of times for each change, and the worst value may be set as the reaction time TR. The test may be performed at any time without being limited to the charging start time.

Further, in addition to the reaction time TR of the charger 3, the time from the change of the current to the stabilization, that is, the time constant τ determined by the charging cable, the battery, and the like is taken into consideration, and the margin M is set to correspond to TR+τ. Is also good. When the margin M is determined and SOC increases and Win is further limited at t13, the command value I* is set in consideration of the margin M and Win.

As other parameters, in addition to the reaction time TR and the time constant τ, the overshoot amount of the output current may be considered in the setting of the margin M or the command value I*. For example, in the case of a charger with a large amount of current overshoot, it is possible to make the change in the command value I* small.

Further, the specifications of the response performance of the quick charging stand are collected as market information by using a DCM (Data Communication Module) or the like, and the charger 3 arranged in the stand is obtained from CAN communication with the stand or position information of the stand by GPS. The model M may be indexed and the margin M corresponding to the indexed model may be set.

As described above, the charging control device according to the present embodiment is configured to detect the control delay of the charger with respect to the command value I* of the charging current and calculate the margin M according to the amount. With this configuration, when the battery of the vehicle is charged by the quick charging stand, the command value I* can be calculated while ensuring a margin M that does not cause overcharging of the battery at any quick charging stand.

According to the charge control device of the present embodiment, by setting the margin M according to each charger, it is convenient to charge the battery as quickly as possible while protecting the battery even when there are variations in the performance of the charger. You can get sex.

The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

1 vehicle, 3 charger, 4 charging cable, 9 charging system, 10 ECU, 11 battery, 14 navigation system, 16 vehicle network, 30 control device, 31 power supply unit, 41 connector, 42, GL, PL power line, 43 communication Lines, 102 memory, 111 monitoring unit, 121 SMR, 122 PCU, 123 motor generator, 124 power transmission gear, 125 drive wheels, 131 charging relay, 135 inlet, 141 receiver, 142 navigation screen.

Claims (1)

A charging control device for transmitting a command value of a charging current required for a charger connected to a power storage device for a vehicle,
A process of changing the command value after the start of charging, and measuring a time difference from the output fluctuation of the charger in response to the fluctuation of the command value,
A charge control device that executes a process of setting the command value using an upper limit charge amount determined by the state of the power storage device and a margin from the upper limit charge amount determined by the time difference.

Images