Frequency converter carrier frequency down-conversion measuring device

Abstract

The utility model discloses an underclocking measuring device for carrier frequency of a frequency converter, which comprises a plurality of linear modules and a cylinder formed by encircling the modules in an annular array form. A variable frequency motor to be tested is placed at the central axis of the cylinder. Each linear module is connected to one end of the detection piece. And if the carrier frequency is lower or the setting is poor, the noise waveform of the motor is more disordered. By adjusting the switching frequency, the noise of the system is minimum, the smoothness of the waveform is best, and the interference is minimum. Whether the carrier frequency of the frequency converter is properly set or not can be determined by detecting the disorder degree of the noise wave pattern and carrying out backstepping; according to the technical scheme of the utility model, by introducing the linear module, the rotating module and the like which move in multiple dimensions and adopting the sound sensor, the omnibearing test of the variable frequency motor is realized. The omnibearing test method can more comprehensively understand the performance of the motor in different working states.

Description

Technical Field

[0001] The utility model relates to the technical field of variable frequency motors, in particular to a frequency converter carrier frequency reduction measuring device. Background Art

[0002] A variable-frequency motor is a complete motor system that combines a motor with a frequency converter (variable-frequency speed regulator). This integrated design allows for seamless coordination between the motor and the frequency converter, facilitating installation, commissioning, and maintenance. An integrated variable-frequency motor system typically includes a motor, a frequency converter, and associated control circuitry and interfaces. In this system, the frequency converter primarily adjusts the power supply frequency, thereby varying the motor's speed. The frequency converter can provide variable power supply frequency as needed, enabling the motor to operate at varying speeds to meet diverse operating requirements. This speed regulation approach offers significant flexibility, meeting the needs of many industrial applications.

[0003] Traditional AC motors typically adjust their speed by adjusting the power supply voltage or changing the number of poles. However, variable-frequency motors vary the input power frequency to control the motor's speed. This speed regulation method offers many advantages, including higher energy efficiency, greater precision, and improved reliability.

[0004] Frequency converters control motor speed through pulse width modulation (PWM). In PWM modulation, the inverter generates a series of pulse signals. By adjusting the pulse width and interval, the effective value of the output voltage is controlled, thereby adjusting the motor speed. The carrier frequency of this series of pulse signals is one of the key parameters affecting system performance.

[0005] The carrier frequency refers to the repetition rate of the pulses in the PWM signal, typically measured in Hertz (Hz). The switching frequency refers to the frequency at which the inverter's switching elements (such as transistors or IGBTs) switch, also known as the carrier frequency of the PWM signal. A higher switching frequency means more pulses per cycle. This has a significant impact on motor control, as it determines the average voltage seen by the motor. A higher switching frequency means smaller pulse widths and intervals, allowing for more precise control of the motor's output voltage. This improves motor control accuracy and efficiency. The choice of switching frequency directly affects the system's noise level and electromagnetic interference (EMI) with surrounding equipment. A higher switching frequency reduces system noise but also tends to cause more EMI. The choice of switching frequency is also related to system efficiency. Generally, increasing the switching frequency reduces motor power loss, but may also increase losses in the inverter itself.

[0006] The concept of carrier frequency can be summarized as follows: the carrier frequency depends on the intersection of the modulation wave and the carrier wave, that is, the switching frequency. The higher the switching frequency, the more pulses there are in one cycle, and the smoother the current waveform is, but the interference to other devices is also greater. The lower the carrier frequency or the poorly set one, the motor will make unpleasant noise. By adjusting the switching frequency, the system noise can be minimized, the waveform can be smoothed to the best, and the interference can be minimized. The source of this concept is:

[0007] Yu Yanjun. Research on sensorless control of permanent magnet synchronous motor based on carrier frequency component method[D]. Harbin Institute of Technology, 2009.

[0008] In existing technology, variable-frequency motor manufacturers lack effective means to determine whether the carrier frequency of each variable-frequency motor that rolls off the production line meets process specifications during production and production. If the carrier frequency deviates from design requirements, the motor may not operate as expected. This can lead to decreased efficiency, increased power loss, and even a negative impact on the motor's lifespan.

[0009] Therefore, a device for measuring the down-conversion frequency of a frequency converter carrier frequency is proposed. Utility Model Content

[0010] In view of this, the embodiments of the present invention hope to provide a frequency converter carrier frequency reduction measurement device to solve or alleviate the technical problem existing in the prior art, namely, the inability to ensure that the variable frequency motor produced thereby has good carrier frequency performance in actual use, rather than just at the theoretical design level, and to at least provide a useful alternative for this purpose;

[0011] The technical solution of the embodiment of the present utility model is implemented as follows: a frequency converter carrier frequency reduction measurement device, including a plurality of linear modules, which are arranged in a circular array around a cylinder. The variable frequency motor to be tested is placed at the central axis of the cylinder. Each linear module is connected to one end of the detection part. Each linear module performs a lifting movement, and during the lifting movement, the detection part performs a universal angle adjustment movement through each linear module. When the detection part performs universal angle adjustment, noise detection and its waveform are performed around the test motor. Because for the frequency converter of the variable frequency motor, the lower the carrier frequency or the poorly set it, the more chaotic the noise waveform of the motor. By adjusting the switching frequency, the system noise can be minimized, the waveform can be smoothed to the best, and the interference can be minimized. By reversely deducing the degree of disorder of the noise waveform, it is possible to determine whether the carrier frequency of the frequency converter is set appropriately.

[0012] In one embodiment, the device further comprises a frame, wherein each linear module is mounted around the frame in a circular array, and an electric clamping claw for clamping the test piece is provided in the middle of the frame.

[0013] In one embodiment, the linear module is composed of a hinge rod that performs lifting and lowering motions and a rotary module. One end and the other end of the hinge rod are connected to the rotary module and a connecting frame respectively through universal joint couplings, and the connecting frame is equipped with a detection component.

[0014] In one embodiment, the rotary module includes a rotary actuator and an eccentric shaft driven to rotate by the rotary actuator. The eccentric section of the eccentric shaft is hinged to a universal joint coupling on the hinge rod.

[0015] In one embodiment, the rotary actuator adopts a servo motor, which is fixed on the frame, and the output shaft of the servo motor is fixedly connected to the eccentric shaft.

[0016] In one embodiment, the detection component is a sound sensor.

[0017] In one embodiment, each pair of adjacent linear modules is arranged in a V-shape or inverted V-shape. This arrangement allows each linear module to overlap when performing lifting motion. This increases the maximum travel position and travel volume of each linear degree of freedom, increases the trajectory flexibility of the detection component during universal adjustment, and enables the capture of sound from more locations.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] (1) Comprehensive testing: By introducing multi-dimensional linear modules, rotary modules, and acoustic sensors, the present invention achieves comprehensive testing of variable frequency motors. This comprehensive testing method provides a more comprehensive understanding of the motor's performance under different operating conditions. This design can capture the motor's acoustic signals at various angles, improving the flexibility and applicability of the test.

[0020] (2) Real-time monitoring and adjustment: The present invention uses a sound sensor as a detection element, and the technical solution of the present invention realizes real-time monitoring of noise changes around the motor. This provides timely feedback for adjusting the motor performance in actual use. If the carrier frequency is lower or poorly set, the noise waveform of the motor will be more chaotic. By adjusting the switching frequency, the system noise can be minimized, the waveform can be smoothest, and the interference can be minimized. By reversely detecting the degree of disorder of the noise waveform, it is possible to determine whether the carrier frequency of the inverter is set appropriately. Assist production personnel to measure the quality of the variable frequency motor currently offline. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or technical descriptions. 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 any creative work.

[0022] Figure 1 This is a three-dimensional schematic diagram from one perspective of the present invention;

[0023] Figure 2 This is a three-dimensional schematic diagram from another perspective of the present invention;

[0024] Figure 3 This is a three-dimensional schematic diagram of the linear module of the present utility model;

[0025] Figure numerals: 1, frame; 2, linear module; 201, rotary actuator; 202, eccentric shaft; 203, hinge rod; 204, universal joint coupling; 3, connecting frame; 4, detection part; 5, electric claw. DETAILED DESCRIPTION

[0026] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is provided in conjunction with the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] Example

[0028] In the existing technology, there is no effective way for VFD motor manufacturers to determine whether the carrier frequency of each VFD motor that comes off the production line actually meets the process specifications. If the carrier frequency deviates from the design requirements, the motor may not operate as expected. This may lead to reduced efficiency, increased power loss, and even a negative impact on the life of the motor. For this reason, please refer to Figure 1-3 , this specific embodiment will provide relevant technical solutions to solve the above technical problems: a frequency converter carrier frequency reduction measurement device, including a plurality of linear modules 2 in the form of a circular array around a cylinder formed, the test piece, that is, the variable frequency motor is placed at the central axis of the cylinder; each linear module 2 is connected to one end of the detection piece 4; each linear module 2 takes turns to perform the lifting movement, and when the lifting movement is performed, the detection piece 4 is replaced by each linear module 2 to perform the universal angle adjustment movement; when the detection piece 4 performs the universal angle adjustment, the noise and its waveform are detected around the test piece. Because for the frequency converter of the variable frequency motor, if the carrier frequency is lower or the setting is not good, the noise waveform of the motor is more chaotic. By adjusting the switching frequency, the system noise can be minimized, the waveform is smoothest, and the interference is also minimized. By reversely detecting the degree of disorder of the noise waveform, it is possible to determine whether the carrier frequency of the frequency converter is set appropriately. During execution, the staff will place the test piece in rack 1 for testing; if they judge that the waveform smoothness is not good and meets the characteristics of defective products (a production process standard needs to be formulated by the manufacturer), it will be judged as a defective product and shall not be taken off the line.

[0029] In this solution, the circular array and lifting motion of the linear module 2 allow for omnidirectional movement of the detection element 4. This allows for precise noise detection of the variable-frequency motor in various directions through the movement of the linear module 2 and the adjustment of the detection element 4. Noise detection can be performed using sensors or microphones to capture the characteristics of the noise signal. The universal angular adjustment of the detection element 4 allows for simultaneous acquisition of motor waveform information at various angles while simultaneously detecting noise.

[0030] Specifically, this device's primary function is to determine whether the inverter's carrier frequency is properly set. By monitoring the noise and waveform surrounding the inverter motor, particularly at different angles, the degree of noise waveform disorder can be inferred, thereby determining the suitability of the carrier frequency. A more turbulent noise waveform may indicate a low or inappropriate carrier frequency setting. This device allows manufacturers to monitor and adjust the inverter's carrier frequency in real time to ensure minimal noise, optimal waveform smoothness, and minimal interference in actual operation.

[0031] In this solution, the above-mentioned components are the main functional mechanisms of the device provided in this specific embodiment; based on the above-mentioned mechanisms, they are placed on the frame 1; specifically, the frame 1 serves as the reference support structure of the entire device, provides a basis for the above-mentioned device to adapt to the external environment, and can adapt to external personnel to perform routine mechanical maintenance operations such as maintenance, adjustment and assembly of related parts;

[0032] Specifically, by supporting the above-mentioned mechanism with the frame 1, the entire device can be placed and applied to the variable frequency motor automated production line, so that the entire device can be used as an additional process in the existing automated production line to provide carrier frequency performance testing for the production and preparation of the variable frequency motor; specifically, the device is applied to the rear part of the offline process section in the variable frequency motor automated production line;

[0033] It should be noted that the height, width and other parameters of the rack 1 need to be adapted and selected according to the relevant mechanical devices of the front and back processes of the variable frequency motor automation production line, and are non-limiting.

[0034] It should be pointed out that when this device is applied to the variable frequency motor automated production line based on the frame 1, its external part can be equipped with a production line body, or the input and output functions of the frame 1 in the process provided by this device can be transported by an external robotic arm in the form of clamping and storage; when the staff detects an abnormality in the carrier frequency of the current variable frequency motor or judges it to be a defective product, the variable frequency motor should be removed from the production line body and placed in the processing area, waiting for subsequent repair.

[0035] In this solution, all electrical components of the device as a whole rely on AC power for energy supply; specifically, the electrical components of the device as a whole are conventionally electrically connected to the AC power output port through devices such as relays, transformers and button panels to meet the energy supply requirements of all electrical components of the device.

[0036] Specifically, a controller is also provided on the outside of the device, which is used to connect and control all electrical components of the device as a whole to be driven according to a pre-set program as a preset value and drive mode; it should be pointed out that the above-mentioned drive mode corresponds to the corresponding start-stop time interval, speed, power and other output parameters between the relevant electrical components below, that is, it meets the requirements of the relevant electrical components described below to drive the relevant mechanical devices to operate according to the functions described therein.

[0037] In some specific embodiments of this application, please refer to Figures 2-3 : It also includes a frame 1, and each linear module 2 is installed around the frame 1 in the form of a ring array; an electric clamping claw 5 for clamping the test piece is provided in the middle of the frame 1.

[0038] In this solution, the frame 1 provides support and securement for the linear modules 2. These modules are arranged in a circular array around the frame 1, ensuring comprehensive testing coverage. The motorized grippers 5 in the center of the frame 1 stabilize and secure the test piece, preventing it from moving or shaking during testing, thereby ensuring accuracy and reliability.

[0039] Specifically, the addition of the frame 1 enhances the stability and reliability of the entire device. The circular array arrangement allows the linear modules 2 to move smoothly in various directions, while the motorized grippers 5 within the frame 1 securely clamp the test piece, preventing errors during testing. This ensures accurate noise and waveform detection, thereby improving the accuracy of the inverter carrier frequency. Therefore, this implementation not only considers the comprehensiveness of testing but also emphasizes secure gripping of the test piece during testing, ensuring the credibility of the test results.

[0040] In some specific embodiments of this application, please refer to Figures 2-3 : The linear module 2 includes a hinge rod 203 for performing lifting movements, and a rotary module; one end and the other end of the hinge rod 203 are respectively universally hinged to the rotary module and the connecting frame 3 through a universal joint coupling 204, and a detection member 4 is installed on the connecting frame 3.

[0041] In this solution, hinge rod 203 achieves lifting motion through its articulated design, while the rotary module is connected to the hinge rod via a universal joint 204, enabling the rotary module to rotate in conjunction with the hinge rod. A connecting frame 3 serves as a supporting structure, mounted on the rotary module, while the test component 4 is directly mounted on the connecting frame 3. This design enables the linear module 2 to perform both lifting and rotating motion, thus enabling comprehensive testing.

[0042] Specifically: This embodiment realizes the multi-dimensional movement of the linear module 2 by introducing the hinge rod 203 and the rotating module. The lifting movement is completed by the hinge rod 203, while the rotational movement is achieved through the coordinated action of the rotating module. This design ensures that the detection part 4 can perform comprehensive inspections on the test piece in different directions. Through the linkage of the hinge rod and the rotating module, the test piece can be adjusted at multiple angles while lifting and lowering, thereby more accurately capturing the noise and waveform information. This multi-dimensional movement design makes the device more flexible and suitable for the needs of all-round testing of the inverter carrier frequency.

[0043] In some specific embodiments of this application, please refer to Figures 2-3 The rotating module includes a rotating actuator 201 and an eccentric shaft 202 driven to rotate by the rotating actuator 201. The eccentric section of the eccentric shaft 202 is hinged to the universal joint coupling 204 on the hinge rod 203.

[0044] In this solution, a rotary actuator 201 acts as a driving device, achieving rotational motion by rotating an eccentric shaft 202. The eccentric section of the eccentric shaft 202 is articulated with a universal joint 204 on a hinge 203, transmitting the rotational motion to the hinge 203. This design enables the linkage between the lifting and rotating motions of the rotary module, providing the dynamic foundation for omnidirectional motion.

[0045] Specifically, the design of the rotary module enables linear module 2 to move in a rotational direction. The rotary actuator 201 drives the rotation of the eccentric shaft 202, transmitting the rotational motion to the universal joint coupling 204, which is hinged to the hinge rod 203. This combination of rotational motion and lifting motion enables the detection component 4 to perform comprehensive inspection of the test piece in multiple directions. By adjusting the parameters of the rotary actuator 201, rotational motion at different angles can be achieved, providing more testing options. This design provides a more flexible solution for the requirement of accurately measuring the inverter carrier frequency.

[0046] In some specific embodiments of this application, please refer to Figures 2-3 : The rotary actuator 201 is a servo motor, which is fixed on the frame 1, and the output shaft of the servo motor is fixedly connected to the eccentric shaft 202.

[0047] In this solution, a servo motor acts as a rotary actuator 201. Precise adjustments to its control system enable precise rotation of the output shaft. The output shaft is connected to an eccentric shaft 202, allowing the servo motor's rotational motion to be transmitted to the eccentric shaft, thereby achieving movement of the rotating module. The servo motor's high precision and programmability enable precise control of rotational motion at various angles and speeds.

[0048] Specifically, the advantages of using a servo motor as the rotary actuator 201 lie in its high precision and programmability. The servo motor is fixed to the frame 1, and accurate control of the eccentric shaft can be achieved by controlling the servo motor's rotation. This design enables the rotary module to perform flexible rotational motion at different angles and speeds, providing higher control accuracy for comprehensive testing. Due to the fixed servo motor and the connection to the output shaft, this embodiment ensures more accurate and controllable rotational motion during inverter carrier frequency measurement.

[0049] In some specific embodiments of this application, please refer to Figures 2-3 : Detection component 4 is a sound sensor.

[0050] In this solution, an acoustic sensor serves as detection element 4, capturing noise signals around the test piece. When the variable-frequency motor is running, the noise generated is captured by the sensor and converted into an electrical signal. The acoustic sensor's design makes it highly sensitive to changes in frequency and amplitude, accurately capturing the noise characteristics of the variable-frequency motor under different operating conditions.

[0051] Specifically, the use of an acoustic sensor as detection element 4 enables the device to monitor noise changes around the variable-frequency motor in real time. The acoustic sensor captures noise signals with high precision and sensitivity, converting them into electrical signals to provide data support for subsequent analysis. By analyzing the noise signal, the degree of disturbance in the noise waveform can be inferred, thereby assessing the appropriateness of the inverter carrier frequency setting. This implementation has significant application value for real-time monitoring and adjustment of inverter performance.

[0052] Furthermore, the hardware connection steps for generating the waveform graph of the sound sensor feedback include: inputting the analog signal fed back by the sound sensor into an analog-to-digital converter, transmitting the converted digital signal to a microcontroller or processor. The output of the microcontroller or processor is connected to a visualization device via serial communication, I2C, SPI, or other protocols. This can be an LCD screen, a display on a computer, a microcontroller, or other visualization device.

[0053] Preferably, the sound sensor model is the BR-ZS1 noise monitor, which is an integrated design integrating collection, analysis and output.

[0054] Preferably, the model of the sound sensor is TZ-2KA noise sensor, which has an AC voltage signal output and comes with a built-in acquisition instrument, and can visualize the output waveform.

[0055] In some specific embodiments of this application, please refer to Figures 2-3 Each pair of adjacent linear modules 2 is arranged in a V-shape or inverted V-shape. This arrangement allows each linear module 2 to overlap when performing its own lifting motion. This allows the linear modules 2 to extend their travel limits and increase the detection element 4's trajectories during universal adjustment, allowing it to capture sound from more locations.

[0056] In this solution, the V-shaped or inverted V-shaped arrangement of adjacent linear modules 2 allows them to overlap during lifting motion. This means that when a linear degree of freedom is generated, there is a certain amount of overlap between the various linear degrees of freedom. This design helps expand the limit travel position and travel range of the linear degrees of freedom. The overlapping of adjacent linear modules 2 increases the trajectory flexibility of the detection element 4 during universal adjustment, allowing it to capture sound signals over a wider area.

[0057] Specifically, the V-shaped or inverted V-shaped arrangement enhances the device's flexibility and omnidirectionality. The overlapping of adjacent linear modules 2 expands the range of linear freedom, increasing the test range. During universal adjustment, the detection element 4's trajectory is more flexible, covering more locations and thus more comprehensively capturing the sound signals around the variable-frequency motor. This arrangement offers the advantage of adapting the device to variable-frequency motors of various sizes and shapes, improving both the applicability and accuracy of testing.

[0058] In summary, in response to the relevant problems in traditional technologies, this specific embodiment is based on a frequency converter carrier frequency reduction measurement device provided above, and adopts the following technical means or features to achieve a solution: by introducing multi-dimensional motion linear modules 2, rotary modules, servo motors and other components, and using sound sensors as detection components 4, a full-dimensional, multi-angle testing device is constructed. This design takes into account a variety of factors in the implementation, such as lifting motion, rotary motion, sound detection, etc., to comprehensively and flexibly test the performance of the variable frequency motor. Through innovative mechanical structure design and sensor selection, some limitations of traditional technology in testing the carrier frequency performance of the variable frequency motor are overcome. Through a full-dimensional, multi-dimensional testing method, the performance of the variable frequency motor carrier frequency in actual operation can be more comprehensively understood.

[0059] The above-described embodiments merely represent implementation methods for the relevant practical applications of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that a person of ordinary skill in the art would be able to make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present utility model patent shall be determined by the appended claims.

Claims

1. A device for measuring frequency reduction of a frequency converter carrier frequency, characterized in that: A cylinder is formed by surrounding a plurality of linear modules (2) in the form of a ring array, and the test piece is placed at the central axis of the cylinder; Each of the linear modules (2) is connected to one end of the detection member (4); each of the linear modules (2) performs lifting motion in turn, and when the lifting motion is performed, the detection member (4) is replaced by each of the linear modules (2) to perform universal angle adjustment motion; When the detection piece (4) performs the universal angle adjustment, the noise and its waveform are detected around the test piece.

2. The device for measuring the frequency converter carrier frequency reduction according to claim 1, wherein: It also includes a frame (1), each of the linear modules (2) is installed around the frame (1) in the form of a ring array; the middle of the frame (1) is provided with an electric clamping claw (5) for clamping the test piece.

3. The device for measuring the frequency converter carrier frequency reduction according to claim 1, wherein: The linear module (2) includes a hinge rod (203) for performing the lifting motion, and a rotary module; One end and the other end of the hinge rod (203) are universally hinged to the rotating module and the connecting frame (3) through a universal joint coupling (204), and the detecting member (4) is mounted on the connecting frame (3).

4. The device for measuring the frequency converter carrier frequency reduction according to claim 3, wherein: The rotary module comprises a rotary actuator (201) and an eccentric shaft (202) driven to rotate by the rotary actuator (201); an eccentric section of the eccentric shaft (202) is hinged to the universal joint coupling (204) on the hinge rod (203).

5. The device for measuring the frequency converter carrier frequency reduction according to claim 4, wherein: The rotary actuator (201) is a servo motor, and the output shaft of the servo motor is fixedly connected to the eccentric shaft (202).

6. The device for measuring the frequency converter carrier frequency reduction according to any one of claims 1 to 5, characterized in that: The detection component (4) is a sound sensor.

7. The device for measuring the frequency converter carrier frequency reduction according to any one of claims 1 to 5, characterized in that: Every two adjacent linear modules (2) are arranged in a V-shape or an inverted V-shape.

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