Overload protection circuit and motor system

Abstract

The embodiment of the invention discloses an overload protection circuit which is applied to the technical field of motor protection. The overload protection circuit comprises an overload protection circuit power supply, a motor common power supply, a motor power supply control circuit and an overload feedback circuit, and the motor power supply control circuit comprises a relay switch sub-circuit and a relay switch control sub-circuit. A common power supply of the motors supplies power to each motor after passing through each motor power supply control circuit in the overload protection circuit; when a certain motor is overloaded, the relay switch control sub-circuit in the motor power supply control circuit corresponding to the motor can be used for controlling the relay switch sub-circuit to cut off the connection between the motor common power supply and the motor power supply input end, so that the motor is shut down, and meanwhile, the relay switch control sub-circuit enters a self-locking state; and the overload feedback circuit feeds back overload fault information of the motor, so that overload protection of the motor is realized.

Description

Technical Field

[0001] This application relates to the field of motor protection technology, and in particular to an overload protection circuit and motor system. Background Technology

[0002] If a motor's own output is insufficient or the external load is too heavy during operation, the actual load on the motor will exceed its rated output capacity, causing the motor to operate under overload. If the motor operates under overload for a prolonged period of time, the internal current will increase, the temperature will rise, and eventually the motor will burn out.

[0003] In existing technologies, an electrical system often contains multiple motors. To prevent a motor from overloading, it is usually necessary to disconnect the power supply to that motor and lock it in a stopped state (i.e., automatic reset is not allowed, manual reset is required) to achieve overload protection. To achieve automated overload protection for a motor, thermal relays are usually added to the outside of each motor. The thermal relays can feed back signals to the main controller of the system by switching on or off whether the current is abnormal. Alternatively, current sensors can be added to monitor the current data of each motor and feed back signals to the main controller of the system. The main controller then controls the contactor to disconnect the power supply to that motor to achieve overload protection. Or, a dedicated motor protector integrating hardware and software functions can be used to provide overload protection for each motor in the system based on auxiliary contacts.

[0004] The above solution requires the addition of external hardware units (such as relays, current sensors, etc.) and corresponding software control terminals (main controllers) or dedicated motor protectors that integrate software and hardware functions to achieve motor overload protection. However, as the number of motors in the motor system increases, the corresponding software and hardware supporting facilities will also increase, the wiring and control programs will be complex and costly, and bugs or crashes are prone to occur when controlling the power supply shutdown and self-locking through the software control terminal, affecting the stability of the motor system. Summary of the Invention

[0005] This application provides an overload protection circuit and a motor system that can protect a motor from overload.

[0006] In a first aspect, embodiments of this application provide an overload protection circuit, which includes: an overload protection circuit power supply, a motor common power supply, a fault reset switch, a motor power control circuit, and an overload feedback circuit.

[0007] The motor power supply control circuit includes: a relay switch sub-circuit and a relay switch control sub-circuit;

[0008] The relay switch control sub-circuit includes: an overload signal sub-switch, a first resistor, a first capacitor, a first inverter, a second resistor, a second capacitor, a second inverter, a third inverter, a third resistor, a first diode, and a third diode;

[0009] The motor's common power supply is connected to the motor power supply via the relay switch of the relay switch sub-circuit. One end of the overload signal sub-switch is connected to the overload protection circuit power supply, and the other end of the overload signal sub-switch is connected to one end of the first resistor. The overload signal sub-switch is also connected to the motor's overload feedback point. The other end of the first resistor, one end of the third resistor, and one end of the first capacitor are all connected to the input terminal of the first inverter. The other end of the third resistor and the other end of the first capacitor are grounded. The first output terminal of the relay switch sub-circuit and one end of the second resistor are all connected to the output terminal of the first inverter. The other end of the second resistor, one end of the second capacitor, and the anode of the third diode are all connected to the input terminal of the second inverter. The other end of the second capacitor is grounded. The output terminal of the second inverter is connected to the input terminal of the third inverter. The output terminal of the second inverter is also connected to the input terminal of the first inverter. The second output terminal of the relay switch sub-circuit and the anode of the first diode are all connected to the output terminal of the third inverter. The cathode of the first diode is connected to the output terminal of the overload feedback circuit, and the input terminal of the overload feedback circuit is connected to the overload protection circuit power supply.

[0010] Furthermore, the relay switch sub-circuit of the motor power control circuit includes: a first relay, a second relay, a third relay, and a power input pin;

[0011] The first phase input terminal of the three-phase input terminal of the motor common power supply is connected to the first phase input terminal of the motor power supply via the switch of the first relay; the second phase input terminal of the three-phase input terminal of the motor common power supply is connected to the second phase input terminal of the motor power supply via the switch of the second relay; the third phase input terminal of the three-phase input terminal of the motor common power supply is connected to the third phase input terminal of the motor power supply via the switch of the third relay.

[0012] The power input pin is connected to the output terminal of the overload protection circuit power supply. One end of the coil of the first relay, one end of the coil of the second relay, and one end of the coil of the third relay are all connected to the power input pin. The other end of the coil of the first relay, the other end of the coil of the second relay, and the other end of the coil of the third relay are all connected to the output terminal of the first inverter of the motor power control circuit.

[0013] Furthermore, the overload feedback circuit includes: a sixth resistor, a fourth relay, a fourth inverter, a fifth inverter, a third capacitor, a fourth capacitor, and a seventh resistor;

[0014] One end of the sixth resistor and one end of the coil of the fourth relay are connected to the power supply of the overload protection circuit. The other end of the coil of the fourth relay is connected to the output terminal of the fifth inverter. The other end of the sixth resistor, the output terminal of the fourth inverter, and one end of the third capacitor are connected to the input terminal of the fifth inverter. The other end of the third capacitor is grounded. One end of the fourth capacitor and one end of the seventh resistor are connected to the input terminal of the fourth inverter. The other end of the fourth capacitor and the other end of the seventh resistor are grounded.

[0015] When no overload fault occurs, the fourth relay contact closes;

[0016] When an overload fault occurs, the contacts of the fourth relay disconnect.

[0017] Furthermore, the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter all include a pull-down switch unit;

[0018] One end of the pull-down switch unit of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter is grounded; the other end of the pull-down switch unit of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter is connected to the output terminal of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter respectively; the switching state of the pull-down switch unit of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter is controlled by the corresponding input terminal of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter.

[0019] When the input terminals of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter are at a high level, the corresponding pull-down switch unit is turned on, so that the output terminals of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter are grounded through the pull-down switch unit, and are in a low impedance state;

[0020] When the input terminals of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter are at a low level, the corresponding pull-down switch unit is turned off, so that the output terminals of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter are disconnected from the ground point and are in a high impedance state.

[0021] Furthermore, the resistor-capacitor time constant of the first inverter input terminal of the motor power control circuit is determined based on the first resistor and the first capacitor.

[0022] The resistor-capacitor time constant at the input of the second inverter in the motor power control circuit is determined based on the second resistor and the second capacitor.

[0023] The time constant of the resistor-capacitor at the input of the first inverter is less than the time constant of the resistor-capacitor at the input of the second inverter.

[0024] Furthermore, the overload signal sub-switch is also connected to the overload feedback point of the motor;

[0025] The signal fed back by the overload feedback point is a motor overload signal, and the overload signal sub-switch is turned off.

[0026] The signal fed back by the overload feedback point is a non-overload signal for the motor, and the overload signal sub-switch is turned on.

[0027] Furthermore, when the input terminal of the first inverter is at a high level, the output terminal of the first inverter is in a low impedance state, and the relay switch of the relay switch sub-circuit is turned on so that the motor common power supply can supply power to the motor power supply normally.

[0028] When the input terminal of the first inverter is at a low level, the output terminal of the first inverter is in a high impedance state, and the relay switch of the relay switch sub-circuit is turned off, so that the motor common power supply stops supplying power to the motor power supply.

[0029] When the input of the second inverter is at a high level, the output of the second inverter is in a low impedance state. The output of the second inverter is connected to the output of the first inverter, which forces the input potential of the first inverter to be low so that the input potential of the first inverter remains unchanged. The relay switch control sub-circuit then enters a self-locking state.

[0030] Furthermore, the overload protection circuit also includes: a fault reset switch;

[0031] After the relay switch control subcircuit enters the self-locking state, if the fault reset switch is triggered, the input terminal of the second inverter is grounded through the third diode, and the input terminal of the first inverter is disconnected from the output terminal of the second inverter, so as to release the self-locking state of the relay switch control subcircuit.

[0032] Furthermore, the motor power control circuit also includes a fault indication circuit;

[0033] The fault indication circuit includes a fifth resistor and an LED diode. One end of the fifth resistor is connected to the input terminal of the first inverter, and the other end of the fifth resistor is connected to the anode of the LED diode. The cathode of the LED diode is grounded.

[0034] The LED diode is configured to indicate motor overload.

[0035] Secondly, embodiments of this application also provide a motor system including multiple motor units. The common power supply of the motor units is connected to the power input terminal of each motor unit through an overload protection circuit, and the overload protection circuit described above is used for motor overload protection.

[0036] As can be seen from the above technical solutions, the embodiments of this application have the following advantages:

[0037] This application embodiment incorporates an overload protection circuit within the motor system. When a motor is overloaded, the corresponding relay switch control subcircuit controls the relay switch subcircuit to disconnect the motor's common power supply from its power input terminal, thus stopping the motor. Simultaneously, the relay switch control subcircuit enters a self-locking state, completing the overload protection for the motor. In the process of overload protection, only the corresponding hardware circuit needs to be added; no software control is required. Furthermore, the hardware circuit is simple, uses low-cost electronic components, and avoids the bugs or crashes associated with software control. Therefore, this application embodiment can achieve a low-cost, highly stable automated overload protection function for the motor system. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0039] Figure 1 This is a circuit diagram of an overload protection circuit disclosed in an embodiment of this application;

[0040] Figure 2This is a circuit diagram of a motor power supply control circuit for an overload protection circuit disclosed in an embodiment of this application;

[0041] Figure 3 This is an overload feedback circuit diagram of an overload protection circuit disclosed in an embodiment of this application;

[0042] Figure 4 This is a fault indication circuit diagram of an overload protection circuit disclosed in an embodiment of this application. Detailed Implementation

[0043] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0044] In the description of the embodiments of this application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0045] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0046] If a motor operates under overload for an extended period, the internal current and temperature of the motor will increase, eventually burning out the motor. An electrical system often contains multiple motors. To prevent a particular motor from overloading, it is usually necessary to disconnect the power supply to that motor and enable self-locking to lock the overloaded motor in a stopped state (i.e., automatic reset is not allowed; manual reset is required) to achieve overload protection. Currently, to achieve automated overload protection for a motor, thermal relays are typically added externally to each motor. These relays can send signals to the main controller of the system by switching on or off to indicate abnormal current conditions. Alternatively, current sensors can be added to monitor the current data of each motor and send signals back to the main controller. The main controller then controls a contactor to cut off the power supply to that motor, thus achieving overload protection. Another approach is to use a dedicated motor protector with integrated hardware and software functions, based on auxiliary contacts, to provide overload protection for each motor in the system. However, these overload protection methods require the addition of external hardware units (such as relays and current sensors) and corresponding software control terminals (main controllers) or dedicated motor protectors with integrated hardware and software functions to achieve motor overload protection. As the number of motors in the system increases, the corresponding hardware and software support also increases, leading to complex wiring and control programs, higher costs, and the potential for bugs or system crashes when controlling power shutdown and self-locking via software, affecting the stability of the motor system. Therefore, this application provides an overload protection circuit for overload protection of each motor in a motor system.

[0047] In the embodiments of this application, such as Figure 1 As shown, the overload protection circuit 10 may specifically include: an overload protection circuit power supply CN1, a motor common power supply CN2, a fault reset switch KEY1, a motor power control circuit 20, and an overload feedback circuit 30;

[0048] The +12V power output terminal of the overload protection circuit power supply CN1 can be connected to each of the +12V power input pins shown in the figure (the connection lines are not shown in the figure).

[0049] For a clearer understanding, please refer to the motor power control circuit 20. Figure 2 As shown, the motor power control circuit 20 includes: a relay switch sub-circuit 201 and a relay switch control sub-circuit 202, wherein the motor power control circuit 20 can be multiple ( Figure 1 It includes two motor power control circuits 20), one motor power control circuit 20 controls the power supply of one motor;

[0050] The relay switch sub-circuit 201 includes: a first relay RLY1, a second relay RLY2, a third relay RLY3, a fourth resistor R4, and a 12V power input pin; the relay switch control sub-circuit 202 includes: an overload signal sub-switch CN4, a first resistor R1, a first capacitor C1, a first inverter U1, a second resistor R2, a second capacitor C2, a second inverter U2, a third inverter U3, a third resistor R3, a first diode D1, and a third diode D3.

[0051] The first phase input terminal of the three-phase input terminal of the motor common power supply CN2 is connected to the first phase input terminal of the motor power supply input terminal via the switch of the first relay RLY1; the second phase input terminal of the three-phase input terminal of the motor common power supply CN2 is connected to the second phase input terminal of the motor power supply input terminal via the switch of the second relay RLY2; the third phase input terminal of the three-phase input terminal of the motor common power supply CN2 is connected to the third phase input terminal of the motor power supply input terminal via the switch of the third relay RLY3; the power input pin is connected to the output terminal of the overload protection circuit power supply CN1; one end of the coil of the first relay RLY1, one end of the coil of the second relay RLY2, one end of the coil of the third relay RLY3 and one end of the fourth resistor R4 are connected to the power input pin; the other end of the coil of the first relay RLY1, the other end of the coil of the second relay RLY2 and the other end of the coil of the third relay RLY3 together serve as the first output terminal of the relay switch sub-circuit 201 and are connected to the output terminal of the first inverter U1 of the motor power control circuit 20; the other end of the fourth resistor R4 serves as the second output terminal of the relay switch sub-circuit 201.

[0052] The aforementioned relay switch sub-circuit 201 is used to control the motor common power supply CN2 to supply power to the motor power supply through the relay switch. It can be understood that the number of relay switches can be adjusted based on the number of phases output by the motor common power supply CN2. For example, when the motor common power supply CN2 has only one phase output, the relay switch can be set to one. No specific restrictions are imposed here.

[0053] One end of the overload signal sub-switch CN4 is connected to the overload protection circuit power supply CN1, and the other end of the overload signal sub-switch CN4 is connected to one end of the first resistor R1. The other end of the first resistor R1, one end of the third resistor R3, and one end of the first capacitor C1 are all connected to the input terminal of the first inverter U1. The other end of the third resistor R3 and the other end of the first capacitor C1 are grounded. The first output terminal of the relay switch sub-circuit 201 (i.e., the coil end of the first relay RLY1 coil, the second relay RLY2 coil, and the third relay RLY3 coil closest to the output terminal of the first inverter U1) and one end of the second resistor R2 are all connected to the output terminal of the first inverter U1. The other end of the second resistor R2, one end of the second capacitor C2, and the first... The anodes of the three diodes D3 are connected to the input terminal of the second inverter U2. The other end of the second capacitor C2 is grounded. The cathode of the third diode D3 is grounded after passing through the fault reset switch KEY1. The output terminal of the second inverter U2 is connected to the input terminal of the third inverter U3. The output terminal of the second inverter U2 is also connected to the input terminal of the first inverter U1. The second output terminal of the relay switch sub-circuit 201 (i.e., one end of the fourth resistor R4) and the anode of the first diode D1 are connected to the output terminal of the third inverter U3. The cathode of the first diode D1 is connected to the input terminal of the fourth inverter U4 (i.e., the output terminal of the overload feedback circuit 30). The second output terminal of the relay switch sub-circuit 201 is connected to the input terminal of the overload feedback circuit 30.

[0054] The aforementioned relay switch control sub-circuit 202 can be used to control the relay switch state of the relay switch sub-circuit 201 based on the different switch states of the overload signal sub-switch CN4, so as to determine whether the motor common power supply CN2 supplies power to the motor. The above process does not require software control and can be implemented according to the corresponding hardware circuit. Furthermore, the wiring of the relevant circuit is simple, the electronic components are low-cost, and it is easy to implement.

[0055] For easier understanding, please refer to the specific overload feedback circuit 30. Figure 3 As shown, the overload feedback circuit 30 includes: a sixth resistor R6, a fourth relay RLY4, a fourth inverter U4, a fifth inverter U5, a third capacitor C3, a fourth capacitor C4, and a seventh resistor R7.

[0056] One end of the sixth resistor R6 and one end of the coil of the fourth relay RLY4 are connected to the overload protection circuit power supply CN1. Figure 1One end of the sixth resistor R6 and one end of the coil of the fourth relay RLY4 can be connected to the overload protection circuit power supply CN1 through the power input pin of the relay switch sub-circuit 201. The other end of the coil of the fourth relay RLY4 is connected to the output terminal of the fifth inverter U5. The other end of the sixth resistor R6, the output terminal of the fourth inverter U4, and one end of the third capacitor C3 are connected to the input terminal of the fifth inverter U5. The other end of the third capacitor C3 is grounded. One end of the fourth capacitor C4 and one end of the seventh resistor R7 are connected to the input terminal of the fourth inverter U4. The other end of the fourth capacitor C4 and the other end of the seventh resistor R7 are grounded.

[0057] The overload feedback circuit 30 described above can determine whether there is an overload fault in the motor in the entire overload protection circuit based on whether the output terminal of the corresponding third inverter U3 in the motor power control circuit 20 for each motor is in a high impedance state.

[0058] Furthermore, the inverters used in this embodiment (i.e., the first inverter U1, the second inverter U2, the third inverter U3 in the motor power control circuit 20, and the fourth inverter U4 and the fifth inverter U5 in the overload feedback circuit 30) include a pull-down switch unit. One end of the pull-down switch unit is grounded, and the other end is connected to the output terminal of the inverter. The switching state of the pull-down switch unit is controlled by the input terminal of the inverter. When the input terminal of the inverter is high, the pull-down switch unit is turned on, and the output terminal of the inverter is grounded through the pull-down switch unit, exhibiting a low impedance state. When the output terminal of the inverter is low, the pull-down switch unit is turned off, and the output terminal of the inverter is disconnected from the ground point, exhibiting a high impedance state.

[0059] It is understood that the inverter in the embodiments of this application is an open-drain output or open-collector output inverter. The inverter can be a transistor, MOSFET, Darlington transistor, or an integrated circuit with similar functions, and there are no specific limitations here.

[0060] Specifically, in this embodiment of the application, when the motor is running normally, the overload signal sub-switch CN4 in the corresponding motor power control circuit 20 is in the on state. The potential of the first capacitor C1 is in a high-level state due to the influence of the overload protection circuit power supply CN1, that is, the input terminal of the first inverter U1 is at a high level. The pull-down switch unit of the first inverter U1 is turned on, and the output terminal of the first inverter U1 is grounded through the pull-down switch unit, which is in a low-impedance state. The relays in the relay switch sub-circuit 201 are energized, that is, the relays are in the on state. The motor common power supply C N2 supplies power to the motor normally. The input of the second inverter U2 is at a low level, and the output of the second inverter U2 is in a high impedance state. The output of the second inverter U2 has no effect on the input of the first inverter U1. The input of the third inverter U3 is at the same potential as the input of the first inverter U1, both at a high level. The output of the third inverter U3 is grounded and is in a low impedance state. The current in the second output of the relay switch sub-circuit 201 (i.e., the end of the fourth resistor R4 closest to the third inverter U3) flows to the output of the third inverter U3.

[0061] If all motors are operating normally, the output terminals of the corresponding third inverter U3 in the motor power control circuit 20 are all grounded. The input terminal of the fourth inverter U4 in the overload feedback circuit 30 is at a low level, and the output terminal of the fourth inverter U4 is disconnected from the ground point, exhibiting a high impedance state. The input terminal of the fifth inverter U5 is at a high level due to the influence of the 12V power input pin through the branch of the sixth resistor R6. The output terminal of the fifth inverter U5 is grounded, exhibiting a low impedance state. The fourth relay RLY4 is energized. At this time, the fault signal output by the overload feedback circuit 30 does not indicate a motor overload fault.

[0062] When the motor is overloaded, the overload signal switch in the corresponding motor power control circuit 20 is in the off state. The voltage of the first capacitor C1 discharges through the third resistor R3, making the input terminal of the first inverter U1 low level. The output terminal of the first inverter U1 is disconnected from the ground point and is in a high impedance state. All relay switches in the relay switch sub-circuit 201 are disconnected, and the motor common power supply CN2 stops supplying power to the motor power supply. The first output terminal of the relay switch sub-circuit 201 (i.e., the coil terminal closest to the output terminal of the first inverter U1 among the coils of the first relay RLY1, the second relay RLY2, and the third relay RLY3) charges the second capacitor C2 through the second resistor R2, making the input terminal of the second inverter U2 high level. The output terminal of the second inverter U2 is grounded because the output terminal of the second inverter U2 is connected to the first inverter U1. The input terminal of the first inverter U1 is forced low. Even if the overload signal switch is turned on again, the input terminal of the first inverter U1 is still at a low level, thus achieving self-locking. The input terminal of the third inverter U3 is also at a low level. The output terminal of the third inverter U3 is disconnected from the ground point and is in a high impedance state. At this time, the output current of the second output terminal of the relay switch sub-circuit 201 (i.e., the end of the fourth resistor R4 close to the third inverter U3) charges the fourth resistor R4 in the overload feedback circuit 30, so that the input terminal of the fourth resistor R4 is at a high level and the output terminal of the fourth resistor R4 is grounded and is in a low impedance state. The input terminal of the fifth inverter U5 is at a low level and the output terminal of the fifth inverter U5 is disconnected from the ground point. The switch terminal of the fourth relay RLY4 is disconnected. At this time, the fault signal output by the overload feedback circuit 30 is that there is a motor overload fault.

[0063] In this embodiment, the resistor-capacitor time constant at the input terminal of the first inverter U1 can be determined by the first resistor R1 and the first capacitor C1; the resistor-capacitor time constant at the input terminal of the second inverter U2 can be determined by the second resistor R2 and the second capacitor C2; the resistor-capacitor time constant at the input terminal of the first inverter U1 is less than the resistor-capacitor time constant at the input terminal of the second inverter U2.

[0064] When the circuit is not powered on, each inverter is in a high impedance state. When the overload signal sub-switch CN4 is in the conducting state, and power is applied, the first capacitor C1 and the second capacitor C2 will be charged simultaneously. By setting the time constant of the resistor-capacitor at the input of the first inverter U1 to be less than the time constant of the resistor-capacitor at the input of the second inverter U2, it can be ensured that the voltage at the input of the first inverter U1 rises to the high level corresponding to the inverter first. This prevents the second inverter U2 from forcibly pulling down the input potential of the first inverter U1 when the motor is in normal operation (i.e., when the overload signal sub-switch CN4 is in the conducting state), causing the entire relay switch control sub-circuit 202 to enter a self-locking state (i.e., the input potential of the first inverter U1 is not affected by the overload signal switch state and is always in a low level state, so that the relay switch control sub-circuit 202 always controls the relay switch in the relay switch sub-circuit 201 to be in the off state).

[0065] Furthermore, when the relay switch control sub-circuit 202 enters the self-locking state, the self-locking state of the relay switch control sub-circuit 202 can be released by manually pressing the fault reset switch KEY1 when the overload protection circuit is energized: After pressing the fault reset switch KEY1, the third diode D3 is grounded, the potential of the second capacitor C2 is pulled low, that is, the input terminal of the second inverter U2 is at a low level, the output terminal of the second inverter U2 is disconnected from the ground point and is in a high impedance state, the output terminal of the second inverter U2 and the input terminal of the first inverter U1 are open circuit, the potential of the input terminal of the first inverter U1 is no longer forcibly pulled low by the output terminal of the second inverter U2, the on / off state of the overload signal switch can affect the potential of the input terminal of the first inverter U1 again, and the self-locking state of the relay switch control sub-circuit 202 is released.

[0066] Furthermore, after the relay switch control sub-circuit 202 enters the self-locking state, it can also be de-energized, thereby making the input terminal of the second inverter U2 low level, the output terminal of the second inverter U2 disconnected from the ground point and in a high-impedance state, and the output terminal of the second inverter U2 and the input terminal of the first inverter U1 open circuit. The potential of the input terminal of the first inverter U1 is no longer forcibly pulled low by the output terminal of the second inverter U2. The on / off state of the overload signal switch can affect the potential of the input terminal of the first inverter U1 again, and the self-locking state of the relay switch control sub-circuit 202 is released.

[0067] The self-locking and unlocking processes described above are controlled by hardware circuitry, eliminating the need for corresponding software control and preventing software control bugs or crashes, thus ensuring high stability.

[0068] In this embodiment, the overload signal sub-switch CN4 can be connected to the overload feedback point of the motor, such as the three-phase winding temperature feedback point of the motor. When the temperature of the three-phase winding of the motor is not greater than the overload three-phase winding temperature threshold of the motor (i.e., the signal fed back based on the temperature overload feedback point is a non-overload signal of the motor), the overload signal sub-switch CN4 is in the conducting state, and the motor common power supply CN2 supplies power to the motor normally. When the temperature of the three-phase winding of the motor is greater than the overload three-phase winding temperature threshold of the motor (i.e., the signal fed back based on the temperature overload feedback point is a motor overload signal), the overload signal sub-switch CN4 will be turned off, thereby providing overload protection for the overloaded motor based on the overload protection circuit of this embodiment.

[0069] It is understood that the overload signal sub-switch CN4 can also provide overload feedback based on other physical quantities related to motor overload, such as current, voltage, and speed, thereby controlling the overload signal sub-switch to turn on or off, and then providing overload protection for the overloaded motor based on the overload protection circuit in this embodiment. The specific overload feedback settings corresponding to the overload signal sub-switch CN4 are not limited here.

[0070] See Figure 4 The motor power control circuit 20 provided in this application embodiment may further include a fault indication circuit 40, which includes: a fifth resistor R5 and an LED diode LED1;

[0071] In this circuit, one end of the fifth resistor R5 is connected to the input terminal of the first inverter U1, and the other end of the fifth resistor R5 is connected to the anode of the LED diode LED1. The cathode of the LED diode LED1 is grounded. One motor corresponds to one fault indication circuit. When the motor is running normally, the overload signal sub-switch CN4 is turned on, and the LED diode LED1 lights up, indicating that the motor is running normally. When the motor is overloaded, the overload signal sub-switch CN4 is turned off, and the LED diode LED1 goes out, indicating that the motor has an overload fault.

[0072] When an overload fault occurs in a certain motor, the specific motor with the overload fault can be identified through the corresponding motor overload indicator circuit.

[0073] This application embodiment also provides a motor system, which includes multiple motor units. The common power supply of the motor units is connected to the motor power input terminal of each motor unit through the above-mentioned overload protection circuit, and the motor is protected from overload through the above-mentioned overload protection circuit.

[0074] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0075] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between apparatuses or units through some interfaces, and may be electrical, mechanical, or other forms.

[0076] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0077] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0078] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

Claims

1. An overload protection circuit, characterized in that, The overload protection circuit includes: an overload protection circuit power supply, a motor common power supply, a motor power supply control circuit, and an overload feedback circuit. The motor power supply control circuit includes: a relay switch sub-circuit and a relay switch control sub-circuit; The relay switch control sub-circuit includes: an overload signal sub-switch, a first resistor, a first capacitor, a first inverter, a second resistor, a second capacitor, a second inverter, a third inverter, a third resistor, a first diode, and a third diode; The motor's common power supply is connected to the motor power supply via the relay switch of the relay switch sub-circuit. One end of the overload signal sub-switch is connected to the overload protection circuit power supply, and the other end of the overload signal sub-switch is connected to one end of the first resistor. The overload signal sub-switch is also connected to the motor's overload feedback point. The other end of the first resistor, one end of the third resistor, and one end of the first capacitor are all connected to the input terminal of the first inverter. The other end of the third resistor and the other end of the first capacitor are grounded. The first output terminal of the relay switch sub-circuit and one end of the second resistor are all connected to the output terminal of the first inverter. The other end of the second resistor, one end of the second capacitor, and the anode of the third diode are all connected to the input terminal of the second inverter. The other end of the second capacitor is grounded. The output terminal of the second inverter is connected to the input terminal of the third inverter. The output terminal of the second inverter is also connected to the input terminal of the first inverter. The second output terminal of the relay switch sub-circuit and the anode of the first diode are all connected to the output terminal of the third inverter. The cathode of the first diode is connected to the output terminal of the overload feedback circuit, and the input terminal of the overload feedback circuit is connected to the overload protection circuit power supply.

2. The overload protection circuit according to claim 1, characterized in that, The relay switch sub-circuit of the motor power control circuit includes: a first relay, a second relay, a third relay, and a power input pin; The first phase input terminal of the three-phase input terminal of the motor common power supply is connected to the first phase input terminal of the motor power supply via the switch of the first relay; the second phase input terminal of the three-phase input terminal of the motor common power supply is connected to the second phase input terminal of the motor power supply via the switch of the second relay; the third phase input terminal of the three-phase input terminal of the motor common power supply is connected to the third phase input terminal of the motor power supply via the switch of the third relay. The power input pin is connected to the output terminal of the overload protection circuit power supply. One end of the coil of the first relay, one end of the coil of the second relay, and one end of the coil of the third relay are all connected to the power input pin. The other end of the coil of the first relay, the other end of the coil of the second relay, and the other end of the coil of the third relay are all connected to the output terminal of the first inverter of the motor power control circuit.

3. The overload protection circuit according to claim 1, characterized in that, The overload feedback circuit includes: a sixth resistor, a fourth relay, a fourth inverter, a fifth inverter, a third capacitor, a fourth capacitor, and a seventh resistor; One end of the sixth resistor and one end of the coil of the fourth relay are connected to the power supply of the overload protection circuit. The other end of the coil of the fourth relay is connected to the output terminal of the fifth inverter. The other end of the sixth resistor, the output terminal of the fourth inverter, and one end of the third capacitor are connected to the input terminal of the fifth inverter. The other end of the third capacitor is grounded. One end of the fourth capacitor and one end of the seventh resistor are connected to the input terminal of the fourth inverter. The other end of the fourth capacitor and the other end of the seventh resistor are grounded. When no overload fault occurs, the fourth relay contact closes; When an overload fault occurs, the contacts of the fourth relay disconnect.

4. The overload protection circuit according to claim 3, characterized in that, The first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter all include: a pull-down switch unit; One end of the pull-down switch unit of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter is grounded; the other end of the pull-down switch unit of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter is connected to the output terminal of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter respectively; the switching state of the pull-down switch unit of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter is controlled by the corresponding input terminal of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter. When the input terminals of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter are at a high level, the corresponding pull-down switch unit is turned on, so that the output terminals of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter are grounded through the pull-down switch unit, and are in a low impedance state; When the input terminals of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter are at a low level, the corresponding pull-down switch unit is turned off, so that the output terminals of the first inverter, the second inverter, the third inverter, the fourth inverter, and the fifth inverter are disconnected from the ground point and are in a high impedance state.

5. The overload protection circuit according to claim 1, characterized in that, The resistor-capacitor time constant of the first inverter input terminal of the motor power control circuit is determined based on the first resistor and the first capacitor. The resistor-capacitor time constant at the input of the second inverter in the motor power control circuit is determined based on the second resistor and the second capacitor. The time constant of the resistor-capacitor at the input of the first inverter is less than the time constant of the resistor-capacitor at the input of the second inverter.

6. The overload protection circuit according to claim 1, characterized in that, The overload signal sub-switch is also connected to the overload feedback point of the motor; The signal fed back by the overload feedback point is a motor overload signal, and the overload signal sub-switch is turned off. The signal fed back by the overload feedback point is a non-overload signal for the motor, and the overload signal sub-switch is turned on.

7. The overload protection circuit according to claim 1, characterized in that, When the input terminal of the first inverter is at a high level, the output terminal of the first inverter is in a low impedance state, and the relay switch of the relay switch sub-circuit is turned on so that the motor common power supply can supply power to the motor power supply normally. When the input terminal of the first inverter is at a low level, the output terminal of the first inverter is in a high impedance state, and the relay switch of the relay switch sub-circuit is turned off, so that the motor common power supply stops supplying power to the motor power supply. When the input of the second inverter is at a high level, the output of the second inverter is in a low impedance state. The output of the second inverter is connected to the output of the first inverter, which forces the input potential of the first inverter to be low so that the input potential of the first inverter remains unchanged. The relay switch control sub-circuit then enters a self-locking state.

8. The overload protection circuit according to claim 7, characterized in that, The overload protection circuit also includes: a fault reset switch; After the relay switch control subcircuit enters the self-locking state, if the fault reset switch is triggered, the input terminal of the second inverter is grounded through the third diode, and the input terminal of the first inverter is disconnected from the output terminal of the second inverter, so as to release the self-locking state of the relay switch control subcircuit.

9. The overload protection circuit according to claim 1, characterized in that, The motor power control circuit also includes: a fault indication circuit; The fault indication circuit includes a fifth resistor and an LED diode. One end of the fifth resistor is connected to the input terminal of the first inverter, and the other end of the fifth resistor is connected to the anode of the LED diode. The cathode of the LED diode is grounded. The LED diode is configured to indicate motor overload.

10. A motor system comprising multiple motor units, characterized in that, The common power supply for the motor units is connected to the power input terminal of each motor unit through the overload protection circuit described in any one of claims 1 to 9.

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