JP7449802B2 - power supply - Google Patents

Description

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

A superconducting electromagnet is known as an inductive load (for example, see Patent Document 1). Superconducting electromagnets can generate strong magnetic fields when supplied with direct current from a constant current source power supply, and are used in a variety of applications.

On the other hand, since superconducting electromagnets have a very large inductance value, even a small change in current causes voltage overshoot due to induced electromotive force. In the worst case, voltage overshoot can lead to a quench phenomenon, which can lead to burning out of the superconducting electromagnet's coil. For this reason, a power supply device that supplies direct current to a superconducting electromagnet is required to have extremely stable current output with low ripple.

The power supply device includes a linear regulator section that supplies direct current to the superconducting electromagnet, and a control section that performs feedback control of the linear regulator section. The control section generates a control signal so that the current value of the direct current output from the linear regulator section approaches a predetermined target value, and outputs the generated control signal to the linear regulator section 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 section. However, when the control command value is small, such as during startup (when the current rises from zero), the linear regulator section does not operate, so the current value of the DC current does not follow the target value of the DC current. In other words, in the conventional power supply device, there is a region (dead band) in which the current value of the direct current output from the linear regulator section does not increase even if the control command value is increased (see FIG. 6).

This dead zone impairs the ability of the current value to follow the target value. When the current value begins to follow the target value when the dead band is exceeded, a steep slope (di/dt) occurs in the current value, and a voltage overshoot (L・di/dt) occurs in the superconducting electromagnet. Resulting in.

JP2016-46427A

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power supply device that can suppress voltage overshoot that occurs during startup.

In order to solve the above problems, a power supply device according to the present invention includes:
A power supply device that supplies direct current to an inductive load,
a DC source that outputs DC voltage;
a linear regulator unit that steps down the DC voltage output from the DC source and supplies the DC current to the inductive load;
Generating a control signal for bringing the current value of the DC current output from the linear regulator section closer to the target value of the DC current, outputting the control signal to the linear regulator section, and providing feedback of the linear regulator section. A control unit that performs control;
The control unit includes:
The present invention is characterized in that the control command value includes a predetermined offset value so that the control command value of the control signal is always greater than zero.

According to this configuration, the control unit includes the predetermined offset value in the control command value of the control signal, so that the control command value is larger than 0 by the offset value even at the time of startup. Thereby, the linear regulator section can be operated immediately after startup, so that the current value of the DC current can be made to follow the target value. Therefore, with this configuration, it is possible to suppress voltage overshoot occurring in the inductive load.

In the above power supply device,
The control unit includes:
a first arithmetic circuit that generates an error signal corresponding to an error between the current value and the target value;
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 regarding the offset value;
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 section;
It can be configured to have

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 section includes a plurality of transistors connected in series,
The offset value may be set to a voltage value necessary to cause a base current to flow through the transistor.

According to the present invention, it is possible to provide a power supply device that can suppress voltage overshoot at startup.

1 is a diagram showing a power supply device according to the present invention. FIG. 3 is a circuit diagram of an offset circuit and a second arithmetic circuit of the present invention. FIG. 3 is a diagram for explaining feedback control of the present invention. FIG. 7 is a waveform diagram for explaining the operation of a power supply device according to a comparative example. FIG. 3 is a waveform diagram for explaining the operation of the power supply device according to the present invention. FIG. 3 is a diagram for explaining a dead zone.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a 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 section 120, a current detection means 130, and a control section 140, and supplies a DC current I to a superconducting electromagnet 200 (corresponding to the "inductive load" of the present invention). supply

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

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

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

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

The control unit 140 generates a control signal for bringing the current value Iout of the DC 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 like this. In this 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 the error (difference) between the current value Iout of the DC current I and the target value Iref of the DC current I. In this embodiment, the first arithmetic circuit 141 is configured with an error amplifier including at least one operational amplifier. The first arithmetic circuit 141 receives a voltage signal corresponding to the current value Iout of the DC current I from the current detection means 130, and also receives the DC current I from the outside (for example, a microcomputer provided outside the power supply 100). A voltage signal corresponding to the target value Iref is input. The first arithmetic circuit 141 amplifies the voltage difference between these voltage signals and generates 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 DC current I closer to the target value Iref based on the error signal Verr. In this embodiment, the response circuit 142 is configured of a circuit including a plurality of operational amplifiers connected in multiple stages to increase the amplification factor. Note that the control command value of the first control signal Va (hereinafter referred to as "first control command value") corresponds to the control command value of the control signal in a conventional power supply device.

Offset circuit 143 is configured to generate an offset signal Vb regarding 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 this embodiment includes a series circuit made up of resistors R1 and R2, and a capacitor C1 whose one end is connected to the connection point of the resistors R1 and R2. The offset circuit 143 generates an offset voltage by dividing a predetermined voltage Vee by resistors R1 and R2, and outputs a voltage signal corresponding to the offset voltage to the second arithmetic circuit 144 as an offset signal Vb.

The voltage value (offset value) of the offset voltage is set to a voltage value necessary to cause a base current to flow through the transistors constituting the linear regulator section 120 to make the linear regulator section 120 operable. That is, when the voltage value required to cause the base current to flow 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 uses the second control signal Vi as a control signal for feedback control (the "control signal" of the present invention) to generate a linear signal. It is configured to output to the regulator section 120. As shown in FIG. 2, the second arithmetic circuit 144 of this embodiment is constituted by 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 referred to as "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 the configuration of feedback control of the power supply device 100. The feedback control configuration according to this 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 section 120, which is a hardware section.

As shown in FIG. 3, the first arithmetic circuit 141 outputs an error signal Verr generated based on a signal corresponding to the current value Iout of the DC current I and a signal corresponding to the target value Iref of the DC current I. The response circuit 142 outputs a first control signal Va generated based on the error signal Verr. The second arithmetic circuit 144 outputs a second control signal Vi obtained by adding the offset signal Vb to the first control signal Va. The linear regulator section 120 supplies the superconducting electromagnet 200 with a direct current I generated according to the second control signal Vi. The current detection means 130 detects the current value Iout of the DC 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 section 120 is set to the offset signal regardless of the magnitude of the first control command value of the first control signal Va. It is always greater than 0 by the offset value of Vb.

Next, the operation of the power supply device 100 according to the present embodiment at startup will be described in comparison with a power supply device that does not include the offset circuit 143 and the second arithmetic circuit 144 (power supply device according to a comparative example).

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

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

In the power supply device according to the comparative example, as shown in FIG. 4(D), 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 remains at the target value. Does not follow Iref. This is because until time T3, the control command value of the control signal Vi' is small (see FIG. 4(F)), so no base current flows through the transistors forming the linear regulator section 120, and the linear regulator section 120 does not operate. . As a result, in the power supply device according to the comparative example, a dead band occurs from time T2 to time T3.

At time T3, when the linear regulator section 120 starts operating, the current value Iout starts to follow the target value Iref. At time T3, the error between current value Iout and target value Iref is large, so current value Iout rapidly increases from time T3 to time T4 (see FIG. 4(D)). Therefore, an excessive overshoot of the voltage Vs occurs in the superconducting electromagnet 200 between time T3 and time T4 (see FIG. 4(E)).

On the other hand, in the power supply device 100 according to the present embodiment, as shown in FIG. 5(D), when the operation is started at time T1 and the target value Iref is increased from time T2 to time T3, the current value Iout becomes 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)). A base current flows through the transistors forming the linear regulator section 120 from then to time T3 (the linear regulator section 120 operates). As a result, in the power supply device 100, the current value Iout follows the target value Iref from time T2 to time T3, and the occurrence of a dead band can be avoided.

Further, since the generation of a dead band can be avoided, the power supply device 100 can avoid a sudden increase in the current value Iout from time T3 to time T4 (see FIG. 5(D)). Therefore, according to the power supply device 100 according to this embodiment, overshoot of the voltage Vs generated in the superconducting electromagnet 200 at the time of startup can be suppressed (see FIG. 5(E)).

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

A power supply device according to the present invention includes a DC source that outputs a DC voltage, a linear regulator unit that steps down the DC voltage and supplies a DC current to an inductive load, and a current value of the DC current output from the linear regulator unit. and a control section that generates a control signal for approaching the target value and outputs it to the linear regulator section to perform feedback control, and the control section is configured such that the control command value of the control signal is always greater than 0. As long as a predetermined offset value is included in the control command value, the configuration can be changed as appropriate.

The control unit of the present invention may include a correction circuit that corrects the target value Iref of the DC current I instead of the offset circuit 143 and the second arithmetic circuit 144. The correction circuit corrects the target value Iref by generating an offset signal and adding the generated offset signal to a 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, generates 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'. 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 sends the control signal Vi to the linear regulator section. 120.

That is, the configuration in which the control unit includes the correction circuit includes a predetermined offset value 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. This is a configuration that allows

In the power supply device according to the present invention, it is preferable that the offset value of the offset signal Vb is set to a voltage value necessary for causing a base current to flow through the transistor constituting the linear regulator section 120. It can be changed as appropriate depending on the allowable amount of overshoot of the voltage Vs. For example, if the voltage value required to cause the base current to flow through the transistor is X [V], the offset value may be set to a value within the range of X [V] ±5%.

Although the offset circuit 143 of this embodiment generates an offset voltage using a resistance voltage divider circuit as shown in FIG. 2, the means for generating the offset voltage is not limited to this. It can also be used in place of a pressure circuit.

The power supply device according to the present invention can also be applied to inductive loads other than superconducting electromagnets. That is, the power supply device according to the present invention can suppress voltage overshoot even for inductive loads other than superconducting electromagnets.

100 Power supply device 110 DC source 120 Linear regulator section 121 First regulator section 122 Second regulator section 123 Third regulator section 130 Current detection means 140 Control section 141 First arithmetic circuit 142 Response circuit 143 Offset circuit 144 Second arithmetic circuit 200 Super conduction electromagnet

Claims (3)

A power supply device that supplies direct current to an inductive load,
a DC source that outputs DC voltage;
a linear regulator unit that steps down the DC voltage output from the DC source and supplies the DC current to the inductive load;
Generating a control signal for bringing the current value of the DC current output from the linear regulator section closer to the target value of the DC current, outputting the control signal to the linear regulator section, and providing feedback of the linear regulator section. A control unit that performs control;
The control unit includes:
A power supply device characterized in that the control command value includes a predetermined offset value so that the control command value of the control signal is always greater than zero. The control unit includes:
a first arithmetic circuit that generates an error signal corresponding to an error between the current value and the target value;
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 regarding the offset value;
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 section;
The power supply device according to claim 1, comprising: The power supply device according to claim 2, wherein the second arithmetic circuit is an operational amplifier addition circuit.

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