JP2015208065A - vehicle charging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle charging system which allows for suitable charging of a vehicle in a charger.SOLUTION: Switching can be made between power supply state by one 100 V voltage line L1 in single-phase three-wire wiring and another 100 V voltage line L2, and power supply state by the neutral line N of single-phase three-wire wiring and one 100 V voltage line L1, by means of electromagnetic contactors MC2, MC3. A controller performs switching control between the power supply state by the neutral line N and the 100 V voltage line L1, and the power supply state by one 100 V voltage line L1 and another 100 V voltage line L2, according to the changes in the charging environment.

Description

  The present invention relates to a vehicle charging system for charging a vehicle in a charging device.

  For example, Patent Document 1 discloses a vehicle charging system that charges a power storage device mounted on a vehicle such as an electric vehicle (EV) or a plug-in hybrid vehicle (PHV). As a vehicle charging system, in Patent Document 1, a charging voltage is switched by a user's key operation so that a vehicle with a different charging voltage can be appropriately handled.

JP 2012-186926 A

  By the way, when the vehicle charging system is configured to be able to supply power to a plurality of vehicles, it is possible to charge a plurality of vehicles at the same time, but the contract power cannot be exceeded, so each vehicle can be charged. There is a need for a system (energy management) that controls charging power. When charging is controlled by this energy management, a vehicle having a control pilot (CPLT) function (mode 2 or 3 compatible vehicle) can inform the maximum value of current that can be supplied from the charging station to the vehicle. At this time, in IEC61851 and SAEJ1772 which are charging standards for electric vehicles, 6A is the lowest current, so conventionally, 200V × 6A = 1200 W was the lowest power. Therefore, it cannot be narrowed down to 1200 W or less, and there is a concern that charging is not possible when a plurality of batteries are charged or when power is tight.

  The objective of this invention is providing the vehicle charging system which can charge a vehicle suitably in a charging device.

  According to the first aspect of the present invention, in the vehicle charging system in which the vehicle is charged with power supplied from the system power supply in the charging device, the single-phase three-wire system in the charging device that receives power supply with the single-phase three-wire wiring. Switch between the power supply state with one of the 100 volt voltage line and the other 100 volt voltage line in the wiring, and the power supply state with two of the neutral and 100 volt voltage lines in the single-phase three-wire wiring The gist is provided with possible switching means and switching control means for switching and controlling the switching means according to a change in charging environment.

  According to the first aspect of the present invention, in the switching device, in the charging device that receives power supply by the single-phase three-wire wiring, one 100-volt voltage line and the other 100-volt voltage in the single-phase three-wire wiring. It is possible to switch between a power supply state with two lines and a power supply state with two neutral lines and a 100 volt voltage line with single-phase three-wire wiring. The switching control unit performs switching control of the switching unit according to a change in the charging environment.

  Therefore, when charging the vehicle by receiving power supply from the system power supply in the charging device, the power can be further reduced by switching the charging voltage to the vehicle between 200 V and 100 V, thereby favorably charging. be able to.

As described in claim 2, in the vehicle charging system according to claim 1, the switching control means may perform switching control of the switching means based on the number of vehicles to be charged.
As described in claim 3, in the vehicle charging system according to claim 1, the switching control means may perform switching control of the switching means based on power information from a center.

  According to a fourth aspect of the present invention, in the vehicle charging system according to the first aspect, the switching control unit may perform switching control of the switching unit based on power price information from a center.

  According to the present invention, the vehicle can be suitably charged in the charging device.

1 is an overall configuration diagram of a vehicle charging system according to an embodiment. The time chart for demonstrating an effect | action. The time chart for demonstrating an effect | action. The time chart for demonstrating an effect | action.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
As shown in FIG. 1, the vehicle charging system 10 includes a charging station 20 and a charging station 60. Vehicles 40 and 42 are electric vehicles or plug-in hybrid vehicles. Vehicles 40 and 42 are mounted with a power storage device such as a secondary battery or an electrochemical capacitor, a power converter that converts alternating current into direct current and charges the power storage device, a controller that controls the power converter, and the like. The charging stations 20 and 60 serving as charging devices can be supplied with electric power from the system power supply 30 to charge the vehicles 40 and 42. Here, the charging stand 20 and the charging stand 60 have the same configuration except for the arrangement of the power source 22.

  The charging stand 20 includes a charging controller 21, electromagnetic contactors (magnet contactors) MC1, MC2, MC3, a power breaker 23, charging voltage detectors 24, 25, a voltage detector 26, and the like. The charging stand 20 is connected to the system power supply 30 by single-phase three-wire wiring. The charging stand 20 is connected to the vehicle 40 via the charging plug 41 when charging the power storage device mounted on the vehicle 40.

  The charging stand 20 includes an electromagnetic contactor MC1 that switches a charging path between the system power supply 30 and the vehicle 40 to an energized state during charging. The magnetic contactor MC1 is electrically connected to the charge controller 21. The charge controller 21 opens and closes the electromagnetic contactor MC1 by outputting an electrical signal.

  The vehicle charging system 10 includes a main controller 50 that controls the charging controller 21, and the main controller 50 is connected to the charging controller 21 so as to be communicable. The main controller 50 outputs a charge execution instruction to the charge controller 21. Connected to the primary side of the magnetic contactor MC1 is a power breaker 23 that cuts off the flow of current when an overcurrent flows. The charging stand 20 includes a power source 22. The power source 22 receives power from the system power source 30 on the electromagnetic contactor MC 1 side from the power breaker 23 and supplies power to the charge controller 21.

  The charge controller 21 is connected to a charge voltage detector 24 that detects a secondary voltage between the charge plug 41 and the electromagnetic contactor MC1, that is, the output side of the electromagnetic contactor MC1. In addition, the charge controller 21 inputs the detection result of the charge voltage detection unit 24. The charge controller 21 is connected to a charge voltage detector 25 that detects a voltage on the primary side that is the input side of the electromagnetic contactor MC1. The charge controller 21 inputs the detection result of the charge voltage detection unit 25. Furthermore, a voltage detection unit 26 that detects the voltage of the CPLT (control pilot) line in the charge plug 41 is connected to the charge controller 21. The charge controller 21 confirms the connection with the vehicle 40 side by the CPLT (control pilot) function based on the detection result of the voltage detection unit 26 and the like. In the charging stand 20, the primary side of the magnetic contactor MC <b> 1 is connected to the system power supply 30 via the power breaker 23, and the secondary side of the electromagnetic contactor MC <b> 1 is connected to the vehicle 40 via the charging plug 41.

  The power breaker 23 of the charging stand 20 is connected to the system power supply 30 by a single-phase three-wire wiring. In other words, the system power supply 30 and the power breaker 23 are connected by three lines of the neutral line N, the first 100 volt voltage line L1, and the second 100 volt voltage line L2. The power breaker 23 is connected to the primary side of the magnetic contactor MC1 by two lines, a first 100 volt voltage line L1 and a second 100 volt voltage line L2. 200 V is applied between the first 100 volt voltage line L1 and the second 100 volt voltage line L2, and the battery is charged. An electromagnetic contactor MC2 is provided in the middle of the first 100 volt voltage line L1 and the second 100 volt voltage line L2 to which 200V is supplied. The electromagnetic contactor MC2 is opened and closed by the charge controller 21.

  The power breaker 23 is connected to the primary side of the magnetic contactor MC1 by two lines, a first 100 volt voltage line L1 and a neutral line N. 100V is applied between the first 100-volt voltage line L1 and the neutral line N, and the battery is charged. An electromagnetic contactor MC3 is provided in the middle of the first 100 volt voltage line L1 and the neutral line N to which 100V is supplied. The electromagnetic contactor MC3 is driven to open and close by the charge controller 21.

  As described above, in the charging station 20 that receives power supply by the single-phase three-wire wiring, the electromagnetic contactors MC2 and MC3 as the switching means, and the one 100-volt voltage line L1 in the single-phase three-wire wiring and the other It is possible to switch between a power supply state with two 100 volt voltage lines L2 and a power supply state with two neutral lines N and a first 100 volt voltage line L1 with single-phase three-wire wiring.

  On the other hand, the charging stand 60 is connected to the system power supply 30 by single-phase three-wire wiring. The charging stand 60 is connected to the vehicle 42 via the charging plug 43 when charging the power storage device mounted on the vehicle 42.

  Similarly to the charging stand 20, the charging stand 60 includes a charging controller 21, electromagnetic contactors (magnet contactors) MC1, MC2, MC3, a power breaker 23, charging voltage detection units 24, 25, a voltage detection unit 26, and the like. Yes. The charge controller 21 of the charging station 60 operates by receiving power from the power source 22 of the charging station 20. Furthermore, the power breaker 23 of the charging stand 60 is also connected to the system power supply 30 by a single-phase three-wire wiring, and the power breaker 23 is connected to the first 100 volt voltage line L1 and the second 100 volt voltage line L2. Two are connected to the primary side of the magnetic contactor MC1 and two are connected to the primary side of the magnetic contactor MC1 through the second 100-volt voltage line L2 and the neutral line N. Furthermore, an electromagnetic contactor MC2 is provided in the middle of the first 100 volt voltage line L1 and the second 100 volt voltage line L2 provided with 200V. An electromagnetic contactor MC3 is provided in the middle of the second 100 volt voltage line L2 and the neutral line N to which 100V is supplied. The magnetic contactors MC2 and MC3 are opened and closed by the charge controller 21 of the charging stand 60.

  In this way, in the charging station 60 that receives power supply by the single-phase three-wire wiring, the electromagnetic contactors MC2 and MC3 as the switching means, and the one 100-volt voltage line L1 in the single-phase three-wire wiring and the other It is possible to switch between a power supply state with two 100 volt voltage lines L2 and a power supply state with two neutral lines N and a second 100 volt voltage line L2 with single-phase three-wire wiring.

  The charging station 20 can be in a power supply state with a neutral line N and a first 100-volt voltage line L1 with a single-phase three-wire wiring, and the charging station 60 with a single-phase three-wire wiring. The power supply state by the two neutral lines N and the second 100-volt voltage line L2 is made in consideration of balance.

  In addition, the charging controller 21 of the charging stand 60 communicates with the main controller 50. That is, the main controller 50 is communicably connected to the charging controller 21 of the charging stand 60, and the main controller 50 outputs a charge execution instruction to the charging controller 21 of the charging stand 60.

  Then, the upper main controller 50 that controls the plurality of charging stations 20 and 60 controls the charging controller 21 of the charging station 20 and the charging controller 21 of the charging station 60. The charging power can be adjusted.

  As described above, the magnetic contactors MC2 and MC3 are controlled in the charging stations 20 and 60 by the change of the charging environment by using the main controller 50 as the switching control means and the charging controller 21 in each charging station 20 and 60. Can be done.

Next, the operation of the vehicle charging system 10 will be described.
The charging controller 21 in the main controller 50 and each charging station 20 and 60 switches and controls the electromagnetic contactors MC2 and MC3 in the charging stations 20 and 60 according to changes in the charging environment. The main controller 50 and the charging controller 21 in each charging station 20, 60 adjust the charging power at each charging station 20, 60 by switching and controlling the electromagnetic contactors MC 2, MC 3 based on the number of vehicles to be charged.

This will be described in detail below.
The single-phase three-wire wiring has three lines (neutral line N, first 100 volt voltage line L1, and second 100 volt voltage line L2). From the charging voltage 200V using the 100 volt voltage line L1 and the second 100 volt voltage line L2, the neutral line N and the first 100 volt voltage line L1 in the charging station 20 and the neutral line N in the charging station 60 and The charging voltage is switched to 100V using the second 100 volt voltage line L2. As a result, the minimum power can be reduced to 600 W (= 100 V × 6 A).

  When charging an electric vehicle (EV), a plug-in hybrid vehicle (PHV), etc., it is 6 A at 200 V and has a predetermined upper limit current (the upper limit is 80 A in the standard).

In the conventional method in which the charging voltage is not switched, the minimum value of the charging power is 1200 W (= 200 V × 6 A).
On the other hand, in the present embodiment in which the charging voltage is switched at 100V / 200V, the operation is as follows.

  When the charging voltage is 100 V, the minimum value of the charging power is 600 W (= 100 V × 6 A). When the charging voltage is 200V, the minimum value of the charging power is 1200W (= 200V × 6A). Therefore, by switching the charging voltage at 100V / 200V, the minimum value of the charging power can be adjusted from 600W to 1200W.

This will be specifically described with reference to FIG.
In FIG. 2, the horizontal axis represents time and the vertical axis represents power. Contract power is predetermined for the power on the vertical axis.

  Now, it is assumed that the vehicle A is charging at the charging station 20. Thereafter, it is assumed that the vehicle B starts charging at the charging station 60. That is, when charging two vehicles at the same time in a charging facility (charging station 20 and charging station 60) that receives power supply from a common system power supply 30, the main controller 50 and the charging controller 21 are connected to the charging stations 20 and 60, respectively. The magnetic contactors MC2 and MC3 are switched and controlled as follows.

Now, the electromagnetic contactor MC1 is closed, the electromagnetic contactor MC2 is closed, and the electromagnetic contactor MC3 is opened, and charging is performed at 200V.
When it is necessary to suppress (control) the power at the request of the energy management system or EDMS (energy data management system), the charge controller 21 sets the control pilot (CPLT) voltage to 0 V, and then temporarily sets the magnetic contactor MC1. open. This is because if the plug is kept inserted when switching the charging voltage, charging cannot be resumed after switching, so the plug is removed and then plugged again. In this embodiment, the control pilot (CPLT) is used. The voltage is forced to 0V and the plug is unplugged.

Then, the charge controller 21 opens the electromagnetic contactor MC2 and closes the electromagnetic contactor MC3 to switch the charging voltage from the current 200V to 100V.
Thereafter, the charge controller 21 closes the electromagnetic contactor MC1. Further, the charge controller 21 sets the control pilot (CPLT) voltage to 12V. Thereby, it is possible to create a state in which the plug is inserted. As a result, charging at a charging voltage of 100V is started.

  In this way, when the charging voltage is set to 200 V during charging, the mode 2 and 3 compatible vehicles can only adjust the minimum charging power to 1200 W. By switching the charging voltage to 100 V in order to perform charging over time while reducing the power, the minimum value of the charging power can be adjusted to 600 W. As a result, as shown in FIG. 2, when charging the vehicle A at the charging stand 20, charging is possible within a range of 1200 to 3200W when the charging voltage is 200V (200V × 16A = 3200W with the upper limit current value being 16A in FIG. 2). However, by switching the charging voltage to 100V, charging can be performed in the range of 600 to 1600W (in FIG. 2, the upper limit current value is 16A and 100V × 16A = 1600W), and during the period from t1 to t2 in FIG. In FIG. 20, the power to the vehicle A can be reduced to less than 1200 W, and the charging to the vehicle B can be simultaneously performed at the charging stand 60.

  In this way, by adding the function of the present embodiment to the existing charging stand, the variable control (power suppression) range of the mode 2 and 3 compatible vehicles is widened, so that power can be distributed to other vehicles. .

Another example will be described with reference to FIG.
As shown in FIG. 1, the main controller 50 adjusts a peak power setting value, which is a power value that can be used for charging, from the center 70 based on information from an electric power company through Internet communication or the like. Then, the main controller 50 and the charging controller 21 switch and control the electromagnetic contactors MC2 and MC3 at the timing t3 in FIG. 3 based on the power tightness information from the center 70.

FIG. 3 shows a situation where the peak power set value is set low due to power tightness.
When the power is tightened after the vehicle A starts to be charged at 200 V at the charging station 20 and the peak power setting value is lowered, the charging voltage is switched to 100 V and the supply of power to the vehicle A at the charging station 20 is kept low. Continue charging. In other words, when charging the vehicle A at the charging stand 20, it was possible to charge in the range of 1200 to 3200W at 200V (200V × 16A = 3200W with the upper limit current value being 16A in FIG. 3). Charging is possible within a range of 1600W (in FIG. 3, the upper limit current value is 16A and 100V × 16A = 1600W). Even when the peak power set value becomes less than 1200 W due to power shortage, the charging station 20 can supply power to the vehicle A. Charging can be performed with the power reduced to less than 1200 W.

  Specifically, when it is necessary to suppress (control) power at the request of an energy management system or EDMS (energy data management system) when charging at 200 V, the electromagnetic contactor MC1 is once opened. Then, the electromagnetic contactor MC2 is opened and the electromagnetic contactor MC3 is closed to switch the charging voltage from the previous 200V to 100V. Thereafter, the magnetic contactor MC1 is closed. This can reduce power during charging.

Another example will be described with reference to FIG.
The center 70 in FIG. 1 transmits power price prediction information. Specifically, RTP (Real Time Pricing), CPP (Critical Peak Pricing), and the like can be cited as prediction information of power prices. RTP is information in which prediction information is sent in units of 12 hours or 24 hours, for example, according to past results and weather.

  The main controller 50 is connected to the center 70 via a communication line, and the main controller 50 can communicate with the center 70. The main controller 50 is notified of power price prediction information from the center 70 via the Internet line or the like. Then, the main controller 50 and the charge controller 21 switch and control the electromagnetic contactors MC2 and MC3 based on the power price information from the center 70.

  FIG. 4 shows the relationship between RTP and suppression power. When RTP increases, the suppression power (suppression current value) decreases, and when RTP decreases, the suppression power (suppression current value) increases. As a result, when the power price is likely to increase, it is possible to suppress the suppressed power (suppressed current value) and to make the power charge constant.

  The main controller 50 increases the basic charge when the contract power is exceeded, so that the power charge is kept constant from the RTP information received from the center 70 in order to manage the power so as not to exceed the contract power. Determine the power. That is, the main controller 50 schedules the suppressed power for keeping the power rate constant based on the prediction information of the power price from the center 70.

  Then, when the power price rises after charging the vehicle 40 at the charging station 20 at 200V, the charging voltage is switched to 100V to suppress the supply of power to the vehicle 40 at the charging station 20 and to suppress the suppression power. Make the price constant. In FIG. 4, the charging voltage is switched to 100V at the timing of t4 when the power price is increased and the power (suppressed power) that can be used for charging is decreased, and the charging voltage is changed to 200V at the timing of t5 when the power price is decreased and the suppressing power is increased. It has been switched to.

According to the above embodiment, the following effects can be obtained.
(1) Because the range of variable control (power control) for vehicles compatible with modes 2 and 3 is expanded, the contracted power is reduced even when the number of vehicles to be charged increases, and when power is tight or when solar power is generated. Even when the power price increases due to the decrease in the power consumption, it is possible to distribute power to other vehicles and to suppress the charging power of the own vehicle.

  That is, in the vehicle charging system that receives power from the system power supply 30 at the charging stations 20 and 60 and charges the vehicles 40 and 42, the electromagnetic contactors MC2 and MC3 as switching means and the main controller 50 as switching control means. And a charge controller 21. The magnetic contactors MC2 and MC3 include a single-phase three-wire wiring in the single-phase three-wire wiring and the power supply state by one of the 100-volt voltage line L1 and the other 100-volt voltage line L2. The neutral line N and the first 100-volt voltage line L1, and the charging stand 60 can be switched to the power supply state by the neutral line N and the second 100-volt voltage line L2. Then, the main controller 50 and the charge controller 21 may change the power supply state by one of the 100 volt voltage line L1 and the other 100 volt voltage line L2, and the neutral line N In the first 100 volt voltage line L1 and the charging stand 60, switching control is performed between the power supply state of the neutral line N and the second 100 volt voltage line L2.

  Therefore, when the vehicle is charged with power supplied from the system power supply 30 at the charging stand, the power can be further reduced by switching the charging voltage to the vehicles 40 and 42 between 200V and 100V. Thus, the charging power can be suppressed, and charging can be suitably performed.

  (2) Specifically, the main controller 50 and the charge controller 21 serving as switching control means perform replacement control based on the number of vehicles to be charged. Therefore, it is possible to flexibly cope with charging a plurality of units.

  (3) The main controller 50 and the charge controller 21 as switching control means perform switching control based on power tightness information as power information from the center 70. Therefore, it is possible to flexibly cope with power shortages.

  (4) The main controller 50 and the charge controller 21 as switching control means perform switching control based on the power price information from the center 70. Therefore, even when the power price is likely to rise, it is possible to flexibly cope with the suppression power (suppressed current value).

The embodiment is not limited to the above, and may be embodied as follows, for example.
Although a control pilot (CPLT) compatible vehicle (mode 2, 3 compatible vehicle) has been described, it may be applied to a mode 1 compatible vehicle. A mode 1 vehicle is charged with a uniform power value, for example, 3200 W (= 200 V × 16 A) during charging. This mode 1 compatible vehicle is also useful because the power can be reduced by switching the charging voltage between 200V and 100V. Whether or not the vehicle is a mode 1 compatible vehicle, for example, a CPLT signal (charge permission signal) is sent from the stand side to the vehicle side.

  Then, as described with reference to FIG. 2, power control is performed on the mode 1 compatible vehicle that cannot be charged by the energy management system. As a result, the power control of the mode 1 compatible vehicle becomes possible, so that it is possible to distribute the power to other vehicles without occupying the charging power. In this way, by taking advantage of the characteristics of the single-phase three-wire wiring, it is possible to detect the mode 1 vehicle and perform power control.

  Further, as described with reference to FIG. 3, when it is desired to control power with an energy management system or the like, the power is suppressed by switching the voltage from 200 V to 100 V (single unit 100 V). For example, it is 3200W (= 200V × 16A) at a charging voltage of 200V, but it becomes 1600W (= 100V × 16A) by setting the charging voltage to 100V, enabling energy management that was impossible with a mode 1 compatible vehicle. Become. Specifically, when charging at 200V, if it is necessary to suppress (control) the power at the request of the energy management system or EDMS (energy data management system), if it is a mode 1 compatible vehicle that charges at 16A when charging, From 3200W (= 200V × 16A) to 1600W (= 100V × 16A), the power for 1600W can be suppressed.

  Since variable control of the mode 1 compatible vehicle is possible, when the mode 1 compatible vehicle and other mode compatible vehicles (such as the mode 3 compatible vehicle) are charged at the same time, the power to the mode 1 compatible vehicle is transferred to other mode compatible vehicles ( Can be distributed to mode 3 vehicles, etc.).

  -Although the example which charges two vehicles was shown in FIGS. 1, 2, etc., the number of vehicles to charge does not ask | require. For example, when charging 4 vehicles at the same time, when the contract power is 3600W, when 3 vehicles are charging at 1200W (= 200V × 6A), Consider the case of charging at a charging stand. By switching the charging voltage from the previous 200V to 100V, each of the four vehicles can be charged at 900W (= 100V × 9A).

  In FIG. 1, the charging station 20 forms a 100-volt charging path with two neutral lines N and a first 100-volt voltage line L1 in a single-phase three-wire wiring, and the charging station 60 has a single-phase three-wire. A 100 volt charging path was formed by two lines, a neutral line N and a second 100 volt voltage line L <b> 2. That is, as a 100-volt charging path to the first vehicle at the charging station, a path by two lines of the neutral line N and the first 100-volt voltage line L1 in the single-phase three-wire wiring, and to the second vehicle As a 100-volt charging path, a path with two neutral lines N and a second 100-volt voltage line L2 in a single-phase three-wire wiring was formed. Without being limited thereto, for example, the charging stand 20 forms a 100 volt charging path by two neutral wires N and the first 100 volt voltage line L1 in a single-phase three-wire wiring, and the charging stand 60 also It is also possible to form a 100-volt charging path with two neutral wires N and a first 100-volt voltage line L1 in a single-phase three-wire wiring.

  DESCRIPTION OF SYMBOLS 10 ... Vehicle charging system, 20 ... Charging stand, 21 ... Charge controller, 30 ... System power supply, 40 ... Vehicle, 42 ... Vehicle, 50 ... Main controller, 60 ... Charging stand, 70 ... Center, L1 ... First 100 volts Voltage line, L2 ... second 100 volt voltage line, MC2 ... magnetic contactor, MC3 ... magnetic contactor, N ... neutral wire.

Claims (4)

In the vehicle charging system that charges the vehicle by receiving power from the system power supply in the charging device,
In the charging apparatus that receives power supply by single-phase three-wire wiring, the power supply state by one of the 100-volt voltage line and the other 100-volt voltage line in the single-phase three-wire wiring and the single-phase three-wire wiring Switching means capable of switching between a neutral power line and a power supply state with two 100 volt voltage lines;
Switching control means for switching the switching means according to a change in charging environment;
A vehicle charging system comprising:   The vehicle charging system according to claim 1, wherein the switching control unit performs switching control of the switching unit based on the number of vehicles to be charged.   The vehicle charging system according to claim 1, wherein the switching control unit performs switching control of the switching unit based on power information from a center.   The vehicle charging system according to claim 1, wherein the switching control unit performs switching control of the switching unit based on power price information from a center.