Electrical power control system

Abstract

Electrical power control system, comprehensive: an electrical power supply system (20) which supplies alternating current power; a load (32); a power source switching unit (31) which is connected to the electrical power supply system (20) and the load (32), wherein the power source switching unit (31) switches a power source supplied to the load (32); a charging / discharging switching unit (41) which is connected to the electrical power supply system (20) via a charging line (53) and to the power source switching unit (31) via a discharging line (54); a conversion unit (12) which is connected to the charging / discharging switching unit (41) via a charging / discharging line (51); an electrical power storage device (11) connected to the conversion unit (12), wherein the conversion unit (12) converts the alternating current power supplied by the electrical power supply system (20) into direct current power and charges the electrical power storage device (11) with the direct current power when a charging condition is met, and the conversion unit (12) discharges the electrical power storage device (11) by converting the direct current power stored in the electrical power storage device (11) into alternating current power when a discharging condition is met; a discharge detection unit (42) which detects a state of the alternating current power converted by the conversion unit (12), wherein the alternating current power converted by the conversion unit (12) is referred to as a first alternating current power; a power input detection unit (43) which detects a state of the alternating current power supplied by the electrical power input system (20), wherein the alternating current power supplied by the electrical power input system (20) is referred to as a second alternating current power; a control unit (44) which controls the discharge detection unit (42) and the power input detection unit (43), the control unit (44) contains: a conversion control section (S130, S340) which controls the conversion unit (12) to convert the direct current power stored in the electrical power storage device (11) into the first alternating current power under a condition that the connection of the charging / discharging line (51) with the charging line (53) is disconnected; a detection control section (S130, S340) which, under the condition that the connection of the charging / discharging line (51) with the charging line (53) is disconnected, controls the discharge detection unit (42) to detect the state of the first AC power and which controls the power supply detection unit (43) to detect the state of the second AC power; a calculation section (S140, S350) which calculates a phase difference between a phase of the first AC power and a phase of the second AC power; a regulating section (S150, S360) which, provided that the connection of the charging / discharging line (51) with the charging line (53) is disconnected, reduces the phase difference by regulating the phase of the first AC power if the phase difference is greater than a predetermined threshold; and a switching control section (S160, S170, S370, S380) which: provided that the connection of the charging / discharging line (51) to the charging line (53) is disconnected, the power source switching unit (31) is controlled to connect the load (32) to the discharging line (54) when the discharging condition is met and the phase difference is equal to or less than the predetermined threshold; and the power source switching unit (31) controls the load (32) to connect the electrical power supply system (20) when the charging condition is met; and an additional control unit (13) which is communicatively connected to the control unit (44) and controls the conversion unit (12) on the basis of a first control signal (P1b) which is transmitted by the conversion control section (S130, S340) of the control unit (44), wherein the regulating section (S150, S360) generates a second control signal (P1c) which indicates the phase difference and has a frequency higher than a frequency of the first control signal (P1b), wherein the control unit (44) superimposes the second control signal (P1c) onto the first control signal (P1b) via a coupling element and transmits the first control signal (P1b) and the second control signal (P1c) to the auxiliary control unit (13) and the additional control unit (13) is provided separately from the control unit (44).

Description

TECHNICAL AREA

[0001] The present invention relates to an electrical power control system which provides electrical power to a load by discharging electrical power which is stored in an electrical power storage device. BACKGROUND

[0002] JP 2002 - 315 193 A discloses an electrical power control system that supplies electrical power stored in an electrical power storage device to a load located in a house. Specifically, the electrical power control system includes an AC / DC conversion unit located between the electrical power storage device and an electrical power supply system. Hereinafter, AC denotes alternating current, and DC denotes direct current. When an electrical power source of the load is switched from the electrical power supply system to the electrical power storage device, the conversion unit converts direct current, or direct current energy, stored in the electrical power storage device into alternating current power.This means that when the electrical power stored in the electrical power storage device is discharged, the DC power stored in the electrical power storage device is converted into AC power. The AC power is then supplied to the load.

[0003] However, in the electrical power control system described above, when the AC power discharged from the electrical power storage device and converted by the conversion unit is supplied to the load, one phase of the AC power from the electrical power storage device may differ significantly from one phase of the AC power supplied by the electrical power supply system. If the AC power from the electrical power storage device, which has a phase significantly different from the phase of the electrical power from the electrical power supply system, is supplied directly to the load, the AC power applied to the load changes abruptly, and a malfunction or defect may occur in the load.

[0004] German patent application DE 10 2012 202 130 A1 discloses an electrical power supply system with an ECU integrated into a charger. German patent application JP 2003 - 037 941 A discloses further prior art. SUMMARY

[0005] In view of the difficulties described above, an object of the present invention is to provide an electrical power control system which protects a load by limiting an adverse effect which occurs when an electrical power source of the load is switched between an electrical power storage device and an electrical power supply system.

[0006] The above problem is solved by an electrical power control system according to claim 1. Furthermore, the above problem is solved by an electrical power control system according to claim 3.

[0007] With the systems according to the invention, the adverse effect which occurs when an electrical power source is switched between the electrical power storage device and the electrical power supply system is limited, and the load is protected from the adverse effects.

[0008] Further advantageous embodiments are disclosed in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The foregoing and other problems, features and advantages of the present invention will become more apparent from the following detailed description, which is carried out with reference to the accompanying drawings. In the drawings: Fig. Figure 1 is a block diagram showing the structure of an electrical power control system according to an embodiment of the present invention; Fig. 2A is a diagram showing converted AC power before regulation, and Fig. 2B is a diagram showing the converted AC power after regulation, according to a first embodiment of the present invention; Fig. Figure 3 is a flowchart showing a procedure that is carried out by a setup control unit according to the first embodiment; Fig. Figure 4 is a flowchart showing a procedure performed by a vehicle control unit; Fig. 5A is a diagram showing converted AC power before regulation, and Fig. Figure 5B is a diagram showing the converted AC power after regulation, according to a second embodiment of the present invention; and Fig. Figure 6 is a flowchart showing a procedure that is carried out by a setup control unit according to the second embodiment. DETAILED DESCRIPTION

[0010] The following will describe examples of the present invention with reference to the drawings.

[0011] The following will describe an electrical power control system according to a first embodiment of the present invention. In the following description, AC refers to alternating current and DC refers to direct current. As in Fig. As shown in Figure 1, the electrical power control system according to the present invention comprises an electric drive vehicle (EC VH) 10, a house 30 which is equipped with the electrical power supply system (PW SUPPLY SYS) 20, and an electrical power charging and discharging device 40 for the electric drive vehicle 10. The electrical power charging and discharging device 40 is also referred to as a power control device (PW CONTROL) 40.

[0012] The electric drive vehicle 10 and the power control unit 40 are connected to a first electrical cable containing a charging / discharging line 51 and a communication line 52. The house 30 and the power control unit 40 are connected to a second electrical cable containing a charging line 53, a discharging line 54, and a communication line 55. The charging line 53 is connected to the electrical power supply system 20.

[0013] In the present embodiment, the communication line 52 can be provided by a CPLT line. Furthermore, in the present embodiment, the first electrical cable and the second electrical cable are contained in the power control unit 40. Thus, a user can connect the power control unit 40 to the electric drive vehicle 10 using the first electrical cable and connect the house 30 to the power control unit 40 using the second electrical cable.

[0014] The electric drive vehicle 10 can be an electric vehicle, a hybrid vehicle, or a fuel cell vehicle. As in Fig. As shown in Figure 1, the electric propulsion vehicle (EC VH) 10 includes an electrical power storage device (PW STORAGE) 11, an AC / DC conversion unit (CONVERSION) 12 and a control unit (CONTROL) 13. Hereinafter, the control unit 13 of the electric propulsion vehicle 10 is also referred to as a vehicle control unit 13.

[0015] The electrical power storage device 11 can be provided by a rechargeable battery such as a nickel-cadmium battery, nickel-hydrogen battery, lithium-ion battery, lithium battery and the like.

[0016] The AC / DC conversion unit 12 contains a converter that performs voltage regulation, frequency regulation, and phase regulation. For the sake of clarity, the AC / DC conversion unit 12 will be referred to as a conversion unit in the following description. The conversion unit 12 is connected to the electrical power storage device 11, the charging / discharging line 51, and the vehicle control unit 13. The conversion unit 12 receives control signals S1a and S1b, which are transmitted by the vehicle control unit 13. When the conversion unit 12 receives the control signal S1a from the vehicle control unit 13, the conversion unit 12 converts the alternating current power supplied from the electrical power supply system 20 via the charging / discharging line 51 into direct current or direct current power, and charges the electrical energy storage unit 11 with the direct current or direct current power.This means that the conversion unit 12 stores the direct current energy, which was converted from the alternating current energy supplied by the electrical power supply system 20, in the electrical power storage device 11. When the conversion unit 12 receives the control signal S1b from the vehicle control unit 13, the conversion unit 12 discharges the electrical power storage unit 11 by converting the direct current energy, which is charged (stored) in the electrical power storage device 11, into alternating current energy.

[0017] In the present embodiment, the conversion unit 12 converts the direct current or direct current power stored in the electrical power storage device 11 into alternating current or alternating current power, such that the alternating current power has the same voltage and frequency as the alternating current power supplied to the house 30 by the electrical power supply system 20. For example, if the alternating current power supplied by the electrical power supply system 20 has a voltage of 100 volts (V) and a frequency of 50 hertz (Hz), the alternating current energy converted from the direct current energy of the electrical power storage device 11 can have a voltage of 100 V and a frequency of 50 Hz.Furthermore, the conversion unit 12 can convert the direct current energy stored in the electrical power storage device 11 into alternating current energy, which has a voltage and frequency different from the voltage and frequency of the alternating current energy supplied by the electrical power supply system 20. Hereinafter, the alternating current power supplied by the electrical power supply system 20 is also referred to as system alternating current energy, and the alternating current power converted by the conversion unit 12 from the direct current energy stored in the electrical power storage device is also referred to as converted alternating current energy.

[0018] The vehicle control unit 13 contains a central processing unit (CPU), several memory modules that function as a storage device, and one or more peripheral devices. The vehicle control unit 13 is connectable to a control unit 44 of the power control device 40 via the communication line 52. Hereinafter, the control unit of the power control device 40 is also referred to as a device control unit 44. When the vehicle control unit 13 receives a control signal P1a from the device control unit 44, the vehicle control unit 13 transmits the control signal S1a to the conversion unit 12 to charge the electrical power storage device 11. When the vehicle control unit 13 receives a control signal P1b from the device control unit 44, the vehicle control unit 13 transmits the control signal S1b to the conversion unit 12 to discharge the electrical power storage device 11.When the vehicle control unit 13 receives a control signal P1c from the device control unit 44, the vehicle control unit 13 regulates the control signal S1b based on the control signal P1c and then transmits the regulated control signal S1b to the conversion unit 12. When the vehicle control unit 13 receives a request signal T1 from the device control unit 44, the vehicle control unit 13 determines whether the remaining power of the electrical power storage device 11 is greater than a threshold power. The vehicle control unit 13 then transmits a determination signal T2, indicating the result of the determination of the remaining power of the electrical power storage device 11, to the device control unit 44.

[0019] The threshold power can be expedited. For example, the threshold power can be set to 10% of the maximum charging capacity of the electrical power storage device 11. In the present embodiment, the vehicle control unit 13 is connected to the device control unit 44 via the communication line 52. Alternatively, the vehicle control unit 13 can be connected to the device control unit 44 via a wireless communication line. The vehicle control unit 13 functions as an auxiliary control unit of the electrical power control system.

[0020] As in Fig. As shown in Figure 1, house 30 contains a power source switching unit (PW switch) 31 and a load 32. The load 32 can contain domestic electrical applications commonly used in ordinary houses. Normally, the AC power is supplied to the load 32 from the electrical power supply system 20.

[0021] The power source switching unit 31 can be provided by a switching element such as a transistor. When the power source switching unit 31 receives a control signal P2a from the setup control unit 44, the power source switching unit 31 connects the load 32 to the electrical power supply system 20. When the power source switching unit 31 receives a control signal P2b from the setup control unit 44, the power source switching unit disconnects the load 32 from the electrical power supply system 20.

[0022] Provided that the load 32 is connected to the electrical power supply system 20, the power source switching unit 31 maintains a connection between the load 32 and the electrical power supply system 20 when the control signal P2a is transmitted by the setup control unit 44. Provided that the load 32 is connected to the discharge line 54, the power source switching unit 31 maintains a connection between the load 32 and the discharge line 54 when the control signal P2b is transmitted by the setup control unit 44.

[0023] As in Fig. As shown in Figure 1, the power control unit (PW CONTROL UNIT) 40 includes a charging / discharging switching unit (CHARGE UNCHARGE SWITCH) 41, a discharging detection unit (DISCHARGE DETECTION) 42, a power input detection unit (PW SUPPLY DETECTION) 43 and the device control unit 44.

[0024] The charge / discharge switching unit 41 can be provided by a switching element such as a transistor. When the charge / discharge switching unit 41 receives a control signal P3a from the setup control unit 44, the charge / discharge switching unit 41 connects the charge / discharge line 51 to the charge line 53. When the charge / discharge switching unit 41 receives a control signal P3b from the setup control unit 44, the charge / discharge switching unit 41 connects the charge / discharge line 51 to the charge line 54. That is, when the charge / discharge switching unit 41 receives a control signal P3b from the setup control unit 44, the charge / discharge switching unit 41 disconnects the connection between the charge / discharge line 51 and the charge line 53.

[0025] Provided that the charging / discharging line 51 is connected to the charging line 53, the charging / discharging switching unit 41 maintains a connection between the charging / discharging line 51 and the charging line 53 when a control signal P3a is transmitted from the setup control unit 44. Provided that the charging / discharging line 51 is connected to the discharging line 54, the charging / discharging switching unit 41 maintains a connection between the charging / discharging line 51 and the discharging line 54 when the control signal P3b is transmitted from the setup control unit 44.

[0026] The discharge detection unit 42 is connected to the charge / discharge line 51. When the discharge detection unit 42 receives a control signal P4 from the system control unit 44, it detects the state of the alternating current or power in the charge / discharge line 51. The system control unit 44 transmits the control signal P4 to the discharge detection unit 42 when it discharges the electrical power storage device 11. That is, the discharge detection unit 42 detects the state of the converted alternating current or power in the charge / discharge line 51.

[0027] Parameters of the converted AC power can be detected by the discharge detection unit 42 as the state of the converted AC energy, and the parameters are expediently changeable. In the present embodiment, the discharge detection unit 42 detects at least zero crossing points or frequency f1 of an AC voltage of the converted AC power.

[0028] The power supply sensing unit 43 is connected to the charging line 53. When the power supply sensing unit 43 receives a control signal P5 from the system control unit 44, it receives information about the system AC current or system AC power in the charging line 53. That is, the power supply sensing unit 43 detects the state of the AC power supplied by the electrical power supply system 20. The system control unit 44 transmits the control signal P5 to the power supply sensing unit 43 simultaneously with the control signal P4.

[0029] Parameters of the system AC current or system AC power can be detected by the power supply detection unit 43 as the state of the AC power, and the parameters can be conveniently changed. In the present embodiment, the power supply detection unit 43 detects at least zero crossing points or frequency f2 of an AC voltage of the system AC power.

[0030] The setup control unit 44 contains a CPU, several memory modules functioning as a single storage device, and one or more peripheral devices. The setup control unit 44 transmits the control signals P1a, P1b, and P1c to control the vehicle control unit 13; the control signals P2a and P2b to control the power source switching unit 31; the control signals P3a and P3b to control the charge / discharge switching unit 41; the control signal P4 to control the discharge sensing unit 42; and the control signal P5 to control the power supply sensing unit 43. The setup control unit 44 functions as a control unit of the electrical power control system.

[0031] When a charging period begins or an operation is performed by the user, the electrical power control system starts charging the electrical power storage device 11, and the device control unit 44 transmits the control signals P1a, P2a, and P3a. Specifically, when the electrical power control system starts charging the electrical power storage device 11, the device control unit 44 transmits the control signal P3a to the charge / discharge switching unit 41, so that the charge / discharge switching unit 41 connects the charge / discharge line 51 to the charge line 53. Furthermore, the device control unit 44 transmits the control signal P1a to the vehicle control unit 13.When the vehicle control unit 13 receives the control signal P1a, it transmits the control signal S1a to the conversion unit 12. The conversion unit 12 then converts the system alternating current, supplied via the charging line 53 and the charging / discharging line 51, into direct current power and charges the electrical power storage device 11 with this direct current power. Furthermore, the device control unit 44 transmits the control signal P2a to the power source switching unit 31, which then connects the load 32 to the electrical power supply system 20.

[0032] When a discharge period occurs or an operation is performed by the user, the electrical power control system supplies the electrical power stored in the electrical power storage device 11 to the load 32. That is, when the discharge period occurs or the operation is performed by the user, the electrical power control system discharges the electrical power storage device 11. In this case, the device control unit 44 transmits the control signals P1b, P3b, P4, and P5. Specifically, the device control unit 44 transmits the control signal P3b to the charge / discharge switching unit 41, so that the charge / discharge switching unit 41 connects the charge / discharge line 51 to the discharge line 54. Furthermore, the device control unit 44 transmits the control signal P1b to the vehicle control unit 13.In response to the control signal P1b, the vehicle control unit 13 transmits the control signal S1b to the conversion unit 12, so that the conversion unit 12 converts the direct current power stored in the electrical power storage device 11 into alternating current power.

[0033] The setup control unit 44 further transmits the control signal P4 to the discharge detection unit 42, so that the discharge detection unit 42 detects the state of the converted alternating current or the converted alternating current power in the charging / discharging line 51. The setup control unit 44 further transmits the control signal P5 to the power supply detection unit 43, so that the power supply detection unit 43 detects the state of the system alternating current or the system alternating current power in the charging line 53. Then, as described in Fig. As shown in Figure 2A, the setup control unit 44 receives a state detection result ST1 of the converted AC current or converted AC power PW1 from the discharge detection unit 42 and a state detection result ST2 of the system AC current or system AC power PW2, which is transmitted by the power input detection unit 43. The setup control unit 44 then calculates a phase difference PhD between a phase of the converted AC current or converted AC power and a phase of the system AC current or system AC power based on the state detection results.

[0034] If the phase difference is greater than a predetermined threshold, the control unit 44 transmits the control signal P1c, which indicates a phase difference greater than the threshold, to the vehicle control unit 13. For example, the control signal P1c may have a higher frequency than the control signal P1b, and the control signal P1c may be superimposed on the control signal P1b via a coupling element. The two control signals P1b and P1c are then transmitted together to the vehicle control unit 13 via a communication device. Here, the coupling element may be provided by a coupling capacitor. With this configuration, the control signal P1b is not affected by the control signal P1c. If the phase difference is greater than the threshold, the power source switching unit 31 outputs a switching signal SW1 to maintain the isolation state between the load 32 and the discharge line (DL) 54, as shown in Fig. 2A is shown. This means that the load 32 is kept in a connected state with the electrical power supply system (SYS) 20.

[0035] When the vehicle control unit 13 receives the control signal P1c from the facility control unit 44, the vehicle control unit 13 regulates the control signal S1b based on the control signal P1c and then transmits the control signal S1b to the conversion unit 12. Thus, as in Fig. As shown in Figure 2B, the regulated phase difference between the converted AC power and the system AC power is equal to or less than the threshold value. Furthermore, the vehicle control unit 13 can regulate the phase difference such that it becomes zero.

[0036] If the phase difference is equal to or less than the threshold value, the setup control unit 44 transmits the control signal P2b to the power source switching unit 31. In response to the control signal P2b, the power source switching unit 31 outputs a switching signal SW2 to connect the load 32 to the discharge line (DL) 54, as shown in Fig. Figure 2B shows that load 32 is disconnected from the electrical power supply system (SYS) 20. By connecting load 32 to discharge line 54, the converted AC power is supplied to load 32.

[0037] The phase difference threshold can be chosen to be equal to or less than the maximum value of a normal operating phase difference, below which the load 32 operates normally. The normal operating phase difference can be determined by monitoring the operation of the load 32 under various phase differences. For example, the threshold can be chosen as one hundredth of a frequency of the system AC current or system AC power. Since the normal operating phase difference is determined based on a monitoring result (operating history) of the load 32's operation, it is possible to select the phase difference threshold as an optimal value with respect to the load 32.

[0038] Furthermore, the user can select the charging and discharging periods. The user can choose these periods based on an electricity rate or tariff. For example, the user can select a charging period during a time when the electricity tariff is low, such as midnight. Similarly, the user can select a discharging period during a time when the electricity tariff is high, such as daytime.

[0039] The user can operate a liquid crystal control panel, with which the power control unit 40 or the housing 30 is equipped, to start charging or discharging the electrical power storage device 11. In the present embodiment, the operation performed by the user has a higher priority than the charging and discharging time periods selected or set by the user. For example, if the user performs an operation to discharge the electrical power storage device 11 at night, the electrical power control system performs the discharge of the electrical power storage device 11. Furthermore, the charging and discharging of the electrical power storage device 11 can be controlled solely by the user's operation without selecting the charging and discharging time periods.

[0040] The following describes a procedure executed by the electrical power control system. The procedure, executed by the electrical power control system, primarily describes the discharge of the electrical power storage device 11. Furthermore, the procedure is executed under the condition that the electric vehicle 10 is connected to the power control unit 40 via the charging / discharging line 51 and the communication line 52, and the house 30 is connected to the power control unit 40 via the charging line 53, the discharging line 54, and the communication line 55.

[0041] First, a procedure executed by the facility control unit 44 is described with reference to a [missing information]. Fig. The flowchart shown in section 3 is described. In the present embodiment, the flowchart shown in section 3 is described. Fig. The procedures shown in section 3 are executed by the control unit 44 at a predetermined time interval, such as every 5 minutes or every 30 minutes. When the user performs the operation to charge or discharge the electrical power storage device 11, the following occurs: Fig. The 3 procedures shown are executed directly by the setup control unit 44 in response to the operation performed by the user.

[0042] As in Fig. As shown in Figure 3, when the procedure starts, the setup control unit 44 at S100 determines whether the vehicle control unit 13 is connected to the setup control unit 44 and capable of communication. For example, the setup control unit 44 determines whether the charging / discharging line 51 and the communication line 52 are properly connected to the electric vehicle 10. Furthermore, the setup control unit 44 determines whether the charging line 53, the discharging line 54, and the communication line 55 are properly connected to the house 30.

[0043] If the system control unit 44 determines that the vehicle control unit 13 is connected to the system control unit 44 in a communication-capable manner (S100: YES), the system control unit 44 further determines at S110 whether the discharge of the electrical power storage device 11 is to be performed. For example, the system control unit 44 determines whether the discharge period begins or whether an operation is performed by the user. If the system control unit 44 determines that the operation is performed by the user, the system control unit 44 further determines whether the operation is an operation to discharge the electrical power storage device 11. Hereinafter, the operation to discharge the electrical power storage device 11 is also referred to as a discharge operation.In S110, if the user's discharge operation is performed during a time period outside the discharge time period, the discharge operation performed by the user is prioritized and the electrical power control system begins discharging the electrical power storage device 11.

[0044] If the control unit 44 determines that the electrical power storage device 11 is to be discharged (S110: YES), the control unit 44 further determines at S120 whether the electrical power storage device 11 is currently dischargeable. Specifically, the control unit 44 transmits the request signal T1 to the vehicle control unit 13 and receives the determination signal T2 from the vehicle control unit 13 to determine whether the electrical power storage device 11 is currently dischargeable. Specifically, when the vehicle control unit 13 receives the request signal T1 from the control unit 44, the vehicle control unit 13 determines whether the remaining power of the electrical power storage device 11 is greater than the threshold power.The vehicle control unit 13 then transmits the determination signal T2, which indicates whether the remaining power of the electrical power storage device 11 is greater than the threshold power, to the device control unit 44. If the remaining power of the electrical power storage device 11 is greater than the threshold power, the electrical power storage device 11 can be discharged.

[0045] If the system control unit 44 determines that the electrical power storage device 11 is currently dischargeable (S120: YES), the system control unit 44 transmits the control signal P1b to the vehicle control unit 13 and the control signal P3b to the charge / discharge switching unit 41. Furthermore, the system control unit 44 transmits the control signal P4 to the discharge detection unit 42 and the control signal P5 to the power supply detection unit 43. If the system control unit 44 determines that the vehicle control unit 13 is communicatively connected to the system control unit 44 (S100: YES), determines that the electrical power storage device 11 is to be discharged (S110: YES), and determines that the electrical power storage device 11 is currently dischargeable (S120: YES), a discharge condition for discharging the electrical power storage device is 11 fulfilled.

[0046] When the charging / discharging switching unit 41 receives the control signal P3b from the facility control unit 44, the charging / discharging switching unit 41 connects the charging / discharging line 51 to the discharging line 54. When the vehicle control unit 13 receives the control signal P1b from the facility control unit 44, the vehicle control unit 13 controls the conversion unit 12 so that the conversion unit 12 converts the DC power stored in the electrical power storage device 11 into AC power. When the discharging detection unit 42 receives the control signal P4 from the facility control unit 44, the discharging detection unit 42 detects the state of the converted AC current or the converted AC power in the charging / discharging line 51.When the power supply detection unit 43 receives the control signal P5 from the device control unit 44, the power supply detection unit 43 detects the state of the system alternating current or the system alternating current power in the charging line 53.

[0047] The setup control unit 44 then calculates the phase difference between the converted AC power and the system AC power based on the sensing results transmitted by the discharge sensing unit 42 and the power input sensing unit 43 at S140. The setup control unit 44 then determines whether the phase difference is equal to or less than the threshold (TH) at S140. If the setup control unit 44 determines that the phase difference is equal to or less than the threshold (S140: YES), it transmits the control signal P2b to the power source switching unit 31. When the power source switching unit 31 receives the control signal P2b, it connects the load 32 to the discharge line 54, so that the converted AC power is delivered to the load 32.

[0048] Furthermore, the power source switching unit 31 can switch the power source of the load 32 from the system AC power to the converted AC power at a zero-crossing point of the converted AC power or at a zero-crossing point of the system AC power. By converting the power source at the zero-crossing point of the converted AC power or the system AC power, it is less likely that the load will be affected by the switching of the power source. The zero-crossing point includes a point at which the converted AC power or the system AC power drops completely to zero and a point at which the converted AC power or the system AC power drops almost to zero.

[0049] If the setup control unit 44 determines that the phase difference is greater than the threshold (S140: NO), the setup control unit 44 transmits the control signal P1c to the vehicle control unit 13. When the vehicle control unit 13 receives the control signal P1c, the vehicle control unit 13 regulates the phase of the converted AC power so that the phase difference between the converted AC power and the system AC power is reduced.

[0050] If the system control unit 41 determines that the vehicle control unit 13 is not communicatively connected to the system control unit 44 (S100: NO), the system control unit 44 transmits the control signal P2a to the power source switching unit 31 at S170. Furthermore, if the system control unit 44 determines that the electrical power storage device 11 is not to be discharged (S110: NO), the system control unit 44 transmits the control signal P2a to the power source switching unit 31 at S170. Additionally, if the system control unit 44 determines that the electrical power storage device 11 cannot be discharged (S120: NO), the system control unit 44 transmits the control signal P2a to the power source switching unit 31 at S170. When the power source switching unit 31 receives the control signal P2a, the power source switching unit 31 connects the load 32 to the electrical power supply system 20.

[0051] If the system control unit 44 determines that the electrical power storage device 11 is not to be discharged (S110: NO), the system control unit 44 essentially performs the charging of the electrical power storage device 11. Furthermore, if the system control unit 44 determines that the electrical power storage device 11 cannot be discharged (S120: NO), the system control unit 44 essentially performs the charging of the electrical power storage device 11. Thus, the system control unit 44 transmits the control signals P1a, P2a, and P3a. Specifically, the system control unit 44 transmits the control signal P3a to the charge / discharge switching unit 41, so that the charge / discharge switching unit 41 connects the charge / discharge line 51 to the charge line 53.Furthermore, the system control unit 44 transmits the control signal P1a to the vehicle control unit 13, so that the vehicle control unit 13 controls the conversion unit 12 to convert the system AC energy into DC energy and charge the electrical power storage device 11 with the DC energy. The system control unit 44 also transmits the control signal P2a to the power source switching unit 31, so that the power source switching unit 31 connects the load 32 to the electrical power supply system 20. If the system control unit 44 determines that the electrical power storage device 11 is not to be discharged (S110: NO) or determines that the electrical power storage device 11 cannot be discharged (S120: NO), a charging condition of the electrical power storage device 11 is met.

[0052] As described above, if the setup control unit 44 transmits the control signals P1a to P5 to each unit 13, 31, 41, 42, 43 under the condition that each unit 13, 31, 41, 42, 43 is already in a state corresponding to the control signal P1a to P5, each unit 13, 31, 41, 42, 43 maintains the state corresponding to the control signal. For example, if the setup control unit 44 transmits the control signal P2a to the power source switching unit 31 at S170, under the condition that the load 32 is already connected to the power source supply system 20, the power source switching unit 31 maintains the connection state between the load 32 and the electrical power supply system 20.

[0053] The following describes a procedure executed by the vehicle control unit 13 with reference to a Fig. Describe the flowchart shown in Figure 4. When the vehicle control unit 13 receives the request signal T1 from the device control unit 44 at S120, the vehicle control unit 13 executes the procedure.

[0054] When the vehicle control unit 13 receives the request signal T1 from the device control unit 44 at S120, the vehicle control unit 13 determines at S200 whether the electrical power storage device 11 can be discharged. Specifically, the vehicle control unit 13 detects the remaining power of the electrical power storage device 11 and determines whether the remaining power of the electrical power storage device 11 is greater than the threshold power. Then, the vehicle control unit 13 transmits the determination signal T1, which indicates the result of the determination of the remaining power of the electrical power storage device 11, to the device control unit 44.

[0055] When the vehicle control unit 13 determines that the electrical power storage device 11 is dischargeable (S200: YES), the vehicle control unit 13 receives the control signal P1b from the device control unit 44 and transmits the control signal S1b to the conversion unit 12 in response to the control signal P1b at S210. When the conversion unit 12 receives the control signal S1b from the vehicle control unit 13, the conversion unit 12 converts the DC power stored in the electrical power storage device 11 into AC power.

[0056] At S220, the vehicle control unit 13 determines whether the control signal P1c, which is transmitted by the device control unit 44 at S150, is received at S220. If the vehicle control unit 13 receives the control signal P1c (S220: YES), the vehicle control unit 13 regulates the control signal S1b based on the control signal P1c and transmits the regulated control signal S1b to the conversion unit 12.

[0057] The regulated control signal S1b is a signal that delays the phase of the AC-converted power. By delaying the phase of the converted AC power, the phase difference between the converted AC power and the system AC power is reduced.

[0058] If the vehicle control unit 13 does not receive the control signal P1c (S220: NO), the vehicle control unit 13 terminates the procedure.

[0059] If the vehicle control unit 13 determines that the electrical power storage device 11 is not dischargeable (S200: NO), the vehicle control unit 13 receives the control signal P1a from the device control unit 44 and transmits the control signal S1a to the conversion unit 12. Then the conversion unit 12 converts the system AC power to DC power and charges the electrical power storage device 11 with the DC power.

[0060] In the present embodiment, the method executed by the setup control unit 44 at S130 functions as a detection control section and a conversion control section. The method executed by the setup control unit 44 at S140 functions as a calculation section. The method executed by the setup control unit 44 at S150 functions as a regulation section. The methods executed by the setup control unit 44 at steps S160 and S170 function as a switching control section. The converted AC power corresponds to a first AC power, and the system AC power corresponds to a second AC power. The control signal P1b corresponds to a first control signal, and the control signal P1c corresponds to a second control signal.

[0061] As described above, in the present embodiment, the state of the converted alternating current or converted alternating current power and the state of the system alternating current or system alternating current power are detected by the control unit 44. If the phase difference is equal to or less than the threshold value, the converted alternating current power is supplied to the load 32. Thus, it is less likely that the load 32 will be affected by the switching of the current or power source from the electrical power supply system 20 to the electrical power storage device 11. That is, if the power source of the load 32 is switched between the electrical power storage device 11 and the electrical power supply system 20, any adverse effect caused by the switching of the power source is limited, and accordingly, the load 32 is protected against such adverse effects.

[0062] The preceding description mainly describes the connection of the load 32 to the discharge line 54 when the load 32 is connected to the electrical power supply system 20. Similarly, the load 32 can be connected to the electrical power supply system 20 starting from a state in which the load 32 is connected to the discharge line 54. For example, when the discharge period switches to or changes from the charging period, the phase difference between the converted AC power and the system AC power can be regulated to equal to or less than the threshold value. Then, the power source switching unit 31 can switch between the connection between the load 32 and the discharge line 54 and the connection between the load 32 and the electrical power supply system 20.

[0063] In the present embodiment, as described above, the control unit 44 includes the conversion control section S130, the detection control section S130, the calculation section S140, the regulation section S150, and a switching control section S160. The conversion control section S130 controls the conversion unit 12 to convert the direct current or direct current power stored in the electrical power storage device 11 into the first alternating current or first alternating current power, provided that the charge / discharge line 51 is disconnected from the charging line 53. The detection control section S130 controls, provided that the charge / discharge

[0064] When line 51 is disconnected from charging line 53, the discharge detection unit 42 detects the state of the first AC power and controls the power input detection unit 43 to detect the state of the second AC power. The calculation section S140 calculates a phase difference between a phase of the first AC power and a phase of the second AC power. The regulation section S150 reduces the phase difference by regulating the phase of the first AC power, provided that the charging / discharging line 51 is disconnected from charging line 53, if the phase difference exceeds a predetermined threshold.The switching control section S160, provided that the charging / discharging line 51 is disconnected from the charging line 53, controls the power source switching unit 31 to connect the load 32 to the discharge line 54 when the discharge condition is met and the phase difference is equal to or less than the predetermined threshold. The switching control section S170 further controls the power source switching unit 31 to connect the load 32 to the electrical power supply system 20 when the charging condition is met.

[0065] Furthermore, in the present embodiment, the vehicle control unit 13 can function as the auxiliary control unit. The auxiliary control unit 13 is communicatively connected to the control unit 44 and controls the conversion unit 12 based on the first control signal P1b, which is transmitted by the conversion control section S130 of the control unit 44. The regulating section S150 generates the second control signal P1c, which indicates the phase difference and has a frequency higher than that of the first control signal P1b. The control unit 44 superimposes the second control signal P1c onto the first control signal P1b via the coupling element and transmits the first control signal P1b and the second control signal P1c together to the auxiliary control unit 13.

[0066] Furthermore, in the present embodiment, the switching control section S160 can control the power source switching unit 31 to connect the load 32 to the discharge line 54 at the zero crossing point of the first AC current or the first AC power, or at the zero crossing point of the second AC current or the second AC power. The switching control section S170 can control the power source switching unit 31 to connect the load 32 to the electrical power supply system 20 at the zero crossing point of the first AC power, or at the zero crossing point of the second AC power.

[0067] Furthermore, the detection control section S130 can control the discharge detection unit 42 to detect at least the AC voltage of the first AC power as the state of the first AC energy and to control the power supply detection unit 43 to detect at least the AC voltage of the second AC power as the state of the second AC energy.

[0068] Furthermore, as described above, the predetermined threshold value of the phase difference is set to be equal to or less than the maximum value of the normal operating phase difference, below which the load 32 performs normal operation.

[0069] The following describes an electrical power control system according to a second embodiment of the present invention with reference to Fig. 5A to Fig. 6 describe. In the present embodiment, the state of the system AC power supplied by the electrical power supply system 20 is detected before control signals P1b, P3b, P4 and a control signal P1d are transmitted. Other parts and the structure are similar to the electrical power control system according to the first embodiment. Furthermore, the structure of the electrical power control system according to the present embodiment is similar to the structure of the electrical power control system according to the first embodiment, as described in Fig. Figure 1 is shown. In the electrical power control system according to the first embodiment, the control unit 44 transmits the control signals P1a, P1b, P1c to the vehicle control unit 13. In the present embodiment, the control unit 44 transmits the control signals P1a, P1b, P1c, P1d to the vehicle control unit 13.

[0070] In the present embodiment, before the electrical power storage device 11 is discharged, the device control unit 44 initially transmits only the control signal P5 to the power supply detection unit 43. That is, as in Fig. As shown in Figure 5A, the power supply detection unit 43 detects the state of the system AC current or system AC power, and the device control unit 44 receives a state detection result ST2 of the system AC current or system AC power PW2 from the power supply detection unit 43. The device control unit 44 then generates a control signal P1d based on the state detection result ST2 and transmits the control signal P1d simultaneously with the control signal P1b to the vehicle control unit 13.

[0071] The control signal P1d can be a pulse signal synchronized with the system's AC power.

[0072] When the vehicle control unit 13 receives the control signal P1d, it regulates the control signal S1b based on the control signal P1d and transmits the regulated control signal S1b to the conversion unit 12. Thus, the conversion unit 12 is able to convert the DC power stored in the electrical power storage device 11 into AC power, which is similar to the system's AC energy, as described in [reference to relevant document]. Fig. 5B is shown.

[0073] The following describes a procedure that is executed by the facility control unit 44 with reference to a Fig. Describe the flowchart shown in section 6.

[0074] When the procedure starts, the facility control unit 44 determines at S300 whether the vehicle control unit 13 is connected to the facility control unit 44 and capable of communication. If the facility control unit 44 determines that the vehicle control unit 13 is connected to the facility control unit 44 and capable of communication (S300: YES), the facility control unit 44 determines at S310 whether the discharge of the electrical power storage device 11 is to be performed. If the facility control unit 44 determines that the discharge of the electrical power storage device 11 is to be performed (S310: YES), the facility control unit 44 determines at S320 whether the electrical power storage device 11 is currently dischargeable.

[0075] When the facility control unit 44 determines that the electrical power storage device 11 is currently dischargeable (S320: YES), the facility control unit 44 transmits the control signal P5 to the power input sensing unit 43 at S330. When the power input sensing unit 43 receives the control signal P5 from the facility control unit 44, the power input sensing unit 43 senses the state of the system AC power PW2 and outputs the state sensing result ST2 of the system AC power to the facility control unit 44, as shown in Fig. 5A is shown. At this time, since the control signal P1b has not yet been transmitted to the vehicle control unit 13, the conversion unit 12 has not yet started to convert the DC power stored in the electrical power storage device 11 into AC power. Thus, as shown in Fig. 5A is shown, the converted AC power PW1 and the state detection result ST1 of the converted AC power are both zero.

[0076] Then the setup control unit 44 receives the status detection result ST2 of the system alternating current energy PW2. In the S340, the control unit 44 transmits the control signals P1b and P1d to the vehicle control unit 13, the control signal P3b to the charging / discharging switching unit 41, and the control signal P4 to the discharge detection unit 42. When the vehicle control unit 13 receives the control signal P1b, it transmits the control signal S1b, which is regulated based on the control signal P1d, to the conversion unit 12. When the charging / discharging switching unit 41 receives the control signal P3b, it connects the charging / discharging line 51 to the discharge line 54. The conversion unit 12 then converts the power stored in the electrical power storage device 11 into alternating current based on the control signal S1b.When the discharge detection unit 42 receives the control signal P4, the discharge detection unit 42 detects the state of the converted AC power and outputs the state detection signal ST1 of the converted AC power PW1, as shown in . Fig. 5B is shown. Fig. 5B shows PW2 the system AC power at the time when the control signal P4 is detected by the discharge detection unit 42, and ST2 shows the state of the detection result of the system AC power at the time when the control signal P4 is received by the discharge detection unit 42.

[0077] The setup control unit 44 then calculates the phase difference PhD between the converted AC current or AC power and the system AC current or system AC power 20 based on the sensing results from the discharge sensing unit 42 and the power input sensing unit 43 at S350. The setup control unit 44 then determines at S350 whether the phase difference is equal to or less than the threshold value. If the setup control unit 44 determines that the phase difference is greater than the threshold value (S350: NO), it transmits the control signal P1c, indicating that the phase difference is greater than the threshold value, to the vehicle control unit 13 at S360.

[0078] If the setup control unit 44 determines that the phase difference is equal to or less than the threshold (S350: YES), the setup control unit 44 transmits the control signal P2b to the power source switching unit 31 at S370. When the power source switching unit 31 receives the control signal P2b, it connects the load 32 to the discharge line 54, so that the converted AC power is supplied to the load 32. Specifically, as in Fig. As shown in Figure 5B, the power source switching unit 31 outputs a switching signal SW2 to connect the load 32 to the discharge line (DL) 54. This means that the connection of the load 32 to the electrical power supply system (SYS) 20 is disconnected.

[0079] If the phase difference is greater than the threshold (S350: NO), the power source switching unit 31 outputs a switching signal SW1 to maintain the isolation state between the load 32 and the discharge line (DL) 54, as shown in Fig. 5A is shown. This means that the load 32 is held in a connected state with the electrical power supply system (SYS) 20.

[0080] If the setup control unit 44 determines that the vehicle control unit 13 is not communicatively connected to the setup control unit 44 (S300: NO), the setup control unit 44 transmits the control signal P2a to the power source switching unit 31 at S380. Furthermore, if the setup control unit 44 determines that the electrical power storage device 11 is not to be discharged (S310: NO), the setup control unit 44 transmits the control signal P2a to the power source switching unit 31 at S380. Furthermore, if the setup control unit 44 determines that the electrical power storage device 11 cannot be discharged (S320: NO), the setup control unit 44 transmits the control signal P2a to the power source switching unit 31 at S380. When the power source switching unit 31 receives the control signal P2a, the power source switching unit 31 connects the load 32 to the electrical power supply system 20.

[0081] In the method implemented by the vehicle control unit 13 according to the present embodiment, the vehicle control unit 13 transmits the control signal S1b to the conversion unit 12 in response to the control signal P1b, which is received at S210. In the present embodiment, the vehicle control unit 13 transmits the control signal S1b, which is regulated based on the control signal P1d, to the conversion unit 12. With this configuration, the conversion unit 12 is able to convert direct current or direct current power, which is stored in the electrical power storage device 11, into alternating current or alternating current power, the state of which is close to the state of the system's alternating current power.

[0082] In the present embodiment, the method executed by the control unit 44 at S330 functions as an additional sensing control section. The method executed by the control unit 44 at S340 functions as a conversion control section and a sensing control section. The method executed by the control unit 44 at S350 functions as a calculation section. The method executed by the control unit 44 at S360 functions as a regulation section. The method executed by the control unit 44 at S370 and S380 functions as a switching control section. The converted AC power corresponds to a first AC power, and the system AC power corresponds to a second AC power.The control signal P1b corresponds to a first control signal, the control signal P1c corresponds to a second control signal, and the control signal P1d corresponds to a third control signal.

[0083] As described above, when the electrical power control system performs the discharge of the electrical power storage device 11 according to the present embodiment, the electrical power control system can control the power supply sensing unit 43 to sense the state of the system AC power.

[0084] In the present embodiment, the control signal P1c is transmitted to the vehicle control unit 13 by superimposing it on the control signal P1b. Furthermore, similar to the control signal P1d, the control signal P1c can be transmitted to the vehicle control unit 13 via a pulse signal.

[0085] In the present embodiment, the control signal P1d is transmitted to the vehicle control unit 13 via the pulse signal. Furthermore, the control signal P1d can be transmitted to the vehicle control unit 13 by superimposing it on the control signal P1b.

[0086] In the present embodiment, the control unit 44 further includes the additional detection control section S330, which controls the power supply detection unit 43 to detect the state of the second alternating current or the second alternating current power before the conversion unit 12 converts the direct current energy stored in the electrical power storage device 11 into the first alternating current power. The additional detection control section S330 outputs the detection result, which indicates the state of the second alternating current power before the conversion unit 12 converts the direct current power stored in the electrical power storage device 11 into the first alternating current power, to the conversion control section S340.The conversion control section S340 controls the conversion unit 12 to convert the DC power charged in the electrical power storage device 11 into the first AC power, based on the detection result output by the additional detection control section S330, so that the phase difference between the phase of the first AC power and the phase of the second AC power is reduced.

[0087] Furthermore, in the present embodiment, the additional detection control section S330 outputs the detection result of the state of the second AC power supply to the conversion control section S340. The conversion control section S340 generates the third control signal P1d based on the detection result output by the additional detection control section S330 and can transmit the first control signal P1b and the third control signal P1d to the auxiliary control unit 13 via the pulse signal.

[0088] In the preceding embodiments, the power control unit 40 is arranged between the electric vehicle 10 and the house 30. Furthermore, the power control unit 40 can be integrated into the house 30. That is, the power control unit 40 can be contained within the house 30.

[0089] The electrical power storage device 11 and the conversion unit 12 can be located in the housing 30 differently than in the electric vehicle 10. That is, the power control unit 40 can be integrated into the housing 30, and the electrical power storage device 11 and the conversion unit 12 can be located in the housing 30. In this case, the housing 30 can contain a control unit corresponding to the vehicle control unit 13.

[0090] In the preceding embodiments, the control unit 44 controls the conversion unit 12 via the vehicle control unit 13. Furthermore, the control unit 44 can directly control the conversion unit 12. Specifically, if the electrical power control system includes the electrical power storage device 11 and the conversion unit 12, which are located in the house 30, the electrical power storage device 11 and the conversion unit 12 can be controlled by the control unit 44 alone.

[0091] In the preceding embodiments, the first electrical cable, which contains the charging / discharging line 51 and the communication line 52, is contained in the power control unit 40. The second electrical cable, which contains the charging line 53, the discharging line 54, and the communication line 55, is also contained in the power control unit 40. Alternatively, the first electrical cable can be contained in the electric vehicle 10, and the second electrical cable can be contained in the house 30.

[0092] In the preceding embodiments, the discharge detection unit 42 is connected to the charge / discharge line 51. Furthermore, the discharge detection unit 42 can be connected to the discharge line 54 if the discharge line 54 is connected to the charge / discharge line 51. Specifically, if the charge / discharge line 51 is connected to the discharge line 54, and the discharge detection unit 42 is also connected to the discharge line 54, the discharge detection unit 42 is also able to detect the state of the converted AC power.

[0093] In the foregoing embodiments, it is necessary that the discharge detection unit 42 detects the state of the converted alternating current or the converted alternating current power under a condition that the discharge detection unit 42 is connected to the charge / discharge line 51, that the charge / discharge line 51 is disconnected from the charge line 53, and that the charge / discharge line 51 can be connected to or disconnected from the discharge line 54.

[0094] In the preceding embodiments, the control unit 44 transmits the control signal P1c to the vehicle control unit 13 when the phase difference between the converted AC current or AC power and the system AC current or system AC power is greater than the threshold value. Furthermore, the control signal P1c can be generated by the control unit according to the phase difference, and the control unit can transmit the control signal P1c, which corresponds to the phase difference, to the vehicle control unit 13. That is, if the phase difference is zero, the control unit 44 can generate and transmit the control signal P1c, which indicates a phase difference of zero.In this case, the setup control unit 44 transmits the phase difference at S140 or S350, and then transmits the control signal P1c, which corresponds to the phase difference, to the vehicle control unit 13. Since the vehicle control unit 13 receives the control signal P1c from the setup control unit 44 at S220 unconditionally, the vehicle control unit 13 can terminate the procedure if the control signal P1c indicates that the phase difference is equal to or less than the threshold, and can proceed to S230 if the control signal P1c indicates that the phase difference is greater than the threshold.

[0095] In the preceding embodiments, the discharge detection unit 42 and the power supply detection unit 43 can be configured to detect an alternating voltage, an alternating current, and a waveform of the AC power, and to transmit each of the detection results as the control signal P1c. The vehicle control unit 13 can then regulate the control signal S1b based on the detection results transmitted by the discharge detection unit 42 and the power supply detection unit 43. This configuration increases the regulation accuracy of the AC current or AC power, which is converted by the conversion unit 12.

[0096] When the discharge detection unit 42 and the power supply detection unit 43 detect the alternating voltage and alternating current, the power source switching unit 31 can switch the connection between the load 32 and the electrical power supply system 20, or between the load 32 and the discharge line 54, as follows (S160, S370). When the alternating current supplied by the electrical power supply system 20 is zero, the power source switching unit 31 can switch the connection between the load 32 and the electrical power supply system 20 to the connection between the load 32 and the discharge line 54.

[0097] Furthermore, if the alternating current supplied by the electrical power supply system 20 is zero, the power source switching unit 31 can disconnect the load 32 from the electrical power supply system 20. Then, if the alternating current converted by the conversion unit 12 is zero, the power source switching unit 31 can connect the load 32 to the discharge line 54.

[0098] In the second embodiment of the present invention, the power supply detection unit 43 can detect the alternating voltage, the alternating current, and the waveform of the alternating current supplied from the electrical power supply system 20. The power supply detection unit 43 can then transmit each of these detection results to the vehicle control unit 13 as the control signal P1d. In this case, all of the detection results can be transmitted to the vehicle control unit 13 by changing the relative duty cycle of the pulse signal P1d or by changing the potential of the pulse signal P1d.

[0099] While only the selected exemplary embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this invention that a wide variety of changes and modifications can be made to it without deviating from the scope of the invention as specified in the attached claims.

Claims

[1] An electrical power control system comprising: an electrical power supply system (20) which supplies alternating current (AC) power; a load (32); a power source switching unit (31) connected to the electric power supply system (20) and the load (32), the power source switching unit (31) switching a power source supplied to the load (32); a charge / discharge switching unit (41) connected to the electric power supply system (20) via a charge line (53) and connected to the power source switching unit (31) via a discharge line (54); a conversion unit (12) connected to the charge / discharge switching unit (41) via a charge / discharge line (51); an electric power storage device (11) connected to the conversion unit (12), wherein the conversion unit (12) converts the alternating current power supplied from the electric power supply system (20) into direct current (DC) power and charges the electric power storage device (11) with the direct current power when a charging condition is met, and the conversion unit (12) discharges the electric power storage device (11) by converting the direct current power stored in the electric power storage device (11) into alternating current power when a discharging condition is met; a discharge detection unit (42) which detects a state of the AC power converted by the conversion unit (12), wherein the AC power converted by the conversion unit (12) is referred to as a first AC power; a power supply detection unit (43) which detects a state of the AC power supplied from the electric power supply system (20), wherein the AC power supplied from the electric power supply system (20) is referred to as a second AC power; a control unit (44) which controls the discharge detection unit (42) and the power supply detection unit (43), wherein the control unit (44) contains: a conversion control section (S130, S340) which controls the conversion unit (12) to convert the direct current power stored in the electric power storage device (11) into the first alternating current power under a condition that the connection of the charging / discharging line (51) to the charging line (53) is disconnected; a detection control section (S130, S340) which, under the condition that the connection of the charge / discharge line (51) to the charge line (53) is disconnected, controls the discharge detection unit (42) to detect the state of the first AC power and which controls the power supply detection unit (43) to detect the state of the second AC power; a calculation section (S140, S350) which calculates a phase difference between a phase of the first AC power and a phase of the second AC power; a regulating section (S150, S360) which, under the condition that the connection of the charging / discharging line (51) to the charging line (53) is disconnected, reduces the phase difference by regulating the phase of the first AC power when the phase difference is greater than a predetermined threshold; and a switching control section (S160, S170, S370, S380) which: under the condition that the connection of the charge / discharge line (51) to the charge line (53) is disconnected, controlling the power source switching unit (31) to connect the load (32) to the discharge line (54) when the discharge condition is satisfied and the phase difference is equal to or less than the predetermined threshold value; and the power source switching unit (31) controls to connect the load (32) to the electric power supply system (20) when the charging condition is met; and an additional control unit (13) which is communicatively connected to the control unit (44) and controls the conversion unit (12) on the basis of a first control signal (P1b) transmitted from the conversion control section (S130, S340) of the control unit (44), wherein the regulating section (S150, S360) generates a second control signal (P1c) indicating the phase difference and having a frequency higher than a frequency of the first control signal (P1b), wherein the control unit (44) superimposes the second control signal (P1c) on the first control signal (P1b) via a coupling element and transmits the first control signal (P1b) and the second control signal (P1c) to the additional control unit (13) and the additional control unit (13) is provided separately from the control unit (44). [2] Electric power control system according to claim 1, wherein the control unit (44) further includes an additional detection control section (S330) which controls the power supply detection unit (43) to detect the state of the second AC power before the conversion unit (12) converts the DC power charged in the electric power storage device (11) into the first AC power; wherein the additional detection control section (S330) outputs a detection result indicating the state of the second AC power before the conversion unit (12) converts the DC power charged in the electric power storage device (11) into the first AC power to the conversion control section (S340), and wherein the conversion control section (S340) controls the conversion unit (12) to convert the direct current power charged in the electric power storage device (11) into the first alternating current power based on the detection result output from the additional detection control section (S330) so that the phase difference between the phase of the first alternating current power and the phase of the second alternating current power is reduced. [3] Electrical power control system comprising: an electrical power supply system (20) which supplies alternating current (AC) power; a load (32); a power source switching unit (31) connected to the electric power supply system (20) and the load (32), the power source switching unit (31) switching a power source supplied to the load (32); a charge / discharge switching unit (41) connected to the electric power supply system (20) via a charge line (53) and connected to the power source switching unit (31) via a discharge line (54); a conversion unit (12) connected to the charge / discharge switching unit (41) via a charge / discharge line (51); an electric power storage device (11) connected to the conversion unit (12), wherein the conversion unit (12) converts the alternating current power supplied from the electric power supply system (20) into direct current (DC) power and charges the electric power storage device (11) with the direct current power when a charging condition is met, and the conversion unit (12) discharges the electric power storage device (11) by converting the direct current power stored in the electric power storage device (11) into alternating current power when a discharging condition is met; a discharge detection unit (42) which detects a state of the AC power converted by the conversion unit (12), wherein the AC power converted by the conversion unit (12) is referred to as a first AC power; a power supply detection unit (43) which detects a state of the AC power supplied from the electric power supply system (20), wherein the AC power supplied from the electric power supply system (20) is referred to as a second AC power; and a control unit (44) which controls the discharge detection unit (42) and the power supply detection unit (43), wherein the control unit (44) contains: a conversion control section (S130, S340) which controls the conversion unit (12) to convert the direct current power stored in the electric power storage device (11) into the first alternating current power under a condition that the connection of the charging / discharging line (51) to the charging line (53) is disconnected; a detection control section (S130, S340) which, under the condition that the connection of the charge / discharge line (51) to the charge line (53) is disconnected, controls the discharge detection unit (42) to detect the state of the first AC power and which controls the power supply detection unit (43) to detect the state of the second AC power; a calculation section (S140, S350) which calculates a phase difference between a phase of the first AC power and a phase of the second AC power; a regulating section (S150, S360) which, under the condition that the connection of the charging / discharging line (51) to the charging line (53) is disconnected, reduces the phase difference by regulating the phase of the first AC power when the phase difference is greater than a predetermined threshold; and a switching control section (S160, S170, S370, S380) which: under the condition that the connection of the charge / discharge line (51) to the charge line (53) is disconnected, controlling the power source switching unit (31) to connect the load (32) to the discharge line (54) when the discharge condition is satisfied and the phase difference is equal to or less than the predetermined threshold value; and the power source switching unit (31) controls to connect the load (32) to the electric power supply system (20) when the charging condition is met; wherein the control unit (44) further includes an additional detection control section (S330) which controls the power supply detection unit (43) to detect the state of the second AC power before the conversion unit (12) converts the DC power charged in the electric power storage device (11) into the first AC power; wherein the additional detection control section (S330) outputs a detection result indicating the state of the second AC power before the conversion unit (12) converts the DC power charged in the electric power storage device (11) into the first AC power to the conversion control section (S340), wherein the conversion control section (S340) controls the conversion unit (12) to convert the direct current power stored in the electric power storage device (11) into the first alternating current power based on the detection result output by the additional detection control section (S330) so that the phase difference between the phase of the first alternating current power and the phase of the second alternating current power is reduced, wherein the electric power control system further comprises an auxiliary control unit (13) which is communicatively connected to the control unit (44) and controls the conversion unit (12) on the basis of a first control signal (P1b) transmitted from the conversion control section (S340) of the control unit (44), wherein the additional detection control section (S330) outputs a detection result of the state of the second AC power to the conversion control section (S340), wherein the conversion control section (S340) generates a third control signal (P1d) based on the detection result transmitted from the additional detection control section (S330), and transmits the first control signal (P1b) and the third control signal (P1d) to the additional control unit (13) via a pulse signal, and the additional control unit (13) is provided separately from the control unit (44). [4] Electric power control system according to any one of claims 1 to 3, wherein the switching control section (S160, S370) controls the power source switching unit (31) to connect the load (32) to the discharge line (54) at a zero-crossing point of the first AC power or at a zero-crossing point of the second AC power, and wherein the switching control section (S170, S380) switches the power source switching unit (31) to connect the load (32) to the electric power supply system (20) at the zero-crossing point of the first AC power or at the zero-crossing point of the second AC power. [5] Electric power control system according to any one of claims 1 to 4, wherein the detection control section (S130, S340) controls the discharge detection unit (42) to detect at least one AC voltage of the first AC power as the state of the first AC power, and wherein the detection control section (S130, S340) controls the power supply detection unit (43) to detect at least an AC voltage of the second AC power as the state of the second AC power. [6] Electric power control system according to any one of claims 1 to 5, wherein the predetermined threshold value of the phase difference is selected to be equal to or less than a maximum value of a normal operation phase difference, and wherein the normal operation phase difference is a phase difference under which the load (32) performs normal operation.

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