CN112436730B - Parameter design method of bidirectional CLLC resonant converter - Google Patents

Parameter design method of bidirectional CLLC resonant converter Download PDF

Info

Publication number
CN112436730B
CN112436730B CN202011200410.2A CN202011200410A CN112436730B CN 112436730 B CN112436730 B CN 112436730B CN 202011200410 A CN202011200410 A CN 202011200410A CN 112436730 B CN112436730 B CN 112436730B
Authority
CN
China
Prior art keywords
resonant converter
bidirectional
cllc resonant
cllc
charging
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202011200410.2A
Other languages
Chinese (zh)
Other versions
CN112436730A (en
Inventor
曲璐
王昕�
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shenzhen Graduate School Harbin Institute of Technology
Original Assignee
Shenzhen Graduate School Harbin Institute of Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shenzhen Graduate School Harbin Institute of Technology filed Critical Shenzhen Graduate School Harbin Institute of Technology
Priority to CN202011200410.2A priority Critical patent/CN112436730B/en
Publication of CN112436730A publication Critical patent/CN112436730A/en
Application granted granted Critical
Publication of CN112436730B publication Critical patent/CN112436730B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/3353—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having at least two simultaneously operating switches on the input side, e.g. "double forward" or "double (switched) flyback" converter
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L53/00—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
    • B60L53/20—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles characterised by converters located in the vehicle
    • B60L53/22—Constructional details or arrangements of charging converters specially adapted for charging electric vehicles
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/30—Circuit design
    • G06F30/36—Circuit design at the analogue level
    • G06F30/373—Design optimisation
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from ac mains by converters
    • H02J7/04—Regulation of charging current or voltage
    • H02J7/06—Regulation of charging current or voltage using discharge tubes or semiconductor devices
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • H02M1/4233—Arrangements for improving power factor of AC input using a bridge converter comprising active switches
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2210/00—Converter types
    • B60L2210/10—DC to DC converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2207/00—Indexing scheme relating to details of circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J2207/20—Charging or discharging characterised by the power electronics converter
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/7072—Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02T90/10—Technologies relating to charging of electric vehicles
    • Y02T90/14—Plug-in electric vehicles

Abstract

The invention discloses a parameter design method of a bidirectional CLLC resonant converter, which comprises the following steps: (1) providing a bidirectional CLLC resonant converter in cascade connection with a PFC module, and selecting an operating frequency range of the bidirectional CLLC resonant converter according to one or more structural characteristics and/or one or more performance characteristics of the bidirectional CLLC resonant converter; (2) when the bidirectional CLLC resonant converter works in a wide range, preliminarily setting the turn ratio of the transformer according to the working point of rated voltage; (3) selecting proper Ln and Qe according to the charge-discharge mode; (4) and (4) optimizing the turns ratio of the transformer, and then performing the operation of the step (3) again until the bidirectional CLLC resonant converter has the required working efficiency. The method provided by the invention can ensure that the bidirectional CLLC resonant converter obtains the optimal charging efficiency in the wide-range operation and has lower realization cost.

Description

Parameter design method of bidirectional CLLC resonant converter
Technical Field
The invention relates to a capacitance-inductance-capacitance (CLLC) bidirectional resonant converter, in particular to a parameter design method of the bidirectional CLLC resonant converter.
Background
Global non-renewable energy is rapidly consumed, and electric vehicles using clean energy instead of burning gasoline are important components for environmental protection. One of the key technologies in the field of electric vehicle applications is an on-board battery charger (OBC) conversion technology for charging and discharging a lithium ion battery. OBCs typically have single phase, three phase charging capabilities of 6.6kW, 11kW, and 22 kW. The high-voltage battery is charged by the energy of the power grid when the OBC operates in the forward direction, and the energy of the high-voltage battery is discharged to an alternating current load or provides power assistance for other electric vehicles when the OBC operates in the reverse direction. Due to the special application background of electric vehicles, OBCs are required to have high power density, low cost, and wide range of output characteristics. The most common internal of existing OBCs is a two-stage structure, namely: PFC (Power Factor Correction) and a high-voltage DC/DC converter are cascaded. The first PFC stage implements power factor correction and generates a stable bus voltage. The second stage DC/DC converts the high voltage bus to a wide range of battery voltages and provides isolation between the AC and DC sides. The DCDC topology for OBC is most competitive with CLLC resonant converters. The schemes that currently exist for applying CLLC topologies to OBCs can be divided into two categories:
the first type is an adjustable dc bus scheme. The variable high-voltage direct-current bus voltage in a wide range is generated by the first-stage PFC, the rear-stage CLLC resonant converter mainly has the minimum working loss at a resonant frequency point, and the efficiency and the power density of the whole machine are improved by using the SiC device. The scheme avoids the complicated parameter design process of CLLC, and the efficiency can be improved by 2% compared with a bus-changing scheme and a bus-fixing scheme. According to the scheme of adjusting the bus in the wide range, due to the adoption of the high-voltage wide-bandgap device, the cost of the whole machine is greatly increased, and the use of the high-voltage bus capacitor has larger volume and cost.
The second scheme is a scheme of not adjusting the bus voltage, the bus voltage output by the PFC is generally stabilized at 400V, and the voltage withstanding specification of a switching tube and a bus capacitor applied by the topology is low. In order to achieve a wide range of battery charging voltages, researchers have proposed a combination of different control strategies, typically frequency modulation, pulse width modulation and phase shift control, to extend the operating range of the resonant converter. These novel control strategies usually have complex control modes depending on the different operating areas, which increases the complexity of the overall system and reduces the reliability of the software, the customized scheme of the topological use interval being detrimental to the power expansion from single phase to three phase.
In summary, the design process of the CLLC converter is complicated and difficult due to the ultra wide battery voltage charging range of the OBC and the multiple resonance parameter coupling characteristics of the CLLC topology. The two schemes respectively utilize a variable bus and a control strategy to realize wide-range charging, but not topology self characteristics, so that the scheme brings a vehicle-mounted charger with high cost, large volume and low competitiveness. Therefore, in order to highlight the advantages of the CLLC resonant converter applied to the vehicle-mounted charger, reasonable parameters need to be designed so that the resonant converter can realize a wide variation range of input and output. However, the conventional CLLC resonance parameter design method is difficult to meet the application of the actual vehicle-mounted charger product.
Disclosure of Invention
The invention mainly aims to provide a parameter design method of a bidirectional CLLC resonant converter, which overcomes the defects in the prior art.
In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:
the embodiment of the invention provides a parameter design method of a bidirectional CLLC resonant converter, which comprises the following steps:
(1) providing a bidirectional CLLC resonant converter in cascade connection with a PFC module, and selecting an operating frequency range of the bidirectional CLLC resonant converter according to one or more structural characteristics and/or one or more performance characteristics of the bidirectional CLLC resonant converter;
(2) when the bidirectional CLLC resonant converter works in a wide range, preliminarily setting the turn ratio of the transformer according to the working point of rated voltage;
(3) selecting proper proportionality coefficients Ln and Qe according to the charge-discharge mode;
(4) and (4) optimizing the turns ratio of the transformer, and then performing the operation of the step (3) again until the bidirectional CLLC resonant converter has the required working efficiency.
In some embodiments, the one or more structural and/or performance characteristics of the bidirectional CLLC resonant converter in step (1) include the size of the magnetic component (corresponding to the size of the transformer), output power, switching losses, EMC conducted radiation requirements.
In some embodiments, the operating frequency of the bidirectional CLLC resonant converter is in the range of 100kHz to 200 kHz.
In some embodiments, in step (3), when the forward and reverse transmission power is at the same level, the capacitance of the secondary capacitor of the bidirectional CLLC resonant converter is 2 times that of the primary capacitor.
In some embodiments, in step (3), appropriate Ln and Qe are determined according to the forward-reverse transmission requirement.
Compared with the prior art, the parameter design method of the bidirectional CLLC resonant converter provided by the invention can enable the resonant converter to obtain the optimal charging efficiency in the wide-range operation, and has lower implementation cost.
Drawings
Fig. 1 is a schematic diagram of a bidirectional vehicle-mounted charger according to an exemplary embodiment of the present invention;
fig. 2 a-2 b are equivalent mathematical models of a bidirectional CLLC resonant converter in charge and discharge modes according to an exemplary embodiment of the present invention;
FIG. 3a is a graph of normalized gain of a bi-directional CLLC resonant converter in a charging mode in an exemplary embodiment of the present invention;
FIG. 3b is a graph of normalized gain of a bi-directional CLLC resonant converter in discharge mode in an exemplary embodiment of the present invention;
FIG. 4 is a flow chart of a method for designing parameters of a bidirectional CLLC resonant converter according to an exemplary embodiment of the present invention;
FIGS. 5 a-5 b illustrate the losses of MOSFETs with different transformer turn ratios in the charging and discharging modes in accordance with an exemplary embodiment of the present invention;
FIG. 6a is a discharge mode gain curve in an exemplary embodiment of the invention;
fig. 6b is a distribution of discharge mode operating points for different transformer turn ratios.
Detailed Description
In view of the defects that the existing parameter design method of the bidirectional CLLC resonant converter is generally applied to bidirectional symmetrical working conditions and is difficult to meet the application of an actual vehicle-mounted charger product, and the like, the inventor of the invention provides the technical scheme of the invention through long-term research and a large amount of practice. The technical solution, its implementation and principles, etc. will be further explained as follows.
The parameter design method of the bidirectional CLLC resonant converter provided by the exemplary embodiment of the invention is mainly applied to the bidirectional vehicle-mounted charger shown in FIG. 1, and the bidirectional vehicle-mounted charger has a two-stage structure, wherein the first stage is an FPC module and comprises a bidirectional AC-DC rectifier and an inverter, and the bidirectional AC-DC rectifier and the inverter can rectify single-phase grid voltage of 85VAC-265VAC into a fixed bus of 400V (namely, provide fixed bus voltage). The charger has a wide range of AC inputs to meet the grid requirements of different countries and regions. The second stage is a bidirectional CLLC resonant converter capable of converting the bus voltage to an ultra wide battery voltage of 200V to 480V.
More specifically, where the PFC of the first stage operates in CCM mode, where S1 and S3 employ SiC diodes with IGBT operating frequencies of 67kHz and S2 and S4 in parallel, acting as high frequency rectification while wide bandgap devices eliminate reverse recovery losses. S5 and S6 are low-frequency rectifying switching tubes composed of IGBTs. Because the bus voltage is fixed, the PFC in CCM mode has a wide variation only on the AC side, and the design is easy to implement. The bidirectional CLLC converter has a full-bridge configuration on both the bus side and the battery side. L in the figurerIs a resonant inductor, LmIs an excitation inductance, Cr1And C'r2Is a resonance capacitor, and the turn ratio of the transformer is N: 1. The maximum charging power is DC 6.6kW, and the alternating current side discharging power is AC3.3kW. For the resonant converter, the forward and reverse operation is an asymmetric working condition, and the fixed low bus voltage is 400V, so that the CLLC converter can select a common Si MOSFET, and the realization cost of the whole machine is low.
Further, referring to fig. 4, the parameter design method of the bidirectional CLLC resonant converter provided in the exemplary embodiment includes the following steps:
(1) selecting a resonant frequency
The operating frequency of the CLLC is suitably in the range of 100kHz to 200kHz, taking into account the test range of switching losses, transformer size and EMC (electromagnetic compatibility).
(2) Initial selection of transformer turns ratio
When the input and output have a wide range of variation, the turns ratio of the transformer is first set according to the operating point of the rated voltage.
(3) Selection of LnAnd Qe
And selecting proper Ln and Qe according to the charge-discharge mode. The secondary capacitor Cn of the CLLC converter has the capacity of reversely transmitting power, and the value of Cn is usually 2 under the condition that the forward and reverse transmission power is equal.
(4) Optimizing transformer turn ratio N
The parameters selected according to the steps can meet the power conversion requirements of charging and discharging, but under the ultra-wide output range, the battery voltage has a larger circulating current value when being lower, and the conduction loss of the MOSFET is larger than that of other working points, which is not beneficial to the device type selection of the whole machine. The value of N needs to be increased to lower the circulating effective value of the low voltage part in the charging mode, and the loss of the MOSFET is reduced. Increasing the value of N can significantly reduce the charge loss, but at the same time increases the loss for the discharge regime. Therefore, the turn ratio of the transformer determines the overall efficiency of forward and reverse operation of the resonant converter, generally, the charging efficiency is a more concerned index, and the selection of the value N tends to improve the charging efficiency.
Specifically, based on FHA analysis, an equivalent mathematical model of CLLC in charge and discharge mode is obtained as shown in fig. 2 a-2 b. For better analysis, the parameters of the CLLC model can be equivalent to the bus terminal R during charge and discharge operationacAnd RacfThe equivalent expression for the charge and discharge load is as follows:
and (3) charging mode:
Figure BDA0002752862320000041
a discharging mode:
Figure BDA0002752862320000051
and deducing a gain formula of the charge-discharge resonant network according to the equivalent model of the FHA, wherein the gain formula is shown in formulas (3) to (4).
And (3) charging mode:
Figure BDA0002752862320000052
a discharging mode:
Figure BDA0002752862320000053
to simplify the analysis, the variables in the formula are equivalently transformed as follows:
Figure BDA0002752862320000054
Figure BDA0002752862320000055
Figure BDA0002752862320000056
Figure BDA0002752862320000057
Figure BDA0002752862320000058
substituting expressions (5) to (9) into expressions (3) and (4) to derive a normalized gain model as shown in expressions (10) and (11), transforming gains with f, Ln，Qe(Qef) And CnIs related to.
Figure BDA0002752862320000059
Figure BDA00027528623200000510
Setting the imaginary parts of equations (11) and (12) to zero, the resonance frequency points of charging and discharging can be solved as follows:
high-frequency solution:
Figure BDA00027528623200000511
low-frequency solution:
Figure BDA00027528623200000512
the gain of the bidirectional resonant converter at the high-frequency resonance point is derived as follows (14) and (15):
and (3) charging mode:
Figure BDA00027528623200000513
a discharging mode:
Figure BDA0002752862320000061
specifically, the parameter affecting the CLLC converter gain is Ln，Qe(Qef) N and Cn. And (4) taking the normalized switching frequency as a variable, and drawing the trend of the charge and discharge gain curve along with the change of different resonance parameters. It can be seen that with QeIs increased by the load RacDecreasing (i.e., the output power becomes larger) the trend of the gain is decreasing. Observation of the curve with LnThe curve of the reduction of the value becomes narrow, the gain is gradually increased, and the CLLC converter has better output voltage capability and smaller frequency variation range. Wherein L isnAnd QeThe parameter selection principle of the method is consistent with that of the LLC converter. CnThe value of (c) determines the gain capability of the CLLC to charge and discharge. CnThe larger the value of (A), Cr2The smaller the influence of the impedance on the charging voltage gain, and the closer the charging gain curve is to the LLC. CnThe value of (A) mainly affects the low frequency resonance point and the gain of the low frequency resonance point when CnWhen smaller, the higher the gain at the low frequency resonance point in the charging mode, the more gain loss near the high frequency resonance point results. When C is presentnWhen the discharge gain curve is larger, the gain near the high-frequency resonance point of the discharge gain curve is smoother, and the frequency of the operating point is higher, which is an operating area with poorer characteristics. CnThe influence on the charging and discharging directions is opposite, so that C needs to be comprehensively selected according to actual requirementsnThe value is obtained. When C is presentnWhen the value of (d) is equal to 1, the gain loss amplitude in the charge mode is large. In the case of a bi-directional application,Cnshould be greater than 1. At CnIn case of not less than 5, discharge mode f0_hThe gain becomes too smooth and the section in which the boost operation is possible is small, so CnShould be less than 5. The charge and discharge gain condition is synthesized, and the value of Cn is more suitable to be selected from 2 to 3 under the requirement of equivalent bidirectional transmission power.
In the process of selecting parameters of the resonant converter in wide-range application, the efficiency is the most important optimization quantity. The CLLC topology operates in a soft switching mode, so that the loss of the MOSFET is mainly conduction loss which is determined by the circulating current value of the resonant cavity, and the turn ratio of the transformer determines the circulating current value distribution of charging and discharging, namely the distribution of the optimal working point of the system. Deducing the effective value of the circulation current at the bus side in the charging mode as follows:
Figure BDA0002752862320000062
the effective voltage and current values of the ports are as follows:
Figure BDA0002752862320000063
Figure BDA0002752862320000064
the effective value of the exciting current is derived as follows
Figure BDA0002752862320000065
The effective value expressions of the bus side circulation current according to the charging modes (17) to (19) are
Figure BDA0002752862320000071
Similarly, the effective value expression for deriving the battery-side circulating current in the discharge mode is
Figure BDA0002752862320000072
According to the expression of the effective value of the circulating current, the main influencing parameters are the turns ratio N and L of the transformerm. Wherein L ismIs selected in relation to the output power capability. General LmThe larger the value of (A), the smaller the output power capability, the smaller the circulating current, the higher the efficiency, i.e. at rated output power, the designed LmMaking the amount of power domain smaller will be more efficient and generally this optimization procedure has a limited impact on efficiency. When the value of N is selected to be larger, the circulating current value on the bus line side in the charging mode is larger, and the loss of the MOSFET and the resonant capacitor on the bus line side is larger. In the charge mode, the MOSFET on the battery side functions as a diode, the influence of the circulating current on the loss is small, and the discharge mode has the same tendency. When the value of N is selected to be small, the loop current on the battery side in the discharge mode is large, and the losses of the MOSFET and the resonant capacitor on the battery side are large. I.e. adjusting the value of N can set a higher efficiency in either the charging or discharging regime. The charging mode is typically a typical operating region, and therefore the value of N is often set in consideration of optimization to improve charging efficiency. In addition, N also divides a wide range of operating points into a voltage boosting region (frequency less than the resonant frequency) and a voltage dropping region (frequency greater than the resonant frequency), wherein the operating frequency of the voltage boosting region is lower, and the gain curve is more efficient and easier to control, which is a better operating region.
The parameter design method of the bidirectional CLLC resonant converter provided by the above embodiment of the invention can guide the parameter design and optimization of the CLLC converter. Based on the requirements of high efficiency and low cost of a vehicle-mounted charger, a fixed bus scheme is adopted, and analysis on the gain and loss of a resonant converter shows that the resonant capacitor and the turn ratio of a transformer are main influence parameters for bidirectional operation. The reasonable arrangement of the turn ratio of the resonant capacitor to the transformer can ensure that the resonant converter can obtain the best charging efficiency in the wide-range operation, and simultaneously has lower realization cost.
In a specific application case, the input and output voltage power of the designed bidirectional CLLC resonant converter is shown in table 1 below.
TABLE 1
Item Numerical value
Bus voltage 400V
Voltage of battery 270V-480V
Charging power 6600W
AC discharge power 3300W
Bus side MOSFET STW65N65DM2AG
Battery side MOSFET STW50N65DM2AG
Further, for the bidirectional CLLC resonant converter, the design is selected from the resonant frequency f0_hAnd starting. Considering the switching losses, the transformer volume and the EMC test range together, it is appropriate that the operating frequency of the CLLC is in the range of 100kHz to 200kHz, where f is defined herein0Set at 100 kHz. After the resonant frequency is determined, the operating point of the converter will be close to the resonant frequency. High-frequency resonance point f of CLLC system0_hIs determined by four resonance parameters, in orderSimplifying the parameter design process to make the selected resonance frequency approximately equal to f0The actual charging resonance frequency will be slightly greater than f0And the discharge resonance frequency will be slightly less than f0。
Further, for the bidirectional CLLC resonant converter, the input and output voltage conversion formula is as follows:
Figure BDA0002752862320000081
Vbus＝Vbattery×N×Mg_reverse (23)
when the input and output have a wide range of variation, the turns ratio of the transformer is first set according to the operating point of the rated voltage. As can be seen from the previous section, the gain of the CLLC converter at the high frequency resonance point will be slightly lower than 1, and the initial design can temporarily adjust the gain value Mg_f0Is set to 1. According to the rated working point of the system, a bus 400V is converted into charging voltage 360V, and the turns ratio of a transformer is preliminarily selected to be
Figure BDA0002752862320000082
According to the selected transformer turn ratio, the maximum value and the minimum value of the required charging gain can be calculated to be M respectivelyg_c_min0.6 and Mg_c_max1.08. The maximum value and the minimum value of the required discharge gain are Mg_d_min0.92 and Mg_d_max＝1.64。
Further, for the bidirectional CLLC resonant converter, a suitable L should be selectednAnd QeThe value of (c) ensures that the system achieves the required charge and discharge maximum and minimum gains. According to pair CnAnalysis of values, CnWhen the value is 2, the gain of forward and reverse operation can better satisfy the bidirectional power transmission. In FIGS. 3 a-3 b, the following L is givennAnd QeA curve of variation of the gain peak at the variation of (2), wherein C n2. For example, where point A indicates Ln＝1，Qe＝0.5，CnThe maximum gain value of the sensitivity region on the charge gain curve at 2 is 2.83. Comparing fig. 3a and 3b, it can be seen that some of the curves are discontinuous. There are two peaks on the gain curve, and only the peak points with higher frequencies are in the applicable sensitivity zone. With Qe(or Q)ef) The peak value of the gain is gradually reduced, and a capacitance region appears between two resonance frequency points, so that the peak value of the inductance region is suddenly changed to the gain value of a high-frequency resonance point.
Further, for the bidirectional CLLC resonant converter, L can be selected according to charging requirementsnAnd QeThe value of (c). Specifically, the output is constant power during charging conditions, thus QeThe lowest value point is 480V. Can temporarily put QeSet to 480V at 0.5, see if Q is present in the figureeA gain of 0.5 is greater than the desired 1.08, then LnMust be less than 3. Selection of LnThen continue checking for Q3e1.58 (battery voltage 270V) and a gain of 0.85 (i.e. close to the desired gain of 0.6), the parameters chosen are satisfactory. According to the forward gain, Ln＝3，Qe＝0.5(480V)。
Further, for the bidirectional CLLC resonant converter, L can be selected according to discharge requirementsnAnd QeThe value of (c). Specifically, the output is a constant voltage value under the discharge condition, and the load is unchanged. In this case, the voltage and DC power values are 400V and 3600W, respectively, Qef0.39. The 270V battery voltage needs to meet the requirement of gain 1.64 during inversion, and as can be seen from the discharge curve, when Q is equal toefWhen equal to 0.39, LnThe gain value of 3 is compared with the threshold value, and L is further adjustedn2. Finally, selecting a parameter L according to the charge and discharge gain requirementn＝2，Qe0.5 (charge 480V).
The parameters selected according to the steps can meet the power conversion requirements of charging and discharging, but under the ultra-wide output range, the battery voltage has a larger circulating current value when being lower, and the conduction loss of the MOSFET is larger than that of other working points, which is not beneficial to the device type selection of the whole machine. The value of N needs to be increased to reduce the effective value of circulating current of the low-voltage part in the charging mode and reduce the loss of the MOSFET. The selected on-resistances of Q1-Q4 and Q5-Q8 in this example were 40m and 70m, respectively. The resonance parameters are the same, and the switching losses in the different N-value versus charge-discharge modes are shown in fig. 5 a-5 b below. The comparison in the figure gives the loss values of the two extreme operating points 270V/6.6kW and 480V/6.6 kW. If N is chosen to be 0.9 according to the nominal operating point, the losses will be as high as 36W at 270V/6.6 kW. Increasing the value of N can significantly reduce the charge loss, but at the same time increases the loss for the discharge regime. Generally, the charging efficiency is a more interesting index, and the selection of the value of N tends to improve the charging efficiency.
In addition, with the increase of the value of N, the voltage of the battery corresponding to the high-frequency resonance point is gradually reduced, and the charging working condition has more working points in a boosting area. Meanwhile, more working points under the discharge working condition are positioned in the voltage reduction area, and the working frequency of the discharge mode is improved. The curves shown in fig. 6 a-6 b below plot the gain curves for discharge modes at different turns ratios and different battery voltages. The load in the curve corresponds to a bus voltage of 400V/3.6 kW. The graph shows that as N increases, the operating point frequency of the discharge mode will increase significantly. The OBC designed by the embodiment adopts a control strategy combining frequency modulation and hiccup modes, and enters the 300kHz hiccup state from the frequency modulation state after the working frequency of the CLLC exceeds 300 kHz. The increase of the operating point frequency will make more operating conditions be located in hiccup region, because the duty cycle is intermittent ripples, the ripple of battery current can be great, is not better operating region, consequently will consider the division of the operating point that discharges simultaneously when adjusting N. The distribution of the discharge operating points when the load changes is described as shown in fig. 6b below, and the larger the value of N, the larger the region in which the discharge operating condition hiccups. Therefore, the charging efficiency and the distribution of the discharging working points of the whole machine are comprehensively considered, N is determined to be 1, the resonance parameters are more suitable to be finely adjusted by combining software simulation and device model selection, and finally the optimized resonance parameters and device model selection are shown in the following table 2. The design parameters of the corresponding experimental prototype (6.6 kW DC and 3.3kW AC for the charge/discharge rated power, respectively) are also shown in Table 2 below. The proposed parameter design method was verified by the experimental prototype. Experimental results show that the resonant converter can realize bidirectional wide-range power conversion, the full-load charging efficiency reaches 97.5%, and the complete machine charging efficiency reaches 94.5%.
TABLE 2
Figure BDA0002752862320000101
It should be understood that the above-mentioned embodiments are merely illustrative of the technical concepts and features of the present invention, which are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and therefore, the protection scope of the present invention is not limited thereby. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims (1)

1. A parameter design method of a bidirectional CLLC resonant converter is characterized by comprising the following steps:
(1) providing a bi-directional CLLC resonant converter in cascade with a PFC module, and selecting an operating frequency range of the bi-directional CLLC resonant converter according to one or more structural characteristics and/or one or more performance characteristics of the bi-directional CLLC resonant converter, wherein the one or more structural characteristics and/or one or more performance characteristics of the bi-directional CLLC resonant converter include a size of a magnetic element, an output power, a switching loss, an EMC conducted radiation requirement;
(2) when the bidirectional CLLC resonant converter works in a wide range, preliminarily setting the turn ratio of the transformer according to the working point of rated voltage;
(3) selecting proper proportionality coefficients Ln and Qe according to a charging and discharging mode, and determining proper Ln and Qe according to forward and reverse transmission requirements, wherein when forward and reverse transmission power is under the same level condition, the capacitance value of a secondary side capacitor of the bidirectional CLLC resonant converter is 2 times that of a primary side capacitor;
(4) optimizing the turns ratio of the transformer, and then performing the operation of the step (3) again until the bidirectional CLLC resonant converter has the required working efficiency;
the working frequency of the bidirectional CLLC resonant converter is within the range of 100kHz to 200kHz, and the charging and discharging resonant frequency points of the bidirectional CLLC resonant converter are as follows:
high-frequency solution:
Figure 686062DEST_PATH_IMAGE002
low-frequency solution:
Figure 901405DEST_PATH_IMAGE004
wherein the content of the first and second substances,
Figure 149984DEST_PATH_IMAGE006
；
the gain of the bidirectional resonant converter at the high frequency resonance point is derived as follows:
and (3) charging mode:
Figure 607510DEST_PATH_IMAGE008
a discharging mode:
Figure 15357DEST_PATH_IMAGE010
；
for the bidirectional CLLC resonant converter, the effective value of the circulating current on the bus side in the charging mode is as follows:
Figure 572241DEST_PATH_IMAGE012
；
the effective values of the current and the voltage of the port are as follows:
Figure 432749DEST_PATH_IMAGE014
Figure 932782DEST_PATH_IMAGE016
；
the effective value of the excitation current is derived as follows:
Figure 336081DEST_PATH_IMAGE018
；
further, the effective value expression of the charging mode bus side circulating current is:
Figure 922920DEST_PATH_IMAGE020
；
the effective value expression of the battery side circulating current in the discharge mode is as follows:
Figure 473987DEST_PATH_IMAGE022
；
whereinL r Is a resonant inductance that is a function of,L m is an excitation inductance, and is characterized in that,C r1、C r2is a resonant capacitance that is a function of,R ac is a charging load to which the electric power is supplied,R acf is a load of the electric discharge, and,V m is the effective value of the voltage at the port.
CN202011200410.2A 2020-10-30 2020-10-30 Parameter design method of bidirectional CLLC resonant converter Active CN112436730B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202011200410.2A CN112436730B (en) 2020-10-30 2020-10-30 Parameter design method of bidirectional CLLC resonant converter

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202011200410.2A CN112436730B (en) 2020-10-30 2020-10-30 Parameter design method of bidirectional CLLC resonant converter

Publications (2)

Publication Number Publication Date
CN112436730A CN112436730A (en) 2021-03-02
CN112436730B true CN112436730B (en) 2022-03-15

Family

ID=74695054

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202011200410.2A Active CN112436730B (en) 2020-10-30 2020-10-30 Parameter design method of bidirectional CLLC resonant converter

Country Status (1)

Country Link
CN (1) CN112436730B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2021127995A1 (en) * 2019-12-24 2021-07-01 Cree, Inc. Circuits and methods for controlling bidirectional cllc converters

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107493017A (en) * 2017-10-11 2017-12-19 燕山大学 A kind of multiport bidirectional DC/DC converter topology based on CLLC
CN108566096A (en) * 2018-04-10 2018-09-21 西安理工大学 A kind of design method of bidirectional DC-DC converter resonant slots parameter
CN110838793A (en) * 2019-10-21 2020-02-25 浙江大学 Synchronous rectification circuit and control strategy applied to bidirectional CLLC resonant converter
US10587201B1 (en) * 2019-03-12 2020-03-10 Zhejiang University Method for controlling smooth switching of operation direction of bidirectional resonant CLLC circuit
CN111669058A (en) * 2020-05-26 2020-09-15 中国科学院电工研究所 Three-phase CLLC bidirectional DC converter and control method thereof

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105871215A (en) * 2016-05-17 2016-08-17 华南理工大学 Rectification control circuit for bidirectional CLLLC resonant converter
CN109703399B (en) * 2018-12-27 2021-05-18 台达电子企业管理（上海）有限公司 Vehicle-mounted charging and discharging system and control method applicable to same
CN109687719B (en) * 2019-02-28 2020-10-27 西安交通大学 Modulation method for CLLC bidirectional isolation type DC-DC converter

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107493017A (en) * 2017-10-11 2017-12-19 燕山大学 A kind of multiport bidirectional DC/DC converter topology based on CLLC
CN108566096A (en) * 2018-04-10 2018-09-21 西安理工大学 A kind of design method of bidirectional DC-DC converter resonant slots parameter
US10587201B1 (en) * 2019-03-12 2020-03-10 Zhejiang University Method for controlling smooth switching of operation direction of bidirectional resonant CLLC circuit
CN110838793A (en) * 2019-10-21 2020-02-25 浙江大学 Synchronous rectification circuit and control strategy applied to bidirectional CLLC resonant converter
CN111669058A (en) * 2020-05-26 2020-09-15 中国科学院电工研究所 Three-phase CLLC bidirectional DC converter and control method thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"Variable CLLC Topology Structure Technique for a Bidirectional on Board Charger of Electric Vehicle";Lu Qu,et al;《2019 the 4th International Conference on Power and Renewable Energy》;20200316;第185-189页 *

Also Published As

Publication number Publication date
CN112436730A (en) 2021-03-02

Similar Documents

Publication Publication Date Title
Dao et al. High-efficiency hybrid LLC resonant converter for on-board chargers of plug-in electric vehicles
Wang et al. A PWM LLC type resonant converter adapted to wide output range in PEV charging applications
US9490709B2 (en) Hybrid DC-DC converter with LLC converter and full-bridge converter
CN110936827B (en) Wireless charging system, wireless charging control method and automobile wireless charging device
Sun et al. An improved wide input voltage buck-boost+ LLC cascaded converter
Jovanović et al. Efficiency optimization of LLC resonant converters operating in wide input-and/or output-voltage range by on-the-fly topology-morphing control
Hu et al. LLC resonant converters for PHEV battery chargers
Inamdar et al. Literature review of 3.3 kW on board charger topologies
Cao et al. Fixed frequency phase shift modulated LLC resonant converter adapted to ultra wide output voltage range
Khalid et al. Hybrid modulated reconfigurable bidirectional CLLC converter for V2G enabled PEV charging applications
Reddy et al. Novel wide voltage range multi-resonant bidirectional DC-DC converter
CN112436730B (en) Parameter design method of bidirectional CLLC resonant converter
Shukla et al. A Power Factor Profile-Improved EV Charging System Using Bridgeless Buckboost-Cuk Converter
Liu et al. High efficiency wide range bidirectional DC/DC converter for OBCM application
Qu et al. A high efficiency and low shutdown current bidirectional DC-DC CLLLC resonant converter
Outeiro et al. Resonant power converters applications: L s C s L p C p circuit for renewable energy sources as case study
Colak et al. Hybrid control approach of CLL resonant converter for EV battery chargers
Zhang et al. Hybrid structure for an input-parallel output-serial dc-dc combined converter with high efficiency and high power density
Reddy et al. Reconfigurable bidirectional dc-dc converter for electric vehicle onboard charging applications
Suthar et al. A Pulse density modulated LLC resonant converter based battery charger for HEV/PHEV application
Minli et al. GaN-based high frequency 6.6 kw bi-directional dc/dc converter for obc application
Cao et al. Design optimization of LLC converter for battery charger with wide output voltage range
CN207926446U (en) A kind of DC-DC converter
Zhang et al. Analysis and optimal parameter selection of Full bridge bidirectional CLLC converter for EV
Luo et al. A primary shunt inductor compensated inductive power transfer system with natural ZVS for battery charging application

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant