KR20210150176A - Hybrid power system, apparatus and control method performing power distribution between fuel cell and battery - Google Patents

Abstract

The present invention relates to a hybrid power system, a device and control method for power distribution between a fuel cell and a battery. The hybrid power system includes: a first DC/DC converter connected to the fuel cell and converting a DC voltage produced by the fuel cell according to a first switching control signal and providing it to a DC link; a second DC/DC converter connected to the battery and converting a voltage of a DC link to the battery according to second and third switching control signals, or converting a DC voltage of the battery and providing it to the DC link; and a controller which determines a load sharing ratio between the fuel cell and the battery by analyzing the characteristics according to the requirements of an external load connected to the DC link, and outputs first to third switching control signals for feedback-controlling an output current of the fuel cell and the voltage of the DC link according to the load sharing ratio. Accordingly, it is possible to secure the stability of the entire hybrid power system and improve a lifespan.

Description

HYBRID POWER SYSTEM, APPARATUS AND CONTROL METHOD PERFORMING POWER DISTRIBUTION BETWEEN FUEL CELL AND BATTERY

The embodiment relates to a hybrid power system, an apparatus, and a control method for performing power distribution between a fuel cell and a battery. More specifically, in an integrated fuel cell-battery hybrid power system in which a fuel cell and a battery are connected in parallel in one system, it relates to a technology for stably controlling the output of a fuel cell and charging and discharging of a battery regardless of a change in an external load will be.

In general, a fuel cell is a device that produces electricity through an electrochemical reaction. Hydrogen (H2) supplied to an anode is dispersed on the electrode surface by a platinum catalyst to generate hydrogen ions (H+, proton) and electrons (e-, It is characterized in that it is separated into electrons). At the cathode, hydrogen ions that have moved through the electrolyte and electrons that have moved through an external load react with oxygen supplied to the cathode to generate water. Through this process, the fuel cell is an energy conversion device that generates electricity by the external flow of electrons.

Polymer Electrolyte Membrane Fuel Cell (PEMFC) has higher current density and power density, shorter start-up time, and faster response to load changes compared to other types of fuel cells. is suitable as These fuel cells can achieve 2 to 3 times higher efficiency than the combustion method used in existing internal combustion engines, and as an eco-friendly energy source that can minimize the generation of environmental pollutants, they are commercialized in various fields through continuous R&D. is becoming

The fuel cell-battery hybrid power system is a new concept independent power source type renewable energy power device that supplies the required power according to the demand by connecting the fuel cell and the battery in parallel. In such a system, by supplying power by connecting a fuel cell as a main power source and a battery as an auxiliary power source, the fuel cell capacity can be installed smaller than that of a single fuel cell system of the same capacity, thereby reducing system cost.

1 is a diagram illustrating a typical fuel cell-battery hybrid power system.

Referring to FIG. 1 , a fuel cell-battery hybrid power system 1 includes a fuel cell 10 , a battery pack 20 , a DC/DC converter 30 , a controller 40 , an inverter 50 , and an external load ( 60). The fuel cell 10 produces a DC voltage of a certain size and is used as a main power source.

The battery pack 20 is connected in parallel to the DC link and is used as an auxiliary power source. The battery pack 20 is charged by receiving the DC voltage generated from the fuel cell 10 through the DC link, and discharges the charging voltage to the DC link. The DC/DC converter 30 converts the DC voltage produced by the fuel cell 10 into a DC voltage of another level and outputs it to the DC link.

When the power demand of the external load 60 is low, the controller 40 operates the fuel cell 10 at a low output while charging the surplus power to the battery pack 20 . On the other hand, when the power demand of the external load 60 is high, the battery pack 20 is discharged simultaneously with the operation of the fuel cell 10 .

However, in the hybrid power system 1 having the above structure, the output of the fuel cell 10 fluctuates as the power demand of the external load 60 changes, so that the life of the fuel cell 10 is shortened, and the battery pack 20 ), the DC link voltage fluctuates according to the charge rate, so that the power quality is deteriorated, and the capacity of the battery pack 20 becomes larger than necessary.

In addition, since the unidirectional DC/DC converter 30 is connected only to the fuel cell 10 side, charging/discharging speed management of the battery pack 20 connected in parallel to the DC/DC converter 30 cannot be managed. 20) causing overcharge and overdischarge. Due to this, the lifespan of the battery pack 20 may be shortened.

Republic of Korea Patent Publication No. 10-0708273 (2007.04.10)

The embodiment is intended to overcome the above-described problem, and hybrid power that performs power distribution between a fuel cell and a battery capable of stably operating a fuel cell even when an external load changes rapidly and preventing overcharging and overdischarging of the battery pack It relates to a system, an apparatus and a control method.

The technical problems to be achieved by the embodiment are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those of ordinary skill in the art from the description of the embodiment.

A hybrid power system for distributing power between a fuel cell and a battery according to an embodiment is a first first that is connected to the fuel cell, converts the DC voltage generated in the fuel cell according to a first switching control signal, and provides the converted DC voltage to the DC link. DC/DC converter; A second DC/DC converter that is connected to the battery and converts the voltage of the DC link and provides it to the battery according to second and third switching control signals, or converts the DC voltage of the battery and provides it to the DC link ; and a characteristic of an external load connected to the DC link is analyzed to determine a load sharing ratio between the fuel cell and the battery, and the output current of the fuel cell and the voltage of the DC link are determined according to the load sharing ratio. and a controller outputting the first to third switching control signals for feedback control.

Here, the fuel cell includes at least one of a fuel cell, a solar cell, and a wind power cell. The hybrid power system may be an integrated system in which the fuel cell and the battery are configured as one system, or a system in which two or more independent systems are connected. a photovoltaic cell-battery, a fuel cell-wind cell-battery, and a fuel cell-solar cell-wind cell-battery.

Here, the battery includes any one of a lithium-ion battery, a lead acid battery, and a lithium iron phosphate battery.

Here, the first DC/DC converter includes a boost converter that boosts the DC voltage of the fuel cell.

Here, the second DC/DC converter is a bidirectional converter operating in either a boost mode for boosting the DC voltage of the battery and discharging it to the DC link, and a buck mode for charging the battery by stepping down the DC link voltage. includes

Here, the controller determines the fuel cell load shared by the fuel cell as a constant size, and determines the battery load shared by the battery as a size corresponding to a difference between the external load and the fuel cell load.

Here, the controller sets the target current value of the fuel cell according to the fuel cell load, and generates the first switching control signal so that the output current of the fuel cell tracks the target current value.

Here, the controller sets the target current value to different levels according to the charging rate of the battery.

Here, the controller sets the target voltage value of the DC link according to the battery load, and generates the second and third switching control signals so that the voltage of the DC link follows the target voltage value.

Here, the controller determines the charging and discharging rates according to the charging rate of the battery, and sets the target voltage value to a certain level higher or smaller than the open circuit voltage of the battery according to the determined charging and discharging rates.

Here, the controller determines the charging and discharging rates such that the charging rate of the battery is maintained in a range between a preset minimum charging rate and a maximum charging rate.

Here, the controller includes: a current measuring unit for monitoring the output current of the fuel cell; a voltage measuring unit monitoring the voltage of the DC link; a target setting unit configured to set a target current value and a target voltage value according to a fuel cell load shared by the fuel cell, a battery load shared by the battery, and a charging rate of the battery; a current controller controlling the first switching control signal so that the output current of the fuel cell follows the target current value; and a voltage controller controlling the second and third switching control signals so that the voltage of the DC link follows the target voltage value.

Here, the current controller calculates a first duty ratio by proportionally integrating a deviation between the target current value and the output current of the fuel cell, and generates the first switching control signal according to the first duty ratio.

Here, the voltage controller calculates a second duty ratio by proportionally integrating a deviation between the target voltage value and the voltage value of the DC link, and generates the second and third switching control signals according to the second duty ratio do.

According to an embodiment, there is provided a hybrid power device for distributing power between a fuel cell and a battery, comprising: a current measuring unit monitoring an output current of the fuel cell; a voltage measuring unit for monitoring the voltage of the DC link; a target setting unit for determining a load sharing ratio between the fuel cell and the battery by analyzing characteristics according to a requirement condition of an external load connected to the DC link, and setting a target current value and a target voltage value according to the load sharing ratio; a current controller for generating a first switching control signal so that the output current of the fuel cell tracks the target current value and outputting it to a first DC/DC converter connected between the fuel cell and the DC link; and a voltage controller for generating second and third switching control signals so that the voltage of the DC link follows the target voltage value and outputting the second and third switching control signals to a second DC/DC converter connected between the battery and the DC link.

Here, the first DC/DC converter includes a boost converter that boosts the DC voltage of the fuel cell.

Here, the second DC/DC converter is a bidirectional converter operating in either a boost mode for boosting the DC voltage of the battery and discharging it to the DC link, and a buck mode for charging the battery by stepping down the DC link voltage. includes

Here, the target setting unit fixes the fuel cell load shared by the fuel cell to a constant size, and determines the battery load shared by the battery as a size corresponding to a difference between the external load and the fuel cell load.

Here, the target setting unit sets the target current value to different levels according to the charging rate of the battery.

Here, the target setting unit determines the charging and discharging rates according to the charging rate of the battery, and sets the target voltage value to be higher or lower than the open circuit voltage of the battery by a certain level according to the determined charging and discharging rates.

Here, the target setting unit determines the charging and discharging rates such that the charging rate of the battery is maintained in a range between a preset minimum charging rate and a maximum charging rate.

Here, the current controller calculates a first duty ratio by proportionally integrating a deviation between the target current value and the output current of the fuel cell, and generates the first switching control signal according to the first duty ratio.

Here, the voltage controller calculates a second duty ratio by proportionally integrating a deviation between the target voltage value and the voltage value of the DC link, and generates the second and third switching control signals according to the second duty ratio do.

According to an exemplary embodiment, a control method of a hybrid power device performing power distribution between a fuel cell and a battery includes: monitoring an output current of the fuel cell by a current measuring unit; monitoring the voltage of the DC link by a voltage measuring unit; determining a load sharing ratio between the fuel cell and the battery by analyzing a characteristic according to a requirement condition of an external load connected to the DC link by a target setting unit, and setting a target current value and a target voltage value according to the load sharing ratio ; generating, by a current controller, a first switching control signal so that the output current of the fuel cell tracks the target current value and outputting it to a first DC/DC converter connected between the fuel cell and the DC link; calculating a battery charge rate by integrating the charge/discharge current of the battery in real time; and generating, by a voltage controller, second and third switching control signals so that the voltage of the DC link follows the target voltage value and outputting them to a second DC/DC converter connected between the battery and the DC link. .

Here, the first DC/DC converter includes a boost converter that boosts the DC voltage of the fuel cell.

Here, the second DC/DC converter is a bidirectional converter operating in either a boost mode for boosting the DC voltage of the battery and discharging it to the DC link, and a buck mode for charging the battery by stepping down the DC link voltage. includes

Here, the determining of the load sharing ratio between the fuel cell and the battery may include: determining a fuel cell load shared by the fuel cell to have a constant size; and determining a battery load shared by the battery as a size corresponding to a difference between the external load and the fuel cell load.

Here, the target current value is set to different levels according to the charging rate of the battery.

Here, the target voltage value is set to be higher or lower than the open circuit voltage of the battery by a certain level according to the charging and discharging rates determined based on the charging rate of the battery.

Here, the charging and discharging rates are determined such that the charging rate of the battery is maintained in a range between a preset minimum charging rate and a maximum charging rate.

Here, the generating of the first switching control signal may include: calculating a first duty ratio by proportionally integrating a deviation between the target current value and an output current of the fuel cell; and outputting the first switching control signal according to the first duty ratio.

Here, the generating of the second and third switching control signals may include: calculating a second duty ratio by proportionally integrating a deviation between the target voltage value and the voltage value of the DC link; and outputting the second and third switching control signals according to the second duty ratio.

A hybrid power system, apparatus, and control method for performing power distribution between a fuel cell and a battery according to an embodiment maintain a constant output of a fuel cell using a current control method, and use a DC link voltage control method to charge a battery charge rate constant, and by preventing overcharging and overdischarging of the battery, it is possible to secure the stability of the entire hybrid power system and improve the lifespan.

In addition, in the embodiment, the lifespan of the fuel cell is improved by preventing the output of the fuel cell from fluctuating in response to a sudden load change, and at the same time, the power quality of the hybrid power system is improved by supplying a constant voltage to the secondary power system. can

1 is a diagram illustrating a fuel cell-battery hybrid power system.
2 is a diagram illustrating a hybrid power system for performing power distribution between a fuel cell and a battery according to an embodiment of the present invention.
FIG. 3 is a diagram illustrating control models of the fuel cell, the battery, and first and second DC/DC converters shown in FIG. 2 .
FIG. 4 is a diagram illustrating the controller illustrated in FIG. 2 , and is a diagram illustrating a controller designed based on the control model illustrated in FIG. 4 .
5 is a diagram illustrating a machine state control block diagram according to an embodiment of the present invention.
6 is a diagram illustrating a driving test result of a hybrid power system according to an embodiment of the present invention.
7 is a diagram illustrating experimental results performed to evaluate the accuracy of a hybrid power system according to an embodiment of the present invention.

Hereinafter, the embodiments disclosed in the present specification will be described in detail with reference to the accompanying drawings, but identical or similar components are given the same and similar reference numerals, and overlapping descriptions thereof will be omitted. The suffixes "module" and "part" for components used in the following description are given or mixed in consideration of only the ease of writing the specification, and do not have distinct meanings or roles by themselves. In addition, in describing the embodiments disclosed in the present specification, if it is determined that detailed descriptions of related known technologies may obscure the gist of the embodiments disclosed in this specification, the detailed description thereof will be omitted. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and the technical spirit disclosed in the present specification is not limited by the accompanying drawings, and all changes included in the spirit and scope of the embodiments; It should be understood to include equivalents and substitutes.

Terms including an ordinal number such as 1st, 2nd, etc. may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

When an element is referred to as being “connected” or “connected” to another element, it is understood that it may be directly connected or connected to the other element, but other elements may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle.

The singular expression includes the plural expression unless the context clearly dictates otherwise.

In the present application, terms such as “comprises” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

2 is a diagram illustrating a hybrid power system for performing power distribution between a fuel cell and a battery according to an embodiment of the present invention.

Referring to FIG. 2 , a hybrid power system 2 according to an embodiment of the present invention includes a fuel cell 100 , a battery pack 200 , a first DC/DC converter 300 , and a second DC/DC converter 400 . ), a controller 500 , an inverter 600 and an external load 700 . The fuel cell 100 is a main power supply and generates a DC voltage of a certain size.

The fuel cell 100 may receive fuel from a fuel storage unit (not shown) and receive an oxidizer from an oxidizer supply unit (not shown) to produce electrical energy. Here, the fuel refers to hydrocarbon-based fuels in a liquid or gaseous state, such as methanol, ethanol, natural gas, LPG, and the like. And, as the oxidizing agent reacting with hydrogen, oxygen gas stored in a separate storage means may be used or air may be used.

The fuel cell 100 may generate electric energy according to various methods. For example, a polymer electrolyte fuel cell method in which a fuel is reformed to generate hydrogen, and hydrogen and oxygen are electrochemically reacted to generate electric energy may be used. The embodiment of the present invention is not limited thereto, and the fuel cell 100 uses a direct oxidation fuel cell method that generates electric energy through a direct reaction between liquid or gas fuel and oxygen in a unit cell. may be The fuel cell 100 may include an air-cooled or water-cooled cooling device (not shown).

Here, the fuel cell 100 may include at least one of a (hydrogen) fuel cell, a solar cell, and a wind power cell. The hybrid power system 2 according to the embodiment of the present invention is an integrated system in which the fuel cell 100 and the battery pack 200 are configured as one system, or is a system in which two or more independent systems are connected, for example, a fuel cell-battery; and at least one of a solar cell-battery, a wind cell-battery, a fuel cell-solar cell-battery, a fuel cell-wind cell-battery, and a fuel cell-solar cell-wind cell-battery.

The battery pack 200 includes a battery 210 and a Battery Management System (BMS) 220 as an auxiliary power source. The battery 210 receives the voltage of the DC link through the second DC/DC converter 400 to be charged, or discharges the voltage to the DC link. Here, the battery 210 may include a lithium-ion battery, a lead-acid battery, a lithium iron phosphate battery, and the like. The battery management system 220 monitors the current, voltage, temperature, and state of charge (SOC) of the battery 210 , and manages the overall state of the battery 210 .

The first DC/DC converter 300 is connected to the fuel cell 100 and is controlled by the controller 500 to convert the DC voltage output from the fuel cell 100 into a DC voltage of another level and provide it to the DC link. do. That is, the first DC/DC converter 300 serves to adjust the voltage on the DC link side. Here, the first DC/DC converter 300 may include a boost converter that boosts and outputs the output voltage of the fuel cell 100 .

The second DC/DC converter 400 is connected to the battery pack 200 and is controlled by the controller 500 to convert the DC voltage provided to the DC link into a DC voltage of another level and provide it to the battery 210, The DC voltage of the battery 210 is converted into a DC voltage of another level and provided to the DC link. That is, the second DC/DC converter 400 is responsible for charging and discharging the battery 210 and also serves to adjust the voltage on the DC link side.

Here, the second DC/DC converter 400 includes a bidirectional converter operating as a buck-boost converter. The second DC/DC converter 400 may discharge the DC voltage of the battery 210 to the DC link in the boost mode, and charge the battery 210 with the voltage of the DC link in the buck mode.

The controller 500 determines a load sharing ratio between the fuel cell 100 and the battery 210 by analyzing characteristics according to the requirements of the external load 700 , and the fuel cell 100 shares the load according to the determined load sharing ratio. The fuel cell load and the battery load shared by the battery 210 are separated and controlled. The controller 500 may determine the fuel cell load as a constant size, and determine the battery load as a size corresponding to the difference between the external load 700 and the fuel cell load.

In other words, the controller 500 separates and controls the power shared by the fuel cell 100 and the battery 210 , but uniformly controls the power shared by the fuel cell 100 , and Power corresponding to the difference between the required power and the power shared by the fuel cell 100 is controlled to be shared by the battery 210 .

That is, when the power required of the external load 700 is less than the power shared by the fuel cell 100 while maintaining the power shared by the fuel cell 100 constant, the controller 500 The surplus power is charged to the battery 210 , and when the required power of the external load 700 is greater than the power shared by the fuel cell 100 , the additionally required power is discharged from the battery 210 . Accordingly, even if the required power of the external load 700 changes frequently, the output power of the fuel cell 100 can be constantly maintained, so that the fuel cell 100 can be operated stably.

Specifically, the controller 500 feedback-controls the output current of the fuel cell 100 and the DC link voltage of the battery 210 according to the load sharing ratio between the fuel cell 100 and the battery 210 . To this end, the controller 500 sets a target current value of the fuel cell 100 and a target voltage value for the DC link of the battery 210 according to the load sharing ratio. _{The controller 500 controls the first DC/DC converter 300 so that the output current I FC} of the fuel cell 100 tracks the target current value, and the voltage (V _DC ) of the DC link of the battery 210 . The second DC/DC converter 400 is controlled to follow the target voltage value.

The controller 500 sets the target current value to a constant current level. Here, the target current value may be set to different levels according to the charging rate of the battery 210 . To this end, the controller 500 receives the charging rate of the battery 210 as feedback from the battery management system 220 , and sets the target current value to current values (high current, medium current) of different levels corresponding to the charging rate range of the battery 210 . and low current).

Here, the range of the charging rate may be determined according to the operating environment of the hybrid power system. For example, the controller 500 sets the target current value to the intermediate current value when the charging rate of the battery 210 is in the range of 40 to 70%, and sets the target current value to the high current value when the charging rate of the battery 210 is less than 30%. can be set to When the charge rate of the battery 210 is in an overcharge state of 90% or more, the controller 500 may set the target current value to 0, that is, stop the driving of the fuel cell 100 .

The controller 500 may determine the charging and discharging rates according to the charging rate of the battery 210 , and may set the target voltage value to be higher or lower than the open voltage of the battery 210 by a certain level according to the charging and discharging rates.

In general, the DC link voltage of the battery 210 may vary according to a charge rate of the battery 210 . Since the efficiency of the hybrid power system 2 may be reduced when the DC link voltage is changed, the controller 500 according to the embodiment of the present invention maintains the DC link voltage constant regardless of the charge/discharge state of the battery 210 . You can set the target voltage value so that

The charging and discharging rates of the battery 210 are determined by the difference between the DC link voltage and the open voltage of the battery 210 . For example, when the DC link voltage is much greater than the open voltage of the battery 210 , the battery 210 is rapidly charged, and when the DC link voltage is greater than the open voltage of the battery 210 , the battery 210 is slowly charged. When the DC link voltage is less than the open-circuit voltage of the battery 210, the battery 210 is slowly discharged, and when the DC link voltage is much smaller than the open-circuit voltage of the battery 210, the battery 210 is rapidly discharged.

The controller 500 may determine the charging and discharging rates such that the charging rate of the battery 210 maintains a range between a preset minimum charging rate and a maximum charging rate. For example, when the charging rate of the battery 210 is lowered below the minimum charging rate, the controller 500 sets the target voltage value to be relatively larger than the open voltage of the battery 210 to rapidly charge the battery 210 , and the battery 210 . ) when the charging rate is higher than the maximum charging rate, the controller 500 may set the target voltage value to be relatively smaller than the open voltage of the battery 210 to rapidly discharge the battery 210 . Due to this, the charging rate of the battery 210 can be maintained in a range between the preset minimum charging rate and the maximum charging rate, and being overcharged or overdischarged at the same time can be prevented.

The inverter 600 is connected between the DC link and the external load 700 , converts the DC voltage applied from the DC link into an AC voltage, and outputs the converted DC voltage to the external load 700 . Here, the inverter 600 may convert the DC voltage from the fuel cell 100 and/or the battery pack 200 into a commercial AC voltage used at home or in a building and output it.

FIG. 3 is a diagram illustrating control models of the fuel cell, the battery, and first and second DC/DC converters shown in FIG. 2 . That is, FIG. 3 is a diagram illustrating a distribution controller model for controlling a power distribution method between the fuel cell 100 and the battery 210 .

Referring to FIG. 3 , the fuel cell 100 includes a DC voltage 110 and an internal resistance 120 . The fuel cell 100 outputs a voltage Vfc in which the DC voltage 110 is lowered by the internal resistance 120 . Here, the DC voltage 110 is a voltage produced by the fuel cell 100 and has a Nernst voltage value Enernst.

The internal resistor 120 includes first to third variable resistors 122 , 124 , 126 and a variable capacitor 128 . The internal resistance 120 and the DC voltage 110 are connected in series between the _{fuel cell output voltage V FC application terminals.} The first variable resistor 122 includes one end connected to the output terminal N1 and the other end connected to one end of the second variable resistor 122 , and a resistance value Rconc corresponding to a saturation voltage drop of the fuel cell 100 . has

The second variable resistor 124 includes the other end connected to one end of the third variable resistor 126 , and has a resistance value Rohm corresponding to an ohmic voltage drop of the fuel cell 100 . The third variable resistor 126 includes the other end connected to the DC voltage 110 , and has a resistance value Ract corresponding to a drop in the activation voltage of the fuel cell 100 . The variable capacitor 128 is connected to both ends of the third variable resistor 126 , and has a capacitor value Cact corresponding to a drop in the activation voltage of the fuel cell 100 .

The battery pack 200 includes a battery 210 and a battery management system (BMS) 220 . The battery 210 includes a variable voltage 212 that is charged and discharged and an internal resistor 214 . The variable voltage 212 is a voltage controlled by the battery management system 220 to be charged and discharged. The internal resistance 214 has the internal resistance value R of the battery 210 .

The battery management system 220 monitors the battery charge/discharge capacity (Q), the battery current (i), and the target battery current (i*). Here, the battery charge/discharge capacity (Q) is a value obtained by integrating the battery current (i) for a predetermined time (t) through the integrator 222 , and the target battery current (i*) is obtained through the low-pass filter 224 . It is a set value.

The first DC/DC converter 300 includes an inductor 310 , diodes D and 320 , switches S ₁ , 330 , and a capacitor 340 . The inductor 310 includes one _{end connected to the output voltage V FC} applying terminal of the fuel cell 100 and the other end connected to the anode terminal of the diode 320 . The diode 320 includes an anode terminal connected to the other end of the inductor 310 and a cathode terminal connected to the DC link voltage (V _DC ) application terminal.

The switch 330 is connected between the other end of the inductor 310 and an output voltage (V _FC ) applying end of the fuel cell 100 , and is turned on/off by the first switching control signal u1 . . The switch 330 is a semiconductor switch and may include a metal oxide silicon field effect transistor (MOSFET). The capacitor 340 includes one end and the other end respectively connected between the DC link voltage (V _{DC ) application terminals.}

The first DC/DC converter 300 having the above configuration is modeled according to Equation 1 below.

는 연료전지(100)의 전류 변화량,

는 연료전지(100)의 전압 변화량, V_DC는 DC 링크 전압, L₁은 인덕터(310)의 인덕턴스 값, C₁은 콘덴서(340)의 값, r_FCS 는 제1 DC/DC 컨버터(300)의 저항값, u₁은 제1 스위칭 제어 신호로서, 듀티 비(duty ratio)를 갖는 온(on) 신호 및 오프(off) 신호를 포함한다. Here, I _FC is the current _{of the fuel cell 100 , V FC} is the voltage of the fuel cell 100 ,

is the amount of change in current of the fuel cell 100,

is the voltage change amount of the fuel cell 100, V _DC is the DC link voltage, L ₁ is the inductance value of the inductor 310, C ₁ is the value of the capacitor 340, r _FCS is the first DC/DC converter 300 A resistance value of u ₁ is a first switching control signal, and includes an on signal and an off signal having a duty ratio.

The second DC/DC converter 400 includes a first capacitor 410 , a second capacitor 420 , an inductor 430 , a first switch S ₂ , 440 and a second switch S ₃ , 450 . do. Here, the first capacitor 410 includes one end and the other end respectively connected between the _{DC link voltage (V DC} ) applying terminals, and the second capacitor 420 has one end respectively connected between the _{battery voltage (V BATT ) applying terminals.} and the other end. The inductor 430 includes one end connected to one end of the second capacitor 420 and the other end connected to the second switch 450 , and has an inductance value L2 .

The first switch 440 is connected between the other end of the inductor 430 and the other end of the second capacitor 420 , and is turned on/off by the second switching control signal u2 . Here, the first switch 440 is a semiconductor switch and may include a MOSFET.

The second switch 450 is connected between the other end of the inductor 430 and one end of the second capacitor 420 , and is turned on/off by the third switching control signal u3 . Here, the second switch 450 is a semiconductor switch and may include a MOSFET.

Here, the third switching control signal u3 is an inverted signal of the second switching control signal u2. Accordingly, the first and second switches 440 and 450 operate complementary to each other, the first switch 440 operates as a switch for discharging the battery 210, and the second switch 450 operates the battery ( 210) as a switch for charging.

The second DC/DC converter 400 having the above configuration is modeled as in [Equation 2] below when in a boost mode, which is a step-up mode.

는 인덕터(430)에 흐르는 전류의 변화량,

는 DC 링크 전압(V_DC)의 변화량, L₂는 인덕터(430)의 인덕턴스 값, C₂는 제1 콘덴서(410)의 값, r_LIB,disc는 배터리(210)의 방전시 제2 DC/DC 컨버터(400)의 저항값, u₂는 제2 스위칭 제어 신호로서, 듀티 비를 갖는 온(on) 신호 및 오프(off) 신호를 포함한다. Here, I _L2 is the current flowing in the inductor 430, V _DC is the DC link voltage, V _BATT is the voltage of the battery 210,

is the amount of change in the current flowing through the inductor 430,

is the amount of change in the DC link voltage (V _{DC ), L 2} is the inductance value of the inductor 430 , C ₂ is the value of the first capacitor 410 , r _LIB,disc is the second DC/ The resistance value of the DC converter 400, u _{2 ,} is a second switching control signal, and includes an on signal and an off signal having a duty ratio.

When the second DC/DC converter 400 is in the buck mode, which is the step-down mode, it is modeled as in [Equation 3] below.

는 인덕터(430)에 흐르는 전류의 변화량, C₃는 제2 콘덴서(420)의 값, r_LIB,charg 는 배터리(210)의 충전 시 제2 DC/DC 컨버터(400)의 저항값을 나타낸다. u₃는 제3 스위칭 제어 신호로서, 듀티 비를 갖는 온(on) 신호 및 오프(off) 신호를 포함한다.Here, I _L2 is the current flowing in the inductor 430, V _DC is the DC link voltage, V _BATT is the voltage of the battery 210,

is the change amount of the current flowing through the inductor 430 , C ₃ is the value of the second capacitor 420 , and r _LIB,charg is the resistance value of the second DC/DC converter 400 when the battery 210 is charged. u ₃ is a third switching control signal, and includes an on signal and an off signal having a duty ratio.

FIG. 4 is a diagram illustrating the controller illustrated in FIG. 2 , and is a diagram illustrating a controller designed based on the control model illustrated in FIG. 3 .

Referring to FIG. 4 , since the power required by the external load 700 is not constant and varies with time, the power shared between the fuel cell 100 and the battery 210 should be optimally distributed. In particular, when a high load (peak power) is frequently required from the external load 700 , since the fuel cell 100 has to share a high power momentarily, it acts as a stress on the fuel cell 100 . shorten the lifespan

Therefore, even when a high load is required from the external load 700 , the voltage of the DC link must be kept constant as a method for increasing the overall efficiency of the hybrid power system 2 while constantly controlling the power shared by the fuel cell 100 . . Accordingly, the controller 500 according to the embodiment of the present invention simultaneously controls _{the output current I FC} and the DC link voltage V _{DC of the fuel cell 100 .} That is, the controller 500 maintains the output constant by using the current control method on the fuel cell 100 side, and constant the charge rate (SOC) of the battery 210 by using the DC link voltage control method on the battery 210 side. to prevent overcharging and overdischarging at the same time.

To this end, the controller 500 includes a current measuring unit 510 , a voltage measuring unit 520 , a current controlling unit 530 , a voltage controlling unit 540 , and a target setting unit 550 . Here, the current measuring unit 510 monitors _{the output current I FC of the fuel cell 100 .} The voltage measuring unit 520 _{monitors the voltage (V DC} ) of the DC link.

Current controller 530 is the output current (I _FC) the target current value (I _FC of the fuel cell output current (I _FC), the feedback received, the fuel cell 100 of the system 100 from a current measuring unit _{(510), ref} ) to generate the first switching control signal u1. _{Here, the current controller 530 is a current proportional integral controller that proportionally and integrally controls the output current I FC} of the fuel cell 100 , and includes a subtractor 531 , a proportional calculator 533 , an integral calculator 535 , and Laplace. It includes a converter 537 and an adder 539 .

The subtractor 531 calculates a deviation e between the target current value I _{FC, ref} and the output current value of the fuel cell 100 . The proportional operator 533 performs a proportional operation on the calculated deviation e, and the integral operator 535 performs an integral operation on the calculated deviation e. The Laplace transformer 537 performs a Laplace transform on the result of the integral operation. Here, S represents the Laplace transform value used in the control logic.

The adder 539 generates the duty ratio control signal u1 by adding the proportional operation result value and the Laplace-transformed integration operation result value. Here, a value obtained by adding the result value calculated by the proportional operation and the result value obtained by the Laplace transform integration operation represents a duty ratio value, and the first switching control signal u1 may be generated as a PWM signal having a duty ratio value.

The voltage control unit 540 receives the DC link voltage V _DC as feedback from the voltage measurement unit 520 , and the second and third switching control signals u2 so that the DC link voltage follows the target voltage values V _{DC and REF .} , u3). _{Here, the voltage controller 540 is a voltage proportional integral controller that proportionally and integrally controls the DC voltage (V DC} ) for the battery 210 , and includes a subtractor 541 , a proportional operator 543 , an integral operator 545 , and Laplace. It includes a converter 547 and an adder 549 .

The subtractor 541 calculates a deviation e between the target voltage values (V _{DC, REF} ) and the DC link voltage (V _{DC ) values.} The proportional operator 543 performs a proportional operation on the calculated deviation e, and the integral operator 545 performs an integral operation on the calculated deviation e. The Laplace transform 547 performs a Laplace transform on the result of the integral operation. Here, S represents the Laplace transform value used in the control logic.

The adder 549 outputs the second switching control signal u2 by adding the proportional operation result value and the Laplace-transformed integration operation result value. Here, a value obtained by adding the result value calculated by the proportional operation and the result value obtained by the integration operation may represent a duty ratio, and the second switching control signal u2 may be generated as a PWM signal having a duty ratio. And, the voltage control unit 540 further includes an inverter (not shown) for inverting the output of the adder 549 to invert the second switching control signal u2 to generate the third switching control signal u3 . can

Specifically, each of the current controller 530 and the voltage controller 540 may generate the first and second switching control signals u1 and u2 using a control method as in Equation 4 below.

Here, I _{FC, ref} is a target current value of the fuel cell 100 , V _{DC, ref} is a DC link target voltage value, K _P1 is a proportional control constant used for current control of the fuel cell 100 , and K _P2 is an integral control constant used for current control of the fuel cell 100 . K _I1 is a proportional control constant used for DC link voltage control, and K _I2 is an integral control constant used for DC link voltage control.

The target setting unit 550 determines a load sharing ratio between the fuel cell 100 and the battery 210 by analyzing characteristics according to the requirements of the external load 700 , and the determined load sharing ratio and the charging rate of the battery 210 . Accordingly, target current values I _{FC, ref of the fuel cell 100 and target voltage values V DC, REF} for the DC link of the battery 210 are set.

Here, the target setting unit 550 sets the target current value (I _{FC, ref} ) to a constant level according to the load sharing ratio, but the level of the target current value (I _{FC, ref} ) according to the charge rate of the battery 210 . can be set to different levels (high current, medium current and low current). For example, if the charge rate of the battery 210 is in the range of 40 to 70%, the target setting unit 550 sets the target current value I _{FC, ref} as an intermediate current value, and the charge rate of the battery 210 is 30%. If less than, the target current value (I _{FC, ref} ) may be set to a high current value. When the charge rate of the battery 210 is in an overcharge state of 90% or more, the controller 500 may set the target current values I _{FC, ref} to 0, that is, stop the driving of the fuel cell 100 .

The target setting unit 550 sets the target voltage values (V _{DC, REF} ) to a predetermined level according to the load sharing ratio, but determines the charging and discharging rates according to the charging rate of the battery 210 to determine the target voltage value (V _{DC, REF} ) can be set to different levels. Here, the target setting unit 550 may determine the charging and discharging rates such that the charging rate of the battery 210 is maintained within a range between a preset minimum charging rate and a maximum charging rate.

_{The target setting unit 550 may set the level of the target voltage values V DC and REF} to be higher or lower than the open voltage of the battery 210 by a predetermined level according to the determined charging and discharging rates. For example, when the charging rate of the battery 210 decreases below the minimum charging rate, the target setting unit 550 sets the target voltage values V _{DC and REF} to be relatively larger than the open circuit voltage of the battery 210 . is rapidly charged, and when the charging rate of the battery 210 increases above the maximum charging rate, the target setting unit 550 sets the target voltage values V _{DC, REF} to be relatively smaller than the open circuit voltage of the battery 210 to set the battery ( 210) can be rapidly discharged.

5 is a diagram illustrating a machine state control block diagram according to an embodiment of the present invention. That is, FIG. 5 is a machine state control block diagram used to control load distribution of the hybrid power system.

5, the controller 500 first detects the requirement of the external load 700 (step S110). The controller 500 determines a load sharing ratio between the fuel cell 100 and the battery 210 by analyzing characteristics according to the requirements of the external load 700 . _{The controller 500 sets the target current values I FC and ref} and the target voltage values V _{DC and REF} according to the load sharing ratio between the fuel cell 100 and the battery 210 (step S120 ).

In this case, the controller 500 may set the target current values I _{FC and ref} and the target voltage values V _{DC and REF} according to the charging rate of the battery 210 . _{For example, the controller 500 may set the target current values I FC and ref} to any one of a high current, a medium current, and a low current according to the charge rate of the battery 210 by using the fuzzy control method.

And, the controller 500 determines the charging and discharging rates according to the charging rate of the battery 210, and a predetermined level greater or less than the open circuit voltage of the battery 210 according to the charging and discharging rates target voltage values V _{DC, REF} ) can be set.

Next, the controller 500 _{measures the output current I FC} and the DC link voltage V _{DC of the} fuel cell 100 (step S130 ), and the output current I _FC and DC of the fuel cell 100 . The first and second DC/DC converters 300 and 400 are controlled so that the link voltage V _{DC follows} the target current values I _{FC, ref} and the target voltage values V _{DC and REF , respectively (step S140 ).} ).

Then, the controller 500 determines whether the operation stop of the hybrid power system 2 is determined (step S150). For example, when an external operation stop button (not shown) is pressed, the controller 500 determines that operation stop has been determined and stops the hybrid power system 2 .

The controller 500 repeats from step S110 if the operation is not stopped. That is, the controller 500 is the output current (I _FC of the fuel cell 100, the output current (I _FC) and the battery (210), DC link voltage (V _DC) measured in real time, and fuel cell 100 of the _{) and the voltage (V DC} ) of the DC link of the battery 210 to satisfy the set target current values (I _{FC, ref} ) and the target voltage values (V _{DC, REF} ), the first and second DC/DC converters 300 , 400) (step S160).

6 is a diagram illustrating a driving test result of a hybrid power system according to an embodiment of the present invention.

6, (a) and (c) show the simulation results of the hybrid power system when the external load is constant at 6A. It can be seen that the DC link target voltage value of 24V is followed within about 0.2 seconds, and the fuel It can be seen that the battery outputs a constant voltage of 15V within about 0.4 seconds.

(b) and (d) hold the external load at 6A for 0~5 seconds, reduce the external load constantly for 5~7 seconds, and then keep the external load at 4A for 7~9.5 seconds, and then 9.5~12 It shows the simulation result of the hybrid power system when maintained at 5A until the second. It can be seen that even when the external load is increased, the DC link target voltage value of 24V is instantaneously followed, and the fuel cell also outputs a constant voltage of 15V. .

Accordingly, the hybrid power system according to an embodiment of the present invention can improve the lifespan of the fuel cell by constantly maintaining the power output from the fuel cell even when the power demand of an external load changes. In addition, by making the DC link voltage constant, power quality can be improved, and by changing the constant DC link voltage at the same time, overcharging and overdischarging of the battery can be prevented.

7 is a diagram illustrating experimental results performed to evaluate the accuracy of a hybrid power system according to an embodiment of the present invention. 7 is a result of an experiment using a 100W fuel cell and a 2400mAh lithium-ion battery.

In FIG. 7, (a) is an oscilloscope observation result for a case in which the external load is increased to 6A under a constant voltage condition. Here, the yellow line (channel 1) is the DC link voltage, the light blue line (channel 2) is the battery voltage, and the green line (channel 3) is the fuel cell voltage. It can be seen that the DC link voltage is maintained constant after being changed gently, and the fuel cell voltage is changed abruptly and then returns to the state before the external load is changed and remains constant. And, it can be seen that the battery voltage is reduced.

(b) is the oscilloscope observation result for the case where the external load value is increased at a constant rate under a constant external load condition and then maintained at a constant load value again. Here, it can be seen that the DC link voltage and the fuel cell voltage are kept constant, and the battery voltage is charged and discharged according to an external load requirement.

The hybrid power system 2 according to the embodiment of the present invention described above is an independent power generation device that does not need to be connected to a power grid, and connects the fuel cell 100 and the battery pack 200 in parallel, and the fuel cell 100 . Controls the electric power in charge of , and the battery pack 200 is in charge of electric power corresponding to a difference between the electric power required by the external load 700 and electric power in charge of the fuel cell 100 . Accordingly, even when the power demand of the external load 700 changes frequently, the output of the fuel cell 100 is prevented from being rapidly changed, thereby improving the lifespan of the fuel cell 100 . In addition, by maintaining the DC link voltage to the battery pack 200 constant, the voltage of the DC link is changed according to the charge rate of the battery pack 200 to prevent the efficiency of the hybrid power system 2 from being deteriorated, thereby improving power quality. can be improved

In addition, the fuel cell 100 maintains a constant output of the fuel cell 100 by the current control method, and the battery pack 200 maintains a constant charge rate of the battery pack 200 by controlling the DC link voltage by the voltage control method It is possible to secure the stability of the entire hybrid power system 2 and improve the lifespan by preventing overcharging and overdischarging.

Although the embodiment has been described in detail above, the scope of the embodiment is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the embodiment defined in the claims below are also included in the scope of the embodiment.

Accordingly, the foregoing detailed description should not be construed as limiting in all respects but should be considered as illustrative. The scope of the embodiments should be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the embodiments are included in the scope of the embodiments.

100: fuel cell
200: battery pack
300: first DC/DC converter
400: second DC/DC converter
500: controller
600: inverter
700: external load

Claims (33)

A hybrid power system that distributes power between a fuel cell and a battery, the hybrid power system comprising:
a first DC/DC converter connected to the fuel cell and converting the DC voltage generated by the fuel cell according to a first switching control signal and providing the converted DC voltage to the DC link;
A second DC/DC converter that is connected to the battery and converts the voltage of the DC link and provides it to the battery according to second and third switching control signals, or converts the DC voltage of the battery and provides it to the DC link ; and
A load sharing ratio between the fuel cell and the battery is determined by analyzing a characteristic according to a requirement of an external load connected to the DC link, and the output current of the fuel cell and the voltage of the DC link are fed back according to the load sharing ratio A controller outputting the first to third switching control signals to control
A hybrid power system comprising a. According to claim 1,
The fuel cell is at least one of a fuel cell, a solar cell, and a wind cell
A hybrid power system comprising: The method of claim 2, wherein the hybrid power system comprises:
The fuel cell and the battery are integrated as one system, or two or more independent systems are connected,
At least one of a fuel cell-battery, solar cell-battery, wind cell-battery, fuel cell-solar cell-battery, fuel cell-wind cell-battery, fuel cell-solar cell-wind cell-battery which is a hybrid power system. According to claim 1,
The battery is a hybrid power system including any one of a lithium-ion battery, a lead acid battery, and a lithium iron phosphate battery. According to claim 1,
The first DC/DC converter includes a boost converter that boosts the DC voltage of the fuel cell. According to claim 1,
The second DC/DC converter includes a bidirectional converter operating in either a boost mode for boosting the DC voltage of the battery and discharging it to the DC link and a buck mode for charging the battery by stepping down the DC link voltage. , hybrid power systems. According to claim 1,
The controller determines the fuel cell load shared by the fuel cell as a constant size, and determines the battery load shared by the battery as a size corresponding to a difference between the external load and the fuel cell load. 8. The method of claim 7,
and the controller sets a target current value of the fuel cell according to the fuel cell load, and generates the first switching control signal so that an output current of the fuel cell tracks the target current value. 9. The method of claim 8,
and the controller sets the target current value to different levels according to a charge rate of the battery. 8. The method of claim 7,
and the controller sets a target voltage value of the DC link according to the battery load, and generates the second and third switching control signals so that the voltage of the DC link follows the target voltage value. 11. The method of claim 10,
wherein the controller determines charging and discharging rates according to the charging rate of the battery, and sets the target voltage value to a predetermined level higher or smaller than an open circuit voltage of the battery according to the determined charging and discharging rates. 12. The method of claim 11,
and the controller determines the charging and discharging rates such that the charging rate of the battery is maintained in a range between a preset minimum and maximum charging rate. The method of claim 1, wherein the controller is
a current measuring unit monitoring the output current of the fuel cell;
a voltage measuring unit monitoring the voltage of the DC link;
a target setting unit configured to set a target current value and a target voltage value according to a fuel cell load shared by the fuel cell, a battery load shared by the battery, and a charging rate of the battery;
a current controller controlling the first switching control signal so that the output current of the fuel cell follows the target current value; and
a voltage controller for controlling the second and third switching control signals so that the voltage of the DC link follows the target voltage value
A hybrid power system comprising: 14. The method of claim 13,
The current control unit calculates a first duty ratio by proportionally integrating a deviation between the target current value and the output current of the fuel cell, and generates the first switching control signal according to the first duty ratio. 14. The method of claim 13,
The voltage control unit calculates a second duty ratio by proportionally integrating a deviation between the target voltage value and the voltage value of the DC link, and generates the second and third switching control signals according to the second duty ratio. power system. A hybrid power device for distributing power between a fuel cell and a battery, the hybrid power device comprising:
a current measuring unit monitoring the output current of the fuel cell;
a voltage measuring unit for monitoring the voltage of the DC link;
a target setting unit for determining a load sharing ratio between the fuel cell and the battery by analyzing characteristics according to a requirement condition of an external load connected to the DC link, and setting a target current value and a target voltage value according to the load sharing ratio;
a current controller for generating a first switching control signal so that the output current of the fuel cell tracks the target current value and outputting it to a first DC/DC converter connected between the fuel cell and the DC link; and
A voltage controller for generating second and third switching control signals so that the voltage of the DC link follows the target voltage value and outputting the second and third switching control signals to a second DC/DC converter connected between the battery and the DC link
A hybrid power device comprising a. 17. The method of claim 16,
The first DC/DC converter includes a boost converter that boosts the DC voltage of the fuel cell. 17. The method of claim 16,
The second DC/DC converter may include: a boost mode in which the DC voltage of the battery is boosted and discharged to the DC link; and
Bi-directional converter operating in any one of buck mode to charge the battery by stepping down the voltage of the DC link
A hybrid power device comprising: 17. The method of claim 16,
The target setting unit fixes the fuel cell load shared by the fuel cell to a constant size, and determines the battery load shared by the battery to have a size corresponding to a difference between the external load and the fuel cell load. 20. The method of claim 19,
The target setting unit sets the target current value to different levels according to a charging rate of the battery. 20. The method of claim 19,
The target setting unit determines the charging and discharging rates according to the charging rate of the battery, and sets the target voltage value to a certain level greater or smaller than the open circuit voltage of the battery according to the determined charging and discharging rates. 22. The method of claim 21,
The target setting unit determines the charging and discharging rates so that the charging rate of the battery is maintained in a range between a preset minimum charging rate and a maximum charging rate. 17. The method of claim 16,
The current control unit calculates a first duty ratio by proportionally integrating a deviation between the target current value and an output current of the fuel cell, and generates the first switching control signal according to the first duty ratio. 17. The method of claim 16,
The voltage control unit calculates a second duty ratio by proportionally integrating a deviation between the target voltage value and the voltage value of the DC link, and generates the second and third switching control signals according to the second duty ratio. power device. In the control method of a hybrid power device performing power distribution between a fuel cell and a battery,
monitoring an output current of the fuel cell by a current measuring unit;
monitoring the voltage of the DC link by a voltage measuring unit;
determining a load sharing ratio between the fuel cell and the battery by analyzing a characteristic according to a requirement condition of an external load connected to the DC link by a target setting unit, and setting a target current value and a target voltage value according to the load sharing ratio ;
generating, by a current controller, a first switching control signal so that the output current of the fuel cell tracks the target current value and outputting it to a first DC/DC converter connected between the fuel cell and the DC link; and
generating, by a voltage controller, second and third switching control signals so that the voltage of the DC link follows the target voltage value, and outputting the second and third switching control signals to a second DC/DC converter connected between the battery and the DC link
A control method of a hybrid power device comprising a. 26. The method of claim 25,
The first DC/DC converter includes a boost converter that boosts the DC voltage of the fuel cell. 26. The method of claim 25,
The second DC/DC converter includes a bidirectional converter operating in either a boost mode for boosting the DC voltage of the battery and discharging it to the DC link and a buck mode for charging the battery by stepping down the DC link voltage. , a control method of a hybrid power device. 26. The method of claim 25,
The step of determining a load sharing ratio between the fuel cell and the battery includes:
determining a fuel cell load shared by the fuel cell to have a constant size; and
determining the battery load shared by the battery as a size corresponding to a difference between the external load and the fuel cell load;
Including, a control method of a hybrid power device. 26. The method of claim 25,
and the target current value is set to different levels according to a charging rate of the battery. 26. The method of claim 25,
The control method of the hybrid power device, wherein the target voltage value is set to be greater or less than an open circuit voltage of the battery by a certain level according to a charging and discharging rate determined based on a charging rate of the battery. 31. The method of claim 30,
and the charging and discharging rates are determined such that a charging rate of the battery is maintained in a range between a preset minimum charging rate and a maximum charging rate. 26. The method of claim 25,
The step of generating the first switching control signal is
calculating a first duty ratio by proportionally integrating a deviation between the target current value and an output current of the fuel cell; and
outputting the first switching control signal according to the first duty ratio
Including, a control method of a hybrid power device. 26. The method of claim 25,
The generating of the second and third switching control signals comprises:
calculating a second duty ratio by proportionally integrating a deviation between the target voltage value and the voltage value of the DC link;
outputting the second and third switching control signals according to the second duty ratio
Including, a control method of a hybrid power device.

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