Variable frequency drive soft start method and device, electronic equipment and readable storage medium

Abstract

The application relates to a variable frequency converter soft starting method and device, electronic equipment and a readable storage medium. The method comprises the following steps: sampling a 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 according to the sampling voltage; and sending a conduction signal to a soft starting module if the power supply voltage is in the positive half cycle descending stage. The power supply voltage is sampled and positioned in the positive half cycle descending stage, and the thyristor is turned on when the power supply voltage is in the positive half cycle descending stage, so that the thyristor can be prevented from being broken down by power grid fluctuation, and the reliability of the variable frequency converter soft starting is improved.

Description

Technical Field

[0001] This application relates to the field of compressor control, and more particularly to a method, apparatus, electronic device, and readable storage medium for soft starting a frequency converter. Background Technology

[0002] Nowadays, users have increasingly higher requirements for the integration of compressors, especially magnetic levitation compressors, which often require the integration of three important components: magnetic levitation bearing controller, frequency converter, and compressor controller. The internal integration of compressors is high and the space is small. Existing frequency converters often use a circuit breaker combined with a charging resistor to achieve pure hardware soft start. However, the circuit breaker is too large to meet the space requirements of the compressor. Thyristor-controlled soft start schemes are usually used to replace circuit breakers. However, thyristors are easily damaged by power grid fluctuations when conducting, making the soft start scheme unreliable. Summary of the Invention

[0003] This application provides a method, apparatus, electronic device, and readable storage medium for soft starting a frequency converter, aiming to solve the technical problem in the prior art where the thyristor is broken down by power grid fluctuations during soft starting of a frequency converter.

[0004] To solve the above-mentioned technical problems, or at least partially solve them, this application provides a soft-start method for a frequency converter, the method comprising the following steps:

[0005] The sampled voltage is obtained by sampling the supply voltage in real time;

[0006] Based on the sampled voltage, determine whether the supply voltage is in the positive half-cycle decreasing phase;

[0007] If the power supply voltage is in the positive half-cycle decreasing phase, a conduction signal is sent to the soft-start module.

[0008] Optionally, the sampling voltage includes sampling sub-voltages corresponding to multiple consecutive sampling periods; determining whether the supply voltage is in the positive half-cycle decreasing phase based on the sampling voltage includes:

[0009] The stage characteristics of the power supply voltage are continuously determined based on each of the sampled sub-voltages;

[0010] If the phase characteristics of the supply voltage are sequentially determined as rising zero-crossing characteristic, rising characteristic, peak characteristic, and falling characteristic, then the supply voltage is determined to be in the falling phase of the positive half-cycle.

[0011] Optionally, the stage feature of determining the supply voltage based on each of the sampled sub-voltages includes:

[0012] Determine 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 spaced apart from the current sampling period by a first preset number of sampling periods;

[0013] If the first sample sub-voltage is greater than 0 and the second sample sub-voltage is less than 0, then the stage feature is determined to be a rising zero-crossing feature.

[0014] Optionally, the stage feature of determining the supply voltage based on each of the sampled sub-voltages includes:

[0015] Determine whether the voltage of the first sample sub-sampling is greater than the voltage of the second sample sub-sampling;

[0016] If the first sampling sub-voltage is greater than the second sampling sub-voltage, then the stage feature corresponding to the current sampling period is determined to be an ascending feature.

[0017] Optionally, the stage feature of determining the supply voltage based on each of the sampled sub-voltages includes:

[0018] Determine whether the third sampling sub-voltage is greater than the fourth sampling sub-voltage and the first sampling sub-voltage, and whether the third sampling sub-voltage is greater than a preset peak voltage, wherein the sampling period corresponding to the third sampling sub-voltage is spaced apart from the current sampling period by a second preset number of sampling periods, the sampling period corresponding to the fourth sampling sub-voltage is spaced apart from the sampling period corresponding to the third sampling sub-voltage by a second preset number of sampling periods, and the sampling period corresponding to the third sampling sub-voltage is later than the sampling period corresponding to the fourth sampling sub-voltage;

[0019] If the third sample sub-voltage is greater than the fourth sample sub-voltage and the first sample sub-voltage, and the third sample sub-voltage is greater than the preset vertex voltage, then the stage feature is determined to be a vertex feature.

[0020] Optionally, the stage feature of determining the supply voltage based on each of the sampled sub-voltages includes:

[0021] Determine whether the first sampling sub-voltage is less than the second sampling sub-voltage, whether the fifth sampling sub-voltage is less than the third sampling sub-voltage, and whether the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is less than a preset slope threshold. The sampling period corresponding to the fifth sampling sub-voltage is spaced apart from the current sampling period by a third preset number of sampling periods, and the sampling period corresponding to the sixth sampling sub-voltage is spaced apart from the current sampling period by a fourth preset number of sampling periods.

[0022] 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 the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is less than a preset slope threshold, then the stage feature is determined to be a decreasing feature.

[0023] Optionally, sending the control signal to the thyristor corresponding to the supply voltage includes:

[0024] Obtain the bus voltage and calculate the voltage difference between the first sampled sub-voltage and the bus voltage;

[0025] Determine whether the cumulative value of the rising zero-crossing feature is greater than a preset rising zero-crossing threshold, whether the voltage difference is greater than 0, and whether the voltage difference is less than a preset difference, wherein the cumulative value of the rising zero-crossing feature is the number of sampling periods for maintaining the stage feature as the rising zero-crossing feature;

[0026] If the cumulative value of the rising zero-crossing feature is greater than the preset rising zero-crossing threshold, and the voltage difference is greater than 0 and the voltage difference is less than the preset difference, then the conduction signal is sent to the soft-start module as the control signal.

[0027] To achieve the above objectives, the present invention also provides a frequency converter soft start device, the frequency converter soft start device comprising:

[0028] The first sampling module is used to sample the power supply voltage in real time to obtain the sampled voltage;

[0029] The first judgment module is used to determine whether the power supply voltage is in the positive half-cycle decreasing phase based on the sampled voltage.

[0030] The first transmitting module is used to send a conduction signal to the soft-start module if the power supply voltage is in the positive half-cycle decreasing phase.

[0031] To achieve the above objectives, the present invention also provides an electronic device, the electronic device including a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the inverter soft-start method as described above.

[0032] To achieve the above objectives, the present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the inverter soft-start method as described above.

[0033] This invention proposes a method, apparatus, electronic device, and readable storage medium for soft starting a frequency converter. The method involves sampling the supply voltage in real time to obtain a sampled voltage; determining whether the supply voltage is in the positive half-cycle decreasing phase based on the sampled voltage; and if the supply voltage is in the positive half-cycle decreasing phase, sending a conduction signal to the soft-start module. By sampling the supply voltage and locating it in the positive half-cycle decreasing phase, and by turning on the thyristor when the supply voltage is in the positive half-cycle decreasing phase, the method avoids grid fluctuations damaging the thyristor, thereby improving the reliability of the frequency converter's soft starting. Attached Figure Description

[0034] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a flowchart illustrating the first embodiment of the inverter soft-start method of the present invention;

[0037] Figure 2 This is a schematic diagram of the compressor control circuit used in the inverter soft-start method of the present invention;

[0038] Figure 3 This is a schematic diagram of the overall process of the inverter soft-start method of the present invention;

[0039] Figure 4 This is a schematic diagram of the module structure of the electronic device of the present invention. Detailed Implementation

[0040] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.

[0041] This invention provides a soft-start method for a frequency converter, referring to... Figure 1 , Figure 1This is a flowchart illustrating the first embodiment of the inverter soft-start method of the present invention, the method comprising the following steps:

[0042] Step S10: Sample the power supply voltage in real time to obtain the sampled voltage;

[0043] The inverter soft-start method in this embodiment is applied to the compressor control circuit. See [link / reference]. Figure 2 , Figure 2 This is a schematic diagram of the compressor control circuit. It should be noted that... Figure 2 The structure of the compressor control circuit is shown for only one application scenario. In practical applications, the structure of the compressor control circuit can be adjusted according to actual needs.

[0044] The compressor control circuit includes a controller, a soft-start module, and an IGBT inverter bridge. The soft-start module is a thyristor semi-controlled rectifier bridge. Its three input terminals are connected to the three-phase power supply, and its output terminal serves as the DC bus voltage terminal, connected to the input terminal of the inverter bridge. The three-phase output terminals of the IGBT inverter bridge are connected to the three-phase power supply terminals of the compressor. The controller includes a sampling circuit, a DSP (Digital Signal Processing), a thyristor drive circuit, and an IGBT drive circuit. The sampling terminals of the sampling circuit are connected to the three-phase power supply and the DC bus voltage terminal, respectively. The output terminal of the sampling circuit is connected to the DSP. The output terminals of the DSP are connected to the control terminals of both the thyristor drive circuit and the IGBT drive circuit. The output terminals of the thyristor drive circuit are connected to the control terminals of each thyristor in the thyristor semi-controlled rectifier bridge, respectively. The output terminals of the IGBT drive circuit are connected to the gates of each IGBT in the IGBT inverter bridge, respectively.

[0045] The DSP controls the compressor by sampling the three-phase power supply and DC bus voltage through a sampling circuit to control the conduction of the thyristor semi-controlled rectifier bridge and the IGBT inverter bridge. It is understood that the specific control method for the IGBT inverter bridge can be set based on actual needs. In this embodiment, the DSP simultaneously controls both the thyristor semi-controlled rectifier bridge and the IGBT inverter bridge, reducing the number of soft-start controllers, the number of chips, and the space occupied, while improving the coordination between soft-start control and compressor control.

[0046] It should be noted that the soft start of the inverter in this embodiment uses a thyristor semi-controlled rectifier bridge. In practical applications, it can also be set to other rectifier devices, such as a diode rectifier bridge. The inverter circuit in this embodiment uses an IGBT inverter bridge. In practical applications, it can also be set to other inverter devices, such as a MOS inverter bridge.

[0047] In this embodiment, the sampling voltage is the line voltage, including the three-phase power supply voltage, i.e., the U-phase voltage V. U Phase V voltage V V and W-phase voltage V W In addition, the DC bus voltage u can also be adjusted. dc The sampling method for three-phase power supply voltage and DC bus voltage can be set based on the actual application scenario, such as current transformers, voltage sensors, etc.

[0048] It should be noted that the voltage sampling frequency can be set according to actual needs. This embodiment and subsequent embodiments use a sampling frequency of 10kHz for illustration. Other frequencies can be implemented by analogy and will not be described in detail.

[0049] Step S20: Determine whether the power supply voltage is in the positive half-cycle decreasing phase based on the sampled voltage;

[0050] It is understandable that the supply voltage is alternating current, which means that the supply voltage exhibits a sine wave over time. Therefore, the supply voltage includes 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. Therefore, the current sine wave phase of the supply voltage can be determined by sampling the voltage.

[0051] Step S30: If the power supply voltage is in the positive half-cycle decreasing phase, a conduction signal is sent to the soft-start module.

[0052] It is understandable that when the supply voltage is in the rising phase, including both the positive and negative half-cycle rising phases, the thyristor is susceptible to breakdown due to power grid fluctuations. However, when the supply voltage is in the negative half-cycle, the thyristor is cut off. Therefore, the thyristor can be turned on during the positive half-cycle, and at the same time, it can avoid excessive impact from power grid fluctuations during the falling phase. Thus, controlling the thyristor during the falling phase of the positive half-cycle can ensure system stability while maintaining conduction.

[0053] This embodiment samples the power supply voltage and locates the power supply voltage in the positive half-cycle decreasing phase. By turning on the thyristor when the power supply voltage is in the positive half-cycle decreasing phase, it can avoid the power grid fluctuation from breaking down the thyristor and improve the reliability of the inverter's soft start.

[0054] Further details will follow. Figure 3 In the second embodiment of the inverter soft-start method of the present invention based on the first embodiment, the sampling voltage includes sampling sub-voltages corresponding to multiple consecutive sampling periods; step S20 includes the following steps:

[0055] Step S21: Continuously determine the stage characteristics of the power supply voltage based on each of the sampled sub-voltages;

[0056] The phase characteristics are used to reflect the sinusoidal phase of the current supply voltage. It should be noted that the voltages of the three-phase power supply are in different phases. Therefore, the sinusoidal phase of the supply voltage corresponding to the three-phase power supply is not necessarily the same. Therefore, in this embodiment, the thyristors in the thyristor semi-controlled rectifier bridge corresponding to the three-phase power supply are controlled independently. That is, the thyristor connected to the U-phase power supply is controlled by the U-phase supply voltage, the thyristor connected to the V-phase power supply is controlled by the V-phase supply voltage, and the thyristor connected to the W-phase power supply is controlled by the W-phase supply voltage. In this embodiment, the U-phase supply voltage is used for explanation. The other phase supply voltages can be implemented by analogy and will not be described in detail.

[0057] It is understandable that the length of the sampling period varies depending on the sampling frequency, and can be determined according to the actual sampling frequency set. In this embodiment, continuous sampling is performed based on the sampling period, and the obtained sampled voltage includes sampled sub-voltages obtained from multiple consecutive sampling periods. It should be noted that the number of sampled sub-voltages can be set based on the actual accuracy requirements. In this embodiment, the number of sampled sub-voltages is 7, and other scenarios can be implemented by analogy. It should be noted that this embodiment is implemented by continuously looping interrupts; in practical applications, other implementation methods can be used.

[0058] The sampling voltage includes seven sampling sub-voltages: u0, u1, u2, u3, u4, u5, and u6. Among them, u6 is the sampling sub-voltage obtained in the latest sampling period, u5 is the sampling sub-voltage obtained in the previous sampling period, and so on. u0 is the sampling sub-voltage obtained 6 sampling periods away from the latest sampling period.

[0059] Based on this, if a new sampled sub-voltage un is sampled in a new sampling period, each sampled sub-voltage is updated. Specifically, the sampled sub-voltages of the previous sampling period are updated to the sampled sub-voltages of the next sampling period, while the earliest sampled sub-voltage is removed, maintaining the number of sampled sub-voltages at 7.

[0060] u0=u1; u1=u2; u2=u3; u3=u4; u4=u5; u5=u6; u6=un;

[0061] For ease of explanation later, 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.

[0062] The characteristics or trends of the supply voltage differ in different stages of a sine wave. Based on these characteristics and trends, the stage of the sine wave in which the supply voltage is located can be determined. Specifically:

[0063] Step S211: Determine 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 spaced apart from the current sampling period by a first preset number of sampling periods;

[0064] Step S212: If the first sample sub-voltage is greater than 0 and the second sample sub-voltage is less than 0, then the stage feature is determined to be a rising zero-crossing feature.

[0065] If the first sample sub-voltage is less than or equal to 0, or the second sample sub-voltage is greater than or equal to 0, then the stage feature is not a rising zero-crossing feature.

[0066] Since the sampling period of the first sampling sub-voltage is after that of 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, it indicates that the supply voltage has crossed zero. Simultaneously, the first sampling sub-voltage is greater than the second sampling sub-voltage, therefore, the supply voltage shows an upward trend. Thus, the phase characteristic of the supply voltage can be determined as a rising zero-crossing characteristic. It should be noted that, theoretically, when the first sampling sub-voltage is greater than 0 and the fifth sampling sub-voltage, u5, is less than 0, the phase characteristic of the supply voltage can be considered a rising zero-crossing characteristic. However, in practical applications, there are grid fluctuations or other factors that cause small fluctuations. In such cases, directly judging based on the sampling sub-voltages of two adjacent sampling periods can easily lead to misjudgment. In this embodiment, the sampling period corresponding to the second sampling sub-voltage is spaced apart from the current sampling period by a first preset number of sampling periods. Taking u6 and u2 as an example, the first preset number is 3, resulting in a relatively long interval between the two sampling periods, thereby avoiding misjudgment caused by grid fluctuations or other factors. The reasons for setting the subsequent preset numbers are the same and will not be repeated. It should be noted that the specific values ​​of each preset number can be set based on actual needs.

[0067] Step S213: Determine whether the first sampling sub-voltage is greater than the second sampling sub-voltage;

[0068] Step S214: If the first sampling sub-voltage is greater than the second sampling sub-voltage, then the stage feature corresponding to the current sampling period is determined to be an ascending feature;

[0069] If the first sample sub-voltage is less than or equal to the second sample sub-voltage, then the stage feature is not an ascending feature.

[0070] Since the sampling period of the first sampling sub-voltage is after that of the second sampling sub-voltage, and the first sampling sub-voltage is greater than the second sampling sub-voltage, it indicates that the power supply voltage is on an upward trend. Therefore, it can be determined that the phase characteristic of the power supply voltage is an upward characteristic.

[0071] Step S215: Determine whether the third sampling sub-voltage is greater than the fourth sampling sub-voltage and the first sampling sub-voltage, and whether the third sampling sub-voltage is greater than a preset peak voltage. The sampling period corresponding to the third sampling sub-voltage is spaced apart from the current sampling period by a second preset number of sampling periods. The sampling period corresponding to the fourth sampling sub-voltage is spaced apart from the sampling period corresponding to the third sampling sub-voltage by a second preset number of sampling periods. The sampling period corresponding to the third sampling sub-voltage is later than the sampling period corresponding to the fourth sampling sub-voltage.

[0072] Step S216: If the third sample sub-voltage is greater than the fourth sample sub-voltage and the first sample sub-voltage, and the third sample sub-voltage is greater than the preset vertex voltage, then the stage feature is determined to be a vertex feature.

[0073] If the third sample sub-voltage is less than or equal to the fourth sample sub-voltage or the first sample sub-voltage, or if the third sample sub-voltage is less than or equal to a preset vertex voltage, then the stage feature is determined to be a vertex feature.

[0074] Since the sampling period of the third sampling sub-voltage is after the fourth sampling sub-voltage and before the first sampling sub-voltage, the supply voltage shows an upward trend when the third sampling sub-voltage is greater than the fourth sampling sub-voltage, and a downward trend when the third sampling sub-voltage is greater than the first sampling sub-voltage. When an upward trend is detected first, followed by a downward trend, the supply voltage is considered to have passed its peak. Furthermore, to avoid interference from grid fluctuations or other factors, a preset peak voltage is set. Only when the third sampling sub-voltage is greater than the preset peak voltage is the supply voltage considered to have passed its peak, thus defining the phase characteristic of the supply voltage as a peak characteristic. It should be noted that the preset peak voltage can be set based on actual needs. For example, with a line voltage of 380V, the preset peak voltage can be set to 430V.

[0075] Step S217: Determine whether the first sampling sub-voltage is less than the second sampling sub-voltage, whether the fifth sampling sub-voltage is less than the third sampling sub-voltage, and whether the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is less than a preset slope threshold. The sampling period corresponding to the fifth sampling sub-voltage is spaced three preset number of sampling periods apart from the current sampling period, and the sampling period corresponding to the sixth sampling sub-voltage is spaced four preset number of sampling periods apart from the current sampling period.

[0076] 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 the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is less than a preset slope threshold, then the stage feature is determined to be a decreasing feature.

[0077] If the first sample sub-voltage is greater than or equal to the second sample sub-voltage, or the fifth sample sub-voltage is greater than or equal to the third sample sub-voltage, or the difference between the sixth sample sub-voltage and the first sample sub-voltage is greater than or equal to a preset slope threshold, then the stage feature is determined to be a decreasing feature.

[0078] Since the sampling period of the first sampling sub-voltage is after that of the second sampling sub-voltage, when the first sampling sub-voltage is less than the second sampling sub-voltage, the supply voltage shows a downward trend. Similarly, when the fifth sampling sub-voltage is less than the third sampling sub-voltage, it is determined that the supply voltage shows a downward trend. To avoid the rapid voltage drop caused by power grid fluctuations or other factors affecting the judgment of the sine wave phase, a preset slope threshold is set. If the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is less than the preset slope threshold, it is considered that the supply voltage drops too quickly, possibly due to power grid fluctuations or other factors. In this case, the phase characteristic of the supply voltage is not considered to be a downward characteristic. If the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is less than the preset slope threshold, it is considered that the supply voltage conforms to the normal downward characteristic of a sine wave. In this case, the phase characteristic of the supply voltage is determined to be a downward characteristic.

[0079] Step S22: If the phase characteristics of the power supply voltage are sequentially determined as rising zero-crossing characteristic, rising characteristic, peak characteristic and falling characteristic, then the power supply voltage is determined to be in the falling phase of the positive half-cycle.

[0080] It should be noted that, because the different stages of a sine wave have a sequential relationship—starting with the rising zero-crossing feature, the stages appearing in sequence as rising feature, peak feature, falling feature, falling zero-crossing feature, falling feature, negative peak feature, rising feature, and rising zero-crossing feature—only by sequentially and continuously detecting the rising zero-crossing feature, rising feature, peak feature, and falling feature can it be accurately determined that the supply voltage is in the falling phase of the positive half-cycle. Specifically, flag bits are set for different stage features. Initially, all flag bits are reset to 0. Detection of the rising zero-crossing feature begins. After detecting the rising zero-crossing feature, the rising zero-crossing flag bit is set to 1. After the rising zero-crossing flag bit is set to 1, detection of the rising feature begins. After detecting the rising feature, the rising flag bit is set to 1. After the rising flag bit is set to 1, detection of the peak feature begins. After detecting the peak feature, the peak flag bit is set to 1. After the peak flag bit is set to 1, detection of the falling feature begins. After detecting the falling feature, the falling flag bit is set to 1. After the falling flag bit is set to 1, it is determined that the supply voltage is in the falling phase of the positive half-cycle.

[0081] It should be noted that when detecting a certain stage feature, only the detected stage feature is reacted to. For example, when detecting a rising feature, if other stage features besides the rising feature are detected, no reaction is made. Only after the rising feature is detected is the rising flag bit set to 1, and the detection of subsequent stage features is performed simultaneously. It should also be noted that in this embodiment, it is necessary to determine that the supply voltage is in the falling phase of the positive half-cycle. Once the supply voltage is detected to be in the lower half-cycle, that is, when the 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 the detection of the rising zero-crossing feature is re-executed.

[0082] It should be noted that since the changes in characteristics at different stages are continuous, in some embodiments, the stage characteristics to be detected can be selected. For example, in this embodiment, the rising zero-crossing feature, rising feature, peak feature, and falling feature are detected sequentially. In other embodiments, the stage characteristics to be detected can be set to the rising feature, peak feature, and falling feature sequentially, or the peak feature and falling feature sequentially, or the rising feature and falling feature sequentially, or the rising zero-crossing feature, peak feature, and falling feature sequentially. That is, by combining different stage characteristics, it is possible to determine that the supply voltage is in the falling stage of the positive half-cycle when the falling feature is detected.

[0083] This embodiment can accurately determine the sinusoidal phase of the power supply voltage, and thus determine whether the power supply voltage is in the positive half-cycle decreasing phase.

[0084] Furthermore, in the third embodiment of the inverter soft-start method of the present invention based on the first embodiment, step S30 includes the following steps:

[0085] Step S31: Obtain the bus voltage and calculate the voltage difference between the first sampled sub-voltage and the bus voltage;

[0086] Step S32: Determine whether the cumulative value of the rising zero-crossing feature is greater than a preset rising zero-crossing threshold, whether the voltage difference is greater than 0, and whether the voltage difference is less than a preset difference, wherein the cumulative value of the rising zero-crossing feature is the number of sampling periods for maintaining the stage feature as the rising zero-crossing feature;

[0087] Step S33: If the cumulative value of the rising zero-crossing feature is greater than the preset rising zero-crossing threshold, and the voltage difference is greater than 0, and the voltage difference is less than the preset difference, then the conduction signal is sent to the soft-start module as the control signal.

[0088] If the cumulative value of the rising zero-crossing feature is less than or equal to the preset rising zero-crossing threshold, or the voltage difference is less than or equal to 0, or the voltage difference is greater than or equal to the preset difference, then the cutoff signal is sent to the soft-start module as the control signal.

[0089] When a rising zero-crossing feature is detected, the cumulative value of the rising zero-crossing feature is incremented by 1, and the cumulative value of the rising zero-crossing feature is incremented by 1 every subsequent sampling period; when the rising zero-crossing flag is reset to 0, the cumulative value of the rising zero-crossing feature is reset to 0.

[0090] To avoid interference from power grid fluctuations or other factors, a preset zero-crossing threshold is set. Only when a certain time has elapsed after detecting a zero-crossing characteristic is the supply voltage considered to be in the declining phase of the first half of the cycle. The specific preset zero-crossing threshold can be set based on actual needs, such as 45.

[0091] The voltage difference reflects the gap between the first sampling sub-voltage and the bus voltage. Understandably, when a decreasing characteristic is detected, the first sampling sub-voltage continuously decreases, while the bus voltage remains constant. Therefore, the voltage difference will continuously decrease. When the voltage difference is between 0 and a preset difference value, a turn-on signal is output to the thyristor. It is understood that the thyristor is only triggered to turn on by the turn-on signal; when a reverse voltage is applied to the thyristor, it will automatically turn off. Therefore, the turn-on time of the thyristor can be set by setting the specific value of the preset difference value; the specific preset difference value can be set based on actual needs.

[0092] This embodiment can accurately set the conduction time of the thyristor.

[0093] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to this application. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0094] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods according to the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0095] This application also provides a frequency converter soft starter for implementing the above-described frequency converter soft starter method, the frequency converter soft starter comprising:

[0096] The first sampling module is used to sample the power supply voltage in real time to obtain the sampled voltage;

[0097] The first judgment module is used to determine whether the power supply voltage is in the positive half-cycle decreasing phase based on the sampled voltage.

[0098] The first transmitting module is used to send a conduction signal to the soft-start module if the power supply voltage is in the positive half-cycle decreasing phase.

[0099] This inverter soft-start device samples the power supply voltage and locates the power supply voltage in the positive half-cycle decreasing phase. By turning on the thyristor when the power supply voltage is in the positive half-cycle decreasing phase, it can avoid the thyristor being damaged by power grid fluctuations, thereby improving the reliability of the inverter soft start.

[0100] It should be noted that the first sampling module in this embodiment can be used to execute step S10 in this application embodiment, the first judgment module in this embodiment can be used to execute step S20 in this application embodiment, and the first sending module in this embodiment can be used to execute step S30 in this application embodiment.

[0101] Furthermore, the sampling voltage includes sampling sub-voltages corresponding to multiple consecutive sampling periods; the first determination module includes:

[0102] The first determining unit is used to continuously determine the stage characteristics of the power supply voltage based on each of the sampled sub-voltages;

[0103] The second determining unit is used to determine that the power supply voltage is in the positive half-cycle decreasing phase if the phase characteristics of the power supply voltage are sequentially determined as rising zero-crossing characteristic, rising characteristic, peak characteristic and falling characteristic.

[0104] Further, the first determining unit includes:

[0105] The first judgment subunit is used to determine 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 spaced apart from the current sampling period by a first preset number of sampling periods.

[0106] The first determining subunit is used to determine the stage feature as a rising zero-crossing feature if the first sampling sub-voltage is greater than 0 and the second sampling sub-voltage is less than 0.

[0107] Further, the first determining unit includes:

[0108] The second judgment subunit is used to determine whether the first sampling sub-voltage is greater than the second sampling sub-voltage;

[0109] The second determining subunit is used to determine that the stage feature corresponding to the current sampling period is an rising feature if the first sampling sub-voltage is greater than the second sampling sub-voltage.

[0110] Further, the first determining unit includes:

[0111] The third judgment subunit is used to determine whether the third sampling sub-voltage is greater than the fourth sampling sub-voltage and the first sampling sub-voltage, and whether the third sampling sub-voltage is greater than a preset peak voltage. The sampling period corresponding to the third sampling sub-voltage is spaced apart from the current sampling period by a second preset number of sampling periods. The sampling period corresponding to the fourth sampling sub-voltage is spaced apart from the sampling period corresponding to the third sampling sub-voltage by a second preset number of sampling periods. The sampling period corresponding to the third sampling sub-voltage is later than the sampling period corresponding to the fourth sampling sub-voltage.

[0112] The third determining subunit is used to determine the stage feature as a vertex feature 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 vertex voltage.

[0113] Further, the first determining unit includes:

[0114] The fourth judgment subunit is used to determine whether the first sampling sub-voltage is less than the second sampling sub-voltage, whether the fifth sampling sub-voltage is less than the third sampling sub-voltage, and whether the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is less than a preset slope threshold. The sampling period corresponding to the fifth sampling sub-voltage is spaced apart from the current sampling period by a third preset number of sampling periods, and the sampling period corresponding to the sixth sampling sub-voltage is spaced apart from the current sampling period by a fourth preset number of sampling periods.

[0115] The fourth determining subunit is used to determine the stage feature as a decreasing feature 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 the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is less than a preset slope threshold.

[0116] Furthermore, the first sending module includes:

[0117] The first acquisition unit is used to acquire the bus voltage and calculate the voltage difference between the first sampled sub-voltage and the bus voltage.

[0118] The first judgment unit is used to judge whether the cumulative value of the rising zero-crossing feature is greater than the preset rising zero-crossing threshold, whether the voltage difference is greater than 0, and whether the voltage difference is less than the preset difference, wherein the cumulative value of the rising zero-crossing feature is the number of sampling periods for maintaining the stage feature as the rising zero-crossing feature;

[0119] The first transmitting unit is configured to transmit the turn-on signal as the control signal to the soft-start module if the cumulative value of the rising zero-crossing feature is greater than a preset rising zero-crossing threshold, the voltage difference is greater than 0, and the voltage difference is less than a preset difference.

[0120] It should be noted that the examples and application scenarios implemented by the above modules and corresponding steps are the same, but are not limited to the content disclosed in the above embodiments. It should also be noted that the above modules, as part of the device, can be implemented in software or hardware, wherein the hardware environment includes a network environment.

[0121] Reference Figure 4 In terms of hardware structure, the electronic device may include components such as a communication module 10, a memory 20, and a processor 30. In the electronic device, the processor 30 is connected to both the memory 20 and the communication module 10. The memory 20 stores a computer program, which is executed by the processor 30. When the computer program is executed, it implements the steps of the above-described method embodiments.

[0122] The communication module 10 can connect to external communication devices via a network. The communication module 10 can receive requests from the external communication devices and can also send requests, instructions, and information to the external communication devices. The external communication devices can be other electronic devices, servers, or IoT devices, such as televisions, etc.

[0123] The memory 20 can be used to store software programs and various data. The memory 20 may primarily include a program storage area and a data storage area. The program storage area may store the operating system, at least one application program required for a function (such as sampling the supply voltage in real time to obtain a sampled voltage), etc.; the data storage area may include a database, and may store data or information created based on system usage. Furthermore, the memory 20 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0124] The processor 30 is the control center of the electronic device. It connects various parts of the electronic device via various interfaces and lines. By running or executing software programs and / or modules stored in the memory 20, and by calling data stored in the memory 20, it performs various functions and processes data, thereby providing overall monitoring of the electronic device. The processor 30 may include one or more processing units; optionally, the processor 30 may integrate an application processor and a modem processor. The application processor mainly handles the operating system, user interface, and applications, while the modem processor mainly handles wireless communication. It is understood that the modem processor may not be integrated into the processor 30.

[0125] although Figure 4 Not shown, but the above-described electronic device may further include a circuit control module for connecting to a power supply to ensure the normal operation of other components. Those skilled in the art will understand that... Figure 4 The electronic device structure shown does not constitute a limitation on the electronic device and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0126] The present invention also proposes a computer-readable storage medium having a computer program stored thereon. The computer-readable storage medium may be... Figure 4The memory 20 in the electronic device may also be at least one of ROM (Read-Only Memory) / RAM (Random Access Memory), magnetic disk, optical disk, etc. The computer-readable storage medium includes a number of instructions to cause a terminal device with a processor (which may be a television, automobile, mobile phone, computer, server, terminal, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0127] In this invention, the terms "first," "second," "third," "fourth," and "fifth" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0128] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0129] Although embodiments of the present invention have been shown and described above, the scope of protection of the present invention is not limited thereto. It is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, and substitutions to the above embodiments within the scope of the present invention, and such changes, modifications, and substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for soft starting a frequency converter, characterized by The method includes: The sampled voltage is obtained by sampling the supply voltage in real time; Based on the sampled voltage, determine whether the supply voltage is in the positive half-cycle decreasing phase; If the power supply voltage is in the positive half-cycle decreasing phase, a conduction signal is sent to the soft-start module; The sampling voltage includes sampling sub-voltages corresponding to multiple consecutive sampling periods. If a new sampling sub-voltage is sampled in a new sampling period, each sampling sub-voltage is updated, with the sampling sub-voltage of the previous sampling period being updated to the sampling sub-voltage of the next sampling period. Simultaneously, the earliest sampled sampling sub-voltage is removed. Determining whether the supply voltage is in the positive half-cycle decreasing phase based on the sampling voltage includes: The stage characteristics of the power supply voltage are continuously determined based on each of the sampled sub-voltages; If the phase characteristics of the supply voltage are sequentially determined as rising zero-crossing characteristic, rising characteristic, peak characteristic, and falling characteristic, then the supply voltage is determined to be in the falling phase of the positive half-cycle. The stage characteristics of determining the supply voltage based on each of the sampled sub-voltages include: Determine whether the first sampling sub-voltage is less than the second sampling sub-voltage, whether the fifth sampling sub-voltage is less than the third sampling sub-voltage, and whether the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is less than a preset slope threshold. Here, the first sampling sub-voltage is the sampling sub-voltage corresponding to the current sampling period; the sampling period corresponding to the second sampling sub-voltage is spaced apart from the current sampling period by a first preset number of sampling periods; the sampling period corresponding to the third sampling sub-voltage is spaced apart from the current sampling period by a second preset number of sampling periods; the sampling period corresponding to the fifth sampling sub-voltage is spaced apart from the current sampling period by a third preset number of sampling periods; and the sampling period corresponding to the sixth sampling sub-voltage is spaced apart from the current sampling period by a fourth preset number of sampling periods. The sampling order of the sampling sub-voltages is: fourth sampling sub-voltage, second sampling sub-voltage, third sampling sub-voltage, sixth sampling sub-voltage, fifth sampling sub-voltage, and first sampling sub-voltage. 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 the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is less than a preset slope threshold, then the stage feature is determined to be a decreasing feature.

2. The inverter soft-start method as described in claim 1, characterized in that, The stage characteristics of determining the supply voltage based on each of the sampled sub-voltages include: Determine whether the first sample sub-voltage is greater than 0 and whether the second sample sub-voltage is less than 0; If the first sample sub-voltage is greater than 0 and the second sample sub-voltage is less than 0, then the stage feature is determined to be a rising zero-crossing feature.

3. The inverter soft-start method as described in claim 1, characterized in that, The stage characteristics of determining the supply voltage based on each of the sampled sub-voltages include: Determine whether the voltage of the first sample sub-sampling is greater than the voltage of the second sample sub-sampling; If the first sampling sub-voltage is greater than the second sampling sub-voltage, then the stage feature corresponding to the current sampling period is determined to be an ascending feature.

4. The inverter soft-start method as described in claim 1, characterized in that, The stage characteristics of determining the supply voltage based on each of the sampled sub-voltages include: Determine whether the third sampling sub-voltage is greater than the fourth sampling sub-voltage and the first sampling sub-voltage, and whether the third sampling sub-voltage is greater than a preset peak voltage, wherein the sampling period corresponding to the fourth sampling sub-voltage and the third sampling sub-voltage is spaced apart by a second preset number of sampling periods, and the sampling period corresponding to the third sampling sub-voltage is later than the sampling period corresponding to the fourth sampling voltage; If the third sample sub-voltage is greater than the fourth sample sub-voltage and the first sample sub-voltage, and the third sample sub-voltage is greater than the preset vertex voltage, then the stage feature is determined to be a vertex feature.

5. The inverter soft-start method as described in claim 1, characterized in that, The step of sending the activation signal to the soft-start module includes: Obtain the bus voltage and calculate the voltage difference between the first sampled sub-voltage and the bus voltage; Determine whether the cumulative value of the rising zero-crossing feature is greater than a preset rising zero-crossing threshold, whether the voltage difference is greater than 0, and whether the voltage difference is less than a preset difference, wherein the cumulative value of the rising zero-crossing feature is the number of sampling periods for maintaining the stage feature as the rising zero-crossing feature; If the cumulative value of the rising zero-crossing feature is greater than the preset rising zero-crossing threshold, and the voltage difference is greater than 0 and the voltage difference is less than the preset difference, then the conduction signal is sent to the soft-start module as a control signal.

6. A soft-start device for a frequency converter, characterized in that, The inverter soft start device includes: The first sampling module is used to sample the power supply voltage in real time to obtain the sampled voltage; The first judgment module is used to determine whether the power supply voltage is in the positive half-cycle decreasing phase based on the sampled voltage. The first transmitting module is used to send a turn-on signal to the soft-start module if the power supply voltage is in the positive half-cycle decreasing phase. The sampling voltage includes sampling sub-voltages corresponding to multiple consecutive sampling periods. If a new sampling sub-voltage is sampled in a new sampling period, each sampling sub-voltage is updated, with the sampling sub-voltage of the previous sampling period updated to the sampling sub-voltage of the next sampling period. Simultaneously, the earliest sampled sampling sub-voltage is removed. The first judgment module includes: The first determining unit is used to continuously determine the stage characteristics of the power supply voltage based on each of the sampled sub-voltages; The second determining unit is used to determine that the power supply voltage is in the positive half-cycle decreasing phase if the phase characteristics of the power supply voltage are sequentially determined to be rising zero-crossing characteristic, rising characteristic, peak characteristic and falling characteristic. The first determining unit includes: The fourth judgment subunit is used to determine whether the first sampling sub-voltage is less than the second sampling sub-voltage, whether the fifth sampling sub-voltage is less than the third sampling sub-voltage, and whether the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is less than a preset slope threshold. Here, the first sampling sub-voltage is the sampling sub-voltage corresponding to the current sampling period, the sampling period corresponding to the second sampling sub-voltage is spaced apart from the current sampling period by a first preset number of sampling periods, the sampling period corresponding to the third sampling sub-voltage is spaced apart from the current sampling period by a second preset number of sampling periods, the sampling period corresponding to the fifth sampling sub-voltage is spaced apart from the current sampling period by a third preset number of sampling periods, and the sampling period corresponding to the sixth sampling sub-voltage is spaced apart from the current sampling period by a fourth preset number of sampling periods. The sampling order of the sampling sub-voltages is the fourth sampling sub-voltage, the second sampling sub-voltage, the third sampling sub-voltage, the sixth sampling sub-voltage, the fifth sampling sub-voltage, and the first sampling sub-voltage. The fourth determining subunit is used to determine the stage feature as a decreasing feature 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 the difference between the sixth sampling sub-voltage and the first sampling sub-voltage is less than a preset slope threshold.

7. An electronic device, characterized in that, The electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the steps of the inverter soft-start method as described in any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the inverter soft-start method as described in any one of claims 1 to 5.

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