Adjustable reactor, frequency converter and control method

Abstract

The invention discloses an adjustable reactor, a frequency converter and a control method. The adjustable reactor comprises at least two adjustable inductors which are arranged in series; the low-pass filter is used for filtering a higher harmonic component in a current sampling signal of the input current of the rectification module and then outputting the filtered current sampling signal; the first input end of the processing chip inputs a filtered current sampling signal, the second input end of the processing chip inputs a current sampling signal before filtering, and the processing chip is used for calculating a current distortion rate according to the filtered current sampling signal and the current sampling signal before filtering and then outputting a driving signal according to the current distortion rate; and the driving module is used for adjusting the number of the input adjustable inductors and the inductance values of the input adjustable inductors according to the driving signal so as to adjust the reactance value of the adjustable reactor. According to the invention, the workload of developers can be reduced, and the product development cycle can be shortened.

Description

Technical Field

[0001] The present invention relates to the field of electronic power technology, and in particular to an adjustable reactor, a frequency converter and a control method. Background Art

[0002] With the rapid development of variable frequency speed regulation technology, the use of frequency converters has become more and more widespread. Standardizing the design, selection and production of suitable radio interference suppression reactors, power supply side AC reactors, DC reactors, and output side AC reactors of variable frequency speed regulation control systems, so that the variable frequency speed regulation system can operate stably, reliably, and with low failure rate, can not only improve production quality and efficiency, but also obtain good economic benefits, and also have extremely important significance for social benefits such as energy saving, environmental protection, and improving the quality of power supply of power grids. Practice has proved that selecting suitable reactors to match the frequency converter can not only suppress harmonics and improve the power factor of the frequency converter, but also suppress the impact of surge current from the power grid on the frequency converter, and ensure the reliable operation of the frequency converter.

[0003] At present, high-power inverters have high operating currents, and copper busbars are generally used for wiring. The inductors used in conjunction with them are large in size and high in cost. If the harmonic test fails, a new inductor must be replaced for testing. Before replacing the inductor, the inverter structure and copper busbar structure need to be changed. On the one hand, this causes a waste of inductor development costs and increases the workload of rectification. On the other hand, it prolongs the rectification cycle and affects the progress of product development.

[0004] In the prior art, the parameters of the reactor in the inverter are fixed. Once the harmonic test fails, the inverter needs to be disassembled and the reactor replaced, which increases the workload and prolongs the product development cycle. No effective solution has been proposed so far. Summary of the invention

[0005] An adjustable reactor, a frequency converter and a control method are provided in the embodiments of the present invention to solve the problem that the parameters of the reactor in the frequency converter in the prior art are fixed. Once the harmonic test fails, the frequency converter needs to be disassembled and the reactor needs to be replaced, which increases the workload and prolongs the product development cycle.

[0006] In order to solve the above technical problems, the present invention provides an adjustable reactor, which is applied to a frequency converter, wherein the frequency converter includes a rectifier module and an inverter module, and the adjustable reactor includes:

[0007] at least two adjustable inductors arranged in series;

[0008] A low-pass filter, used to filter out the high-order harmonic components in the current sampling signal of the input current of the rectifier module, and then output the filtered current sampling signal;

[0009] A processing chip, a first input terminal of which inputs a filtered current sampling signal, and a second input terminal of which inputs a pre-filtered current sampling signal, for calculating a current distortion rate according to the filtered current sampling signal and the pre-filtered current sampling signal, and then outputting a driving signal according to the current distortion rate;

[0010] The driving module is used to adjust the number of the adjustable inductors and the inductance of the adjustable inductors according to the driving signal, thereby adjusting the reactance value of the adjustable reactor.

[0011] Furthermore, the adjustable inductor comprises:

[0012] A plurality of single-turn coils, each of which is connected in parallel with a switch, and the processing chip is used to control the number of switches turned on in the adjustable inductor according to the current distortion rate, thereby adjusting the inductance value of the adjustable inductor.

[0013] Furthermore, the switch is a DC contactor, and the DC contactor comprises:

[0014] A coil, a first contact and a second contact, wherein the first end of the coil is connected to a voltage source, the second end of the coil is grounded through a switch tube, the first contact is connected to the first end of the single-turn coil of the adjustable inductor, and the second contact is connected to the second end of the single-turn coil of the adjustable inductor.

[0015] The present invention also provides a frequency converter, comprising a rectifier module and an inverter module, and also comprising the above-mentioned adjustable reactor.

[0016] The present invention also provides a control method, which is applied to the above-mentioned adjustable reactor, and the control method comprises:

[0017] Calculating a current distortion rate according to the current sampling signal after filtering and the current sampling signal before filtering;

[0018] The number of the adjustable inductors and the inductance of the adjustable inductors are adjusted according to the current distortion rate, thereby adjusting the reactance value of the adjustable reactor.

[0019] Further, calculating the current distortion rate according to the filtered current sampling signal and the unfiltered current sampling signal includes:

[0020] Obtaining the signal value of the filtered current sampling signal;

[0021] Subtracting the signal value of the current sampling signal before filtering from the signal value of the direct current and the current sampling signal after filtering to obtain a high-order harmonic component;

[0022] The ratio of the high-order harmonic component to the fundamental signal component in the filtered current sampling signal is calculated to obtain the current distortion rate.

[0023] Further, adjusting the number of adjustable inductors and the inductance of the adjustable inductors according to the current distortion rate includes:

[0024] Determining the interval in which the current distortion rate is located;

[0025] The number of the adjustable inductors and the inductance values ​​of the adjustable inductors are controlled according to the interval in which the current distortion rate is located.

[0026] Furthermore, the number of adjustable inductors to be used is controlled according to the interval in which the current distortion rate is located, including:

[0027] If the current distortion rate is greater than the first threshold, it is determined whether the inductance value of each currently-input adjustable inductor has reached a maximum; if so, the number of the currently-input adjustable inductors is controlled to increase; if not, the inductance value of at least one currently-input adjustable inductor is controlled to increase;

[0028] If the current distortion rate is less than or equal to the first threshold value and greater than the second threshold value, the number of the adjustable inductors input is controlled to remain unchanged;

[0029] If the current distortion rate is less than the second threshold, it is determined whether the inductance of each adjustable inductor currently in use has reached the minimum; if so, the number of adjustable inductors currently in use is controlled to decrease; if not, the inductance of at least one adjustable inductor currently in use is controlled to decrease.

[0030] Further, controlling the inductance value of the at least one adjustable inductor currently in use to increase includes:

[0031] Controlling the number of switches turned on in the adjustable inductor to decrease, thereby controlling the number of single-turn coils turned on in the adjustable inductor to increase, thereby controlling the inductance value of the adjustable inductor to increase;

[0032] Wherein, the switch is arranged in parallel with the single-turn coil.

[0033] Further, controlling the inductance value of the at least one adjustable inductor currently in use to decrease includes:

[0034] Controlling the number of switches turned on in the adjustable inductor to increase, thereby controlling the number of single-turn coils turned on in the adjustable inductor to decrease, thereby controlling the inductance value of the adjustable inductor to decrease;

[0035] Wherein, the switch is arranged in parallel with the single-turn coil.

[0036] The present invention also provides a computer-readable storage medium on which a computer program is stored, and the program implements the above control method when executed by a processor.

[0037] The present invention also provides an electronic device, comprising:

[0038] one or more processors;

[0039] The storage device is used to store one or more programs, and when the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned control method.

[0040] By applying the technical solution of the present invention, the current distortion rate is calculated according to the current sampling signal after filtering and the current sampling signal before filtering through the processing chip, and then the driving signal is output according to the current distortion rate, so as to adjust the number of adjustable inductors invested in the reactor and the inductance value of the invested adjustable inductors, and then adjust the reactance value of the adjustable reactor. It is possible to adjust the reactance value of the adjustable reactor according to the harmonic content. When the harmonic test fails, there is no need to disassemble the inverter and replace the reactor, which can reduce the workload of developers and shorten the product development cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a structural diagram of an adjustable reactor according to an embodiment of the present invention;

[0042] Figure 2 is a structural diagram of a frequency converter according to an embodiment of the present invention;

[0043] Figure 3 is a flow chart of a control method according to an embodiment of the present invention;

[0044] Figure 4 is a flow chart of a control method according to another embodiment of the present invention;

[0045] Figure 5 FIG. 4 is a schematic diagram of the hardware structure of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings, and "multiple" generally includes at least two.

[0048] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0049] It should be understood that, although the terms first, second, etc. may be used to describe thresholds in embodiments of the present invention, these thresholds should not be limited to these terms. These terms are only used to distinguish different thresholds. For example, without departing from the scope of embodiments of the present invention, the first threshold may also be referred to as the second threshold, and similarly, the second threshold may also be referred to as the first threshold.

[0050] As used herein, the words "if" and "if" may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0051] It should also be noted that the term "includes", "comprising" or any other variation thereof is intended to cover non-exclusive inclusion, so that a commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprising a ..." do not exclude the existence of other identical elements in the commodity or device including the elements.

[0052] The optional embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0053] Example 1

[0054] At present, high-power inverters have high operating currents, and copper busbars are generally used for wiring. The inductors used in conjunction with them are large in size and high in cost. If the harmonic test fails, a new inductor must be replaced for testing. Before replacing the inductor, the inverter structure and copper busbar structure need to be changed. On the one hand, this causes a waste of inductor development costs and increases the workload of rectification. On the other hand, it prolongs the rectification cycle and affects the progress of product development.

[0055] In view of the problem that the parameters of the reactor in the inverter in the prior art are fixed, once the harmonic test fails, the reactor needs to be replaced, which increases the workload and prolongs the product development cycle, this embodiment provides an adjustable reactor, which is applied to the inverter, and the inverter includes a rectifier module and an inverter module. Figure 1 is a structural diagram of an adjustable reactor according to an embodiment of the present invention, as shown Figure 1 As shown, the adjustable reactor includes: at least two adjustable inductors arranged in series; in this embodiment, the adjustable reactor includes two adjustable inductors, a first adjustable inductor L1 and a second adjustable inductor L2. In other embodiments of the present invention, the number of adjustable inductors can be set according to actual needs, such as two, three, four... or more; a low-pass filter 1, which is used to filter out the high-order harmonic components in the current sampling signal of the input current of the rectifier module, and then output the filtered current sampling signal. The current sampling signal is obtained by setting a current sensor on each phase circuit of the input end of the rectifier module. The processing chip 2, whose first input end inputs the filtered current sampling signal, and whose second input end inputs the current sampling signal before filtering, is used to calculate the current distortion rate according to the filtered current sampling signal and the current sampling signal before filtering, and then output the drive signal according to the current distortion rate. The current distortion rate can reflect the harmonic content. The larger the current distortion rate, the higher the harmonic content. The driving module 3 is used to adjust the number of the adjustable inductors and the inductance of the adjustable inductors according to the driving signal, thereby adjusting the reactance value of the adjustable reactor.

[0056] The variable reactor of the present embodiment calculates the current distortion rate according to the current sampling signal after filtering and the current sampling signal before filtering through the processing chip, and then outputs a driving signal according to the current distortion rate, adjusts the number of adjustable inductors invested in the reactor and the inductance value of the invested adjustable inductors, and then adjusts the reactance value of the adjustable reactor. It is possible to adjust the reactance value of the adjustable reactor according to the harmonic content. When the harmonic test fails, there is no need to disassemble the inverter and replace the reactor, which can reduce the workload of developers and shorten the product development cycle.

[0057] The adjustable inductor comprises: a plurality of single-turn coils, each of which is connected in parallel with a switch, such as Figure 1 As shown, the single-turn coil in the first adjustable inductor L1 is l 11 ~l 1n , the corresponding switch is S 11 ~S 1n , S 11 ~S 1n The first switch group S1 is formed, and the single-turn coil in the second adjustable inductor L2 is l 21 ~l 2n , the corresponding switch is S 21 ~S 2n , S 21 ~S 2nThe first switch group S2 is formed. The processing chip 2 controls the number of switches turned on in the adjustable inductor according to the current distortion rate, thereby adjusting the inductance value of the adjustable inductor. Specifically, since the single-turn coil and its corresponding switch are in parallel, when the corresponding switch is turned on, the single-turn coil is short-circuited and not connected to the circuit. When the corresponding switch is turned off, the single-turn coil is turned on and connected to the circuit. Therefore, by controlling the on-off of the above-mentioned switch, the on-off of the single-turn coil can be controlled, and then the number of turns of the coil connected to the circuit can be controlled. The more single-turn coils connected, the greater the inductance value. Therefore, the inductance value of the adjustable inductor can be controlled by controlling the on-off of the above-mentioned switch. Further, the adjustable inductors are connected in series. The more the number of adjustable inductors connected in series, the greater the inductance value. Therefore, by controlling the number of adjustable inductors put in, the inductance value of the entire reactor can also be adjusted, that is, the reactance value of the adjustable reactor can be adjusted.

[0058] There are many types of switches, such as relays, contactors, MOS tubes, transistors, etc. In this embodiment, the switch is a DC contactor, such as Figure 1 As shown, the DC contactor includes: a coil, a first contact a and a second contact b, the first end of the coil is connected to a voltage source VCC, the second end of the coil is grounded through a switch tube, the first contact a is connected to the first end of a single-turn coil of adjustable inductance, and the second contact b is connected to the second end of the single-turn coil of adjustable inductance.

[0059] Example 2

[0060] This embodiment provides a frequency converter. Figure 2 : is a structural diagram of a frequency converter according to an embodiment of the present invention, Figure 2 As shown, the frequency converter includes a rectifier module 10 and an inverter module 20, and also includes the adjustable reactor in the above embodiment.

[0061] Example 3

[0062] This embodiment provides a control method, which is applied to the adjustable reactor in the above embodiment. Figure 3 is a flow chart of a control method according to an embodiment of the present invention, as shown in Figure 3 As shown, the control method includes:

[0063] S101, calculating the current distortion rate according to the current sampling signal after filtering and the current sampling signal before filtering.

[0064] The current distortion rate can reflect the harmonic content. The larger the current distortion rate, the higher the harmonic content.

[0065] S102, adjusting the number of adjustable inductors and the inductance values ​​of the adjustable inductors according to the current distortion rate, and then adjusting the reactance value of the adjustable reactor.

[0066] The more single-turn coils that the adjustable inductor is connected to, the greater the inductance value. At the same time, the more adjustable inductors are connected in series, the greater the inductance value. Therefore, by controlling the number of adjustable inductors put into use, the inductance value of the entire reactor can also be adjusted, that is, the reactance value of the adjustable reactor can be adjusted.

[0067] The control method of this embodiment calculates the current distortion rate based on the current sampling signal after filtering and the current sampling signal before filtering, and adjusts the number of adjustable inductors and the inductance of the adjustable inductors in the reactor according to the current distortion rate. It can adjust the reactance value of the adjustable reactor according to the harmonic content. When the harmonic test fails, there is no need to disassemble the inverter and replace the reactor, which can reduce the workload of developers and shorten the product development cycle.

[0068] The higher the harmonic content, the higher the reactance value of the reactor needs to be, that is, the higher the inductance value of the adjustable inductor needs to be. In order to accurately judge the harmonic content so as to facilitate the subsequent precise adjustment of the reactance value of the adjustable reactor, the current distortion rate is calculated based on the current sampling signal after filtering and the current sampling signal before filtering, including: obtaining the signal value of the current sampling signal after filtering; subtracting the signal value of the current sampling signal before filtering from the signal value of the direct current and the current sampling signal after filtering to obtain higher harmonic components; calculating the ratio of the higher harmonic components to the fundamental signal component in the filtered current sampling signal to obtain the current distortion rate.

[0069] When the inverter cabinet is powered by three-phase electricity, it works normally, and the current sensor takes samples, and the sampled current signal containing high-order harmonics is:

[0070] Among them, I N is the sampling current signal, I0 is the DC signal component, I1 is the fundamental signal component. Due to interference in the mains, or the frequency converter is not a pure resistor, the calculated current is a calculation formula composed of multiple harmonic components. Generally, only odd harmonics exist (1, 3, 5, 7...), and even harmonics will be offset according to the calculation formula. The most important component in a signal is the fundamental signal component (the heaviest proportion), and other high-order harmonic components are just transformed on it. The high-order harmonic signal I h It is the sum of all higher harmonics except the fundamental wave I1. The above sampling current signal is input into the processing chip. The sampling current of one path first passes through a low-pass filter to filter out the DC and fundamental wave. External high-order harmonic signal I h Then, the DC and fundamental components at this time are subtracted from the input current of another circuit to obtain the high-order harmonic components in the input current. The high-order harmonic component and the input signal are calculated by DSP to calculate the harmonics, that is, to calculate the current distortion rate.

[0071] The inductor has the function of passing direct current and blocking alternating current, that is, it has the function of suppressing high-order harmonic components. The larger the inductance, the lower the harmonic components. In order to ensure that the inductance value of the adjustable inductor matches the current distortion rate and ensure that the current distortion rate is within a preset range after adjustment, the number of adjustable inductors put in and the inductance value of the adjustable inductors put in are adjusted according to the current distortion rate, including: judging the range where the current distortion rate is located; controlling the number of adjustable inductors put in and the inductance value of the adjustable inductors put in according to the range where the current distortion rate is located.

[0072] The overall inductance value of the reactor can be roughly adjusted by controlling the number of at least one adjustable inductor, and can also be finely adjusted by adjusting the inductance value of at least one adjustable inductor. Coarse adjustment can improve the adjustment efficiency, and fine adjustment can ensure the adjustment accuracy. In order to take into account both the adjustment efficiency and the adjustment accuracy, the number of adjustable inductors put in is controlled according to the interval in which the current distortion rate is located, including: if the current distortion rate is greater than a first threshold, then judging whether the inductance value of each adjustable inductor currently put in reaches a maximum; if so, controlling the number of adjustable inductors put in to increase; if not, controlling the inductance value of at least one adjustable inductor currently put in to increase; if the current distortion rate is less than or equal to the first threshold and greater than a second threshold, controlling the number of adjustable inductors put in to remain unchanged; if the current distortion rate is less than the second threshold, judging whether the inductance value of each adjustable inductor currently put in reaches a minimum; if so, controlling the number of adjustable inductors put in to decrease; if not, controlling the inductance value of at least one adjustable inductor currently put in to decrease.

[0073] Since the single-turn coil and its corresponding switch are in parallel relationship, when the corresponding switch is turned on, the single-turn coil is short-circuited and is not connected to the circuit, and when the corresponding switch is turned off, the single-turn coil is turned on and connected to the circuit. Therefore, by controlling the on-off of the above-mentioned switch, the on-off of the single-turn coil can be controlled, and then the number of turns of the coil connected to the circuit can be controlled. The more single-turn coils are connected, the greater the inductance value. Therefore, controlling the inductance value of the at least one adjustable inductor currently in use to increase includes: controlling the number of switches turned on in the adjustable inductor to decrease, and then controlling the number of single-turn coils turned on in the adjustable inductor to increase, and then controlling the inductance value of the adjustable inductor to increase; wherein the switch is arranged in parallel with the single-turn coil.

[0074] Controlling the inductance value of at least one currently-in-use adjustable inductor to decrease includes: controlling the number of switches turned on in the adjustable inductor to increase, thereby controlling the number of single-turn coils turned on in the adjustable inductor to decrease, thereby controlling the inductance value of the adjustable inductor to decrease; wherein the switch is arranged in parallel with the single-turn coil.

[0075] Example 4

[0076] This embodiment provides another control method. Figure 4 is a flow chart of a control method according to another embodiment of the present invention, Figure 4 As shown, the control method includes:

[0077] S1, obtaining the current sampling signal at the input end of the rectifier module.

[0078] The current sampling signal is obtained by arranging a current sensor on each phase circuit at the input end of the rectifier module.

[0079] S2, obtain the current sampling signal after low-pass filtering.

[0080] S3, calculating the difference between the current sampling signal at the input end of the rectifier module and the current sampling signal after low-pass filtering, obtaining the high-order harmonic components of the current sampling signal, and then obtaining the current distortion rate.

[0081] When the inverter cabinet is powered by three-phase electricity, it works normally, and the current sensor takes samples, and the sampled current signal containing high-order harmonics is:

[0082] Among them, I N is the sampling current signal, I0 is the DC signal component, I1 is the fundamental signal component. Due to interference in the mains, or the frequency converter is not a pure resistor, the calculated current is a calculation formula composed of multiple harmonic components. Generally, only odd harmonics exist (1, 3, 5, 7...), and even harmonics will be offset according to the calculation formula. The most important component in a signal is the fundamental signal component (the heaviest proportion), and other high-order harmonic components are just transformed on it. The high-order harmonic signal I h It is the sum of all higher harmonics except the fundamental wave I1. The above sampling current signal is input into the processing chip. The sampling current of one path first passes through a low-pass filter to filter out the DC and fundamental wave. External high-order harmonic signal I h Then, the DC and fundamental components at this time are subtracted from the input current of another circuit to obtain the high-order harmonic components in the input current. The high-order harmonic component and the input signal are calculated by DSP to calculate the harmonics, that is, to calculate the current distortion rate. To determine the range of the current distortion rate at this time, the ideal current distortion rate range should be between [32% and 35%].

[0083] S4, determine the range of the current distortion rate; if the current distortion rate is greater than 35%, execute step S5; if 32%≤current distortion rate≤35%, execute step S6; if the current distortion rate is less than 32%, execute step S7.

[0084] S5, controlling the overall inductance value of the adjustable inductor to increase, thereby controlling the reactance value of the reactor to increase.

[0085] S6, controls the overall inductance value of the adjustable inductor to remain unchanged, thereby controlling the reactance value of the reactor to remain unchanged.

[0086] S7, controlling the overall inductance value of the adjustable inductor to decrease, thereby controlling the reactance value of the reactor to decrease.

[0087] When the distortion rate is greater than 35%, the technical condition that the harmonic requirement specified in the enterprise standard should be less than 35% is not met. Under the premise that all single-turn coils of the first adjustable inductor L1 are connected, the driving module drives the second switch group to operate, so that the coil KT2 corresponding to each switch in the second switch group S2 is powered on, so that all switches S2 in the second switch group S2 are powered on. 21 ~S 2n The first contact and the second contact are both disconnected, so that all the single-turn coils of the second adjustable inductor L2 are connected, and then the opening and closing states of some switches in the second switch group S2 are adjusted according to the idea of ​​quantized differentiation, so that some switches are turned on, so that some single-turn coils are short-circuited, and the inductance corresponding to the other disconnected switches is connected to the circuit, so as to increase the reactance inductance in the circuit. The inductor has the function of passing direct current and blocking alternating current, that is, it has the function of suppressing high-order harmonic components. The inductance increases, the harmonic components decrease, and the current distortion rate THDi decreases accordingly. The idea of ​​differentiation is adopted, and each small section of inductance is subdivided by the number of switches. The more switches there are, the finer the subdivision of the inductance is, and the finer the increase in inductance controlled by DSP is, which leads to a higher accuracy in controlling the current distortion rate.

[0088] In addition, the current distortion rate cannot be too low in reality. When the distortion rate is less than 32%, the inductance of the reactance used will increase, resulting in an increase in the volume of the reactance used in the frequency converter cabinet. The designed frequency converter cabinet is generally solid in size, and the increase in the volume of the reactance will inevitably compress the circuit routing inside the electric control box, resulting in failure to meet the safety spacing requirements for the electrical routing. Increasing the volume of the electric control box will inevitably increase the cost, which is equivalent to a major change in the overall framework and logical architecture. This is not what we need. In this embodiment, when the distortion rate is less than 32%, the drive module drives the coil KT1 corresponding to each switch in the first switch group S1 to be energized and work, so that all switches S in the first switch group S1 11 ~S 1nThe first contact and the second contact are both disconnected, so that all the single-turn coils of the first adjustable inductor L1 are connected. The coils play a role in distinguishing the small current of the control logic around the chip from the strong current of the frequency converter cabinet, which is safe and reliable. Then, each switch in the first switch group S is controlled to change from the disconnected state to the on state, which is reflected in the circuit as short-circuiting some of the single-turn coils in the first adjustable inductor L1, thereby achieving the purpose of reducing the inductance value of the first adjustable inductor L1. When the inductance value is reduced, the harmonic component content naturally increases, thereby controlling the current distortion rate THDi within a variable range.

[0089] In summary, the reactor can be set at a reasonable position in the frequency converter cabinet. The reactor can save a lot of time and financial costs by simulating the size of the reactance under different output load conditions. It is also easy to use and does not require tedious calculation and design of a theoretical value and then manufacture of the corresponding reactor to verify whether the value of the reactor is reasonable. In case the theoretical value is inconsistent with the actual value, the corresponding reactor will have to be remade, resulting in a great waste.

[0090] Example 5

[0091] This embodiment provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the control method of the above embodiment is implemented.

[0092] Example 6

[0093] This embodiment provides an electronic device, including:

[0094] one or more processors;

[0095] The storage device is used to store one or more programs, and when the one or more programs are executed by the one or more processors, the one or more processors implement the control method of the above embodiment.

[0096] Figure 5 FIG. 1 is a schematic diagram of the hardware structure of an electronic device according to an embodiment of the present invention. Figure 5 As shown, the electronic device includes:

[0097] One or more processors 510 and memory 520, Figure 5 A processor 510 is taken as an example.

[0098] The electronic device may further include: an input device 530 and an output device 540 .

[0099] The processor 510, the memory 520, the input device 530 and the output device 540 may be connected via a bus or other means. Figure 5 The example of connecting through bus is taken in the following.

[0100] The memory 520 is a non-volatile computer-readable storage medium that can be used to store non-volatile software programs, non-volatile computer executable programs and modules, such as program instructions / modules corresponding to the control method in the embodiment of the present invention. The processor 510 executes various functional applications and data processing of the server by running the non-volatile software programs, instructions and modules stored in the memory 520, that is, implementing the above method embodiment.

[0101] The memory 520 may include a program storage area and a data storage area, wherein the program storage area may store an application required for operating the device and at least one function; the data storage area may store data created according to the use of the control method, etc. In addition, the memory 520 may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage devices.

[0102] The input device 530 can receive input digital or character information and generate key signal input related to user settings and function control of the electronic device. The output device 540 can include a display device such as a display screen.

[0103] The one or more modules are stored in the memory 520, and when executed by the one or more processors 510, perform the control method in any of the above method embodiments.

[0104] The electronic device can execute the method provided by the embodiment of the present invention, and has the functional modules and beneficial effects corresponding to the execution method. For technical details not described in detail in this embodiment, please refer to the method provided by the embodiment of the present invention.

[0105] The electronic devices of the embodiments of the present invention exist in various forms, including but not limited to:

[0106] (1) Mobile communication devices: These devices are characterized by their mobile communication functions and their main purpose is to provide voice and data communications. These terminals include: smart phones (such as iPhone), multimedia phones, functional phones, and low-end phones.

[0107] (2) Ultra-mobile personal computer devices: These devices fall into the category of personal computers, have computing and processing capabilities, and generally also have mobile Internet access features. These terminals include: PDA, MID and UMPC devices, such as iPad.

[0108] (3) Portable entertainment devices: These devices can display and play multimedia content. They include audio and video players (such as iPods), handheld game consoles, e-books, as well as smart toys and portable car navigation devices.

[0109] (4) Server: A device that provides computing services. The server consists of a processor, hard disk, memory, device bus, etc. The server is similar to a general computer architecture, but because it needs to provide highly reliable services, it has higher requirements in terms of processing power, stability, reliability, security, scalability, and manageability.

[0110] (5) Other electronic devices with data interaction functions, such as televisions, large-screen cars, etc.

[0111] The adjustable reactor embodiment described above is merely illustrative, wherein the modules described as separate components may or may not be physically separated, and the components displayed as modules may or may not be physical modules, i.e., they may be located in one place or distributed to multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment.

[0112] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention 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. However, 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 invention.

Claims

1. An adjustable reactor, applied to a frequency converter, the frequency converter comprising a rectifier module and an inverter module, characterized in that: The adjustable reactor comprises: at least two adjustable inductors arranged in series; A low-pass filter, used to filter out the high-order harmonic components in the current sampling signal of the input current of the rectifier module, and then output the filtered current sampling signal; A processing chip, a first input terminal of which inputs a filtered current sampling signal, and a second input terminal of which inputs a pre-filtered current sampling signal, for calculating a current distortion rate according to the filtered current sampling signal and the pre-filtered current sampling signal, and then outputting a driving signal according to the current distortion rate; The driving module is used to adjust the number of the adjustable inductors and the inductance of the adjustable inductors according to the driving signal, thereby adjusting the reactance value of the adjustable reactor.

2. The adjustable reactor according to claim 1, characterized in that: The adjustable inductor comprises: A plurality of single-turn coils, each of which is connected in parallel with a switch, and the processing chip is used to control the number of switches turned on in the adjustable inductor according to the current distortion rate, thereby adjusting the inductance value of the adjustable inductor.

3. The adjustable reactor according to claim 1, characterized in that: The switch is a DC contactor, and the DC contactor comprises: A coil, a first contact and a second contact, wherein the first end of the coil is connected to a voltage source, the second end of the coil is grounded through a switch tube, the first contact is connected to the first end of the single-turn coil of the adjustable inductor, and the second contact is connected to the second end of the single-turn coil of the adjustable inductor.

4. A frequency converter, comprising a rectifier module and an inverter module, characterized in that: It also includes the adjustable reactor according to any one of claims 1 to 3.

5. A control method, applied to the adjustable reactor according to any one of claims 1 to 3, characterized in that: The control method comprises: Calculating a current distortion rate according to the current sampling signal after filtering and the current sampling signal before filtering; The number of the adjustable inductors and the inductance of the adjustable inductors are adjusted according to the current distortion rate, thereby adjusting the reactance value of the adjustable reactor.

6. The control method according to claim 5, characterized in that: Calculating the current distortion rate according to the filtered current sampling signal and the pre-filtered current sampling signal, comprising: Obtaining the signal value of the filtered current sampling signal; Subtracting the signal value of the current sampling signal before filtering from the signal value of the direct current and the current sampling signal after filtering to obtain a high-order harmonic component; The ratio of the high-order harmonic component to the fundamental signal component in the filtered current sampling signal is calculated to obtain the current distortion rate.

7. The control method according to claim 5, characterized in that: The number of the adjustable inductors and the inductance values ​​of the adjustable inductors are adjusted according to the current distortion rate, including: Determining the interval in which the current distortion rate is located; The number of the adjustable inductors and the inductance values ​​of the adjustable inductors are controlled according to the interval in which the current distortion rate is located.

8. The control method according to claim 7, characterized in that: The number of adjustable inductors to be input is controlled according to the interval in which the current distortion rate is located, including: If the current distortion rate is greater than the first threshold, it is determined whether the inductance value of each currently-input adjustable inductor has reached a maximum; if so, the number of the currently-input adjustable inductors is controlled to increase; if not, the inductance value of at least one currently-input adjustable inductor is controlled to increase; If the current distortion rate is less than or equal to the first threshold value and greater than the second threshold value, the number of the adjustable inductors input is controlled to remain unchanged; If the current distortion rate is less than the second threshold, it is determined whether the inductance of each adjustable inductor currently in use has reached the minimum; if so, the number of adjustable inductors currently in use is controlled to decrease; if not, the inductance of at least one adjustable inductor currently in use is controlled to decrease.

9. The control method according to claim 8, characterized in that: Controlling the inductance value of at least one adjustable inductor currently input to increase includes: Controlling the number of switches turned on in the adjustable inductor to decrease, thereby controlling the number of single-turn coils turned on in the adjustable inductor to increase, thereby controlling the inductance value of the adjustable inductor to increase; Wherein, the switch is arranged in parallel with the single-turn coil.

10. The control method according to claim 8, characterized in that: Controlling the inductance value of at least one adjustable inductor currently input to decrease comprises: Controlling the number of switches turned on in the adjustable inductor to increase, thereby controlling the number of single-turn coils turned on in the adjustable inductor to decrease, thereby controlling the inductance value of the adjustable inductor to decrease; Wherein, the switch is arranged in parallel with the single-turn coil.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 5 to 10 is implemented.

12. An electronic device, characterized in that: include: one or more processors; A storage device for storing one or more programs, which, when executed by the one or more processors, enables the one or more processors to implement the method according to any one of claims 5 to 10.

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