Motor control circuit and power supply system

Abstract

The utility model relates to a motor control circuit and a power supply system, the motor control circuit comprises a control circuit, a main circuit and a motor, the main circuit supplies power to the motor and comprises a first power supply branch and a second power supply branch, the first power supply branch and the second power supply branch are connected in parallel, one end of the main circuit is connected with a power supply connecting end, and the other end of the main circuit is connected with the motor; the control circuit is connected with the first power supply branch and the second power supply branch, controls the first power supply branch and the second power supply branch to be switched on under the condition that a motor starting signal is received, records the switching-on duration of the first power supply branch, controls the first power supply branch to be switched off under the condition that the switching-on duration is determined to be greater than or equal to a preset time threshold value, and controls the second power supply branch to be switched off under the condition that the switching-on duration is greater than or equal to the preset time threshold value; and the second power supply branch supplies power to the motor. Thus, the first power supply branch circuit and the second power supply branch circuit supply power to the motor within the preset time threshold value, the phenomenon of equipment shutdown caused by large starting current can be avoided, and therefore the experience feeling and the satisfaction degree of a user can be effectively improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of electrical equipment, and in particular, to a motor control circuit and a power supply system. Background Art

[0002] Electrical equipment refers to equipment used for generating, transmitting, distributing, converting, or using electrical energy. These devices are widely used in industrial, commercial, residential, and other fields, covering all aspects from power generation to final use, and are an indispensable part of modern society. Different types of electrical equipment play important roles in various industries, providing convenience and support for production and life.

[0003] When large on-site electrical equipment starts up instantaneously, motors or other large devices require a large starting current to overcome static inertia. The starting current is usually several times the full-load operating current. If not controlled, this instantaneous starting current may trigger the operation of electrical protection devices, resulting in equipment shutdown. In the prior art, the starting current can be reduced by means of a soft starter or a frequency converter to protect electrical equipment, but there is a problem of high cost due to the high product cost and maintenance cost of the soft starter and the frequency converter. Summary of the Utility Model

[0004] The purpose of the present disclosure is to provide a motor control circuit and a power supply system.

[0005] The first aspect of the present disclosure provides a motor control circuit. The motor control circuit includes a control circuit, a main circuit, and a motor. The main circuit is used to supply power to the motor. The main circuit includes a first power supply branch and a second power supply branch. The first power supply branch is connected in parallel with the second power supply branch. One end of the main circuit is used to connect to a power connection terminal, and the other end of the main circuit is used to connect to the motor;

[0006] The control circuit, which is connected to the first power supply branch and the second power supply branch, is configured to control the first power supply branch and the second power supply branch to conduct when receiving a motor start signal, and record the conduction duration of the first power supply branch. When it is determined that the conduction duration is greater than or equal to a preset time threshold, the control circuit controls the first power supply branch to disconnect, and the second power supply branch supplies power to the motor.

[0007] Through the above technical solution, the motor control circuit includes a control circuit, a main circuit, and a motor. The main circuit is used to supply power to the motor. The main circuit includes a first power supply branch and a second power supply branch. The first power supply branch is connected in parallel with the second power supply branch. One end of the main circuit is used to connect to the power connection terminal, and the other end of the main circuit is used to connect to the motor. The control circuit, connected to the first power supply branch and the second power supply branch, is configured to control the first power supply branch and the second power supply branch to conduct when receiving a motor start signal, and record the conduction duration of the first power supply branch. When it is determined that the conduction duration is greater than or equal to a preset time threshold, the control circuit controls the first power supply branch to disconnect, and the second power supply branch supplies power to the motor. In this way, by recording the conduction duration of the first power supply branch, the first power supply branch and the second power supply branch supply power to the motor within the preset time threshold. When it is determined that the conduction duration is greater than or equal to the preset time threshold, the control circuit controls the first power supply branch to disconnect, and the second power supply branch supplies power to the motor, which can enable the motor to avoid a large starting current through the first power supply branch and the second power supply branch during the starting process. Without using a soft starter or a frequency converter, it can avoid the equipment shutdown phenomenon caused by a large starting current, thereby effectively reducing costs and improving the user experience and satisfaction.

[0008] Optionally, the first power supply branch includes the main contact of a first contactor, and the second power supply branch includes the main contact of a second contactor. The control circuit includes a low-voltage power supply terminal, a normally open switch, the coil of the first contactor, the coil of the second contactor, and a time relay. The time relay includes a first normally closed contact and a relay coil.

[0009] One end of the main contact of the second contactor is used to connect to the power connection terminal, and the other end of the main contact of the second contactor is connected to the motor. The main contact of the first contactor is connected in parallel with the main contact of the second contactor.

[0010] The coil of the first contactor is connected in series with the first normally closed contact and then one end is connected to the low-voltage power supply terminal, and the other end is grounded. The first end of the normally open switch is connected in series with the coil of the second contactor and then grounded, the second end of the normally open switch is connected to the low-voltage power supply terminal, the first end of the relay coil is connected to the coil of the second contactor, and the second end of the relay coil is grounded.

[0011] The control circuit is configured to, when the normally open switch is closed, the coils of the first contactor and the second contactor are energized, and the time relay starts timing. When the timing duration is greater than the preset threshold, the first normally closed contact disconnects, so that the coil of the first contactor loses power.

[0012] The first power supply branch is configured to, when the coil of the first contactor is energized, close the main contacts of the first contactor to form a first path between the power connection terminal and the motor;

[0013] The second power supply branch is configured to, when the coil of the second contactor is energized, close the main contacts of the second contactor to form a second path between the power connection terminal and the motor.

[0014] Optionally, the normally open switch is a non-self-locking switch, and the control circuit further includes an auxiliary normally open contact of the second contactor;

[0015] The first end of the auxiliary normally open contact is connected to the low-voltage power supply terminal, and the second end of the auxiliary normally open contact is connected to the first end of the normally open switch;

[0016] The control circuit is configured to, when the non-self-locking switch is closed, energize the coil of the second contactor, and close the auxiliary normally open contact of the second contactor to form a self-locking path of the non-self-locking switch.

[0017] Optionally, the control circuit further includes a normally closed switch,

[0018] The first end of the normally closed switch is connected to the second end of the auxiliary normally open contact and the first end of the normally open switch, and the second end of the normally closed switch is connected to the first end of the relay coil;

[0019] The control circuit is configured to, when the normally closed switch is opened, de-energize the coils of the first contactor and the second contactor.

[0020] Optionally, the motor control circuit further includes a thermal protector, and the thermal protector includes a second normally closed contact and a thermosensitive element;

[0021] One end of the thermosensitive element is connected to the main contacts of the second contactor, and the other end of the thermosensitive element is connected to the motor;

[0022] The first end of the second normally closed contact is connected to the coil of the second contactor, and the second end of the second normally closed contact is grounded.

[0023] Optionally, the control circuit further includes a fuse,

[0024] One end of the fuse is connected to the low-voltage power supply terminal, and the other end of the fuse is connected to the second end of the normally open switch.

[0025] Optionally, the main circuit further includes a main circuit breaker,

[0026] One end of the main circuit breaker is used to connect to the power connection end, and the other end of the main circuit breaker is connected to the first power supply branch and the second power supply branch.

[0027] Optionally, the normally open switch is a normally open button, a sliding normally open switch, a rotary normally open switch, or a magnetic normally open switch.

[0028] Optionally, the normally closed switch is a normally closed button, a sliding normally closed switch, a rotary normally closed switch, or a magnetic normally closed switch.

[0029] A second aspect of the present disclosure provides a power supply system, and the power supply system includes the motor control circuit described in the first aspect above.

[0030] By the above technical solutions, the motor control circuit includes a control circuit, a main circuit, and a motor. The main circuit is used to supply power to the motor. The main circuit includes a first power supply branch and a second power supply branch. The first power supply branch and the second power supply branch are connected in parallel. One end of the main circuit is used to connect to a power connection end, and the other end of the main circuit is used to connect to the motor. The control circuit is connected to the first power supply branch and the second power supply branch, and is configured to control the first power supply branch and the second power supply branch to conduct when receiving a motor start signal, and record the conduction duration of the first power supply branch. When it is determined that the conduction duration is greater than or equal to a preset time threshold, control the first power supply branch to disconnect, and supply power to the motor by the second power supply branch. In this way, by recording the conduction duration of the first power supply branch, the motor is supplied power by the first power supply branch and the second power supply branch within the preset time threshold. When it is determined that the conduction duration is greater than or equal to the preset time threshold, control the first power supply branch to disconnect, and supply power to the motor by the second power supply branch, which can enable the motor to avoid a large starting current through the first power supply branch and the second power supply branch during the starting process, and avoid the equipment shutdown phenomenon caused by the large starting current without using a soft starter or a frequency converter, thereby effectively reducing costs and improving the user experience and satisfaction.

[0031] Other features and advantages of the present disclosure will be described in detail in the subsequent specific implementation part. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings are used to provide a further understanding of the present disclosure, and constitute a part of the specification. Together with the following specific implementation, they are used to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the drawings:

[0033] Figure 1 is a schematic diagram of a motor control circuit shown according to an exemplary embodiment of the present disclosure;

[0034] Figure 2 is a circuit diagram of a motor control circuit shown according to the Figure 1 illustrated embodiment;

[0035] Figure 3 is a circuit diagram of a motor control circuit shown according to the Figure 1 illustrated embodiment.

[0036] Description of Reference Numerals

[0037] 101 Main circuit 102 Control circuit

[0038] 103 Motor 104 Low-voltage power supply terminal

[0039] 1011 First power supply branch 1012 Second power supply branch

[0040] L1 L2 L3 Power connection terminals KM1 First contactor

[0041] KM2 Second contactor SB1 Normally open switch

[0042] KT Time relay SB2 Normally closed switch

[0043] KH Thermal protector FU Fuse

[0044] QF Main circuit breaker Detailed Embodiment

[0045] The following provides a detailed description of the specific embodiments of the present disclosure in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustration and explanation of the present disclosure, and are not intended to limit the present disclosure.

[0046] Before introducing the specific embodiments of the present disclosure in detail, the application scenarios of the present disclosure are first described as follows. The present disclosure can be applied to the startup process of electrical equipment. When a large electrical equipment on-site starts up instantaneously, a motor or other large equipment requires a large startup current to overcome the static inertia, and the startup current is usually several times the full-load running current. If not controlled, this instantaneous startup current may trigger the action of the electrical protection device and cause the equipment to shut down. In the prior art, the startup current can be reduced by means of a soft starter or a frequency converter to protect the electrical equipment, but there will be a problem of high cost due to the high product cost and maintenance cost of the soft starter and the frequency converter.

[0047] To solve the above technical problems, the present disclosure provides a motor control circuit and a power supply system. The motor control circuit includes a control circuit, a main circuit, and a motor. The main circuit is used to supply power to the motor. The main circuit includes a first power supply branch and a second power supply branch. The first power supply branch is connected in parallel with the second power supply branch. One end of the main circuit is used to connect to a power connection terminal, and the other end of the main circuit is used to connect to the motor. The control circuit is connected to the first power supply branch and the second power supply branch, and is configured to control the first power supply branch and the second power supply branch to conduct when receiving a motor start signal, and record the conduction duration of the first power supply branch. When it is determined that the conduction duration is greater than or equal to a preset time threshold, the control circuit controls the first power supply branch to disconnect, and the second power supply branch supplies power to the motor. In this way, by recording the conduction duration of the first power supply branch, the first power supply branch and the second power supply branch supply power to the motor within the preset time threshold. When it is determined that the conduction duration is greater than or equal to the preset time threshold, the first power supply branch is controlled to disconnect, and the second power supply branch supplies power to the motor. This can enable the motor to avoid a large starting current through the first power supply branch and the second power supply branch during the start-up process. Without using a soft starter or a frequency converter, it can avoid the equipment shutdown phenomenon caused by the large starting current, thereby effectively reducing costs and improving the user experience and satisfaction.

[0048] Figure 1 is a schematic diagram of a motor control circuit shown according to an exemplary embodiment of the present disclosure; as Figure 1 shown, the motor control circuit 100 includes a main circuit 101, a control circuit 102, and a motor 103. The main circuit 101 is used to supply power to the motor 103. The main circuit 101 includes a first power supply branch 1011 and a second power supply branch 1012. The first power supply branch 1011 is connected in parallel with the second power supply branch 1012. One end of the main circuit 101 is used to connect to a power connection terminal L1L2L3, and the other end of the main circuit 101 is used to connect to the motor 103. The control circuit 102 is connected to the first power supply branch 1011 and the second power supply branch 1012, and is configured to control the first power supply branch 1011 and the second power supply branch 1012 to conduct when receiving a start signal of the motor 103, and record the conduction duration of the first power supply branch 1011. When it is determined that the conduction duration is greater than or equal to a preset time threshold, the control circuit 102 controls the first power supply branch 1011 to disconnect, and the second power supply branch 1012 supplies power to the motor 103.

[0049] Among them, the preset time threshold is the time required for the motor 103 to start and reach a stable operating state. The start signal of the motor 103 can be a start operation instruction from an operator or a start signal issued by an automatic control system. The power supply is connected through the power connection terminals L1L2L3. The conduction time can be recorded by a timer inside the control circuit 102 or a dedicated timing circuit. The control circuit 102 can include components such as a microcontroller, a relay, and a transistor. Among them, the microcontroller is used to process the start signal of the motor 103 and control the conduction or cut-off of the first power supply branch 1011 and the second power supply branch 1012. The relay or transistor is used to actually conduct or disconnect the power supply branch. The control circuit 102 can be implemented through the level change of the input port of the control circuit 102 or a specific communication protocol. When the control circuit 102 receives the start signal of the motor 103, it controls the first power supply branch 1011 and the second power supply branch 1012 to conduct, and at the same time, the first power supply branch 1011 and the second power supply branch 1012 provide a start current for the motor 103. The motor 103 requires a large start current to overcome the static inertia at the start moment. The start current is usually several times the operating current. For example, the start current of a squirrel-cage motor is usually 4 to 7 times the full-load current. The operating current is the current flowing through the motor 103 in the normal operating state, which is close to the rated current of the motor 103. When it is determined that the conduction duration is greater than or equal to the start time of the motor 103, the first power supply branch 1011 is controlled to disconnect, and the second power supply branch 1012 provides the operating current for the motor 103.

[0050] In the above technical solution, by recording the conduction duration of the first power supply branch, when the conduction duration is less than the preset time threshold, the first power supply branch and the second power supply branch supply power to the motor. When it is determined that the conduction duration is greater than or equal to the preset time threshold, the first power supply branch is controlled to disconnect, and the second power supply branch supplies power to the motor. This can enable the motor to avoid a large start current through the first power supply branch and the second power supply branch during the start process. Without using a soft starter or a frequency converter, it can avoid the equipment shutdown phenomenon caused by a large start current, thereby effectively reducing costs and improving the user experience and satisfaction.

[0051] Figure 2 is according to Figure 1 shown in the circuit diagram of a motor control circuit according to the illustrated embodiment; as Figure 2 shown,

[0052] The first power supply branch 1011 includes the main contacts of a first contactor KM1, the second power supply branch 1012 includes the main contacts of a second contactor KM2, the control circuit 102 includes a low-voltage power supply terminal 104, a normally open switch SB1, the coil of the first contactor KM1, the coil of the second contactor KM2, and a time relay KT. The time relay KT includes a first normally closed contact and a relay coil;

[0053] One end of the main contacts of the second contactor KM2 is used to connect to the power supply connection terminals L1L2L3, the other end of the main contacts of the second contactor KM2 is connected to the motor 103, and the main contacts of the first contactor KM1 are connected in parallel with the main contacts of the second contactor KM2;

[0054] The coil of the first contactor KM1 is connected in series with the first normally closed contact KT and then one end is connected to the low-voltage power supply terminal 104, and the other end is grounded. The first end of the normally open switch SB1 is connected in series with the coil of the second contactor KM2 and then grounded, the second end of the normally open switch SB1 is connected to the low-voltage power supply terminal 104, the first end of the relay coil KT is connected to the coil of the second contactor KM2, and the second end of the relay coil KT is grounded;

[0055] The control circuit 102 is configured to, when the normally open switch SB1 is closed, the coils of the first contactor KM1 and the second contactor KM2 are energized, and the time relay KT starts timing. When the timing duration is greater than a preset time threshold, the first normally closed contact KT disconnects, so that the coil of the first contactor KM1 loses power;

[0056] The first power supply branch 1011 is configured to, when the coil of the first contactor KM1 is energized, the main contacts of the first contactor KM1 close, forming a first path between the power supply connection terminals L1L2L3 and the motor 103;

[0057] The second power supply branch 1012 is configured to, when the coil of the second contactor KM2 is energized, the main contacts of the second contactor KM2 close, forming a second path between the power supply connection terminals L1L2L3 and the motor 103.

[0058] Among them, the first contactor KM1 can be an AC contactor or other contactors used to control the on / off of an AC circuit. The second contactor KM2 can be an AC contactor or other contactors used to control the on / off of an AC circuit. The low-voltage power supply terminal 104 is used to receive a power supply connection terminal L1L2L3 with a relatively low voltage, such as DC voltages of 12V, 24V, 36V, etc., to provide a stable low-voltage power supply for the control circuit 102. The time relay KT has a delay start type. When the timing duration is greater than a preset threshold, the first normally closed contact KT disconnects. The preset time threshold is the time required for the motor 103 to start and reach a stable operating state. The first contactor KM1 includes the main contacts of the first contactor KM1 and the main coil of the first contactor KM1. The first contactor KM1 includes the main contacts of the second contactor KM2 and the coil of the second contactor KM2. The normally open switch SB1 is a switch that is in an open state in the unactivated state and only closes the circuit when activated. The normally open switch SB1 can have various types, including a normally open button, a sliding normally open switch SB1, a rotary normally open switch SB1, or a magnetic normally open switch SB1. When the timing duration is less than or equal to the preset time threshold, the motor 103 is powered through the first path and the second path. When the timing duration is greater than the preset time threshold, the motor 103 is powered through the second path.

[0059] In the above technical solution, by recording the conduction duration of the first power supply branch, when the conduction duration is less than the preset time threshold, the motor is powered through the first path and the second path. When it is determined that the conduction duration is greater than or equal to the preset time threshold, the motor is powered through the second path, which can enable the motor to avoid a large starting current through the first path and the second path during the starting process. Without using a soft starter or frequency converter, it can avoid the equipment shutdown phenomenon caused by a large starting current, thereby effectively reducing costs and improving the user experience and satisfaction.

[0060] Figure 3 is based on Figure 1 The circuit diagram of a motor control circuit shown in the illustrated embodiment; as Figure 3 shown,

[0061] The normally open switch SB1 is a non-self-locking switch, and the control circuit 102 further includes an auxiliary normally open contact of the second contactor KM2;

[0062] The first end of the auxiliary normally open contact is connected to the low-voltage power supply terminal 104, and the second end of the auxiliary normally open contact is connected to the first end of the normally open switch SB1;

[0063] The control circuit 102 is configured to, when the non-self-locking switch is closed, energize the coil of the second contactor KM2, and the auxiliary normally open contact of the second contactor KM2 is closed to form a self-locking path for the non-self-locking switch.

[0064] Among them, a normally open non-self-locking switch is a switch that is in an open state in the unactivated state and needs to continuously apply an external force to remain closed. Once the external force is removed, the switch will automatically return to the open state. The operation mode of the non-self-locking switch can be button type, sliding type, rotary type, etc. For example, the non-self-locking switch includes a normally open button that needs to be continuously pressed to remain closed and automatically disconnects when released.

[0065] Optionally, still taking Figure 3 as an example, the control circuit 102 further includes a normally closed switch SB2.

[0066] The first end of the normally closed switch SB2 is connected to the second end of the auxiliary normally open contact and the first end of the normally open switch SB1, and the second end of the normally closed switch SB2 is connected to the first end of the relay coil KT.

[0067] The control circuit 102 is configured to, when the normally closed switch SB2 is opened, de-energize the coils of the first contactor KM1 and the second contactor KM2.

[0068] Among them, the normally closed switch SB2 is a switch that is in a closed state in the unactivated state and only disconnects the circuit when activated. The normally closed switch SB2 can have various types, including a normally closed button, a sliding normally closed switch SB2, a rotary normally closed switch SB2, and a magnetic normally closed switch SB2. The normally closed switch SB2 can be a non-self-locking switch button. When the button is pressed, it temporarily closes the circuit, and once the button is released, the switch will automatically return to the open state.

[0069] Optionally, as Figure 3 shown, the motor 103 control circuit 102100 further includes a thermal protector KH, and the thermal protector KH includes a second normally closed contact and a thermosensitive element.

[0070] One end of the thermosensitive element is connected to the main contact of the second contactor KM2, and the other end of the thermosensitive element is connected to the motor 103.

[0071] The first end of the second normally closed contact is connected to the coil of the second contactor KM2, and the second end of the second normally closed contact is grounded.

[0072] Among them, the thermosensitive element is used to monitor the temperature of the motor 103. When the motor 103 is operating normally, that is, when the temperature of the motor 103 is less than or equal to the preset temperature threshold, the thermosensitive element remains closed, and the second normally closed contact also remains closed. The coil of the second contactor KM2 is energized, causing the main contacts of the second contactor KM2 to close, and the motor 103 operates normally. When the temperature of the motor 103 exceeds the preset temperature threshold, the thermosensitive element disconnects, causing the second normally closed contact to disconnect. The coil of the second contactor KM2 loses power, and the main contacts of the second contactor KM2 disconnect, causing the motor 103 to stop operating, achieving overheat protection.

[0073] In the above technical solution, the temperature of the motor 103 is monitored by the thermal protector KH in the main circuit 101 and the control circuit 102, and the circuit is disconnected when the temperature is too high, achieving overheat protection.

[0074] Optionally, still taking Figure 3 as an example, the control circuit 102 further includes a fuse FU,

[0075] One end of the fuse FU is connected to the low-voltage power supply terminal 104, and the other end of the fuse FU is connected to the second end of the normally open switch SB1.

[0076] Among them, the low-voltage power supply terminal 104 can be the positive pole of a +12V DC power supply or the positive pole of a +24V DC power supply. The fuse FU is an electrical device used to protect the circuit from overcurrent damage. When the current passing through the fuse FU exceeds its rated value, the fuse FU will blow, thereby cutting off the control circuit 102, playing a role in protecting the control circuit 102. One end of the fuse FU is connected to the low-voltage power supply terminal 104, and the other end of the fuse FU is connected to the second end of the normally open switch SB1. The fuse FU is connected in series in the path from the low-voltage power supply terminal 104 to the controller circuit, playing a role in overcurrent protection. When the current passing through the fuse FU exceeds its rated value, the fuse FU will blow, thereby cutting off the circuit and protecting the controller from overcurrent damage.

[0077] In the above technical solution, one end of the fuse is connected to the low-voltage power supply terminal, and the other end is connected to the controller circuit. In this way, the fuse is connected in series in the path from the low-voltage power supply terminal to the controller circuit, playing a role in overcurrent protection. When the current passing through the fuse exceeds its rated value, the fuse will blow, thereby cutting off the circuit and protecting the controller from overcurrent damage.

[0078] Optionally, still taking Figure 3 as an example, the main circuit 101 further includes a main circuit breaker QF,

[0079] One end of the main circuit breaker QF is used to connect to the power connection terminals L1L2L3, and the other end of the main circuit breaker QF is connected to the first power supply branch 1011 and the second power supply branch 1012.

[0080] Among them, the main circuit breaker QF is an electrical device used to protect the circuit from damage caused by faults such as overcurrent and short circuit. When the current in the main circuit 101 exceeds the rated current of the main circuit breaker QF, the main circuit breaker QF will automatically disconnect the circuit to protect the first power supply branch 1011 and the second power supply branch 1012 from damage caused by overcurrent.

[0081] The above technical solution can protect the main circuit 101 from damage caused by faults such as overcurrent and short circuit by setting the main circuit breaker QF in the main circuit 101.

[0082] Optionally, the normally open switch SB1 is a normally open button, a sliding normally open switch SB1, a rotary normally open switch SB1 or a magnetic normally open switch SB1.

[0083] Among them, the normally open button is a manually operated switch, usually used in occasions that need to be activated within a short time. When the normally open button is pressed, the circuit closes; when released, the circuit automatically disconnects. The sliding normally open switch SB1 is a switch that controls the on / off of the circuit 102 by sliding operation. When the sliding normally open switch SB1 is slid to the closed position, the circuit closes; when slid to the open position, the circuit disconnects. The rotary normally open switch SB1 is a switch that controls the on / off of the circuit 102 by rotary operation. When the rotary normally open switch SB1 is rotated to the closed position, the circuit closes; when rotated to the open position, the circuit disconnects.

[0084] Optionally, the normally closed switch SB2 is a normally closed button, a sliding normally closed switch SB2, a rotary normally closed switch SB2 or a magnetic normally closed switch SB2.

[0085] Among them, the normally closed button is a manually operated switch, usually used in occasions that need to disconnect the circuit within a short time. When the button is pressed, the circuit disconnects; when released, the circuit automatically closes. The sliding normally closed switch SB2 is a switch that controls the on / off of the circuit 102 by sliding operation. When the sliding normally closed switch SB2 is slid to the open position, the circuit disconnects; when slid to the closed position, the circuit closes. The rotary normally closed switch SB2 is a switch that controls the on / off of the circuit 102 by rotary operation. When the rotary normally closed switch SB2 is rotated to the open position, the circuit disconnects; when rotated to the closed position, the circuit closes. The magnetic normally closed switch SB2 is a switch that controls the on / off of the circuit 102 by magnetic force. When the magnet approaches the magnetic normally closed switch SB2, the circuit closes; when the magnet moves away, the circuit disconnects.

[0086] In another exemplary embodiment of the present disclosure, a power supply system is shown, which includes any one of the above Figures 1 - 3 motor control circuits.

[0087] The preferred embodiments of the present disclosure have been described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0088] In addition, it should be noted that, among the various specific technical features described in the above specific embodiments, without conflict, they can be combined in any suitable manner. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination manners.

[0089] Furthermore, any combination can be made among various different embodiments of the present disclosure, as long as it does not violate the idea of the present disclosure, and it should also be regarded as the content disclosed by the present disclosure.

Claims

1. A motor control circuit, characterized in that, The motor control circuit includes a control circuit, a main circuit, and a motor. The main circuit is used to supply power to the motor. The main circuit includes a first power supply branch and a second power supply branch. The first power supply branch is connected in parallel with the second power supply branch. One end of the main circuit is used to connect to a power connection terminal, and the other end of the main circuit is used to connect to the motor; The control circuit, connected to the first power supply branch and the second power supply branch, is used to control the first power supply branch and the second power supply branch to conduct when receiving a motor start signal, and record the conduction duration of the first power supply branch. When it is determined that the conduction duration is greater than or equal to a preset time threshold, control the first power supply branch to disconnect, and supply power to the motor by the second power supply branch.

2. The motor control circuit according to claim 1, characterized in that, The first power supply branch includes the main contacts of a first contactor. The second power supply branch includes the main contacts of a second contactor. The control circuit includes a low-voltage power supply terminal, a normally open switch, the coil of the first contactor, the coil of the second contactor, and a time relay. The time relay includes a first normally closed contact and a relay coil; One end of the main contacts of the second contactor is used to connect to the power connection terminal, and the other end of the main contacts of the second contactor is connected to the motor. The main contacts of the first contactor are connected in parallel with the main contacts of the second contactor; The coil of the first contactor is connected in series with the first normally closed contact and then one end is connected to the low-voltage power supply terminal and the other end is grounded. The first end of the normally open switch is connected in series with the coil of the second contactor and then grounded. The second end of the normally open switch is connected to the low-voltage power supply terminal. The first end of the relay coil is connected to the coil of the second contactor, and the second end of the relay coil is grounded; The control circuit is used to make the coils of the first contactor and the second contactor energized when the normally open switch is closed, and the time relay starts timing. When the timing duration is greater than the preset threshold, the first normally closed contact disconnects, so that the coil of the first contactor loses power; The first power supply branch is used to make the main contacts of the first contactor closed when the coil of the first contactor is energized, forming a first path between the power connection terminal and the motor; The second power supply branch is used to make the main contacts of the second contactor closed when the coil of the second contactor is energized, forming a second path between the power connection terminal and the motor.

3. The motor control circuit according to claim 2, wherein The normally open switch is a non-self-locking switch. The control circuit further includes an auxiliary normally open contact of the second contactor; The first end of the auxiliary normally open contact is connected to the low-voltage power supply terminal, and the second end of the auxiliary normally open contact is connected to the first end of the normally open switch; The control circuit is used to make the coil of the second contactor energized when the non-self-locking switch is closed, and the auxiliary normally open contact of the second contactor is closed, forming a self-locking path of the non-self-locking switch.

4. The motor control circuit according to claim 3, wherein, The control circuit further includes a normally closed switch, The first end of the normally closed switch is connected to the second end of the auxiliary normally open contact and the first end of the normally open switch, and the second end of the normally closed switch is connected to the first end of the relay coil; The control circuit is configured to de-energize the coils of the first contactor and the second contactor when the normally closed switch is opened.

5. The motor control circuit according to claim 2, characterized in that, The motor control circuit further includes a thermal protector, the thermal protector including a second normally closed contact and a thermal element; One end of the thermal element is connected to the main contact of the second contactor, and the other end of the thermal element is connected to the motor; The first end of the second normally closed contact is connected to the coil of the second contactor, and the second end of the second normally closed contact is grounded.

6. The motor control circuit according to claim 2, characterized in that The control circuit further includes a fuse, One end of the fuse is connected to the low-voltage power supply terminal, and the other end of the fuse is connected to the second end of the normally open switch.

7. The motor control circuit according to claim 2, wherein The main circuit further includes a main circuit breaker, One end of the main circuit breaker is configured to be connected to the power connection terminal, and the other end of the main circuit breaker is connected to the first power supply branch and the second power supply branch.

8. The motor control circuit according to claim 2, wherein The normally open switch is a normally open push button, a sliding normally open switch, a rotary normally open switch or a magnetic normally open switch.

9. The motor control circuit according to claim 4, wherein The normally closed switch is a normally closed push button, a sliding normally closed switch, a rotary normally closed switch or a magnetic normally closed switch.

10. A power supply system, characterized in that, Comprising the motor control circuit according to any one of claims 1-9.

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