JP7233825B1 - DC power supply system - Google Patents

Abstract

A stable DC power supply system is provided by suppressing operation stoppage of a converter and maintaining redundancy of the converter.
A DC power supply system includes a DC bus 2, a first power supply 4A, a second power supply 4B, a first converter 5A, a second converter 5B, and a control circuit. Based on a first physical quantity that changes according to the remaining energy amount stored in the first power supply 4A and a second physical quantity that changes according to the remaining energy amount stored in the second power supply 4B, the control circuit 7 performs the first A first output voltage command value for the converter 5A and a second output voltage command value for the second converter 5B are determined. The first converter 5A steps up and down the first power supply voltage to the first output voltage based on the first output voltage command value and the first voltage droop characteristic. The second converter 5B steps up and down the second power supply voltage to the second output voltage based on the second output voltage command value and the second voltage droop characteristic.
[Selection drawing] Fig. 1

Description

Embodiments of the present invention relate to DC power supply systems.

2. Description of the Related Art In a system in which power is output from batteries connected in parallel to a DC bus, there is known a technique for controlling the output current to be output to the DC bus by a conversion device between each battery and the DC bus.

As a related technique, Patent Literature 1 discloses a switching power supply system. In the switching power supply system described in Patent Document 1, a switching power supply with a droop characteristic in which the output voltage drops as the output current increases is arranged between the power generator and the DC bus.

More specifically, in the switching power supply system described in Patent Document 1, conversion is performed so that the output current to the DC bus is appropriately shared according to the power supply capacity of each power generator as a power supply source. A droop characteristic in which the output voltage drops as the output current increases is added to each switching power supply as a device, and the droop characteristic is set in advance. In the operation of each conversion device, a deviation in control timing, a control error, and the like may occur. Therefore, even when the target voltage, which is the target value of the output to the DC bus, is set to be the same among the plurality of converters, an error may occur in the actual output voltage of each converter. Therefore, in the switching power supply system described in Patent Document 1, by adding a droop characteristic to the converter, the output voltage of a specific converter becomes higher than the output voltage of the other converters. To prevent current from being intensively output from a specific conversion device.

FIG. 14 shows an example of a conventional DC power supply system. 14, the DC power supply system includes a load 91, a DC bus 92, a first battery group 94A, a second battery group 94B, a first battery management unit 93A, a second battery management unit 93B, a first It has a conversion device 95A, a second conversion device 95B, a first current detector 96A, a second current detector 96B, a first droop control section 97A and a second droop control section 97B.

In the DC power supply system shown in FIG. 14, the first droop control unit 97A has a droop characteristic in which the output voltage of the first converter 95A drops when the output current detected by the first current detector 96A increases. The output voltage command value is transmitted to the first conversion device 95A so as to be exhibited. In addition, the second droop control unit 97B controls the second droop characteristic so that the output voltage of the second conversion device 95B drops when the output current detected by the second current detector 96B increases. The output voltage command value is transmitted to the converter 95B. Thus, the output voltage of one of the first converter 95A and the second converter 95B is higher than the output voltage of the other of the first converter 95A and the second converter 95B. This prevents current from being intensively output from one of the first conversion device 95A and the second conversion device 95B.

JP 2020-22331 A

However, when batteries with different capacities or discharge characteristics are combined, or when there are individual differences in batteries of the same type, the switching power supply system disclosed in Patent Document 1 does not allow the battery level to reach zero first. occurs. In this case, the conversion device powered by the individual with zero remaining battery capacity stops operating, and the load on the remaining device increases stepwise. As a result, an overload acts on the remaining machine, which may lead to system stoppage. Redundancy is also compromised due to the reduced number of active converters arranged in parallel.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a stable DC power supply system by suppressing the operation stoppage of the converter and maintaining the redundancy of the converter.

In order to solve the above problems, a DC power supply system according to an embodiment of the present invention includes a DC bus to which one or both of a load and a charging power supply are connected; a second power supply that stores a second energy and outputs DC power from the second energy; a first power supply that is disposed between the first power supply and the DC bus; a first conversion device for stepping up or down a first power supply voltage to a first output voltage on the DC bus side; Detecting or calculating a first physical quantity that changes according to a second conversion device that steps up and down to a second output voltage on the DC bus side and the remaining amount of the first energy stored in the first power supply, and calculating the first physical quantity and a second output unit for detecting or calculating a second physical quantity that changes according to the remaining amount of the second energy stored in the second power supply, and for outputting a signal indicating the second physical quantity. Based on the 2 output units and the first physical quantity and the second physical quantity, a first output voltage command value for the first conversion device and a second output voltage command value for the second conversion device are determined. A control circuit that outputs the determined first output voltage command value to the first conversion device and outputs the determined second output voltage command value to the second conversion device, the first conversion device increases or decreases the first power supply voltage to the first output voltage based on the first output voltage command value and a first voltage droop characteristic, and the second converter increases the second output voltage command value and the second voltage droop characteristic, the second power supply voltage is stepped up or down to the second output voltage.

In order to solve the above problems, a DC power supply system according to another embodiment of the present invention includes a DC bus to which one or both of a load and a charging power supply are connected; a first power supply that outputs DC power from energy; a second power supply that stores second energy and outputs DC power from the second energy; a first converter for stepping up or stepping down a first power supply voltage on the side of a first power supply to a first output voltage on the side of the DC bus; detecting or calculating a first physical quantity that changes according to a second converter that steps up and down a power supply voltage to a second output voltage on the DC bus side, and a remaining amount of the first energy stored in the first power supply; a first output unit for outputting a signal indicating a first physical quantity; detecting or calculating a second physical quantity that changes according to the remaining amount of the second energy stored in the second power supply; and generating a signal indicating the second physical quantity. a first current detector that detects a first output current of the first conversion device and outputs a first current signal indicative of the first output current to a first droop control unit; a second current detector that detects a second output current of the second conversion device and outputs a second current signal indicating the second output current to a second droop control unit; and the first physical quantity and the second physical quantity. Based on, a first droop control value for the first droop control unit and a second droop control value for the second droop control unit are determined, and the determined first droop control value is applied to the first droop control a control circuit for outputting the determined second droop control value to the second droop control unit; and a control circuit for outputting the determined second droop control value to the second droop control unit; said first droop control for adjusting one voltage droop characteristic; and said second droop control for adjusting a second voltage droop characteristic of said second converter based on said second droop control value received from said control circuit. and the first droop control unit determines a first output voltage command value for the first conversion device based on the first voltage droop characteristic after adjustment and the first output current, The determined first output voltage command value is output to the first conversion device, and the second droop control unit is based on the adjusted second voltage droop characteristic and the second output current, the Determining a second output voltage command value for the second converter, the determined It is characterized by outputting said 2nd output voltage command value to said 2nd converter.

According to the present invention, it is possible to provide a stable DC power supply system by suppressing the operation stoppage of the converter and maintaining the redundancy of the converter.

FIG. 1 is a diagram schematically showing an example of the circuit configuration of a DC power supply system according to the first embodiment. FIG. 2 is a diagram for explaining the voltage droop characteristic of the converter. FIG. 3 is a diagram showing an example of the relationship between the remaining battery level and the output voltage command value for the conversion device in relation to the comparative example. FIG. 4 is a diagram showing an example of the relationship between the remaining battery level and the output voltage command value for the conversion device in the first embodiment. FIG. 5 is a diagram schematically showing how the first output voltage command value for the first converter is changed under the condition that the first converter has voltage droop characteristics. FIG. 6 is a diagram schematically showing an example of the circuit configuration of the DC power supply system according to the first embodiment. FIG. 7 is a diagram showing an example of the relationship between the remaining battery level and the output voltage command value for the conversion device in relation to the comparative example. FIG. 8 is a diagram showing an example of the relationship between the remaining battery level and the output voltage command value for the conversion device in the first embodiment. FIG. 9 is a diagram schematically showing an example of a circuit configuration of a DC power supply system according to the second embodiment. FIG. 10 is a diagram schematically showing an example of the circuit configuration of the DC power supply system according to the third embodiment. FIG. 11 is a diagram showing an example of voltage droop characteristics of the converter of the DC power supply system according to the third embodiment. FIG. 12 is a diagram schematically showing a state after the voltage droop characteristic of the first converter is changed. FIG. 13 is a diagram schematically showing an example of the circuit configuration of the DC power supply system according to the third embodiment. FIG. 14 is a diagram schematically showing the circuit configuration of a conventional DC power supply system.

A DC power supply system 100 according to an embodiment will be described below with reference to the accompanying drawings. In the following description, members and portions having the same functions are denoted by the same reference numerals, and repeated descriptions of members and portions denoted by the same reference numerals are omitted.

(First embodiment)
A DC power supply system 100A according to the first embodiment will be described with reference to FIGS. 1 to 8. FIG. FIG. 1 is a diagram schematically showing an example of a circuit configuration of a DC power supply system 100A according to the first embodiment. FIG. 2 is a diagram for explaining voltage droop characteristics of the converters (5A, 5B). FIG. 3 is a diagram showing an example of the relationship between the remaining battery level and the output voltage command value for the converters (5A, 5B) in relation to the comparative example. FIG. 4 is a diagram showing an example of the relationship between the remaining battery level and the output voltage command value for the converters (5A, 5B) in the first embodiment. FIG. 5 is a diagram schematically showing how the first output voltage command value for the first converter 5A is changed under the condition that the first converter 5A has voltage droop characteristics. FIG. 6 is a diagram schematically showing an example of the circuit configuration of the DC power supply system 100A in the first embodiment. FIG. 6 shows how the batteries (40A, 40B) are being charged. FIG. 7 is a diagram showing an example of the relationship between the remaining battery level and the output voltage command value for the converters (5A, 5B) in relation to the comparative example. FIG. 8 is a diagram showing an example of the relationship between the remaining battery level and the output voltage command value for the converters (5A, 5B) in the first embodiment.

(composition)
In the example shown in FIG. 1, the DC power supply system 100A includes at least one load 1A, a DC bus 2, a first power supply 4A, a second power supply 4B, and a first battery management unit 3A (hereinafter, battery A management unit is called a “BMU”.), a second BMU 3B, a first conversion device 5A, a second conversion device 5B, a first output section 6A, a second output section 6B, and a control circuit 7. and One of the first BMU 3A and the second BMU 3B, or both the first BMU 3A and the second BMU 3B may be omitted.

Also, at least one load 1A may be replaced with at least one charging power supply 1B. Alternatively, the DC power supply system 100A may include at least one charging power source 1B in addition to at least one load 1A. In other words, DC bus 2 is connected to one or both of load 1A and charging power supply 1B.

In the example shown in FIG. 1, the load 1A is composed of, for example, a DC load or a combination of a conversion device and an AC load, and consumes power supplied from the DC bus 2 . In the example shown in FIG. 1, when the load 1A is replaced with the charging power source 1B, or when the DC power supply system 100A includes the charging power source 1B in addition to the load 1A, the charging power source 1B supplies power via the DC bus 2 to the first power source 4A and/or the second power source 4B. Thus, the amount of energy stored in first power source 4A and/or second power source 4B is increased.

The first power supply 4A stores the first energy and outputs DC power from the first energy. The first power supply 4A is, for example, a rechargeable first battery 40A (more specifically, a first battery group). The first rechargeable battery 40A is, for example, a chemical battery that produces DC power from first energy through a chemical reaction. The first rechargeable battery 40A may be a lithium ion battery.

In the first embodiment (or a second embodiment described later or a third embodiment described later), the first power supply 4A is a fuel cell (a fuel cell is a type of chemical cell). It doesn't matter if there is. The fuel cell generates direct-current power from the fuel as the first energy by chemically reacting the fuel such as hydrogen with oxygen or the like. Alternatively, in the first embodiment (or a second embodiment described later or a third embodiment described later), the first power supply 4A is a power supply that stores kinetic energy such as a flywheel. or a power source that stores elastic energy or thermal energy. Further alternatively, the first power source 4A may be a power source that stores persistent current, such as a superconducting coil.

The second power supply 4B stores second energy and outputs DC power from the second energy. The second power supply 4B is, for example, a rechargeable second battery 40B (more specifically, a second battery group). The rechargeable second battery 40B is, for example, a chemical battery that produces DC power from second energy through a chemical reaction. The rechargeable second battery 40B may be a lithium ion battery.

In the first embodiment (or a second embodiment described later or a third embodiment described later), the second power supply 4B is a fuel cell (a fuel cell is a type of chemical cell). It doesn't matter if there is. The fuel cell generates DC power from the fuel as the second energy by chemically reacting the fuel such as hydrogen and oxygen. Alternatively, in the first embodiment (or a second embodiment described later or a third embodiment described later), the second power supply 4B is a power supply that stores kinetic energy such as a flywheel. or a power source that stores elastic energy or thermal energy. Further alternatively, the second power source 4B may be a power source that stores persistent current, such as a superconducting coil.

The first power source 4A and the second power source 4B may be the same type of power source (eg, both may be rechargeable batteries). Alternatively, the first power source 4A and the second power source 4B may be different types of power sources (eg, the former being a rechargeable battery and the latter a power source other than a rechargeable battery). is also good.).

In the following, the first power source 4A is a first rechargeable battery 40A (eg, a first battery group), and the second power source 4B is a second rechargeable battery 40B (eg, a second battery group). An example in the case of is described. However, in the first embodiment, at least one of the first power source 4A and the second power source 4B may be a power source other than a rechargeable battery.

In other words, in the following description of the first embodiment, "first battery 40A", "second battery 40B", "battery voltage", "first battery voltage", "second battery voltage", "battery Remaining capacity", "first battery remaining capacity", and "second battery remaining capacity" are respectively "first power supply 4A", "second power supply 4B", "power supply voltage", "first power supply voltage", " It can be read as "second power supply voltage", "remaining energy", "first remaining energy", and "second remaining energy".

The first BMU 3A monitors the state of the first battery 40A and/or protects the first battery 40A. In the example shown in FIG. 1, the first BMU 3A is equipped with the first battery 40A. The second BMU 3B monitors the state of the second battery 40B and/or protects the second battery 40B. In the example shown in FIG. 1, the second BMU 3B is equipped with the second battery 40B.

5 A of 1st converters are arrange|positioned between the 1st battery 40A and the DC bus-line 2, and the 1st battery voltage by the side of the 1st battery 40A is the output voltage by the side of the DC bus-line 2 (henceforth, "1st output voltage"). ). More specifically, the first conversion device 5A is based on the target voltage of the DC bus 2 (or a first output voltage command value described later) and the first voltage droop characteristic, the first voltage on the first battery 40A side 1 battery voltage is stepped up or down to the first output voltage on the DC bus 2 side.

In this specification, the first voltage droop characteristic means that the output current of the first converter 5A (hereinafter referred to as "first output current") increases, and the first voltage droop characteristic of the first converter 5A increases. 1 means the characteristic that the output voltage drops.

In the example shown in FIG. 1, the first battery 40A and the first conversion device 5A are connected via the first wire L1, and the first conversion device 5A and the DC bus 2 are connected via the second wire L2. ing. In this case, the first conversion device 5A steps up and down the voltage on the first wire L1 to the voltage on the second wire L2.

The first voltage droop characteristic of the first conversion device 5A will be described with reference to FIG. In the example shown in FIG. 2, the target voltage of DC bus 2 is voltage V1. In the example shown in FIG. 2, when the value of the first output current of the first conversion device 5A increases from the current value I1 to the current value I1′, the value of the first output voltage of the first conversion device 5A changes from the voltage From value F1, it drops to voltage value F1' (see arrow AR1). On the other hand, in the example shown in FIG. 2, when the value of the first output current of the first conversion device 5A decreases from the current value I1' to the current value I1, the value of the first output voltage of the first conversion device 5A changes to , from the voltage value F1′ to the voltage value F1 (see arrow AR2).

In order for the first converter 5A to exhibit the first voltage droop characteristic, the DC power supply system 100A in the first embodiment requires the first output current (more specifically, the second current flowing through the wire L2) can be detected. The first conversion device 5A reduces (or increases) the first output voltage according to the increase (or decrease) of the first output current. In the example shown in FIG. 1, the first current detector 9A for detecting the first output current is incorporated in the first conversion device 5A, but the first current detector 9A and the first conversion device 5A are separate may be

The second converter 5B is arranged between the second battery 40B and the DC bus 2, and converts the second battery voltage on the side of the second battery 40B to the output voltage on the side of the DC bus 2 (hereinafter, "second output voltage"). ). More specifically, the second conversion device 5B, based on the target voltage of the DC bus 2 (or a second output voltage command value described later) and the second voltage droop characteristic, the second battery 40B side 2 battery voltage is stepped up or down to the second output voltage on the DC bus 2 side.

In this specification, the second voltage droop characteristic means that the output current of the second conversion device 5B (hereinafter referred to as “second output current”) increases, and the second voltage droop characteristic of the second conversion device 5B increases. 2 means the characteristic that the output voltage drops.

In the example shown in FIG. 1, the second battery 40B and the second converter 5B are connected via the third electric wire L3, and the second converter 5B and the DC bus 2 are connected via the fourth electric wire L4. ing. In this case, the second converter 5B steps up and down the voltage on the third wire L3 to the voltage on the fourth wire L4.

The second voltage droop characteristic of the second converter 5B will be described with reference to FIG. In the example shown in FIG. 2, the target voltage of DC bus 2 is voltage V1. In the example shown in FIG. 2, when the value of the second output current of the second conversion device 5B increases from the current value I1 to the current value I1′, the value of the second output voltage of the second conversion device 5B changes to voltage From value F1, it drops to voltage value F1' (see arrow AR3). On the other hand, in the example shown in FIG. 2, when the value of the second output current of the second conversion device 5B decreases from the current value I1' to the current value I1, the value of the second output voltage of the second conversion device 5B changes to , from the voltage value F1′ to the voltage value F1 (see arrow AR4).

In order for the second converter 5B to exhibit the second voltage droop characteristic, the DC power supply system 100A in the first embodiment uses the second output current (more specifically, the fourth current flowing through the wire L4) can be detected. The second converter 5B reduces (or increases) the second output voltage in accordance with the increase (or decrease) of the second output current. In the example shown in FIG. 1, the second current detector 9B for detecting the second output current is incorporated in the second conversion device 5B, but the second current detector 9B and the second conversion device 5B are separate may be

In the example illustrated in FIG. 2, the second voltage droop characteristic of the second converter 5B is equal to the first voltage droop characteristic of the first converter 5A. Alternatively, the second voltage droop characteristic of the second converter 5B may be different than the first voltage droop characteristic of the first converter 5A.

As illustrated in FIG. 2, when each of the first converter 5A and the second converter 5B has a voltage droop characteristic, when the first converter 5A and the second converter 5B are operated in parallel, the first The occurrence of a cross current between the first conversion device 5A and the second conversion device 5B is suppressed.

The first output unit 6A changes according to the remaining amount of the first energy stored in the first power supply 4A (more specifically, the first remaining battery amount that is the remaining battery amount of the first battery 40A). A physical quantity is detected or calculated, and a signal indicating the first physical quantity is output to the control circuit 7 . The first physical quantity may be any physical quantity that changes according to the first battery remaining amount of the first battery 40A. The first physical quantity may include a plurality of physical quantities that change according to the first battery remaining amount of the first battery 40A. The first output section 6A is an arbitrary output section that outputs a signal indicating the first physical quantity to the control circuit 7 . Needless to say, the signal output from the first output section 6A to the control circuit 7 may be performed via any element or any configuration.

In the example shown in FIG. 1, the first physical quantity is the battery voltage of the first battery 40A (hereinafter referred to as "first battery voltage"), and the first output unit 6A outputs the first battery voltage of the first battery 40A. A first voltage detector 60A detects a first battery voltage that changes according to the remaining amount.

A voltage divider, isolator, or the like is used as the first voltage detector 60A. In the example shown in FIG. 1, the first voltage detector 60A detects the voltage in the first wire L1 between the first battery 40A and the first converter 5A as the first battery voltage.

The first voltage detector 60A may be incorporated in a PLC (Programmable Logic Controller), the first converter 5A, the first BMU 3A, or the like.

The second output unit 6B outputs a second energy that changes according to the remaining amount of the second energy stored in the second power supply 4B (more specifically, the second battery remaining amount that is the remaining battery amount of the second battery 40B). A physical quantity is detected or calculated, and a signal indicating the second physical quantity is output to the control circuit 7 . The second physical quantity may be any physical quantity that changes according to the second battery remaining amount of the second battery 40B. The second physical quantity may include a plurality of physical quantities that change according to the second battery level of second battery 40B. The second output section 6B is an arbitrary output section that outputs a signal indicating the second physical quantity to the control circuit 7 . Needless to say, the signal output from the second output section 6B to the control circuit 7 may be performed via any element or any configuration.

In the example shown in FIG. 1, the second physical quantity is the battery voltage of the second battery 40B (hereinafter referred to as "second battery voltage"), and the second output unit 6B outputs the second battery voltage of the second battery 40B. A second voltage detector 60B that detects a second battery voltage that changes according to the remaining amount.

A voltage divider, isolator, or the like is used as the second voltage detector 60B. In the example illustrated in FIG. 1, the second voltage detector 60B detects the voltage in the third wire L3 between the second battery 40B and the second converter 5B as the second battery voltage.

The second voltage detector 60B may be incorporated in a PLC (Programmable Logic Controller), the second converter 5B, the second BMU 3B, or the like.

The control circuit 7 determines a first output voltage command value for the first conversion device 5A and a second output voltage command value for the second conversion device 5B based on the first physical quantity and the second physical quantity. More specifically, the control circuit 7 receives a signal indicating the first physical quantity from the first output section 6A, receives a signal indicating the second physical quantity from the second output section 6B, and based on the first physical quantity and the second physical quantity Then, the first output voltage command value for the first conversion device 5A and the second output voltage command value for the second conversion device 5B are determined.

When the first output section 6A is the first voltage detector 60A and the second output section 6B is the second voltage detector 60B, the control circuit 7 is detected by the first voltage detector 60A. A first battery voltage (in other words, a first signal indicating the first battery voltage received from the first voltage detector 60A) and a second battery voltage detected by the second voltage detector 60B (in other words, a second Based on the second signal indicating the second battery voltage received from the voltage detector 60B), the first output voltage command value for the first converter 5A and the second output voltage command value for the second converter 5B are determined. do.

In addition, the control circuit 7 outputs the determined first output voltage command value (in other words, the first control command corresponding to the first output voltage command value) to the first conversion device 5A, and the determined second An output voltage command value (in other words, a second control command corresponding to the second output voltage command value) is output to the second converter 5B.

Based on the first output voltage command value received from the control circuit 7 (in other words, the first control command corresponding to the first output voltage command value) and the first voltage droop characteristic, the first conversion device 5A The first battery voltage on the 1 battery 40A side is stepped up or down to the first output voltage on the DC bus 2 side. In addition, the second converter 5B receives the second output voltage command value from the control circuit 7 (in other words, the second control command corresponding to the second output voltage command value) and the second voltage droop characteristic. , the second battery voltage on the second battery 40B side is stepped up or down to the second output voltage on the DC bus 2 side.

(Action: power supply to DC bus 2)
In the example shown in FIG. 1, the control circuit 7 controls the first battery 40A and the second battery 40B so that the power share ratio of the battery with the smaller remaining battery level is reduced. An output voltage command value and a second output voltage command value for the second converter 5B are determined. Further, the control circuit 7 outputs a first control command corresponding to the determined first output voltage command value to the first converter 5A, and outputs a second control command corresponding to the determined second output voltage command value. Output to the second converter 5B. As a result, the first output voltage of the first conversion device 5A and/or the second output voltage of the second conversion device 5B change, and the power share ratio of the battery with the smaller remaining battery capacity is reduced. In this way, the timing at which the remaining battery level becomes zero for each battery is prevented from greatly varying.

More specifically, in the example illustrated in FIG. 1, control circuit 7 receives a first signal indicative of a first battery voltage of first battery 40A from first voltage detector 60A and a first signal from second voltage detector 60B. A second signal is received indicative of a second battery voltage of the second battery 40B. Based on the first battery voltage of the first battery 40A and the discharge characteristic of the first battery 40A, the control circuit 7 calculates the first remaining battery capacity of the first battery 40A, calculates the second battery voltage of the second battery 40B and A second battery remaining amount of the second battery 40B is calculated based on the discharge characteristics of the second battery 40B.

When the first battery remaining amount of the first battery 40A is less than the second battery remaining amount of the second battery 40B, the control circuit 7 reduces the power share ratio of the first battery 40A and the power of the second battery 40B. The first output voltage command value for the first conversion device 5A and the second output voltage command value for the second conversion device 5B are determined so that the burden ratio is increased.

Further, the control circuit 7 outputs a first control command corresponding to the determined first output voltage command value to the first converter 5A, and outputs a second control command corresponding to the determined second output voltage command value. Output to the second converter 5B.

5 A of 1st converters which receive a 1st control command reduce a 1st output voltage based on a 1st output voltage command value. Thus, the power share of the first battery 40A is reduced, and the power share of the second battery 40B is increased. Alternatively or additionally, the second converter 5B that receives the second control command may increase the second output voltage based on the second output voltage command value.

On the other hand, when the second battery remaining amount of the second battery 40B is less than the first battery remaining amount of the first battery 40A, the control circuit 7 reduces the power share of the second battery 40B and The first output voltage command value for the first conversion device 5A and the second output voltage command value for the second conversion device 5B are determined so that the power share ratio of is increased.

Further, the control circuit 7 outputs a first control command corresponding to the determined first output voltage command value to the first converter 5A, and outputs a second control command corresponding to the determined second output voltage command value. Output to the second converter 5B.

The second conversion device 5B that receives the second control command reduces the second output voltage based on the second output voltage command value. Thus, the power share of the second battery 40B is reduced, and the power share of the first battery 40A is increased.

In this specification, the first battery remaining amount may mean the amount of charge of the first battery 40A with respect to the amount of full charge of the first battery 40A (that is, the ratio to the amount of full charge). Specifically, the first battery remaining amount may mean the amount of energy itself (that is, the amount of charge itself) stored in the first battery 40A. In addition, the second battery remaining amount may mean the amount of charge of the second battery 40B with respect to the amount of full charge of the second battery 40B (that is, the ratio to the amount of full charge). The remaining battery capacity may mean the amount of energy itself (that is, the amount of charge itself) stored in the second battery 40B.

3 and 4, an example of the relationship between the remaining battery capacity of each battery (40A, 40B) and the output voltage command value for each converter (5A, 5B) in the comparative example (FIG. 3), and An example (FIG. 4) of the relationship between the remaining battery capacity of each battery (40A, 40B) and the output voltage command value for each converter (5A, 5B) in the first embodiment will be described. 3 and 4, as illustrated in FIG. 1, the load 1A is connected to the DC bus 2, and the first battery 40A and the second battery 40B supply power to the load 1A via the DC bus 2. An example of when to do so is assumed.

FIGS. 3(a) and 4(a) show temporal changes in the first output voltage command value for the first converter 5A and temporal changes in the first remaining battery capacity of the first battery 40A. . 3(b) and 4(b) show temporal changes in the second output voltage command value for the second converter 5B and temporal changes in the second battery remaining amount of the second battery 40B. ing. It is assumed that the passage of time in FIG. 3(a) and the passage of time in FIG. 3(b) proceed concurrently. Similarly, it is assumed that the passage of time in FIG. 4(a) and the passage of time in FIG. 4(b) proceed concurrently.

In the examples shown in FIGS. 3 and 4, until time t2, the first output voltage command value for first converter 5A is voltage V1, and the second output voltage command value for second converter 5B is voltage V1. Yes, the first output voltage command value and the second output voltage command value are the same value. 3 and 4, the battery capacity of the first battery 40A shall be smaller than the battery capacity of the second battery 40B.

When the battery capacity of the first battery 40A is smaller than the battery capacity of the second battery 40B, if each battery equally shares the power supplied to the DC bus 2, the first battery remaining amount of the first battery 40A is It drops faster than the second battery remaining amount of the second battery 40B. Therefore, in the example shown in FIGS. 3 and 4, the first battery remaining amount of the first battery 40A at the time t2 is the remaining amount P1, and the second battery remaining amount of the second battery 40B at the time t2 is the remaining amount P2. , P1<P2.

In this state, as illustrated in FIG. 3, when the first output voltage command value for the first converter 5A and the second output voltage command value for the second converter 5B are maintained at voltage V1, time At t4, the first battery remaining amount of the first battery 40A becomes zero, and the first converter 5A stops. Such a stoppage of the first conversion device 5A leads to the occurrence of excessive power in the second conversion device 5B or a reduction in the redundancy of the conversion device.

Therefore, as illustrated in FIG. 4, according to the first embodiment, at time t2, the control circuit 7 sets the first output voltage command value for the first conversion device 5A to the voltage V2, which is lower than the voltage V1. , and outputs the first control command corresponding to the first output voltage command value to the first converter 5A. The first conversion device 5A that receives the first control command steps up and down the first battery voltage to the first output voltage based on the decreased first output voltage command value. As a result, the power share of the first battery 40A is reduced and the power share of the second battery 40B is increased. In this way, the timing at which the charge amount of the first battery 40A becomes zero can be delayed from time t4.

Alternatively, at time t2, the control circuit 7 determines the second output voltage command value for the second converter 5B to be a voltage higher than the voltage V1, and performs the second control corresponding to the second output voltage command value. The command may be output to the second conversion device 5B. The second conversion device 5B that receives the second control command steps up and down the second battery voltage to the second output voltage based on the increased second output voltage command value. As a result, the power share of the second battery 40B is increased, and the power share of the first battery 40A is reduced. In this way, the timing at which the remaining battery capacity of the first battery 40A becomes zero can be delayed from time t4.

In the first embodiment, if a DC power supply system is adopted in which the power load of each battery is proportionally distributed according to the battery capacity of each battery, theoretically, the remaining battery capacity It is possible to operate a plurality of batteries so that the ratio of the amounts does not vary. However, depending on how each battery is used or how the battery is replaced, the ratio of the remaining battery capacity to the battery capacity may vary from battery to battery. In this case, the remaining battery charge of one battery reaches zero prior to the remaining battery charge of the other battery.

The first embodiment can also handle such cases. More specifically, the control circuit 7 controls the output voltage for each conversion device so that the power burden ratio of a battery having a small ratio of remaining battery capacity to battery capacity among the plurality of batteries (40A, 40B) is reduced. A command value is determined, and a control command corresponding to the determined output voltage command value is output to each converter (5A, 5B). As a result, the power burden ratio of a battery with a relatively small remaining battery capacity (%) is reduced. As a result, the remaining battery charge of one battery is prevented or suppressed from reaching zero prior to the remaining battery charge of the other batteries. It should be noted that "prevention" here means that the remaining battery levels of a plurality of batteries become zero at substantially the same time. Also, the term "restraint" here means that the timing at which the remaining battery charge of one battery reaches zero prior to the remaining battery charge of another battery is delayed.

In the example shown in FIG. 4, the timing at which the first output voltage command value is changed is the first battery remaining amount of the first battery 40A (for example, the first battery voltage of the first battery 40A and the first battery 40A The first battery remaining amount of the first battery calculated from the discharge characteristics of the first battery reaches a predetermined remaining amount P1.

Alternatively, a plurality of timings for changing the first output voltage command value may be set. For example, at the timing when the first remaining battery capacity of the first battery 40A reaches the first predetermined value, the first output voltage command value for the first conversion device 5A is changed from the voltage V1 to the voltage V2 lower than the voltage V1. Then, at the timing when the first battery remaining amount of the first battery 40A becomes a second predetermined value that is lower than the first predetermined value, the first output voltage command value for the first converter 5A changes from the voltage V2 to the voltage It may be changed to a voltage lower than V2.

Further alternatively, the timing at which the first output voltage command value is changed is not determined depending only on the first battery remaining amount of the first battery 40A, but is based on the first battery remaining amount of the first battery 40A. and time (for example, the discharge time from the first battery 40A, or the time until the first battery remaining amount of the first battery 40A becomes zero when the first output voltage command value is not changed, etc.) may be determined based on

Further, after the first output voltage command value for the first converter 5A is changed from the voltage V1 to the voltage V2, the first battery remaining amount of the first battery 40A and the second battery remaining amount of the second battery 40B are At the matching timing, the first output voltage command value of the first conversion device 5A may be returned from the voltage V2 to the voltage V1.

In the example shown in FIG. 1, the number of converters (5A, 5B) connected in parallel to the DC bus 2 is two, but the number of converters connected in parallel to the DC bus 2 is , three or more.

In the first embodiment, the first output voltage command value for the first converter 5A and / Alternatively, in addition to changing the second output voltage command value for the second converter 5B, each of the first converter 5A and the second converter 5B has a voltage droop characteristic.

An example in which the output voltage command value of the converters (5A, 5B) is changed under the condition that the converters (5A, 5B) have voltage droop characteristics will be described with reference to FIGS. 2 and 5 .

FIG. 2 shows the state before the control circuit 7 outputs the first control command and the second control command for reducing the power share ratio of the first battery 40A or the second battery 40B, whichever has the smaller remaining battery capacity. An example of the relationship between the first output current of the first converter 5A and the first output voltage of the first converter 5A at the time (hereinafter referred to as "time t1"), and the second converter 5B It is a graph which shows an example of the relationship between a 2nd output current and the 2nd output voltage of the 2nd converter 5B. Note that time t1 is an arbitrary time between time t0 and time t2 in the example shown in FIG.

On the other hand, in FIG. 5, the control circuit 7 outputs the first control command and the second control command for reducing the power share ratio of the one of the first battery 40A and the second battery 40B with the smaller remaining battery capacity. An example of the relationship between the first output current of the first converter 5A and the first output voltage of the first converter 5A at a later time (hereinafter referred to as "time t3"), and the second converter It is a graph which shows an example of the relationship between the 2nd output current of 5B, and the 2nd output voltage of the 2nd converter 5B. Note that time t3 is an arbitrary time between time t2 and time t4 in the example shown in FIG.

In the example shown in FIG. 2, at time t1, the first output voltage command value received by the first converter 5A from the control circuit 7 and the second output voltage command value received by the second converter 5B from the control circuit 7 are Identical, the first output voltage command value and the second output voltage command value respectively match the value of the target voltage V1 of the DC bus 2 . Since the first conversion device 5A has a first voltage droop characteristic, the value of the first output voltage of the first conversion device 5A at time t1 is the voltage value F1, and the first output of the first conversion device 5A at time t1 The value of the current is the current value I1. Since the second conversion device 5B has a second voltage droop characteristic, the value of the second output voltage of the second conversion device 5B at time t1 is the voltage value F1, and the second output of the second conversion device 5B at time t1 The value of the current is the current value I1. For simplicity, at time t1, the first voltage droop characteristic and the second voltage droop characteristic are the same, and the value of the first output voltage of the first converter 5A and the value of the second output voltage of the second converter 5B are the same. It is assumed that the value of the output voltage is the same, and the value of the first output current of the first converter 5A and the value of the second output current of the second converter 5B are the same.

At time t1, when the first output current of the first conversion device 5A increases, the first output voltage of the first conversion device 5A decreases (see arrow AR1), and the first output current of the first conversion device 5A increases to As it decreases, the first output voltage of the first conversion device 5A rises. Further, at time t1, when the second output current of the second converter 5B increases, the second output voltage of the second converter 5B decreases (see arrow AR3), and the second output of the second converter 5B As the current decreases, the second output voltage of the second converter 5B increases. These voltage droop characteristics are exhibited regardless of the remaining battery capacity of each battery.

In the example shown in FIG. 5, at time t3 after time t2, the first conversion device The first output voltage command value received by 5A from the control circuit 7 is lowered from the voltage V1 (more specifically, the value of the target voltage V1 of the DC bus 2) to the voltage V2 (see arrow AR5). The second output voltage command value received by the second conversion device 5B from the control circuit 7 is maintained at the voltage V1 (more specifically, the value of the target voltage V1 of the DC bus 2).

Since the first conversion device 5A has the first voltage droop characteristic, the value of the first output voltage of the first conversion device 5A at time t3 is the second voltage value F, and the first output voltage of the first conversion device 5A at time t3 is The value of one output current is the current value I2. Since the second converter 5B has a second voltage droop characteristic, the value of the second output voltage of the second converter 5B at time t3 is the second voltage value F, and the second output voltage of the second converter 5B at time t3 is The value of the two output currents is the current value I3.

In the example shown in FIG. 5, current value I2 is smaller than current value I3. Therefore, of the first battery 40A and the second battery 40B, the power share of the first battery 40A, which has the smaller remaining battery capacity (see the area hatched with dots), is reduced, and the first battery 40A is reduced. and the second battery 40B, the power share ratio of the second battery 40B with the larger remaining battery capacity (see the area hatched with oblique lines) is increased.

At time t3, when the first output current of the first conversion device 5A increases, the first output voltage of the first conversion device 5A decreases (see arrow AR6), and the first output current of the first conversion device 5A decreases to When it decreases, the first output voltage of the first conversion device 5A rises (see arrow AR7). Further, at time t3, when the second output current of the second conversion device 5B increases, the second output voltage of the second conversion device 5B decreases (see arrow AR8), and the second output of the second conversion device 5B As the current decreases, the second output voltage of the second converter 5B increases (see arrow AR9). These droop characteristics are exhibited even after the output voltage command value of the converter (5A, 5B) is changed based on the remaining battery capacity of each battery.

(Action: power reception from DC bus 2)
In the example illustrated in FIG. 6 , the control circuit 7 controls the first battery 40A and the second battery 40B so that the power reception rate of the battery with the greater remaining battery level is reduced. An output voltage command value and a second output voltage command value for the second converter 5B are determined.

Further, the control circuit 7 outputs a first control command corresponding to the determined first output voltage command value to the first converter 5A, and outputs a second control command corresponding to the determined second output voltage command value. Output to the second converter 5B. As a result, the first output voltage of the first conversion device 5A and/or the second output voltage of the second conversion device 5B change, and the power reception ratio of the battery with the greater remaining energy is reduced. In this way, it is possible to prevent the timing of reaching full charge from varying greatly for each battery.

More specifically, in the example shown in FIG. 6, the control circuit 7 receives a first signal indicative of the first battery voltage of the first battery 40A from the first voltage detector 60A, and from the second voltage detector 60B. A second signal is received indicative of a second battery voltage of the second battery 40B. Based on the first battery voltage of the first battery 40A and the discharge characteristic of the first battery 40A, the control circuit 7 calculates the first remaining battery capacity of the first battery 40A, calculates the second battery voltage of the second battery 40B and A second battery remaining amount of the second battery 40B is calculated based on the discharge characteristics of the second battery 40B.

When the first battery remaining amount of the first battery 40A is greater than the second battery remaining amount of the second battery 40B, the control circuit 7 reduces the power reception ratio of the first battery 40A and the power of the second battery 40B. The first output voltage command value for the first conversion device 5A and the second output voltage command value for the second conversion device 5B are determined so that the power reception ratio is increased.

Further, the control circuit 7 outputs a first control command corresponding to the determined first output voltage command value to the first converter 5A, and outputs a second control command corresponding to the determined second output voltage command value. Output to the second converter 5B.

5 A of 1st converters which receive 1st control instruction|command increase a 1st output voltage based on a 1st output voltage command value. Thus, the power reception ratio of the first battery 40A is reduced, and the power reception ratio of the second battery 40B is increased.

7 and 8, an example of the relationship between the remaining battery capacity of each battery (40A, 40B) and the output voltage command value for each converter (5A, 5B) in the comparative example (FIG. 7), and An example (FIG. 8) of the relationship between the remaining battery capacity of each battery (40A, 40B) and the output voltage command value for each converter (5A, 5B) in the first embodiment will be described. 7 and 8, as illustrated in FIG. 6, the DC bus 2 is connected to the charging power supply 1B, and the first battery 40A and the second battery 40B are connected via the DC bus 2 for charging. An example of receiving power from power source 1B is assumed.

FIGS. 7(a) and 8(a) show temporal changes in the first output voltage command value for the first converter 5A and temporal changes in the first remaining battery capacity of the first battery 40A. . 7(b) and 8(b) show changes over time in the second output voltage command value for the second converter 5B and changes over time in the second battery remaining amount of the second battery 40B. ing. It is assumed that the passage of time in FIG. 7(a) and the passage of time in FIG. 7(b) proceed concurrently. Similarly, it is assumed that the passage of time in FIG. 8(a) and the passage of time in FIG. 8(b) proceed concurrently.

7 and 8, until time t2, the first output voltage command value for first converter 5A is voltage V1, and the second output voltage command value for second converter 5B is voltage V1. Yes, the first output voltage command value and the second output voltage command value are the same value.

In the example shown in FIG. 7, at time t2, the first remaining battery charge P of the first battery 40A is greater than the second remaining battery charge P' of the second battery 40B. In the example shown in FIG. 7, when the power receiving rate from DC bus 2 is maintained for each of first battery 40A and second battery 40B, at time t4, first battery 40A is connected to second battery 40B. It will be fully charged first.

When the first battery 40A is fully charged, the first converter 5A stops. Such a stoppage of the first conversion device 5A leads to the occurrence of excessive power in the second conversion device 5B or a reduction in the redundancy of the conversion device.

Therefore, as illustrated in FIG. 8, according to the first embodiment, at time t2, the control circuit 7 sets the first output voltage command value for the first converter 5A to the voltage V3 higher than the voltage V1. , and outputs the first control command corresponding to the first output voltage command value to the first converter 5A. The first conversion device 5A that receives the first control command steps up and down the first battery voltage to the first output voltage based on the increased first output voltage command value. As a result, the power reception ratio of the first battery 40A is reduced, and the power reception ratio of the second battery 40B is increased. Thus, the timing at which the first battery 40A is fully charged can be delayed from time t4.

In the example shown in FIG. 8, the timing at which the first output voltage command value is changed is only the timing at which the first battery remaining amount of the first battery 40A reaches a predetermined remaining amount (P).

Alternatively, a plurality of timings for changing the first output voltage command value may be set. For example, at the timing when the first battery remaining amount of the first battery 40A reaches the first predetermined value, the first output voltage command value for the first conversion device 5A is changed from the voltage V1 to the voltage V3 higher than the voltage V1. Then, at the timing when the first battery remaining amount of the first battery 40A becomes a second predetermined value higher than the first predetermined value, the first output voltage command value for the first converter 5A changes from the voltage V3 to the voltage It may be changed to a voltage higher than V3.

Further alternatively, the timing at which the first output voltage command value is changed is not determined depending only on the first battery remaining amount of the first battery 40A, but is based on the first battery remaining amount of the first battery 40A. and time (for example, the charging time of the first battery 40A, or the time until the first battery 40A is fully charged when the first output voltage command value is not changed, etc.). good too.

Further, after the first output voltage command value for the first converter 5A is changed from the voltage V1 to the voltage V3, the first battery remaining amount of the first battery 40A and the second battery remaining amount of the second battery 40B are At the matching timing, the first output voltage command value of the first conversion device 5A may be returned from the voltage V3 to the voltage V1.

In the first embodiment, the first output voltage command value for the first conversion device 5A and / Alternatively, in addition to changing the second output voltage command value for the second converter 5B, each of the first converter 5A and the second converter 5B has a voltage droop characteristic. Since the voltage droop characteristic has already been described using FIG. 2, FIG. 5, etc., a repeated description of the voltage droop characteristic will be omitted.

(effect)
In the DC power supply system 100A in the first embodiment, when the energy capacity of each power supply or the characteristics of each power supply is different, the output voltage command value of at least one converter is changed according to the remaining energy of each power supply. By doing so, the power share ratio of each power supply is adjusted. In this way, the remaining energy of one power supply is prevented or suppressed from reaching zero ahead of the remaining energy of the other power supply. As a result, operation of multiple converters is maintained, overpowering of a particular converter is prevented, and converter redundancy is maintained. Thus, the first embodiment provides a stable DC power supply system.

Further, in the DC power supply system 100A in the first embodiment, the output voltage command value of at least one converter is changed according to the remaining energy of each power supply, and the voltage droop characteristic of each converter and changing the output voltage of the converter based on the output voltage. Therefore, even before changing the output voltage command value of at least one converter according to the remaining energy of each power supply, after changing the output voltage command value of at least one converter according to the remaining energy of each power supply Also, the occurrence of cross currents between a plurality of conversion devices is suppressed.

Further, in the first embodiment, when power is supplied from the charging power source 1B to the plurality of power sources (4A, 4B) via the DC bus 2, the remaining energy of each power source (in other words, each power source The power reception rate of each power supply is adjusted by changing the output voltage command value of at least one conversion device according to the amount of energy stored in the power supply. In this way, the energy storage of one power supply is prevented or suppressed from becoming FULL prior to the energy storage of the other power supply. As a result, operation of multiple converters is maintained, overpowering of a particular converter is prevented, and converter redundancy is maintained. Thus, the first embodiment provides a stable DC power supply system.

(Second embodiment)
A DC power supply system 100B in the second embodiment will be described with reference to FIG. FIG. 9 is a diagram schematically showing an example of a circuit configuration of a DC power supply system 100B according to the second embodiment.

In the second embodiment, the points different from the first embodiment will be mainly described. On the other hand, in the second embodiment, repetitive explanations of matters already explained in the first embodiment will be omitted. Therefore, it goes without saying that the matters already explained in the first embodiment can be applied to the second embodiment even if they are not explicitly explained in the second embodiment.

(composition)
In the second embodiment, the first output unit 6A is the "first estimated charge amount calculator 62A", the second output unit 6B is the "second estimated charge amount calculator 62B", and the second output unit 6B is the "second estimated charge amount calculator 62B". The first physical quantity detected or calculated by the 1 output unit 6A (first estimated charge amount calculation unit 62A) is the "estimated charge amount of the first battery 40A (hereinafter referred to as "first estimated charge amount")", The second physical quantity detected or calculated by the second output unit 6B (second estimated charge amount calculation unit 62B) is the "estimated charge amount of the second battery 40B (hereinafter referred to as "second estimated charge amount")". It is different from the first embodiment in this respect. Otherwise, the second embodiment is similar to the first embodiment.

A DC power supply system 100B in the second embodiment includes a DC bus 2 to which one or both of a load 1A and a charging power supply 1B are connected, a first battery 40A as a first power supply 4A, and a second power supply 4B as The second battery 40B, the first BMU 3A, the second BMU 3B, the first conversion device 5A, the second conversion device 5B, and the first estimated charge amount calculation unit 62A as the first output unit 6A , a second estimated charge amount calculating section 62B as a second output section 6B, and a control circuit 7. FIG. One of the first BMU 3A and the second BMU 3B, or both the first BMU 3A and the second BMU 3B may be omitted.

(Action)
In the second embodiment, the configuration or control associated with the first estimated charge amount calculation unit 62A and the second estimated charge amount calculation unit 62B will be mainly described, and repeated description of other matters will be omitted. do.

The first estimated charge amount calculator 62A calculates a first estimated charge amount (for example, SOC (State Of Charge)) of the first battery 40A, and outputs a third signal indicating the first estimated charge amount to the control circuit 7. output to Needless to say, the output of the third signal from the first estimated charge amount calculator 62A to the control circuit 7 may be performed via any element or any configuration.

A second estimated charge amount calculator 62B calculates a second estimated charge amount (for example, SOC (State Of Charge)) of the second battery 40B, and outputs a fourth signal indicating the second estimated charge amount to the control circuit 7. output to Needless to say, the output of the fourth signal from the second estimated charge amount calculator 62B to the control circuit 7 may be performed via any element or any configuration.

In the example shown in FIG. 9, the first estimated charge amount calculation unit 62A calculates the first estimated charge amount of the first battery 40A based on the signal received from the first BMU 3A, and calculates the second estimated charge amount. The amount calculator 62B calculates a second estimated charge amount of the second battery 40B based on the signal received from the second BMU 3B. Alternatively, the first estimated charge amount calculator 62A may calculate the first estimated charge amount of the first battery 40A based on the signal received from the first conversion device 5A, and the second estimated charge amount may be calculated. The amount calculator 62B may calculate the second estimated charge amount of the second battery 40B based on the signal received from the second converter 5B. For example, the first estimated charge amount of the first battery 40A may be calculated based on the integrated value of the current passing through the first wire L1, or a combination of the integrated value and environmental conditions such as temperature. Further, the second estimated charge amount of the second battery 40B may be calculated based on the integrated value of the current passing through the third electric wire L3 or a combination of the integrated value and environmental conditions such as temperature.

Further alternatively, the first estimated charge amount calculation unit 62A receives the first battery charge amount from another control circuit other than the control circuit 7, a PLC, or the like, or the electric amount information for estimating the first battery charge amount. , the estimated charge amount of the first battery 40A may be calculated. Similarly, the second estimated charge amount calculation unit 62B calculates the second battery charge amount or the electric amount information for estimating the second battery charge amount received from a control circuit other than the control circuit 7, a PLC, or the like. The estimated charge amount of the second battery 40B may be calculated.

In addition, in the "calculation of the estimated charge amount", the first BMU 3A, the second BMU 3B, the first conversion device 5A, the second conversion device 5B, another control circuit different from the control circuit 7, or a PLC, etc. It also includes using the estimated charge amount calculated by as it is.

In the example shown in FIG. 9, the control circuit 7 is based on the first estimated charge amount and the second estimated charge amount, the first output voltage command value for the first converter 5A and the second output for the second converter 5B Determine the voltage command value. More specifically, when the first estimated charge amount of the first battery 40A is smaller than the second estimated charge amount of the second battery 40B, the control circuit 7 reduces the power share of the first battery 40A, The first output voltage command value for the first conversion device 5A and the second output voltage command value for the second conversion device 5B are determined so that the power share ratio of the second battery 40B is increased.

(effect)
The second embodiment has the same effect as the first embodiment.

(Third embodiment)
A DC power supply system 100C according to the third embodiment will be described with reference to FIGS. 10 to 13. FIG. FIG. 10 is a diagram schematically showing an example of the circuit configuration of a DC power supply system 100C according to the third embodiment. FIG. 11 is a diagram showing an example of voltage droop characteristics of the converters (5A, 5B) of the DC power supply system 100C in the third embodiment. FIG. 12 is a diagram schematically showing a state after the voltage droop characteristic of the first conversion device 5A is changed. FIG. 13 is a diagram schematically showing an example of the circuit configuration of a DC power supply system 100C according to the third embodiment. FIG. 13 shows how the batteries (40A, 40B) are being charged.

3rd Embodiment demonstrates centering on a different point from 1st Embodiment and 2nd Embodiment. On the other hand, in the third embodiment, repetitive descriptions of matters already explained in the first or second embodiment will be omitted. Therefore, it goes without saying that the matters already explained in the first or second embodiment can be applied to the third embodiment even if they are not explicitly explained in the third embodiment.

(composition)
A DC power supply system 100C in the third embodiment has a first droop control unit 10A that adjusts the first voltage droop characteristic and a second droop control unit 10B that adjusts the second voltage droop characteristic. It differs from the DC power supply system 100A in the first embodiment and the DC power supply system 100B in the second embodiment. Otherwise, the third embodiment is similar to the first or second embodiment.

A DC power supply system 100C in the third embodiment includes, as illustrated in FIG. 10, a DC bus 2 to which one or both of a load 1A and a charging power source 1B are connected, a first power source 4A (for example, a 1 battery 40A), a second power supply 4B (for example, a second battery 40B), a first BMU 3A, a second BMU 3B, a first conversion device 5A, a second conversion device 5B, and a first output unit 6A, a second output section 6B, a first current detector 9A, a second current detector 9B, a first droop control section 10A, and a second droop control section 10B. One of the first BMU 3A and the second BMU 3B, or both the first BMU 3A and the second BMU 3B may be omitted.

Load 1A, charging power source 1B, DC bus 2, first power source 4A (eg, first battery 40A), second power source 4B (eg, second battery 40B), first BMU 3A, second BMU 3B, first Since the conversion device 5A, the second conversion device 5B, the first output section 6A, and the second output section 6B have already been described in the first embodiment or the second embodiment, these configurations will be repeated. Description is omitted.

In the following, the first power source 4A is a first rechargeable battery 40A (eg, a first battery group), and the second power source 4B is a second rechargeable battery 40B (eg, a second battery group). An example in the case of is described. However, in the third embodiment, at least one of the first power source 4A and the second power source 4B may be a power source other than a rechargeable battery.

In other words, in the following description of the third embodiment, "first battery 40A", "second battery 40B", "battery voltage", "first battery voltage", "second battery voltage", "battery Remaining capacity", "first battery remaining capacity", and "second battery remaining capacity" are respectively "first power supply 4A", "second power supply 4B", "power supply voltage", "first power supply voltage", " It can be read as "second power supply voltage", "remaining energy", "first remaining energy", and "second remaining energy".

The first output unit 6A detects or calculates a first physical quantity that changes according to the first remaining battery capacity of the first battery 40A, and outputs a signal indicating the first physical quantity to the control circuit 7 . The first physical quantity may be any physical quantity that changes according to the first battery remaining amount of the first battery 40A. The first physical quantity may include a plurality of physical quantities that change according to the first battery remaining amount of the first battery 40A. The first output section 6A is an arbitrary output section that outputs a signal indicating the first physical quantity to the control circuit 7 . Needless to say, the signal output from the first output section 6A to the control circuit 7 may be performed via any element or any configuration. The first output unit 6A may include a first voltage detector 60A that detects a first battery voltage of the first battery 40A, and a first estimated charge that calculates a first estimated charge of the first battery 40A. The amount calculator 62A may be included, or both the first voltage detector 60A and the first estimated charge amount calculator 62A may be included.

The second output unit 6B detects or calculates a second physical quantity that changes according to the second battery remaining amount of the second battery 40B, and outputs a signal indicating the second physical quantity to the control circuit 7 . The second physical quantity may be any physical quantity that changes according to the second battery remaining amount of the second battery 40B. The second physical quantity may include a plurality of physical quantities that change according to the second battery level of second battery 40B. The second output section 6B is an arbitrary output section that outputs a signal indicating the second physical quantity to the control circuit 7 . Needless to say, the signal output from the second output section 6B to the control circuit 7 may be performed via any element or any configuration. The second output unit 6B may include a second voltage detector 60B that detects a second battery voltage of the second battery 40B, and a second estimated charge that calculates a second estimated charge of the second battery 40B. The amount calculator 62B may be included, or both the second voltage detector 60B and the second estimated charge amount calculator 62B may be included.

The first voltage detector 60A, the second voltage detector 60B, the first estimated charge amount calculator 62A, and the second estimated charge amount calculator 62B are described in the first embodiment or the second embodiment. Since the description has already been made, a repeated description of these configurations will be omitted.

9 A of 1st electric current detectors detect the 1st output electric current which 5 A of 1st converters output to the DC bus-line 2. FIG. More specifically, the first current detector 9A detects the first output current flowing through the second electric wire L2 between the first conversion device 5A and the DC bus 2 . Also, the first current detector 9A outputs a first current signal indicating the first output current to the first droop control section 10A. For example, a CT (Current Transformer), a current probe, or the like is used as the first current detector 9A. In addition, the first current detector 9A may be incorporated in the PLC, the first converter 5A, the first BMU 3A, or the like.

The second current detector 9B detects the second output current output to the DC bus 2 by the second converter 5B. More specifically, the second current detector 9B detects the second output current flowing through the fourth electric wire L4 between the second converter 5B and the DC bus 2. Also, the second current detector 9B outputs a second current signal indicating the second output current to the second droop control section 10B. For example, a CT (Current Transformer), a current probe, or the like is used as the second current detector 9B. In addition, the second current detector 9B may be incorporated in the PLC, the second converter 5B, the second BMU 3B, or the like.

The control circuit 7 determines a first droop control value for the first droop control section 10A and a second droop control value for the second droop control section 10B based on the first physical quantity and the second physical quantity. More specifically, the control circuit 7 controls the signal indicating the first physical quantity (for example, the first signal indicating the first battery voltage and/or the third signal indicating the first estimated charge amount) and the second A signal indicating a physical quantity (for example, a second signal indicating a second battery voltage and/or a fourth signal indicating a second estimated charge amount) is received, and based on the first physical quantity and the second physical quantity, a second A first droop control value for the first droop control section 10A and a second droop control value for the second droop control section 10B are determined.

Further, the control circuit 7 outputs a first droop control command corresponding to the determined first droop control value to the first droop control section 10A, and outputs a second droop control command corresponding to the determined second droop control value. is output to the second droop control section 10B.

The first droop control section 10A adjusts the first voltage droop characteristic of the first converter 5A. More specifically, the first droop control section 10A adjusts the first voltage droop characteristic of the first conversion device 5A based on the first droop control value received from the control circuit 7 .

Further, the first droop control unit 10A receives a first current signal indicating the first output current from the first current detector 9A, and adjusts the first voltage droop characteristic based on the first droop control value and the first voltage droop characteristic. A first output voltage command value for the first converter 5A is determined based on the output current. Further, the first droop control unit 10A outputs a first control command corresponding to the determined first output voltage command value to the first converter 5A.

The second droop control section 10B adjusts the second voltage droop characteristic of the second converter 5B. More specifically, second droop control section 10B adjusts the second voltage droop characteristic of second conversion device 5B based on the second droop control value received from control circuit 7 .

Further, the second droop control unit 10B receives a second current signal indicating the second output current from the second current detector 9B, and adjusts the second voltage droop characteristic based on the second droop control value and the second voltage droop characteristic. A second output voltage command value for the second converter 5B is determined based on the output current. Furthermore, the second droop control unit 10B outputs a second control command corresponding to the determined second output voltage command value to the second converter 5B.

A part or the whole of the first droop control section 10A may be incorporated in the first conversion device 5A or the control circuit 7. Also, part or the whole of the second droop control section 10B may be incorporated in the second conversion device 5B or the control circuit 7 .

(Action: power supply to DC bus 2)
In the example shown in FIG. 10 , the control circuit 7 controls the first droop control unit 10A so that the power share ratio of the battery with the smaller remaining battery level of the first battery 40A and the second battery 40B is reduced. A first droop control value and a second droop control value for the second droop control section 10B are determined. Further, the control circuit 7 outputs a first droop control command corresponding to the determined first droop control value to the first droop control section 10A, and outputs a second droop control command corresponding to the determined second droop control value. is output to the second droop control section 10B.

The first droop control unit 10A is based on the first voltage droop characteristic adjusted based on the first droop control value and the first output current of the first converter 5A, the first output to the first converter 5A Determine the voltage command value. Further, the first droop control unit 10A outputs a first control command corresponding to the determined first output voltage command value to the first conversion device 5A.

The second droop control unit 10B is based on the second voltage droop characteristic adjusted based on the second droop control value and the second output current of the second converter 5B, the second output to the second converter 5B Determine the voltage command value. The second droop control unit 10B also outputs a second control command corresponding to the determined second output voltage command value to the second conversion device 5B.

As a result, the first output voltage of the first conversion device 5A and/or the second output voltage of the second conversion device 5B change, and the power share ratio of the battery with the smaller remaining battery capacity is reduced. In this way, the timing at which the remaining battery level becomes zero for each battery is prevented from greatly varying.

An example of voltage droop characteristic adjustment will be described with reference to FIGS. 11 and 12 .

In FIG. 11, the control circuit 7 outputs a first droop control command and a second droop control command for reducing the power share ratio of the first battery 40A or the second battery 40B, whichever has the smaller remaining battery capacity. An example of the relationship between the first output current of the first conversion device 5A and the first output voltage of the first conversion device 5A and the second output current of the second conversion device 5B and the second It is a graph which shows an example of the relationship between the 2nd output voltage of the converter 5B.

For simplicity, it is assumed that the voltage droop characteristic of the first converter 5A and the voltage droop characteristic of the second converter 5B are equal at time t1. Also, at time t1, the value of the first output voltage of the first converter 5A is equal to the value of the second output voltage of the second converter 5B, and the value of the first output voltage and the value of the second output voltage are Each has a voltage value F2. Also, at time t1, the value of the first output current of the first converter 5A is equal to the value of the second output current of the second converter 5B, and the value of the first output current and the value of the second output current are Each has a current value I1.

In the example shown in FIG. 11, the output power of the first converter 5A and the output power of the second converter 5B are both F2×I1. In the example shown in FIG. 11, it is assumed that the remaining battery charge of the first battery 40A is less than the remaining battery charge of the second battery 40B. In this case, as in the description of the first embodiment, if the output power of each conversion device is equal, the remaining battery capacity of the first battery 40A becomes zero first, and the first conversion device 5A stops. Such stoppage of the first conversion device 5A leads to the occurrence of excessive power in the second conversion device 5B or a reduction in the redundancy of the conversion device.

Therefore, according to the third embodiment, the control circuit 7 controls the first droop control unit so that the power share ratio of the first battery 40A or the second battery 40B, whichever has the smaller remaining battery capacity, is reduced. A first droop control value for 10A and a second droop control value for the second droop control section 10B are determined. Also, at least one of the first droop control section 10A receiving the first droop control value and the second droop control section 10B receiving the second droop control value changes the voltage droop characteristic of the corresponding converter ( In other words, it corrects the voltage droop characteristic of the corresponding converter).

More specific description will be given. In the example shown in FIG. 12, it is assumed that the first battery remaining amount of the first battery 40A is less than the second battery remaining amount of the second battery 40B. In this case, the first droop control unit 10A, which receives the first droop control command corresponding to the first droop control value, increases the first voltage droop characteristic of the first conversion device 5A (in other words, the first so that the ratio of the decrease (or increase) in the first output voltage of the first converter 5A to the increase (or decrease) in the first output current of the converter 5A is increased). 1 Correct the voltage droop characteristic (see arrow AR10).

In the example shown in FIG. 12, the first voltage droop characteristic of the first converter 5A is enhanced, so that the power share of the first battery 40A is reduced and the power share of the second battery 40B is increased. . More specifically, in the example shown in FIG. 12, the first voltage droop characteristic of the first conversion device 5A is enhanced, so that (1) the value of the first output voltage of the first conversion device 5A and the second The values of the second output voltage of the converter 5B are both changed from the voltage value F2 to the voltage value F3, and (2) the value of the first output current of the first converter 5A is changed from the current value I1 to the current value I2. (3) the value of the second output current of the second converter 5B is increased from the current value I1 to the current value I3; As a result, the output power of the first conversion device 5A changes to F3×I2, and the output power of the second conversion device 5B changes to F3×I3. The output power of the device 5A (F3×I2)<the output power of the second conversion device 5B (F3×I3). In addition, the sum of the output power of the first conversion device 5A and the output power of the second conversion device 5B "F3 × (I2 + I3)" is the first voltage droop characteristic of the first conversion device 5A before the output of both It is equal to the total power "2*F2*I1".

As described above, in the example illustrated in FIG. 12, the first voltage droop characteristic of the first converter 5A is enhanced, so that the power share of the first battery 40A is reduced, and the power share of the second battery 40B is increased. Alternatively or additionally, the second voltage droop characteristic of the second converter 5B is weakened, thereby reducing the power share of the first battery 40A and increasing the power share of the second battery 40B. may

Note that, in the third embodiment, the voltage droop characteristic of the first battery 40A or the second battery 40B with the smaller remaining battery level may be enhanced continuously or stepwise. . Alternatively or additionally, in the third embodiment, the voltage droop characteristic of whichever of the first battery 40A and the second battery 40B has the greater remaining battery capacity may be continuously weakened, It may be weakened step by step.

(Action: power reception from DC bus 2)
In the example illustrated in FIG. 13 , the control circuit 7 controls the first droop control unit 10A so that the power reception ratio of the battery with the greater remaining battery capacity of the first battery 40A and the second battery 40B is reduced. A first droop control value and a second droop control value for the second droop control section 10B are determined. Further, the control circuit 7 outputs a first droop control command corresponding to the determined first droop control value to the first droop control section 10A, and outputs a second droop control command corresponding to the determined second droop control value. is output to the second droop control section 10B.

The first droop control unit 10A is based on the first voltage droop characteristic adjusted based on the first droop control value and the first output current of the first converter 5A, the first output to the first converter 5A Determine the voltage command value. Further, the first droop control unit 10A outputs a first control command corresponding to the determined first output voltage command value to the first conversion device 5A.

The second droop control unit 10B is based on the second voltage droop characteristic adjusted based on the second droop control value and the second output current of the second converter 5B, the second output to the second converter 5B Determine the voltage command value. The second droop control unit 10B also outputs a second control command corresponding to the determined second output voltage command value to the second conversion device 5B.

As a result, the first output voltage of the first conversion device 5A and/or the second output voltage of the second conversion device 5B change, the power reception rate of the battery with the greater remaining battery capacity is reduced, and the remaining battery capacity The power receiving rate of the battery with the lower amount is increased. As a result, it is possible to prevent large variations in the timing of full charge for each battery.

(effect)
In the DC power supply system 100C according to the third embodiment, when the energy capacity or the characteristics of each power supply are different, the voltage droop characteristic of at least one converter is changed according to the remaining energy of each power supply. By doing so, the power share ratio of each power supply is adjusted. In this way, the remaining energy of one power supply is prevented or suppressed from reaching zero ahead of the remaining energy of the other power supply. As a result, operation of multiple converters is maintained, overpowering of a particular converter is prevented, and converter redundancy is maintained. Thus, the third embodiment provides a stable DC power supply system.

Further, in the DC power supply system 100C in the third embodiment, the voltage droop characteristic of at least one converter is changed according to the remaining energy of each power supply, and based on the voltage droop characteristic of the converter Both the output voltage is changed according to the output current. Therefore, both before changing the voltage droop characteristic of the at least one conversion device according to the remaining energy of each power supply and after changing the voltage droop characteristic of the at least one conversion device according to the remaining energy of each power supply, The occurrence of cross currents between a plurality of conversion devices is suppressed.

Further, in the third embodiment, when power is supplied from the charging power source 1B to the plurality of power sources (4A, 4B) through the DC bus 2, the energy remaining amount of each power source (in other words, each power source ), the voltage droop characteristic of at least one converter is changed to adjust the power receiving rate of each power supply. In this way, the energy storage of one power supply is prevented or suppressed from becoming FULL prior to the energy storage of the other power supply. As a result, operation of multiple converters is maintained, overpowering of a particular converter is prevented, and converter redundancy is maintained. Thus, the third embodiment provides a stable DC power supply system.

The present invention is not limited to the above embodiments or modifications, and it is obvious that each embodiment or modification can be modified or changed as appropriate within the scope of the technical idea of the present invention. In addition, various techniques used in each embodiment or each modified example are applicable to other embodiments or other modified examples as long as there is no technical contradiction. Furthermore, optional additional configurations in each embodiment or each modification can be omitted as appropriate.

1A... Load 1B... Charging power supply 2... DC bus 3A... First BMU 3B... Second BMU 4A... First power supply 4B... Second power supply 5A... First converter 5B... Second converter 6A First output section 6B Second output section 7 Control circuit 9A First current detector 9B Second current detector 10A First droop control section 10B second droop control unit 40A first battery 40B second battery 60A first voltage detector 60B second voltage detector 62A first estimated charge calculating unit 62B second Estimated charge amount calculator 91 Load 92 DC bus 93A First battery management unit 93B Second battery management unit 94A First battery group 94B Second battery group 95A 1st conversion device 95B 2nd conversion device 96A 1st current detector 96B 2nd current detector 97A 1st droop control unit 97B 2nd droop control unit , 100, 100A, 100B, 100C... DC power supply system, L1... 1st wire, L2... 2nd wire, L3... 3rd wire, L4... 4th wire

Claims (7)

a DC bus to which one or both of the load and the charging power supply are connected;
a first power supply that stores a first energy and outputs DC power from the first energy;
a second power supply that stores second energy and outputs DC power from the second energy;
a first conversion device disposed between the first power supply and the DC bus for stepping up or down a first power supply voltage on the first power supply side to a first output voltage on the DC bus side;
a second conversion device disposed between the second power supply and the DC bus for stepping up or stepping down a second power supply voltage on the side of the second power supply to a second output voltage on the side of the DC bus;
a first output unit that detects or calculates a first physical quantity that changes according to the remaining amount of the first energy stored in the first power supply and outputs a signal that indicates the first physical quantity;
a second output unit that detects or calculates a second physical quantity that changes according to the remaining amount of the second energy stored in the second power supply and outputs a signal that indicates the second physical quantity;
Based on the first physical quantity and the second physical quantity, a first output voltage command value for the first conversion device and a second output voltage command value for the second conversion device are determined, and the determined first A control circuit that outputs an output voltage command value to the first conversion device and outputs the determined second output voltage command value to the second conversion device,
The first conversion device steps up and down the first power supply voltage to the first output voltage based on the first output voltage command value and a first voltage droop characteristic,
The DC power supply system, wherein the second converter steps up and down the second power supply voltage to the second output voltage based on the second output voltage command value and a second voltage droop characteristic. The control circuit provides the first output voltage command value for the first conversion device, and The DC power supply system according to claim 1, wherein said second output voltage command value for said second converter is determined. the first power source is a rechargeable first battery;
the second power source is a rechargeable second battery;
the first output unit includes a first voltage detector that detects a first battery voltage that changes according to a first battery remaining amount of the first battery;
the second output unit includes a second voltage detector that detects a second battery voltage that changes according to a second remaining battery level of the second battery;
The control circuit calculates the first remaining battery capacity based on the first battery voltage and the discharge characteristics of the first battery, and calculates the remaining battery capacity based on the second battery voltage and the discharge characteristics of the second battery. calculating the second battery remaining amount;
The control circuit reduces a power share of the first battery and increases a power share of the second battery when the first battery remaining amount is less than the second battery remaining amount. The DC power supply system according to claim 1, wherein said first output voltage command value for said first converter and said second output voltage command value for said second converter are determined. the first power source is a rechargeable first battery;
the second power source is a rechargeable second battery;
The first output unit includes a first estimated charge amount calculation unit that calculates a first estimated charge amount of the first battery,
The second output unit includes a second estimated charge amount calculation unit that calculates a second estimated charge amount of the second battery,
The control circuit reduces the power share of the first battery and increases the power share of the second battery when the first estimated charge amount is less than the second estimated charge amount. , the first output voltage command value for the first converter, and the second output voltage command value for the second converter. The control circuit controls the first output voltage command value for the first conversion device, and The DC power supply system according to claim 1, wherein said second output voltage command value for said second converter is determined. a DC bus to which one or both of the load and the charging power supply are connected;
a first power supply that stores a first energy and outputs DC power from the first energy;
a second power supply that stores second energy and outputs DC power from the second energy;
a first conversion device disposed between the first power supply and the DC bus for stepping up or down a first power supply voltage on the first power supply side to a first output voltage on the DC bus side;
a second conversion device disposed between the second power supply and the DC bus for stepping up or stepping down a second power supply voltage on the side of the second power supply to a second output voltage on the side of the DC bus;
a first output unit that detects or calculates a first physical quantity that changes according to the remaining amount of the first energy stored in the first power supply and outputs a signal that indicates the first physical quantity;
a second output unit that detects or calculates a second physical quantity that changes according to the remaining amount of the second energy stored in the second power supply and outputs a signal that indicates the second physical quantity;
a first current detector that detects a first output current of the first conversion device and outputs a first current signal indicative of the first output current to a first droop control unit;
a second current detector that detects a second output current of the second conversion device and outputs a second current signal indicative of the second output current to a second droop control unit;
determining a first droop control value for the first droop control unit and a second droop control value for the second droop control unit based on the first physical quantity and the second physical quantity; a control circuit that outputs a droop control value to the first droop control unit and outputs the determined second droop control value to the second droop control unit;
the first droop control for adjusting a first voltage droop characteristic of the first conversion device based on the first droop control value received from the control circuit;
said second droop control for adjusting a second voltage droop characteristic of said second converter based on said second droop control value received from said control circuit;
The first droop control unit determines a first output voltage command value for the first conversion device based on the adjusted first voltage droop characteristic and the first output current, and determines the determined first 1 output voltage command value to the first conversion device,
The second droop control unit determines a second output voltage command value for the second conversion device based on the adjusted second voltage droop characteristic and the second output current, and determines the determined second A DC power supply system that outputs two output voltage command values to the second converter. The control circuit controls the first droop control value for the first droop control unit, and 7. The DC power supply system of claim 6, wherein said second droop control value for said second droop control is determined.

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