CN115632576A - Frequency converter soft start method and device, electronic equipment and readable storage medium - Google Patents

Frequency converter soft start method and device, electronic equipment and readable storage medium Download PDF

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Publication number
CN115632576A
CN115632576A CN202211381742.4A CN202211381742A CN115632576A CN 115632576 A CN115632576 A CN 115632576A CN 202211381742 A CN202211381742 A CN 202211381742A CN 115632576 A CN115632576 A CN 115632576A
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voltage
sampling
sub
sampling sub
power supply
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于安波
张良浩
陈栋建
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Gree Electric Appliances Inc of Zhuhai
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Gree Electric Appliances Inc of Zhuhai
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    • 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
    • H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
    • H02P1/02—Details of starting control
    • H02P1/04—Means for controlling progress of starting sequence in dependence upon time or upon current, speed, or other motor parameter
    • 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
    • H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
    • H02P1/02—Details of starting control
    • H02P1/022—Security devices, e.g. correct phase sequencing
    • 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)
  • Computer Security & Cryptography (AREA)
  • Rectifiers (AREA)

Abstract

The application relates to a frequency converter soft start method, a frequency converter soft start device, electronic equipment and a readable storage medium, wherein the method comprises the following steps: sampling the power supply voltage in real time to obtain a sampling voltage; judging whether the power supply voltage is in a positive half-cycle descending stage or not according to the sampling voltage; and if the power supply voltage is in the positive half-cycle descending stage, sending a conducting signal to the soft start module. By sampling the power supply voltage and positioning the power supply voltage at the positive half period reduction stage and conducting the thyristor when the power supply voltage is at the positive half period reduction stage, the thyristor can be prevented from being broken down by power grid fluctuation, and the reliability of soft start of the frequency converter is improved.

Description

Frequency converter soft start method and device, electronic equipment and readable storage medium
Technical Field
The present disclosure relates to the field of compressor control, and in particular, to a method and an apparatus for soft starting of a frequency converter, an electronic device, and a readable storage medium.
Background
Nowadays, the requirement of users on the integration level of a compressor is higher and higher, and particularly, a magnetic suspension compressor usually needs to integrate three important components, namely a magnetic suspension bearing controller, a frequency converter and a compressor controller; the internal integration level of the compressor is high, and the space is small; the existing frequency converter usually adopts a mode of combining a breaker with a charging resistor to realize pure hardware soft start, the volume of the breaker is too large to meet the space requirement of a compressor, and a soft start scheme controlled by a thyristor is usually adopted to replace the breaker, however, the thyristor is easily influenced by power grid fluctuation when being conducted, so that the soft start scheme is unreliable.
Disclosure of Invention
The application provides a frequency converter soft start method and device, electronic equipment and a readable storage medium, and aims to solve the technical problem that a thyristor is broken down by power grid fluctuation when the frequency converter is in soft start in the prior art.
In order to solve the above technical problem or at least partially solve the above technical problem, the present application provides a method for soft start of a frequency converter, the method comprising:
sampling the power supply voltage in real time to obtain a sampling voltage;
judging whether the power supply voltage is in a positive half-cycle descending stage or not according to the sampling voltage;
and if the power supply voltage is in the positive half-cycle descending stage, sending a conducting signal to the soft start module.
Optionally, the sampling voltage includes sampling sub-voltages corresponding to a plurality of consecutive sampling periods; the judging whether the power supply voltage is in a positive half-cycle descending phase according to the sampling voltage comprises the following steps:
continuously determining the stage characteristics of the power supply voltage according to each sampling sub-voltage;
and if the stage characteristics of the power supply voltage are sequentially determined as rising zero-crossing point characteristics, rising characteristics, vertex characteristics and falling characteristics, determining that the power supply voltage is in a positive half-cycle falling stage.
Optionally, the determining the phase characteristics of the supply voltage according to each of the sampling sub-voltages includes:
judging whether a first sampling sub-voltage is larger than 0 or not and whether a second sampling sub-voltage is smaller than 0 or not, wherein the first sampling sub-voltage is a sampling sub-voltage corresponding to the current sampling period, and the sampling period corresponding to the second sampling sub-voltage is separated from the current sampling period by a first preset number of sampling periods;
and if the first sampling sub-voltage is greater than 0 and the second sampling sub-voltage is less than 0, determining that the stage characteristic is an ascending zero-crossing characteristic.
Optionally, the determining the phase characteristics of the power supply voltage according to each of the sampling sub-voltages includes:
judging whether the first sampling sub-voltage is larger than the second sampling sub-voltage;
and if the first sampling sub-voltage is greater than the second sampling sub-voltage, determining that the phase characteristic corresponding to the current sampling period is a rising characteristic.
Optionally, the determining the phase characteristics of the power supply voltage according to each of the sampling sub-voltages includes:
judging whether a third sampling sub-voltage is greater than a fourth sampling sub-voltage and a first sampling sub-voltage, and whether the third sampling sub-voltage is greater than a preset peak voltage, wherein a sampling period corresponding to the third sampling sub-voltage is separated from a current sampling period by a second preset number of sampling periods, a second preset number of sampling periods are separated between the fourth sampling sub-voltage and a sampling period corresponding to the third sampling sub-voltage, and the sampling period corresponding to the third sampling sub-voltage is later than the sampling period corresponding to the fourth sampling sub-voltage;
and if the third sampling sub-voltage is greater than the fourth sampling sub-voltage and the first sampling sub-voltage, and the third sampling sub-voltage is greater than a preset peak voltage, determining that the stage characteristic is a peak characteristic.
Optionally, the determining the phase characteristics of the supply voltage according to each of the sampling sub-voltages includes:
judging whether the first sampling sub-voltage is smaller than the second sampling sub-voltage, whether the fifth sampling sub-voltage is smaller than the third sampling sub-voltage, and whether the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is smaller than a preset slope threshold value, wherein a sampling period corresponding to the fifth sampling sub-voltage is separated from a current sampling period by a third preset number of sampling periods, and a sampling period corresponding to the sixth sampling sub-voltage is separated from the current sampling period by a fourth preset number of sampling periods;
and if the first sampling sub-voltage is smaller than the second sampling sub-voltage, the fifth sampling sub-voltage is smaller than the third sampling sub-voltage, and the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is smaller than a preset slope threshold, determining that the stage characteristic is a descending characteristic.
Optionally, the sending the control signal to the thyristor corresponding to the supply voltage includes:
acquiring bus voltage, and calculating a voltage difference value obtained by subtracting the bus voltage from a first sampling sub-voltage;
judging whether an ascending zero-crossing feature accumulated value is larger than a preset ascending zero-crossing threshold value, whether the voltage difference value is larger than 0 and whether the voltage difference value is smaller than a preset difference value, wherein the ascending zero-crossing feature accumulated value is the number of sampling cycles for keeping the stage feature as the ascending zero-crossing feature;
and if the cumulative value of the rising zero-crossing point characteristics is greater than a preset rising zero-crossing point threshold value, the voltage difference value is greater than 0, and the voltage difference value is smaller than a preset difference value, sending a conducting signal as the control signal to the soft start module.
In order to achieve the above object, the present invention further provides a soft start device for a frequency converter, including:
the first sampling module is used for sampling the power supply voltage in real time to obtain a sampling voltage;
the first judgment module is used for judging whether the power supply voltage is in a positive half-period descending stage or not according to the sampling voltage;
the first sending module is used for sending a conducting signal to the soft start module if the power supply voltage is in a positive half-cycle descending stage.
To achieve the above object, the present invention further provides an electronic device, which includes a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the frequency converter soft start method as described above.
To achieve the above object, the present invention further provides a computer readable storage medium, having a computer program stored thereon, where the computer program, when executed by a processor, implements the steps of the frequency converter soft start method as described above.
According to the frequency converter soft start method, the frequency converter soft start device, the electronic equipment and the readable storage medium, the power supply voltage is sampled in real time to obtain the sampling voltage; judging whether the power supply voltage is in a positive half-cycle descending stage or not according to the sampling voltage; and if the power supply voltage is in the positive half-cycle descending stage, sending a conducting signal to the soft start module. By sampling the power supply voltage and positioning the power supply voltage at the positive half period reduction stage and conducting the thyristor when the power supply voltage is at the positive half period reduction stage, the thyristor can be prevented from being broken down by power grid fluctuation, and the reliability of soft start of the frequency converter is improved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.
Fig. 1 is a schematic flow chart of a soft start method of a frequency converter according to a first embodiment of the present invention;
FIG. 2 is a schematic diagram of a compressor control circuit applied to the soft start method of the inverter according to the present invention;
FIG. 3 is a schematic view of the overall process of the soft start method of the frequency converter according to the present invention;
fig. 4 is a schematic diagram of a module structure of the electronic device of the present invention.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In order to make the technical solutions of the present application better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making any creative effort shall fall within the protection scope of the present application.
The invention provides a frequency converter soft start method, referring to fig. 1, fig. 1 is a schematic flow chart of a first embodiment of the frequency converter soft start method of the invention, and the method comprises the following steps:
step S10, sampling the power supply voltage in real time to obtain a sampling voltage;
fig. 2 is a schematic structural diagram of the compressor control circuit, and it should be noted that fig. 2 only shows a structure of the compressor control circuit in an application scenario, and in practical application, the structure of the compressor control circuit may be adjusted based on actual needs.
The compressor control circuit comprises a controller, a soft start module and an IGBT inverter bridge; the soft start module is a thyristor half-controlled rectifier bridge, three input ends of the thyristor half-controlled rectifier bridge are respectively connected with a three-phase power supply, an output end of the thyristor half-controlled rectifier bridge is connected with an input end of an inverter bridge as a direct-current bus voltage end, and a three-phase output end of the IGBT inverter bridge is respectively connected with a three-phase power source end of the compressor; the controller comprises a sampling circuit, a Digital Signal Processing (DSP), a thyristor drive circuit and an Insulated Gate Bipolar Transistor (IGBT) drive circuit, wherein a sampling end of the sampling circuit is respectively connected with a three-phase power supply and a direct-current bus voltage end, an output end of the sampling circuit is connected with the DSP, an output end of the DSP is respectively connected with a control end of the thyristor drive circuit and a control end of the IGBT drive circuit, an output end of the thyristor drive circuit is respectively connected with control ends of thyristors in a thyristor half-controlled rectifier bridge, and an output end of the IGBT drive circuit is respectively connected with gate poles of the IGBTs in the IGBT inverter bridge.
The DSP controls the conduction of the thyristor semi-controlled rectifier bridge and the IGBT inverter bridge by acquiring the sampling of the three-phase power supply and the DC bus voltage by the sampling circuit so as to realize the control of the compressor; it can be understood that the specific control mode for the IGBT inverter bridge may be set based on actual needs. In the embodiment, the thyristor semi-controlled rectifier bridge and the IGBT inverter bridge are simultaneously controlled by the DSP, so that one soft start controller can be reduced, the number of chips is reduced, the occupied space is reduced, and the cooperativity of soft start control and compressor control is improved.
It should be noted that in this embodiment, the soft start of the frequency converter adopts a thyristor half-controlled rectifier bridge, and in practical application, the frequency converter can also be set as other rectifier devices, such as a diode rectifier bridge; the inverter circuit in this embodiment adopts an IGBT inverter bridge, and may be configured as other inverter devices in practical application, such as a MOS inverter bridge.
The sampled voltage in this embodiment is a line voltage, which includes a three-phase supply voltage, i.e., a U-phase voltage V U Voltage of V phase V V And W-phase voltage V W Besides, it can also add the DC bus voltage u dc Carrying out detection; the sampling mode for the three-phase power supply voltage and the direct-current bus voltage can be set based on practical application scenes, such as a current transformer, a voltage sensor and the like.
It should be noted that the sampling frequency of the voltage may be set based on actual needs, and in this embodiment and subsequent embodiments, the sampling frequency is 10kHz, and other frequencies may be performed by analogy, and are not described again.
Step S20, judging whether the power supply voltage is in a positive half-cycle descending stage or not according to the sampling voltage;
it will be appreciated that the supply voltage is alternating current, i.e. the supply voltage appears sinusoidal over time, and therefore comprises a positive half-cycle rising phase, a positive half-cycle falling phase, a negative half-cycle falling phase and a negative half-cycle rising phase; when the supply voltage is in different sine wave phases, the characteristics of the sampled voltage are different, and therefore, the sine wave phase in which the supply voltage is currently located can be determined by sampling the voltage.
And step S30, if the power supply voltage is in a positive half period descending stage, sending a conducting signal to a soft start module.
It can be understood that when the supply voltage is in the rise phase, including the positive half cycle rise phase and the negative half cycle rise phase, the thyristor conducts and is easily punctured by the power grid fluctuation, and when the supply voltage is in the negative half cycle, the thyristor is cut off, so the thyristor can meet the conduction in the positive half cycle, and meanwhile, the thyristor can avoid the power grid fluctuation from causing too large influence in the fall phase, so the thyristor is controlled in the positive half cycle fall phase to ensure the system stability while conducting.
According to the embodiment, the power supply voltage is sampled and positioned at the positive half period descending stage, and the thyristor is conducted when the power supply voltage is at the positive half period descending stage, so that the thyristor can be prevented from being broken down by power grid fluctuation, and the reliability of soft start of the frequency converter is improved.
Further, referring to fig. 3 together subsequently, in a second embodiment of the soft start method of the frequency converter according to the present invention based on the first embodiment of the present invention, the sampling voltage includes sampling sub-voltages corresponding to a plurality of consecutive sampling periods; the step S20 includes the steps of:
step S21, continuously determining the stage characteristics of the power supply voltage according to each sampling sub-voltage;
the phase characteristics are used for reflecting the characteristics of the sine wave phase in which the power supply voltage is currently positioned; it should be noted that, phases of voltages of the three-phase power supplies are different, and therefore, a sine wave phase where a supply voltage corresponding to the voltage of the three-phase power supply is located is not necessarily the same, and therefore, in this embodiment, thyristors corresponding to the three-phase power supply in the thyristor half-controlled rectifier bridge are independently controlled, that is, the thyristor connected to the U-phase power supply is controlled by the supply voltage of the U-phase power supply, the thyristor connected to the V-phase power supply is controlled by the supply voltage of the V-phase power supply, and the thyristor connected to the W-phase power supply is controlled by the supply voltage of the W-phase power supply; in this embodiment, the U-phase power supply voltage is used for illustration, and the other phase power supply voltages can be performed by analogy, which is not described again.
It can be understood that, based on the difference of the sampling frequency, the length of the corresponding sampling period is also different, and the length can be specifically determined according to the actually set sampling frequency; in this embodiment, continuous sampling is performed based on a sampling period, and the obtained sampling voltage includes sampling sub-voltages obtained by a plurality of continuous sampling periods; it should be noted that the number of the sampling sub-voltages may be set based on actual precision requirements, in this embodiment, the number of the sampling sub-voltages is illustrated as 7, and other scenarios may be performed by analogy. It should be noted that, this embodiment is implemented by a method of continuously cycling off, and in practical application, other implementation methods may be adopted.
The sampling voltages comprise 7 sampling sub-voltages of u0, u1, u2, u3, u4, u5, u6 and the like, wherein u6 is the sampling sub-voltage obtained in the latest sampling period, u5 is the sampling sub-voltage obtained in the previous sampling period of the latest sampling period, and by analogy, u0 is the sampling sub-voltage obtained 6 sampling periods away from the latest sampling period.
On this basis, if a new sampling sub-voltage un is sampled in a new sampling period, each sampling sub-voltage is updated, specifically, the sampling sub-voltage in the previous sampling period is updated to the sampling sub-voltage in the next sampling period, and meanwhile, the sampling sub-voltage sampled earliest is removed, and the number of the sampling sub-voltages is kept to be 7:
u0＝u1；u1＝u2；u2＝u3；u3＝u4；u4＝u5；u5＝u6；u6＝un；
for convenience of subsequent description, u6 corresponds to the first sampling sub-voltage, u2 corresponds to the second sampling sub-voltage, u3 corresponds to the third sampling sub-voltage, u0 corresponds to the fourth sampling sub-voltage, u5 corresponds to the fifth sampling sub-voltage, and u4 corresponds to the sixth sampling sub-voltage.
In different sine wave stages, the characteristics or trends of the power supply voltage are different, and the sine wave stage where the power supply voltage is located can be determined based on the characteristics and the trends of the power supply voltage; specifically, the method comprises the following steps:
step S211, judging whether the first sampling sub-voltage is greater than 0 and whether the second sampling sub-voltage is less than 0, wherein the first sampling sub-voltage is the sampling sub-voltage corresponding to the current sampling period, and the sampling period corresponding to the second sampling sub-voltage is separated from the current sampling period by a first preset number of sampling periods;
step S212, if the first sampling sub-voltage is greater than 0 and the second sampling sub-voltage is less than 0, determining that the stage characteristic is a rising zero-crossing point characteristic;
if the first sampling sub-voltage is less than or equal to 0 or the second sampling sub-voltage is greater than or equal to 0, the phase characteristic is not a rising zero-crossing characteristic.
Since the sampling period of the first sampling sub-voltage is after the second sampling sub-voltage, when the first sampling sub-voltage is greater than 0 and the second sampling sub-voltage is less than 0, the zero crossing point of the power supply voltage is indicated, and at the same time, the first sampling sub-voltage is greater than the second sampling sub-voltage, the power supply voltage is in an ascending trend, and therefore, the stage characteristic of the power supply voltage can be determined to be an ascending zero crossing point characteristic. It should be noted that, theoretically, when the first sampling sub-voltage is greater than 0 and the fifth sampling sub-voltage, that is, u5 is less than 0, the phase characteristic of the power supply voltage may be considered as an ascending zero-crossing point characteristic, but there is power grid fluctuation or interference of other factors in practical application, which causes small-amplitude up-and-down fluctuation, at this time, if the sampling sub-voltages of two adjacent sampling periods are directly used for judgment, erroneous judgment is easily caused, in this embodiment, the sampling period corresponding to the second sampling sub-voltage is separated from the current sampling period by a first preset number of sampling periods, for example, u6 and u2 are used, the first preset number is 3, and the distance between the two sampling periods is long, so that erroneous judgment caused by power grid fluctuation or interference of other factors can be avoided; the reason for setting the subsequent preset number is the same, and the detailed description is omitted; it should be noted that the specific numerical value of each preset number can be set based on actual needs.
Step S213, determining whether the first sampling sub-voltage is greater than the second sampling sub-voltage;
step S214, if the first sampling sub-voltage is greater than the second sampling sub-voltage, determining that the phase characteristic corresponding to the current sampling period is an ascending characteristic;
if the first sampling sub-voltage is less than or equal to the second sampling sub-voltage, the phase characteristic is not a rising characteristic.
Since the sampling period of the first sampling sub-voltage is after the second sampling sub-voltage, the first sampling sub-voltage is greater than the second sampling sub-voltage, indicating that the supply voltage is in an ascending trend, whereby the phase characteristic of the supply voltage can be determined as an ascending characteristic.
Step S215, determining whether a third sampling sub-voltage is greater than a fourth sampling sub-voltage and a first sampling sub-voltage, and whether the third sampling sub-voltage is greater than a preset top voltage, where a sampling period corresponding to the third sampling sub-voltage is separated from a current sampling period by a second preset number of sampling periods, a sampling period corresponding to the fourth sampling sub-voltage is separated from a sampling period corresponding to the third sampling sub-voltage by a second preset number of sampling periods, and a sampling period corresponding to the third sampling sub-voltage is later than a sampling period corresponding to the fourth sampling sub-voltage;
step S216, if a third sampling sub-voltage is greater than a fourth sampling sub-voltage and the first sampling sub-voltage, and the third sampling sub-voltage is greater than a preset vertex voltage, determining that the stage feature is a vertex feature;
and if the third sampling sub-voltage is less than or equal to the fourth sampling sub-voltage or the first sampling sub-voltage or the third sampling sub-voltage is less than or equal to a preset peak voltage, determining that the stage characteristic is a peak characteristic.
Because the sampling period of the third sampling sub-voltage is behind the fourth sampling sub-voltage and in front of the first sampling sub-voltage, when the third sampling sub-voltage is greater than the fourth sampling sub-voltage, the power supply voltage is in an ascending trend, when the third sampling sub-voltage is greater than the first sampling sub-voltage, the power supply voltage is in a descending trend, when the ascending trend is detected at first and the descending trend is detected later, the power supply voltage is considered to pass through the vertex. It should be noted that the preset peak voltage may be set based on actual needs, and for example, the line voltage is 380V, and the preset peak voltage may be set to 430V.
Step S217, judging whether the first sampling sub-voltage is smaller than the second sampling sub-voltage, whether the fifth sampling sub-voltage is smaller than the third sampling sub-voltage, and whether the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is smaller than a preset slope threshold value, wherein a sampling period corresponding to the fifth sampling sub-voltage is separated from the current sampling period by a third preset number of sampling periods, and a sampling period corresponding to the sixth sampling sub-voltage is separated from the current sampling period by a fourth preset number of sampling periods;
step S218, if the first sampling sub-voltage is less than the second sampling sub-voltage, the fifth sampling sub-voltage is less than the third sampling sub-voltage, and a difference between the sixth sampling sub-voltage and the first sampling sub-voltage is less than a preset slope threshold, determining that the stage characteristic is a falling characteristic;
and if the first sampling sub-voltage is greater than or equal to the second sampling sub-voltage, or the fifth sampling sub-voltage is greater than or equal to the third sampling sub-voltage, or the difference of the sixth sampling sub-voltage minus the first sampling sub-voltage is greater than or equal to a preset slope threshold, determining that the stage characteristic is not a falling characteristic.
Because the sampling period of the first sampling sub-voltage is positioned after the second sampling sub-voltage, when the first sampling sub-voltage is smaller than the second sampling sub-voltage, the power supply voltage has a descending trend, and similarly, when the fifth sampling sub-voltage is smaller than the third sampling sub-voltage, the power supply voltage is determined to have a descending trend; in order to avoid the influence of rapid voltage drop caused by power grid fluctuation or other factor interference on the judgment of the sine wave stage, a preset slope threshold value is set, if the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is smaller than the preset slope threshold value, the power supply voltage is considered to be reduced too fast, probably caused by power grid fluctuation or other factor interference, and at the moment, the stage characteristic of the power supply voltage is not determined to be a reduction characteristic; and if the difference of the sixth sampling sub-voltage minus the first sampling sub-voltage is smaller than a preset slope threshold, the power supply voltage is considered to accord with the normal descending characteristic of the sine wave, and the stage characteristic of the power supply voltage is determined to be the descending characteristic.
And S22, if the stage characteristics of the power supply voltage are sequentially determined as rising zero-crossing point characteristics, rising characteristics, vertex characteristics and falling characteristics, determining that the power supply voltage is in a positive half-cycle falling stage.
It should be noted that, because different stages of the sine wave have a sequential relationship, that is, starting with the rising zero-crossing point feature, the stage features presented in sequence are a rising feature, a vertex feature, a falling zero-crossing point feature, a falling feature, a negative vertex feature, a rising feature, and a rising zero-crossing point feature; thus, it is only possible to accurately determine that the supply voltage is in the positive half-cycle falling phase if a rising zero-crossing feature, a rising feature, a top feature and a falling feature are detected consecutively in sequence. Specifically, flag bits are set for different stage features, each flag bit is reset to 0 at the beginning, detection of rising zero-crossing point features is started, after the rising zero-crossing point features are detected, detection of the rising features is started after the rising zero-crossing point flag position 1 and the rising zero-crossing point flag position 1 are detected, after the rising features are detected, detection of vertex features is started after the rising flag position 1 and the rising flag position 1 are detected, after the vertex features are detected, detection of the falling features is started after the vertex flag position 1 and the vertex flag position 1 are detected, after the falling features are detected, the power supply voltage is determined to be in a positive half-cycle falling stage after the falling flag position 1 and the falling flag position 1 are detected.
It should be noted that, when detecting a feature of a certain stage, only the detected feature of the stage is reacted, and when detecting an ascending feature, if a feature of another stage other than the ascending feature is detected, the feature is not reacted, and only after detecting the ascending feature, the ascending flag is set to 1, and the feature of the subsequent stage is detected. It should be noted that, in this embodiment, it is required to determine that the power supply voltage is in a positive half cycle falling stage, and once it is detected that the power supply voltage is in a next half cycle, that is, when a falling zero-crossing feature is detected, it is considered that the thyristor cannot be turned on in the current sine wave cycle, at this time, all flag bits are reset to 0, and detection of a rising zero-crossing feature is performed again.
It should be noted that, because the change of the features in different stages is continuous, in some embodiments, the stage features to be detected may be selected, for example, in this embodiment, the rising zero-crossing point feature, the rising feature, the vertex feature, and the falling feature are detected in sequence; in other embodiments, the stage features to be detected may be set to detect the ascending feature, the vertex feature, and the descending feature in sequence, or to detect the vertex feature and the descending feature in sequence, or to detect the ascending zero-crossing point feature, the vertex feature, and the descending feature in sequence; i.e. by different combinations of phase characteristics, it is sufficient to determine that the supply voltage is in the positive half-cycle falling phase when the falling characteristic is detected.
The embodiment can accurately determine the sine wave phase of the power supply voltage, and further determine whether the power supply voltage is in the positive half-cycle descending phase.
Further, in a third embodiment of the method for soft starting a frequency converter according to the present invention based on the first embodiment of the present invention, the step S30 includes the steps of:
step S31, acquiring bus voltage, and calculating a voltage difference value of the first sampling sub-voltage minus the bus voltage;
step S32, judging whether an ascending zero-crossing feature accumulated value is larger than a preset ascending zero-crossing threshold value, whether the voltage difference value is larger than 0 and whether the voltage difference value is smaller than a preset difference value, wherein the ascending zero-crossing feature accumulated value is the sampling period number for keeping the stage feature as the ascending zero-crossing feature;
step S33, if the rising zero-crossing feature accumulated value is larger than a preset rising zero-crossing threshold value, the voltage difference value is larger than 0, and the voltage difference value is smaller than a preset difference value, sending a conducting signal as the control signal to the soft start module;
and if the cumulative value of the rising zero-crossing feature is smaller than or equal to a preset rising zero-crossing threshold value, or the voltage difference value is smaller than or equal to 0, or the voltage difference value is larger than or equal to a preset difference value, sending a cut-off signal serving as the control signal to the soft start module.
When the rising zero-crossing point feature is detected, adding 1 to the rising zero-crossing point feature accumulated value, and then adding 1 to the rising zero-crossing point feature accumulated value after each sampling period; and when the rising zero-crossing point flag bit is reset to 0, resetting the rising zero-crossing point feature accumulated value to 0.
In order to avoid power grid fluctuation or interference of other factors, a preset rising zero-crossing point threshold value is set, and the possibility that the power supply voltage is positioned in the last half period of descending stage is considered to exist only when a certain time is reached after the rising zero-crossing point characteristic is detected; the specific preset rising zero-crossing threshold value may be set based on actual needs, such as 45.
It can be understood that when the droop characteristic is detected, the first sampling sub-voltage is continuously decreased, and the bus voltage is fixed, so that the voltage difference is continuously decreased, and when the voltage difference is between 0 and a preset difference, a turn-on signal is output to the thyristor. It can be understood that the thyristor is triggered to be turned on only by the turn-on signal, and is turned off automatically when reverse voltage is applied to the thyristor, so that the turn-on time of the thyristor can be set by setting a specific value of the preset difference value; the specific preset difference value can be set based on actual needs.
The embodiment can accurately set the conduction time of the thyristor.
It should be noted that, for simplicity of description, the above-mentioned method embodiments are described as a series of acts or combination of acts, but those skilled in the art will recognize that the present application is not limited by the order of acts described, as some steps may occur in other orders or concurrently depending on the application. Further, those skilled in the art will recognize that the embodiments described in this specification are preferred embodiments and that acts or modules referred to are not necessarily required for this application.
Through the description of the foregoing embodiments, it is clear to those skilled in the art that the method according to the foregoing embodiments may be implemented by software plus a necessary general hardware platform, and certainly may also be implemented by hardware, but the former is a better implementation mode in many cases. Based on such understanding, the technical solutions of the present application may be embodied in the form of a software product, which is stored in a storage medium (e.g., ROM/RAM, magnetic disk, optical disk) and includes instructions for enabling a terminal device (e.g., a mobile phone, a computer, a server, or a network device) to execute the method according to the embodiments of the present application.
The present application further provides a frequency converter soft start apparatus for implementing the frequency converter soft start method, where the frequency converter soft start apparatus includes:
the first sampling module is used for sampling the power supply voltage in real time to obtain a sampling voltage;
the first judgment module is used for judging whether the power supply voltage is in a positive half period reduction stage or not according to the sampling voltage;
the first sending module is used for sending a conducting signal to the soft start module if the power supply voltage is in a positive half-cycle descending stage.
The soft start device of the frequency converter samples the power supply voltage and positions the power supply voltage in the positive half period reduction stage, and the thyristor is conducted when the power supply voltage is in the positive half period reduction stage, so that the thyristor can be prevented from being broken down by power grid fluctuation, and the soft start reliability of the frequency converter is improved.
It should be noted that the first sampling module in this embodiment may be configured to execute step S10 in this embodiment, the first determining module in this embodiment may be configured to execute step S20 in this embodiment, and the first sending module in this embodiment may be configured to execute step S30 in this embodiment.
Further, the sampling voltage comprises sampling sub-voltages corresponding to a plurality of continuous sampling periods; the first judging module comprises:
the first determining unit is used for continuously determining the stage characteristics of the power supply voltage according to each sampling sub-voltage;
a second determining unit, configured to determine that the supply voltage is in a positive half-cycle falling phase if the phase characteristics of the supply voltage are sequentially determined as a rising zero-crossing point characteristic, a rising characteristic, a vertex characteristic, and a falling characteristic.
Further, the first determination unit includes:
the first judging subunit is configured to judge whether the first sampling sub-voltage is greater than 0 and whether the second sampling sub-voltage is less than 0, where the first sampling sub-voltage is a sampling sub-voltage corresponding to a current sampling period, and a sampling period corresponding to the second sampling sub-voltage is separated from the current sampling period by a first preset number of sampling periods;
and the first determining subunit is used for determining that the stage characteristic is a rising zero-crossing characteristic if the first sampling sub-voltage is greater than 0 and the second sampling sub-voltage is less than 0.
Further, the first determination unit includes:
the second judging subunit is used for judging whether the first sampling sub-voltage is greater than the second sampling sub-voltage;
and the second determining subunit is configured to determine that the phase feature corresponding to the current sampling period is an ascending feature if the first sampling sub-voltage is greater than the second sampling sub-voltage.
Further, the first determination unit includes:
a third determining subunit, configured to determine whether a third sampling sub-voltage is greater than a fourth sampling sub-voltage and the first sampling sub-voltage, and whether the third sampling sub-voltage is greater than a preset vertex voltage, where a sampling period corresponding to the third sampling sub-voltage is separated from a current sampling period by a second preset number of sampling periods, a sampling period corresponding to the fourth sampling sub-voltage is separated from a sampling period corresponding to the third sampling sub-voltage by a second preset number of sampling periods, and a sampling period corresponding to the third sampling sub-voltage is later than a sampling period corresponding to the fourth sampling sub-voltage;
and the third determining subunit is configured to determine that the stage feature is a vertex feature if the third sampling sub-voltage is greater than a fourth sampling sub-voltage and the first sampling sub-voltage, and the third sampling sub-voltage is greater than a preset vertex voltage.
Further, the first determination unit includes:
a fourth judging subunit, configured to judge whether the first sampling sub-voltage is smaller than the second sampling sub-voltage, whether a fifth sampling sub-voltage is smaller than a third sampling sub-voltage, and whether a difference between a sixth sampling sub-voltage and the first sampling sub-voltage is smaller than a preset slope threshold, where a sampling period corresponding to the fifth sampling sub-voltage is separated from a current sampling period by a third preset number of sampling periods, and a sampling period corresponding to the sixth sampling sub-voltage is separated from the current sampling period by a fourth preset number of sampling periods;
and the fourth determining subunit is configured to determine that the stage characteristic is a falling characteristic if the first sampling sub-voltage is less than the second sampling sub-voltage, the fifth sampling sub-voltage is less than the third sampling sub-voltage, and a difference between the sixth sampling sub-voltage and the first sampling sub-voltage is less than a preset slope threshold.
Further, the first transmitting module includes:
the first acquisition unit is used for acquiring bus voltage and calculating a voltage difference value obtained by subtracting the bus voltage from the first sampling sub-voltage;
a first judging unit, configured to judge whether an ascending zero-crossing feature accumulated value is greater than a preset ascending zero-crossing threshold, whether the voltage difference value is greater than 0, and whether the voltage difference value is smaller than a preset difference value, where the ascending zero-crossing feature accumulated value is a number of sampling cycles for keeping the stage feature as the ascending zero-crossing feature;
the first sending unit is configured to send a conducting signal to the soft start module as the control signal if the rising zero-crossing feature accumulated value is greater than a preset rising zero-crossing threshold value, the voltage difference value is greater than 0, and the voltage difference value is smaller than a preset difference value.
It should be noted that the modules described above are the same as examples and application scenarios realized by corresponding steps, but are not limited to what is disclosed in the foregoing embodiments. The modules may be implemented by software as part of the apparatus, or may be implemented by hardware, where the hardware environment includes a network environment.
Referring to fig. 4, the electronic device may include components such as a communication module 10, a memory 20, and a processor 30 in a hardware structure. In the electronic device, the processor 30 is connected to the memory 20 and the communication module 10, respectively, the memory 20 stores thereon a computer program, which is executed by the processor 30 at the same time, and when executed, implements the steps of the above-mentioned method embodiments.
The communication module 10 may be connected to an external communication device through a network. The communication module 10 may receive a request from an external communication device, and may also send a request, an instruction, and information to the external communication device, where the external communication device may be other electronic devices, a server, or an internet of things device, such as a television.
The memory 20 may be used to store software programs as well as various data. The memory 20 may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application program required by at least one function (for example, sampling a power supply voltage in real time to obtain a sampled voltage), and the like; the storage data area may include a database, and the storage data area may store data or information created according to use of the system, or the like. Further, the memory 20 may include high speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other volatile solid state storage device.
The processor 30, which is a control center of the electronic device, connects various parts of the entire electronic device using various interfaces and lines, and performs various functions of the electronic device and processes data by operating or executing software programs and/or modules stored in the memory 20 and calling data stored in the memory 20, thereby integrally monitoring the electronic device. Processor 30 may include one or more processing units; alternatively, the processor 30 may integrate an application processor, which mainly handles operating systems, user interfaces, application programs, etc., and a modem processor, which mainly handles wireless communications. It will be appreciated that the modem processor described above may not be integrated into the processor 30.
Although not shown in fig. 4, the electronic device may further include a circuit control module, which is connected to a power supply to ensure the normal operation of other components. Those skilled in the art will appreciate that the electronic device configuration shown in fig. 4 does not constitute a limitation of the electronic device and may include more or fewer components than those shown, or some components may be combined, or a different arrangement of components.
The invention also proposes a computer-readable storage medium on which a computer program is stored. The computer-readable storage medium may be the Memory 20 in the electronic device in fig. 4, and may also be at least one of a ROM (Read-Only Memory)/RAM (Random Access Memory), a magnetic disk, and an optical disk, where the computer-readable storage medium includes instructions for enabling a terminal device (which may be a television, an automobile, a mobile phone, a computer, a server, a terminal, or a network device) having a processor to execute the method according to the embodiments of the present invention.
In the present invention, the terms "first", "second", "third", "fourth" and "fifth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance, and those skilled in the art can understand the specific meanings of the above terms in the present invention according to specific situations.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although the embodiment of the present invention has been shown and described, the scope of the present invention is not limited thereto, it should be understood that the above embodiment is illustrative, and not restrictive, and that those skilled in the art can make changes, modifications and substitutions to the above embodiment within the scope of the present invention, and that these changes, modifications and substitutions are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (10)

1. A soft start method of a frequency converter is characterized by comprising the following steps:
sampling the power supply voltage in real time to obtain a sampling voltage;
judging whether the power supply voltage is in a positive half-cycle descending stage or not according to the sampling voltage;
and if the power supply voltage is in the positive half-cycle descending stage, sending a conducting signal to the soft start module.
2. The soft start method of a frequency converter according to claim 1, wherein the sampling voltage comprises sampling sub-voltages corresponding to a plurality of consecutive sampling periods; the judging whether the power supply voltage is in a positive half-cycle descending phase according to the sampling voltage comprises the following steps:
continuously determining the stage characteristics of the power supply voltage according to each sampling sub-voltage;
and if the stage characteristics of the power supply voltage are sequentially determined as rising zero-crossing point characteristics, rising characteristics, vertex characteristics and falling characteristics, determining that the power supply voltage is in a positive half-cycle falling stage.
3. The method of claim 2, wherein said determining phase characteristics of said supply voltage from each of said sampled sub-voltages comprises:
judging whether a first sampling sub-voltage is larger than 0 or not and whether a second sampling sub-voltage is smaller than 0 or not, wherein the first sampling sub-voltage is a sampling sub-voltage corresponding to the current sampling period, and the sampling period corresponding to the second sampling sub-voltage is separated from the current sampling period by a first preset number of sampling periods;
and if the first sampling sub-voltage is greater than 0 and the second sampling sub-voltage is less than 0, determining that the stage characteristic is an ascending zero-crossing characteristic.
4. The method of claim 2, wherein said determining phase characteristics of said supply voltage from each of said sampled sub-voltages comprises:
judging whether the first sampling sub-voltage is larger than the second sampling sub-voltage or not;
and if the first sampling sub-voltage is greater than the second sampling sub-voltage, determining that the phase characteristic corresponding to the current sampling period is a rising characteristic.
5. The method of claim 2, wherein said determining phase characteristics of said supply voltage from each of said sampled sub-voltages comprises:
judging whether a third sampling sub-voltage is greater than a fourth sampling sub-voltage and a first sampling sub-voltage, and whether the third sampling sub-voltage is greater than a preset peak voltage, wherein a sampling period corresponding to the third sampling sub-voltage is separated from a current sampling period by a second preset number of sampling periods, a second preset number of sampling periods are separated between the fourth sampling sub-voltage and a sampling period corresponding to the third sampling sub-voltage, and the sampling period corresponding to the third sampling sub-voltage is later than the sampling period corresponding to the fourth sampling sub-voltage;
and if the third sampling sub-voltage is greater than the fourth sampling sub-voltage and the first sampling sub-voltage, and the third sampling sub-voltage is greater than a preset peak voltage, determining that the stage characteristic is a peak characteristic.
6. The method of claim 2, wherein said determining phase characteristics of said supply voltage from each of said sampled sub-voltages comprises:
judging whether the first sampling sub-voltage is smaller than the second sampling sub-voltage, whether the fifth sampling sub-voltage is smaller than the third sampling sub-voltage, and whether the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is smaller than a preset slope threshold value, wherein a sampling period corresponding to the fifth sampling sub-voltage is separated from a current sampling period by a third preset number of sampling periods, and a sampling period corresponding to the sixth sampling sub-voltage is separated from the current sampling period by a fourth preset number of sampling periods;
and if the first sampling sub-voltage is smaller than the second sampling sub-voltage, the fifth sampling sub-voltage is smaller than the third sampling sub-voltage, and the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is smaller than a preset slope threshold, determining that the stage characteristic is a descending characteristic.
7. The method of claim 2, wherein said sending a turn-on signal to a soft start module comprises:
acquiring bus voltage, and calculating a voltage difference value obtained by subtracting the bus voltage from the first sampling sub-voltage;
judging whether the cumulative value of the ascending zero-crossing point features is larger than a preset ascending zero-crossing point threshold value, whether the voltage difference value is larger than 0 and whether the voltage difference value is smaller than a preset difference value, wherein the cumulative value of the ascending zero-crossing point features is the number of sampling cycles for keeping the stage features as the ascending zero-crossing point features;
and if the cumulative value of the rising zero-crossing feature is greater than a preset rising zero-crossing threshold value, the voltage difference value is greater than 0, and the voltage difference value is smaller than a preset difference value, sending a conduction signal as the control signal to the soft start module.
8. A frequency converter soft start device is characterized in that the compressor frequency converter control device comprises:
the first sampling module is used for sampling the power supply voltage in real time to obtain a sampling voltage;
the first judgment module is used for judging whether the power supply voltage is in a positive half-period descending stage or not according to the sampling voltage;
the first sending module is used for sending a conducting signal to the soft start module if the power supply voltage is in a positive half-cycle descending stage.
9. An electronic device, characterized in that the electronic device comprises a memory, a processor and a computer program stored on the memory and executable on the processor, which computer program, when executed by the processor, carries out the steps of the frequency converter soft start method according to any one of claims 1 to 7.
10. A computer-readable storage medium, characterized in that a computer program is stored on the computer-readable storage medium, which computer program, when being executed by a processor, carries out the steps of the frequency converter soft start method according to any one of claims 1 to 7.
CN202211381742.4A 2022-11-04 2022-11-04 Frequency converter soft start method and device, electronic equipment and readable storage medium Pending CN115632576A (en)

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