Alternating current power supply system input surge current suppression circuit and working method

Abstract

The invention discloses an AC power supply system input surge current suppression circuit and a working method.The AC power supply system input surge current suppression circuit comprises a charging module, a first voltage detection module and a second voltage detection module, the first voltage detection module and the second voltage detection module are connected with the charging module, charging is conducted through a power resistor, and when the voltage reaches the detection voltage of the first voltage detection circuit, the power resistor is cut off; charging is carried out through the bidirectional thyristor, the problems that after a traditional power resistor operates for a period of time, the resistance value is extremely reduced, large power-on current impact is borne, and the size is large when a large-power relay is used are solved, and the defects that an alternating current power supply system cannot be powered on repeatedly in a short time and is large in size are overcome. And when the second voltage is reached through the second voltage detection circuit, the post-stage POWER module is started, so that the alternating current power supply system starts to work, and the power-on reliability of the post-stage POWER module of the alternating current power supply system is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of AC power supply systems, and in particular relates to an input surge current suppression circuit and a working method for an AC power supply system. Background Art

[0002] Currently, there are usually two technical solutions for implementing the input surge current suppression circuit of the AC power supply system.

[0003] The first technical solution: Use a thermistor. The higher the temperature of the thermistor, the lower the resistance. This limits the initial power-on current. After running for a period of time, the resistance of the thermistor drops sharply, which is approximately considered to be a short-circuit state. Since the thermistor needs to withstand a large power-on current shock, the disadvantage of this technical solution is that it is not suitable for high-power (200W) AC power supply products. Also, since it takes a long time for the thermistor to return to its cold resistance, it is also not suitable for products that require frequent power on and off.

[0004] The second technical solution is to use a high-power relay in parallel with a power resistor. The implementation form is that when the power is initially turned on, the relay is disconnected and the current is limited by the power resistor. After the charging is completed, the relay is closed. Due to the large size of the high-power relay, this technical solution requires a larger space to implement. In addition, when this technical solution is used, the contacts of the relay are prone to arcing due to the energized action at the moment the relay is closed, and there is a risk of contact welding, and the reliability is low. Summary of the invention

[0005] The purpose of the present invention is to provide an input surge current suppression circuit and a working method for an AC power supply system, so as to solve the technical problems of poor power-on reliability and large product volume of the input surge current suppression circuit of the AC power supply system in the prior art.

[0006] In order to solve the above problems, the present invention adopts the following technical solutions: An input surge current suppression circuit for an AC power supply system comprises a charging module, a first voltage detection module and a second voltage detection module, wherein the first voltage detection module and the second voltage detection module are both connected to the charging module; The charging module includes a power resistor R3, a bidirectional thyristor Q1 connected in parallel with the power resistor R3, a component for driving the bidirectional thyristor Q1, a rectifier bridge V1 and a support capacitor C1. The bidirectional thyristor Q1 is connected in parallel with the power resistor R3 and then connected to the support capacitor C1 through the rectifier bridge V1; The first voltage detection module includes low temperature drift resistors R9, R14, a reference voltage source Q5 and a first switch circuit module, the low temperature drift resistor R9 is connected to the low temperature drift resistor R14, the connection end of the low temperature drift resistor R9 and the low temperature drift resistor R14 is connected to the reference end of the reference voltage source Q5, the cathode of the reference voltage source Q5 is connected to one end of the first switch circuit module, and the other end of the first switch circuit module is connected to the element for driving the bidirectional thyristor Q1; The second voltage detection module includes low-temperature drift resistors R4 and R7, a reference voltage source Q3, a second switch circuit module and a post-stage POWER module, the low-temperature drift resistor R4 is connected to the low-temperature drift resistor R7, the connecting end of the low-temperature drift resistor R4 and the low-temperature drift resistor R7 is connected to the reference end of the reference voltage source Q3, the cathode of the reference voltage source Q3 is connected to one end of the second switch circuit module, and the other end of the second switch circuit module is connected to the post-stage POWER module.

[0007] Furthermore, the low temperature drift resistor R9 of the first voltage detection module is connected to the high voltage end of the support capacitor C1 of the charging module.

[0008] Furthermore, the low temperature drift resistor R4 of the second voltage detection module is connected to the high voltage end of the support capacitor C1 of the charging module. Furthermore, it also includes a power supply circuit module, which is connected to the first voltage detection module and the second voltage detection module for power supply. Furthermore, the power supply circuit module includes a capacitor C3, a voltage regulator tube D1 and a resistor R8. The capacitor C3 is connected in parallel with the voltage regulator tube D1 and then connected in series with the resistor R8. Furthermore, the first switching circuit module includes a PNP transistor Q4 and a diode D2, the cathode of the reference voltage source Q5 is connected to the emitter of the PNP transistor Q4, the collector of the PNP transistor Q4 is connected to one end of the diode D2, and the other end of the diode D2 is connected to the element used to drive the bidirectional thyristor Q1. Furthermore, the element for driving the bidirectional thyristor Q1 is a bidirectional driving optocoupler, and the other end of the diode D2 is connected to the primary side of the bidirectional driving optocoupler. Furthermore, the second switch circuit module includes a PNP transistor Q2, and the cathode of the reference voltage source Q3 and the subsequent POWER module are both connected to the emitter of the PNP transistor Q2. A working method of an input surge current suppression circuit of an AC power supply system comprises the following steps: The charging module charges the supporting capacitor C1 through the power resistor R3; When the first voltage detection module detects that the voltage reaches the first voltage, the first switch circuit module starts the element for driving the bidirectional thyristor Q1, turns on the bidirectional thyristor Q1, and then cuts off the power resistor R3, and charges the support capacitor C1 through the bidirectional thyristor Q1; When the second voltage detection module detects that the voltage reaches the second voltage, the subsequent POWER module is started through the second switch circuit module, and the AC power supply system starts to work. Furthermore, the first voltage is 240V, and the second voltage is 280V. Compared with the prior art, the present invention has the following beneficial technical effects: The invention relates to an input surge current suppression circuit for an AC power supply system. A bidirectional thyristor and a driving element of the bidirectional thyristor are connected in parallel at a power resistor of a charging module, and two voltage detection circuit modules are provided. The two voltage detection circuit modules are respectively used for cutting off the power resistor and starting a subsequent POWER module, thereby ensuring the normal operation of the AC power supply system. The problem of poor reliability caused by the use of a thermistor in the input surge current suppression circuit of the current AC power supply system is solved, and the problem of large volume caused by the use of a high-power relay is also solved, thereby enhancing the power-on reliability of the AC power supply system.

[0009] Preferably, the power supply is connected to the first voltage detection module and the second voltage detection module through the power supply circuit module, so as to provide a relatively stable power supply for the voltage detection circuit, thereby ensuring that this part of the circuit can work.

[0010] Preferably, the driving pole of the bidirectional thyristor is connected to one end of the secondary side of the bidirectional drive optocoupler, and this part of the line is connected in series to the live wire of the AC output to ensure that the live wire loop is disconnected when a cut-off occurs, thereby ensuring the safety of personnel operation.

[0011] The present invention also provides a working method for an input surge current suppression circuit of an AC power supply system. The method first charges the circuit through a power resistor. When the voltage reaches the detection voltage of a first voltage detection circuit, the power resistor is cut off and the circuit is charged through a bidirectional thyristor. This solves the problem that the resistance of a traditional power resistor decreases greatly after running for a period of time, the power resistor is subjected to a large power-on current shock, and the power relay is large in size. This solves the shortcomings of the AC power supply system that the AC power supply system cannot be repeatedly powered on in a short period of time and has a large size, and increases the power-on reliability of the subsequent POWER module of the AC power supply system. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 This is a schematic diagram of the structure of an input surge current suppression circuit for an AC power supply system according to an embodiment of the present invention; Figure 2 The present invention is a flowchart of a working method of an input surge current suppression circuit of an AC power supply system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0012] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0013] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0014] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0015] Example 1 An input surge current suppression circuit for an AC power supply system, such as Figure 1 As shown, it includes a charging module and a first voltage detection module and a second voltage detection module connected to the charging module, wherein: Charging module: including a power resistor R3, a bidirectional thyristor Q1 connected in parallel with the power resistor R3, and a component connected in parallel with the bidirectional thyristor Q1 and used to drive the bidirectional thyristor Q1. After the bidirectional thyristor Q1 is connected in parallel with the power resistor R3, it is connected to the high voltage end of the supporting capacitor C1 through a rectifier bridge V1; The first voltage detection module and the second voltage detection module are used to detect the voltage of the charging module; The first voltage detection module: comprises a first voltage measurement module and a first switch circuit module, wherein the first voltage measurement module comprises a low temperature drift resistor R9, a low temperature drift resistor R14 connected to the low temperature drift resistor R9, and a reference voltage source Q5 connected to the connection end of the low temperature drift resistor R9 and the low temperature drift resistor R14, one end of the first switch circuit module is connected to the reference voltage source Q5, and the other end is connected to the element for driving the bidirectional thyristor Q1; The second voltage detection module: includes a second voltage measurement module and a second switch circuit module, wherein the first voltage measurement module includes a low-temperature drift resistor R4, a low-temperature drift resistor R7 connected to the low-temperature drift resistor R4, and a reference voltage source Q3 connected to the connection end of the low-temperature drift resistor R4 and the low-temperature drift resistor R7, and one end of the second switch circuit module is connected to the reference voltage source Q3, and the other end is connected to the post-stage POWER module. Specifically, the first voltage detection module is connected to the high voltage end of the support capacitor C1 of the charging module through the low temperature drift resistor R9, and the second voltage detection module is connected to the high voltage end of the support capacitor C1 of the charging module through the low temperature drift resistor R4, and the element used to drive the bidirectional thyristor Q1 adopts a bidirectional driving optocoupler; The circuit also includes a power supply circuit module, which is used to connect to the first voltage detection module and the second voltage detection module for power supply.

[0016] Example 2 like Figure 1 As shown, the circuit part protected by the present invention is composed of three parts, which are as follows: The first part of the circuit includes the following components: bidirectional thyristor Q1; bidirectional drive optocoupler U1; drive resistors R1 and R2; and power resistor R3. The functions of this part of the circuit are: when powered on, the power resistor R3 is used to limit the surge current. When the voltage threshold for turning on Q1 is reached, U1 drives Q1 to turn on, thereby cutting off the power resistor R3. When it is detected that the system power-on reaches the minimum input voltage, the subsequent POWER (power conversion part) is allowed to be turned on, and the AC power supply system starts to work. Among them, the bidirectional thyristor Q1 and the power resistor R3 are in parallel; the two ends of the secondary side of the bidirectional drive optocoupler U1 are connected in series with the drive resistors R1 and R2 respectively, and then connected in parallel with the power pole of the bidirectional thyristor Q1 through the two ends of the resistor, and the drive pole of the bidirectional thyristor Q1 is connected to one end of the secondary side of the bidirectional drive optocoupler U1. This part of the line is connected in series with the live wire of the AC output to ensure that the live wire loop is disconnected when a cut occurs, ensuring the safety of personnel operation; The AC output end of the rectifier bridge V1 is connected in parallel between the live wire and the neutral wire of the AC, and the rectifier output end of V1 is connected in parallel with the supporting capacitor C1.

[0017] The components included in the second part of the circuit are: low temperature drift detection resistors R9 and R14; adjustable precision reference voltage source Q5; PNP transistor Q4; diode D2; capacitors C4 and C3; resistors R8, R10, R11, R12 and R13; voltage regulator D1; the functions of R8, C3 and D1 are to provide a relatively stable power supply to ensure that this part of the circuit can work; R9 and R14 detect the input voltage of the AC power supply system. When it is detected that the voltage of the supporting capacitor reaches the set value (187V*1.414*0.9=240V), Q5 is turned on, Q4 is turned on, and the driving signal drives U1 through diode D2, thereby turning on Q1, thereby realizing the function of short-circuiting R3, turning on the drive of the bidirectional thyristor, and short-circuiting the power resistor R3, thereby reducing the heat generation of the system and enabling the normal operation of the product; Among them, one end of resistor R9 is connected to the high voltage end of capacitor C1 (i.e. the bus positive line), and the other end is connected to resistor R14. The connection end of R9 and R14 is connected to the reference end of Q5 reference chip; resistor R11 is connected in parallel with capacitor C4, connected in series with resistor R12, and then connected to the cathode of Q5; the anode of Q5 and one end of resistor R14 are connected to the power supply ground. Resistor R10 is connected to the emitter of transistor Q4, the base of Q4 is connected to the middle connection point of resistors R11 and R12, the collector of Q4 is connected in series with resistor R13, one end of R13 is connected to the system power supply ground, and the other end is connected to diode D2, and then connected to the primary side anode of bidirectional drive optocoupler U1; The components of the third circuit are: low temperature drift detection resistors R4 and R7; adjustable precision reference voltage source Q3; PNP transistor Q2; capacitor C2; resistors R5 and R6. The power supply of this circuit also comes from R8, C3, and D1; R4 and R7 detect the input voltage of the AC power supply system. When the voltage of the supporting capacitor reaches the set value (187V*1.414=260V), Q3 is turned on, Q2 is turned on, the power on / off command is valid, and the output of the subsequent POWER module is allowed; Among them, one end of resistor R4 is connected to the high voltage end of capacitor C1 (i.e. the bus positive line), and the other end is connected to resistor R7, and the connecting end of R4 and R7 is connected to the reference end of Q3 reference chip; resistor R6 is connected to the cathode of Q3 after being connected in parallel with capacitor C2; the anode of Q3 and one end of resistor R7 are connected to the power supply ground; resistor R5 is connected to the emitter of transistor Q2, the base of Q2 is connected to the cathode of Q3, and the emitter of Q2 is connected to the subsequent POWER (power module enable end).

[0018] After capacitor C3 is connected in parallel with the voltage regulator tube D1, it is connected in series with resistor R8. The other end of R8 is connected to the high voltage end of C1. One end of capacitor C3 and voltage regulator tube D1 is connected to the power supply ground of the system. The cathode end of D1 is connected to resistors R5 and R10 to power the two voltage detection circuits.

[0019] The present invention also provides a working method of an input surge current suppression circuit of an AC power supply system, such as Figure 2 As shown, the following steps are included: The charging module charges the supporting capacitor C1 through the power resistor R3; When the first voltage detection module detects that the voltage reaches the first voltage, the first switch circuit module starts the element for driving the bidirectional thyristor Q1, turns on the bidirectional thyristor Q1, and then cuts off the power resistor R3, and charges the support capacitor C1 through the bidirectional thyristor Q1; When the second voltage detection module detects that the voltage reaches the second voltage, the subsequent POWER module is started through the second switch circuit module, and the AC power supply system starts to work.

[0020] Specifically, the two voltage detection modules always work with the charging module. The two voltage detection modules are started in sequence: the first voltage detection module is started first, the power resistor R3 is short-circuited and cut off through the first voltage detection module, and the bidirectional thyristor Q1 is started to charge the supporting capacitor C1, thereby solving the problem of poor reliability of only thermistors in the traditional method, and also solving the problem of large volume when using high-power relays. When the second voltage detection circuit reaches the second voltage through the second voltage detection module, the subsequent POWER module is started to make the AC power supply system start working, thereby optimizing the power-on interface circuit of the AC power supply system and increasing the power-on reliability of the AC power supply system.

[0021] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. An input surge current suppression circuit for an AC power supply system, characterized in that: It includes a charging module, a first voltage detection module and a second voltage detection module, wherein the first voltage detection module and the second voltage detection module are both connected to the charging module; The charging module includes a power resistor R3, a bidirectional thyristor Q1 connected in parallel with the power resistor R3, a component for driving the bidirectional thyristor Q1, a rectifier bridge V1 and a support capacitor C1. The bidirectional thyristor Q1 is connected in parallel with the power resistor R3 and then connected to the support capacitor C1 through the rectifier bridge V1; The first voltage detection module includes low temperature drift resistors R9, R14, a reference voltage source Q5 and a first switch circuit module, the low temperature drift resistor R9 is connected to the low temperature drift resistor R14, the connection end of the low temperature drift resistor R9 and the low temperature drift resistor R14 is connected to the reference end of the reference voltage source Q5, the cathode of the reference voltage source Q5 is connected to one end of the first switch circuit module, and the other end of the first switch circuit module is connected to the element for driving the bidirectional thyristor Q1; The second voltage detection module includes low-temperature drift resistors R4 and R7, a reference voltage source Q3, a second switch circuit module and a post-stage POWER module, the low-temperature drift resistor R4 is connected to the low-temperature drift resistor R7, the connecting end of the low-temperature drift resistor R4 and the low-temperature drift resistor R7 is connected to the reference end of the reference voltage source Q3, the cathode of the reference voltage source Q3 is connected to one end of the second switch circuit module, and the other end of the second switch circuit module is connected to the post-stage POWER module.

2. The input surge current suppression circuit of an AC power supply system according to claim 1, characterized in that: The low temperature drift resistor R9 of the first voltage detection module is connected to the high voltage end of the support capacitor C1 of the charging module.

3. The input surge current suppression circuit of an AC power supply system according to claim 1, characterized in that: The low temperature drift resistor R4 of the second voltage detection module is connected to the high voltage end of the support capacitor C1 of the charging module.

4. The input surge current suppression circuit of an AC power supply system according to claim 1, characterized in that: It also includes a power supply circuit module, which is connected to the first voltage detection module and the second voltage detection module for power supply.

5. The input surge current suppression circuit of an AC power supply system according to claim 4, characterized in that: The power supply circuit module includes a capacitor C3, a voltage regulator tube D1 and a resistor R8. The capacitor C3 is connected in parallel with the voltage regulator tube D1 and then connected in series with the resistor R8.

6. The input surge current suppression circuit of an AC power supply system according to claim 1, characterized in that: The first switch circuit module includes a PNP transistor Q4 and a diode D2, the cathode of the reference voltage source Q5 is connected to the emitter of the PNP transistor Q4, the collector of the PNP transistor Q4 is connected to one end of the diode D2, and the other end of the diode D2 is connected to a component for driving the bidirectional thyristor Q1.

7. The input surge current suppression circuit of an AC power supply system according to claim 6, characterized in that: The element for driving the bidirectional thyristor Q1 is a bidirectional driving optocoupler, and the other end of the diode D2 is connected to the primary side of the bidirectional driving optocoupler.

8. The input surge current suppression circuit of an AC power supply system according to claim 1, characterized in that: The second switch circuit module includes a PNP transistor Q2, and the cathode of the reference voltage source Q3 and the subsequent POWER module are both connected to the emitter of the PNP transistor Q2.

9. A working method of an input surge current suppression circuit of an AC power supply system according to claim 1, characterized in that: The following steps are involved: The charging module charges the supporting capacitor C1 through the power resistor R3; When the first voltage detection module detects that the voltage reaches the first voltage, the first switch circuit module starts the element for driving the bidirectional thyristor Q1, turns on the bidirectional thyristor Q1, and then cuts off the power resistor R3, and charges the support capacitor C1 through the bidirectional thyristor Q1; When the second voltage detection module detects that the voltage reaches the second voltage, the subsequent POWER module is started through the second switch circuit module, and the AC power supply system starts to work.

10. The three-phase Hall signal decoding method of a brushless DC motor driver according to claim 9, characterized in that: The first voltage is 240V, and the second voltage is 280V.

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