DC power supply device

Abstract

To provide a DC power supply device that enables efficient power supply while avoiding over-specification of power conversion devices. [Solution] The DC power supply device 1 includes a power converter 10 that converts AC power to DC power and supplies DC power to a plurality of power supply devices 2. The power converter 10 and the power supply devices 2 are configured as separate units. The DC power supply device 1 has an output voltage control unit 11 that controls the output voltage based on at least one of the input state or output state of the power converter 10.

Description

[Technical Field]

[0001] This disclosure relates to a DC power supply device, and more particularly to output control of a DC power supply device. [Background technology]

[0002] Conventionally, DC power supply devices capable of simultaneously supplying power to multiple power receiving devices have become widespread. For example, Patent Document 1 discloses a DC power supply device configured to simultaneously supply power to multiple power receiving devices, which transmits a list of available voltage and current combinations to the power receiving devices in the order they are connected, and supplies power according to the combination selected by the power receiving devices. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2022-044165 [Overview of the project] [Problems that the invention aims to solve]

[0004] Incidentally, when a DC power supply device is configured to supply power to multiple power receiving devices via multiple output terminals, if the sum of the output power of the multiple power receiving devices exceeds the maximum output power of the power converter (AC / DC converter), the AC / DC converter's overcurrent protection and overpower protection will activate, causing a problem where the power supply is stopped for a certain period of time. As a result, the power supply to all power receiving devices is stopped, which impairs efficient power supply. On the other hand, if the number of output terminals is reduced so as not to exceed the maximum output power of the AC / DC converter, the AC / DC converter becomes over-specified. Patent Document 1 describes the effect that the maximum power that can be supplied by the power supply device or power converter can be distributed efficiently and without waste, adapted to the power required by the power receiving devices. However, the conventional power converter disclosed in Patent Document 1 does not disclose anything about avoiding the power converter becoming over-specified or suppressing the power supply stoppage of the power converter. [Means for solving the problem]

[0005] The DC power supply device according to this disclosure is a DC power supply device that includes a power converter that converts AC power to DC power and supplies DC power to a plurality of power supply devices, wherein the power converter and the power supply devices are configured as separate units and each has an output voltage control unit that controls the output voltage based on at least one of the input state or output state of the power converter. [Effects of the Invention]

[0006] According to the DC power supply device described herein, efficient power supply is possible while avoiding over-specification of the power converter. [Brief explanation of the drawing]

[0007] [Figure 1] This is a block diagram showing the power supply system according to this embodiment. [Figure 2] This flowchart shows the output voltage control of the DC power supply device according to this embodiment. [Figure 3]This is a diagram illustrating the relationship between the output voltage and output power of the DC power supply device according to the present embodiment. [Figure 4] This is a diagram showing the relationship between output voltage, output power and time. [Figure 5] This is a flowchart showing output control of the power supply device according to the present embodiment. [Figure 6] This is a diagram showing the relationship between the maximum supply power and the input voltage of the power supply device according to the present embodiment. [Figure 7] This is a diagram showing a specific example of output control of the DC power supply device. [Figure 8] This is a diagram showing a specific example of output control of the DC power supply device. [Figure 9] This is a diagram showing a specific example of output control of the DC power supply device. [Figure 10] This is a diagram showing a first modified example of the DC power supply device. [Figure 11] This is a diagram showing a second modified example of the DC power supply device. [Figure 12] This is a diagram showing a third modified example of the DC power supply device. [Figure 13] This is a block diagram showing the DC power supply device in detail. [Figure 14] This is a diagram illustrating another example of the relationship between the output voltage and output power of the AC / DC converter. [Figure 15] This is a diagram showing a bus wiring scheme. [Figure 16] This is a diagram showing a daisy chain wiring scheme. [Figure 17] This is a diagram showing a star wiring scheme. [Figure 18] This is a diagram showing a specific example of maximum supply power control by a power budget management scheme. [Figure 19] This is a diagram showing a specific example of maximum supply power control by a control scheme based on a port priority scheme. [Figure 20] This is a diagram showing a specific example of maximum supply power control by a total power consumption limiting scheme. [Figure 21] This is a diagram showing a specific example of maximum supply power control by a power adjustment scheme based on the number of connections. [Figure 22] This is a diagram showing a specific example of maximum power supply control by a rotation method. [Figure 23] This is a diagram showing an example of address setting in the rotation method. [Figure 24] This is a block diagram showing another example of the power supply system. [Description of Embodiments for Carrying Out the Invention]

[0008] Hereinafter, embodiments of the power supply device and the power supply system according to the present disclosure will be described in detail with reference to the drawings. The embodiments described below are merely examples, and the present disclosure is not limited to the following embodiments. Further, configurations obtained by selectively combining a plurality of embodiments and modified examples described below are included in the present disclosure.

[0009] The configuration of the power supply system 100 according to the present embodiment will be described in detail using FIG. 1. Specifically, the configurations of the DC power supply device 1 and the power supply device 2 that constitute the power supply system 100 will be described in detail. FIG. 1 is a block diagram showing the power supply system 100 according to the present embodiment. In FIG. 1, solid lines indicate power paths, and dashed-dotted lines indicate information paths. The information paths may be configured by wired communication or may be formed by wireless communication.

[0010] As shown in FIG. 1, the DC power supply device 1 includes a power converter 10 that converts AC power into DC power, and supplies DC power to a plurality of power supply devices 2. Further, the power converter 10 and the power supply device 2 are configured as separate bodies. The power converter 10 has an output voltage control unit 11 that controls the output voltage based on at least one of the input state and the output state of the power converter 10. According to this, since the output voltage can be lowered before the output power of the power converter 10 exceeds the maximum output power, it is possible to prevent the interruption of power supply due to overcurrent protection or overpower protection of the power converter 10. In addition, since the degree of freedom in the number of installed power supply devices 2 is high, a plurality of power supply devices 2 can be connected to the power converter 10, and the power converter 10 can be prevented from being overspecified.

[0011] The power supply device 2 receives input DC power from the DC power supply device 1 and outputs DC power to the power receiving device 30. The DC power supply device 1 and the power supply device 2 are configured as separate units. The power supply device 2 also has a DC voltage converter 20 that converts the input voltage of the input DC power to a predetermined output voltage and an input voltage measuring unit 22 that measures the input voltage. Furthermore, the power supply device 2 has an output power control unit 21 that sets the maximum supply power that the DC voltage converter 20 can supply based on the input voltage and controls the output power of the DC voltage converter 20 based on the result of negotiations with the power receiving device 30 using the maximum supply power. In addition, if the input voltage fluctuates, the output power control unit 21 sets the maximum supply power based on the fluctuating input voltage and negotiates with the power receiving device 30. With the above power supply device 2, since no communication takes place between the AC / DC converter 10 and the DC / DC converter 20, the power supply device 2 and the power supply system 100 can be simplified and costs reduced.

[0012] The power converter 10 is a device equipped with a power conversion circuit that converts AC power to DC power. In this embodiment, the power converter 10 is an AC / DC converter 10, as shown in Figure 1. The following explanation will be based on the example of the case where the power converter 10 is an AC / DC converter 10. The AC / DC converter 10 is connected to one end of an AC power cable 12 and is connected to a power source via the AC power cable 12. For example, AC power is supplied to the AC / DC converter 10 when the AC power cable 12 is connected to a commercial power outlet installed on a wall or the like. The AC / DC converter 10 converts, for example, AC 100-240V AC power to DC 24V DC power. As will be described in more detail later, the AC / DC converter 10 adjusts the output voltage according to instructions from the output voltage control unit 11.

[0013] The DC power supply device 1 is equipped with a safety mechanism that, if the output power exceeds a preset maximum output power, activates overcurrent protection or overpower protection, and stops the power supply for a certain period of time. When the overcurrent protection of the DC power supply device 1 is activated, the power supply is stopped, and the output from the power supply device 2 is also stopped.

[0014] As described above, the DC power supply device 1 has an output voltage control unit 11 that controls the output voltage based on at least one of the input state or output state of the AC / DC converter 10. Here, the input state of the AC / DC converter 10 is at least one of the input power and input current input to the AC / DC converter 10, and the output state is at least one of the output current and output power output from the AC / DC converter 10. Note that the output power of the AC / DC converter 10 is calculated regardless of which of the above is selected as the input state. In the case of input power or input current, the output power is calculated based on the losses of the AC / DC converter 10 itself. In the case of output current, the output power is calculated in relation to the output voltage. The following explanation will use the case in which the output voltage control unit 11 controls the output voltage based on the output power of the AC / DC converter 10 as an example. The output power is measured by the output power measuring unit 14.

[0015] The output power measurement unit 14 is located on the output side of the AC / DC converter 10 and is connected to the DC power cable 13 that supplies DC power to the power supply device 2. It measures the power output from the AC / DC converter 10. In this embodiment, the output power measurement unit 14 is located within the DC power supply device 1. That is, in this embodiment, the output power measurement unit 14 is located within the same housing as the AC / DC converter 10 and the output voltage control unit 11.

[0016] As described above, the DC power supply device 1 has an overcurrent protection function and an overpower protection function. More specifically, the AC / DC converter 10 of the DC power supply device 1 stops outputting when the output power of the AC / DC converter 10 exceeds a preset maximum output power. More specifically, when the output power measured by the output power measurement unit 14 exceeds a preset maximum output power, the output voltage control unit 11 sets the output voltage to 0V and stops outputting power from the AC / DC converter 10. This prevents damage to the AC / DC converter 10 due to overcurrent and overpower.

[0017] The output voltage control unit 11 lowers the output voltage of the AC / DC converter 10 when at least one of the input state or output state exceeds a predetermined threshold, and raises the output voltage of the AC / DC converter 10 when it falls below the threshold. Specifically, the output voltage control unit 11 controls the output voltage of the AC / DC converter 10 to lower it when the output power measured by the output power measurement unit 14 exceeds a predetermined threshold. In addition, the output voltage control unit 11 controls the output voltage of the AC / DC converter 10 to raise it when the output power measured by the output power measurement unit 14 falls below a predetermined threshold. This allows the output voltage of the AC / DC converter 10 to be lowered before the output power exceeds the maximum output power. Therefore, the output power output from the AC / DC converter 10 decreases, preventing the output power of the AC / DC converter 10 from exceeding the maximum output power. As a result, it is possible to prevent the power supply from being stopped due to overcurrent protection or overpower protection of the AC / DC converter 10. This suppresses the interruption of the power supply and enables efficient power supply.

[0018] Furthermore, the DC power supply device 1 controls the output voltage so as not to exceed the maximum output power of the AC / DC converter 10, regardless of the number of connected power supply devices 2, thus offering greater flexibility in the number of connected power supply devices 2. As a result, even if the sum of the maximum power supplied by multiple power supply devices 2 exceeds the maximum output power of the AC / DC converter 10, the AC / DC converter 10 will operate normally. Therefore, since it is not necessary to make the sum of the maximum power supplied by the power supply devices 2 less than the maximum output power of the AC / DC converter 10, the AC / DC converter 10 can be avoided as being over-specified.

[0019] The output voltage control unit 11 preferably controls the output voltage of the AC / DC converter 10 by switching between a plurality of preset output voltages. In other words, the output voltage control unit 11 preferably discretely varies the output voltage of the AC / DC converter 10. This allows for hysteresis characteristics compared to continuously varying the output voltage, thus preventing chattering where the state changes instantaneously. The following explanation will illustrate the case where the output voltage control unit 11 switches between a plurality of preset output voltages.

[0020] The AC / DC converter 10 is connected to the DC voltage converter 20 of the power supply device 2, which is connected to the power receiving device 30, via a DC power cable 13. This allows the DC voltage converter 20 of the power supply device 2 to output DC power to the power receiving device 30. The number of power supply devices 2 connected to the AC / DC converter 10 is not particularly limited, as long as there are multiple devices. As shown in Figure 1, for example, there are two power supply devices 2 connected to the AC / DC converter 10.

[0021] As described above, the power supply device 2 has a DC voltage converter 20 that adjusts the voltage of the input DC power. In this embodiment, the DC voltage converter 20 is a DC / DC converter 20, as shown in Figure 1. The following explanation will be based on an example where the DC voltage converter 20 is a DC / DC converter 20.

[0022] The power supply device 2 has an input voltage measuring unit 22 that measures the voltage input to the DC / DC converter 20. The power supply device 2 also has an output power control unit 21 that controls the output power of the DC / DC converter 20 based on the input voltage measured by the input voltage measuring unit 22.

[0023] The input voltage measurement unit 22 is located on the input side of the DC / DC converter 20 and is connected to the DC power cable 13 that supplies DC power to the DC / DC converter 20. It measures the input voltage of the DC / DC converter 20. In this embodiment, the input voltage measurement unit 22 is located within the power supply device 2. That is, in this embodiment, the input voltage measurement unit 22 is located within the same housing as the DC / DC converter 20 and the output power control unit 21.

[0024] The power supply device 2 is directly connected to the power receiving device 30 and supplies power to the power receiving device 30. The power supply device 2 and the power receiving device 30 are connected by a power supply cable 31. The power supply device 2 and the power receiving device 30 may also be further connected via a communication line 32. In this case, the power supply cable 31 is connected to the DC / DC converter 20, and the communication line 32 is connected to the output power control unit 21. The power supply cable 31 and the communication line 32 may be physically separate wiring or may be contained within a single cable. The power receiving device 30 may be, for example, an information terminal such as a smartphone, tablet terminal, or personal computer, or a lighting device such as a ceiling light.

[0025] The power supply device 2 negotiates with the power receiving device 30 using the communication line 32. Specifically, the output power control unit 21 of the power supply device sets the maximum power that the DC / DC converter 20 can supply based on the input voltage, and negotiates with the power receiving device 30 using this maximum power. Specifically, the power supply device 2 creates a list containing PDOs (Power Data Objects), which are combinations of voltage and current that the power supply device 2 can supply to the power receiving device 30, and transmits it to the power receiving device 30. The PDOs contain combinations of current and voltage that can output the maximum power that the DC / DC converter 20 can supply.

[0026] The power receiving device 30 compares the received list of voltage and current combinations (PDOs) with the model information and specifications of the power receiving device 30, and selects a combination from the presented PDOs that is suitable for the power receiving device 30. Here, the combination selected by the power receiving device 30 is, for example, the combination that can obtain the maximum power among the suitable PDOs. The power receiving device 30 transmits the selected PDO to the power supply device 2 via the communication line 32 and requests power from the power supply device 2 according to the PDO. In this way, negotiation between the power supply device 2 and the power receiving device 30 is completed. The output power control unit 21 controls the DC / DC converter 20 to output power according to the PDO selected by the power receiving device 30 from the DC / DC converter 20. Furthermore, as will be described in more detail later, if the output voltage of the AC / DC converter 10, i.e., the input voltage of the DC / DC converter 20, fluctuates, the output power control unit 21 sets the maximum supply power based on the fluctuating input voltage and negotiates with the power receiving device 30.

[0027] With the power supply device 2 having the output power control unit 21 described above, even without communication between the power supply device 2 and the DC power supply device 1, the output power of the power supply device 2 can be controlled when the output voltage of the DC power supply device 1, i.e., the input voltage to the power supply device 2, fluctuates, thereby preventing the output power of the DC power supply device 1 from exceeding the maximum output power. This prevents the power supply from being stopped from the DC power supply device 1 to the power receiving device 30. Furthermore, since there is no need for communication between the DC power supply device 1 and the power supply device 2, wiring for communication can be omitted. As a result, the power supply device 2 and the power supply system 100 can be simplified and costs reduced.

[0028] As described above, the power supply device 2 includes a DC / DC converter 20. The DC / DC converter 20 converts the input voltage into a predetermined output voltage. In other words, the DC / DC converter 20 converts the voltage of the DC power obtained via the DC power cable 13 into DC power within a voltage range in which the power supply device 2 can operate. The DC / DC converter 20 may be, for example, a step-down converter that converts the DC24V output by the AC / DC converter 10 to DC5V~20V. Alternatively, the DC / DC converter 20 may be a boost converter or a step-up / step-down converter that increases the voltage. The voltage conversion by the DC / DC converter 20 is appropriately set depending on the type of power supply device 2 and the type of power receiving device 30, etc.

[0029] The output power control unit 21 controls the output power of the DC / DC converter 20 based on the power request from the power receiving device 30. More specifically, it causes the DC / DC converter 20 to output power according to the PDO selected by the power receiving device 30 during negotiation. That is, the output power control unit 21 creates and transmits a PDO containing information on the maximum supply power based on information from the input voltage measurement unit 22, and controls the output power output from the DC / DC converter 20 based on the information regarding the PDO selection from the power receiving device 30.

[0030] The output power control unit 21 preferably controls the maximum power supplied by the DC / DC converter 20 based on the output voltage of the AC / DC converter 10. In other words, the output power control unit 21 preferably controls the maximum power supplied by the DC / DC converter 20 based on the input voltage of the DC / DC converter 20. More specifically, the output power control unit 21 lowers the maximum power supplied by the DC / DC converter 20 when the input voltage falls below a predetermined threshold, and increases the maximum power supplied by the DC / DC converter 20 when the input voltage rises above the threshold. More specifically, the output power control unit 21 lowers the maximum power that can be supplied by lowering the voltage or current of the PDO when the input voltage falls below a predetermined threshold. Also, the output power control unit 21 raises the maximum power that can be supplied by raising the voltage or current of the PDO when the input voltage rises above a predetermined threshold. This allows the power requested by the power receiving device 30 to be controlled by setting an upper limit on the power that can be supplied. As a result, the output power output from the DC / DC converter 20 can be controlled.

[0031] The power supply device 2 preferably has a temperature measuring unit 23 for measuring the temperature inside the power supply device 2. In this case, the output power control unit 21 preferably controls the output power of the DC / DC converter 20 based on the temperature measured by the temperature measuring unit 23. For example, the output power control unit 21 may reduce the output power of the DC / DC converter 20 when the temperature measured by the temperature measuring unit 23 exceeds a predetermined temperature. Alternatively, the output power control unit 21 may stop outputting power from the DC / DC converter 20 when the temperature measured by the temperature measuring unit 23 exceeds an acceptable temperature. This can suppress failure of the power supply device 2 due to temperature rise.

[0032] The AC / DC converter 10 and the power supply device 2 are configured as separate units. That is, the DC power supply device 1, which has the AC / DC converter 10, and the power supply device 2, which has the DC / DC converter 20, are configured as separate units. In other words, the AC / DC converter 10 and the DC / DC converter 20 are housed in separate enclosures. In this embodiment, the AC / DC converter 10 is housed in the DC power supply device 1, and the DC / DC converter 20 is housed in the power supply device 2. This makes it possible to miniaturize the power supply device 2 compared to the case where the DC / DC converter 20 and the AC / DC converter 10 are housed in the same enclosure. Furthermore, in the power supply device 2 where the DC / DC converter 20 is housed, it is no longer necessary to consider the problem of heat generation due to the operation of the AC / DC converter 10. As a result, it is possible to realize a power supply device 2 that is smaller and has a higher output than conventional devices.

[0033] The operation of the DC power supply device 1 will be described in detail with further reference to Figures 2 and 3. Figure 2 is a flowchart showing the output voltage control of the DC power supply device 1. Figure 3 is a diagram illustrating the relationship between the output voltage and output power of the AC / DC converter 10. Below, the explanation will be given using the example of a case where five thresholds are provided, as shown in Figure 3. The first threshold P1 and the third threshold P3 are thresholds that increase the output voltage. The second threshold P2, the fourth threshold P4, and the fifth threshold P5 are thresholds that decrease the output voltage.

[0034] First, the AC / DC converter 10 operates to output a first output voltage V1 (step S1). Next, the output power measurement unit 14 measures the output power P of the AC / DC converter 10 at the first output voltage V1 (step S2). The output voltage control unit 11 also determines whether the output power P is equal to or greater than the second threshold P2 (step S3). If the output power P is less than the second threshold P2 (NO in step S3), the process returns to step S1, and the AC / DC converter 10 continues to operate to output the first output voltage V1. On the other hand, if the output power P is equal to or greater than the second threshold P2 (YES in step S3), the output voltage control unit 11 switches the first output voltage V1 of the AC / DC converter 10 to the second output voltage V2 (step S4).

[0035] Next, the output power measurement unit 14 measures the output power P of the AC / DC converter 10 at the second output voltage V2 (step S5). The output voltage control unit 11 also determines whether the output power P is less than or equal to the first threshold P1 (step S6). If the output power P is less than or equal to the first threshold P1 (YES in step S6), the output voltage control unit 11 switches the second output voltage V2 of the AC / DC converter 10 to the first output voltage V1. That is, the process returns to step S1. On the other hand, if the output power P exceeds the first threshold P1 (NO in step S6), the unit determines whether the output power P is greater than or equal to the fourth threshold P4 (step S7).

[0036] If the output power P is less than the fourth threshold P4 (NO in step S7), the process returns to step S4, and the AC / DC converter 10 continues to operate to output the second output voltage V2. On the other hand, if the output power P is greater than or equal to the fourth threshold P4 (YES in step S7), the output voltage control unit 11 switches the second output voltage V2 of the AC / DC converter 10 to the third output voltage V3 (step S8).

[0037] Next, the output power measurement unit 14 measures the output power P of the AC / DC converter 10 at the third output voltage V3 (step S9). The output voltage control unit 11 also determines whether the output power P is less than or equal to the third threshold P3 (step S10). If the output power P is less than or equal to the third threshold P3 (YES in step S10), the output voltage control unit 11 switches the third output voltage V3 of the AC / DC converter 10 to the second output voltage V2. That is, the process returns to step S4. On the other hand, if the output power P exceeds the third threshold P3 (NO in step S10), the unit determines whether the output power P is greater than or equal to the fifth threshold P5 (step S11).

[0038] If the output power P is less than the fifth threshold P5 (NO in step S11), the process returns to step S8, and the AC / DC converter 10 continues to operate to output the third output voltage V3. On the other hand, if the output power P is greater than or equal to the fifth threshold P5 (YES in step S11), the output voltage control unit 11 stops the output of the AC / DC converter 10 (step S12).

[0039] The number and value of the thresholds are not particularly limited, but it is preferable to have multiple thresholds set at equal intervals, for example, as shown in Figure 3. The threshold for the output voltage may be set by a switch (not shown) provided on the DC power supply device 1, or by a higher-level control device (not shown) configured to control the DC power supply device 1.

[0040] The output voltage threshold of the AC / DC converter 10 preferably has hysteresis, as shown in Figure 3. Specifically, it is configured so that the output voltage does not follow the same path when decreasing and increasing. For example, when the output power exceeds the second threshold P2, the output voltage decreases and switches from the first output voltage V1 to the second output voltage V2. Also, the output voltage increases and switches from the second output voltage V2 to the first output voltage V1, provided that the output power falls below the first threshold P1. Therefore, by setting the second threshold P2, which decreases the output voltage, and the first threshold P1, which increases the output voltage, to different values, the output voltage does not follow the same path when decreasing and increasing. As described above, by setting two types of thresholds and setting the two types of thresholds with an interval between them, the transition of the output voltage has hysteresis. The interval between the two types of thresholds is not particularly limited, but may be set based on the rated power of the AC / DC converter 10 to which it is applied. In the example shown in Figure 3, the interval is set at 50W.

[0041] If the threshold for decreasing the output voltage and the threshold for increasing the output voltage are the same, chattering occurs, where the output voltage frequently decreases and increases when the output power slightly increases or decreases near the threshold. As a result, stable control becomes difficult. Therefore, as described above, by dividing the threshold into two types and setting a gap between the two thresholds, the occurrence of chattering can be suppressed and stable control can be achieved.

[0042] The output voltage control unit 11 may gradually increase the output voltage when recovering from a reduced output voltage state. That is, the output voltage control unit 11 may increase the output voltage in stages when increasing the output voltage. For example, as shown in Figure 3, when the AC / DC converter 10 is operating at the third output voltage V3, the output voltage control unit 11 may switch from the third output voltage V3 to the second output voltage V2 when the output power falls below the first threshold P1. Here, if the output power is also below the first threshold P1 at the second output voltage V2, the output voltage control unit 11 may switch from the second output voltage V2 to the first output voltage V1. This allows for a gradual increase in output power while suppressing a rapid increase in power caused by a sudden increase in voltage. By gradually increasing the output power, it is possible to suppress the output power from immediately exceeding the threshold and to achieve stable control.

[0043] The output voltage control unit 11 may return the output voltage to its maximum output voltage before it was reduced when recovering from a reduced output voltage state. For example, as shown in Figure 3, when the AC / DC converter 10 is operating at the third output voltage V3, the output voltage control unit 11 may switch from the third output voltage V3 to the first output voltage V1 when the output power falls below the first threshold P1. In this case, the output power is increased to the maximum output voltage only when the output power falls below a predetermined threshold, so that the maximum output power can be supplied immediately when the condition is met. The output voltage control unit 11 restores the output voltage, for example, when some of the connections among the multiple power receiving devices 30 connected to the multiple power supply devices 2 are disconnected. At this time, the maximum output power can be supplied immediately to the power supply devices 2 to which the power receiving devices 30 are still connected, thereby increasing the power supply efficiency to the power receiving devices 30.

[0044] In the DC power supply device 1, as described above, the output of the AC / DC converter 10 is stopped if the output power exceeds a preset maximum output power. The DC power supply device 1 preferably resumes outputting the output voltage after a predetermined time has elapsed since the output voltage was stopped, or after the DC power supply device 1 has been restarted. Here, the predetermined time is not particularly limited, but for example, it is 30 seconds. Restarting the DC power supply device 1 means, for example, disconnecting and reconnecting the connection between the power supply and the DC power supply device 1. By resuming outputting the output voltage under the above conditions, power supply can be resumed even if the power supply has been stopped.

[0045] It is preferable that the output voltage control unit 11 refrains from making a determination for issuing the next control instruction for a predetermined time after sending a control signal to the AC / DC converter 10 to instruct it to change the output voltage. That is, it is preferable that the output voltage control unit 11 refrains from making a determination regarding the necessity of changing the output voltage for a predetermined time after instructing the AC / DC converter 10 to change the output voltage. For example, as shown in Figure 4, if an output voltage change instruction is issued at time t1, the system is configured not to make a determination for issuing a new output voltage change instruction for a predetermined time t. Here, it is preferable that the predetermined time t is longer than the time it takes for the power supply device 2 to negotiate with the power receiving device 30. The predetermined time t is, for example, 3 seconds.

[0046] Specifically, in the example shown in Figure 4, the output power P becomes greater than or equal to the second threshold P2 at time t1. At this time, the output voltage control unit 11 switches the output voltage of the AC / DC converter 10 from the first output voltage V1 to the second output voltage V2. As a result, negotiation using a newly set PDO takes place between the power supply device 2 and the power receiving device 30. During negotiation, the output power is 0W, so the output power temporarily becomes less than or equal to the first threshold P1. If a decision regarding the threshold is made between time t2 and time t3 when the output power is newly determined, in the example shown in Figure 4, the second output voltage V2 will be returned to the first output voltage V1. However, returning to the first output voltage V1 may cause the output power to exceed the second threshold P2 again, potentially causing chattering. Therefore, the output voltage control unit 11 waits for a predetermined time t, so that the output voltage is not changed until the output power stabilizes after the negotiation is complete. As a result, stable control is possible.

[0047] Note that the operation of the DC power supply device 1 is not limited to the above example. Below, another example of the operation of the DC power supply device 1 will be described using Figures 13 and 14. Figure 13 corresponds to Figure 1 and is a block diagram showing the DC power supply device 1 in detail. Figure 14 corresponds to Figure 3 and illustrates another example of the relationship between the output voltage and output power of the AC / DC converter 10.

[0048] The output power measuring unit 14 of the DC power supply device 1 may consist of an output current measuring unit 14a and an output voltage measuring unit 14b, as shown in Figure 13. Here, the output current measuring unit 14a is connected in series with the AC / DC converter 10, and the output voltage measuring unit 14b is connected in parallel. The output power measuring unit 14 may use the product of the output current measured by the output current measuring unit 14a and the output voltage measured by the output voltage measuring unit 14b as the output power.

[0049] The output voltage control unit 11 of the DC power supply device 1 may continuously vary the output voltage based on at least one of the input state or output state of the AC / DC converter 10. For example, as shown in Figure 14, the output voltage control unit 11 continuously decreases or increases the output voltage in response to fluctuations in output power.

[0050] The output voltage control unit 11 continuously decreases the output voltage in response to an increase in output power, for example, as shown in Figure 14. Furthermore, when the output power exceeds a first predetermined value, the output voltage control unit 11 sets the output voltage to 0V and stops the output. The output voltage control unit 11 may also restart the output after stopping the output if the output power falls below a second predetermined value. The output voltage control unit 11 also continuously increases the output voltage in response to a decrease in output power. Here, the first predetermined value and the second predetermined value may be different.

[0051] A virtual resistance may be set in advance in the output voltage control unit 11. This virtual resistance is set in advance as a set value in the output voltage control unit 11 and is used to control the output voltage. Specifically, the virtual resistance is stored in the memory unit of the output voltage control unit 11. In this case, the calculation unit of the output voltage control unit 11 calculates the output voltage based on the output current and the virtual resistance, and the output voltage control unit 11 controls the AC / DC converter 10 to output the calculated output voltage. Here, the calculation unit of the output voltage control unit may calculate the output voltage using the following equation 1.

[0052]

number

[0053] Here, V out V indicates the output voltage. ref This indicates the reference voltage, K droop represents virtual resistance, I out This indicates the measured output current, I ref V indicates the reference current. V is the reference voltage. ref and reference current I refis a preset value and is stored in the storage unit of the output voltage control unit 11. In the example shown in FIG. 14, the reference voltage V ref is set to 24.0V, and the reference current I ref is set to about 4A. Since the output power can be calculated by the product of the output voltage V out and the output current I out , in Equation 1, the variation of the output current I out indicates the variation of the output power.

[0054] As shown in FIG. 14, the output voltage control unit 11 may form a flat region where the output voltage is not varied until the value of the output power (output current I out ) exceeds a predetermined value. In the example shown in FIG. 14, a flat region where the output voltage does not vary is formed in the region where the output power is 0W or more and 100W or less. According to the flat region, the output voltage is not limited within the region, so the power supply device 2 can supply power at the highest efficiency. Further, in the example shown in FIG. 14, when the output power exceeds 100W, the output voltage continuously decreases as the output power increases. Further, when the output power exceeds a first predetermined value (for example, 300W), the output voltage is set to 0V to stop the output.

[0055] The output voltage control unit 11 may restart voltage output on the condition that the output power falls below a second predetermined value after the output is stopped. After restarting the voltage output, for example, it operates at the third output voltage V3, and continuously increases the output voltage as the output power decreases. Further, the output voltage control unit 11 may form a flat region where the output voltage does not vary when the value of the output power (output current I out ) falls below a predetermined value (for example, 100W).

[0056] The virtual resistance is set appropriately based on, for example, the number of power supply devices 2 connected to the DC power supply device 1, the maximum output power of the DC power supply device 1, etc. Furthermore, it is preferable that the virtual resistance set in the output voltage control unit 11 fluctuates according to the state of the DC power supply device 1, such as the temperature of the DC power supply device 1 and the connection status of the power receiving devices in the power supply devices 2. By fluctuating the virtual resistance according to the temperature or connection status, the output of the DC power supply device 1 can be optimized. For example, if the number of connected power receiving devices is small, the value of the virtual resistance may be reduced. When the number of connected power receiving devices is small, the total output power is small, so there is a low possibility that the total output power will exceed the first predetermined value and the output will stop. Therefore, by reducing the value of the virtual resistance, the decrease in output voltage can be slowed down, and even if the total output power is large, a relatively high output voltage can be maintained, enabling efficient power supply. Although the above has described output voltage control by calculation using virtual resistance, the above control can also be performed by analog circuits.

[0057] The control of the output power of the power supply device 2 will be explained in detail with reference to Figures 5 and 6. Figure 5 is a flowchart illustrating the control of the output power of the power supply device 2. Figure 6 is a diagram illustrating the relationship between the input voltage of the power supply device 2 and the maximum supply power. In the following explanation, we will use the case where four thresholds are provided as shown in Figure 6 as an example. The sixth threshold Va and the eighth threshold Vc are thresholds that increase the maximum supply power. The seventh threshold Vb and the ninth threshold Vd are thresholds that decrease the maximum supply power.

[0058] First, the power supply device 2 operates at the first maximum supply power Px (step S21). That is, the output power control unit 21 controls the output power based on the result of negotiations using the first maximum supply power Px, which is set as the maximum supply power. Next, the input voltage measurement unit 22 measures the input voltage Vin of the DC / DC converter 20 (step S22). The output power control unit 21 also determines whether the input voltage Vin is less than or equal to the seventh threshold Vb (step S23). If the input voltage Vin exceeds the seventh threshold Vb (NO in step S23), the process returns to step S21, and the power supply device 2 continues to operate at the first maximum supply power Px. On the other hand, if the input voltage Vin is less than or equal to the seventh threshold Vb (YES in step S23), the output power control unit 21 changes the first maximum supply power Px of the DC / DC converter 20 to the second maximum supply power Py and negotiates with the power receiving device 30 again using the second maximum supply power Py (step S24). In other words, power supply device 2 operates at the second maximum supply power Py.

[0059] Next, the input voltage measurement unit 22 measures the input voltage Vin at the second maximum supply power Py (step S25). The output power control unit 21 also determines whether the input voltage Vin is equal to or greater than the sixth threshold Va (step S26). If the input voltage Vin is equal to or greater than the sixth threshold Va (YES in step S26), the process returns to step S21 and the system operates at the first maximum supply power Px. On the other hand, if the input voltage Vin is less than the sixth threshold Va (NO in step S26), the system determines whether the input voltage Vin is equal to or less than the ninth threshold Vd (step S27).

[0060] If the input voltage Vin exceeds the ninth threshold Vd (NO in step S27), the process returns to step S24, and the power supply device 2 continues to operate at the second maximum supply power Py. On the other hand, if the input voltage Vin is less than or equal to the ninth threshold Vd (YES in step S27), the output power control unit 21 changes the second maximum supply power Py of the DC / DC converter 20 to the third maximum supply power Pz and negotiates with the power receiving device 30 again using the third maximum supply power Pz (step S28). That is, the power supply device 2 operates at the third maximum supply power Pz.

[0061] Next, the input voltage measurement unit 22 measures the input voltage Vin at the third maximum supply power Pz (step S29). The output power control unit 21 also determines whether the input voltage Vin is equal to or greater than the eighth threshold Vc (step S30). If the input voltage Vin is equal to or greater than the eighth threshold Vc (YES in step S30), the process returns to step S24 and the system operates at the second maximum supply power Py. On the other hand, if the input voltage Vin is less than the eighth threshold Vc (NO in step S30), the system determines whether the input voltage Vin is 0 (step S31).

[0062] If the input voltage Vin is greater than 0 (NO in step S31), the process returns to step S28 and operates at the third maximum supply power Pz. On the other hand, if the input voltage Vin is 0 (YES in step S31), the output power control unit 21 shuts off the output of the DC / DC converter 20 (step S32).

[0063] The threshold for the maximum power supply of the DC / DC converter 20 preferably has hysteresis, as shown in Figure 6. Specifically, it is configured so that the same path is not followed when the maximum power supply decreases and increases. For example, when the input voltage Vin is less than or equal to the seventh threshold Vb, the maximum power supply decreases and switches from the first maximum power supply Px to the second maximum power supply Py. Also, when the input voltage becomes greater than or equal to the sixth threshold Va, the maximum power supply increases and switches from the second maximum power supply Py to the first maximum power supply Px. Therefore, by setting the seventh threshold Vb, which decreases the maximum power supply, and the sixth threshold Va, which increases the maximum power supply, to different values, the output voltage does not follow the same path when decreasing and increasing. As described above, by setting two types of thresholds and setting the two types of thresholds with an interval between them, the transition of the maximum power supply has hysteresis. The interval between the two types of thresholds is not particularly limited, but may be set based on the rated power of the DC / DC converter 20 to which it is applied. In the example shown in Figure 6, the interval between the two thresholds is set to 0.5V.

[0064] If the threshold for reducing the maximum supply power and the threshold for increasing it are the same, chattering occurs, where the maximum supply power frequently decreases and increases when the input voltage slightly increases or decreases near the threshold. As a result, stable control becomes difficult. Therefore, as described above, by dividing the threshold into two types and setting a gap between the two thresholds, the occurrence of chattering can be suppressed and stable control can be achieved.

[0065] The output power control unit 21 may gradually increase the maximum supply power when recovering from a state where the maximum supply power has been reduced. That is, the output power control unit 21 may gradually increase the maximum supply power when increasing it. For example, as shown in Figure 6, when the DC / DC converter 20 is operating at the third maximum supply power Pz, the output power control unit 21 may switch from the third maximum supply power Pz to the second maximum supply power Py when the input voltage becomes equal to or greater than the sixth threshold Va. Here, if the input voltage is also equal to or greater than the sixth threshold Va at the second maximum supply power Py, the output power control unit 21 may switch from the second maximum supply power Py to the first maximum supply power Px. This allows for a gradual increase in output power while suppressing a rapid increase in the output power of the power supply device 2 caused by a sudden increase in maximum supply power. By gradually increasing the output power, it is possible to suppress the input voltage from immediately falling below the threshold and to achieve stable control.

[0066] The output power control unit 21 may return to the maximum supply power level before the reduction when recovering from a state where the maximum supply power level has been reduced. For example, as shown in Figure 6, when the DC / DC converter 20 is operating at the third maximum supply power level Pz, the output power control unit 21 may switch from the third maximum supply power level Pz to the first maximum supply power level Px when the input voltage exceeds the sixth threshold level Va. This allows the maximum supply power level, which has been reduced on the condition that the input voltage exceeds a predetermined threshold level, to be returned to the initial maximum supply power level, making it possible to immediately supply the maximum output power to the power receiving device 30.

[0067] It is preferable that the output power control unit 21 refrains from making a determination for issuing the next control instruction for a predetermined time after issuing a control instruction to the DC / DC converter 20. That is, it is preferable that the output power control unit 21 suppresses the determination of whether or not to change the output power for a certain period of time. By suppressing the determination of whether or not to change the output power for a certain period of time, the output power control unit 21 suppresses the issuance of further control instructions until the output power of the DC / DC converter 20 is determined by negotiation. As a result, the maximum supply power is not changed until the negotiation is completed and the output power is set. Consequently, stable control is possible.

[0068] Referring to Figures 7 to 9, the control of the power supply system 100 will be explained in more detail. Specifically, the output voltage control of the DC power supply device 1 and the output power control of the power supply device 2 will be explained in detail. Figure 7 shows the power supply system 100 when there is one power receiving device 30. Figure 8 shows the power supply system 100 when two power receiving devices 30 are connected. Figure 9 shows the power supply system 100 when five power receiving devices 30 are connected.

[0069] As shown in Figure 7, the DC power supply unit 1 is connected to five power supply units 2. The power supply units 2 may have, for example, USB standard connection terminals. In the following explanation, we will use the case where the power supply unit 2 is configured to be connectable to the power receiving unit 30 via a USB standard connection terminal as an example. The maximum power supply of the power supply unit 2 is 100W. The threshold values ​​for each parameter are based on the graphs illustrated in Figures 3 and 6. Here, the power consumption of power receiving units 30A and 30B is 80W, and the power consumption of power receiving units 30C, 30D, and 30E is 50W.

[0070] As shown in Figure 7, the power receiving device 30A is connected to the power supply device 2A. During negotiation with the power receiving device 30A, the power supply device 2A sends a list containing PDOs that have a maximum supply power of 100W. In the example shown in Figure 7, the power receiving device 30A requested 80W, so the power supply device 2 outputs an output power of 80W. In this case, the output power of the DC power supply device 1 is 80W, so the output voltage is the first output voltage V1 (24.0V).

[0071] Next, as shown in Figure 8, a power receiving device 30B is connected to the power supply device 2B. In this case, power supply devices 2A and 2B send a list to power receiving devices 30A and 30B that includes a PDO with a maximum supply power of 100W. In the example shown in Figure 8, power receiving devices 30A and 30B request 80W, so power supply devices 2A and 2B output 80W of power. In this case, the output power of DC power supply device 1 becomes 160W, which is above the second threshold P2, so the output voltage control unit 11 switches from the first output voltage V1 (24.0V) to the second output voltage V2 (22.5V). As a result, the maximum supply power of power supply device 2 decreases, so power supply devices 2A and 2B negotiate again with power receiving devices 30A and 30B.

[0072] In this case, as shown in Figure 8, the power supply devices 2A and 2B send a list containing PDOs that have a maximum supply power of 65W. As the power receiving devices 30A and 30B request 60W, the power supply devices 2A and 2B output 60W of power. As a result, the output power of the AC / DC converter 10 decreases from 160W to 120W.

[0073] Next, as shown in Figure 9, power receiving devices 30C, 30D, and 30E are newly connected to power supply devices 2C, 2D, and 2E. As described above, power supply devices 2A to 2E send a list containing PDOs that have a maximum power supply of 65W to power receiving devices 30A to 30E. In the example shown in Figure 9, power receiving devices 30A and 30B request 60W, so power supply devices 2A and 2B output 60W of power. Also, since the newly connected power receiving devices 30C, 30D, and 30E request 50W, power supply devices 2C, 2D, and 2E output 50W of power.

[0074] In this case, the output power of the DC power supply device 1 becomes 270W, which is above the fourth threshold P4, so the output voltage control unit 11 switches from the second output voltage V2 (22.5V) to the third output voltage V3 (21.0V). As a result, the maximum supply power of the power supply device 2 decreases, so the power supply devices 2A to 2E negotiate again with the power receiving devices 30A to 30E.

[0075] In this case, as shown in Figure 9, power supply units 2A to 2E send a list containing PDOs with a maximum supply power of 50W. In the example shown in Figure 9, power receiving units 30A to 30E request 45W, so power supply units 2A to 2E output 45W of power. As a result, the output power of the AC / DC converter 10 decreases from 270W to 225W. This prevents the AC / DC converter 10 from exceeding its maximum output power even if the number of power receiving units 30 increases, thus preventing power supply interruptions. As a result, efficient power supply is achieved.

[0076] Using Figure 10, we will describe in detail the first modified example, the power supply system 100x and the DC power supply device 1x. Figure 10 is a block diagram illustrating the first modified example, the DC power supply device 1x. The DC power supply device 1x differs from the DC power supply device 1 in that the AC / DC converter 10, the output voltage control unit 11, and the output power measuring unit 14 are housed in separate enclosures.

[0077] As shown in Figure 10, the DC power supply device 1x houses the AC / DC converter 10, the output voltage control unit 11, and the output power measurement unit 14 in separate enclosures. Even in this case, the output voltage control unit 11 is configured to control the AC / DC converter 10. The same effects as the DC power supply device 1 can be obtained with DC power supply device 1x. Furthermore, because the AC / DC converter 10, the output voltage control unit 11, and the output power measurement unit 14 are housed in separate enclosures, the output voltage control unit 11 and the output power measurement unit 14 are less affected even if the AC / DC converter 10 generates heat. In addition, it is possible to easily retrofit the output voltage control unit 11 and the output power measurement unit 14 to an existing AC / DC converter 10.

[0078] Using Figure 11, a second modified example, the power supply system 100y and the DC power supply device 1y, will be described in detail. Figure 11 is a block diagram illustrating the DC power supply device 1y, the second modified example. The DC power supply device 1y differs from the DC power supply device 1 in that it has a DC / DC converter 40 in addition to the configuration of the DC power supply device 1.

[0079] As shown in Figure 11, the DC power supply device 1y has a DC / DC converter 40. The DC / DC converter 40 is located between the AC / DC converter 10 and the DC / DC converter 20 and is installed within the DC power supply device 1y. In the DC power supply device 1y, the output voltage control unit 11 issues control instructions to the DC / DC converter 40. That is, the output power is measured by the output power measuring unit 14, and the output voltage control unit 11 controls the output voltage output by the DC / DC converter 40 based on the measured output power. Even with the DC power supply device 1y, the same effects as the DC power supply device 1 can be obtained.

[0080] Using Figure 12, a third modified example, the power supply system 100z and the DC power supply device 1z, will be described in detail. Figure 12 is a block diagram illustrating the DC power supply device 1z, the third modified example. The DC power supply device 1z differs from the DC power supply device 1 in that, in addition to the configuration of the DC power supply device 1, it has a DC / DC converter 40, and the AC / DC converter 10, the output voltage control unit 11, the output power measurement unit 14, and the DC / DC converter 40 are housed in separate enclosures.

[0081] As shown in Figure 12, the DC power supply device 1z has a DC / DC converter 40. Furthermore, the DC / DC converter 40 is housed in the same enclosure as the output voltage control unit 11 and the output power measurement unit 14. Here, the AC / DC converter 10 is housed in a separate enclosure from the output voltage control unit 11, the output power measurement unit 14, and the DC / DC converter 40. Note that even with the DC power supply device 1z, the same effects as the DC power supply device 1 can be obtained. Moreover, it is possible to easily retrofit the DC / DC converter 40, the output voltage control unit 11, and the output power measurement unit 14 to an existing AC / DC converter 10.

[0082] The wiring method of the power supply system 100 will be described below with further reference to Figures 15 to 17. The wiring method of the power supply system 100 may be a method in which the DC power cable 13 extending from the DC power supply device 1 branches out toward each power supply device 2 (hereinafter referred to as the bus wiring method), as illustrated in the above embodiment and Figure 15. Alternatively, the wiring method of the power supply system 100 may be a method in which the DC power cable 13 extending from the DC power supply device 1 is connected in series with each power supply device 2 (hereinafter referred to as the daisy-chain wiring method), as shown in Figure 16. In detail, the daisy-chain wiring method is configured such that the DC power cable 13 extending from the DC power supply device 1 is connected to the input terminal of the upstream power supply device 2, and is sequentially connected in a chain from the output terminal of the said power supply device 2 to the input terminal of the downstream power supply device 2. As a result, the power output from the DC power supply device 1 is transmitted to the terminal power supply device 2 via each power supply device 2. Furthermore, the wiring method for the power supply system 100 may be a method in which DC power cables 13 extend from the DC power supply device 1 to each of the multiple power supply devices 2, and each power supply device 2 is connected separately to the DC power supply device 1 (hereinafter referred to as the star wiring method), as shown in Figure 17.

[0083] The control method of the power supply system 100 will be described in detail below with further reference to Figures 18 to 23. The overall control of the power supply system 100 will be described in detail below. Unless otherwise specified, the wiring method of the power supply system 100 may be a bus wiring method, a daisy-chain wiring method, or a star wiring method. Furthermore, the control method described below is just one example, and control may be performed by combining multiple control methods.

[0084] <Power Budget Management System> In the following, with reference to Figure 18, we will explain the power budget management method, which is an example of a control method for the power supply system 100. The power budget management method is a control method that uniformly limits the maximum supply power of all multiple power supply devices 2 when the output power of the DC power supply device 1 exceeds a predetermined value. That is, in the power budget management method, the same maximum supply power is set for all of the multiple power supply devices 2. In the power budget management method, for example, each of the multiple power supply devices 2 has an input voltage-to-maximum supply power relationship as shown in Figure 6. In the power budget management method, since the limit is applied uniformly to all power supply devices 2, it is easy to prevent overload in the DC power supply device 1.

[0085] The following describes a specific example of controlling the power supply system 100 using the power budget management method, with reference to Figure 18. First, as shown in Figure 18, the power supply devices 2A to 2D are initially set to a maximum supply power of 100W. Also, in state 1, 100W is output from power supply device 2A. At this time, the output voltage of DC power supply device 1 is 24.0V. Now, in state 2, when the output power of DC power supply device 1 increases from 100W to 200W, the output voltage of DC power supply device 1 decreases from 24.0V to 22.5V. That is, the input voltage to power supply devices 2A to 2D decreases from 24.0V to 22.5V.

[0086] Each of the multiple power supply devices 2A to 2D reduces its maximum supply power from 100W to 65W based on the decrease in input voltage. In other words, each of the multiple power supply devices 2A to 2D uniformly limits its maximum supply power. In state 3, as the maximum supply power decreases, the output power from power supply devices 2A and 2B decreases to 65W each, and the total output power (output power of DC power supply device 1) becomes 130W. Thus, in the power budget management method, all of the multiple power supply devices 2 control their maximum supply power based on the fluctuations in the output voltage of DC power supply device 1.

[0087] <Control method based on port priority> In the following section, with reference to Figure 19, we will explain a control method based on port priority, which is an example of a control method for the power supply system 100. The control method based on port priority is a control method that limits the maximum supply power of multiple power supply devices 2 based on a priority set in advance for each of the multiple power supply devices 2 when the output power of the DC power supply device 1 exceeds a predetermined value. In other words, in the control method based on port priority, different maximum supply powers are set for the multiple power supply devices 2.

[0088] In a port priority-based control system, a priority is predetermined for each of the multiple power supply devices 2. In a port priority-based control system, for example, the maximum power supply of a power supply device 2 with a high priority is maintained, and the maximum power supply of a power supply device 2 with a low priority is reduced. In a port priority-based control system, for example, a power supply device 2 with a low priority may have the relationship between input voltage and maximum power supply as shown in Figure 6, and a power supply device 2 with a high priority may be controlled so that its maximum power supply does not fluctuate even if the input voltage fluctuates.

[0089] The following describes a specific example of controlling the power supply system 100 using a port priority-based control method, with reference to Figure 19. First, as shown in Figure 19, the power supply devices 2A to 2D are initially set to a maximum supply power of 100W. In addition, each of the power supply devices 2A to 2D has a priority assigned to it in advance. In the example shown in Figure 19, there are two types of priority settings: "high" and "low," with power supply device 2A set to "high" and power supply devices 2B to 2D set to "low." In state 1, power supply device 2A outputs 100W. Now, in state 2, if the output power of DC power supply device 1 increases from 100W to 200W, the output voltage of DC power supply device 1 decreases from 24.0V to 22.5V. That is, the input voltage of power supply devices 2A to 2D decreases from 24.0V to 22.5V.

[0090] Power supply devices 2B to 2D, which are set to "low" priority, limit their maximum power supply from 100W to 65W based on the decrease in input voltage. Power supply device 2A, however, is set to "high" priority, so its maximum power supply does not change. In state 3, as the maximum power supply decreases, the output power from power supply device 2B decreases to 65W, and the total output power (output power of DC power supply device 1) becomes 165W. In this way, the port priority-based control method controls the maximum power supply based on the priority set in advance for power supply devices 2A to 2D. According to the port priority-based control method, by setting the priority, it is possible to select power supply device 2 that maintains output power, thus preventing interference with the function of power receiving devices that require a certain level of output power.

[0091] In the port priority-based control method, priorities are set in advance for the power supply device 2 as described above. Here, the method of setting priorities is not particularly limited and may be set by a physical switch provided on the power supply device 2. Alternatively, priorities may be set by a software write operation to a memory unit (not shown) provided on the power supply device 2. In the above example, the explanation was given using a two-level priority system of "high" and "low," but the priority system is not limited to two levels and may be set in multiple levels, for example, three or more levels. Also, the rate of change in maximum supplied power may differ depending on the priority level. For example, the lower the priority level, the greater the rate of decrease in maximum supplied power.

[0092] <Total power consumption limiting method> In the following section, with reference to Figure 20, we will explain the total power consumption limiting method, which is an example of a control method for the power supply system 100. The total power consumption limiting method is a control method that limits the maximum power supply of one of the multiple power supply devices 2 that is not connected to a power receiving device when the output power of the DC power supply device 1 exceeds a predetermined value. Whether or not a power receiving device is connected to a power supply device 2 is determined, for example, by the presence or absence of output power in the power supply device 2.

[0093] The following describes a specific example of controlling the power supply system 100 using the total power consumption limiting method, with reference to Figure 20. First, as shown in Figure 20, the power supply devices 2A to 2D are initially set to a maximum supply power of 100W. In state 2, if the output power of DC power supply device 1 increases from 100W to 200W, the output voltage of DC power supply device 1 decreases from 24.0V to 22.5V. That is, the input voltage of power supply devices 2A to 2D decreases from 24.0V to 22.5V.

[0094] Power supply units 2C and 2D, which are not connected to a power receiving device, limit their maximum power supply from 100W to 65W based on the decrease in input voltage. Power supply units 2A and 2B, which are connected to a power receiving device, do not have their maximum power supply fluctuate. Thus, in the total power consumption limiting method, the maximum power supply is controlled based on whether or not power receiving devices are connected to power supply units 2A to 2D. In other words, power supply unit 2 determines whether or not it is necessary to limit its maximum power supply by judging the connection status of its own power receiving device. With the total power consumption limiting method, by pre-reducing the maximum power supply of power supply unit 2, which is not connected to a power receiving device, it is possible to suppress a sudden increase in the total output power (output power of DC power supply unit 1) when a power receiving device is newly connected. In addition, since the output of power supply unit 2, which is already connected to a power receiving device, is not limited, efficient power supply is possible.

[0095] <Power adjustment method based on the number of connections> In the following, with reference to Figure 21, we will explain a power adjustment method based on the number of connections, which is an example of a control method for the power supply system 100. The power adjustment method based on the number of connections is a control method that evenly distributes the maximum output power (for example, 300W) preset in the DC power supply device 1 to the power supply devices 2 to which the power receiving devices are connected. Note that the power adjustment method based on the number of connections requires the DC power supply device 1 to detect whether or not a power receiving device is connected to the power supply device 2. Therefore, in the power supply system 100 according to this disclosure, it is possible to implement this method when the wiring method is a star wiring method. With a star wiring method, the presence or absence of a power receiving device connected to each power supply device 2 can be detected by acquiring power information at the base end of the DC power cable 13.

[0096] The DC power supply device 1, for example, when a new power receiving device is connected, evenly distributes the maximum output power to the power supply devices 2 to which the power receiving device is connected. Specifically, the DC power supply device 1 divides the preset maximum output power by the number of power supply devices 2 to which the power receiving device is connected to determine the maximum supply power for each power supply device 2 to which the power receiving device is connected. Note that the maximum supply power for power supply devices 2 to which no power receiving device is connected may be set to 0W. Subsequently, the determined maximum supply power is notified to each of the power supply devices 2.

[0097] In this specification, "notification" means that the DC power supply device 1 transmits information to the power supply device 2 by controlling the behavior of its output voltage or output current. That is, "notification" in this specification means that information is transmitted using only power lines and not communication lines. The DC power supply device 1 converts the information it wants to transmit to the power supply device 2 into the behavior of its output voltage according to predetermined rules and outputs it. The power supply device 2, upon receiving the output voltage, converts the behavior of the output voltage into information according to predetermined rules. That is, the power supply device 2 acquires the information based on the behavior of the input voltage or input current and sets the maximum power supply. This enables the DC power supply device 1 to transmit information to the power supply device 2.

[0098] In the above "Notification," the behavior of the output voltage of DC power supply device 1 (input voltage of power supply device 2) refers to, for example, the amount of change in voltage, the time of voltage drop, the number of voltage drops in a predetermined time, and the period of voltage drop. Furthermore, the behavior of the output current of DC power supply device 1 (input current of power supply device 2) refers to, for example, the amount of change in current, the time of current change, the number of current changes in a predetermined time, and the period of current change.

[0099] The following describes a specific example of controlling the power supply system 100 using a power adjustment method based on the number of connections, with reference to Figure 21. The maximum output power of the DC power supply device 1 is set to 300W. First, as shown in Figure 21, power supply devices 2A to 2C are initially set to a maximum supply power of 100W, and power supply device 2D is set to a maximum supply power of 0W. In state 2, when a power receiving device is connected to power supply device 2D, the DC power supply device 1 detects this connection. Then, the maximum output power of the DC power supply device 1 is divided by the number of power supply devices 2A to 2D to which power receiving devices, including power supply device 2D, are connected, to determine and notify the maximum supply power of each power supply device 2A to 2D. In the example shown in Figure 21, a maximum supply power of 75W for each power supply device 2A to 2D is notified. In this way, the power adjustment method based on the number of connections controls the maximum supply power based on the number of power supply devices 2 to which power receiving devices are connected. According to the power adjustment method based on the number of connections, the maximum output power of the DC power supply device 1 is equally distributed among the power supply device 2 to which the power receiving device is connected, thus ensuring that the power supply device 2 to which the power receiving device is connected can reliably supply power.

[0100] <Rotation system> In the following, with reference to Figures 22 and 23, we will explain the rotational method, which is an example of a control method for the power supply system 100. The rotational method is a control method in which the DC power supply device 1 notifies multiple power supply devices 2 at regular intervals, and the power supply devices 2 switch the maximum power supply based on the notification. According to the rotational method, it is possible to provide each power receiving device connected to the power supply device 2 with an equal opportunity to receive power.

[0101] The following describes a specific example of controlling the power supply system 100 using a rotational method, with reference to Figure 22. First, as shown in Figure 22, in the initial state, power supply device 2A is pre-set to a maximum supply power of 100W, and power supply devices 2B to 2D are set to a maximum supply power of 65W. Here, the maximum supply power of power supply devices 2A to 2D in each state is set so that their sum does not exceed the maximum output power of DC power supply device 1.

[0102] After a certain period of time has elapsed, DC power supply device 1 sends a first notification to power supply devices 2A and 2B. Upon receiving the first notification, power supply devices 2A and 2B switch their maximum power supply. Specifically, as shown in Figure 22, power supply device 2A switches its maximum power supply from 100W to 65W, and power supply device 2B switches its maximum power supply from 65W to 100W. After a certain period of time has elapsed since the first notification, DC power supply device 1 sends a second notification to power supply devices 2B and 2C. At this time, as shown in Figure 22, power supply device 2B switches its maximum power supply from 100W to 65W, and power supply device 2C switches its maximum power supply from 65W to 100W. After a certain period of time has elapsed since the second notification, DC power supply device 1 sends a third notification to power supply devices 2C and 2D. At this time, as shown in Figure 22, power supply unit 2C switches its maximum supply power from 100W to 65W, and power supply unit 2D switches its maximum supply power from 65W to 100W. Furthermore, after a certain period of time has elapsed since the third notification, DC power supply unit 1 issues a fourth notification to power supply units 2D and 2A. At this time, as shown in Figure 22, power supply unit 2D switches its maximum supply power from 100W to 65W, and power supply unit 2A switches its maximum supply power from 65W to 100W. By repeating the above cycle, a maximum supply power of 100W is sequentially allocated to power supply units 2A to 2D. As a result, each power supply unit 2 will have a moment when its maximum supply power is 100W, and each power supply unit 2 will be given an equal opportunity to provide high output.

[0103] The DC power supply device 1 has, for example, a clock that counts a certain amount of time. The clock starts counting, for example, when a power receiving device is first connected to one of the power supply devices 2, and the DC power supply device 1 notifies the power supply devices 2 at regular intervals counted by the clock. The clock may also stop counting if no power receiving devices are connected to any of the power supply devices 2.

[0104] It is preferable that each of the multiple power supply devices 2 is assigned an address. In this case, it is preferable that the DC power supply device 1 notifies the multiple power supply devices 2 of its address at regular intervals, and that the multiple power supply devices 2 switch the maximum power supply when their own address is notified. This makes it possible to identify which power supply device 2 switches the maximum power supply even in daisy-chain wiring and bus wiring systems where notifications from the DC power supply device 1 are notified to all power supply devices 2. Addresses may also be set in star wiring systems. However, in star wiring systems, since the DC power supply device 1 can notify each power supply device 2 separately, it is not necessary to set addresses.

[0105] The following section provides a detailed explanation of how to set addresses in a rotational system.

[0106] The power supply device 2 may have a physical switch for setting the address. That is, the address of the power supply device 2 may be set by a physical switch provided on the power supply device 2. The physical switch is, for example, a DIP switch. Address setting using a physical switch is easy because of its simple structure. Also, since there is no need to provide a complex control circuit in the power supply device 2, the address can be set without increasing the cost of the power supply device 2.

[0107] The power supply device 2 may have a memory unit that stores addresses set by software writing. That is, the address of the power supply device 2 may be set by a software writing process to a memory unit provided in the power supply device 2. Software-based address setting is performed, for example, during the installation of the power supply system 100. Software-based address setting allows for easy resetting, thus providing high design flexibility. For example, even if the number of power supply devices 2 in the power supply system 100 increases or decreases, the addresses can be easily reset. Here, the memory unit is a non-volatile memory such as ROM, a volatile memory such as RAM, etc.

[0108] The power supply device 2 may have a random value generation unit that generates random values. The power supply device 2 may also determine an address based on these random values. For example, when the power supply system 100 is connected to a power source, the random value generation unit generates a random value, and the address of the power supply device 2 is determined. Determining the address using random values ​​allows for the automation of address determination.

[0109] In a star-wiring power supply system 100, the DC power supply device 1 may set a different address for each of the multiple power supply devices 2. The DC power supply device 1 has an address determination unit that determines a different address for each of the multiple power supply devices 2. The DC power supply device 1 then sets the determined address for each of the multiple power supply devices 2. For example, the DC power supply device 1 notifies each power supply device 2 of the determined address, and the power supply devices 2 store the notified address. As a result, since the address determination unit of the DC power supply device 1 determines different addresses, the addresses of each power supply device 2 can be set so that they do not overlap, and control errors due to address overlap can be prevented more effectively. In addition, since the DC power supply device 1 has an address determination unit, the address setting for each power supply device 2 can be performed automatically. For example, the address determination unit determines the address for each of the multiple power supply devices 2 when the power supply system 100 is connected to a power source.

[0110] The power supply system 100 may have a main cable 13a extending from the DC power supply device 1, and a plurality of branch cables 13b extending from the main cable 13a to each of the plurality of power supply devices 2, as shown in Figure 23(A). The power supply system 100 may also have a branch ammeter SC provided on each of the plurality of branch cables 13b, a main ammeter MC provided on the main cable 13a between the plurality of branch cables 13b and the DC power supply device 1, and between the plurality of branch cables 13b, and a switch SW provided on each of the plurality of branch cables 13b between the power supply device 2 and the branch ammeter SC, which controls the input current of the branch ammeter SC and the main ammeter MC by switching between ON and OFF. In this case, each of the plurality of power supply devices 2 sets its own address based on the state of the main ammeter MC and the branch ammeter SC when the switch SW is switched between ON and OFF.

[0111] The address setting using switches SW will be explained in detail below, with further reference to Figure 23(B). In Figure 23(B), 1 is used when current flows through the main line ammeter MC, and 0 is used when no current flows. Similarly, 1 is used when current flows through the branch line ammeter SC, and 0 is used when no current flows. Also, in the initial state, all switches SW are in the OFF position.

[0112] The DC power supply unit 1 notifies multiple power supply units 2A to 2D of information regarding address setting. For example, the DC power supply unit 1 notifies multiple power supply units 2 to switch the switch SW ON and OFF once within a predetermined execution time. The multiple power supply units 2A to 2D that receive the notification each turn the switch SW ON for a predetermined time at different times, and then turn it OFF after the predetermined time has elapsed. At this time, the power supply units 2 detect the state of the switch SW and the presence or absence of current in the main line ammeter MC and branch line ammeter SC.

[0113] Multiple power supply devices 2A to 2D determine whether or not current flows to the main line ammeter MC and branch line ammeter SC only when their own switch SW is turned ON. Here, power supply device 2D, which only has current flowing to the main line ammeter MC and branch line ammeter SC when its own switch SW is turned ON, is determined to be the power supply device 2 located furthest from the DC power supply device 1 in the power supply system 100. Power supply device 2D, whose position has been determined, sets its own address according to the position and address agreement predetermined with the DC power supply device 1. Note that, as shown in Figure 23(B), power supply devices 2A to 2C, which have current flowing to the main line ammeter MC when their own switch SW is OFF, do not have an address set.

[0114] After a predetermined execution time has elapsed, the DC power supply device 1 will again notify the user of information regarding address setting. At this time, the multiple power supply devices 2A to 2C will again set their addresses using the switch SW, but power supply device 2D, whose address has already been determined, will not move the switch SW and will not participate in address setting. The multiple power supply devices 2A to 2C will, as described above, each turn the switch SW ON for a predetermined time at different times, turn it OFF after the predetermined time has elapsed, and detect the state of the switch SW and the presence or absence of current in the main line ammeter MC and branch line ammeter SC. As a result, it will be determined that power supply device 2C is the power supply device 2 located furthest from the DC power supply device 1 among the multiple power supply devices 2A to 2C. Power supply device 2C, whose position has been determined, will set its own address according to the position and address agreement that was previously established with the DC power supply device 1.

[0115] The above cycle is repeated until an address is set for all power supply devices 2. According to the above method, address setting can be automated. Furthermore, even when setting the address for each power supply device 2 automatically, it is possible to prevent address duplication. In the above explanation, a bus wiring system as shown in Figure 23(A) was used as an example, but the above method can also be applied to a daisy-chain wiring system. In the case of a daisy-chain wiring system, a switch SW, a main line ammeter MC, and a branch line ammeter SC are provided in the power supply device 2.

[0116] As described above, the power supply device and power supply system having the above configuration allow for simplification and cost reduction of the power supply device and power supply system by performing control without communication other than between the power supply device and the power receiving device. Furthermore, the DC power supply device having the above configuration allows for efficient power supply by avoiding over-specification of the power converter and preventing power supply interruptions.

[0117] The above embodiments can be modified as appropriate without impairing the purpose of this disclosure. For example, in the above embodiments, the description was given using the case where the power receiving device 30 is mainly an information terminal as an example, but the power receiving device 30 is not limited to an information terminal. The power receiving device 30 may be, for example, a lighting device such as a ceiling light. Even in this case, the DC power supply device 1 will function properly and the above effects can be obtained.

[0118] Furthermore, as shown in Figure 24, the DC power supply device 1 may have an output current control unit 15 that controls the output current based on at least one of the input state or output state of the AC / DC converter 10. Here, the DC power supply device 1 may have only one of the output voltage control unit 11 or the output current control unit 15, or it may have an output control unit 16 consisting of the output voltage control unit 11 and the output current control unit 15. The output current control unit 15 can notify the power supply device 2 by controlling the output current.

[0119] Furthermore, the power supply device 2 may have an input current measuring unit 24 for measuring the input current, as shown in Figure 24. Here, the power supply device 2 may have only one of the input voltage measuring unit 22 or the input current measuring unit 24, or it may have a measuring unit 25 consisting of the input voltage measuring unit 22 and the input current measuring unit 24. With the input current measuring unit 24, it is possible to receive notifications via current by measuring the input current.

[0120] This disclosure is further illustrated by the following embodiments. Configuration 1: A DC power supply device comprising a power conversion device that converts AC power to DC power, and which supplies DC power to a plurality of power supply devices, wherein the power conversion device and the power supply devices are configured as separate units, and each has an output voltage control unit that controls the output voltage based on at least one of the input state or output state of the power conversion device. Configuration 2: The DC power supply device according to configuration 1, wherein the input state consists of at least one of the input current and input power of the power converter. Configuration 3: The DC power supply device according to configuration 1 or 2, wherein the output state is comprised of at least one of the output current and output power of the power converter. Configuration 4: The DC power supply device according to any one of configurations 1 to 3, wherein the output voltage control unit lowers the output voltage of the power converter when at least one of the input state and the output state exceeds a predetermined threshold, and raises the output voltage of the power converter when it falls below the threshold. Configuration 5: The DC power supply device according to any one of configurations 1 to 4, wherein the output voltage control unit increases the output voltage in steps when the output voltage returns from a reduced state. Configuration 6: The DC power supply device according to any one of configurations 1 to 4, wherein the output voltage control unit restores the output voltage to its maximum output voltage before it was reduced when recovering from a reduced output voltage state. Composition 7: The power converter is a DC power supply device according to any one of configurations 1 to 6, wherein the power converter stops outputting the output power when the output power of the power converter exceeds a preset maximum output power. Composition 8: The DC power supply device according to configuration 7, wherein the DC power supply device resumes outputting the output power after a predetermined time has elapsed since the output of the output power was stopped, or after the DC power supply device has been restarted. Composition 9: The DC power supply device according to any one of configurations 1 to 8, wherein the threshold value of the output voltage of the power converter has hysteresis. Configuration 10: The DC power supply device according to any one of configurations 1 to 9, wherein the output voltage control unit does not perform a determination for issuing the next control instruction for a predetermined time after issuing a control instruction to the power converter. Composition 11: The DC power supply device according to configuration 1, wherein the output voltage control unit continuously varies the output voltage based on at least one of the input state or the output state. Composition 12: The DC power supply device according to configuration 11, wherein the output voltage control unit continuously decreases the output voltage in response to an increase in at least one of the input state or the output state. Composition 13: A virtual resistance is set in the output voltage control unit in advance. The DC power supply device according to configuration 11, wherein the output voltage control unit continuously varies the output voltage based on the virtual resistance and the output state. Composition 14: The DC power supply device according to configuration 11, wherein the output voltage control unit does not fluctuate the output voltage until the output state exceeds a predetermined value. Composition 15: The DC power supply device according to any one of configurations 1 to 14, wherein the output voltage control unit is housed in a separate enclosure from the power converter. [Explanation of Symbols]

[0121] 1,1x,1y,1z DC power supply equipment 2,2A,2B,2C,2D,2E power supply device 10. AC / DC converter (power conversion device) 11 Output Voltage Control Unit 12 AC power cables 13 DC power cable 13a Main cable 13b Branch cable 14. Output power measurement section 14a Output current measurement section 14b Output voltage measurement section 15 Output Current Control Unit 16 Output control unit 20,40 DC / DC converter (DC voltage converter) 21 Output Power Control Unit 22 Input voltage measurement section 23 Temperature measurement section 24 Input current measurement section 25 Measuring part 30, 30A, 30B, 30C, 30D Power receiving equipment 31 Power supply cable 32 communication lines 100, 100x, 100y, 100z power supply system MC main line ammeter SC branch line ammeter SW Switch

Claims

1. Equipped with a power conversion device that converts AC power to DC power, A DC power supply device that supplies DC power to multiple power supply devices, The power conversion device and the power supply device are configured as separate units. A DC power supply device having an output voltage control unit that controls the output voltage based on at least one of the input state or output state of the power converter.

2. The DC power supply device according to claim 1, wherein the input state is comprised of at least one of the input current and input power of the power converter.

3. The DC power supply device according to claim 1, wherein the output state is comprised of at least one of the output current and output power of the power converter.

4. The DC power supply device according to claim 1, wherein the output voltage control unit lowers the output voltage of the power converter when at least one of the input state or the output state exceeds a predetermined threshold, and raises the output voltage of the power converter when it falls below the threshold.

5. The DC power supply device according to claim 1, wherein the output voltage control unit increases the output voltage in steps when the output voltage returns from a reduced state.

6. The DC power supply device according to claim 1, wherein the output voltage control unit restores the output voltage to the maximum output voltage before it was reduced when it recovers from a reduced state.

7. The DC power supply device according to claim 1, wherein the power converter stops outputting the output power when the output power of the power converter exceeds a preset maximum output power.

8. The DC power supply device according to claim 7, wherein the DC power supply device resumes outputting the output power after a predetermined time has elapsed since the output of the output power was stopped, or after the DC power supply device has been restarted.

9. The DC power supply device according to claim 1, wherein the threshold value of the output voltage of the power converter has hysteresis.

10. The DC power supply device according to claim 1, wherein the output voltage control unit does not perform a determination for issuing the next control instruction for a predetermined time after issuing a control instruction to the power converter.

11. The DC power supply device according to claim 1, wherein the output voltage control unit continuously varies the output voltage based on at least one of the input state or the output state.

12. The DC power supply device according to claim 11, wherein the output voltage control unit continuously decreases the output voltage in response to an increase in at least one of the input state or the output state.

13. A virtual resistance is set in the output voltage control unit in advance. The DC power supply device according to claim 11, wherein the output voltage control unit continuously varies the output voltage based on the virtual resistance and the output state.

14. The DC power supply device according to claim 11, wherein the output voltage control unit does not fluctuate the output voltage until the output state exceeds a predetermined value.

15. The DC power supply device according to any one of claims 1 to 14, wherein the output voltage control unit is housed in a separate enclosure from the power conversion device.

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