CN111478571B - Control method and device of frequency converter - Google Patents

Control method and device of frequency converter Download PDF

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CN111478571B
CN111478571B CN202010238422.8A CN202010238422A CN111478571B CN 111478571 B CN111478571 B CN 111478571B CN 202010238422 A CN202010238422 A CN 202010238422A CN 111478571 B CN111478571 B CN 111478571B
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pfc circuit
bus voltage
current bus
input voltage
voltage range
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CN111478571A (en
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尹发展
牟宗娥
岳元龙
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Hisense Air Conditioning Co Ltd
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Hisense Air Conditioning Co Ltd
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    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/06—Control using electricity
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
    • H02P23/26—Power factor control [PFC]
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
    • H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
    • H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
    • H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
    • 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
    • H02M1/0048—Circuits or arrangements for reducing losses
    • H02M1/0054—Transistor switching losses
    • 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
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Rectifiers (AREA)

Abstract

The invention relates to the technical field of frequency converters, and discloses a control method and a control device of a frequency converter, wherein the method comprises the following steps: when a PFC circuit in the frequency converter is in a working state, calculating the target input voltage of the compressor in real time; calculating a target direct current bus voltage range of the PFC circuit according to the target input voltage of the compressor; modulating the input voltage of the PFC circuit according to the target DC bus voltage range of the PFC circuit; adjusting the direct current bus voltage output by the PFC circuit so that the direct current bus voltage output by the PFC circuit is within a target direct current bus voltage range of the PFC circuit and within a preset actual direct current bus voltage range of the PFC circuit; and outputting the regulated direct current bus voltage of the PFC circuit to a compressor. The PFC circuit of the embodiment of the invention achieves the optimal control, avoids the PFC circuit from adopting a constant voltage output mode, reduces the loss of a power device in the PFC circuit and reduces the whole machine function.

Description

Control method and device of frequency converter
Technical Field
The invention relates to the technical field of frequency converters, in particular to a control method and a control device of a frequency converter.
Background
The inverter air conditioner is a conventional air conditioner additionally provided with an inverter, and the rotating speed of a compressor in the air conditioner is adjusted through the inverter to be in the optimal rotating speed state all the time, so that the inverter air conditioner has higher energy efficiency ratio. A frequency converter in an air conditioner mainly comprises three parts, namely a rectifying circuit, a Power Factor Correction (PFC) circuit and a Power supply inverter circuit, as shown in figure 1; the PFC circuit mainly plays the roles of restraining harmonic current, improving power factor and improving direct-current bus voltage.
At present, a PFC circuit in the existing frequency converter is mainly controlled by adopting a constant voltage output mode; specifically, the PFC circuit is controlled to constantly output a direct-current bus voltage of 350V. Although, in some control schemes, the output voltage of the PFC circuit varies, the PFC circuit actually performs the output in different segments according to the operating frequency of the compressor, and the dc bus voltage of each segment is also constant. In the process of implementing the invention, the inventor finds that the prior art has at least the following technical problems: when the compressor load operates at a medium-low frequency, the direct-current bus voltage is still output according to 350V, and the consumption power of the PFC circuit is related to the output voltage of the PFC circuit; when the voltage output by the PFC circuit is high, an MCU (micro controller Unit) controls the output PWM duty ratio of the PFC circuit to be large, which makes the on-time of each PWM period longer and the on-current also increased, so that the on-loss of the IGBT controlling the PFC circuit is increased, resulting in relatively high power consumption of the whole device.
Disclosure of Invention
The invention aims to provide a control method and a control device of a frequency converter, which can reduce the loss of a power device in a PFC circuit so as to reduce the power consumption of the whole frequency converter.
In order to solve the above technical problems, the present invention provides a method for controlling a frequency converter, comprising:
when a PFC circuit in the frequency converter is in a working state, calculating the target input voltage of the compressor in real time;
calculating a target direct current bus voltage range of the PFC circuit according to the target input voltage of the compressor;
modulating the input voltage of the PFC circuit according to the target direct-current bus voltage range of the PFC circuit;
adjusting the direct-current bus voltage output by the PFC circuit so that the direct-current bus voltage output by the PFC circuit is within a target direct-current bus voltage range of the PFC circuit and within a preset actual direct-current bus voltage range of the PFC circuit;
and outputting the regulated direct current bus voltage output by the PFC circuit to the compressor so as to drive the compressor to operate.
As a preferable scheme, the calculating a target dc bus voltage range of the PFC circuit according to the target input voltage of the compressor specifically includes:
according to the target input voltage of the compressor, calculating an upper limit value of a target direct current bus voltage range of the PFC circuit through the following formula:
Figure BDA0002431777650000021
wherein, V dcref-H The voltage range is the upper limit value of the target direct current bus voltage range of the PFC circuit; v s A target input voltage for the compressor;
according to the target input voltage of the compressor, calculating a lower limit value of a target direct current bus voltage range of the PFC circuit through the following formula:
Figure BDA0002431777650000022
wherein, V dcref-L The lower limit value of the target direct current bus voltage range of the PFC circuit; v s Is a target input voltage for the compressor.
As a preferred scheme, the modulating the input voltage of the PFC circuit according to the target dc bus voltage range of the PFC circuit specifically includes:
when the lower limit value of the target direct-current bus voltage range of the PFC circuit meets a preset first condition, modulating the input voltage of the PFC circuit in the whole period of the input voltage of the PFC circuit;
wherein the first condition is:
Figure BDA0002431777650000031
wherein, V dcref-L The lower limit value of the target direct current bus voltage range of the PFC circuit; vac is the input voltage of the PFC circuit;
when the upper limit value of the target direct-current bus voltage range of the PFC circuit meets a preset second condition, modulating the input voltage of the PFC circuit in a first time period, and turning off the PFC circuit in a second time period; the first time period is a time period in which the input voltage of the PFC circuit is less than or equal to the direct-current bus voltage output by the PFC circuit in the whole cycle of the input voltage of the PFC circuit; the second time period is a time period in which the input voltage of the PFC circuit is greater than the DC bus voltage output by the PFC circuit in the whole cycle of the input voltage of the PFC circuit;
the second condition is:
Figure BDA0002431777650000032
wherein, V dcref-H The voltage range is the upper limit value of the target direct current bus voltage range of the PFC circuit; vac is the input voltage of the PFC circuit.
Preferably, the method for controlling the frequency converter further includes:
acquiring the input voltage of the PFC circuit;
and calculating the actual direct current bus voltage range of the PFC circuit according to the input voltage of the PFC circuit.
As a preferable scheme, the calculating an actual dc bus voltage range of the PFC circuit according to the input voltage of the PFC circuit specifically includes:
when the input voltage of the PFC circuit does not meet a preset third condition, acquiring that the upper limit value of the actual direct-current bus voltage range of the PFC circuit is 350V, and the lower limit value of the actual direct-current bus voltage range of the PFC circuit is 280V;
when the input voltage of the PFC circuit meets a preset third condition, the upper limit value of the actual direct current bus voltage range of the PFC circuit is 350V, and the lower limit value of the actual direct current bus voltage range of the PFC circuit is obtained through calculation according to the following formula:
Figure BDA0002431777650000041
therein, VDC min Is that it isThe lower limit value of the actual direct current bus voltage range of the PFC circuit; vac is the input voltage of the PFC circuit; the third condition is:
Figure BDA0002431777650000042
in order to solve the same technical problem, an embodiment of the present invention further provides a control apparatus for a frequency converter, including:
the compressor target input voltage calculation module is used for calculating the target input voltage of the compressor in real time when a PFC circuit in the frequency converter is in a working state;
the target direct current bus voltage range calculation module is used for calculating a target direct current bus voltage range of the PFC circuit according to the target input voltage of the compressor;
the voltage modulation module is used for modulating the input voltage of the PFC circuit according to the target direct-current bus voltage range of the PFC circuit;
the voltage adjusting module is used for adjusting the direct current bus voltage output by the PFC circuit so that the direct current bus voltage output by the PFC circuit is within a target direct current bus voltage range of the PFC circuit and within a preset actual direct current bus voltage range of the PFC circuit;
and the direct current bus voltage output module is used for outputting the regulated direct current bus voltage output by the PFC circuit to the compressor so as to drive the compressor to operate.
As a preferred scheme, the target dc bus voltage range calculation module specifically includes:
the upper limit value calculating unit is used for calculating an upper limit value of a target direct current bus voltage range of the PFC circuit according to a target input voltage of the compressor by the following formula:
Figure BDA0002431777650000043
wherein, V dcref-H The voltage range is the upper limit value of the target direct current bus voltage range of the PFC circuit;V s a target input voltage for the compressor;
the lower limit value calculating unit is used for calculating a lower limit value of a target direct current bus voltage range of the PFC circuit according to a target input voltage of the compressor by the following formula:
Figure BDA0002431777650000051
wherein, V dcref-L The lower limit value of the target direct current bus voltage range of the PFC circuit; v s Is a target input voltage for the compressor.
As a preferred scheme, the voltage modulation module specifically includes:
the first modulation unit is used for modulating the input voltage of the PFC circuit in the whole period of the input voltage of the PFC circuit when the lower limit value of the target direct-current bus voltage range of the PFC circuit meets a preset first condition;
wherein the first condition is:
Figure BDA0002431777650000052
wherein, V dcref-L The lower limit value of the target direct current bus voltage range of the PFC circuit; vac is the input voltage of the PFC circuit;
the second modulation unit is used for modulating the input voltage of the PFC circuit in a first time period and switching off the PFC circuit in a second time period when the upper limit value of the target direct-current bus voltage range of the PFC circuit meets a preset second condition; the first time period is a time period in which the input voltage of the PFC circuit is less than or equal to the direct-current bus voltage output by the PFC circuit in the whole cycle of the input voltage of the PFC circuit; the second time period is a time period in which the input voltage of the PFC circuit is greater than the DC bus voltage output by the PFC circuit in the whole cycle of the input voltage of the PFC circuit;
the second condition is that:
Figure BDA0002431777650000053
wherein, V dcref-H The voltage range is the upper limit value of the target direct current bus voltage range of the PFC circuit; vac is the input voltage of the PFC circuit.
Preferably, the control device of the frequency converter further includes:
the input voltage acquisition module is used for acquiring the input voltage of the PFC circuit;
and the actual direct current bus voltage range calculating module is used for calculating the actual direct current bus voltage range of the PFC circuit according to the input voltage of the PFC circuit.
As a preferred scheme, the actual dc bus voltage range calculation module specifically includes:
the first voltage range calculation unit is used for obtaining that the upper limit value of the actual direct current bus voltage range of the PFC circuit is 350V and the lower limit value of the actual direct current bus voltage range of the PFC circuit is 280V when the input voltage of the PFC circuit does not meet a preset third condition;
the second voltage range calculating unit is configured to, when the input voltage of the PFC circuit meets a preset third condition, obtain that an upper limit value of an actual dc bus voltage range of the PFC circuit is 350V, and calculate a lower limit value of the actual dc bus voltage range of the PFC circuit according to the following formula:
Figure BDA0002431777650000061
therein, VDC min The lower limit value of the actual direct current bus voltage range of the PFC circuit; vac is the input voltage of the PFC circuit; the third condition is that:
Figure BDA0002431777650000062
compared with the prior art, the invention provides a control method and a control device of a frequency converter, which are characterized in that when a PFC circuit in the frequency converter is in a working state, a target direct-current bus voltage range of the PFC circuit is calculated according to a target input voltage of a compressor, the input voltage of the PFC circuit is modulated according to the target direct-current bus voltage range of the PFC circuit, and meanwhile, the direct-current bus voltage output by the PFC circuit is adjusted to be within the target direct-current bus voltage range of the PFC circuit and within a preset actual direct-current bus voltage range of the PFC circuit, so that the direct-current bus voltage value output by the PFC circuit is adjusted in real time according to the load requirement of the compressor, the PFC circuit achieves optimal control, and meanwhile, the PFC circuit is prevented from adopting a constant-voltage output mode, the loss of power devices in the PFC circuit is reduced, the efficiency of a controller is improved, and the power consumption of the whole machine is reduced.
Drawings
Fig. 1 is a schematic structural diagram of a frequency converter according to an embodiment of the present invention;
fig. 2 is a schematic flowchart of a control method of a frequency converter according to an embodiment of the present invention;
fig. 3 is a schematic diagram of regulating a dc bus voltage output by a PFC circuit according to an embodiment of the present invention;
fig. 4 is a schematic diagram of modulating an input voltage of a PFC circuit according to an embodiment of the present invention;
fig. 5 is a schematic diagram of another exemplary embodiment of the present invention for modulating the input voltage of the PFC circuit;
fig. 6 is a schematic structural diagram of a frequency converter control device according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.
Fig. 2 is a schematic flow chart of a control method of a frequency converter according to an embodiment of the present invention.
The control method of the frequency converter provided by the embodiment of the invention can be executed by an MCU, and the MCU is taken as an execution main body for explanation in the embodiment.
In the embodiment of the invention, the control method of the frequency converter comprises the following steps S11-S15:
s11, when a PFC circuit in the frequency converter is in a working state, calculating the target input voltage of the compressor in real time.
It can be understood that, when the frequency converter is turned on, after the PFC circuit operates, the operating frequency of the compressor is adjusted according to the actual operating requirement during operation, and the target input voltage of the compressor is calculated by combining the magnitude of the load carried by the compressor, the target operating frequency, and the parameters of the coil inside the compressor.
Preferably, the target input voltage of the compressor is calculated according to a driving algorithm by the following formula:
Figure BDA0002431777650000071
wherein, V s A target input voltage of the compressor; v d Is the earth axis voltage; v q Is the side axis voltage.
It should be noted that the above is only one embodiment of calculating the target input voltage of the compressor, and the target input voltage of the compressor may be calculated in other manners according to actual use conditions, which is not limited in the present invention.
In addition, in the embodiment of the invention, when the current of the whole machine is greater than or equal to the preset current threshold, the PFC circuit is determined to be in the working state; and when the current of the whole machine is smaller than a preset current threshold value, determining that the PFC circuit is in a non-working state. Wherein, the PFC circuit is in a working state, which is specifically represented as: and starting and working the PFC circuit.
And S12, calculating a target direct current bus voltage range of the PFC circuit according to the target input voltage of the compressor.
The target dc bus voltage range of the PFC circuit includes an upper limit value and a lower limit value of the target dc bus voltage range of the PFC circuit. In order to prevent voltage fluctuation during subsequent adjustment, the upper limit value and the lower limit value of the target direct current bus voltage range of the PFC circuit are calculated according to the target input voltage of the compressor, so that the target direct current bus voltage range of the PFC circuit is obtained for subsequent adjustment.
And S13, modulating the input voltage of the PFC circuit according to the target direct-current bus voltage range of the PFC circuit.
Specifically, according to the calculated target direct-current bus voltage range of the PFC circuit, PFC modulation is carried out on the input voltage of the PFC circuit.
And S14, adjusting the direct current bus voltage output by the PFC circuit so that the direct current bus voltage output by the PFC circuit is within a target direct current bus voltage range of the PFC circuit and within a preset actual direct current bus voltage range of the PFC circuit.
Specifically, the DC bus voltage VDC + output by the PFC circuit is regulated to the target DC bus voltage range (V) by PID regulation dcref-L ，V dcref-H ) Meanwhile, the direct current bus voltage output by the PFC circuit meets the actual bus voltage range (VDC) preset by the system min ，VDC max ) As shown in fig. 3.
And S15, outputting the regulated direct current bus voltage output by the PFC circuit to the compressor so as to drive the compressor to operate.
It can be understood that, as shown in fig. 1, the frequency converter includes a rectification circuit, a PFC circuit, and an inverter circuit; and the voltage output by the power supply sequentially passes through the rectification circuit, the PFC circuit and the inverter circuit and then is transmitted to the compressor so as to drive the compressor to operate. Therefore, when step S15 is performed, the input voltage of the PFC circuit is modulated in the PFC circuit, and the dc bus voltage VDC + output by the PFC circuit is adjusted, and then the dc bus voltage VDC + output by the PFC circuit is output to the compressor through the inverter circuit, so as to drive the compressor to operate.
In the embodiment of the invention, when the PFC circuit in the frequency converter is in a working state, the target direct-current bus voltage range of the PFC circuit is calculated according to the target input voltage of the compressor, the input voltage of the PFC circuit is modulated according to the target direct-current bus voltage range of the PFC circuit, and the direct-current bus voltage output by the PFC circuit is adjusted to be within the target direct-current bus voltage range of the PFC circuit and within the preset actual direct-current bus voltage range of the PFC circuit, so that the direct-current bus voltage value output by the PFC circuit is adjusted in real time according to the load requirement of the compressor, the PFC circuit is optimally controlled, and meanwhile, the PFC circuit is prevented from adopting a constant-voltage output mode, therefore, the loss of power devices in the PFC circuit is reduced, the efficiency of a controller is improved, and the power consumption of the whole machine is reduced.
Preferably, in step S12, the target dc bus voltage range of the PFC circuit includes an upper limit value and a lower limit value of the target dc bus voltage range of the PFC circuit;
then, the calculating a target dc bus voltage range of the PFC circuit according to the target input voltage of the compressor specifically includes the following steps S121 to S122:
s121, calculating an upper limit value of a target direct current bus voltage range of the PFC circuit according to the target input voltage of the compressor by the following formula:
Figure BDA0002431777650000091
wherein, V dcref-H The voltage range is the upper limit value of the target direct current bus voltage range of the PFC circuit; v s A target input voltage for the compressor;
s122, according to the target input voltage of the compressor, calculating a lower limit value of a target direct current bus voltage range of the PFC circuit through the following formula:
Figure BDA0002431777650000101
wherein, V dcref-L The lower limit value of the target direct current bus voltage range of the PFC circuit; v s Is a target input voltage for the compressor.
In the embodiment of the present invention, the upper limit value and the lower limit value of the target dc bus voltage range of the PFC circuit are obtained through calculation in steps S121 to S122, so as to obtain the target dc bus voltage range of the PFC circuit. It should be noted that, in the embodiment of the present invention, the execution sequence of step S121 and step S122 is not limited, for example, step S122 may be implemented first, and then step S121 is implemented, and of course, step S121 and step S122 may also be implemented simultaneously.
Preferably, in step S13, the modulating the input voltage of the PFC circuit according to the target dc bus voltage range of the PFC circuit specifically includes the following steps S131 to S132:
s131, when the lower limit value of the target direct-current bus voltage range of the PFC circuit meets a preset first condition, modulating the input voltage of the PFC circuit in the whole period of the input voltage of the PFC circuit;
wherein the first condition is:
Figure BDA0002431777650000102
wherein, V dcref-L The lower limit value of the target direct current bus voltage range of the PFC circuit; vac is the input voltage of the PFC circuit;
s132, when the upper limit value of the target direct current bus voltage range of the PFC circuit meets a preset second condition, modulating the input voltage of the PFC circuit in a first time period, and turning off the PFC circuit in a second time period; the first time period is a time period in which the input voltage of the PFC circuit is less than or equal to the direct-current bus voltage output by the PFC circuit in the whole period of the input voltage of the PFC circuit; the second time period is a time period within the whole period of the input voltage of the PFC circuit, wherein the input voltage of the PFC circuit is larger than the direct-current bus voltage output by the PFC circuit;
the second condition is:
Figure BDA0002431777650000111
wherein, V dcref-H The voltage range is the upper limit value of the target direct current bus voltage range of the PFC circuit; vac is the input voltage of the PFC circuit.
Specifically, when the lower limit value of the target dc bus voltage range of the PFC circuit satisfies:
Figure BDA0002431777650000112
in the meantime, the PFC modulation is performed all over the entire period of the input voltage of the PFC circuit, as shown in fig. 4. When the upper limit value of the target direct current bus voltage range of the PFC circuit meets the following conditions:
Figure BDA0002431777650000113
in the whole period of the input voltage of the PFC circuit, only performing PFC modulation on part of the input voltage of the PFC circuit; specifically, in the whole period of the input voltage of the PFC circuit, PFC modulation is performed in a period in which the input voltage of the PFC circuit is less than or equal to the dc bus voltage output by the PFC circuit, and the PFC circuit is turned off in a period in which the input voltage of the PFC circuit is greater than the dc bus voltage output by the PFC circuit, as shown in fig. 5.
In a preferred embodiment, the method for controlling the frequency converter further includes the following steps S21 to S22:
s21, acquiring the input voltage of the PFC circuit;
and S22, calculating the actual direct current bus voltage range of the PFC circuit according to the input voltage of the PFC circuit.
It should be noted that the actual dc bus voltage range of the PFC circuit includes an upper limit value and a lower limit value of the actual dc bus voltage range of the PFC circuit.
Preferably, in step S22, the calculating an actual dc bus voltage range of the PFC circuit according to the input voltage of the PFC circuit specifically includes the following steps S221 to S222:
s221, when the input voltage of the PFC circuit does not meet a preset third condition, acquiring that the upper limit value of the actual direct-current bus voltage range of the PFC circuit is 350V, and the lower limit value of the actual direct-current bus voltage range of the PFC circuit is 280V;
s222, when the input voltage of the PFC circuit meets a preset third condition, obtaining that the upper limit value of the actual direct-current bus voltage range of the PFC circuit is 350V, and calculating the lower limit value of the actual direct-current bus voltage range of the PFC circuit through the following formula:
Figure BDA0002431777650000121
therein, VDC min The lower limit value of the actual direct current bus voltage range of the PFC circuit is obtained; vac is the input voltage of the PFC circuit; the third condition is:
Figure BDA0002431777650000122
specifically, when the input voltage of the PFC circuit does not meet a preset third condition, obtaining that an upper limit value of an actual dc bus voltage range of the PFC circuit is 350V, and a lower limit value of the actual dc bus voltage range of the PFC circuit is 280V, specifically: when the input voltage of the PFC circuit meets the following conditions:
Figure BDA0002431777650000123
or
Figure BDA0002431777650000124
And then, the upper limit value of the actual direct current bus voltage range of the PFC circuit is 350V, and the lower limit value of the actual direct current bus voltage range of the PFC circuit is 280V. When the input voltage of the PFC circuit meets the following conditions:
Figure BDA0002431777650000125
the upper limit value of the actual direct current bus voltage range of the PFC circuit is 350V, and the lower limit value of the actual direct current bus voltage range of the PFC circuit is 350V
Figure BDA0002431777650000126
It can be understood that the upper limit value of the actual dc bus voltage range of the PFC circuit is 350V, and the lower limit value of the actual dc bus voltage range of the PFC circuit is 350V
Figure BDA0002431777650000127
Figure BDA0002431777650000128
Fig. 6 is a schematic structural diagram of a control device of a frequency converter correspondingly provided in the embodiment of the present invention.
In the embodiment of the present invention, the control device 1 of the frequency converter includes:
the compressor target input voltage calculating module 11 is used for calculating the target input voltage of the compressor in real time when a PFC circuit in the frequency converter is in a working state;
a target dc bus voltage range calculation module 12, configured to calculate a target dc bus voltage range of the PFC circuit according to a target input voltage of the compressor;
the voltage modulation module 13 is configured to modulate an input voltage of the PFC circuit according to a target dc bus voltage range of the PFC circuit;
the voltage adjusting module 14 is configured to adjust a dc bus voltage output by the PFC circuit, so that the dc bus voltage output by the PFC circuit is within a target dc bus voltage range of the PFC circuit and within a preset actual dc bus voltage range of the PFC circuit;
and the direct current bus voltage output module 15 is configured to output the regulated direct current bus voltage output by the PFC circuit to the compressor, so as to drive the compressor to operate.
Specifically, in the compressor target input voltage calculation module 11, the operation frequency of the compressor is adjusted according to the actual operation requirement, and the target input voltage of the compressor is calculated by combining the magnitude of the load carried by the compressor, the target operation frequency, and the parameter of the internal coil of the compressor.
Preferably, the target input voltage of the compressor is calculated according to a driving algorithm by the following formula:
Figure BDA0002431777650000131
wherein, V s A target input voltage of the compressor; v d Is the earth axis voltage; v q Is the side axis voltage.
It should be noted that the above is only one embodiment of calculating the target input voltage of the compressor, and the target input voltage of the compressor may be calculated in other manners according to actual use conditions, which is not limited in the present invention.
In the embodiment of the present invention, when a PFC circuit in a frequency converter is in a working state, a target dc bus voltage range of the PFC circuit is calculated by the target dc bus voltage range calculation module 12 according to a target input voltage of the compressor, and an input voltage of the PFC circuit is modulated by the voltage modulation module 13 according to the target dc bus voltage range of the PFC circuit, and meanwhile, a dc bus voltage output by the PFC circuit is adjusted by the voltage adjustment module 14 to be within the target dc bus voltage range of the PFC circuit and to be within a preset actual dc bus voltage range of the PFC circuit, so that a dc bus voltage value output by the PFC circuit is adjusted in real time according to a requirement of a compressor load, so that the PFC circuit achieves optimal control, and meanwhile, the PFC circuit is prevented from adopting a constant voltage output mode, thereby reducing loss of a power device in the PFC circuit, improving efficiency of a controller, and reducing power consumption of a whole machine.
Further, the target dc bus voltage range calculation module 11 specifically includes:
the upper limit value calculating unit is used for calculating an upper limit value of a target direct current bus voltage range of the PFC circuit according to a target input voltage of the compressor by the following formula:
Figure BDA0002431777650000132
wherein, V dcref-H The voltage range is the upper limit value of the target direct current bus voltage range of the PFC circuit; v s A target input voltage for the compressor;
the lower limit value calculating unit is used for calculating the lower limit value of the target direct current bus voltage range of the PFC circuit according to the target input voltage of the compressor by the following formula:
Figure BDA0002431777650000141
wherein, V dcref-L The lower limit value of the target direct current bus voltage range of the PFC circuit; v s Is a target input voltage for the compressor.
Further, the voltage modulation module 13 specifically includes:
the first modulation unit is used for modulating the input voltage of the PFC circuit in the whole period of the input voltage of the PFC circuit when the lower limit value of the target direct-current bus voltage range of the PFC circuit meets a preset first condition;
wherein the first condition is:
Figure BDA0002431777650000142
wherein, V dcref-L The lower limit value of the target direct current bus voltage range of the PFC circuit; vac is the input voltage of the PFC circuit;
the second modulation unit is used for modulating the input voltage of the PFC circuit in a first time period and switching off the PFC circuit in a second time period when the upper limit value of the target direct-current bus voltage range of the PFC circuit meets a preset second condition; the first time period is a time period within the whole period of the input voltage of the PFC circuit, wherein the input voltage of the PFC circuit is smaller than or equal to the direct-current bus voltage output by the PFC circuit; the second time period is a time period in which the input voltage of the PFC circuit is greater than the DC bus voltage output by the PFC circuit in the whole period of the input voltage of the PFC circuit;
the second condition is:
Figure BDA0002431777650000143
wherein, V dcref-H The voltage range is the upper limit value of the target direct current bus voltage range of the PFC circuit; vac is the input voltage of the PFC circuit.
Specifically, when the lower limit value of the target dc bus voltage range of the PFC circuit satisfies:
Figure BDA0002431777650000151
and when the voltage is in the input voltage range, the first modulation unit performs PFC modulation in the whole period of the input voltage of the PFC circuit. When the upper limit value of the target direct-current bus voltage range of the PFC circuit meets the following conditions:
Figure BDA0002431777650000152
in the meantime, the second modulation unit only outputs part of the PFC circuit in the whole period of the input voltage of the PFC circuitPerforming PFC modulation on the input voltage; specifically, in the whole period of the input voltage of the PFC circuit, PFC modulation is carried out in a time period in which the input voltage of the PFC circuit is less than or equal to the DC bus voltage output by the PFC circuit, and the PFC circuit is turned off in a time period in which the input voltage of the PFC circuit is greater than the DC bus voltage output by the PFC circuit.
In a preferred embodiment, the control device 1 of the frequency converter further includes:
the input voltage acquisition module is used for acquiring the input voltage of the PFC circuit;
and the actual direct current bus voltage range calculation module is used for calculating the actual direct current bus voltage range of the PFC circuit according to the input voltage of the PFC circuit.
Further, the actual dc bus voltage range calculation module specifically includes:
the first voltage range calculation unit is used for obtaining that the upper limit value of the actual direct current bus voltage range of the PFC circuit is 350V and the lower limit value of the actual direct current bus voltage range of the PFC circuit is 280V when the input voltage of the PFC circuit does not meet a preset third condition;
the second voltage range calculating unit is configured to, when the input voltage of the PFC circuit meets a preset third condition, obtain that an upper limit value of an actual dc bus voltage range of the PFC circuit is 350V, and calculate a lower limit value of the actual dc bus voltage range of the PFC circuit according to the following formula:
Figure BDA0002431777650000153
therein, VDC min The lower limit value of the actual direct current bus voltage range of the PFC circuit is obtained; vac is the input voltage of the PFC circuit; the third condition is:
Figure BDA0002431777650000154
specifically, the first voltageA range calculation unit, specifically configured to, when the input voltage of the PFC circuit satisfies:
Figure BDA0002431777650000161
or
Figure BDA0002431777650000162
In the meantime, the upper limit value of the actual dc bus voltage range of the PFC circuit is 350V, and the lower limit value of the actual dc bus voltage range of the PFC circuit is 280V. When the input voltage of the PFC circuit meets the following conditions:
Figure BDA0002431777650000163
the upper limit value of the actual direct current bus voltage range of the PFC circuit is 350V, and the lower limit value of the actual direct current bus voltage range of the PFC circuit is 350V
Figure BDA0002431777650000164
It can be understood that the upper limit value of the actual dc bus voltage range of the PFC circuit is 350V, and the lower limit value of the actual dc bus voltage range of the PFC circuit is max
Figure BDA0002431777650000165
Preferably, in the embodiment of the present invention, the control device of the frequency converter is an MCU.
In summary, the present invention provides a method and an apparatus for controlling a frequency converter, where when a PFC circuit in the frequency converter is in a working state, a target dc bus voltage range of the PFC circuit is calculated according to a target input voltage of a compressor, and an input voltage of the PFC circuit is modulated according to the target dc bus voltage range of the PFC circuit, and at the same time, a dc bus voltage output by the PFC circuit is adjusted to be within the target dc bus voltage range of the PFC circuit and within a preset actual dc bus voltage range of the PFC circuit, so as to adjust a dc bus voltage value output by the PFC circuit in real time according to a load requirement of the compressor, so that the PFC circuit achieves optimal control, and simultaneously, the PFC circuit is prevented from adopting a constant voltage output mode, thereby reducing a loss of a power device in the PFC circuit, improving efficiency of the controller, and reducing power consumption of the entire power consumption.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, many modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.

Claims (8)

1. A control method of a frequency converter is characterized by comprising the following steps:
when a PFC circuit in the frequency converter is in a working state, calculating the target input voltage of the compressor in real time;
calculating a target direct current bus voltage range of the PFC circuit according to the target input voltage of the compressor;
modulating the input voltage of the PFC circuit according to the target direct-current bus voltage range of the PFC circuit;
adjusting the direct-current bus voltage output by the PFC circuit so that the direct-current bus voltage output by the PFC circuit is within a target direct-current bus voltage range of the PFC circuit and within a preset actual direct-current bus voltage range of the PFC circuit;
outputting the regulated direct current bus voltage output by the PFC circuit to the compressor so as to drive the compressor to operate;
the modulating the input voltage of the PFC circuit according to the target dc bus voltage range of the PFC circuit specifically includes:
when the lower limit value of the target direct-current bus voltage range of the PFC circuit meets a preset first condition, modulating the input voltage of the PFC circuit in the whole period of the input voltage of the PFC circuit;
wherein the first condition is:
Figure FDA0003843286970000011
wherein, V dcref-L The lower limit value of the target direct current bus voltage range of the PFC circuit; vac is the input voltage of the PFC circuit;
when the upper limit value of the target direct-current bus voltage range of the PFC circuit meets a preset second condition, modulating the input voltage of the PFC circuit in a first time period, and turning off the PFC circuit in a second time period; the first time period is a time period in which the input voltage of the PFC circuit is less than or equal to the direct-current bus voltage output by the PFC circuit in the whole cycle of the input voltage of the PFC circuit; the second time period is a time period in which the input voltage of the PFC circuit is greater than the DC bus voltage output by the PFC circuit in the whole cycle of the input voltage of the PFC circuit;
the second condition is that:
Figure FDA0003843286970000021
wherein, V dcref-H The voltage range is the upper limit value of the target direct current bus voltage range of the PFC circuit; vac is the input voltage of the PFC circuit.
2. The method for controlling the frequency converter according to claim 1, wherein the calculating a target dc bus voltage range of the PFC circuit according to the target input voltage of the compressor specifically includes:
according to the target input voltage of the compressor, calculating an upper limit value of a target direct current bus voltage range of the PFC circuit through the following formula:
Figure FDA0003843286970000022
wherein, V dcref-H The voltage range is the upper limit value of the target direct current bus voltage range of the PFC circuit; v s For said compressorThe target input voltage of (1);
according to the target input voltage of the compressor, calculating a lower limit value of a target direct current bus voltage range of the PFC circuit through the following formula:
Figure FDA0003843286970000023
wherein, V dcref-L The lower limit value of the target direct current bus voltage range of the PFC circuit; v s Is a target input voltage for the compressor.
3. The method for controlling a frequency converter according to any one of claims 1 or 2, further comprising:
acquiring the input voltage of the PFC circuit;
and calculating the actual direct current bus voltage range of the PFC circuit according to the input voltage of the PFC circuit.
4. The method according to claim 3, wherein the calculating an actual dc bus voltage range of the PFC circuit according to the input voltage of the PFC circuit specifically includes:
when the input voltage of the PFC circuit does not meet a preset third condition, acquiring that the upper limit value of the actual direct-current bus voltage range of the PFC circuit is 350V, and the lower limit value of the actual direct-current bus voltage range of the PFC circuit is 280V;
when the input voltage of the PFC circuit meets a preset third condition, the upper limit value of the actual direct current bus voltage range of the PFC circuit is 350V, and the lower limit value of the actual direct current bus voltage range of the PFC circuit is obtained through calculation according to the following formula:
Figure FDA0003843286970000031
wherein, VDC min The lower limit value of the actual direct current bus voltage range of the PFC circuit is obtained; vac is the input voltage of the PFC circuit; the third condition is that:
Figure FDA0003843286970000032
5. a control apparatus of a frequency converter, characterized by comprising:
the compressor target input voltage calculation module is used for calculating the target input voltage of the compressor in real time when a PFC circuit in the frequency converter is in a working state;
the target direct current bus voltage range calculation module is used for calculating a target direct current bus voltage range of the PFC circuit according to the target input voltage of the compressor;
the voltage modulation module is used for modulating the input voltage of the PFC circuit according to the target direct-current bus voltage range of the PFC circuit;
the voltage adjusting module is used for adjusting the direct-current bus voltage output by the PFC circuit so that the direct-current bus voltage output by the PFC circuit is within a target direct-current bus voltage range of the PFC circuit and within a preset actual direct-current bus voltage range of the PFC circuit;
the direct current bus voltage output module is used for outputting the regulated direct current bus voltage output by the PFC circuit to the compressor so as to drive the compressor to operate;
the voltage modulation module specifically includes:
the first modulation unit is used for modulating the input voltage of the PFC circuit in the whole period of the input voltage of the PFC circuit when the lower limit value of the target direct-current bus voltage range of the PFC circuit meets a preset first condition;
wherein the first condition is:
Figure FDA0003843286970000041
wherein, V dcref-L The lower limit value of the target direct current bus voltage range of the PFC circuit; vac is the input voltage of the PFC circuit;
the second modulation unit is used for modulating the input voltage of the PFC circuit in a first time period and switching off the PFC circuit in a second time period when the upper limit value of the target direct-current bus voltage range of the PFC circuit meets a preset second condition; the first time period is a time period in which the input voltage of the PFC circuit is less than or equal to the direct-current bus voltage output by the PFC circuit in the whole cycle of the input voltage of the PFC circuit; the second time period is a time period in which the input voltage of the PFC circuit is greater than the DC bus voltage output by the PFC circuit in the whole cycle of the input voltage of the PFC circuit;
the second condition is that:
Figure FDA0003843286970000042
wherein, V dcref-H The voltage range is the upper limit value of the target direct current bus voltage range of the PFC circuit; vac is the input voltage of the PFC circuit.
6. The control device of the frequency converter according to claim 5, wherein the target dc bus voltage range calculating module specifically includes:
the upper limit value calculating unit is used for calculating an upper limit value of a target direct current bus voltage range of the PFC circuit according to a target input voltage of the compressor by the following formula:
Figure FDA0003843286970000043
wherein, V dcref-H The voltage range is the upper limit value of the target direct current bus voltage range of the PFC circuit; v s Is a target input voltage of the compressor；
The lower limit value calculating unit is used for calculating a lower limit value of a target direct current bus voltage range of the PFC circuit according to a target input voltage of the compressor by the following formula:
Figure FDA0003843286970000051
wherein, V dcref-L The lower limit value of the target direct current bus voltage range of the PFC circuit; v s Is a target input voltage for the compressor.
7. The control apparatus of a frequency converter according to any one of claims 5 or 6, further comprising:
the input voltage acquisition module is used for acquiring the input voltage of the PFC circuit;
and the actual direct current bus voltage range calculating module is used for calculating the actual direct current bus voltage range of the PFC circuit according to the input voltage of the PFC circuit.
8. The control device of the frequency converter according to claim 7, wherein the actual dc bus voltage range calculating module specifically includes:
the first voltage range calculating unit is used for obtaining that the upper limit value of the actual direct current bus voltage range of the PFC circuit is 350V and the lower limit value of the actual direct current bus voltage range of the PFC circuit is 280V when the input voltage of the PFC circuit does not accord with a preset third condition;
the second voltage range calculating unit is configured to, when the input voltage of the PFC circuit meets a preset third condition, obtain that an upper limit value of an actual dc bus voltage range of the PFC circuit is 350V, and calculate a lower limit value of the actual dc bus voltage range of the PFC circuit according to the following formula:
Figure FDA0003843286970000052
therein, VDC min The lower limit value of the actual direct current bus voltage range of the PFC circuit is obtained; vac is the input voltage of the PFC circuit; the third condition is that:
Figure FDA0003843286970000053
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