DC power supply system and power supply system

Abstract

To provide a DC power supply system that executes power supply to a load without performing cooperative control between a plurality of DC power supplies connected in parallel, and to extend the life of the DC power supply system and improve the maintainability of the DC power supply system.SOLUTION: A DC power supply system is formed by connecting a plurality of DC power supply devices 10 in parallel to a load 120. The DC power supply device 10 is a CVCC power supply, and until an output current Io reaches an upper limit current Icc, turn-on and off of a semiconductor switching element 130 is controlled so that output voltage Vo is maintained to be a reference voltage Vr. When the ripple voltage of a smoothing capacitor 133 exceeds a determination voltage while an ambient temperature Ta is higher than a predetermined determination temperature, an increase of the ripple voltage is detected, and the reference voltage Vr is reduced to prevent the progress of deterioration of the smoothing capacitor 133. The detection of the increase of the ripple voltage is used as maintenance information for managing a DC power supply device.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a DC power supply system and a power supply system.

Background Art

[0002] In recent years, DC electrical equipment has attracted attention in DC power supply for zero-emission buildings (ZEB), power supply for data centers, electrification of mobility, etc., and its demand is increasing. For this reason, there is also an increasing demand for DC power supply systems for supplying power to DC electrical equipment in terms of increased capacity, high reliability, and miniaturization. In particular, for increased capacity, in addition to using a single large-capacity DC power supply, a configuration in which multiple small-capacity DC power supplies are operated in parallel is adopted.

[0003] For example, in Japanese Patent Application Laid-Open No. 2006-34047 (Patent Document 1), in a configuration in which a plurality of power supply units (DC power supply devices) whose droop characteristics part performs constant current operation are connected in parallel to an external load, only the first power supply unit is started, and when the output current reaches a constant current (maximum current), a start signal is transmitted to the next-stage power supply unit, and thereafter the power supply units are sequentially started step by step. Further, in Patent Document 1, the reference voltage indicating the constant current value due to the droop characteristics is transmitted together with the start signal, so that when the power supply units are sequentially started, the burden is balanced between the power supply units.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] According to the configuration of Patent Document 1, it is possible to supply current to a large-capacity load without using a large-capacity power source that tends to be difficult to miniaturize and improve efficiency. However, since cooperative operation involving the transmission and reception of the above-described start signal and reference voltage signal is performed among a plurality of DC power supply devices (power modules), there is a concern about increased control complexity including an increase in control lines.

[0006] On the other hand, when a plurality of parallel-connected DC power sources are operated without the cooperative operation as in Patent Document 1, there may be a difference in output voltage between the DC power supply devices due to individual differences. In this case, in a situation where the current supply to the load can be covered by a part of the plurality of power modules, current will be intensively supplied from the DC power supply device with a high output voltage. As a result, there is a concern that the probability of failure will increase due to the progress of component degradation in some of the DC power supply devices.

[0007] The present disclosure has been made to solve such problems, and an object of the present disclosure is to avoid an increase in the failure probability of some DC power sources and achieve a longer life and improve maintainability in a DC power supply system that realizes power supply corresponding to changes in the output current to a load without performing cooperative control by exchanging signals or information among a plurality of parallel-connected DC power sources.

Means for Solving the Problems

[0008] In one aspect of the present disclosure, a DC power supply system is provided for supplying a DC voltage and a DC current to a load. The DC power supply system includes a plurality of DC power supply devices having output sides electrically connected to the load in parallel. Each of the plurality of DC power supply devices enters a non-operating state in which it does not output current when the DC voltage supplied to the load is higher than the actual output voltage of the DC power supply device, while when the DC voltage is below the output voltage, it operates so as to enter an operating state according to a predetermined output characteristic. The output characteristic is such that in each DC power supply device, when the output current is smaller than the upper limit current set for each of the plurality of DC power supply devices, it operates in a constant voltage mode in which feedback control of the output voltage is performed to maintain the output voltage at the reference voltage, while when the output current reaches the upper limit current, it is set to operate in a constant current mode in which feedback control of the output current is performed to maintain the output current at the upper limit current. In each DC power supply device, the upper limit current is set to be equal to or lower than the rated current of the DC power supply device. Each DC power supply device includes a smoothing capacitor connected to the output side, a voltage detection circuit, a temperature detection circuit, and a control circuit. The smoothing capacitor has a characteristic that the DC resistance component increases as deterioration progresses. The voltage detection circuit detects the ripple voltage generated in the smoothing capacitor. The temperature detection circuit detects the ambient temperature of the smoothing capacitor. When the ripple voltage exceeds a predetermined determination voltage when the ambient temperature is higher than a predetermined determination temperature, an increase in the ripple voltage is detected and the reference voltage in the constant voltage mode of the DC power supply device is decreased.

[0009] In another aspect of the present disclosure, a power supply system is provided. The power supply system includes M DC power supply systems, where M is an integer of 2 or more, and a management device. Each of the M DC power supply systems has a communication function with the management device and is configured to transmit, to the management device, maintenance information for notifying an abnormality of each of the plurality of DC power supply devices in the DC power supply system in combination with the identification information of each of the plurality of DC power supply devices. The maintenance information includes information on whether or not the control circuit has detected an increase in the ripple voltage in the DC power supply device of each DC power supply system.

Advantages of the Invention

[0010] According to the present disclosure, in a DC power supply system that realizes power supply corresponding to a change in output current to a load without performing cooperative control by exchanging signals or information between a plurality of parallel-connected DC power supply devices, it is possible to avoid an increase in the failure probability of some DC power supply devices, achieve a longer lifespan, and improve maintainability.

Brief Description of the Drawings

[0011]

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Modes for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated in principle.

[0013] Embodiment 1. FIG. 1 shows a block diagram for explaining the configuration of the DC power supply system according to the present embodiment.

[0014] Referring to FIG. 1, the DC power supply system 100 according to the present embodiment includes N (N: an integer of 2 or more) DC power supply devices 10(1) to 10(N). Each of the DC power supply devices 10(1) to 10(N) can be configured by power modules of the same specification, and it is assumed that their respective circuit configurations, capacities (current capacities), and life designs are equivalent, but it is not essential that they have the same specification. For example, the capacities (current capacities) may be different among the DC power supply devices 10(1) to 10(N).

[0015] The input sides of the DC power supply devices 10(1) to 10(N) are connected to a power source 101. As will be described later, in the present embodiment, it is assumed that the DC power supply devices 10(1) to 10(N) perform DC / DC conversion by turning on and off at least one semiconductor switching element (not shown). Therefore, the power source 101 can be a power converter that converts an AC voltage from an AC power supply into a DC voltage, or a DC power supply by a power storage element such as a battery.

[0016] Alternatively, by arranging a rectifier circuit at the input stage of the DC power supply devices 10(1) to 10(N), the power source 101 can also be configured by an AC power supply. In FIG. 1, a configuration example is shown in which the input sides of the DC power supply devices 10(1) to 10(N) are connected to a common power source 101, but it is also possible to adopt a configuration in which a plurality of power sources 101 are connected to the input sides of some of the DC power supply devices 10(1) to 10(N) respectively.

[0017] Each of the DC power supply devices 10(1) to 10(N) outputs DC power between the DC output terminals P(+) and N(-) with feedback (FB) control of either the output voltage or the output current. The DC output terminals P(+), N(-) of the DC power supply devices 10(1) to 10(N) are connected in parallel to the power lines PL, NL for supplying power to the load 120.

[0018] The load 120 is a DC electrical device that requires a load current exceeding the supply current of one of the DC power supply devices 10(1) to 10(N). Also, the load 120 has a margin (±X(%)) that can tolerate voltage fluctuations within a predetermined range with respect to the rated voltage Vrx. Conversely, the output voltage Vout from the DC power supply system 100 to the load 120 needs to be within the voltage tolerance range of Vout = Vrx ± X(%) according to the above margin. Also, the maximum load current Imax for the load 120 is predetermined.

[0019] The load 120 is composed of a resistive load, an inductive load, a capacitive load, or a combination of a power converter for DC / AC conversion and an AC electrical device (such as a motor), and is composed of devices that require DC power supply, such as loads of DC power distribution facilities, air conditioners, indoor lights, elevators, and home appliances. For example, two or more of the DC electrical devices are installed for the load 120, and the output current (load current) from the DC power supply system 100 to the load 120 changes according to the number of operating units.

[0020] Fig. 2 shows a conceptual diagram for explaining the output characteristics of each of the DC power supply devices 10(1) to 10(N) shown in Fig. 1.

[0021] Referring to Fig. 2, each of the DC power supply devices 10(1) to 10(N) operates in a constant voltage (CV) mode by voltage feedback control to maintain the output voltage at the reference voltage Vr when the output current is lower than the upper limit current Icc. On the other hand, when the output current exceeds the upper limit current Icc, it operates in a constant current (CC) mode to limit the output of the DC power supply devices 10(1) to 10(N) so that the output current does not increase further. That is, in the CC mode, current feedback control with the current target value set to the upper limit current Icc is performed, and the output voltage is no longer directly controlled. For this reason, the output voltage (Vo) of the DC power supply device decreases according to the power supplied to the load 120.

[0022] The control characteristics of the output voltage-output current shown in FIG. 2 are called droop characteristics, and a DC power supply having such control characteristics is called a CVCC (Constant Voltage Constant Current) power supply. In the present embodiment, for each of the DC power supply devices 10(1) to 10(N), the values of the reference voltage Vr and the upper limit current Icc in the CVCC control can be variably set.

[0023] For example, in the present embodiment, the initial value of the reference voltage Vr in the CVCC control in the DC power supply devices 10(1) to 10(N) can be commonly set among the DC power supply devices 10(1) to 10(N) to be equal to the rated voltage Vrx of the load 120. On the other hand, in each of the DC power supply devices 10(1) to 10(N), the output voltage Vo in the CV mode with respect to the reference voltage Vr may actually have different values within the tolerance (Vr±Z(%)) due to the occurrence of an offset caused by manufacturing variations or the like.

[0024] For example, inside each of the DC power supply devices 10(1) to 10(N), an analog constant voltage (bias voltage) corresponding to the reference voltage Vr is generated and used for feedback control in the CV mode, but there are variations in the setting of the bias voltage. Also, it is common to use a voltage divider circuit during feedback control, but variations also occur in the voltage division ratio at this time. Due to these reasons, variations will occur among the output voltages Vo of the DC power supply devices 10(1) to 10(N) with respect to the equally set reference voltage Vr. As a result, the actual output characteristics of each DC power supply device 10 may be such that the characteristic line shown in FIG. 2 is shifted upward or downward according to the difference (offset) between the actual output voltage Vo and the reference voltage Vr.

[0025] However, if the output voltage Vo deviates from the above tolerance (±Z(%)), the DC power supply device is removed by product testing. Therefore, if the tolerance Z(%) is equal to or less than the margin X(%) (Z≤X), the actual output voltage Vo of the DC power supply devices 10A to 10E falls within the voltage tolerance range (±X(%)) of the above-described load 120. As a result, in the DC power supply system according to the present embodiment, even if the output voltages Vo differ between at least some of the DC power supply devices 10(1) to 10(N) connected in parallel, the output voltage Vout to the load 120 is understood to be within the voltage tolerance range of Vrx±X(%).

[0026] In a general CVCC power supply, the upper limit current Icc for shifting from the CV mode to the CC mode is set to about 120% to 140% with respect to the rated current value, and each component of the power supply is designed so that operation at the rated current value satisfies the assumed design life. That is, in a normal CVCC power supply, the design life of operation at the current value (upper limit current Icc) at which constant current control is performed by the droop characteristic is not necessarily guaranteed. This is because operation at this current value is operation in a region exceeding the rated current value.

[0027] On the other hand, in each of the DC power supply devices 10(1) to 10(N) according to the present embodiment, the upper limit current Icc at which constant current control is performed is set to be equal to or smaller than the rated current value. That is, in the DC power supply devices 10(1) to 10(N), each component is designed so that the design life is satisfied even in operation at the current value at which constant current control is performed by the droop characteristic.

[0028] Next, an embodiment with specific numerical examples of the number of DC power supplies connected in parallel, as well as the output voltage and output current, will be described. Hereinafter, an example with N = 5 will mainly be described.

[0029] FIG. 3 is a block diagram for explaining the configuration of the DC power supply system according to Embodiment 1. Referring to FIG. 3, the DC power supply system 100a according to the present embodiment includes at least five (N = 5) DC power supply devices 10A to 10E whose output sides are connected in parallel. The rated values (rated voltages) of the output voltages of the DC power supply devices 10A to 10D, and the rated value of the voltage supplied to the load 120 (i.e., the standard voltage Vrx) are 15 (V). The load 120 corresponds to the "load", and the output voltage Vout and output current Iout from the DC power supply system 100a to the load 120 respectively correspond to the "DC voltage" and "DC current" supplied to the "load".

[0030] In each of the DC power supply devices 10A to 10E, it is controlled to the upper limit current Icc = 100 (A) in FIG. 2, and a constant current is output in the droop characteristic (CC mode) with the output current being 100 (A).

[0031] Here, it is assumed that the load 120 can tolerate a power supply voltage fluctuation of ±5 (%) with respect to the standard voltage Vrx = 15 (V) (X = 5 (%)). That is, the voltage tolerance range of the output voltage Vout from the DC power supply system 100a to the load 120 is 15 (V) ±5% (14.25 to 15.75 (V)). Also, the maximum load current Imax = 480 (A), and the output current Iout from the DC power supply system 100a to the load 120 is assumed to change from 20 (A) to 480 (A).

[0032] Since Imax of the load 120 is 480 (A), five DC power supply devices 10A to 10E with Icc = 100 (A) are provided in parallel. That is, by the parallel operation of the DC power supply devices 10A to 10E because the sum of the upper limit currents Icc of the DC power supply devices 10A to 10E is larger than the maximum load current Imax, the maximum current 480 (A) of the load 120 can be supplied.

[0033] The reference voltage Vr of the DC power supply devices 10A to 10E is set to the same value as the rated voltage Vrx of the load 120, that is, 15 (V). On the other hand, although the actual output voltage Vo of the DC power supply devices 10A to 10E may be different values within the tolerance (Vr ± Z (%)), as described above, by satisfying Z ≤ 5 (%), it is understood that the actual output voltage Vo of the DC power supply devices 10A to 10E falls within the voltage tolerance range of 15 (V) ± 5 (%).

[0034] In FIG. 3, as an example, in the DC power supply device 10A, Vo = 15 + 0.17 = 15.17 (V), and in the DC power supply device 10B, Vo = 15 + 0.08 = 15.08 (V). Also, in the DC power supply device 10C, Vo = 15 + 0.05 = 15.05 (V). Furthermore, in the DC power supply device 10D, Vo = 15 - 0.03 = 14.97 (V), and in the DC power supply device 10E, Vo = 15 - 0.18 = 14.82 (V). That is, in FIG. 4, a case where the output voltages Vo of the DC power supply devices 10A to 10E with respect to the equivalently set reference voltage Vr are all different is illustrated. Here, for the sake of easy understanding, an example in which the difference in the output voltage Vo between the DC power supply devices 10A to 10E is set to a relatively large value is described, but in reality, the above-mentioned tolerance Z is generally smaller than 1 (%).

[0035] FIG. 4 shows a conceptual diagram and charts for explaining the operation of the DC power supply system 100a.

[0036] On the horizontal axis of FIG. 4(a), the output current Iout (i.e., the load current) from the DC power supply system 100a to the load 120 is shown, and on the vertical axis, the output voltage Vout from the DC power supply system 100a to the load 120 is shown. Due to the droop characteristics of the DC power supply devices 10A to 10E which are CVCC power supplies, the operating state of the DC power supply devices 10A to 10E changes between the current regions IRa to IRe of the output current Iout, causing the output voltage Vout to change.

[0037] FIG. 4(b) shows a chart for explaining the operating state of the DC power supply devices 10A to 10E for each region of the output current Iout.

[0038] Referring to FIGS. 4(a) and 4(b), in the current range IRa where the output current Iout is 0 to 100 A, only the DC power supply device 10A with the highest output voltage Vo (Vo = 15.17 V) outputs current, while the remaining DC power supply devices 10B to 10E with an output voltage Vo lower than 15.07 V do not supply current. Therefore, the output voltage Vout of the DC power system 100a becomes 15.17 V, and the output of the DC power supply device 10A is within the range from 0% to 100% (output current = Icc = 100 A).

[0039] On the other hand, although the DC power supply devices 10B to 10E are operating, their outputs are 0% (output current = 0 A). Hereinafter, for each of the DC power supply devices 10A to 10E, the operating state in which current is being supplied is referred to as the "operating state", and the operating state in which current is not being supplied (output is 0 (%)) is also referred to as the "non-operating state". In the current range IRa, the DC power supply device 10A is in the operating state, while the DC power supply devices 10B to 10E are in the non-operating state.

[0040] Next, when the output current Iout reaches 100 A, according to the droop characteristic (Icc = 100 A) shown in FIG. 2, the output voltage of the DC power supply device 10A decreases. When the output voltage drops to 15.08 V, current supply also starts from the DC power supply device 10B with an output voltage Vo of 15.08 V. As a result, the DC power supply device 10A operates in the constant current (CC) mode, while the DC power supply device 10B operates in the constant voltage (CV) mode (Vo = 15.08 V) and supplies the insufficient current within the range of 0% to 100% (100 A) of the output. This operating state continues until the output voltage Vo of the DC power supply device 10B decreases due to the droop characteristic, that is, until Iout = 100 × 2 = 200 A.

[0041] Therefore, in the current range IRb where Iout = 100 to 200 (A), the output voltage Vout of the DC power supply system 100a is 15.08 (V). And when the output of the DC power supply device 10A operating in the constant current (CC) mode reaches 100% (100 (A)), the output of the DC power supply device 10B (Vo = 15.08 (V)) operating in the constant voltage (CV) mode is within the range from 0% to 100% (100 (A)). On the other hand, no current is supplied from the DC power supply devices 10C to 10E whose output voltage Vo is lower than 15.08 (V), and they remain in the non-operating state, so the output is 0 (%).

[0042] Similarly, when the output current Iout reaches 200 (A), the output voltage of the DC power supply device 10B decreases according to the droop characteristic, and the current supply from the DC power supply device 10C with Vo = 15.05 (V) is started. In the current range IRc where Iout = 200 to 300 (A) until the output voltage of the DC power supply device 10C decreases due to the droop characteristic, the output voltage Vout of the DC power supply system 100a is 15.05 (V). Furthermore, when the outputs of the DC power supply devices 10A and 10B operating in the constant current (CC) mode reach 100% (100 (A)), the output of the DC power supply device 10C (Vo = 15.05 (V)) operating in the constant voltage (CV) mode is within the range from 0% to 100% (100 (A)). On the other hand, no current is supplied from the DC power supply devices 10D to 10E whose output voltage Vo is lower than 15.05 (V), and they remain in the non-operating state.

[0043] Similarly, in response to an increase in the output current Iout, in the current region IRd (Iout = 300 to 400 (A)), current supply from the DC power supply device 10D with Vo = 14.97 (V) is further started. Therefore, the output voltage Vout of the DC power supply system 100a becomes 14.97 (V). Furthermore, while the outputs of the DC power supply devices 10A to 10C operating in the constant current (CC) mode reach 100% (100 (A)), the output of the DC power supply device 10D (Vo = 14.97 (V)) operating in the constant voltage (CV) mode is within the range from 0% to 100% (100 (A)). On the other hand, no current is supplied from the DC power supply device 10E whose output voltage Vo is lower than 14.97 (V), and it remains in the non-operating state, so the output is 0 (%).

[0044] In the current region IRe (Iout = 400 to 500 (A)) where the output current Iout further increases, current supply from the DC power supply device 10E with Vo = 14.82 (V) is further started. Therefore, the output voltage Vout of the DC power supply system 100a becomes 14.82 (V). Furthermore, while the outputs of the DC power supply devices 10A to 10D operating in the constant current (CC) mode reach 100% (100 (A)), the output of the DC power supply device 10E (Vo = 14.82 (V)) operating in the constant voltage (CV) mode is within the range from 0% to 100% (100 (A)). That is, all of the DC power supply devices 10A to 10E are in the operating state.

[0045] By controlling such an operating state, within the range where the decrease in the output voltage Vout is within 5% from the standard value of 15 (V), the parallel operation of the DC power supply devices 10A to 10E can supply the maximum load current Imax = 480 (A) of the load 120.

[0046] As described above, in the DC power supply system shown in FIG. 3, among the plurality of DC power supply devices 10A to 10E connected in parallel, without the need to exchange control signals or information with each other, by simply connecting the output sides in parallel, multi-parallel operation following the change in the output current Iout to the load 120 becomes possible. Further, each of the DC power supply devices 10A to 10E is constantly in operation even when not outputting current depending on the voltage level, so it can promptly respond to an increase in the load current. Thereby, a DC power supply system having sufficient instantaneous current supply capacity can be configured with respect to fluctuations in voltage or current at the load 120.

[0047] Furthermore, as shown in FIG. 3, in a configuration where a large number of DC power supply devices are connected in parallel, the capacity of each DC power supply device can be reduced. Generally, since magnetic components increase in size in proportion to the current, the parallel connection configuration in the present embodiment enables the total size to be reduced, enabling a small-sized device design with good space efficiency.

[0048] Due to the miniaturization, each component can be further increased in frequency due to the skin effect and proximity effect. If the frequency can be increased, the components can be further miniaturized. In particular, small components have more stable quality due to the mass production effect compared to large components, and also tend to have excellent availability. Furthermore, the characteristics of magnetic components, especially ferrites, tend to be superior in small components. Thus, by reducing the capacity of each DC power supply device, a great effect can also be obtained in manufacturing.

[0049] Furthermore, if the configuration is such that DC power supply devices of the same specification are connected in parallel, the design of the DC power supply devices can be made common, so that the design efficiency and the cost merit due to an increase in the production quantity by commonization can be enjoyed. Also, when it is desired to increase the supply power to the load 120, it can be dealt with by additionally connecting DC power supply devices of the same specification in parallel and programming the reference voltage Vr to a desired value, so that the response to an increase in capacity can also be made more efficient.

[0050] However, in the DC power supply system 100a shown in FIG. 3, when a plurality of DC power supply devices 10A to 10E connected in parallel are operated without coordinated operation, the output voltage may become high or low due to individual differences as described with reference to FIG. 4. As a result, current is intensively supplied from the DC power supply device with the highest output voltage (DC power supply device 10A in FIG. 4), and there is a concern that the probability of failure increases due to the progress of component deterioration in the DC power supply device. In particular, it is common for the progress of deterioration of the smoothing capacitor to cause a failure.

[0051] Therefore, a configuration example of the DC power supply device, its operation example, and the detection of capacitor deterioration will be described below.

[0052] FIG. 5 is a block diagram showing a configuration example of the DC power supply device 10. FIG. 5 shows an example in which the DC power supply device 10 is configured by a non-insulated step-down chopper. The DC power supply device 10 comprehensively represents the DC power supply devices 10A to 10E. Note that the configuration example in FIG. 5 is merely an example, and any configuration can be adopted as long as it has a DC / DC conversion function and incorporates a smoothing capacitor.

[0053] Referring to FIG. 5, the DC power supply device 10 includes a semiconductor switching element 130, diodes 131 and 138, a reactor 132, a smoothing capacitor 133, a feedback (FB) circuit 135, a thermistor 140 for detecting the ambient temperature, a ripple voltage detection circuit 150, and a control IC (Integrated Circuit) 160. The control IC 160 can be configured by a microcomputer incorporating an electronic circuit, a processor, etc., and is configured to realize the control functions described below by a combination of hardware processing and software processing.

[0054] In the example of FIG. 5, the semiconductor switching element 130 is composed of a MOS (Metal Oxide Semiconductor)-FET (Field Effect Transistor) with a built-in body diode, but any semiconductor element that can be turned on and off by a control signal can be applied. The semiconductor switching element 130 and the diodes 131 and 138 can be fabricated using wide bandgap semiconductors such as GaN (gallium nitride) or SiC (silicon carbide) in addition to the commonly used Si (silicon)-based semiconductor materials.

[0055] The input voltage Vin from the power source 101 is applied between the input nodes Ni1 (+ side) and Ni2 (- side). The input node Nin2 is connected to a reference potential node Ns that supplies a reference potential (e.g., GND). The input node Ni is connected to the node N1 via the semiconductor switching element 130. A reactor 132 is connected between the nodes N1 and N2.

[0056] The diode 131 is connected between the reference potential node Ns and the node N1 with the direction from the reference potential node Ns to the node N1 as the forward direction. The smoothing capacitor 133 is connected between the node N2 and the reference potential node Ns.

[0057] The node N2 is connected to the output node No1 via a diode 138 for preventing the reverse flow of the output current. The output node No2 is connected to the reference potential node Ns. In the configuration example of FIG. 5, the input node Ni2 and the output node No2 are not electrically insulated and have the same potential (e.g., GND). The output nodes No1 and No2 correspond to the DC output terminals P (+) and N (-) in FIG. 1 and are connected in parallel to the power lines PL and NL (FIG. 1) to the load 120 with the output nodes No1 and No2 of another DC power supply device 10.

[0058] When the DC voltage Vo at node N2, which corresponds to the actual output voltage of the DC power supply device 10, is higher than the output voltage Vout to the load 120, a DC current Io is output to the load 120 via the diode 138 due to the discharge of the smoothing capacitor 133. On the other hand, when the DC voltage Vo is lower than the output voltage Vout, no DC current Io is generated (Io = 0).

[0059] During the on-period of the semiconductor switching element 130, a charging current for the smoothing capacitor 133 is generated by the input voltage Vin via the reactor 132. As a result, the DC voltage Vo of the DC power supply device 10 increases. On the other hand, during the off-period of the semiconductor switching element 130, a current path including the diode 131, the reactor 132, and the smoothing capacitor 133 is formed to circulate a current in the same direction as the on-period. During the off-period, the energy accumulated in the reactor 132 during the on-period is used to charge the smoothing capacitor 133 and supply the output current Io. When the energy supplied by the DC current Io from the DC power supply device 10 exceeds the energy accumulated in the reactor 132 during the on-period, the DC voltage Vo of the DC power supply device 10 decreases.

[0060] Therefore, it is understood that in the on / off control of the semiconductor switching element 130, the DC voltage Vo or the DC current Io can be controlled by adjusting the ratio of the on-period and the off-period.

[0061] The FB circuit 135 is composed of a voltage divider or a current detection resistor (not shown), etc., and outputs a voltage detection signal and a current detection signal (for example, an analog voltage signal) indicating the DC voltage Vo and the DC current Io at node N2 to the control IC 160. Thereby, the control IC 160 can acquire the DC voltage Vo and the DC current Io of the DC power supply device 10.

[0062] The control IC 160 outputs a gate signal, which is an on / off control signal for the semiconductor switching element 130, based on the feedback DC voltage Vo and DC current Io. The output of the DC power supply device 10 is controlled by the on-period ratio (on-duty ratio) of the semiconductor switching element 130 that is on / off controlled.

[0063] The reference voltage Vr and the upper limit current Icc described in FIG. 2 are programmed in the control IC 160. For example, the reference voltage Vr and the upper limit current Icc are set in the control IC 160 using a constant voltage generated by a bias circuit (not shown) provided inside the control IC 160, or by a plurality of bits of stored digital information. Further, the control IC 160 has a function of changing the reference voltage Vr inside the IC. For example, a configuration can be provided in which the reference voltage Vr in the DC power supply device 10 is set in a manner of adding a positive or negative correction amount calculated inside the IC to a default value defined by the above-described constant voltage or digital information.

[0064] That is, in the control IC 160, it is possible to program the reference voltage Vr at the start of operation of the DC power supply device 10, and it is also possible to change the reference voltage Vr during each operation of the DC power supply device 10.

[0065] In the constant voltage (CV) mode, the control IC 160 generates a gate signal for the semiconductor switching element 130 according to an on-duty ratio set so as to bring the DC voltage Vo detected by the FB circuit 135 closer to the reference voltage Vr.

[0066] On the other hand, in the constant current (CC) mode, the control IC 160 generates a gate signal for the semiconductor switching element 130 according to an on-duty ratio controlled to maintain the output current Io detected by the FB circuit 135 at the upper limit current Icc. Any known method can be applied to the on / off control of the semiconductor switching element in these CV mode and CC mode.

[0067] The control IC 160 can typically be constituted by a microcomputer having functions such as a PWM (Pulse Width Modulation) output function and an A / D (Analog / Digital) conversion function. Alternatively, the control IC 160 is not limited to a microcomputer, and can also be constituted by a circuit combining a dedicated IC and discrete IC components as long as equivalent functions can be realized.

[0068] In the DC power supply device 10, with the repeated on / off of the semiconductor switching element 130 for controlling the DC voltage Vo or the DC current Io, a ripple voltage, which is an AC voltage component, is generated across the terminals of the smoothing capacitor 133 (i.e., the DC voltage Vo). The ripple voltage has a frequency component that follows the switching frequency of the semiconductor switching element 130.

[0069] Typically, an electrolytic capacitor is used as the smoothing capacitor 133. The electrolytic capacitor deteriorates over time due to self-heating of the electrolytic capacitor generated by energization during the use of the DC power supply device 10 and heat received from the surroundings. A typical degradation symptom is an increase in ESR (Equivalent Series Resistance), which causes an increase in the ripple voltage. As long as the smoothing capacitor 133 has the characteristic that the DC resistance component (ESR) increases with the passage of time, components other than the electrolytic capacitor may be applied.

[0070] The ripple voltage detection circuit 150 extracts the AC voltage component (ripple voltage component) included in the DC voltage Vo at the node N2 and outputs a ripple voltage signal Vrp to the node N3. The ripple voltage detection circuit 150 corresponds to an embodiment of the "voltage detection circuit".

[0071] The thermistor 140 is arranged near the smoothing capacitor 133 and outputs a thermistor voltage signal Vtmp indicating the ambient temperature Ta, which is the ambient temperature around the smoothing capacitor 133. The thermistor 140 corresponds to an embodiment of the "temperature detector". If it is possible to detect the ambient temperature Ta, it is also possible to use a detector or sensor other than the thermistor as the "temperature detector".

[0072] FIG. 6 shows a circuit diagram for explaining a configuration example of the ripple voltage detection circuit 150. Referring to FIG. 6, the ripple voltage detection circuit 150 includes an AC component amplification unit 152 and a peak hold circuit 154. The AC component amplification unit 152 includes a capacitor C1, an operational amplifier 151, and resistor elements R1 to R3.

[0073] The capacitor C1 is connected between nodes N2 and N4, and the resistor element R1 is connected between node N4 and ground (VSS). By blocking the DC voltage component by the high-pass filter formed by the capacitor C1 and the resistor element R1, the AC voltage component of the DC voltage Vo at node N2 is transmitted to node N4. The RC values of the capacitor C1 and the resistor element R1 are determined so that the frequency component corresponding to the switching frequency of the semiconductor switching element 130 passes through the high-pass filter.

[0074] The resistor element R2 is connected between node N5, which is connected to the inverting input terminal (-) of the operational amplifier 151, and node N4. The resistor element R3 is connected between node N5 and node N6, which is connected to the output terminal of the operational amplifier 151. Since the non-inverting (+) input terminal of the operational amplifier 151 is connected to ground, an inverting amplifier circuit is formed by the operational amplifier 151 and the resistor elements R2 and R3. Therefore, an AC voltage signal in which the amplitude of the AC voltage component input to node N4 is amplified is generated at node N6.

[0075] The peak hold circuit 154 includes a diode 153, a capacitor C2, and resistor elements R4 and R5. The diode 153 and the resistor element R4 are connected in series between the node N6 and the node N3. The capacitor C2 and the resistor element R5 are connected in parallel between the node N3 and the ground.

[0076] The diode 153 conducts when the voltage at the node N6 is higher than the voltage at the node N3, and is non-conductive otherwise. Also, the voltage at the node N6 is held by the capacitor C2, and the resistor element R5 is connected to the capacitor C2 as a discharge resistor. As a result, it is understood that the ripple voltage signal Vrp generated at the node N3 becomes a voltage according to the maximum value of the amplitude of the AC voltage component input to the node N4. More specifically, the voltage value of the ripple voltage signal Vrp corresponds to the multiplication value of the maximum value of the amplitude of the ripple voltage included in the DC voltage Vo and the amplification factor of the inverting amplifier circuit by the operational amplifier 151. For example, if the amplitude of the ripple voltage is 50 (mV), by setting the amplification factor to about 10 times, the ripple voltage signal Vrp input to the control IC160 can be set to about 500 (mV).

[0077] In this way, the ripple voltage detection circuit 150 outputs a ripple voltage signal Vrp indicating the maximum value of the amplitude of the ripple voltage included in the DC voltage Vo to the node N3. The ripple voltage signal Vrp is input to the control IC160 together with the thermistor voltage signal Vtmp from the thermistor 140.

[0078] In the DC power supply system according to the first embodiment, in each DC power supply device 10, the control IC160 can detect an increase in the ripple voltage of the smoothing capacitor 133 based on the ripple voltage signal Vrp. As described above, since the smoothing capacitor 133 has the characteristic that the ESR increases with deterioration, when the maximum value of the ripple voltage (hereinafter also simply referred to as "ripple voltage") indicated by the ripple voltage signal Vrp exceeds a predetermined determination voltage, the progress of the deterioration of the smoothing capacitor 133 can be detected.

[0079] In the DC power supply system 100a shown in FIG. 3, since cooperative control is not executed among a plurality of DC power supply devices 10A to 10E connected in parallel, due to the difference in the DC voltage Vo among the DC power supply devices described with reference to FIG. 3, the operating time of some DC power supplies (in the example of FIG. 3, the DC power supply device 10A with the maximum Vo) becomes the maximum, so that the energization time of the smoothing capacitor 133 also becomes longer, and deterioration progresses.

[0080] On the other hand, the ESR of an electrolytic capacitor generally varies greatly depending on the ambient temperature. Therefore, the ripple voltage, which is in a proportional relationship with the magnitude of the ESR, is also affected by the ambient temperature. Assuming that 25 (°C) in a room temperature environment is the reference for the ESR value, in an environment where the ambient temperature is below 0 (°C), the value of the ESR may increase several times to more than ten times from the reference value. Therefore, in a low-temperature environment, if a determination is made based on the ripple voltage signal Vrp, there is a possibility of erroneously detecting an increase in the ripple voltage due to aging deterioration.

[0081] For this reason, as will be described in detail below, in the DC power supply system according to the present embodiment, after avoiding false detection in a low-temperature environment, in the DC power supply device 10 in which an increase in the ripple voltage is detected, control is executed to suppress the progress of deterioration of the smoothing capacitor 133 by reducing the DC voltage Vo.

[0082] FIG. 7 is a flowchart for explaining control processing for suppressing the progress of deterioration of a smoothing capacitor executed in each DC power supply device of the DC power supply system according to Embodiment 1. The control processing shown in FIG. 7 can be executed by the control IC 160 of each DC power supply device 10.

[0083] Referring to FIG. 7, when the operation of the DC power supply device 10 is started, the control IC 160 reads, by step S110, a reference value Vt of the ripple voltage (amplitude) of the DC power supply device 10. The reference value Vt is preset as part of the specification values for each model of the DC power supply device 10. As will be described later, a determination voltage for detecting an increase in the ripple voltage is set by a multiplication value (k·Vt) of a coefficient k (k: a real number greater than 1) that can be set for each DC power supply device 10 and the reference value Vt.

[0084] During the operation of the DC power supply device 10, the control IC 160 acquires, by step S120, the ambient temperature Ta detected by the thermistor 140, and in step S130, compares the ambient temperature Ta acquired in step S120 with a predetermined determination temperature Tjd. The determination temperature Tjd can be determined in consideration of the temperature characteristics of the ESR of the capacitor used as the smoothing capacitor 133. For example, when using a capacitor with characteristics such that the ESR increases significantly in an environment where the ambient temperature is below 0 (°C) as described above, it can be set to about Tjd = 10 (°C).

[0085] When the ambient temperature Ta is equal to or higher than the determination temperature Tjd (YES determination in S130), the control IC 160 acquires, by step S140, the ripple voltage of the smoothing capacitor 133 based on the ripple voltage signal Vrp from the ripple voltage detection circuit 150. Further, in step S150, the acquired ripple voltage (S140) is compared with the determination voltage (Vt·k).

[0086] When the ripple voltage is equal to or higher than the determination voltage (YES determination in S150), the control IC 160 detects, by step S160, that the deterioration of the smoothing capacitor 133 has advanced. Further, in step S170, the reference voltage Vr of the DC power supply device 10 is decreased. As a result, the DC voltage Vo of the DC power supply device 10 in which the deterioration of the smoothing capacitor 133 has advanced can be decreased. By suppressing the output of the DC current Io from the DC power supply device 10 to the load 120, the energization of the smoothing capacitor 133 can be suppressed, preventing further progression of the deterioration.

[0087] As a result, in a specific DC power supply device 10 where the output voltage (DC voltage Vo) becomes higher than that of other DC power supply devices 10 due to individual differences and the current output concentrates, it is possible to prevent the deterioration of the smoothing capacitor 133 from progressing intensively and leading to a failure. As a result, in a DC power supply system including a plurality of DC power supply devices connected in parallel, the life of the DC power supply system can be extended during a period when no failure has occurred in all the DC power supply devices.

[0088] In addition, in order to obtain the effect of reducing the output current (DC current Io), it is necessary that the reference voltage Vr after the reduction in step S170 is set lower than the reference voltage Vr of at least one other DC power supply device 10. For example, in step S170, the reference voltage Vr can be reduced to Vrx - (X - Z) (%) with respect to the lower limit value (Vrx - X (%)) of the voltage tolerance range of the output voltage Vout.

[0089] On the other hand, when the ripple voltage is lower than the determination voltage (when the determination in S150 is NO), the process returns to step S120 without executing steps S160 and S170. As a result, the monitoring of the ripple voltage by steps S120 to S150 can be periodically and repeatedly executed until it is detected that the ripple voltage becomes equal to or higher than the determination voltage.

[0090] Also, when the ambient temperature Ta is lower than the determination temperature Tjd (when the determination in S130 is NO), the process returns to step S120 without proceeding to step S140 and subsequent steps. Thereby, it is possible to prevent misdetection of the progress of deterioration of the smoothing capacitor 133 in response to an increase in the ripple voltage caused by an increase in the ESR due to a low-temperature environment.

[0091] Alternatively, it is also possible to obtain the ripple voltage so as to correct according to the ambient temperature Ta, reflecting the temperature dependence of the ESR.

[0092] FIG. 8 shows a conceptual diagram for explaining an example of setting a correction value for the ripple voltage according to the ambient temperature.

[0093] Referring to FIG. 8, in the region where the ambient temperature Ta ≥ T0 (for example, T0 = 10 (°C)), β = 0 (%) is set. On the other hand, in the region where Ta < T0, the correction value β (%) is set such that the absolute value increases as the temperature decreases, and the ripple voltage is corrected by the following formula (1). T0 corresponds to the "correction start temperature".

[0094] Vrp♯ = Vrpl·(1.0 + β / 100) …(1) In this case, the ripple voltage Vrpl based on the ripple voltage signal Vrp from the ripple voltage detection circuit 150 can be used to obtain the ripple voltage in step S140 using the corrected ripple voltage Vrp♯ in formula (1).

[0095] When performing the correction according to FIG. 8, in the range of Ta ≤ Tjd, it is possible not to execute the detection of the progress of deterioration based on the ripple voltage. Thus, in the range of Tjd < Ta < T0, according to the temperature characteristics of the ESR of the smoothing capacitor 133 shown in FIG. 8, the detected value in the ripple voltage detection circuit 150 can be corrected in the decreasing direction and compared with the determination voltage (k·Vt).

[0096] By performing such correction, the determination temperature Tjd can be set low, and the temperature range in which the progress of capacitor deterioration can be detected can be expanded. For example, in FIG. 8, when Tjd is set to about -20 (°C), and in the range of -20 (°C) to T0 (for example, 10 (°C)), the ripple voltage can be corrected using the correction value β (%) set to a negative value according to the ambient temperature Ta (°C). As a result, it becomes possible to lower the determination temperature Tjd from about 10 (°C) in the above example.

[0097] As described above, according to the DC power supply system according to Embodiment 1, it is possible to detect the progress of deterioration of the smoothing capacitor 133 from an increase in the ripple voltage while preventing false detection due to the temperature environment. Then, by reducing the output voltage (DC voltage Vo) of the DC power supply device 10 in which the progress of deterioration of the smoothing capacitor 133 is detected, it is possible to suppress the concentrated progress of deterioration of the smoothing capacitor 133 in a specific DC power supply device 10. As a result, it is possible to extend the life of the DC power supply system in which a plurality of DC power supply devices 10A to 10E connected in parallel operate without accompanying cooperative operation. Thereby, the maintainability of the system can be improved.

[0098] Further, detecting the progress of deterioration of the smoothing capacitor 133 from an increase in the ripple voltage (S160) can be output from the DC power supply system 100a as information for maintenance such as notifying that the replacement timing of the DC power supply device 10 is approaching.

[0099] Modification of Embodiment 1. In Embodiment 1, as shown in FIG. 3, an example in which the reference voltage Vr is set to be common (the same value) in a plurality of DC power supply devices 10A to 10E connected in parallel has been described. However, it is also possible to intentionally set the reference voltage Vr to different values between at least some of the DC power supply devices.

[0100] FIG. 9 is a block diagram for explaining the configuration of a DC power supply system 100b according to a modification of Embodiment 1.

[0101] Referring to FIG. 9, the DC power supply system 100b includes five DC power supply devices 10A to 10E whose output sides are connected in parallel, similarly to FIG. 3. The configuration of each of the DC power supply devices 10A to 10E is the same as that of Embodiment 1. For example, the configuration example of FIG. 5 can be applied. Therefore, in each of the control ICs 160 of the DC power supply devices 10A to 10E, it is possible to program different reference voltages Vr at the start of operation of each of the DC power supply devices 10A to 10E, and it is also possible to change the reference voltage Vr during the operation of each of the DC power supply devices 10A to 10E, similarly to Embodiment 1.

[0102] In the modification of Embodiment 1, the reference voltage Vr of the DC power supply devices 10A to 10E is set such that at least a part thereof becomes different values within the range of the maximum value Vrmax and the minimum value Vrmin. The maximum value Vrmax and the minimum value Vrmin can be determined so as not to deviate from the voltage tolerance range (Vrx ± X (%)) of the load 120 in consideration of the tolerance (Vr ± Z (%)) of the output voltage (DC voltage Vo) of each DC power supply device 10 described above.

[0103] In FIG. 9, an example will be described in which the reference voltages Vr of the DC power supply devices 10A to 10E are set to different values, for example, at intervals of 0.05 (V). Specifically, in the DC power supply device 10A, Vr = 15 + 0.10 = 15.10 (V), and in the DC power supply device 10B, Vr = 15 + 0.05 = 15.05 (V). Also, in the DC power supply device 10C, Vr = 15 + 0.00 = 15 (V). Further, in the DC power supply device 10D, Vr = 15 - 0.05 = 14.95 (V), and in the DC power supply device 10E, Vr = 15 - 0.10 = 14.90 (V).

[0104] In the example of FIG. 9, in the DC power supply devices 10A and 10E where Vrmax = 15.10 (V) and Vrmin = 14.90 (V) are determined, even if an offset occurs in the output (DC voltage Vo) within the tolerance (± Z (%)) of each DC power supply device 10, 15 (V) ± X (%) (here, X = 5 (%)) is ensured. In the modification of Embodiment 1, for the sake of simplicity of explanation, the output voltages (DC voltages Vo) of the DC power supply devices 10A to 10E are described as being equal to their respective reference voltages Vr.

[0105] FIG. 10 shows a conceptual diagram and a chart for explaining the operation of each DC power supply device in the DC power supply system 100b. Similar to FIG. 4(a), on the horizontal axis of FIG. 10(a), the output current Iout (that is, the load current) from the DC power supply system 100b to the load 120 is shown, and on the vertical axis, the output voltage Vout from the DC power supply system 100b to the load 120 is shown.

[0106] Also in the DC power supply system 100b, due to the droop characteristics of the DC power supply devices 10A to 10E which are CVCC power supplies, within the current regions IRa to IRe of the output current Iout, as the operating states of the DC power supply devices 10A to 10E change, the output voltage Vout changes.

[0107] Fig. 10(b) shows a chart explaining the operating states of the DC power supply devices 10A to 10E for each region of the output current Iout.

[0108] Referring to Fig. 10(a) and Fig. 10(b), the current regions IRa to IRe are defined in the same manner as in Fig. 4(a) and Fig. 4(b). In the current region IRa, only the DC power supply device 10A (Vr = 15.10 (V)) with the highest reference voltage Vr is in the operating state, while the remaining DC power supply devices 10B to 10E are in the non-operating state. As a result, the output voltage Vout of the DC power supply system 100a becomes 15.10 (V), and the output of the DC power supply device 10A is within the range from 0% to 100% (output current = Icc = 100 (A)).

[0109] In the current region IRb where Iout = 100 to 200 (A), according to the droop characteristic (Icc = 100 (A)), the output voltage of the DC power supply device 10A decreases, while the output of the DC power supply device 10B (Vr = 15.05 (V)) is within the range from 0% to 100% (100 (A)). On the other hand, the DC power supply devices 10C to 10E with a reference voltage Vr lower than 15.05 (V) remain in the non-operating state and the output is 0 (%). As a result, the output voltage Vout of the DC power supply system 100a becomes 15.05 (V). This operating state continues until the output voltage of the DC power supply device 10B decreases due to the droop characteristic, that is, until Iout = 100×2 = 200 (A).

[0110] In the current range IRc where Iout = 200 to 300 (A), as the output voltage of the DC power supply device 10B decreases according to the droop characteristic, the current supply from the DC power supply device 10C with Vr = 15.00 (V) is started. Thereby, the current is supplied to the load 120 by the DC power supply devices 10A and 10B operating in the constant current (CC) mode and the DC power supply device 10C operating in the constant voltage (CV) mode. On the other hand, the DC power supply devices 10D and 10E with the reference voltage Vr lower than 15.00 (V) remain in the non-operating state and the output is 0 (%). As a result, the output voltage Vout of the DC power supply system 100b becomes 15.00 (V). This operating state continues until the output voltage of the DC power supply device 10B decreases due to the droop characteristic, that is, until Iout = 100 × 3 = 300 (A).

[0111] Similarly, in the current range IRd (Iout = 300 to 400 (A)) where the output current Iout further increases, the current supply from the DC power supply device 10D with Vr = 14.95 (V) operating in the constant voltage (CV) mode is further started. Therefore, the output voltage Vout of the DC power supply system 100b becomes 14.95 (V). Further, the outputs of the DC power supply devices 10A to 10C operating in the constant current (CC) mode become 100% (100 (A)), and the output of the DC power supply device 10D (Vr = 14.95 (V)) operating in the constant voltage (CV) mode is in the range from 0% to 100% (100 (A)). On the other hand, no current is supplied from the DC power supply device 10E with the reference voltage Vr lower than 14.95 (V), and it remains in the non-operating state, so the output is 0 (%).

[0112] Furthermore, in the current region IRe where the output current Iout increases further (Iout = 400 to 500 (A)), current supply from the DC power supply device 10E with Vr = 14.90 (V) is further started. Therefore, the output voltage Vout of the DC power supply system 100b becomes 14.90 (V). Furthermore, when the outputs of the DC power supply devices 10A to 10D operating in the constant current (CC) mode reach 100% (100 (A)), the output of the DC power supply device 10E (Vr = 14.90 (V)) operating in the constant voltage (CV) mode is within the range from 0% to 100% (100 (A)). That is, all of the DC power supply devices 10A to 10E are in the operating state.

[0113] Thus, also in the DC power supply system 100b according to the modification of Embodiment 1, similar to the DC power supply system 100a according to Embodiment 1, among the plurality of DC power supply devices 10A to 10E connected in parallel, without the need to exchange control signals or information with each other, just by connecting the output sides in parallel, multi-parallel operation following the change in the output current Iout to the load 120 becomes possible. Thereby, the same effects as those of the DC power supply system 100a described in Embodiment 1 can be enjoyed.

[0114] Also, in the modification of Embodiment 1, based on the reference voltages Vr (default values) of the DC power supply devices 10A to 10E in the "initial state" where no increase in the ripple voltage is detected in any of the DC power supply devices 10 set at the start of operation of the DC power supply system 100b, it becomes possible to intentionally determine the priority order of the operating states among the DC power supply devices 10A to 10E.

[0115] Also in the DC power supply system 100b according to Embodiment 1, each DC power supply device 10 has a function of detecting deterioration of the capacitor based on detection of an increase in the ripple voltage, as exemplified in FIG. 6. Therefore, the controls shown in FIGS. 7 and 8 described in Embodiment 1 can be executed.

[0116] In addition, in the modification of Embodiment 1, when an increase in the ripple voltage is detected (i.e., when step S150 in FIG. 7 is determined to be YES) using the reference voltage Vr (default value) of each of the DC power supply devices 10A to 10E at the start of operation of the DC power supply system 100b, that is, the reference voltage Vr (after decrease) in step S170 of FIG. 7 can be set more appropriately.

[0117] For example, in step S170 of FIG. 7, in the DC power supply device 10 in which an increase in the ripple voltage is detected, the reference voltage Vr can be decreased according to an integer multiple of the step width ΔVr of the reference voltage Vr (in the example of FIG. 9, ΔVr = 0.05 (V)) so as to be set lower than at least the reference voltage Vr of any one of the other DC power supply devices 10. Thereby, the progress of deterioration of the smoothing capacitor in the DC power supply device 10 can be suppressed.

[0118] Preferably, in order to minimize the priority (operating state) of the DC power supply device 10 in which an increase in the ripple voltage is detected, in step S170, the reference voltage Vr of the DC power supply device 10 can be set to a voltage lower than the lowest voltage Vrmin in the initial state (before detection of an increase in the ripple voltage) (for example, Vrx - (X - Z) (%) < Vr < Vrmin).

[0119] Thus, also in the DC power supply system according to the modification of Embodiment 1, similar to the DC power supply system according to Embodiment 1, concentrated progress of deterioration of the smoothing capacitor 133 in a specific DC power supply device 10 can be suppressed. Thereby, without involving cooperative operation, the life of the DC power supply system in which a plurality of DC power supply devices 10A to 10E connected in parallel operate can be extended.

[0120] Further, in the DC power supply system according to the modification of Embodiment 1, by setting the default reference voltage Vr before an increase in the ripple voltage is detected (initial state) to different values among the plurality of DC power supply devices 10, it is also possible to specify in advance the DC power supply device in which the operating time becomes long. Thereby, it can be expected that the formulation of a maintenance plan for maintenance can be made more efficient.

[0121] Also, during the continuous operation of the DC power supply system 100b, it is also possible to equalize the operating time of each DC power supply device 10 by switching the high-low relationship of the reference voltage Vr among the plurality of DC power supply devices 10 midway.

[0122] Embodiment 2. In Embodiment 2, a redundant design in which an extra number of DC power supply devices are connected in parallel with respect to the maximum current of the load 120 will be described.

[0123] FIG. 11 is a block diagram for explaining the configuration of a DC power supply system 100c according to Embodiment 2.

[0124] As shown in FIG. 11, the DC power supply system 100c is different in that, in addition to the configuration of the DC power supply system 100a (FIG. 3) according to Embodiment 1, it further includes a DC power supply device 10F. The output side of the DC power supply device 10F is connected in parallel with the output sides of the DC power supply devices 10A to 10E.

[0125] In the DC power supply system 100c, the upper limit current Icc of each of the DC power supply devices 10A to 10F is set to 100 (A). Therefore, in the DC power supply system 100g, a total of six DC power supply devices 10A to 10F are connected in parallel, one more than the number (N = 5) required to ensure Imax = 480 (A), and power is supplied to the load 120.

[0126] That is, in the DC power supply system 100c, the number of DC power supply devices connected in parallel is determined such that the sum of the upper limit currents Icc of only some of the DC power supply devices is greater than the maximum load current Imax of the load 120. In FIG. 11, a configuration in which the extra number is one is shown as a preferred example.

[0127] It is assumed that the actual output voltage Vo of the DC power supply devices 10A to 10E is the same as in Embodiment 1. The reference voltage Vr of the DC power supply device 10F redundantly arranged is set to be equal to the reference voltage Vr of the DC power supply devices 10A to 10E (Vr = 15 (V)). The output voltage Vo of the DC power supply device 10F does not necessarily match the reference voltage Vr (15 (V)), but is within the range of 15 (V) ± X (%). Since the configuration of the other parts of the DC power supply system 100c is the same as in Embodiment 1 (FIG. 3) including the power source 101 and the load 120, detailed description will not be repeated.

[0128] FIG. 12 is a diagram for explaining the operation of each DC power supply device in the DC power supply system 100c. In FIG. 12, an operation example is shown when the output voltage Vo of the DC power supply device 10F is lower than any of the DC power supply devices 10A to 10E (i.e., Vo < 14.82 (V)).

[0129] FIG. 12(a) shows the operation of each DC power supply device when no failure has occurred in any of the DC power supply devices 10A to 10F. In this case, the output current Iout is supplied by the five DC power supply devices with the higher output voltage (here, the DC power supply devices 10A to 10E). As a result, similar to FIG. 4(b), the operation states of each DC power supply device 10A to 10E in each current region of the output current Iout, and the output voltage Vout to the load 120 are determined.

[0130] In the state of FIG. 12(a), the redundant DC power supply device 10F is in a non-operating state with an output of 0% even in the current region where the output current Iout is 400 to 500 (A). Even when the maximum current 480 (A) of the load 120 is supplied, the output current Iout can be ensured by the DC power supply devices 10A to 10E. Therefore, the output voltage Vout becomes the lowest 14.82 (V) among the output voltages Vo of the DC power supply devices 10A to 10E, while the output voltage Vo of the DC power supply device 10F is lower than that. In other words, the one with the lowest actual output voltage Vo among the plurality of parallel-connected DC power supply devices 10A to 10F is automatically set to be in a non-operating state as a redundancy at all times.

[0131] Fig. 12(b) shows the operation when a failure occurs in any one of the DC power supply devices 10A to 10E, here, the DC power supply device 10C.

[0132] As shown in Fig. 12(b), the output of the failed DC power supply device 10C (Vr = 15.00 (V)) becomes 0% in the entire current range. Also, the operations of the DC power supply devices 10A and 10B whose reference voltage Vr is higher than that of the DC power supply device 10C do not change from Fig. 12(a).

[0133] On the other hand, the DC power supply device 10D (Vo = 14.97 (V)) whose output voltage Vo is next higher than that of the DC power supply device 10C starts to operate in the same manner as the DC power supply device 10C. That is, the output of the DC power supply device 10D in each current range in Fig. 12(b) becomes equal to the output of the DC power supply device 10C in Fig. 12(a). Similarly, the output of the DC power supply device 10E (Vo = 14.90 (V)) in Fig. 12(b) becomes equal to the output of the DC power supply device 10D in Fig. 12(a). That is, the DC power supply device 10E starts to operate in the same manner as the DC power supply device 10D.

[0134] Furthermore, the DC power supply device 10F which was in the non-operating state (output is 0 (%)) in Fig. 12(a) starts to operate in the same manner as the DC power supply device 10E in Fig. 12(a) in the current range (400 to 500 (A)) where the DC power supply device 10E in Fig. 12(a) outputs current in the range of 0 to 100%.

[0135] As a result, for each current range similar to Fig. 12(a), the output current Iout can be ensured by the five DC power supply devices 10A, 10B, 10D to 10F. Note that in Fig. 12(b), in the current range where the DC power supply device 10C outputs current, that is, in each current range where Iout ≥ 200 (A), the output voltage Vout will be lower than that in Fig. 12(a). However, as described above, even for the DC power supply device 10F with the lowest output voltage Vo, those whose output voltage Vo is within the voltage tolerance range (±X (%)) of the load 120 are used as a result of the product test.

[0136] Therefore, even in the state of FIG. 12(b) where the DC power supply device 10C has failed, the load 120 can be supplied with an output current Iout up to Imax = 480 (A) by the output voltage Vout within the voltage tolerance range of the load 120. That is, it is understood that a redundant design for coping with the failure of any DC power supply device is realized.

[0137] Thus, in the DC power supply system according to the second embodiment, a redundant design can be realized simply by increasing the number of DC power supply devices connected in parallel by one with respect to the number required to supply the maximum load current Imax to the load 120. The redundant design of a general power supply system is realized by arranging two power supply devices with a rated current capable of corresponding to the maximum current of the load in parallel. In contrast, according to the present embodiment, for M DC power supply devices for sharing and supplying the maximum current, a redundant design can be realized simply by additionally connecting one more (M + 1) DC power supply devices.

[0138] As a result, compared with the above-described general power supply system, the cost for the redundant configuration can be suppressed. For example, in a general redundant design, twice the number of power supply devices is required, while in the present embodiment, only (M + 1) / M times the number is sufficient, so cost reduction is possible. Thereby, miniaturization of the device (system) can also be realized.

[0139] Also, in the second embodiment as well, each DC power supply device 10 has a function of detecting deterioration of the capacitor based on detection of an increase in the ripple voltage, as illustrated in FIGS. 5 and 6, as described in the first embodiment. Therefore, the control shown in FIGS. 7 and 8 described in the first embodiment can be executed.

[0140] Accordingly, when an increase in the ripple voltage is detected (i.e., when step S150 in FIG. 7 is determined to be YES), in step S170 of FIG. 7, the reference voltage Vr is decreased in the same manner as in the first embodiment, so that the DC power supply device 10 (for example, the DC power supply device 10C in FIG. 12(b)) can be protected to be fixed in a non-operating state before reaching a complete failure. Thereby, it can be expected to further extend the life of the DC power supply system.

[0141] Modification example of the second embodiment. The redundant design described in the second embodiment can also be applied to the modification example of the first embodiment.

[0142] FIG. 13 is a block diagram for explaining the configuration of a DC power supply system 100d according to a modification example of the second embodiment.

[0143] As shown in FIG. 13, the DC power supply system 100d is different in that, in addition to the configuration of the DC power supply system 100b (FIG. 9) according to the modification example of the first embodiment, it further includes a DC power supply device 10F. The output side of the DC power supply device 10F is connected in parallel with the output sides of the DC power supply devices 10A to 10E.

[0144] Also in the DC power supply system 100d, the upper limit current Icc of each of the DC power supply devices 10A to 10F is set to 100 (A). Therefore, in the DC power supply system 100g, a total of six DC power supply devices 10A to 10F are connected in parallel, one more than the number (N = 5) required to ensure Imax = 480 (A), to supply power to the load 120.

[0145] That is, also in the DC power supply system 100d, similar to the DC power supply system 100c (FIG. 9), the number of DC power supply devices connected in parallel is determined such that the sum of the upper limit currents Icc of only some of the DC power supply devices is greater than the maximum load current Imax of the load 120. Also in FIG. 13, similar to FIG. 9, a configuration in which the extra number is one is shown as a preferred example.

[0146] The reference voltages Vr of the DC power supplies 10A to 10E are set stepwise to different values, similar to the modification of Embodiment 1. The reference voltage Vr of the redundantly arranged extra DC power supply 10F is set to a value lower than the reference voltages Vr of the DC power supplies 10A to 10E. In the example of Fig. 13, it is set to Vr = 15 - 0.15 = 14.85 (V). However, also for the reference voltage Vr of the DC power supply 10F, considering the tolerance (Vr ± Z (%)) of the DC voltage Vo of each DC power supply 10, the DC voltage Vo output by the DC power supply 10F can be determined so as not to exceed the lower limit value (Vrx - X (%)) of the voltage tolerance range of the load 120. In the modification of Embodiment 2 as well, similar to the modification of Embodiment 1, the output voltages (DC voltages Vo) of the DC power supplies 10A to 10E will be described as being equal to their respective reference voltages Vr.

[0147] The configuration of the other parts of the DC power system 100d, including the power source 101 and the load 120, is the same as that of the modification of Embodiment 1 (Fig. 9), so detailed description will not be repeated.

[0148] Fig. 14 shows a chart for explaining the operation of each DC power supply in the DC power system 100d.

[0149] Fig. 14(a) shows the operation of each DC power supply when no failure has occurred in any of the DC power supplies 10A to 10F. In this case, the output current Iout is supplied by the five DC power supplies 10A to 10E with the higher reference voltages Vr. As a result, similar to Fig. 10(b), the operating states of each DC power supply 10A to 10E in each current region of the output current Iout and the output voltage Vout to the load 120 are determined.

[0150] In the state of Fig. 14(a), the redundant DC power supply device 10F is in a non-operating state with an output of 0% even in a current range where the output current Iout is 400 to 500 (A). Even when the maximum current of 480 (A) of the load 120 is supplied, the output current Iout can be ensured by the DC power supply devices 10A to 10E. Therefore, the output voltage Vout becomes 14.90 (V), which is the lowest among the reference voltages Vr of the DC power supply devices 10A to 10E, while the reference voltage Vr of the DC power supply device 10F is lower than that. In other words, one of the plurality of DC power supply devices 10A to 10F connected in parallel, that is, the one with the lowest reference voltage Vr, i.e., the one with the reference voltage Vr being the minimum voltage Vrmin, will automatically be in a non-operating state as a redundant device at all times.

[0151] Fig. 14(b) shows the operation when a failure occurs in any one of the DC power supply devices 10A to 10E, here, the DC power supply device 10C.

[0152] As shown in Fig. 14(b), the output of the failed DC power supply device 10C (Vr = 15.00 (V)) becomes 0% in the entire current range. Also, the operations of the DC power supply devices 10A and 10B, whose reference voltages Vr are higher than that of the DC power supply device 10C, do not change from Fig. 14(a).

[0153] On the other hand, the DC power supply device 10D (Vr = 14.95 (V)), whose reference voltage Vr is next higher than that of the DC power supply device 10C, will operate in the same way as the DC power supply device 10C. That is, the output of the DC power supply device 10D in each current range in Fig. 14(b) will be the same as the output of the DC power supply device 10C in Fig. 14(a). Similarly, the output of the DC power supply device 10E (Vr = 14.90 (V)) in Fig. 14(b) will be the same as the output of the DC power supply device 10D in Fig. 14(a). That is, the DC power supply device 10E will operate in the same way as the DC power supply device 10D.

[0154] Furthermore, in FIG. 14(a), the DC power supply device 10F, which was in the non-operating state (output is 0 (%)), operates in the same manner as the DC power supply device 10E in FIG. 14(a) in the current range (400 to 500 (A)) where the DC power supply device 10E was outputting current in the range of 0 to 100%.

[0155] As a result, for each current range similar to that in FIG. 14(a), the output current Iout can be ensured by the five DC power supply devices 10A, 10B, 10D to 10F. In FIG. 14(b), in the current ranges where the DC power supply device 10C was outputting current, that is, in each current range where Iout ≥ 200 (A), the output voltage Vout will be lower than that in FIG. 14(a). However, as described above, even in the DC power supply device 10F where the reference voltage Vr is the lowest, the reference voltage Vr is set such that the output voltage Vo of each DC power supply device 10 is within the voltage tolerance range (±5%) of the load 120.

[0156] Therefore, even in the state of FIG. 14(b) where the DC power supply device 10C has failed, the output current Iout up to Imax = 480 (A) can be supplied to the load 120 with an output voltage Vout within the voltage tolerance range of the load 120. That is, it is understood that a redundant design for coping with the failure of any DC power supply device has been realized.

[0157] Thus, also in the DC power supply system according to the modification of Embodiment 2, a redundant design can be realized simply by increasing the number of parallel-connected DC power supply devices by one compared to the number required to supply the maximum load current Imax to the load 120. Thereby, similar to Embodiment 2, for M DC power supply devices, by simply additionally connecting one more (M + 1) DC power supply devices, a redundant design that is advantageous in terms of cost reduction and miniaturization can be realized.

[0158] Also, in the modification of Embodiment 2, each DC power supply device 10 has a function of detecting deterioration of a capacitor based on detection of an increase in a ripple voltage, as illustrated in FIGS. 5 and 6, as described in Embodiment 1. Therefore, similar to the modification of Embodiment 1, the control shown in FIGS. 7 and 8 can be executed.

[0159] For example, when an increase in the ripple voltage is detected (i.e., when step S150 in FIG. 7 is determined to be YES), in step S170 of FIG. 7, the reference voltage Vr can be decreased so as to be lower than at least one of the other DC power supply devices 10. Thereby, progression of deterioration of the smoothing capacitor in the DC power supply device 10 can be suppressed.

[0160] Preferably, in step S170, the reference voltage Vr can be set lower than the minimum voltage Vrmin in the initial state (before detection of an increase in the ripple voltage) (for example, Vtx + Z(%) < Vr < Vrmin). Thereby, it becomes possible to protect the DC power supply device 10 (for example, the DC power supply device 10C in FIG. 12(b)) so as to be fixed in a non-operating state before it reaches a complete failure. Thereby, it can be expected to further extend the life of the DC power supply system.

[0161] Embodiment 3. In Embodiment 3, a power supply system having the maintenance function of the DC power supply system described in Embodiments 1 and 2 and their modifications will be described.

[0162] FIG. 15 is a block diagram for explaining the configuration of the power supply system 2 according to Embodiment 3. Referring to FIG. 15, the power supply system 2 includes M (M: an integer of 2 or more) DC power supply systems 100(1) to 100(M) and a server 3 for maintenance management. The server 3 is installed, for example, in a service center for maintaining the quality of a plurality of DC power supply systems 100(1) to 100(M) and protecting them from failures. The server 3 corresponds to an example of a “management device”.

[0163] Each DC power supply system 100 is communicably connected to the server 3 via the communication network 5. The communication network 5 is typically the Internet. The server 3 may be a shared server shared by a plurality of service centers, or may be a cloud server provided by a cloud server management company.

[0164] FIG. 16 is a block diagram for explaining a configuration example of the DC power supply device 10 constituting the DC power supply systems 100(1) to 100(M) shown in FIG. 15. Hereinafter, the DC power supply systems 100(1) to 100(M) are collectively referred to simply as the DC power supply system 100.

[0165] The DC power supply system 100 includes a plurality of DC power supply devices 10 connected in parallel, similar to Embodiments 1 and 2 and their modified examples.

[0166] As shown in FIG. 16, in the DC power supply system 100 included in the power supply system according to Embodiment 3, each DC power supply device 10 is configured to further include a communication circuit 170 and a status display circuit 180 as compared with the configuration example in FIG. 6. The configuration and operation of the DC power supply device 10 in FIG. 16 are the same as those of any of Embodiments 1 and 2 and their modified examples. That is, the control IC 160 has a function of detecting an increase in the ripple voltage of the DC power supply device 10 in consideration of the ambient temperature Ta (steps S130 to S160 in FIG. 7), and a function of reducing the reference voltage Vr when an increase in the ripple voltage is detected (step S170 in FIG. 7).

[0167] The status display circuit 180 is composed of a plurality of LEDs (Light Emitting Diodes) or a display panel such as a liquid crystal, and executes an abnormality notification according to the abnormality notification data Dds generated by the control IC 160. The abnormality notification data Dds is generated so that, for example, when an increase in the ripple voltage of the DC power supply device 10 is detected, at S160 in FIG. 7, lighting of the LED or message display for notifying deterioration detection of the smoothing capacitor 133 is executed.

[0168] By providing the status display circuit 180, it is possible to improve the visibility and work efficiency of the operator during maintenance work. The control IC 160 can generate the abnormality notification data Dds so that an abnormality notification is also performed when not only the increase in the ripple voltage but also a defect of the DC power supply device 10 such as a failure of other components is detected. In this case, the abnormality notification data Dds can be generated so that the display content (selection of the LED to be lit or the message content to be displayed) by the status display circuit 180 is different according to the type of the defect.

[0169] Similar to the abnormality notification data Dds, the control IC 160 generates the status data Dinf indicating the maintenance information of the DC power supply device 10. The status data Dinf is transmitted to the server 3 shown in FIG. 15 by the communication circuit 170.

[0170] FIG. 17 is a block diagram for explaining the operation of the communication circuit 170. As shown in FIG. 17, the communication circuit 170 of each of the plurality of DC power supply devices 10 constituting each DC power supply system 100 is communicatively connected to the server 3. In each DC power supply device 10, when the DC power supply device 10 fails due to factors such as component failure, or when an increase in the ripple voltage is detected and the reference voltage Vr is decreased, the status data Dinf indicating the information is generated. For example, when the output voltage (DC voltage Vo) of the DC power supply device 10 is too low with respect to the reference voltage Vr (Vo < Vr·kt, where kt is a constant less than 1.0), the failure of the DC power supply device 10 can be detected.

[0171] The communication circuit 170 combines the identification information of the corresponding DC power supply system 100 and DC power supply device 10 with the status data Dinf and transmits it to the server 3. The server 3 stores the maintenance information of the power supply system 2 in a storage area (not shown) based on the status data Dinf received from the communication circuit 170 of each DC power supply device 10.

[0172] FIG. 18 is a diagram for explaining an example of the structure of maintenance information stored in the server 3. As shown in FIG. 18, the state data Dinf is transmitted to the server 3 for each of the DC power supply systems 100(1) to 100(M), distinguished for every plurality of DC power supply devices 10.

[0173] Therefore, in the server 3, for each of the DC power supply systems 100(1) to 100(M), maintenance information indicating the presence or absence of the occurrence of a failure and an increase in the ripple voltage in each of the plurality of DC power supply devices 10 can be stored as data indicating normal (0) and abnormal (1). Regarding the failure, a plurality of bits of information may be stored so that the failure mode and the failed component can be distinguished.

[0174] Also, when an increase in the ripple voltage is detected, information indicating the ambient temperature Ta at the time of detection may be further included in the state data Dinf and further stored in the server 3.

[0175] In the server 3, on a display (not shown), information indicating the occurrence of a failure or a defect in each DC power supply device 10 of each of the plurality of DC power supply systems 100 can be integrally displayed based on the maintenance information in FIG. 18.

[0176] Thus, according to the power supply system according to the third embodiment, an operator at the service center can know the DC power supply system 100 and the DC power supply device 10 that require maintenance from a remote location without going directly to the installation location of the DC power supply system 100. As a result, it becomes possible to efficiently perform the maintenance of each DC power supply device 10 of each DC power supply system 100 at an appropriate timing.

[0177] For example, for the faulty DC power supply device 10, it may be necessary to promptly plan the work of replacing components and the like by going to the installation location of the DC power system 100 including the DC power supply device 10. On the other hand, for the DC power supply device in which an increase in the ripple voltage is detected, since the further progress of the smoothing capacitor 133 can be suppressed by the control of reducing the reference voltage Vr described in Embodiment 1 and the like, there is no urgency until component replacement, and it is possible to plan the replacement at the next regular maintenance.

[0178] Note that the communication between the DC power system 100 and the server 3 is not limited to the configuration example of FIG. 17. FIG. 19 shows a block diagram for explaining a modified example of the configuration of the DC power system in Embodiment 3.

[0179] As shown in FIG. 19, the DC power system 100 may be configured to further include a communication control circuit 190 in which the communication functions of a plurality of DC power supply devices 10(1) to 10(N) and the server 3 are aggregated.

[0180] In the configuration example of FIG. 19, the communication circuit 170 of each DC power supply device 10 does not have a communication function with the server 3 and transmits the status data Din to the communication control circuit 190. Then, the communication control circuit 190 combines the identification information of the DC power supply devices 10(1) to 10(N) and transmits the status data Din from each DC power supply device 10 to the server 3.

[0181] Alternatively, the communication control circuit 190 may be configured to generate the status data Din of the plurality of DC power supply devices 10(1) to 10(N) using the information received from the control IC 160 via the communication circuit 170 of each DC power supply device 10.

[0182] Also in FIG. 19, the status data Din and the identification information transmitted to the server 3 are the same as those in the communication configuration of FIG. 16. Therefore, the maintenance information stored in the server 3 can be the same for any of the communication configurations of FIGS. 16 and 19.

[0183] In the configuration example of FIG. 19, without providing each DC power supply device 10 with a communication function with the server 3, the communication function with the server 3 can be aggregated only in the communication control circuit 190 shared by the plurality of DC power supply devices 10(1) to 10(N). Thereby, the configuration of the communication circuit 106 in each DC power supply device 10 can be simplified.

[0184] Regarding the plurality of embodiments described above, including combinations not mentioned in the specification, it is also confirmed that the configurations described in each embodiment can be appropriately combined within a range where no inconsistency or contradiction occurs, as planned from the beginning of the application.

[0185] <Supplementary Note> The above-described embodiments and modification examples include the following technical ideas.

[0186] [Configuration 1] A DC power supply system (100, 100a to 100d) for supplying (Vout) and direct current (Iout) to a load (120), Comprising a plurality of DC power supply devices (10A to 10E / 10A to 10F) whose output sides connected to the load are connected in parallel, Each of the plurality of DC power supply devices enters a non-operating state where it does not output current when the DC voltage supplied to the load is higher than the actual output voltage (Vo) of the DC power supply device, while when the DC voltage is equal to or lower than the output voltage, it operates to enter an operating state according to a predetermined output characteristic. The output characteristic is that in each of the DC power supply devices, when the output current (Io) is smaller than the upper limit current (Icc) set for each of the plurality of DC power supply devices, it operates in a constant voltage mode in which feedback control of the output voltage is performed to maintain the output voltage at the reference voltage (Vr), while when the output current reaches the upper limit current, it is set to operate in a constant current mode in which feedback control of the output current is performed to maintain the output current at the upper limit current. In each of the DC power supply devices, the upper limit current is set to be equal to or less than the rated current of the DC power supply device. Each of the DC power supply devices includes a smoothing capacitor (133) connected to the output side and having a characteristic that the DC resistance component increases as deterioration progresses, a voltage detection circuit (150) that detects the ripple voltage generated in the smoothing capacitor, a temperature detection circuit (140) that detects the ambient temperature (Ta) around the smoothing capacitor, and a control circuit (160) that, when the ambient temperature is higher than a predetermined determination temperature (Tjd) and the ripple voltage exceeds a predetermined determination voltage (k·Vt), detects an increase in the ripple voltage and reduces the reference voltage in the constant voltage mode of the DC power supply device. A DC power supply system.

[0187] [Configuration 2] The control circuit (160) is configured such that when the ambient temperature (Ta) is lower than a correction start temperature (T0) predetermined according to the temperature characteristic of the DC resistance component of the smoothing capacitor (133) and higher than the determination temperature (Tjd), and a voltage value obtained by correcting the detection value by the voltage detection circuit (150) in the decreasing direction according to the temperature characteristic exceeds the determination voltage (k·Vt), the increase in the ripple voltage is detected. The DC power supply system according to Configuration 1.

[0188] [Configuration 3] In an initial state where it is not detected that the ripple voltage has risen above the determination voltage in all of the plurality of DC power supply devices (10A to 10E / 10A to 10F), among at least some of the plurality of DC power supply devices, the reference voltage is (Vr), and the output voltages (Vo) from the respective DC power supply devices are set to different values within a range where they do not deviate from the voltage tolerance range (Vrx ± X (%)) of the load. The DC power supply system according to Configuration 1 or Configuration 2.

[0189] [Configuration 4] The number of the plurality of DC power supply devices is determined such that the sum of the upper limit currents (Icc) of some of the plurality of DC power supply devices (10A to 10F) is greater than the maximum load current (Imax) of the load (120). The DC power supply system according to any one of Configurations 1 to 3.

[0190] [Configuration 5] Each of the plurality of DC power supply devices (10A to 10F) has the same specification. The number of the plurality of DC power supply devices is determined such that the sum of the upper limit currents (Icc) of the DC power supply devices excluding one from the plurality of DC power supply devices is greater than the maximum load current (Imax) of the load (120). The DC power supply system according to Configuration 4.

[0191] [Configuration 6] Each of the DC power supply devices (10A to 10E / 10A to 10F) further includes a status display circuit (180) that displays information for abnormal notification of the DC power supply device. The information for abnormal notification includes information on whether the control circuit has detected an increase in the ripple voltage. The DC power supply system according to any one of Configurations 1 to 5.

[0192] [Configuration 7] M DC power supply systems (100, 100a to 100d) according to any of Configurations 1 to 6, where M is an integer of 2 or more. And a management device (3). Each of the M DC power supply systems has a communication function with the management device, and transmits maintenance information (Dinf) for abnormal notification of each of the plurality of DC power supply devices (10A to 10E / 10A to 10F) of the DC power supply system to the management device in combination with the identification information of each of the plurality of DC power supply devices. The maintenance information includes information on whether the control circuit has detected an increase in the ripple voltage in the DC power supply device of each DC power supply system. The power supply system (2).

[0193] [Configuration 8] The power supply system according to Configuration 7, wherein each of the DC power supply devices (10A to 10E / 10A to 10F) further includes a communication circuit (170) for transmitting the maintenance information (Dinf) to the management device (3).

[0194] [Configuration 9] Each of the DC power supply systems (100, 100a to 100d) further includes a communication control circuit (190) for transmitting the maintenance information (Dinf) to the management device (3), The power supply system according to Configuration 7, wherein each of the DC power supply devices (10A to 10E / 10A to 10F) further includes a communication circuit (170) for transmitting the maintenance information to the communication control circuit.

[0195] It should be considered that all aspects of the embodiments disclosed this time are illustrative and not restrictive. The scope of the present disclosure is shown by the claims rather than the above description, and all changes within the meaning and scope equivalent to the claims are intended to be included.

Explanation of Reference Numerals

[0196] 2 Power supply system, 3 Server, 5 Communication network, 10, 10A, 10B, 10C, 10D, 10E, 10F Power supply unit, 15 Standard value, 100, 100B, 100a, 100b, 100c, 100d, 100g DC power supply system, 101 Power source, 106, 170 Communication circuit, 120 Load, 130 Semiconductor switching element, 131, 138, 153 Diode, 132 Reactor, 133 Smoothing capacitor, 135 Circuit, 140 Thermistor, 150 Ripple voltage detection circuit, 151 Operational amplifier, 152 AC component amplification section, 154 Peak hold circuit, 160 Control IC, 180 Status display circuit, 190 Communication control circuit, Dds abnormality notification data, Dinf status data, IRa~IRe Current region, Icc Upper limit current, Imax Maximum load current, Io Output current (DC power supply unit), Iout Output current (DC power supply system), NL, PL Power line, Ta Ambient temperature, Tjd Reference temperature, Vo Output voltage (DC power supply unit), Vout Output voltage (DC power supply system), Vrp Ripple voltage signal, Vr Reference voltage (DC power supply unit), Vrx Standard voltage (load), Vtmp Thermistor voltage signal.

Claims

1. A DC power supply system for supplying a DC voltage and a DC current to a load, comprising a plurality of DC power supply devices whose output sides connected to the load are connected in parallel, each of the plurality of DC power supply devices enters a non-operating state in which it does not output current when the DC voltage supplied to the load is higher than the actual output voltage of the DC power supply device, while when the DC voltage is less than or equal to the output voltage, it operates so as to enter an operating state according to a predetermined output characteristic, the output characteristic is that in each of the DC power supply devices, when the output current is less than the upper limit current set for each of the plurality of DC power supply devices, it operates in a constant voltage mode in which feedback control of the output voltage is performed to maintain the output voltage at a reference voltage, while when the output current reaches the upper limit current, it is set to operate in a constant current mode in which feedback control of the output current is performed to maintain the output current at the upper limit current, in each of the DC power supply devices, the upper limit current is set to be less than or equal to the rated current of the DC power supply device, each of the DC power supply devices includes a smoothing capacitor connected to the output side and having a characteristic that the DC resistance component increases as deterioration progresses, a voltage detection circuit for detecting a ripple voltage generated in the smoothing capacitor, a temperature detection circuit for detecting the ambient temperature of the smoothing capacitor, and a control circuit that, when the ripple voltage exceeds a predetermined determination voltage when the ambient temperature is higher than a predetermined determination temperature, detects an increase in the ripple voltage and reduces the reference voltage in the constant voltage mode of the DC power supply device. A DC power supply system.

2. When the ambient temperature is lower than a preset correction start temperature according to the temperature characteristics of the DC resistance component of the smoothing capacitor and higher than the determination temperature, if the voltage value obtained by correcting the detection value by the voltage detection circuit in the decreasing direction according to the temperature characteristics exceeds the determination voltage, the DC power supply system according to claim 1 detects an increase in the ripple voltage.

3. In an initial state where it is not detected that the ripple voltage has risen above the determination voltage in all of the plurality of DC power supply devices, among at least some of the plurality of DC power supply devices, the reference voltage is set to different values within a range where the output voltage from each DC power supply device does not deviate from the voltage tolerance range of the load. The DC power supply system according to claim 1.

4. The number of the plurality of DC power supply devices is determined such that the sum of the upper limit currents of some of the plurality of DC power supply devices is greater than the maximum load current of the load. The DC power supply system according to claim 1.

5. The number of the plurality of DC power supply devices is determined such that the sum of the upper limit currents of some of the plurality of DC power supply devices is greater than the maximum load current of the load. The DC power supply system according to claim 3.

6. Each of the plurality of DC power supply devices has the same specification. The number of the plurality of DC power supply devices is determined such that the sum of the upper limit currents of the DC power supply devices excluding one from the plurality of DC power supply devices is greater than the maximum load current of the load. The DC power supply system according to claim 4 or 5.

7. Each of the DC power supply devices further includes a status display circuit that displays information for abnormal notification of the DC power supply device. The information for abnormal notification includes information on whether the control circuit has detected an increase in the ripple voltage. The DC power supply system according to any one of claims 1 to 5.

8. M DC power supply systems according to any one of claims 1 to 5, which are integers of 2 or more, and a management device, Each of the M DC power supply systems has a communication function with the management device, and maintenance information for notifying abnormalities of each of the plurality of DC power supply devices of the DC power supply system is combined with the identification information of each of the plurality of DC power supply devices and transmitted to the management device. It is configured to do so. The maintenance information includes information on whether or not the control circuit has detected an increase in the ripple voltage in the DC power supply device of each DC power supply system.

9. Each of the DC power supply devices further includes a communication circuit for transmitting the maintenance information to the management device. The power supply system according to claim 8.

10. Each of the DC power supply systems further includes a communication control circuit for transmitting the maintenance information to the management device, Each of the DC power supply devices further includes a communication circuit for transmitting the maintenance information to the communication control circuit. The power supply system according to claim 8.

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