Series-connected power supply system

Abstract

To provide a serial connection power source system in which a current fluctuation rate of each power source unit can be controlled to be within a fixed range.SOLUTION: A control module CM performs arithmetic control of the next (A), (B) for each power module PM(x) (x is 1 to n) after the elapse of a prescribed time since the power module undergoes an output start in a constant current control mode. (A) acquiring a current detection value Idet of the power module PM(x), and acquiring a current detection value correction rate α with the following formula (1): α=Idet(AV) / Idet, where Io(AV) is an average current value of the current detection value Idet of each power module. (B) sending the current detection value correction rate α to the power module PM(x). The power module PM(x) corrects the current detection value Idet by the current detection value correction rate α sent from the control module CM.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a series-connected power supply system configured by connecting a plurality of power supply units in series. [Background technology]

[0002] A series-connected power supply system is a system in which a plurality of power supply units are connected in series to make the voltage applied to a load equal to or higher than the output voltage of a single power supply unit.

[0003] FIG. 1 shows a series-connected power supply system in which four power modules (power supply units) PM1 to PM4 are connected in series. In a series-connected power supply system in which four power modules PM1 to PM4 are connected in series, an output end voltage VL up to four times the output voltage Vo of each power module can be applied to a load L. Each power module is controlled by a control module (control unit) CM. In such a series-connected power supply system, the output end voltage VL during constant current control changes depending on the magnitude of the load, but the rate of change (current fluctuation rate) of the output current Io depending on the magnitude of the output end voltage VL must be within a certain range.

[0004] Therefore, in a conventional series-connected power supply system, a communication line is provided to connect each power module, and each power module can grasp the control status of all the power modules through the communication line (Patent Document 1). In this series-connected power supply system, each power module adjusts its own control according to the control status of the other power modules. This stabilizes the current regulation rate of the system. It is also possible to stabilize the current regulation rate of the system by constantly monitoring the control status of each power module with a control module (control unit) CM and constantly fine-tuning the control of each power module. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-127119 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in a configuration in which each power module is connected by a communication line, the provision of the communication line makes the wiring that much more complicated, and each power module constantly monitors the control status of the other power modules while fine-tuning its own control, which causes problems of complicating the control. Similarly, a method in which the control module CM monitors the control status of each power module and constantly fine-tunes each power module also has the problem of complicating the control.

[0007] An object of the present invention is to provide a series-connected power supply system that can control the current regulation of each power module (power supply unit) within a certain range without complex control. [Means for solving the problem]

[0008] The series-connected power supply system of the present invention comprises: A series-connected power supply system including n power supply units connected in series and a control unit for controlling each of the power supply units, Each of the power supply units is an output current detector for detecting an output current; an output voltage detector for detecting an output voltage; a control unit having a constant current control mode in which a current detection value Idet detected by the output current detector and a voltage detection value Vdet detected by the output voltage detector are fed back and the output current is controlled so that the current detection value Idet becomes a current setting value set by the control unit, the control unit performs the following arithmetic control (A) and (B) for each of the power supply units (x) (x is 1 to n) when a predetermined time has elapsed since output was started in the constant current control mode, (A) The current detection value Idet of the power supply unit (x) is acquired, and a current detection value correction ratio α is calculated using the following formula (1).

[0009] α = Idet(AV) / Idet―――(1) however, Idet(AV) is the average current value of the current detection value Idet of each power supply unit (B) The current detection value correction ratio α is sent to a power supply unit (x).

[0010] Each of the power supply units (x) corrects the current detection value Idet based on the current detection value correction ratio α sent from the control unit. Series connected power system.

[0011] The present invention provides a constant current control mode for a series-connected power supply system in which n power supply units are connected in series. In the above (A), the control unit determines the degree of detection error of the output current detector and calculates a current detection value correction ratio α to correct this. Then, in the above (B), the control unit sends the current detection value correction ratio α to the corresponding power supply unit. The power supply unit corrects the current detection value Idet using the current detection value correction ratio α.

[0012] This improves the current control accuracy of the feedback system of the control unit, which is caused by detection errors of the output current detectors of the power supply units.

[0013] The present invention also provides a method for producing a semiconductor device comprising the steps of: The control unit performs the calculation and control of (A) and (B) when the predetermined time has elapsed each time output is started, corrects the current detection value correction ratio α calculated by equation (1) when the predetermined time has elapsed after the current output is started, using the following equation (2) to calculate the current detection value correction ratio α' (present), and sends the current detection value correction ratio α' (present) to the power supply unit (x).

[0014] Current detection value correction ratio α' (this time) = Current detection value correction ratio α (previous time) × Current detection value correction ratio α ----- (2) Here, the current detection value correction ratio α' (present) is the current detection value correction ratio α corrected after the present startup, and the current detection value correction ratio α (previous) is the current detection value correction ratio α corrected after the previous startup. In the control unit, the above-mentioned calculation control of (A) and (B) is performed each time the output is started, and the current detection value correction ratio α is calculated. After that, constant current control is performed using the current detection value Idet corrected by α. Here, when the above-mentioned calculation control of (A) is performed using this current detection value correction ratio α after the next output is started, the current detection value Idet at that time has been corrected by the previous current detection value correction ratio α. Therefore, the current current detection value correction ratio (α) is calculated using the following formula (2).

[0015] Current detection value correction ratio α' (this time) = Current detection value correction ratio α (previous time) × Current detection value correction ratio α ----- (2) For example, if the current detection value correction ratio α (previous) = 99% and the current detection value correction ratio α = 99%, The current detection value correction ratio α' (this time) = 99% × 99% = 98%.

[0016] The present invention also provides a method for producing a semiconductor device comprising the steps of: The control unit At the appointed time, The following calculation control (C) is performed.

[0017] (C) If the absolute value error between the maximum and minimum values ​​of the current detection value Idet of each power supply unit is equal to or smaller than a predetermined value, the calculation and control of (A) and (B) is not performed.

[0018] Therefore, if the current control error between the power supply units is not so large, the above calculation controls (A) and (B) are not performed. In this case, the current control accuracy of the entire series-connected power supply system is not significantly affected even if the above calculation controls are not performed. Effect of the Invention

[0019] In the present invention, in the constant current control mode, a current detection value correction ratio α for correcting the current detection value Idet is calculated for each power supply unit when a predetermined time has elapsed since output was started in the constant current control mode. In each power supply unit, the current detection value Idet is corrected by this current detection value correction ratio α, thereby compensating for the detection error of the output current detector. This makes it possible to control the current regulation rate of each power supply unit within a certain range without complex control. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 shows a configuration diagram of a series-connected power supply system in which four power supply units are connected in series. [Diagram 2] FIG. 2 shows a configuration diagram of a series-connected power supply system according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic configuration diagram of the output side of the power modules PM1 to PM4. [Figure 4] FIG. 4 shows the current regulation rate relative to the fluctuation of the output terminal voltage VL. [Diagram 5] FIG. 5 is a configuration diagram of a power module PM1 according to an embodiment of the present invention. [Figure 6] FIG. 6 is a flow chart showing the operation of the control module CM according to the embodiment of the present invention. [Figure 7] FIG. 7 is a flow chart showing the operation of the control module CM according to the embodiment of the present invention. [Figure 8] FIG. 8 shows the operation of part of the power modules PM1 to PM4. [Figure 9] FIG. 9 shows a configuration diagram of a series-parallel connected power supply system according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] FIG. 2 shows a configuration diagram of a series-connected power supply system according to an embodiment of the present invention.

[0022] The series-connected power supply system of this embodiment is composed of four power supply units (hereinafter referred to as power modules) PM1 to PM4, and a control unit (hereinafter referred to as control module) CM connected to each of the power modules PM1 to PM4. The output terminals of the four power modules PM1 to PM4 are connected in series, and supply an output current Io to a load L in a constant current control mode.

[0023] In the above configuration, the power modules PM1 to PM4 are connected to the control module CM via communication lines and exchange data with each other. The control module CM sends to the power modules PM1 to PM4 information on whether constant current control or constant voltage control is being performed, the output current setting value, and the output voltage setting value. In the case of constant current control, the power modules PM1 to PM4 set the output current setting value as a constant current command value (target value) and the output voltage setting value as the output voltage limit value (if this value is exceeded, constant voltage control will be used).

[0024] As described later, the control module CM calculates and sends a current detection value correction ratio α to the power modules PM1 to PM4 when a predetermined time has elapsed since the output was started. The power modules PM1 to PM4 constantly send the current detection value Idet and the voltage detection value Vdet to the control module CM.

[0025] 2, the power modules PM1 to PM4 show that there is an error between the current detection value Idet and the actual output current Io. In the example shown in the figure, the power module PM1 has an error of (-1.0%), the power module PM2 has an error of (0.0%), the power module PM3 has an error of (+0.5%), and the power module PM4 has an error of (+1.0%). Therefore, when the output current Io is constant-current controlled at 500A, the current detection value Idet is 495A in the power module PM1, the current detection value Idet is 500A in the power module PM2, the current detection value Idet is 502.5A in the power module PM3, and the current detection value Idet is 505A in the power module PM4.

[0026] The above errors actually include errors due to losses in the output wiring and voltage drops, but the largest effect comes from detection errors in the current detector.

[0027] FIG. 3 is a schematic configuration diagram of the output side of the power modules PM1 to PM4.

[0028] The output current of the DC-DC converter 1 is detected as a current detection value Idet by a current detector 2 consisting of a shunt resistor, Hall CT, etc., and is fed back to a control unit 3. In addition, the output voltage of the DC-DC converter 1 is detected as a voltage detection value Vdet by a voltage detector 4, and is fed back to the control unit 3. The control unit 3 performs constant current control based on the current detection value Idet and constant voltage control based on the voltage detection value Vdet. In addition, the control unit 3 sends the current detection value Idet and voltage detection value Vdet to a control module CM.

[0029] Now, assume that a load L with an output current set to 500A and an output end voltage VL of 6V to 60V is connected to a series-connected power supply system including power modules PM1 to PM4. Since the power modules PM1 to PM4 are connected in series, the overall output end voltage VL applied to the load L varies between 6V and 60V. In this case, the current regulation rate of the series-connected power supply system is calculated as the current regulation rate when the output end voltage VL varies from 100% to 10% due to the fluctuation of the load L. However, if this current regulation rate is large (for example, 2.0% or more), highly accurate constant current control cannot be performed at an arbitrary output end voltage VL.

[0030] For example, if the rated current value of this system is 500A, and the output current Io is 505.0A when the output terminal voltage VL is 60V, and the output current Io is 495.0A when the output terminal voltage VL is 6V, the current regulation is Current fluctuation rate = (505 - 495) / 500 x 100 = 2.0% Since the current fluctuation rate is large, it is difficult to perform high-precision constant current control in response to load fluctuations.

[0031] The above current change rate depends on the current control accuracy of each of the power modules PM1 to PM4, and the current control accuracy greatly depends on the error of the current detectors 2 (configured by shunt resistors, Hall ICs, etc.) of the power modules PM1 to PM4.

[0032] Therefore, in this embodiment, the control module CM obtains a current detection value correction ratio α for each of the power modules PM1 to PM4 by the following calculation based on the current detection value Idet of the current detector 2 for each of the power modules PM1 to PM4. Then, this is sent to each of the power modules PM1 to PM4. This control is performed only once when a predetermined time has elapsed since the power modules PM1 to PM4 were output-activated. After that, in the power modules PM1 to PM4, the current detection value Idet is corrected by the current detection value correction ratio α.

[0033] By performing such control, in each of the power modules PM1 to PM4, the error of the current detector 2 is compensated, and the current detection value Idet becomes equal to the output current Io. Since the compensation of this error is independent of the magnitude of the output voltage Vo, it is always correctly performed even when the output voltage Vo changes.

[0034] Hereinafter, for ease of understanding, first, the behavior of the power modules PM1 to PM4 when not corrected by the current detection value correction ratio α will be described. It is assumed that in the control module CM, the power modules PM1 to PM4 are set to perform constant current control.

[0035] Now, assume that the errors of the current detectors 2 of the power modules PM1 to PM4 are PM1 (-1.0%) < PM2 (0.0%) < PM3 (+0.5%) < PM4 (+1.0%). The current set value (command value) is 500 A, and the voltage set value (voltage limit value) is 15.3 V, which is one-fourth of 102% (61.2 V) of the output terminal voltage VL (60 V).

[0036] (When the output terminal voltage VL is low, 15.3 V or less) When the detected current value Idet of PM1 is 500 A, due to an error of (-1.0%), the actual current value is 495 A. At this time, since the error of current detector 2 is PM1 < PM2 < PM3 < PM4, the detected current values Idet of PM2 to PM4 will be 500 A or more. For this reason, PM1 enters the constant current control mode, and PM2 to PM4 are controlled to reduce the output current. As a result, the constant current control of PM1 becomes dominant. PM2 to PM4 operate based on the values detected by each current detector for the actual current value of 495 A, but do not output current.

[0037] The output terminal voltage VL of the system is approximately equal to the output voltage Vo1 of PM1. Each PM is in the following state. Strictly speaking, in the PM in the output stop state, the output current Io flows through the secondary side rectifying diode (see the DC-DC converter 1 in Fig. 5), resulting in a voltage drop in this part. Due to this voltage drop, the output terminal voltage VL does not exactly match the output voltage Vo1 of PM1.

[0038] PM1: Constant current control mode. PM2: Operates based on the value detected by current detector 2 for the actual current value of 495 A. Output stop state. PM3: Operates based on the value detected by current detector 2 for the actual current value of 495 A. Output stop state. PM4: Operates based on the value detected by current detector 2 for the actual current value of 495 A. Output stop state.

[0039] In this state, the detected current values Idet of PM2, PM3, and PM4 are, for example, PM2: 505 A (+1%), PM3: 507.5 A (+1.5%), PM4: 510 A (+2%).

[0040] (When the output terminal voltage VL rises above 15.3 V) The output voltage Vo1 of PM1 rises until it reaches the voltage limit value (15.3 V: 102% of 15 V). From this point on, PM1 enters the constant voltage control mode.

[0041] Since PM1 enters the constant voltage control mode, the insufficient voltage needs to be covered by other PMs. At this time, due to the error of current detector 2 being PM2 < PM3 < PM4, PM2 enters the constant current control mode and outputs the insufficient voltage. Assuming the detected current value Idet of PM2 is 500A (the actual current value is 500A), PM3 - 4 are controlled to reduce the output current. As a result, the constant current control of PM2 becomes dominant. PM3 - PM4 operate based on the values detected by each current detector for the actual current value of 500A, but do not output.

[0042] The output terminal voltage VL of the system is approximately equal to the sum of the output voltage Vo1 of PM1 and the output voltage Vo2 of PM2. Each PM is in the following state at this time.

[0043] PM1: Constant voltage control mode. PM2: Constant current control mode. PM3: Operates based on the value detected by current detector 2 for the actual current value of 500A. Output stopped state. PM4: Operates based on the value detected by current detector 2 for the actual current value of 500A. Output stopped state.

[0044] The detected current values Idet of PM1, PM3, and PM4 in this state are PM1: 495A (-1%), PM3: 502.5A (+0.5%), PM4: 505A (+1%).

[0045] (When the output terminal voltage VL further increases) The output voltage Vo2 of PM2 rises until it reaches the voltage limit value (15.3V: 102% of 15V). From this point on, PM2 enters the constant voltage control mode.

[0046] Since PM1 is already in the constant voltage control mode and subsequently PM2 enters the constant voltage control mode, the insufficient voltage will be covered by other PMs. At this time, because the error of current detector 2 is such that PM3 < PM4, PM3 enters the constant current control mode and outputs the insufficient voltage. Assuming the detected current value Idet of PM3 is 500 A (the actual current value is 502.5 A), PM4 controls to reduce the output current. As a result, the constant current control of PM3 becomes dominant. PM4 operates based on the value detected by current detector 2 for the actual current value of 502.5 A but does not output.

[0047] The output terminal voltage VL of the system is approximately equal to the sum of the output voltages Vo1 to Vo3 of PM1 to PM3. Each PM is in the following state at this time.

[0048] PM1: Constant voltage control mode. PM2: Constant voltage control mode. PM3: Constant current control mode. PM4: Operates based on the value detected by current detector 2 for the actual current value of 502.5 A. Output stop state.

[0049] The detected current values Idet of PM1, PM2, and PM4 in this state are PM1: 492.5 A (-1.5%), PM2: 497.5 A (-1%), and PM4: 502.5 A (+0.5%).

[0050] (When the output terminal voltage VL further increases) The output voltage Vo3 of PM3 rises until it reaches the voltage limit value (15.3 V: 102% of 15 V). From this point on, PM3 enters the constant voltage control mode.

[0051] Since PM1 and PM2 are already in the constant voltage control mode and subsequently PM3 enters the constant voltage control mode, the insufficient voltage will be covered by PM4, and PM4 enters the constant current control mode and outputs the insufficient voltage. Assuming the detected current value Idet of PM4 is 500 A (the actual current value is 505 A), the constant current control of PM4 becomes dominant.

[0052] The output terminal voltage VL of the system is equal to the sum of the output voltages Vo1 to Vo4 of PM1 to PM4. At this time, each PM is in the following state.

[0053] PM1: Constant voltage control mode. PM2: Constant voltage control mode. PM3: Constant voltage control mode. PM4: Constant current control mode. In this state, the detected current values ​​Idet of PM1, PM2, and PM3 are PM1: 490A (-2%), PM2: 495A (-1%), and PM3: 497.5A (-0.5%).

[0054] FIG. 4 shows the current regulation rate with respect to the fluctuation of the output terminal voltage VL when the error of the current detector 2 is PM1 (-1.0%), PM2 (0.0%), PM3 (+0.5%), and PM4 (+1.0%). Constant current control is performed by PM1 until the output terminal voltage VL is 15.3V, constant current control is performed by PM2 until the output terminal voltage VL is 15.3V to 30.6V, constant current control is performed by PM3 until the output terminal voltage VL is 30.6V to 45.9V, and constant current control is performed by PM4 until the output terminal voltage VL is 45.9V to 61.2V. The PMs operating under constant current control change from PM1 to PM2 to PM3 to PM4, and the current regulation rate gradually increases, eventually reaching 2%.

[0055] Thus, in the above example, in the period from when the output terminal voltage VL is low until it rises to VL=60V, the current fluctuation rate is as high as 1% to 2%, which is not a sufficiently low value.

[0056] In this embodiment, as described below, the error of the current detector 2 of PM1 to PM4 is compensated for and the current detection value Idet is corrected by the current detection value correction ratio α. This controls the current regulation rate to be a sufficiently low value from when the output terminal voltage VL is low to when VL=60V.

[0057] 5 is a configuration diagram of a power module PM1 according to an embodiment of the present invention. The other power modules PM2 to PM4 have the same configuration.

[0058] The power module PM1 includes a rectifier 6 that rectifies the input current from a power source 5, and a The power module PM1 and the control module CM are connected via a communication line for transmitting and receiving a control signal TC1 in both directions.

[0059] The control signal TC1 is transmitted from the control module CM to the power module PM1 and includes a current set value, a voltage set value, and a current detection value correction ratio α (described later). When constant current control is set, the current set value is a current command value, and the voltage set value is a voltage limit value. The control signal TC1 also includes a current detection value Idet of the output current detector 2 and a voltage detection value Vdet of the output voltage detector 4, which are transmitted from the power module PM1 to the control module CM.

[0060] In the constant current control mode, the control unit 3 controls the switching of the DC-DC converter 1 so that the current detection value Idet of the output current detector 2 matches the current command value and so that the voltage detection value Vdet of the output voltage detector 4 does not exceed the voltage limit value. In the constant voltage control mode, the control unit 3 controls the switching of the DC-DC converter 1 so that the voltage detection value Vdet of the output voltage detector 4 matches the voltage command value and so that the current detection value Idet of the output current detector 2 does not exceed the current limit value. In either mode, specifically, the control unit 3 controls the pulse width of a PWM signal that controls the on / off of the switching element of the DC-DC converter 1.

[0061] In the above configuration, each of the power modules PM1 to PM4 operates as described above in accordance with the magnitude of the output end voltage VL (the magnitude of the load L).

[0062] 6 and 7 are flowcharts showing the operation of the control module CM according to the embodiment of the present invention. Fig. 6 shows the operation of acquiring Idet and Vdet, which is executed at regular intervals. Fig. 7 shows the operation of each PM when the output is started.

[0063] The control module CM acquires the current detection values ​​Idet from the power modules PM1 to PM4 at regular time intervals (ST1), and displays these on a display in an operation unit (not shown) (ST2).

[0064] When the control module CM issues a command to start output to the power modules PM1 to PM4, the process proceeds to ST11 and subsequent steps after a predetermined time has elapsed (ST10). ST11 and subsequent steps are executed for each of the power modules PM1 to PM4. The predetermined time is preset as the time required for the operation of the power modules PM1 to PM4 to stabilize.

[0065] First, the average value Idet(AV) of the current detection values ​​Idet of the power modules PM1 to PM4 is calculated, and if Idet(AV)>=a constant current value (for example, 10% of the rated current), proceed to ST12 and below. Otherwise, since the output current Io is small, return is made without performing control in ST12 and below.

[0066] The error (absolute value) between the maximum and minimum values ​​of the current detection value Idet of the power modules PM1 to PM4 is obtained, and if the error is >= 0.4%, proceed to ST13 and subsequent steps. Otherwise, since the error of the power modules PM1 to PM4 is not very large, the control of ST13 and subsequent steps is not performed and the process returns.

[0067] If the average value Idet(AV) is greater than or equal to a constant current value and the error (absolute value) between the maximum and minimum values ​​of the current detection value Idet is greater than or equal to 0.4%, the current detection value correction ratio α(n) is calculated using the following formula (ST13).

[0068] The correction ratio for this time is α(n)=Idet(AV) / Idet―――(1) α´(n)=α(n-1)×α(n)――(2) Here, n represents the current output start calculation time, and n-1 represents the previous output start calculation time.

[0069] In formula (1), the average value Idet(AV) is estimated as the correct output current, and the ratio of the estimated output current to the current detection value Idet is calculated as the current correction ratio α(n). This correction ratio α(n) correlates with the error of the output current detector 2 of the corresponding power module PM.

[0070] Next, in formula (2), the current detection value correction ratio α'(n) used in this control is calculated as: Current detection value correction ratio α'(n) = Current detection value correction ratio α(n-1) × Current detection value correction ratio α. For example, if α(n-1) is 99% and α(n) is 98%, then α'(n) = 97%.

[0071] In other words, the current detection value correction ratio α'(n) for this time (n) is calculated by multiplying the current detection value correction ratio α(n-1) calculated previously (n-1) by the correction ratio α(n) calculated this time (n).

[0072] If the current detection value correction ratio α'(n) calculated above exceeds a certain range, it is limited to be within that range (ST14). If the absolute value of the current detection value correction ratio α'(n) exceeds the upper or lower limit, an abnormality in the detector may be suspected, and therefore it is considered desirable to limit the value.

[0073] Next, the current detection value correction ratio α'(n) is transmitted to the corresponding power module (ST15).

[0074] In preparation for control at the next output startup, α(n-1)=α'(n) is set and stored in the internal memory (ST16). Therefore, the current detection value correction ratio α'(n) calculated this time is used as α(n-1) in the control from ST10 onwards at the next output startup.

[0075] Through the above control, the current detection value correction ratios α'(n) of the power modules PM1 to PM4 are obtained.

[0076] FIG. 8 shows the operation of part of the power modules PM1 to PM4.

[0077] When the current detection value correction ratio α'(n) is received from the control module CM (ST20), the value is updated (ST21), and the current detection value Idet is corrected by the following equation (3) (ST22).

[0078] Idet=Idet×α´(n)---(3) According to the above formula (3), the power modules PM1 to PM4 perform constant current control after correctly correcting the current detection value Idet based on the error of the output current detector 2. After the power modules PM1 to PM4 receive the current detection value correction ratio α'(n) only once after output startup, they correct the current detection value Idet according to formula (3) until the output is stopped. Since the error of the current detector 2 is constant regardless of the magnitude of the output end voltage VL, the current detection value Idet is corrected to match the output current Io regardless of the magnitude of the output end voltage VL.

[0079] Therefore, the errors of current detector 2 for PM1 (-1.0%), PM2 (0.0%), PM3 (+0.5%), and PM4 (+1.0%) are all corrected to (0.0%). As a result, the current regulation rate for the change in output terminal voltage VL from 6V to 60V is almost flat, unlike in Figure 4, and the current control accuracy of the entire series-connected power supply system can be improved.

[0080] In the embodiment, the calculation of α'(n) = α(n-1) × α(n) is performed using equation (2). However, it is also possible to obtain the detection value correction ratio α using equation (1) as α = Idet(AV) / Idet each time the output is started, and send this α to the power modules PM1 to PM4.

[0081] In the embodiment, the calculations in ST13 and after are performed only when Idet(AV)>=constant current value in ST11 in Fig. 7 and when the error (absolute value) between the maximum and minimum values ​​of Idet is>=0.4% in ST12, but these conditions in ST11 and ST12 are not necessarily required. Also, in ST12, it is possible to provide hysteresis to the value of "0.4%" used to judge the error.

[0082] In this embodiment, a system in which power modules PM1 to PM4 are connected in series has been shown, but it is also possible to configure a series-parallel connected power supply system as a whole by connecting multiple series-connected groups in parallel. FIG. 9 shows an example of the configuration of such a series-parallel connected power supply system. A PM series-connected group G1 and a PM series-connected group G2 are connected in parallel, and multiple PMs are connected in series in each group. The PM series-connected groups G1 and G2 are each controlled by a control module CM in the same manner as described above. A series-parallel connected power supply system can increase the output current Io compared to a single PM series-connected power supply system such as those shown in FIG. 1 and FIG. 2. [Explanation of symbols]

[0083] CM - Control Module PM1~PM4-Power Modules

Claims

1. A series-connected power supply system including n power supply units connected in series and a control unit for controlling each of the power supply units, Each of the power supply units is an output current detector for detecting an output current; an output voltage detector for detecting an output voltage; a control unit having a constant current control mode in which a current detection value Idet detected by the output current detector and a voltage detection value Vdet detected by the output voltage detector are fed back and the output current is controlled so that the current detection value Idet becomes a current setting value set by the control unit, the control unit performs the following arithmetic control of (A) and (B) for each of the power supply units (x) (x is 1 to n) when a predetermined time has elapsed since output was started in the constant current control mode, (A) The current detection value Idet of the power supply unit (x) is acquired, and a current detection value correction ratio α is calculated using the following equation (1). α=Idet(AV) / Idet――(1) however, Idet(AV) is the average current value of the current detection value Idet of each power supply unit. (B) The current detection value correction ratio α is sent to the power supply unit (x). Each of the power supply units (x) corrects the current detection value Idet based on the current detection value correction ratio α transmitted from the control unit. Series connected power system.

2. 2. The series-connected power supply system according to claim 1, wherein the control unit performs the calculation control of (A) and (B) when the predetermined time has elapsed for each output startup, corrects the current detection value correction ratio α calculated by equation (1) when the predetermined time has elapsed after the current output startup by the following equation (2) to calculate the current detection value correction ratio α' (present), and sends the current detection value correction ratio α' (present) to the power supply unit (x). Current detection value correction ratio α' (this time) = Current detection value correction ratio α (previous time) × Current detection value correction ratio α --- (2) Here, the current detection value correction ratio α' (present) is the current detection value correction ratio α corrected after the present startup, and the current detection value correction ratio α (previous) is the current detection value correction ratio α corrected after the previous startup.

3. 3. The series-connected power supply system according to claim 1, wherein the control unit performs the following arithmetic control (C) at a predetermined time: (C) If the absolute value error between the maximum and minimum values ​​of the current detection value Idet of each power supply unit is equal to or smaller than a predetermined value, the calculation and control of (A) and (B) is not performed.

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