KR101093574B1 - High efficiency dc power supply system using hybrid distribution method - Google Patents

Abstract

The present invention relates to a high efficiency DC power supply system using a hybrid power supply method, comprising: a boost type DC-DC converter for boosting a DC voltage of a low voltage input side to a preset DC output voltage according to an input control signal; Inverting mode that converts DC voltage output from DC link and battery into AC voltage and supplies it to the system and AC load, and converting mode that receives power from the system and stores constant DC output voltage to DC link and battery. A bidirectional PWM converter unit performing; A step-down DC-DC converter unit for stepping down the energy stored in the DC link and the battery to a preset DC feed voltage to transfer power to the DC load; And a control unit configured to control the boost type DC-DC converter unit, the bidirectional PWM converter unit, and the step-down DC-DC converter unit to generate a PWM signal. It includes.
According to the present invention as described above, the DC and AC hybrid power distribution method can be expected to reduce the adverse effects on the system side due to the increase in efficiency of the home load and the input harmonic current in the future, such as reduction of utilization and loss of the distribution line, renewable energy By reducing the conversion process in conjunction with the system, it is possible to reduce the losses generated in the conversion step to increase the utilization of renewable energy.

Description

High efficiency DC power supply system using hybrid power feeding system {HIGH EFFICIENCY DC POWER SUPPLY SYSTEM USING HYBRID DISTRIBUTION METHOD}

The present invention relates to a high-efficiency DC power supply system using a hybrid power supply method, and more particularly, input currents of various loads used in AC 220 [Vac] to examine the DC power supply and energy efficiency of individual loads in a home hybrid power supply Analysis and classify into 4 types of electric heating load, digital load, lighting load and inductive load, and in each case, find out whether DC power supply is possible and DC power supply voltage level that is most suitable to supply DC and AC simultaneously. will be.

Green growth, a new growth concept based on low carbonization and green industrialization, which doubles economic growth power, is attracting global attention. Low carbonization means coping with climate change by reducing CO ₂ emissions from economic activities, and green industrialization means creating new markets through green technologies and eco-friendly business models, thereby driving economic growth.

At present, the major countries of the world are focusing their power on securing the interests of the leaders in the early stages of the green market. In Japan and Europe, which are called energy powerhouses, the vision of the "carbon society" is presented as a vision and related to energy efficiency and renewable energy. We are focusing on core technology development. The energy policies of these countries have greatly strengthened the importance of energy efficiency.

In this regard, increasing energy efficiency means minimizing energy loss throughout the entire process of energy production, transmission, and consumption. Renewable energy, such as wind and solar power, is attracting attention as future energy in order to reduce environmental pollution. But the easiest way to reduce carbon emissions and air pollution is accepted as increasing energy efficiency.

In order to use energy as a direct current, the output power of the new renewable energy is converted to alternating current through a conversion process of a power converter, and the loss generated by heat during DC-AC power conversion is 10 [%] of the total generated power. ]to be. The converted AC power is supplied to the system or to the load within the customer. Most of the electrical equipment used in the home is converted to the DC voltage of the required voltage level by using an AC-DC converter or an adapter attached to the product.

This type of load has a built-in AC-DC converter, such as an adapter, and its efficiency is approximately 80 [%]. As a result, the total loss from the renewable energy to the load is 28 [%] of the generated power.

At present, the method of converting renewable energy into AC through a power converter and supplying it to the load has a large amount of loss occurring in the process of transferring the power to the required power during the transmission and consumption processes, and thus the DC efficiency supply method cannot be satisfied. Is being presented. This DC power supply method has demonstrated efficiency improvement of about 13.2% by applying DC power distribution of 300 ~ 400 [V] at KT Namsuwon Data Center (IDC) since 2008.

Starting with the introduction of such DC distribution, it is spreading a lot now, and it is expected that DC power of 60 [V] or less will be introduced at home with the expansion of solar power generation. In addition, as some countries have recently adopted an incandescent lamp prohibition, the types of loads driven by DC will increase even further, as the lighting load will be replaced by LED lamps, and the need for DC power supply is expected to accelerate.

However, due to the motor load using the AC power directly and the existing distribution line suitable for conventional AC distribution alone, DC feeding alone does not solve this problem. Therefore, the present invention proposes a hybrid power supply system that simultaneously distributes direct current and alternating current to a home, selects a suitable supply voltage for direct current supply, and is easily linked with renewable energy, and can supply DC / AC to a load simultaneously. We would like to propose a hybrid system.

An object of the present invention is to propose a direct current and alternating current hybrid power supply system to supply an appropriate DC voltage to a DC distribution load and to supply AC to other loads to increase efficiency.

High efficiency DC power supply system using a hybrid power supply method of the present invention for achieving the technical problem, step-up DC-DC to perform the function of boosting the DC voltage of the low voltage input side to a predetermined DC output voltage according to the input control signal A converter unit; Inverting mode that converts DC voltage output from DC link and battery into AC voltage and supplies it to the system and AC load, and converting mode that receives power from the system and stores constant DC output voltage to DC link and battery. A bidirectional PWM converter unit performing; A step-down DC-DC converter unit for stepping down the energy stored in the DC link and the battery to a preset DC feed voltage to transfer power to the DC load; And a control unit configured to control the boost type DC-DC converter unit, the bidirectional PWM converter unit, and the step-down DC-DC converter unit to generate a PWM signal. It includes.

The boost type DC-DC converter may boost the DC voltage on the low voltage input side to 330V to 380V.

In addition, the step-down DC-DC converter is characterized in that the voltage stored in the DC link and the battery step-down to a DC feed voltage of 220V to 310V.

In addition, when the supply power of the DC output power is the same as the power consumption of the DC load, the controller boosts the supply voltage of the DC load to the DC link voltage 360 [Vdc] through the boost type DC-DC converter, and boosts the DC link. It includes a rated load mode for controlling the voltage to be transferred to the DC load via the step-down DC-DC converter.

In addition, when the power consumption of the DC load is more than the power supplied by the DC output power, the control unit, the power generated from the DC output power is boosted DC-DC converter unit, DC link and battery and step-down DC-DC converter unit It includes a heavy load mode for supplying a direct current load via, and controlling the insufficient power to be supplied from the system through a bidirectional PWM converter.

If the generated power of the DC output power is greater than the power consumption of the DC load, the control part covers all of the power consumption of the DC load with the DC output power generated power and the remaining power generated through the inverting process of the PWM converter unit. And the surplus power includes a power generation mode that controls the system to regenerate.

According to the present invention as described above, the DC and AC hybrid power distribution method can be expected to reduce the adverse effects on the system side due to the increase in efficiency of the home load and the input harmonic current in the future, such as reduction of utilization and loss of the distribution line, renewable energy By reducing the conversion process in conjunction with the system, it is possible to reduce the losses generated in the conversion step to increase the utilization of renewable energy.

1 is a block diagram showing a built-in rectifier circuit having an AC power source.
Fig. 2 is a diagram showing waveforms of each part of a built-in rectifier circuit having an AC power supply.
3 is a block diagram showing a built-in rectifier circuit having a DC power supply.
4 is a diagram showing waveforms of each part of a built-in rectifier circuit having a DC power supply;
5 is a configuration diagram showing an experimental configuration of a wiring path.
6 is a graph illustrating distribution line loss and voltage drop according to distribution voltage;
7 is a diagram illustrating a basic concept of a hybrid feed system.
8 is a block diagram showing a high efficiency DC power supply system using a hybrid power supply system according to the present invention.
9 is a flow chart showing a power flow for the rated load mode of the high efficiency DC power supply system using a hybrid power supply method according to the present invention.
10 is a flow chart illustrating a power flow for the heavy load mode of the high efficiency DC power supply system using a hybrid power supply method according to the present invention.
11 is a flow chart showing the power flow for the power generation mode of the high efficiency DC power supply system using a hybrid power supply method according to the present invention.

Specific features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings. Prior to this, terms and words used in the present specification and claims are to be interpreted in accordance with the technical idea of the present invention based on the principle that the inventor can properly define the concept of the term in order to explain his invention in the best way. It should be interpreted in terms of meaning and concept. It is to be noted that the detailed description of known functions and constructions related to the present invention is omitted when it is determined that the gist of the present invention may be unnecessarily blurred.

FIG. 1 is a view illustrating rectification circuits inside a product used in a general home, respectively, connected to an AC power source, and FIG. 2 illustrates waveforms of respective parts of a built-in rectifier circuit having an AC power source.

및 내부 저항

, 커패시터의 내부 직렬저항

및 부하저항

등을 정의한다. 이때, 각 경우의 회로손실은 다이오드 필터 커패시터의 흐르는 전류에 의해 좌우된다.1 and 2, first, the voltage drop of the built-in rectifier diode

And internal resistance

Internal series resistance of the capacitor

And load resistance

And so on. In this case, the circuit loss in each case depends on the current flowing through the diode filter capacitor.

)이 연결된 경우, 정류회로의 모든 다이오드가 모두 작동되며, 커패시터로 전류가 흐르게 된다. 이때, 회로내에 흐르는 각 부의 주요파형은 도 2와 같고 회로의 발생되는 손실을 구해보면 [수학식1]과 같다.First, AC power supply (rated RMS value

), All diodes in the rectifier circuit are activated and current flows to the capacitor. At this time, the main waveform of each part flowing in the circuit is as shown in Figure 2 and when the loss generated in the circuit is obtained as [Equation 1].

[Equation 1]

의 소비전력은 [수학식2]와 같다.Also, load when connecting AC power

The power consumption of is shown in [Equation 2].

&Quot; (2) "

On the other hand, Figure 3 is a diagram showing that the rectifier circuit inside the product used in the general home is connected to the DC power supply, respectively, Figure 4 is a diagram showing the waveform of each part of the built-in rectifier circuit having a DC power supply.

)을 내장 정류회로에 공급할 경우, 두 개의 다이오드만이 동작하고, 커패시터전압이 전원전압과 같아지면 더 이상 전류가 흐르지 않게 되어, 도 4 와 같이 회로내 파형이 나타난다. 이때, 직류전압 인가시 회로의 손실은 다이오드의 손실만 나타나므로 [수학식3]으로 표현된다.DC power (average voltage in Figure 3)

) Is supplied to the built-in rectifier circuit, and only two diodes operate, and when the capacitor voltage is equal to the power supply voltage, no current flows any more, and the waveform in the circuit appears as shown in FIG. 4. At this time, the loss of the circuit when applying the DC voltage is represented by the equation (3) because only the loss of the diode appears.

&Quot; (3) "

의 소비전력은 [수학식4]와 같다.Also, load when connecting DC power

The power consumption of is shown in [Equation 4].

&Quot; (4) "

과

는 동일해야 하므로 교류 및 직류에 대한 관계식을 [수학식5]와 같이 도출할 수 있다. Regardless of the type of power supply, the power consumption of the load resistor in FIGS. 1 and 3

and

Since must be the same, the relation for AC and DC can be derived as shown in [Equation 5].

[Equation 5]

가 교류전원 인가시 전류

보다 작음을 알 수 있다. 즉, 직류급전시 내장 정류회로에서 발생하는 손실이 적음을 알 수 있다. 특히, 직류의 경우 필터 커패시터는 개방되므로 손실이 발생하지 않는데, 이 값은 실제 정류회로에서 발생하는 총 손실의 70[%]를 차지하고 있다.According to Equations 1 to 5, the magnitude of current when DC power is applied.

Current when AC power is applied

It can be seen that less. That is, it can be seen that the loss generated in the built-in rectifier circuit during the DC power supply is small. In particular, in the case of direct current, the filter capacitor is open so that no loss occurs. This value accounts for 70 [%] of the total loss in the actual rectifier circuit.

Also, although not expressed by the formula, since the AC output has a lower waveform rate or crest factor than DC, the loss in the rectifier device will increase somewhat. Therefore, DC feeding rather than AC has a built-in rectifier circuit. It can be seen that the efficiency can be improved.

Ultimately, if the DC power supply is made and the voltage level is appropriate, the rectifier element itself becomes unnecessary and the loss of the rectifier element can be eliminated. In addition, the problem that the harmonic current is generated at the input terminal of the rectifier circuit and the power factor is also lowered in the case of DC power supply can be solved.

In addition, the loss generated in the indoor wiring path greatly decreases the input power factor of the built-in rectifier circuit when the AC power is applied to 0.5 to 0.6. As such, the low power factor causes the input current to be large, thereby increasing the distribution line loss and the voltage drop.

Meanwhile, referring to FIG. 5, the characteristics of the hybrid power distribution through the circuit with a simple wiring are as follows.

및 부하 입력단은

로 표기하며 교류급전시

, 직류급전시

를 나타내고, 회로해석을 위해 직류전원은 교류정격전압(실효값 220[V])의 k배로 정의하였으며, 이는 [수학식6]과 같다.The resistance value existing in the indoor distribution line of 20m or more is r (the reactance of the 20m line is much smaller than the line resistance in the alternating current distribution. Therefore, the reactance component of the line is ignored for convenience of calculation.)

And the load input stage

In the form of

, DC feeding

For the circuit analysis, DC power was defined as k times the AC rated voltage (effective value 220 [V]), as shown in [Equation 6].

[Equation 6]

, 부하전류를

, 배선로 저항을 2r, 역률을

및 선로손실을

라 할 경우, 교류에 의한 배선로에서 발생하는 손실은 [수학식7]과 같다.In addition, the load power consumption

Load current

, Wiring resistance 2r, power factor

And track losses

In this case, the loss generated in the wiring path by AC is shown in [Equation 7].

[Equation 7]

, 부하소비전력을

, 부하전류를

, 배선로 저항을 2r 및 선로손실을

라 할 경우, 직류인가시 배선로의 발생 손실은 [수학식8]과 같다.In addition, the DC distribution voltage

Load power consumption

Load current

2r resistance and wiring loss

In this case, the loss in the wiring path when applying DC is expressed by [Equation 8].

[Equation 8]

In addition, the relation between current magnitude and line loss in two different power feeding methods is shown in Equation (9).

[Equation 9]

즉, 직류전압의 크기를 교류의 실효값이상으로 설정하게 되면, 부하의 역률이 낮을수록 배선로에 흐르는 교류전류의 크기가 더 커져 전선의 손실이 증가된다.As shown in [Equation 9],

That is, when the magnitude of the DC voltage is set to be equal to or greater than the effective value of AC, the lower the power factor of the load, the larger the magnitude of the AC current flowing through the wiring line, and the loss of the wire increases.

일 때 DC배전 전류의 크기와 배전선에서 발생하는 손실은 상기 [수학식8]을 통해 도출할 수 있으며, 직류급전시 역률 1로 유지가능하기 때문에 교류전압의 피크값과 동일한 직류전압(

)을 인가하게 되면 동일 전력 공급시, 도 6 에서 도시된 바와 같이 교류보다 전류 크기가

로 작아져 배전선에 발생하는 손실을 저감 할 수 있을 뿐만 아니라 기존 배선로의 이용률을 높일 수 있다.When the same load power is transmitted, the DC voltage

When the magnitude of the DC distribution current and the loss occurring in the distribution line can be derived through Equation (8) above, and the DC power factor can be maintained at the power factor of 1 during the DC power supply, so that the DC voltage equal to the peak value of the AC voltage (

), When the same power is supplied, as shown in FIG.

As a result, the loss caused by distribution lines can be reduced, and the utilization rate of existing wiring lines can be increased.

In addition, as shown in FIG. 7, the hybrid power supply system includes two power supplies, an AC power supply and a DC power supply, and two types of loads, AC loads, AC loads, and a switching matrix that interconnects them. Can be configured.

Hereinafter, the high efficiency DC power supply system S using the hybrid power feeding method according to the present invention with reference to FIGS. 8 to 11 is as follows.

8 is a block diagram showing a high-efficiency DC power supply system using a hybrid power supply method according to the present invention, the boost-type DC-DC converter unit 100, the bidirectional PWM converter unit 200, the DC link and the battery 300 as a whole , The step-down DC-DC converter 400 and the control unit 500 is configured to include.

Specifically, the boosted DC-DC converter unit 100 is configured in the form of a full-bridge converter, and the DC voltage of the low voltage input side is set as a preset DC output voltage (330V to 380V) according to the input control signal. It boosts the function, and as the input and output are separated by the high frequency insulation type transformer, the safety of the renewable energy of the input side can be secured and the wide voltage range of the input side can be secured due to the high boost ratio of the transformer.

In addition, the bidirectional PWM converter 200 performs the function of the inverting mode and the converting mode at the same time, the inverting mode converts the DC voltage output from the DC link and the battery 300 into an AC voltage to the system and the AC load The power supply is started to supply, and the converting mode is supplied to receive power from the system and starts to store a constant DC output voltage in the DC link and the battery 300.

In addition, the step-down DC-DC converter 400 has a structure of a buck converter, by stepping down the energy (voltage 360V) stored in the DC link and the battery 300 to a constant voltage of the DC feed voltage (220V to 310V) It performs the function of transferring power to DC load.

The control unit 500 controls the step-up type DC-DC converter unit 100, the bidirectional PWM converter unit 200, the DC link and the battery 300, and the step-down DC-DC converter unit 400 which are the above-described components. In addition to controlling, it generates a PWM signal and controls the operation mode of the hybrid power distribution type DC power supply system.

Specifically, the control unit 500 may be divided into three modes of operation of the entire system, each of which is rated load mode (mode 1), heavy load mode (mode 2) and power generation according to the power consumption of the DC load. It is divided into mode (mode 3).

First, the rated load mode of the controller 500 assumes that the supply power of the DC output power is the same as the power consumption of the DC load, and the supply energy of the DC load is DC through the step-up DC-DC converter unit 100. The power boosted by the link voltage 360 [Vdc] is transferred to the direct current load via the step-down DC-DC converter 400. At this time, as shown in FIG. 9, since only the generated power of the DC output power is used in the DC load, the power required for the AC load is directly supplied in connection with the system.

In addition, the heavy load mode of the control unit 500 is a mode that starts when the power consumption of the DC load is greater than the energy supplied by the DC output power source. All of the power supplied is supplied to the DC load via the boost type DC-DC converter unit 100, the DC link and the battery 300, and the step-down DC-DC converter unit 400, and insufficient energy is supplied to the bidirectional PWM converter unit ( Maneuver from the system via 200). At this time, the energy required for the AC load is also directly supplied with the system.

In addition, the power generation mode of the control unit 500 is a mode that starts when the generated power of the DC output power is greater than the power consumption of the DC load. When the power generation mode of the control unit 500 is referred to, the power consumption of the DC load is measured. All of the remaining generated power is supplied to the AC load through the inverting process of the PWM converter unit 200 and the surplus power is started to regenerate to the system.

That is, as described above, by implementing a hybrid power distribution system in which the control unit 500 directly boosts or lowers the DC output power to correspond to the rated load mode, the heavy load mode, and the power generation mode, thereby providing AC / DC or DC / As the AC conversion step is reduced, the efficiency of the DC output power source can be improved.

As described above and described with reference to a preferred embodiment for illustrating the technical idea of the present invention, the present invention is not limited to the configuration and operation as shown and described as described above, it is a deviation from the scope of the technical idea It will be understood by those skilled in the art that many modifications and variations can be made to the invention without departing from the scope of the invention. And all such modifications and changes as fall within the scope of the present invention are therefore to be regarded as being within the scope of the present invention.

S: High efficiency DC feeding system using hybrid feeding method
100: step-up DC-DC converter unit 200: bidirectional PWM converter unit
300: DC link and battery 400: step-down DC-DC converter unit
500: control unit

Claims (6)

In a high efficiency DC feeding system using a hybrid feeding method,
A boost type DC-DC converter configured to boost a DC voltage at a low voltage input side to a preset DC output voltage according to an input control signal;
Inverting mode that converts DC voltage output from DC link and battery into AC voltage and supplies it to system and AC load, and converting mode that receives power from system and stores constant DC output voltage in the DC link and battery Bidirectional PWM converter unit for performing;
A step-down DC-DC converter unit for stepping down the energy stored in the DC link and the battery to a preset DC feed voltage to transfer power to the DC load; And
A controller which controls the boosted DC-DC converter, the bidirectional PWM converter and the step-down DC-DC converter and generates a PWM signal; Including,
When the supply power of the DC output power is the same as the power consumption of the DC load, the control unit boosts the supply voltage of the DC load to the DC link voltage 360 [Vdc] through the step-up DC-DC converter, and boosts the DC link. A rated load mode for controlling a voltage to be transmitted to a DC load via the step-down DC-DC converter;
When the power consumption of the DC load is more than that supplied by the DC output power, the power generated from the DC output power is supplied via the boost type DC-DC converter unit, the DC link, and the battery and step-down DC-DC converter unit. A heavy load mode for supplying power to the system and controlling the insufficient power to be supplied from the system through the bidirectional PWM converter; And
When the generated power of the DC output power is more than the power consumption of the DC load, the power consumption of the DC load is all covered by the DC output power and the remaining power is supplied to the AC load through the inverting process of the PWM converter unit. High power DC power supply system using a hybrid power supply method, characterized in that it comprises a power generation mode to control the power to regenerate the system. The method of claim 1,
The boost type DC-DC converter unit,
A high-efficiency DC power supply system using a hybrid power feeding method, characterized by boosting the DC voltage of the low voltage input side to 330V to 380V. The method of claim 1,
The step-down DC-DC converter,
High-efficiency DC power supply system using a hybrid power supply method characterized in that for stepping down the voltage stored in the DC link and the battery to a DC power supply voltage of 220V to 310V. delete delete delete

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