Charge and discharge control device, charge control method, discharge control method, and program

When power required by a load is larger than or equal to reception peak-cut power, a secondary battery discharges at a power rate that is larger or equal to a difference between the required power and the reception peak-cut power, and when the required power is smaller than or equal to the reception peak-cut power, the secondary battery discharges at a power rate that is smaller than or equal to the discharge improving power value. When power generated by the load is larger than or equal to transmission peak-cut power, the secondary battery charges at a power rate that is larger or equal to a difference between the regenerative power and the transmission peak-cut power, and when the regenerative power is smaller than or equal to the transmission peak-cut power, the secondary battery charges at a power rate that is smaller than or equal to the charge improving power value.

TECHNICAL FIELD

The present invention relates to a charge and discharge control device, a charge control method, a discharge control method, and a program for controlling charge and discharge of a secondary battery to be coupled to a load capable of generating the regenerative power.

Priority is claimed on Japanese Patent Application No. 2011-269937, filed Dec. 9, 2011, the content of which is incorporated herein by reference.

BACKGROUND ART

Conventionally, vehicles running with the power supplied from wires are known. The power required for such a vehicle to run (running power) differs depending on environments, such as slopes of rails on which the vehicle runs. For this reason, the capacity and power consumption of a substation supplying the power to wires are determined based on a variation of the voltage caused by the running power.

Additionally, when such a vehicle brakes and thereby causes the regenerative power to be generated, the regenerative power is fed to the wires to prevent a regenerative failure. The regenerative power fed to the wires is collected by the substation. For this reason, an interval at which substations are to be installed is determined based on a variation of the voltage caused by the regenerative power.

In order to reduce costs for a traffic system by decreasing the number of substations to be installed, suppression of the peaks of the running power and the regenerative power (peak cut) has been considered. As a method of cutting the peaks of the running power and the regenerative power, there is a method in which a secondary battery is mounted on a vehicle to absorb the regenerative power and supplement the running power.

In order to adequately cut the peak of the power, it is necessary to adequately manage a charging rate of the secondary battery.

Patent Document 1 discloses a method of performing a charge so that a charging rate varies within an adequate range of the charging rate, thereby preventing a secondary battery mounted on a wire-less vehicle from deteriorating.

Patent Document 2 discloses a method of controlling a charging rate of a secondary battery mounted on a wire-less vehicle.

CITATION LIST

Patent Document

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

However, the methods disclosed by Patent Documents 1 and 2 are used to adjust the charging rate of the secondary battery in order to enable the vehicle to run in wire-less intervals. Both documents fail to disclose a method of adjusting the charging rate of the secondary battery while performing a peak cutting process.

An object of the present invention is to provide a charge and discharge control device, a charge control method, a discharge control method, and a program for adjusting a charging rate of a secondary battery while performing a peak cutting process.

Means for Solving the Problems

The present invention has been made to solve the above problem. The present invention is a charge and discharge control device configured to control charge and discharge of a secondary battery coupled to a load capable of generating a regenerative power. The charge and discharge control device includes a peak cutting unit configured to, in a case that a required power required by the load is larger than or equal to a reception peak-cut power set as a power receivable from a wire, have the secondary battery discharged at a power rate that is larger or equal to a difference between the required power and the reception peak-cut power; an improving power value calculating unit configured to calculate a discharge improving power value defined as a power value that increases as a charging rate of the secondary battery becomes larger than a target charging rate; and a charging rate improving unit configured to, in a case that the required power is smaller than or equal to the reception peak-cut power, have the secondary battery discharged at a power rate that is smaller than or equal to the discharge improving power value calculated by the improving power value calculating unit.

Additionally, regarding the present invention, the peak cutting unit is preferably configured to have the secondary battery discharged at a power rate equal to the discharge improving power value, in a case that the required power is larger than or equal to the reception peak-cut power, and the discharge improving power value is larger than or equal to a value of a difference between the required power and the reception peak-cut power.

Further, regarding the present invention, the peak cutting unit is preferably configured to have the secondary battery discharged at a power rate that is smaller than a maximum discharge power value for discharge allowed by the secondary battery.

Moreover, regarding the present invention, the charge and discharge control device preferably further includes a discharge terminating unit configured to terminate discharge by the peak cutting unit in a case that the charging rate of the secondary battery is smaller than a minimum charging rate allowed to the secondary battery.

Additionally, regarding the present invention, the peak cutting unit is preferably configured to, in a case that a regenerative power generated by the load is larger than or equal to a transmission peak-cut power set as a power transmittable to a wire, have the secondary battery charged at a power rate that is larger than or equal to a difference between the regenerative power and the transmission peak-cut power. The improving power value calculating unit is preferably configured to calculate a charge improving power value defined as a power value that increases as the charging rate of the secondary battery becomes lower than the target charging rate of the secondary battery. The charging rate improving unit is preferably configured to, in a case that the regenerative power is smaller than or transmission peak-cut power, have the secondary battery charged at a power rate that is smaller than or equal to the charge improving power value calculated by the improving power value calculating unit.

Further, regarding the present invention, the peak cutting unit is preferably configured to have the secondary battery charged at a power rate equal to the charge improving power value, in a case that the regenerative power is larger than or equal to the transmission peak-cut power, and the charge improving power value is larger than or equal to a difference between the regenerative power and the transmission peak-cut power.

Moreover, regarding the present invention, the peak cutting unit is preferably configured to have the secondary battery charged at a power rate that is smaller than a maximum charge power value for charge allowed by the secondary battery.

Additionally, regarding the present invention, the charge and discharge control device preferably further includes a charge terminating unit configured to terminate charge by the peak cutting unit in a case that the charging rate of the secondary battery exceeds a maximum charging rate allowed to the secondary battery.

Further, the present invention is a charge and discharge control device configured to control charge and discharge of a secondary battery coupled to a load capable of generating a regenerative power. The charge and discharge control device includes: a peak cutting unit configured to, in a case that a regenerative power generated by the load is larger than or equal to a transmission peak-cut power set as a power transmittable to a wire, have the secondary battery charged at a power rate that is larger or equal to a difference between the regenerative power and the transmission peak-cut power; an improving power value calculating unit configured to calculate a charge improving power value defined as a power value that increases as a charging rate of the secondary battery becomes smaller than a target charging rate; and a charging rate improving unit configured to, in a case that the regenerative power is smaller than or equal to the transmission peak-cut power, have the secondary battery charged at a power rate that is smaller than or equal to the charge improving power value calculated by the improving power value calculating unit.

Moreover, regarding the present invention, the peak cutting unit is preferably configured to have the secondary battery charged at a power rate equal to the charge improving power value, in a case that the regenerative power is larger than or equal to the transmission peak-cut power, and the charge improving power value is larger than or equal to a value of a difference between the regenerative power and the transmission peak-cut power.

Additionally, the present invention is a charge and discharge control method using a charge and discharge control device configured to control charge and discharge of a secondary battery coupled to a load capable of generating a regenerative power. The charge and discharge control method includes: in a case that a required power required by the load is larger than or equal to a reception peak-cut power set as a power receivable from a wire, a peak cutting unit having the secondary battery discharged at a power rate that is larger or equal to a difference between the required power and the reception peak-cut power; an improving power value calculating unit calculating a discharge improving power value defined as a power value that increases as a charging rate of the secondary battery becomes larger than a target charging rate; and in a case that the required power is smaller than or equal to the reception peak-cut power, a charging rate improving unit having the secondary battery discharged at a power rate that is smaller than or equal to the discharge improving power value calculated by the improving power value calculating unit.

Further, the present invention is a charge and discharge control method using a charge and discharge control device configured to control charge and discharge of a secondary battery coupled to a load capable of generating a regenerative power. The charge and discharge control device includes: in a case that a regenerative power generated by the load is larger than or equal to a transmission peak-cut power set as a power transmittable to a wire, a peak cutting unit having the secondary battery charged at a power rate that is larger or equal to a difference between the regenerative power and the transmission peak-cut power; an improving power value calculating unit calculating a charge improving power value defined as a power value that increases as a charging rate of the secondary battery becomes smaller than a target charging rate; and in a case that the regenerative power is smaller than or equal to the transmission peak-cut power, a charging rate improving unit having the secondary battery charged at a power rate that is smaller than or equal to the charge improving power value calculated by the improving power value calculating unit.

Moreover, the present invention is a program to cause a charge and discharge control device configured to control charge and discharge of a secondary battery coupled to a load capable of generating a regenerative power, to function as: a peak cutting unit configured to, in a case that a required power required by the load is larger than or equal to a reception peak-cut power set as a power receivable from a wire, have the secondary battery discharged at a power rate that is larger or equal to a difference between the required power and the reception peak-cut power; an improving power value calculating unit configured to calculate a discharge improving power value defined as a power value that increases as a charging rate of the secondary battery becomes larger than a target charging rate; and a charging rate improving unit configured to, in a case that the required power is smaller than or equal to the reception peak-cut power, have the secondary battery discharged at a power rate that is smaller than or equal to the discharge improving power value calculated by the improving power value calculating unit.

Additionally, the present invention is a program to cause a charge and discharge control device configured to control charge and discharge of a secondary battery coupled to a load capable of generating a regenerative power, to function as: a peak cutting unit configured to, in a case that a regenerative power generated by the load is larger than or equal to a transmission peak-cut power set as a power transmittable to a wire, have the secondary battery charged at a power rate that is larger or equal to a difference between the regenerative power and the transmission peak-cut power; an improving power value calculating unit configured to calculate a charge improving power value defined as a power value that increases as a charging rate of the secondary battery becomes smaller than a target charging rate; and a charging rate improving unit configured to, in a case that the regenerative power is smaller than or equal to the transmission peak-cut power, have the secondary battery charged at a power rate that is smaller than or equal to the charge improving power value calculated by the improving power value calculating unit.

Effects of the Invention

According to the present invention, a peak cutting process is performed using a secondary battery when the required power or the regenerative power is larger than or equal to the peak cut power. When the required power or the regenerative power is smaller than the peak cut power, the charging rate of the secondary battery is improved. Thus, it is possible to adjust the charging rate of the secondary battery while performing a peak cut process.

BEST MODE FOR CARRYING OUT THE INVENTION

First Embodiment

FIG. 1is a schematic block diagram illustrating a configuration of a vehicle100including a charge and discharge control device150according to a first embodiment of the present invention.

The vehicle100of the present embodiment includes an inverter110, a load120, a DC-DC converter130, a secondary battery140, and a charge and discharge control device150.

The inverter110converts into the alternate-current power, the direct-current power supplied from a wire200and the direct-current power supplied from the secondary battery140via the DC-DC converter130.

The load120has the vehicle100run using the alternate-current power converted by the inverter110. Additionally, the load120has the vehicle100perform regenerative braking, thereby causing the regenerative power to be generated. The regenerative power is fed to the wire200and the secondary battery140via the inverter110.

The DC-DC converter130converts the voltage of the power supplied from the wire200and the load120and the voltage of the power supplied from the secondary battery140.

The secondary battery140is coupled to the wire200and the load120via the DC-DC converter130. The secondary battery140is charged using the power supplied from the wire200and the load120. Additionally, the secondary battery140supplies the power to the load120via the DC-DC converter130.

The charge and discharge control device150is a device that controls charge and discharge of the secondary battery140. The charge and discharge control device150includes a load power monitoring unit151, a mode control unit152, a peak cutting unit153, a charging rate monitoring unit154, an improving power value calculating unit155, and a charging rate improving unit156.

The load power monitoring unit151monitors the required power required for the load120to have the vehicle run, and a value of the regenerative power generated by the load120. Hereinafter, the required power and the regenerative power are collectively referred to as the “load power”.

The mode control unit152changes, based on the load power, a control mode that controls charge and discharge of the secondary battery140to one of a wire preferred mode or a battery preferred mode. The wire preferred mode is a mode that prefers to use a power supply from the wire200. The battery preferred mode is a mode that prefers to improve charging rate of the secondary battery140.

The peak cutting unit153, when the control mode is set to the wire preferred mode, outputs to the DC-DC converter130, an instruction to control the amount of power by which the secondary battery140is charged or discharged, so that the power received from or fed to the wire200does not exceed a predetermined peak-cut power. Specifically, when the vehicle100is running, the peak cutting unit153outputs a discharge instruction to have the secondary battery140discharged at a power rate equal to a value of a difference between the required power and the reception peak-cut power that is the maximum value of the power receivable from the wire200. On the other hand, when the vehicle100is braking, the peak cutting unit153outputs a charge instruction to have the secondary battery140charged at a power rate equal to a value of a difference between the regenerative power and the transmission peak-cut power that is the maximum value of the power transmittable to the wire200.

The charging rate monitoring unit154monitors a charging rate of the secondary battery140. The monitoring of the secondary battery140can be performed by measuring the open circuit voltage of the secondary voltage140and specifying the charging rate associated with the open circuit voltage.

The improving power value calculating unit155calculates an improving power value representing a power value required to have the charging rate of the secondary battery140reach a predetermined target charging rate. Here, calculation of the improving power value is performed by PI control. Here, as a difference between the charging rate of the secondary battery140and the target charging rate becomes larger, the improving power value becomes larger. Specifically, when the charging rate of the secondary battery140is larger than the target charging rate, the improving power value used to discharge the secondary battery140(discharge improving power value) increases as the difference between the charging rate of the secondary battery140and the target charging rate increases. On the other hand, when the charging rate of the secondary battery140is smaller than the target charging rate, the improving power value used to charge the secondary battery140(charge improving power value) increases as the difference between the charging rate of the secondary battery140and the target charging rate increases.

The charging rate improving unit156, when the control mode is set to the battery preferred mode, outputs to the DC-DC converter130, an instruction to control the power rate at which the secondary battery140is charged or discharged, based on the improving power value.

Next, processing of the charge and discharge control device150according to the present embodiment is described.

FIG. 2is a flowchart illustrating the processing of the charge and discharge control device150according to the first embodiment of the present invention.

When a train initiates running, the load power monitoring unit151obtains the load power (step S1). Then, the load power monitoring unit151determines whether the load120is under a running operation or a braking operation (step S2).

If the load power monitoring unit151determines that the load120is under the running operation (step S2: YES), the mode control unit152determines whether or not the required power is larger than the preset reception peak-cut power (step S3). If the mode control unit152determines that the required power is larger than the preset reception peak-cut power (step S3: YES), the mode control unit152changes the control mode to the wire preferred mode (step S4). Here, if the control mode is already set to the wire preferred mode, there is no need to change the control mode.

If the control mode of the mode control unit152is set to the wire preferred mode, the peak cutting unit153outputs to the DC-DC converter130, a discharge instruction to discharge the secondary battery140at a power rate obtained by dividing a value of the difference between the required power and the reception peak-cut power by the efficiency of the DC-DC converter130(step S5). Then, the processing returns to step S1, and the charge and discharge control device150performs charge and discharge control at the next time.

On the other hand, if the mode control unit152determines that the required power is smaller than or equal to the preset reception peak-cut power (step S3: NO), the mode control unit152changes the control mode to the battery preferred mode (step S6). Here, if the control mode is already set to the battery preferred mode, there is no need to change the control mode.

When the control mode of the mode control unit152is set to the battery preferred mode, the charging rate monitoring unit154obtains the charging rate of the secondary battery140. Then, the improving power value calculating unit155determines whether or not the charging rate of the secondary battery140is larger than the preset target charging rate (step S7). If the charging rate of the secondary battery140is smaller than or equal to the target charging rate (step S7: NO), discharge of the secondary battery140is not performed and the processing returns to step S1, since the difference between the charging rate of the secondary battery140and the target charging rate becomes larger if the secondary battery140is discharged.

On the other hand, if the charging rate of the secondary battery140is larger than the target charging rate (step S7: YES), the improving power value calculating unit155calculates, by PI control, a discharge improving power value based on the charging rate of the secondary battery140and the target charging rate (step S8). Then, the charging rate improving unit156determines whether or not the power value obtained by dividing the required power by the efficiency of the DC-DC converter130is smaller than or equal to the discharge improving power value (step S9).

If the charging rate improving unit156determines that the power value obtained by dividing the required power by the efficiency of the DC-DC converter130is smaller than or equal to the discharge improving power value (step S9: YES), the charging rate improving unit156outputs to the DC-DC converter130, a discharge instruction to have the secondary battery140discharged at a power rate obtained by dividing the required power by the efficient (step S10). Thus, the power required by the load120is supplied from the secondary battery140. Consequently, the charging rate of the secondary battery140becomes closer to the target charging rate. Then, the processing returns to step S1, and the charge and discharge control device150performs charge and discharge control at the next time.

On the other hand, if the charging rate improving unit156determines that the power value obtained by dividing the required power by the efficiency of the DC-DC converter130is larger than the discharge improving power value (step S9: NO), the charging rate improving unit156outputs to the DC-DC converter130, a discharge instruction to have the secondary battery140discharged at a power rate equal to the discharge improving power value (step S11). Thus, the charging rate of the secondary battery140becomes closer to the target charging rate. At this time, similar to step S10, if control is made to supply all the power required by the load120from the secondary battery140, the charging rate of the secondary battery140might be below the target charging rate. For this reason, the secondary battery140is discharged at a power rate equal to the discharge improving power value, and the rest of the required power is supplied from the wire200, thereby making it possible to adequately control charge and discharge so that the charging rate of the secondary battery140becomes closer to the target charging rate.

Then, the processing returns to step S1, and the charge and discharge control device150performs charge and discharge control at the next time.

In step S2, if the load power monitoring unit151determines that the load120is under the regenerative breaking operation (step S2: NO), the mode control unit152determines whether or not the regenerative power is larger than the preset transmission peak-cut power (step S12). If the mode control unit152determines that the regenerative power is larger than the transmission peak-cut power (step S12: YES), the mode control unit152changes the control mode to the wire preferred mode (step S13). Here, if the control mode is already set to the wire preferred mode, there is no need to change the control mode.

When the control mode of the mode control unit152is set to the wire preferred mode, the peak cutting unit153outputs to the DC-DC converter130, a charge instruction to have the secondary battery140charged at a power rate obtained by multiplying a value of a difference between the regenerative power and the transmission peak-cut power by the efficiency of the DC-DC converter130(step S14). Then, the processing returns to step S1, and the charge and discharge control device150performs charge and discharge control at the next time.

On the other hand, if the mode control unit152determines that the regenerative power is smaller than or equal to the preset transmission peak-cut power (step S12: NO), the mode control unit152changes the control mode to the battery preferred mode (step S15). Here, if the control mode is already set to the battery preferred mode, there is no need to change the control mode.

When the control mode of the mode control unit152is set to the battery preferred mode, the charging rate monitoring unit154obtains the charging rate of the secondary battery140. Then, the improving power value calculating unit155determines whether or not the charging rate of the secondary battery140is smaller than the target charging rate (step S16). If the charging rate of the secondary battery140is larger than or equal to the target charging rate (step S16: NO), charge of the secondary battery140is not performed and the processing returns to step S1, since the difference between the charging rate of the secondary battery140and the target charging rate becomes larger if the secondary battery140is charged.

On the other hand, if the charging rate of the secondary battery140is smaller than the target charging rate (step S16: YES), the improving power value calculating unit155calculates, by PI control, a charge improving power value based on the charging rate of the secondary battery140and the target charging rate (step S17). Then, the charging rate improving unit156determines whether or not a power value obtained by multiplying the regenerative power by the efficiency of the DC-DC converter130is smaller than or equal to the charge improving power value (step S18).

If the charging rate improving unit156determines that the power value obtained by multiplying the regenerative power by the efficiency of the DC-DC converter130is smaller than or equal to the charge improving power value (step S18: YES), the charging rate improving unit156outputs to the DC-DC converter130, a charge instruction to have the secondary battery140charged at a power rate obtained by multiplying the regenerative power by the efficient (step S19). Thus, all the regenerative power generated by the load120is stored in the secondary battery140. Consequently, the charging rate of the secondary battery140becomes closer to the target charging rate. Then, the processing returns to step S1, and the charge and discharge control device150performs charge and discharge control at the next time.

On the other hand, if the charging rate improving unit156determines that the power value obtained by multiplying the regenerative power by the efficiency of the DC-DC converter130is larger than the charge improving power value (step S18: YES), the charging rate improving unit156outputs to the DC-DC converter130, a charge instruction to have the secondary battery140charged at a power rate equal to the charge improving power value (step S20). Thus, the charging rate of the secondary battery140becomes closer to the target charging rate. At this time, similar to step S19, if control is made to supply all the regenerative power generated by the load120to the secondary battery140for charging, the charging rate of the secondary battery140might exceed the target charging rate. For this reason, the secondary battery140is charged at the power rate equal to the charge improving power value, and the surplus power is collected by the wire200, thereby making it possible to adequately control charge and discharge so that the charging rate of the secondary battery140becomes closer to the target charging rate.

Then, the processing returns to step S1, and the charge and discharge control device150performs charge and discharge control at the subsequent time.

The above processes from step S1to step S20are repeatedly performed, thereby making it possible to implement the peak-cut of the powers supplied from and corrected by the wire200and to perform a control so that the charging rate of the secondary battery140becomes closer to the target charging rate.

Next, charge and discharge control of the secondary battery140performed by the charge and discharge control device150of the present embodiment is described with reference to a specific example.

FIG. 3is a diagram illustrating a specific example of the state at the time the charge and discharge control device150of the first embodiment of the present invention performs charge and discharge control on the secondary battery140.

First, at time t0, the load power monitoring unit151obtains the load power and determines in step S2that the load120is under the running operation. Then, the mode control unit152compares the required power of the load120and the reception peak-cut power, in step S3. At time t0, the required power of the load120is smaller than the reception peak-cut power, as shown inFIG. 3(A). For this reason, in step S6, the mode control unit152changes the control mode to the battery preferred mode, as shown inFIG. 3(C).

Then, the improving power value calculating unit155determines whether or not the charging rate of the secondary battery140is larger than the target charging rate. At time t0, the charging rate of the secondary battery140is larger than the target charging rate, as shown inFIG. 3(B). For this reason, in step S8, the improving power value calculating unit155calculates a discharge improving power value, as shown inFIG. 3(A).

Then, the charging rate improving unit156compares the discharge improving power value and a power value obtained by dividing the required power by the efficiency of the DC-DC converter130, in step S9. At time t0, the power value obtained by dividing the required power by the efficiency of the DC-DC converter130is smaller than or equal to the discharge improving power value, as shown inFIG. 3(A). For this reason, in step S10, the charging rate improving unit156outputs a discharge instruction to have the secondary battery140discharged at the power rate obtained by dividing the required power by the efficiency of the DC-DC converter130.

Then, at time t1, the power value obtained by dividing the required power by the efficiency of the DC-DC converter130exceeds the discharge improving power value, as shown inFIG. 3(A). For this reason, in step S11, the charging rate improving unit156outputs a discharge instruction to have the secondary battery140discharged at the power rate equal to the discharge improving power value. Then, the differential power between the required power and the power supplied from the secondary battery140is supplied from the wire200to the load120, as shown inFIG. 3(A).

Then, at time t2, the required power of the load120exceeds the reception peak-cut power, as shown inFIG. 3(A). For this reason, in step S4, the mode control unit152changes the control mode to the wire preferred mode. Then, the peak cutting unit153outputs a discharge instruction to have the second battery140discharged at a power rate obtained by dividing the difference between the required power and the reception peak-cut power by the efficiency of the DC-DC converter130. At this time, the power supplied from the wire200becomes the reception peak-cut power.

Then, at time t3, the required power of the load120becomes below the reception peak-cut power, as shown inFIG. 3(A). For this reason, in step S6, the mode control unit152changes the control mode to the battery preferred mode. Additionally, at time t3, the charging rate of the secondary battery140reaches the target charging rate, as shown inFIG. 3(B). For this reason, in the process at the time t3, the charge and discharge control device150does not output a discharge instruction to the DC-DC converter130in accordance with the result of the determination in step S7. For this reason, all the required power of the load120is supplied from the wire200.

Then, at time t4, the load120generates the regenerative power, as shown inFIG. 3(A). For this reason, in step S12, the mode control unit152compares the regenerative power of the load120and the transmission peak-cut power. At time t4, the regenerative power of the load120becomes larger than or equal to the transmission peak-cut power, as shown inFIG. 3(A). For this reason, the mode control unit152changes the control mode to the wire preferred mode, in step S13, as shown inFIG. 3(C).

Then, the peak cutting unit153outputs a charge instruction to have the secondary battery140charged at a power rate obtained by the multiplying the difference between the regenerative power and the transmission peak-cut power by the efficiency of the DC-DC converter130. At this time, the power collected by the wire200becomes the transmission peak-cut power. Additionally, by charging the secondary battery140at time t4, the charging rate of the secondary battery140becomes larger than the target charging rate, as shown inFIG. 3(B).

Then, at time t5, the regenerative power of the load120becomes below the transmission peak-cut power, as shown inFIG. 3(A). For this reason, in step S15, the mode control unit152changes the control mode to the battery preferred mode. Additionally, at time t5, the charging rate of the secondary battery140is larger than the target charging rate, as shown inFIG. 3(B). For this reason, the charge and discharge control device150does not output a charge instruction to the DC-DC converter130in accordance with a result of the determination in step S16. For this reason, all the regenerative power of the load120is collected by the wire200.

Then, at time t6, the operation of the load120changes from the regenerative breaking operation to the running operation, as shown inFIG. 3(A). Additionally, at time t6, the charging rate of the secondary battery140is larger than the target charging rate, as shown inFIG. 3(B). For this reason, in step S9, the improving power value calculating unit156compares the discharge improving power value and a power value obtained by dividing the required power by the efficiency of the DC-DC converter130. At time t6, the power value obtained by dividing the required power by the efficiency of the DC-DC converter130is smaller than or equal to the discharge improving power value, as shown inFIG. 3(A). For this reason, in step S10, the charging rate improving unit156outputs a discharge instruction to have the secondary battery140discharged at the power rate obtained by dividing the required power by the efficiency of the DC-DC converter130. Thus, the charging rate of the secondary battery140becomes closer to the target charging rate, again.

As explained above, according to the present embodiment, the charge and discharge control device150has the secondary battery140discharged at a power rate that is larger than or equal to the difference between the required power and the reception peak-cut power when the required power of the load120is larger than or equal to the reception peak-cut power. When the required power of the load120is smaller than the reception peak-cut power, the discharge control device150has the secondary battery140discharged at a power rate that is smaller than or equal to the discharge improving power value.

Additionally, according to the present embodiment, the charge and discharge control device150has the secondary battery140charged at the power rate that is larger than or equal to the difference between the regenerative power and the transmission peak-cut power when the regenerative power of the load120is larger than or equal to the transmission peak-cut power. When the regenerative power of the load120is smaller than the transmission peak-cut power, the charge and discharge control device150has the secondary battery140charged at the power rate that is smaller than or equal to the charge improving power value.

Thus, it is possible to adjust the charging rate of the secondary battery140while cutting the peaks of the power transmitted to the wire200and the power received from the wire200.

Descriptions have been given in the present embodiment with respect to the case where the peak cutting unit153, in the wire preferred mode, control charge and discharge of the secondary battery140so that the power supplied from or collected by the wire200becomes the peak-cut power. However, the configuration is not limited thereto. In other words, as long as the power supplied from or collected by the wire200does not become larger than or equal to the peak-cut power, the peak cutting unit153may be configured to control charge and discharge of the secondary battery140so that the power received from or transmitted to the wire200becomes smaller than or equal to the peak-cut power.

Second Embodiment

Next, a second embodiment of the present invention is described here.

FIG. 4is a schematic block diagram illustrating a configuration of the vehicle100including the charge and discharge control device150according to a second embodiment of the present invention.

The charge and discharge control device150of the second embodiment does not include the mode control unit152included in the charge and discharge control device150of the first embodiment, but includes a power determining unit157. The power determining unit157outputs to the DC-DC converter130, an instruction to have the secondary battery140charged or discharged at a power rate that is larger of the powers to charge or discharge the secondary battery140, which are output from the peak cutting unit153and the charging rate improving unit156.

Next, processing of the charge and discharge control device150of the second embodiment is described here.

FIG. 5is a flowchart illustrating the processing of the charge and discharge control device150according to the second embodiment of the present invention.

When a train initiates running, the load power monitoring unit151obtains the load power (step S101). Then, the load power monitoring unit151determines whether the load120is under a running operation or a braking operation (step S102).

If the load power monitoring unit151determines that the load120is under the running operation (step S102: YES), the peak cutting unit153determines whether or not the required power is larger than the preset reception peak-cut power (step S103). If the peak cutting unit153determines that the required power is larger than the preset reception peak-cut power (step S103: YES), the peak cutting unit153calculates, as a first power value, a power value obtained by dividing a value of the difference between the required power and the reception peak-cut power by the efficiency of the DC-DC converter130(step S104). On the other hand, if the peak cutting unit153determines that the required power is smaller than or equal to the preset reception peak-cut power (step S103: NO), the peak cutting unit153sets the first power value to be zero (step S105).

After the peak cutting unit153calculates the first power value in step S104or step S105, the charging rate monitoring unit154obtains the charging rate of the secondary battery140. Then, the improving power value calculating unit155calculates, by PI control, a discharge improving power value based on the charging rate of the secondary battery140and the target charging rate (step S106). Here, if the charging rate of the secondary battery140is smaller than the target charging rate, the discharge improving power value becomes zero. Then, the charging rate improving unit156determines whether or not the power value obtained by dividing the required power by the efficiency of the DC-DC converter130is smaller than or equal to the discharge improving power value (step S107).

If the charging rate improving unit156determines that the power value obtained by dividing the required power by the efficiency of the DC-DC converter130is smaller than or equal to the discharge improving power value (step S107: YES), the charging rate improving unit156calculates, as a second power value, the power value obtained by dividing the required power by the efficiency (step S108). On the other hand, if the charging rate improving unit156determines that the power value obtained by dividing the required power by the efficiency of the DC-DC converter130is larger than the discharge improving power value (step S107: NO), the charging rate improving unit156sets the second power value to be the discharge improving power value (step S109).

After the charging rate improving unit156calculates the second power value in step S108or S109, the power determining unit157determines whether or not the first power value calculated by the peak cutting unit153is larger than the second power value calculated by the charging rate improving unit156(step S110). If the power determining unit157determines that the first power value is larger than the second power value (step S110: YES), the power determining unit157outputs to the DC-DC converter130, a discharge instruction to have the secondary battery140discharged at a power rate equal to the first power value (step S111). On the other hand, if the power determining unit157determines that the first power value is smaller than or equal to the second power value (step S110: NO), the power determining unit157outputs to the DC-DC converter130, a discharge instruction to have the secondary battery140discharged at a power rate equal to the second power value (step S112).

Then, the processing returns to step S101and the charge and discharge control device150performs charge and discharge control at the subsequent time.

On the other hand, in step S102, if the load power monitoring unit151determines that the load120is under the regenerative breaking operation (step S102: NO), the peak cutting unit153determines whether or not the regenerative power is larger than the preset transmission peak-cut power (step S113). If the peak cutting unit153determines that the regenerative power is larger than the preset transmission peak-cut power (step S113: YES), the peak cutting unit153calculates, as a first power value, a power value obtained by multiplying a value of the difference between the regenerative power and the transmission peak-cut power by the efficiency of the DC-DC converter130(step S114). On the other hand, if the peak cutting unit153determines that the regenerative power is smaller than or equal to the preset transmission peak-cut power (step S103: NO), the peak cutting unit153sets the first power value to be zero (step S115).

After the peak cutting unit153calculates the first power value in step S114or step S115, the charging rate monitoring unit154obtains the charging rate of the secondary battery140. Then, the improving power value calculating unit155calculates, by PI control, a charge improving power value based on the charging rate of the secondary battery140and the target charging rate (step S116). Here, when the charging rate of the secondary battery140is smaller than the target charging rate, the charge improving power value becomes zero. Then, the charging rate improving unit156determines whether or not the power value obtained by multiplying the regenerative power by the efficiency of the DC-DC converter130is smaller than or equal to the charge improving power value (step S117).

If the charging rate improving unit156determines that the power value obtained by multiplying the regenerative power by the efficiency of the DC-DC converter130is smaller than or equal to the charge improving power value (step S117: YES), the charging rate improving unit156calculates, as a second power value, the power value obtained by multiplying the regenerative power by the efficiency (step S118). On the other hand, if the charging rate improving unit156determines that the power value obtained by multiplying the regenerative power by the efficiency of the DC-DC converter130is larger than the charge improving power value (step S117: NO), the charging rate improving unit156sets the second power value to be the charge improving power value (step S119).

After the charging rate improving unit156calculates the second power value in step S118or S119, the power determining unit157determines whether or not the first power value calculated by the peak cutting unit153is larger than the second power value calculated by the charging rate improving unit156(step S120). If the power determining unit157determines that the first power value is larger than the second power value (step S120: YES), the power determining unit157outputs to the DC-DC converter130, a charge instruction to have the secondary battery140charged at the power rate equal to the first power value (step S121). On the other hand, if the power determining unit157determines that the first power value is smaller than or equal to the second power value (step S120: NO), the power determining unit157outputs to the DC-DC converter130, a charge instruction to have the secondary battery140charged at the power rate equal to the second power value (step S122).

Then, the processing returns to step S101, and the charge and discharge control device150performs charge and discharge control at the subsequent time.

The above processes from step S101to step S122are repeatedly performed, thereby making it possible to implement the peak-cut of the powers supplied from and corrected by the wire200and to perform a control so that the charging rate of the secondary battery140becomes closer to the target charging rate. Particularly, according to the second embodiment, it is possible to perform a control so that the charging rate of the secondary battery140becomes closer to the target charging rate faster than in the first embodiment.

Next, charge and discharge control of the secondary battery140performed by the charge and discharge control device150according to the present embodiment is described with reference a specific example.

FIG. 6is a diagram illustrating a specific example of the state at the time the charge and discharge control device150of the second embodiment of the present invention performs charge and discharge control on the secondary battery140.

First, at time t0, the load power monitoring unit151obtains the load power and determines in step S102that the load120is under the running operation. At this time, the required power of the load120is smaller than the reception peak-cut power as shown inFIG. 6(A). For this reason, in step S105, the peak cutting unit153sets the first power value to be zero. On the other hand, the power value obtained by dividing the required power by the efficiency of the DC-DC converter130is smaller than or equal to the discharge improving power value, as shown inFIG. 6(A). For this reason, in step S108, the charging rate improving unit156sets the second power value to be the power value obtained by dividing the required power by the efficiency of the DC-DC converter130.

At this time, the first power value is smaller than or equal to the second power value. For this reason, the power determining unit157outputs a discharge instruction to have the secondary battery140discharged at the power rate equal to the second power value, that is, the power value obtained by dividing the required power by the efficiency of the DC-DC converter130.

Then, at time t1, the required power of the load120is smaller than the reception peak-cut power, as shown inFIG. 6(A). For this reason, in step S105, the peak cutting unit153sets the first power value to be zero. On the other hand, the power value obtained by dividing the required power by the efficiency of the DC-DC converter130is larger than the discharge improving power value, as shown inFIG. 6(A). For this reason, in step S109, the charging rate improving unit156sets the second power value to be the discharge improving power value.

At this time, the first power value is smaller than or equal to the second power value. For this reason, the power determining unit157outputs a discharge instruction to have the secondary battery140discharged at the power rate equal to the second power value, that is, the discharge improving power. Then, the differential power between the required power and the power supplied from the secondary battery140is supplied from the wire200to the load120, as shown inFIG. 6(A).

Then, at time t2, the required power of the load120exceeds the reception peak-cut power, as shown inFIG. 6(A). For this reason, in step S104, the peak cutting unit153sets the first power value to be the power value obtained by dividing a value of the difference between the required power and the reception peak-cut power by the efficiency of the DC-DC converter130. On the other hand, the power value obtained by dividing the required power by the efficiency of the DC-DC converter130is larger than the discharge improving power value, as shown inFIG. 6(A). For this reason, in step S109, the charging rate improving unit156sets the second power value to be the discharge improving power value.

At this time, the first power value is smaller than or equal to the second power value. For this reason, the power determining unit157outputs a discharge instruction to have the secondary battery140discharged at the power rate equal to the second power value, that is, the discharge improving power value. In other words, according to the present embodiment, even when the required power is larger than or equal to the reception peak-cut power, as long as the discharge improving power value is larger than or equal to the differential power between the required power and the reception peak-cut power, the secondary battery140is discharged at the power rate equal to the discharge improving power value.

On the other hand, at time t3, the first power value becomes larger than the second power value. For this reason, the power determining unit157outputs a discharge instruction to have the secondary battery140discharged at the power rate equal to the first power value, that is, the value of the difference between the required power and the reception peak-cut power. At this time, the power supplied from the wire200becomes the reception peak-cut power.

Then, at time t4, the required power of the load120becomes below the reception peak-cut power, as shown inFIG. 6(A). For this reason, in step S105, the peak cutting unit153sets the first power value to be zero. On the other hand, at time t4, the charging rate of the secondary battery140is below the target charging rate, as shown inFIG. 6(B). For this reason, the discharge improving power value is zero. Accordingly, the power value obtained by dividing the required power by the efficiency of the DC-DC converter130is larger than the discharge improving power value. For this reason, in step S109, the charging rate improving unit156sets the second power value to be the discharge improving power value. In other words, the second power value becomes zero.

Accordingly, the first and second power values are zero. For this reason, the power determining unit157outputs a discharge instruction to have the secondary battery140discharged at the power rate equal to zero. This is equivalent to that the discharge instruction is not output. For this reason, all the required power of the load120is supplied from the wire200.

Then, at time t5, the load power monitoring unit151obtains the load power and determines in step S102that the load120is under the regenerative breaking operation. At this time, the regenerative power of the load120is larger than or equal to the transmission peak-cut power, as shown inFIG. 6(A). For this reason, in step S114, the peak cutting unit153sets the first power value to be a power value obtained by multiplying a value of the difference between the regenerative power and the transmission peak-cut power by the efficiency of the DC-DC converter130. On the other hand, the power value obtained by multiplying the regenerative power by the efficiency of the DC-DC converter130is larger than the charge improving power value. For this reason, in step S119, the charging rate improving unit156sets the second power value to be the charge improving power value.

At this time, the first power value is larger than the second power value. For this reason, the power determining unit157outputs a charge instruction to have the secondary battery140charged at the power rate equal to the first power value, that is, the power value obtained by multiplying the value of the difference between the regenerative power and the transmission peak-cut power by the efficiency of the DC-DC converter130.

Then, at time t6, the regenerative power of the load120is larger than or equal to the transmission peak-cut power, as shown inFIG. 6(A). For this reason, in step S115, the peak cutting unit153sets the first power value to be zero. On the other hand, at time t6, the charging rate of the secondary battery140is above the target charging rate, as shown inFIG. 6(B). For this reason, the charge improving power value is zero. Accordingly, the power value obtained by multiplying the regenerative power by the efficiency of the DC-DC converter130is larger than the charge improving power value. For this reason, in step S119, the charging rate improving unit156sets the second power value to be the charge improving power value. In other words, the second power value becomes zero.

Accordingly, the first and second power values are zero. For this reason, the power determining unit157outputs a charge instruction to have the secondary battery140charged at the power rate equal to zero. This is equivalent to that the charge instruction is not output. For this reason, all the regenerative power of the load120is collected by the wire200.

Then, at time t7, the operation of the load120changes from the regenerative braking operation to the running operation, as shown inFIG. 6(A). Additionally, the required power of the load120is smaller than the reception peak-cut power, as shown inFIG. 6(A). For this reason, in step S105, the peak cutting unit153sets the first power value to be zero. On the other hand, the power value obtained by dividing the required power by the efficiency of the DC-DC converter130is smaller than or equal to the discharge improving power, as shown inFIG. 6(A). For this reason, in step S108, the charging rate improving unit156sets the second power value to be the power value obtained by dividing the required power by the efficiency of the DC-DC converter130.

At this time, the first power value is smaller than or equal to the second power value. For this reason, the power determining unit157outputs a discharge instruction to have the secondary battery140discharged at the power rate equal to the second power value, that is, the power value obtained by dividing the required power by the efficiency of the DC-DC converter130. Thus, the charging rate of the secondary battery140becomes closer to the target charging rate, again.

As explained above, according to the present embodiment, the charge and discharge control device150has the secondary battery140discharged at the power rate equal to the discharge improving power value when the required power is larger than or equal to the reception peak-cut power, and the discharge improving power is larger than or equal to the value of the difference between the required power and the reception peak-cut power.

Additionally, according to the present embodiment, the charge and discharge control device150has the secondary battery140charged at the power rate equal to the discharge improving power value when the regenerative power is larger than or equal to the transmission peak-cut power, and the charge improving power is larger than or equal to the value of the difference between the regenerative power and the transmission peak-cut power.

Thus, it is possible to adjust the charging rate of the secondary battery140more efficiently than in the first embodiment while cutting the peaks of the power transmitted to the wire200and the power received from the wire200. Additionally, determination of the control mode is not performed, thereby making the control logic simpler than that in the first embodiment. Further, it is possible in the second embodiment to prevent a rapid variation of the power of the secondary battery, compared to the second embodiment, thereby enabling a reduction in load on devices, such as the DC-DC converter130and the inverter110.

Different from the first embodiment, descriptions have been given in the present embodiment with respect to the case where determination of the control mode is not performed. However, the configuration is not limited thereto. For example, the peak cutting unit153may be configured to, when the control mode is set to the wire preferred mode, if the discharge improving power value is larger than or equal to the power obtained by dividing the difference between the required power and the reception peak-cut power by the efficiency of the DC-DC converter130, output an instruction to have the secondary battery140discharged at the power rate equal to the discharge improving power value, thereby achieving the same effect as that of the first embodiment. Similarly, the peak cutting unit153may be configured to, when the control mode is set to the wire preferred mode, if the charge improving power value is larger than or equal to the power obtained by multiplying the difference between the required power and the reception peak-cut power by the efficiency of the DC-DC converter130, output an instruction to have the secondary battery140charged at the power rate equal to the charge improving power value, thereby achieving the same effect as that of the first embodiment.

Third Embodiment

Next, processing of the charge and discharge control device150according to a third embodiment of the present invention is described here.

The charge and discharge control device150of the third embodiment is configured to perform a control such that the peak cutting unit153of the charge and discharge control device150of the first or second embodiment outputs a control instruction to have the secondary battery140charged or discharged within a use voltage range or a use current range of the secondary battery140. In other words, control is made such that the peak cutting unit153outputs a discharge control instruction to have the secondary battery140discharged at a power rate that is smaller than the maximum discharge power value allowable by the second battery140, and outputs a charge control instruction to have the secondary battery140charged at a power rate that is smaller than the maximum charge power value allowable by the second battery140.

Specifically, at the time the capacity of the secondary battery140is designed, a configuration is made such that the power to be calculated by the peak cutting unit153in step S5or S104becomes smaller than a power value obtained by multiplying a value of the monitored voltage of the secondary battery140by the amount of the maximum allowable discharge current. At this time, as the maximum allowable discharge current, a current value obtained by dividing by an internal resistance of the secondary battery140, a value obtained by subtracting the minimum allowable voltage of the secondary battery140from the voltage of an open circuit of the secondary battery140, may be used.

Additionally, at the time the capacity of the secondary battery140is designed, a configuration is made such that the power to be calculated by the peak cutting unit153in step S14or S114is smaller than a power value obtained by multiplying a value of the monitored voltage of the secondary battery140by the amount of the minimum allowable discharge current. At this time, as the minimum allowable discharge current, a current value obtained by dividing by the internal resistance of the secondary battery140, a value obtained by subtracting the maximum allowable voltage of the secondary battery140from the voltage of the open circuit of the secondary battery140, may be used.

Thus, the charge and discharge control device150can control charge and discharge of the secondary battery140within the use range of the secondary battery140. Here, when the use range is exceeded while the vehicle100is running, a margin is previously provided for a power supplying device (not shown) that supplies the power to the wire200, or acceleration or deceleration of the vehicle100is adjusted, thereby preventing the use range from being exceeded.

Fourth Embodiment

Next, a fourth embodiment of the present invention is described here.

FIG. 7is a schematic block diagram illustrating a configuration of the vehicle100including the charge and discharge control device150according to the fourth embodiment of the present invention.

The charge and discharge control device150of the fourth embodiment is configured to further include a charge and discharge terminating unit158(a charge terminating unit, a discharge terminating unit) in the charge and discharge control device150of the first embodiment. The charge and discharge terminating unit158terminates discharge by the peak cutting unit153when the charging rate of the secondary battery140is smaller than the minimum charging rate allowable to the secondary battery140. Additionally, the charge and discharge terminating unit158terminates charge by the peak cutting unit153when the charging rate of the secondary battery140exceeds the maximum charging rate allowable to the secondary battery140.

Thus, the charge and discharge control device150can control charge and discharge of the secondary battery140within the use range of the secondary battery140. Here, when the use range is exceeded while the vehicle100is running, a margin is previously provided for a power supplying device (not shown) that supplies the power to the wire200, or acceleration or deceleration of the vehicle100is adjusted, thereby preventing the use range from being exceeded.

Here, the charging rate improving unit156does not output a charge instruction when the charging rate of the secondary battery140is larger than the target charging rate. Additionally, the charging rate improving unit156does not output a discharge instruction when the charging rate of the secondary battery140is smaller than the target charging rate. For this reason, it is sufficient for the charge and discharge terminating unit158to stop the peak cutting unit153to output the charge or discharge instruction.

Some embodiments of the present invention have been described above with reference to the drawings. However, the specific configuration is not limited to the above, and various design modifications may be made without departing from the scope of the present invention.

For example, descriptions have been given in the above embodiments with respect to the case where control is performed with respect to both the charge processing and the discharge processing. However, the configuration is not limited thereto. In other words, a configuration may be such that the charge control method of the present invention is used only at the time the secondary battery140is charged, and another control method is used at the time the secondary battery140is discharged. Alternatively, a configuration may be such that the discharge control method of the present invention is used only at the time the secondary battery140is discharged, and another control method is used at the time the secondary battery140is charged.

The above charge and discharge control device150includes a computer system. A program for implementing the above process of each processing unit is stored in a computer-readable recording medium, so that a computer reads and executes the program to perform the above process. Here, the “computer-readable recording medium” includes a magnet disk, a magneto optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, and the like. Additionally, the computer program may be distributed to computers via communication lines, so that a computer receiving the distribution can execute the program.

Further, the program includes a program that executes part of the aforementioned functions. Moreover, the program includes a program, called a differential file (differential program), which can implement the aforementioned functions in combination with the program already stored in the computer system.

INDUSTRIAL APPLICABILITY

The present invention is applicable to wire-less vehicles mounted with secondary batteries.

DESCRIPTION OF REFERENCE NUMERALS

100: vehicle110: inverter120: load130: DC-DC converter140: secondary battery150: charge and discharge control device151: load power monitoring unit152: mode control unit153: peak cutting unit154: charging rate monitoring unit155: improving power value calculating unit156: charging rate improving unit157: power determining unit158: charge and discharge terminating unit200: wire