KR20170050531A

KR20170050531A - Dc-ac inverter

Info

Publication number: KR20170050531A
Application number: KR1020150152180A
Authority: KR
Inventors: 김명오; 천명식
Original assignee: 엘에스오토모티브 주식회사
Priority date: 2015-10-30
Filing date: 2015-10-30
Publication date: 2017-05-11

Abstract

An insulated DC-AC inverter capable of controlling the secondary DC voltage on the output side while the input side and output side are insulated is disclosed. An insulated DC-AC inverter according to one aspect of the present invention includes: a power supply device for converting a DC input voltage into a switching pulse and outputting the switching pulse; A transformer for boosting the voltage output from the power supply device; A rectifying and DC high voltage unit for rectifying and amplifying the voltage boosted by the transformer; An H-bridge switching unit converting the voltage output from the rectifying and DC high-voltage unit into an AC voltage and outputting the converted voltage; A voltage detector for outputting a signal according to a comparison result between an output voltage of the rectifying and direct current high voltage unit and a reference voltage; And an isolation circuit part for transmitting a signal of the voltage detection part to the power supply device, and the power supply device turns on or off the operation of the pulse width modulation based on a signal transmitted through the insulation circuit part.

Description

DC-AC inverter {DC-AC INVERTER}

The present invention relates to a DC-AC inverter, and more particularly, to an insulated DC-AC inverter.

Recently, as the use of AC-powered appliances (game machines, mobile phone chargers, Notebook PCs, etc.) in automobiles has increased, the use of DC-AC inverters to convert DC voltage to AC voltage is also increasing. Especially in leisure vehicles, it tends to be installed as basic equipment. These DC-AC inverters are largely divided into sinusoidal (sinusoidal) and modal (sinusoidal) inverters according to their output waveforms. The DC-AC inverter can be classified into an insulated inverter and a non-isolated inverter depending on whether the input side ground and the output side ground are connected.

1 is a schematic configuration diagram of an insulated transform sinusoidal DC-AC inverter according to the related art. 1, the insulated transformer sinusoidal DC-AC inverter includes a switching mode power supply (SMPS) 10, a transformer 20, a rectifying and DC high-voltage unit 30, an H-bridge switching unit 40, Unit (MCU) (not shown).

1, a DC input voltage (for example, a low voltage of 12 V as a voltage of a battery of a vehicle) is applied to the SMPS 10 through a 20 KHz to 100 KHz switching pulse And then the voltage is converted through the transformer 20. Then, the boosted voltage is converted to DC 200V to 300V through the rectifying and DC high-voltage unit 30, and this voltage is converted into square-wave AC voltage from the H-bridge switching unit 40 and output to the load.

The isolated transformer sine wave DC-AC inverter has input side ground (Gin) and output side ground (Gout) separated from the transformer (20). Since the input-side ground and the output-side ground are separated as described above, the input-side ground Gin and the output-side ground Gout are independent of each other even if any one line of the output side through which the high voltage flows is in the electric-shocked state.

This conventional insulated transformed sinusoidal DC-AC inverter has a DC output voltage (hereinafter, referred to as a secondary DC voltage) that flows through the transformer 20, depending on whether the DC input voltage ). As described above, since the input-side ground and the output-side ground are separated from each other, the insulated transform sinusoidal DC-AC inverter can not receive feedback on the secondary DC voltage from the input side, DC voltage can not be controlled separately on the input side. Therefore, when the DC input voltage is high and the load is unloaded or the load is small, the secondary DC voltage becomes high. Therefore, it is necessary to select a component having a high withstand voltage in consideration of the design of the DC-AC inverter. It may be damaged due to an internal pressure problem.

Accordingly, in order to generate a constant output voltage, that is, a constant AC 110V or 220V voltage, the H-bridge switching unit 40 is controlled according to the secondary DC voltage to control the output waveform without directly controlling the secondary DC voltage . That is, when the secondary DC voltage is fluidly changed, the H-bridge switching unit 40 is controlled so that the pulse width of the output waveform is narrowed or widened so that the total area is constantly adjusted to constantly adjust the output voltage. 2, when the secondary DC voltage changes from V = Low state to V = High state, the pulse width of the output waveform of the DC-AC inverter of the conventional insulated transformed sinusoidal wave DC- When the secondary DC voltage changes from V = Low state to V = High state, the pulse width Ton of the output waveform is widened to adjust the total area constantly, Make the output voltage constant.

However, when the circuit is constituted as described above, since the secondary DC voltage is changed in accordance with the variation of the input voltage, a high secondary DC voltage is generated when the input voltage is high, There is a problem that the component may be burned due to the voltage. In addition, when the pulse width is short, since the current must flow for a short pulse width period when the capacitive load is connected, the inrush current flows more than when the pulse width is wide, And the quality of the AC-powered equipment may be deteriorated due to inrush current.

The present invention provides a DC-AC inverter in which an input side and an output side are insulated from each other and an insulated DC-AC inverter capable of controlling a secondary DC voltage on the output side from an input side, It has its purpose.

According to an aspect of the present invention, there is provided an isolated DC-AC inverter including: a power supply for converting a DC input voltage into a switching pulse and outputting the switching pulse; A transformer for boosting the voltage output from the power supply device; A rectifying and DC high voltage unit for rectifying and amplifying the voltage boosted by the transformer; An H-bridge switching unit converting the voltage output from the rectifying and DC high-voltage unit into an AC voltage and outputting the converted voltage; A voltage detector for outputting a signal according to a comparison result between an output voltage of the rectifying and direct current high voltage unit and a reference voltage; And an isolation circuit part for transmitting a signal of the voltage detection part to the power supply device, and the power supply device turns on or off the operation of the pulse width modulation based on a signal transmitted through the insulation circuit part.

The insulated DC-AC inverter includes an output-side control unit connected to the H-bridge switching unit for measuring an output current and delivering a signal according to a comparison result between an output current and a reference current to the insulation circuit unit; And an input-side controller for receiving a signal according to a comparison result between the output current and the reference current from the isolation circuit and controlling the power supply based on the signal.

The output-side controller may transmit a PWM signal having a duty cycle proportional to a difference between an output current and a reference current to the insulation circuit.

Wherein the output side controller further measures a temperature of the inverter and transmits a signal according to a comparison result between the internal temperature and the reference temperature to the insulation circuit part, And controls the power supply based on the received signal.

Wherein the output side control unit includes a first PWM signal having a duty cycle proportional to a difference between an output current and a reference current and a second PWM signal having a duty cycle proportional to a difference between an internal temperature and a reference temperature, The first PWM signal and the second PWM signal may be differentiated by different periods.

The voltage detector transmits a high signal or a low signal to the insulation circuit part according to a result of comparison between the output voltage of the rectifying and direct current high voltage part and the reference voltage, The operation of the pulse width modulation can be turned on or off based on the high signal or the low signal transmitted through the high-

According to another aspect of the present invention, there is provided an isolated DC-AC inverter including: a power supply for converting a DC input voltage into a switching pulse and outputting the switching pulse; A transformer for boosting the voltage output from the power supply device; A rectifying and DC high voltage unit for rectifying and amplifying the voltage boosted by the transformer; An H-bridge switching unit converting the voltage output from the rectifying and DC high-voltage unit into an AC voltage and outputting the converted voltage; An output side controller connected to the H-bridge switching unit for measuring an output current and delivering a signal according to a comparison result between an output current and a reference current to an isolation circuit; And an input side controller for receiving a signal according to a comparison result between the output current and the reference current from the isolation circuit portion and controlling the power supply device based on the received signal.

In the present invention, the DC voltage of the output side can be controlled by monitoring the DC voltage of the output side from the input side in the insulated DC-AC inverter in which the input side and the output side are insulated, thereby enhancing the durability of the internal parts of the DC-AC inverter.

Further, the present invention can actively control the DC-AC inverter to control the DC voltage on the output side when the internal temperature of the DC-AC inverter is high or the output current flows heavily, thereby improving the stability of the DC-AC inverter.

1 is a schematic configuration diagram of an insulated transform sinusoidal DC-AC inverter according to the related art.
2 is a diagram showing an output waveform of a conventional insulated transform sinusoidal DC-AC inverter.
3 is a diagram illustrating a configuration of an insulated DC-AC inverter according to an embodiment of the present invention.
4 is a diagram illustrating a configuration of an H-bridge switching unit according to an embodiment of the present invention.
5 is a diagram illustrating the configuration of an insulated DC-AC inverter according to another embodiment of the present invention.

The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings, in which: There will be. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is a diagram illustrating a configuration of an insulated DC-AC inverter according to an embodiment of the present invention. The insulated DC-AC inverter according to the present invention will be described as an insulated strain sine wave DC-AC inverter.

3, the isolated DC-AC inverter according to the present embodiment includes an SMPS (Switching Mode Power Supply) 310, a transformer 320, a rectifying and DC high-voltage unit 330, an H-bridge H an LC filter unit 350, an output side control unit 360, an insulation circuit unit 370, and an input side control unit 380. The input /

The SMPS 310 is a power supply unit that converts a DC input voltage (e.g., DC 12V) into a switching pulse of 20 kHz to 100 kHz and outputs the switching pulse. That is, a pulse width modulation (PWM) circuit provided inside the SMPS 310 receives a current control signal from the input-side control unit 380, passes a DC input voltage through an internal amplifier, compares it with an oscillator voltage, And then converted into a switching pulse by outputting a pulse-width-modulated (PWM) signal to a MOSFET serving as a switching element.

The voltage output from the SMPS 310 is stepped up through the transformer 320. The voltage boosted by the transformer 320 is rectified and amplified through the rectifying and DC high-voltage unit 330 and is output from DC 200 V to 300 V. The voltage output from the rectifying and DC high-voltage unit 330 is supplied to the H- 340, and is output to the load through the smoothing process of the LC filter unit 350.

The H-bridge switching unit 340 converts the DC voltage to an AC voltage. 4 is a diagram illustrating a configuration of an H-bridge switching unit according to an embodiment of the present invention. The H-bridge switching unit 340 includes an H-bridge driving module 410 and an H-bridge switching module 420. The H-bridge drive module 410 drives the H-bridge switching module 420 to output an AC voltage. The H-bridge switching module 420 is generally composed of four switching elements. The switching element may be composed of four FET elements (or four transistors), or a multiple thereof (e.g., eight, twelve, sixteen, etc.). The H-bridge switching module 420 outputs an AC waveform of a square wave type by switching operation of 'X' shape using four switching elements. For example, when the AC output is divided into the first section and the second section, the first switch S1 and the fourth switch S4 are turned on and the second switch S2 The second switch S2 and the third switch S3 are turned off while the first switch S1 and the fourth switch S4 are turned off in the second section, (S3) is turned ON, and AC waveforms of square wave form are outputted in the first and second sections.

The output side control unit 360 is connected to the H-bridge switching unit 340 and controls the conversion of the DC voltage to the AC voltage by applying the H-bridge PWM signal to the H-bridge switching unit 340, And measures the output current and the internal temperature of the inverter and transmits the information on the output current and the internal temperature to the isolation circuit unit 370. The output-side controller 360 may periodically transmit the information on the output current and the internal temperature to the isolation circuit unit 370. [

Specifically, the output-side control unit 360 includes a sensing resistor connected in series with the third switch S3 and the fourth switch S4 of the H-bridge switching module 420 of the H-bridge switching unit 340 Measures the output current flowing through the sensing resistor, and transmits a comparison value between the measured output current and the reference current to the insulation circuit unit 370. The output-side controller 360 includes a temperature sensor, compares the internal temperature measured by the temperature sensor with a reference temperature, and transmits the comparison value to the insulation circuit unit 370.

The output-side controller 360 can transmit a comparison value between the output current and the reference current or a comparison value between the internal temperature and the reference temperature as a PWM signal. Specifically, the output-side controller 360 can set the duty cycle of the PWM signal in proportion to the difference between the output current and the reference current and the difference between the internal temperature and the reference temperature. For example, when the output current is larger than the reference current, the duty cycle is proportionally increased as the difference increases, and when the output current is smaller than the reference current, the duty cycle is reduced in proportion as the difference increases. Here, the duty cycle means a time ratio in which the pulse width is maintained for one period. The PWM signal relating to the output current and the PWM signal relating to the temperature can be distinguished by different periods. For example, the PWM signal for the output current is divided by 1 kHz and the PWM signal for the temperature is divided into 5 kHz, which can be alternated every second. Alternatively, the PWM signal may be transmitted by combining information on the output current and the temperature.

The isolation circuit portion 370 is a circuit capable of transmitting a signal while insulating the input side and the output side, for example, a photocoupler. The photocoupler consists of an LED and a phototransistor. The photocoupler emits light when the LED is energized. The phototransistor receives the light and operates the transistor to transmit the electrical signal. The isolation circuit unit 370 transmits information about the output current and internal temperature transmitted from the output-side control unit 360 to the input-side control unit 380.

The input side controller 380 performs PWM control of the SMPS 310 according to the information transmitted from the isolation circuit unit 370 to change the secondary DC voltage on the output side. Specifically, the input side controller 380 analyzes the information transmitted from the isolation circuit unit 370, and when the output current is higher than the reference current or the internal temperature is higher than the reference temperature, the pulse width of the PWM of the SMPS 310 To stabilize the secondary DC voltage. At this time, the input side controller 380 may temporarily turn off the PWM operation.

5 is a diagram illustrating the configuration of an insulated DC-AC inverter according to another embodiment of the present invention. In the embodiment with reference to FIG. 5, the same reference numerals as in the embodiment described with reference to FIG. 3 perform the same functions and operations, and a description thereof will be omitted.

Referring to FIG. 5, the isolated DC-AC inverter according to the present embodiment further includes a voltage measuring unit 510 for measuring the output voltage of the rectifying and DC high-voltage unit 330. The voltage measuring unit 510 compares the output voltage of the rectifying and DC high-voltage unit 330 with the reference voltage, outputs a low signal when the output voltage is lower than the reference voltage, and outputs a High signal when the output voltage is higher than the reference voltage. Output. For example, the voltage measuring unit 510 may be an OP-AMP.

The signal output from the voltage measuring unit 510 is transmitted to the SMPS 310 via the isolation circuit unit 370 and the SMPS 310 turns on and off the PWM operation according to the signal received from the isolation circuit unit 370. More specifically, when the DC output voltage of the rectifying and DC high-voltage section 330 rises, it becomes higher than the reference voltage in the OP-AMP, and the OP-AMP outputs a High signal. Therefore, the High signal is transmitted to the SMPS 310 via the isolation circuit unit 370, and the SMPS 310 turns off the PWM operation to drop the DC output voltage. When the DC output voltage drops, it becomes lower than the reference voltage in OP-AMP, and OP-AMP outputs a low signal. Accordingly, the Low signal is transmitted to the SMPS 310 via the isolation circuit unit 370, and the SMPS 310 turns on the PWM operation again to raise the DC output voltage. Thus, by monitoring the output side DC voltage in real time and turning on or off the input side PWM operation, the output side DC voltage is operated so as to always maintain a constant voltage irrespective of variations of the input voltage or the presence or absence of the load.

While the specification contains many features, such features should not be construed as limiting the scope of the invention or the scope of the claims. In addition, the features described in the individual embodiments herein may be combined and implemented in a single embodiment. Conversely, various features described in the singular < Desc / Clms Page number 5 > embodiments herein may be implemented in various embodiments individually or in combination as appropriate.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. The present invention is not limited to the drawings.

310: SMPS
320: Transformer
330: rectified and DC high voltage
340: H-bridge switching unit
350: LC filter
360:
370: Insulation circuit part
380: Input side control unit
510:

Claims

In an isolated DC-AC inverter,
A power supply for converting a DC input voltage into a switching pulse and outputting the switching pulse;
A transformer for boosting the voltage output from the power supply device;
A rectifying and DC high voltage unit for rectifying and amplifying the voltage boosted by the transformer;
An H-bridge switching unit converting the voltage output from the rectifying and DC high-voltage unit into an AC voltage and outputting the converted voltage;
A voltage detector for outputting a signal according to a comparison result between an output voltage of the rectifying and direct current high voltage unit and a reference voltage; And
And an isolation circuit part for transmitting a signal of the voltage detection part to the power supply device,
Wherein the power supply device turns on or off the operation of the pulse width modulation based on a signal transmitted through the insulation circuit part.

The method according to claim 1,
An output side controller connected to the H-bridge switching unit for measuring an output current and transmitting a signal according to a comparison result between an output current and a reference current to the insulation circuit; And
Further comprising: an input side control unit for receiving a signal according to a comparison result between the output current and the reference current from the insulation circuit unit and controlling the power supply device based on the signal.

3. The method of claim 2,
The output-
Wherein the PWM signal having a duty cycle proportional to a difference between an output current and a reference current is transmitted to the insulation circuit section.

3. The method of claim 2,
The output side control unit measures the internal temperature of the inverter and further transmits a signal according to a result of comparison between the internal temperature and the reference temperature to the insulation circuit unit,
Wherein the input side control part receives the signal from the insulation circuit part according to a result of comparison between the internal temperature and the reference temperature and controls the power supply device based thereon.

5. The method of claim 4,
The output-
A first PWM signal having a duty cycle proportional to a difference between an output current and a reference current and a second PWM signal having a duty cycle set in proportion to a difference between an internal temperature and a reference temperature,
Wherein the first PWM signal and the second PWM signal are differentiated by different periods.

The method according to claim 1,
An output side controller for measuring an internal temperature and transmitting a signal according to a comparison result between an internal temperature and a reference temperature to the insulation circuit; And
Further comprising an input-side control unit for receiving a signal according to a result of comparison between the internal temperature and the reference temperature from the insulation circuit unit and controlling the power supply unit based on the signal.

The method according to claim 6,
The output-
And the PWM signal having a duty cycle proportional to a difference between an internal temperature and a reference temperature is transmitted to the insulation circuit part.

8. The method according to any one of claims 1 to 7,
The voltage detector may include:
A high signal or a low signal is transmitted to the insulation circuit section according to a result of comparison between the output voltage of the rectifying and direct current high voltage section and the reference voltage,
Wherein the power supply device turns on or off the operation of the pulse width modulation based on the high signal or the low signal transmitted through the insulation circuit portion.

In an isolated DC-AC inverter,
A power supply for converting a DC input voltage into a switching pulse and outputting the switching pulse;
A transformer for boosting the voltage output from the power supply device;
A rectifying and DC high voltage unit for rectifying and amplifying the voltage boosted by the transformer;
An H-bridge switching unit converting the voltage output from the rectifying and DC high-voltage unit into an AC voltage and outputting the converted voltage;
An output side controller connected to the H-bridge switching unit for measuring an output current and delivering a signal according to a comparison result between an output current and a reference current to an isolation circuit; And
And an input side control section for receiving a signal from the insulation circuit section according to a comparison result between the output current and the reference current and controlling the power supply device based on the received signal.

10. The method of claim 9,
The output-
Wherein the PWM signal having a duty cycle proportional to a difference between an output current and a reference current is transmitted to the insulation circuit section.

10. The method of claim 9,
The output side control unit measures the internal temperature of the inverter and further transmits a signal according to a result of comparison between the internal temperature and the reference temperature to the insulation circuit unit,
Wherein the input side control part receives the signal from the insulation circuit part according to a result of comparison between the internal temperature and the reference temperature and controls the power supply device based thereon.

12. The method of claim 11,
The output-
A first PWM signal having a duty cycle proportional to a difference between an output current and a reference current and a second PWM signal having a duty cycle set in proportion to a difference between an internal temperature and a reference temperature,
Wherein the first PWM signal and the second PWM signal are differentiated by different periods.