A speed control system and method for a non-locked motor

Abstract

The application discloses a speed control system and method of a non-self-locking motor, and belongs to the field of motor speed regulation. The application is applied to providing initial power for a motor, and power provided by load gravity or motor inertia after the motor is powered off, and the system comprises a power supply, a controller, an H-bridge driving module, a double-way relay module and a non-self-locking motor. The controller is connected with the H-bridge driving module and the double-way relay module respectively, and is used for driving the H-bridge driving module and the double-way relay module. The output end of the H-bridge driving module is connected with the non-self-locking motor through the double-way relay module. The power supply is connected with the H-bridge driving module. The application realizes speed control of the non-self-locking motor, especially speed control after power-off.

Description

Technical Field

[0001] This invention belongs to the field of motor speed control. Specifically, this invention relates to a speed control system and method for a non-self-locking motor. Background Technology

[0002] Controlling the speed of non-self-locking motors (such as DC motors, stepper motors, etc.) after power failure usually requires active braking or energy management.

[0003] Existing technologies often adjust the speed of the motor when it is powered on. For example, publication number CN215340781U, published on 2021-12-28, entitled "Motor Speed ​​Control Board Based on Internet of Things Communication," discloses a motor speed control board based on Internet of Things communication. This motor speed control board includes a control module, which is connected to a control panel and a motor speed control drive module. The control module is connected to a host controller via a communication module. The motor speed control drive module includes a zero-crossing detection circuit and a thyristor control circuit. The zero-crossing detection circuit is connected to the control module, and the thyristor control circuit is connected to the control module via an isolation circuit.

[0004] However, like most existing technologies, this published document does not address speed control after the motor is powered off. This is extremely disadvantageous for scenarios where the motor provides initial power, and power is provided by load gravity or motor inertia after power failure. Therefore, this invention proposes a speed control system and method for a non-self-locking motor. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of the prior art and proposes a speed control system and method for a non-self-locking motor to achieve the following objectives: to realize speed control of a non-self-locking motor, especially speed control after power failure.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a speed control system for a non-self-locking motor, applied to scenarios where the motor provides initial power and, after power failure, the motor is powered by the load gravity or motor inertia. The system includes a power supply, a controller, an H-bridge drive module, a dual-channel relay module, and a non-self-locking motor. The controller is connected to both the H-bridge drive module and the dual-channel relay module, and is used to drive both modules. The output of the H-bridge drive module is connected to the non-self-locking motor through the dual-channel relay module. The power supply is connected to the H-bridge drive module.

[0007] Preferably, the H-bridge drive module includes an H-bridge drive circuit, which comprises four bridge arms consisting of four transistors Q1, Q2, Q3, and Q4, each with a built-in freewheeling diode. A terminal M01_A_SH1 between the second terminal of transistor Q1 and the first terminal of transistor Q2 is connected to the dual-channel relay module; a terminal M01_A_SH2 between the second terminal of transistor Q3 and the first terminal of transistor Q4 is connected to the dual-channel relay module; a terminal between the first terminal of transistor Q1 and the first terminal of transistor Q3 is connected to the positive power supply A_VDH1; a terminal between the second terminal of transistor Q2 and the second terminal of transistor Q4 is grounded; and the control terminals of the four transistors Q1, Q2, Q3, and Q4 are respectively connected to the four signal terminals A_GH1, A_GL1, A_GH2, and A_GL2 of the controller.

[0008] Preferably, an RC series circuit is connected in parallel between the first and second terminals of transistors Q1, Q2, Q3, and Q4.

[0009] Preferably, the H-bridge drive circuit further includes capacitors C5 and C6, wherein capacitors C5 and C6 are connected in parallel, with one end grounded and the other end connected to the positive terminal A_VDH1 of the power supply.

[0010] Preferably, transistors Q1, Q2, Q3, and Q4 are all NMOS transistors, and correspondingly, the first terminal of transistors Q1, Q2, Q3, and Q4 is the drain, the second terminal is the source, and the control terminal is the gate.

[0011] Preferably, the dual-channel relay module includes dual-channel relays and a power resistor R5, wherein the output terminal of the H-bridge drive module is connected to the non-self-locking motor through the first channel of the dual-channel relay; the power resistor R5 is connected to the non-self-locking motor through the second channel of the dual-channel relay; the control coils of the first and second channels of the dual-channel relay are connected in parallel, with one end grounded and the other end connected to the signal terminal A_k1,2 of the controller.

[0012] Preferably, the dual-channel relay module further includes an energy storage element and a control switch, wherein the two ends of the control switch connected in series with the power resistor R5 are connected in parallel with the energy storage element.

[0013] This application also proposes a speed control method for a non-self-locking motor. Using the aforementioned speed control system for a non-self-locking motor, the method includes:

[0014] When the power supply is normal, the controller outputs PWM signals through signal terminals A_GH1, A_GL1, A_GH2, and A_GL2 to the control terminals of transistors Q1, Q2, Q3, and Q4 for speed control. At the same time, it outputs a low level through signal terminals A_k1 and A_k2 to control the first channel of the dual relay to be turned on and the second channel to be turned off.

[0015] After the power is cut off, the controller first outputs a low level on the control signal terminals A_GH1, A_GL1, A_GH2, and A_GL2, and transistors Q1, Q2, Q3, and Q4 are turned off accordingly. At this time, the motor continues to rotate due to the load gravity or inertia, and the controller continues to control the motor speed at this time by controlling the output level of the control signal terminals A_GH1, A_GL1, A_GH2, A_GL2, and A_k1,2.

[0016] Preferably, after the power is cut off, if it is necessary to control the motor to decelerate, the controller controls A_GH1 to high level, A_GL1 to low level, A_GH2 to low level and A_GL2 to high level, or A_GH1 to low level, A_GL1 to high level, A_GH2 to high level and A_GL2 to low level, according to the direction of motor rotation. At the same time, A_k1,2 is kept at low level. At this time, the reverse braking force generated by the reverse electromotive force of the motor increases, and the motor decelerates.

[0017] Preferably, after the power is cut off, if the motor needs to be decelerated, the controller control signal terminal A_k1,2 outputs a high level. At this time, the second channel of the dual-channel relay is turned on and the first channel is turned off. The motor and the power resistor R5 form a circuit. The reverse electromotive force generated by the motor is actively consumed by the power resistor R5. The reverse braking force generated by the reverse electromotive force of the motor increases, and the motor decelerates.

[0018] The technical advantages of this invention are as follows: This invention uses NMOS transistors to construct an H-bridge drive circuit, reducing on-resistance and switching losses, simplifying drive design, and lowering costs and installation difficulty; freewheeling diodes provide protection and braking function, while RC circuits and filter capacitors effectively reduce electromagnetic interference, stabilize power supply voltage, and improve system reliability. The dual-channel relay module achieves PWM speed regulation under normal power conditions through channel switching, and controls deceleration after power failure by consuming back electromotive force through a power resistor or increasing braking torque by conducting a specific transistor, with flexible adjustment of the deceleration degree. Overall, it achieves non-self-locking motor speed control, especially speed control after power failure. Attached Figure Description

[0019] Figure 1 The circuit diagram of the H-bridge driver module provided in the embodiment of the present invention;

[0020] Figure 2 The circuit diagram of the dual-channel relay module provided in the embodiment of the present invention. Detailed Implementation

[0021] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. This is to help those skilled in the art to have a more complete, accurate, and in-depth understanding of the inventive concept and technical solutions of the present invention, and to facilitate its implementation. It should be noted that the terms "first," "second," etc., used in this application are only for the convenience of describing the technical solutions and to distinguish components; the corresponding component configurations may be the same or different, and are not intended to limit the scope of this application. To make the technical solutions of the present invention clearer, the present invention will be explained and illustrated through the following embodiments.

[0022] This embodiment provides a speed control system for a non-self-locking motor, applicable to scenarios where the motor provides initial power, and after power failure, the motor is powered by load gravity or motor inertia. The system includes a power supply, a controller, an H-bridge drive module, a dual-channel relay module, and a non-self-locking motor. The controller is connected to both the H-bridge drive module and the dual-channel relay module to drive them. The output of the H-bridge drive module is connected to the non-self-locking motor through the dual-channel relay module. The power supply is connected to the H-bridge drive module.

[0023] Specifically, such as Figure 1 As shown, the H-bridge driving module of this embodiment includes an H-bridge driving circuit, which includes four bridge arms composed of four transistors Q1, Q2, Q3, and Q4, each with a built-in freewheeling diode. A terminal M01_A_SH1 between the second terminal of transistor Q1 and the first terminal of transistor Q2 is connected to the dual-channel relay module; a terminal M01_A_SH2 between the second terminal of transistor Q3 and the first terminal of transistor Q4 is connected to the dual-channel relay module; a terminal between the first terminal of transistor Q1 and the first terminal of transistor Q3 is connected to the positive power supply A_VDH1; a terminal between the second terminal of transistor Q2 and the second terminal of transistor Q4 is grounded; and the control terminals of the four transistors Q1, Q2, Q3, and Q4 are respectively connected to the four signal terminals A_GH1, A_GL1, A_GH2, and A_GL2 of the controller.

[0024] Furthermore, in this embodiment, transistors Q1, Q2, Q3, and Q4 all employ NMOS transistors. Correspondingly, the first terminal of each transistor is the drain, the second terminal is the source, and the control terminal is the gate. Compared to PMOS transistors, NMOS transistors offer advantages such as lower on-resistance, faster switching speed, and simpler driving, which can reduce circuit layout difficulty and lower costs.

[0025] In this embodiment, each transistor has a built-in freewheeling diode connected between the drain and source of the transistor, with the anode of the freewheeling diode connected to the source and the cathode connected to the drain. The motor is an inductive load; when the transistor is turned off, the current in the motor inductor cannot change abruptly, resulting in a very high back electromotive force. The freewheeling diode provides a freewheeling path for the inductor current, preventing excessive voltage spikes from damaging the switching device. Simultaneously, this freewheeling path creates reverse braking during the motor's continued movement after power failure, causing the motor's continued movement to slow down.

[0026] In this embodiment, to reduce electromagnetic interference, an RC series circuit is connected in parallel between the first and second terminals of transistors Q1, Q2, Q3, and Q4, such as... Figure 1 As shown, a resistor R1 and a capacitor C1 are connected in parallel between the drain and source of transistor Q1; a resistor R2 and a capacitor C2 are connected in parallel between the drain and source of transistor Q2; a resistor R3 and a capacitor C3 are connected in parallel between the drain and source of transistor Q3; and a resistor R4 and a capacitor C4 are connected in parallel between the drain and source of transistor Q4. This RC series circuit forms a low-pass filter circuit, attenuating high-frequency oscillation signals and thus reducing electromagnetic interference.

[0027] In addition, the H-bridge drive circuit in this embodiment also includes capacitors C5 and C6. One end of capacitors C5 and C6 is grounded after being connected in parallel, and the other end is connected to the positive power supply terminal A_VDH1. Capacitors C5 and C6 serve as filter capacitors, connected in parallel between the positive power supply terminal A_VDH1 and ground, forming a low-impedance path to absorb instantaneous current changes in the circuit and stabilize the power supply voltage.

[0028] like Figure 2As shown, the dual-channel relay module in this embodiment includes a dual-channel relay and a power resistor R5. The output of the H-bridge drive module is connected to the non-self-locking motor through the first channel of the dual-channel relay. That is, when the first channel is on, terminals M01_A_SH1 and M01_A_SH2 are directly connected to the motor. The power resistor R5 is connected to the non-self-locking motor through the second channel of the dual-channel relay. That is, when the second channel is on, the power resistor R5 and the non-self-locking motor form a series circuit. The control coils of the first and second channels of the dual-channel relay are connected in parallel, with one end grounded and the other end connected to the signal terminals A_k1,2 of the controller. That is, the switching between the first and second channels is controlled by the output level of the signal terminals A_k1,2. When the output of the signal terminals A_k1,2 is low, the control coil is not energized, contacts K1 and K2 remain stationary, and the dual-channel relay maintains the conduction of the first channel. When the output of the signal terminals A_k1,2 is high, the control coil is energized, driving contacts K1 and K2, and the dual-channel relay correspondingly activates the second channel. The dual-channel relay control logic is simple, and it can control two different circuits simultaneously. The control signals of the first and second channels are completely independent and do not affect each other, thus achieving strong electrical isolation.

[0029] The controller in this embodiment is used to control the output levels of signal terminals A_GH1, A_GL1, A_GH2, A_GL2, and A_k1,2, and integrates a PWM module. In specific implementations, microcontrollers (MCUs) or other control devices can be used. Microcontrollers (MCUs) have the advantages of small size, high integration, and low cost, which facilitates the deployment of the system of this invention and reduces costs.

[0030] Correspondingly, this embodiment proposes a speed control method for a non-self-locking motor. Using the aforementioned speed control system for a non-self-locking motor, the method will be specifically described below under normal power supply and power failure conditions.

[0031] When the power supply is normal:

[0032] The controller outputs PWM signals to the control terminals of transistors Q1, Q2, Q3, and Q4 via signal terminals A_GH1, A_GL1, A_GH2, and A_GL2 for speed control. At the same time, it outputs a low level via signal terminal A_k1,2 to control the first channel of the dual-channel relay to be turned on and the second channel to be turned off.

[0033] For example, when the A_GH1 signal is high, transistor Q1 is turned on; when the A_GL1 signal is low, transistor Q2 is turned off; when the A_GH2 signal is low, transistor Q3 is turned off; when the A_GL2 signal is high, transistor Q4 is turned on, and the motor rotates forward.

[0034] When signal A_GH1 is low, transistor Q1 is off; when signal A_GL1 is high, transistor Q2 is on; when signal A_GH2 is high, transistor Q3 is on; and when signal A_GL2 is low, transistor Q4 is off, causing the motor to reverse. During this process, speed is adjusted by changing the duty cycle of signals A_GH1, A_GL1, A_GH2, and A_GL2. Generally, a larger duty cycle results in a faster motor speed.

[0035] After the power is cut off:

[0036] The controller first controls the signal terminals A_GH1, A_GL1, A_GH2, and A_GL2 to all output a low level, correspondingly turning off transistors Q1, Q2, Q3, and Q4. At this time, the motor continues to rotate due to load weight or inertia, generating a back electromotive force (EMF). For example, if the motor continues to rotate forward due to load weight or inertia, it will generate a back EMF and a back current. In the H-bridge drive circuit, the motor's back current sequentially passes through the freewheeling diode of transistor Q3, the positive power supply terminal, ground, and the freewheeling diode of transistor Q2 before returning to the motor to form a circuit. Correspondingly, the back current generates an electromagnetic force (Lorentz force) through the motor windings. According to Lenz's law, this electromagnetic force opposes the rotor's movement, creating a braking torque that hinders the motor's free rotation due to load weight or inertia. Here, the reverse current equals the back EMF divided by the loop resistance.

[0037] In order to achieve motor speed control after power failure, the controller of this application controls the motor speed at this time through the output level of control signal terminals A_GH1, A_GL1, A_GH2, A_GL2, and A_k1,2.

[0038] Specifically, after the power is cut off, if the motor needs to be decelerated, the controller will control A_GH1 to be high, A_GL1 to be low, A_GH2 to be low, and A_GL2 to be high, or A_GH1 to be low, A_GL1 to be high, A_GH2 to be high, and A_GL2 to be low, according to the direction of motor rotation. At the same time, A_k1,2 will be kept low. At this time, the reverse braking force generated by the reverse electromotive force of the motor increases, and the motor decelerates.

[0039] For example, if the motor continues to rotate forward due to load gravity or inertia, it will generate a reverse electromotive force and a reverse current. At this time, if A_GH1 is low, A_GL1 is high, A_GH2 is high, and A_GL2 is low, transistors Q2 and Q3 will conduct, while transistors Q2 and Q3 will remain off. The reverse current will then flow sequentially through transistor Q3, the positive power supply terminal, ground, and transistor Q2 back to the motor, forming a circuit. Compared to a circuit relying on a freewheeling diode, the overall loop resistance is reduced. Therefore, according to the formula reverse current = reverse electromotive force / loop resistance, the reverse current increases, resulting in a larger motor torque, thus achieving motor deceleration. This solution allows for speed adjustment after motor power failure even when the H-bridge drive circuit is connected to the motor, without requiring changes to the system configuration, making it convenient to operate and saving on modification costs.

[0040] In addition, this embodiment also proposes a motor deceleration scheme: After power failure, if motor deceleration is to be controlled, the controller control signal terminal A_k1,2 outputs a high level. At this time, the second channel of the dual-channel relay is turned on, and the first channel is turned off. The motor and the power resistor R5 form a circuit. The back electromotive force generated by the motor is actively consumed by the power resistor R5, and the reverse braking force generated by the back electromotive force of the motor increases, thus decelerating the motor. Part of the mechanical energy generated by the motor due to gravity or inertia is converted into heat energy consumed by the power resistor R5, thereby reducing the motor speed. In specific implementation, the value of the power resistor R5 can be flexibly selected according to the actual application scenario, thereby autonomously adjusting the degree of motor deceleration as needed. This scheme achieves motor speed regulation after power failure through a simple and easily controllable dual-channel relay and power resistor R5. The motor is completely disconnected from the H-bridge drive circuit, and the back electromotive force generated by the motor is not output to the H-bridge drive circuit, reducing the safety protection requirements of the H-bridge drive circuit and thus reducing system costs.

[0041] In a preferred embodiment of this application, to avoid wasting the back electromotive force generated by the motor, the corresponding dual-channel relay module further includes an energy storage element and a control switch. The two ends of the control switch connected in series with the power resistor R5 are connected in parallel with the energy storage element. The motor, power resistor R5, and control switch form a series circuit. When the second channel is on, the controller can turn off the control switch, thereby directly storing the back electromotive force generated by the motor into the energy storage element. The corresponding energy storage element can be the power supply A_VDH1 of the H-bridge drive circuit.

[0042] In a preferred embodiment of this application, under special circumstances where it is still necessary to accelerate the motor after a power outage, the motor can be disconnected from the H-bridge drive circuit and all other electrically connected loads. In this case, the motor will not generate reverse braking force. Correspondingly, the dual-channel relay can be replaced with a switching device that can control three states. The first state is used to control the connection between the motor and the H-bridge drive circuit, the second state is used to control the connection between the motor and the power resistor R5, and the third state is used to directly disconnect the motor from all circuits or loads, which is usually left floating.

[0043] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the inventive concept and technical solution; or the direct application of the inventive concept and technical solution to other situations without modification, are all within the protection scope of the present invention.

Claims

1. A speed control system of a non-self-locking motor, applied to a scenario that the motor provides initial power, and the load gravity or the motor inertia provides power after the motor is powered off, characterized in that: The system comprises a power supply, a controller, an H-bridge driving module, a double-way relay module and a non-self-locking motor, wherein the controller is connected with the H-bridge driving module and the double-way relay module respectively, and is used for driving the H-bridge driving module and the double-way relay module; the output end of the H-bridge driving module is connected with the non-self-locking motor through the double-way relay module; and the power supply is connected with the H-bridge driving module. The double-way relay module comprises a double-way relay and a power resistor R5, wherein the output end of the H-bridge driving module is connected with the non-self-locking motor through the first channel of the double-way relay; the power resistor R5 is connected with the non-self-locking motor through the second channel of the double-way relay; the control coils of the first channel and the second channel of the double-way relay are connected in parallel, and one end is grounded, and the other end is connected with the signal end A_k1,2 of the controller. The double-way relay module further comprises an energy storage element and a control switch, and the control switch is connected in series with the power resistor R5 and is connected in parallel with the energy storage element. When there is a motor acceleration demand after power failure, the double-way relay is replaced by a switch device controlling three states, the first state is used for controlling the connection of the motor and the H-bridge driving circuit to realize deceleration, the second state is used for controlling the connection of the motor and the power resistor R5 to realize deceleration, and the third state is used for disconnecting the motor from the H-bridge driving module and disconnecting all other electrically connected loads, so as to realize the motor acceleration after power failure.

2. A speed control system for a non-locked motor as claimed in claim 1, wherein: The H-bridge driving module comprises an H-bridge driving circuit, and the H-bridge driving circuit comprises four bridge arms respectively composed of four transistors Q1, Q2, Q3 and Q4 with built-in freewheeling diodes, wherein a terminal M01_A_SH1 is led between the second end of the transistor Q1 and the first end of the transistor Q2 and is connected to the double-way relay module; a terminal M01_A_SH2 is led between the second end of the transistor Q3 and the first end of the transistor Q4 and is connected to the double-way relay module; a terminal is led between the first end of the transistor Q1 and the first end of the transistor Q3 and is connected to the positive pole A_VDH1 of the power supply; a terminal is led between the second end of the transistor Q2 and the second end of the transistor Q4 and is grounded; and the control ends of the four transistors Q1, Q2, Q3 and Q4 are respectively connected with four signal ends A_GH1, A_GL1, A_GH2 and A_GL2 of the controller.

3. A speed control system for a non-locked motor as claimed in claim 2, wherein: An RC series circuit is connected in parallel between the first end and the second end of each of the transistors Q1, Q2, Q3 and Q4.

4. A speed control system for a non-locked motor as claimed in claim 2, wherein: The H-bridge driving circuit further comprises capacitors C5 and C6, wherein one end of the capacitors C5 and C6 is grounded, and the other end is connected with the positive pole A_VDH1 of the power supply.

5. A speed control system for a non-locked motor as claimed in any one of claims 2 to 4, wherein: The transistors Q1, Q2, Q3 and Q4 are all NMOS, and correspondingly, the first end of each of the transistors Q1, Q2, Q3 and Q4 is a drain, the second end is a source, and the control end is a gate.

6. A method of speed control of a non-self-locking motor using a speed control system of a non-self-locking motor according to any one of claims 1 to 5, characterized in that: The method comprises: When the power supply is normal, the controller outputs PWM signals to the control terminals of transistors Q1, Q2, Q3 and Q4 through signal terminals A_GH1, A_GL1, A_GH2 and A_GL2 for speed control, and outputs low level to signal terminal A_k1,2 to control the first channel of the double-channel relay to be on and the second channel to be off. After the power supply is powered off, the controller first controls signal terminals A_GH1, A_GL1, A_GH2 and A_GL2 to output low level, and transistors Q1, Q2, Q3 and Q4 are turned off correspondingly. At this time, the motor continues to rotate due to the load gravity or inertia, and the controller continues to control the motor speed through the output level of control signal terminals A_GH1, A_GL1, A_GH2, A_GL2 and A_k1,2.

7. A method of speed control of a non-locked motor as claimed in claim 6, wherein: After the power supply is powered off, if the motor speed is to be controlled, the controller controls A_GH1 to be high level, A_GL1 to be low level, A_GH2 to be low level and A_GL2 to be high level, or A_GH1 to be low level, A_GL1 to be high level, A_GH2 to be high level and A_GL2 to be low level according to the rotating direction of the motor, and at the same time, A_k1,2 is kept to be low level. At this time, the reverse braking force generated by the reverse electromotive force of the motor increases, and the motor slows down.

8. The method of claim 6, wherein: After the power supply is powered off, if the motor speed is to be controlled, the controller controls signal terminal A_k1,2 to output high level. At this time, the second channel of the double-channel relay is turned on and the first channel is turned off, and the motor forms a loop with power resistor R5. The reverse electromotive force generated by the motor is actively consumed by power resistor R5, the reverse braking force generated by the reverse electromotive force of the motor increases, and the motor slows down.

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