JP2020137155A - Voltage conversion circuit, control method, and program - Google Patents

Abstract

To provide a novel voltage conversion circuit capable of achieving both low switching noise in the voltage conversion circuit and low loss in a snubber circuit.SOLUTION: The voltage conversion circuit includes: a chopper circuit including a switching element and for stepping up, stepping down, or stepping up or down an input voltage using the switching element; a snubber circuit including a switch enabling connection to the chopper circuit; a voltage detection unit for detecting a voltage at a switching node of the switching element in the chopper circuit; and a control circuit for controlling the switch based on a voltage detected by the voltage detection unit.SELECTED DRAWING: Figure 10

Description

The present invention relates to voltage conversion circuits, control methods and programs.

Switching elements are used in voltage conversion circuits such as step-up circuits, step-down circuits, and buck-boost circuits. Then, in such a voltage conversion circuit, switching noise may occur. Therefore, the voltage conversion circuit may be required to reduce the switching noise, and one of the methods for reducing the switching noise is a technique using a snubber circuit.
Patent Document 1 discloses, as a related technique, a technique of applying a snubber circuit in a booster circuit and controlling a booster switch and a snubber switch according to a fuel injection frequency in an internal combustion engine.
Patent Document 2 discloses, as a related technique, a technique relating to a snubber circuit capable of suppressing a short-circuit current in a power conversion device and having a low loss.

Japanese Unexamined Patent Publication No. 2018-053786 Japanese Unexamined Patent Publication No. 2008-206282

By the way, in many cases where a snubber circuit is applied to a voltage conversion circuit, there is a trade-off between reducing the switching noise in the voltage conversion circuit and reducing the loss of the snubber circuit, and in general, those low noises. It is difficult to realize a voltage conversion circuit having a snubber circuit that achieves both high loss and low loss. Therefore, there is a demand for a new voltage conversion circuit that can achieve both low switching noise in the voltage conversion circuit and low loss in the snubber circuit.

Each aspect of the present invention is intended to provide a voltage conversion circuit, a control method and a program capable of solving the above problems.

In order to achieve the above object, according to one aspect of the present invention, the voltage conversion circuit includes a switching element, and the input voltage is boosted, stepped down, or stepped up and down by using the switching element. , A snubber circuit including a switch that enables connection to the chopper circuit, a voltage detection unit that detects a voltage at the switching node of the switching element in the chopper circuit, and the switch based on the voltage detected by the voltage detection unit. It is provided with a control circuit for controlling the voltage.

In order to achieve the above object, according to another aspect of the present invention, the control method comprises a chopper circuit comprising a switching element and using the switching element to boost, step down, or buckle the input voltage. , A voltage conversion circuit control method including a snubber circuit including a switch and a switch that can be connected to the chopper circuit, and a voltage detection unit that detects a voltage at a switching node of the switching element in the chopper circuit. The switch is controlled based on the voltage detected by the voltage detection unit.

In order to achieve the above object, according to one aspect of the present invention, the program includes a switching element, and a chopper circuit and a switch for boosting, stepping down, or stepping up or lowering the input voltage using the switching element. A voltage detection unit in a computer of a voltage conversion circuit including a snubber circuit including a switch that can be connected to the chopper circuit and a voltage detection unit that detects a voltage at a switching node of the switching element in the chopper circuit. The switch is controlled based on the voltage detected by.

According to each aspect of the present invention, it is possible to achieve both low switching noise in the voltage conversion circuit and low loss in the snubber circuit.

It is a figure which shows the structure of the voltage conversion circuit by one Embodiment of this invention. It is a figure which shows an example of the structure of the voltage conversion circuit including the step-down chopper circuit. It is a figure which shows an example of the structure of the voltage conversion circuit including the step-up chopper circuit. It is a figure which shows an example of the structure of the voltage conversion circuit including the buck-boost chopper circuit. It is a figure which shows the processing flow of the voltage conversion circuit by one Embodiment of this invention. It is a figure which shows an example of the structure in the case where the voltage conversion circuit by one Embodiment of this invention is a step-down circuit. It is a figure which shows an example of the structure when the voltage conversion circuit by one Embodiment of this invention is a booster circuit. It is a figure which shows an example of the structure in the case where the voltage conversion circuit by one Embodiment of this invention is a buck-boost circuit. It is a figure which shows the example of the application of the voltage conversion circuit by embodiment of this invention. It is a figure which shows the voltage conversion circuit of the minimum structure by embodiment of this invention. It is a figure which shows the processing flow of the voltage conversion circuit of the minimum structure by embodiment of this invention. It is a schematic block diagram which shows the structure of the computer which concerns on at least one Embodiment.

Hereinafter, embodiments will be described in detail with reference to the drawings.
<Embodiment>
The voltage conversion circuit 1 according to an embodiment of the present invention is a circuit including a snubber circuit including a resistor, a capacitor, and a switch connected in series with the resistor and the capacitor. By providing such a snubber circuit in the voltage conversion circuit 1, the switching noise in the voltage conversion circuit 1 can be reduced by the function of the snubber circuit. Further, the voltage conversion circuit 1 directly monitors the switching node, controls the switch of the snubber circuit, and operates the snubber circuit only when necessary, thereby realizing low loss of the snubber circuit.

As shown in FIG. 1, the voltage conversion circuit 1 includes a chopper circuit 10, a capacitor 20, a snubber circuit 30, a voltage detection unit 40, and a control circuit 50.
Note that FIG. 1 shows a DC voltage source 60 that supplies a DC voltage to the voltage conversion circuit 1 and a load 70 of the voltage conversion circuit 1.

The chopper circuit 10 is a step-down circuit, a step-up circuit, or a step-up / down circuit including a switching element. The chopper circuit 10 converts the DC voltage output by the DC voltage source 60 into a desired DC voltage by switching the switching element between the ON state and the OFF state under the control of a control device (not shown). In FIG. 1, in the chopper circuit 10, the ground GND, the input IN, the output OUT, and the switching node P are shown. The switching node P is a node in which the voltage directly changes when the switching element is switched between the on state and the off state.
The capacitor 20 is an element that smoothes the voltage output by the chopper circuit 10.

The snubber circuit 30 is a circuit that reduces switching noise generated when the switching element of the chopper circuit 10 is switched between the on state and the off state. As shown in FIG. 2, the snubber circuit 30 includes an RC circuit 301 and a switch 302.

The RC circuit 301 reduces switching noise generated when the switching element of the chopper circuit 10 is switched between the on state and the off state. The RC circuit 301 includes a resistor 301a and a capacitor 301b.

The switch 302 is a switch that is turned on only when it is necessary to remove switching noise by controlling the control circuit 50 described later. As a result, the RC circuit 301 is connected to the chopper circuit only when it is necessary to remove the switching noise. For example, the switch 302 is a transistor switch such as a FET (Field effect transistor).

The order and position of the resistor 301a, the capacitor 301b, and the switch 302 connected in series in the snubber circuit 30 are arbitrary.
Further, the snubber circuit 30 is not limited to that composed of a resistor and a capacitor. For example, the snubber circuit 30 may be another snubber circuit such as a snubber circuit in which a diode is added and a resistor, a capacitor, a diode, and a switch are connected in series.

The voltage detection unit 40 detects the voltage at the switching node P of the chopper circuit 10. The voltage detection unit 40 is, for example, a voltage sensor. The voltage detected by the voltage detection unit 40 is always output to the control circuit 50.

The control circuit 50 receives the voltage detected by the voltage detection unit 40. The control circuit 50 controls to turn on the switch 302 when the voltage detected by the voltage detection unit 40 exceeds a voltage of a predetermined magnitude (an example of a predetermined voltage value).

For example, as shown in FIG. 3, the control circuit 50 includes a comparator 501 (an example of a first comparator) and a comparator 502 (an example of a second comparator). The comparator 501 is set with a voltage upper limit + Vref (an example of a predetermined voltage value) as a reference voltage. The lower limit value of the voltage −Vref (an example of a predetermined voltage value) is set in the comparator 502 as a reference voltage. Then, the comparator 501 compares the voltage detected by the voltage detection unit 40 with the reference voltage + Vref. Further, the comparator 502 compares the voltage detected by the voltage detection unit 40 with the reference voltage −Vref.
As a result, as shown in FIG. 4, the comparator 501 outputs a control signal for turning on the switch 302 to the snubber circuit 30 when the voltage detected by the voltage detection unit 40 is equal to or higher than the reference voltage + Vref. Further, as shown in FIG. 4, the comparator 502 outputs a control signal for turning on the switch 302 to the snubber circuit 30 when the voltage detected by the voltage detection unit 40 is equal to or lower than the reference voltage −Vref. Further, when the voltage detected by the voltage detection unit 40 is between the reference voltage + Vref and the reference voltage −Vref, the comparator 501 and the comparator 502 send a control signal for turning off the switch 302 to the snubber circuit 30. Output.
The comparator 501 and the comparator 502 may be window comparators.

Next, the operation of the voltage conversion circuit 1 will be described. Here, the processing flow shown in FIG. 5 will be described.
The voltage detection unit 40 detects the voltage at the switching node P of the chopper circuit 10 (step S1). The voltage detection unit 40 outputs the detected voltage to the control circuit 50.

The control circuit 50 receives the voltage detected by the voltage detection unit 40. The control circuit 50 controls the switch of the snubber circuit 30 based on the voltage detected by the voltage detection unit 40 (step S2).
Specifically, the control circuit 50 controls the switch 302 to be turned on when the voltage detected by the voltage detection unit 40 exceeds a voltage having a predetermined magnitude.

For example, in the control circuit 50, the comparator 501 compares the voltage detected by the voltage detection unit 40 with the reference voltage + Vref. Further, the comparator 502 compares the voltage detected by the voltage detection unit 40 with the reference voltage −Vref.
When the voltage detected by the voltage detection unit 40 is equal to or higher than the reference voltage + Vref, the comparator 501 outputs a control signal for turning on the switch 302 to the snubber circuit 30. Further, the comparator 502 outputs a control signal for turning on the switch 302 to the snubber circuit 30 when the voltage detected by the voltage detection unit 40 is equal to or lower than the reference voltage −Vref. When the voltage detected by the voltage detection unit 40 is between the reference voltage + Vref and the reference voltage-Vref, the comparator 501 and the comparator 502 send a control signal for turning off the switch 302 to the control terminal of the switch 302 ( For example, when the switch 302 is an FET, it outputs to the gate terminal).

The switch 302 of the snubber circuit 30 is turned on only when it is necessary to remove the switching noise under the control of the control circuit 50 (step S3). As a result, the RC circuit 301 is connected to the chopper circuit only when it is necessary to remove the switching noise.

The RC circuit 301 operates only when it is connected to the chopper circuit, and reduces switching noise generated when the switching element of the chopper circuit 10 is switched between the on state and the off state (step S4).

Next, a configuration example of the voltage conversion circuit 1 according to the type of the chopper circuit 10 is shown in FIGS. 6 to 8. In FIGS. 6 to 8, the voltage detection unit 40 and the control circuit 50 are omitted. Further, FIGS. 6 to 8 show a voltage conversion circuit 1 when the load 70 is a resistor.

When the chopper circuit 10 is a step-down chopper circuit, the chopper circuit 10 is, for example, the circuit shown in FIG.
When the chopper circuit 10 is a boost chopper circuit, the chopper circuit 10 is, for example, the circuit shown in FIG. 7.
When the chopper circuit 10 is a buck-boost chopper circuit, the chopper circuit 10 is, for example, the circuit shown in FIG.
As an application of the voltage conversion circuit 1, a power supply circuit on a motherboard (see FIG. 9), a power supply circuit for a battery-powered sensor device, and the like can be considered.

The voltage conversion circuit 1 according to the embodiment of the present invention has been described above. In the voltage conversion circuit 1, the chopper circuit 10 includes a switching element, and boosts, lowers, or raises and lowers the input voltage by using the switching element. The snubber circuit 30 includes resistors, capacitors and switches connected in series. The snubber circuit 30 can be connected to the chopper circuit 10. The voltage detection unit 40 detects the voltage at the switching node of the switching element in the chopper circuit 10. The control circuit 50 controls the switch of the snubber circuit 30 based on the voltage detected by the voltage detection unit 40.

By configuring the voltage conversion circuit 1 in this way, the snubber circuit 30 can be operated only when the ringing of switching noise in the voltage conversion circuit 1 becomes large.
As a result, for example, while the current of the load 70 is small and the ringing of switching noise is small, no loss occurs in the snubber circuit 30. That is, the voltage conversion circuit 1 can be operated with high efficiency.
Further, the snubber circuit 30 is a simple RC circuit 301 composed of a resistor 301a and a capacitor 301b. Therefore, the RC time constant for reducing the ringing of switching noise can be determined relatively easily. That is, the ringing of switching noise can be reduced by the snubber circuit 30 having a simple configuration.
Therefore, the voltage conversion circuit 1 has low loss and high efficiency, which is required in the application of batteries for IoT (Internet of Things) devices such as sensors to prolong the driving time and wireless communication of IoT devices. Both time reductions are achieved.

The voltage conversion circuit 1 having the minimum configuration according to the embodiment of the present invention will be described.
As shown in FIG. 10, the voltage conversion circuit 1 having the minimum configuration according to the embodiment of the present invention includes a chopper circuit 10, a snubber circuit 30, a voltage detection unit 40, and a control circuit 50.

The chopper circuit 10 includes a switching element, and boosts, lowers, or raises and lowers the input voltage by using the switching element.
The snubber circuit 30 includes a switch and can be connected to the chopper circuit 10.
The voltage detection unit 40 detects the voltage at the switching node of the switching element in the chopper circuit 10.
The control circuit 50 controls the switch based on the voltage detected by the voltage detection unit 40.

Next, the operation of the voltage conversion circuit 1 having the minimum configuration will be described. Here, the processing flow shown in FIG. 11 will be described.
The voltage detection unit 40 detects the voltage at the switching node of the switching element in the chopper circuit 10 (step S11). The voltage detection unit 40 outputs the detected voltage to the control circuit 50.

The control circuit 50 receives the voltage detected by the voltage detection unit 40. The control circuit 50 controls the switch of the snubber circuit 30 based on the voltage detected by the voltage detection unit 40. (Step S12).

The switch of the snubber circuit 30 is turned on only when it is necessary to remove the switching noise by the control of the control circuit 50 (step S13). As a result, the snubber circuit 30 is connected to the chopper circuit 10 only when it is necessary to remove the switching noise.

The snubber circuit 30 operates only when connected to the chopper circuit 10 and reduces switching noise generated when the switching element of the chopper circuit 10 is switched between the on state and the off state (step S14).

The voltage conversion circuit 1 having the minimum configuration of the present invention has been described above.
By configuring the voltage conversion circuit 1 in this way, it is possible to achieve both low switching noise in the voltage conversion circuit 1 and low loss in the snubber circuit 30.

In one embodiment of the present invention, the snubber circuit 30 has been described as being connected to the switching node P. However, the snubber circuit 30 according to another embodiment of the present invention may be connected to an arbitrary node in which switching noise occurs in the chopper circuit 10.

The control circuit 50 according to the embodiment of the present invention has been described as using a comparator for detecting the voltage level at the switching node P. However, the control circuit 50 according to another embodiment of the present invention includes an FPGA (Field Programmable Gate Array), and the FPGA determines whether the voltage detected by the voltage detection unit 40 is equal to or lower than the upper limit of the voltage. In addition, it may be determined whether or not the voltage detected by the voltage detection unit 40 is equal to or less than the upper limit value of the voltage.
Then, the control circuit 50 may control the switch 302 based on the determination result by the FPGA.

In the processing according to the embodiment of the present invention, the order of the processing may be changed as long as the appropriate processing is performed.

Each of the storage device and other storage devices (including registers and latches) in the embodiment of the present invention may be provided anywhere as long as appropriate information is transmitted and received. Further, each of the storage device and the other storage devices according to the embodiment of the present invention may exist in a plurality of storage devices within a range in which appropriate information is transmitted and received, and the data may be distributed and stored.

Although the embodiment of the present invention has been described, the voltage conversion circuit 1, the chopper circuit 10, the snubber circuit 30, the control circuit 50, and other control devices may have a computer system inside. The process of the above-mentioned processing is stored in a computer-readable recording medium in the form of a program, and the above-mentioned processing is performed by the computer reading and executing this program. A specific example of a computer is shown below.

FIG. 12 is a schematic block diagram showing the configuration of a computer according to at least one embodiment.
As shown in FIG. 12, the computer 5 includes a CPU 6, a main memory 7, a storage 8, and an interface 9.
For example, each of the voltage conversion circuit 1, the chopper circuit 10, the snubber circuit 30, the control circuit 50, and other control devices described above is mounted on the computer 5. The operation of each processing unit described above is stored in the storage 8 in the form of a program. The CPU 6 reads a program from the storage 8, expands it into the main memory 7, and executes the above processing according to the program. Further, the CPU 6 secures a storage area corresponding to each of the above-mentioned storage units in the main memory 7 according to the program.

Examples of the storage 8 include HDD (Hard Disk Drive), SSD (Solid State Drive), magnetic disk, magneto-optical disk, CD-ROM (Compact Disk Read Only Memory), DVD-ROM (Digital Versaille Disk Read). , Semiconductor memory and the like. The storage 8 may be internal media directly connected to the bus of computer 5, or external media connected to computer 5 via an interface 9 or a communication line. When this program is distributed to the computer 5 via a communication line, the distributed computer 5 may expand the program to the main memory 7 and execute the above processing. In at least one embodiment, the storage 8 is a non-temporary tangible storage medium.

Further, the above program may realize a part of the above-mentioned functions. Further, the program may be a file that can realize the above-mentioned functions in combination with a program already recorded in the computer system, that is, a so-called difference file (difference program).

Although some embodiments of the present invention have been described, these embodiments are examples and do not limit the scope of the invention. Various additions, omissions, replacements, and changes may be made to these embodiments without departing from the gist of the invention.

1 ... Voltage conversion circuit 5 ... Computer 6 ... CPU
7 ... Main memory 8 ... Storage 9 ... Interface 10 ... Chopper circuit 20, 301b ... Capacitor 30 ... Snubber circuit 40 ... Voltage detector 50 ... Control circuit 60 ...・ ・ DC voltage source 70 ・ ・ ・ Load 301 ・ ・ ・ RC circuit 301a ・ ・ ・ Resistance 302 ・ ・ ・ Switch 501, 502 ・ ・ ・ Comparator

In order to achieve the above object, according to one aspect of the present invention, the voltage conversion circuit includes a switching element, and the input voltage is boosted, stepped down, or stepped up / down by using the switching element. , A snubber circuit including a switch that enables connection to the chopper circuit, a voltage detection unit that detects a voltage at the switching node of the switching element in the chopper circuit, a voltage detected by the voltage detection unit, and an upper limit of the voltage. A control circuit having a first comparator for comparing values and a second comparator for comparing the voltage detected by the voltage detection unit with the lower limit of the voltage, and the comparison result of the first comparator and the second A control circuit for controlling the switch based on the comparison result of the comparator is provided .

In order to achieve the above object, according to another aspect of the present invention, the control method comprises a chopper circuit comprising a switching element and using the switching element to boost, step down, or step up and down the input voltage. , A snubber circuit including a switch and a switch that can be connected to the chopper circuit, a voltage detection unit that detects a voltage at the switching node of the switching element in the chopper circuit, and a voltage detected by the voltage detection unit. A method for controlling a voltage conversion circuit, comprising a first comparator for comparing the upper limit of the voltage and a control circuit having a second comparator for comparing the voltage detected by the voltage detection unit with the lower limit of the voltage. Therefore, the switch is controlled based on the comparison result of the first comparator and the comparison result of the second comparator .

In order to achieve the above object, according to one aspect of the present invention, the program comprises a switching element, and a chopper circuit and a switch for boosting, stepping down, or raising and lowering an input voltage using the switching element. A snubber circuit including a switch that enables connection to the chopper circuit, a voltage detection unit that detects a voltage at the switching node of the switching element in the chopper circuit, a voltage detected by the voltage detection unit, and a voltage. To a computer of a voltage conversion circuit including a first comparator for comparing the upper limit value of the voltage and a control circuit having a second comparator for comparing the voltage detected by the voltage detection unit and the lower limit value of the voltage. The switch is controlled based on the comparison result of the first comparator and the comparison result of the second comparator .

Claims (6)

A chopper circuit provided with a switching element and boosting, stepping down, or stepping up or lowering an input voltage using the switching element.
A snubber circuit with a switch that can be connected to the chopper circuit,
A voltage detector that detects the voltage at the switching node of the switching element in the chopper circuit, and
A control circuit that controls the switch based on the voltage detected by the voltage detector,
A voltage conversion circuit equipped with. The control circuit
When the voltage detected by the voltage detection unit exceeds a predetermined voltage value, the switch is controlled to be turned on.
The voltage conversion circuit according to claim 1. The control circuit
A first comparator that compares the voltage detected by the voltage detector with the upper limit of the voltage.
A second comparator that compares the voltage detected by the voltage detector with the lower limit of the voltage.
With
The switch is controlled based on the comparison result of the first comparator and the comparison result of the second comparator.
The voltage conversion circuit according to claim 1 or 2. The control circuit
FPGA, which determines whether the voltage detected by the voltage detection unit is equal to or less than the upper limit value of the voltage, and determines whether the voltage detected by the voltage detection unit is equal to or less than the upper limit value of the voltage.
With
The switch is controlled based on the determination result by the FPGA.
The voltage conversion circuit according to claim 1 or 2. A chopper circuit having a switching element and stepping up, stepping down, or stepping up or lowering an input voltage using the switching element, a snubber circuit having a switch and a switch capable of connecting to the chopper circuit, and the chopper. A control method for a voltage conversion circuit including a voltage detection unit for detecting a voltage at a switching node of the switching element in the circuit.
The switch is controlled based on the voltage detected by the voltage detector.
Control method. A chopper circuit having a switching element and stepping up, stepping down, or stepping up or lowering an input voltage using the switching element, a snubber circuit having a switch and a switch capable of connecting to the chopper circuit, and the chopper. A computer of a voltage conversion circuit including a voltage detection unit for detecting a voltage at a switching node of the switching element in the circuit.
The switch is controlled based on the voltage detected by the voltage detection unit.
program.

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