Control circuit for speed regulation and positive and negative rotation switching of DC motor of laminator

Abstract

The utility model discloses a control circuit for speed regulation and positive and negative rotation switching of a DC motor of a laminator, which comprises an H-bridge control chip U3 integrated by field effect transistors Q1 to Q4. A first pin GND of the H-bridge control chip U3 is grounded, a second pin IN1 is the input end of PWM2, a third pin IN2 is the input end of PWM1, a fourth pin VREF is connected with a first resistor R1 and inputs reference voltage, a fifth pin VM is connected with a DC motor driving power supply and directly supplies power to the H-bridge control chip U3, a sixth pin OUT1 is connected with an inductor L3, a seventh pin ISEN is connected with a second resistor R2, an eighth pin OUT2 is connected with an inductor L2, the inductor L2 is connected with the positive electrode end of a DC motor, and the positive electrode end of the DC motor is connected with the negative electrode end of the DC motor. The inductor L3 is connected with the negative electrode end of the DC motor. The rotation speed of the DC motor is controlled by performing pulse width modulation (PWM) on an input signal, and forward and reverse rotation of the DC motor is switched.

Description

Technical Field

[0001] This disclosure relates to the field of DC motor control circuit technology, and in particular to a control circuit for speed regulation and forward / reverse switching of a DC motor in a laminating machine. Background Technology

[0002] A laminating machine typically consists of upper and lower glue rollers and a heating element. A motor drives the synchronous rotation of the rollers to apply adhesive to flat, coated items. For laminating machines with stepless speed regulation, a DC motor is used. DC motors offer stable speed control and are commonly used in equipment requiring precise speed control. In existing laminating machines with DC motors driving the rollers, the speed control function uses a traditional circuit: PWM control of a MOSFET for speed regulation, and a double-pole relay for switching between forward and reverse directions, which is costly. The double-pole relay has redundant contacts; switching between forward and reverse requires two independent sets of contacts to control the current direction. Compared to solid-state semiconductor solutions, this requires twice the contact material and a more complex structural design, and the contact life is affected by arc erosion, necessitating higher-specification models. Therefore, it is necessary to optimize and improve the speed regulation and forward / reverse switching circuits of existing DC motor-driven laminating machines. Utility Model Content

[0003] In view of this, this disclosure proposes a control circuit for speed regulation and forward / reverse switching of a DC motor in a gluing machine. Four field-effect transistors are combined together to form an H-bridge circuit, which controls the motor speed and switches the forward and reverse rotation of the DC motor by pulse width modulation (PWM) of the input signal.

[0004] According to one aspect of this disclosure, a control circuit for speed regulation and forward / reverse switching of a DC motor in a gluing machine is provided. The control circuit includes an H-bridge control chip U3 integrated with MOSFETs Q1, Q2, Q3, and Q4. Pin 1 of the H-bridge control chip U3 is grounded (GND), pin 2 (IN1) is the PWM2 input terminal, pin 3 (IN2) is the PWM1 input terminal, pin 4 (VREF) is connected to a first resistor R1 and an input reference voltage, pin 5 (VM) is connected to a DC motor drive power supply and directly powers the H-bridge control chip U3, pin 6 (OUT1) is connected to an inductor L3, pin 7 (ISEN) is connected to a second resistor R2, and pin 8 (OUT2) is connected to an inductor L2. Inductor L2 is connected to the positive terminal of the DC motor, and inductor L3 is connected to the negative terminal of the DC motor. The second resistor R2, being a 0.22Ω resistor, is connected in series in the DC motor circuit and is used for real-time monitoring of the DC motor current. Both inductors L2 and L3 are 220uH inductors, used to reduce electromagnetic interference during DC motor commutation.

[0005] In operation, a high-level duty cycle signal is input to the PWM1 input terminal, and PWM1 remains at a low level. At this time, MOSFETs Q1 and Q4 are turned on, while MOSFETs Q2 and Q3 are turned off. Current flows through MOSFET Q1 from pin 6 (OUT1) to inductor L3, the negative terminal of the DC motor, the positive terminal of the DC motor, inductor L2, MOSFET Q4, and ground. The voltage at the positive terminal of the DC motor is higher than that at the negative terminal, causing the DC motor to rotate forward. Similarly, a high-level duty cycle signal is input to the PWM2 input terminal, and PWM1 remains at a low level. At this time, MOSFETs Q2 and Q3 are turned on, while MOSFETs Q1 and Q4 are turned off. Current flows through MOSFET Q2 from pin 8 (OUT2) to inductor L2, the positive terminal of the DC motor, the negative terminal of the DC motor, inductor L3, MOSFET Q3, and ground. The voltage at the negative terminal of the DC motor is higher than that at the positive terminal, causing the DC motor to rotate in reverse. Adjusting the high-level duty cycle input to either the PWM1 or PWM2 input terminal allows for adjustment of the forward or reverse rotation speed of the DC motor.

[0006] Furthermore, a capacitor C14 is connected in parallel between pin 1 GND and pin 5 VM. The capacitor C14 is a 100μF / 25V capacitor, used for low-frequency filtering and energy storage of the power supply.

[0007] Furthermore, a capacitor C15 is connected between pin 6 OUT1 and pin 8 OUT2. The capacitor C15 is a 104 / 50V capacitor used to suppress voltage spikes.

[0008] Furthermore, inductors L2 and L3 are respectively connected in parallel between the two ends of the DC motor with a filter capacitor CY3. The filter capacitor CY3 is a 104 / 100V capacitor, which is used to filter out high-frequency noise from the VCC power supply and ensure the stability of the control signal.

[0009] Furthermore, the first resistor R1 is a 1KΩ resistor, used to limit the gate current of the field-effect transistor and prevent transient overshoot during switching.

[0010] The beneficial effects of this utility model are as follows: The speed regulation and forward / reverse switching control circuit for the DC motor of the laminating machine disclosed in this technical solution replaces the traditional circuit control scheme that uses a double-pole relay for forward / reverse switching. The traditional scheme requires the design of a double-pole relay and a field-effect transistor speed regulation circuit, as well as a relay coil drive circuit, involving transistors and driver ICs. In addition, the relay coil needs to maintain a continuous current state, resulting in high static power consumption, and the mechanical contacts of the relay have a limited lifespan. Therefore, the traditional circuit control scheme using a double-pole relay is costly.

[0011] This solution utilizes an H-bridge control chip to switch the forward and reverse rotation of a DC motor and adjust its speed by adjusting the pulse width modulation (PWM) of the input signal. It requires only an H-bridge chip integrating four MOSFETs and MOSFET gate drive resistors, eliminating the need for complex driving mechanisms. Furthermore, the MOSFETs are solid-state devices with a long lifespan, exceeding 10^9 switching cycles. Additionally, the MOSFETs experience losses only during switching, resulting in extremely low static power consumption. Therefore, this control circuit design helps reduce overall cost. Attached Figure Description

[0012] Figure 1 This is a circuit diagram for an existing DC motor control circuit that uses a double-pole relay circuit to switch the forward and reverse rotation of a DC motor and a field-effect transistor circuit to adjust the speed of a DC motor.

[0013] Figure 2 This is a schematic diagram of the circuit structure of a control circuit for speed regulation and forward / reverse switching of a DC motor, as disclosed in this utility model.

[0014] Figure 3 This is a schematic diagram of the circuit structure of Embodiment 2 of the control circuit for speed regulation and forward / reverse switching of a DC motor disclosed in this utility model.

[0015] Figure 4 This is a schematic diagram of the connection circuit between the H-bridge integrated with four field-effect transistors and the DC motor disclosed in this utility model. Detailed Implementation

[0016] The technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are also within the scope of protection of this disclosure.

[0017] Please refer to Figure 2 , Figure 4This technical solution discloses a control circuit for speed regulation and forward / reverse switching of a DC motor in a gluing machine. The control circuit includes an H-bridge control chip U3 integrated with MOSFETs Q1, Q2, Q3, and Q4. Pin 1 of the H-bridge control chip U3 is grounded (GND); pin 2 (IN1) is the PWM2 input; pin 3 (IN2) is the PWM1 input; pin 4 (VREF) is connected to a first resistor R1 and an input reference voltage; pin 5 (VM) is connected to the DC motor drive power supply and directly powers the H-bridge control chip U3; pin 6 (OUT1) is connected to an inductor L3; pin 7 (ISEN) is connected to a second resistor R2; and pin 8 (OUT2) is connected to an inductor L2. The first resistor R1 is a 1KΩ resistor used to limit the gate current of the MOSFETs and prevent transient overshoot during switching. Inductor L2 is connected to the positive terminal of the DC motor, and inductor L3 is connected to the negative terminal of the DC motor. The second resistor R2, a 0.22Ω resistor, is connected in series in the DC motor circuit and is used to monitor the DC motor current in real time. Preferably, both inductors L2 and L3 are 220uH inductors to reduce electromagnetic interference during DC motor commutation.

[0018] In operation, a high-level duty cycle signal is input to the PWM1 input terminal, and PWM1 remains at a low level. At this time, MOSFETs Q1 and Q4 are turned on, while MOSFETs Q2 and Q3 are turned off. Current flows through MOSFET Q1 from pin 6 (OUT1) to inductor L3, the negative terminal of the DC motor, the positive terminal of the DC motor, inductor L2, MOSFET Q4, and ground. The voltage at the positive terminal of the DC motor is higher than that at the negative terminal, causing the DC motor to rotate forward. Similarly, a high-level duty cycle signal is input to the PWM2 input terminal, and PWM1 remains at a low level. At this time, MOSFETs Q2 and Q3 are turned on, while MOSFETs Q1 and Q4 are turned off. Current flows through MOSFET Q2 from pin 8 (OUT2) to inductor L2, the positive terminal of the DC motor, the negative terminal of the DC motor, inductor L3, MOSFET Q3, and ground. The voltage at the negative terminal of the DC motor is higher than that at the positive terminal, causing the DC motor to rotate in reverse. Adjusting the high-level duty cycle input to either the PWM1 or PWM2 input terminal allows for adjustment of the forward or reverse rotation speed of the DC motor.

[0019] Preferably, a capacitor C14 is connected in parallel between the first pin GND and the fifth pin VM. The capacitor C14 is a 100μF / 25V capacitor, which is used for low-frequency filtering and energy storage of the power supply, such as current surges when the DC motor starts and stops, to ensure the stability of the power supply.

[0020] Preferably, a capacitor C15 is connected between pin 6 OUT1 and pin 8 OUT2. The capacitor C15 is a 104 / 50V capacitor used to suppress voltage spikes, such as absorbing back electromotive force voltage spikes generated when the DC motor commutates or the MOSFET switches, to protect the MOSFET from being damaged.

[0021] Please refer to Figure 3 The inductors L2 and L3 are respectively connected in parallel between the two ends of the DC motor and a filter capacitor CY3. The filter capacitor CY3 is a 104 / 100V capacitor, which is used to filter out high-frequency noise from the VCC power supply and ensure the stability of the control signal.

[0022] This solution utilizes the control circuit of the H-bridge control chip U3, which can be a model L9110S chip. It switches the forward and reverse rotation of the DC motor and adjusts the speed of the DC motor's forward and reverse rotation by adjusting the pulse width modulation (PWM) of the input signal. Only four integrated MOSFETs are needed in the H-bridge chip, eliminating the need for complex drive mechanisms. Furthermore, the MOSFETs are solid-state devices with a long lifespan, exceeding 10^9 switching cycles. Additionally, the MOSFETs only experience losses during switching, resulting in extremely low static power consumption. Therefore, the control circuit of this technical solution helps reduce output costs.

[0023] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A control circuit for DC motor speed regulation and forward-reverse switching of a laminator, characterized in that, The control circuit includes an H-bridge control chip U3 integrated with MOSFETs Q1, Q2, Q3, and Q4. Pin 1 of the H-bridge control chip U3 is grounded (GND), pin 2 (IN1) is the input terminal of PWM2, pin 3 (IN2) is the input terminal of PWM1, pin 4 (VREF) is connected to a first resistor R1 and an input reference voltage, pin 5 (VM) is connected to a DC motor drive power supply and directly powers the H-bridge control chip U3, pin 6 (OUT1) is connected to an inductor L3, pin 7 (ISEN) is connected to a second resistor R2, and pin 8 (OUT2) is connected to an inductor L2. The inductor L2 is connected to the positive terminal of the DC motor, and the inductor L3 is connected to the negative terminal of the DC motor. The second resistor R2 is connected in series in the DC motor circuit for real-time monitoring of the DC motor current. In operation, a high-level duty cycle signal is input to the PWM1 input terminal, and PWM1 remains at a low level. At this time, MOSFETs Q1 and Q4 are turned on, while MOSFETs Q2 and Q3 are turned off. Current flows through MOSFET Q1 from pin 6 (OUT1) to inductor L3, the negative terminal of the DC motor, the positive terminal of the DC motor, inductor L2, MOSFET Q4, and ground. The voltage at the positive terminal of the DC motor is higher than that at the negative terminal, causing the DC motor to rotate forward. Similarly, a high-level duty cycle signal is input to the PWM2 input terminal, and PWM1 remains at a low level. At this time, MOSFETs Q2 and Q3 are turned on, while MOSFETs Q1 and Q4 are turned off. Current flows through MOSFET Q2 from pin 8 (OUT2) to inductor L2, the positive terminal of the DC motor, the negative terminal of the DC motor, inductor L3, MOSFET Q3, and ground. The voltage at the negative terminal of the DC motor is higher than that at the positive terminal, causing the DC motor to rotate in reverse. Adjusting the high-level duty cycle input to either the PWM1 or PWM2 input terminal allows for adjustment of the forward or reverse rotation speed of the DC motor.

2. The control circuit for DC motor speed regulation and forward-reverse switching of a laminator according to claim 1, characterized in that, A capacitor C14 is connected in parallel between pin 1 (GND) and pin 5 (VM). The capacitor C14 is a 100μF / 25V capacitor used for low-frequency filtering and energy storage of the power supply.

3. The control circuit for DC motor speed regulation and forward-reverse switching of a laminator according to claim 1, characterized in that, A capacitor C15 is connected between pin 6 OUT1 and pin 8 OUT2. The capacitor C15 is a 104 / 50V capacitor used to suppress voltage spikes.

4. The control circuit for DC motor speed regulation and forward-reverse switching of a laminator according to claim 1, characterized in that, The inductors L2 and L3 are respectively connected in parallel between the two ends of the DC motor and a filter capacitor CY3. The filter capacitor CY3 is a 104 / 100V capacitor, which is used to filter out high-frequency noise from the VCC power supply and ensure the stability of the control signal.

5. The control circuit for DC motor speed regulation and forward-reverse switching of a laminator according to claim 1, characterized in that, The first resistor R1 is a 1KΩ resistor, used to limit the gate current of the field-effect transistor and prevent transient overshoot during switching.

6. The control circuit for DC motor speed regulation and forward-reverse switching of a laminator according to claim 1, characterized in that, The second resistor R2 is a 0.22Ω resistor.

7. The control circuit for DC motor speed regulation and forward-reverse switching of a laminator according to claim 1, characterized in that, Both inductors L2 and L3 are 220uH inductors.

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