Power conversion device and control method for power conversion device

Abstract

A power conversion device 100 includes: a plurality of power supply circuits 110a, 110b, 110c including storage media for storing characteristic information; current detection units 120a, 120b, 120c for detecting the output currents of the respective power supply circuits; and a control unit 140 to which the power supply circuits and the current detection units are connected. The control unit 140 acquires the characteristic information from the power supply circuits 110a, 110b, 110c and the output currents of the respective power supply circuits 110a, 110b, 110c from the current detection units 120a, 120b, 120c, and controls the plurality of power supply circuits 110a, 110b, 110c on the basis of the acquired characteristic information and output current information.

Description

Power conversion device and control method for power conversion device

[0001] The present invention relates to a power conversion device that receives power from an external source and supplies the power to a load, and more particularly to a power conversion device that has a plurality of power supply circuits that perform power conversion.

[0002] BACKGROUND ART Conventionally, a power conversion device is known that operates multiple power supply circuits in parallel to enable a large amount of power to be supplied to a load, and ensures high reliability by enabling the power supply to continue even if one of the power supply circuits fails.

[0003] As an example of such a power conversion device, Patent Document 1 discloses a power supply unit having a plurality of power supply modules operating in parallel, in which the power-on / power-off of the plurality of power supply modules is controlled in accordance with the required output current so that the power supply modules operate within a load factor range in which the efficiency of each power supply module is high.

[0004] Furthermore, Patent Document 2 discloses a parallel operation power supply device that detects output currents output from a plurality of switching regulators, controls the output voltage of each switching regulator so that the output current from each switching regulator is the same, and, if the output current falls outside a load current range that is set in advance based on the efficiency of the switching regulator, increases or decreases the number of operating power supplies of the switching regulators so that the output current falls within the load current range.

[0005] JP 2010-158098 A JP 2013-150390 A

[0006] In the conventional power conversion device described above, each power supply circuit is controlled based on a predetermined characteristic (load current-efficiency characteristic), and therefore when replacing or adding a power supply circuit, it is necessary to apply a power supply circuit having the same characteristic.

[0007] However, when reusing a power supply circuit that has been used in another power conversion device, the characteristics of the power supply circuit may have changed due to usage conditions, deterioration over time, etc. Furthermore, if the power supply circuit has been upgraded by adopting more efficient power devices than before for some of the components that make up the power supply circuit, the characteristics of the power supply circuit will have improved.

[0008] In this way, when the characteristics of the applied power supply circuit differ from the preset characteristics, a decrease in efficiency occurs due to the characteristic error, making it difficult to operate the power conversion device with high efficiency.

[0009] An object of the present invention is to provide a power conversion device that solves the above-mentioned problems of the conventional technology and can realize highly efficient parallel operation of power supply circuits.

[0010] In one preferred aspect of the present invention, the power conversion device includes a plurality of power supply circuits connected in parallel, each of which has a storage medium for storing characteristic information relating to its own characteristics and converts externally supplied power and supplies the converted power to a load; a plurality of current detection units provided corresponding to each of the power supply circuits, which detect the output current supplied from the corresponding power supply circuit to the load and output the output current information; and a control unit connected to the plurality of power supply circuits and the plurality of current detection units, which obtains characteristic information from each of the power supply circuits and output current information of each power supply circuit from the current detection units, and controls the plurality of power supply circuits based on the obtained characteristic information and output current information.

[0011] According to the present invention, in a power conversion device that operates a plurality of power supply circuits in parallel, even if the efficiency of each power supply circuit is unknown, it is possible to operate the power conversion device with high efficiency.

[0012] Other objects and novel features of the present invention will become apparent from the description and drawings of this specification.

[0013] 1 is a schematic diagram showing the overall configuration of a power conversion device according to a first embodiment of the present invention; FIG. 2 is a simplified block diagram showing the hardware configuration of a control unit; FIG. 3 is a data configuration diagram showing the configuration of characteristic data stored in a storage medium; FIG. 4 is a flowchart showing the flow of processing performed by the control unit when a power supply circuit is attached; FIG. 5 is a conceptual diagram for explaining the concepts of a usage current range and maximum power conversion efficiency; FIG. 6 is a graph showing an efficiency curve drawn based on efficiency data; FIG. 7 is a flowchart showing the flow of processing performed by the control unit when power supply to a load starts; FIG. 8 is a flowchart showing the flow of processing performed by the control unit when the load current fluctuates; FIG. 9 is a flowchart showing the flow of processing performed by the control unit when the power supply circuit is removed from the power conversion device; FIG. 10 is a graph conceptually showing the relationship between the operating time and the on-resistance of a power device; FIG. 11 is a screen configuration diagram showing an example of a monitor screen showing the operating status of the power conversion device; FIG. 12 is a schematic diagram showing the overall configuration of a power conversion device according to a second embodiment of the present invention; FIG. 13 is a schematic diagram showing the overall configuration of a power conversion device according to a third embodiment of the present invention; FIG. 14 is a data configuration diagram showing the configuration of characteristic data stored in a storage medium provided in the power supply circuit; FIG. 15 is a flowchart showing the flow of processing performed by the control unit when power supply to a load starts;

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, parts having the same configuration and / or function are designated by the same reference numerals. In the following description, unless particularly necessary, duplicate descriptions of parts having the same function and / or configuration will be omitted.

[0015] First Embodiment FIG. 1 is a schematic diagram showing the overall configuration of a power conversion device according to a first embodiment of the present invention.

[0016] In FIG. 1 , a power conversion device 100 receives power from a main power line 160 and supplies the power to a load 150 connected to its output side. The power conversion device 100 includes multiple power supply circuits 110a, 110b, and 110c, multiple current detection units 120a, 120b, and 120c, multiple diodes 130a, 130b, and 130c, a control unit 140, and an input power detection unit 190. In this specification, when multiple components having the same function and / or configuration exist, they are referred to by a common reference numeral followed by an alphabetical suffix, and when there is no need to distinguish between the individual components, the alphabetical suffix is ​​omitted. For example, when individual power supply circuits are to be distinguished from one another, they are referred to as power supply circuit 110a, power supply circuit 110b, etc., and when there is no need to distinguish between them, they are referred to as power supply circuit 110.

[0017] The power supply circuits 110 are connected to the main power supply line 160, and perform a predetermined power conversion process on the power supplied from the main power supply line 160 based on a control signal sent via the control signal line 170, and supply the power to the load 150. Here, for example, if the power supplied from the main power supply line 160 is direct current (DC), each power supply circuit 110 performs DC / DC conversion on the supplied power to generate a DC output voltage through switching operations using power device elements. Also, if the power supplied from the main power supply line 160 is alternating current (AC), each power supply circuit 110 first performs AC / DC conversion on the supplied power by rectifying and smoothing the power, and then generates a desired DC output voltage through DC / DC conversion.

[0018] The power supply circuits 110a, 110b, and 110c are respectively provided with storage media 200a, 200b, and 200c for storing characteristic data (described later), and temperature sensors 210a, 210b, and 210c for measuring the surface temperature of the package of a power device element (not shown) that performs power conversion or the ambient temperature of the power device element to acquire temperature data. Each power supply circuit 110 is configured to be detachable from the power conversion device 100.

[0019] Current detection units 120a, 120b, and 120c are provided corresponding to power supply circuits 110a, 110b, and 110c, respectively, and detect the output current output from the corresponding power supply circuit 110, and output current data indicating this current value to signal line 180. The current data output to signal line 180 may be either an analog signal corresponding to the output current, or a digital signal converted from an analog value to a digital value inside current detection unit 120.

[0020] Diodes 130a, 130b, and 130c are inserted on the output sides of the power supply circuits 110a, 110b, and 110c, respectively, and the power output from each of the power supply circuits 110a, 110b, and 110c passes through the diodes 130a, 130b, and 130c, respectively, before being integrated and supplied to the load 150. The diode 130 is inserted to prevent reverse current from flowing to the power supply circuit 110.

[0021] The input power detection unit 190 measures the voltage, current, and / or power supplied from the main power supply line 160 and acquires power data relating to these. The input power detection unit 190 outputs the acquired power data to a signal line 195. The power data output to the signal line 195 may be either an analog signal corresponding to the voltage, current, or power, or a digital signal obtained by converting these analog values ​​into digital values ​​inside the current detection unit 120.

[0022] The control unit 140 has an output voltage / EN setting unit 141, a storage medium R / W unit 142, a maximum efficiency calculation unit 143, a temperature data accumulation unit 144, an operating time management unit 145, an efficiency change calculation unit 146, and a monitor information generation unit 147, and controls each power supply circuit 110 via a control signal line 170.

[0023] The output voltage and EN setting unit 141 controls the on / off and output voltage of the power supply circuit 110 via a control signal line 170. The storage medium R / W unit 142 writes information to a storage medium 200 provided in the power supply circuit 110 and reads information from the storage medium 200 via the control signal line 170. The maximum efficiency calculation unit 143 obtains the operating conditions of each power supply circuit 110 using the output current value of each power supply circuit 110 obtained based on the characteristic data obtained via the storage medium R / W unit 142 and the current data sent via a signal line 180. The operating conditions obtained by the maximum efficiency calculation unit 143 are used for controlling the power supply circuit 110 in the output voltage and EN setting unit 141.

[0024] The temperature data accumulation unit 144 periodically acquires temperature data obtained by the temperature sensor 210 from each power supply circuit 110 via the control signal line 170 while each power supply circuit 110 is operating, and accumulates the acquired temperature data for each power supply circuit 110. The operation time management unit 145 acquires, for example, the power-on time and the power-off time for each power supply circuit 110, and manages the cumulative operation time of each power supply circuit 110. The efficiency change calculation unit 146 grasps changes in the power conversion efficiency of each power supply circuit based on the temperature data accumulated by the temperature data accumulation unit 144 and the operation time of the power supply circuit 110 acquired by the operation time management unit 145, and updates the characteristic data. The updated characteristic data is stored in the storage medium 200 of the power supply circuit 110 via the storage medium R / W unit 142.

[0025] The monitor information generation unit 147 generates monitor information representing the operating status of each power supply circuit 110 using the output current value of each power supply circuit 110 obtained from the current data sent via the signal line 180 and the power data sent via the signal line 195, and displays the generated monitor information on the monitor device.

[0026] 1 shows three power supply circuits 110, the number of power supply circuits 110 may be two, four or more. In this case, two, four or more current detection units 120 and diodes 130 are provided in accordance with the number of power supply circuits 110.

[0027] In addition, in FIG. 1, the current detection unit 120 and the diode 130 are provided outside the power supply circuit 110, but they may also be provided inside the power supply circuit 110.

[0028] FIG. 2 is a simplified block diagram showing the hardware configuration of the control unit 140.

[0029] The control unit 140 includes a microprocessor (MPU) 1400 , a flash memory 1410 , a random access memory (RAM) 1420 , an interface (I / O) 1430 , and a monitor device 1450 .

[0030] Flash memory 1410 is a nonvolatile storage device that can write and read data, and stores programs executed by MPU 1400. The functions of output voltage and EN setting unit 141, storage medium R / W unit 142, maximum efficiency calculation unit 143, temperature data accumulation unit 144, operating time management unit 145, and efficiency change calculation unit 146 in control unit 140 are realized by MPU 1400 executing the programs stored in flash memory 1410.

[0031] In addition to the program, the flash memory 1410 also stores information that needs to be retained even when the power conversion device 100 is temporarily powered off and operation is suspended, such as temperature data of each power supply circuit 110 collected by the temperature data accumulation unit 144 and the operating time of each power supply circuit 110.

[0032] The RAM 1420 is a volatile storage device, and is used to store data that is temporarily used when the MPU 1400 executes programs and performs calculations to realize various functions.

[0033] I / O 1430 is connected to control signal line 170, signal line 180, and signal line 195, and is used by control unit 140 to exchange the above-mentioned various information with power supply circuit 110, current detection unit 120, and input power detection unit 190, or to control these. When data acquired from current detection unit 120, input power detection unit 190, or others is sent as an analog signal, I / O 1430 converts the analog value indicated by the analog signal into a digital value and takes it into control unit 140.

[0034] The monitor device 1450 is, for example, a display device such as a liquid crystal display, and is used to display various types of monitor information generated by the monitor information generator 147 and notify the user of the operating status of the power conversion device 100. The monitor device 1450 may have a function as a so-called touch panel to accept operations by the user, or may include an operation panel separate from the display device.

[0035] In this embodiment, the programs executed by the MPU 1400 are held in a writable and readable flash memory 1410, but may also be stored in a ROM, which is a read-only storage device.

[0036] FIG. 3 is a data configuration diagram showing an example of characteristic data stored in the storage medium 200 provided in the power supply circuit 110. As shown in FIG.

[0037] The characteristic data in this embodiment includes efficiency data indicating the relationship between the output current and the power conversion efficiency. The efficiency data includes, for example, a plurality of output current values ​​and the power conversion efficiency corresponding to each of the plurality of current values. The characteristic data may also include a plurality of sets of efficiency data according to the use conditions of the power conversion device 100, such as a combination of input and output voltages. For example, FIG. 3 shows three sets of efficiency data 2000, 2010, and 2020 for different output voltages.

[0038] The control unit 140 can read and write the characteristic data stored in the storage medium 200 via the storage medium R / W unit 142 via the control signal line 170 .

[0039] In this way, by storing efficiency data corresponding to usage conditions such as input voltage and output voltage in storage medium 200, it is possible to operate the power conversion device with high efficiency even if the usage conditions change.

[0040] The operation of the power conversion device 100 will now be described in detail.

[0041] 1) Processing When Mounting the Power Supply Circuit FIG. 4 is a flowchart showing the flow of processing performed by the control unit 140 when mounting the power supply circuit 110 on the power conversion device 100.

[0042] The control unit 140 monitors the attachment / detachment status of the power supply circuit 110 (S100), and when it detects that the power supply circuit 110 has been attached, the storage medium R / W unit 142 acquires the characteristic data stored in the storage medium 200 of the power supply circuit 110 whose attachment has been detected via the control signal line 170 (S101).

[0043] The characteristic data acquired by the storage medium R / W unit 142 is passed to the maximum efficiency calculation unit 143. The maximum efficiency calculation unit 143 acquires the operating current range and maximum power conversion efficiency of the installed power supply circuit 110 based on the efficiency data included in the passed characteristic data (S102).

[0044] FIG. 5 is a conceptual diagram for explaining the concept of obtaining the operating current range and the maximum power conversion efficiency in this embodiment.

[0045] Generally, the power conversion efficiency of a power supply circuit is maximized at a certain output current and decreases as the output current decreases or increases, as shown by the efficiency curve in Figure 5. In this embodiment, an efficiency threshold is set so that the power supply circuit 110 operates at a predetermined power conversion efficiency (e.g., 90% or higher), and the range of output currents between IL (lower limit) and IH (upper limit) within which the power supply circuit 110 can operate at a power conversion efficiency equal to or higher than the efficiency threshold is set as the operating current range. As will be described later, the control unit 140 selects the power supply circuit 110 to be operated by the maximum efficiency calculation unit 143 and controls the selected power supply circuit 110 by the output voltage / EN setting unit 141 so that each power supply circuit 110 can operate at an output current value within the operating current range.

[0046] FIG. 6 is a graph illustrating an efficiency curve that can be plotted based on efficiency data set 2000.

[0047] 6 , the efficiency curve can be drawn by plotting the power conversion efficiencies corresponding to each output current value from 1 A to 7 A obtained from the efficiency data set 2000 and fitting a curve between the plots. When the efficiency threshold is set to 90%, in step S102, the operating current range is obtained with the lower limit IL of the output current set to 3 A and the upper limit IH of the output current set to 6 A, and the maximum power conversion efficiency of 95%, which is the maximum power conversion efficiency among the efficiency data set 2000, is obtained.

[0048] In this embodiment, for simplicity, the efficiency data is acquired at intervals of 1 A of output current value. However, acquiring the efficiency data at shorter intervals allows for control using a more accurate working current range and maximum power conversion efficiency. On the other hand, if the efficiency data acquisition interval is made shorter, it takes time to acquire the efficiency data and the amount of data increases, resulting in increased consumption of storage space in the storage medium 200. For this reason, for example, the efficiency data to be stored in the storage medium 200 may be acquired at a somewhat coarse data acquisition interval, and in step S102, the efficiency data acquired from the storage medium 200 may be interpolated using any interpolation method, and the working current range and maximum power conversion efficiency may be acquired based on the interpolated efficiency data.

[0049] As described above, when the control unit 140 detects that a power supply circuit 110 has been installed, it acquires characteristic data from the storage medium 200 of the installed power supply circuit 110 and calculates the operating current range and maximum power conversion efficiency of the power supply circuit 110. Therefore, even if the power conversion efficiency of the newly installed power supply circuit 110 is unknown, the power conversion device 100 of this embodiment can obtain information about the power conversion efficiency of the power supply circuit 110 simply by installing the power supply circuit 110. Note that, at least the efficiency data acquired or interpolated from the power supply circuit 110 within the operating current range is stored as characteristic curve data in the flash memory 1410 of the control unit 140, along with the calculated maximum power conversion efficiency. This allows the characteristic data to be used as needed in the processes described below and other controls without having to acquire the characteristic data again from the power supply circuit or calculate the efficiency data from the characteristic data.

[0050] 2) Processing at the Start of Power Supply to Load FIG. 7 is a flowchart showing the flow of processing performed by the control unit 140 at the start of power supply to the load 150.

[0051] The control unit 140 first activates all of the attached power supply circuits 110 using the output voltage / EN setting unit 141, and controls each power supply circuit 110 so as to supply a predetermined voltage to the load 150 (S200). Next, the control unit 140 acquires the output current of each power supply circuit 110 from each current detection unit 120 via the signal line 180 using the maximum efficiency calculation unit 143, and adds these currents together to determine the load current (S201).

[0052] After acquiring the load current, the control unit 140 uses the maximum efficiency calculation unit 143 to calculate the output current value of each power supply circuit 110 that maximizes the power conversion efficiency ηa of the entire power conversion device 100, using equation (1): ηa = Io / {(I1 / η1) + (I2 / η2) + (I3 / η3)} (1) where Io = I1 + I2 + I3, where Io is the load current, I1, I2, and I3 are the output currents of the power supply circuits 110a, 110b, and 110c, and η1, η2, and η3 are the power conversion efficiencies of the power supply circuits 110a, 110b, and 110c. The power conversion efficiency of each power supply circuit 110 is calculated using the efficiency curve data acquired when the power supply circuit 110 shown in FIG. 4 was installed (S202).

[0053] Next, it is determined whether the output current value of each power supply circuit 110 calculated in step S202 is within the operating current range (S203).

[0054] In step S203, if there is a power supply circuit 110 whose output current value is outside the operating current range, maximum efficiency calculation unit 143 selects the power supply circuit 110 with the lowest maximum efficiency, and returns to step S202. In step 202, the output current values ​​are calculated again for the remaining power supply circuits 110 excluding the selected power supply circuit 110.

[0055] If it is determined in step S203 that the output current of each power supply circuit is within the operating current range, the control unit 140 controls the output voltage / EN setting unit 141 to adjust the output voltage of each power supply circuit 110 so that each power supply circuit 110 outputs the current calculated in step S202. At this time, the output voltage / EN setting unit 141 powers off the power supply circuit 110 selected in step S204.

[0056] The above processing allows each power supply circuit 110 to operate with high efficiency, and the power conversion device 100 to be operated with high efficiency.

[0057] 3) Processing When Load Current Fluctuates FIG. 8 is a flowchart showing the flow of processing performed by the control unit 140 when the load current fluctuates during operation of the power conversion device 100.

[0058] During operation of the power conversion device 100, the control unit 140 appropriately acquires the output current of each power supply circuit 110 from the current detection unit 120 using the maximum efficiency calculation unit 143, and monitors whether they deviate from their respective operating current ranges (S300).

[0059] In step S300, if it is detected that the output current of any of the power supply circuits 110 is outside the operating current range, it is determined whether the output current value exceeds the upper limit value IH of the operating current range or is below the lower limit value IL (S301).

[0060] If step S301 determines that the output current of any of the power supply circuits 110 is below the lower limit IL of the operating current range, the control unit 140 selects the power supply circuit 110 with the lowest maximum power conversion efficiency among the power supply circuits 110 in the power-on state using the maximum efficiency calculation unit 143. The maximum efficiency calculation unit 143 then calculates the output current values ​​that maximize equation (1) for the remaining power supply circuits 110, excluding the selected power supply circuit 110 (S302). Next, the maximum efficiency calculation unit 143 determines whether all of the calculated output current values ​​for each power supply circuit 110 are within the operating current range. If none of the output current values ​​are within the operating current range, the process returns to step S302, where another power supply circuit 110 is selected for exclusion, and the output current values ​​for the remaining power supply circuits 110 are recalculated in the same manner as before. On the other hand, if all of the output current values ​​are within the operating current range, the process proceeds to step S306 (S303).

[0061] On the other hand, if the output current of any of the power supply circuits 110 exceeds the upper limit of the operating current range in step S301, the maximum efficiency calculation unit 143 selects the power supply circuit 110 with the highest maximum efficiency among the power supply circuits 110 that are powered off. Then, the output current values ​​of each power supply circuit 110 that maximize Equation (1) when the selected power supply circuit 110 is powered on and added to the operating power supply circuits 110 are calculated (S304). Next, the maximum efficiency calculation unit 143 determines whether all of the calculated output current values ​​of each power supply circuit 110 are within the operating current range. If none of the output current values ​​are within the operating current range, the process returns to step S304, where an additional power supply circuit 110 is selected in step S304. The output current values ​​of the power supply circuits 110, including the selected power supply circuit 110, are recalculated in the same manner as before. On the other hand, if all of the output current values ​​are within the operating current range, the process proceeds to step S306 (S305).

[0062] In step S306, the control unit 140 causes the output voltage / EN setting unit 141 to power off the power supply circuit 110 selected in step S303, or to power on the power supply circuit 110 selected in step S304. The output voltage / EN setting unit 141 adjusts the output voltage value of each power supply circuit 110 so that the output current value of each power supply circuit 110 becomes the output current value calculated in step S302 or step S304.

[0063] By the above processing, even if the load current fluctuates and the power supply efficiency decreases, the operating conditions of the power supply circuit 110 are set so as to maximize the power supply efficiency again, so that the power conversion device can continue to operate with high efficiency.

[0064] 4) Processing When Removing the Power Supply Circuit FIG. 9 is a flowchart showing processing performed by the control unit 140 when removing the power supply circuit from the power conversion device.

[0065] During operation of the power conversion device 100, the control unit 140 acquires, at predetermined time intervals by the temperature data accumulation unit 144, temperature data detected by the temperature sensor 210 from the power supply circuit 110 that is powered on and in operation, via the control signal line 170, and accumulates the data in the flash memory 1410. The control unit 140 also acquires, by the operation time management unit 145, the time that each power supply circuit 110 has been powered on and operating, for example, the time that it was powered on and the time that it was powered off, and records this information in the flash memory 1410 as operation time information.

[0066] When a user issues an instruction to remove power supply circuit 110 via the operation panel, control unit 140 calculates the average temperature of power supply circuit 110 during operation from the accumulated operating temperatures for power supply circuit 110 to be removed using temperature data accumulation unit 144 (S400). Next, control unit 140 calculates the time that power supply circuit 110 has been operating in a power-on state using operation time management unit 145 based on the recorded operation time information (S401).

[0067] Next, the control unit 140 calculates the amount of change in the on-resistance of the power device mounted in the power supply circuit 110 to be removed, based on the average temperature and operating time calculated in steps S400 and S401, using the efficiency change calculation unit 146. Then, based on this amount of change, the amount of change in the power conversion efficiency is calculated for each current in each group of efficiency data included in the characteristic data shown in FIG.

[0068] FIG. 10 is a graph conceptually showing the relationship between the operating time and the on-resistance of a power device. The on-resistance of a power device increases as the operating time increases, and the higher the operating temperature of the power device, the greater the increase in on-resistance. For example, when the average operating temperature is Tm, the relationship between the operating time and the on-resistance changes as shown by the curve indicated by Tm in the figure. From this graph, when the operating time is Ti and the operating temperature is Tm, the change in on-resistance is ΔRon. At this time, the change in power conversion efficiency Δη is calculated by the following formula (2): Δη (%) = (Io ２·ΔRon) / (Vi·Iin) (2) where Io is the output current, Vin is the input voltage, and Iin is the input current.

[0069] 9 , the efficiency change calculation unit 146 updates the efficiency data using the power conversion efficiency obtained by subtracting the calculated change Δη from the power conversion efficiency corresponding to each current value included in the efficiency data. The control unit 140, via the storage medium R / W unit 142, rewrites the efficiency data stored in the storage medium 200 of the power supply circuit 110 to be removed with the efficiency data updated by the efficiency change calculation unit 146, thereby updating the characteristic data stored in the storage medium 200 (S403).

[0070] The characteristic data updated by the above process can be used in other power conversion devices.

[0071] 11 is a screen configuration diagram showing an example of a monitor screen showing the operating status of the power conversion device 100. The monitor screen is generated by the monitor information generating unit 147 of the control unit 140 and displayed on the screen of the monitor device 1450.

[0072] 11 , reference numeral 500 denotes information on input power to the power conversion device 100, and 501 denotes information on output power from the power conversion device 100. The input power can be acquired by the input power detection unit 190. The output power is calculated by multiplying the output current supplied from the power conversion device 100 to the load 150 by the output voltage. The output current can be acquired by adding up the currents detected by the current detection units 120 a, 120 b, and 120 c, and the output voltage can be acquired as a known voltage controlled by the control unit 140 so as to be the voltage required by the load.

[0073] Reference numeral 502 denotes information on the power conversion efficiency (= output power / input power·100%) of the power conversion device 100 calculated from the input power and output power. Reference numerals 503, 504, and 505 denote information on the operating states of the power supply circuits 110a, 110b, and 110c, respectively, and the output current value acquired by the current detection unit 120 is plotted on an efficiency curve drawn based on the efficiency curve data acquired by the maximum efficiency calculation unit 143, and the output current and power conversion efficiency of each power supply circuit 110 are displayed in numerical form. Reference numeral 504 indicates that "power supply circuit 2" (corresponding to power supply circuit 110b) is powered off, and no information on the output current or power conversion efficiency is displayed.

[0074] In this way, by visualizing the operating status of the power conversion device 100 on the monitor screen, it is possible to improve maintainability.

[0075] According to the embodiment described above, each power supply circuit is controlled using characteristic data stored in a storage medium provided in the power supply circuit, so that the power conversion device can be operated with high efficiency even if the characteristics of each power supply circuit are unknown.

[0076] Furthermore, when a power supply circuit is removed from a power conversion device, the characteristic data is updated based on the usage history of the power supply circuit. As a result, for example, when the removed power supply circuit is reused in another power conversion device, the reused power conversion device can use the characteristic data to operate efficiently.

[0077] 12 is a schematic diagram showing the overall configuration of a power conversion device according to a second embodiment of the present invention. The power conversion device according to the first embodiment described above calculates the amount of change in efficiency at each current value from the operation record of the power supply circuit when the power supply circuit is removed, and updates the characteristic data stored in the storage medium. On the other hand, the power conversion device according to this embodiment differs from the power conversion device according to the first embodiment in that, when the power supply circuit is removed, the efficiency of the power supply circuit is actually measured and the characteristic data is updated.

[0078] As shown in Fig. 12, the power conversion device 101 of this embodiment is configured by adding an output power detection unit 301, a dummy load 302, and an efficiency calculation unit 243 to the control unit 240 to the power conversion device 100 of the first embodiment shown in Fig. 1. On the other hand, the power conversion device 101 omits the temperature data accumulation unit 144, the operating time management unit 145, and the efficiency change calculation unit 146 that the power conversion device 100 of the first embodiment has in the control unit 140.

[0079] Output power detection unit 301 is connected to the output side of power supply circuit 110, detects the amount of power output from power supply circuit 110, and outputs the output power data to control signal line 310. The output power data output to control signal line 310 may be either an analog signal corresponding to the detected power value, or a digital signal converted from an analog value to a digital value inside output power detection unit 301.

[0080] The dummy load 302 is a dummy load that consumes the output power of the power supply circuit 110, and the magnitude of the load can be changed in response to an instruction from the efficiency calculation unit 243 sent via a control signal line 310. Note that the control signal line 310 is physically connected to the I / O 1430 shown in FIG.

[0081] The other components are the same as those of the power conversion device 100 in the first embodiment, and therefore the description thereof will be omitted here.

[0082] In the power conversion device 101 of this embodiment, the process for removing any of the power supply circuits 110 is as follows.

[0083] The control unit 240 powers off all power supply circuits 110 except for the power supply circuit 110 that has been selected by the output voltage / EN setting unit 141 as a target for removal and for which measurement is to be performed. Then, the control unit 240 acquires, via the efficiency calculation unit 243, the input power value from the input power detection unit 190 and the output power value from the output power detection unit 301. At this time, the efficiency calculation unit 243 calculates the power conversion efficiency (= output power / input power·100%) of the power supply circuit 110 to be removed while changing the output current by adjusting the magnitude of the load of the dummy load 302. The storage medium R / W unit 142 updates the characteristic data of the storage medium 200 using the power conversion efficiency for each current calculated by the efficiency calculation unit 243.

[0084] If there are multiple power supply circuits 110 to be removed, the control unit 240 performs the above process for each of the power supply circuits 110 to be removed.

[0085] The processes other than the process when the power supply circuit 110 is removed are the same as those in the first embodiment, and therefore the description thereof will be omitted here.

[0086] According to the power conversion device of this embodiment, the above-mentioned processing obtains power conversion efficiency based on the actual operating conditions and updates the characteristic data, so that when the removed power supply circuit 110 is attached to another power conversion device and used, more accurate characteristic data can be provided to that power conversion device.

[0087] Third Embodiment The power conversion devices of the first and second embodiments perform control taking into consideration the efficiency of each power supply circuit, and the power conversion device of this embodiment also performs control taking into consideration noise.

[0088] 13 is a schematic diagram showing the overall configuration of a power conversion device according to a third embodiment of the present invention. The power conversion device 102 of this embodiment has a configuration in which a noise detection unit 400 and a dummy load 302 are added to the power conversion device of the first embodiment.

[0089] The dummy load 302 is similar to the dummy load described in the second embodiment. When power is supplied to the dummy load 302, the noise detection unit 400 detects noise components contained in the output voltage of the power supply circuit 110 and outputs a noise detection signal indicating the magnitude of the noise components to the control signal line 310. The noise detection unit 400 detects ripple noise of 50 Hz or 60 Hz, which is the frequency of the commercial power supplied from the main power line 160, contained in the output of the power supply circuit 110, switching noise dependent on the switching cycle of the power supply circuit 110, or a combination of both. The noise detection signal output to the control signal line 310 may be either an analog signal corresponding to the magnitude of the detected noise, or a digital signal converted from an analog value to a digital value within the noise detection unit 400. Similarly to the second embodiment, the control signal line 310 is physically connected to the I / O 1430 shown in FIG. 2 .

[0090] The maximum efficiency calculation unit 343 of the control unit 340 corresponds to the maximum efficiency calculation unit 143 in the first embodiment. The maximum efficiency calculation unit 343 differs from the maximum efficiency calculation unit 143 in that the maximum efficiency calculation unit 343 is configured to select the power supply circuit 110 to be used in the operation of the power conversion device by referring to noise data, which will be described later.

[0091] The efficiency change calculation unit 346 of the control unit 340 has the same functions as the efficiency change calculation unit in the first embodiment, and also controls the dummy load 302 via the control signal line 310, acquires the noise detection signal output by the noise detection unit 400, and updates the noise data described below.

[0092] FIG. 14 is a data structure diagram showing the data structure of the characteristic data stored in the storage medium 200 of the power supply circuit 110 in this embodiment.

[0093] In this embodiment, the characteristic data stored in the storage medium 200 includes, in addition to the efficiency data (multiple sets of efficiency data 2000, 2010, 2020) described in the first embodiment, noise data 2030 indicating the magnitude of noise contained in the output voltage from the power supply circuit 110 when power is supplied to a load.

[0094] The operation of the power conversion device 102 in this embodiment will be specifically described below.

[0095] 1) Processing when a power supply circuit is attached As with the power conversion device 100 in the first embodiment, the control unit 340 of the power conversion device 102 monitors the attachment / detachment state of the power supply circuit, and when it detects that a power supply circuit has been attached, the storage medium R / W unit 142 acquires characteristic data (efficiency data and noise data) from the storage medium 200 of the newly attached power supply circuit 110. As with the first embodiment, the maximum efficiency calculation unit 143 uses the efficiency data included in the characteristic data to acquire efficiency curve data in accordance with the flowchart shown in FIG. 4, and acquires the operating current range and maximum power conversion efficiency.

[0096] Here, the noise data included in the characteristic data is stored in flash memory 1410 in control unit 140 together with the acquired efficiency curve data and maximum power conversion efficiency.

[0097] 2) Processing at the Start of Power Supply to the Load FIG. 15 is a flowchart showing the flow of processing performed by the control unit 340 at the start of power supply to the load.

[0098] The processing according to the flowchart shown in FIG. 15 is the same as the flowchart in FIG. 7 except that the processing of step S204 in the flowchart in the first embodiment shown in FIG. 7 is replaced with step S500.

[0099] In step S500, the maximum efficiency calculation unit 343 selects the power supply circuit 110 with the greatest noise, taking into consideration the noise data. After that, the maximum efficiency calculation unit 343 returns to the processing of step 202 and recalculates the output current values ​​for the remaining power supply circuits 110 excluding the selected power supply circuit 110.

[0100] This allows the power conversion device 102 to operate each power supply circuit 110 with high efficiency, and also allows the selection of a power supply circuit with a small noise component in the output, thereby enabling the power conversion device 102 to be operated with high efficiency and low noise.

[0101] 3) Processing When Load Current Fluctuates FIG. 16 is a flowchart showing the flow of processing performed by the control unit 140 when the load current fluctuates during operation of the power conversion device 102.

[0102] The process according to the flowchart shown in Fig. 16 differs from the flowchart in the first embodiment shown in Fig. 8 in that the process of step S302 is replaced by step S600, and the process of step S304 is replaced by step S601. The processes in the other steps are the same as the processes in the first embodiment shown in Fig. 8.

[0103] In step S600, the maximum efficiency calculation unit 343 selects the power supply circuit 110 with the largest noise among the power supply circuits 110 that are powered on based on the noise data, and calculates the output current value that maximizes equation (1) for the remaining power supply circuits 110 excluding that power supply circuit 110. Also, in step S601, the maximum efficiency calculation unit 343 selects the power supply circuit 110 with the smallest noise among the power supply circuits 110 that are powered off based on the noise data, and calculates the output current value that maximizes equation (1) when that power supply circuit 110 is added to the power supply circuits 110 that are powered on and operating.

[0104] By this processing, even if the load current fluctuates and the power supply efficiency decreases, not only are the operating conditions of the power supply circuit set so that the power conversion efficiency is maximized again, but also a power supply circuit with low noise is preferentially selected, allowing the power conversion device to continue operating with high efficiency and reduced noise.

[0105] 4) Processing when power supply circuit is removed When any of the power supply circuits 110 is removed, the control unit 340, similar to the control unit 140 of the first embodiment, calculates an updated value of the efficiency data included in the characteristic data by processing steps S400 to S403 of the flowchart shown in FIG.

[0106] At this time, the control unit 340 further measures the noise contained in the output of the power supply circuit 110 to be removed and acquires updated noise data values. Specifically, the efficiency change calculation unit 346 controls the dummy load 302 to set the magnitude of the load so that the power supply circuit 110 outputs the rated power. The efficiency change calculation unit 346 takes in the noise components detected by the noise detection unit 400 as a noise detection signal from the noise detection unit 400 and acquires new noise data based on this noise detection signal.

[0107] The storage medium R / W unit 142 of the control unit 340 updates the characteristic data (efficiency data and noise data) stored in the storage medium 200 of the power supply circuit 110 to be removed with the efficiency data and noise data acquired by the efficiency change calculation unit 146.

[0108] According to the power conversion device of this embodiment, when a power supply circuit is removed, characteristic data including noise data of the power supply circuit can be updated. Therefore, for example, when the power supply circuit is reused in another power conversion device, accurate noise data can be used in the reused power conversion device in addition to efficiency data based on usage history, allowing for operation with high efficiency and reduced noise.

[0109] The above describes exemplary embodiments of the present invention. According to the above-described embodiments, each power supply circuit is controlled using characteristic data stored in a storage medium provided in the power supply circuit. This allows the power conversion device to be operated with high efficiency even when the characteristics of each power supply circuit are unknown. For example, by storing characteristic data based on the initial characteristics in a storage medium during the production stage of the power supply circuit, it becomes possible to control the power supply circuit accordingly even if the characteristics of the power supply circuit change due to a change in the power supply circuit specifications, etc.

[0110] In each of the above-described embodiments, the characteristic information stored in the storage medium of the power supply circuit is updated when the power supply circuit is removed. However, instead of or in addition to this, the update may be performed at a predetermined interval, for example, every predetermined operating time of each power supply circuit. Furthermore, in this case, the control unit may reacquire the efficiency curve data and maximum power conversion efficiency from the updated characteristic information in accordance with the processing performed when the power supply circuit is attached ( FIG. 4 ). This makes it possible to suppress the effects of a decrease in power conversion efficiency due to changes in the characteristics of the power supply circuit, and to continue highly efficient operation, even when the same power supply circuit is used in the same power conversion device for a long period of time.

[0111] The present inventors have specifically described the invention based on the embodiments thereof, but the present invention is not limited to these embodiments and can be modified in various ways without departing from the spirit and scope of the invention. For example, in the second embodiment, noise data may be included in the characteristic data, and the power supply circuit to be operated may be selected taking the noise data into consideration, thereby enabling operation that takes noise into account. Furthermore, while the power supply circuit has been described as using a power device for switching operation, the power supply circuit may use various elements and circuits with switching functions.

[0112] 100, 101, 102: power conversion device, 110a, 110b, 110c: power supply circuit, 120a, 120b, 120c: current detection unit, 130a, 130b, 130c: diode, 140: control unit, 141: output voltage / EN setting unit, 142: storage medium R / W unit, 143, 343: maximum efficiency calculation unit, 144: temperature data accumulation unit, 145: operating time management unit, 146, 346: efficiency change calculation unit, 150: load, 160: main power line, 190: input power detection unit, 200a, 200b, 200c: storage medium, 210a, 210b, 210c: temperature sensor, 301: output power detection unit, 302: dummy load, 400: noise detection unit

Claims

1. A power conversion device comprising: a plurality of power supply circuits connected in parallel, each having a storage medium for storing characteristic information relating to its own characteristics, which converts externally supplied power and supplies it to a load; a plurality of current detection units provided corresponding to each of the plurality of power supply circuits, which detect the output current supplied from the corresponding power supply circuit to the load, and output output current information indicating the value of the output current; and a control unit to which the plurality of power supply circuits and the plurality of current detection units are connected, which acquires the characteristic information from each of the plurality of power supply circuits, acquires the output current information of each of the plurality of power supply circuits from the plurality of current detection units, and controls the plurality of power supply circuits based on the acquired characteristic information and output current information.

2. The power conversion device according to claim 1, characterized in that the control unit acquires a range of output current for operating each of the plurality of power supply circuits based on the characteristic information acquired from each of the plurality of power supply circuits, and when supplying power to the load, selects a power supply circuit from the plurality of power supply circuits to be used for supplying power to the load based on the characteristic information so that the output current of the power supply circuit to be operated does not deviate from the acquired range.

3. The power conversion device according to claim 2, characterized in that the characteristic information includes efficiency information relating to the efficiency of power conversion, and the control unit, in the selection, preferentially selects a power supply circuit with high power conversion efficiency based on the efficiency information.

4. The power conversion device according to claim 3, characterized in that each of the plurality of power supply circuits further has a temperature sensor that measures the temperature of a power conversion unit that converts input power and acquires temperature information, and the control unit acquires the temperature information acquired by the temperature sensor from the plurality of power supply circuits, and for any power supply circuit, acquires new characteristic information of the any power supply circuit based on the temperature information and the operating time of the any power supply circuit.

5. The power conversion device according to claim 3, further comprising: an input power detection unit that measures input power input to the plurality of power supply circuits from the outside and acquires input power information; a pseudo load that acts as a pseudo load connected to the output side of the plurality of power supply circuits; and an output power detection unit that measures output power supplied to the pseudo load and acquires output power information, wherein the control unit acquires new characteristic information for an arbitrary power supply circuit based on the input power information acquired by the input power detection unit and the output power information acquired by the output power detection unit when the arbitrary power supply circuit is operated.

6. A power conversion device according to claim 2, wherein the characteristic information includes noise information relating to noise contained in the output, and the selection is performed by giving priority to a power supply circuit with less noise based on the noise information.

7. The power conversion device according to claim 6, further comprising: a pseudo load connected to the output side of the plurality of power supply circuits, the pseudo load being a pseudo load; and a noise detection unit that detects noise contained in a voltage applied to the pseudo load when power is supplied from the plurality of power supply circuits to the pseudo load and acquires noise information, wherein the control unit acquires new characteristic information for an arbitrary power supply circuit based on the noise information acquired by the noise detection unit when the arbitrary power supply circuit is operated.

8. A power conversion device as described in any one of claims 4, 5, and 7, characterized in that the control unit updates the characteristic information stored in the storage medium using the new characteristic information.

9. The power conversion device according to claim 8, characterized in that the characteristic information stored in the storage medium is updated in response to an instruction from a user to remove any of the power supply circuits from the power conversion device.

10. The power conversion device according to claim 1, further comprising a monitor device having a display screen for displaying information, and causing the display screen to display information relating to the input power input to the power conversion device, the output power supplied to the load, the power conversion efficiency of the entire power conversion device, and the output current and power conversion efficiency of each of the plurality of power supply circuits.

11. A control method for a power conversion device having a plurality of power supply circuits connected in parallel that convert externally supplied power and supply it to a load, and a control unit connected to the plurality of power supply circuits and controlling the plurality of power supply circuits, the control method for a power conversion device being executed by the control unit, comprising: acquiring characteristic information held by each of the plurality of power supply circuits from the plurality of power supply circuits, acquiring a range of output current to operate for each of the plurality of power supply circuits; acquiring an output current value output from each of the plurality of power supply circuits; and controlling the output voltage of the plurality of power supply circuits based on the characteristic information and the output current value so that the output current of each of the plurality of power supply circuits falls within the range.

12. The control method for a power conversion device according to claim 11, further comprising: receiving an instruction from a user to remove any one of the plurality of power supply circuits; acquiring new characteristic information relating to the power supply circuit instructed to be removed; and updating the characteristic information held in the power supply circuit instructed to be removed with the new characteristic information.

13. A control method for a power conversion device according to claim 11 or 12, characterized in that the controlling step, when the output current of any of the plurality of power supply circuits deviates from the range, selects a power supply circuit not to be used to supply power to the load based on the characteristic information, and operates the power supply circuits other than the power supply circuit selected by the selection.

14. A method for controlling a power conversion device according to claim 13, characterized in that the characteristic information includes efficiency information relating to the efficiency of power conversion, and the selecting step preferentially selects a power supply circuit with low efficiency based on the efficiency information.

15. A method for controlling a power conversion device according to claim 13, characterized in that the characteristic information includes noise information relating to noise contained in the output, and the selecting step preferentially selects a power supply circuit whose output contains a large amount of noise based on the noise information.

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