An electromagnetic brake torque adjustment circuit

Abstract

The utility model relates to an electromagnetic brake braking torque adjusting circuit, its structure includes main control circuit, torque collection circuit, control interface circuit and electromagnet drive circuit, torque collection circuit's output and main control circuit's first signal input end connection, control interface circuit's output and main control circuit's second signal input end connection, electromagnet drive circuit's PWM signal input and main control circuit's PWM signal output meet, electromagnet drive circuit's power output and main control circuit's power input meet, the utility model discloses through torque collection circuit to main control circuit sends real -time braking torque, and the user sets up the set value of braking torque through control interface circuit, and exports PWM signal to electromagnet drive circuit in, has realized the adjustment of electromagnetic brake braking torque adjustable function.

Description

Technical Field

[0001] This utility model relates to a driving device, specifically an electromagnetic brake torque adjustment circuit. Background Technology

[0002] Electromagnetic brakes, as a key actuator that utilizes the principle of electromagnetic induction to achieve mechanical braking, are widely used in industrial transmission, intelligent equipment, transportation, and other fields. Their technological development is deeply intertwined with the evolution of industrial automation and intelligence. The device driving the electromagnetic brake supports two fixed operating states: "power on / power off" or "power on / power off".

[0003] This traditional method of driving electromagnetic brakes was designed based on the simple control needs of early industrial scenarios. As industrial technology upgrades towards automation and intelligence, the technical shortcomings of traditional electromagnetic brakes have gradually become apparent. The torque is not adjustable and cannot meet the current market's intelligent needs. Utility Model Content

[0004] The purpose of this invention is to provide an electromagnetic brake torque adjustment circuit to solve the problem that existing drive devices for electromagnetic brakes cannot adjust the torque.

[0005] The technical solution of this utility model is as follows: An electromagnetic brake torque adjustment circuit includes a main control circuit, a torque acquisition circuit, a control interface circuit, and an electromagnet drive circuit. The output terminal of the torque acquisition circuit is connected to the first signal input terminal of the main control circuit, and the output terminal of the control interface circuit is connected to the second signal input terminal of the main control circuit. The PWM signal input terminal of the electromagnet drive circuit is connected to the PWM signal output terminal of the main control circuit, and the power output terminal of the electromagnet drive circuit is connected to the power input terminal of the main control circuit.

[0006] Furthermore, the structure of the main control circuit is as follows: pins 5 and 6 of chip U7 are connected to the crystal oscillator and its peripheral circuits; the power input terminal and ground terminal of chip U7 are connected through a filter capacitor; pin 7 of chip U7 has two inputs, one of which is connected to the power supply through resistor R17, and the other is grounded through capacitor C23; pins 20 and 44 of chip U7 are both grounded through resistors.

[0007] Furthermore, the structure of the control interface circuit is as follows: pin 1 of the serial-to-RS485 interface chip U4 is connected to pin 22 of chip U7; pins 2 and 3 of the serial-to-RS485 interface chip U4 are both connected to pin 25 of chip U7; pin 21 of the serial-to-RS485 interface chip U4 is connected to pin 21 of chip U7; pin 7 of the serial-to-RS485 interface chip U4 has two outputs, one connected to ground via resistor R3, and the other connected to pin 2 of terminal CN2 via resistor R4; pin 6 of the serial-to-RS485 interface chip U4 has two outputs, one connected to ground via resistor R7, and the other connected to pin 1 of terminal CN2 via resistor R5; pin 2 of terminal CN2 has two inputs, one connected to ground via diode D8, and the other connected to the power supply via diode D7; pin 1 of terminal CN2 has two inputs, one connected to ground via diode D9, and the other connected to the power supply via diode D10; diodes D7 and D9 are connected via resistor R6.

[0008] Furthermore, the electromagnet driving circuit includes a first driving circuit, a second driving circuit, and a third driving circuit; the input terminal of the first driving circuit is connected to the output terminal of the second driving circuit, the PWM signal input terminal of the second driving circuit is connected to the PWM signal output terminal of the main control circuit, and the output terminal of the third driving circuit is connected to the 3.3V input terminal of the main control circuit.

[0009] Furthermore, the structure of the first driving circuit is as follows: pin 1 of terminal J1 is connected to two inputs, one to pin 2 of transformer T1 and the other to pin 3 of rectifier bridge B1; pin 2 of terminal J1 is connected to three inputs, one to pin 4 of transformer T1, two to pin 1 of terminal J1 via varistor VR1, and the third to pin 1 of rectifier bridge B1; pin 2 of rectifier bridge B1 is connected to two outputs, one of which is connected to pin 4 of rectifier bridge B1 via capacitor C1. The second path is connected to the drain of MOSFET Q5; pin 4 of rectifier bridge B1 is connected to pin 2 of terminal J2; the source of MOSFET Q5 has two outputs, one of which is connected to the gate of MOSFET Q5 through resistor R18, and the other is connected to pin 1 of terminal J2; pin 1 of terminal J2 is connected to pin 2 of terminal J2 through resistor R20 and diode D3, and pin 2 of terminal J2 is grounded; the gate of MOSFET Q5 is connected to the output of the second drive circuit.

[0010] Furthermore, the structure of the second driving circuit is as follows: the 18V output terminal of transformer T1 is connected to the input terminal of rectifier bridge B2; pins 2 and 4 of rectifier bridge B2 are connected through capacitor C6; pin 2 of rectifier bridge B2 is connected to pin 1 of buck converter chip U2; pin 4 of rectifier bridge B2 is connected to pin 2 of buck converter chip U2; pins 2 and 3 of buck converter chip U2 are connected through capacitor C6; pin 2 of buck converter chip U2 is connected to pin 5 of isolation chip U3 and grounded; pin 3 of buck converter chip U2 is connected to pin 8 of isolation chip U3; pins 6 and 7 of isolation chip U3 are both connected to the input terminal of the first driving circuit; pin 3 of isolation chip U3 is connected to the collector of transistor Q2; and the base of transistor Q2 is connected to the PWM signal output terminal of the main control circuit through resistor R21.

[0011] Furthermore, the structure of the third driving circuit is as follows: the 8V output terminal of transformer T1 is connected to the input terminal of rectifier bridge B3; pins 2 and 4 of rectifier bridge B3 are connected through capacitor C10; pin 2 of rectifier bridge B3 is connected to pin 1 of buck chip U5; pin 4 of rectifier bridge B3 is connected to pin 2 of buck chip U5; pins 2 and 3 of buck chip U5 are connected through capacitor C8; pin 2 of buck chip U5 is connected to pin 1 of buck chip U6 and grounded; pin 3 of buck chip U5 is connected to pin 8 of buck chip U6; pins 2 and 4 of buck chip U6 are both connected to the 3.3V input terminal of the main control circuit through a filter circuit composed of capacitors C9 and C11.

[0012] Furthermore, the structure of the torque acquisition circuit is as follows: pin 1 of terminal CN1 is connected to both a 5V power supply and ground, with an electrolytic capacitor C26 connected between pin 1 and ground; pins 2 and 6 are both grounded; pin 2 of operational amplifier U1 is connected to pin 3 of terminal CN1 via a filter circuit composed of resistor R26 and capacitor C4; pin 3 of operational amplifier U1 is connected to pin 4 of terminal CN1 via a filter circuit composed of resistor R13 and capacitor C27; a capacitor C5 is connected between pins 2 and 3 of operational amplifier U1; a resistor R25 is connected between pins 2 and 6 of operational amplifier U1; pin 7 of operational amplifier U1 has four outputs, one connected to a 5V power supply, two of which are connected to a 5V power supply, and two of which are connected to a 5V power supply via a filter circuit composed of resistor R26 and capacitor C4. The filter circuit composed of electrolytic capacitor C24 and capacitor C2 is grounded. Three paths are connected to pin 6 of operational amplifier U1 via diode D1. The fourth path outputs a 1.65V voltage through a voltage divider circuit composed of resistor R23 and sliding rheostat R24, and then connects to pin 3 of operational amplifier U1 via resistor R31. Diode D2 is connected between pins 4 and 6 of operational amplifier U1. Pin 6 of operational amplifier U1 is connected to the first signal input terminal of the main control circuit through a four-stage low-pass filter circuit composed of resistors R27, R28, R29, R30, capacitors C31, C28, C29, and C30, and a filter circuit composed of resistor R9 and capacitor C25.

[0013] This invention acquires the braking torque from a force sensor via a torque acquisition circuit. The torque acquisition circuit amplifies the acquired signal, filters out unwanted noise, and sends the real-time braking torque to the main control circuit. The user sets the braking torque setpoint through the control interface circuit and adjusts it using an existing PID algorithm, outputting a PWM signal to the electromagnet drive circuit. The electromagnet drive circuit amplifies the control signal and outputs it to the electromagnetic brake, thus realizing the adjustable braking torque function of the electromagnetic brake. This invention can be applied to electromagnetic brake structures, solving the problems of limited drive device functionality and non-adjustable braking torque in existing electromagnetic brakes. Compared with existing drive devices, this invention features high intelligence, high integration, and refined control, and can be integrated with the Internet of Things to achieve more meaningful application scenarios.

[0014] This invention allows for the arbitrary setting of the braking torque parameters of the electromagnetic brake according to different working conditions, scenarios, and operating sequences. The torque is continuously adjustable, with a short response time and low power consumption, enabling the brake to operate at the optimal braking torque. This reduces energy consumption, mechanical impact, and friction pad wear, while also increasing the overall service life of the machine, lowering maintenance costs, reducing electromagnetic brake operating noise, and providing users with a better experience. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the principle of this utility model.

[0016] Figure 2 This is the circuit diagram of the main control circuit.

[0017] Figure 3 This is the circuit diagram of the control interface circuit.

[0018] Figure 4 This is the circuit diagram of the torque acquisition circuit.

[0019] Figure 5 This is a circuit diagram of an electromagnet drive circuit. Detailed Implementation

[0020] The present invention will now be described in further detail with reference to the accompanying drawings.

[0021] like Figure 1As shown, this utility model includes a main control circuit, a torque acquisition circuit, a control interface circuit, and an electromagnet drive circuit. The output terminal of the torque acquisition circuit is connected to the first signal input terminal of the main control circuit, and the input terminal of the torque acquisition circuit is connected to a force sensor to acquire the signal from the force sensor and amplify the signal for input to the main control circuit. The output terminal of the control interface circuit is connected to the second signal input terminal of the main control circuit, and the user sets the braking torque setting value through the control interface circuit. The PWM signal input terminal of the electromagnet drive circuit is connected to the PWM signal output terminal of the main control circuit, and the main control chip outputs the corresponding power through the output PWM signal. The power output terminal of the electromagnet drive circuit is connected to the power input terminal of the main control circuit, and the electromagnet drive circuit provides power to the main control circuit through the power output terminal. The output terminal of the electromagnet drive circuit is connected to an electromagnetic brake, and the electromagnet drive circuit amplifies the drive signal and outputs it to the electromagnetic brake.

[0022] Force sensors include, but are not limited to, S-type tension / compression sensors, which are fixed on the electromagnetic brake to collect the braking torque of the electromagnetic brake.

[0023] like Figure 2 As shown, the main control circuit chip U7 in this invention can be implemented using an MCU microcontroller, which can receive user commands and generate control signals. The following explanation uses an STM32F103C8T6 as an example.

[0024] Pins 5 and 6 of chip U7 are connected to the crystal oscillator and its peripheral circuitry. Pin 5 of chip U7 is grounded through capacitor C12, and pin 6 is grounded through capacitor C15. Crystal oscillator XT1 is connected between pins 5 and 6, and resistor R11 is connected in parallel across the two ends of crystal oscillator XT1.

[0025] The power input terminal and ground terminal of chip U7 are connected through a filter capacitor. Pins 8, 23, 35, and 47 of chip U7 are all grounded, while pins 9, 24, 26, and 48 are all connected to a 3.3V power supply. A capacitor C13 is connected between pins 8 and 9, with a capacitor C14 connected in parallel across C13. A capacitor C19 is connected between pins 23 and 24, with a capacitor C20 connected in parallel across C19. A capacitor C17 is connected between pins 35 and 36, with a capacitor C18 connected in parallel across C17. A capacitor C21 is connected between pins 47 and 48, with a capacitor C22 connected in parallel across C21. Pin 7 of chip U7 has two inputs: one connected to a 3.3V power supply through resistor R17, and the other grounded through capacitor C23. Resistor R17 and capacitor C23 form the reset circuit of chip U7, providing a reset function when chip U7 is powered on.

[0026] Pin 20 of chip U7 is grounded through resistor R16, and pin 44 is grounded through resistor R14. Pins 20 and 44 control the operating mode of the chip after power-on.

[0027] Pin 14 of chip U7 is connected to a 3.3V power supply via indicator light LE1 and resistor R15.

[0028] Pin 11 of chip U7 serves as the first signal input terminal of the main control circuit, connected to the output terminal of the torque acquisition circuit, receiving the signal from the force sensor (i.e., real-time braking torque). Pins 21, 22, and 25 of chip U7 serve as the second signal input terminals of the main control circuit, connected to the control interface circuit. The main control circuit requires a 3.3V power supply as its power input terminal, connected to the power output terminal of the third drive circuit of the electromagnet drive circuit.

[0029] The JTAG1 terminal block provides a download interface and simulation debugging function for the U7 chip. Pins 1 and 2 of the terminal block are connected through resistor R8, with pin 1 connected to a 3.3V power supply; pins 3 and 4 are connected through resistor R12, with pin 4 grounded.

[0030] An electromagnetic brake consists of an electromagnet, a brake spring, an armature, and friction pads. When the output power of the electromagnet drive circuit decreases, the attraction force of the electromagnet on the armature decreases. The pressure of the brake spring on the armature causes the armature to move towards the friction pad, increasing the normal force of the armature on the friction pad. With a constant coefficient of friction, increasing the normal force of the friction pad increases the friction between the friction pad and the contact surface, thereby increasing the braking torque of the electromagnetic brake. Conversely, when the output power of the electromagnet drive circuit increases, the attraction force of the electromagnet on the armature further increases, increasing the pressure of the armature on the brake spring, causing the armature to move towards the electromagnet. This reduces the normal force of the armature on the friction pad. With a constant coefficient of friction, reducing the normal force of the friction pad reduces the friction between the friction pad and the contact surface, thereby reducing the braking torque of the electromagnetic brake.

[0031] The main control circuit simultaneously receives the real-time braking torque from the torque acquisition circuit and the user-inputted braking torque setpoint. The main control circuit executes the above steps using the PID algorithm in chip U7, causing the brake torque to reach a new equilibrium state, thus realizing the adjustable torque function of the electromagnetic brake. The PID algorithm is a classic feedback control algorithm that achieves precise control of the controlled object through the organic combination of proportional, integral, and derivative components. This algorithm calculates the corresponding control quantity based on the deviation between the system setpoint and the actual output value, gradually bringing the system output closer to the setpoint.

[0032] The PID control algorithm first calculates the deviation e between the torque value SP acquired by the torque acquisition circuit and the setpoint PV given by the user in the control interface circuit, i.e., e = SP – PV. The proportional control link generates control action proportionally to the magnitude of the current deviation: P_out = Kp × e, where Kp is the proportional coefficient. The integral control link generates control action based on the integral of the deviation: I_out = Ki × ∫edt, where Ki is the integral time constant. The derivative control link generates control action based on the rate of change of the deviation: D_out = Kd × de / dt, where Kd is the derivative time constant. The final output is the weighted sum of the proportional, integral, and derivative terms: output = P_out + I_out + D_out.

[0033] like Figure 3 As shown, the control interface circuit mainly consists of a serial-to-RS485 interface chip U4 and a terminal block CN2. The second signal input terminal of the main control circuit includes pins 21, 22, and 25 of chip U7. Pin 1 of the serial-to-RS485 interface chip U4 is connected to pin 22 of chip U7 to receive data transmitted by the user through the RS485 interface; pins 2 and 3 of the serial-to-RS485 interface chip U4 are both connected to pin 25 of chip U7 to control the input / output direction of chip U4; pin 21 of the serial-to-RS485 interface chip U4 is connected to pin 21 of chip U7 to send data.

[0034] Pin 7 of the serial-to-RS485 interface chip U4 has two outputs: one connected to ground via resistor R3, and the other connected to pin 2 of terminal CN2 via resistor R4. Pin 6 of the same chip has two outputs: one connected to ground via resistor R7, and the other connected to pin 1 of terminal CN2 via resistor R5. Resistors R3 and R7 are used to stabilize the differential lines A and B of the RS485 interface to prevent external interference. Resistors R4 and R5 are connected in series on lines A and B for impedance matching to prevent signal reflection from damaging the chip. Resistor R6 tightens the bus voltage level when lines A and B are idle.

[0035] Pin 2 of terminal block CN2 has two inputs: one connected to ground via diode D8, and the other connected to power via diode D7. Pin 1 of terminal block CN2 also has two inputs: one connected to ground via diode D9, and the other connected to power via diode D10. Diodes D7 and D9 are connected together via resistor R6. The user communicates with the main control chip through the CN2 interface to control the braking torque.

[0036] like Figure 4As shown, the torque acquisition circuit mainly consists of terminal CN1 and operational amplifier U1. Terminal CN1 is connected to the force sensor of the brake to acquire the signal from the force sensor. Pin 1 of terminal CN1 has two inputs: one is connected to a 5V power supply to power the force sensor, and the other is connected to protective ground via electrolytic capacitor C26. The positive terminal of electrolytic capacitor C26 is connected to the 5V power supply. Pin 2 is connected to analog ground, and pin 6 is also connected to protective ground. Pin 2 of operational amplifier U1 is connected to pin 3 of terminal CN1 via resistor R26, and to analog ground via capacitor C4. Pin 3 of operational amplifier U1 is connected to pin 4 of terminal CN1 via resistor R13, and to analog ground via capacitor C27. Capacitor C5 is connected between pins 2 and 3 of operational amplifier U1. A filter circuit composed of resistors R26 and R13, capacitors C4, C5, and C27 prevents noise interference. The signal after filtering is input to pins 2 and 3 of operational amplifier U1.

[0037] A resistor R25 is connected between pins 2 and 6 of operational amplifier U1. Pin 7 of operational amplifier U1 has four outputs: one is connected to a 5V power supply; the second is connected to analog ground via capacitor C2, with an electrolytic capacitor C24 connected in parallel across C2, and the positive terminal of C24 connected to the 5V power supply; the third is connected to pin 6 of operational amplifier U1 via diode D1; and the fourth outputs a 1.65V voltage through a voltage divider circuit consisting of resistor R23 and a variable resistor R24, which then connects to pin 3 of operational amplifier U1 via resistor R31. One fixed terminal of the variable resistor R24 ​​is connected to resistor R23, while the sliding terminal and the other fixed terminal are connected to analog ground. A capacitor C3 is also connected in parallel across the variable resistor R24. Diodes D4 and D6 prevent overvoltage from burning out the microcontroller pins. The 1.65V voltage divided by resistor R1 and variable resistor R2 provides a 1.65V bias voltage to operational amplifier U1 through resistor R14. Capacitor C3 provides bias voltage filtering to prevent power supply fluctuations and interference with the op-amp signal output. Electrolytic capacitors C24 and C2 filter out noise from the DC 5V power supply to prevent interference with the op-amp chip.

[0038] Pin 6 of operational amplifier U1 is split into two outputs via resistors R27, R28, R29, and R30. One output is connected to pin 6 of operational amplifier U1 via diode D2, with the cathode of diode D2 connected to the anode of diode D1. Pin 4 of operational amplifier U1 is connected to analog ground. One end of capacitor C28 is connected to the midpoint between resistors R27 and R28, one end of capacitor C29 is connected to the midpoint between resistors R28 and R29, one end of capacitor C30 is connected to the midpoint between resistors R29 and R30, and one end of capacitor C31 is connected to the other end of resistor R30. The other ends of capacitors C28, C29, C30, and C31 are all connected to pin 4 of operational amplifier U1. The other output is connected to the first signal input terminal of the main control circuit, pin 11 of chip U7, via resistor R9. Resistor R9 is also connected to ground via capacitor C25.

[0039] Operational amplifier U1 amplifies the differential signal by 114.68 times and outputs it through pin 6 to a 4-stage low-pass filter circuit consisting of resistors R27, R28, R29, R30, capacitors C31, C28, C29, and C30.

[0040] like Figure 5 As shown, the electromagnet driving circuit includes a first driving circuit, a second driving circuit, and a third driving circuit. The input terminal of the first driving circuit is connected to the output terminal of the second driving circuit. The second driving circuit drives the switching of the MOS transistor Q5 of the first driving circuit. The PWM signal input terminal of the second driving circuit is connected to the PWM signal output terminal of the main control circuit. The second driving circuit receives the PWM signal output by the main control circuit. The output terminal of the third driving circuit is connected to the 3.3V input terminal of the main control circuit. The third driving circuit provides 3.3V power to the main control circuit.

[0041] The first drive circuit mainly consists of terminal block J1, rectifier bridge B1, MOSFET Q5, and terminal block J2. Pin 1 of terminal block J1 has two inputs: one is the power input interface with an input voltage of AC220V, connected to pin 2 of transformer T1 and pin 3 of rectifier bridge B1; pin 2 of terminal block J1 has three inputs: one is connected to pin 4 of transformer T1, two are connected to pin 1 of terminal block J1 via varistor VR1 to prevent surge current damage to components, and the third is connected to pin 1 of rectifier bridge B1; pin 2 of rectifier bridge B1 has two outputs: one is connected to pin 4 of rectifier bridge B1 via electrolytic capacitor C1, and the other is connected to the drain of MOSFET Q5. After rectification by rectifier bridge B1 and filtering by capacitor C1, a DC310V voltage is output to the drain of MOSFET Q5; pin 4 of rectifier bridge B1 and terminal block J2... Pins 2 of J2 are connected together. The source of MOSFET Q5 has two outputs: one is connected to the gate of MOSFET Q5 through resistor R18 to accelerate the turn-off time of MOSFET Q5, thereby reducing the heat generated by MOSFET Q5; the other is connected to pin 1 of terminal J2, and the output of terminal J2 goes to the brake. Pin 1 of terminal J2 is connected to pin 2 of terminal J2 through resistor R20 and diode D3, and pin 2 of terminal J2 is grounded. Resistor R20 and diode D3 are connected in series to the output of the drive circuit to absorb the reverse voltage generated by the load (i.e., the electromagnetic brake) when the MOSFET is turned off. The gate of MOSFET Q5 is connected to the output of the second drive circuit. The gate of MOSFET Q5 is the input of the first drive circuit.

[0042] The second drive circuit is mainly composed of rectifier bridge B2, step-down chip U2 and isolation chip U3. Transformer T1 has the functions of stepping down and isolating. Transformer T1 outputs two voltages, AC18V and AC8V respectively.

[0043] The 18V output terminal of transformer T1 is connected to the input terminal of rectifier bridge B2. Pin 6 of transformer T1 is connected to pin 1 of rectifier bridge B2, and pin 7 of transformer T1 is connected to pin 3 of rectifier bridge B2. Pins 2 and 4 of rectifier bridge B2 are connected through electrolytic capacitor C7. Pin 2 of rectifier bridge B2 is connected to pin 1 of step-down chip U2, and pin 4 of rectifier bridge B2 is connected to pin 2 of step-down chip U2. The AC 18V is filtered by rectifier bridge B2 and capacitor C7 to generate DC 25V output to step-down chip U2.

[0044] Pins 2 and 3 of the buck converter U2 are connected via electrolytic capacitor C6. Pin 2 of buck converter U2 is connected to pin 5 of isolation chip U3 and grounded. Pin 3 of buck converter U2 is connected to pin 8 of isolation chip U3. Buck converter U2 reduces the DC 25V voltage to DC 15V, and the DC 15V voltage is filtered by capacitor C6 to power isolation chip U3. Pins 6 and 7 of isolation chip U3 are both connected to the input terminals of the first drive circuit, driving the switch of MOSFET Q5. Pin 3 of isolation chip U3 is connected to the collector of transistor Q2, and the base of transistor Q2 is connected to the PWM signal output terminal of the main control circuit, i.e., pin 15 of chip U7, through resistor R21. Pin 2 of isolation chip U3 is connected to a 5V power supply through resistor R22. Chip U7 drives MOSFET Q5 through transistor Q2 and isolation chip U3, thereby realizing power output control.

[0045] The third drive circuit mainly consists of a rectifier bridge B3, a step-down chip U5, and a step-down chip U6. The 8V output terminal of transformer T1 is connected to the input terminal of rectifier bridge B3, pin 9 of transformer T1 is connected to pin 1 of rectifier bridge B3, and pin 10 of transformer T1 is connected to pin 3 of rectifier bridge B3. The AC 8V voltage output from transformer T1 is rectified by rectifier bridge B3 and filtered by capacitor C10, outputting DC 11V voltage to step-down chip U5. Pins 2 and 4 of rectifier bridge B3 are connected through electrolytic capacitor C10. Pin 2 of rectifier bridge B3 is connected to pin 1 of buck converter chip U5, and pin 4 of rectifier bridge B3 is connected to pin 2 of buck converter chip U5. Pins 2 and 3 of buck converter chip U5 are connected through electrolytic capacitor C8. Pin 2 of buck converter chip U5 is connected to pin 1 of buck converter chip U6 and grounded. Pin 3 of buck converter chip U5 is connected to pin 8 of buck converter chip U6. After pins 2 and 4 of buck converter chip U6 are connected, they pass through a filter circuit composed of capacitor C9 and polarized capacitor C11 and are connected to the 3.3V input terminal of the main control circuit. The positive terminal of polarized capacitor C11 is connected to pins 2 and 4 of buck converter chip U6, and the negative terminal is grounded. Capacitor C9 is connected in parallel across polarized capacitor C11. The step-down chip U5 steps down the DC11V voltage to DC5V, and then filters it through capacitor C8 before outputting it to the step-down chip U6. The step-down chip U6 converts the voltage to DC3.3V and then filters it through capacitors C11 and C9 to power chip U7.

[0046] This invention sets the braking torque of the brake and inputs it into the chip U7 of the main control circuit through the control interface circuit. The chip U7 of the main control circuit calculates and outputs a PWM signal to control the drive circuit to output the corresponding power. After the brake is applied, the braking torque is transmitted to the torque acquisition circuit through the force sensor. The torque acquisition circuit amplifies and filters the torque before outputting it to the chip U7, achieving a closed-loop effect so that the brake reaches the set value of the braking torque set by the user.

Claims

1. A braking torque adjustment circuit for an electromagnetic brake, characterized in that, It includes a main control circuit, a torque acquisition circuit, a control interface circuit, and an electromagnet drive circuit; the output terminal of the torque acquisition circuit is connected to the first signal input terminal of the main control circuit, and the output terminal of the control interface circuit is connected to the second signal input terminal of the main control circuit; the PWM signal input terminal of the electromagnet drive circuit is connected to the PWM signal output terminal of the main control circuit, and the power output terminal of the electromagnet drive circuit is connected to the power input terminal of the main control circuit.

2. The electromagnetic brake torque adjustment circuit according to claim 1, characterized in that, The main control circuit is structured as follows: pins 5 and 6 of chip U7 are connected to the crystal oscillator and its peripheral circuitry; the power input terminal and ground terminal of chip U7 are connected through a filter capacitor; pin 7 of chip U7 has two inputs, one connected to the power supply through resistor R17 and the other connected to ground through capacitor C23; pins 20 and 44 of chip U7 are both grounded through resistors.

3. The electromagnetic brake torque adjustment circuit according to claim 2, characterized in that, The control interface circuit is structured as follows: pin 1 of the serial-to-RS485 interface chip U4 is connected to pin 22 of chip U7; pins 2 and 3 of the serial-to-RS485 interface chip U4 are both connected to pin 25 of chip U7; pin 21 of the serial-to-RS485 interface chip U4 is connected to pin 21 of chip U7; pin 7 of the serial-to-RS485 interface chip U4 has two outputs, one connected to ground via resistor R3, and the other connected to pin 2 of terminal CN2 via resistor R4; pin 6 of the serial-to-RS485 interface chip U4 has two outputs, one connected to ground via resistor R7, and the other connected to pin 1 of terminal CN2 via resistor R5; pin 2 of terminal CN2 has two inputs, one connected to ground via diode D8, and the other connected to the power supply via diode D7; pin 1 of terminal CN2 has two inputs, one connected to ground via diode D9, and the other connected to the power supply via diode D10. Diodes D7 and D9 are connected through resistor R6.

4. The electromagnetic brake torque adjustment circuit according to claim 1, characterized in that, The electromagnet driving circuit includes a first driving circuit, a second driving circuit, and a third driving circuit; the input terminal of the first driving circuit is connected to the output terminal of the second driving circuit, the PWM signal input terminal of the second driving circuit is connected to the PWM signal output terminal of the main control circuit, and the output terminal of the third driving circuit is connected to the 3.3V input terminal of the main control circuit.

5. The electromagnetic brake torque adjustment circuit according to claim 4, characterized in that, The structure of the first driving circuit is as follows: pin 1 of terminal J1 is connected to two inputs, one to pin 2 of transformer T1 and the other to pin 3 of rectifier bridge B1; pin 2 of terminal J1 is connected to three inputs, one to pin 4 of transformer T1, two to pin 1 of terminal J1 via varistor VR1, and the third to pin 1 of rectifier bridge B1; pin 2 of rectifier bridge B1 is connected to two outputs, one to pin 4 of rectifier bridge B1 via capacitor C1, and the other to the drain of MOSFET Q5; pin 4 of rectifier bridge B1 is connected to pin 2 of terminal J2; the source of MOSFET Q5 is connected to two outputs, one to the gate of MOSFET Q5 via resistor R18, and the other to pin 1 of terminal J2; pin 1 of terminal J2 is connected to pin 2 of terminal J2 via resistor R20 and diode D3, and pin 2 of terminal J2 is grounded; the gate of MOSFET Q5 is connected to the output of the second driving circuit.

6. The electromagnetic brake torque adjustment circuit according to claim 4, characterized in that, The structure of the second driving circuit is as follows: the 18V output terminal of transformer T1 is connected to the input terminal of rectifier bridge B2; pins 2 and 4 of rectifier bridge B2 are connected through capacitor C6; pin 2 of rectifier bridge B2 is connected to pin 1 of buck chip U2; pin 4 of rectifier bridge B2 is connected to pin 2 of buck chip U2; pins 2 and 3 of buck chip U2 are connected through capacitor C6; pin 2 of buck chip U2 is connected to pin 5 of isolation chip U3 and grounded; pin 3 of buck chip U2 is connected to pin 8 of isolation chip U3; pins 6 and 7 of isolation chip U3 are both connected to the input terminal of the first driving circuit; pin 3 of isolation chip U3 is connected to the collector of transistor Q2; the base of transistor Q2 is connected to the PWM signal output terminal of the main control circuit through resistor R21.

7. The electromagnetic brake torque adjustment circuit according to claim 4, characterized in that, The structure of the third drive circuit is as follows: the 8V output terminal of transformer T1 is connected to the input terminal of rectifier bridge B3; pins 2 and 4 of rectifier bridge B3 are connected through capacitor C10; pin 2 of rectifier bridge B3 is connected to pin 1 of buck chip U5; pin 4 of rectifier bridge B3 is connected to pin 2 of buck chip U5; pins 2 and 3 of buck chip U5 are connected through capacitor C8; pin 2 of buck chip U5 is connected to pin 1 of buck chip U6 and grounded; pin 3 of buck chip U5 is connected to pin 8 of buck chip U6; pins 2 and 4 of buck chip U6 are both connected to the 3.3V input terminal of the main control circuit through a filter circuit composed of capacitors C9 and C11.

8. The electromagnetic brake torque adjustment circuit according to claim 1, characterized in that, The torque acquisition circuit is structured as follows: pin 1 of terminal CN1 is connected to both a 5V power supply and ground, with an electrolytic capacitor C26 connected between pin 1 and ground; pins 2 and 6 are both grounded; pin 2 of operational amplifier U1 is connected to pin 3 of terminal CN1 via a filter circuit consisting of resistor R26 and capacitor C4; pin 3 of operational amplifier U1 is connected to pin 4 of terminal CN1 via a filter circuit consisting of resistor R13 and capacitor C27; a capacitor C5 is connected between pins 2 and 3 of operational amplifier U1; a resistor R25 is connected between pins 2 and 6 of operational amplifier U1; pin 7 of operational amplifier U1 has four outputs, one connected to a 5V power supply, two connected to an electrolytic capacitor C26, and two connected to a 5V power supply. The filter circuit composed of capacitors C24 and C2 is grounded. Three paths are connected to pin 6 of operational amplifier U1 via diode D1. The fourth path outputs a 1.65V voltage through a voltage divider circuit consisting of resistor R23 and sliding rheostat R24, and then connects to pin 3 of operational amplifier U1 via resistor R31. Diode D2 is connected between pins 4 and 6 of operational amplifier U1. Pin 6 of operational amplifier U1 is connected to the first signal input terminal of the main control circuit through a four-stage low-pass filter circuit consisting of resistors R27, R28, R29, R30, capacitors C31, C28, C29, and C30, and a filter circuit consisting of resistor R9 and capacitor C25.

Images