Power frequency and variable frequency switching control method and device, frequency converter, power equipment and medium

Abstract

According to the power frequency and variable frequency switching control method, in the phase synchronization control process, the power frequency power grid phase is used as the frequency converter voltage vector wave sending angle of first phase synchronization, and compared with conventional PID loop control, the problem that the power grid phase cannot be rapidly synchronized under the condition of power grid distortion or power grid frequency fluctuation is solved; and the response speed and the synchronization accuracy of phase synchronization are improved. Besides, after the first phase synchronization, a phase synchronization control strategy based on current oscillation suppression is also added, so that current impact caused by phase synchronization errors can be suppressed, the phase adjustment response speed is high, final phase synchronization is realized, and the adaptability of power frequency and variable frequency switching to the working condition of a weak power grid is effectively improved.

Description

Technical Field

[0001] The present application belongs to the field of power electronics technology, and in particular relates to an industrial frequency conversion switching control method, an industrial frequency conversion switching control device, a frequency converter, a power device, and a computer-readable storage medium. Background Art

[0002] When using a frequency converter to drive a motor, in order to achieve smooth switching between industrial (i.e., industrial frequency grid) and variable frequency (i.e., variable frequency grid), it is necessary to control the amplitude, phase, and frequency of the frequency converter output voltage to be consistent with the industrial frequency grid until the switching is completed; among them, phase synchronization is the most important issue to consider in achieving smooth switching. Traditional phase synchronization technology uses the PID (Proportion Integral Differential) algorithm to adjust the phase deviation in real time. This method can achieve better control effects when the grid is good or the motor power is small.

[0003] However, in actual application conditions, the on-site power grid conditions are relatively complex. For example, the grid waveform is distorted and the power grid is weak, which will cause large fluctuations in the grid frequency. During the industrial frequency conversion switching process, the inverter power supply and the grid power supply will be supplied simultaneously during the disturbance-free switching. The parallel operation process is prone to current shocks, which can easily affect the grid frequency, especially when large-power motors are switched from industrial frequency to industrial frequency. There are also factors such as the motor's own operating oscillations that affect the output frequency of the variable frequency power supply. These factors will cause the phase synchronization time of the variable frequency power supply and the grid power supply to be extended, and the phase synchronization effect will be poor. Summary of the invention

[0004] The purpose of the present application is to provide an industrial frequency conversion switching control method, an industrial frequency conversion switching control device, a frequency converter, an electric power equipment and a computer-readable storage medium, aiming to solve the problems of long phase synchronization time and poor phase synchronization effect existing in the traditional industrial frequency conversion switching phase synchronization method.

[0005] A first aspect of an embodiment of the present application provides an industrial frequency conversion switching control method, wherein the frequency converter is connected to a variable frequency power grid and a motor; the motor is connected to an industrial frequency power grid; and the control method comprises:

[0006] Obtaining the grid phase and grid frequency of the industrial frequency grid;

[0007] Driving the motor to operate at the grid frequency;

[0008] Controlling the phase of the output voltage to track the grid phase until the phase difference between the two is less than or equal to a preset synchronous phase difference;

[0009] Calculate and output SVPWM waveform using the grid phase as the voltage vector wave angle;

[0010] Obtaining a phase synchronization adjustment angle according to the three-phase current output to the motor;

[0011] The voltage vector wave generation angle is adjusted according to the phase synchronization adjustment angle to update the SVPWM waveform, so that the phase of the output voltage is synchronized with the phase of the power grid.

[0012] In some embodiments, obtaining the phase synchronization adjustment angle according to the three-phase current output to the motor includes:

[0013] Acquiring three-phase current output to the motor;

[0014] The three-phase current is transformed by Park to obtain a d-axis current and a q-axis current;

[0015] Performing high-pass filtering on the d-axis current and the q-axis current to extract a d-axis oscillation component and a q-axis oscillation component respectively;

[0016] A phase synchronization adjustment angle is obtained according to the d-axis oscillation component and the q-axis oscillation component.

[0017] In some embodiments, obtaining the phase synchronization adjustment angle according to the d-axis oscillation component and the q-axis oscillation component includes:

[0018] Summing the d-axis oscillation component and the q-axis oscillation component to obtain a total oscillation component;

[0019] The product of the total oscillation component and the oscillation suppression factor is used as the fine-tuning angular frequency;

[0020] The fine-tuning angular frequency is integrated to obtain the phase synchronization adjustment angle.

[0021] In some embodiments, adjusting the voltage vector wave angle according to the phase synchronization adjustment angle to update the SVPWM waveform includes:

[0022] The voltage vector wave generating angle is adjusted by superimposing the phase synchronization adjustment angle on the basis of the grid phase;

[0023] The SVPWM waveform is calculated and outputted according to the adjusted voltage vector wave angle.

[0024] In some embodiments, the step of calculating and outputting a SVPWM waveform using the grid phase as a voltage vector wave angle includes:

[0025] Assigning the wave angle of the output voltage to the grid phase;

[0026] The assigned wave generation angle is used as the voltage vector wave generation angle to calculate and output the SVPWM waveform.

[0027] In some embodiments, controlling the phase of the output voltage to track the grid phase until the phase difference between the two is less than or equal to a preset synchronous phase difference includes:

[0028] Obtaining a wave angle of the output voltage;

[0029] Calculating the phase difference between the wave transmission angle and the grid phase;

[0030] In the case where the phase difference between the two is greater than the preset synchronization phase difference, the transmission angle is updated with a fixed fine-tuning angle until the phase difference between the two is less than or equal to the preset synchronization phase difference.

[0031] A second aspect of the embodiment of the present application provides an industrial frequency conversion switching control device, the device is arranged in a frequency converter, the frequency converter is connected to a variable frequency grid and a motor respectively; the motor is connected to an industrial frequency grid; the device comprises:

[0032] An acquisition module, used for acquiring a grid phase and a grid frequency of an industrial frequency grid;

[0033] A driving module, used for driving the motor to operate at the grid frequency;

[0034] An output module, used to control the phase of the output voltage to track the grid phase until the phase difference between the two is less than or equal to a preset synchronous phase difference; using the grid phase as the voltage vector wave angle to calculate and output an SVPWM waveform;

[0035] An updating module is used to obtain a phase synchronization adjustment angle according to the three-phase current output to the motor; adjust the voltage vector wave angle according to the phase synchronization adjustment angle to update the SVPWM waveform, so that the phase of the output voltage is synchronized with the phase of the power grid.

[0036] A second aspect of an embodiment of the present application proposes a frequency converter, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above-mentioned power-conversion frequency switching control method when executing the computer program.

[0037] A third aspect of an embodiment of the present application proposes an electric power device, comprising a first switch, a second switch, a memory, a frequency converter, and a computer program stored in the memory and executable on the frequency converter, wherein the input end of the frequency converter is used to connect to a variable frequency power grid, and the output end is used to connect to a motor through the first switch, and the motor is connected to an industrial frequency power grid through the second switch, and when the frequency converter executes the computer program, the steps of the industrial frequency switching control method as described above are implemented.

[0038] A fourth aspect of an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0039] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0040] The industrial frequency conversion switching control method provided in the embodiment of the present application uses the industrial frequency grid phase as the inverter voltage vector wave angle for the first phase synchronization in the process of controlling phase synchronization. Different from the conventional PID loop control, it improves the problem of not being able to quickly synchronize the grid phase under the condition of grid distortion or grid frequency fluctuation, and improves the response speed and synchronization accuracy of phase synchronization. In addition, after the first phase synchronization, a phase synchronization control strategy based on current oscillation suppression is added, which can suppress the current impact caused by the phase synchronization error, and the phase adjustment response speed is fast, so as to achieve the final phase synchronization, and effectively improve the adaptability of industrial frequency conversion switching to weak grid conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0042] Figure 1 It is a schematic diagram of the structure of a traditional power device with a frequency converter;

[0043] Figure 2 A specific flow chart of the power-converter frequency switching control method provided in one embodiment of the present application;

[0044] Figure 3 A specific flow chart of the power-converter frequency switching control method provided in one embodiment of the present application;

[0045] Figure 4 A control loop diagram of an industrial frequency conversion switching control method provided in an embodiment of the present application;

[0046] Figure 5 A schematic diagram of the structure of an industrial frequency conversion switching control device provided in an embodiment of the present application;

[0047] Figure 6 It is a structural schematic diagram of a frequency converter provided in one embodiment of the present application. DETAILED DESCRIPTION

[0048] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0049] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0050] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0051] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0052] The present application provides an industrial frequency switching control method for a frequency converter, which uses the industrial frequency grid phase as the inverter voltage vector wave angle for the first phase synchronization and adds a phase synchronization control strategy based on current oscillation suppression.

[0053] See also Figure 1 , shows an electric power device with a frequency converter, wherein the input end of the frequency converter is used to connect to the variable frequency power grid, and the output end is used to connect to the motor M through the first switch KM1, and the motor M is connected to the power frequency power grid (R / S / T) through the second switch KM2. In this example, the variable frequency power grid is the power frequency power grid (R / S / T), and in other embodiments, the variable frequency power grid can be other three-phase power sources. The first switch KM1 and the second switch KM2 are, for example, circuit breakers or contactors.

[0054] Among them, in the industrial frequency conversion control system, the AC synchronization card is used to sample the instantaneous value of the industrial frequency grid line voltage and the instantaneous value of the output voltage of the inverter output by the inverter to determine whether the output phase sequence of the industrial frequency grid and the output voltage of the inverter is consistent.

[0055] See also Figure 2 and Figure 3 In some embodiments of the present application, a power conversion frequency switching control method includes:

[0056] Step S110, obtaining the grid phase and grid frequency of the industrial frequency grid.

[0057] See also Figure 1 , the power frequency grid voltage can be sampled through the mains synchronization card, and the voltage amplitude and grid phase θ can be obtained by processing. grid and grid frequency f grid wait.

[0058] Step S120, driving the motor to run to the grid frequency.

[0059] Exemplarily, when the first switch KM1 is closed and the second switch KM2 is open, the motor M is not connected to the power grid but is connected to the inverter. Exemplarily, the external programmable logic controller (PLC) controls the switch K1 to be closed, sends a forward running signal to the S1 terminal of the inverter, controls the inverter to start, and drives the motor M to run until the rotation frequency f_set of the motor M reaches the grid frequency f grid It is understandable that in practical applications, the rotation frequency f_set reaches the grid frequency f grid When the rotation frequency is equal to the grid frequency f grid There may be acceptable deviations.

[0060] Step S130 , controlling the phase of the output voltage to track the grid phase until the phase difference between the two is less than or equal to a preset synchronous phase difference.

[0061] For example, the wave angle θ of the inverter output voltage is inv Superimpose fixed fine-tuning angle θ delta , thereby changing the wave angle θ of the inverter output voltage inv and grid phase θ grid The phase difference of the disturbance inverter output voltage quickly tracks the grid phase θ grid When the phase difference between the two is less than the preset synchronization phase difference (for example, 3-5 degrees), the first phase synchronization between the two is achieved.

[0062] Step S140, calculating and outputting the SVPWM waveform using the grid phase as the voltage vector wave angle.

[0063] Exemplarily, after a delay of a period of time, the PLC controls the switch K2 to close, sends a power frequency application signal to the S2 terminal of the inverter, and controls the inverter to start the first phase synchronization process.

[0064] The phase of the inverter output voltage and the grid phase θ grid After the first synchronization is completed, the grid phase θ grid Directly assign the wave angle θ of the inverter output voltage inv , used to calculate the voltage vector wave angle θ of the inverter and output the space vector pulse width modulation (SVPWM) waveform to the motor M, which is used to realize the phase of the inverter output voltage and the grid phase θ grid long-term phase synchronization.

[0065] Step S150, obtaining a phase synchronization adjustment angle according to the three-phase current output to the motor.

[0066] Among them, the active current component and the reactive current component of the three-phase current are decoupled, and the active current component and the reactive current component are processed separately to obtain the phase synchronization adjustment angle θ oce .

[0067] Step S160, adjusting the voltage vector wave angle θ according to the phase synchronization adjustment angle to update the SVPWM waveform so that the phase of the output voltage is synchronized with the phase of the power grid.

[0068] Adjust the angle θ according to phase synchronization oce Adjusting the voltage vector wave angle θ is used to suppress the current impact when switching the power frequency grid and the inverter output voltage in parallel without disturbance and to quickly adjust the phase of the output voltage to the grid phase θ grid Sync Fine-tune sync.

[0069] The power conversion phase synchronization technology of the embodiment of the present application directly controls the θ output by the inverter. inv Add fixed fine-tuning angle θ to the upper overlay delta , realize the phase of the inverter output voltage and the grid phase θ grid After the first synchronization is completed, the grid phase θ grid The inverter output voltage is used as the wave angle to achieve long-term phase synchronization. In addition, by using the phase synchronization control strategy based on the three-phase current oscillation suppression of the inverter output, the inverter output voltage phase is quickly adjusted to suppress current shock and achieve phase stability and real-time synchronization.

[0070] See also Figure 2 and Figure 4 In some embodiments of the present application, step S160 further includes step S170, outputting a signal for triggering the first switch KM1 to open and the second switch KM2 to close, so that the motor M is switched from being driven by the inverter to being driven by the industrial frequency grid.

[0071] In some embodiments, step S140 includes:

[0072] Step S141, assigning the output voltage wave angle to the grid phase θ grid .

[0073] Since the phase of the inverter output voltage and the grid phase θ grid After the first synchronization is completed, in order to further improve the speed of long-term phase synchronization, the output voltage of the inverter is assigned the grid phase θ grid .

[0074] Step S142, the assigned wave angle is used as the voltage vector wave angle θ to calculate and output the SVPWM waveform to drive the motor M, and the motor M is switched from the inverter drive to the industrial frequency grid drive.

[0075] See also Figure 3 In some embodiments, step S150 includes:

[0076] Step S151, obtaining the three-phase current ia, ib, ic output to the motor M.

[0077] The inverter can sample the three-phase currents ia, ib, and ic output by the inverter through the AC synchronization card.

[0078] Step S152, the three-phase currents ia, ib, ic are transformed by Park to obtain the d-axis current id and the q-axis current iq.

[0079] The active current component and the reactive current component of the three-phase current ia, ib, ic are decoupled to obtain the active current component d-axis current id and the reactive current component q-axis current iq.

[0080] Step S153: Perform high-pass filtering (HPF) on the d-axis current id and the q-axis current iq to extract the d-axis oscillation component Δi sd and the q-axis oscillation component Δi sq .

[0081] From this, we can get: the d-axis oscillation component Δi indicating the current impact caused by the inverter output voltage and the power frequency grid voltage being supplied simultaneously during the power frequency switching process without disturbance switching, or the oscillation current caused by the running oscillation of the motor itself sd and the q-axis oscillation component Δi sq .

[0082] It can be understood that both the active current component and the reactive current component will cause harmonics, which can be obtained by high-pass filtering the d-axis current id and the q-axis current iq respectively. The harmonic component d-axis oscillation component Δi caused by the d-axis current id sd, the harmonic component q-axis oscillation component Δi caused by q-axis current iq sq .

[0083] Step S153: according to the d-axis oscillation component Δi sd and the q-axis oscillation component Δi sq Get the phase synchronization adjustment angle θ oce .

[0084] The phase synchronization adjustment angle θ is obtained by performing proportional integration operation on the harmonic components according to the d-axis oscillation component and the q-axis oscillation component. oce .

[0085] See also Figure 3 In some embodiments, step S153 includes:

[0086] Step S1531: d-axis oscillation component Δi sd and the q-axis oscillation component Δi sq Add them together to get the total oscillation component.

[0087] Step S1532: taking the product of the total oscillation component and the oscillation suppression factor kp as the fine-tuning angular frequency ω oce .

[0088] Step S1533, integrating the fine-tuning angular frequency to obtain the phase synchronization adjustment angle θ oce .

[0089] In some embodiments, step S160 includes:

[0090] Step S161, when the grid phase θ grid Based on the superimposed phase synchronization adjustment angle θ oce Adjust the voltage vector wave angle θ.

[0091] Among them, the grid phase θ grid The basis is that the positive assignment is the grid phase θ grid The wave angle.

[0092] Step S162, calculating and outputting the SVPWM waveform according to the adjusted voltage vector wave angle θ.

[0093] The phase synchronization adjustment angle θ is obtained by decoupling the active current component and the reactive current component of the three-phase current ia, ib, ic and processing the active current component and the reactive current component. oce , and then adjust the angle θ with phase synchronization oce The correction value is the grid phase θ grid The wave angle is adjusted by the cyclic correction of the wave angle, so as to suppress the current impact and achieve the effect of phase stability and real-time synchronization.oce It changes dynamically during the cyclic correction process rather than being a scalar, so the control effect is better and the system robustness is higher.

[0094] In some embodiments, step S130 includes:

[0095] Step S131, obtaining the wave angle θ of the output voltage inv .

[0096] The inverter is connected to the mains synchronization card to obtain the waveform or instantaneous value of the inverter output voltage, and the wave angle θ is obtained according to the waveform or instantaneous value of the inverter output voltage. inv .

[0097] Step S132, calculate the wave angle θ inv Phase with the grid θ grid The phase difference between the two.

[0098] Step S133: When the phase difference between the two is greater than the preset synchronization phase difference, the fixed fine adjustment angle θ is used. delta Update the wave angle θ inv , until the phase difference between the two is less than or equal to the preset synchronization phase difference.

[0099] At the wave angle θ inv Greater than the grid phase θ grid In the case of inv A fixed fine-tuning angle θ will be subtracted delta Get the new wave angle θ inv , until the phase difference between the two is less than or equal to the preset synchronization phase difference. Otherwise, each time the transmission angle θ is updated inv A fixed fine-tuning angle θ will be added delta Get the new wave angle θ inv , until the phase difference between the two is less than or equal to the preset synchronization phase difference.

[0100] Among them, θ delta According to the formula θ delta =2πΔT configuration, where ΔT is the interruption time of the inverter.

[0101] In some embodiments, step 110 includes:

[0102] Step S111, obtaining the instantaneous value of the line voltage of the power frequency power grid.

[0103] The power frequency power grid is sampled by the mains synchronization card to obtain, for example, instantaneous line voltage values ​​Urs and Ust.

[0104] Step S112, the instantaneous value of the line voltage is processed by phase locking to obtain the grid phase θ grid .

[0105] The instantaneous line voltage values ​​Urs and Ust are input into the phase-locked loop to obtain the grid phase θ grid , according to the grid phase θ grid Calculate the grid frequency f grid .

[0106] In some embodiments, assuming that the motor M is an asynchronous motor, the variable frequency drive motor M is started and the process proceeds to step 120, which includes the following steps:

[0107] A. The excitation device is energized.

[0108] A certain excitation current is passed through the excitation winding of the motor M to establish a certain magnetic field on the rotor of the motor M.

[0109] B. Apply a certain DC voltage to the armature winding of motor M to generate a certain stator current.

[0110] At this time, a certain stator current is generated on the motor M, and a strong magnetic field is established on the stator. The rotor begins to rotate under the action of the electromagnetic force between the stator and rotor, causing the rotor magnetic poles to gradually approach the opposite end of the stator magnetic poles. At this time, the direction of rotation of the rotor may be the same as the direction of rotation during normal operation of the motor, or it may be opposite.

[0111] C. Slowly rotate the voltage vector applied to the armature winding in the same direction as the motor's normal rotation direction.

[0112] As the motor M rotor rotates and the stator magnetic field rotates, the rotor magnetic pole will pass over the stator magnetic pole of opposite polarity at a certain moment, or the rotor magnetic pole will accelerate to catch up with the rotating stator magnetic pole. At this time, the motor's rotor magnetic pole is reliably attracted by the stronger stator magnetic pole, and the angle between the two gradually tends to a smaller constant after a small amount of damped oscillation. At this point, the motor M enters the synchronous operation state, and the whole process is completed.

[0113] D. According to the preset acceleration and v / f curve (i.e. flux given), adjust the inverter output voltage and gradually accelerate to the grid frequency.

[0114] At this time, the rotor angle of the motor M gradually increases to a certain constant value, and then the motor rotor poles are gradually accelerated to the desired speed under the attraction of the stator magnetic field, and the starting process of the motor M is completed.

[0115] See also Figure 1 In some embodiments, the first control port RO1 and the second control port RO2 of the frequency converter are connected to the first switch KM1 and the second switch KM2 respectively.

[0116] Step 170 includes:

[0117] Outputting a first control signal to the first switch KM1 through the first control port RO1 to control the first switch KM1 to be disconnected;

[0118] The second control signal for controlling the second switch KM2 to be closed is output to the first switch through the second control port RO2.

[0119] For example, the industrial frequency conversion switching can be completed by the inverter control according to the user settings. If the user chooses the inverter to directly control the industrial frequency conversion contactor, the inverter outputs the disconnection and attraction control signals to the first switch KM1 and the second switch KM2 through the first control port RO1 and the second control port RO2 to complete the industrial frequency conversion switching.

[0120] In some embodiments, the indication port of the frequency converter is connected to a controller (eg, a PLC), and the controller is connected to the first switch KM1 and the second switch KM2 respectively.

[0121] Step 170 includes:

[0122] An indication signal indicating that the power-converter switching is ready is output to the controller through the indication port, and the controller is used to control the first switch KM1 to be opened and the second switch KM2 to be closed according to the indication signal.

[0123] Exemplarily, the industrial frequency conversion switching is completed by PLC control according to the user settings. If the user chooses PLC to control the first switch KM1 and the second switch KM2, the inverter and the indication port send an industrial frequency conversion switching ready signal to the PLC, and the PLC controls the first switch KM1 and the second switch KM2 to disconnect and attract, thereby completing the industrial frequency conversion switching.

[0124] See also Figure 1 , the power equipment with frequency converter can choose whether to add reactor L as needed. At this time, during the power-to-frequency conversion switching, the first switch KM1 and the second switch KM2 have different closing timings: if the reactor L is added, the second switch KM2 is closed first during the power-to-frequency conversion switching. After the second switch KM2 is closed, the power grid and the frequency converter output voltage are used to supply power to the motor M at the same time, and then the first switch KM1 is disconnected to complete the power-to-frequency conversion switching. If there is no reactor L, the first switch KM1 is disconnected first, and the second switch KM2 is closed after the first switch KM1 is completely disconnected to complete the power-to-frequency conversion switching.

[0125] See also Figure 5 The second aspect of the embodiment of the present application proposes an industrial variable frequency switching control device comprising:

[0126] An acquisition module 501 is used to acquire a power grid phase and a power grid frequency of an industrial frequency power grid;

[0127] A driving module 502, used for driving the motor to operate at the grid frequency;

[0128] The output module 503 is used to control the phase of the output voltage to track the grid phase until the phase difference between the two is less than or equal to the preset synchronous phase difference; the grid phase is used as the voltage vector wave angle to calculate and output the SVPWM waveform;

[0129] The updating module 504 is used to obtain a phase synchronization adjustment angle according to the three-phase current output to the motor; adjust the voltage vector wave angle according to the phase synchronization adjustment angle to update the SVPWM waveform so that the phase of the output voltage is synchronized with the phase of the power grid.

[0130] In some embodiments, the update module 504 includes:

[0131] An acquisition unit, used for acquiring a three-phase current output to the motor;

[0132] A conversion unit, used for obtaining a d-axis current and a q-axis current by performing Park transformation on the three-phase current;

[0133] A filtering unit, used for performing high-pass filtering on the d-axis current and the q-axis current to extract a d-axis oscillation component and a q-axis oscillation component respectively;

[0134] A processing unit is used to obtain a phase synchronization adjustment angle according to the d-axis oscillation component and the q-axis oscillation component.

[0135] In some embodiments, the processing unit includes:

[0136] a summing subunit, used for summing the d-axis oscillation component and the q-axis oscillation component to obtain a total oscillation component;

[0137] A multiplication subunit, used for taking the product of the total oscillation component and the oscillation suppression factor as the fine-tuning angular frequency;

[0138] The integration subunit is used to integrate the fine-tuning angular frequency to obtain a phase synchronization adjustment angle.

[0139] In some embodiments, the update module 504 includes:

[0140] A superposition subunit, configured to adjust the voltage vector wave angle by superimposing the phase synchronization adjustment angle on the basis of the grid phase;

[0141] The calculation subunit is used to calculate and output the SVPWM waveform according to the adjusted voltage vector wave angle.

[0142] In some embodiments, the output module 503 includes:

[0143] An assignment unit, used for assigning the wave angle of the output voltage to the grid phase;

[0144] The output unit is used to calculate and output the SVPWM waveform by using the assigned wave generation angle as the voltage vector wave generation angle.

[0145] In some embodiments, the output module 503 further includes:

[0146] An acquisition subunit, used for acquiring a wave angle of the output voltage;

[0147] A calculation subunit, used for calculating the phase difference between the wave transmission angle and the grid phase;

[0148] The updating subunit updates the transmitting angle with a fixed fine-tuning angle when the phase difference between the two is greater than the preset synchronous phase difference until the phase difference between the two is less than or equal to the preset synchronous phase difference.

[0149] For the specific implementation of the above-mentioned industrial frequency conversion switching control device and the description of related beneficial effects, please refer to the description of the specific embodiment of the above-mentioned industrial frequency conversion switching control method, which will not be repeated here.

[0150] See also Figure 6 The second aspect of the embodiment of the present application proposes a frequency converter, including a memory 62, a processor 63, and a computer program 621 stored in the memory 62 and executable on the processor 63. When the processor 63 executes the computer program 621, the steps of the above-mentioned industrial frequency conversion switching control method are implemented.

[0151] See also Figure 1 According to a third aspect of an embodiment of the present application, an electric power device is proposed, comprising a first switch KM1, a second switch KM2, a memory, a frequency converter, and a computer program stored in the memory and executable on the frequency converter. The input end of the frequency converter is used to connect to a variable frequency power grid, and the output end is used to connect to a motor through the first switch KM1. The motor is connected to the industrial frequency power grid through the second switch KM2. When the frequency converter executes the computer program, the steps of the industrial frequency switching control method are implemented.

[0152] Those skilled in the art will understand that Figure 1 These are merely examples of electrical equipment and do not constitute limitations on the electrical equipment. The equipment may include more or fewer components than those shown in the figure, or a combination of certain components, or different components, and may also include input and output devices, network access devices, etc.

[0153] The processor 63 may be a central processing unit (CPU), or may be other general controllers, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general controller may be a microcontroller or any conventional controller.

[0154] In some embodiments, the memory 62 may be an internal storage unit of the power device 60, such as a hard disk or memory of the power device 60. In other embodiments, the memory 62 may also be an external storage device of the power device 60, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the power device 60. Further, the memory 62 may also include both an internal storage unit of the power device 60 and an external storage device. The memory 62 is used to store an operating system, an application program, a boot loader, data, and other programs. The memory 62 may also be used to temporarily store data that has been output or is to be output.

[0155] The embodiment of the present application further provides a computer-readable storage medium, which stores a computer program 621. When the computer program 621 is executed by the processor 63, the steps in the above-mentioned method embodiments can be implemented.

[0156] An embodiment of the present application provides a computer program product, which, when executed on a computer, enables the computer to execute the steps in the above-mentioned method embodiments.

[0157] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the processes in the above method embodiments, which can be completed by instructing the relevant hardware through a computer program 621. The computer program 621 can be stored in a computer-readable storage medium. When the computer program 621 is executed by the processor 63, the steps of the above method embodiments can be implemented. Among them, the computer program 621 includes a computer program 621 code, and the computer program 621 code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may at least include: any entity or device that can carry the computer program 621 code to the camera device / terminal device, a recording medium, a computer memory 62, a ROM (Read-Only Memory, read-only memory 62), a RAM (Random Access Memory, random access memory 62), a CD-ROM (Compact Disc Read-Only Memory, read-only optical disc), a magnetic tape, a floppy disk and an optical data storage device. The computer-readable storage medium mentioned in the present application may be a non-volatile storage medium, in other words, a non-transitory storage medium.

[0158] It should be understood that all or part of the steps to implement the above embodiments can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, it can be implemented in whole or in part in the form of a computer program 621 product. The computer program 621 product includes one or more computer instructions. The computer instructions can be stored in the above-mentioned computer readable storage medium.

[0159] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0160] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0161] In the embodiments provided in the present application, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. For example, the device / electronic device embodiments described above are merely schematic. For example, the division of modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0162] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0163] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A power conversion switching control method, characterized in that: The frequency converter is connected to the variable frequency power grid and the motor respectively; the motor is connected to the power frequency power grid; the control method includes: Obtaining the grid phase and grid frequency of the industrial frequency grid; Driving the motor to operate at the grid frequency; Controlling the phase of the output voltage to track the grid phase until the phase difference between the two is less than or equal to a preset synchronous phase difference; Calculate and output SVPWM waveform using the grid phase as the voltage vector wave angle; Obtaining a phase synchronization adjustment angle according to the three-phase current output to the motor; The voltage vector wave generation angle is adjusted according to the phase synchronization adjustment angle to update the SVPWM waveform, so that the phase of the output voltage is synchronized with the phase of the power grid.

2. The control method according to claim 1, characterized in that: The step of obtaining a phase synchronization adjustment angle according to the three-phase current output to the motor includes: Acquiring three-phase current output to the motor; The three-phase current is transformed by Park to obtain a d-axis current and a q-axis current; Performing high-pass filtering on the d-axis current and the q-axis current to extract a d-axis oscillation component and a q-axis oscillation component respectively; A phase synchronization adjustment angle is obtained according to the d-axis oscillation component and the q-axis oscillation component.

3. The control method according to claim 2, characterized in that: The obtaining of the phase synchronization adjustment angle according to the d-axis oscillation component and the q-axis oscillation component comprises: Summing the d-axis oscillation component and the q-axis oscillation component to obtain a total oscillation component; The product of the total oscillation component and the oscillation suppression factor is used as the fine-tuning angular frequency; The fine-tuning angular frequency is integrated to obtain the phase synchronization adjustment angle.

4. The control method according to any one of claims 1 to 3, characterized in that: The step of adjusting the voltage vector wave angle according to the phase synchronization adjustment angle to update the SVPWM waveform includes: The voltage vector wave generating angle is adjusted by superimposing the phase synchronization adjustment angle on the basis of the grid phase; The SVPWM waveform is calculated and outputted according to the adjusted voltage vector wave angle.

5. The control method according to any one of claims 1 to 3, characterized in that: The method of calculating and outputting the SVPWM waveform using the grid phase as the voltage vector wave angle comprises: Assigning the wave angle of the output voltage to the grid phase; The assigned wave generation angle is used as the voltage vector wave generation angle to calculate and output the SVPWM waveform.

6. The control method according to any one of claims 1 to 3, characterized in that: The step of controlling the phase of the output voltage to track the grid phase until the phase difference between the two is less than or equal to a preset synchronous phase difference includes: Obtaining a wave angle of the output voltage; Calculating the phase difference between the wave transmission angle and the grid phase; In the case where the phase difference between the two is greater than the preset synchronization phase difference, the transmission angle is updated with a fixed fine-tuning angle until the phase difference between the two is less than or equal to the preset synchronization phase difference.

7. An industrial frequency conversion switching control device, characterized in that: The device is arranged on a frequency converter, and the frequency converter is connected to a variable frequency power grid and a motor respectively; the motor is connected to an industrial frequency power grid; the device comprises: An acquisition module, used for acquiring a grid phase and a grid frequency of an industrial frequency grid; A driving module, used for driving the motor to operate at the grid frequency; An output module, used to control the phase of the output voltage to track the grid phase until the phase difference between the two is less than or equal to a preset synchronous phase difference; using the grid phase as the voltage vector wave angle to calculate and output an SVPWM waveform; An updating module is used to obtain a phase synchronization adjustment angle according to the three-phase current output to the motor; adjust the voltage vector wave angle according to the phase synchronization adjustment angle to update the SVPWM waveform, so that the phase of the output voltage is synchronized with the phase of the power grid.

8. A frequency converter, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the power frequency conversion switching control method as claimed in any one of claims 1 to 6 when executing the computer program.

9. An electric power device, characterized in that: The method comprises a first switch, a second switch, a memory, a frequency converter, and a computer program stored in the memory and executable on the frequency converter, wherein the input end of the frequency converter is used to connect to a variable frequency grid, the output end is used to connect to a motor through the first switch, the motor is connected to an industrial frequency grid through the second switch, and the frequency converter implements the steps of the industrial frequency switching control method as claimed in any one of claims 1 to 6 when executing the computer program.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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