Control circuit and power conversion device including the same

Abstract

To provide a control circuit capable of suppressing destabilization of control even when a plurality of power conversion devices control a common control target, and a power conversion device including the control circuit.SOLUTION: A control circuit 23 that controls an electrical characteristic of an output or an input of a power conversion circuit 21 includes a subtractor 24 that calculates a deviation Δ Vdc obtained by subtracting a detection value (voltage value Vdc) obtained by detecting the electrical characteristic from a target value Vdc * of the detection value, a correction unit 25 that corrects the deviation Δ Vdc to a corrected deviation Δ Vdc ', and a control unit 26 that calculates a compensation value by performing at least an integration operation on the corrected deviation Δ Vdc '. When the deviation Δ Vdc is smaller than the first reference value X1 and larger than the second reference value X2, the correction unit 25 outputs "0" as the corrected deviation Δ Vdc '.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control circuit for controlling a power conversion circuit, and a power conversion device including the control circuit. [Background technology]

[0002] Patent Document 1 discloses a power conversion device that outputs a DC voltage. The power conversion device includes a power conversion unit and a control circuit. The control circuit outputs a gate drive signal based on the result of a proportional-plus-integral calculation performed on the deviation between a detected DC voltage value output by the power conversion unit and a DC voltage command value, which is a target value. The power conversion unit drives each switching element in response to the gate drive signal. As a result, the DC voltage output by the power conversion unit is controlled to the DC voltage command value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-216810 Summary of the Invention [Problem to be solved by the invention]

[0004] In a system having a plurality of power conversion devices as described above, when each power conversion device controls the DC voltage of a common DC bus, there is a problem that the control is unstable. That is, even if the DC voltage command value set in each power conversion device is the same, the DC voltage values ​​detected by each power conversion device do not exactly match due to detection errors in the DC voltage sensors and conversion errors during analog-to-digital conversion. Therefore, interference occurs between the controls of each power conversion device, causing the control to become unstable.

[0005] The present invention was devised in light of the above-mentioned circumstances, and aims to provide a control circuit that can suppress control instability even when multiple power conversion devices control a common control target, and a power conversion device equipped with such a control circuit. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides the following technical means.

[0007] A control circuit provided by a first aspect of the present invention is a control circuit that controls the electrical characteristics of the output or input of a power conversion circuit, and includes a subtractor that calculates a deviation by subtracting a detected value of the electrical characteristic from a target value of the detected value, a correction unit that corrects the deviation to a corrected deviation, and a control unit that performs at least an integral operation on the corrected deviation to calculate a compensation value, and the correction unit outputs ``0'' as the corrected deviation when the deviation is smaller than a first threshold value and larger than a second threshold value.

[0008] The "electrical characteristics" include voltage, current, and power (active power, reactive power).

[0009] In a preferred embodiment of the present invention, when the deviation is equal to or greater than the first threshold, the correction unit outputs a value obtained by subtracting the first threshold from the deviation as the corrected deviation, and when the deviation is equal to or less than the second threshold, the correction unit outputs a value obtained by subtracting the second threshold from the deviation as the corrected deviation.

[0010] In a preferred embodiment of the present invention, the detected value is a detected value of a DC voltage output by the power conversion circuit.

[0011] In a preferred embodiment of the present invention, the device further includes a threshold setting unit that sets the first threshold and the second threshold, and the threshold setting unit changes the first threshold and the second threshold depending on the result of the integration calculation in the control unit.

[0012] A power conversion device provided by a second aspect of the present invention includes the control circuit provided by the first aspect of the present invention and the power conversion circuit. [Effects of the Invention]

[0013] According to the present invention, when the deviation input from the subtractor is smaller than the first threshold value and larger than the second threshold value, the correction unit outputs "0" as the corrected deviation to the control unit. Therefore, even if the detected voltage value Vdc includes an error, when the deviation is smaller than the first threshold value and larger than the second threshold value, "0" is input as the corrected deviation to the control unit. This prevents the output of the integral term from increasing in the control unit. Therefore, the power conversion device according to the present invention can prevent destabilization of control by each power conversion device even when multiple power conversion devices control a common controlled object.

[0014] Other features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0015] [Figure 1] 1A and 1B are diagrams for explaining a power conversion device according to a first embodiment, in which (a) is a block diagram showing the overall configuration of a storage battery system equipped with a power conversion device, and (b) is a diagram for explaining interference suppression processing performed by a correction unit of a control circuit of the power conversion device. [Figure 2] 10 is an example of a flowchart illustrating an interference suppression process performed by a correction unit. [Figure 3] 10A and 10B are diagrams for explaining a modified example of the interference suppression processing performed by the correction unit. [Figure 4] FIG. 10 is a block diagram showing the internal configuration of a control circuit 23 of a storage battery system according to a second embodiment. [Figure 5] FIG. 10 is a block diagram showing the overall configuration of a storage battery system according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0017] [First embodiment] Fig. 1 is a diagram for explaining a power conversion device 2 according to a first embodiment. Fig. 1(a) is a block diagram showing the overall configuration of a storage battery system A1 including a power conversion device 2. Fig. 1(b) is a diagram for explaining interference suppression processing performed by a correction unit 25 of a control circuit 23 of the power conversion device 2.

[0018] The battery system A1 includes a plurality of storage batteries 1, a plurality of power conversion devices 2, an inverter device 3, and a DC bus 4. The battery system A1 converts AC power supplied from a power grid into DC power to charge the storage batteries 1, discharges the storage batteries 1 in predetermined cases, and converts the DC power output by the storage batteries 1 into AC power to supply to the power grid. In this embodiment, the battery system A1 includes four power conversion devices 2, each connected to a storage battery 1. The number of power conversion devices 2 and storage batteries 1 included in the battery system A1 is not limited.

[0019] The inverter device 3 has input / output terminals on the DC side connected to the DC bus 4 and input / output terminals on the AC side connected to the power grid. The inverter device 3 includes a bidirectional inverter circuit that converts DC power and AC power. The inverter device 3 converts AC power supplied from the power grid into DC power and outputs it to the DC bus 4, and converts DC power input from the DC bus 4 into AC power and supplies it to the power grid. The specific configuration of the inverter device 3 is not limited.

[0020] Each of the multiple storage batteries 1 is a secondary battery capable of repeated charging and discharging, such as a lithium-ion battery. The storage batteries 1 may also be other secondary batteries such as nickel-metal hydride batteries, nickel-cadmium batteries, and lead-acid batteries. The storage batteries 1 may also be capacitors such as electric double-layer capacitors instead of secondary batteries. Each of the storage batteries 1 is connected to a power conversion device 2.

[0021] Each of the multiple power conversion devices 2 is a so-called DC / DC converter device that transforms and outputs an input DC voltage. Each of the multiple power conversion devices 2 has a storage battery 1 connected to one input / output terminal and an inverter device 3 connected to the other input / output terminal via a DC bus 4. In other words, the power conversion devices 2 are connected in parallel with each other. The multiple power conversion devices 2 have a common internal configuration.

[0022] The power conversion device 2 includes a power conversion circuit 21, a sensor 22, and a control circuit 23. The power conversion device 2 also includes sensors other than the sensor 22, but these are not shown or described here. The power conversion circuit 21 increases or decreases the input DC voltage and outputs it by turning on and off a switching element (not shown) in response to a drive signal input from the control circuit 23. The specific circuit configuration of the power conversion circuit 21 is not limited. The sensor 22 detects the DC voltage at the input / output terminal connected to the DC bus 4 of the power conversion circuit 21, i.e., the DC voltage of the DC bus 4. The sensor 22 outputs a voltage value Vdc that has been subjected to analog-to-digital conversion to the control circuit 23.

[0023] The control circuit 23 is configured to control the power conversion circuit 21 and is realized by, for example, a microcomputer. The control circuit 23 generates a drive signal based on the voltage value Vdc input from the sensor 22, and outputs the drive signal to the power conversion circuit 21. The control circuit 23 includes a subtractor 24, a correction unit 25, and a control unit 26 as functional components for controlling the DC voltage of the DC bus 4. The control circuit 23 also includes other functional components, but these are not shown or described here.

[0024] The subtractor 24 subtracts the voltage value Vdc input from the sensor 22 from a preset target value Vdc * By subtracting from the deviation ΔVdc (=Vdc * The subtractor 24 outputs the calculated deviation ΔVdc to the correction unit 25.

[0025] The correction unit 25 is a functional component that performs interference suppression processing to suppress control interference. The correction unit 25 corrects the deviation ΔVdc input from the subtractor 24 and outputs the corrected deviation ΔVdc′ to the control unit 26. The correction unit 25 will be described in detail later.

[0026] The control unit 26 has a functional configuration for performing proportional-integral-derivative control (PID control) based on the corrected deviation ΔVdc' input from the correction unit 25. The control unit 26 calculates and outputs a compensation value for making the corrected deviation ΔVdc' "0". The control unit 26 performs proportional calculation, integral calculation, and differential calculation on the corrected deviation ΔVdc', and calculates a compensation value based on the results of each calculation. The control circuit 23 generates a drive signal based on the compensation value calculated by the control unit 26 and outputs it to the power conversion circuit 21. The power conversion circuit 21 increases or decreases the input DC voltage and outputs it by turning on and off the switching element in accordance with the drive signal input from the control circuit 23. As a result, the DC voltage of the DC bus 4 is adjusted to the target value Vdc * is controlled by.

[0027] Next, the interference suppression process performed by the correction unit 25 will be described.

[0028] The voltage value Vdc input from the sensor 22 to the control circuit 23 contains a detection error in the sensor 22 and a conversion error during analog-to-digital conversion. These errors cause interference in the control by each power electronics device 2, so the deviation ΔVdc calculated by the subtractor 24 cannot maintain "0." Therefore, the output of the integral term, which is the result of the integration calculation in the control unit 26, increases, resulting in so-called windup. This destabilizes the control by each power electronics device 2. The correction unit 25 corrects the deviation ΔVdc to "0" within a range corresponding to the error contained in the voltage value Vdc and outputs it as a corrected deviation ΔVdc'. This prevents the output of the integral term in the control unit 26 from increasing, thereby preventing destabilization of the control by each power electronics device 2.

[0029] The thick solid line shown in Fig. 1(b) indicates the relationship between the deviation ΔVdc input to the correction unit 25 and the corrected deviation ΔVdc’ output from the correction unit 25. In Fig. 1(b), the horizontal axis represents the deviation ΔVdc input to the correction unit 25, and the vertical axis represents the corrected deviation ΔVdc’ output from the correction unit 25. In Fig. 1(b), the relationship between the deviation ΔVdc and the corrected deviation ΔVdc’ when the deviation ΔVdc is not corrected (ΔVdc’ = ΔVdc) is indicated by a dashed line. As shown by the thick solid line in Fig. 1(b), when the deviation ΔVdc is smaller than the first threshold value X1 and larger than the second threshold value X2 (=-X1) (X2 < ΔVdc < X1), the correction unit 25 outputs "0" as the corrected deviation ΔVdc’. Also, when the deviation ΔVdc is greater than or equal to the first threshold value X1 (X1 ≤ ΔVdc), the correction unit 25 outputs, as the corrected deviation ΔVdc’, a value obtained by subtracting the first threshold value X1 from the deviation ΔVdc (ΔVdc’ = ΔVdc - X1). Further, when the deviation ΔVdc is less than or equal to the second threshold value X2 (ΔVdc ≤ X2), the correction unit 25 outputs, as the corrected deviation ΔVdc’, a value obtained by subtracting the second threshold value X2 from the deviation ΔVdc (ΔVdc’ = ΔVdc - X2 = ΔVdc + X1).

[0030] The first threshold value X1 and the second threshold value X2 (=-X1) are set in advance. The first threshold value X1 is set according to the accuracy of the sensor 22, and a smaller value is set as the accuracy is higher. The first threshold value X1 is appropriately set based on experiments or simulations.

[0031] Fig. 2 is an example of a flowchart for explaining the interference suppression process performed by the correction unit 25. The interference suppression process is executed at predetermined timings from when the power conversion device 2 is started.

[0032] First, ΔVdc is acquired (S1). Specifically, the correction unit 25 acquires the deviation ΔVdc from the subtractor 24. Next, it is determined whether the absolute value of the deviation ΔVdc is smaller than the first threshold value X1 (S2). That is, it is determined whether (X2 < ΔVdc < X1). When the absolute value of the deviation ΔVdc is smaller than the first threshold value X1 (S2: YES), the corrected deviation ΔVdc’ is set to “0” (S3), the corrected deviation ΔVdc’ is output to the control unit 26 (S4), and the interference suppression process ends.

[0033] In step S2, when the absolute value of the deviation ΔVdc is greater than or equal to the first threshold value X1 (S2: NO), it is determined whether the deviation ΔVdc is greater than or equal to “0” (S5). When the deviation ΔVdc is greater than or equal to “0” (S5: YES), that is, when (X1 ≤ ΔVdc), the corrected deviation ΔVdc’ is set to the value obtained by subtracting the first threshold value X1 from the deviation ΔVdc (S6), the corrected deviation ΔVdc’ is output to the control unit 26 (S4), and the interference suppression process ends.

[0034] In step S5, when the deviation ΔVdc is less than “0” (S5: NO), that is, when (ΔVdc ≤ X2 = -X1), the corrected deviation ΔVdc’ is set to the value obtained by adding the first threshold value X1 to the deviation ΔVdc (S7), the corrected deviation ΔVdc’ is output to the control unit 26 (S4), and the interference suppression process ends. Note that the process shown in the flowchart of FIG. 2 is an example, and the interference suppression process performed by the correction unit 25 is not limited to the above-described one.

[0035] Next, the operation and effects of the control circuit 23 and the power conversion device 2 according to the present embodiment will be described.

[0036] According to the present embodiment, when the deviation ΔVdc input from the subtractor 24 is smaller than the first threshold value X1 and larger than the second threshold value X2, the corrector 25 outputs "0" as the corrected deviation ΔVdc' to the control unit 26. Therefore, even if the voltage value Vdc detected by the sensor 22 includes an error, when the deviation ΔVdc is smaller than the first threshold value X1 and larger than the second threshold value X2, "0" is input to the control unit 26 as the corrected deviation ΔVdc'. This prevents the output of the integral term from increasing in the control unit 26. Therefore, even when a plurality of power conversion devices 2 control the DC voltage of the DC bus 4, the power conversion device 2 can prevent destabilization of the control by each power conversion device 2.

[0037] Furthermore, according to this embodiment, when the deviation ΔVdc is equal to or greater than the first threshold X1 (X1≦ΔVdc), the correction unit 25 outputs, as the corrected deviation ΔVdc′, a value obtained by subtracting the first threshold X1 from the deviation ΔVdc (ΔVdc′=ΔVdc−X1). When the deviation ΔVdc is equal to or less than the second threshold X2 (ΔVdc≦X2), the correction unit 25 outputs, as the corrected deviation ΔVdc′, a value obtained by subtracting the second threshold X2 from the deviation ΔVdc (ΔVdc′=ΔVdc−X2=ΔVdc+X1). Therefore, the correction unit 25 can continuously change the corrected deviation ΔVdc′ around the first threshold X1 and the second threshold X2.

[0038] Furthermore, according to this embodiment, the sensor 22 detects the DC voltage of the DC bus 4. Therefore, the power conversion device 2 can control the DC voltage of the DC bus 4.

[0039] Furthermore, according to this embodiment, the control circuit 23 is simply a control circuit of a conventional power conversion device, with a correction unit 25 added between the subtractor 24 and the control unit 26. Therefore, the conventional power conversion device can be converted into the power conversion device 2 simply by changing the program of the control circuit. In other words, the time and cost required to convert the conventional power conversion device into the power conversion device 2 can be reduced.

[0040] In this embodiment, the first threshold value X1 and the second threshold value X2 have the same absolute value (X2=-X1), but this is not limiting. The first threshold value X1 and the second threshold value X2 may have different absolute values. For example, if the voltage value Vdc detected by the sensor 22 is likely to have an error in the increasing direction, the deviation ΔVdc is likely to be small. In this case, the second threshold value X2 may be set to a value whose absolute value is greater than the first threshold value X1.

[0041] In addition, in the present embodiment, the case where the control unit 26 performs proportional-integral-derivative control (PID control) has been described, but the present invention is not limited to this. The control unit 26 may perform proportional-integral control (PI control), integral control (I control), or integral-derivative control (ID control).

[0042] Furthermore, in the present embodiment, the case where the power converter 2 controls the DC voltage of the DC bus 4 has been described, but this is not limiting. The power converter 2 may control the DC current of the DC bus 4 by detecting the DC current of the DC bus 4, correcting the deviation ΔI between the detected value and its target value using the correction unit 25, and calculating a compensation value using the control unit 26. Similarly, the power converter 2 may control the DC power of the DC bus 4.

[0043] FIG. 3 is a diagram illustrating modified examples of the interference suppression process performed by the correction unit 25. FIG. 3(a) shows a first modified example, and FIG. 3(b) shows a second modified example. The thick solid lines shown in FIGS. 3(a) and 3(b) indicate the relationship between the deviation ΔVdc input to the correction unit 25 and the corrected deviation ΔVdc′ output from the correction unit 25, similar to FIG. 1(b). In FIGS. 3(a) and 3(b), the horizontal axis indicates the deviation ΔVdc input to the correction unit 25, and the vertical axis indicates the corrected deviation ΔVdc′ output from the correction unit 25. Note that in FIGS. 3(a) and 3(b), the dashed dotted line indicates the relationship between the deviation ΔVdc and the corrected deviation ΔVdc′ when no correction is made to the deviation ΔVdc (ΔVdc′=ΔVdc).

[0044] As shown by the thick solid line in Fig. 3(a), the correction unit 25 according to the first modification example also outputs "0" as the corrected deviation ΔVdc' when the deviation ΔVdc is smaller than the first threshold value X1 and larger than the second threshold value X2. Further, when the deviation ΔVdc is equal to or greater than the first threshold value X1 or equal to or less than the second threshold value X2, the correction unit 25 outputs the deviation ΔVdc as the corrected deviation ΔVdc'. According to the first modification example, when the deviation ΔVdc is equal to or greater than the first threshold value X1 or equal to or less than the second threshold value X2, the deviation ΔVdc is directly output as the corrected deviation ΔVdc', so that the correction unit 25 can improve the control accuracy.

[0045] As shown by the thick solid line in Fig. 3(b), the correction unit 25 according to the second modification example also outputs "0" as the corrected deviation ΔVdc' when the deviation ΔVdc is smaller than the first threshold value X1 and larger than the second threshold value X2. Further, when the deviation ΔVdc is equal to or greater than the third threshold value X3 (X3 > X1) or equal to or less than the fourth threshold value X4 (X4 < X2), the correction unit 25 outputs the deviation ΔVdc as the corrected deviation ΔVdc'. Further, when the deviation ΔVdc is equal to or greater than the first threshold value X1 and less than the third threshold value X3, the correction unit 25 outputs the calculation result of the following formula (1) as the corrected deviation ΔVdc'. Further, when the deviation ΔVdc is greater than the fourth threshold value X4 and equal to or less than the second threshold value X2, the correction unit 25 outputs the calculation result of the following formula (2) as the corrected deviation ΔVdc'. According to the second modification example, when the deviation ΔVdc is equal to or greater than the third threshold value X3 or equal to or less than the fourth threshold value X4, the deviation ΔVdc is directly output as the corrected deviation ΔVdc', so that the correction unit 25 can improve the control accuracy. Further, the correction unit 25 can continuously change the corrected deviation ΔVdc' before and after the first threshold value X1, the second threshold value X2, the third threshold value X3, and the fourth threshold value X4. ΔVdc'=(X3 / (X3 - X1))·(ΔVdc - X1) ··· (1) ΔVdc'=(X4 / (X4 - X2))·(ΔVdc - X2) ··· (2)

[0046] 〔Second Embodiment〕 FIG. 4 is a block diagram illustrating a storage battery system A2 according to a second embodiment, showing the internal configuration of the control circuit 23 of the power conversion device 2. In FIG. 4, elements that are the same as or similar to those in the first embodiment are given the same reference numerals. In the storage battery system A2, the configuration other than the control circuit 23 is the same as in the first embodiment, and therefore description and explanation thereof will be omitted. The storage battery system A2 according to this embodiment differs from the storage battery system A1 according to the first embodiment in that the control circuit 23 automatically sets the threshold value of the correction unit 25.

[0047] The control circuit 23 according to this embodiment further includes a threshold setting unit 27. The control unit 26 according to this embodiment outputs an integral term, which is the result of the integration calculation, to the threshold setting unit 27. The threshold setting unit 27 changes the first threshold X1 and the second threshold X2 according to the integral term input from the control unit 26 and sets them in the correction unit 25. If the integral term diverges, the threshold setting unit 27 increases the first threshold X1 and decreases the second threshold X2. In this case, the range in which the corrected deviation ΔVdc′ is “0” is widened, thereby suppressing the divergence of the integral term. On the other hand, if the integral term does not diverge, the threshold setting unit 27 decreases the first threshold X1 and increases the second threshold X2. In this case, the range in which the corrected deviation ΔVdc′ is “0” is narrowed, thereby improving the accuracy of control. This allows the control circuit 23 to suppress the divergence of the integral term while increasing the accuracy of control as much as possible.

[0048] In the present embodiment, too, when the deviation ΔVdc input from the subtractor 24 is smaller than the first threshold value X1 and larger than the second threshold value X2, the corrector 25 outputs “0” as the corrected deviation ΔVdc′ to the control unit 26. This prevents the output of the integral term from increasing in the control unit 26. Therefore, even when multiple power conversion devices 2 control the DC voltage of the DC bus 4, the power conversion device 2 can prevent destabilization of control by each power conversion device 2. Furthermore, the power conversion device 2 has a common configuration with the power conversion device 2 according to the first embodiment, thereby achieving the same effects as the power conversion device 2 according to the first embodiment. Furthermore, according to the present embodiment, the threshold setting unit 27 changes the first threshold value X1 and the second threshold value X2 according to the integral term input from the control unit 26 and sets them in the corrector 25. This allows the control circuit 23 to increase the accuracy of control as much as possible while suppressing divergence of the integral term.

[0049] Third Embodiment Fig. 5 is a block diagram illustrating a storage battery system A3 according to a third embodiment, showing the overall configuration of the storage battery system A3. In Fig. 5, elements that are the same as or similar to those in the first embodiment are denoted by the same reference numerals. The storage battery system A3 according to this embodiment differs from the storage battery system A1 according to the first embodiment in that it includes a DC / DC converter device 5 instead of the multiple power conversion devices 2 and a multiple power conversion devices 6 instead of the inverter device 3.

[0050] The storage battery system A3 includes a DC / DC converter device 5 instead of multiple power conversion devices 2. The DC / DC converter device 5 has one input / output terminal connected to the storage battery 1 and the other input / output terminal connected to multiple power conversion devices 6 via a DC bus 4. The DC / DC converter device 5 transforms the input DC voltage and outputs it.

[0051] Furthermore, the storage battery system A3 includes a plurality of power conversion devices 6 instead of the inverter device 3. Each of the plurality of power conversion devices 6 is an inverter device, with input / output terminals on the DC side connected to the DC bus 4 and input / output terminals on the AC side connected to the power grid. In other words, the power conversion devices 6 are connected in parallel with one another. Each power conversion device 6 converts AC power supplied from the power grid into DC power and outputs it to the DC bus 4, and converts DC power input from the DC bus 4 into AC power and supplies it to the power grid. The plurality of power conversion devices 6 have a common internal configuration.

[0052] The power conversion device 6 includes a power conversion circuit 61, a sensor 62, and a control circuit 63. The power conversion device 6 also includes sensors other than the sensor 62, but these are not shown or described here. The power conversion circuit 61 is a bidirectional inverter circuit that converts DC power to AC power, and performs conversion between DC power and AC power by turning on and off a switching element (not shown) in response to a drive signal input from the control circuit 63. The specific circuit configuration of the power conversion circuit 61 is not limited. The sensor 62 detects the DC voltage at the input / output terminal connected to the DC bus 4 of the power conversion circuit 61, i.e., the DC voltage of the DC bus 4. The sensor 62 outputs a voltage value Vdc that has been subjected to analog-to-digital conversion to the control circuit 63.

[0053] The control circuit 63 is configured to control the power conversion circuit 61, and is realized by, for example, a microcomputer. The control circuit 63 generates a drive signal based on the voltage value Vdc input from the sensor 62, and outputs the drive signal to the power conversion circuit 61. The control circuit 63 has a subtractor 24, a correction unit 25, and a control unit 26 as functional components for controlling the DC voltage of the DC bus 4, similar to the control circuit 23 according to the first embodiment. The control circuit 23 also has other functional components, but these will not be described or explained here. The power conversion circuit 61 converts DC power and AC power by turning on and off switching elements in response to the drive signal input from the control circuit 63. As a result, the DC voltage of the DC bus 4 is controlled to a target value Vdc * is controlled by.

[0054] Also in the present embodiment, when the deviation ΔVdc input from the subtractor 24 is smaller than the first threshold value X1 and larger than the second threshold value X2, the correction unit 25 outputs "0" as the corrected deviation ΔVdc' to the control unit 26. This prevents the output of the integral term from increasing in the control unit 26. Therefore, even when a plurality of power conversion devices 6 control the DC voltage of the DC bus 4, the power conversion device 6 can prevent the control by each power conversion device 6 from becoming unstable. Furthermore, the power conversion device 6 has a configuration in common with the power conversion device 2 according to the first embodiment, and therefore achieves the same effects as the power conversion device 2 according to the first embodiment.

[0055] As can be seen from the third embodiment, the power conversion device according to the present invention is not limited to a DC / DC converter device, but may be an inverter device or other power conversion devices. Furthermore, the power conversion device according to the present invention may control electrical characteristics (voltage, current, and power (active power, reactive power)) on the input side, or may control electrical characteristics on the output side. Furthermore, the object controlled by the power conversion device according to the present invention is not limited to direct current, but may also be alternating current.

[0056] In the first to third embodiments, the power conversion device 2 is described as being used in a storage battery system, but the present invention is not limited to this. The power conversion device 2 according to the present invention can also be used in other systems, such as a solar power generation system or an EV charging system.

[0057] The control circuit and the power conversion device including the control circuit according to the present invention are not limited to the above-described embodiment. The specific configurations of the control circuit and the power conversion device including the control circuit according to the present invention can be freely designed in various ways. [Explanation of symbols]

[0058] A1 to A3: storage battery system, 2, 6: power conversion device, 21, 61: power conversion circuit, 23, 63: control circuit, 24: subtractor, 25: correction unit, 26: control unit, 27: threshold setting unit

Claims

1. A control circuit for controlling an electrical characteristic of an output or an input of a power conversion circuit, a subtractor that calculates a deviation by subtracting a detected value of the electrical characteristic from a target value of the detected value; a correction unit that corrects the deviation to a corrected deviation; a control unit that calculates a compensation value by performing at least an integral operation on the corrected deviation; Equipped with When the deviation is smaller than a first threshold value and larger than a second threshold value, the correction unit outputs “0” as the corrected deviation. Control circuit.

2. The correction unit If the deviation is equal to or greater than the first threshold value, a value obtained by subtracting the first threshold value from the deviation is output as the corrected deviation; If the deviation is equal to or smaller than the second threshold value, a value obtained by subtracting the second threshold value from the deviation is output as the corrected deviation. The control circuit of claim 1 .

3. the detected value is a detected value of a DC voltage output by the power conversion circuit; The control circuit of claim 1 .

4. a threshold value setting unit that sets the first threshold value and the second threshold value; the threshold setting unit changes the first threshold and the second threshold in accordance with a calculation result of the integral calculation performed by the control unit. The control circuit of claim 1 .

5. a control circuit according to any one of claims 1 to 4; the power conversion circuit; Equipped with Power conversion device.

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