Silicon controlled rectifier protection circuit of soft starter

Abstract

The utility model provides a silicon controlled rectifier protection circuit of a soft starter. The silicon controlled rectifier protection circuit comprises a silicon controlled rectifier SCR1, a silicon controlled rectifier SCR2, a resistor R1, a capacitor C1, a capacitor C2 and a switch K, one end of the resistor R1 is connected with the anode of the silicon controlled rectifier SCR1 and the cathode of the silicon controlled rectifier SCR2 and then is externally connected with a power supply, the cathode of the silicon controlled rectifier SCR1 is connected with one end of the capacitor C1, one end of the capacitor C2 and the anode of the silicon controlled rectifier SCR2 and then is externally connected with a controlled motor, and the other end of the resistor R1 is connected with the other end of the capacitor C1 and one end of the switch K; the other end of the switch K is connected with the other end of the capacitor C2, and the control electrode of the silicon controlled rectifier SCR1 and the control electrode of the silicon controlled rectifier SCR2 are respectively and externally connected with a processor circuit. According to the utility model, the loss of hot standby can be effectively reduced, the resistance value power is reduced, the heat productivity is reduced, and the product volume is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of thyristor protection for soft starters, in particular to a thyristor protection circuit for soft starters. Background Art

[0002] A soft starter is a motor monitoring device that integrates motor soft start, soft stop and multiple protection functions. Its main circuit consists of a three-phase reverse parallel gate connected in series between the power supply and the controlled motor, a protection circuit connected in parallel at both ends of the thyristor (silicon controlled rectifier), and an associated control circuit. The general thyristor protection circuit uses an RC absorption circuit, which has two major functions: 1. Suppress the peak of harmonics in the power grid to prevent the thyristor from being broken down by excessive voltage; 2. Reduce the critical rise rate of the off-state voltage to prevent the thyristor from being mis-conducted. Therefore, the value of RC becomes particularly important. In some sites, in order to avoid problems with a certain soft starter affecting the progress of other work in the company, a solution of using several for one is used for design, and a certain soft starter is regularly switched as a backup device to ensure the reliability of the system. The backup soft starter is in hot standby state. Once a soft starter in the system has a problem and stops, the backup soft starter will immediately enter the working state. During soft start hot standby, the RC equivalent circuit connected in parallel at both ends of the three-phase thyristor is equivalent to a group of star-connected RC connected to the three-phase power grid. In order to suppress the amount of harmonics generated to the power grid during the soft start process, the capacitance value is generally greater than the value that only satisfies the reduction of the critical voltage rise rate. Therefore, the capacitance reactance of the capacitor is small. In addition, the hot standby state makes the soft start connected to the power grid for a long time, and the power consumed by the resistor R will increase (the cold standby state soft start is disconnected from the power grid, and RC will not consume power. It only works during the start and stop process, which lasts for tens of seconds to several minutes. The temperature of the resistor has not yet completely risen, and the relevant process has been completed), causing serious heating of the resistor. In order to ensure that the heat of the resistor will not affect the life of the capacitor (in order to achieve a better absorption effect, the RC will be closer, and the connection with the heat sink will be as short as possible, and the heat of R will be easily transferred to C), the selected resistor power will be several times the actual power, so as to reduce the temperature rise of the resistor. The volume of the resistor will increase a lot, resulting in an increase in the volume of the equipment and an increase in cost.

[0003] The current soft start hot standby solution will cause the RC to absorb a large amount of power in the hot standby state, thereby increasing unnecessary losses in the power grid, and the product cost and volume will increase. Utility Model Content

[0004] The utility model provides a thyristor protection circuit for a soft starter, which can effectively reduce the loss of hot standby, reduce the power of the resistance value, reduce the heat generation, and reduce the product volume.

[0005] The embodiment of this specification discloses a thyristor protection circuit of a soft starter, including thyristor SCR1, thyristor SCR2, resistor R1, capacitor C1, capacitor C2 and switch K;

[0006] One end of the resistor R1 is connected to the anode of the thyristor SCR1 and the cathode of the thyristor SCR2 and then connected to an external power supply. The cathode of the thyristor SCR1 is connected to one end of the capacitor C1, one end of the capacitor C2 and the anode of the thyristor SCR2 and then connected to an external controlled motor. The other end of the resistor R1 is connected to the other end of the capacitor C1 and one end of the switch K, and the other end of the switch K is connected to the other end of the capacitor C2. The control electrode of the thyristor SCR1 and the control electrode of the thyristor SCR2 are respectively connected to an external processor circuit.

[0007] The embodiment of this specification also discloses a thyristor protection circuit of a soft starter, including thyristor SCR3, thyristor SCR4, resistor R6, resistor R7, capacitor C6, capacitor C7 and switch S;

[0008] One end of the resistor R6 is connected to the anode of the thyristor SCR3, one end of the switch S and the cathode of the thyristor SCR4 and then connected to an external power supply. The cathode of the thyristor SCR3 is connected to one end of the capacitor C6, one end of the capacitor C7 and the anode of the thyristor SCR4 and then connected to an external controlled motor. The other end of the resistor R6 is connected to the other end of the capacitor C6, the other end of the capacitor C7 is connected to one end of the resistor R7, the other end of the switch K is connected to the other end of the resistor R7, and the control electrode of the thyristor SCR3 and the control electrode of the thyristor SCR4 are respectively connected to external processor circuits.

[0009] In some embodiments of this specification, the processor circuit includes a processor, an input terminal P1, an output terminal P2, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a capacitor C3, a capacitor C4, a capacitor C5, and an operational amplifier U1;

[0010] The processor is connected to the input terminal P1, the input terminal P1 is connected to one end of the resistor R2, the other end of the resistor R2 is connected to one end of the resistor R3, one end of the resistor R4 and a grounded capacitor C3, the other end of the resistor R3 is connected to one end of the capacitor C4 and an inverting end of the operational amplifier U1, the non-inverting end of the operational amplifier U1 is grounded, the other end of the resistor R4 is connected to the other end of the capacitor C4, one end of the resistor R5 and an output end of the operational amplifier U1, and the other end of the resistor R5 is connected to the output terminal P2 and the grounded capacitor C5.

[0011] In some embodiments of the present specification, the processor is a MUC, DSP, PLC, ASIC or FPGA chip.

[0012] In some embodiments of this specification, the model of the operational amplifier U1 is LM358.

[0013] The embodiments of this specification can at least achieve the following beneficial effects:

[0014] The reliability of the soft start in the hot standby state is ensured by a set of RC with static parameters. When the soft start is working, another C or RC is incorporated to ensure the product reliability in the soft start start-stop state. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 The figure is a schematic diagram of a thyristor protection circuit of a soft starter involved in some embodiments of the present invention.

[0017] Figure 2 It is a schematic diagram of a processor circuit involved in some embodiments of the present invention.

[0018] Figure 3 The figure is a schematic diagram of a thyristor protection circuit of a soft starter involved in other embodiments of the utility model. DETAILED DESCRIPTION

[0019] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the embodiments of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0020] In the description of the embodiments of the present invention, it should be understood that the terms "length", "vertical", "horizontal", "top", "bottom", etc. indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present invention.

[0021] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of the present utility model, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0022] In the embodiments of the present utility model, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present utility model can be understood according to specific circumstances.

[0023] In the embodiments of the present utility model, unless otherwise clearly specified and limited, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through another feature between them. Moreover, the first feature being "above", "above" and "above" the second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature includes the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0024] The disclosure below provides many different embodiments or examples for realizing different structures of the embodiments of the present utility model. In order to simplify the disclosure of the embodiments of the present utility model, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the embodiments of the present utility model. In addition, the embodiments of the present utility model can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0025] The embodiments of the present utility model are described in detail below with reference to the accompanying drawings.

[0026] like Figure 1 As shown, the embodiment of this specification discloses a thyristor protection circuit of a soft starter, including thyristor SCR1, thyristor SCR2, resistor R1, capacitor C1, capacitor C2 and switch K;

[0027] One end of the resistor R1 is connected to the anode of the thyristor SCR1 and the cathode of the thyristor SCR2 and then connected to an external power supply. The cathode of the thyristor SCR1 is connected to one end of the capacitor C1, one end of the capacitor C2 and the anode of the thyristor SCR2 and then connected to an external controlled motor. The other end of the resistor R1 is connected to the other end of the capacitor C1 and one end of the switch K, and the other end of the switch K is connected to the other end of the capacitor C2. The control electrode of the thyristor SCR1 and the control electrode of the thyristor SCR2 are respectively connected to an external processor circuit.

[0028] In this embodiment, thyristor SCR1 and thyristor SCR2 correspond to a processor circuit respectively, and each is controlled to be turned on or off by the processor circuit; when soft starting is working, closing switch K and connecting capacitor C2 in parallel with capacitor C1 can effectively reduce the loss of hot standby, reduce the power of the resistance value, and reduce the heat generation.

[0029] like Figure 3 As shown, the embodiment of this specification also discloses a thyristor protection circuit of a soft starter, including thyristor SCR3, thyristor SCR4, resistor R6, resistor R7, capacitor C6, capacitor C7 and switch S;

[0030] One end of the resistor R6 is connected to the anode of the thyristor SCR3, one end of the switch S and the cathode of the thyristor SCR4 and then connected to an external power supply. The cathode of the thyristor SCR3 is connected to one end of the capacitor C6, one end of the capacitor C7 and the anode of the thyristor SCR4 and then connected to an external controlled motor. The other end of the resistor R6 is connected to the other end of the capacitor C6, the other end of the capacitor C7 is connected to one end of the resistor R7, the other end of the switch K is connected to the other end of the resistor R7, and the control electrode of the thyristor SCR3 and the control electrode of the thyristor SCR4 are respectively connected to external processor circuits.

[0031] In this embodiment, thyristor SCR3 and thyristor SCR4 correspond to a processor circuit respectively, and each is controlled to be turned on or off by the processor circuit; when soft starting is working, closing switch S, connecting resistor R7 and capacitor C7 in parallel with resistor R6 and capacitor C6, can effectively reduce the loss of hot standby, reduce the power of the resistance value, and reduce the heat generation.

[0032] In some embodiments of this specification, Figure 2 As shown, the processor circuit includes a processor, an input terminal P1, an output terminal P2, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a capacitor C3, a capacitor C4, a capacitor C5 and an operational amplifier U1;

[0033] The processor is connected to the input terminal P1, the input terminal P1 is connected to one end of the resistor R2, the other end of the resistor R2 is connected to one end of the resistor R3, one end of the resistor R4 and a grounded capacitor C3, the other end of the resistor R3 is connected to one end of the capacitor C4 and an inverting end of the operational amplifier U1, the non-inverting end of the operational amplifier U1 is grounded, the other end of the resistor R4 is connected to the other end of the capacitor C4, one end of the resistor R5 and an output end of the operational amplifier U1, and the other end of the resistor R5 is connected to the output terminal P2 and the grounded capacitor C5.

[0034] In this embodiment, the components other than the processor in the processor circuit constitute a filter subcircuit. The number of filter subcircuits depends on the number of thyristors. For example, if there are thyristors SCR1 and SCR2, there are two filter subcircuits, and their respective output terminals P2 are respectively connected to the control electrodes of thyristors SCR1 and SCR2; the same applies to thyristors SCR3 and SCR4.

[0035] In some embodiments, the processor is a MUC, DSP, PLC, ASIC or FPGA chip.

[0036] In some embodiments, the operational amplifier U1 is of model LM358.

[0037] The technical idea of ​​the utility model is: according to the RC value that reduces the critical rise rate of the off-state voltage and prevents the thyristor from being mis-turned on, it ensures that the thyristor in the soft start hot standby state will not be mis-turned on, and at the same time greatly reduces the loss on the hot standby state RC. Before the soft start, a larger absorption capacitor or a larger set of RC absorption parameters is invested to ensure the protection of the thyristor during the soft start process.

[0038] The above embodiments describe multiple specific implementations of the present invention, but those skilled in the art should understand that various changes or modifications can be made to these implementations without departing from the principles and essence of the present invention, but these changes and modifications are all within the scope of protection of the present invention.

Claims

1. A thyristor protection circuit for a soft starter, characterized in that: It includes thyristor SCR1, thyristor SCR2, resistor R1, capacitor C1, capacitor C2 and switch K; One end of the resistor R1 is connected to the anode of the thyristor SCR1 and the cathode of the thyristor SCR2 and then connected to an external power supply. The cathode of the thyristor SCR1 is connected to one end of the capacitor C1, one end of the capacitor C2 and the anode of the thyristor SCR2 and then connected to an external controlled motor. The other end of the resistor R1 is connected to the other end of the capacitor C1 and one end of the switch K, and the other end of the switch K is connected to the other end of the capacitor C2. The control electrode of the thyristor SCR1 and the control electrode of the thyristor SCR2 are respectively connected to an external processor circuit.

2. The thyristor protection circuit of the soft starter according to claim 1, characterized in that: The processor circuit includes a processor, an input terminal P1, an output terminal P2, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a capacitor C3, a capacitor C4, a capacitor C5 and an operational amplifier U1; The processor is connected to the input terminal P1, the input terminal P1 is connected to one end of the resistor R2, the other end of the resistor R2 is connected to one end of the resistor R3, one end of the resistor R4 and a grounded capacitor C3, the other end of the resistor R3 is connected to one end of the capacitor C4 and an inverting end of the operational amplifier U1, the non-inverting end of the operational amplifier U1 is grounded, the other end of the resistor R4 is connected to the other end of the capacitor C4, one end of the resistor R5 and an output end of the operational amplifier U1, and the other end of the resistor R5 is connected to the output terminal P2 and the grounded capacitor C5.

3. The thyristor protection circuit of the soft starter according to claim 2, characterized in that: The processor is a MUC, DSP, PLC, ASIC or FPGA chip.

4. The thyristor protection circuit of the soft starter according to claim 2, characterized in that: The model of the operational amplifier U1 is LM358.

5. A thyristor protection circuit for a soft starter, characterized in that: It includes thyristor SCR3, thyristor SCR4, resistor R6, resistor R7, capacitor C6, capacitor C7 and switch S; One end of the resistor R6 is connected to the anode of the thyristor SCR3, one end of the switch S and the cathode of the thyristor SCR4 and then connected to an external power supply. The cathode of the thyristor SCR3 is connected to one end of the capacitor C6, one end of the capacitor C7 and the anode of the thyristor SCR4 and then connected to an external controlled motor. The other end of the resistor R6 is connected to the other end of the capacitor C6, the other end of the capacitor C7 is connected to one end of the resistor R7, the other end of the switch K is connected to the other end of the resistor R7, and the control electrode of the thyristor SCR3 and the control electrode of the thyristor SCR4 are respectively connected to external processor circuits.

6. The thyristor protection circuit of the soft starter according to claim 5, characterized in that: The processor circuit includes a processor, an input terminal P1, an output terminal P2, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a capacitor C3, a capacitor C4, a capacitor C5 and an operational amplifier U1; The processor is connected to the input terminal P1, the input terminal P1 is connected to one end of the resistor R2, the other end of the resistor R2 is connected to one end of the resistor R3, one end of the resistor R4 and a grounded capacitor C3, the other end of the resistor R3 is connected to one end of the capacitor C4 and an inverting end of the operational amplifier U1, the non-inverting end of the operational amplifier U1 is grounded, the other end of the resistor R4 is connected to the other end of the capacitor C4, one end of the resistor R5 and an output end of the operational amplifier U1, and the other end of the resistor R5 is connected to the output terminal P2 and the grounded capacitor C5.

7. The thyristor protection circuit of the soft starter according to claim 6, characterized in that: The processor is a MUC, DSP, PLC, ASIC or FPGA chip.

8. The thyristor protection circuit of the soft starter according to claim 6, characterized in that: The model of the operational amplifier U1 is LM358.

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