Brake resistor alternating current cooling fan system of mining dump truck and control method

Abstract

The invention belongs to the field of mining dump trucks, and relates to a mining dump truck brake resistor alternating current cooling fan system and a control method. Comprising a wide-width inverter, a whole vehicle system matching module and an alternating-current asynchronous cooling fan, the wide inverter is used for inverting the direct current into alternating current so as to drive a motor of the alternating current asynchronous cooling fan to operate; the alternating-current asynchronous cooling fan is powered by the wide inverter and operates to generate airflow to cool the brake resistor; and the whole vehicle system matching module performs signal interaction with the wide inverter to guarantee power supply of a whole vehicle fan. The device can realize reliable cooling of the brake resistor of the mining dump truck, has the functions of over-temperature protection, fan abnormity protection, cooling prolonging and the like, optimizes the electric brake function of the mining dump truck, improves the system stability, reduces the maintenance period, and improves the use efficiency of the truck.

Description

Technical Field

[0001] The invention belongs to the field of mining dump trucks and relates to a braking resistor AC cooling fan system and a control method for a mining dump truck. Background Art

[0002] Mining dump trucks are widely used to transport materials in industries such as metallurgy, nonferrous metals, chemicals, coal, building materials, and hydropower. They are the primary transport equipment in large open-pit mines. Their operating conditions are complex, transport roads are poorly maintained, and the vehicles frequently switch between traction and braking modes. To ensure system stability, brake resistors are required to dissipate the energy generated by the motor's reverse output during braking. When the brake resistors are operating, electrical energy is converted into heat, which is dissipated by dedicated cooling fans.

[0003] Large mining dump trucks have traditionally used DC fans to cool the brake resistors. However, during mining operations, high levels of ore fines, coal dust, and dust can easily affect the operation of DC fans, causing internal ring fires, carbon brush burnout, and even motor short circuits. This can lead to equipment burnout due to insufficient cooling, causing brake failure, resulting in property damage, and endangering the driver's safety. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and to provide an AC cooling fan system for a braking resistor of a mining dump truck and a control method thereof.

[0005] A mining dump truck brake resistor AC cooling fan system, characterized by comprising: a wide-band inverter, a vehicle system matching module and an AC asynchronous cooling fan; Wide-range inverter: converts DC power into AC power to drive the motor of the AC asynchronous cooling fan; AC asynchronous cooling fan: powered by the wide-range inverter, it generates airflow to cool the brake resistor; Vehicle system matching module: interacts with the wide-band inverter to ensure power supply to the vehicle's wind turbine.

[0006] Furthermore, the wide-band inverter forms a three-level topology structure through an inverter bridge arm composed of multiple groups of power switching devices; The control circuit of the wide-band inverter includes a power board and a control board. The power board processes power circuit signals and cooperates with the inverter bridge arm to realize power conversion; the control board integrates a core control chip.

[0007] Furthermore, the control board includes an FPGA chip and a DSP chip, the FPGA chip is responsible for logic control and signal processing, and the DSP chip is used for algorithm calculation.

[0008] Furthermore, the vehicle system matching module includes a high-voltage detection unit, an MCU unit, and a constant current source circuit; High-voltage detection unit: connects to the DC bus, detects the DC side input voltage, and transmits the voltage signal to the MCU unit; MCU unit: receives high-voltage detection data from the high-voltage detection unit, as well as communication information from the CAN and RS485 buses, conducts communication interaction, and controls output according to the fan status; Constant current source circuit: controlled by the MCU unit, outputs current to the entire vehicle system to ensure power supply for the cooling fan.

[0009] Furthermore, the control board of the wide-band inverter includes an ADC chip, a low-pass filter circuit and a gain circuit.

[0010] Furthermore, the vehicle system matching module includes a voltage sensor and a current sensor. The low-pass filter circuit and the gain circuit condition the voltage signal transmitted by the voltage sensor and the current signal transmitted by the current sensor and input them into the ADC chip.

[0011] Furthermore, the vehicle system matching module includes a temperature sensor, which uses a voltage-controlled constant current source to transmit a temperature signal to an ADC chip through the temperature sensor.

[0012] Furthermore, the vehicle system matching module includes a speed sensor, which transmits the speed signal to the ADC chip through the temperature sensor.

[0013] A control method for an AC cooling fan system for a braking resistor of a mining dump truck as described in any of the above items controls the start and stop of the AC asynchronous cooling fan through a wide-range inverter, thereby achieving cooling of the braking resistor.

[0014] Furthermore, the control logic of the wide-band inverter includes: Startup logic: The wide-range inverter system collects the bus voltage and the feedback signal of the brake resistor control switch RP in real time. During startup, when the bus voltage is greater than 300VDC and the RP feedback signal changes from open to closed, indicating that the vehicle's brake resistor is engaged, the inverter enters the working state and controls the output voltage frequency according to the bus voltage amplitude, thereby controlling the fan speed. Normal shutdown logic: When the RP feedback limit signal changes from closed to open, the inverter shuts down immediately. Then, 500 milliseconds after shutdown, the inverter starts up and controls the fan speed to run at 1000 rpm for 2 seconds to achieve delayed shutdown and enhance the cooling effect of the brake resistor. Protection shutdown logic: If the motor current, temperature, or speed of the wide-range inverter system exceeds the threshold during startup, operation, or shutdown, the fault information will be transmitted to the vehicle system matching module via CAN or 485 communication, and the system will stop working immediately to ensure equipment safety.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention can achieve reliable cooling of the brake resistor of a mining dump truck, has functions such as over-temperature protection, fan abnormality protection, and extended cooling, optimizes the electric braking function of the mining dump truck, improves system stability, reduces maintenance cycles, and improves vehicle utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, serve to explain the principles of the invention.

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0018] Figure 1 This is a schematic diagram of a mining dump truck system of the present invention; Figure 2 This is a diagram of the wide-width inverter system of the present invention; Figure 3 This is a system diagram of the vehicle system matching module of the present invention; Figure 4 This is a diagram showing the relationship between the motor speed and torque of the present invention; Figure 5 This is a diagram showing the relationship between motor line voltage and power of the present invention; Figure 6 This is a schematic diagram of a voltage / current sensor sampling circuit of the present invention; Figure 7 This is a schematic diagram of a temperature sensor sampling circuit of the present invention; Figure 8 Schematic diagram of the speed sensor sampling circuit of the present invention. DETAILED DESCRIPTION

[0019] Here, exemplary embodiments will be described in detail, and the embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Instead, they are only examples consistent with some aspects of the present invention described in detail in the appended claims.

[0020] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. Example

[0021] A braking resistor AC cooling fan system for a mining dump truck, such as Figure 1As shown, it includes: wide-band inverter, vehicle system matching module and AC asynchronous cooling fan; Wide-range inverter: converts DC power into AC power to drive the motor of the AC asynchronous cooling fan; AC asynchronous cooling fan: powered by the wide-range inverter, it generates airflow to cool the brake resistor; Vehicle system matching module: interacts with the wide-band inverter to ensure power supply to the vehicle's wind turbine.

[0022] In this embodiment, the parameters of the AC asynchronous cooling fan are as follows: rated voltage: 690VAC; rated frequency: 105Hz; rated power: 70kW; number of stages: four; weight: 279kg.

[0023] Furthermore, if Figure 2 As shown, the wide-band inverter forms a three-level topology structure through an inverter bridge arm composed of multiple groups of power switching devices; The control circuit of the wide-band inverter includes a power board and a control board. The power board processes power circuit signals and cooperates with the inverter bridge arm to realize power conversion; the control board integrates a core control chip.

[0024] In this embodiment, the functions of the wide frequency conversion system include: 1. Convert the input DC power into variable-frequency AC power through the inverter to provide power for the AC asynchronous fan; 2. Realize DC side input voltage detection and AC side output current detection; 3. Realize motor speed collection and temperature collection.

[0025] 4. The control panel can realize the start and stop of the fan, speed control, and provide overvoltage, undervoltage, overcurrent, overspeed, overtemperature and other protection functions to ensure the stability of the vehicle system.

[0026] 5. The wide frequency conversion system includes a power drive unit, a power sampling board, and a control board.

[0027] like Figure 4The horizontal axis represents torque-related parameters, and the vertical axis represents speed. The chart clearly demonstrates the speed values ​​corresponding to different torque values. As the torque gradually decreases from 214.3 N∙m, the speed rises rapidly, reaches a certain value, and then stabilizes. This can be roughly divided into three stages. In the initial torque stage (around 214.3-214.4 N∙m), the speed increases rapidly as the torque decreases slightly. When the torque is in the intermediate range (around 214.3-210.2 N∙m), the speed continues to rise, but at a slower rate. As the torque further decreases to below 210.2 N∙m and reaches 204.5 N∙m, the speed stabilizes at approximately 3000 rpm. This demonstrates the motor's speed performance under different loads (corresponding to different torque requirements), demonstrating that the motor can maintain a constant speed output under varying torque load conditions.

[0028] like Figure 5 As shown in the figure, the horizontal axis represents power-related parameters, and the vertical axis represents line voltage. As power gradually increases from 0, the line voltage shows a trend of first rising rapidly and then stabilizing. This can be roughly divided into two stages. In the initial power stage (approximately 0-70.1 kW), the line voltage rises rapidly with increasing power. After the power reaches approximately 70.1 kW, the effective value of the line voltage stabilizes at around 690 V. This demonstrates the AC cooling fan system's ability to regulate line voltage at different power outputs. The initial rise and subsequent stabilization of the line voltage demonstrates the AC cooling fan system's voltage self-regulation capabilities.

[0029] Furthermore, the control board includes an FPGA chip and a DSP chip, the FPGA chip is responsible for logic control and signal processing, and the DSP chip is used for algorithm calculation.

[0030] Furthermore, if Figure 3 As shown, the vehicle system matching module includes a high-voltage detection unit, an MCU unit, and a constant current source circuit; High-voltage detection unit: connects to the DC bus, detects the DC side input voltage, and transmits the voltage signal to the MCU unit; MCU unit: receives high-voltage detection data from the high-voltage detection unit, as well as communication information from the CAN and RS485 buses, conducts communication interaction, and controls output according to the fan status; Constant current source circuit: controlled by the MCU unit, outputs current to the entire vehicle system to ensure stable operation of the vehicle system.

[0031] In this embodiment, the functions of the vehicle system matching module include: 1. Realize DC side input voltage detection; 2. Communicate with the wide frequency conversion system through CAN and RS485 bus; 3. According to the operating status of the fan, control the constant current source circuit to output a maximum current of 50mA to the vehicle control system; Furthermore, the power board of the wide-band inverter includes an ADC chip, and the control board of the wide-band inverter includes a low-pass filter circuit and a gain circuit.

[0032] Furthermore, the vehicle system control module includes a voltage sensor and a current sensor. The low-pass filter circuit and the gain circuit condition the voltage signal transmitted by the voltage sensor and the current signal transmitted by the current sensor and input them into the ADC chip.

[0033] like Figure 6 As shown in the figure, the voltage / current sensor sampling circuit can be adapted to current sensors and voltage sensors. Based on the bandwidth requirements, a low-pass filter circuit and gain circuit are designed to condition the signal to the appropriate range for input to the ADC chip (analog-to-digital conversion chip).

[0034] Furthermore, the vehicle system control module includes a temperature sensor, which uses a voltage-controlled constant current source to transmit a temperature signal to an ADC chip through the temperature sensor.

[0035] like Figure 7 As shown in the figure, the temperature sensor sampling circuit adopts a voltage-controlled constant current source with an output current of 2.5mA. The signal is output to the ADC chip through an operational amplifier, gain and low-pass filtering.

[0036] Furthermore, the vehicle system control module includes a speed sensor, which transmits a speed signal to an ADC chip via a temperature sensor. Figure 8 It is the sampling circuit of speed sensor (magnetic sensor).

[0037] In this embodiment, the vehicle system matching module realizes matching connection between the wide-band inverter system and the vehicle system, thereby achieving stable operation of the system.

[0038] Vehicle system matching module control logic: fan operation communication logic.

[0039] Fan operation control logic: The vehicle system matching module collects the bus voltage and the feedback signal of the brake resistor control switch RP in real time. When the bus voltage is greater than 300VDC and the RP feedback signal changes from open to closed, it means that the vehicle brake resistor is connected and there is no fault information in the wide-range inverter. The vehicle system matching module uses the bus voltage according to the following formula: (1) Where I_out is the output current in A; Udc is the bus voltage at this time in V; k is the proportional coefficient, which is 33333.3 and is in V / A.

[0040] High sampling rate sampling According to the sampling circuit design, the calculation formula for each channel is as follows: The voltage signal sampling rate is 16 bits, and the calculation formula is as follows: (2) Vr is the actual sampling voltage; k is the sensor proportional coefficient; codev is the data read by the sampling device; VADC is the ADC chip reference voltage; GAIN is the circuit gain.

[0041] The current signal sampling rate is 16 bits, and the calculation formula is as follows: (3) Ir is the actual sampling voltage; K is the sensor proportional coefficient; Codei is the data read by the sampling device; VADC is the ADC chip reference voltage; GAIN is the circuit gain.

[0042] The temperature signal sampling rate is 12 bits, and the calculation formula is as follows: (4) T is the actual acceleration signal; a and b are coefficients; codet is the data read by the sampling device; GAIN is the circuit gain.

[0043] The speed sampling rate is 12 bits, and the calculation formula is as follows: (5) Fx is the actual square wave frequency; Fn is the actual square wave count within time t; Fx is the given frequency of the comparative square wave; Fn is the comparative square wave count within time t.

[0044] When the inverter fails, the current output of the vehicle system matching module is 0. At this time, the vehicle system reports a fan system failure and the vehicle system shuts down to ensure vehicle safety.

[0045] A control method for an AC cooling fan system of a braking resistor of a mining dump truck controls the start and stop of an AC asynchronous cooling fan through a wide-range inverter, thereby cooling the braking resistor.

[0046] Furthermore, the control logic of the wide-band inverter includes: Startup logic: The wide-range inverter system collects the bus voltage and the feedback signal of the brake resistor control switch RP in real time. During startup, when the bus voltage is greater than 300VDC and the RP feedback signal changes from open to closed, indicating that the vehicle's brake resistor is engaged, the inverter enters the working state and controls the output voltage frequency according to the bus voltage amplitude, thereby controlling the fan speed. Normal shutdown logic: When the RP feedback limit signal changes from closed to open, the inverter shuts down immediately. Then, 500 milliseconds after shutdown, the inverter starts up and controls the fan speed to run at 1000 rpm for 2 seconds to achieve delayed shutdown and enhance the cooling effect of the brake resistor. Protection shutdown logic: If the motor current, temperature, or speed of the wide-range inverter system exceeds the threshold during startup, operation, or shutdown, the fault information will be transmitted to the vehicle system matching module via CAN or 485 communication, and the system will stop working immediately to ensure equipment safety.

[0047] Specifically, the wide-band inverter input is the vehicle's intermediate DC bus voltage, and the DC voltage is converted into AC voltage through the inverter to drive the AC fan motor.

[0048] The wide range inverter control logic includes: fan start, delayed shutdown, voltage, current, temperature, speed protection, etc.

[0049] Inverter startup logic: The wide-range inverter system collects feedback signals from the bus voltage and the brake resistor control switch RP in real time. During startup, when the bus voltage is greater than 300VDC and the RP feedback signal changes from open to closed, it means that the vehicle's brake resistor is engaged. At this time, the inverter enters the working state and controls the output voltage frequency according to the amplitude of the bus voltage, thereby controlling the fan speed.

[0050] Normal shutdown logic of the inverter: The wide-range inverter system collects the bus voltage and the feedback signal of the brake resistor control switch RP in real time. During normal shutdown, the RP feedback signal changes from closed to open, indicating that the vehicle's brake resistor is not in use. At this time, the inverter enters the delayed shutdown state.

[0051] The delayed shutdown control sequence is as follows: first, when the RP feedback limit signal changes from closed to open, the inverter shuts down immediately. Then, 500 milliseconds after shutdown, the inverter starts up and controls the fan speed to run at 1000 rpm for 2 seconds, achieving delayed shutdown and enhancing the cooling effect of the brake resistor.

[0052] Inverter protection shutdown logic: If the motor current, temperature, or speed exceeds the threshold during the startup, operation, or shutdown process of the wide-range inverter system, the fault information will be transmitted to the vehicle system matching module via CAN or 485 communication, and the system will stop working immediately to ensure equipment safety.

[0053] The foregoing description is intended only to provide specific embodiments of the present invention, which will enable those skilled in the art to understand and implement 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 present invention.

[0054] It should be understood that the present invention is not limited to the above description and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A braking resistor AC cooling fan system for a mining dump truck, characterized in that: include: Wide-range inverter, vehicle system matching module and AC asynchronous cooling fan; Wide-range inverter: converts DC power into AC power to drive the motor of the AC asynchronous cooling fan; AC asynchronous cooling fan: powered by the wide-range inverter, it generates airflow to cool the brake resistor; Vehicle system matching module: interacts with the wide-band inverter to ensure power supply to the vehicle's wind turbine.

2. The AC cooling fan system for a mining dump truck brake resistor according to claim 1 is characterized in that: The wide-band inverter forms a three-level topology structure through an inverter bridge arm composed of multiple groups of power switching devices; The control circuit of the wide-band inverter includes a power board and a control board. The power board processes power circuit signals and cooperates with the inverter bridge arm to realize power conversion; the control board integrates a core control chip.

3. The AC cooling fan system for a mining dump truck brake resistor according to claim 2 is characterized in that: The control board includes an FPGA chip and a DSP chip. The FPGA chip is responsible for logic control and signal processing, and the DSP chip is used for algorithm calculation.

4. The braking resistor AC cooling fan system for a mining dump truck according to claim 1 is characterized in that: The vehicle system matching module includes a high-voltage detection unit, an MCU unit, and a constant current source circuit; High-voltage detection unit: connects to the DC bus, detects the DC side input voltage, and transmits the voltage signal to the MCU unit; MCU unit: receives high-voltage detection data from the high-voltage detection unit, as well as communication information from the CAN and RS485 buses, conducts communication interaction, and controls output according to the fan status; Constant current source circuit: controlled by the MCU unit, outputs current to the entire vehicle system to ensure power supply for the cooling fan.

5. The AC cooling fan system for a mining dump truck brake resistor according to claim 1 is characterized in that: The power board of the wide-band inverter includes an ADC chip, and the control board of the wide-band inverter includes a low-pass filter circuit and a gain circuit.

6. The braking resistor AC cooling fan system for a mining dump truck according to claim 1 is characterized in that: The vehicle system matching module includes a voltage sensor and a current sensor. The low-pass filter circuit and the gain circuit condition the voltage signal transmitted by the voltage sensor and the current signal transmitted by the current sensor and input them into the ADC chip.

7. The AC cooling fan system for a mining dump truck brake resistor according to claim 1, characterized in that: The vehicle system matching module includes a temperature sensor, which uses a voltage-controlled constant current source to transmit a temperature signal to an ADC chip through the temperature sensor.

8. The AC cooling fan system for a mining dump truck brake resistor according to claim 1, characterized in that: The vehicle system matching module includes a speed sensor, which transmits the speed signal to the ADC chip through the temperature sensor.

9. A control method for a braking resistor AC cooling fan system for a mining dump truck according to any one of claims 1 to 8, characterized in that: The start and stop of the AC asynchronous cooling fan is controlled by the wide-range inverter, thereby cooling the braking resistor.

10. The control method of the braking resistor AC cooling fan system of a mining dump truck according to claim 9, characterized in that: The control logic of the wide-band inverter includes: Startup logic: The wide-range inverter system collects the bus voltage and the feedback signal of the brake resistor control switch RP in real time. During startup, when the bus voltage is greater than 300VDC and the RP feedback signal changes from open to closed, indicating that the vehicle's brake resistor is engaged, the inverter enters the working state and controls the output voltage frequency according to the bus voltage amplitude, thereby controlling the fan speed. Normal shutdown logic: When the RP feedback limit signal changes from closed to open, the inverter shuts down immediately. Then, 500 milliseconds after shutdown, the inverter starts up and controls the fan speed to run at 1000 rpm for 2 seconds to achieve delayed shutdown and enhance the cooling effect of the brake resistor. Protection shutdown logic: If the motor current, temperature, or speed of the wide-range inverter system exceeds the threshold during startup, operation, or shutdown, the fault information will be transmitted to the vehicle system matching module via CAN or 485 communication, and the system will stop working immediately to ensure equipment safety.

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