Motor braking circuit

Abstract

The invention discloses a motor braking circuit which comprises a motor, the motor is driven to work by mains supply through a driving power supply, and a capacitor is arranged in the driving power supply; the driving power supply is connected with a mains supply outage detection circuit, the mains supply outage detection circuit sends a mains supply outage signal to the driving power supply when the mains supply is in outage, and the driving power supply drives the motor to rotate reversely after receiving the mains supply outage signal. The device has the advantages of being simple in structure, low in cost and capable of braking in time during power failure.

Description

Technical Field

[0001] The present invention relates to the field of motor control, and particularly to an electric motor braking circuit with a simple structure, low cost, and capable of timely braking during a power outage. Background Art

[0002] Modern life and production are inseparable from power motors. Power motors are generally powered by a driving power supply. When the switching power supply in the driving power supply is powered by the mains input, the switching power supply outputs direct current to the controller, and the motor in the controller can control the forward and reverse rotation of the motor. When the motor load is large, the inertia is also large. If the mains power is cut off during the rotation of the motor, since the electric charge stored in the capacitor inside the switching power supply has not been discharged completely, the controller still has power supply, and the motor will continue to rotate until the electric charge stored in the capacitor inside the switching power supply is discharged completely, and then the controller may lose power and the motor will stop rotating. In this case, if the mains power suddenly cuts off during the rotation of the motor, the motor still has to rotate for more than a few seconds and cannot cut off the power in time, which may cause various risks and trigger accidents. Summary of the Invention

[0003] The present invention provides an electric motor braking circuit with a simple structure, low cost, and capable of timely braking during a power outage.

[0004] The technical solution adopted by the present invention is to provide an electric motor braking circuit, including a motor, the motor is driven by the mains through a driving power supply, and a capacitor is provided in the driving power supply; a mains power failure detection circuit is connected in the driving power supply, and when the mains power fails, the mains power failure detection circuit sends a mains power failure signal to the driving power supply, and the driving power supply drives the motor to reverse after receiving the mains power failure signal.

[0005] As a preferred mode, the driving power supply includes a switching power supply connected to the mains and a controller, and the mains power failure detection circuit is connected to the mains and sends a detection signal to the controller.

[0006] As a preferred mode, the power failure detection circuit includes a rectifying circuit connected to the mains, and a signal output module is connected to the output end of the rectifying circuit, and the signal output module sends a detection signal to the controller.

[0007] As a preferred mode, two groups of lines are connected in parallel to the input end of the motor. Among them, the first group of lines is powered by the motor driving circuit in the controller, and the second group of lines of the motor is short-circuited through a normally closed switch, and the normally closed switch is connected to the power line; when the power supply stops supplying power, the normally closed switch short-circuits the second group of lines, and when the power supply supplies power, the normally closed switch opens the second group of lines.

[0008] As a preferred mode, the motor is a common permanent magnet motor or a three-phase permanent magnet synchronous motor.

[0009] As a preferred mode, the normally-closed switch is a normally-closed electromagnetic switch.

[0010] In the present invention, a mains power failure detection circuit is added inside the drive power supply. When the mains power fails, the power stored in the capacitor inside the drive power supply is utilized to output a power failure signal through the mains power failure detection circuit. When the drive power supply receives the power failure signal, the drive power supply drives the motor to reverse. Since the reverse rotation of the motor consumes a large amount of power, the power in the capacitor inside the drive power supply is discharged completely within a very short time, causing the motor to stop rotating. The present invention can cause the motor to stop rotating in time after the mains power suddenly fails during the rotation of the motor, and can effectively prevent accidents caused by the continuous rotation of the motor. Description of the Drawings

[0011] Figure 1 is the structural schematic diagram of an embodiment of the present invention; Figure 2 is the circuit schematic diagram of the mains power failure detection circuit of an embodiment of the present invention. Detailed Embodiments

[0012] Referring to Figures 1 to 2 as shown, there is shown a motor braking circuit provided by the present invention, including a motor 100. The motor 100 is driven to operate by the mains power through a drive power supply, and a capacitor is provided in the drive power supply; the drive power supply includes a switching power supply 400 connected to the mains power and a controller 300 for controlling the operation of the motor 100. In this embodiment, the mains power failure detection circuit 401 is disposed inside the switching power supply 400 connected to the mains power. When the mains power fails, the mains power failure detection circuit 401 sends a mains power failure signal to the MCU in the controller 300 of the drive power supply. After receiving the mains power failure signal, the motor drive circuit 301 in the controller 300 drives the motor 100 to reverse.

[0013] Referring to Figure 1 , in order to prevent accidents caused by the continuous rotation of the motor 100 after the mains power fails during the rotation of the motor 100, the circuit of this embodiment provides a low-cost solution: a mains power failure detection circuit 401 is added inside the switching power supply 400 in the drive power supply. When the mains power fails, the power stored in the capacitor inside the switching power supply 401 is utilized to output a power failure signal externally. The cost of this circuit is within 2 yuan. The mains power failure detection circuit 401 in this embodiment refers to Figure 2 as shown. Referring to Figure 1During the rotation of the motor 100, if the mains power is cut off, the switch power supply disconnection signal output circuit 401 can output a signal to the controller 300 on the right within 0.5 seconds. After receiving the power-off signal, the motor drive circuit 301 in the controller 300 drives the motor 100 to reverse. Since the reverse rotation of the motor 100 will consume a large amount of electricity and discharge the electricity of the internal capacitor of the switch power supply 400 in a very short time, the controller 300 will lose power and the motor 100 will stop rotating. This circuit can stop the motor 100 within 1 second after the mains power is suddenly cut off during the rotation of the motor, effectively preventing accidents caused by the continuous rotation of the motor 100.

[0014] The circuit of the present invention refers to Figure 2 , specifically based on the previous technical solution, the power-off detection circuit 401 includes a rectification circuit connected to the mains power, and a signal output module is connected to the output end of the rectification circuit. The signal output module sends the detection signal to the MCU in the controller 300.

[0015] The circuit of the present invention refers to Figure 1 , specifically based on the previous technical solution, two groups of lines are connected in parallel to the input end of the motor 100. The first group of lines is powered by the motor drive circuit 301 in the controller 300. The second group of lines of the motor 100 is short-circuited through the normally closed switches K1 and K2, and the normally closed switches are connected to the power supply line; when the power supply stops, the normally closed switches short-circuit the second group of lines, and when the power supply is on, the normally closed switches open the second group of lines. When the coils of the normally closed switches K1 and K2 are energized, the normally closed contacts are disconnected. After adding the normally closed switches, when the elevator, crane, electric door, etc. driven by the motor fall or are pushed manually, they drive the permanent magnet motor M to rotate at high speed in the reverse direction through the speed reduction mechanism (the magnetic field and the coil cut the magnetic force lines to generate an induced electromotive force), that is, it becomes a generator. At this time, due to the short circuit of the motor, an impedance force is generated inside the motor and it is not easy to rotate, generating a damping effect to avoid the harm caused by the fall or inertial movement of the elevator, crane, electric door, etc. The permanent magnet motor M can be a single-phase ordinary permanent magnet motor or a three-phase permanent magnet synchronous motor (in this embodiment, refer to Figure 1 is a three-phase permanent magnet synchronous motor).

[0016] The circuit of the present invention refers to Figure 1 and Figure 2 , specifically based on the previous technical solution, the motor 100 is an ordinary permanent magnet motor or a three-phase permanent magnet synchronous motor.

[0017] The circuit of the present invention refers to Figure 1 and Figure 2 , specifically based on the previous technical solution, the normally closed switches K1 and K2 are normally closed electromagnetic switches.

[0018] The above-disclosed is only the preferred embodiment of the present invention. Of course, the scope of the rights of the present invention cannot be limited thereby. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A motor braking circuit, characterized in that: The invention comprises a motor, wherein the motor is driven by the mains via a driving power supply, wherein a capacitor is arranged in the driving power supply; wherein a mains power failure detection circuit is connected to the driving power supply, wherein when the mains power is failed, the mains power failure detection circuit sends a mains power failure signal to the driving power supply, and the driving power supply drives the motor to reverse after receiving the mains power failure signal.

2. The motor braking circuit according to claim 1, characterized in that: The driving power supply comprises a switching power supply and a controller connected to the mains power supply. The mains power failure detection circuit is connected to the mains power supply and sends a detection signal to the controller.

3. The motor braking circuit according to claim 1, characterized in that: The power failure detection circuit comprises a rectifier circuit connected to the mains, an output end of the rectifier circuit is connected to a signal output module, and the signal output module sends a detection signal to a controller.

4. The motor braking circuit according to claim 1, characterized in that: The input end of the motor is connected in parallel with two groups of circuits, wherein the first group of circuits is powered by the motor drive circuit in the controller, and the second group of circuits of the motor is short-circuited by a normally closed switch, and the normally closed switch is connected to the power line; When the power source stops supplying power, the normally closed switch short-circuits the second group of lines, and when the power source supplies power, the normally closed switch disconnects the second group of lines.

5. The motor braking circuit according to claim 4, characterized in that: The motor is a common permanent magnet motor or a three-phase permanent magnet synchronous motor.

6. The motor braking circuit according to claim 4, characterized in that: The normally closed switch is a normally closed electromagnetic switch.

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