Vehicle Charging System

Abstract

To provide a vehicle charging system capable of distributing surplus of photovoltaic generation power in addition to commercial power to vehicle charging smoothly.SOLUTION: A charging control unit has a charging control master unit 2 for controlling supply surplus of commercial power and photovoltaic generation power to a charger, and a plurality of charging control slave units 3 installed per charger and controlling current which a charger of a connection destination supplies to a vehicle. The charging control master unit 2 includes a second measuring unit 22 for monitoring surplus power of the photovoltaic generation power, a communication unit 25 for simultaneously informing surplus power information to each charging control slave unit 3 when the surplus power is generated, and a master unit CPU 26 for managing current supplied to each charger 4. When a new vehicle 5 is connected to the charger 4 during vehicle charging in the absence of the surplus power, charging current of a vehicle 5 which is being charged already is reduced by a predetermined amount, and the reduced current is supplied to the new vehicle 5.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle charging system capable of simultaneously charging multiple vehicles. [Background technology]

[0002] BACKGROUND ART There is a vehicle charging system that can charge a plurality of vehicles equipped with storage batteries, such as electric vehicles (EVs) and plug-in hybrid vehicles (PHVs). For example, in Patent Document 1, power is managed so as not to exceed the contracted power amount with the power supplier, while at the same time, in order to improve user convenience, a vehicle with a large storage capacity is charged with a relatively large current, thereby controlling the charging time so that it does not become extremely long. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-162555 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional vehicle charging system described above, priorities are set according to the vehicle's battery capacity, so that vehicles that require more charging power are given a higher priority and can be charged with a larger current. This is effective when charging multiple vehicles simultaneously, and enables efficient charging.

[0005] However, because vehicles that start charging later are charged under the same conditions as vehicles that start charging earlier, it can take a long time to reach full charge. Considering this charge amount, if the battery is charged to, say, about 20% of its capacity, it is possible to travel a certain distance, such as returning home, so it is unlikely that this will cause any disruption to driving. Therefore, even if it takes a long time to reach full charge, it would be more convenient for users if the charging time could be shortened to reach a charge level that allows the vehicle to travel a certain distance.

[0006] On the other hand, operators of charging stations equipped with solar power generation equipment are hoping to use the surplus solar power they have been selling to charge vehicles. However, when supplying surplus solar power to a vehicle charging system that simultaneously charges the storage batteries of multiple electric vehicles, it is difficult to supply it efficiently. The reason for this is that the control of allocating charging power to multiple storage batteries (vehicles) requires mutual communication with the vehicles, which takes time. This time-consuming control makes it difficult to efficiently supply the fluctuating solar power to the vehicles. Furthermore, if priority is given to surplus solar power, if a new vehicle is added when there is no surplus solar power, charging may not begin immediately.

[0007] In view of these problems, the present invention aims to provide a vehicle charging system that can prioritize the use of surplus solar-generated power in addition to commercial power for vehicle charging, thereby reducing the burden on the commercial power being received. [Means for solving the problem]

[0008] In order to solve the above problem, the invention of claim 1 is a vehicle charging system that has a plurality of chargers for charging vehicles and a charging control unit that controls the charging current of the chargers, and that charges vehicles using commercial power and solar-generated power, and the solar-generated power is supplied to a load other than the chargers, and the surplus power is Will the electricity be sold to the commercial power grid?The charging control unit is provided for vehicle charging and has a charging control master unit that controls the supply of surplus commercial power and solar-generated power to the charger, and a plurality of charging control slave units that are installed for each charger and control the current that the connected charger supplies to the vehicle. The charging control master unit has an excess power monitoring unit that monitors the surplus power of solar-generated power, and when surplus power occurs, sends a notification to each charging control slave unit. The increase in charging current based on the surplus power is recorded as surplus power information. It has a notification unit that notifies all at once and an upper limit value management unit that manages the current supplied to each charger. 、 Surplus electricity Below a specified value When a new vehicle is connected to the charger while a vehicle is being charged, the charging current of the vehicle already being charged is reduced by a certain amount and the reduced current is supplied to the new vehicle. In addition, the charge control slave device has a slave device current control section that, upon receiving a notice of surplus power information from the charge control master device, calculates an increase in the charging current by a predetermined calculation based on the charge amount relative to a threshold value that is the required charge amount set at the start of charging and the surplus power information, and performs current increase control. It is characterized by: With this configuration, surplus solar power can be diverted to vehicle charging, making effective use of solar power. Furthermore, if a new vehicle is charged when there is no surplus solar power, the current to the vehicle being charged is reduced and diverted to the new vehicle, allowing charging to begin without increasing commercial power and reducing electricity costs. Furthermore, since charging of the new vehicle begins promptly, the new charger will not be dissatisfied.

[0009] In addition, The distribution of surplus solar power generation to individual vehicles is determined by each charging control slave unit based on threshold information set at the start of charging, allowing for smooth charging control and efficient charging.

[0010] Claim 2 The invention is 1 In the configuration described above, the charge control master unit acquires information on the remaining battery capacity and power cost of the vehicle to be charged from the vehicle, calculates the amount of power that will enable the vehicle to travel a predetermined distance, and has a threshold calculation unit that sets the amount of charge required to reach the calculated amount of power as a threshold, and the upper limit value management unit calculates whether the received power is Set based on the contracted power with the power supplier The charging control parent unit manages the charging so that it does not exceed the upper limit value, sets the priority of the vehicles so that charging of vehicles that have not reached the threshold value is given priority over charging of vehicles that have reached the threshold value, and controls the current supplied to the charger so that the received power does not exceed the upper limit value. With this configuration, vehicle charging using commercial power is performed by setting a threshold for the amount of charge based on the amount of power required to travel a specified distance, regardless of the vehicle model or remaining battery charge. Charging of vehicles that have not yet reached this threshold is prioritized over charging of vehicles that have reached the threshold, shortening the time it takes to reach the threshold and improving user convenience. Furthermore, the travel distance of vehicles that have reached the threshold can be made approximately the same regardless of vehicle model, providing equal treatment to all users. Furthermore, demand control is also implemented, preventing increases in electricity rates. Incidentally, electricity consumption is the rate of electricity consumption and is expressed as the number of kilometers traveled per kWh of electricity. [Effects of the Invention]

[0011] According to the present invention, solar The system allows for effective use of solar power generation because surplus solar power is directed toward vehicle charging. Furthermore, if a new vehicle begins charging when there is no surplus solar power, the current flowing to the vehicle being charged is reduced and redirected to the new vehicle, allowing charging to begin without increasing commercial power consumption and reducing electricity costs. Furthermore, new vehicles begin charging quickly, eliminating dissatisfaction among new chargers. In addition, the distribution of surplus solar power generation to individual vehicles is determined by each charging control slave unit based on threshold information set at the start of charging, allowing for smooth charging control and efficient charging. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a configuration diagram showing an example of a vehicle charging system according to the present invention. [Figure 2] 10 is a flowchart showing a flow of threshold setting. [Figure 3] 10 is a flowchart showing a procedure for assigning priorities. [Figure 4] 10 is a flowchart showing a flow of charging control. [Figure 5] 10 is a flowchart showing a control flow of the charge control master unit when solar-generated power is used to charge a vehicle. [Figure 6] 10 is a flowchart showing a control flow of the charge control slave unit when solar-generated power is used to charge a vehicle. [Figure 7]10 is a flowchart showing a flow of charging control when a new vehicle is charged when there is no surplus solar-generated power. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments embodying the present invention will be described in detail with reference to the drawings. Fig. 1 is a block diagram showing an example of a vehicle charging system according to the present invention. In Fig. 1, 2 is a charge control master unit (hereinafter simply referred to as "master unit"), and 3 is a charge control slave unit (hereinafter simply referred to as "slave unit"), and together they form a charge control unit. A slave unit 3 is installed for each charger 4 to which a vehicle 5 is connected, and the slave unit 3 and charger 4 are connected by a signal line L1, and the master unit 2 and slave unit 3 are connected via a signal line L2, thereby communicating with each other.

[0014] On the other hand, in addition to commercial power P, solar power generation equipment 8 is connected to power receiving equipment 7, which supplies power to load 9 and charger 4. The commercial power P supplied at high voltage is converted to low voltage by power receiving equipment 7 and supplied to load 9 and charger 4 via power cables L3 and L4, respectively. The power generated by the solar power generation facility 8 is mainly supplied to the load 9, and if any surplus power is generated, it is configured to be able to flow back into the commercial power system P, but is configured to perform control to supply the amount of power to be flowed back to the charger 4 by a control to be described later. Furthermore, the parent device 2 and each child device 3 are connected by a signal line L2, but the signal line L2 may be eliminated and they may communicate with each other wirelessly.

[0015] The parent unit 2 includes a first measurement unit 21 that acquires received power information from a smart meter 10 installed on a feeder line L5 of the commercial power P, a second measurement unit 22 that detects surplus solar-generated power from the reverse flow to the commercial power grid, a memory unit 23 that stores a demand value, an upper limit value (a power value that is, for example, 10% smaller than the maximum demand value, and is a value set by the consumer to reduce the maximum demand value and thereby reduce the contract fee), threshold values, and arithmetic expressions, etc., a communication unit 25 (a first communication unit 25a, a second communication unit 25b,...an n-th communication unit 25n) that communicates with each child unit 3, a parent unit CPU 26 that determines the charging current of the charger 4 and controls each part of the parent unit 2, etc. The threshold value is the amount of charge required to enable the vehicle to travel a predetermined distance, and is calculated as described below.

[0016] In addition to the function of communicating with the sub-unit 3, the communication unit 25 has the function of communicating with the vehicle 5 connected to the charger 4 via the sub-unit 3, and under the control of the parent unit CPU 26, it is possible to obtain information from the vehicle 5 such as the remaining charge (kWh) of the storage battery installed in the vehicle 5 and the electricity consumption (number of kilometers traveled per kWh of electricity). The communication unit 25 functions to allow the master CPU 26 to calculate a threshold value based on the remaining battery charge information and electricity cost information acquired from the vehicle 5 .

[0017] The slave unit 3 includes a slave unit first communication unit 31 that communicates with the base unit 2, a slave unit second communication unit 32 that communicates with the charger 4, a slave unit memory unit 33 that stores an arithmetic formula for calculating the increase in charging current, and a slave unit CPU 34 that controls the connected charger 4 and also controls the slave unit 3. The slave CPU 34 receives the surplus power information of the solar power generation notified from the master unit 2 and controls the charging current of the charger 4. It also transmits to the master unit 2 information on the amount of charge supplied to the vehicle by the charger 4 (obtained from the charging current and charging time).

[0018] The vehicle charging system configured as above operates as follows: Fig. 2 is a flowchart of threshold setting, and the operation will be described with reference to Fig. 2. The parent unit CPU 26 acquires the remaining battery charge and power consumption information from the vehicle 5 via the child unit 3 and the charger 4 (S11), calculates the amount of power required to travel a specified distance based on the acquired information, and calculates the required amount of charge based on the remaining battery charge information (S12). The amount of charge required to enable travelling a predetermined distance is calculated using the following formula: Required charging amount (kWh) = specified driving distance (km) / electricity cost (km / kWh) - remaining battery capacity (kWh) (Equation 1)

[0019] The threshold value is the amount of charge required to travel a predetermined distance regardless of the vehicle type, and the required amount of charge calculated in this manner is set as the threshold value (S13). The predetermined distance is set to a distance (for example, 50 km) that can be traveled to home or the next charging station.

[0020] Once the threshold value is set, charging priorities are assigned, and then charging control is performed for each vehicle 5. The priorities are assigned as follows. 3 is a flowchart showing the flow of assigning priorities, which will be described with reference to FIG. 3. When a vehicle 5 is connected to the charger 4 (the charging plug of the vehicle 5 is connected) and a threshold is set, the master CPU 26 starts charging. At the same time, a priority is assigned to the vehicle 5 together with other vehicles 5 that are already undergoing charging control.

[0021] First, the number of vehicles 5 whose charge amount is less than the threshold (unachieved number: n) is determined (S21), and then the number of vehicles 5 whose charge amount is equal to or greater than the threshold (achieved number: m) is determined (S22). The master CPU 26 obtains and grasps information on the amount of charge since the start of charging of each vehicle 5 from the slave 3, and compares this value with a threshold value to make a judgment.

[0022] Next, the vehicles 5 included in the unachieved number n are arranged in descending order of the amount of charge, and are ranked from 1st to nth and allocated (S23), and further the vehicles 5 included in the achieved number m are arranged in descending order of the amount of charge, and are ranked from n+1th to n+mth and allocated (S24). In this way, the vehicles are ranked from 1st to n+mth. At this time, among the 1st to nth vehicles 5, the 1st vehicle 5 has the most charged amount and the nth vehicle 5 has the least charged amount, and among the n+1st to n+mth vehicles 5, the n+1st vehicle 5 has the most charged amount and the n+mth vehicle 5 has the least charged amount. After prioritizing the vehicles in this way, the process proceeds to control the increase / decrease of the current.

[0023] 4 shows a flowchart illustrating the flow of control for increasing or decreasing the current for each ordered vehicle 5, and the charging control will be described with reference to this flow. This control is also performed by the base unit 2, and the control changes significantly depending on whether the current received power is in relation to the upper limit value described above.

[0024] In the following description, it is assumed that the upper limit value is used as the criterion for judging deviation information. First, when receiving the priority allocation (S31) information, if the deviation information is equal to 0 (proceed to the left in S32), that is, if the current received power is approximately equal to the upper limit value, the charging current of any vehicle 5 is not changed and the process ends, and the process returns to the first step, S31, where priority allocation is performed. Note that the current received power is the value of the received power that the first measurement unit 21 obtains from the smart meter 10. The deviation information is a value defined as in the following equation 2. Deviation information (kW) = Current received power (kW) - Upper limit (kW) (Equation 2)

[0025] Next, if the deviation information is a positive value (proceeding downward in S32), that is, if the received power exceeds the upper limit, control is implemented to reduce the current. More precisely, if the average power for 30 minutes is calculated and predicted from the current received power, and it is determined that the upper limit may be exceeded, control is implemented to reduce the current. Specifically, the excess current value (deviation value) is calculated using the following equation 3 (S33), and the charging current reduction control (S34) is performed in order from the vehicle 5 that has reached the threshold and has the least amount of charge. Deviation value = deviation information (kW) / voltage (V) (Equation 3)

[0026] However, the maximum reduction amount per vehicle is set to the smaller of the current current value minus a predetermined minimum current value or the calculated deviation value (S35). For example, if the deviation value is 10 amperes and the current current value minus the predetermined minimum current value is 5 amperes, 5 amperes is selected, and control is implemented to reduce the charging current of the (n+m)th vehicle 5, which has the highest charge amount, by 5 amperes. In this way, the vehicle 5 with the lowest charge amount among those that have reached the threshold is given the highest priority for charging current reduction. In other words, it has the lowest charging priority. The minimum current value is the minimum value of the charging current set when charging a vehicle, and charging is set so that charging will not occur below this minimum current value.

[0027] Then, the current value obtained by subtracting the reduced current value from the deviation value is set as the new deviation value (S36), and steps S34 to S37 are repeated for all vehicles 5 to be charged until the deviation value becomes 0 or until the control is performed for the vehicles in the set order. In this way, the newly set charging current value is notified to each charger 4 from the communication unit 25 via the slave unit 3 (S43), and the control from S31 to S43 is repeatedly performed at a predetermined time interval, such as one second. As a result, when the received power from the commercial power source P is reduced, the charging current is reduced starting from the vehicle 5 that has reached the threshold value. At that time, the charging current is reduced starting from the vehicle 5 with the least amount of charge. Therefore, the amount of charge of a vehicle 5 that starts charging later does not exceed the amount of charge of a vehicle 5 that starts charging earlier, and users who take long charging times will not be dissatisfied.

[0028] On the other hand, if the deviation information is negative, that is, if the received power does not reach the upper limit value, control is performed to increase the charging current. Specifically, the current value that can be increased (margin value) is calculated using the following equation 4 (S38), and the charging current is increased in order from the vehicle 5 with the most charged capacity to the vehicle 5 with the least charged capacity among the vehicles 5 that do not meet the threshold (S39). Margin value = - deviation information (kW) / voltage (V) (Equation 4)

[0029] However, the maximum increase per vehicle is set to the smaller of either the value obtained by subtracting the current current value from the predetermined maximum charging current value or the calculated margin value (S40). For example, if the value obtained by subtracting the current current value from the maximum charging current value is 5 amperes and the margin value is 10 amperes, 5 amperes is selected and control is implemented to increase the charging current of the first vehicle 5 with the highest charge amount by 5 amperes. In this way, the vehicle 5 with the highest charge amount among the vehicles 5 that have not reached the threshold is given top priority for increasing the charging current, and the current is increased. The maximum charging current value is a current value that is set in advance to implement stable charging control.

[0030] Then, the current value obtained by subtracting the increased current value from the margin value is set as the new margin value (S41), and steps S39 to S42 are repeated for all vehicles 5 to be charged until the margin value becomes 0 or until the margin value becomes 0, and control is performed for the vehicles in the set order. In this way, the newly set charging current value is notified to each charger 4 (S43), and charging is controlled.

[0031] Furthermore, when the received power from the commercial power P is reduced, the charging current is reduced from the vehicle 5 whose threshold value has been reached, and when the received power from the commercial power P is increased, the charging current is increased from the vehicle 5 whose charge amount is below the threshold value.

[0032] Next, a description will be given of vehicle charging control in the case where surplus solar-generated power occurs while the vehicle is being charged using commercial power. Figure 5 is a flowchart showing the control flow of the parent unit 2 when solar-generated power is used to charge a vehicle, and Figure 6 is a flowchart showing the control flow of the child unit 3 when solar-generated power is used to charge a vehicle. We will explain this with reference to these flows. The second measurement unit 22 detects reverse power flow to the commercial power grid, i.e., power sale (S51), and when power sale occurs (Yes in S52), the parent unit CPU 26 acquires the power sale current value from the second measurement unit 22 (S52) and calculates the increase in charging current to the vehicle 5 to treat this power sale current as surplus and reduce it to zero (S53). This increase in charging current is calculated using the following equation (5). Current increase value = (power selling current value / system margin) / number of operating chargers (Equation 5) The calculated current increase value is notified simultaneously to all of the slave units 3 that are in operation (S54). The current increase value is notified at regular time intervals, and if no power is sold, "0" is notified (S55).

[0033] The system margin is an adjustment value when there are points to be considered depending on the system, and while "1" is theoretically desirable, it is set to, for example, 0.8 depending on the system installation environment. Information on the number of chargers 4 in operation is obtained from the slave unit 3. The power supplied from the power receiving equipment 7 to the chargers 4 is AC power with a constant voltage such as 200V, and the current increase value is also a power increase value of the same proportion.

[0034] Meanwhile, each slave unit 3 receives a notification of a current increase value from the base unit 2 (S61), and the slave unit CPU 33 performs the following control. If the increase value is not 0, the slave unit 3 calculates the allocation amount for the charger 4 it is responsible for (connected to the slave unit 3) (Yes in S62). The charging current after control, including the allocation amount, is calculated using the following equation 6 based on the notified current increase value (S63). If the notified current increase value is 0, there is no increase in charging current (No in S62). Charging current after control (A) = Charging current value before control (A) + Increase in charging current × (1 + (Charging amount (Wh) / Threshold (Wh))) × Coefficient (Equation 6)

[0035] The "coefficient" is a coefficient for calculating the minimum current increase value for the charging current, regardless of the charging priority, and is, for example, 0.5, and the "threshold" is obtained from the parent device 2. The "charge amount" is the amount of charging power up to the present calculated by the child device 3 from the charging current and charging time of the charger 4, as described above, and if the result of "charge amount / threshold" is greater than 1, it is set to 0 and the priority is lowered. The slave device 3 controls the charger 4 so that charging is performed at the current value calculated in this way (S64).

[0036] Next, vehicle charging control in the case where there is no surplus solar-generated power when a new vehicle needs to be charged will be described. Fig. 7 is a flowchart showing the control flow of the base unit 2, and the description will be made with reference to this flow. When n vehicles 5 being charged have not yet reached the threshold and a new vehicle (n+1th vehicle) is connected to the charger 4 (S71), this vehicle is given a provisional priority of n+1th, and charging control is started under the control of the parent CPU 26. At this time, if the surplus solar power generation is greater than the minimum current (YES in S72), the surplus current is supplied to the new vehicle and charging control is terminated, but if the surplus solar power generation is equal to or less than the minimum current, charging control is performed as follows.

[0037] First, the charging current of the vehicle 5 with the nth priority is checked (S74). If the charging current of this vehicle 5 is greater than the minimum current (YES in S75) and is at least twice the minimum current value (YES in S76), the minimum current value is subtracted from the charging current of this vehicle 5 and this is set as the charging current of the new vehicle (n+1th vehicle) 5 (S77). If the current does not exceed twice the minimum current value, the charging current of the vehicle 5 with the next highest priority (n-1) is checked. Then, the same determination / control as for the nth vehicle is performed to ensure the charging current (S75 to S79). If the charging current cannot be secured, this control is repeated up to the vehicle 5 with the first priority (S80). During this time, if the charging current can be secured from the charging current of the vehicle 5 with the first priority (YES in S80 and S81), charging of the new vehicle 5 begins (S82). If the charging current still cannot be secured, the charging current is not supplied to the new vehicle 5, and the system enters a standby state until the charging current can be secured (S83). Furthermore, after the standby state, once the charging current is secured, a threshold is set for the new vehicle 5 as described above, and a formal priority is assigned, and charging control continues to be carried out in the same way as for other vehicles 5.

[0038] In this way, surplus solar power can be diverted to vehicle charging, making effective use of solar power. If a new vehicle 5 is charged when there is no surplus solar power, the current to the vehicle 5 being charged is reduced and diverted to the new vehicle 5, allowing charging to begin without increasing commercial power and reducing electricity charges. Furthermore, charging of the new vehicle 5 begins promptly, so the new charger will not be dissatisfied. In addition, the distribution of surplus solar power generation to each vehicle 5 is determined by each charging control slave 3 based on threshold information set at the start of charging, allowing for smooth charging control and efficient charging. Furthermore, when charging vehicles using commercial power, a threshold for the amount of charge is set based on the amount of power required to travel a specified distance, regardless of the vehicle type or the remaining battery charge of the vehicle 5. Charging of vehicles that have not yet reached this threshold is prioritized over charging of vehicles that have reached the threshold, shortening the time it takes to reach the threshold and providing greater convenience for users. Furthermore, the travel distance of vehicles 5 whose charge amount has reached the threshold can be made roughly the same regardless of the vehicle type, providing equal treatment to all users. Furthermore, demand control is also implemented, preventing increases in electricity rates.

[0039] In the above embodiment, the threshold value is set by calculating the driving distance of the vehicle 5, but it may also be set uniformly at a certain percentage, such as 20%, of the capacity of the storage battery installed in the vehicle 5, or at a certain charging capacity. [Explanation of symbols]

[0040] 1··Vehicle charging system, 2··Charging control parent unit (charging control unit), 3··Charging control child unit (charging control unit), 4··Charger, 5··Vehicle, 7··Power receiving equipment, 8··Photovoltaic power generation equipment, 9··Load, 10··Smart meter, 10··Smart meter (energy meter), 21··First measurement unit, 22··Second measurement unit (surplus power monitoring unit), 23··Memory unit, 25··Communication unit (charging vehicle information acquisition unit, notification unit), 26··Parent unit CPU (upper limit value management unit, threshold calculation unit), 33··Child unit CPU (child unit current control unit), P··Commercial power.

Claims

1. A vehicle charging system having a plurality of chargers for charging vehicles and a charging control unit that controls charging currents of the chargers, and that charges vehicles using commercial power and solar-generated power, The solar-generated power is supplied to a load different from the charger, and surplus power is sold to a commercial power grid or provided for vehicle charging; The charging control unit includes a charging control master unit that controls the supply of surplus commercial power and solar power to the charger; a plurality of charge control slave units provided for each of the chargers, each of which controls a current supplied to a vehicle by the charger to which it is connected; The charge control master unit has an excess power monitoring unit that monitors the excess power of the photovoltaic power generation. a notification unit that, when the surplus power occurs, notifies all the charge control slave devices of an increase in charging current based on the surplus power as surplus power information; an upper limit value management unit that manages the current supplied to each charger; When a new vehicle is connected to the charger while the surplus power is below a predetermined value, the charging current of the vehicle already being charged is reduced by a certain amount, and the reduced current is supplied to the new vehicle; The vehicle charging system is characterized in that the charging control slave device, upon receiving the surplus power information from the charging control master device, calculates the increase in charging current by a predetermined calculation based on the charge amount relative to a threshold, which is the required charge amount set at the start of charging, and the surplus power information, and has a slave device current control unit that performs current increase control.

2. The charge control master unit has a threshold calculation unit that acquires information on the remaining battery charge and power cost of the vehicle to be charged from the vehicle, calculates the amount of power required to travel a predetermined distance, and sets the amount of charge required to reach the calculated amount of power as the threshold; the upper limit value management unit manages the received power so that it does not exceed an upper limit value set based on a contract power with an electric power supply company, 2. The vehicle charging system according to claim 1, wherein the charging control master unit sets a priority of the vehicles so that charging of vehicles that have not reached the threshold is given priority over charging of vehicles that have reached the threshold, and controls the current supplied to the charger so that the received power does not exceed the upper limit value.

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