Power supply system

Abstract

This provides a power supply system that can stably control the current supplied to the load over the medium to long term. [Solution] The power supply system S comprises a power supply unit 1 that supplies current to a load L, a current detector 2 that detects the current value of the current, a feedback control unit 53 that controls the power supply unit 1 so that the current value approaches a set value, a digital signal generation unit 3 that generates a digital signal based on the current detection result by the current detector 2, a constant temperature chamber unit 4 that suppresses temperature changes of the digital signal generation unit 3, a first digital control unit 51 that detects abnormalities in the digital signal based on fluctuations in the digital signal, and a second digital control unit 52 that calculates a correction amount to correct the set value based on the digital signal and corrects the set value based on the correction amount. When the first digital control unit 51 detects an abnormality in the digital signal, the second digital control unit 52 corrects the set value based on the correction amount calculated before the abnormality was detected.

Description

[Technical Field]

[0001] This invention relates to a power supply system that provides feedback control of the current supplied to a load. [Background technology]

[0002] Generally, accelerators used in fields such as physical chemistry experiments and medicine are equipped with a power supply unit that supplies current to excite an electromagnet, which is the load, and a control unit that provides feedback control to the current supplied from the power supply unit to the electromagnet (see, for example, Patent Document 1).

[0003] Patent Document 1 describes a power supply device comprising a chopper circuit that supplies current to an electromagnet, a load current detector that detects the load current flowing through the electromagnet, and a control device that controls the chopper circuit based on information detected by the load current detector. The control device can stabilize the current supplied to the load by controlling the chopper circuit so that the load current value approaches the set value based on the current detection result from the load current detector and a predetermined set value. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2017-175732 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, due to the influence of external factors such as ambient temperature changes and voltage fluctuations, it may not be possible to accurately obtain information on the current value supplied to the load. Therefore, it is conceivable to adopt a configuration in which a digital signal generation unit installed in the constant temperature chamber is used to convert the analog signal indicating the current detection result from the current detector into a digital signal, and the set value is corrected based on that digital signal. By correcting the set value in this way, the current supplied to the load can be stabilized even when it is not possible to accurately obtain information on the current value due to the influence of external factors.

[0006] However, if an abnormality occurs in the digital signal generation unit due to a malfunction or other reason, it becomes impossible to obtain accurate current value information. Furthermore, if an abnormality occurs in the constant temperature chamber due to a malfunction or power outage, the digital signal generation unit may be affected by external factors, potentially preventing the acquisition of accurate current value information. In these cases, it becomes impossible to properly correct the set values, resulting in the problem of being unable to stably control the current supplied to the load over the medium to long term.

[0007] The present invention has been made in view of the above circumstances, and aims to provide a power supply system that can stably control the current supplied to a load over the medium to long term. [Means for solving the problem]

[0008] To solve the above problems, a power supply system according to the present invention includes a power supply unit that supplies current to a load, a current detector that detects the current value of the current, a feedback control unit that controls the power supply unit based on the current detection result by the current detector and a predetermined set value so that the current value approaches the set value, a digital signal generation unit that generates a digital signal corresponding to the current detection result based on an analog signal indicating the current detection result by the current detector, a thermostat unit that suppresses temperature changes of the digital signal generation unit, a correction amount calculation unit that calculates a correction amount for correcting the set value based on the digital signal, a set value correction unit that corrects the set value based on the correction amount, and an abnormality detection unit that detects an abnormality of the digital signal based on fluctuations of the digital signal. The set value correction unit corrects the set value based on the correction amount calculated before the abnormality is detected when the abnormality detection unit detects the abnormality.

[0009] According to the above configuration, an abnormality of the digital signal is detected based on fluctuations of the digital signal. When an abnormality of the digital signal is detected, the set value is corrected based on the correction amount calculated before the abnormality is detected. Therefore, even when an abnormality occurs in the digital signal generation unit or the thermostat unit, the set value can be appropriately corrected so that the abnormality is not reflected in the feedback control, and the current supplied to the load can be stabilized in the medium and long term.

[0010] In the above power supply system, it is preferable that the current detector includes a first current detector that outputs an analog signal indicating the current detection result to the feedback control unit and a second current detector that outputs an analog signal indicating the current detection result to the digital signal generation unit.

[0011] In the above power supply system, it is preferable that the set value correction unit sets the correction amount to 0 when an instruction to invalidate the correction of the set value is input.

[0012] In the above power supply system, it is preferable that the correction amount calculation unit calculates the correction amount at a predetermined correction amount calculation cycle, and the set value correction unit determines an actual correction amount targeted at the correction amount at a cycle shorter than the correction amount calculation cycle, and corrects the set value by adding the actual correction amount to the set value.

[0013] In the above power supply system, it is preferable that the set value correction unit corrects the set value by adding the correction amount to the set value when a predetermined condition is satisfied.

Advantages of the Invention

[0014] According to the present invention, it is possible to provide a power supply system capable of stably controlling the current supplied to a load in the medium and long term.

Brief Description of the Drawings

[0015] [Figure 1] (A) and (B) are schematic configuration diagrams of a power supply system according to an embodiment of the present invention. [Figure 2] It is a flowchart of normal / abnormal determination processing of a digital signal according to the embodiment. [Figure 3] It is a flowchart of normal / abnormal determination processing of a digital signal according to the embodiment. [Figure 4] It is a flowchart of correction amount setting processing according to the embodiment. [Figure 5] It is a flowchart of set value correction processing according to the embodiment. [Figure 6] It is a timing chart showing a change example of the correction amount and the actual correction amount. [Figure 7] It is a schematic configuration diagram of a power supply system according to a modification example.

Modes for Carrying Out the Invention

[0016] Referring to the drawings, a power supply system S according to an embodiment of the present invention will be described. As shown in Figure 1(A), the power supply system S comprises a power supply unit 1, a current detector 2, a digital signal generation unit 3, a constant temperature bath unit 4, and a control unit 5.

[0017] Power supply unit 1 supplies direct current to the load L, which is an electromagnet (inductive load) of the accelerator. Power supply unit 1 includes an AC / DC converter 11 that converts AC power input from an external power supply P, which is a three-phase AC power supply, into DC power, a capacitor unit 12 that stores DC power, and a DC / DC converter 13 that converts the DC power stored in the capacitor unit 12 into a desired DC power suitable for the load L. The DC / DC converter 13 is composed of IGBTs (Insulated Gate Bipolar Transistors) and supplies the DC power after power conversion to the load L.

[0018] The current detector 2 detects the current value of the current supplied from the power supply unit 1 to the load L. The current detector 2 includes current detectors 2P and 2N as first current detectors and current detector 2D as a second current detector, and each of the current detectors 2P, 2N, and 2D is composed of a direct current-current transformer (DCCT).

[0019] Current detectors 2P and 2N are DCCTs for feedback control, and are connected to the positive power line L of the load L. P and the negative terminal power line L N The current detectors 2P and 2N input analog signals indicating the current detection result to the feedback control unit 53 (see Figure 1(B)), which will be described later. Current detector 2P outputs an analog signal indicating a positive current flowing from the power supply unit 1 to the load L, and current detector 2N outputs an analog signal indicating a positive current flowing from the load L to the power supply unit 1.

[0020] The current detector 2D is a DCCT for generating digital signals in the constant temperature bath section 4, and the power lines L on the positive and negative sides P ,L N On the other hand (in this embodiment, the positive terminal power line L) PIt is located in the ). The current detector 2D inputs an analog signal indicating the current detection result to the digital signal generation unit 3.

[0021] The digital signal generation unit 3 generates a digital signal corresponding to the current detection result based on the analog signal indicating the current detection result from the current detector 2D. In other words, the digital signal generation unit 3 converts the analog signal indicating the current detection result into a digital signal. The digital signal generation unit 3 is composed of a DMM (Digital Multi Meter).

[0022] The constant temperature chamber 4 suppresses temperature changes in the digital signal generation unit 3. Specifically, the constant temperature chamber 4 forms a space that houses the digital signal generation unit 3 and suppresses temperature and humidity changes in this space. In this way, the constant temperature chamber 4 prevents the digital signals generated by the digital signal generation unit 3 from being affected by external factors by suppressing temperature changes in the digital signal generation unit 3.

[0023] The control unit 5 controls the operation of the power supply unit 1 by controlling the switching elements that make up the AC / DC conversion unit 11 and the DC / DC conversion unit 13. The control unit 5 receives analog signals indicating the current detection results from the current detectors 2P and 2N, as well as digital signals corresponding to the current detection results from the current detector 2D (i.e., digital signals generated by the digital signal generation unit 3).

[0024] As shown in Figure 1(B), the control unit 5 includes a first digital control unit 51 that functions as an anomaly detection unit, a second digital control unit 52 that functions as a correction amount calculation unit and a set value correction unit, and a feedback control unit 53.

[0025] The first digital control unit 51 is a digital control unit configured by a PLC (Programmable Logic Controller). The first digital control unit detects abnormalities in the digital signal based on fluctuations in the digital signal generated by the digital signal generation unit 3 by performing normal / abnormal determination processing of the digital signal, which will be described later. When the digital signal is abnormal, it can be said that there is an abnormality in the digital signal generation unit 3 that generates the digital signal, or that the digital signal generation unit 3 is normal but there is an abnormality in the constant temperature chamber unit 4 that suppresses temperature changes etc. in the digital signal generation unit 3. Therefore, the first digital control unit 51 detects an abnormality in either the digital signal generation unit 3 or the constant temperature chamber unit 4 by detecting an abnormality in the digital signal. The first digital control unit 51 also transmits information necessary for the operation of the second digital control unit 52 (for example, information input from the digital signal generation unit 3 and processing information in the first digital control unit 51) to the second digital control unit 52.

[0026] The second digital control unit 52 is a digital control unit configured using an FPGA (Field Programmable Gate Array). The second digital control unit 52 calculates a correction amount to correct the set value based on the digital signal generated by the digital signal generation unit 3 by performing a correction amount setting process, which will be described later. The second digital control unit 52 also corrects the set value based on the correction amount by performing a set value correction process, which will be described later, and transmits a digital signal indicating the set value to the feedback control unit 53.

[0027] However, when the set value is corrected at the same cycle as the correction amount is calculated, if the correction amount fluctuates significantly, the set value is also corrected to fluctuate significantly, which leads to a problem where the current supplied to the load L fluctuates significantly. Therefore, in this embodiment, suppressing large current fluctuations caused by the correction of the set value is also an objective. To solve this problem, the second digital control unit 52 determines an actual correction amount with a target correction amount at a shorter cycle than the correction amount calculation cycle described later, and corrects the set value by adding the actual correction amount to the set value. Furthermore, when a predetermined condition is met (specifically, when it is a non-gradual correction time described later), the second digital control unit 52 corrects the set value by adding the correction amount to the set value.

[0028] The feedback control unit 53 is a circuit that controls the DC / DC converter 13 of the power supply unit 1 so that the current value supplied to the load L approaches the set value, based on the current detection result from the current detector 2 and the set value. Specifically, the feedback control unit 53 controls the IGBTs that make up the DC / DC converter 13 based on the analog signals indicating the current detection results from the current detectors 2P and 2N and the set value output by the second digital control unit 52. The DC / DC converter 13 is controlled with a period of less than 1 millisecond (on the order of kilohertz) based on the current detection results from the current detectors 2P and 2N and the set value, while the correction amount for correcting the set value is calculated with a correction amount calculation period on the order of minutes, which will be described later.

[0029] The feedback control unit 53 includes a D / A conversion unit 53A, an average current signal generation unit 53B, a deviation signal generation unit 53C, and a PWM (Pulse Width Modulation) control unit 53D. The D / A conversion unit 53A converts a digital signal indicating a set value into an analog signal and generates an analog set value signal. The average current signal generation unit 53B calculates an arithmetic mean of the analog signals indicating the current detection results from the current detectors 2P and 2N and generates a current value signal. The deviation signal generation unit 53C generates a deviation signal representing the deviation of the current value relative to the set value, based on the set value signal and the current value signal. The PWM control unit 53D performs PWM control on the IGBTs constituting the DC / DC conversion unit 13 based on the deviation signal. Specifically, the PWM control unit 53D generates a gate signal with a pulse width such that the above deviation approaches 0, based on the deviation signal, and inputs it to the gate of the IGBT in the DC / DC conversion unit 13.

[0030] Referring to Figures 2 and 3, the flow of the normal / abnormal determination process for digital signals will be explained. The normal / abnormal determination process for digital signals starts when the power supply unit 1 is started up. First, the first digital control unit 51 waits from the start time of the power supply unit 1 until a predetermined initial drift time has elapsed (step S1). The initial drift time is, for example, the time from when the set value (command current value) reaches a certain value of 100A or more (for example, 200A) until a certain period of time (for example, 10 seconds) has elapsed.

[0031] Next, the first digital control unit 51 determines whether the current supplied from the power supply unit 1 to the load L is stable based on the digital signal generated by the digital signal generation unit 3 (i.e., the digital signal corresponding to the current detection result) (step S2). If the current supplied to the load L rises or falls significantly, the first digital control unit 51 determines that the current is unstable (step S2: NO) and repeats the determination in step S2 without proceeding to step S3 described later.

[0032] When the current supplied to the load L neither increases nor decreases significantly, the first digital control unit 51 determines that the current is stable (step S2: YES), and further waits until both a predetermined digital signal monitoring start time and a non-sequential correction time described later have elapsed since the current became stable (step S3). The digital signal monitoring start time is, for example, 900 seconds (15 minutes). The non-sequential correction time is, for example, a time obtained by multiplying the correction amount calculation period described later by (any natural number + 0.5).

[0033] Next, the first digital control unit 51 performs initialization processing (step S4). Specifically, the first digital control unit 51 sets the digital signal state parameter to "normal", sets the abnormal determination value C1 and the normal determination value C2 to 0, and sets the value indicated by the digital signal generated by the digital signal generation unit 3 as the first current value X0. The digital signal state parameter is a flag representing the state of the digital signal. In this specification, "normal" represents a value indicating that the digital signal is normal, and "abnormal" represents a value indicating that the digital signal is abnormal.

[0034] Next, the first digital control unit 51 acquires the value indicated by the digital signal input from the digital signal generation unit 3 as a new current value X (step S5), and calculates a change amount Δδ representing the degree of change in the current value X based on the current value X this time and the previous time (step S6).

[0035] Specifically, in the first step S6, the first digital control unit 51 calculates the difference Y1 (Y1 = |X0 - X R |) between the current value X0 acquired in step S4 and the set value X R and the difference Y2 (Y2 = |X1 - X R |) between the current value X1 acquired in step S5 and the set value X R and calculates the change amount Δδ (Δδ = |Y1 - Y2|), which is the difference between the differences Y1 and Y2. Also, when N is an integer of 2 or more, in the Nth step S6, the first digital control unit 51 calculates the difference between the current value X N acquired in the (N - 1)th step S5 and the set value XR The difference between Y1 and |X N-1 -X R |) and the current value X obtained in the Nth step S5. N and the set value X R The difference between Y2 and |X N -X R |) is calculated, and the change amount Δδ is calculated.

[0036] Next, the first digital control unit 51 compares the change amount Δδ calculated in step S6 with a predetermined threshold Z to determine whether the change amount Δδ exceeds the threshold Z (step S11).

[0037] When the first digital control unit 51 determines that "Δδ>Z" is true and the change amount Δδ exceeds the threshold Z (step S11: YES), it increments the abnormality determination value C1 (step S12), and further determines whether the abnormality determination value C1 is less than or equal to a predetermined threshold CR1 (step S13). If the abnormality determination value C1 is less than or equal to the threshold CR1 (step S13: YES), the first digital control unit 51 repeats steps S5 onward without proceeding to step S14 described later.

[0038] If the abnormality determination value C1 exceeds the threshold CR1 (step S13: NO), the first digital control unit 51 determines that the digital signal generated by the digital signal generation unit 3 is abnormal and detects the abnormality of the digital signal (step S14). In this way, when the first digital control unit 51 determines that the digital signal is abnormal, if the digital signal status parameter is "normal", it sets the parameter to "abnormal", and if the digital signal status parameter is "abnormal", it maintains the parameter. Then, the first digital control unit 51 resets the determination values ​​C1 and C2 to 0 and repeats steps S5 onwards.

[0039] On the other hand, when the first digital control unit 51 determines that "Δδ≦Z" is true and the change amount Δδ does not exceed the threshold Z (step S11:NO), it counts up the normal determination value C2 (step S15), and further determines whether the normal determination value C2 is less than or equal to a predetermined threshold CR2 (step S16). If the normal determination value C2 is less than or equal to the threshold CR2 (step S16:YES), the first digital control unit 51 repeats steps S5 onwards without proceeding to step S17 described later.

[0040] If the normal determination value C2 exceeds the threshold CR2 (step S16: NO), the first digital control unit 51 determines that the digital signal generated by the digital signal generation unit 3 is normal (step S14). When the first digital control unit 51 determines that the digital signal is normal, it maintains the digital signal state parameter if it is "normal", and sets the digital signal state parameter to "normal" if it is "abnormal". Then, the first digital control unit 51 resets the determination values ​​C1 and C2 to 0 and repeats steps S5 onward.

[0041] As described above, the first digital control unit 51 detects an abnormality in the digital signal (current value X) based on the fluctuation of the digital signal. The first digital control unit 51 transmits a digital signal status parameter indicating the result of detecting the abnormality in the digital signal to the second digital control unit 52.

[0042] Referring to Figure 4, the flow of the correction amount setting process will be explained. The correction amount setting process starts after the initial drift time has elapsed since the power supply unit 1 started up. First, the second digital control unit 52 performs an initialization process to set the correction amount to 0 (step S21).

[0043] Next, the second digital control unit 52 obtains the value indicated by the digital signal generated by the digital signal generation unit 3 as the current value X, and calculates the average value X of the current value X by a simple moving average of the most recent time-series data, the current value X. ACalculate (Step S22).

[0044] Next, the second digital control unit 52 sets the set value X R Obtain the average value X A and the set value X R The difference between ΔX and |X A -X R |) is calculated (step S23), and it is determined whether the predetermined correction amount update conditions are met (step S24).

[0045] The correction amount update conditions include, for example, the following conditions A to F. In step S24, the second digital control unit 52 determines that the correction amount update conditions are met if all of conditions A to F are met, and determines that the correction amount update conditions are not met if at least one of conditions A to F is not met. Condition A: The difference ΔX calculated in step S23 is equal to the predetermined comparison value T. A Smaller than (ΔX <T A ) Condition B: A predetermined waiting period T after the difference ΔX calculated in step S23 becomes 0. B The time has passed. Condition C: The above initial drift time has elapsed since power supply unit 1 started operating. Condition D: The difference ΔX calculated in step S23 is equal to the predetermined correction tolerance threshold T. D Smaller than (ΔX <B) Condition E: The digital signal status parameter is 'normal'. Condition F: Setting value X R After the value becomes constant, a predetermined waiting period T F The time has passed.

[0046] When the second digital control unit 52 determines that the correction amount update condition is met (step S24: YES), it calculates the product of the difference ΔX calculated in step S23 and a predetermined gain G, and sets the correction amount to the product (ΔX × G) (step S25). In this way, in step S25, the second digital control unit 52 updates the correction amount based on the current value X. When the correction amount update condition is met, the second digital control unit 52 is configured to calculate the correction amount at a predetermined correction amount calculation cycle (for example, a 1-minute cycle), and therefore steps S22 to S24 are also repeated at the correction amount calculation cycle.

[0047] On the other hand, if the second digital control unit 52 determines that the correction amount update condition is not met (step S24: NO), it does not set (update) the correction amount in step S25 and maintains the correction amount that has already been set.

[0048] Furthermore, the second digital control unit 52 determines whether or not an instruction to disable the correction of the set value has been input from an external source (step S26). If no instruction to disable the correction of the set value has been input (step S26: NO), the second digital control unit 52 does not set the correction amount in step S27, which will be described later, and repeats steps S22 onwards.

[0049] On the other hand, when an instruction to disable the correction of the set value is input to the second digital control unit 52 (step S26: YES), the correction amount is set to 0 (step S27), and steps S22 onwards are repeated.

[0050] As described above, when an abnormality in the digital signal is detected (i.e., when condition E is not met), the second digital control unit 52 does not update the correction amount in step S25, but maintains the correction amount calculated before the abnormality was detected. In addition, when an instruction to disable the correction of the set value is input to the second digital control unit 52, the correction amount is set to 0.

[0051] The flow of the setpoint correction process will be explained with reference to Figures 5 and 6. The setpoint correction process starts when the initial drift time has elapsed since the power supply unit 1 started up, and is performed at a shorter cycle than the correction amount calculation cycle (for example, a 1-second cycle).

[0052] First, the second digital control unit 52 determines whether the correction amount is 0 or not based on the correction amount set in the correction amount setting process (step S31). If the correction amount is 0 (step S31: YES), the second digital control unit 52 does not proceed to steps S34 and S37 described later, and does not correct the set value.

[0053] On the other hand, the second digital control unit 52 determines whether the current time is non-gradual correction time (step S32) if the correction amount is not zero (step S31: NO). Non-gradual correction time is the time from when the initial drift time has elapsed until a certain period of time has elapsed, and the time from when the digital signal state parameter switches from "abnormal" to "normal" until a certain period of time has elapsed.

[0054] When the second digital control unit 52 determines that the current time is a non-gradual correction time (step S32: YES), it corrects the set value output to the feedback control unit 53 by adding the correction amount set in the correction amount setting process as the actual correction amount to the set value (step S33).

[0055] On the other hand, when the second digital control unit 52 determines that the current time is not a non-gradual correction time (step S32: NO), it sets the correction amount set in the correction amount setting process as the target correction amount (step S34), determines an actual correction amount with the correction amount as the target based on the target correction amount and the most recent actual correction amount (step S35), and corrects the set value output to the feedback control unit 53 by adding the actual correction amount to the set value (step S36).

[0056] Specifically, in step S35, if the target correction amount is greater than the most recent actual correction amount, the second digital control unit 52 sets the new actual correction amount to the value representing the most recent actual correction amount plus 1. On the other hand, if the target correction amount is less than the most recent actual correction amount, the second digital control unit 52 sets the new actual correction amount to the value representing the most recent actual correction amount minus 1. Furthermore, if the target correction amount is the same as the most recent actual correction amount, the second digital control unit 52 maintains the most recent actual correction amount.

[0057] As described above, when the second digital control unit 52 detects an abnormality in the digital signal, it maintains the correction amount calculated before the abnormality was detected, and therefore corrects the set value based on the correction amount calculated before the abnormality was detected. Furthermore, since the set value correction process is repeated at a shorter interval than the correction amount calculation cycle, the second digital control unit 52 corrects the set value at a shorter interval than the correction amount calculation cycle.

[0058] Figure 6 illustrates the relationship between the correction amount set during the correction amount setting process and the actual correction amount set based on that correction amount. The black dots in Figure 6 represent the correction amount, and the line graph in Figure 6 represents the actual correction amount.

[0059] From the time T0 when the power supply unit 1 starts until the initial drift time has elapsed, no correction amount setting process is performed, and no correction amount based on the current detection result is calculated. When the correction amount is calculated at times T1 and T2, which are non-gradual correction times after the initial drift time has elapsed, the correction amount set in the correction amount setting process becomes the actual correction amount. When the correction amount is calculated at time T3, which is after the non-gradual correction time has elapsed, the actual correction amount changes stepwise from time T3 towards the target correction amount. In this way, from time T3 to T8, which are not non-gradual correction times, the correction amount set in the correction amount setting process becomes the target correction amount, and the actual correction amount changes so that it gradually approaches the target correction amount.

[0060] If an abnormality in the digital signal is detected immediately before time T8 (i.e., the digital signal status parameter becomes "abnormal"), the correction amount is not updated, and the correction amount from before the abnormality was detected is maintained. When the correction amount is calculated at times T10 and T11, after the abnormality in the digital signal generation unit 3 or the constant temperature bath unit 4 has been resolved and the digital signal has returned to normal (i.e., the digital signal status parameter has become "normal"), the correction amount set in the correction amount setting process becomes the actual correction amount because it is the non-gradual correction time until a certain amount of time has elapsed since the digital signal status parameter switched from "abnormal" to "normal".

[0061] When the correction amount is calculated at time T12, after the non-gradual correction time has elapsed, the actual correction amount changes gradually from time T12. In this way, at times T12 and T13, which are not part of the non-gradual correction time, the actual correction amount changes so that it gradually approaches the target correction amount, with the correction amount set in the correction amount setting process being used as the target correction amount.

[0062] In this embodiment, the following effects can be obtained. (1) Based on fluctuations in the generated digital signal, abnormalities in the digital signal can be detected. When an abnormality in the digital signal is detected, the set value is corrected based on the correction amount calculated before the abnormality was detected. Therefore, even if an abnormality occurs in the digital signal generation unit 3 or the constant temperature chamber unit 4, the set value can be appropriately corrected so that the abnormality is not reflected in the feedback control, and the current supplied to the load L can be stabilized over the medium to long term.

[0063] (2) The current detector 2 includes current detectors 2P and 2N (first current detectors) that output analog signals indicating the current detection result to the feedback control unit 53, and a current detector 2D (second current detector) that outputs analog signals indicating the current detection result to the digital signal generation unit 3. With this configuration, if an abnormality (e.g., a break in the wire) occurs in the current detectors 2P and 2N, it is possible to detect the abnormality in the current detectors 2P and 2N based on the current detection result from the current detector 2D.

[0064] (3) The second digital control unit 52 (set value correction unit) determines an actual correction amount with a target correction amount at a shorter cycle than the correction amount calculation cycle, and corrects the set value by adding the actual correction amount to the set value. With this configuration, it is possible to correct the set value in detail, and thus large fluctuations in the current supplied to the load L caused by the correction of the set value can be suppressed.

[0065] (4) When it is a non-gradual correction time (when a predetermined condition is met), the second digital control unit 52 corrects the set value by adding the correction amount to the set value. With this configuration, it is possible to prevent a large discrepancy between the correction amount and the actual correction amount.

[0066] The present invention is not limited to the embodiments described above, and the above configuration can be modified. For example, it can be implemented with the following modifications, or a combination of the following modifications can be used.

[0067] In the above embodiment, the feedback control unit 53 was configured to control the DC / DC conversion unit 13 by performing analog signal processing. However, a configuration in which the DC / DC conversion unit 13 is controlled by performing digital signal processing may also be adopted. This modified example will be described with reference to Figure 7. Note that the same configuration as in the above embodiment will not be described.

[0068] As shown in Figure 7, the modified feedback control unit 53 includes an average current signal generation unit 53B, an A / D conversion unit 53E, and a second digital control unit 52. The A / D conversion unit 53E converts an analog current value signal into a digital current value signal.

[0069] The second digital control unit 52 not only functions as a correction amount calculation unit and a set value correction unit, but also calculates the deviation of the current value relative to the set value based on the digital current value signal, generates a gate signal with a pulse width such that this deviation approaches 0, and inputs it to the gate of the IGBT of the DC / DC conversion unit 13.

[0070] Furthermore, in the above embodiment, the second digital control unit 52 changes the actual correction amount by 1 in step S36, but the amount of change in the actual correction amount may be changed as appropriate, as long as the actual correction amount can be gradually brought closer to the target correction amount.

[0071] Furthermore, while the correction amount update conditions in the above embodiment required all of conditions A to F to be met, if condition E is included, one or more of conditions A to D and F may be deleted, or other conditions may be added. In other words, the correction amount update conditions may be changed as appropriate, as long as the correction amount before the abnormality of the digital signal is maintained.

[0072] In the above embodiment, the configuration detected anomalies in the digital signal based on the change amount Δδ, which is the difference between the differences Y1 and Y2, but the current value X N and current value X N-1 The difference between the two is the change Δδ (Δδ = |X N-1 -X N A configuration that detects abnormalities in digital signals based on |) may also be adopted. Furthermore, the current value X N and the most recent current value X N-1 ,…,X N-k The mean value X calculated by the simple moving average of A The difference between the two is the change Δδ (Δδ = |X A -X N A configuration that detects abnormalities in the digital signal based on |) may be adopted. In other words, if abnormalities in the digital signal can be detected based on fluctuations in the digital signal, the operation of the first digital control unit 51 may be changed as appropriate. [Explanation of Symbols]

[0073] 1 Power supply section 2 Current detectors 2P, 2N current detector (first current detector) 2D current detector (second current detector) 3. Digital signal generation unit 4 Constant temperature chamber 5. Control Unit 51 First Digital Control Unit (Anomaly Detection Unit) 52 Second Digital Control Unit (Correction Amount Calculation Unit, Set Value Correction Unit) 53 Feedback Control Unit L load P External power supply S Power System

Claims

1. A power supply unit that supplies current to the load, A current detector for detecting the current value of the aforementioned current, A feedback control unit controls the power supply unit so that the current value approaches the set value based on the current detection result from the current detector and a predetermined set value. A digital signal generation unit generates a digital signal corresponding to the current detection result based on an analog signal indicating the current detection result from the current detector, A constant temperature chamber for suppressing temperature changes in the digital signal generation unit, A correction amount calculation unit calculates a correction amount for correcting the set value based on the digital signal, A setting value correction unit that corrects the setting value based on the correction amount, The system includes an abnormality detection unit that detects abnormalities in the digital signal based on fluctuations in the digital signal, When the abnormality detection unit detects an abnormality, the setting value correction unit corrects the setting value based on the correction amount calculated before the abnormality was detected. A power supply system characterized by the following features.

2. The current detector includes a first current detector that outputs an analog signal indicating the current detection result to the feedback control unit, and a second current detector that outputs an analog signal indicating the current detection result to the digital signal generation unit. The power supply system according to feature 1.

3. The setting value correction unit sets the correction amount to 0 when an instruction to disable the correction of the setting value is input. The power supply system according to claim 1 or 2, characterized by the features described above.

4. The correction amount calculation unit calculates the correction amount at a predetermined correction amount calculation cycle, The setting value correction unit determines an actual correction amount targeting the correction amount at a shorter cycle than the correction amount calculation cycle, and corrects the setting value by adding the actual correction amount to the setting value. The power supply system according to claim 1 or 2, characterized by the features described above.

5. The setting value correction unit corrects the setting value by adding the correction amount to the setting value when a predetermined condition is met. The power supply system according to feature 4.

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