Adjustable reactor and frequency converter

Abstract

The utility model discloses an adjustable reactor and a frequency converter. 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 utility model, the workload of developers can be reduced, and the product development cycle can be shortened.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic power, in particular to an adjustable reactor and a frequency converter. Background Art

[0002] With the rapid development of variable frequency speed regulation technology, the use of frequency converters has become increasingly widespread. Standardizing the design, selection, and manufacture of appropriate radio interference suppression reactors, power supply-side AC reactors, DC reactors, and output-side AC reactors for variable frequency speed regulation control systems ensures stable, reliable, and low-failure operation. This not only improves production quality and efficiency, but also yields positive economic benefits. It is also extremely important for social benefits such as energy conservation, environmental protection, and improved grid power quality. Practice has proven that selecting appropriate reactors for use with frequency converters can not only suppress harmonics and improve the frequency converter's power factor, but also mitigate the impact of grid surge currents on the frequency converter, ensuring reliable operation.

[0003] At present, high-power inverters have high operating currents and generally use copper busbars for wiring. The reactors used in conjunction with them are large in size and high in cost. If the harmonic test fails, a new reactor must be replaced for testing. Before replacing the reactor, the inverter structure and copper busbar structure need to be changed. On the one hand, this causes a waste of reactor 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 existing technology, the parameters of the reactor in the inverter are fixed. If 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. Utility Model Content

[0005] The present invention provides an adjustable reactor and a frequency converter to solve the problem in the prior art that the parameters of the reactor in the frequency converter are fixed. Once the harmonic test fails, the frequency converter needs to be disassembled and the reactor 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. The frequency converter includes a rectifier module and an inverter module. The adjustable reactor includes:

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

[0008] A low-pass filter, configured to filter out 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, wherein a first input terminal of the processing chip inputs a filtered current sampling signal, and a second input terminal of the processing chip inputs a pre-filtered current sampling signal, and the processing chip is configured to calculate a current distortion rate based on the filtered current sampling signal and the pre-filtered current sampling signal, and then output a driving signal based on the current distortion rate;

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

[0011] Furthermore, the adjustable inductor includes:

[0012] Multiple 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 includes:

[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 switching 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 utility model also provides a frequency converter, comprising a rectifier module and an inverter module, and also comprising the above-mentioned adjustable reactor.

[0016] By applying the technical solution of the utility model, a current distortion rate is calculated based on a current sampling signal after filtering and a current sampling signal before filtering by a processing chip, and then a driving signal is output based on the current distortion rate, so as to adjust the number of adjustable inductors and the inductance value of the adjustable inductors invested in the reactor, thereby adjusting the reactance value of the adjustable reactor. This makes it possible to adjust the reactance value of the adjustable reactor based on the harmonic content. When the harmonic test fails, there is no need to disassemble the inverter and replace the reactor, thereby reducing the workload of developers and shortening the product development cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 1 is a structural diagram of an adjustable reactor according to an embodiment of the present utility model;

[0018] Figure 2 2 is a structural diagram of a frequency converter according to an embodiment of the present utility model. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0020] 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", "the" 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 otherwise, and "a plurality" generally includes at least two.

[0021] It should be understood that the term "and / or" as used herein is merely a description of the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0022] 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 merely used to distinguish different thresholds. For example, without departing from the scope of embodiments of the present invention, a first threshold may also be referred to as a second threshold, and similarly, a second threshold may also be referred to as a first threshold.

[0023] 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 the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0024] It should also be noted that the terms "include," "comprises," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a product or device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such product or device. In the absence of further limitations, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the product or device comprising the element.

[0025] Optional embodiments of the present utility model are described in detail below with reference to the accompanying drawings.

[0026] Example 1

[0027] At present, high-power inverters have high operating currents and generally use copper busbars for wiring. The reactors used in conjunction with them are large in size and high in cost. If the harmonic test fails, a new reactor must be replaced for testing. Before replacing the reactor, the inverter structure and copper busbar structure need to be changed. On the one hand, this causes a waste of reactor development costs and increases the workload of rectification. On the other hand, it prolongs the rectification cycle and affects the progress of product development.

[0028] 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 for use in the inverter, which includes a rectifier module and an inverter module. Figure 1 FIG. 1 is a structural diagram of an adjustable reactor according to an embodiment of the present utility model, as shown in FIG. Figure 1 As shown, the adjustable reactor includes: at least two adjustable inductors connected 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 is used to filter out high-order harmonic components from 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 providing a current sensor on each phase circuit of the input end of the rectifier module. A processing chip 2 receives the filtered current sampling signal at its first input end and the pre-filtered current sampling signal at its second input end. The processing chip 2 is used to calculate the current distortion ratio based on the filtered and pre-filtered current sampling signals and then output a drive signal based on the current distortion ratio. The current distortion ratio can reflect the harmonic content; a larger current distortion ratio indicates a higher 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.

[0029] The variable reactor of this embodiment calculates the current distortion rate based on the filtered current sampling signal and the pre-filtered current sampling signal through a processing chip, then outputs a drive signal based on the current distortion rate, adjusts the number of adjustable inductors and the inductance of the adjustable inductors in the reactor, and further adjusts the reactance value of the adjustable reactor. This 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.

[0030] The adjustable inductor includes: 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 composed of a single-turn coil in the second adjustable inductor L2. 21 ~l 2n , the corresponding switch is S 21 ~S 2n , S 21 ~S 2n The first switch group S2 is formed. The processing chip 2 controls the number of switches that are turned on in the adjustable inductor according to the current distortion rate, thereby adjusting the inductance 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 the number of turns of the coil connected to the circuit can be controlled. The more single-turn coils connected, the greater the inductance. Therefore, the inductance of the adjustable inductor can be controlled by controlling the on-off of the above-mentioned switch. Furthermore, the adjustable inductors are connected in series. The more adjustable inductors are connected in series, the greater the inductance. Therefore, by controlling the number of adjustable inductors connected, the inductance of the entire reactor can also be adjusted, that is, the reactance value of the adjustable reactor can be adjusted.

[0031] 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 the 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 the single-turn coil of the adjustable inductance, and the second contact b is connected to the second end of the single-turn coil of the adjustable inductance.

[0032] Example 2

[0033] This embodiment provides a frequency converter. Figure 2 FIG. 1 is a structural diagram of a frequency converter according to an embodiment of the present utility model, as shown in FIG. 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.

[0034] The above-described adjustable reactor embodiment is merely illustrative. The modules described as separate components may or may not be physically separate, and the components shown as modules may or may not be physical modules, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of this embodiment.

[0035] 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 various embodiments of the present invention.

Claims

1. An adjustable reactor is applied to a frequency converter, wherein the frequency converter includes 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, configured to filter out 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, wherein a first input terminal of the processing chip inputs a filtered current sampling signal, and a second input terminal of the processing chip inputs a pre-filtered current sampling signal, and the processing chip is configured to calculate a current distortion rate based on the filtered current sampling signal and the pre-filtered current sampling signal, and then output a driving signal based on the current distortion rate; The driving module is used to adjust the number of the adjustable inductors and the inductance values ​​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: Multiple 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 2, characterized in that: The switch is a DC contactor, and the DC contactor includes: 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 switching 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.

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