CN114914877A

CN114914877A - Composite relay short-circuit protection circuit

Info

Publication number: CN114914877A
Application number: CN202210463408.7A
Authority: CN
Inventors: 李文华; 姜泊
Original assignee: Hebei University of Technology
Current assignee: Hebei University of Technology
Priority date: 2022-04-29
Filing date: 2022-04-29
Publication date: 2022-08-16

Abstract

The invention relates to a short-circuit protection circuit of a composite relay, which comprises a power supply module and a control module, wherein the control module comprises an IGBT current judgment circuit, a logic fault judgment circuit, a latch circuit, a drive circuit and a fast acting relay, and the fast acting relay comprises a normally closed contact which is connected in series with a branch where the IGBT is located. The invention can avoid short circuit between the upper contact and the lower contact of the relay caused by short circuit of the IGBT and improve the safety of a circuit system.

Description

Composite relay short-circuit protection circuit

Technical Field

The invention relates to the technical field of electrical appliance intellectualization, in particular to a short-circuit protection circuit of a composite relay.

Background

In the field of switching electrical appliances, mechanical contacts are generally used as devices for opening and closing loads, and an existing mechanical contact relay generally comprises a static upper contact, a static lower contact, a movable contact arranged between the upper contact and the lower contact and a coil for controlling the action of the movable contact.

The existing all-solid-state relay avoids the problem of arc ablation, but the switching loss of the all-solid-state relay is large, and because the load current is borne by a power electronic device, the heat is serious, a radiator with a large volume needs to be additionally arranged, and the problem of overvoltage and overcurrent damage exists.

The existing composite relay generally has the principle that load current is borne through a mechanical contact, Insulated Gate Bipolar Transistors (IGBTs) are connected in parallel on two sides of a movable contact and an upper contact and two sides of the movable contact and a lower contact, and the IGBTs with breaking actions are conducted only when the mechanical contact acts, so that the advantages of the two relays are combined, but in consideration of the complexity of a working environment, the IGBTs can be broken down, the upper contact and the lower contact of the relay are short-circuited, and safety accidents are caused.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a composite relay short-circuit protection circuit.

The invention is realized by the following technical scheme:

the utility model provides a compound relay short-circuit protection circuit, its characterized in that, includes power module and control module, control module includes IGBT current judgement circuit, logic fault judgement circuit, latch circuit, drive circuit and fast action relay, the fast action relay includes the normally closed contact of establishing ties to IGBT place branch road, wherein:

the IGBT current judging circuit is used for judging whether the contact point current is transferred to the IGBT according to the current passing through the IGBT and transmitting a first signal indicating a judging result to the logic fault judging circuit;

the logic fault judgment circuit judges whether the IGBT is broken down according to the first signal and the IGBT grid control signal and transmits a second signal indicating a judgment result to the latch circuit;

the latch circuit is used for receiving the second signal, and if the latch circuit receives the second signal indicating that the IGBT is broken down, the latch circuit latches the second signal, generates a driving signal at the same time, and transmits the driving signal to the driving circuit;

and if the driving circuit receives the driving signal, the normally closed contact of the quick action relay is controlled to be disconnected.

Preferably, the input end of the power supply module is connected with the positive pole and the negative pole of the coil voltage, the control module further comprises a magnetic latching relay, the fast acting relay comprises a normally closed contact connected in series to a branch where the IGBT is located, and if the driving circuit receives a driving signal, the normally closed contact of the magnetic latching relay is controlled to be disconnected.

Preferably, the IGBT current determination circuit includes a current sensor and a voltage comparator, the current sensor is configured to detect a current passing through the IGBT and convert the current into a voltage, the voltage comparator is configured to determine a voltage output by the current sensor, and if the current passing through the IGBT is detected to be greater than a preset threshold, the output first signal is at a high level.

Preferably, the logic fault determination circuit includes an inverter and an and gate, and if it is detected that the first signal is at a high level and the IGBT gate control signal is at a low level, the output second signal is at a high level.

The invention has the beneficial effects that:

the invention can avoid short circuit between the upper contact and the lower contact of the relay caused by short circuit of the IGBT, thereby improving the safety of the circuit system; the power supply module does not need to be additionally provided with a control power supply, so that the whole circuit can be simplified; the magnetic latching relay is used for preventing the problem that the quick-acting relay is reconnected to the fault branch circuit after the coil is powered off, so that the safety of a circuit system can be further improved; the logic fault judging circuit has strong anti-interference performance and can avoid false operation of the fast acting relay and the magnetic latching relay.

Drawings

FIG. 1 is a block diagram of a control module according to the present invention.

Fig. 2 is a timing diagram of normal operation of the composite relay.

Fig. 3 is an operation timing diagram after the breakdown fault of the composite relay occurs.

Fig. 4 is a graph of contact voltage waveforms after a breakdown fault occurs in the composite relay.

Detailed Description

In order to make the technical solutions of the present invention better understood by those skilled in the art, the present invention will be further described in detail with reference to the accompanying drawings and preferred embodiments.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

The utility model provides a compound relay short-circuit protection circuit, its characterized in that, includes power module and control module, and power module is used for supplying power to control module, control module includes IGBT current judgement circuit, logic fault judgement circuit, latch circuit, drive circuit and fast action relay, fast action relay includes the normally closed contact of establishing ties to IGBT place branch road, wherein:

the IGBT current judging circuit is used for judging whether the contact current is transferred to the IGBT according to the current passing through the IGBT and transmitting a first signal indicating a judging result to the logic fault judging circuit;

the latch circuit is used for receiving the second signal, if the second signal indicating that the IGBT is broken down is received, the latch circuit latches the second signal, meanwhile, the drive signal is generated, and the drive signal is transmitted to the drive circuit;

the drive circuit is used for amplifying the power of the drive signal, if the drive circuit receives the drive signal, the drive circuit controls the normally closed contact of the quick action relay to be disconnected, the quick action relay can guarantee the rapidity of cutting off a fault circuit, when the IGBT is broken down, the control module can quickly make a judgment and control the quick action relay to disconnect a branch where the IGBT is located, the upper contact and the lower contact of the relay are prevented from being short-circuited, and the safety of a circuit system can be improved.

The utility model discloses a control module, including power module input, power module, control module, power module, drive circuit, power module, power off back quick action relay, power module, and power module.

The IGBT current judging circuit comprises a current sensor and a voltage comparator, the current sensor is used for detecting current passing through an IGBT and converting the current into voltage, the voltage comparator is used for judging the voltage output by the current sensor, if the current passing through the IGBT is detected to be larger than a preset threshold value, it is indicated that contact point current generated by arc energy is transferred to a branch where the IGBT is located, and at the moment, an output first signal is at a high level.

The logic fault judging circuit comprises a NOT gate and an AND gate, a first signal is A, an IGBT gate control signal is B, the high level of A indicates that contact current generated by arc energy is transferred to a branch where the IGBT is located, the high level of B is a control signal for switching on the IGBT, and a second signal is Y, the judging logic of the logic fault judging circuit is that

Namely, A is high level and B is low level, the output Y is high level, which indicates that the IGBT is broken down, and the mode of judging whether the IGBT is broken down through the logics of A and B has strong anti-interference performance, so that the malfunction of the fast acting relay and the magnetic latching relay can be avoided.

The working principle of the invention is that through the logic fault judgment circuit, when the IGBT grid control signal is at low level and the branch current signal passing through the IGBT is at high level, the IGBT is indicated to be broken down, and when the latch circuit receives a high-level second signal indicating that the IGBT is broken down, the latch circuit latches the second signal and drives the fast acting relay and the magnetic latching relay to break off the corresponding normally closed contact through the drive circuit.

Fig. 2 shows a normal operation timing diagram of the composite relay, and it can be seen that, in normal operation, after the IGBT turn-off signal, i.e., the IGBT gate control signal, changes to the low level, the first signal immediately changes to the low level, and at this time, the driving signal also changes to the low level.

The working timing diagram of the composite relay after breakdown fault is shown in fig. 3, and it can be seen that when breakdown fault occurs, after the IGBT turn-off signal, i.e. the IGBT gate control signal, is changed to low level, the first signal is still high level, and after a short time delay, the first signal is changed to low level, which indicates that the fast acting relay successfully turns off the fault branch.

The voltage waveform diagram of the contact after the composite relay has breakdown fault is shown in fig. 4, the dotted line waveform is the voltage waveform of the movable contact and the upper contact with breaking action, and the solid line waveform is the voltage waveform of the movable contact and the lower contact with closing action.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. The utility model provides a compound relay short-circuit protection circuit, its characterized in that, includes power module and control module, control module includes IGBT current judgement circuit, logic fault judgement circuit, latch circuit, drive circuit and fast action relay, the fast action relay includes the normally closed contact of establishing ties to IGBT place branch road, wherein:

2. The composite relay short-circuit protection circuit as claimed in claim 1, wherein the input terminal of the power supply module is connected to the positive and negative poles of the coil voltage, the control module further comprises a magnetic latching relay, the fast acting relay comprises a normally closed contact connected in series to the branch where the IGBT is located, and the normally closed contact of the magnetic latching relay is controlled to be opened by the driving circuit if the driving circuit receives a driving signal.

3. The composite relay short-circuit protection circuit of claim 1, wherein the IGBT current determination circuit comprises a current sensor and a voltage comparator, the current sensor is configured to detect a current passing through the IGBT and convert the current into a voltage, the voltage comparator is configured to determine a magnitude of the voltage output by the current sensor, and if the current passing through the IGBT is detected to be greater than a predetermined threshold, the output first signal is at a high level.

4. The composite relay short-circuit protection circuit according to claim 1, wherein the logic fault determination circuit comprises a not gate and an and gate, and if the first signal is detected to be at a high level and the IGBT gate control signal is detected to be at a low level, the output second signal is at a high level.