Soft start control circuit and control system

Abstract

The invention provides a soft start control circuit and system, and relates to the technical field of circuit electronics, and the circuit comprises a fuse switch which is electrically connected with the positive electrode of a power supply, the first end of a first contactor switch, and the first end of a second contactor switch; a second end of the first contactor switch is electrically connected with a load anode; the second end of the second contactor switch is electrically connected with the first end of the current-limiting resistor; a second end of the current-limiting resistor is electrically connected with a load anode; the power supply cathode is electrically connected with the load cathode; the control circuit is electrically connected with the main circuit; the control circuit is used for controlling the second contactor switch to be switched on when a control instruction is received, and the power supply supplies power to the load in advance through the current-limiting resistor; and when the loop voltage of the main circuit is greater than the preset voltage threshold, the first contactor switch is controlled to be switched on, the second contactor switch is switched off, and the power supply supplies power to the load. According to the invention, soft start is realized, impact current is avoided, the service life of each component in the circuit is prolonged, and the use reliability is improved.

Description

Technical Field

[0001] This application relates to the field of circuit electronics technology, and more specifically, to a soft-start control circuit and control system. Background Technology

[0002] At the moment of startup of a high-power load, due to its extremely low equivalent impedance, an inrush current several times higher than the rated current is generated, which can damage the equipment. To solve this problem, existing technologies mainly use electronic soft starters to achieve soft starting of the load. By controlling the phase of power semiconductor devices, the output voltage is gradually increased, thereby achieving a smooth start-up of the load. However, in high-power applications, electronic soft starting has many shortcomings: the power semiconductor devices operate under high voltage and high current conditions for extended periods, significantly reducing their lifespan and reliability. Summary of the Invention

[0003] In view of this, the purpose of this application is to overcome the shortcomings of the prior art and provide a soft-start control circuit and control system. This application provides the following technical solution: In a first aspect, this application provides a soft-start control circuit, the circuit comprising: a main circuit and a control circuit, the main circuit comprising: a fuse switch, a first contactor switch, a second contactor switch and a current-limiting resistor; The first terminal of the fuse switch is electrically connected to the positive terminal of the power supply, and the second terminal of the fuse switch is electrically connected to the first terminal of the first contactor switch and the first terminal of the second contactor switch, respectively. The second terminal of the first contactor switch is electrically connected to the positive terminal of the load; The second terminal of the second contactor switch is electrically connected to the first terminal of the current-limiting resistor; The second end of the current-limiting resistor is electrically connected to the positive terminal of the load; The negative terminal of the power supply is electrically connected to the negative terminal of the load; The control circuit is electrically connected to the main circuit. The control circuit is used to control the second contactor switch to turn on when a control command is received, so that the positive terminal of the power supply is electrically connected to the first end of the current limiting resistor, and the power supply pre-supplyes the load through the current limiting resistor; When the loop voltage of the main circuit is detected to be greater than a preset voltage threshold, the first contactor switch is controlled to turn on and the second contactor switch is turned off, so that the positive terminal of the power supply is electrically connected to the positive terminal of the load, and the power supply supplies power to the load.

[0004] In one embodiment, the control circuit is further configured to, upon receiving a stop command, control the first contactor switch and the second contactor switch to disconnect, thereby disconnecting the positive terminal of the power supply from the positive terminal of the load and disconnecting the positive terminal of the power supply from the first end of the current-limiting resistor, thus stopping the power supply from supplying power to the load.

[0005] In one embodiment, the control circuit includes: a circuit breaker control sub-circuit and a contactor control sub-circuit, wherein the circuit breaker control sub-circuit includes: a programmable logic controller and a first relay coil; The first end of the first relay coil is electrically connected to the first output terminal of the programmable logic controller, and the second end of the first relay coil is grounded. The programmable logic controller is configured to supply power to the first relay coil when it receives the control command, so that the first relay coil is energized; The contactor control sub-circuit is used to enter a first conducting state when the first relay coil is energized, so as to control the second contactor switch to conduct.

[0006] In one embodiment, the circuit breaker control sub-circuit further includes: a sampling control board and a second relay coil; The input terminal of the sampling control board is electrically connected to the main circuit, and the output terminal of the sampling control board is electrically connected to the input terminal of the programmable logic controller. The first end of the second relay coil is electrically connected to the second output terminal of the programmable logic controller, and the second end of the second relay coil is grounded. The sampling control board is used to sample the loop voltage of the main circuit and send the loop voltage to the programmable logic controller; The programmable logic controller is further configured to supply power to the second relay coil when the circuit voltage is greater than the preset voltage threshold, so that the second relay coil is energized; The contactor control sub-circuit is also used to enter a second conduction state when the second relay coil is energized, so as to control the first contactor switch to conduct.

[0007] In one embodiment, the circuit breaker control sub-circuit further includes: a third relay coil; The first end of the third relay coil is electrically connected to the third output terminal of the programmable logic controller, and the second end of the third relay coil is grounded. The programmable logic controller is further configured to supply power to the third relay coil when the stop command is received, so that the third relay coil is energized; The contactor control sub-circuit is also used to enter a shutdown state when the third relay coil is energized, so as to control both the first contactor switch and the second contactor switch to be disconnected.

[0008] In one embodiment, the contactor control sub-circuit includes: a second contactor coil, a third contactor switch, a fourth contactor switch, a first relay switch, and a second relay switch; Both the first terminal of the first relay switch and the first terminal of the fourth contactor switch are electrically connected to the power supply. The second terminal of the first relay switch and the second terminal of the fourth contactor switch are both electrically connected to the first terminal of the second relay switch, and the second terminal of the second switch is electrically connected to the first terminal of the second contactor coil; The second end of the second contactor coil is electrically connected to the first end of the third contactor switch; The second terminal of the third contactor switch is grounded; The first relay switch is configured to conduct when the first relay coil is energized, so that the second contactor coil is energized and the second contactor switch is turned on.

[0009] In one embodiment, the contactor control sub-circuit further includes: a first contactor coil, a fifth contactor switch, a third relay switch, and a fourth relay switch; The first terminal of the third relay switch and the first terminal of the fifth contactor switch are both electrically connected to the power supply. The second terminal of the third relay switch and the second terminal of the fifth contactor switch are both electrically connected to the first terminal of the fourth relay switch, and the second terminal of the fourth switch is electrically connected to the first terminal of the first contactor coil. The second terminal of the first contactor coil is grounded; The third relay switch is used to conduct when the second relay coil is energized, so that the first contactor coil is energized and the first contactor switch is turned on.

[0010] In one embodiment, the second relay switch and the fourth relay switch are respectively used to disconnect when the third relay coil is energized, so that the second relay coil and the first relay coil are de-energized, and the first relay switch and the second relay switch are disconnected.

[0011] In one embodiment, the circuit breaker control sub-circuit further includes: a first rotary switch, a second rotary switch, and a third rotary switch; The first end of the first rotary switch, the first end of the second rotary switch, and the first end of the third rotary switch are respectively electrically connected to the power supply. The second end of the first rotary switch is electrically connected to the first end of the first relay coil, the second end of the second rotary switch is electrically connected to the first end of the second relay coil, and the second end of the third rotary switch is electrically connected to the first end of the third relay coil.

[0012] Secondly, this application also provides a soft-start control system, including: a host computer and the soft-start control circuit described in the first aspect.

[0013] This application achieves the switching between the pre-charging circuit and the normal charging circuit by controlling the on and off of the dual contactors, realizing the soft start of the circuit, avoiding inrush current, and extending the service life and reliability of the components in the circuit.

[0014] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A circuit diagram of a soft-start control circuit provided in an embodiment of this application is shown; Figure 2 A schematic diagram of the soft-start control system provided in an embodiment of this application is shown.

[0017] Explanation of key component symbols: 100 - Soft start control circuit; 110 - Main circuit; 121 - Opening and closing control sub-circuit; 122 - Contactor control sub-circuit; 200 - Soft start control system; 210 - Host computer. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0019] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the template description is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] Example 1 High-power loads, such as high-power motors and energy storage system charging / discharging modules, generate inrush currents several times higher than the rated current during startup. These inrush currents can easily cause momentary overload damage to power equipment and shorten the lifespan of components. To address this issue, soft-start solutions for drives primarily rely on electronic soft starters. Their core principle is to gradually increase the output voltage by controlling the conduction angle of power semiconductor devices, thereby achieving a smooth rise in load voltage and avoiding current surges. However, electronic soft-start methods suffer from insufficient reliability—power semiconductor devices operate under high voltage and high current conditions for extended periods, leading to a high risk of component aging and weak anti-interference capabilities, making them unsuitable for high-power applications. For further information, please refer to [link to relevant documentation / reference]. Figure 1 This application provides a soft-start control circuit 100, including a main circuit 110 and a control circuit. The main circuit 110 includes a fuse switch QF01, a first contactor switch KM01_1, a second contactor switch KM02_1, and a current-limiting resistor R. The first terminal of the fuse switch QF01 is electrically connected to the positive terminal of the power supply, and the second terminal of the fuse switch QF01 is electrically connected to the first terminal of the first contactor switch KM01_1 and the first terminal of the second contactor switch KM02_1, respectively; the second terminal of the first contactor switch KM01_1 is electrically connected to the positive terminal of the load. The second terminal of the second contactor switch KM02_1 is electrically connected to the first terminal of the current-limiting resistor R; The second terminal of the current-limiting resistor R is electrically connected to the positive terminal of the load; The negative terminal of the power supply is electrically connected to the negative terminal of the load; The control circuit is electrically connected to the main circuit 110; The control circuit is used to control the second contactor switch KM02_1 to be turned on when a control command is received, so that the positive terminal of the power supply is electrically connected to the first end of the current limiting resistor R, and the power supply pre-supplyes the load through the current limiting resistor R. When the loop voltage of the main circuit 110 is detected to be greater than a preset voltage threshold, the first contactor switch KM01_1 is turned on and the second contactor switch KM02_1 is turned off, so that the positive terminal of the power supply is electrically connected to the positive terminal of the load, and the power supply supplies power to the load.

[0022] In this embodiment, both the first contactor switch KM01_1 and the second contactor switch KM02_1 are normally open switches. When the second contactor switch KM02_1 is on, it forms a pre-charge circuit together with the power supply, the current-limiting resistor R, and the load. When the load needs to be started, the control circuit responds to the received control command and controls the second contactor switch KM02_1 to change from its initial normally open state to its on state. This causes the pre-charge circuit formed by the power supply, the second contactor switch KM02_1, the current-limiting resistor R, and the load to be turned on, and the power supply supplies power to the load through the pre-charge circuit.

[0023] During the pre-charging process, the control circuit detects the circuit voltage and, when the circuit voltage exceeds a preset voltage threshold, controls the first contactor switch KM01_1 to switch from its initial normally open state to its conducting state. At this time, the power supply is directly connected to the load, supplying power to the load. It can be understood that in the initial startup phase, the power supply supplies power to the load through the pre-charging circuit. Due to the presence of the current-limiting resistor R, the charging current of the pre-charging circuit is limited, avoiding the inrush current caused by the low equivalent impedance of the load at startup.

[0024] During the pre-charging phase, the loop voltage gradually increases as the load charges. The preset voltage threshold is typically set to 90%-95% of the load's rated voltage, and can be flexibly adjusted by the programmable logic controller UP02 in the control circuit to adapt to the load requirements of different power levels. When the loop voltage reaches the preset voltage threshold, it indicates that the load capacitor has been fully charged, and the voltage difference between the load end and the power supply end has significantly decreased. At this point, switching to direct power supply will not cause a significant current surge.

[0025] When the control circuit detects that the circuit voltage is greater than the preset voltage threshold, it controls the first contactor switch KM01_1 to switch from the normally open state to the conducting state, and controls the second contactor switch KM02_1 to return to the normally open state. This cuts off the pre-charge circuit and completes a smooth transition from pre-charge to normal charge, avoiding problems such as increased energy consumption and overheating caused by the long-term operation of the current limiting resistor R. This ensures that the main circuit 110 can stably and reliably provide rated power to the load.

[0026] In one embodiment, the control circuit is further configured to, upon receiving a stop command, control the first contactor switch KM01_1 and the second contactor switch KM02_1 to disconnect, thereby disconnecting the positive terminal of the power supply from the positive terminal of the load and disconnecting the positive terminal of the power supply from the first end of the current-limiting resistor R, thus stopping the power supply from supplying power to the load.

[0027] In this embodiment, in response to the received stop command, the control circuit is also used to control the first contactor switch KM01_1 and the second contactor switch KM02_1 to enter the open state, so that the power supply is completely disconnected from the load, preventing accidental power supply before restart, avoiding damage to the components in the circuit caused by residual current during shutdown, and significantly improving the power supply safety and reliability of the circuit.

[0028] In one embodiment, the control circuit includes: a circuit breaker control sub-circuit 121 and a contactor control sub-circuit 122. The circuit breaker control sub-circuit 121 includes: a programmable logic controller UP02 (PLC) and a first relay coil KA01. The first terminal of the first relay coil KA01 is electrically connected to the first output terminal of the programmable logic controller UP02, and the second terminal of the first relay coil KA01 is grounded. The programmable logic controller UP02 is used to supply power to the first relay coil KA01 when the control command is received, so that the first relay coil KA01 is energized; the contactor control sub-circuit 122 is used to enter a first conduction state when the first relay coil KA01 is energized, so as to control the second contactor switch KM02_1 to conduct.

[0029] In this embodiment, please refer to Figure 1 The programmable logic controller UP02 is configured such that, upon receiving a control command, in response to the control command, the first output terminal of the programmable logic controller UP02 outputs a high level, thereby energizing the first relay coil KA01.

[0030] When the first relay coil KA01 is energized, its corresponding normally open contact will conduct, meaning the first relay switch KA01_1 in the contactor control sub-circuit 122 will conduct, and the contactor control sub-circuit 122 will enter the first conducting state. In the first conducting state, the second contactor coil KM02 is energized. When the second contactor coil KM02 is energized, its corresponding normally open contact will conduct, meaning the second contactor switch KM02_1 in the main circuit 110 will conduct, and the fourth contactor switch KM02_2 in the contactor control sub-circuit 122 will also conduct.

[0031] It is understandable that when the second contactor switch KM02_1 is turned on, the positive terminal of the power supply, the current-limiting resistor R, and the positive terminal of the load form a pre-charge circuit. The power supply slowly charges the load through the current-limiting resistor, achieving a smooth soft start and avoiding inrush current. When the fourth contactor switch KM02_2 is turned on, the second contactor coil KM02 is self-locked. Thereafter, even if the first relay switch KA01_1 is disconnected due to command changes or momentary interference, the second contactor coil KM02 can still be continuously energized, ensuring the stable operation of the pre-charge circuit and improving the reliability and stability of the circuit.

[0032] In one embodiment, the circuit breaker control sub-circuit 121 further includes: a sampling control board UP01 and a second relay coil KA02; the input terminal of the sampling control board UP01 is electrically connected to the main circuit 110, and the output terminal of the sampling control board UP01 is electrically connected to the input terminal of the programmable logic controller UP02; the first terminal of the second relay coil KA02 is electrically connected to the second output terminal of the programmable logic controller UP02, and the second terminal of the second relay coil KA02 is grounded; The sampling control board UP01 is electrically connected to the main circuit 110, the programmable logic controller UP02, and the power supply. A fuse FU is connected in series between the power supply and the sampling control board UP01. The sampling control board UP01 is used to sample the loop voltage of the main circuit 110 and send the loop voltage to the programmable logic controller UP02. The programmable logic controller UP02 is also used to supply power to the second relay coil KA02 when the loop voltage is greater than the preset voltage threshold, so that the second relay coil KA02 is energized. The contactor control sub-circuit 122 is also used to enter a second conduction state when the second relay coil KA02 is energized, so as to control the first contactor switch KM01_1 to conduct.

[0033] In this embodiment, please continue to refer to Figure 1 The sampling control board UP01 is used to acquire the loop voltage of the main circuit 110 and send it to the programmable logic controller UP02. The programmable logic controller UP02 performs logical judgment based on the acquired loop voltage. When the loop voltage is greater than the preset voltage threshold, it outputs a high level to the second relay coil KA02 so that the second relay coil KA02 is energized.

[0034] When the second relay coil KA02 is energized, its corresponding normally open contact will be closed, meaning the third relay switch KA02_1 in the contactor control sub-circuit 122 will be closed, and the contactor control sub-circuit 122 will enter the second conducting state. In the second conducting state, the first contactor coil KM01 is energized. When the first contactor coil KM01 is energized, its corresponding normally open contact will be closed, meaning the first contactor switch KM01_1 in the main circuit 110 will be closed, and the fifth contactor switch KM01_3 in the contactor control sub-circuit 122 will be closed; its corresponding normally closed contact will be open, meaning the third contactor switch KM01_2 in the contactor control sub-circuit 122 will be open.

[0035] When the first contactor switch KM01_1 is turned on, the power supply is directly connected to the load, providing normal power and achieving a smooth transition from soft start to normal charging. When the fifth contactor switch KM01_3 is turned on, the first contactor coil KM01 is self-locked. When the third contactor switch KM01_2 is turned off, the second contactor coil KM02 is de-energized, and the second contactor switch KM02_1 corresponding to the second contactor coil KM02 is turned off. The fourth contactor switch KM02_2 is also turned off, ensuring that the pre-charge circuit is disconnected and avoiding component aging problems caused by prolonged energization of the pre-charge circuit.

[0036] In one embodiment, the circuit breaker control sub-circuit 121 further includes: a third relay coil KA03; the first end of the third relay coil KA03 is electrically connected to the third output terminal of the programmable logic controller UP02, and the second end of the third relay coil KA03 is grounded; The programmable logic controller UP02 is further configured to supply power to the third relay coil KA03 when the stop command is received, so that the third relay coil KA03 is energized; the contactor control sub-circuit 122 is further configured to enter the off state when the third relay coil KA03 is energized, so as to control both the first contactor switch KM01_1 and the second contactor switch KM02_1 to be disconnected.

[0037] In this embodiment, in response to the received stop command, the third terminal of the programmable logic controller UP03 outputs a high level, thereby energizing the third relay coil KA03.

[0038] When the third relay coil KA03 is energized, its corresponding normally closed contact opens, meaning the second relay switch KA03_1 and the fourth relay switch KA03_2 in the contactor control sub-circuit 122 are open, and the contactor control sub-circuit 122 enters the off state. When the second relay switch KA03_1 is open, the second contactor coil KM02 is de-energized, and the second contactor switch KM02_1 is open; when the fourth relay switch KA03_2 is open, the first contactor coil KM01 is de-energized, and the first contactor switch KM01_1 is open.

[0039] It is understandable that by controlling both the first contactor switch KM01_1 and the second contactor switch KM02_1 to be disconnected, it is ensured that the power supply is completely disconnected from the load when the machine is stopped, thus avoiding power loss caused by a single circuit not being disconnected.

[0040] In one embodiment, the contactor control sub-circuit 122 includes: a second contactor coil KM02, a third contactor switch KM01_2, a fourth contactor switch KM02_2, a first relay switch KA01_1, and a second relay switch KA03_1; The first terminal of the first relay switch KA01_1 and the first terminal of the fourth contactor switch KM02_2 are both electrically connected to the power supply. The second terminal of the first relay switch KA01_1 and the second terminal of the fourth contactor switch KM02_2 are both electrically connected to the first terminal of the second relay switch KA03_1, and the second terminal of the second relay switch KA03_1 is electrically connected to the first terminal of the second contactor coil KM02; The second terminal of the second contactor coil KM02 is electrically connected to the first terminal of the third contactor switch KM01_2; The second terminal of the third contactor switch KM01_2 is grounded; The first relay switch KA01_1 is used to conduct when the first relay coil KA01 is energized, so that the second contactor coil KM02 is energized and the second contactor switch KM02_1 is turned on.

[0041] In this embodiment, the programmable logic controller UP02 controls the first relay coil KA01 to be energized, thereby turning on the first relay switch KA01_1 corresponding to the first relay coil KA01, and then controls the second contactor coil KM02 to be energized, turning on the second contactor switch KM02_1 corresponding to the second contactor coil KM02.

[0042] In one embodiment, the contactor control sub-circuit 122 further includes: a first contactor coil KM01, a fifth contactor switch KM01_3, a third relay switch KA02_1, and a fourth relay switch KA03_2; The first terminal of the third relay switch KA02_1 and the first terminal of the fifth contactor switch KM01_3 are both electrically connected to the power supply. The second terminal of the third relay switch KA02_1 and the second terminal of the fifth contactor switch KM01_3 are both electrically connected to the first terminal of the fourth relay switch KA03_2, and the second terminal of the fourth relay switch KA03_2 is electrically connected to the first terminal of the first contactor coil KM01. The second terminal of the first contactor coil KM01 is grounded; The third relay switch KA02_1 is used to conduct when the second relay coil KA02 is energized, so that the first contactor coil KM01 is energized and the first contactor switch KM01_1 is turned on.

[0043] In this embodiment, the programmable logic controller UP02 controls the second relay coil KA02 to be energized, thereby turning on the third relay switch KA02_1 corresponding to the second relay coil KA02, and in turn controlling the first contactor coil KM01 to be energized, and turning on the first contactor switch KM01_1 corresponding to the first contactor coil KM01.

[0044] In one embodiment, the second relay switch KA03_1 and the fourth relay switch KA03_2 are respectively used to disconnect when the third relay coil KA03 is energized, so that the second relay coil KM02 and the first relay coil KM01 are de-energized, and the first relay switch KM01_1 and the second relay switch KM02_1 are disconnected.

[0045] In this embodiment, the programmable logic controller UP02 controls the third relay coil KA03 to be energized, causing the second relay switch KA03_1 corresponding to the third relay coil KA03 to be disconnected and the fourth relay switch KA03_2 to be disconnected. This, in turn, controls the first contactor coil KM01 to be de-energized and the second contactor coil KM02 to be de-energized. Consequently, the first contactor switch KM01_1 corresponding to the first contactor coil KM01 is disconnected, and the second contactor switch KM02_1 corresponding to the second contactor coil KM02 is disconnected.

[0046] In one embodiment, the circuit breaker control sub-circuit 121 further includes: a first rotary switch SA01, a second rotary switch SA02, and a third rotary switch SA03; the first end of the first rotary switch SA01, the first end of the second rotary switch SA02, and the first end of the third rotary switch SA03 are respectively electrically connected to the power supply. The second end of the first rotary switch SA01 is electrically connected to the first end of the first relay coil KA01, the second end of the second rotary switch SA01 is electrically connected to the first end of the second relay coil KA02, and the second end of the third rotary switch SA03 is electrically connected to the first end of the third relay coil KA03.

[0047] In this embodiment, to control the energization of each relay coil, the programmable logic controller UP02 can automatically send control signals to each relay coil. Alternatively, it can respond to the operator's rotation operation by turning on the first rotary switch SA01, the second rotary switch SA02, or the third rotary switch SA03 to achieve manual opening and closing operations, ensuring that the circuit can still start and stop normally in emergency situations.

[0048] The soft-start control circuit provided in this application embodiment includes: a main circuit and a control circuit. The main circuit includes: a fuse switch, a first contactor switch, a second contactor switch, and a current-limiting resistor. The first terminal of the fuse switch is electrically connected to the positive terminal of the power supply; the second terminal of the fuse switch is electrically connected to the first terminals of both the first and second contactor switches; the second terminal of the first contactor switch is electrically connected to the positive terminal of the load; the second terminal of the second contactor switch is electrically connected to the first terminal of the current-limiting resistor; and the second terminal of the current-limiting resistor is electrically connected to the positive terminal of the load. The negative terminal of the power supply is electrically connected to the negative terminal of the load; the control circuit is electrically connected to the main circuit; the control circuit, upon receiving a control command, controls the second contactor switch to conduct, so that the positive terminal of the power supply is electrically connected to the first end of the current-limiting resistor, and the power supply pre-supplyes the load through the current-limiting resistor; when the loop voltage of the main circuit is detected to be greater than a preset voltage threshold, the first contactor switch is controlled to conduct, and the second contactor switch is controlled to open, so that the positive terminal of the power supply is electrically connected to the positive terminal of the load, and the power supply supplies power to the load. This application achieves the switching between the pre-charging circuit and the normal charging circuit by controlling the conduction and cutoff of the dual contactors, realizing the soft start of the circuit, avoiding inrush current, and extending the service life and reliability of the components in the circuit.

[0049] Example 2 In addition, please see Figure 2 , Figure 2A schematic diagram of a soft-start control system 200 provided in an embodiment of this application is shown. The soft-start control system 200 includes a host computer 210 and a soft-start control circuit 100 as described in Embodiment 1. The host computer 210 is electrically connected to the soft-start control circuit 100.

[0050] The soft-start control system 200 provided in this application embodiment can perform the functions of the soft-start control circuit 100 provided in the above embodiment 1. To avoid repetition, it will not be described again here.

[0051] In all examples shown and described herein, any specific values ​​should be interpreted as merely exemplary and not as limitations; therefore, other examples of exemplary embodiments may have different values.

[0052] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0053] The above-described embodiments are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A soft-start control circuit, characterized in that, The circuit includes a main circuit and a control circuit. The main circuit includes a fuse switch, a first contactor switch, a second contactor switch, and a current-limiting resistor. The first terminal of the fuse switch is electrically connected to the positive terminal of the power supply, and the second terminal of the fuse switch is electrically connected to the first terminal of the first contactor switch and the first terminal of the second contactor switch, respectively. The second terminal of the first contactor switch is electrically connected to the positive terminal of the load; The second terminal of the second contactor switch is electrically connected to the first terminal of the current-limiting resistor; The second end of the current-limiting resistor is electrically connected to the positive terminal of the load; The negative terminal of the power supply is electrically connected to the negative terminal of the load; The control circuit is electrically connected to the main circuit. The control circuit is used to control the second contactor switch to turn on when a control command is received, so that the positive terminal of the power supply is electrically connected to the first end of the current limiting resistor, and the power supply pre-supplyes the load through the current limiting resistor; When the loop voltage of the main circuit is detected to be greater than a preset voltage threshold, the first contactor switch is controlled to turn on and the second contactor switch is turned off, so that the positive terminal of the power supply is electrically connected to the positive terminal of the load, and the power supply supplies power to the load.

2. The soft-start control circuit according to claim 1, characterized in that, The control circuit is also used to control the first contactor switch and the second contactor switch to open respectively when a stop command is received, so that the positive terminal of the power supply is disconnected from the positive terminal of the load, and the positive terminal of the power supply is disconnected from the first end of the current limiting resistor, so that the power supply stops supplying power to the load.

3. The soft-start control circuit according to claim 2, characterized in that, The control circuit includes: a circuit breaker control sub-circuit and a contactor control sub-circuit, wherein the circuit breaker control sub-circuit includes: a programmable logic controller and a first relay coil; The first end of the first relay coil is electrically connected to the first output terminal of the programmable logic controller, and the second end of the first relay coil is grounded. The programmable logic controller is configured to supply power to the first relay coil when it receives the control command, so that the first relay coil is energized; The contactor control sub-circuit is used to enter a first conducting state when the first relay coil is energized, so as to control the second contactor switch to conduct.

4. The soft-start control circuit according to claim 3, characterized in that, The circuit breaker control sub-circuit also includes: a sampling control board and a second relay coil; The input terminal of the sampling control board is electrically connected to the main circuit, and the output terminal of the sampling control board is electrically connected to the input terminal of the programmable logic controller. The first end of the second relay coil is electrically connected to the second output terminal of the programmable logic controller, and the second end of the second relay coil is grounded. The sampling control board is used to sample the loop voltage of the main circuit and send the loop voltage to the programmable logic controller; The programmable logic controller is further configured to supply power to the second relay coil when the circuit voltage is greater than the preset voltage threshold, so that the second relay coil is energized; The contactor control sub-circuit is also used to enter a second conduction state when the second relay coil is energized, so as to control the first contactor switch to conduct.

5. The soft-start control circuit according to claim 4, characterized in that, The circuit breaker control sub-circuit also includes: a third relay coil; The first end of the third relay coil is electrically connected to the third output terminal of the programmable logic controller, and the second end of the third relay coil is grounded. The programmable logic controller is further configured to supply power to the third relay coil when the stop command is received, so that the third relay coil is energized; The contactor control sub-circuit is also used to enter a shutdown state when the third relay coil is energized, so as to control both the first contactor switch and the second contactor switch to be disconnected.

6. The soft-start control circuit according to claim 5, characterized in that, The contactor control sub-circuit includes: a second contactor coil, a third contactor switch, a fourth contactor switch, a first relay switch, and a second relay switch; Both the first terminal of the first relay switch and the first terminal of the fourth contactor switch are electrically connected to the power supply. The second terminal of the first relay switch and the second terminal of the fourth contactor switch are both electrically connected to the first terminal of the second relay switch, and the second terminal of the second switch is electrically connected to the first terminal of the second contactor coil; The second end of the second contactor coil is electrically connected to the first end of the third contactor switch; The second terminal of the third contactor switch is grounded; The first relay switch is configured to conduct when the first relay coil is energized, so that the second contactor coil is energized and the second contactor switch is turned on.

7. The soft-start control circuit according to claim 6, characterized in that, The contactor control sub-circuit further includes: a first contactor coil, a fifth contactor switch, a third relay switch, and a fourth relay switch; The first terminal of the third relay switch and the first terminal of the fifth contactor switch are both electrically connected to the power supply. The second terminal of the third relay switch and the second terminal of the fifth contactor switch are both electrically connected to the first terminal of the fourth relay switch, and the second terminal of the fourth switch is electrically connected to the first terminal of the first contactor coil. The second terminal of the first contactor coil is grounded; The third relay switch is used to conduct when the second relay coil is energized, so that the first contactor coil is energized and the first contactor switch is turned on.

8. The soft-start control circuit according to claim 7, characterized in that, The second relay switch and the fourth relay switch are respectively used to disconnect when the third relay coil is energized, so that the second relay coil and the first relay coil are de-energized, and the first relay switch and the second relay switch are disconnected.

9. The soft-start control circuit according to claim 8, characterized in that, The circuit breaker control sub-circuit further includes: a first rotary switch, a second rotary switch, and a third rotary switch; The first end of the first rotary switch, the first end of the second rotary switch, and the first end of the third rotary switch are respectively electrically connected to the power supply. The second end of the first rotary switch is electrically connected to the first end of the first relay coil, the second end of the second rotary switch is electrically connected to the first end of the second relay coil, and the second end of the third rotary switch is electrically connected to the first end of the third relay coil.

10. A soft-start control system, characterized in that, include: The host computer and the soft-start control circuit according to any one of claims 1-9.

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