JP6733922B1 - Voltage conversion circuit, control method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new voltage conversion circuit capable of achieving both low switching noise in a voltage conversion circuit and low loss in a snubber circuit. A voltage conversion circuit includes a switching element, and includes a chopper circuit that steps up, steps down, or steps up or down an input voltage using the switching element, and a switch, and enables connection to the chopper circuit. A snubber circuit including a switch; a voltage detection unit that detects a voltage at a 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 detection unit. .. [Selection diagram] Figure 10

Description

The present invention relates to a voltage conversion circuit, a control method and a program.

A switching element is used in a voltage conversion circuit such as a step-up circuit, a step-down circuit, and a step-up/down circuit. 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 as one of the methods for reducing the switching noise, there 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 the booster switch and the snubber switch according to the frequency of fuel injection in an internal combustion engine.
Patent Document 2 discloses, as a related technique, a technique related to a snubber circuit which can suppress a short-circuit current in a power conversion device and has a low loss.

JP, 2008-053786, A JP, 2008-206282, A

By the way, in many cases where a snubber circuit is applied to a voltage conversion circuit, there is a trade-off relationship between the reduction of switching noise in the voltage conversion circuit and the reduction of loss of the snubber circuit. It is difficult to realize a voltage conversion circuit including a snubber circuit that achieves both low cost 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.

It is an object of each aspect of the present invention to provide a voltage conversion circuit, a control method, and a program that can solve the above problems.

To achieve the above object, according to one aspect of the present invention, a voltage conversion circuit includes a switching element, and a chopper circuit that steps up, steps down, or steps up an input voltage using the switching element. A snubber circuit including a switch that can be connected to the chopper circuit, a voltage detection unit that detects a voltage at a 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 a value and a second comparator for comparing a voltage detected by the voltage detecting unit with a lower limit value of the voltage, the comparison result of the first comparator and the second comparator. A control circuit for controlling the switch based on the comparison result of the comparator .

In order to achieve the above object, according to another aspect of the present invention, a control method includes a switching element, and a chopper circuit that steps up, steps down, or steps up an input voltage by using the switching element. A snubber circuit that includes a switch and that is connectable to the chopper circuit, a voltage detection unit that detects a voltage at a switching node of the switching element in the chopper circuit, and a voltage detected by the voltage detection unit. A control circuit having a first comparator that compares an upper limit value of the voltage and a voltage detected by the voltage detection unit with a second comparator that compares the lower limit value 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, a program includes a switching element, and a chopper circuit that steps up, steps down, or steps up an input voltage by using the switching element, and a switch. A snubber circuit including a switch that enables connection to the chopper circuit, a voltage detection unit that detects a voltage at a switching node of the switching element in the chopper circuit, a voltage detected by the voltage detection unit, and a voltage. The voltage detected by the voltage detector and a control circuit having a second comparator that compares the lower limit value of the voltage to the computer of the voltage conversion circuit. The switch is controlled based on the comparison result of one comparator and the comparison result of the second comparator .

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 a structure of the voltage conversion circuit provided with a step-down chopper circuit. It is a figure which shows an example of a structure of the voltage conversion circuit provided with a boost chopper circuit. It is a figure which shows an example of a structure of the voltage conversion circuit provided with a buck-boost chopper circuit. It is a figure which shows the processing flow of the voltage conversion circuit by one Embodiment of this invention. FIG. 6 is a diagram showing an example of a configuration in which the voltage conversion circuit according to the embodiment of the present invention is a step-down circuit. It is a figure which shows an example of a 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 a structure when the voltage conversion circuit by one Embodiment of this invention is a buck-boost circuit. FIG. 6 is a diagram showing an example of an application of the voltage conversion circuit according to the embodiment of the present 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 1 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 including such a snubber circuit, the voltage conversion circuit 1 realizes the reduction of switching noise in the voltage conversion circuit 1 by the function of the snubber circuit. Further, the voltage conversion circuit 1 realizes a low loss of the snubber circuit by directly monitoring the switching node, controlling the switches of the snubber circuit, and operating the snubber circuit only when necessary.

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/step-down circuit including a switching element. The chopper circuit 10 converts the DC voltage output from the DC voltage source 60 into a desired DC voltage by switching the switching element between an ON state and an 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 switches between an on state and an 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 switches between an on state and an 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 switches between an on state and an 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 under the control of the control circuit 50 described later. Thereby, 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).

Note that the resistor 301a, the capacitor 301b, and the switch 302 connected in series in the snubber circuit 30 may be in any order or position.
Further, the snubber circuit 30 is not limited to the one configured by the resistor and the capacitor. For example, the snubber circuit 30 may be another snubber circuit such as a snubber circuit in which a diode is further added and resistors, capacitors, diodes, and switches are connected in series.

The voltage detector 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 detector 40 is constantly output to the control circuit 50.

The control circuit 50 receives the voltage detected by the voltage detection unit 40. The control circuit 50 performs control 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, the control circuit 50 includes a comparator 501 (an example of a first comparator) and a comparator 502 (an example of a second comparator), as shown in FIG. In the comparator 501, the upper limit value of voltage+Vref (an example of a predetermined voltage value) is set as a reference voltage. A lower limit value of 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 becomes 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 comparators 501 and 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 switches of the snubber circuit 30 based on the voltage detected by the voltage detection unit 40 (step S2).
Specifically, the control circuit 50 performs control to turn on the switch 302 when the voltage detected by the voltage detection unit 40 exceeds a voltage of 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, when the voltage detected by the voltage detection unit 40 becomes equal to or lower than the reference voltage −Vref, 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 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 a FET, it outputs to the gate terminal).

Under the control of the control circuit 50, the switch 302 of the snubber circuit 30 is turned on only when it is necessary to remove switching noise (step S3). Thereby, 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 connected to the chopper circuit, and reduces switching noise generated when the switching element of the chopper circuit 10 switches between the on state and the off state (step S4).

Next, FIGS. 6 to 8 show configuration examples of the voltage conversion circuit 1 according to the type of the chopper circuit 10. 6 to 8, the voltage detector 40 and the control circuit 50 are omitted. Further, FIGS. 6 to 8 show the voltage conversion circuit 1 in the case where 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.
Note that the voltage conversion circuit 1 may be applied to a power supply circuit on a motherboard (see FIG. 9), a power supply circuit for a battery-powered sensor device, and the like.

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 the input voltage is stepped up, stepped down, or stepped up or down by using the switching element. The snubber circuit 30 includes a resistor, a capacitor, and a switch that are 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 switches 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, no loss occurs in the snubber circuit 30 while the current of the load 70 is small and the ringing of the switching noise is small. That is, the voltage conversion circuit 1 can be operated with high efficiency.
The snubber circuit 30 is a simple RC circuit 301 including 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 the switching noise can be reduced by the snubber circuit 30 having a simple structure.
Therefore, since the voltage conversion circuit 1 has low loss and high efficiency, the drive time is extended and the wireless communication of the IoT device is required in the application of the battery for the IoT (Internet of Things) device such as the sensor. Both low noise of time is achieved.

The minimum voltage conversion circuit 1 according to the embodiment of the present invention will be described.
The minimum configuration voltage conversion circuit 1 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, as shown in FIG.

The chopper circuit 10 includes a switching element, and boosts, steps down, or steps up or down the input voltage using the switching element.
The snubber circuit 30 includes a switch and can be connected to the chopper circuit 10.
The voltage detector 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 switches of the snubber circuit 30 based on the voltage detected by the voltage detection unit 40. (Step S12).

Under the control of the control circuit 50, the switch of the snubber circuit 30 is turned on only when it is necessary to remove switching noise (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 it is connected to the chopper circuit 10, and reduces switching noise generated when the switching element of the chopper circuit 10 switches between an on state and an off state (step S14).

The minimum voltage conversion circuit 1 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 the embodiment of the present invention, the snubber circuit 30 is connected to the switching node P. However, the snubber circuit 30 according to another embodiment of the present invention may be connected to any node in the chopper circuit 10 where switching noise occurs.

The control circuit 50 according to the embodiment of the present invention has been described as using the 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 value of the voltage. Moreover, it may be determined whether or not the voltage detected by the voltage detection unit 40 is equal to or lower 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.

Note that the order of the processes in the embodiments of the present invention may be changed within a range in which appropriate processes are performed.

Each of the storage device and the other storage device (including a register and a latch) according to the embodiment of the present invention may be provided anywhere within a range in which appropriate information is transmitted and received. Further, each of the storage device and the other storage device according to the embodiment of the present invention may exist in plural in a range where appropriate information is transmitted and received, and may store data in a distributed manner.

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 described above may have a computer system therein. The above-described process steps are stored in a computer-readable recording medium in the form of a program, and the above process is performed by the computer reading and executing the program. A specific example of the 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 the program from the storage 8 and expands it in the main memory 7, and executes the above processing according to the program. Further, the CPU 6 reserves 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 a HDD (Hard Disk Drive), an SSD (Solid State Drive), a magnetic disk, a magneto-optical disk, a CD-ROM (Compact Disc Read Only Memory), and a DVD-ROM (Digital Versatile Disc Memory). , Semiconductor memory, and the like. The storage 8 may be an internal medium directly connected to the bus of the computer 5, or may be an external medium connected to the computer 5 via the interface 9 or a communication line. When this program is distributed to the computer 5 via a communication line, the computer 5 that has received the distribution may expand the program in the main memory 7 and execute the above processing. In at least one embodiment, storage 8 is a non-transitory, tangible storage medium.

Further, the program may realize a part of the functions described above. Further, the above program may be a file that can realize the above-mentioned function in combination with a program already recorded in the computer system, that is, a so-called differential file (differential 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 spirit 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... Resistor 302... Switches 501, 502... Comparator

Claims (4)

A chopper circuit that includes a switching element, and that boosts, steps down, or boosts or lowers the 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 a switching node of the switching element in the chopper circuit,
The control circuit having a voltage detected by the voltage detecting unit, and the voltage detected by the first comparator and the voltage detecting section for comparing the upper limit value of the voltage, a second comparator for comparing the lower limit value of the voltage And a control circuit for controlling the switch based on the comparison result of the first comparator and the comparison result of the second comparator ,
Voltage conversion circuit including. The control circuit is
When the voltage detected by the voltage detection unit exceeds a predetermined voltage value, control is performed to turn on the switch.
The voltage conversion circuit according to claim 1. A snubber circuit comprising a switching element, a chopper circuit for stepping up, stepping down, or stepping up or down an input voltage using the switching element; A voltage detector that detects a voltage at a switching node of the switching element in the circuit, a first comparator that compares a voltage detected by the voltage detector with an upper limit value of the voltage, and a voltage detected by the voltage detector. And a control circuit having a second comparator for comparing the lower limit value of the voltage, and a method for controlling the voltage conversion circuit,
Controlling the switch based on a comparison result of the first comparator and a comparison result of the second comparator ;
Control method. A snubber circuit comprising a switching element, a chopper circuit for boosting, stepping down, or stepping up or down an input voltage using the switching element; A voltage detection unit that detects a voltage at a switching node of the switching element in a circuit, a first comparator that compares a voltage detected by the voltage detection unit, and an upper limit value of the voltage, and a voltage detected by the voltage detection unit. And a control circuit having a second comparator for comparing the lower limit value of the voltage, to a computer of the voltage conversion circuit,
Controlling the switch based on a comparison result of the first comparator and a comparison result of the second comparator ;
program.

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