Vehicle charging system

Abstract

To solve a problem in which a newly added vehicle is not charged until at least an initial demand time is exceeded when a new charging vehicle is generated in a situation where the demand value is likely to be exceeded.SOLUTION: A vehicle charging system includes a plurality of chargers 2 for charging a vehicle 4, and a charging control unit that controls a charging current of the charger 2, the charge control unit includes a control base unit 1 that obtains received power information from a power amount 10 obtained by measuring the received power from commercial power, compares the received power information with a predetermined upper limit value, and outputs difference information, and a control slave unit 3 installed in each of the chargers 2 to individually control the charging current of the chargers 2, and on the basis of the difference information output by the control base unit 1, the control slave unit 3 controls the charging current such that the received power from the commercial power does not exceed the upper limit value, and does not starts charging of the vehicle 4 that has occurred until at least a demand time elapses when the charging vehicle 4 occurs in such a situation in which the received power exceeds the upper limit value on the basis of the difference information.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a vehicle charging system, and more particularly to a vehicle charging system that can simultaneously charge a plurality of vehicles while coping with demand control.

Background Art

[0002] As a vehicle charging system for simultaneously charging a plurality of vehicles such as EVs and PHVs, for example, there is the charging system of Patent Document 1. In Patent Document 1, control is performed by a control master unit that manages received power and a control slave unit that controls the received current for each charger, and the current supplied to the charger is controlled so that the received power does not exceed the demand value.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the vehicle charging system of Patent Document 1 above, instead of collectively controlling a plurality of chargers, the control unit provided in each charger individually controls the charging current of the charger, making it easy to cope with increases and decreases in chargers and giving the system expandability. However, if a new vehicle is connected to the charger when the received power is about to exceed the maximum demand value, charging of that vehicle is also carried out, so there is a possibility that the maximum demand value will be exceeded due to an increase in the received power.

[0005] Therefore, in view of such problems, the present invention aims to provide a vehicle charging system that does not charge a newly added charging vehicle until at least the first demand time has elapsed when a newly added charging vehicle occurs in a situation where the maximum demand value is likely to be exceeded.

Means for Solving the Problems

[0006] In order to solve the above problems, the invention according to claim 1 is a vehicle charging system having a plurality of chargers for charging a vehicle and a charging control unit for controlling the charging current of the chargers. The charging control unit obtains received power information from a watt-hour meter that measures the received power from commercial power, compares it with a predetermined upper limit value, and outputs the difference information. It has a control master unit and control slave units installed in each of the chargers to individually control the charging current of the chargers. The control slave unit controls the charging current based on the difference information output by the control master unit so that the received power from commercial power does not exceed the upper limit value. When a charging vehicle occurs in a situation where it is recognized from the difference information that the received power exceeds the upper limit value or is approximately the upper limit value, charging of the generated charging vehicle is not started until at least the first demand time has elapsed.

Effect of the Invention

[0007] According to the present invention, since the control slave unit controls so that the received power does not exceed the upper limit value, if the upper limit value is set to, for example, the maximum demand value or a power value smaller than that, demand control can be implemented even without a central control unit that controls the whole. And when a new charging vehicle occurs in a situation where the received power exceeds the upper limit value or is likely to exceed it, charging of that vehicle is not started until the first demand time has elapsed, so it can be surely controlled not to exceed the upper limit value. In addition, since the control master unit only needs to output the difference information with respect to the upper limit value of the received power, it is not necessary to change the setting of the control master unit when changing the number of installed chargers, and the increase or decrease of chargers can be easily implemented.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments embodying the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram showing an example of a vehicle charging system according to the present invention, which includes a control master unit 1 that obtains received power information of commercial power P from a smart meter (power meter) 10, and a control slave unit 3 that communicates with the control master unit 1 to control the charging current of a charger 2. It shows a state where a charging cable L1 extending from a vehicle 4 is connected to the charger 2. The control slave unit 3 is installed for each charger 2.

[0010] In addition, 5 (5a, 5b) is a step-down transformer that converts the power received at high voltage into low-voltage power, 6 is a load such as an air conditioner to which three-phase power is supplied, and 7 is a load such as lighting to which single-phase 100 / 200V is supplied. 5a is a three-phase transformer, 5b is a single-phase transformer, and it shows a configuration in which single-phase 200V power output from the single-phase transformer 5b is supplied to each charger 2.

[0011] FIG. 2 shows a block diagram of the control master unit 1. As shown in FIG. 2, the control master unit 1 includes a master unit measurement unit 11 that obtains received power information from the smart meter 10, a master unit storage unit 12 that stores upper limit values and the like, a master unit CPU 13 that controls the control master unit 1, a master unit communication unit 14 that performs wireless communication with the control slave unit 3, and the like. It is connected to the smart meter 10 via a communication line L2.

[0012] FIG. 3 shows a block diagram of the control slave unit 3. As shown in FIG. 3, the control slave unit 3 includes a slave unit communication unit 31 that performs wireless communication with the control master unit 1, a slave unit storage unit 32 that stores a threshold value of the charge amount, a duration time, a standby time, etc. to be described later, a slave unit CPU 33 that controls the control slave unit 3, a charger control unit 34 that outputs a control signal to the charger 2, and the like. It is connected to the charger 2 via a transmission line L3. Here, the threshold value is the amount of charge required for the vehicle 4 to travel a certain distance such as 50 km. Whether a fixed value is set regardless of the vehicle 4, or the charger 2 obtains electricity charge information etc. from the vehicle 4 and sets it for each vehicle 4, may be acceptable. Also, the control slave unit 3 and the charger 2 may be integrally configured.

[0013] Here, the upper limit value stored in the master unit storage unit 12 will be explained. The upper limit value is a value (power value) set to be, for example, about 10% smaller than the maximum demand value, and is set based on the following background. For the basic electricity charge, the maximum value (maximum demand value) of the demand values (the maximum value of the average power consumption per 30 minutes for one month) in the past one year (the current month and the previous 11 months) is applied. Therefore, if a demand value larger than the demand values in the previous 11 months is measured even once in a month, the basic electricity charge for the next one year will be determined based on that value. That is, in order to suppress or reduce the electricity charge, it is effective to perform control (demand control) to suppress the maximum demand value. Therefore, an upper limit value set to a value that does not exceed the maximum demand value is used. This upper limit value is set by the customer.

[0014] The charging control of the vehicle charging system configured as described above is implemented as follows. First, the control master unit 1 obtains information on the received power from the smart meter 10, and notifies each control slave unit 3 of the deviation information as the differential information at regular intervals such as every 1 second. The deviation information is information indicating what value the current received power is with respect to the upper limit value (what value the predicted value of the power amount for 30 minutes calculated from the received power is), and the control changes greatly depending on whether it is equal to or greater than the upper limit value. When the current received power is approximately the upper limit value, the master unit CPU 13 outputs information of "0" as the deviation information from the master unit communication unit 14, and when it exceeds the upper limit value, it outputs information of "plus". Further, when the upper limit value has not been reached, information of "minus" is output to each control slave unit 3. Here, the received power being approximately the upper limit value means that the received power is close to the upper limit value, for example, within a difference of 2% with respect to the upper limit value.

[0015] Each individual control slave unit 3 that has received deviation information from the control master unit 1 performs the following control. FIGS. 4 and 5 show flowcharts indicating the flow of current control performed by the slave CPU 33 of the control slave unit 3, and the description will be made with reference to this flow. This control is performed every time deviation information is received. When deviation information is received (S1), it is determined whether the charger 2 is charging or about to start charging. If charging has started, the process proceeds to S6. If a new vehicle is connected and charging is about to start (YES in S2), the count status of the demand time is determined (S3). In S3, it is determined whether the time until the demand deadline, that is, whether the demand time has elapsed, is less than a predetermined time such as 3 minutes. If it is less than the predetermined time, the process proceeds to S6. If it is more than the predetermined time, the process proceeds to S4. In S4, a determination is made by looking at the deviation information. If the deviation information is 0 or more, that is, if the received power is equal to or exceeds the upper limit value (YES in S4), the charging current of 0 amperes is continued until the demand deadline (S5). If the deviation information is negative, the process proceeds to S6.

[0016] In this way, when a new charging vehicle 4 occurs in a situation where the received power exceeds the upper limit value or is likely to exceed it, charging of the vehicle is not started until the first demand time has elapsed, so that control can be performed to surely not exceed the upper limit value.

[0017] In addition, even if the first demand time has elapsed, if the situation where the received power continues to be tight around the upper limit value continues, the state of the charging current of 0 amperes may be continuously continued. Also, the control master unit 1 manages the demand time by communicating with the smart meter 10, and that information is notified to the control slave unit 3.

[0018] In S6, the state of the charge amount is determined, and different controls are performed depending on whether the charge amount since charging started has reached the threshold value. If the charge amount has not reached the threshold value, the process proceeds to S7. If it has reached the threshold value, the process proceeds to S11. When the deviation information is negative in the state where the charging has not reached the threshold (NO in S6), that is, when the received power has not reached the upper limit value (NO in S7) and the charging current can be increased, the increased current is calculated by the following formula (Formula 1), and the charging current is increased (S10). Note that a maximum value is set for the charging current, and it will not increase further if the maximum value has been reached. Increased current = Maximum current value (A) × Charge amount (Wh) / Threshold value (Wh) ··· (Formula 1)

[0019] When the deviation information is zero, that is, when the received power is substantially at the upper limit value (YES in S8), a signal not to change the charging current is output to the charger 2 (S18) and the process ends. When the deviation information is positive, that is, when the received power exceeds the upper limit value (NO in S8) and the charging current must be controlled to decrease, the reduced current is calculated by the following formula (Formula 2), and the charging current is reduced (S9). Note that a minimum value is set for the charging current, and it will not be reduced further if the minimum value has been reached. Reduced current = Maximum current value (A) × (Threshold value (Wh) - Charge amount (Wh)) / Threshold value (Wh) ··· (Formula 2) The newly set current value is notified to the charger 2 (S18), and the charger 2 changes the charging current according to the received notification.

[0020] On the other hand, when charging has progressed beyond the threshold value at the stage of receiving the deviation information (YES in S6), the following control is performed. When the deviation information is negative, that is, when the received power has not reached the upper limit value (NO in S11), the duration stored in the slave unit storage unit 32 is read. If the duration has not reached the set standby time such as 60 seconds (NO in S12), the duration is incremented by 1 unit (the time interval for receiving the deviation information) (S14) and saved, and a signal not to change the current is output to the charger 2 (S18) and the process ends. Then, when the duration has reached the standby time (YES in S12), a signal to add the minimum increased current to the current is output to the charger 2 (S18) and the process ends.

[0021] With such control, for vehicle 4 where the charging current has reached the threshold, the increase in the charging current is stopped until the set waiting time elapses. Therefore, if there is a vehicle 4 whose charge amount has not reached the threshold, it is possible to increase the charging current using this waiting time to proceed with charging, and balanced current control can be achieved without having a control unit for collectively managing charger 2.

[0022] Also, if the deviation information is zero or positive, that is, if the received power is equal to or greater than the upper limit value (YES in S11), the following control is performed. When the deviation information is zero, that is, when the received power is approximately the upper limit value (YES in S15), the stored duration is reset (S17) to zero, and a signal not to change the current is output to charger 2 (S18) and the process ends. When the deviation information is positive, that is, when the received power exceeds the upper limit value (NO in S15), the charging current is set to zero and the stored duration is reset to 0 (S17). As a result, a signal to set the charging current to 0 is output to charger 2 and the process ends.

[0023] With this control, when the received power exceeds the upper limit value, demand control can be performed to stop the charging of vehicle 4 where charging is proceeding above the threshold regardless of the waiting time. Also, since the count of the waiting time is reset, a sufficient waiting time (duration) can be set, and during that time, the charging of vehicle 4 whose charge amount has not reached the threshold can be continued. Therefore, the distribution of the charging current can be carried out in a well-balanced manner.

[0024] And since control slave unit 3 controls so that the received power does not exceed the upper limit value, demand control can be implemented without having a central control unit for overall control. In addition, since control master unit 1 only needs to output deviation information (difference information) with respect to the upper limit value of the received power, it is not necessary to change the settings of control master unit 1 when changing the number of installed chargers 2, and it is easy to increase or decrease charger 2. Also, even if the charging current of each charger 2 is independently controlled, balanced charging can be performed for the vehicles 4 connected to the individual chargers 2. Furthermore, since the control master unit 1 and the control slave unit 3 communicate wirelessly, there is no need to arrange signal lines between them, and the constructability of the system is good.

[0025] In addition, in the above embodiment, the communication between the control master unit 1 and the control slave unit 3 is carried out wirelessly, but a wired connection may also be used.

Explanation of Signs

[0026] 1... Control master unit (charging control unit), 2... Charger, 3... Control slave unit (charging control unit), 4... Vehicle, 10... Smart meter (electric energy meter), 11... Master unit measurement unit, 14... Master unit communication unit (wireless communication unit), 12... Master unit storage unit, 31... Slave unit communication unit (wireless communication unit), 32... Slave unit storage unit.

Claims

【Claim 1】 A vehicle charging system having a plurality of chargers for charging a vehicle and a charging control unit for controlling the charging current of the chargers, wherein the charging control unit obtains received power information from a watt-hour meter that measures the received power from commercial power, compares it with a predetermined upper limit value, and outputs the difference information as a control master unit, and has control slave units installed in each of the chargers for individually controlling the charging current of the chargers, wherein the control slave unit controls the charging current so that the received power from commercial power does not exceed the upper limit value based on the difference information output by the control master unit, and when a charging vehicle occurs in a situation where it is recognized from the difference information that the received power exceeds the upper limit value or is substantially the upper limit value, charging of the generated charging vehicle is not started until at least the first demand time has elapsed. A vehicle charging system characterized by this.

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