An emergency stop self-locking circuit for a DC motor

Abstract

This invention provides an emergency stop self-locking circuit for a DC motor, belonging to the field of motor braking technology. The emergency stop self-locking circuit includes a main circuit, an energy release circuit, and a power-off detection circuit. The energy release circuit consists of MOSFETs connected in parallel across the motor terminals, with the source and drain of the MOSFETs connected to the motor terminals respectively. The power-off detection circuit is a switching circuit used to control the on / off state of the MOSFETs. The switching circuit is connected to the gate of the MOSFETs. When the power supply is on, the switching circuit is off, and the MOSFETs are in the off state. When the power supply is off, the motor acts as a generator to provide current, the switching circuit is on, the MOSFETs become saturated, and the current provided by the motor flows from the positive terminal through the MOSFETs to the negative terminal, causing a short circuit. The advantage of this invention is that this structure allows the motor to achieve an emergency stop function while reducing the size of the push rod, facilitating processing and installation. This invention is used for emergency stop control of motors.

Description

[Technical Field]

[0001] This invention relates to an emergency stop self-locking circuit for a DC motor, belonging to the field of motor braking technology. [Background Technology]

[0002] DC motors have a wide range of applications in daily life and production, such as in electric linear actuators. Usually, in order to make it more convenient for users to use electric linear actuators, the motor needs to be able to achieve an emergency stop function, that is, the motor that needs to rotate can stop rotating immediately after the power is cut off and remain in the current position. However, due to inertia, if no interference is applied, the high-speed rotating motor will continue to rotate for a period of time after the power is cut off before it stops.

[0003] The common method is to add mechanical structures such as torsion springs to the motor shaft, or to achieve the purpose of emergency stop of the motor when the power is cut off through normally closed contacts of relays. This structure can enable the motor to achieve emergency stop function. However, due to the large size of mechanical structures and components such as relays, it is difficult to make the push rod into a miniaturized push rod, which makes the push rod large in size and affects the processing and installation. [Summary of the Invention]

[0004] The technical problem to be solved by the present invention is to provide an emergency stop self-locking circuit for a DC motor, which enables the motor to achieve an emergency stop function while reducing the size of the push rod, making it easier to process and install.

[0005] To solve the above-mentioned technical problems, the emergency stop self-locking circuit of the DC motor of the present invention includes:

[0006] The main circuit has its two ends connected to the positive and negative terminals of the power supply, respectively, and the motor is located within the main circuit to obtain electrical energy.

[0007] An energy release circuit is used to control the motor to be short-circuited so that the motor can be braked;

[0008] A power failure detection circuit is used to control the disconnection of the energy release circuit when the power supply is on and to control the conduction of the energy release circuit when the power supply is off.

[0009] The energy release circuit consists of MOSFETs connected in parallel across the motor. The source and drain of the MOSFETs are connected to the two ends of the motor, respectively. The power-off detection circuit is a switching circuit used to control the on / off state of the MOSFETs. The switching circuit is connected to the gate of the MOSFETs. When the power supply is on, the switching circuit is off, the gate of the MOSFETs has no voltage and is in the off state, and the motor rotates normally. When the power supply is off, the motor acts as a generator to provide current, the switching circuit is on, the gate of the MOSFETs has voltage and becomes saturated, and the current provided by the motor flows from the positive terminal through the MOSFETs in the energy release circuit to the negative terminal, causing a short circuit and forming short-circuit braking.

[0010] Preferably, the power failure detection circuit consists of a PNP transistor Q3, an NPN transistor Q5, and a diode D4. In the PNP transistor Q3, its emitter is connected to the positive terminal of the power supply, its collector is connected to the gate of the MOSFET, and its base is connected to the collector of the NPN transistor Q5. In the NPN transistor Q5, its base is connected to the negative terminal of the power supply, and its emitter is connected to the negative terminal of the motor. The diode D4 is located in the circuit between the base of the NPN transistor Q5 and the negative terminal of the power supply to generate a voltage drop to ensure that the NPN transistor Q5 is turned on.

[0011] The main circuit also includes a voltage isolation circuit, which consists of diodes D1 and D2. Diode D1 is located in the circuit between the emitter of NPN transistor Q5 and the negative terminal of the power supply. Diode D2 is connected in parallel across diode D1. The current conduction directions of diodes D1 and D2 are opposite.

[0012] Preferably, the power failure detection circuit consists of a PNP transistor Q4 and a diode D3. In the PNP transistor Q4, its emitter is connected to the positive terminal of the motor, its collector is connected to the gate of the MOSFET, and its base is connected to the positive terminal of the power supply. The diode D3 is located in the circuit between the base of the PNP transistor Q4 and the positive terminal of the power supply to generate a voltage drop to ensure that the PNP transistor Q4 is turned on.

[0013] The main circuit also includes a voltage isolation circuit, which consists of diodes D1 and D2. Diode D1 is located in the base circuit between PNP transistor Q4 and the positive terminal of the power supply. Diode D2 is connected in parallel across diode D1. The current conduction directions of diodes D1 and D2 are opposite.

[0014] Preferably, the power failure detection circuit includes a first power failure detection circuit for controlling the on / off state of the energy release circuit when the motor rotates forward and a second power failure detection circuit for controlling the on / off state of the energy release circuit when the motor rotates in reverse.

[0015] Preferably, the first power failure detection circuit consists of a PNP transistor Q3, an NPN transistor Q5, and a diode D4. In the PNP transistor Q3, its emitter is connected to the positive terminal of the power supply when the motor is rotating forward, its collector is connected to the gate of the MOSFET, and its base is connected to the collector of the NPN transistor Q5. In the NPN transistor Q5, its base is connected to the negative terminal of the power supply when the motor is rotating forward, and its emitter is connected to the negative terminal of the motor when the motor is rotating forward. The diode D4 is located in the circuit between the emitter of the NPN transistor Q5 and the negative terminal of the power supply when the motor is rotating forward to generate a voltage drop to ensure that the NPN transistor Q5 is turned on.

[0016] The second power failure detection circuit consists of a PNP transistor Q4 and a diode D3. In the PNP transistor Q4, its emitter is connected to the positive terminal of the motor when the motor reverses, its collector is connected to the gate of the MOSFET, and its base is connected to the positive terminal of the power supply when the motor reverses. The diode D3 is located in the circuit between the base of the PNP transistor Q4 and the positive terminal of the power supply when the motor reverses to generate a voltage drop to ensure that the PNP transistor Q4 is turned on.

[0017] The main circuit also includes a voltage isolation circuit, which consists of diodes D1 and D2. Diode D1 is located in the circuit between the emitter of NPN transistor Q5 and the negative terminal of the power supply when the motor reverses, and in the circuit between the base of PNP transistor Q4 and the positive terminal of the power supply when the motor reverses. Diode D2 is connected in parallel across diode D1, and the current conduction directions of diodes D1 and D2 are opposite.

[0018] Preferably, the MOS transistor includes an NMOS transistor Q2 connected to the first power-off detection circuit and an NMOS transistor Q1 connected to the second power-off detection circuit. The drain of the NMOS transistor Q2 and the drain of the NMOS transistor Q1 are connected in series. The source of the NMOS transistor Q2 and the source of the NMOS transistor Q1 are respectively connected to the two ends of the motor so that the NMOS transistors Q1 and Q2 are connected in parallel with respect to the motor. Both the NMOS transistors Q1 and Q2 include a body diode to prevent the other from limiting current flow when one of the NMOS transistors Q1 and Q2 is turned on.

[0019] Preferably, the first power-off detection circuit and the second current detection circuit are both composed of a PNP transistor Q3, an NPN transistor Q5, and a diode D4. In the PNP transistor Q3, its emitter is connected to the positive terminal of the power supply, its collector is connected to the gate of the MOSFET, and its base is connected to the collector of the NPN transistor Q5. In the NPN transistor Q5, its base is connected to the negative terminal of the power supply, and its emitter is connected to the negative terminal of the motor. The diode D4 is located in the circuit between the base of the NPN transistor Q5 and the negative terminal of the power supply to generate a voltage drop to ensure that the NPN transistor Q5 is turned on. The main circuit also includes a voltage isolation circuit, which is composed of diodes D1 and D2. The diode D1 is located in the circuit between the emitter of the NPN transistor Q5 and the negative terminal of the power supply, and the diode D2 is connected in parallel across the two ends of the diode D1. The current conduction directions of the diodes D1 and D2 are opposite.

[0020] Preferably, both the first power-off detection circuit and the second current detection circuit are composed of a PNP transistor Q4 and a diode D3. In the PNP transistor Q4, its emitter is connected to the positive terminal of the motor, its collector is connected to the gate of the MOSFET, and its base is connected to the positive terminal of the power supply. The diode D3 is located in the circuit between the base of the PNP transistor Q4 and the positive terminal of the power supply to generate a voltage drop to ensure that the PNP transistor Q4 is turned on. The main circuit is also provided with a voltage isolation circuit, which is composed of diodes D1 and D2. The diode D1 is located in the circuit between the base of the PNP transistor Q4 and the positive terminal of the power supply, and the diode D2 is connected in parallel across the two ends of the diode D1. The current conduction directions of the diodes D1 and D2 are opposite.

[0021] Preferably, the base of the NPN transistor Q5 is connected to the positive terminal of the power supply, and a resistor R4 is provided between the base and the positive terminal of the power supply; the base of the PNP transistor Q3 is connected to the positive terminal of the power supply, and a resistor R1 is provided between the base and the positive terminal of the power supply; a resistor R2 is provided between the base of the PNP transistor Q3 and the collector of the NPN transistor Q5; the collector of the PNP transistor Q3 is connected to the negative terminal of the motor; a voltage divider resistor R6 is provided between the collector of the PNP transistor Q3 and the gate of the MOSFET; and a voltage divider resistor R8 is provided between the gate and the source of the MOSFET.

[0022] Preferably, the base of the PNP transistor Q4 is connected to the negative terminal of the power supply, and a resistor R3 is provided between the base and the negative terminal of the power supply. The collector of the PNP transistor Q4 is connected to the negative terminal of the motor, and a voltage divider resistor R5 is provided between the collector of the PNP transistor Q4 and the gate of the MOS transistor. A voltage divider resistor R7 is provided between the gate and the source of the MOS transistor.

[0023] The beneficial effects of this invention are:

[0024] First, when the power supply is normal, the MOSFET acts as a switch and is in the off state, preventing current from flowing through the MOSFET and short-circuiting the motor, allowing the motor to rotate normally. The on / off state of the MOSFET is controlled by a power-off detection circuit connected to its gate. This power-off detection circuit is a switching circuit, used to control the flow of current, such as a transistor or a common switch. When the power supply is normal, the power-off detection circuit disconnects the current flowing to the gate to prevent current from flowing through the gate and generating voltage, thus ensuring the MOSFET is in the off state. When the power supply is momentarily disconnected, there is no power supply to the motor, but due to inertia, the motor continues to rotate. The rotation generates current, turning the motor into a generator. When this current flows through the MOSFET, the power-off detection circuit is activated, causing the current to flow through the gate and generate voltage, saturating the MOSFET and turning it on. The current flows from the positive terminal of the motor through the MOSFET to the negative terminal, achieving short-circuit braking, allowing the motor to stop suddenly. The principle of short-circuit braking is: when the power supply to the motor is cut off, the stator windings are short-circuited, and the rotor rotates due to inertia. Because of the residual magnetism in the rotor core, a rotating magnetic field is formed. Under the action of the motor's rotational inertia, the magnetic field cuts the stator winding and generates an induced electromotive force in the stator winding. Since the stator winding has been short-circuited by the normally closed contact of the contactor, there is an induced current in the stator winding circuit. This current interacts with the rotating magnetic field to generate a braking torque, forcing the motor to stop rotating.

[0025] Secondly, by implementing emergency stop through circuitry, the push rod does not require the mechanical structure or relay components found in existing technologies. These components are too bulky and affect processing and installation. This allows the push rod to be smaller, making it easier to process and install. In addition, when the power supply is unavailable, the motor can achieve self-locking by relying on the magnetic resistance of the rotating magnetic field, making it easier for users to operate.

[0026] These features and advantages of the present invention will be disclosed in detail in the following specific embodiments and accompanying drawings. [Attached Image Description]

[0027] The present invention will now be described in further detail with reference to the accompanying drawings, wherein:

[0028] Figure 1 This is a schematic diagram of the emergency stop self-locking circuit in Example 1;

[0029] Figure 2 This is a schematic diagram of the emergency stop self-locking circuit in Embodiment 1 when it is only the first power failure detection circuit;

[0030] Figure 3 This is a schematic diagram of the emergency stop self-locking circuit in Example 2.

Detailed Implementation Methods

[0031] The technical solutions of the embodiments of the present invention will be explained and described below with reference to the accompanying drawings. However, the following embodiments are only preferred embodiments of the present invention and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments in the implementation methods without creative effort are all within the protection scope of the present invention.

[0032] In the following description, terms such as “inner,” “outer,” “upper,” “lower,” “left,” and “right” that indicate orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings and are used only for the convenience of describing embodiments and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0033] Example 1:

[0034] like Figure 1 and Figure 2 As shown, the preferred structure of the emergency stop self-locking circuit for the DC motor in this embodiment includes:

[0035] The main circuit has its two ends connected to the positive and negative terminals of the power supply, respectively, and the motor is located within the main circuit to obtain electrical energy.

[0036] An energy release circuit is used to control the motor to be short-circuited so that the motor can be braked;

[0037] A power failure detection circuit is used to control the disconnection of the energy release circuit when the power supply is on and to control the conduction of the energy release circuit when the power supply is off.

[0038] The energy release circuit consists of MOSFETs connected in parallel across the motor. The source and drain of the MOSFETs are connected to the two ends of the motor, respectively. The power-off detection circuit is a switching circuit used to control the on / off state of the MOSFETs. The switching circuit is connected to the gate of the MOSFETs. When the power supply is on, the switching circuit is off, the gate of the MOSFETs has no voltage and is in the off state, and the motor rotates normally. When the power supply is off, the motor acts as a generator to provide current, the switching circuit is on, the gate of the MOSFETs has voltage and becomes saturated, and the current provided by the motor flows from the positive terminal through the MOSFETs in the energy release circuit to the negative terminal, causing a short circuit and forming short-circuit braking.

[0039] The beneficial effects of this invention are:

[0040] First, when the power supply is normal, the MOSFET acts as a switch and is in the off state, preventing current from flowing through the MOSFET and short-circuiting the motor, allowing the motor to rotate normally. The on / off state of the MOSFET is controlled by a power-off detection circuit connected to its gate. This power-off detection circuit is a switching circuit, used to control the flow of current, such as a transistor or a common switch. When the power supply is normal, the power-off detection circuit disconnects the current flowing to the gate to prevent current from flowing through the gate and generating voltage, thus ensuring the MOSFET is in the off state. When the power supply is momentarily disconnected, there is no power supply to the motor, but due to inertia, the motor continues to rotate. The rotation generates current, turning the motor into a generator. When this current flows through the MOSFET, the power-off detection circuit is activated, causing the current to flow through the gate and generate voltage, saturating the MOSFET and turning it on. The current flows from the positive terminal of the motor through the MOSFET to the negative terminal, achieving short-circuit braking, allowing the motor to stop suddenly. The principle of short-circuit braking is: when the power supply to the motor is cut off, the stator windings are short-circuited, and the rotor rotates due to inertia. Because of the residual magnetism in the rotor core, a rotating magnetic field is formed. Under the action of the motor's rotational inertia, the magnetic field cuts the stator winding and generates an induced electromotive force in the stator winding. Since the stator winding has been short-circuited by the normally closed contact of the contactor, there is an induced current in the stator winding circuit. This current interacts with the rotating magnetic field to generate a braking torque, forcing the motor to stop rotating.

[0041] Secondly, by implementing emergency stop through circuitry, the push rod does not require the mechanical structure or relay components found in existing technologies. These components are too bulky and affect processing and installation. This allows the push rod to be smaller, making it easier to process and install. In addition, when the power supply is unavailable, the motor can achieve self-locking by relying on the magnetic resistance of the rotating magnetic field, making it easier for users to operate.

[0042] In this embodiment, the positive terminal of the motor is the end connected to the positive terminal of the power supply, and the negative terminal of the motor is the end connected to the negative terminal of the power supply. The positive terminal when the motor is rotating in reverse is the negative terminal when the motor is rotating forward, and the negative terminal when the motor is rotating in reverse is the positive terminal when the motor is rotating forward. The positive and negative terminals when the motor is rotating in reverse are exactly the opposite of those when the motor is rotating forward. That is, in this embodiment, the two ends of the main circuit are POWER1 and POWER2, ​​respectively. When the motor is rotating forward, POWER1 is connected to the positive terminal of the power supply, and POWER2 is connected to the negative terminal of the power supply. The positive terminal of the motor is closer to the side of POWER1. When the motor is rotating in reverse, POWER2 is connected to the positive terminal of the power supply, and POWER1 is connected to the negative terminal of the power supply. The positive terminal of the motor is closer to the side of POWER2. In addition, the main circuit refers to the circuit from POWER1 to POWER2 or from POWER2 to POWER1, and the motor is located in the main circuit.

[0043] To optimize the power failure detection circuit, this embodiment preferably uses a PNP transistor Q3, an NPN transistor Q5, and a diode D4. In the PNP transistor Q3, its emitter is connected to the positive terminal of the power supply, its collector is connected to the gate of the MOSFET, and its base is connected to the collector of the NPN transistor Q5. In the NPN transistor Q5, its base is connected to the negative terminal of the power supply, and its emitter is connected to the negative terminal of the motor. The diode D4 is located in the circuit between the base of the NPN transistor Q5 and the negative terminal of the power supply to generate a voltage drop to ensure that the NPN transistor Q5 is turned on.

[0044] The main circuit also includes a voltage isolation circuit composed of diodes D1 and D2. Diode D1 is located between the emitter of NPN transistor Q5 and the negative terminal of the power supply. Diode D2 is connected in parallel across diode D1. The current conduction directions of diodes D1 and D2 are opposite. With this circuit, when the power supply is normal, a voltage difference is generated between diodes D4 and D1. The base voltage and emitter voltage of NPN transistor Q5 are approximately 0.7V, making Vbe = 0, and NPN transistor Q5 is in the off state. The non-conducting NPN transistor Q5 results in no current flowing to the base of PNP transistor Q3, causing the base voltage to equal the emitter voltage, and PNP transistor Q3 is in the off state. The gate of the MOSFET has no voltage, and the MOSFET is in the off state. The moment the power is disconnected, the motor quickly transforms into a generator, and the generator generates electricity. The current flows through diodes D4 and D2 to the negative terminal of the power supply, creating a voltage difference between them. The base voltage of NPN transistor Q5 is approximately 1.4V, and the emitter voltage is 0V, resulting in Vbe being approximately 1.4V. By controlling the values ​​of resistors R4, R1, and R2, Vbc can be controlled to be greater than 0, causing NPN transistor Q5 to saturate. When NPN transistor Q5 conducts, a voltage difference is created between the base and emitter of PNP transistor Q3, causing PNP transistor Q3 to conduct. When PNP transistor Q3 conducts, current flows through resistor R8, making the gate voltage of the MOSFET greater than the source voltage, thus turning on the MOSFET. The current from the motor flows directly from the positive terminal to the negative terminal through the MOSFET, forming a short circuit and achieving braking. In addition to reducing the voltage to ensure that transistor Q5 can switch on and off, the voltage isolation circuit can also optimize the circuit and ensure that the current can flow normally.

[0045] To enable the power failure detection circuit to control the on / off state of the energy release circuit for braking when POWER1 is connected to both the positive and negative terminals, this embodiment preferably includes a first power failure detection circuit for controlling the on / off state of the energy release circuit when the motor is rotating forward and a second power failure detection circuit for controlling the on / off state of the energy release circuit when the motor is rotating in reverse. By cooperating with the first and second power failure detection circuits, the power failure detection circuit can control the on / off state of the energy release circuit for braking when POWER1 is connected to both the positive and negative terminals.

[0046] To optimize the first and second power failure detection circuits, this embodiment preferably uses a PNP transistor Q3, an NPN transistor Q5, and a diode D4 for the first power failure detection circuit. In the PNP transistor Q3, its emitter is connected to the positive terminal of the power supply when the motor is rotating forward, its collector is connected to the gate of a MOSFET, and its base is connected to the collector of the NPN transistor Q5. In the NPN transistor Q5, its base is connected to the negative terminal of the power supply when the motor is rotating forward, and its emitter is connected to the negative terminal of the motor when the motor is rotating forward. The diode D4 is located in the circuit between the emitter of the NPN transistor Q5 and the negative terminal of the power supply when the motor is rotating forward to generate a voltage drop, ensuring that the NPN transistor Q5 is turned on.

[0047] The second power failure detection circuit consists of a PNP transistor Q4 and a diode D3. In the PNP transistor Q4, its emitter is connected to the positive terminal of the motor when the motor reverses, its collector is connected to the gate of the MOSFET, and its base is connected to the positive terminal of the power supply when the motor reverses. The diode D3 is located in the circuit between the base of the PNP transistor Q4 and the positive terminal of the power supply when the motor reverses to generate a voltage drop to ensure that the PNP transistor Q4 is turned on.

[0048] The main circuit also includes a voltage isolation circuit, which consists of diodes D1 and D2. Diode D1 is located in the circuit between the emitter of NPN transistor Q5 and the negative terminal of the power supply when the motor reverses, and in the circuit between the base of PNP transistor Q4 and the positive terminal of the power supply when the motor reverses. Diode D2 is connected in parallel across diode D1. The current conduction directions of diodes D1 and D2 are opposite. With this structure, when POWER1 is connected to the positive terminal and the motor rotates forward, the first power-off detection circuit controls the switching on and off of the MOSFET. When POWER1 is connected to the negative terminal and the motor reverses, the second power-off detection circuit controls the switching on and off of the MOSFET. This allows the power-off detection circuit to control the energy release circuit to achieve braking whether POWER1 is connected to the positive or negative terminal.

[0049] The voltage isolation circuits of the first and second power failure detection circuits can be combined, using only one voltage isolation circuit to power both power failure detection circuits. This optimizes the circuit structure and simplifies the circuit. In addition to generating voltage drops, diodes D4 and D3 ensure that current does not flow back when the motor rotates forward or in reverse, allowing the current to flow normally and the circuit to work properly. This also avoids R3 or R4 generating additional power consumption during motor operation.

[0050] To optimize the energy release circuit, this embodiment preferably includes an NMOS transistor Q2 connected to the first power-off detection circuit and an NMOS transistor Q1 connected to the second power-off detection circuit. The drains of NMOS transistor Q2 and NMOS transistor Q1 are connected in series, and the sources of NMOS transistor Q2 and NMOS transistor Q1 are respectively connected to the two ends of the motor so that NMOS transistors Q1 and Q2 are connected in parallel with respect to the motor. Both NMOS transistors Q1 and Q2 include a body diode to prevent the other from limiting current flow when one of NMOS transistors Q1 and Q2 is conducting. With this structure, NMOS transistors Q1 and Q2 can be connected to the first power-off detection circuit and the second power-off detection circuit respectively, so that the first power-off detection circuit and the second power-off detection circuit can function independently without interfering with each other. As can be seen from the characteristics of the body diode, when the motor rotates forward or reverse, the current direction is consistent with the current conduction direction of the body diode, which allows the MOS transistor to pass through, ensuring that the circuit can work normally.

[0051] To further optimize the circuit, in this embodiment, the base of the NPN transistor Q5 is preferably connected to the positive terminal of the power supply, and a resistor R4 is provided between its base and the positive terminal of the power supply. The base of the PNP transistor Q3 is connected to the positive terminal of the power supply, and a resistor R1 is provided between its base and the positive terminal of the power supply. A resistor R2 is provided between the base of the PNP transistor Q3 and the collector of the NPN transistor Q5. The collector of the PNP transistor Q3 is connected to the negative terminal of the motor, and a voltage divider resistor R6 is provided between the collector of the PNP transistor Q3 and the gate of the MOSFET. A voltage divider resistor R8 is provided between the gate and source of the MOSFET. Resistor R4 can be used to ensure... To ensure that POWER1 and POWER2 do not short-circuit, and to ensure that there is a voltage on the base of NPN transistor Q5, resistor R1 ensures that there is a voltage on the base of PNP transistor Q3. At the same time, resistor R1 can divide the voltage to ensure that the base voltage of PNP transistor Q3 is greater than its collector voltage. By adjusting the values ​​of resistor R1, R6, and R8, the base voltage of PNP transistor Q3 can be greater than its emitter voltage, so that PNP transistor Q3 can be turned on. The voltage difference between the gate and source of NMOS transistor Q2 can be adjusted by voltage divider resistors R6 and R8 to ensure that NMOS transistor Q2 is turned on.

[0052] To further optimize the circuit, in this embodiment, the base of the PNP transistor Q4 is preferably connected to the negative terminal of the power supply, and a resistor R3 is provided between the base and the negative terminal of the power supply. The collector of the PNP transistor Q4 is connected to the negative terminal of the motor, and a voltage divider resistor R5 is provided between the collector of the PNP transistor Q4 and the gate of the MOS transistor. A voltage divider resistor R7 is provided between the gate and source of the MOS transistor. Resistor R3 can ensure that POWER1 and POWER2 will not be short-circuited, while allowing voltage to be applied to the base of the PNP transistor Q4. The voltage divider resistors R5 and R7 can adjust the voltage difference between the gate and source of the NMOS transistor Q1 to ensure that the NMOS transistor Q1 is turned on.

[0053] Example 2:

[0054] The difference between this embodiment and Embodiment 1 is that, as Figure 3 As shown, in this embodiment, the power failure detection circuit consists of a PNP transistor Q4 and a diode D3. In the PNP transistor Q4, its emitter is connected to the positive terminal of the motor, its collector is connected to the gate of the MOSFET, and its base is connected to the positive terminal of the power supply. The diode D3 is located in the circuit between the base of the PNP transistor Q4 and the positive terminal of the power supply to generate a voltage drop to ensure that the PNP transistor Q4 is turned on.

[0055] The main circuit also includes a voltage isolation circuit, which consists of diodes D1 and D2. Diode D1 is located in the base circuit between the PNP transistor Q4 and the positive terminal of the power supply. Diode D2 is connected in parallel across diode D1. The current conduction directions of diodes D1 and D2 are opposite. With this structure, when the power supply is operating normally, POWER 2 is connected to the positive terminal of the power supply, and POWER 1 is connected to the negative terminal. Current flows from POWER 2 through diode D2 to the emitter of the PNP transistor Q4. Diode D2 generates a voltage difference, and simultaneously, the current from POWER 1... 2. The current flows through diode D3 to the base of PNP transistor Q4. Diode D3 also generates a voltage difference, making Vbe = 0, and PNP transistor Q4 is in the off state. The gate of the MOSFET has no voltage, and the MOSFET is in the off state. At the moment the power is disconnected, the motor quickly transforms into a generator, and the generator generates current. The current flows through diodes D1 and D3 to the base of PNP transistor Q4. At the same time, the current flows directly to the emitter of PNP transistor Q4. Diodes D1 and D3 generate a voltage difference, making the base voltage of PNP transistor Q4 less than the emitter voltage, and PNP transistor Q4 becomes saturated. When PNP transistor Q4 is turned on, the current flows through resistor R5, making the gate voltage of the MOSFET greater than the source voltage, and the MOSFET is turned on. The current generated by the motor flows directly from the positive terminal to the negative terminal through the MOSFET, forming a short circuit, thereby achieving braking. In addition to reducing the voltage to ensure that transistor Q4 can be switched on and off, the voltage isolation circuit can also optimize the circuit and ensure that the current can flow normally. This embodiment can also achieve the technical effect described in embodiment one.

[0056] Example 3:

[0057] The difference between this embodiment and Embodiment 1 is that in this embodiment, both the first power-off detection circuit and the second current detection circuit are composed of a PNP transistor Q3, an NPN transistor Q5, and a diode D4. In the PNP transistor Q3, its emitter is connected to the positive terminal of the power supply, its collector is connected to the gate of the MOSFET, and its base is connected to the collector of the NPN transistor Q5. In the NPN transistor Q5, its base is connected to the negative terminal of the power supply, and its emitter is connected to the negative terminal of the motor. The diode D4 is located in the circuit between the base of the NPN transistor Q5 and the negative terminal of the power supply to generate a voltage drop to ensure that the NPN transistor Q5 is turned on. The main circuit also includes a voltage isolation circuit, which is composed of diodes D1 and D2. Diode D1 is located in the circuit between the emitter of the NPN transistor Q5 and the negative terminal of the power supply, and diode D2 is connected in parallel across diode D1. The current conduction directions of diodes D1 and D2 are opposite. This embodiment can also achieve the technical effects described in Embodiment 1.

[0058] Example 4:

[0059] The difference between this embodiment and Embodiment 1 is that in this embodiment, both the first power-off detection circuit and the second current detection circuit are composed of a PNP transistor Q4 and a diode D3. In the PNP transistor Q4, its emitter is connected to the positive terminal of the motor, its collector is connected to the gate of the MOSFET, and its base is connected to the positive terminal of the power supply. The diode D3 is located in the circuit between the base of the PNP transistor Q4 and the positive terminal of the power supply to generate a voltage drop to ensure that the PNP transistor Q4 is turned on. The main circuit also includes a voltage isolation circuit, which is composed of diodes D1 and D2. The diode D1 is located in the circuit between the base of the PNP transistor Q4 and the positive terminal of the power supply, and the diode D2 is connected in parallel across the two ends of the diode D1. The current conduction directions of the diodes D1 and D2 are opposite. This embodiment can also achieve the technical effect described in Embodiment 1.

[0060] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments above. Any modifications that do not depart from the functional and structural principles of the present invention will be included within the scope of the claims.

Claims

1. An emergency stop self-locking circuit for a DC motor, characterized in that, include: The main circuit has its two ends connected to the positive and negative terminals of the power supply, respectively, and the motor is located within the main circuit to obtain electrical energy. Energy release circuit is used to control the motor to short-circuit so that the motor can be braked; A power failure detection circuit is used to control the disconnection of the energy release circuit when the power supply is on and to control the conduction of the energy release circuit when the power supply is off. The energy release circuit is composed of MOSFETs connected in parallel across the motor. The source and drain of the MOSFETs are respectively connected to the two ends of the motor. The power-off detection circuit is a switching circuit used to control the on / off state of the MOSFETs. The switching circuit is connected to the gate of the MOSFETs. When the power supply is on, the switching circuit is off, the gate of the MOSFETs has no voltage and is in the off state, and the motor rotates normally. When the power supply is off, the motor acts as a generator to provide current, the switching circuit is on, the gate of the MOSFETs has voltage and becomes saturated, and the current provided by the motor flows from the positive terminal through the MOSFETs in the energy release circuit to the negative terminal, causing a short circuit and forming short-circuit braking. The power failure detection circuit consists of a PNP transistor Q3, an NPN transistor Q5, and a diode D4. In the PNP transistor Q3, its emitter is connected to the positive terminal of the power supply, its collector is connected to the gate of the MOSFET, and its base is connected to the collector of the NPN transistor Q5. In the NPN transistor Q5, its base is connected to the negative terminal of the power supply through diode D4, and its emitter is connected to the negative terminal of the motor. Diode D4 is located in the circuit between the base of the NPN transistor Q5 and the negative terminal of the power supply to generate a voltage drop, ensuring that the NPN transistor Q5 is turned on. The main circuit also includes a voltage isolation circuit, which consists of diodes D1 and D2. Diode D1 is located in the circuit between the emitter of the NPN transistor Q5 and the negative terminal of the power supply, and diode D2 is connected in parallel across diode D1. The current conduction directions of diodes D1 and D2 are opposite. Alternatively, the power failure detection circuit may consist of a PNP transistor Q4 and a diode D3. In the PNP transistor Q4, its emitter is connected to the positive terminal of the motor, its collector is connected to the gate of the MOSFET, and its base is connected to the positive terminal of the power supply through the diode D3. The diode D3 is located in the circuit between the base of the PNP transistor Q4 and the positive terminal of the power supply to generate a voltage drop to ensure that the PNP transistor Q4 is turned on. The main circuit also includes a voltage isolation circuit, which consists of diodes D1 and D2. Diode D1 is located in the circuit between the emitter of the PNP transistor Q4 and the positive terminal of the power supply, and diode D2 is connected in parallel across diode D1. The current conduction directions of diodes D1 and D2 are opposite.

2. An emergency stop self-locking circuit for a DC motor, characterized in that: include: The main circuit has its two ends connected to the positive and negative terminals of the power supply, respectively, and the motor is located within the main circuit to obtain electrical energy. Energy release circuit is used to control the motor to short-circuit so that the motor can be braked; A power failure detection circuit is used to control the disconnection of the energy release circuit when the power supply is on and to control the conduction of the energy release circuit when the power supply is off. The energy release circuit is composed of MOSFETs connected in parallel across the motor. The source and drain of the MOSFETs are respectively connected to the two ends of the motor. The power-off detection circuit is a switching circuit used to control the on / off state of the MOSFETs. The switching circuit is connected to the gate of the MOSFETs. When the power supply is on, the switching circuit is off, the gate of the MOSFETs has no voltage and is in the off state, and the motor rotates normally. When the power supply is off, the motor acts as a generator to provide current, the switching circuit is on, the gate of the MOSFETs has voltage and becomes saturated, and the current provided by the motor flows from the positive terminal through the MOSFETs in the energy release circuit to the negative terminal, causing a short circuit and forming short-circuit braking. The power failure detection circuit includes a first power failure detection circuit for controlling the on / off state of the energy release circuit when the motor rotates forward and a second power failure detection circuit for controlling the on / off state of the energy release circuit when the motor rotates in reverse. The first power failure detection circuit consists of a PNP transistor Q3, an NPN transistor Q5, and a diode D4. In the PNP transistor Q3, its emitter is connected to the positive terminal of the power supply when the motor is rotating forward, its collector is connected to the gate of the MOSFET, and its base is connected to the collector of the NPN transistor Q5. In the NPN transistor Q5, its base is connected to the negative terminal of the power supply when the motor is rotating forward through the diode D4, and its emitter is connected to the negative terminal of the motor when the motor is rotating forward. The diode D4 is located in the circuit between the base of the NPN transistor Q5 and the negative terminal of the power supply when the motor is rotating forward to generate a voltage drop to ensure that the NPN transistor Q5 is turned on. The second power failure detection circuit consists of a PNP transistor Q4 and a diode D3. In the PNP transistor Q4, its emitter is connected to the positive terminal of the motor when the motor is in reverse, its collector is connected to the gate of the MOSFET, and its base is connected to the positive terminal of the power supply when the motor is in reverse through the diode D3. The diode D3 is located in the circuit between the base of the PNP transistor Q4 and the positive terminal of the power supply when the motor is in reverse to generate a voltage drop to ensure that the PNP transistor Q4 is turned on. The main circuit also includes a voltage isolation circuit, which consists of diodes D1 and D2. Diode D1 is located in the circuit between the emitter of NPN transistor Q5 and the negative terminal of the power supply when the motor reverses, and in the circuit between the base of PNP transistor Q4 and the positive terminal of the power supply when the motor reverses. Diode D2 is connected in parallel across diode D1, and the current conduction directions of diodes D1 and D2 are opposite.

3. The emergency stop self-locking circuit for a DC motor as described in claim 2, characterized in that: The MOS transistors include an NMOS transistor Q2 connected to a first power-off detection circuit and an NMOS transistor Q1 connected to a second power-off detection circuit. The drains of the NMOS transistor Q2 and the NMOS transistor Q1 are connected in series. The sources of the NMOS transistor Q2 and the NMOS transistor Q1 are respectively connected to the two ends of the motor so that the NMOS transistors Q1 and Q2 are connected in parallel with respect to the motor. Both the NMOS transistors Q1 and Q2 include a body diode to prevent the other from limiting current flow when one of the NMOS transistors Q1 and Q2 is turned on.

4. The emergency stop self-locking circuit for a DC motor as described in claim 1, characterized in that: The base of the NPN transistor Q5 is connected to the positive terminal of the power supply, and a resistor R4 is provided between the base and the positive terminal of the power supply. The base of the PNP transistor Q3 is connected to the positive terminal of the power supply, and a resistor R1 is provided between the base and the positive terminal of the power supply. A resistor R2 is provided between the base of the PNP transistor Q3 and the collector of the NPN transistor Q5. The collector of the PNP transistor Q3 is connected to the negative terminal of the motor through series resistors R6 and R8. A voltage divider resistor R6 is provided between the collector of the PNP transistor Q3 and the gate of the MOSFET. A voltage divider resistor R8 is provided between the gate and the source of the MOSFET.

5. The emergency stop self-locking circuit for a DC motor as described in claim 1, characterized in that: The base of the PNP transistor Q4 is connected to the negative terminal of the power supply, and a resistor R3 is provided between the base and the negative terminal of the power supply. The collector of the PNP transistor Q4 is connected to the negative terminal of the motor through series resistors R5 and R7. A voltage divider resistor R5 is provided between the collector of the PNP transistor Q4 and the gate of the MOS transistor, and a voltage divider resistor R7 is provided between the gate and the source of the MOS transistor.

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