Cooling fault control system of variable frequency motor

Abstract

The utility model discloses a variable frequency motor heat radiation fault control system which comprises a variable frequency motor, a cooling fan is arranged at the rear end of the variable frequency motor, a temperature measuring element is installed on a winding of the variable frequency motor, and a detection signal of the temperature measuring element is transmitted to a control module through a signal processing module. The control module performs logic judgment on the received data signal and controls the start and stop states of the variable frequency motor according to a judgment result; according to the utility model, the temperature measuring element is adopted to carry out multi-point measurement on the working temperature of the winding of the variable frequency motor, so that comprehensive analysis on data of a plurality of temperature points is realized to judge the thermal state of the variable frequency motor; and in combination with an amplification noise reduction and compensation adjustment circuit of the signal processing module, the accuracy and stability of temperature data are ensured, and the judgment accuracy and control reliability of the system on the heat dissipation fault of the variable frequency motor are effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of battery power supply, in particular to a frequency conversion motor heat dissipation fault control system. Background Art

[0002] In the process of converting electrical energy into mechanical energy, the variable frequency motor generates heat due to iron loss, copper loss, mechanical loss and other losses. Currently, the windings of variable frequency motors on the market are mostly Class B insulation, with a maximum operating temperature of 130°C and a temperature rise of 80K. The working environment temperature of the variable frequency motor is about 30°C-40°C.

[0003] At present, variable frequency motors are usually cooled by independent fans. In terms of structure, there are no blades on the shaft of the variable frequency motor. Instead, a cooling fan is installed in the fan cover of the variable frequency motor. The purpose is to ensure that when the variable frequency motor is running at a low frequency, the cooling fan still runs at the industrial frequency to ensure the heat dissipation of the variable frequency motor. Based on many years of experience in using variable frequency motors, the cooling fan has the highest failure rate in variable frequency motors. Once the cooling fan fails, the variable frequency motor will not be able to dissipate the internal heat quickly due to poor ventilation, causing the temperature to rise rapidly, which will cause the variable frequency motor to burn out and may even cause safety accidents.

[0004] Therefore, the utility model provides a new solution to solve this problem. Utility Model Content

[0005] In view of the above situation, in order to overcome the defects of the prior art, the purpose of the utility model is to provide a variable frequency motor heat dissipation fault control system.

[0006] The technical solution is: a variable frequency motor heat dissipation fault control system, including a variable frequency motor, a cooling fan is arranged at the rear end of the variable frequency motor, a temperature measuring element is installed on the winding of the variable frequency motor, the detection signal of the temperature measuring element is transmitted to the control module through the signal processing module, the control module performs logical judgment on the received data signal, and controls the start and stop state of the variable frequency motor according to the judgment result; the signal processing module includes a detection signal amplification and noise reduction circuit and a compensation adjustment circuit, the detection signal amplification and noise reduction circuit is used to perform amplitude enhancement and filtering processing on the detection signal of the temperature measuring element, and the compensation adjustment circuit is used to sample and amplify the output signal of the detection signal amplification and noise reduction circuit, and then suppress the drift generated by the temperature measuring element through compensation adjustment.

[0007] Preferably, the detection signal amplification and noise reduction circuit includes an op amp AR1, a MOS tube Q1, a MOS tube Q2 and a filter component. The inverting input end of the op amp AR1 is connected to the signal output end of the temperature measuring element and the drain of the MOS tube Q1 through a resistor R1, and is connected to the source of the MOS tube Q2 through the filter component. The non-inverting input end of the op amp AR1 is connected to the source of the MOS tube Q1 and is grounded through a resistor R7. The output end of the op amp AR1 is connected to the gate of the MOS tube Q2 through a resistor R3, and the drain of the MOS tube Q2 is connected to one end of the capacitor C2 and the control module through a resistor R4, and the other end of the capacitor C2 is grounded.

[0008] Preferably, the filtering component includes an inductor L1, a capacitor C1 and a resistor R2, one end of the inductor L1 and the resistor R2 is connected to the inverting input terminal of the operational amplifier AR1, and the other end of the inductor L1 is connected to the other end of the resistor R2 and the source of the MOS tube Q2 through the capacitor C1.

[0009] Preferably, the compensation and adjustment circuit includes an operational amplifier AR2, a voltage zener diode DZ1 and a variable resistor RP1, the non-inverting input terminal of the operational amplifier AR2 is connected to the cathode of the voltage zener diode DZ1 and the adjustment terminal of the variable resistor RP1, one end of the variable resistor RP1 is connected to the drain of the MOS tube Q2, the other end of the variable resistor RP1 is grounded through a resistor R5, the anode of the voltage zener diode DZ1 is grounded, the inverting input terminal and the output terminal of the operational amplifier AR2 are connected to the gate of the MOS tube Q1 and one end of the capacitor C3 through a resistor R6, and the other end of the capacitor C3 is grounded.

[0010] Preferably, the control module uses a DCS control system, and the control output end of the DCS control system is connected to a variable frequency motor control loop.

[0011] Preferably, the variable frequency motor control circuit includes a power supply, and a start switch, a stop switch and a relay coil connected in series in the power supply circuit, and the normally open contact of the relay is arranged in parallel with the start switch.

[0012] Preferably, the temperature measuring element is a platinum thermal resistor.

[0013] Through the above technical scheme, the beneficial effects of the utility model are:

[0014] 1. The utility model adopts temperature measuring elements to measure the working temperature of the winding of the variable frequency motor at multiple points, so as to realize comprehensive analysis of the data of multiple temperature points to judge the thermal state of the variable frequency motor; combined with the amplification and noise reduction and compensation adjustment circuit of the signal processing module, the accuracy and stability of the temperature data are ensured, and the judgment accuracy and control reliability of the system for the heat dissipation failure of the variable frequency motor are effectively improved;

[0015] 2. By utilizing the advanced logic judgment and control capabilities of the DCS control system, intelligent management of the start and stop status of the variable frequency motor is realized. Once the temperature is detected to exceed the preset threshold, the system can automatically cut off the power supply to prevent the variable frequency motor from overheating and damage. This not only reduces the failure rate of the motor, but also enhances the safety of the entire production process, providing an effective motor protection solution for the field of industrial automation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the electric control principle of the utility model.

[0017] Figure 2 This is a circuit schematic diagram of the signal processing module in the utility model. DETAILED DESCRIPTION

[0018] The above and other technical contents, features and functions of the present invention are described in detail below with reference to the attached Figure 1 To Attachment Figure 2 The detailed description of the embodiments will clearly show that the structural contents mentioned in the following embodiments are all based on the drawings in the specification.

[0019] Various exemplary embodiments of the present utility model will be described below with reference to the accompanying drawings.

[0020] like Figure 1 As shown, a variable frequency motor heat dissipation fault control system includes a variable frequency motor 1, a cooling fan 2 is configured at the rear end of the variable frequency motor 1, a temperature measuring element 3 is installed on the winding of the variable frequency motor 1, and the detection signal of the temperature measuring element 3 is transmitted to the control module 5 through the signal processing module 4. The control module 5 performs logical judgment on the received data signal and controls the start and stop state of the variable frequency motor 1 according to the judgment result.

[0021] In the above, the temperature measuring element 3 can use multiple platinum thermal resistors to perform multi-point measurement of the winding working temperature of the variable frequency motor, so as to achieve comprehensive analysis of the data of multiple temperature points to determine the thermal state of the variable frequency motor. Since the temperature measuring element is easily affected by the working environment of the variable frequency motor during the measurement process, such as electromagnetic interference, temperature fluctuation, etc., the signal processing module 4 is used to condition the detection signal of the temperature measuring element. Specifically, Figure 2 As shown, the signal processing module 4 includes a detection signal amplification and noise reduction circuit and a compensation adjustment circuit. The detection signal amplification and noise reduction circuit is used to perform amplitude enhancement and filtering processing on the detection signal of the temperature measuring element 3. The compensation adjustment circuit is used to sample and amplify the output signal of the detection signal amplification and noise reduction circuit, and then suppress the drift generated by the temperature measuring element 3 through compensation adjustment.

[0022] The detection signal amplification and noise reduction circuit includes an op amp AR1, a MOS tube Q1, a MOS tube Q2 and a filter component, wherein the inverting input terminal of the op amp AR1 is connected to the signal output terminal of the temperature measuring element and the drain of the MOS tube Q1 through a resistor R1, and is connected to the source of the MOS tube Q2 through a filter component, the non-inverting input terminal of the op amp AR1 is connected to the source of the MOS tube Q1 and is grounded through a resistor R7, the output terminal of the op amp AR1 is connected to the gate of the MOS tube Q2 through a resistor R3, the drain of the MOS tube Q2 is connected to one end of the capacitor C2 and the control module through a resistor R4, and the other end of the capacitor C2 is grounded. The filter component includes an inductor L1, a capacitor C1 and a resistor R2, one end of the inductor L1 and the resistor R2 are connected to the inverting input terminal of the op amp AR1, and the other end of the inductor L1 is connected to the other end of the resistor R2 and the source of the MOS tube Q2 through the capacitor C1.

[0023] During the operation of the detection signal amplification and noise reduction circuit, the operational amplifier AR1 is first used as the main amplifier to amplify the detection signal of the temperature measuring element, and the amplitude of the temperature detection signal is quickly enhanced. At the same time, a MOS tube Q2 is set at the output end of the operational amplifier AR1 to improve the waveform of the amplified signal, and the detection signal is passed through a filtering component to filter out high-frequency noise, which not only improves the accuracy of temperature measurement, but also enhances the anti-interference ability of the system, so that the system can work stably in a complex electromagnetic environment.

[0024] In order to further avoid the temperature drift and imbalance of the detection signal caused by environmental factors, a compensation adjustment circuit is used to process the output signal of the detection signal amplification and noise reduction circuit. The compensation adjustment circuit includes an op amp AR2, a voltage stabilizing diode DZ1 and a variable resistor RP1, the in-phase input end of the op amp AR2 is connected to the cathode of the voltage stabilizing diode DZ1 and the adjustment end of the variable resistor RP1, one end of the variable resistor RP1 is connected to the drain of the MOS tube Q2, the other end of the variable resistor RP1 is grounded through a resistor R5, the anode of the voltage stabilizing diode DZ1 is grounded, the inverting input end and the output end of the op amp AR2 are connected to the gate of the MOS tube Q1 and one end of the capacitor C3 through a resistor R6, and the other end of the capacitor C3 is grounded.

[0025] During the operation of the compensation and adjustment circuit, the variable resistor RP1 is used to sample the output signal of the detection signal amplification and noise reduction circuit, and then the signal is sent to the operational amplifier AR2 after being stabilized by the voltage stabilizing diode DZ1. The operational amplifier AR2 amplifies the sampled signal by using the voltage follower principle, thereby providing a stable follower voltage for the MOS tube Q1. The amplitude of the follower voltage can determine the conduction degree of the MOS tube Q1, thereby automatically adjusting the conduction resistance of the MOS tube Q1. As the MOS tube Q1 is turned on, the feedback signal is received by the in-phase input terminal of the operational amplifier AR1, and the input offset voltage of the inverting input terminal of the operational amplifier AR1 is eliminated by using the subtractor principle. The above automatic adjustment mechanism can effectively suppress temperature drift and improve the stability and accuracy of the system.

[0026] The temperature detection signal conditioned by the signal processing module is sent to the control module for calculation and processing. Specifically, the control module uses a DCS control system, and the control output end of the DCS control system is connected to the variable frequency motor control loop. During specific operation, the controller of the DCS control system compares and analyzes the processed temperature measurement data with the system set threshold. When the temperature measurement data exceeds the system set threshold, the controller outputs a stop command to the variable frequency motor control loop to cut off the power supply to the variable frequency motor.

[0027] like Figure 1 As shown, specifically, the variable frequency motor control circuit includes a power supply, and a start switch S2, a stop switch S1 and a coil of a relay KM connected in series in the power supply circuit, and the normally open contact of the relay KM is set in parallel with the start switch. When the variable frequency motor works normally, the start switch S2 and the stop switch S1 are closed at the same time, the coil of the relay KM is energized, and its normally open contact is closed to form a self-locking state with the start switch; when the DCS control system detects that the winding operating temperature of the variable frequency motor exceeds the system set threshold, it is determined that the variable frequency motor has a cooling failure, and its controller outputs a stop command to cut off the stop switch S1, thereby automatically cutting off the power supply to stop the operation of the variable frequency motor, protecting the variable frequency motor from overheating damage, and providing the operator with enough time to deal with abnormal situations to avoid greater impact on the entire production device.

[0028] During the specific use of the utility model, a temperature measuring element is used to perform multi-point measurement of the winding operating temperature of the variable frequency motor, and a comprehensive analysis of the data of multiple temperature points is realized to judge the thermal state of the variable frequency motor; the amplification and noise reduction and compensation adjustment circuit of the signal processing module is combined to ensure the accuracy and stability of the temperature data, and effectively improve the system's judgment accuracy and control reliability of the heat dissipation failure of the variable frequency motor; and the advanced logic judgment and control capabilities of the DCS control system are used to realize intelligent management of the start and stop states of the variable frequency motor. Once the temperature is detected to exceed the preset threshold, the system can automatically cut off the power supply to prevent the variable frequency motor from overheating and damage, which not only reduces the failure rate of the motor, but also enhances the safety of the entire production process, and provides an effective motor protection solution for the field of industrial automation.

[0029] The above is a further detailed description of the utility model in combination with a specific implementation method, and it cannot be determined that the specific implementation of the utility model is limited to this; for technical personnel in the field of the utility model and related technical fields, based on the technical solution of the utility model, the expansion and replacement of operating methods and data should all fall within the protection scope of the utility model.

Claims

1. A variable frequency motor heat dissipation fault control system, comprising a variable frequency motor, a cooling fan is arranged at the rear end of the variable frequency motor, and is characterized in that: A temperature measuring element is installed on the winding of the variable frequency motor, and the detection signal of the temperature measuring element is transmitted to the control module through the signal processing module. The control module performs logical judgment on the received data signal and controls the start and stop state of the variable frequency motor according to the judgment result; The signal processing module includes a detection signal amplification and noise reduction circuit and a compensation adjustment circuit. The detection signal amplification and noise reduction circuit is used to perform amplitude enhancement and filtering processing on the detection signal of the temperature measuring element. The compensation adjustment circuit is used to sample and amplify the output signal of the detection signal amplification and noise reduction circuit, and then suppress the drift generated by the temperature measuring element through compensation adjustment.

2. A variable frequency motor heat dissipation fault control system according to claim 1, characterized in that: The detection signal amplification and noise reduction circuit includes an operational amplifier AR1, a MOS tube Q1, a MOS tube Q2 and a filter component. The inverting input end of the operational amplifier AR1 is connected to the signal output end of the temperature measuring element and the drain of the MOS tube Q1 through a resistor R1, and is connected to the source of the MOS tube Q2 through the filter component. The non-inverting input end of the operational amplifier AR1 is connected to the source of the MOS tube Q1 and is grounded through a resistor R7. The output end of the operational amplifier AR1 is connected to the gate of the MOS tube Q2 through a resistor R3. The drain of the MOS tube Q2 is connected to one end of the capacitor C2 and the control module through a resistor R4, and the other end of the capacitor C2 is grounded.

3. A variable frequency motor heat dissipation fault control system according to claim 2, characterized in that: The filter component includes an inductor L1, a capacitor C1 and a resistor R2. One end of the inductor L1 and the resistor R2 is connected to the inverting input end of the operational amplifier AR1, and the other end of the inductor L1 is connected to the other end of the resistor R2 and the source of the MOS tube Q2 through the capacitor C1.

4. A variable frequency motor heat dissipation fault control system according to claim 3, characterized in that: The compensation adjustment circuit includes an operational amplifier AR2, a voltage-stabilizing diode DZ1 and a variable resistor RP1. The non-inverting input terminal of the operational amplifier AR2 is connected to the cathode of the voltage-stabilizing diode DZ1 and the adjustment terminal of the variable resistor RP1. One end of the variable resistor RP1 is connected to the drain of the MOS tube Q2. The other end of the variable resistor RP1 is grounded through a resistor R5. The anode of the voltage-stabilizing diode DZ1 is grounded. The inverting input terminal and the output terminal of the operational amplifier AR2 are connected to the gate of the MOS tube Q1 and one end of the capacitor C3 through a resistor R6. The other end of the capacitor C3 is grounded.

5. A variable frequency motor heat dissipation fault control system according to claim 4, characterized in that: The control module uses a DCS control system, and the control output end of the DCS control system is connected to a variable frequency motor control loop.

6. A variable frequency motor heat dissipation fault control system according to claim 5, characterized in that: The variable frequency motor control circuit includes a power supply, and a start switch, a stop switch and a relay coil connected in series in the power supply circuit, and the normally open contact of the relay is arranged in parallel with the start switch.

7. A variable frequency motor heat dissipation fault control system according to any one of claims 1 to 6, characterized in that: The temperature measuring element is a platinum thermal resistor.

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