CN101976880A - Intelligent device for voltage dip protection - Google Patents

Abstract

The invention relates to an intelligent device for voltage drop protection, which is suitable for a full series of electromagnetic AC contactor voltage drop protection intelligent modules. Low-voltage DC maintenance, energy-saving and silent operation, has the characteristics of fault display, alarm, adjustable protection time, and strong versatility.

Description

An intelligent device for voltage drop protection

technical field

The invention relates to the field of intelligent control of equipment, in particular to an intelligent device for voltage drop protection.

Background technique

With the development of society and the advancement of technology, new technology industries are constantly emerging, and power users are paying more attention to power quality issues than ever before. For large iron and steel enterprises, petrochemical enterprises, chemical enterprises, etc., the economic losses caused by motor failure due to power grid quality problems have a huge impact. The power system will encounter a variety of faults during operation. Due to lightning strikes, short-circuit fault reclosing, external or internal power grid faults, and large-scale equipment startups, etc., the voltage fluctuates greatly instantaneously or the power is restored after a short-term power failure. The phenomenon of temporary voltage drop has a great impact on users, especially in important areas of continuous work.

When the voltage suddenly drops, the current system often adopts the operation mode of delayed power failure, and the delay time of this mode is often fixed, or the working mode of dual power supply is used, which is costly and limited in application. At present, there are a few protection products against voltage drops on the market, such as anti-sway AC contactors, anti-sway delay modules, anti-sway motor intelligent controllers, etc. Anti-sway AC contactors must design different anti-sway modules for different types of contactors. Due to the wide variety of AC contactors, special contactor manufacturers must be able to produce them, and it will also affect the installation position of the AC contactor. Its promotion is subject to certain restrictions. At present, the anti-sway delay modules that are matched with control electrical appliances on the market have few manufacturers, and most of the control lines use relay control schemes. There are problems such as contactor contact vibration and unreliable actions during switching, and urgently need to be improved. Therefore, the development of a voltage drop protection intelligent module with wide application range, strong versatility, reliable operation and high cost performance will have broad application prospects when used in conjunction with a series of electromagnetic AC contactors.

Electromagnetic AC contactor is an electrical product with a large quantity and a wide range. It is an automatic switcher used to switch on or off the AC main circuit with load or large-capacity control circuit. When the circuit voltage suddenly drops, the AC contactor may be frequently connected or disconnected due to unstable voltage, which will have a great impact on the circuit. With the rapid development of power electronics technology, computer technology, and intelligent electrical control technology, the intelligent control and protection technology of low-voltage electrical appliances has received comprehensive attention. Under the premise of not changing the structure of electrical appliances, the corresponding intelligent modules are designed and combined with electrical appliances. It is possible to complete various control and protection functions.

Contents of the invention

The purpose of the invention is to control the AC contactor to maintain the holding state by the intelligent device when the grid voltage suddenly drops, so that the AC contactor is normally disconnected when the voltage drop does not occur. The device has the characteristics of small size, wide application range (suitable for all series of electromagnetic AC contactors), step-down DC start, DC low voltage maintenance, energy-saving and silent operation, etc.

The present invention is achieved as follows: an intelligent device for voltage drop protection, including a high-power rectification circuit D1 and a rectification circuit D2 connected in parallel to the AC mains, characterized in that the output power of the high-power rectification circuit D1 After one path passes through a DC step-down module R1, it is added to the coil C of the AC contactor through the first switch tube A. The coil C is provided with a clamp control circuit I for judging the state of the AC contactor. The clamp The output end of the control circuit I is connected to the single-chip microcomputer S through a conversion control circuit J; the other path of the output power of the high-power rectifier circuit D1 is connected to a switching power supply module M through a switch tube module K, and the switching power supply module M It includes four outputs, the first output of which is applied to the contactor coil circuit through the first voltage stabilization circuit P1, the voltage adjustment module R2 and the second switch tube B; the second output is charged for the backup power supply through the second voltage stabilization circuit P2 The module U is charged; the third output is connected to the driving module T of the first and second switching tubes through a bias power supply P3; the fourth output is powered for the single-chip microcomputer through the voltage adjustment module P4; the output terminal of the voltage adjustment module P4 A power feedback module N is connected, and the output end of the power feedback module N is connected to the switch tube module K; the output end of the single-chip microcomputer S is connected to the first control module E of the first switch tube A and the second switch tube The second control module F of B; the other output terminal of the single-chip microcomputer S also controls the voltage drop control module L through the voltage drop conversion module Q to start the backup power supply module O that provides backup power for the coil loop, and the backup power supply The module O also supplies power to the single-chip microcomputer S via a step-down module V; the single-chip microcomputer S is also connected to a sampling module H for collecting output signals of the rectification circuit D2 and a human-computer interaction and alarm module S1.

The present invention has the following advantages:

(1) DC step-down starting function. According to the control characteristics of DC high-voltage start and low-voltage maintenance, the step-down start control mode of the start circuit is designed. This step-down module can greatly reduce the impact on the AC contactor during the start-up process, especially the switch Manage the workload of A, so that the scope of application of the control module is greatly expanded. This principle can be used in the energy-saving control module and the control module of the intelligent AC contactor;

(2) Voltage drop protection function. When a voltage drop accident occurs in the circuit, the AC contactor is controlled by the control module to keep it in the holding state, and it is broken under normal conditions. The backup power supply freewheeling circuit is not started, and the contactor is quickly broken;

(3) DC holding adjustable function. According to the coil and iron core parameters of different types of AC contactors, the holding DC voltage of the contactor is designed and adjusted by itself, and the module has a wide range of applications;

(4) It has the jogging control function of quick breaking. After adopting intelligent module control, the starting and stopping time of the AC contactor is prolonged, which is a common problem of the current intelligent AC contactor, and it will not be able to meet the requirements in the case of inching and fast action. The module is designed with a clamp The position control circuit and the conversion control circuit directly make the contactor enter the fast breaking working mode in the occasion where a quick breaking contactor is required;

(5) It has the functions of display, alarm and adjustable protection time. On the panel, parameters such as starting voltage reduction module, maintaining voltage module, and voltage drop delay time can be adjusted and set, and it has normal operation indication and fault alarm functions.

Description of drawings

Fig. 1 is a schematic block diagram of the circuit of the present invention.

Detailed ways

As shown in Figure 1, the present invention provides an intelligent device for voltage drop protection, including a high-power rectification circuit D1 and a rectification circuit D2 connected in parallel to the AC mains, characterized in that: the high-power rectification circuit D1 After the output power supply passes through a DC step-down module R1, it is added to the coil C of the AC contactor through the first switch tube A, and the coil C is provided with a clamping control circuit I for judging the state of the AC contactor. The output terminal of the clamp control circuit I is connected with the single-chip microcomputer S through a conversion control circuit J; the other path of the output power supply of the high-power rectifier circuit D1 is connected with a switching power supply module M through a switching tube module K, and the switching power supply Module M includes four outputs, the first output of which is applied to the coil circuit of the contactor through the first voltage regulator circuit P1, the voltage adjustment module R2 and the second switch tube B; the second output is backed up by the second voltage regulator circuit P2 The power supply charging module U charges; the third output is connected to the drive module T of the first and second switching tubes through a bias power supply P3; the fourth output is powered for the single-chip microcomputer through the voltage adjustment module P4; the voltage adjustment module P4 The output end is connected to a power feedback module N, and the output end of the power feedback module N is connected to the switch tube module K; the output end of the single-chip microcomputer S is connected to the first control module E of the first switch tube A and the second The second control module F of the switch tube B; the other output end of the single-chip microcomputer S also controls the voltage drop control module L through the voltage drop conversion module Q to start the backup power supply module O that provides backup power for the coil loop, the described The backup power supply module O also supplies power to the single-chip microcomputer S through a step-down module V; the single-chip microcomputer S is also connected with a sampling module H for collecting output signals of the rectification circuit D2 and a human-computer interaction and alarm module S1.

In order to allow those of ordinary skill to understand the present invention more clearly, the working principle of the present invention will be described below in conjunction with the accompanying drawings:

As shown in Figure 1, the AC 220V power supply is divided into two channels from 1 and 2, and one channel is supplied to the rectifier circuit D2, and the power supply voltage is directly sampled through the sampling module H. This sampling method greatly reduces the interference and influence of the switching power supply on the sampling voltage, and improves the operational reliability of the system. The sampling voltage 7 is input into the single-chip microcomputer system S, and the power supply voltage is judged by the single-chip microcomputer system. If it is within the normal working voltage range of the AC contactor, the single-chip microcomputer system issues an instruction to apply a high level to the drive control module E through the control signal 3, and the switch tube A is turned on, and at this time the AC contactor enters the DC high voltage starting stage. In this stage, there is an important module, that is, the DC step-down module R1, which is one of the important modules and features of the present invention. When the AC contactor is in the working state of DC start and DC hold, in the electromagnetic mechanism, the magnetic reactance and inductance have changed greatly, which greatly increases the current value. If the electromagnetic mechanism of the large-capacity AC contactor is used Said that its starting current is very large, therefore, the first switching tube A cannot meet the control requirements of a large-capacity AC contactor, and after it becomes a DC starting working mode, as long as the equivalent magnetic potential of its mechanism can meet the starting of the electromagnetic mechanism Magnetic potential requirements, it can work normally. Therefore, the DC step-down module circuit is designed. This module can set different step-down gears according to the needs, and the adjustment of the starting voltage can be realized through the switching switch on the panel of the display module S1. Although a step-down module is added to the starting circuit, because the DC high voltage starting period is very short, generally within tens of milliseconds, when the contactor is reliably closed, the single-chip microcomputer system will start the DC holding circuit and cut off the starting circuit. , so that the circuit loss will not be significantly increased, and the capacity and cost of the first switching tube A can be greatly reduced, so as to meet the control requirements of AC contactors with different capacities, and the module has a wide range of applications.

The other path of the AC 220V power supply is rectified and filtered by the high-power rectifier circuit D1, and then becomes a DC power supply, which is divided into the following two paths:

(1) High voltage starter power supply for AC contactor. After the power supply passes through the DC step-down module R1, it is applied to the coil of the AC contactor through the first switch tube A, and G1 and G2 are protection circuits. During the operation of the AC contactor, it often encounters the control state that needs to quickly cut off the circuit or jog control, which is difficult for the AC contactor system using the intelligent control module, and the contactor after the intelligent control is often used It takes a certain amount of time to start and break. Therefore, the present invention designs a clamp control circuit I for the coil of the AC contactor. The function of this circuit is to judge whether the AC contactor is in the pull-in state. If the AC contactor is in the pull-in state and the coil circuit has electricity, then the The clamping circuit will output a signal to the conversion control circuit J, which will send a control command 5 to the single-chip microcomputer system. After the single-chip microcomputer system receives the signal of command 5, all control programs will run normally; on the contrary, if the AC contactor is in the disconnected state, That is, the electromagnetic mechanism of the contactor is in the power-off state, and the clamping control circuit will automatically reset the single-chip microcomputer system to realize instantaneous forced shutdown, realize rapid breaking of the contactor or realize jog control, and will not start the voltage drop protection program.

(2) In this implementation example, the switching power supply module described adopts a wide-voltage input high-frequency switching power supply design based on the TinySwith-Ⅲ single-chip switching power supply chip TNY280PN. TNY280YN has functions such as wide-range voltage input, undervoltage protection, overvoltage protection, overheating protection, current limiting protection, and power switch tube self-adaptation. Once the control module fails, such as overload, short circuit or open loop, it can realize the protection function of automatically shutting down the switching power supply. When the system returns to normal, it can realize automatic restart. The power module has good protection function and stable performance , N is the feedback circuit of the switching power supply. The switching power supply module has four power supply outputs. P1 is the power supply of the DC low voltage holding circuit, which is applied to the coil circuit of the contactor through the voltage adjustment module R2. Similarly, the voltage adjustment module R2 is also a special feature of the present invention. Through this module, the holding control voltage of the contactor can be adjusted to suit different AC contactors. This module can also be set and adjusted on the panel. When the AC contactor is reliably closed, the single-chip microcomputer system turns off the control signal 3 and turns on the control signal 4, so that the first switch tube A is turned off, the switch tube B is turned on, and the AC contactor enters the DC low voltage maintenance stage, and F is the second The control module of the switch tube B controls the switching on and off of the switch tube B.

P2 is the power supply voltage required by the backup power module U, and P2 is connected to the backup power module U, which contains a rechargeable battery and a fully automatic charging circuit. The fully automatic charging circuit is monitored and started by the single-chip microcomputer control system.

The single-chip microcomputer system of the present invention can have two kinds of operation control modes: (1) adopt the control scheme of double CPU, in this scheme, the backup power charging system adopts one chip control alone, and this charging system can monitor the electric quantity of backup power in real time, once When the power is found to be insufficient, the charging control circuit is activated to charge the battery in real time to ensure that the power of the battery is within the normal range. The main single-chip microcomputer system realizes DC step-down high-voltage start, low-voltage maintenance, voltage drop control and protection, display and alarm, energy-saving and silent operation control. The scheme is flexible in control and reliable in operation. (2) Adopt the operating mode of single CPU. A single-chip microcomputer is used in the scheme, and the single-chip microcomputer system samples the system voltage and the backup power supply interleavedly, and all operation commands of the module are controlled by a single-chip microcomputer system. The program design of this program is relatively complicated, and the mutual interference and coordination problems between the systems must be considered in the design.

In this implementation example, the voltage drop protection module adopts a dual-CUP control mode.

When it is detected that the power supply voltage is lower than the working voltage of the AC contactor, the single-chip microcomputer system turns off the control signal 4 and turns on the control signal 6, the voltage drop conversion module Q starts to work, triggers the voltage drop control module L, and starts the backup power supply mode, O is The backup power supply provided to the coil circuit, because the power supply voltage supply is not normal at this time, so the backup power supply must also supply power to the single-chip microcomputer system S, and the backup power supply O generates a suitable power supply after passing through the step-down control module V to supply power to the single-chip microcomputer system. the

P3 is the bias voltage of high-power switching tubes A and B, and the power supply and other power supply modules cannot share the same ground.

P4 is the power supply of the one-chip computer system. When the power supply voltage is at a normal value, the single-chip microcomputer system is powered by P4, the backup power supply system is always in a standby state, the battery is completely isolated from the circuit, and there is no other power consumption except for self-discharge. In the event of a voltage drop failure, start the backup power supply.

The switching power supply adopts self-designed shielded winding high-frequency transformer, and adopts stacked winding method, which not only saves wires, reduces volume and cost, but also enhances the mutual inductance between windings and increases the degree of coupling; at the same time, the shielded winding can enhance the anti-interference ability. Prevent high-frequency interference from radiating into space, and the system performance is more reliable.

The display module S1 has functions such as adjustable voltage drop fault protection time, fault alarm, normal operation indication, adjustable starting and step-down module, and adjustable holding voltage.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

Claims (5)

1. one kind is used for the intelligent apparatus that electric voltage dropping is protected, comprise the power rectifier circuit (D1) and the rectification circuit (D2) that are connected to electric main, it is characterized in that: the out-put supply one tunnel of described power rectifier circuit (D1) is after a direct current step-down module (R1), be added in by first switching tube (A) on the coil (C) of A.C. contactor, described coil (C) is provided with a clamper control circuit (I) that is used to judge the A.C. contactor state, and the output of described clamper control circuit (I) is connected with single-chip microcomputer (S) through a conversion control circuit (J); Another Lu Jingyi switching tube module (K) of the out-put supply of described power rectifier circuit (D1) is connected with a switch power module (M), described switch power module (M) comprises four tunnel outputs, and the output of its first via is applied to the contactor coil loop through first voltage stabilizing circuit (P1) and voltage regulator module (R2) and second switch pipe (B); The second tunnel output is back-up source charging module (U) charging through second voltage stabilizing circuit (P2); Third Road output links to each other through the driver module (T) of a bias supply (P3) and first, second switching tube; The four tunnel output is the single-chip microcomputer power supply through voltage regulator module (P4); The output of described voltage regulator module (P4) is connected with power supply feedback module (N), and the output of described power supply feedback module (N) links to each other with described switching tube module (K); The output of described single-chip microcomputer (S) is connected with first control module (E) of first switching tube (A) and second control module (F) of second switch pipe (B); Another output of described single-chip microcomputer (S) also starts the back-up source module (O) that back-up source is provided for wire loop through electric voltage dropping modular converter (Q) control electric voltage dropping control module (L), and described back-up source module (O) is described single-chip microcomputer (S) power supply through a step-down module (V) also; Described single-chip microcomputer (S) also is connected with the sampling module (H) of gathering rectification circuit (D2) output signal and man-machine interaction, alarm module (S1).

2. the intelligent apparatus that is used for the electric voltage dropping protection according to claim 1 is characterized in that: described switch power module (M) adopts the wide voltage input high frequency switch power design based on TinySwith-III single-chip switching power supply chip TNY280PN.

3. the intelligent apparatus that is used for the electric voltage dropping protection according to claim 2 is characterized in that: described switch power module adopts shielding winding high frequency transformer, and winding adopts the stack winding.

4. the intelligent apparatus that is used for the electric voltage dropping protection according to claim 1, it is characterized in that: the output of described power rectifier circuit (D1) is provided with first protective circuit (G1).

5. the intelligent apparatus that is used for the electric voltage dropping protection according to claim 1, it is characterized in that: described contactor coil loop is provided with second protective circuit (G2).

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