KR101847964B1 - Apparatus and method for controlling dc-dc converter - Google Patents

Abstract

An apparatus for controlling a DC-DC converter is disclosed. The apparatus according to the present invention includes the DC-DC converter which converts an input voltage into a predetermined output voltage and outputs the output voltage, a load terminal which is connected to an output terminal of the DC-DC converter and receives the output voltage of the DC-DC converter, an error amplifier which senses and amplifies a voltage difference between both ends of the load terminal and outputs the amplified voltage difference, a PWM control unit for generating a PWM signal for operating the DC-DC converter according to the output signal of the error amplifier, and a load check unit which applies a control power source (Vi) of a predetermined voltage level lower than the input voltage to the load terminal for a predetermined time before the DC-DC converter converts the input voltage to the output voltage, and generates a control signal for controlling the PWM control unit according to the output signal of the error amplifier. Accordingly, the present invention can prevent a circuit from being damaged.

Description

[0001] APPARATUS AND METHOD FOR CONTROLLING DC-DC CONVERTER [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and method for controlling a DC-DC converter, and more particularly, to an apparatus and method for controlling a DC-DC converter operated by a pulse width modulation (PWM) .

Generally, a DC-DC converter (DC-DC converter) is a device that converts a DC power input from the outside into a predetermined DC power required by a load. DC-DC converters are typically a buck converter, a boost converter, a forward converter, a flyback converter, and the like. These DC-DC converters usually get the desired output voltage through PWM (pulse width modulation) control.

When the PWM control device applies a PWM control signal to the field effect transistor (FET), which is a switching element of the buck converter, the input power is connected to the output while the switching element is on, And the pulse-like voltage is smoothed through the LC filter to output the DC voltage. The PWM controller receives the output voltage of the buck converter and compares it with a predetermined reference voltage to perform PWM control.

In the case of the conventional overcurrent protection circuit, the inrush current limit circuit is applied to the input side of the load side, the DC-DC converter is operated without confirming the initial load state, and the output is fed back to check the protection circuit .

However, since the conventional technology is intended to prevent burn-out on the load side rather than to protect the DC-DC converter and the protection circuit is operated by feedback of the converter output change, the overcurrent on the load side, The protection circuit is operated after the output of the converter is first applied, so that there is a possibility that the damage of the equipment may accumulate. In spite of the fact that the overcurrent protection function is actually provided, the DC-DC converter may be burned out by applying the output without checking the short-circuit of the load.

Therefore, when a conventional DC-DC converter having the above-described characteristics is incorporated into a specific component, power is applied regardless of the initial load state, so that a DC-DC converter burnout or damage accumulation There is a need for measures to improve the problems that occur.

Korean Registered Patent No. 10-1515511 (registered on April 21, 2015)

SUMMARY OF THE INVENTION It is an object of the present invention to provide an apparatus and method for controlling a DC-DC converter requiring an overcurrent protection circuit.

A DC-DC converter control apparatus according to an embodiment of the present invention includes a DC-DC converter (DC-DC converter) converting an input voltage into a predetermined output voltage and outputting the input voltage; A negative terminal connected to an output terminal of the DC-DC converter to receive the output voltage of the DC-DC converter; An error amplifier for sensing and amplifying the voltage difference between both ends of the negative terminal; A PWM controller for generating a pulse width modulation (PWM) signal for operating the DC-DC converter according to an output signal of the error amplifier; And the base load checking unit may be configured to control the control power source (V _i ) of a predetermined voltage level lower than the input voltage for a predetermined time, before the DC-DC converter performs an operation of converting the input voltage into the output voltage A load checking unit for applying a control signal to the PWM control unit in response to an output signal of the error amplifier; .

The DC-DC converter is connected to the PWM control unit and the gate G, performs a switching operation in accordance with the PWM signal of the PWM control unit, and the drain D is connected to the N-channel MOSFET connected to the input voltage. an oxide semiconductor field-effect transistor; An inductor having one end connected in series to the source (S) of the N-channel MOSFET transistor and the other end connected to the load; A diode having a cathode connected between the source and the inductor and having an anode connected to the ground; A second capacitor having one end connected between the other end and the lower end of the inductor and the other end connected to the ground; And a control unit.

Wherein the load checking unit includes: a control power source for applying control power to the sub-stage before the DC-DC converter operates; A protection resistor for preventing an overcurrent from flowing to the negative terminal of the control power supply; A voltage sensing unit connected to an output terminal of the error amplifier and measuring a voltage applied to the negative terminal; And a load determination unit for transmitting the control signal to the PWM control unit according to the voltage measured by the voltage sensing unit. And a control unit.

The load determining unit may determine that the load is short-circuited if the voltage measured by the voltage sensing unit is 0V, and shut off the DC-DC converter or output a failure signal.

The load determining unit determines that the negative terminal of the DC-DC converter is in an excessive capacitance state if the voltage measured by the voltage sensing unit is greater than 0 and smaller than the product of the control power source and the voltage charging rate, Wherein the voltage charging rate is a value preset in proportion to a reciprocal of a product of a resistance value of the protection resistor and a capacitance of the lower stage, .

The load determining unit determines that the load is normal if the voltage measured by the voltage sensing unit is greater than or equal to the product of the control power and the voltage charging rate and applies the normal operation signal to the PWM control unit .

A method of controlling a DC-DC converter according to an exemplary embodiment of the present invention includes: applying a control power of a predetermined voltage level to a lower end of a load check unit for a predetermined time; Outputting an error amplifier for sensing and amplifying the voltage difference at the lower stage; Measuring a voltage applied to the negative terminal using the amplified voltage difference; Determining whether there is an abnormality in the lower load according to the measured voltage; Generating a control signal for operating the DC / DC converter if it is determined that there is no abnormality in the lower stage; Outputting a PWM (Pulse Width Modulation) signal for operating the DC-DC converter according to the amplified voltage difference to the DC-DC converter when the PWM control unit receives the control signal; And the DC-DC converter converting the input voltage into the predetermined voltage by the PWM signal and outputting the voltage; .

According to the embodiment of the present invention described above, the DC-DC converter can determine the load condition in advance and then apply the power, so that the circuit is damaged compared with the protection circuit that operates after the output is applied regardless of the load state .

1 is a configuration diagram of a control apparatus for a DC-DC converter according to an embodiment of the present invention.
2 is a method flow diagram of a DC-DC converter control apparatus according to an embodiment of the present invention.
3 is a configuration diagram of a DC-DC converter control apparatus according to another embodiment of the present invention.
4 is a configuration diagram of a DC-DC converter control apparatus according to another embodiment of the present invention.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings. However, the present invention can be implemented in various different forms, and is not limited to the embodiments described. In order to clearly describe the present invention, parts that are not related to the description are omitted, and the same reference numerals in the drawings denote the same members.

Throughout the specification, when an element is referred to as "including" an element, it does not exclude other elements unless specifically stated to the contrary. The terms "part", "unit", "module", "block", and the like described in the specification mean units for processing at least one function or operation, And a combination of software.

1 is a configuration diagram of a control apparatus 100 of a DC-DC converter according to an embodiment of the present invention. In the embodiment of the present invention, the DC-DC converter 110 will be described by taking a buck converter as an example, but it is also applicable to other types of DC-DC converters operated by PWM control.

Load checking unit 120 in Figure 1, the load determination unit (170a), a load including a voltage sensing unit (170b) checking circuit 170, the control power source (V _i), (120a) and a protective resistor (R) (120b ). Here, the protection resistor (R) 120b is provided to prevent a load from being short-circuited to the load terminal 160 to prevent an overcurrent from flowing.

The DC-DC converter 110 converts the input voltage V _IN 130 to a predetermined voltage and outputs the converted voltage V _IN 130 to the N-channel MOSFET (metal-oxide semiconductor field-effect transistor) ), A diode (D1) 110b, an inductor (L1) 110c, and a capacitor (C1) 110d.

The gate G of the N-channel MOSFET transistor 110a is connected to the PWM control unit 140 and the N-channel MOSFET transistor 110a performs a switching operation according to the PWM signal of the PWM control unit 140. [ The drain D of the N-channel MOSFET transistor 110a is connected to the input voltage V _IN 130 and the source S is connected to the inductor 110c of the DC- And a cathode of the diode 110b is connected between the source S and one end of the inductor 110c and the anode is connected to the ground. One end of the capacitor 110d of the DC-DC converter 110 is connected to the other end of the inductor 110c, and the other end of the capacitor 110d is connected to the ground.

The lower stage 160 is a circuit driven by receiving power from the DC-DC converter. Although the load terminal 160 can be implemented by various electronic circuits according to the purpose of use, the load resistor 160a and the load capacitor 160b are replaced with a simplified equivalent circuit for convenience of explanation in FIG. 1 .

One end of the load terminal 160 connected in series with the load resistor 160a and the load capacitor 160b is connected to the output terminal of the DC-DC converter 110 and the output terminal of the load check unit 120. Before the DC-DC converter 110 operates, the control power source V _i is applied to the negative terminal 160 by the load check unit 120, and the error amplifier 150 is connected to the negative And outputs the amplified voltage difference to the output PWM control unit 140 and the voltage sensing unit 170b.

The PWM controller 140 generates a pulse width modulation (PWM) signal for operating the DC-DC converter 110 according to an output signal of the error amplifier 150. At this time, The load determining unit 170a of the load checking unit 120 generates a control signal for controlling the load.

The voltage sensing unit 170b applies the control power source V _i 120a to the negative terminal 160 via the resistor 120b before the DC-DC converter 110 operates, 150 to measure the voltage applied to the lower terminal 160, and transmits the measured voltage to the load determining unit 170a. At this time, the control power source V _i may be set to be applied for about 10 ms at +5 V _dc , but may be variously set. The load determination unit 170a transmits a control signal for operating the Q1 110a to the PWM control unit 140 according to the voltage measured by the voltage sensing unit 170b for about 10 ms.

The load determining unit 170a compares the voltage measured by the voltage sensing unit 170b with the applied voltage V _o applied to the lower stage 160 to determine the state of the load.

Specifically, when the voltage V _o measured by the voltage sensing unit 170b is 0 V (V _o ? 0 V), the load determining unit 170a determines that the load is short-circuited, and the PWM control unit 140 It is possible to shut off the DC-DC converter 110 or output a failure signal without transmitting an operation control signal.

The short circuit of the load terminal 160 is caused by a failure of the load terminal 160 or a flow of conductive foreign matter. When a failure occurs due to a short circuit, the resistance value of the load terminal 160 becomes small. The overcurrent is generated and the converter inside and the load side circuit are burned out.

On the other hand, when the voltage measured by the voltage sensing unit 170b is greater than 0 and smaller than the product of the control power source and the voltage charging ratio (V _o <(V _i X voltage charging rate) It is possible to shut off the DC-DC converter 110 or output a failure signal by determining that the capacitance of the subsidiary terminal 160, that is, the size of the capacitor 160b, is excessive.

The voltage charging rate is set to a value proportional to a reciprocal of a product of a resistance R of the resistor 120b of the load check unit 120 and a capacitance C of the capacitor 160b of the lower stage 160 However, it may be set according to the peripheral circuit specification.

, I : 충전전류, dV : 전압 변화량, dT : 시간 변화량)가 증가하고, 초기 충전 전류가 컨버터 내부 소자 및 부하 측 회로의 허용 전류를 초과할 시 소손이 발생한다. The cause of the excessive capacitance of the negative terminal 160 is generated due to excessive design of the output side smoothing capacitor, a capacitance component of the input filter of the load or other structurally generated capacitance component. When a fault occurs due to an excessive capacitance, Initial charge current by component (

, I: charge current, dV: voltage change amount, dT: time change amount) increases and firing occurs when the initial charge current exceeds the allowable current of the in-converter element and the load-side circuit.

Finally, when the voltage measured by the voltage sensing unit 170b is equal to or greater than the product of the control power source and the voltage charging ratio (V _o ? (V _i X voltage charging rate)), It determines that the negative terminal is normal and applies a normal operation signal to the PWM controller 140. [

2 is a method flow diagram of a DC-DC converter control apparatus according to an embodiment of the present invention.

The load checking unit 120 of the DC-DC converter controller 100 applies the control power V _i 120a to the load terminal 160 through the second resistor 120b. The error amplifier 150 amplifies the voltage difference of the load 160 at step 205 and the voltage of the load applied to the load 160 via the voltage amplified by the error amplifier at step 210 (V _o ) is measured.

If the measured voltage _Vo is 0, the load check unit 120 determines the load shortage in step 220 and stops the operation of the DC-DC converter 110 in step 225 Shut off), and then outputs a failure signal in step 230.

On the other hand, in step 215, the load checking unit 120 compares the measured voltage (V _o) is, V _o, and (V _i x voltage charge rate) in step 235. If the value "0". If V _o is smaller than (V _i x voltage charging rate) in step 235, the load checking unit 120 determines that the capacitance of the lower stage 160 is excessive in step 240, -DC converter 110, and then outputs a failure signal in step 250. In step 250,

In step 235, if the measured voltage V _o is not less than (V _i x voltage charging rate), the load checking unit 120 determines whether the voltage The PWM controller 140 transmits a control signal for operating the DC-DC converter 110 to the N-channel MOSFET transistor 140. The PWM controller 140 transmits the PWM signal to the N-channel MOSFET transistor Q1 110a serving as a switch, DC converter 110 is applied with the input power source (V _IN ) 130.

1, the control power source V _IN used by the load check unit 120 of the DC-DC converter control apparatus is separately configured. However, the control power source may be a main power source as shown in FIG. 3, Or an internal control power source can be used as shown in FIG. 4 below. Also, calculate the R value according to the power source so that the circuit does not burn out.

3 is a configuration diagram of a DC-DC converter control apparatus according to another embodiment of the present invention. 3 shows a case where the main input power source (V _i ) 310 is used as a control power source to be applied to the lower stage, unlike the DC-DC converter control apparatus of FIG. 3 includes a load check circuit 320 including a load determination unit 320a and a voltage sensing unit 320b, and a protection resistor (R) 340. The voltage sensing unit 320b senses the voltage amplified by the error amplifier 150 and the load determination unit 320a compares the sensed voltage with a predetermined value to determine whether the load is normal. 3, the remaining components perform the same operation as the load check circuit 170 shown in FIG. 1, and the remaining components perform the same operations as those of FIG. 1, so that the same reference numerals are given thereto, It will be omitted.

3, the load determining unit 320a determines the voltage V _{o based} on the voltage V _o 330 applied to the load 160 and the value of the main input power V _i 310 by the voltage measuring unit 320b. The state of the lower end 160 is determined. In Figure 3 the load determination unit (320a) is V _o ≒ is 0V, determines that sub-bottom 160 is determined that the short circuit, and V _o <(V _i x voltage charge rate), the capacitance of the portion at the bottom 160, over , And if V _o ? (V _i x voltage charging rate), it is judged to be normal.

3, there is an advantage in that the circuit configuration is relatively simple, since the main input power is directly used in the circuit configuration, but the resistance value of the protection resistor 340 can be increased according to the main input voltage.

4 is a configuration diagram of a DC-DC converter control apparatus according to another embodiment of the present invention. 4, the internal control power source V _s is used to determine the state of the negative terminal. The regulator 415 receives the input power V _i 410, The internal control power supply V _s 430 is input to the load check circuit 420 including the load determination unit 420a and the voltage sensing unit 420b and the PWM control unit 440, Is the same as the described configuration.

4, the load determination unit 420a determines the voltage V _o according to the value of the voltage V _o 450 applied to the load 160 and the internal control voltage V _s 430 by the voltage measuring unit 420b. The state of the lower end 160 is determined. 4 the load determination unit (420a) at the V _o ≒ is 0V, determines that sub-bottom 160 is determined that the short circuit, and V _o <(V _i x voltage charge rate), the capacitance of the portion at the bottom 160, over , And if V _o ? (V _i x voltage charging rate), it is judged to be normal.

The resistance value of the internal control power source protection resistor 460 uses a (V _s) in case of a circuit as shown in FIG. 4 as can be made relatively small applications, the internal control power source of the DC-DC converter is 5V, 3V, etc. There is a disadvantage that the initial operation due to the control power generation time may be delayed a little while the standardization is easy to apply.

The method according to the present invention can be implemented as a computer program stored in a medium for execution in a computer. Where the computer-readable medium can be any available media that can be accessed by a computer, and can also include both computer storage media. Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data, (Digital Versatile Disk) -ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art.

Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

Claims (10)

A control apparatus for a DC-DC converter, comprising:
A DC-DC converter (DC-DC converter) converting an input voltage into a predetermined output voltage and outputting the converted output voltage;
A lower terminal connected to an output terminal of the DC-DC converter and receiving the output voltage of the DC-DC converter;
An error amplifier for sensing and amplifying the voltage difference between both ends of the negative terminal;
A PWM controller for generating a pulse width modulation (PWM) signal for operating the DC-DC converter according to an output signal of the error amplifier; And
A control voltage Vi of a predetermined voltage level lower than the input voltage for a predetermined time is applied to the lower stage before the DC-DC converter performs an operation of converting the input voltage into the output voltage, A control power source for generating a control signal for controlling the PWM control unit according to an output signal of the error amplifier, the control power source for applying a control power to the sub-stage before the DC-DC converter operates; A protection resistor for preventing an overcurrent from flowing to the negative terminal of the control power supply; A voltage sensing unit connected to an output terminal of the error amplifier and measuring a voltage applied to the negative terminal; And transmitting the control signal to the PWM controller according to the voltage measured by the voltage sensing unit when the voltage measured by the voltage sensing unit is greater than 0 and smaller than the product of the control power source and the voltage charging rate, And a load determination unit for determining that the load terminal is in an excessive capacitance state and shutting off the DC-DC converter or outputting a failure signal,
/ RTI &gt;
Wherein the voltage charging rate is a value preset in proportion to a reciprocal of a product of a resistance value of the protection resistor and a capacitance of the lower stage terminal. The method according to claim 1,
The DC-DC converter includes:
An N-channel MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) transistor connected to the PWM control unit and the gate G, performing a switching operation according to the PWM signal of the PWM control unit, and having a drain connected to the input voltage;
An inductor having one end connected in series to the source (S) of the N-channel MOSFET transistor and the other end connected to the load;
A diode having a cathode connected between the source and the inductor and having an anode connected to the ground; And
A second capacitor having one end connected between the other end and the lower end of the inductor and the other end connected to the ground; Wherein the DC-DC converter control unit includes: delete The method according to claim 1,
The load determining unit may determine,
DC converter control device according to claim 1, wherein the DC-DC converter control part determines that the load is short-circuited when the voltage measured by the voltage sensing part is 0 V and turns off the DC-DC converter or outputs a failure signal . delete The method according to claim 1,
The load determining unit may determine,
Wherein when the voltage measured by the voltage sensing unit is greater than or equal to the product of the control power supply and the voltage charging ratio, the control unit determines that the negative terminal is normal and applies the normal operation signal to the PWM control unit. DC converter control device. A control method of a DC-DC converter (DC-DC converter)
Applying a control power of a predetermined voltage level to a load lower end of the load check unit for a predetermined time;
Outputting an error amplifier for sensing and amplifying the voltage difference at the lower stage;
Measuring a voltage applied to the negative terminal using the amplified voltage difference;
Determining whether there is an abnormality in the lower end according to the measured voltage of the load inspecting unit;
Generating a control signal for operating the DC / DC converter if it is determined that there is no abnormality in the lower stage;
Outputting a PWM (Pulse Width Modulation) signal for operating the DC-DC converter according to the amplified voltage difference to the DC-DC converter when the PWM control unit receives the control signal; And
The DC-DC converter converts the input voltage into a predetermined voltage by the PWM signal and outputs the converted voltage
/ RTI &gt;
Wherein the step of determining the abnormality of the lower stage determines that the capacitance of the first capacitor at the lower stage is excessive if the measured voltage is greater than 0 and smaller than the product of the control power supply and the voltage charging rate, -DC converter shut-off, fault signal output,
The voltage charging rate is a value preset in proportion to a reciprocal of a product of a resistance value of the protection resistor provided in the load inspection unit and a capacitance of the lower stage in order to prevent an overcurrent caused by the control power source from flowing to the lower stage DC converter control method. 8. The method of claim 7,
Wherein the step of determining whether or not there is an abnormality in the lower-
Wherein the step of determining that the load is short-circuited if the measured voltage is 0 V, and shutting off the DC-DC converter or outputting a failure signal. delete 8. The method of claim 7,
Wherein the step of determining whether or not there is an abnormality in the lower-
Wherein when the measured voltage is equal to or greater than a product of the control power supply voltage and a voltage charging ratio, it determines that the negative terminal is normal and applies a normal operation signal to the PWM controller.

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