Power System

Abstract

A plurality of power supply devices (1A-1C), of which the outputs are connected in parallel with each other, have converter units (3a-3c) that are configured to include a plurality of semiconductor switching elements (10a-10c) and that supply output voltages and output currents. The converter units (3a-3c) are subjected to constant voltage control so as to cause the output voltages (Voa-Voc) to become closer to a voltage command value. Among the plurality of power supply devices (1a-1c), for a power supply device that is in a first temperature state of which a detected temperature is higher than a temperature threshold value, the voltage command value is set as a first voltage value. Meanwhile, for a power supply device that is in a second temperature state of which the detected temperature is equal to or lower than the temperature threshold value, the voltage command value is set as a second voltage value higher than the first voltage value.

Description

[Technical Field]

[0001] The present disclosure relates to power supply systems. [Background technology]

[0002] To increase the capacity of power supplies, a system configuration has been adopted in which multiple power supply devices are connected in parallel to supply power to a load. In this case, if differences in output voltage occur among the multiple parallel-connected power supply devices due to component variations or the like, there is a risk that the lifespan of a specific power supply device with a higher output voltage will be shorter than expected due to factors such as an increase in the temperature rise of components caused by an increase in output current. This raises concerns about an increase in the lifecycle cost of the equipment due to an increase in the number of maintenance operations, etc.

[0003] On the other hand, if a master / slave relationship is established between multiple power supply devices connected in parallel and control is introduced to suppress bias in output current, there is a concern that the increased complexity of the control will lead to increased circuit scale and wiring, resulting in increased costs and size of the power supply system.

[0004] For this reason, Japanese Patent Application Laid-Open No. 2019-92244 (Patent Document 1) describes a control configuration for balancing output currents by having each power supply device perform similar control without setting a master / slave relationship between multiple power supply devices connected in parallel.

[0005] Specifically, in Patent Document 1, a plurality of power supply devices connected in parallel each generate a current-corrected detection signal (Vop) from a detection voltage (Vi) corresponding to its own output current, and by connecting the power supply devices with a common balance line, the average value of the current-corrected detection signals (Vop) of the plurality of power supply devices appears on the balance line as a balanced voltage (Vbi). Furthermore, in each of the plurality of power supply devices, the switching element is controlled so as to reduce the difference between the balanced voltage (Vbi) shared on the balance line and the current-corrected detection signal (Vop) of that power supply device.

[0006] In Patent Document 1, correction information for converting the detected voltage (Vi) into a current-corrected detection signal (Vop) is stored in advance as an arithmetic expression or conversion table for each of a plurality of power supply devices so as to correct for variations in the resistance values ​​of the current detection resistors and variations in the amplification factors of the amplifiers, which are detected in the adjustment process. This allows control to be achieved that balances the output currents between the power supply devices without setting a master device. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2019-92244 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the current balancing in Patent Document 1 depends on the accuracy of the correction information. For this reason, for example, if there is a difference between the ambient temperature during the adjustment process and the ambient temperature in the actual usage environment, the effect of current balancing using the correction information may be reduced depending on the temperature characteristics of components such as the current detection resistors and signal correction units. Furthermore, since highly accurate correction information must be obtained for each power supply device, the adjustment process takes a long time, which may reduce productivity.

[0009] That is, in Patent Document 1, precise control is required to balance the output currents in order to avoid shortening the lifespan due to uneven temperature rises among multiple power supply devices connected in parallel. As a result, there are concerns that a decrease in control accuracy will result in differences in lifespan among the power supply devices, or that the adjustment load will increase in order to ensure control accuracy that balances the lifespans.

[0010] The present disclosure has been made to solve such problems, and the purpose of the present disclosure is to balance the temperature rise between power supply devices through simple control in a power supply system in which current is supplied to a load by multiple power supply devices connected in parallel. [Means for solving the problem]

[0011] In one aspect of this disclosure, a power supply system is provided. The power supply system includes a plurality of power supply devices whose outputs are connected in parallel. Each of the plurality of power supply devices includes a converter unit, a temperature detection unit, an output voltage detection unit, a switching control unit, and a signal control unit. The converter unit includes a semiconductor switching element and supplies an output voltage and an output current. The temperature detection unit measures the temperature of the converter unit. The output voltage detection unit measures the output voltage of the converter unit. The switching control unit generates a drive signal for controlling the on / off of the semiconductor switching element in accordance with constant voltage control that brings the detected voltage of the output voltage detection unit closer to a voltage command value. The signal control unit increases or decreases the voltage command value of the switching control unit based on a comparison between the temperature detected by the temperature detection unit and a temperature threshold value. The signal control units share information related to setting the voltage command value of each power supply device with each other. Furthermore, for a power supply device among the plurality of power supply devices in a first temperature state where the detected temperature is higher than the temperature threshold value, the signal control unit sets the voltage command value to a first voltage value. On the other hand, for a power supply device in a second temperature state where the detected temperature is equal to or lower than the temperature threshold value, the signal control unit sets the voltage command value to a second voltage value higher than the first voltage value. [Effects of the Invention]

[0012] According to the present disclosure, in a power supply system in which a current is supplied to a load by a plurality of power supply devices connected in parallel, temperature rises can be balanced among the power supply devices by simple control. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a block diagram illustrating an example of the configuration of a power supply system according to a first embodiment. [Figure 2] 5 is a flowchart illustrating constant voltage control of each power supply device in the power supply system according to the first embodiment. [Figure 3] 4 is a table illustrating an example of the operation of the power supply system according to the first embodiment. [Figure 4]FIG. 10 is a conceptual diagram illustrating the output control characteristics of each power supply device in a power supply system according to a modification of the first embodiment. [Figure 5] 4 is a flowchart illustrating a control process for CVCC control of each converter unit in the power supply system according to the first embodiment. [Figure 6] FIG. 10 is a conceptual diagram illustrating an example of the operation of the power supply system according to a modification of the first embodiment. [Figure 7] FIG. 10 is a block diagram illustrating a configuration example of a power supply system according to a second embodiment. [Figure 8] 8 is a flowchart for explaining the operation of an accumulated temperature calculation unit and an accumulated temperature comparison unit shown in FIG. 7. [Figure 9] 10 is a flowchart for explaining an additional operation of a signal control unit in the power supply system according to the second embodiment. [Figure 10] 10 is a table illustrating an example of the operation of the power supply system according to the second embodiment. [Figure 11] FIG. 10 is a block diagram illustrating a configuration example of a power supply system according to a third embodiment. [Figure 12] 12 is a flowchart for explaining the operation of an accumulated temperature calculation unit and an accumulated temperature determination unit shown in FIG. [Figure 13] FIG. 10 is a block diagram illustrating a configuration example of a power supply system according to a fourth embodiment. [Figure 14] FIG. 10 is a block diagram illustrating a configuration example of a power supply system according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following, identical or corresponding parts in the drawings will be denoted by the same reference numerals, and their description will not be repeated in principle.

[0015] Embodiment 1 FIG. 1 is a block diagram illustrating an example of the configuration of a power supply system 100A according to the first embodiment.

[0016] 1, power supply system 100A includes multiple power supply devices connected in parallel. The following describes a configuration in which three power supply devices 1a to 1c are connected in parallel. The outputs of power supply devices 1a to 1c are connected in parallel, and supply an output voltage (DC) and an output current (DC) to a common load 120.

[0017] 1, the input sides of the power supply devices 1a to 1c are connected to a common power supply 110 (AC or DC). In this embodiment, the description will proceed assuming that the power supply 110 is a power converter that converts AC voltage from an AC power supply into DC voltage, or a DC power supply using a battery or other storage element. Note that the input sides of the power supply devices 1a to 1c can also be connected to separate power supplies as long as the input voltage is common.

[0018] Since the configurations of the power supply devices 1a to 1c are similar, the configuration of the power supply device 1a will be described as a representative. The power supply device 1a includes a converter unit 3a, a switching control unit 4a, an output voltage detection unit 5a, an output current detection unit 6a, a temperature detection unit 7a, and a signal control unit 8a.

[0019] The converter unit 3a has at least one semiconductor switching element 10a, a rectifier diode 9a, and a smoothing capacitor 15a. The converter unit 3a converts an input voltage from a power supply 110 into an output voltage Voa by DC voltage conversion using the switching (on / off) of the semiconductor switching element 10a. The output voltage Voa and output current Ioa of the converter unit 3a are supplied to a load 120.

[0020] The converter unit 3a can be configured as any circuit, such as a forward converter or a flyback converter, as long as it performs DC voltage conversion by controlling the on / off of a semiconductor switching element. If the power supply 110 is an AC power supply, a rectifier circuit is further provided at the input stage of the converter unit 3a.

[0021] The output voltage detector 5a measures the output voltage Voa of the converter 3a and outputs an output voltage signal Vva indicating the measured value of the output voltage Voa. The output voltage signal Vva indicates the "detected voltage." A voltage divider circuit using resistors can typically be applied to the output voltage detector 5a, but any method can be applied as long as it is capable of measuring the output voltage Voa.

[0022] The output current detection unit 6a measures the output current Ioa of the converter unit 3a and outputs an output current signal Via indicating the measured value of the output current Ioa. The output current signal Via indicates the "detected current." A fluxgate sensor using a shunt resistor or a current transformer can be applied to the output current detection unit 6a, but any method can be applied as long as it can measure the output current Ioa.

[0023] The temperature detection unit 7a is disposed adjacent to a heat-generating portion such as a rectifier diode 9a, a smoothing capacitor 13a, or a circuit board pattern (not shown) to measure the temperature of that portion. The temperature detection unit 7a outputs a temperature signal Vta indicating the measured temperature of the converter unit 3a. The temperature signal Vta indicates the "detected temperature." The temperature detection unit 7a can be configured by mounting a chip-type thermistor near the heat-generating portion on the circuit board, or by fixing a film-type or lead-type thermistor directly to the heat-generating portion. Any method can be applied to the temperature detection unit 7a as long as it can measure the actual temperature of the converter unit 3a.

[0024] In particular, if the temperature detection unit 7a is a thermistor fixed to the board, it can be placed close to specific components of the converter unit 3a that are prone to heat generation, or that are likely to cause a shortened lifespan due to temperature increases, making it possible to accurately measure temperature increases that affect the lifespan of the power supply device 1a.

[0025] The switching control unit 4a corresponds to a gate drive circuit for the semiconductor switching element 10a and outputs a drive signal Sga for turning the semiconductor switching element 10a on and off. The switching control unit 4a generates the drive signal Sga so as to perform constant voltage (CV) control that brings the output voltage Voa closer to the voltage command value Vo*. For example, the drive signal Sga is generated so as to adjust the on-period ratio (duty ratio) of the semiconductor switching element 10a by feedback control (typically, proportional-integral (PI) control) of the deviation between the output voltage Voa and the voltage command value Vo*.

[0026] Furthermore, the switching control unit 4a has a function of increasing or decreasing the voltage command value Vo* in response to a switching control signal Ssa from a signal control unit 8a (described later). For example, the voltage command value Vo* is set to one of a first voltage value V1 and a second voltage value V2 (Vo*=V1 or V2) in response to the switching control signal Ssa. The first voltage value is lower than the second voltage value; for example, V1 is set to a value lower by a certain value or a certain percentage (e.g., about 0.5%) than a rated value V0 of the output voltage to the load 120, and V2 is set to a value higher by the certain value or a certain percentage (e.g., about 0.5%) than the rated value V0.

[0027] For example, when the switching control signal Ssa is at a logical low level (hereinafter referred to as L level), Vo* is set to V1, and when it is at a logical high level (hereinafter referred to as H level), Vo* is set to V2. Furthermore, by configuring the switching control signal Ssa with multiple bits, it is possible to instruct the semiconductor switching element 10a to be stopped (fixed to OFF). The switching control unit 4a can be configured, for example, by a general-purpose microcomputer or an IC (Integrated Circuit) having a power supply control function.

[0028] The signal control unit 8a receives the output voltage signal Vva from the output voltage detection unit 5a and the temperature signal Vta from the temperature detection unit 7a, and generates a voltage rise signal Sva, a temperature rise signal Sta, and a temperature abnormality signal Sta* for the converter unit 3a.

[0029] The voltage-up signal Sva is set to an H level when the output voltage signal Vva is higher than a voltage threshold VHt (voltage-up state), and is set to an L level when the output voltage signal Vva is lower than the voltage threshold VHt. The voltage threshold VHt is set between a first voltage value V1 and a second voltage value V2. The voltage threshold VHt is set to different values ​​when the voltage-up signal Sva is at an L level and an H level so as to have a so-called hysteresis characteristic. Specifically, the voltage threshold VHt in the voltage-up state is set to a lower value than when the voltage-up state is not in effect.

[0030] The temperature rise signal Sta is set to an H level when the temperature signal Vta is higher than the temperature threshold VTHt (also referred to as a temperature rise state), and is set to an L level when the temperature signal Vta is equal to or lower than the temperature threshold (also referred to as a normal temperature state or a non-rise temperature state). The temperature threshold VTHt is set to different values ​​when the temperature rise signal Sta is at an L level and when it is at an H level so as to have a so-called hysteresis characteristic. Specifically, the temperature threshold VTHt is set to a lower value in the temperature rise state than in the normal temperature state. The temperature rise state corresponds to an example of a "first temperature state," and the normal temperature state or the non-rise temperature state corresponds to an example of a "second temperature state."

[0031] The temperature abnormality signal Sta* is set to H level when the temperature signal Vta is higher than a predetermined upper temperature limit VTHlm (also referred to as an overheated state), and is set to L level when Tva≦THlim. For example, when the temperature threshold VTHt is set to correspond to around 80°C, the upper temperature limit VTHlm is set to correspond to around 120°C.

[0032] The power supply device 1b includes a converter unit 3b, a switching control unit 4b, an output voltage detection unit 5b, an output current detection unit 6b, a temperature detection unit 7b, and a signal control unit 8b, which are similar to the converter unit 3a, the switching control unit 4a, the output voltage detection unit 5a, the output current detection unit 6a, the temperature detection unit 7a, and the signal control unit 8a. The converter unit 3b has a semiconductor switching element 10b, a rectifier diode 9b, and a smoothing capacitor 15b, which are similar to the semiconductor switching element 10a, the rectifier diode 9a, and the smoothing capacitor 15a.

[0033] Similarly, power supply device 1c includes converter unit 3c, switching control unit 4c, output voltage detection unit 5c, output current detection unit 6c, temperature detection unit 7c, and signal control unit 8c, which are similar to converter unit 3a, switching control unit 4a, output voltage detection unit 5a, output current detection unit 6a, temperature detection unit 7a, and signal control unit 8a. Converter unit 3c also includes semiconductor switching element 10c, rectifier diode 9c, and smoothing capacitor 15c, which are similar to semiconductor switching element 10a, rectifier diode 9a, and smoothing capacitor 15a.

[0034] The first voltage value V1 and second voltage value V2 of the voltage command value Vo*, and the above-mentioned voltage threshold value VHt, temperature threshold value VTHt, and upper temperature limit value VTHlm are common among the power supply devices 1a to 1c.

[0035] Therefore, the signal control unit 8b compares the output voltage signal Vvb of the converter unit 3b with the voltage threshold VHt to generate a voltage rise signal Svb in the same manner as the voltage rise signal Sva.Furthermore, by comparing the temperature signal Vtb of the converter unit 3b with the temperature threshold VTHt and the upper temperature limit VTHlm, the signal control unit 8b generates a temperature rise signal Stb and a temperature abnormality signal Stb* in the same manner as the temperature rise signal Sta and the temperature abnormality signal Sta*.

[0036] Furthermore, in the signal control section 8c, a voltage rise signal Svc, a temperature rise signal Stc, and a temperature abnormality signal Stc* are similarly generated based on the output voltage signal Vvc and the temperature signal Vtc of the converter section 3c.

[0037] In the following, when the power supply devices 1a to 1c are collectively referred to without distinguishing between them, the subscripts "a," "b," or "c" will be omitted for each circuit element, signal, physical quantity (temperature, voltage), etc. For example, when the output voltages Voa, Vob, and Voc are collectively referred to, they will also be referred to as output voltage Vo.

[0038] The power supply system 100A further includes signal generation circuits 15t and 15v. The signal generation circuit 15t generates an overall temperature abnormality signal Sto. The signal generation circuit 15v generates an overall voltage state signal Svo. The overall temperature abnormality signal Sto and the overall voltage state signal Svo from the signal generation circuits 15t and 15v are input to each of the signal control units 8a to 8c and shared by the power supply devices 1a to 1c.

[0039] The total temperature abnormality signal Sto is set to H level when the temperature signal Vt (Vta to Vtc) exceeds the upper temperature limit VTHlm in at least one of the power supply devices 1a to 1c. On the other hand, when the temperature signals Vt (Vta to Vtc) are equal to or lower than the upper temperature limit VTHlm in all of the power supply devices 1a to 1c, the total temperature abnormality signal Sto is set to L level. For example, the signal generating circuit 15t is configured by a logical sum (OR) gate that receives the temperature abnormality signals Sta* to Stc* as inputs and outputs the total temperature abnormality signal Sto.

[0040] The total voltage state signal Svo is set to H level when the output voltage signal Vv (Vva to Vvc) exceeds the voltage threshold VHt in at least one of the power supply devices 1a to 1c. On the other hand, when the output voltage signals Vv (Vva to Vvc) are equal to or lower than the voltage threshold VHt in all of the power supply devices 1a to 1c, the total voltage state signal Svo is set to L level. For example, the signal generation circuit 15v is configured by a logical sum (OR) gate that receives the voltage rise signals Sva to Svc as inputs and outputs the total voltage state signal Svo. The functions of the signal generation circuits 15t and 15v may be provided within each of the signal control units 8a to 8c.

[0041] In the power supply system 100A according to the first embodiment, constant voltage control is performed in each converter section 3 in accordance with the voltage command value Vo*, and the voltage command value Vo* of each power supply device 1 (1a to 1c) is increased or decreased through the switching control signal Ss (Ssa to Sac) depending on the temperature state and output voltage state of the power supply devices 1a to 1c.

[0042] Fig. 2 shows a flowchart illustrating constant voltage control of each power supply device in the power supply system according to embodiment 1. Since the constant voltage control process is similar in power supply devices 1a to 1c, Fig. 2 will explain the constant voltage control of power supply device 1a that is executed by signal control unit 8a.

[0043] 2, when power supply system 100A is started, signal control unit 8a sets the initial value of switching control signal Ssa in step (hereinafter simply referred to as "S") 110. The initial value setting is determined in advance so that some of switching control signals Ssa-Sac are set to H level and the rest are set to L level. In this specification, it is assumed that the initial settings are Ssa=H, Sab=Ssc=L.

[0044] The signal control unit 8a monitors the temperature signal Vta in S120. S120 includes S121 for comparing the temperature signal Vta with a temperature upper limit value VTHlm, and S122 for comparing the temperature signal Vta with a temperature threshold value VTHt.

[0045] In S121, when the temperature signal Vta is equal to or lower than the upper temperature limit VTHlm, i.e., when the temperature abnormality signal Sta* is at level L, a YES result is made. On the other hand, when the temperature signal Vta is higher than the upper temperature limit VTHlm, i.e., when the temperature abnormality signal Sta* is at level H (overheated state), a NO result is made in S121.

[0046] In S122, when the temperature signal Vta is equal to or lower than the temperature threshold VTHt, i.e., when the temperature rise signal Sta is at L level (normal temperature state), a YES determination is made. On the other hand, when the temperature signal Vta is higher than the temperature threshold VTHt, i.e., when the temperature rise signal Sta is at H level (temperature rising state), a NO determination is made in S122.

[0047] S120 (S121, S122) determines whether the power supply device 1a is in an overheated state (NO judgment in S121), a temperature rising state (YES judgment in S121 and NO judgment in S122), or a normal temperature (no temperature rising) state (YES judgment in both S121 and S122).

[0048] In an over-temperature state (NO in S121), the signal control unit 8a advances the process to S170 and sets the switching control signal Ssa to a stop signal for stopping (fixing off) the semiconductor switching element 10a of the converter unit 3a.

[0049] In the normal temperature state (YES determination in S122), the signal control unit 8a proceeds to S130 to check the overall voltage state signal Svo. In contrast, in the rising temperature state (NO determination in S122), the signal control unit 8a sets the switching control signal Ssa to L level in S125 to reduce the voltage command value Vo* in the power supply device 1a, and then proceeds to S130.

[0050] When the overall voltage state signal Svo is at L level in S130, that is, when the output voltage signals Vv (Vva to Vvc) of all of the power supply devices 1a to 1c are equal to or lower than the voltage threshold VHt, the signal control unit 8a judges S130 as YES and proceeds to S140.

[0051] In S140, the signal control unit 8a checks whether the temperature of the power supply device 1a is in a normal temperature state, as in S122. That is, when the temperature rise signal Sta is at L level, the determination in S140 is YES, and when the temperature rise signal Sta is at H level, the determination in S140 is NO.

[0052] When the determination in S140 is YES, i.e., when the power supply device 1a is in a normal temperature state (temperature not rising state), S150 and S155 set the switching control signal Ssa to H level. Specifically, when Ssa=L (when the determination in S150 is YES), S155 changes the switching control signal Ssa from L level to H level. In response to this, the total voltage state signal Svo also changes to H level. On the other hand, when Ssa=H (when the determination in S150 is NO), S155 is skipped and the switching control signal Ssa is maintained at H level. Once the switching control signal Ssa has been set to H level or L level in S150 and S155, the process proceeds to S160.

[0053] If the determination in S140 is NO, i.e., if the power supply device 1a is in a temperature rise state, the processes of S150 and S155 are skipped, and the switching control signal Ssa is set to L level in S145. In this way, if the power supply device 1a is in a temperature rise state, Ssa is set to L in at least one of S125 and S145.

[0054] When the total voltage state signal Svo is at H level in S130, that is, when the output voltage signal Vv (Vva to Vvc) of at least one of the power supply devices 1a to 1c is higher than the upper voltage limit VHlim, the signal control unit 8a determines NO in S130 and proceeds to S160. That is, the switching control signal Ssa is maintained at the level (L or H) at the time of determination in S130.

[0055] In S160, the signal control unit 8a checks the total temperature abnormality signal Sto. If the total temperature abnormality signal Sto is at H level, that is, if at least one of the power supply devices 1a to 1c is overheated (St>VTHlm) (NO in S160), the process proceeds to S170, where the switching control signal Ssa is set to a stop signal. As a result, even if the power supply device 1a is not in an overheated state, if at least one of the power supply devices 1b and 1c is in an overheated state, the semiconductor switching element 10a of the converter unit 3a is fixed to the off state.

[0056] On the other hand, when the overall temperature abnormality signal Sto is at L level, that is, when none of the power supply devices 1a to 1c are in an overheated state (YES determination in S160), the process returns to S120. As a result, the processes of S120 to S160 are repeatedly executed until an overheated state is detected in any of the power supply devices 1a to 1c (YES determination in S120 or S160).

[0057] In the processing of S120 to S160, when the power supply device 1a enters a temperature rising state, the switching control signal Ssa is set to L level, and the voltage command value Vo* of the converter section 3a is reduced (Vo*=V1).

[0058] Furthermore, when the power supply device 1a is in a normal temperature state, and none of the other power supply devices 1a to 1c are in a voltage-rising state (Svo=L level), the voltage command value Vo* of the converter unit 3a is increased (Vo*=V2). This makes it possible to restrict Vo* from becoming V2 for all of the power supply devices 1a to 1c. Furthermore, in the initial setting (S110), some of the switching control signals Ssa to Ssc are set to H level and some to L level. As a result, the voltage command values ​​Vo* of the power supply devices 1a to 1c are controlled so that they are not all maintained at the second voltage value V2 or the first voltage value V1. In other words, it is possible to control the voltage command values ​​Vo* of the power supply devices 1a to 1c so that they are not maintained at either the first voltage value V1 or the second voltage value V2. Note that a method different from the example of Figure 2 may be used, for example, by sharing the current levels of the switching control signals Ssa to Ssc between the signal control units 8a to 8c, so that the voltage command values ​​Vo* of the power supply devices 1a to 1c do not become equal to the first voltage value V1 or the second voltage value V2.

[0059] In the power supply devices 1b and 1c, the signal control units 8b and 8c perform control processing in which the subscript "a" in Figure 2 is replaced with "b" or "c," thereby enabling the voltage command value Vo* of the converter units 3b and 3c to be set in a similar manner.

[0060] FIG. 3 shows an example of the operation of power supply system 100A according to the first embodiment. Referring to Fig. 3, State 1 corresponds to the state after the initial setting in S110 in Fig. 2. In power supply device 1a, Ssa is set to H (Vo*=V2), while in power supply devices 1b and 1c, Ssb=Ssc=L (Vo*=V1). As a result, the voltage rise signal Sva of power supply device 1a is at H level, and the overall voltage state signal Svo also becomes H level. In State 1, the temperature of power supply device 1a has not yet risen, and the temperature rise signals Sta to Stc are all at L level.

[0061] In State 2, State 1 continues and the temperature of power supply device 1a rises, causing temperature rise signal Sta to change from L level to H level. In response to this, in S125 of Fig. 2 (NO determination in S1222), switching control signal Ssa of power supply device 1a is set to L level, and voltage command value Vo* of converter unit 3a is reduced (Vo* = V1).

[0062] In State 3, the voltage increase signal Sva of the power supply device 1a changes from H level to L level in response to the reduction in the voltage command value Vo* of the converter unit 3a in State 2. On the other hand, the temperature increase signal Sta is still at H level in State 3 because the temperature of the power supply device 1a decreases with a delay after the voltage reduction.

[0063] In state 3, in response to the voltage increase signal Sva going to L level, the total voltage state signal Svo changes from H level to L level. As a result, in power supply devices 1b and 1c in the normal temperature state (Stb=Stc=L), the switching control signals Ssb and Ssc change from L level to H level at S155 in Fig. 2. As a result, the voltage command value Vo* of converter units 3b and 3c increases (Vo*=V2).

[0064] In state 4, because Ssb=Ssc=H was set in state 3, the voltage rise signals Svb and Svc of power supply devices 1b and 1c change from L level to H level. Accordingly, the overall voltage state signal Svo is set to H level. Meanwhile, in power supply device 1a, which operated under Ssa=L, the temperature drops and the temperature rise signal Sta changes to L level. However, because Svo=H, the switching control signal Ssa of power supply device 1a is maintained at L level.

[0065] In State 5, while the operation of State 4, where Ssb=Ssc=H, continues, the temperature of power supply device 1b rises first, and temperature rise signal Stb changes from L level to H level before temperature rise signal Stc of power supply device 1c. In response to this, in power supply device 1b, switching control signal Ssb is set to L level in S125 of FIG. 2 (YES determination in S1222), and voltage command value Vo* of converter unit 3b is reduced.

[0066] In state 6, the voltage rise signal Svb changes from H level to L level in response to the decrease in the voltage command value Vo* in power supply device 1b in state 5. On the other hand, in power supply device 1c, the temperature rise signal Stc remains at L level, so the switching control signal Ssc is maintained at H, and as a result, the voltage rise signal Svc also remains at H level.

[0067] In State 7, the temperature of power supply device 1c, which is set to Ssc=H, rises, and temperature rise signal Stc changes from L level to H level. In response to this, in power supply device 1c, switching control signal Ssc is set to L level in S125 of FIG. 2 (NO determination in S122), and voltage command value Vo* of converter unit 3c is reduced.

[0068] In state 8, the voltage rise signal Svc of the power supply device 1c changes from H level to L level due to the setting of Ssc=L in state 7. As a result, all of the voltage rise signals Sva to Svc become L level, and the overall voltage state signal Svo returns to L level.

[0069] In state 8, since the temperature rise signal Sta is at L level, in power supply device 1a, the switching control signal Ssa changes from L level to H level in S155 of Fig. 2. In response to this, the total voltage state signal Svo also changes from L level to H level. On the other hand, in power supply devices 1b and 1c, where the temperature rise signals Stb and Stc are still at H level, the switching control signals Ssb and Ssc continue to operate at L level (Vo*=V1), so the voltage rise signals Svb and Svc are maintained at L level.

[0070] 2 and 3, it is possible to switch between parallel-connected power supply devices 1a to 1c, intentionally increasing the output voltage of each power supply device 1a to 1c, based on the temperature state of each power supply device 1a to 1c. In contrast, if multiple power supply devices with different output voltages due to manufacturing variations, temperature dependence of components, etc. are simply connected in parallel, the output current of the power supply device with the relatively higher output voltage increases, causing a concentrated temperature rise.

[0071] In the power supply system according to the first embodiment, based on the comparison result between the temperature signals Vta-Vtc and the temperature threshold VTHt, some of the power supply devices connected in parallel that are not in a temperature rise state are selected in turn and their output voltages are intentionally increased. This allows current to be supplied to the load 120 by the parallel operation of the multiple power supply devices 1a-1c, with the output current (amount of temperature rise) of the power supply devices that are not in a temperature rise state adjusted to be larger than the output current (amount of temperature rise) of the power supply devices that are in a temperature rise state.

[0072] As a result, in a power supply system in which multiple power supply devices connected in parallel supply current to a load, temperature rises in the multiple power supply devices can be balanced through simple control, preventing temperature rises from concentrating on a specific power supply device and resulting in uneven life spans among the power supply devices.

[0073] Furthermore, when an overheating state exceeding the upper temperature limit VTHlm is detected in any of the power supply devices, a protective operation is implemented to shut down the entire power supply system 100A. Furthermore, as described above, by providing hysteresis characteristics to the temperature threshold VTHt and the voltage threshold VHt, frequent changes in the voltage command value Vo* can be prevented, and constant voltage control can be performed stably.

[0074] A variation of the first embodiment. In the first embodiment, the temperature rise of the power supply devices 1a to 1c is detected by an increase in the temperature detected by the temperature detectors 7a to 7c, which are assumed to be thermistors. However, when the temperature rises, the following events occur in sequence: an increase in current, an increase in heat generation, and an increase in the measured value by the thermistor. Therefore, in a modification of the first embodiment, control for suppressing the temperature rise in response to a sudden increase in current will be described.

[0075] In the modification of the first embodiment, each of the converter units 3a to 3c of the power supply devices 1a to 1c has a so-called CVCC (Constant Voltage Constant Current) control function.

[0076] FIG. 4 is a conceptual diagram illustrating the output control characteristics of each power supply device in a power supply system according to a modification of the first embodiment.

[0077] 4, the converter unit 3 (3a to 3c) of each power supply device 1a to 1c executes constant voltage control according to the voltage command value Vo* as described in the first embodiment when the output current Io is lower than the upper limit current Ilm. On the other hand, when the output current Io reaches the upper limit current Ilm during CC control, the control transitions to CC (Constant Current) control, which executes output restrictions such as limiting the duty ratio of the semiconductor switching element 10 (10a to 10c). Because the output power of the converter unit 3 is fixed by this output restriction, the output voltage Vo decreases in accordance with an increase in power consumption in the load 120. The output restriction may be made stricter in stages so that the output current Io does not exceed the upper limit current Ilm.

[0078] FIG. 5 is a flowchart for explaining control processing for CVCC control of the converter section 3 (3a to 3c). The control processing shown in FIG. 5 is executed by each of the switching control sections 4a to 4c.

[0079] Referring to FIG. 5, in S210, the switching control section 4 (4a to 4c) determines whether the switching control signal Ss (Ssa to Ssc) is the stop signal set in S170 of FIG. 2. When the switching control signal Ss is the stop signal (YES determination in S210), the switching control section 4 (4a to 4c) fixes the drive signal Sg (Sga to Sgc) of the corresponding converter section 3 (3a to 3c) at the L level by S220. Thereby, the semiconductor switching elements 10 (10a to 10c) are fixed in the off state.

[0080] When the switching control signal Ss is not the stop signal (NO determination in S210), the switching control section 4 (4a to 4c) compares the output current signal Vi (Via to Vic) from the output current detection section 6 (6a to 6c) with a determination value VIlm determined corresponding to the upper limit current Ilm in FIG. 4 by S215. Thereby, in each of the power supply devices 1a to 1c, the comparison between the output current Io and the upper limit current Ilm in FIG. 4 is performed.

[0081] When Vi (Via to Vic) < VIlm, that is, when the output current Io (Ioa to Ioc) is smaller than the upper limit current Ilm (YES determination in S215), the process proceeds to S230. In S230, the switching control section 4 (4a to 4c) generates the drive signal Sg (Sga to Sgc) according to constant voltage control for bringing the output voltage Vo (Voa to Voc) closer to the voltage command value Vo* set along FIG. 2 (Embodiment 1).

[0082] On the other hand, when Vi (Via to Vic) ≥ VIlm, i.e., when the output current Io (Ioa to Ioc) reaches the upper limit current Ilm (NO in S215), the process proceeds to S240. In S240, the switching control unit 4 (4a to 4c) generates the drive signal Sg (Sga to Sgc) to limit the output, for example, by fixing the duty ratio to a certain limit value. The output may be limited so as to achieve a so-called drooping characteristic, in which the output voltage Vo decreases while the upper limit current Ilm remains unchanged, as shown in FIG. 4, or so as to achieve a so-called "fold-back" characteristic, in which both the output voltage Vo and the output current Io decrease.

[0083] The above-mentioned CVCC control, represented by the drooping characteristic and the "F" characteristic, is well known as converter output control, but by combining it with the constant voltage control described in the first embodiment, it is possible to quickly prevent a large temperature rise from occurring when the output current Io increases rapidly in at least one of the power supply devices 1a to 1c.

[0084] FIG. 6 shows a conceptual diagram illustrating an example of the operation of the power supply system according to the modification of the first embodiment.

[0085] In Fig. 6(a), power supply devices 1a to 1c are operating under constant voltage control, with converter unit 3a having a voltage command value Vo*=V2, while converter units 3b and 3c have a voltage command value Vo*=V1. For example, when the current consumption of load 120 is 10 [A], in Fig. 6(a), power supply device 1a supplies 5 [A] equivalent to upper limit current Ilm, power supply device 1b supplies 3 [A], and power supply device 1c supplies 2 [A].

[0086] In FIG. 6(a), when the output current of the power supply device 1a reaches the upper limit current Ilm, the power supply device 1a shifts from constant voltage control to constant current control.

[0087] As a result, in Fig. 6(b), the output power of power supply device 1a, which is under constant current control, is limited, so the output voltage is lower than in Fig. 6(a), and the output current is also reduced. Power supply devices 1b and 1c operate under constant voltage control, but for example, the output voltage of power supply device 1c, which has a relatively low output voltage and small temperature rise in Fig. 6(a), is increased (voltage command value Vo* = V2). On the other hand, in power supply device 1b, the voltage command value Vo* = V1.

[0088] In FIG. 6(b), the output current of the power supply device 1a decreases, while the output current of the power supply device 1c increases, so that a total current of 10 [A] is supplied to the load 120.

[0089] In the state of Figure 6(b), the output current of the power supply device 1a is decreasing, but when the output current decreases below a switching current that is preset to a value lower than the upper limit current Ilm, the power supply device 1a can return from constant current control to constant voltage control.

[0090] In this way, in the power supply system according to the modification of the first embodiment, in addition to the constant voltage control based on monitoring of the temperature signals Vta-Vtc in the first embodiment, CVCC control is applied to each of the power supply devices 1a-1c, which further combines constant current control for suppressing the output current Io to be equal to or less than the upper limit current Ilm. This makes it possible to more quickly prevent a concentration of temperature rises when the output current of a particular power supply device increases due to load fluctuations or the like. This makes it possible to further balance out the temperature rises among the power supply devices, thereby more reliably preventing uneven lifespans among the power supply devices.

[0091] In particular, while constant voltage control alone, which reduces the output voltage in response to temperature detection by a thermistor, generally requires a time on the order of seconds to reduce the output of converter unit 3 (3a-3b), output reduction using constant current control can be initiated in milliseconds (ms). Therefore, in addition to preventing steady-state output imbalances among multiple power supply devices, it is also possible to avoid concentration of output current, i.e., concentration of temperature rise, in a specific power supply device even when a sudden current increase occurs in some power supply devices due to load fluctuations, etc.

[0092] Embodiment 2 FIG. 7 is a block diagram illustrating an example configuration of a power supply system 100B according to the second embodiment.

[0093] 7, power supply system 100B differs from power supply system 100A (FIG. 1) according to the first embodiment in that it further includes cumulative temperature calculators 11a-11c and cumulative temperature comparator 12. Temperature signals Vta-Vtc are input to cumulative temperature calculators 11a-11c from temperature detectors 7a-7c, respectively. Cumulative temperature calculators 11a-11c output cumulative temperature signals Vtta-Vttc indicating the integrated values ​​of temperature signals Vta-Vtc, respectively, at a predetermined constant period T1 (e.g., T1=approximately 1 hour). Cumulative temperature comparator 12 generates control signals Stta-Sttc for power supply devices 1a-1c based on cumulative temperature signals Vtta-Vttc from cumulative temperature calculators 11a-11c.

[0094] 8 shows a flowchart for explaining the operation of cumulative temperature calculation units 11a-11c and cumulative temperature comparison unit 12 in power supply system 100B. That is, the functions of cumulative temperature calculation units 11a-11c and cumulative temperature comparison unit 12 can be realized by a microcomputer or the like executing the processing shown in FIG.

[0095] 8, in S310, cumulative temperature calculation units 11a to 11c acquire temperature signals Vta to Vtc from temperature detection units 7a to 7c, respectively, at a fixed period T2 (e.g., T2=10 seconds). Cumulative temperature calculation units 11a to 11c add the acquired temperature signals Vta to Vtc to their respective integrated values. In S320, cumulative temperature calculation units 11a to 11c increment count value i (i: integer) indicating the number of integrated data points by 1, and then in S330, compare the incremented count value i with a criterion value N1. The criterion value N1 is predetermined so that count value i reaches criterion value N1 at fixed period T1. The processes of S310 to S330 are repeated until count value i reaches criterion value N1 (NO determination in S330).

[0096] When the count value i reaches the determination value N1, that is, when the integrated value for the fixed period T1 is calculated, a YES determination is made in S330, and the process proceeds to S340. In S340, the cumulative temperature signals Vtta to Vttc are input from the cumulative temperature calculation units 11a to 11c to the cumulative temperature comparison unit 12. Furthermore, in the cumulative temperature calculation units 11a to 11c, the count value i and the cumulative temperature signals Vtta to Vttc (integrated values) are cleared (i=0, Vtta=Vttb=Vttc=0).

[0097] Following S340, in S350, cumulative temperature comparator 12 performs a comparison process of cumulative temperature signals Vtta-Vttc to extract some power supply units that are in a relatively high temperature state. For example, the power supply unit corresponding to the maximum value of cumulative temperature signals Vtta-Vttc, i.e., the hottest power supply unit, is extracted in S350. In other words, cumulative temperature comparator 12 corresponds to one embodiment of a "temperature history comparator."

[0098] In S360, cumulative temperature comparator 12 sets control signals Sttc-Sttc in accordance with the comparison result of S350. Of control signals Stta-Sttc, some corresponding to power supply devices determined to be in a high temperature state are set to H level, and the rest are set to L level. For example, when Vva of cumulative temperature signals Vtta-Vttc is the maximum value, that is, when power supply device 1a is determined to be in a high temperature state, control signal Stta is set to H level, while control signals Sttb and Sttc are set to L level. Control signals Stta-Sttc are input to signal controllers 8a-8c, respectively.

[0099] In power supply system 100B according to the second embodiment, signal control units 8a to 8c further perform the operations described below in response to control signals Stta to Sttc from cumulative temperature comparison unit 12.

[0100] FIG. 9 shows a flowchart illustrating additional operations of signal control units 8a to 8c in power supply system 100B according to the second embodiment.

[0101] 9, in S410, the signal control unit 8 (8a to 8c) checks the level of the control signal Stt (Stta to Sttc) from the cumulative temperature comparison unit 12. If Stt=H (YES determination in S410), in S420, the control process of FIG. 2 is modified so that a waiting time LT is set when the switching control signal Ss (Ssa to Ssc) is changed from L level to H level in S155 of FIG. 2. The waiting time LT is shorter than the constant period T1 in the cumulative temperature calculation units 11a to 11c, and is set within the range of, for example, about 1 second to 10 minutes. The waiting time LT corresponds to the "first time period."

[0102] On the other hand, when Stt=L (NO in S410), S430 does not set a standby time like S420. Alternatively, a standby time (corresponding to the "second time") shorter than S420 may be set. Not setting a standby time means setting the "second time" to zero.

[0103] As a result, in power supply system 100B according to the second embodiment, in a power supply device among power supply devices 1a-1b that is determined to be in a high temperature state, when a YES determination is made in S150 and the process proceeds to S155 during the constant voltage control process (FIG. 2), that is, when switching control signal Ss (Ssa-Ssc) changes from L level to H level, standby time LT is set. On the other hand, in the other power supply devices that are not determined to be in a high temperature state, when a YES determination is made in S150, the switching control signal Ss (Ssa-Ssc) changes from L level to H level (S155) without setting a standby time, as described in the first embodiment.

[0104] Next, an example of operation of the power supply system 100B according to the second embodiment will be described with reference to Fig. 10. In the example of operation in Fig. 10, it is assumed that the power supply device 1b has been extracted as a power supply device in a high temperature state (Sttb=H, Stta=Sttc=L) in S350 of Fig. 8.

[0105] 10, state 11 is similar to state 1 in FIG. 3, with power supply device 1a setting Ssa=H (Vo*=V2), while power supply devices 1b and 1c setting Ssb=Ssc=L (Vo*=V1). As a result, voltage rise signal Sva of power supply device 1a is at H level, and total voltage state signal Svo is also at H level. In state 11, the temperature of power supply device 1a has not yet risen, and temperature rise signals Sta to Stc are all at L level.

[0106] In state 12, similar to state 2 in Fig. 3, the temperature of power supply device 1a, whose output voltage has been increased in state 11, increases, causing temperature increase signal Sta to change from L level to H level. In response to this, in S125 in Fig. 2 (YES determination in S122), switching control signal Ssa of power supply device 1a is set to L level, and voltage command value Vo* of converter unit 3a is reduced (Vo*=V1).

[0107] State 13 is the same as state 3 in Fig. 3. That is, in response to the reduction in the voltage command value Vo* of the converter unit 3a in state 12, the voltage increase signal Sva of the power supply device 1a changes from H level to L level, thereby causing the total voltage state signal Svo to change from H level to L level.

[0108] The temperature of power supply unit 1a drops after the voltage drops, so in state 13, the temperature rise signal Sta is still at H level. Power supply units 1b and 1c are in a temperature non-rise state, and the temperature rise signals Stb and Stc are at L level. Therefore, for power supply units 1b and 1c, the judgments at S122, S122, S130, and S140 in FIG. 2 all return YES. That is, the conditions for the switching control signals Ssb and Ssc to change from L level to H level are met.

[0109] Therefore, in state 14 immediately after state 13, in power supply device 1c where control signal Sttc=L, the voltage-up signal Svc changes from L to H in response to the switching control signal Ssc changing from L to H without any waiting time. In contrast, in power supply device 1b where control signal Sttb=H, the waiting time LT has not yet elapsed, so the switching control signal Ssb is maintained at L. As a result, the voltage-up signal Svb remains at L, just as in state 13.

[0110] In state 15, the standby time LT has elapsed since state 13. Therefore, in response to the switching control signal Ssb of the power supply device 1b changing from L level to H level, the voltage rise signal Svb also changes from L level to H level.

[0111] In state 16, the temperature rise signal Stb of power supply device 1b, which has been determined to be in a high temperature state, changes from L level to H level before the temperature rise signal Stc of power supply device 1c does, and as a result, the switching control signal Ssb of power supply device 1b changes from H level to L level.

[0112] As a result, in state 17, the voltage rise signal Svb of power supply device 1b changes from H level to L level. Also, in power supply device 1c, where the switching control signal Ssc is set to H, the temperature rise signal Stc changes from L level to H level. In response to this, the switching control signal Ssc of power supply device 1c changes from H level to L level.

[0113] As a result, in state 18, the switching control signals Ssa-Ssc of power supply devices 1a-1c all go low again, and the overall voltage state signal Svo returns to low. Meanwhile, there is a delay in the temperature drop of power supply devices 1b and 1c, so while the temperature rise signal Sta (of power supply device 1a) is low, the temperature rise signals Stb and Stc remain high. Therefore, while the switching control signals Ssb and Ssc remain low, only the switching control signal Ssa is changed to high.

[0114] In state 19, in accordance with the switching control signals Ssa to Ssc set in state 18, the voltage rise signal Sva of power supply device 1a is at H level, while the voltage rise signals Svb and Svc of power supply devices 1b and 1c are at L level. The temperature rise signals Sta to Stc are unchanged from state 18.

[0115] Furthermore, if the temperature conditions of power supply devices 1a-1c change and the magnitude relationship of cumulative temperature signals Vtta-Vttc changes, the power supply device that is determined to be in a relatively high temperature state will change (S350), and the settings of switching control signals Ssa-Ssc will also change. By combining this control, in a power supply device that is in a relatively high temperature state (for example, a power supply device corresponding to the maximum cumulative temperature signals Vtta-Vttc), even when the conditions for increasing the output voltage are met, the timing at which the output voltage actually increases and the temperature rises can be delayed. In this way, by taking into account the temperature history over a certain period of time, it is expected that the lengths of time during which power supply devices 1a-1c will be in a high temperature state will be balanced.

[0116] In this way, in the power supply system according to the second embodiment, similar to the first embodiment, it is possible to balance the temperature rise between the power supply devices through simple control, and also to further balance the temperature rise between the power supply devices connected in parallel by taking into account past temperature history.

[0117] In the second embodiment, an example was described in which one power supply unit with the largest cumulative temperature signal was extracted from three power supply units for which a standby time is set. However, it is possible to extract a portion of power supply units that are in a relatively high temperature state from multiple power supply units connected in parallel under any conditions based on the temperature history (cumulative temperature signal).

[0118] Furthermore, the standby time LT can be adapted to an appropriate value through actual equipment testing or simulation, taking into consideration the size and thermal load of the power supply device, or load capacity, etc. The standby time LT may be variably set so that the standby time LT becomes longer as the temperature rises, depending on the degree of the high temperature state, for example, the value of the cumulative temperature signal Vtt (Vtta to Vttc) of the power supply device that is determined to be in a high temperature state.

[0119] Embodiment 3 FIG. 11 is a block diagram illustrating an example configuration of a power supply system 100C according to the third embodiment.

[0120] Referring to FIG. 11, power supply system 100C differs from power supply system 100A (FIG. 1) of embodiment 1 in that it further includes cumulative temperature calculation units 11a to 11c similar to those of embodiment 2, a cumulative temperature determination unit 13, and a replacement information display unit 14.

[0121] 7, cumulative temperature calculation units 11a-11c output cumulative temperature signals Vtta-Vttc at a predetermined period T1 (for example, T1=approximately 1 hour), respectively. Cumulative temperature determination unit 13 determines the remaining lifespan used to determine whether or not power supply devices 1a-1c need to be replaced based on cumulative temperature signals Vtta-Vttc, i.e., past temperature history. For example, cumulative temperature determination unit 13 determines the remaining lifespan of power supply devices 1a-1c.

[0122] The replacement information display unit 14 is provided to display the result of the determination by the cumulative temperature determination unit 13, and can be configured with an LED (Light Emitting Diode) lamp, LED segments, a liquid crystal display, or the like (not shown).

[0123] 12 shows a flowchart for explaining the operation of cumulative temperature calculation units 11a to 11c and cumulative temperature determination unit 13 in power supply system 100C. That is, the functions of cumulative temperature calculation units 11a to 11c and cumulative temperature determination unit 13 can be realized by a microcomputer or the like executing the processing shown in FIG.

[0124] 12, cumulative temperature calculation units 11a to 11c execute steps S310 to S330 similar to those in Fig. 7 to calculate cumulative temperature signals Vtta to Vttc as integrated values ​​of temperature signals Vta to Vtc for each fixed period T1. In the third embodiment as well, the fixed period T1 can be set to about one hour.

[0125] In S510, at regular intervals T1, the cumulative temperature signals Vtta to Vttc are input from the cumulative temperature calculation units 11a to 11c to the cumulative temperature determination unit 13. Also, in S510, similar to S340 (FIG. 8), the count value i and the cumulative temperature signals Vtta to Vttc are cleared in the cumulative temperature calculation units 11a to 11c (i=0, Vtta=Vttb=Vttc=0).

[0126] In S520, the cumulative temperature determination unit 13 compares each of the cumulative temperature signals Vtta-Vttc at regular intervals with a specified temperature value Vjd. The specified temperature value Vjd can be determined taking into consideration the rated temperature. For example, a temperature slightly lower than the rated temperature (e.g., 75°C) can be set as the specified temperature (70°C), and the specified temperature value Vjd can be set in advance to correspond to the cumulative temperature signals Vtta-Vttc that are expected to rise when the specified temperature continues for one hour.

[0127] The cumulative temperature determination unit 13 has temperature rise count values ​​Na to Nc corresponding to the power supply devices 1a to 1b, respectively. Na to Nc are indicated by integers that are set to initial values ​​(Na=Nb=Nc=0) when the power supply system 100C starts to be used.

[0128] When any of the cumulative temperature signals Vtta to Vttc is equal to or greater than the temperature specified value Vjd (when the determination at S520 is YES), at S530, the temperature rise count values Na to Nc are updated according to the comparison result at S520. Specifically, the temperature rise count value N (Na to Nc) corresponding to the power supply device for which the cumulative temperature signal Vtt (Vtta to Vttc) is equal to or greater than the temperature specified value Vjd is incremented by 1, while the remaining temperature rise count values are maintained. For example, when Vtta > Vjd, Vttb < Vjd, and Vttc < Vjd, at S530, the temperature rise count value Na is incremented, while the temperature rise count values Nb and Nc are maintained.

[0129] Following S530, at S540, the cumulative temperature determination unit 13 compares the updated temperature rise count values Na to Nc by S530 with the upper limit number Nt. When at least one of the temperature rise count values Na to Nc reaches the upper limit number Nt (when the determination at S540 is YES), the cumulative temperature determination unit 13 identifies, by S55, the power supply device for which the temperature rise count value N (Na to Nc) has reached the upper limit number Nt and generates a replacement scheduled signal Sch.

[0130] On the other hand, when all of the temperature rise count values Na to Nc are smaller than the upper limit number Nt (when the determination at S540 is NO), S550 is skipped and the processing in the cycle (T1) is terminated. Also, in S520, when all of the cumulative temperature signals Vva to Vvc are smaller than the temperature specified value Vjd (when the determination at S520 is NO), the values of the temperature rise count values Na to Nc are maintained by S560 and the processing in the cycle (T1) is terminated.

[0131] 11, the replacement schedule signal Sch generated in S550 is input from cumulative temperature determination unit 13 to replacement information display unit 14. Based on the replacement schedule signal Sch, replacement information display unit 14 executes a display to notify the user that a power supply device whose temperature rise count value N (Na to Nc) has reached the upper limit number of times Nt is to be replaced. For example, the user can be notified of a power supply device to be replaced by selectively lighting three LED lamps arranged corresponding to power supply devices 1a to 1c. Alternatively, the user can be notified of a power supply device to be replaced by LED segments or by displaying text on an LCD display.

[0132] In this way, the power supply system according to the third embodiment makes it possible to determine the remaining lifespan of a plurality of parallel-connected power supply devices based on their past temperature history, thereby providing the user with information to consider when planning replacement, thereby improving user convenience.

[0133] It is also possible to combine the second and third embodiments and configure the system to include both the cumulative temperature comparing unit 12 and the cumulative temperature determining unit 13. In the power supply system according to the second or third embodiment and in a power supply system according to a combination of the second and third embodiments, each of the power supply devices 1a to 1c can be provided with the CVCC control function according to the modified example of the first embodiment.

[0134] Embodiment 4 FIG. 13 is a block diagram illustrating an example configuration of a power supply system 100D according to the fourth embodiment.

[0135] 13, power supply system 100D differs from power supply system 100C (FIG. 11) according to the third embodiment in that it further includes signal isolation circuit units 16a-16c. Furthermore, in power supply system 100D, signal isolation circuit units 16a-16c are provided, so that temperature detection units 7a-7c can be arranged so as to be directly attached to heat-generating units (circuit elements) connected to the "high-voltage path" inside converter units 3a-3c, which have a non-insulated configuration. Note that if converter units 3a-3c are non-insulated, the high-voltage (positive) terminal of power supply 110 and the high-voltage (positive) terminal of load 120 are electrically connected without being insulated by a transformer or the like.

[0136] Here, the "high-voltage side path" refers to the path along which current flows in each of converter units 3a to 3c from the high-voltage side (positive electrode) terminal of power supply 110 to the high-voltage side (positive electrode) terminal of load 120. For example, temperature detection units 7a to 7c can be attached to the connection points of the heat generating parts, such as rectifier diode 9a, smoothing capacitor 13a, or board pattern (not shown), with the high-voltage side path.

[0137] Similarly, in each of converter units 3a to 3c, the path through which current returns from the low-voltage side (negative) terminal of load 120 to the low-voltage side (negative) terminal of power supply 110 is defined as the "low-voltage side path." When converter units 3a to 3c are configured as non-insulated types, the output sides (load sides) of converter units 3a to 3c are connected in parallel to load 120. Therefore, in each of converter units 3a to 3c, not all of the current flowing through the high-voltage side (current flowing toward load 120) necessarily returns as current flowing through the low-voltage side (current flowing toward power supply 110). For this reason, in order to detect a temperature rise in converter units 3a to 3b, it is preferable that temperature detection units 7a to 7c accurately measure the temperature of the heat-generating portion on the high-voltage side.

[0138] 13, temperature detection units 7a-7c output temperature signals Vtha-Vthc indicating the measured temperature values ​​of the heat generating units on the high voltage side. Because temperature detection units 7a-7c are directly attached to the heat generating units on the high voltage side, the temperature signals Vtha-Vthc are voltage signals based on the potential on the high voltage side, and therefore cannot be directly input to signal control units 8a-8c, cumulative temperature calculation units 11a-11c, etc., which operate based on the potential on the low voltage side.

[0139] Therefore, the signal isolation circuits 16a-16c receive the temperature signals Vtha-Vthc from the temperature detection units 7a-7c and output the temperature signals Vtia-Vtic that are electrically isolated from the high-voltage sides of the converter units 3a-3c. The temperature signals Vtia-Vtic are generated so as to have the same amplitude as the temperature signals Vtha-Vthc, with the potential on the low-voltage side as the reference. For example, the signal isolation circuits 16a-16c can be configured using photocouplers or the like, but any desired elements and circuit configurations can be used.

[0140] The temperature signals Vtia-Vtic output from the signal isolation circuit units 16a-16c are input to the signal control units 8a-8c and the cumulative temperature calculation units 11a-11c, similar to the temperature signals Vta-Vtc in embodiment 3 (FIG. 11). In the power supply system 100D according to embodiment 4, the signal control units 8a-8c and the cumulative temperature calculation units 11a-11c operate using the temperature signals Vtia-Vtic from the signal isolation circuit units 16a-16c as the temperature signals Vta-Vtc in FIG.

[0141] Therefore, in the power supply system according to the fourth embodiment, the temperature detection units 7a to 7c are directly attached to the heat generating units on the high voltage side, and based on the temperatures (temperature signals Vtha to Vthc) measured with high precision, control can be performed in the power supply system 100C according to the third embodiment. As a result, the accuracy of control is improved, and temperature rises between the power supply devices can be further balanced.

[0142] 1 (Embodiment 1), the temperature signals Vtia-Vtic from the signal isolation circuits 16a-16c can also be used as the temperature signals Vta-Vtc input to the signal control units 8a-8c. Also, in FIG. 7 (Embodiment 2), the temperature signals Vtia-Vtic from the signal isolation circuits 16a-16c can also be used as the temperature signals Vta-Vtc input to the signal control units 8a-8c and the cumulative temperature calculation units 11a-11c.

[0143] That is, by appropriately combining embodiment 4 with each of embodiments 1 to 3 or a combination thereof, the temperature measurement by the temperature detection units 7a to 7c can be made more accurate. As a result, as described above, the accuracy of control is improved, and the temperature rises between the power supply devices can be further balanced.

[0144] Embodiment 5. FIG. 14 is a block diagram illustrating an example configuration of a power supply system 100E according to the fifth embodiment.

[0145] 14, power supply system 100E differs from power supply system 100C (FIG. 11) according to the third embodiment in that power supply devices 1a-1c further include power insulation circuit units 17a-17c. Power insulation circuit units 17a-17c comprehensively describe circuit elements for electrically insulating load 120 from the output sides (load sides) of converter units 3a-3c, the temperature of which is to be measured, and can be realized, for example, by an insulation converter, such as a flyback converter or a half-bridge converter, connected between non-insulation converter units 3a-3c and load 120.

[0146] Alternatively, the converter units 3a to 3c themselves may be configured as isolated converters such as flyback converters or half-bridge converters that include transformers, so that the power isolation circuit units 17a to 17c are realized by the transformers included in the converter units 3a to 3c, unlike the example in Figure 17.

[0147] By electrically insulating the power supply 110 and the load 120 using the power insulation circuits 17a to 17c, the current flowing on the high-voltage side (current flowing toward the load 120) and the current flowing on the low-voltage side (current flowing toward the power supply 110) become equal in each of the converter units 3a to 3c. As a result, when detecting a temperature rise in the converter units 3a to 3b, the same results can be obtained regardless of whether the temperature of the heat-generating part on the high-voltage side or the low-voltage side is measured.

[0148] For this reason, in power supply system 100E, temperature detection units 7a-7c can be arranged so as to be directly attached to heat-generating parts on the "low-voltage side," which does not require signal insulation. Temperature signals Vtla-Vtlc output from temperature detection units 7a-7c attached directly to heat-generating parts on the low-voltage side are input to signal control units 8a-8c and cumulative temperature calculation units 11a-11c, similar to temperature signals Vta-Vtc in embodiment 3 (FIG. 11), without passing through signal isolation circuits 16a-16c shown in FIG.

[0149] In power supply system 100E according to the fifth embodiment, signal control units 8a-8c and cumulative temperature calculation units 11a-11c operate using temperature signals Vtla-Vtlc from temperature detection units 7a-7c as temperature signals Vta-Vtc in FIG.

[0150] Therefore, in the power supply system according to the fifth embodiment, the temperature detection units 7a to 7c are directly attached to the heat generating unit on the low voltage side of the converter units 3a to 3c configured to electrically insulate the power supply 110 and the load 120, and thus the power supply system 100C according to the third embodiment can perform control based on the temperatures (temperature signals Vtla to Vtlc) measured with high accuracy. As a result, no configuration for signal isolation is required, and the accuracy of control is improved, thereby making it possible to further balance the temperature rise between the power supply devices.

[0151] 1 (Embodiment 1), by providing electrical insulation between power supply 110 and load 120 using power insulation circuits 17a-17c, it is possible to use temperature signals Vtla-Vtlc from temperature detectors 7a-7c attached directly to heat-generating components on the low voltage side as temperature signals Vta-Vtc input to signal controllers 8a-8c. Also in FIG. 7 (Embodiment 2), by providing power insulation circuits 17a-17c, it is possible to use temperature signals Vtla-Vtlc from temperature detectors 7a-7c attached directly to heat-generating components on the low voltage side as temperature signals Vta-Vtc input to signal controllers 8a-8c and cumulative temperature calculators 11a-11c.

[0152] That is, by appropriately combining embodiment 5 with each of embodiments 1 to 3 or a combination thereof, the temperature measurement by the temperature detection units 7a to 7c can be made more accurate. As a result, as described above, no signal isolation configuration is required, and the accuracy of control is improved, thereby making it possible to further balance the temperature rise between the power supply devices.

[0153] In addition, we would like to confirm that with regard to the multiple embodiments described above, it is intended from the beginning of the application that the configurations described in each embodiment may be combined appropriately, including combinations not mentioned in the specification, within the scope that does not result in inconsistencies or contradictions.

[0154] Furthermore, in the first to fifth embodiments, a configuration in which three power supply devices are connected in parallel has been exemplified, but in a power supply system in which two or four or more power supply devices are connected in parallel to supply power to a load, it is possible to apply the first embodiment, the modified example of the first embodiment, the second embodiment, the third embodiment, the fourth embodiment, and the fifth embodiment, or a combination thereof.

[0155] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0156] 1a to 1c power supply unit, 3a to 3c converter section, 4a to 4c switching control section, 5a to 5c output voltage detection section, 6a to 6c output current detection section, 7a to 7c temperature detection section, 8 signal control section, 8a to 8c signal control section, 9a to 9c rectifier diode, 10a to 10c semiconductor switching element, 11a to 11c cumulative temperature calculation section, 12 cumulative temperature comparison section, 13 cumulative temperature judgment section, 14 replacement information display section, 15a to 15c smoothing capacitor, 15t, 15v signal generation circuit, 16a to 16c signal insulation circuit section, 17a to 17c power insulation circuit section, 100A to 100C power supply system, 110 power supply, 120 load, Ilm upper limit current, Ioa to Ioc output current, LT standby time, Na to Nc temperature rise count value, N1, VIlm Judgment value, Nt upper limit number of times, Sch replacement schedule signal, Sga~Sgc drive signal, Ssa~Ssc switching control signal, Sta, Stb, Stc temperature rise signal, Sta*~Stc* temperature abnormality signal, Sto overall temperature abnormality signal, Stta~Sttc control signal, Sva~Svc voltage rise signal, Svo overall voltage status signal, VHlim voltage upper limit value, VHt voltage threshold, VTHlm temperature upper limit value, VTHt temperature threshold, Via~Vic output current signal, Voa~Voc output voltage, Vo* voltage command value, Vt, Vta~Vtc, Vtha~Vthc, Vtla~Vtlc temperature signals, Vtia~Vtic temperature signal (after insulation), Vtta~Vttc accumulated temperature signal, Vva~Vvc output voltage signal.

Claims

1. 1. A power supply system, comprising: A plurality of power supply units having outputs connected in parallel, Each of the plurality of power supply devices a converter unit including a semiconductor switching element and supplying an output voltage and an output current; a temperature detection unit that measures the temperature of the converter unit; an output voltage detection unit that measures the output voltage of the converter unit; a switching control unit that generates a drive signal for controlling the semiconductor switching element in accordance with constant voltage control that causes the detected voltage of the output voltage detection unit to approach a voltage command value; a signal control unit for increasing or decreasing the voltage command value in the switching control unit based on a comparison between the temperature detected by the temperature detection unit and a temperature threshold value, the signal control units share information related to setting of the voltage command value in each of the power supply devices with each other; Among the plurality of power supply devices, in a power supply device in a first temperature state in which the detected temperature is higher than the temperature threshold, the signal control unit sets the voltage command value to a first voltage value, while in a power supply device in a second temperature state in which the detected temperature is equal to or lower than the temperature threshold, the signal control unit sets the voltage command value to a second voltage value higher than the first voltage value; the signal control unit further compares the detected voltage by the output voltage detection unit with an output voltage threshold; when the voltage command value is the first voltage value, the signal control unit increases the voltage command value from the first voltage value to the second voltage value when the detected temperature is equal to or lower than the temperature threshold and the detected voltages in all of the plurality of power supply devices are equal to or lower than the output voltage threshold.

2. A power supply system, A plurality of power supply units having outputs connected in parallel, Each of the plurality of power supply devices a converter unit including a semiconductor switching element and supplying an output voltage and an output current; a temperature detection unit that measures the temperature of the converter unit; an output voltage detection unit that measures the output voltage of the converter unit; a switching control unit that generates a drive signal for controlling the semiconductor switching element in accordance with constant voltage control that causes the detected voltage of the output voltage detection unit to approach a voltage command value; a signal control unit for increasing or decreasing the voltage command value in the switching control unit based on a comparison between the temperature detected by the temperature detection unit and a temperature threshold value, the signal control units share information related to setting of the voltage command value in each of the power supply devices with each other; Among the plurality of power supply devices, in a power supply device in a first temperature state in which the detected temperature is higher than the temperature threshold, the signal control unit sets the voltage command value to a first voltage value, while in a power supply device in a second temperature state in which the detected temperature is equal to or lower than the temperature threshold, the signal control unit sets the voltage command value to a second voltage value higher than the first voltage value; the signal control unit of each power supply device is configured to determine whether the power supply device is in the first temperature state or the second temperature state, depending on a comparison result between the detected temperature and the temperature threshold value in each of the first temperature state and the second temperature state; The temperature threshold value is set to a lower value in the first temperature state than in the second temperature state.

3. A power supply system, A plurality of power supply units having outputs connected in parallel, Each of the plurality of power supply devices a converter unit including a semiconductor switching element and supplying an output voltage and an output current; a temperature detection unit that measures the temperature of the converter unit; an output voltage detection unit that measures the output voltage of the converter unit; a switching control unit that generates a drive signal for controlling the semiconductor switching element in accordance with constant voltage control that causes the detected voltage of the output voltage detection unit to approach a voltage command value; a signal control unit for increasing or decreasing the voltage command value in the switching control unit based on a comparison between the temperature detected by the temperature detection unit and a temperature threshold value, the signal control units share information related to setting of the voltage command value in each of the power supply devices with each other; Among the plurality of power supply devices, in a power supply device in a first temperature state in which the detected temperature is higher than the temperature threshold, the signal control unit sets the voltage command value to a first voltage value, while in a power supply device in a second temperature state in which the detected temperature is equal to or lower than the temperature threshold, the signal control unit sets the voltage command value to a second voltage value higher than the first voltage value; a power supply system in which the plurality of power supply devices are controlled so that the voltage command values ​​of all of the plurality of power supply devices are not aligned to one of the first voltage value and the second voltage value.

4. A power supply system, A plurality of power supply units having outputs connected in parallel, Each of the plurality of power supply devices a converter unit including a semiconductor switching element and supplying an output voltage and an output current; a temperature detection unit that measures the temperature of the converter unit; an output voltage detection unit that measures the output voltage of the converter unit; a switching control unit that generates a drive signal for controlling the semiconductor switching element in accordance with constant voltage control that causes the detected voltage of the output voltage detection unit to approach a voltage command value; a signal control unit for increasing or decreasing the voltage command value in the switching control unit based on a comparison between the temperature detected by the temperature detection unit and a temperature threshold value, the signal control units share information related to setting of the voltage command value in each of the power supply devices with each other; Among the plurality of power supply devices, in a power supply device in a first temperature state in which the detected temperature is higher than the temperature threshold, the signal control unit sets the voltage command value to a first voltage value, while in a power supply device in a second temperature state in which the detected temperature is equal to or lower than the temperature threshold, the signal control unit sets the voltage command value to a second voltage value higher than the first voltage value; the first voltage value is lower than a rated value of a supply voltage to a load connected to an output of the plurality of power supply devices; The second voltage value is higher than the rated voltage value.

5. A power supply system, A plurality of power supply units having outputs connected in parallel, Each of the plurality of power supply devices a converter unit including a semiconductor switching element and supplying an output voltage and an output current; a temperature detection unit that measures the temperature of the converter unit; an output voltage detection unit that measures the output voltage of the converter unit; a switching control unit that generates a drive signal for controlling the semiconductor switching element in accordance with constant voltage control that causes the detected voltage of the output voltage detection unit to approach a voltage command value; a signal control unit for increasing or decreasing the voltage command value in the switching control unit based on a comparison between the temperature detected by the temperature detection unit and a temperature threshold value, the signal control units share information related to setting of the voltage command value in each of the power supply devices with each other; Among the plurality of power supply devices, in a power supply device in a first temperature state in which the detected temperature is higher than the temperature threshold, the signal control unit sets the voltage command value to a first voltage value, while in a power supply device in a second temperature state in which the detected temperature is equal to or lower than the temperature threshold, the signal control unit sets the voltage command value to a second voltage value higher than the first voltage value; The power supply system includes: a temperature history comparison unit for comparing the histories of temperatures detected by the temperature detection units in the plurality of power supply devices and extracting a portion of the plurality of power supply devices that are in a relatively high temperature state, each of the signal control units included in the part of the power supply devices increases the voltage command value after a first time has elapsed when increasing the voltage command value from the first voltage value to the second voltage value in response to an increase in the detected temperature; the signal control unit that is not included in the some of the power supply devices increases the voltage command value from the first voltage value to the second voltage value in response to an increase in the detected temperature, after a second time period that is shorter than the first time period has elapsed.

6. The signal control unit of each power supply device is configured to determine whether the power supply device is in the first temperature state or the second temperature state according to a comparison result between the detected temperature and the temperature threshold value in each of the first temperature state and the second temperature state; The power supply system according to claim 1 , wherein the temperature threshold is set to a lower value in the first temperature state than in the second temperature state.

7. the converter unit is configured to perform DC voltage conversion by controlling the on / off of the semiconductor switching element, 7. The power supply system according to claim 1, wherein each of the signal control units further compares the detected temperature with an upper temperature limit value, and when it is detected that the detected temperature in at least one of the plurality of power supply devices is higher than the upper temperature limit value, it generates the drive signal to fix the semiconductor switching element of the converter unit in an off state.

8. 7. The power supply system according to claim 1, wherein, at the time of startup of the power supply system, initial values ​​of the voltage command values ​​of the plurality of power supply devices are set so that all of the voltage command values ​​are not aligned to one of the first voltage value and the second voltage value.

9. 7. The power supply system according to claim 1, wherein the temperature detection unit includes a thermistor fixed to a substrate on which components of the converter unit are mounted.

10. A power supply system as described in any one of claims 1, 2, and 4 to 6, wherein the plurality of power supply devices are controlled so that the voltage command values ​​of all of the plurality of power supply devices are not aligned to either the first voltage value or the second voltage value.

11. the first voltage value is lower than a rated value of a supply voltage to a load connected to an output of the plurality of power supply devices; 7. The power supply system according to claim 1, wherein the second voltage value is higher than the rated voltage value.

12. Each of the plurality of power supply devices further including an output current detection unit that measures an output current of the converter unit; Each of the signal control units is 7. The power supply system according to claim 1, wherein when the output current detected by the output current detection unit reaches a predetermined upper limit current, the drive signal is generated to limit the output of the converter unit so as not to increase the output current any further.

13. a temperature history comparison unit for comparing the histories of temperatures detected by the temperature detection units in the plurality of power supply devices and extracting a portion of the plurality of power supply devices that are in a relatively high temperature state, each of the signal control units included in the part of the power supply devices increases the voltage command value after a first time has elapsed when increasing the voltage command value from the first voltage value to the second voltage value in response to an increase in the detected temperature; 10. The power supply system according to claim 1, wherein the signal control unit that is not included in the some of the power supply devices increases the voltage command value from the first voltage value to the second voltage value in response to an increase in the detected temperature, after a second time period that is shorter than the first time period has elapsed.

14. Each of the plurality of power supply devices The temperature sensor further includes a cumulative temperature calculation unit that outputs an integrated value of the detected temperature at predetermined fixed intervals, 6. The power supply system according to claim 5, wherein the temperature history comparison unit extracts the part of the power supply devices based on a comparison of the integrated values ​​of the plurality of power supply devices.

15. Each of the plurality of power supply devices The temperature sensor further includes a cumulative temperature calculation unit that outputs an integrated value of the detected temperature at predetermined fixed intervals, The power supply system according to claim 13 , wherein the temperature history comparison unit extracts the part of the power supply devices based on a comparison of the integrated values ​​of the plurality of power supply devices.

16. a temperature history determination unit that determines a remaining life of the plurality of power supply devices based on a history of temperatures detected by the temperature detection unit of each of the plurality of power supply devices, and determines whether or not replacement of the plurality of power supply devices is necessary; 7. The power supply system according to claim 1, further comprising a display unit for notifying a user of a result of the determination made by said temperature history determination unit.

17. Each of the plurality of power supply devices The temperature sensor further includes a cumulative temperature calculation unit that outputs an integrated value of the detected temperature at predetermined fixed intervals, 17. The power supply system of claim 16, wherein the temperature history determination unit counts, for each of the plurality of power supply devices, the number of times that the integrated value over the constant period output from the cumulative temperature calculation unit exceeds a predetermined determination value, and when the counted number reaches a predetermined upper limit number, determines that the power supply device needs to be replaced.

18. each of the plurality of power supply devices is connected between a power source and a load connected to an output of the plurality of power supply devices; the converter unit of each of the plurality of power supply devices is configured as a non-insulated converter, the temperature detection unit is directly attached to a circuit element connected to a high-voltage side of the converter unit through which a current flows from the power supply to the load, Each of the plurality of power supply devices 7. The power supply system according to claim 1, further comprising a signal isolation circuit section for isolating an output signal from the temperature detection section indicating the detected temperature and inputting the signal to the signal control section.

19. each of the plurality of power supply devices is connected between a power source and a load connected to an output of the plurality of power supply devices; the converter unit of each of the plurality of power supply devices is configured as a non-insulated converter, the temperature detection unit is directly attached to a circuit element connected to a high-voltage side path through which a current flows from the power supply to the load in the converter unit, Each of the plurality of power supply devices 15. The power supply system according to claim 14, further comprising a signal isolation circuit section for isolating an output signal from said temperature detection section, which indicates said detected temperature, and inputting the signal to said signal control section and said cumulative temperature calculation section.

20. each of the plurality of power supply devices is connected between a power source and a load connected to an output of the plurality of power supply devices; the converter unit of each of the plurality of power supply devices is configured as a non-insulated converter, the temperature detection unit is directly attached to a circuit element connected to a high-voltage side path through which a current flows from the power supply to the load in the converter unit, Each of the plurality of power supply devices 16. The power supply system according to claim 15, further comprising a signal isolation circuit section for isolating an output signal from said temperature detection section, which indicates said detected temperature, and inputting the signal to said signal control section and said cumulative temperature calculation section.

21. each of the plurality of power supply devices is connected between a power source and a load connected to an output of the plurality of power supply devices; the converter unit of each of the plurality of power supply devices is configured as a non-insulated converter, the temperature detection unit is directly attached to a circuit element connected to a high-voltage side path through which a current flows from the power supply to the load in the converter unit, Each of the plurality of power supply devices 18. The power supply system according to claim 17, further comprising a signal isolation circuit section for isolating an output signal from said temperature detection section, which indicates said detected temperature, and inputting the signal to said signal control section and said cumulative temperature calculation section.

22. each of the plurality of power supply devices is connected between a power source and a load connected to an output of the plurality of power supply devices; Each of the plurality of power supply devices further includes a power isolation circuit unit for electrically insulating the power supply from the load; the temperature detection unit is directly attached to a circuit element connected to a low-voltage side path through which a current flows toward the power supply in the converter unit of each of the plurality of power supply devices, 7. The power supply system according to claim 1, wherein an output signal from said temperature detection section indicating said detected temperature is input to said signal control section without signal insulation.

23. each of the plurality of power supply devices is connected between a power source and a load connected to an output of the plurality of power supply devices; Each of the plurality of power supply devices further includes a power isolation circuit unit for electrically insulating the power supply from the load; the temperature detection unit is directly attached to a circuit element connected to a low-voltage side path through which a current flows toward the power supply in the converter unit of each of the plurality of power supply devices, 15. The power supply system according to claim 14, wherein an output signal from said temperature detection unit indicating said detected temperature is input to said signal control unit and said cumulative temperature calculation unit without signal insulation.

24. each of the plurality of power supply devices is connected between a power source and a load connected to an output of the plurality of power supply devices; Each of the plurality of power supply devices further includes a power isolation circuit unit for electrically insulating the power supply from the load; the temperature detection unit is directly attached to a circuit element connected to a low-voltage side path through which a current flows toward the power supply in the converter unit of each of the plurality of power supply devices, 16. The power supply system according to claim 15, wherein an output signal from said temperature detection unit indicating said detected temperature is input to said signal control unit and said cumulative temperature calculation unit without signal insulation.

25. each of the plurality of power supply devices is connected between a power source and a load connected to an output of the plurality of power supply devices; Each of the plurality of power supply devices further includes a power isolation circuit unit for electrically insulating the power supply from the load; the temperature detection unit is directly attached to a circuit element connected to a low-voltage side path through which a current flows toward the power supply in the converter unit of each of the plurality of power supply devices, 18. The power supply system according to claim 17, wherein an output signal from said temperature detection unit indicating said detected temperature is input to said signal control unit and said cumulative temperature calculation unit without signal insulation.

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