A kind of explosion-proof high-voltage variable frequency speed regulation motor control system

Abstract

The application discloses a kind of explosion-proof high-voltage variable frequency speed regulation motor control systems, it is related to motor drive control technical field, the system includes: high-voltage power input module, power conversion module, motor drive module, explosion-proof housing, insulation protection module, temperature monitoring module and central control module, high-voltage power input module receives and pre-processes high-voltage electric energy;Power conversion module rectifies and inverts processing to electric energy, and the output adjustable frequency and voltage AC power;Explosion-proof housing is sealed to internal module explosion-proof, meets the requirement of explosion-proof grade;Insulation protection module carries out electrical insulation protection to high-voltage component;Temperature monitoring module monitors key component temperature and is fed back to central control module;Central control module generates control signal accordingly, and has speed closed loop and fault diagnosis function.The application can realize 6kV or 10kV high-voltage motor variable frequency speed regulation, and ensure safe and reliable operation in explosive gas environment, improve system comprehensive performance.

Description

Technical Field

[0001] This invention relates to the field of motor drive control technology, and in particular to an explosion-proof high-voltage variable frequency speed control motor control system. Background Technology

[0002] Explosion-proof high-voltage variable frequency speed control motor control systems are core drive equipment in hazardous locations such as mines and petrochemical plants, and their operational reliability directly affects the safety and efficiency of industrial production. These control systems typically need to adapt to 6kV or 10kV high-voltage power grid environments, while simultaneously meeting the precise control requirements of variable frequency speed regulation and achieving safe and stable operation in harsh environments containing explosive gases. Traditional control systems, when facing high-voltage operating environments, often struggle to simultaneously address electrical insulation protection, electromagnetic compatibility design, and explosion-proof structural requirements, thus limiting the overall performance of the system.

[0003] In existing technologies, conventional variable frequency speed control schemes are mainly designed for low or medium voltage levels. Their power device selection, electrical clearance planning, and insulation treatment are difficult to adapt to 6kV or 10kV high-voltage environments, resulting in high-voltage motors operating at power frequency for extended periods, leading to high energy consumption and significant starting shocks. Simultaneously, traditional frequency converters lack explosion-proof structures suitable for hazardous locations. Their housing strength, joint clearances, and cable entry sealing designs are insufficient to effectively withstand internal explosion pressure and prevent flame spread, exhibiting significant defects in explosion-proof performance. Under high-voltage operating conditions, the insulation protection measures in existing schemes are often insufficiently systematic, particularly for high-voltage busbars, Insufficient electrical isolation and creepage distance in critical components such as through-wall conductors can easily lead to safety hazards such as insulation breakdown or partial discharge. In addition, existing systems generally lack real-time temperature monitoring and overheat protection mechanisms for key heat-generating components such as power modules and bus capacitors, resulting in a high risk of power devices being damaged due to overheating. Furthermore, the control layer mostly adopts an open-loop V / F strategy, which results in large speed fluctuations when the load changes, limited dynamic response capability, and a lack of systematic diagnosis and protection functions for fault states such as overcurrent, overvoltage, undervoltage, and overtemperature. It is difficult to execute protection actions and report fault information in a timely manner after an anomaly occurs, and the overall reliability and ease of maintenance need to be improved.

[0004] Therefore, this invention proposes an explosion-proof high-voltage variable frequency speed control motor control system. Summary of the Invention

[0005] The purpose of this invention is to provide an explosion-proof high-voltage variable frequency speed control motor control system to solve the problem that existing technologies cannot simultaneously meet the requirements of high-voltage operation, variable frequency speed control, and explosion-proof safety.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] An explosion-proof high-voltage variable frequency speed control motor control system includes:

[0008] The high-voltage power input module, power conversion module, motor drive module, explosion-proof enclosure, insulation protection module, temperature monitoring module, and central control module are included, with the high voltage being 6kV or 10kV.

[0009] The high-voltage power input module is configured to receive high-voltage power from the power grid, preprocess the high-voltage power, and then transfer the preprocessed power to the power conversion module.

[0010] The power conversion module is configured to rectify and invert electrical energy from the high-voltage power input module to generate AC power with adjustable frequency and voltage. The power conversion module contains a power module and a drive circuit.

[0011] The motor drive module is configured to receive adjustable electrical energy output from the power conversion module and transmit the adjustable electrical energy to the load motor to achieve variable frequency speed regulation operation of the motor.

[0012] The explosion-proof housing adopts an explosion-proof structural design and is configured to seal the power conversion module, motor drive module and insulation protection module in its internal space. The housing material and structure of the explosion-proof housing meet the explosion-proof level requirements and can withstand possible internal explosion pressure and prevent the explosion flame from spreading outward.

[0013] The insulation protection module is configured to provide electrical insulation protection for the high-voltage power input module and the power conversion module.

[0014] The temperature monitoring module is configured to monitor the operating temperature of the power conversion module, motor drive module and insulation protection module inside the explosion-proof enclosure in real time, and feed the temperature information back to the central control module.

[0015] The central control module is configured to receive external control commands and temperature information fed back by the temperature monitoring module, generate control signals according to a preset control strategy, and send the control signals to the power conversion module to achieve precise adjustment of operating parameters such as motor speed and torque.

[0016] Preferably, the power conversion module includes a rectifier unit, an inverter unit, and a DC bus unit, wherein:

[0017] The rectifier unit is configured to convert high-voltage alternating current into direct current.

[0018] The DC bus unit is configured to filter and regulate the DC power output from the rectifier unit, providing a stable DC power supply for the inverter unit.

[0019] The inverter unit is configured to convert the DC power output from the DC bus unit into AC power with adjustable frequency and voltage.

[0020] Preferably, the motor drive module includes an output filtering module and an output protection unit; the output filtering module includes an output reactor, a filter capacitor, and an output terminal block disposed at its output end, the output terminal block being used to connect to the load motor via a high-voltage cable; the output protection unit includes an output current detection unit and an output overload protection unit; an insulating sleeve is provided where the output terminal block passes through the explosion-proof housing wall.

[0021] Preferably, the explosion-proof housing includes a main enclosure, a wiring cavity, and a heat dissipation structure, wherein:

[0022] The main enclosure is configured to house the power conversion module and the motor drive module. The outer shell of the main enclosure is made of high-strength explosion-proof material. The main enclosure adopts a welded explosion-proof structure, and the wall thickness of the enclosure can withstand an internal explosion pressure of not less than 1MPa. The outer shell of the main enclosure is made of low-carbon alloy structural steel or stainless steel. The connecting flanges of the main enclosure adopt a stop fit structure, and the flanges are sealed by explosion-proof sealing rings.

[0023] The wiring cavity is located on one side of the main enclosure and is configured to introduce external power lines and control signal lines. The wiring cavity is connected to the main enclosure via an explosion-proof cable introduction module.

[0024] The heat dissipation structure is located outside the main housing and is configured to effectively dissipate the heat generated by the power conversion module to the external environment. The heat dissipation structure includes a heat sink, which is connected to the power module of the power conversion module by a thermally conductive insulating pad.

[0025] Preferably, the insulation protection module includes a high-voltage insulation board, an insulating bushing, and a grounding protection module, wherein:

[0026] The high-voltage insulation plate is disposed between the high-voltage power input module and the explosion-proof housing, and is configured to provide electrical isolation and insulation support.

[0027] The insulating sleeve is disposed around the conductive component that penetrates the explosion-proof housing, and is configured to ensure the electrical sealing performance at the penetration point;

[0028] The grounding protection module is configured to reliably connect the explosion-proof enclosure to the ground, preventing the accumulation of dangerous potential in the enclosure.

[0029] Preferably, the temperature monitoring module includes a temperature sensor array, a signal acquisition circuit, and a temperature comparator, wherein:

[0030] The temperature sensor array is located in key positions inside the power module of the power conversion module, the drive element of the motor drive module, and the explosion-proof housing, and is configured to collect temperature data at each temperature measurement point in real time.

[0031] The signal acquisition circuit is configured to amplify and convert the analog signal output by the temperature sensor array into an analog-to-digital signal.

[0032] The temperature comparator is configured to compare the collected temperature data with a preset temperature threshold, and send an alarm signal to the central control module when the temperature exceeds the preset threshold.

[0033] Preferably, the central control module includes a microprocessor unit, a storage unit, a communication interface, and a fault diagnosis unit, wherein:

[0034] The microprocessor unit is configured to execute control algorithms and logic operations to generate control signals for the power conversion module.

[0035] The storage unit is configured to store control programs, preset parameters, and operating data;

[0036] The communication interface is configured to interact with an external monitoring system, receive external control commands, and report the system's operating status.

[0037] The fault diagnosis unit is configured to monitor the system's operating status in real time, detect fault conditions such as overcurrent, overvoltage, undervoltage, and overtemperature, and execute corresponding protection actions when a fault occurs.

[0038] Preferably, the rectifier unit adopts a multi-pulse rectifier topology and is equipped with a power diode module and a voltage equalization protection circuit; the input side of the rectifier unit is equipped with an LC filter circuit; the rectifier unit is also equipped with a short-circuit protection function.

[0039] Preferably, the DC bus unit is configured with a DC bus capacitor array and a DC voltage detection circuit; the DC bus capacitor array is composed of multiple high-voltage energy storage capacitors connected in parallel; the DC bus unit also includes a DC bus discharge circuit.

[0040] Preferably, the inverter unit adopts a three-level NPC topology or a T-type topology and is equipped with an IGBT power module and a gate drive circuit; the output side of the inverter unit is equipped with a voltage sensor and a current sensor; the inverter unit is also equipped with a temperature sensor.

[0041] Preferably, the central control module is also equipped with a speed closed-loop control function. Based on the deviation between the speed signal fed back by the motor and the given speed value, the output frequency of the power conversion module is dynamically adjusted to achieve accurate tracking of the motor speed. The speed closed-loop control function adopts a PID control algorithm or an adaptive control algorithm. Based on the speed deviation, the required voltage-frequency ratio is calculated, and a corresponding PWM modulation signal is generated to control the output of the inverter unit.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The explosion-proof high-voltage variable frequency speed control motor control system provided by the present invention achieves variable frequency speed control of high-voltage motors by setting up a high-voltage power input module, a power conversion module and a motor drive module in coordination, thus meeting the operation requirements of 6kV or 10kV high voltage levels.

[0044] This invention, through the design of an explosion-proof enclosure and an insulating protection module, ensures that the system can operate safely and reliably in hazardous environments with explosive gases, effectively preventing the propagation of internal explosions to the outside.

[0045] This invention achieves real-time monitoring and intelligent control of the system's operating status by setting up a temperature monitoring module and a central control module, thereby improving the system's operational reliability and fault protection capabilities.

[0046] This invention integrates closed-loop speed control and fault diagnosis functions into the central control module, enabling precise adjustment of motor operating parameters and timely handling of faults, thereby improving the overall control performance of the system. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the overall structure of the explosion-proof high-voltage variable frequency speed control motor control system proposed in this invention;

[0048] Figure 2 This is a schematic diagram of the overall technical architecture of the explosion-proof high-voltage variable frequency speed control motor control system proposed in this invention;

[0049] Figure 3 This is a schematic diagram of the core principle framework of the power conversion module in this invention, including the collaborative working relationship between the rectifier unit, the DC bus unit, and the inverter unit;

[0050] Figure 4 This is a schematic diagram of the structural framework integrating the explosion-proof housing and internal components in this invention, showing the layout relationship between the main housing, wiring cavity, heat dissipation structure, power conversion module, and motor drive module;

[0051] Figure 5 This is a schematic diagram of the multi-level interaction relationship and data flow between the temperature monitoring module and the central control module in this invention;

[0052] Figure 6 This is a logical flowchart of the speed closed-loop control and fault diagnosis function of the central control module in this invention. Detailed Implementation

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0054] Please refer to Figure 1 and Figure 2 An explosion-proof high-voltage variable frequency speed control motor control system includes a high-voltage power input module, a power conversion module, a motor drive module, an explosion-proof housing, an insulation protection module, a temperature monitoring module, and a central control module.

[0055] The high-voltage power input module receives high-voltage electrical energy from the power grid and preprocesses it. The power conversion module rectifies and inverts the preprocessed energy to generate AC power with adjustable frequency and voltage. The motor drive module transmits the adjustable power output from the power conversion module to the load motor. The explosion-proof enclosure seals the power conversion module, motor drive module, and insulation protection module within its internal space. The insulation protection module provides electrical insulation protection for the high-voltage power input module and power conversion module. The temperature monitoring module monitors the operating temperature of the power conversion module, motor drive module, and insulation protection module inside the explosion-proof enclosure in real time. The central control module generates control signals based on external control commands and temperature information fed back from the temperature monitoring module, enabling precise adjustment of operating parameters such as motor speed and torque.

[0056] The high-voltage power input module is configured to receive high-voltage electrical energy from the power grid, preprocess the energy, and then transfer the preprocessed energy to the power conversion module. The high-voltage power input module internally includes a high-voltage transformer and a pre-charging circuit. The high-voltage transformer converts the 6kV or 10kV high-voltage AC power input from the power grid to a voltage level suitable for the power conversion module. The pre-charging circuit performs soft charging of the DC bus capacitor during system startup to prevent damage to power devices from inrush currents caused by sudden high voltage increases. The high-voltage power input module also includes a voltage detection unit and a current detection unit, used to acquire input voltage and current signals in real time and transmit the acquired signals to the central control module for monitoring and analysis. The input terminal of the high-voltage power input module is equipped with a high-voltage fuse to quickly disconnect the fault circuit in the event of a short circuit on the power grid side, protecting downstream power devices from overcurrent damage. The connection between the high-voltage power input module and the power conversion module adopts a busbar structure, with insulating supports between the busbars to ensure that the electrical clearance meets the requirements for high-voltage operation.

[0057] The power conversion module is configured to rectify and invert electrical energy from the high-voltage power input module to generate AC power with adjustable frequency and voltage. The power conversion module internally includes a power module and a drive circuit. Please refer to... Figure 3 The power conversion module includes a rectifier unit, an inverter unit, and a DC bus unit, wherein: the rectifier unit is configured to convert high-voltage AC power into DC power; the DC bus unit is configured to filter and regulate the DC power output from the rectifier unit to provide a stable DC power supply for the inverter unit; and the inverter unit is configured to convert the DC power output from the DC bus unit into AC power with adjustable frequency and voltage.

[0058] The rectifier unit adopts a multi-pulse rectifier topology and is equipped with power diode modules and voltage equalization protection circuits. The power diode modules use a series-parallel combination of high-voltage fast recovery diodes, achieving voltage equalization among the diodes through series voltage equalization resistors and parallel voltage equalization capacitors, ensuring the rectifier unit can withstand DC bus voltages of 6kV or 10kV. The input side of the rectifier unit is equipped with an LC filter circuit to suppress harmonic current injection from the grid side, meeting grid compatibility requirements. The rectifier unit also features short-circuit protection; when a short-circuit fault occurs on the load side, the rectifier unit can quickly block the output to prevent the fault current from escalating.

[0059] The DC bus unit is equipped with a DC bus capacitor array and a DC voltage detection circuit. The DC bus capacitor array consists of multiple high-voltage energy storage capacitors connected in parallel, configured to absorb the ripple current output from the rectifier unit and stabilize the DC bus voltage. The capacity configuration of the DC bus capacitor array is determined based on the rated power and ripple voltage requirements of the power conversion module to ensure stable DC voltage during load changes. The DC voltage detection circuit is configured to monitor the DC bus voltage value in real time and feed the voltage signal back to the central control module for overvoltage and undervoltage protection functions. The DC bus unit also includes a DC bus discharge circuit, which automatically discharges the bus capacitors after system shutdown to ensure maintenance safety.

[0060] The inverter unit adopts a three-level NPC topology or a T-type topology, and is equipped with IGBT power modules and gate drive circuits. The IGBT power modules are high-voltage, high-power devices capable of withstanding DC bus voltages from 1200V to 3300V and outputting 6kV high-voltage AC power to drive the load motor. The gate drive circuit is configured to receive PWM control signals generated by the central control module, amplify and electrically isolate the PWM control signals, and drive the IGBT power modules to turn on or off according to a preset modulation strategy. The output side of the inverter unit is equipped with voltage and current sensors to collect output voltage and current signals, respectively, for overvoltage protection, overcurrent protection, and short-circuit protection. The inverter unit also includes a temperature sensor to monitor the junction temperature of the IGBT power modules and prevent overheating damage.

[0061] The motor drive module includes an output filtering module and an output protection unit. The output filtering module is located between the output of the power conversion module and the load motor, and includes an output reactor, a filter capacitor, and output terminals. The output reactor and filter capacitor form an LC filter circuit to filter out high-order harmonics in the PWM wave output by the power conversion module, making the output current waveform closer to a sine wave to reduce harmonic losses and torque ripple. The output terminals are located at the output of the output filtering module and serve as a connection interface with an external high-voltage cable, used to transmit the filtered AC power to the load motor. The output protection unit includes an output current detection unit and an output overload protection unit. The output current detection unit collects the output current signal in real time and feeds it back to the central control module, providing feedback for overcurrent protection and closed-loop control. The output overload protection unit executes a protection action according to the command of the central control module when the output current exceeds a preset threshold, cutting off the power output. An insulating sleeve is installed where the output terminals pass through the explosion-proof housing wall to ensure electrical insulation and explosion-proof sealing performance at the penetration point.

[0062] Please refer to Figure 4The explosion-proof enclosure adopts an explosion-proof structural design, configured to seal the power conversion module, motor drive module, and insulation protection module within its internal space. The enclosure material and structure meet explosion-proof requirements, capable of withstanding potential internal explosion pressure and preventing the propagation of explosion flames. The explosion-proof enclosure includes a main housing, a wiring cavity, and a heat dissipation structure. The main housing is configured to house the power conversion module and motor drive module, and its outer shell is made of high-strength explosion-proof material, possessing sufficient mechanical strength and sealing performance. The wiring cavity is located on one side of the main housing and is configured to introduce external power lines and control signal lines. The wiring cavity is connected to the main housing via an explosion-proof cable. The heat dissipation structure is located outside the main housing and is configured to effectively dissipate the heat generated by the power conversion module to the external environment.

[0063] The main enclosure adopts a welded explosion-proof structure, and the wall thickness meets the minimum wall thickness requirements specified in the explosion-proof standard, enabling it to withstand an internal explosion pressure of not less than 1 MPa. The outer shell of the main enclosure is made of Q355B low-carbon alloy structural steel or stainless steel, possessing excellent mechanical strength and corrosion resistance. All connecting flanges of the main enclosure employ a stop-fit ​​structure, with explosion-proof sealing rings used to achieve a seal between the flange faces, ensuring that the width and gap of the explosion-proof joint surface meet the explosion-proof rating requirements. An internal mounting bracket is provided within the main enclosure for fixing the various module units of the power conversion module and motor drive module. The mounting bracket is isolated from the main enclosure by insulating gaskets to prevent electrical connection between the module shell and the enclosure.

[0064] The wiring compartment is located on one side of the main enclosure and is configured for introducing external power lines and control signal lines. The wiring compartment employs an independent explosion-proof cavity structure and is connected to the main enclosure via an explosion-proof cable entry module. The explosion-proof cable entry module uses a compression-type cable gland, capable of sealing and fixing high-voltage cables of different outer diameters to ensure explosion-proof performance at the cable entry point. The wiring compartment contains terminal blocks for connecting external power lines, control signal lines, and motor load lines. The cover plate of the wiring compartment is bolted on, and the explosion-proof mating surface between the cover plate and the cavity meets explosion-proof requirements.

[0065] The heat dissipation structure is located outside the main enclosure and is configured to effectively dissipate the heat generated by the power conversion module to the external environment. The heat dissipation structure uses a radiator made of aluminum alloy or copper alloy, and the radiator fin arrangement is designed to meet the requirements of forced air cooling or water cooling. The hot end of the radiator is connected to the IGBT module of the power conversion module via a thermally conductive insulating pad to ensure minimal thermal resistance. The heat dissipation structure also includes a cooling fan or a cooling water circulation system to enhance the heat dissipation effect. The cooling fan is an explosion-proof axial fan with a protection rating of not less than IP65, enabling safe operation outside the explosion-proof enclosure. The cooling water circulation system adopts a closed-loop cooling scheme, with heat exchange between the cooling water and the heat-generating components through a plate heat exchanger, preventing cooling water from directly entering the explosion-proof cavity.

[0066] The insulation protection module is configured to provide electrical insulation protection for the high-voltage power input module and power conversion module, including high-voltage insulation materials, insulation support structure, and electrical clearance design. The insulation protection module includes a high-voltage insulation board, an insulating sleeve, and a grounding protection module. Specifically: the high-voltage insulation board is positioned between the high-voltage power input module and the explosion-proof enclosure, providing electrical isolation and insulation support; the insulating sleeve is positioned around conductive components penetrating the explosion-proof enclosure, ensuring electrical sealing performance at the penetration point; and the grounding protection module reliably connects the explosion-proof enclosure to the earth, preventing the accumulation of dangerous potential within the enclosure.

[0067] The high-voltage insulation board is made of high-performance insulating materials such as epoxy resin or polyimide, with a thickness configuration that meets high-voltage electrical insulation requirements and can withstand insulation withstand voltages of 6kV or 10kV. The high-voltage insulation board is positioned between the high-voltage power input module and the explosion-proof housing for electrical isolation and mechanical support. The surface of the high-voltage insulation board is treated with moisture-proof material to prevent degradation of insulation performance in high-humidity environments. The shape and size of the high-voltage insulation board are determined according to the installation location, and it has corresponding mounting holes and wire passage holes.

[0068] The insulating sleeve, made of ceramic or glass fiber reinforced epoxy resin, is configured around conductive components that penetrate the explosion-proof enclosure. These conductive components include high-voltage busbars, signal lines, and control lines, which must be isolated by the insulating sleeve when penetrating the explosion-proof enclosure. The connection between the insulating sleeve and the explosion-proof enclosure is achieved through threaded fastening or adhesive bonding, ensuring a reliable seal. An appropriate gap is maintained between the inner diameter of the insulating sleeve and the outer diameter of the penetrating conductive component, meeting electrical clearance and creepage distance requirements.

[0069] The grounding protection module is configured to reliably connect the explosion-proof enclosure to the earth, preventing the accumulation of dangerous potential within the enclosure. The grounding protection module includes a grounding busbar and a grounding wire. The grounding busbar is fixed inside the explosion-proof enclosure, and one end of the grounding wire is connected to the grounding busbar, while the other end is connected to the earth via a grounding bolt. The grounding resistance of the grounding protection module meets the explosion-proof rating requirements, typically not exceeding 4 ohms. The cross-sectional area of ​​the grounding busbar meets the thermal stability requirements for short-circuit current, capable of withstanding short-term high current flow without damage.

[0070] The temperature monitoring module is configured to monitor the operating temperature of the power conversion module, motor drive module, and insulation protection module inside the explosion-proof enclosure in real time, and feed the temperature information back to the central control module. The temperature monitoring module includes a temperature sensor array, a signal acquisition circuit, and a temperature comparator. Please refer to [reference needed]. Figure 5 The temperature sensor array is located at key positions inside the power module of the power conversion module, the drive element of the motor drive module, and the explosion-proof housing, and is configured to collect temperature data from each temperature measurement point in real time. The signal acquisition circuit is configured to amplify and convert the analog signal output by the temperature sensor array to digital. The temperature comparator is configured to compare the collected temperature data with a preset temperature threshold, and send an alarm signal to the central control module when the temperature exceeds the preset threshold.

[0071] The temperature sensor array employs platinum resistance temperature sensors or thermistor temperature sensors, configured at key locations such as the surface of the IGBT module heatsink, the surface of the DC bus capacitor, the surface of the output reactor, and the air inside the explosion-proof enclosure. The temperature sensors use either lead-wire or plug-in mounting methods, with the leads connected to the signal acquisition circuit via terminals inside the explosion-proof enclosure. The temperature measurement range of the sensors covers -40℃ to 150℃, with an accuracy class of at least B, meeting the temperature measurement requirements of industrial environments.

[0072] The signal acquisition circuit configuration includes a signal amplification circuit and a multi-channel analog switch circuit. The signal amplification circuit employs an instrumentation amplifier architecture to amplify the weak voltage signal output from the temperature sensor, making it suitable for the input range of the analog-to-digital converter (ADC). The multi-channel analog switch circuit is configured to time-division multiplex the multiple temperature sensor signals for sampling by the ADC, reducing hardware costs. The ADC uses 12-bit or 16-bit resolution with a sampling rate of no less than 100 SPS to meet the accuracy requirements of temperature signal acquisition. The signal acquisition circuit also includes a cold junction compensation circuit to compensate for cold junction errors during thermocouple temperature measurement.

[0073] The temperature comparator is equipped with multiple temperature threshold registers, which store over-temperature alarm thresholds and over-temperature protection thresholds, respectively. The temperature comparator compares the collected temperature data with the stored temperature thresholds in real time. When the temperature exceeds the over-temperature alarm threshold, an alarm signal is sent to the central control module; when the temperature exceeds the over-temperature protection threshold, a protection action signal is sent to the central control module. The temperature comparator can also be configured with a temperature change rate detection function. When the temperature change rate exceeds a preset threshold, it is determined to be an abnormal temperature rise state, and the protection action is triggered in a timely manner.

[0074] The central control module is configured to receive external control commands and temperature information from the temperature monitoring module, generate control signals according to a preset control strategy, and send these control signals to the power conversion module to achieve precise adjustment of operating parameters such as motor speed and torque. The central control module includes a microprocessor unit, a storage unit, a communication interface, and a fault diagnosis unit. Specifically: the microprocessor unit is configured to execute control algorithms and logical operations to generate control signals for the power conversion module; the storage unit is configured to store control programs, preset parameters, and operating data; the communication interface is configured to interact with an external monitoring system, receive external control commands, and report system operating status; the fault diagnosis unit is configured to monitor the system operating status in real time, detect overcurrent, overvoltage, undervoltage, and overtemperature faults, and execute corresponding protective actions when a fault occurs.

[0075] The microprocessor unit employs a high-performance digital signal processor or embedded microprocessor chip, configured to execute vector control algorithms or direct torque control algorithms, generating PWM modulation signals to control the switching actions of the inverter unit. The clock frequency of the microprocessor unit is no less than 200MHz, enabling complex control algorithms and high-speed real-time computation. The microprocessor unit integrates multiple PWM output channels, an analog-to-digital converter interface, and general-purpose input / output interfaces to meet the system's signal acquisition and control output requirements. The microprocessor unit is also equipped with a watchdog timer to monitor the program's running status and automatically reset and resume operation if the program crashes.

[0076] The storage unit comprises two parts: non-volatile memory and volatile memory. The non-volatile memory, using Flash memory or EEPROM, stores the control program, preset parameters, and configuration data; data is retained even after power failure. The volatile memory, using DDR or SDRAM, stores temporary data and intermediate variables during operation. The storage capacity of the storage unit is configured to meet the storage requirements of the control program and operational data; the Flash memory capacity is no less than 2MB, and the DDR memory capacity is no less than 256MB.

[0077] The communication interface is configured for data interaction with external monitoring systems, receiving external control commands and reporting system operating status. The communication interface supports multiple industrial communication protocols, including Modbus, PROFIBUS, or Ethernet. The physical layer interface uses an RS485 or RJ45 connector, with a configurable communication rate supporting up to 10Mbps or 100Mbps. The communication interface supports master-slave communication mode, where the central control module acts as a slave responding to control commands and query requests from the external master station. The communication interface also supports online parameter modification, allowing the external monitoring system to modify control parameters and operating settings.

[0078] The fault diagnosis unit is configured to monitor the system's operating status in real time, detect overcurrent, overvoltage, undervoltage, and overtemperature faults, and execute corresponding protective actions when a fault occurs. The fault diagnosis unit collects signals from voltage, current, and temperature sensors and compares them with preset fault thresholds to determine whether a fault has occurred. The fault types detected by the fault diagnosis unit include: input overvoltage fault, input undervoltage fault, DC bus overvoltage fault, DC bus undervoltage fault, output overcurrent fault, output short circuit fault, IGBT overtemperature fault, and motor overtemperature fault. After detecting a fault, the fault diagnosis unit executes corresponding protective actions based on the fault level, including alarm, reduced power operation, or emergency shutdown, and reports the fault information to an external monitoring system via a communication interface.

[0079] Please refer to Figure 6 The central control module is also equipped with a speed closed-loop control function. Based on the deviation between the speed signal fed back from the motor and the given speed value, it dynamically adjusts the output frequency of the power conversion module to achieve precise tracking of the motor speed. This speed closed-loop control function employs a PID control algorithm or an adaptive control algorithm, calculating the required voltage-to-frequency ratio based on the speed deviation and generating a corresponding PWM modulation signal to control the inverter unit output. The speed signal fed back from the motor comes from a photoelectric encoder or rotary transformer installed on the motor shaft. The output signal of the photoelectric encoder or rotary transformer is processed by the capture circuit of the central control module to obtain the actual motor speed value. The speed regulation range of the speed closed-loop control function covers 1:10 or wider, with a speed regulation accuracy of not less than 0.5%, and the response time meets the dynamic performance requirements of industrial processes.

[0080] Example 2

[0081] To meet the needs of different application scenarios, the present invention also provides a second specific implementation of the explosion-proof high-voltage variable frequency speed control motor control system. The main difference between this implementation and the first embodiment lies in the difference in the topology of the power conversion module and the control strategy.

[0082] An explosion-proof high-voltage variable frequency speed control motor control system includes a high-voltage power input module, a power conversion module, a motor drive module, an explosion-proof housing, an insulation protection module, a temperature monitoring module, and a central control module. The functional definitions of each module are the same as in Embodiment 1, except for the specific implementation methods of the power conversion module and the central control module.

[0083] The power conversion module adopts a cascaded multilevel topology instead of the three-level NPC topology in Example 1. The cascaded multilevel topology consists of multiple independent power units connected in series. Each power unit includes a rectifier circuit, a DC energy storage capacitor, and an inverter circuit. The output voltages of these multiple power units are superimposed in series to form a multilevel output voltage waveform. The number of output voltage levels is equal to twice the number of power units connected in series plus one. This cascaded multilevel topology eliminates the need for high-voltage IGBT devices; high-voltage output can be achieved using low-voltage devices, reducing the difficulty and cost of device selection. The number of power units in the cascaded multilevel topology is determined by the output voltage level; a 6kV output typically requires five or six power units connected in series.

[0084] Each power unit of the power conversion module is equipped with an independent drive circuit and control circuit. The drive circuit receives PWM control signals allocated by the central control module to control the switching action of the inverter circuit. The power units are connected via high-speed optical fiber communication. The central control module sends control commands to each power unit through the optical fiber and simultaneously receives status information fed back by each power unit. The DC bus voltage of each power unit is obtained independently through its respective rectifier circuit. The DC voltage balance between the power units is uniformly managed by the central control module, which achieves DC voltage balance control by adjusting the PWM duty cycle of each power unit.

[0085] The motor drive module is the same as in Embodiment 1, including an output filter module for filtering the PWM waveform output by the inverter unit to reduce the impact of harmonic components on the load motor. The filtering parameters of the output filter module are adapted to the output characteristics of the cascaded multilevel topology. Since the output harmonic characteristics of the cascaded multilevel topology are better than those of the traditional two-level topology, the required filter capacity can be reduced accordingly.

[0086] In Embodiment 2, the central control module adopts a distributed control architecture, configured with a master control board and multiple slave control boards. The master control board is responsible for system-level control functions, including closed-loop speed control, speed setpoint processing, fault aggregation, and communication management. The number of slave control boards is the same as the number of power units, and each slave control board is responsible for the control functions of its corresponding power unit, including PWM generation, drive signal output, and unit-level fault detection. The master control board and slave control boards are connected via a high-speed parallel bus or fiber optic communication, with a communication delay of less than 1 microsecond, meeting the real-time requirements of multi-unit collaborative control.

[0087] The central control module is equipped with a speed closed-loop control function. In Example 2, the speed closed-loop control function is implemented using a vector control algorithm. This vector control algorithm decomposes the stator current into excitation and torque components, which are controlled independently to achieve precise control of the motor flux and torque. The vector control algorithm requires obtaining the motor rotor position information, which is acquired through a rotary transformer or photoelectric encoder. The output signal of the rotary transformer or photoelectric encoder is processed by the capture circuit of the main control board to obtain the rotor position angle. The current loop control period of the vector control algorithm is no greater than 100 microseconds, and the speed loop control period is no greater than 1 millisecond, ensuring that the control performance and dynamic response meet the requirements.

[0088] In Embodiment 2, the temperature monitoring module's temperature sensor array is positioned at key locations on the surface of the IGBT module heatsink, the surface of the DC bus capacitor, and inside the explosion-proof enclosure of each power unit. The temperature sensors are digital, transmitting temperature data to the corresponding slave control board via a single bus or I2C bus. The slave control board aggregates the temperature data and transmits it to the main control board for unified processing via a high-speed bus. The temperature comparator's function is integrated into the slave control board's software program. When the detected temperature exceeds a preset threshold, the slave control board executes power unit-level protection actions and simultaneously reports temperature fault information to the main control board.

[0089] The explosion-proof high-voltage variable frequency speed control motor control system provided by this invention achieves variable frequency speed control of the high-voltage motor through the coordinated operation of the high-voltage power input module, power conversion module, and motor drive module, meeting the operational requirements of 6kV or 10kV high-voltage levels. The design of the explosion-proof enclosure and insulation protection module ensures safe and reliable operation in hazardous environments with explosive gases, effectively preventing the propagation of internal explosions to the outside. The inclusion of a temperature monitoring module and a central control module enables real-time monitoring and intelligent control of the system's operating status, improving operational reliability and fault protection capabilities. Furthermore, the integration of closed-loop speed control and fault diagnosis functions in the central control module enables precise adjustment of motor operating parameters and timely fault handling, enhancing the overall control performance of the system.

[0090] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A flameproof high-voltage variable frequency speed control motor control system, characterized in that, include: The high-voltage power input module, power conversion module, motor drive module, explosion-proof enclosure, insulation protection module, temperature monitoring module, and central control module are included, with the high voltage being 6kV or 10kV. The high-voltage power input module is configured to receive high-voltage power from the power grid, preprocess the high-voltage power, and then transfer the preprocessed power to the power conversion module. The power conversion module is configured to rectify and invert electrical energy from the high-voltage power input module to generate AC power with adjustable frequency and voltage. The power conversion module contains a power module and a drive circuit. The motor drive module is configured to receive adjustable electrical energy output from the power conversion module and transmit the adjustable electrical energy to the load motor. The explosion-proof enclosure adopts an explosion-proof structural design and is configured to seal the power conversion module, motor drive module and insulation protection module in its internal space. The material and structure of the explosion-proof enclosure meet the explosion-proof level requirements. The insulation protection module is configured to provide electrical insulation protection for the high-voltage power input module and the power conversion module. The temperature monitoring module is configured to monitor the operating temperature of the power conversion module, motor drive module and insulation protection module inside the explosion-proof enclosure in real time, and feed the temperature information back to the central control module. The central control module is configured to receive external control commands and temperature information from the temperature monitoring module, generate control signals according to the preset control strategy, and send the control signals to the power conversion module.

2. The explosion-proof high-voltage variable frequency speed control motor control system according to claim 1, characterized in that: The power conversion module includes a rectifier unit, an inverter unit, and a DC bus unit. The rectifier unit is configured to convert high-voltage AC power into DC power. The DC bus unit is configured to filter and regulate the DC power output from the rectifier unit to provide a stable DC power supply for the inverter unit. The inverter unit is configured to convert the DC power output from the DC bus unit into AC power with adjustable frequency and voltage.

3. The explosion-proof high-voltage variable frequency speed control motor control system according to claim 1, characterized in that: The motor drive module includes an output filtering module and an output protection unit; the output filtering module includes an output reactor, a filter capacitor, and an output terminal set at its output end, the output terminal being used to connect to the load motor through a high-voltage cable; the output protection unit includes an output current detection unit and an output overload protection unit; an insulating sleeve is provided where the output terminal passes through the explosion-proof housing wall.

4. The explosion-proof high-voltage variable frequency speed control motor control system according to claim 1, characterized in that: The explosion-proof enclosure includes a main housing, a wiring cavity, and a heat dissipation structure; The main enclosure is designed to house the power conversion module and the motor drive module. The outer shell of the main enclosure is made of high-strength explosion-proof material. The main enclosure adopts a welded explosion-proof structure, and the wall thickness of the enclosure can withstand an internal explosion pressure of not less than 1MPa. The outer shell of the main enclosure is made of low-carbon alloy structural steel or stainless steel. The connecting flanges of the main enclosure adopt a stop fit structure, and the flanges are sealed with explosion-proof sealing rings. The wiring compartment is located on one side of the main enclosure and is used to introduce external power lines and control signal lines; The heat dissipation structure is located outside the main enclosure and is used to dissipate the heat generated by the power conversion module to the external environment. The heat dissipation structure includes a heat sink, which is connected to the power module of the power conversion module by a thermally conductive insulating pad.

5. The explosion-proof high-voltage variable frequency speed control motor control system according to claim 1, characterized in that: The insulation protection module includes a high-voltage insulation board, an insulating sleeve, and a grounding protection module. The high-voltage insulation board is disposed between the high-voltage power input module and the explosion-proof enclosure to provide electrical isolation and insulation support. The insulating sleeve is disposed around the conductive parts that penetrate the explosion-proof enclosure to ensure the electrical sealing performance at the penetration point. The grounding protection module is configured to reliably connect the explosion-proof enclosure to the ground.

6. The explosion-proof high-voltage variable frequency speed control motor control system according to claim 1, characterized in that: The temperature monitoring module includes a temperature sensor array, a signal acquisition circuit, and a temperature comparator. The temperature sensor array is located in key positions inside the power module of the power conversion module, the drive element of the motor drive module, and the explosion-proof housing. The signal acquisition circuit is configured to amplify and convert the analog signal output by the temperature sensor array to digital. The temperature comparator is configured to compare the acquired temperature data with a preset temperature threshold, and send an alarm signal to the central control module when the temperature exceeds the preset threshold.

7. The explosion-proof high-voltage variable frequency speed control motor control system according to claim 1, characterized in that: The central control module includes a microprocessor unit, a storage unit, a communication interface, and a fault diagnosis unit. The microprocessor unit is configured to execute control algorithms and logic operations to generate control signals for the power conversion module. The storage unit is configured to store control programs, preset parameters, and operating data. The communication interface is configured to interact with an external monitoring system. The fault diagnosis unit is configured to monitor the system's operating status in real time, detect overcurrent, overvoltage, undervoltage, and overtemperature faults, and execute corresponding protection actions when a fault occurs. The central control module is also equipped with a speed closed-loop control function. Based on the deviation between the speed signal fed back by the motor and the given speed value, the output frequency of the power conversion module is dynamically adjusted. The speed closed-loop control function adopts a PID control algorithm or an adaptive control algorithm. Based on the speed deviation, the required voltage-frequency ratio is calculated, and the corresponding PWM modulation signal is generated to control the output of the inverter unit.

8. The explosion-proof high-voltage variable frequency speed control motor control system according to claim 2, characterized in that: The rectifier unit adopts a multi-pulse rectifier topology and is equipped with a power diode module and a voltage equalization protection circuit; the input side of the rectifier unit is equipped with an LC filter circuit; the rectifier unit is also equipped with a short-circuit protection function.

9. The explosion-proof high-voltage variable frequency speed control motor control system according to claim 2, characterized in that: The DC bus unit is equipped with a DC bus capacitor array and a DC voltage detection circuit; the DC bus capacitor array is composed of multiple high-voltage energy storage capacitors connected in parallel; the DC bus unit also includes a DC bus discharge circuit.

10. The explosion-proof high-voltage variable frequency speed control motor control system according to claim 2, characterized in that: The inverter unit adopts a three-level NPC topology or a T-type topology and is equipped with an IGBT power module and a gate drive circuit; the output side of the inverter unit is equipped with a voltage sensor and a current sensor; the inverter unit is also equipped with a temperature sensor.

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