Power supply control circuit and power supply control method

Abstract

To provide a power supply control circuit and a power supply control method for improving undershoot of current generated when a constant current constant voltage power supply is turned off.SOLUTION: In a power supply circuit 1, a control unit that outputs a control value to a power unit includes: a voltage control unit configured to operate in a voltage control mode in which the control value is output so that a voltage measurement value of a power supply becomes a voltage target value; a current control unit configured to operate in a current control mode in which the control value is output so that a current measurement value of the power supply becomes a current target value; a selection unit 23 connected to respective output sides of the control units and configured to output the control value in one of both the control modes; an auxiliary current control unit 24 configured to operate in an auxiliary current control mode in which the control value is output so as to reduce an error between a predetermined current command value and the current measurement value; and a combining unit 25 connected to respective output sides of the selection unit and the auxiliary current control unit and configured to output the control value to the power unit in the control mode output by the selection unit when the power supply is turned on and to output the control value to the power unit in the auxiliary current control mode when the power supply is turned off.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power supply control circuit and a power supply control method. [Background technology]

[0002] Patent Document 1 describes a method for addressing the problem of control instability caused by a change in the manipulated variable when control is switched from constant current (CC) control to constant voltage (CV) control or from CV control to CC control, by applying a filter to the selected manipulated variable to ensure stability when control is switched. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-17890 Summary of the Invention [Problem to be solved by the invention]

[0004] The device described in Patent Document 1 allows control of the manipulated variable (control value) when both the voltage and current are positive outputs, or when both the voltage and current are negative outputs. For this reason, for example, if the voltage is positive output and the current flows in the negative direction when turning off a constant current / constant voltage power supply, the current cannot be controlled, and current undershoot (a phenomenon in which a negative current flows) may occur. Turning off a constant current / constant voltage power supply refers to stopping the flow of current to the constant current / constant voltage power supply or shutting off the constant current / constant voltage power supply. [Means for solving the problem]

[0005] In one aspect of an embodiment of the present invention, a power supply control circuit that outputs a control value to a power section of a power supply includes: a voltage control section that operates in a voltage control mode that outputs a control value so that a measured voltage value of the power supply becomes a target voltage value; a current control section that operates in a current control mode that outputs a control value so that a measured current value of the power supply becomes a target current value; a selection section that is connected to the output sides of the voltage control section and the current control section and outputs a control value in either the voltage control mode or the current control mode; an auxiliary current control section that operates in an auxiliary current control mode that outputs a control value so as to reduce an error between a predetermined current command value and a measured current value; and a synthesis section that is connected to the output sides of the selection section and the auxiliary current control section and outputs a control value to the power section in the control mode output by the selection section when the power supply is turned on, and outputs a control value to the power section in the auxiliary current control mode when the power supply is turned off. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a technique capable of improving the current undershoot that occurs when a constant-current, constant-voltage power supply is turned off. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating an example of a power supply circuit including a power supply control circuit according to an embodiment of the present invention; [Figure 2] FIG. 4 is a diagram showing a controllable range of voltage and current control. [Figure 3] FIG. 1 is a diagram illustrating an example of a power supply circuit including a power supply control circuit according to a comparative example. [Figure 4] 10 shows the measurement results of voltage and current control in the comparative example and the example. [Figure 5] 10 is a flowchart showing a processing procedure related to command processing. DETAILED DESCRIPTION OF THE INVENTION

[0008] (Embodiment 1) Hereinafter, the present embodiment will be described with reference to the drawings. In the following description, the same or equivalent elements are designated by the same reference numerals, and redundant description will not be repeated. The dimensional ratios of the drawings do not necessarily match those in the description. The terms "upper," "lower," "left," and "right" are based on the state shown in the drawings and are for convenience only.

[0009] Fig. 1 is a diagram showing an example of a power supply circuit 1 equipped with a power supply control circuit according to this embodiment. The power supply circuit 1 shown in Fig. 1 is a circuit that controls a constant voltage constant current power supply (hereinafter, this may be simply referred to as a power supply) that can apply a constant voltage and a constant current.

[0010] The power supply circuit 1 includes a control unit 2 (an example of a power supply control circuit) and a power unit 3. In the example shown in Fig. 1, the power supply circuit 1 applies a constant voltage and a constant current to a load 4 as a pseudo workpiece.

[0011] The control unit 2 outputs a control value to the power unit 3 of the constant-voltage constant-current power supply. The control value is, for example, a voltage value. The power unit 3 operates the constant-voltage constant-current power supply based on the control value output from the control unit 2, and applies an output voltage Vout to a load 4.

[0012] The voltage applied to the load 4 is measured by a voltmeter. The current applied to the load 4 is measured by an ammeter. Based on the measured voltage and current, the control value is adjusted in the control unit 2. As a result, a constant current and a constant voltage are applied even if the load on the load 4 changes.

[0013] The control unit 2 includes a voltage control unit 21, a current control unit 22, a selection unit 23, a turn-off current control unit 24, and a combining unit 25. The turn-off current control unit 24 is given as an example of an auxiliary current control unit that assists in current control during turn-off.

[0014] The voltage control unit 21 operates in a voltage control mode in which it outputs a control value so that the measured voltage value of the constant-voltage constant-current power supply becomes the target voltage value. The voltage control unit 21 outputs a control value adjusted to cancel out the error between the voltage command value Vref1 and the measured voltage value Vreal1.

[0015] The voltage control unit 21 has a first input terminal for inputting a voltage command value Vref1, a first resistor R1 connected to the first input terminal, a second input terminal for inputting a voltage measurement value Vreal1, a second resistor R2 connected to the second input terminal, and a first operational amplifier U1 which is an error amplifier.

[0016] For example, feedback control such as PI (Proportional-Integral) control is performed using a first operational amplifier U1, a capacitor connected in parallel to the first operational amplifier U1, and a first resistor R1 or a second resistor R2 connected in series to the first operational amplifier U1.

[0017] As shown in Figure 1, a resistor may be connected in series to the capacitor connected in parallel to the first operational amplifier U1. For example, feedback control refers to control in which an output value output based on an input value is compared with a target value (e.g., 0 when turned off in this embodiment) and the output is reflected in the input value. A resistor connected in series to the capacitor connected in parallel to the first operational amplifier U1 is connected to adjust the time required to turn on or off the constant current / constant voltage power supply. Turning on the constant current / constant voltage power supply refers to starting to supply current to the constant current / constant voltage power supply or turning on the constant current / constant voltage power supply.

[0018] The voltage command value Vref1 is the target voltage value of the constant-voltage constant-current power supply. The voltage command value Vref1 is set to any value within the performance range of the constant-voltage constant-current power supply. The voltage measurement value Vreal1 is a voltage value measured by a voltmeter connected to the load 4. The output sides of the first resistor R1 and the second resistor R2 are connected to the non-inverting input terminal (-) of the first operational amplifier U1.

[0019] The first input terminal and the second input terminal are connected to the non-inverting input terminal (-) of the first operational amplifier U1 via the first resistor R1 and the second resistor R2, so that the deviation between the voltage command value Vref1 and the voltage measurement value Vreal1 is input to the non-inverting input terminal (-) of the first operational amplifier U1. The inverting input terminal (+) of the first operational amplifier U1 is grounded.

[0020] The deviation between the voltage command value Vref1 and the voltage measurement value Vreal1 is input to the non-inverting input terminal (-) of the first operational amplifier U1, so that the deviation between the voltage command value Vref1 and the voltage measurement value Vreal1 is amplified and a control value with the inverse characteristic of the deviation is output. A resistor and a capacitor are connected to the first operational amplifier U1 for phase compensation.

[0021] The current control unit 22 operates in a current control mode in which it outputs a control value so that the measured current value of the constant-voltage constant-current power supply becomes the target current value. The current control unit 22 outputs a control value adjusted to cancel out the error between the current command value Iref1 and the measured current value Ireal1.

[0022] The current control unit 22 has a third input terminal for inputting the current command value Iref1, a third resistor R3 connected to the third input terminal, a fourth input terminal for inputting the current measurement value Ireal1, a fourth resistor R4 connected to the fourth input terminal, and a second operational amplifier U2 which is an error amplifier.

[0023] For example, feedback control such as PI (Proportional-Integral) control is performed using a second operational amplifier U2, a capacitor connected in parallel to the second operational amplifier U2, and a third resistor R3 or a fourth resistor R4 connected in series to the second operational amplifier U2.

[0024] A resistor may be connected in series to the capacitor connected in parallel to the second operational amplifier U2 as shown in Figure 1. The resistor connected in series to the capacitor connected in parallel to the second operational amplifier U2 is connected to adjust the time required for turning on or off the constant-current / constant-voltage power supply.

[0025] The current command value Iref1 is the target current value of the constant-voltage constant-current power supply. The current command value Iref1 is set to any value within the performance range of the constant-voltage constant-current power supply. The current measurement value Ireal1 is the current value measured by an ammeter connected to the load 4.

[0026] The output terminals of the third resistor R3 and the fourth resistor R4 are connected to the non-inverting input terminal (-) of the second operational amplifier U2. Since the third input terminal and the fourth input terminal are connected to the non-inverting input terminal (-) of the second operational amplifier U2 via the third resistor R3 and the fourth resistor R4, the deviation between the current command value Iref1 and the measured current value Ireal1 is input to the non-inverting input terminal (-) of the second operational amplifier U2. The inverting input terminal (+) of the second operational amplifier U2 is grounded.

[0027] The deviation between the current command value Iref1 and the measured current value Ireal1 is input to the non-inverting input terminal (-) of the second operational amplifier U2, so that the deviation between the current command value Iref1 and the measured current value Ireal1 is amplified and a control value with the inverse characteristic of the deviation is output. A resistor and a capacitor are connected to the second operational amplifier U2 for phase compensation.

[0028] The selector 23 is connected to the output sides of the voltage control unit 21 and the current control unit 22, and outputs a control value in either the voltage control mode or the current control mode. The selector 23 connects the voltage control unit 21 and the current control unit 22 in parallel.

[0029] The selector 23 includes a fifth resistor R5, a first diode D1, and a second diode D2. For example, the selector 23 outputs the control value in either the voltage control mode or the current control mode so that the absolute value of the control value becomes smaller. For example, the control value is converted into a voltage and then calculated.

[0030] The input terminal of the fifth resistor R5 is connected to the output side of the first operational amplifier U1 of the voltage control unit 21. The first diode D1 and the second diode D2 are connected in parallel to the output side of the second operational amplifier U2 of the current control unit 22.

[0031] The first diode D1 is connected in the reverse direction to the output of the second operational amplifier U2, so that the cathode of the first diode D1 is connected to the output side of the second operational amplifier U2 so that it faces the output of the second operational amplifier U2.

[0032] The second diode D2 is connected in the positive direction to the output of the second operational amplifier U2, so that the cathode of the second diode D2 is connected to the output side of the second operational amplifier U2 so that it faces in the same direction as the output of the second operational amplifier U2.

[0033] Either the first diode D1 or the second diode D2 is connected to the output side of the second operational amplifier U2 by a switch. When the output of the second operational amplifier U2 is positive, the first diode D1 is connected to the output side of the second operational amplifier U2, and when the output of the second operational amplifier U2 is negative, the second diode D2 is connected to the output side of the second operational amplifier U2. The first diode D1 and the second diode D2 are connected to the output side of the current control unit 22 in the opposite direction to the output.

[0034] In the selection unit 23, a fifth resistor R5 is connected to the output side of the voltage control unit 21, and either a first diode D1 or a second diode D2 is connected to the output side of the current control unit 22.

[0035] The selection unit 23 has an output terminal connected to the output side of the fifth resistor R5 and the output sides of the first diode D1 and the second diode D2, thereby connecting the voltage control unit 21 and the current control unit 22 in parallel and operating either the voltage control unit 21 or the current control unit 22, forming a so-called diode OR connection.

[0036] In the case of diode OR connection, when a control value is output in voltage control mode by voltage control section 21, the output of second operational amplifier U2 of current control section 22 is saturated with the voltage of the circuit power supply (not shown).

[0037] The circuit power supply refers to a current source or voltage source that provides a voltage or current to the power supply circuit 1. When a control value is output in current control mode by current control unit 22, the output of first operational amplifier U1 of voltage control unit 21 is saturated with the voltage of the circuit power supply. When selection unit 23 is included, the power supply control circuit operates by switching between voltage control mode and current control mode using a circuit having a diode.

[0038] The output terminal of the selection unit 23 is connected to the power unit 3 via a tenth resistor R10. As will be described later, when the constant-voltage constant-current power supply is turned on, the power unit 3 is driven in accordance with the control value output from the output terminal of the selection unit 23, and applies to the load 4 a voltage and a current in accordance with the control value.

[0039] The power unit 3 includes, for example, a sixth resistor R6, a seventh resistor R7, a third operational amplifier U3, and a fourth operational amplifier U4. The output side of the selection unit 23 is connected to the inverting input terminal (+) of the third operational amplifier U3.

[0040] A voltage set by a sixth resistor R6 and a seventh resistor R7 is input to the non-inverting input terminal (-) of the third operational amplifier U3. The output side of the third operational amplifier U3 is connected to the non-inverting input terminal (-) of the fourth operational amplifier U4. The inverting input terminal (+) of the fourth operational amplifier U4 is grounded.

[0041] The power unit 3 generates a drive pulse by a PWM method or the like that modulates the pulse width in accordance with the control value output from the selection unit 23, and transmits the drive pulse to a driver (not shown). When the power unit 3 transmits the drive pulse to the driver, a voltage and current corresponding to the control value are applied to the load 4.

[0042] The control unit 2 may include a quenching unit to improve the performance by canceling out voltage overshoot when the constant-voltage constant-current power supply is turned on. The quenching unit has the function of reducing the potential difference between the voltage control mode and the current control mode.

[0043] Specifically, for example, the elimination unit cancels out the difference between the control value of voltage control unit 21 and the control value of current control unit 22. Even more specifically, for example, there is a set of elimination units (for example, a first potential difference elimination unit 211 and a second potential difference elimination unit, which will be described later), and each elimination unit includes a transistor that operates during positive output (for example, a first transistor Q1 or a third transistor Q3, which will be described later, etc.) and a transistor that operates during negative output (for example, a second transistor Q2 or a fourth transistor Q4, which will be described later, etc.), thereby canceling out the difference between the control value of voltage control unit 21 and the control value of current control unit 22.

[0044] Because the elimination portion reduces the potential difference between the voltage control mode and the current control mode, the power supply control circuit can reduce fluctuations in the control value, for example, when the power supply is turned on. This allows the power supply control circuit to reduce voltage overshoot that occurs when the power supply is turned on, for example.

[0045] 1, the control unit 2 has, as the eliminating units, a first potential difference eliminating unit 211 and a second potential difference eliminating unit 221. The first potential difference eliminating unit 211 and the second potential difference eliminating unit 221 are provided on the output side of the voltage control unit 21 and the current control unit 22, and are configured to cancel out the difference between the control value of the voltage control unit 21 and the control value of the current control unit 22.

[0046] The first potential difference disappearing unit 211 is provided on the output side of the voltage control unit 21. As a specific example, the first potential difference disappearing unit 211 has a first transistor Q1 and a second transistor Q2.

[0047] The first transistor Q1 is a PNP transistor. The base of the first transistor Q1 is connected between the fifth resistor R5 and the tenth resistor R10. The collector of the first transistor Q1 is connected between the first operational amplifier U1 and the fifth resistor R5.

[0048] The emitter of the first transistor Q1 is connected between the first resistor R1, the second resistor R2, and the first operational amplifier U1. The second transistor Q2 is an NPN transistor. The base, collector, and emitter of the second transistor Q2 are connected to the same terminals as those of the first transistor Q1.

[0049] The first transistor Q1 and the second transistor Q2 are connected in parallel, and one of them is connected by a switch. When the output of the first operational amplifier U1 is positive, the first transistor Q1 is connected, and when the output of the first operational amplifier U1 is negative, the second transistor Q2 is connected. The second potential difference disappearing unit 221 is provided on the output side of the current control unit 22. The configuration of the second potential difference disappearing unit 221 is the same as that of the first potential difference disappearing unit 211.

[0050] When there is a potential difference (deviation) between the voltage (control value) on the output side of the voltage control unit 21 and the voltage (control value) on the output side of the current control unit 22, a current flows between the base and emitter of the first potential difference disappearance unit 211, causing a current to flow between the collector and emitter, and increasing the input to the non-inverting input terminal (-) of the first operational amplifier U1.

[0051] As the input to the non-inverting input terminal (-) of the first operational amplifier U1 increases, the control value of the first operational amplifier U1 is adjusted in a direction that reduces the deviation between the voltage control unit 21 and the current control unit 22. The same applies to the second potential difference elimination unit 221; when there is a potential between the voltage on the output side of the voltage control unit 21 and the voltage on the output side of the current control unit 22, the control value of the second operational amplifier U2 is adjusted.

[0052] The turn-off current control unit 24 of the control unit 2 improves current undershoot when the constant-voltage constant-current power supply is turned off. The turn-off current control unit 24 operates in an auxiliary current control mode that outputs a control value so as to reduce the error between a predetermined current command value and a measured current value.

[0053] The turn-off current control unit 24 outputs a control value adjusted to cancel out the error between a predetermined OFF limit value OFFMref1 and the measured current value Ireal1. The turn-off current control unit 24 has a fifth input terminal for inputting the OFF limit value OFFMref1, an eighth resistor R8 connected to the fifth input terminal, a sixth input terminal for inputting the measured current value Ireal1, a ninth resistor R9 connected to the sixth input terminal, and a fifth operational amplifier U5 which is an error amplifier.

[0054] For example, feedback control such as PI (Proportional-Integral) control is performed using a fifth operational amplifier U5, a capacitor connected in parallel to the fifth operational amplifier U5, and a fifth resistor R5 or a sixth resistor R6 connected in series to the fifth operational amplifier U5.

[0055] A resistor may be connected in series to the capacitor connected in parallel to the fifth operational amplifier U5 as shown in Figure 1. The resistor connected in series to the capacitor connected in parallel to the fifth operational amplifier U5 is connected to adjust the time required for turning on or off the constant current / constant voltage power supply.

[0056] The OFF limit value OFFMref1 is the target current value of the constant voltage constant current power supply when it is turned off. The OFF limit value OFFMref1 is set to any value within the performance range of the constant voltage constant current power supply. The current measurement value Ireal1 is the current value measured by an ammeter connected to the load 4.

[0057] The output sides of the eighth resistor R8 and the ninth resistor R9 are connected to the non-inverting input terminal (-) of the fifth operational amplifier U5, so that the deviation between the OFF limit value OFFMref1 and the measured current value Ireal1 is input to the non-inverting input terminal (-) of the fifth operational amplifier U5. The inverting input terminal (+) of the fifth operational amplifier U5 is grounded.

[0058] The deviation between the OFF limit value OFFMref1 and the measured current value Ireal1 is input to the non-inverting input terminal (-) of the fifth operational amplifier U5, so that the deviation between the OFF limit value OFFMref1 and the measured current value Ireal1 is amplified and a control value with the inverse characteristic of the deviation is output. Note that a resistor and a capacitor are connected to the fifth operational amplifier U5 for phase compensation.

[0059] The combining unit 25 is connected to the output side of the selecting unit 23 and the turn-off current control unit 24. When the constant-voltage constant-current power supply is turned on, the combining unit 25 outputs a control value to the power unit 3 in the control mode output by the selecting unit 23.

[0060] When the constant voltage constant current power supply is turned off, the combining unit 25 outputs a control value in the auxiliary current control mode to the power unit 3. The combining unit 25 operates in the auxiliary current control mode only when the constant voltage constant current power supply is turned off.

[0061] The combining unit 25 connects in parallel the voltage control unit 21, the current control unit 22, and the turn-off current control unit 24. The combining unit 25 has a tenth resistor R10, a third diode D3, a fourth diode D4, a fifth diode D5, and a sixth diode D6.

[0062] The input terminal of the tenth resistor R10 is connected to the output side of the fifth resistor R5 (the output side of the selector 23). The fifth diode D5 and the sixth diode D6 are connected in parallel to the output side of the fifth operational amplifier U5 of the turn-off current controller 24. The fifth diode D5 is connected in the positive direction (same direction) as the output of the fifth operational amplifier U5.

[0063] The cathode of the fifth diode D5 is connected to the output side of the fifth operational amplifier U5 so that it faces in the same direction as the output of the fifth operational amplifier U5. The sixth diode D6 is connected in the opposite direction to the output of the fifth operational amplifier U5. In other words, the cathode of the sixth diode D6 is connected to the output side of the fifth operational amplifier U5 so that it faces in the opposite direction to the output of the fifth operational amplifier U5.

[0064] Either the fifth diode D5 or the sixth diode D6 is connected to the output side of the fifth operational amplifier U5 by a switch. When the output of the fifth operational amplifier U5 is positive, the fifth diode D5 is connected to the output side of the fifth operational amplifier U5, and when the output of the fifth operational amplifier U5 is negative, the sixth diode D6 is connected to the output side of the fifth operational amplifier U5. The fifth diode D5 and the sixth diode D6 are connected to the output side of the current control unit 22 in the same direction as the output.

[0065] The third diode D3 and the fourth diode D4 are connected in parallel with the fifth operational amplifier U5 of the turn-off current control section 24. The third diode D3 is connected in the positive direction to the output of the fifth operational amplifier U5.

[0066] The cathode of the third diode D3 is connected so that it faces in the same direction as the output of the fifth operational amplifier U5. The fourth diode D4 is connected so that it faces in the opposite direction to the output of the fifth operational amplifier U5. The cathode of the fourth diode D4 is connected so that it faces in the opposite direction to the output of the fifth operational amplifier U5.

[0067] Either the third diode D3 or the fourth diode D4 is connected to the output side of the fifth operational amplifier U5 by a switch. When the output of the fifth operational amplifier U5 is positive, the third diode D3 is connected to the output side of the fifth operational amplifier U5, and when the output of the fifth operational amplifier U5 is negative, the fourth diode D4 is connected to the output side of the fifth operational amplifier U5.

[0068] The third diode D3 and the fourth diode D4 are connected to the output side of the current control unit 22 in the same direction as the output. Note that the combining unit 25 does not necessarily have to include the third diode D3 and the fourth diode D4.

[0069] In the combining unit 25, a tenth resistor R10 is connected to the output side of the fifth resistor R5, and either a fifth diode D5 or a sixth diode D6 is connected to the output side of the turn-off current control unit 24.

[0070] The combiner 25 has an output terminal connected to the output side of the tenth resistor R10 and the output sides of the fifth and sixth diodes D5 and D6. That is, the combiner 25 connects the voltage control unit 21 and the current control unit 22 in parallel with the turn-off current control unit 24, and operates either the voltage control unit 21 (or the current control unit 22) or the turn-off current control unit 24.

[0071] According to the above-described synthesis unit 25, when the power supply is turned on, the power unit 3 is controlled by either the voltage at the output terminal of the current control unit 22 or the voltage at the output terminal of the voltage control unit 21, and the voltage (control value) at the output terminal of the auxiliary current control unit becomes approximately 0.

[0072] When the power supply is turned off, the voltages at the output terminals of the voltage control unit and the current control unit become almost zero, and the power unit operates in an auxiliary current control mode in which the voltage at the output terminal of the auxiliary current control unit controls the power unit. When the power supply control circuit includes the combining unit 25, the power supply control circuit operates in the auxiliary current control mode by using a circuit having a diode when the power supply is turned off.

[0073] Fig. 2 is a diagram showing the controllable range of voltage and current control. As shown in Fig. 2(A), in the voltage control mode and the current control mode, the control value can be controlled when both the voltage and the current are positive outputs or when both the voltage and the current are negative outputs.

[0074] For example, if the voltage is positive and the current flows in the negative direction when a constant current / constant voltage power supply is turned off, the current cannot be controlled and current undershoot may occur.

[0075] The turn-off current control unit 24 outputs a control value adjusted to cancel out the error between the predetermined OFF limit value OFFMref1 and the current measurement value Ireal1 when turning off, so that ranges that were uncontrollable in the voltage control mode and current control mode can be controlled.

[0076] For example, as shown in Figure 2(B), the second and fourth quadrants are also within the controllable range, so even if the voltage is positive and the current flows in the negative direction, the current can be controlled to flow in the positive direction, thereby improving current undershoot.

[0077] In the control unit 2, while the constant voltage / constant current power supply is turned on, a control value is output in either the voltage control mode or the voltage control mode by the selection unit 23. For example, the voltage control mode is a constant voltage control mode that outputs a control value so that the measured voltage becomes the target voltage value.

[0078] For example, the current control mode is a constant current control mode that outputs a control value so that the measured current becomes the target current value. Each control mode realizes the constant voltage function, which is a function of keeping the voltage constant, or the constant current function, which is a function of keeping the current constant, of the constant voltage constant current power supply. When the constant voltage constant current power supply is turned off, the control value is output in the auxiliary current control mode.

[0079] The control unit 2 can control the current to the current command value even when a negative current flows when the voltage is positive, and can therefore reduce the current undershoot that occurs when the constant-current / constant-voltage power supply is turned off.

[0080] The control unit 2 according to the present embodiment described above is an example of a control unit according to the present invention. The control unit 2 according to the present invention is not limited to the control unit 2 according to the present embodiment, and may be modified or applied to other things within the scope of the gist of each claim.

[0081] Details of voltage overshoot and current undershoot when the power supply circuit 1 according to this embodiment is used will be described with reference to Fig. 3. Fig. 3 is a diagram showing an example of a power supply circuit provided with a power supply control circuit according to a comparative example.

[0082] The power supply circuit 10 shown in FIG. 3 differs from the power supply circuit 1 in that it does not have the first potential difference disappearance section 211, the second potential difference disappearance section 221, the turn-off current control section 24, and the synthesis section 25, but is otherwise the same.

[0083] Fig. 4 shows the measurement results of voltage and current control in the comparative example and the present embodiment. Fig. 4(A) shows the control values ​​of voltage control and current control in the comparative example, which are the results measured at the first position P1 and the second position P2 in Fig. 3.

[0084] As shown in Figure 4(A), 1 ms after the start, the control value of the voltage control mode saturated at around 14 V, and the current control mode became dominant. Then, at 12 ms, the control value of the current control mode exceeded the control value of the voltage control mode (first range A1).

[0085] It can be seen that the control value in the current control mode drops sharply and saturates at around 14 V, resulting in a difference in the control value when switching between voltage control and current control.

[0086] (B) in Figure 4 shows the measured values ​​of the voltage and current applied to the load 4 when the voltage and current control of the comparative example is executed. The measurement points are the fourth position P4 and the fifth position P5 in Figure 3. As shown in (B) in Figure 4, it can be seen that the voltage overshoots at turn-on (second range A2) and the current undershoots at turn-off (third range A3).

[0087] 4C shows the control values ​​of the voltage control, current control, and negative current control according to the embodiment, which are the results measured at the first position P1, the second position P2, and the third position P3 in FIG. 1. The negative current control is the auxiliary current control mode described above.

[0088] 4C, the first potential difference disappearance part 211 and the second potential difference disappearance part 221 prevent a difference in the control value when switching between voltage control and current control (fourth range A4). Furthermore, it can be confirmed that the current value can be controlled at turn-off by the turn-off current control part 24 (fifth range A5).

[0089] FIG. 4(D) shows the measured values ​​of the voltage and current applied to the load 4 when the voltage and current control of the embodiment is performed. The measurement locations are the fourth position P4 and the fifth position P5 in FIG. 1. As shown in FIG. 4(D), it can be confirmed that the voltage overshoot is improved at turn-on (sixth range A6), and that the current undershoot is improved at turn-off, although it cannot be completely eliminated (third range A3, seventh range A7). Furthermore, it can be confirmed that control is possible even when a negative current flows when the voltage is positive output (eighth range A8).

[0090] The present invention is not limited to the above-described embodiment. For example, the auxiliary current control unit may be any circuit that assists in current control during turn-off, such as a voltage control circuit that controls voltage to assist in current control during turn-off. When the auxiliary current control unit is a voltage control circuit, the auxiliary current control unit may be a circuit in which, for example, voltage control unit 21 and current control unit 22 are interchanged.

[0091] When the auxiliary current control section is a voltage control circuit, the second and fourth quadrants are also within the controllable range, as shown in Figure 2(C). Therefore, even if the voltage is a negative output and the current flows in the positive direction, the voltage can be controlled to be a positive output, thereby improving voltage undershoot.

[0092] For example, the auxiliary current control unit may be a current control circuit and a voltage control circuit that controls both the voltage and the current to assist in current control during turn-off. For example, the feedback control by the error amplifier is not limited to PI control, and may be PID (Proportional-Integral-Differential) control or the like.

[0093] The power supply circuit 1 may include a command unit 5 that issues a command 51, such as a voltage command value Vref1, a current command value Iref1, or an OFF limit value OFFMref1, to the control unit 2. For example, the command unit 5 is configured with a circuit such as one or more FPGAs (Field-Programmable Gate Arrays).

[0094] The command unit 5 outputs the OFF limit value OFFMref1 until after the current command value Iref1 or the voltage command value Vref1 ends. For example, the command unit 5 executes the process in accordance with a processing procedure such as the command process shown in FIG.

[0095] 5 is a flowchart showing a processing procedure for command processing, which is a power supply control method. For example, the command unit 5 first starts outputting a current command value Iref1 (step S1), starts outputting a voltage command value Vref1 (step S2), and starts outputting an OFF limit value OFFMref1 (step S3).

[0096] Next, the command unit 5 stops outputting the voltage command value Vref1 (step S4), stops outputting the current command value Iref1 (step S5), and stops outputting the OFF limit value OFFMref1 (step S6).

[0097] For example, the order of steps S1, S2, and S3 may be interchanged, and the order of steps S4 and S5 may also be interchanged. [Explanation of symbols]

[0098] 1...power supply circuit, 2...control section (an example of a power supply control circuit), 3...power section, 21...voltage control section, 22...current control section, 23...selection section, 24...turn-off current control section (an example of an auxiliary current control section), 25...synthesis section, 211...first potential difference disappearance section (an example of a disappearance section), 221...second potential difference disappearance section (an example of a disappearance section).

Claims

1. A power supply control circuit that outputs a control value to a power unit of a power supply, a voltage control unit that operates in a voltage control mode and outputs the control value so that the measured voltage value of the power supply becomes a target voltage value; a current control unit that operates in a current control mode and outputs the control value so that the current measurement value of the power supply becomes a current target value; a selection unit connected to an output side of the voltage control unit and the current control unit, and outputting the control value in either the voltage control mode or the current control mode; an auxiliary current control unit that operates in an auxiliary current control mode to output the control value so as to reduce an error between a predetermined current command value and the current measurement value; a synthesis unit connected to an output side of the selection unit and the auxiliary current control unit, for outputting the control value to the power unit in the control mode output by the selection unit when the power supply is turned on, and for outputting the control value to the power unit in the auxiliary current control mode when the power supply is turned off; A power supply control circuit comprising:

2. The selection unit a resistor connected to the output side of the voltage control unit; a diode connected to the output side of the current control unit in a direction opposite to the output; an output terminal connected to the output side of the resistor and the output side of the diode; The power supply control circuit of claim 1 , comprising:

3. The synthesis unit a resistor connected to the output side of the selection unit; a diode connected to the output side of the auxiliary current control unit in the same direction as the output; an output terminal connected to the output side of the resistor and the output side of the diode; The power supply control circuit of claim 1 , comprising:

4. 4. The power supply control circuit according to claim 1, further comprising a elimination unit provided on the output side of the voltage control unit and the current control unit, which cancels out a difference between the control value of the voltage control unit and the control value of the current control unit.

5. A power supply control method for controlling the power supply control circuit according to claim 1, comprising: a first step of starting to output a current command value; a second step of starting to output a voltage command value; a third step of starting to output the OFF limit value; a fourth step of stopping the output of the voltage command value; a fifth step of stopping the output of the current command value; a sixth step of stopping the output of the OFF limit value; A power supply control method comprising:

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