Vehicle Charging System

Abstract

To effectively perform vehicle charging by monitoring a current flowing through a main breaker of a distribution board, in addition to execution of demand control and monitoring of a transformer current.SOLUTION: A vehicle charging system has a plurality of chargers 2 for charging a vehicle 4, and a charging control part 3 for controlling a charging current of the chargers 2. The charging control part 3 has a first measurement part 31a for acquiring current value information of received power from a smart meter 10 for measuring received high-voltage power, a second measurement part 31b for acquiring current value information of a transformer 5b for converting the received high-voltage power into low-voltage power to be supplied to the chargers 2, and a third measurement part 31c for acquiring information of a current value flowing through a main breaker 11 of a distribution board for supplying power to the chargers 2, and performs control so that a received current value acquired by the first measurement part 31a does not exceed a predetermined first setting value, a current value acquired by the second measurement part 31b does not exceeds a predetermined second setting value, and further a current value acquired by the third measurement part 31c does not exceeds a predetermined third setting value.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 supporting demand control. [Background technology]

[0002] An example of a vehicle charging system that simultaneously charges multiple vehicles equipped with storage batteries, such as EVs and PHVs, is the charging system disclosed in Patent Document 1. In Patent Document 1, the current of a transformer is monitored in addition to the received power, and demand control is performed while controlling vehicle charging so that the transformer constituting the power receiving equipment does not become overloaded, thereby enabling effective vehicle charging. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-188669 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology in Patent Document 1 above was able to prevent transformer overload while implementing demand control. However, because it did not monitor the current flowing through the distribution board that supplies power to the charger that charges the vehicle, if the main breaker in the distribution board trips due to an overcurrent, vehicle charging also stops. This caused a problem where vehicle charging would stop even if the incoming power and transformer were managed.

[0005] Let's explain the demand value here. The maximum value (maximum demand value) of the demand values ​​(maximum value of average power usage every 30 minutes for one month) for the past year (the current month and the previous 11 months) is applied to the basic electricity charge. Therefore, if a demand value greater than the demand value for the past 11 months is measured even once in a month, the basic electricity charge for the following year will be determined based on that value. In other words, controlling the maximum demand value (demand control) is an effective way to reduce electricity charges.

[0006] In view of these problems, the present invention aims to provide a vehicle charging system that can effectively charge vehicles by not only implementing demand control and monitoring transformer current, but also monitoring the current flowing through the main breaker of the distribution board. [Means for solving the problem]

[0007] In order to solve the above problem, the invention of claim 1 is a vehicle charging system having a plurality of chargers for charging vehicles and a charging control unit that controls the charging current of the chargers, wherein the charging control unit has a first measurement unit that obtains current value information of received power from a watt-hour meter that measures the received high-voltage power, a second measurement unit that obtains current value information of a transformer that converts the received high-voltage power to low-voltage power and supplies it to the chargers, and a third measurement unit that obtains current value information flowing to a main breaker of a distribution board that supplies power to the chargers, and controls the received current value so that the received current value obtained by the first measurement unit does not exceed a predetermined first set value, so that the current value obtained by the second measurement unit does not exceed a predetermined second set value, and so that the current value obtained by the third measurement unit does not exceed a predetermined third set value. In addition, the charging control section is formed separately into a first control master unit having a first measurement unit and outputting difference information of the receiving current relative to the first set value, a second control master unit having a second measurement unit and outputting difference information of the transformer current relative to the second set value, a third control master unit having a third measurement unit and outputting difference information of the main breaker current relative to the third set value, and a control slave unit installed for each charger and controlling the charging current based on the information output by the first control master unit, the second control master unit and the third control master unit, and the control slave unit calculates the receiving current value based on the difference information transmitted from the first control master unit, the second control master unit and the third control master unit. The control unit controls the current so that it does not exceed a first set value, so that the current value of the transformer does not exceed a second set value, and so that the current value flowing through the main breaker does not exceed a third set value, and the first control master unit, the second control master unit, the third control master unit, and the control slave units communicate with each other wirelessly, and the control slave units obtain difference information wirelessly from the first control master unit, the second control master unit, and the third control master unit, in addition, the first control master unit, the second control master unit, and the third control master unit mutually grasp the transmission of difference information to the control slave units, and each unit controls the transmission of individual difference information to the control slave units so that collisions do not occur. . With this configuration, vehicle charging is controlled by monitoring three currents: the current of the received power, the current of the transformer, and the current of the main breaker. This allows for demand control and prevents transformer overload, enabling efficient vehicle charging without stopping charging.

[0008] and,Even if multiple chargers are installed, each charger is controlled independently, eliminating the need for a centralized control unit, making it easy to add more chargers.

[0009] In addition, Since the control slave unit and each control master unit communicate wirelessly, there is no need to install a separate communication line.

[0010] Furthermore, A plurality of control master units do not simultaneously transmit control signals to the control slave units, and the control slave units can communicate well with each master unit and perform stable control. [Effects of the Invention]

[0011] According to the present invention, vehicle charging is controlled by managing three currents: the current of the received power, the current of the transformer, and the current of the main breaker.In addition to demand control and transformer overload monitoring, overcurrent of the main breaker is also monitored, allowing for efficient charging control without stopping vehicle charging. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a configuration diagram showing a first embodiment of a vehicle charging system. [Figure 2] 10 is a flowchart showing the flow of priority allocation. [Figure 3] 2 is a flowchart showing a flow of charging current control in the vehicle charging system shown in FIG. [Figure 4] FIG. 10 is a configuration diagram showing a second embodiment of a vehicle charging system. [Figure 5] FIG. 2 is a block diagram of a first control master unit. [Figure 6] FIG. 2 is a block diagram of a second control master unit. [Figure 7] FIG. 10 is a block diagram of a third control master unit. [Figure 8] FIG. 2 is a block diagram of a control slave unit. [Figure 9] 10 is a flowchart showing the flow of transmission control of the first control master device. [Figure 10]10 is a flowchart showing the flow of transmission control of the second control master device. [Figure 11] 10 is a flowchart showing the flow of transmission control of the third control master device. [Figure 12] 10 is a flowchart showing a flow of charging current control of a controlled slave device. DETAILED DESCRIPTION OF THE INVENTION

[0013] Embodiments of the present invention will be described in detail below with reference to the drawings. Fig. 1 is a configuration diagram showing a first embodiment of a vehicle charging system according to the present invention. As shown in Fig. 1, the vehicle charging system 1 includes a plurality of chargers 2 to which a charging cable L1 extending from a vehicle 4 is connected, and a charging control unit 3 that obtains received power information (current information) of high-voltage commercial power Q from a smart meter (watt-hour meter) 10, obtains current information from a plurality of locations, generates a control signal for the charging current, and outputs the signal to each charger 2.

[0014] Note that 5 (5a, 5b) is a step-down transformer (hereinafter simply referred to as "transformer") that converts high-voltage power into low-voltage power, 6 is a load such as an air conditioner that is supplied with three-phase power, 7 is a load such as lighting that is supplied with single-phase 100 / 200V, and 11 is a main breaker provided in a distribution board (not shown) that supplies power to the charger 2. Single-phase 200V power is supplied to the charger 2.

[0015] The charger 2 includes a circuit (not shown) that receives a control signal from the charge control unit 3 to change the charging current, and a circuit that communicates with the connected vehicle.

[0016] The charging control unit 3 includes a first measurement unit 31a connected to the smart meter 10 via communication line L2 to obtain current information on the received power, a second measurement unit 31b that obtains current information from a current sensor 8 provided in the secondary circuit of transformer 5b, which is one of the transformers 5 that supplies power to the charger 2, a third measurement unit 31c that obtains current information from a current sensor 9 that measures the current flowing to the main breaker 11, a memory unit 32 that stores the received current reference value (first set value) described below, the rated current value (second set value) of the transformer 5b, the rated value (third set value) of the main breaker 11, and a charging power threshold value described below, a charging control unit CPU 34 that determines the charging current of each charger 2 and controls each unit of the charging control unit 3, and a plurality of communication units 35 that communicate with each charger 2.

[0017] The receiving current reference value is a current value set so that the received power is, for example, 10% less than the maximum demand value, and is a numerical value set by the consumer to reduce the maximum demand value and thereby reduce the contract fee. The charging power threshold (hereinafter simply referred to as the "threshold") is the amount of power used as a reference when setting the priority of vehicles to be charged, and is, for example, the amount of power required to travel a set distance. This threshold is set for each vehicle 4 under the control of the charging control unit CPU 34 based on the remaining battery capacity information obtained by the charger 3 from the vehicle 4.

[0018] The charging control of the vehicle charging system 1 configured as above is carried out as follows. First, a priority order is assigned to the vehicles 4 to be charged. Figure 2 shows the flow of assigning a priority order to the vehicles 4 to be charged, and will be described with reference to Figure 2. When a vehicle 4 is connected to the charger 2 (the charging plug of the vehicle 4 is connected) and a charging start operation is performed, charging begins with a preset current value under the control of the charging control unit CPU 34. At the same time, a priority is assigned to the vehicle 4 together with other vehicles 4 that are already undergoing charging control. First, the number of vehicles 4 whose charge amount is less than the threshold (unachieved number: n) is determined (S1), and then the number of vehicles 4 whose charge amount is equal to or greater than the threshold (achieved number: m) is determined (S2). The charging control unit CPU 34 grasps the amount of charge (amount of power since the start of charging) for each vehicle 4, and makes a judgment by comparing this value with a threshold value.

[0019] Next, the vehicles 4 included in the unachieved number n are arranged in order of the amount of charge, and are ranked from 1st to nth and allocated (S3).Furthermore, the vehicles 4 included in the achieved number m are arranged in order of the amount of charge, and are ranked from n+1th to n+mth and allocated (S4). In this way, the vehicles are ranked from 1 to n+m, and among the 1st to nth vehicles 4, the 1st vehicle 4 has the most charged amount, and the nth vehicle 4 has the least charged amount. Also, among the n+1st to n+mth vehicles 4, the n+1st vehicle 4 has the most charged amount, and the n+mth vehicle 4 has the least charged amount. After assigning the priorities in this way, the process proceeds to control the charging current.

[0020] FIG. 3 is a flowchart showing the flow of the charge current control carried out by the charge control unit 3, and the charge control will be described with reference to this flow. After the above-mentioned priority allocation process (S11) is completed, deviation information is judged (S12). The deviation information will now be explained. There are three types of deviation information: first deviation information, second deviation information, and third deviation information, which are calculated using the following equations 1 to 3, respectively. First deviation information (A) = current receiving current (low voltage equivalent value (A)) - receiving current reference value (low voltage equivalent value (A)) ...(Formula 1) Second deviation information (A) = transformer current (A) - transformer rating (A) ...(Formula 2) Third deviation information (A) = Main breaker current (A) - Main breaker rating (A) ...(Formula 3) The low voltage conversion value of the first deviation information is, for example, a conversion value when a three-phase high voltage of 6600 V is reduced to a single-phase low voltage of 200 V. For example, in the case of 6600 V and 1 A, the power P is P=√3×6600×1=11431.5W Therefore, when converted to 200V, the current I is I=11431.5 / 200=57A and is 57 A. The conversion transformer rating is the rated capacity (secondary current) of the transformer 5b. Moreover, the transformer current is the current value on the secondary side of the transformer 5b.

[0021] The deviation information is judged by integrating the first to third deviation information and determining whether the deviation information is positive, zero, or negative. This determination is made as follows. <Positive Determination> The power receiving current exceeds the first set value, which is the reference value. The current of the transformer 5b exceeds the transformer rated value. The current of the main breaker 11 exceeds the rated value of the main breaker 11. If at least one of these is determined to be true, it is determined to be positive. As described above, the first set value is a current value set so that the amount of received power is, for example, 10% smaller than the set maximum demand value. The case where the received current exceeds the first set value means that the average power for 30 minutes is calculated and predicted from the current received power, and it is determined that the predicted value may exceed 90% of the demand power value and approach the maximum demand value. <Determining Zero> The incoming current is approximately equal to the first set value (including cases where there is a difference of a few percent). The current of the transformer 5b is approximately equal to the transformer rated value. The current of the main breaker 11 is approximately equal to the rated value. If any of these is true and none of them exceeds the set value or rated value, it is determined to be zero. <Determination of negative> The receiving current does not reach the first set value. The current of the transformer 5b does not reach the transformer rated value. The current of the main breaker 11 does not reach the rated value. If all of these conditions are met, it is determined to be negative.

[0022] The control differs depending on whether the deviation information thus determined is positive, zero, or negative. If the deviation information is a positive value, the process proceeds to S13; if it is zero, the control is terminated; if it is negative, the process proceeds to S18.

[0023] If the deviation information is positive, control is implemented to reduce the current. Specifically, the maximum value of the deviation information, which is the current value information that exceeds the threshold, is set as the deviation value (S13), and control is implemented to reduce the charging current in ascending order of number, starting with the (n+m)th vehicle 4 that has reached the threshold and has the least amount of charge (S14). However, the maximum reduction amount per vehicle 4 is set to the smaller of the value obtained by subtracting the predetermined minimum current value from the current current value and the calculated deviation value (S15). For example, if the deviation value is 10 amperes and the value obtained by subtracting the predetermined minimum current value from the current charging current value is 5 amperes, 5 amperes is selected, and control is implemented to reduce the charging current of the (n+m)th vehicle 4, which has the lowest priority (highest charged amount) in the priority setting, by 5 amperes. In this way, the vehicle 4 with the least charged amount among those that have reached the threshold is given the highest priority for charging current reduction.

[0024] Then, the current value obtained by subtracting the reduced current value from the deviation value is set as the new deviation value (S16), and steps S14 to S17 are repeated for all vehicles 4 until the deviation value becomes zero or until the control is performed for the vehicles in the set order. In this way, the newly set charging current value is notified from the communication unit 35 to each charger 2 (S23), and the control from S11 to S23 is repeated at predetermined time intervals to control the charging current. As a result, among the vehicles 4 whose charge amount has reached the threshold, the charging current is reduced starting from the vehicle 4 with the least charge amount. Therefore, the charge amount of a vehicle 4 that started charging later does not exceed the charge amount of a vehicle 4 that started charging earlier, and control can be performed to prevent dissatisfaction among users who spend long charging times.

[0025] If the deviation information is zero, the charging current of any vehicle 4 is not changed, and the process returns to the first step S11, where priority allocation is performed again.

[0026] On the other hand, if the deviation information is negative, control is performed to increase the charging current. Specifically, the minimum absolute value of the deviation information, which is information about the current value that can be increased, is set as a margin value (S18), and the current value that can be increased until it reaches the threshold (margin information) is calculated based on the following equations 4 to 6. First margin information = absolute value of first deviation information (Equation 4) Second margin information = absolute value of second deviation information (Equation 5) Third margin information = absolute value of third deviation information (Equation 6) The margin value is the smallest value among the first to third margin information, and among the vehicles 4 whose charged amounts do not meet the threshold, the charging current is increased in order from the vehicle 4 with the most charged amount to the vehicle 4 with the least charged amount (S19). The charging current is increased (S20) in order from the vehicle 1 that has not reached the threshold and has the highest charge amount to the vehicle 4 that has the n+mth charge amount.

[0027] However, the maximum increase per vehicle 4 is set to the smaller of the value obtained by subtracting the current current value from the predetermined maximum charging current value and the calculated margin value (S20). 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 performed to increase the charging current of the first vehicle 4, which has the least amount of charge, by 5 amperes. In this way, the vehicle 4 with the most charged amount among the vehicles 4 that have not reached the threshold value is given the highest priority for increasing the charging current, and the current is increased.

[0028] Then, the current value obtained by subtracting the increased current value from the margin value is set as a new margin value (S21), and steps S19 to S22 are repeated until the margin value becomes zero or for all vehicles 4, and control is performed in the set order of vehicles 4. In this way, the newly set charging current value is notified to each charger 2 (S23), and charging is controlled. As a result, the charging current increases from the vehicle 4 with the largest charge amount among the vehicles 4 whose charge amount is below the threshold. Therefore, the charge amount of the vehicle 4 that starts charging later does not exceed the charge amount of the vehicle 4 that starts charging earlier, and control can be performed to prevent dissatisfaction from users who spend long charging times.

[0029] In this way, charging of the vehicle 4 is controlled by monitoring three currents: the current of the received power, the current of the transformer 5b, and the current of the main breaker 11. This allows for demand control and prevents overload of the transformer 5b, enabling efficient vehicle charging without stopping charging.

[0030] Next, a second embodiment of the vehicle charging system 1 will be described. Fig. 4 is a configuration diagram showing a second embodiment of the vehicle charging system 1, and the description will be given based on Fig. 4. However, components common to the first embodiment are given the same reference numerals and description thereof will be omitted. This vehicle charging system 1 comprises a plurality of chargers 2, a first control master unit 110 that obtains current information of the received power from a smart meter 10 that measures the power received from high-voltage commercial power Q and outputs first deviation information (difference information), a second control master unit 115 that obtains current information from a current sensor 8 provided on the secondary side of the transformer 5b and outputs second deviation information (difference information), a third control master unit 120 that obtains current information flowing to the main breaker 11 from a current sensor 9 and outputs third deviation information (difference information), and a control slave unit 130 that is installed for each charger 2 and controls the charging current of the charger 2. The first to third deviation information (difference information) are the information shown in the above-mentioned formulas 1 to 3.

[0031] Fig. 5 shows a block diagram of the first control master unit 110. As shown in Fig. 5, the first control master unit 110 includes a first master unit measurement unit 111 that acquires receiving current information from the smart meter 10, a first master unit storage unit 112 that stores a receiving current reference value (first set value) and the like, a first master unit CPU 113 that controls the first control master unit 110, and a first master unit communication unit 114 that wirelessly communicates with the control slave unit 130 and also wirelessly communicates with the second control master unit 115 and the third control master unit 120. The first control master unit 110 is connected to the smart meter 10 via a communication line L2.

[0032] Fig. 6 shows a block diagram of the second control master unit 115. As shown in Fig. 6, the second control master unit 115 includes a second master unit measurement unit 116 that acquires current information of the transformer 5b from the current sensor 8, a second master unit storage unit 117 that stores the transformer rated current (second set value) and the like, a second master unit CPU 118 that controls the second control master unit 115, and a second master unit communication unit 119 that wirelessly communicates with the control slave unit 130 and also wirelessly communicates with the first control master unit 110 and the third control master unit 120.

[0033] Fig. 7 shows a block diagram of the third control master unit 120. As shown in Fig. 7, the third control master unit 120 includes a third master unit measurement unit 121 that acquires information on the current flowing to the main breaker 11 from the current sensor 9, a third master unit storage unit 122 that stores the rated value (third set value) of the main breaker 11, a third master unit CPU 123 that controls the third control master unit 120, and a third master unit communication unit 124 that wirelessly communicates with the control slave unit 130 and also wirelessly communicates with the first control master unit 110 and the second control master unit 115.

[0034] Fig. 8 shows a block diagram of the control slave unit 130. As shown in Fig. 8, a control slave unit 130 is provided for each charger 2, and includes a slave unit communication unit 131 that wirelessly communicates with the first control master unit 110, the second control master unit 115, and the third control master unit 120, a slave unit storage unit 132 that stores a threshold for the charge amount, a duration and a standby time, which will be described later, etc., a slave unit CPU 133 that controls the control slave unit 130, and a charger control unit 134 that outputs a control signal to the charger 2. The control slave unit 130 is connected to the charger 2 via a transmission line L3. The control slave unit 130 and the charger 2 may be formed integrally.

[0035] The first set value stored in the first parent unit memory unit 112 and the transformer rating stored in the second parent unit memory unit 117 are the same as the set values ​​shown in the first embodiment above, with the first set value being set to a value that is, for example, about 10% smaller than the maximum demand value, and the transformer rating being a value set based on the rated value of transformer 5b.

[0036] The charging control of the vehicle charging system configured as above is carried out as follows. First, the first control master device 110 obtains information on the received current from the smart meter 10 and notifies each control slave device 130 of the deviation information at regular intervals, such as every second. At the same time, the first control master device 110 obtains current information and voltage information of the transformer 5b from the current sensor 8, etc., and notifies each control slave device 130 of the deviation information at regular intervals, such as every second. Furthermore, the deviation information notified to each control slave unit 130 is the same as the deviation information of the first form described above, and is information (difference information) consisting of three values: plus, zero, and minus, determined based on the first to third deviation information calculated using the above equations 1 to 3.

[0037] Information is transmitted from the first to third control master devices 110, 115, and 120 to the control slave device 130 as follows. FIG. 9 shows the flow of transmission control of the first control master unit, FIG. 10 shows the flow of transmission control of the second control master unit, and FIG. 11 shows the flow of transmission control of the third control master unit, and the description will be made with reference to these figures. The first control master unit 110 first transmits the calculated first deviation information to the control slave unit 130 (S31). Then, it waits for the third deviation information to be transmitted from the third control master unit 120, and when transmitted, it receives and recognizes it (S32, S33), and then waits for a certain period of time (S34). Then, it transmits the next first deviation information to the control slave unit 130.

[0038] The second control master unit 115 waits for the first control master unit 110 to transmit the first deviation information to the control slave unit 130, and when it is transmitted, receives and recognizes it (S35, S36), and then waits for a certain period of time (S37). Thereafter, the second control master unit 115 transmits the second deviation information to the control slave unit 130 (S38).

[0039] The third control master unit 120 waits for the second control master unit 115 to transmit the second deviation information to the control slave unit 130, and when it is transmitted, receives and recognizes it (S39, S40), and then waits for a certain period of time (S41). Thereafter, the third deviation information is transmitted to the control slave unit 130 (S42).

[0040] In this way, since the control slave device 130 and each of the control master devices 110, 115, and 120 communicate wirelessly, there is no need to install a separate communication line, making it easy to increase or decrease the number of chargers 2. In addition, certain rules are set for the timing of information transmission from each of the control master devices 110, 115, and 120 to the control slave device 130, and the information is not transmitted simultaneously, so there is no problem caused by collision between signals transmitting information to the control slave device 130.

[0041] In the above embodiment, rules are set for the transmission timing of the control master devices 110, 115, and 120 to prevent collisions between signals, but the control slave device 130 may obtain information from each of the control master devices 110, 115, and 120 in turn.

[0042] In this way, each control slave unit 130 that has received the deviation information from each control master unit 110, 115, 120 performs the following control. 12 is a flowchart showing the flow of current control performed by the slave CPU 133 of the control slave 130, and the description will be made with reference to this flow. This control is performed every time deviation information (first to third deviation information) is received. When deviation information is received (S50), the deviation information is judged (S51). As in the above embodiment, the first to third deviation information are combined and judged as either plus, zero, or minus. Thereafter, the state of charge is determined (S52), and different control is performed depending on the charge amount since the start of charging. If the charge amount has not reached a preset threshold, the process proceeds to S53, and if it has reached the threshold, the process proceeds to S56.

[0043] If the charging current has not reached the threshold (proceed left in S52) and the deviation information is negative (proceed right in S53), that is, if there is room for the charging current, the increased current is calculated using the following equation (Equation 7), and the calculated current is added to the charging current to increase it (S55). Note that a maximum value is set for the charging current, and if it has reached the maximum value, it will not increase any further. Increased current = Maximum current value (A) × Charge amount (Wh) / Threshold value (Wh) (Equation 7)

[0044] On the other hand, if the deviation information is zero (proceed to the left in S53), a signal not to change the charging current is output to the charger 2 (S62) and the process ends. If the deviation information is positive (proceed downward in S53), that is, if the current needs to be reduced, the current to be reduced is calculated using the following formula (Formula 8), and the amount of the reduced current is subtracted from the current value (S54). Note that a minimum value is set for the charging current, and if the minimum value is reached, the charging current will not be reduced any further. Reduced current = Maximum current value (A) x (Threshold (Wh) - Charge amount (Wh)) / Threshold (Wh) ...(Formula 8) The new current value thus set is notified to the charger 2 (S62).

[0045] On the other hand, when the deviation information is received, if charging has progressed to the threshold value or more (go right in S52), the following control is performed. If the deviation information is negative (proceed to the right in S56), that is, if there is room for charging current, the duration stored in the slave unit memory unit 132 is read, and if the duration has not reached the set waiting time of 60 seconds or the like (NO in S57), the duration is added by one unit (the time interval for receiving deviation information) (S58) and saved, and a signal that does not change the current is output to the charger 2 (S62) and the process ends. If the duration has reached the standby time (YES in S57), a signal to add the minimum increase current to the current current (S59) is output to the charger 2 (S62), and the process ends.

[0046] With this control, for vehicles 4 whose charging current has reached the threshold, a waiting time is set and changes to the charging current are stopped until that time has elapsed. Therefore, if there is a vehicle 4 whose charge amount has not reached the threshold, this waiting time can be used to increase the charging current and promote charging, allowing for balanced current control without the need for a control unit that manages all chargers 2 at once.

[0047] Also, if the deviation information is almost zero in S56 (proceed left in S56), the stored duration is reset to zero (S61), and a signal that does not change the current is output to the charger 2 (S62), and the process ends. If the deviation information is positive (going down in S56), that is, if the current needs to be reduced, the charging current is set to zero (S60) and the stored duration is reset to 0 (S61). As a result, a signal to set the charging current to 0 is output to the charger 2, and the process ends.

[0048] With this control, if the current of the received power exceeds the first set value or if the current of the transformer 5b exceeds the transformer rating, charging of the vehicle 4 that has been charged above the threshold value regardless of the standby time is stopped, thereby performing demand control while maintaining good condition of the transformer 5b. In addition, since the standby time count is reset, a sufficient standby time (duration) can be set, and charging of vehicles 4 whose charge amount has not reached the threshold can be continued during that time, allowing for balanced allocation of charging current.

[0049] In this way, even if multiple chargers 2 are provided, control of each charger 2 is performed for each charger 2, so there is no need to provide a function for centralized control of the entire system. Therefore, when adding or removing chargers 2, it is only necessary to add or remove the control slave units 130 accordingly, and there is no need to change the first control master unit 110, the second control master unit 115, or even the third control master unit 120, making it easy to add chargers 2 and providing system expandability.

[0050] In the above embodiment, the second set value is set based on the rated power of the transformer 5b (transformer rating), but it may be set to a value slightly smaller than the rated value, for example, 10% smaller. This method of setting the set value is also similar to that for the third set value. [Explanation of symbols]

[0051] 1·· Vehicle charging system, 2·· Charger, 3·· Charging control unit, 4·· Vehicle, 5b·· Transformer (step-down transformer), 9·· Current sensor, 10·· Smart meter (power meter), 11·· Main breaker, 31·· Measurement unit, 31a·· First measurement unit, 31b·· Second measurement unit, 31c·· Third measurement unit, 32·· Memory unit, 34·· Charging control unit CPU, 35·· Communication unit, 110·· First control parent unit (charging control unit), 111·· First parent unit measurement unit (third measurement unit) 1 measurement unit), 114· first parent device communication unit (wireless communication unit), 114· second control parent device, 115· second control parent device (charging control unit), 116· second parent device measurement unit (second measurement unit), 118· second parent device communication unit (wireless communication unit), 120· third control parent device (charging control unit), 121· third parent device measurement unit (third measurement unit), 123· third parent device communication unit (wireless communication unit), 130· control child device (charging control unit), 131· child device communication unit (wireless communication unit).

Claims

[Claim 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, The charging control unit includes a first measurement unit that acquires current value information of received power from a watt-hour meter that measures received high-voltage power; a second measurement unit that acquires current value information of a transformer that converts received high-voltage power into low-voltage power and supplies the low-voltage power to the charger; a third measurement unit that acquires information about a current value flowing through a main breaker of a distribution board that supplies power to the charger, controlling the received current value acquired by the first measuring unit not to exceed a predetermined first set value, the current value acquired by the second measuring unit not to exceed a predetermined second set value, and the current value acquired by the third measuring unit not to exceed a predetermined third set value; In addition, the charging control unit includes a first control master unit that includes the first measurement unit and outputs difference information of the receiving current with respect to the first set value; a second control master unit including the second measurement unit and outputting difference information of the transformer current relative to the second set value; a third control master unit including the third measurement unit and outputting difference information of the main breaker current relative to the third set value; a control slave unit that is installed for each of the chargers and controls the charging current based on information output from the first control master unit, the second control master unit, and the third control master unit; The control slave unit controls, based on the difference information transmitted from the first control master unit, the second control master unit, and the third control master unit, so that the received current value does not exceed the first set value, so that the current value of the transformer does not exceed the second set value, and so that the current value flowing to the main breaker does not exceed the third set value; the first control master unit, the second control master unit, the third control master unit, and the control slave unit communicate with each other wirelessly, and the control slave unit obtains the difference information wirelessly from the first control master unit, the second control master unit, and the third control master unit; In addition, the vehicle charging system is characterized in that the first control parent unit, the second control parent unit, and the third control parent unit mutually understand the transmission of the difference information to the control child units, and each control the transmission of individual difference information to the control child units so that no conflicts occur.

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