Variable-frequency soft start control device

Abstract

The invention relates to the technical field of industry, in particular to a variable-frequency soft start control device which comprises a main body, air inlet grooves communicating with the left side wall and the right side wall of the main body are formed in the main body, refrigeration pieces are fixedly connected to the inner walls of the air inlet grooves, and two vent grooves communicating with the air inlet grooves are formed in the main body. According to the soft start method, through comprehensive acquisition and dynamic regulation and control of multi-dimensional operation parameters of the motor and the power grid, impact damage in the motor start process is reduced from the source, and through real-time monitoring of load current and matching of flexible frequency raising logic, the problem of locked-rotor or winding overheating caused by sudden increase of current can be effectively avoided, and the service life of the motor is prolonged. Meanwhile, the matching relation between the voltage and the frequency is dynamically adjusted in combination with the motor temperature, part aging in a high-temperature state is prevented, a rapid protection mechanism for current and voltage abnormity is matched, the capacity of the motor for coping with complex working conditions is greatly improved, the reliability and operation stability of the starting process are remarkably enhanced, and the fault risk of the motor is reduced.

Description

Technical Field

[0001] This invention relates to the field of industrial technology, specifically a variable frequency soft start control device. Background Technology

[0002] In industrial production, civil equipment and other fields, motors are widely used as core power components, and the stability and economy of their starting process directly affect the operating efficiency and service life of the entire equipment system.

[0003] Currently, among the mainstream motor starting methods, direct starting is prone to generating large inrush currents, interfering with the power grid and damaging motor components. Although star-delta reduced voltage starting can reduce current, it suffers from sudden changes in voltage and speed, and is only suitable for light and medium load scenarios, failing to meet heavy load requirements. Furthermore, while traditional soft starters can achieve a certain degree of smooth starting, they often use fixed control parameters (such as fixed frequency ramp-up step size and a single V / F curve), making it difficult to adapt to changes in motor load, temperature fluctuations, and power grid anomalies. The cooling system is often in continuous operation mode, resulting in energy waste and affecting component lifespan. Therefore, we propose a variable frequency soft starter control device to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a variable frequency soft start control device to solve the problems mentioned in the background art.

[0005] The technical solution of the present invention is: a variable frequency soft start control device, comprising a main body, wherein an air inlet slot is provided inside the main body and communicates with the left and right side walls of the main body, a cooling fin is fixedly connected to the inner wall of the air inlet slot, two ventilation slots are provided inside the main body and communicate with the air inlet slot, a heat dissipation slot is provided inside the main body and communicates with the two ventilation slots, a fan is provided inside each of the two ventilation slots, a baffle is fixedly connected to the inner wall of the air inlet slot, a set of strip-shaped air vents are provided on the front side wall of the baffle, and two symmetrically arranged air intake guide plates are fixedly connected to the inner wall of the air inlet slot.

[0006] The variable frequency soft start control device further includes: multi-dimensional parameter acquisition, initial operating parameter configuration, dynamic frequency ramping control, voltage-frequency coordinated adjustment, and start-up state determination and switching.

[0007] The variable frequency soft start control device includes the following steps: Step 1: Multi-dimensional parameter acquisition. Through the integrated sensing unit of the variable frequency soft start control device, the real-time speed of the motor to be started, the motor winding temperature, the load operating current, and the input voltage and grid frequency on the grid side are collected simultaneously. Step 2, initial operating parameter configuration: The main controller of the device calculates and sets the initial output frequency of the frequency converter based on the collected grid input voltage, grid frequency and motor rated power. The initial output frequency is set to 15%-28% of the motor rated frequency. Step 3, Dynamic frequency ramping control: The main controller increases the output frequency of the frequency converter execution module by adjusting the step size (0.2-0.8Hz / time) according to the preset base frequency, while monitoring the change trend of the load operating current in real time; if the load operating current exceeds the preset first current threshold, the frequency ramping is paused and the current frequency is maintained until the current drops to below 90% of the first current threshold and the current fluctuation amplitude is less than 5% / s, then the frequency ramping is resumed. Step 4, voltage-frequency coordinated adjustment: During the frequency increase process, the main controller calls the preset dynamic V / F (voltage / frequency) curve according to the current output frequency and the motor winding temperature, and synchronously adjusts the output voltage of the frequency converter to make the voltage-frequency ratio decrease linearly as the winding temperature increases. Step 5, Start-up status determination and switching: When the output frequency of the variable frequency drive module reaches more than 98% of the rated frequency of the motor, and the motor speed is stable in the range of 96%-100% of the rated speed and the load operating current is stable in the range of 85%-110% of the rated current, the main controller determines that the soft start is completed and controls the variable frequency drive module to switch to the power frequency operation mode.

[0008] Preferably, the step size of the basic frequency adjustment described in step 3 can be adaptively corrected according to the load type. For heavy-load motors (load rate ≥ 70%), the step size is corrected to 0.2-0.4 Hz / time; for medium-load motors (load rate 30%-70%), the step size is corrected to 0.4-0.6 Hz / time; and for light-load motors (load rate < 30%), the step size is corrected to 0.6-0.8 Hz / time.

[0009] Preferably, it also includes a composite protection step: if the load operating current exceeds 130% of the first current threshold and lasts for more than 1.5s in step 3, or the grid input voltage exceeds 120% of the rated voltage, the main controller immediately controls the frequency converter to reduce the output frequency to 60% of the initial output frequency; if the current or voltage does not recover to the safe range within 15s, the shutdown protection is triggered and a fault signal is output through the alarm unit.

[0010] Preferably, the dynamic V / F curve described in step 4 includes at least 3 sub-curves, which correspond to different ranges of motor winding temperature (<40℃, 40℃-60℃, >60℃). The main controller automatically switches the corresponding sub-curve according to the real-time collected winding temperature.

[0011] Preferably, during the entire software startup process, the main controller will link the collected temperature of the inverter execution module housing with the heat dissipation module of the device. When the housing temperature is >55°C, the heat dissipation module will switch to high-speed heat dissipation mode. When the housing temperature is <35°C, it will switch to low-speed energy-saving mode. When the housing temperature is >70°C, frequency reduction protection will be triggered (the frequency will be reduced to 80% of the current frequency) until the housing temperature drops below 55°C.

[0012] This invention provides an improved variable frequency soft start control device, which has the following improvements and advantages compared with the prior art: Firstly, this invention's soft-start method reduces impact damage during motor startup by comprehensively collecting and dynamically controlling multi-dimensional operating parameters of the motor and power grid. By monitoring the load current in real time and matching flexible frequency ramping logic, it effectively avoids stalling or winding overheating caused by sudden current surges. Simultaneously, it dynamically adjusts the voltage and frequency matching relationship based on motor temperature to prevent component aging under high-temperature conditions. Furthermore, combined with a rapid protection mechanism for current and voltage anomalies, it significantly improves the motor's ability to cope with complex operating conditions, significantly enhances the reliability and operational stability of the startup process, and reduces the risk of motor failure.

[0013] Secondly, this invention constructs an efficient operating system through multi-system collaborative control. On the one hand, it intelligently adjusts the heat dissipation mode based on the temperature of the core components of the control device, avoiding energy waste caused by traditional continuous high-power heat dissipation and reducing overall energy consumption. On the other hand, it flexibly adjusts the starting rhythm according to the motor load, shortening the duration of ineffective operation and reducing the wear and tear on the core control components. At the same time, it promptly switches to the appropriate operating mode after starting, avoiding the additional burden caused by long-term high-frequency operation of components. This not only saves energy but also delays device aging and extends the overall service life, achieving a dual improvement in economy and durability. Attached Figure Description

[0014] The present invention will be further explained below with reference to the accompanying drawings and embodiments: Figure 1 This is a front view structural diagram of the present invention; Figure 2 This is a schematic diagram of the internal structure of the left side of the present invention; Figure 3 This is a partial structural illustration of the present invention; Figure 4 This is a cross-sectional structural schematic diagram of the present invention; Figure 5 This is a flowchart illustrating the present invention.

[0015] Explanation of reference numerals in the attached figures: 1. Main body; 2. Air inlet slot; 3. Cooling element; 4. Ventilation slot; 5. Heat dissipation slot; 6. Fan; 7. Baffle; 8. Strip-shaped vent; 9. Air inlet guide plate. Detailed Implementation

[0016] The present invention will now be described in detail, and the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] This invention provides an improved variable frequency soft start control device. The technical solution of this invention is as follows: like Figure 1 - Figure 5 As shown, a variable frequency soft start control device includes a main body 1. An air intake slot 2, connected to the left and right side walls of the main body 1, is provided inside the main body 1. A cooling fin 3 is fixedly connected to the inner wall of the air intake slot 2. Two ventilation slots 4, connected to the air intake slots 2, are provided inside the main body 1. A heat dissipation slot 5, connected to the two ventilation slots 4, is provided inside the main body 1. A fan 6 is installed inside each of the two ventilation slots 4. A baffle 7 is fixedly connected to the inner wall of the air intake slot 2. A set of strip-shaped ventilation openings 8 are provided on the front side wall of the baffle 7. Two symmetrically arranged air intake guide plates 9 are fixedly connected to the inner wall of the air intake slot 2.

[0018] The variable frequency soft start control device further includes: multi-dimensional parameter acquisition, initial operating parameter configuration, dynamic frequency ramping control, voltage-frequency coordinated adjustment, and start-up state determination and switching.

[0019] The variable frequency soft start control device includes the following steps: Step 1: Multi-dimensional parameter acquisition. Through the integrated sensing unit of the variable frequency soft start control device, the real-time speed of the motor to be started, the motor winding temperature, the load operating current, and the input voltage and grid frequency on the grid side are collected simultaneously. Step 2, initial operating parameter configuration: The main controller of the device calculates and sets the initial output frequency of the frequency converter based on the collected grid input voltage, grid frequency and motor rated power. The initial output frequency is set to 15%-28% of the motor rated frequency. Step 3, Dynamic frequency ramping control: The main controller increases the output frequency of the frequency converter execution module by adjusting the step size (0.2-0.8Hz / time) according to the preset base frequency, while monitoring the change trend of the load operating current in real time; if the load operating current exceeds the preset first current threshold, the frequency ramping is paused and the current frequency is maintained until the current drops to below 90% of the first current threshold and the current fluctuation amplitude is less than 5% / s, then the frequency ramping is resumed. Step 4, voltage-frequency coordinated adjustment: During the frequency increase process, the main controller calls the preset dynamic V / F (voltage / frequency) curve according to the current output frequency and the motor winding temperature, and synchronously adjusts the output voltage of the frequency converter to make the voltage-frequency ratio decrease linearly as the winding temperature increases. Step 5, Start-up status determination and switching: When the output frequency of the variable frequency drive module reaches more than 98% of the rated frequency of the motor, and the motor speed is stable in the range of 96%-100% of the rated speed and the load operating current is stable in the range of 85%-110% of the rated current, the main controller determines that the soft start is completed and controls the variable frequency drive module to switch to the power frequency operation mode.

[0020] Furthermore, the basic frequency adjustment step size described in step 3 can be adaptively adjusted according to the load type. For heavy-load motors (load rate ≥ 70%), the step size is adjusted to 0.2-0.4 Hz / time; for medium-load motors (load rate 30%-70%), the step size is adjusted to 0.4-0.6 Hz / time; and for light-load motors (load rate < 30%), the step size is adjusted to 0.6-0.8 Hz / time. By setting adjustment step sizes of 0.2-0.4 Hz / time, 0.4-0.6 Hz / time, and 0.6-0.8 Hz / time according to heavy-load, medium-load, and light-load levels, impact damage caused by sudden changes in motor current can be avoided under heavy loads, and the frequency response speed can be accelerated under light loads to match load changes, thus achieving a balance between precise speed regulation and operational stability under different load conditions.

[0021] Furthermore, it also includes a composite protection step. If the load operating current exceeds 130% of the first current threshold and lasts for more than 1.5 seconds in step 3, or the grid input voltage exceeds 120% of the rated voltage, the main controller immediately controls the frequency converter to reduce the output frequency to 60% of the initial output frequency. If the current or voltage does not recover to the safe range within 15 seconds, the shutdown protection is triggered and a fault signal is output through the alarm unit. Through the hierarchical protection logic of "first frequency reduction intervention (reducing to 60% of the initial frequency), then shutdown alarm", it can prioritize maintaining the low-load operation of the motor to reduce production interruption losses when the current / voltage exceeds the limit, and can also cut off the risk in time when the fault continues, avoiding the motor or frequency converter module from burning out due to long-term overcurrent / overvoltage. At the same time, the alarm unit can quickly locate the fault and improve the equipment operation and maintenance efficiency.

[0022] Furthermore, according to step 4, the dynamic V / F curve includes at least three sub-curves, corresponding to different temperature ranges of the motor windings (<40℃, 40℃-60℃, >60℃). The main controller automatically switches the corresponding sub-curve based on the real-time collected winding temperature. By switching the corresponding V / F sub-curve according to the motor winding temperature (<40℃, 40℃-60℃, >60℃), a higher voltage output can be matched to ensure the rated output of the motor when the winding is at a low temperature. At a high temperature, the V / F ratio can be appropriately adjusted to reduce copper loss and avoid overheating and aging of the windings. This allows the motor to maintain its operating performance and extend its service life across the entire temperature range.

[0023] Furthermore, throughout the software startup process, the main controller links the collected case temperature of the variable frequency drive module with the heat dissipation module of the device. When the case temperature is >55℃, the heat dissipation module is switched to high-speed heat dissipation mode. When the case temperature is <35℃, it switches to low-speed energy-saving mode. When the case temperature is >70℃, frequency reduction protection is triggered (the frequency is reduced to 80% of the current frequency) until the case temperature drops below 55℃. Through the linkage mechanism of "35℃ low-speed energy saving, 55℃ high-speed heat dissipation, and 70℃ frequency reduction protection", the energy consumption of the heat dissipation module can be reduced when the case temperature is low, and the heat dissipation can be strengthened in time to control the temperature when the case temperature rises. It can also reduce the power loss of the module by frequency reduction when the temperature is too high (>70℃), and prevent the variable frequency drive module from crashing due to overheating. The entire soft start process is guaranteed to be continuous and stable.

[0024] The foregoing description enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A variable frequency soft start control device, comprising a main body (1), characterized in that: The main body (1) has an air intake slot (2) connected to the left and right side walls of the main body (1). A cooling plate (3) is fixedly connected to the inner wall of the air intake slot (2). The main body (1) has two ventilation slots (4) connected to the air intake slot (2). The main body (1) has a heat dissipation slot (5) connected to the two ventilation slots (4). A fan (6) is installed inside each of the two ventilation slots (4). A baffle (7) is fixedly connected to the inner wall of the air intake slot (2). A set of strip-shaped ventilation ports (8) is opened on the front side wall of the baffle (7). Two symmetrically arranged air intake guide plates (9) are fixedly connected to the inner wall of the air intake slot (2). The variable frequency soft start control device further includes: multi-dimensional parameter acquisition, initial operating parameter configuration, dynamic frequency ramping control, voltage-frequency coordinated adjustment, and start-up state determination and switching. The variable frequency soft start control device includes the following steps: Step 1: Multi-dimensional parameter acquisition. Through the integrated sensing unit of the variable frequency soft start control device, the real-time speed of the motor to be started, the motor winding temperature, the load operating current, and the input voltage and grid frequency on the grid side are collected simultaneously. Step 2, initial operating parameter configuration: The main controller of the device calculates and sets the initial output frequency of the frequency converter based on the collected grid input voltage, grid frequency and motor rated power. The initial output frequency is set to 15%-28% of the motor rated frequency. Step 3, Dynamic frequency ramping control: The main controller increases the output frequency of the frequency converter execution module by adjusting the step size (0.2-0.8Hz / time) according to the preset base frequency, while monitoring the change trend of the load operating current in real time; if the load operating current exceeds the preset first current threshold, the frequency ramping is paused and the current frequency is maintained until the current drops to below 90% of the first current threshold and the current fluctuation amplitude is less than 5% / s, then the frequency ramping is resumed. Step 4, voltage-frequency coordinated adjustment: During the frequency increase process, the main controller calls the preset dynamic V / F (voltage / frequency) curve according to the current output frequency and the motor winding temperature, and synchronously adjusts the output voltage of the frequency converter to make the voltage-frequency ratio decrease linearly as the winding temperature increases. Step 5, Start-up status determination and switching: When the output frequency of the variable frequency drive module reaches more than 98% of the rated frequency of the motor, and the motor speed is stable in the range of 96%-100% of the rated speed and the load operating current is stable in the range of 85%-110% of the rated current, the main controller determines that the soft start is completed and controls the variable frequency drive module to switch to the power frequency operation mode.

2. The variable frequency soft start control device according to claim 1, characterized in that: The basic frequency adjustment step size described in step 3 can be adaptively corrected according to the load type. For heavy-load motors (load rate ≥ 70%), the step size is corrected to 0.2-0.4 Hz / time; for medium-load motors (load rate 30%-70%), the step size is corrected to 0.4-0.6 Hz / time; and for light-load motors (load rate < 30%), the step size is corrected to 0.6-0.8 Hz / time.

3. The variable frequency soft start control device according to claim 1, characterized in that: It also includes a composite protection step. If the load operating current exceeds 130% of the first current threshold and lasts for more than 1.5s in step 3, or the grid input voltage exceeds 120% of the rated voltage, the main controller immediately controls the frequency converter to reduce the output frequency to 60% of the initial output frequency. If the current or voltage does not recover to the safe range within 15s, the shutdown protection is triggered and a fault signal is output through the alarm unit.

4. The variable frequency soft start control device according to claim 1, characterized in that: The dynamic V / F curve described in step 4 contains at least three sub-curves, each corresponding to a different range of motor winding temperature (<40℃, 40℃-60℃, >60℃). The main controller automatically switches the corresponding sub-curve based on the real-time collected winding temperature.

5. The variable frequency soft start control device according to claim 1, characterized in that: During the entire software startup process, the main controller will link the collected temperature of the inverter execution module housing with the heat dissipation module of the device. When the housing temperature is >55℃, the heat dissipation module will switch to high-speed heat dissipation mode. When the housing temperature is <35℃, it will switch to low-speed energy-saving mode. When the housing temperature is >70℃, the frequency reduction protection will be triggered (the frequency will be reduced to 80% of the current frequency) until the housing temperature drops back to below 55℃.

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