JP2022021066A - Power supply device - Google Patents

Abstract

To provide a power supply device that is able to suppress voltage overshoot at startup.SOLUTION: A power supply device 100 that supplies a DC current I to an inductive load 200, includes: a DC source 110 that outputs a DC voltage; a linear regulator unit 120 that steps down the DC voltage output from the DC source 110 and supplies the DC current I to the inductive load 200; and a control unit 140 that generates a control signal Vi for bringing an electrical current value Iout of the DC current I output from the linear regulator 120 closer to a target value Iref and outputs the control signal to the linear regulator unit 120 to execute feedback control for the linear regulator unit 120; wherein the control unit 140 causes a control command value to include a predetermined offset value so that a control command value of the control signal Vi is always larger than 0.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power supply that supplies a direct current to an inductive load.

As an inductive load, a superconducting electromagnet is known (see, for example, Patent Document 1). Superconducting electromagnets can generate a strong magnetic field when a direct current is supplied by a power supply device of a constant current source, and are used in various applications.

On the other hand, since superconducting electromagnets have a very large inductance value, voltage overshoot due to induced electromotive force occurs even with a small change in current. In the worst case, voltage overshoot causes a quench phenomenon, which leads to burning of the coil of the superconducting electromagnet. Therefore, a power supply device that supplies a direct current to a superconducting electromagnet is required to have a very stable and low ripple current output.

The power supply device includes a linear regulator unit that supplies a direct current to the superconducting electromagnet and a control unit that performs feedback control of the linear regulator unit. The control unit generates a control signal so that the current value of the direct current output from the linear regulator unit approaches a predetermined target value, and outputs the generated control signal to the linear regulator unit to perform feedback control.

The control command value of the control signal has a correlation with the current value of the direct current output from the linear regulator unit. However, when the control command value is small, such as at startup (when the current rises from zero), the linear regulator unit does not operate, so that the current value of the DC current does not follow the target value of the DC current. In other words, the conventional power supply device has a region (dead band) in which the current value of the DC current output from the linear regulator unit does not increase even if the control command value is increased (see FIG. 6).

Due to this dead band, the followability of the current value with respect to the target value is impaired. Then, when the current value starts to follow the target value when the dead band is exceeded, a steep gradient (di / dt) is generated in the current value, and a voltage overshoot (L · di / dt) is generated in the superconducting electromagnet. Resulting in.

Japanese Unexamined Patent Publication No. 2016-46427

The present invention has been made in view of the above circumstances, and an object thereof is to provide a power supply device capable of suppressing overshoot of a voltage generated at startup.

In order to solve the above problems, the power supply device according to the present invention is
A power supply that supplies direct current to an inductive load.
A DC source that outputs a DC voltage and
A linear regulator unit that steps down the DC voltage output from the DC source and supplies the DC current to the inductive load.
A control signal for bringing the current value of the DC current output from the linear regulator unit closer to the target value of the DC current is generated, the control signal is output to the linear regulator unit, and feedback from the linear regulator unit is performed. It is equipped with a control unit that performs control.
The control unit
It is characterized in that a predetermined offset value is included in the control command value so that the control command value of the control signal is always larger than 0.

According to this configuration, since the control unit includes a predetermined offset value in the control command value of the control signal, the control command value becomes larger than 0 by the offset value even at the time of activation. As a result, the linear regulator unit can be operated immediately after the start-up, so that the current value of the direct current can be made to follow the target value. Therefore, according to this configuration, overshoot of the voltage generated in the inductive load can be suppressed.

In the above power supply device
The control unit
A first arithmetic circuit that generates an error signal corresponding to the error between the current value and the target value, and
A response circuit that generates a first control signal for bringing the current value closer to the target value based on the error signal.
An offset circuit that generates an offset signal related to the offset value, and an offset circuit.
A second arithmetic circuit that generates a second control signal by adding the offset signal to the first control signal and outputs the second control signal as the control signal to the linear regulator unit.
Can be configured to include.

In the above power supply device
The second arithmetic circuit may be an operational amplifier addition circuit.

In the above power supply device
The linear regulator unit includes a plurality of transistors connected in series.
The offset value may be set to a voltage value required for passing a base current through the transistor.

According to the present invention, it is possible to provide a power supply device capable of suppressing voltage overshoot at startup.

It is a figure which shows the power supply device which concerns on this invention. It is a circuit diagram of the offset circuit and the second arithmetic circuit of this invention. It is a figure for demonstrating the feedback control of this invention. It is a waveform diagram for demonstrating the operation of the power supply device which concerns on a comparative example. It is a waveform diagram for demonstrating the operation of the power supply apparatus which concerns on this invention. It is a figure for demonstrating a dead band.

Hereinafter, embodiments of the power supply device according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a power supply device 100 according to an embodiment of the present invention. The power supply device 100 includes a DC source 110, a linear regulator unit 120, a current detecting means 130, and a control unit 140, and supplies a direct current I to the superconducting electromagnet 200 (corresponding to the "inductive load" of the present invention). Supply.

The DC source 110 is configured to output a DC voltage. The DC source 110 preferably has ripples generated in the output DC voltage on the order of ppm or less. In this embodiment, the DC source 110 includes a DC / DC converter.

The linear regulator unit 120 is configured to step down the DC voltage output from the DC source 110 and supply the DC current I to the superconducting electromagnet 200. In the present embodiment, the linear regulator unit 120 includes a first regulator unit 121, a second regulator unit 122, a third regulator unit 123, and a plurality of resistors.

The first regulator unit 121 and the second regulator unit 122 are each composed of one transistor. The third regulator unit 123 is composed of a plurality of (for example, 200) transistors connected in parallel in order to supply a large current DC current I to the superconducting electromagnet 200. The first regulator unit 121, the second regulator unit 122, and the third regulator unit 123 are connected in series in multiple stages in order to increase the current amplification factor.

The current detecting means 130 is provided on a power line connecting the linear regulator unit 120 and the superconducting electromagnet 200. The current detecting means 130 detects the current value Iout of the DC current I output from the linear regulator unit 120 and supplied to the superconducting electric magnet 200, and controls a signal (for example, a voltage signal) corresponding to the detected current value Iout. Output to unit 140. In this embodiment, the current detecting means 130 includes a current transformer.

The control unit 140 generates a control signal for bringing the current value Iout of the direct current I closer to a predetermined target value Iref, outputs the control signal to the linear regulator unit 120, and performs feedback control of the linear regulator unit 120. It is configured as follows. In the present embodiment, the control unit 140 includes a first arithmetic circuit 141, a response circuit 142, an offset circuit 143, and a second arithmetic circuit 144.

The first arithmetic circuit 141 is configured to generate an error signal Verr corresponding to an error (difference) between the current value Iout of the direct current I and the target value Iref of the direct current I. In this embodiment, the first arithmetic circuit 141 is composed of an error amplifier including at least one operational amplifier. A voltage signal corresponding to the current value Iout of the DC current I is input from the current detecting means 130 to the first arithmetic circuit 141, and the DC current I is input from the outside (for example, a microcomputer provided outside the power supply device 100). The voltage signal corresponding to the target value Iref of is input. The first arithmetic circuit 141 amplifies the voltage difference between these voltage signals to generate an error signal Verr.

The response circuit 142 is configured to generate a first control signal Va for bringing the current value Iout of the direct current I closer to the target value Iref based on the error signal Verr. In the present embodiment, the response circuit 142 is composed of a circuit including a plurality of operational amplifiers connected in multiple stages in order to increase the amplification factor. The control command value of the first control signal Va (hereinafter, “first control command value”) corresponds to the control command value of the control signal in the conventional power supply device.

The offset circuit 143 is configured to generate an offset signal Vb with respect to the offset value. The offset signal Vb is added to the first control signal Va in the second arithmetic circuit 144. As shown in FIG. 2, the offset circuit 143 of the present embodiment includes a series circuit including resistors R1 and R2, and a capacitor C1 having one end connected to a connection point of resistors R1 and R2. The offset circuit 143 generates an offset voltage obtained by dividing a predetermined voltage Vee by the resistors R1 and R2, and outputs a voltage signal corresponding to the offset voltage as an offset signal Vb to the second calculation circuit 144.

The voltage value (offset value) of the offset voltage is set to a voltage value necessary for passing a base current through the transistors constituting the linear regulator unit 120 to make the linear regulator unit 120 operable. That is, when the voltage value required to pass the base current through the transistor is X (for example, X = 1.0) [V], it is preferable to set the offset voltage to X [V].

The second arithmetic circuit 144 generates a second control signal Vi by adding an offset signal Vb to the first control signal Va, and linearly uses the second control signal Vi as a feedback control control signal (“control signal” of the present invention). It is configured to output to the regulator unit 120. As shown in FIG. 2, the second arithmetic circuit 144 of the present embodiment is composed of an operational amplifier addition circuit including an operational amplifier OP1 and resistors R3 to R6. The control command value of the second control signal Vi (hereinafter, “second control command value”) is a value obtained by adding the offset value of the offset signal Vb to the first control command value of the first control signal Va.

FIG. 3 shows a configuration of feedback control of the power supply device 100. The feedback control configuration according to the present embodiment is characterized in that the offset signal Vb is added to the first control signal Va before the first control signal Va is input to the linear regulator unit 120 which is the hardware unit.

As shown in FIG. 3, the first arithmetic circuit 141 outputs an error signal Verr generated based on the signal corresponding to the current value Iout of the direct current I and the signal corresponding to the target value Iref of the direct current I. The response circuit 142 outputs the first control signal Va generated based on the error signal Verr. The second arithmetic circuit 144 outputs the second control signal Vi, which is the sum of the first control signal Va and the offset signal Vb. The linear regulator unit 120 supplies the DC current I generated in response to the second control signal Vi to the superconducting electromagnet 200. The current detecting means 130 detects the current value Iout of the direct current I and outputs a signal (detection signal) corresponding to the current value Iout to the first arithmetic circuit 141.

With such a feedback control configuration, the second control command value of the second control signal Vi input to the linear regulator unit 120 is an offset signal regardless of the magnitude of the first control command value of the first control signal Va. It is always larger than 0 by the amount of the offset value of Vb.

Subsequently, the operation at the time of starting the power supply device 100 according to the present embodiment will be described while comparing with the power supply device (power supply device according to the comparative example) that does not include the offset circuit 143 and the second arithmetic circuit 144.

4A and 4B are waveform diagrams at the time of starting the power supply device according to the comparative example, FIG. 4A is a waveform diagram of the current value Iout and the target value Iref of the DC current I, and FIG. 4B is a waveform diagram of the voltage generated by the superconducting electric magnet 200. The waveform diagram of Vs, (C) is the waveform diagram of the feedback control control signal Vi'(= first control signal Va), (D) is the enlarged waveform diagram in the frame D of (A), and (E) is (B). ) Is an enlarged waveform diagram in the frame E, and (F) is an enlarged waveform diagram in the frame F of (C).

On the other hand, FIG. 5 is a waveform diagram at the time of starting of the power supply device 100 according to the present embodiment, (A) is a waveform diagram of the current value Iout and the target value Iref of the DC current I, and (B) is a superconducting electric magnet. The waveform diagram of the voltage Vs generated at 200, (C) is the waveform diagram of the second control signal Vi (= first control signal Va + offset signal Vb) of the feedback control, and (D) is the enlarged waveform in the frame D of (A). The figure, (E) is an enlarged waveform diagram in the frame E of (B), and (F) is an enlarged waveform diagram in the frame F of (C).

In the power supply device according to the comparative example, as shown in FIG. 4D, even if the operation is started at time T1 and the target value Iref is increased from time T2 to time T3, the current value Iout does not increase and the target value is increased. Does not follow Iref. This is because the control command value of the control signal Vi'is small until time T3 (see FIG. 4F), so that the base current does not flow through the transistors constituting the linear regulator unit 120 and the linear regulator unit 120 does not operate. .. As a result, in the power supply device according to the comparative example, a dead band is generated from the time T2 to the time T3.

At time T3, when the linear regulator unit 120 starts to operate, the current value Iout starts to follow the target value Iref. Since the error between the current value Iout and the target value Iref is large at the time point T3, the current value Iout rises sharply from the time T3 to the time T4 (see FIG. 4D). Therefore, an excessive overshoot of the voltage Vs occurs in the superconducting electromagnet 200 between the time T3 and the time T4 (see FIG. 4E).

On the other hand, in the power supply device 100 according to the present embodiment, as shown in FIG. 5D, when the operation is started at the time T1 and the target value Iref is increased from the time T2 to the time T3, the current value Iout becomes the target value. Follow Iref. In the power supply device 100, even if the first control command value of the first control signal Va is small, the offset value X of the offset signal Vb is added to the first control command value (see FIG. 5 (F)), so that the time T2 From to time T3, a base current flows through the transistors constituting the linear regulator unit 120 (the linear regulator unit 120 operates). As a result, in the power supply device 100, the current value Iout follows the target value Iref from the time T2 to the time T3, and it is possible to avoid the generation of a dead band.

Further, since it is possible to avoid the occurrence of a dead band, the power supply device 100 can avoid a sudden increase in the current value Iout from the time T3 to the time T4 (see FIG. 5 (D)). Therefore, according to the power supply device 100 according to the present embodiment, it is possible to suppress the overshoot of the voltage Vs generated in the superconducting electromagnet 200 at the time of starting (see FIG. 5E).

Although the embodiment of the power supply device according to the present invention has been described above, the present invention is not limited to the above embodiment.

The power supply device according to the present invention has a DC source that outputs a DC voltage, a linear regulator unit that steps down the DC voltage to supply a DC current to an inductive load, and a DC current value output from the linear regulator unit. It is equipped with a control unit that generates a control signal to bring it closer to the target value and outputs it to the linear regulator unit for feedback control. If the control command value includes a predetermined offset value, the configuration can be changed as appropriate.

The control unit of the present invention may include a correction circuit for correcting the target value Iref of the direct current I, instead of the offset circuit 143 and the second calculation circuit 144. The correction circuit corrects the target value Iref by generating an offset signal and adding the generated offset signal to the signal corresponding to the target value Iref. The correction circuit outputs a signal corresponding to the corrected target value Iref'to the first calculation circuit 141.

The first arithmetic circuit 141 to which the signal corresponding to the corrected target value Iref'is input has an error signal Verr' corresponding to the error (difference) between the current value Iout of the DC current I and the corrected target value Iref'. To generate. The response circuit 142 generates a control signal Vi (first control signal Va') for bringing the current value Iout closer to the corrected target value Iref' based on the error signal Verr', and the control signal Vi is a linear regulator unit. Output to 120.

That is, in a configuration in which the control unit includes a correction circuit, a predetermined offset value is included in the control command value of the control signal Vi (first control signal Va') by adding the offset signal to the signal corresponding to the target value Iref. It is a configuration that allows.

In the power supply device according to the present invention, the offset value of the offset signal Vb is preferably set to a voltage value required for passing a base current through the transistor constituting the linear regulator unit 120, but it is generated in the superconducting electromagnet 200. It can be appropriately changed according to the allowable amount of overshoot of the voltage Vs to be applied. For example, when the voltage value required to pass the base current through the transistor is X [V], the offset value may be set to a value within the range of X [V] ± 5%.

The offset circuit 143 of the present embodiment generates an offset voltage by a resistance voltage divider circuit as shown in FIG. 2, but the means for generating the offset voltage is not limited to this, and a commercially available voltage reference IC is used as a resistance component. It can also be used in place of the voltage circuit.

The power supply device according to the present invention can also be applied to an inductive load other than a superconducting electromagnet. That is, the power supply device according to the present invention can suppress voltage overshoot even with respect to an inductive load other than the superconducting electromagnet.

100 Power supply 110 DC source 120 Linear regulator unit 121 First regulator unit 122 Second regulator unit 123 Third regulator unit 130 Current detection means 140 Control unit 141 First arithmetic circuit 142 Response circuit 143 Offset circuit 144 Second arithmetic circuit 200 Super Conductive electric magnet

Claims (4)

A power supply that supplies direct current to an inductive load.
A DC source that outputs a DC voltage and
A linear regulator unit that steps down the DC voltage output from the DC source and supplies the DC current to the inductive load.
A control signal for bringing the current value of the DC current output from the linear regulator unit closer to the target value of the DC current is generated, the control signal is output to the linear regulator unit, and feedback from the linear regulator unit is performed. It is equipped with a control unit that performs control.
The control unit
A power supply device characterized in that a predetermined offset value is included in the control command value so that the control command value of the control signal is always larger than 0. The control unit
A first arithmetic circuit that generates an error signal corresponding to the error between the current value and the target value, and
A response circuit that generates a first control signal for bringing the current value closer to the target value based on the error signal.
An offset circuit that generates an offset signal related to the offset value, and an offset circuit.
A second arithmetic circuit that generates a second control signal by adding the offset signal to the first control signal and outputs the second control signal as the control signal to the linear regulator unit.
The power supply device according to claim 1, further comprising. The power supply device according to claim 2, wherein the second arithmetic circuit is an operational amplifier adder circuit. The linear regulator unit includes a plurality of transistors connected in series.
The power supply device according to any one of claims 1 to 3, wherein the offset value is set to a voltage value required for passing a base current through the transistor.

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