KR100636545B1 - Switching driving circuit for parallel-connected circuit solid state relay and magnetic relay - Google Patents

Abstract

A switching drive circuit of a solid state relay and a magnetic relay of a parallel connection for opening and closing a power supply to a load is disclosed. This driving circuit connects a magnetic relay and a solid state relay (SSR) in parallel between the load and the power supply to use as a switching element. The microcontroller has separate outputs connected to the magnetic relay and the solid state relay, and when the control signal is applied to supply or cut off power to the load, the microcontroller always responds to the magnetic relay with the solid state relay turned on. Contacting the contactless relay with the first switching signal for turning the contactless relay on or off and the second switching signal for turning the magnetic relay on or off with a predetermined time difference so that the switch is turned on or turned off. It is programmed to provide each to a magnetic relay. This switching drive circuit may be configured for three phases. In this way, by switching the two switching elements in a manner of injecting a magnetic relay in a state where the contactless relay is applied, damage and malfunction of the device can be prevented.

Description

Switching driving circuit for parallel-connected circuit solid state relay and magnetic relay}

1 is a block diagram schematically showing a driving circuit of a contactless relay-magnetic relay of a simultaneous switching method according to the prior art;

2 is an opening and closing operation time chart of the driving circuit of FIG. 1;

3 is a block diagram schematically showing a driving circuit of a sequential open / close contactless relay-magnetic relay according to the present invention;

4 is a time chart of opening and closing operations of the driving circuit of FIG. 3;

5 is a flowchart in which a microprocessor controls opening and closing of a solid state relay and a magnetic relay.

6 shows a specific embodiment of the switching driving circuit according to the present invention.

** Explanation of symbols for main parts of drawings **

40: switching driving circuit

42: microcontroller

44: solid state relay (SSR)

46: magnetic relay

48: load

The present invention relates to a driving of an electronic switching device, and more particularly, a switching circuit for connecting a solid state relay (SSR) and a magnetic relay in parallel to form a switch circuit and controlling the switching of power supply to a load through the control thereof. It relates to the improvement of the driving circuit.

Solid-state relays (SSRs) work just like regular relays, but they are electronic relays that are made of semiconductors for permanent life, noise and high speed operation. The solid state relay (SSR) generally includes a triac serving as a switch and a photocoupler connected to a control terminal of the triac to provide a switching signal. This contactless relay is simply used for on / off functions, so it is mainly used for frequent on / off operation.

It is often employed as a switching circuit for opening and closing the power supply of a large current flowing electronic product. In this case, the contactless relay generates a lot of heat. Excessive heat has problems such as burning triacs, so an effective solution is required. Commercially available contactless relays can be classified according to the heat dissipation method.The heat dissipation type prevents overheating of the triac using a heat sink and the non-heating type which prevents overheating of the triac by connecting general magnetic relays in parallel to the triac. have. However, the heat dissipation type is not suitable for products seeking miniaturization due to the problem that the appearance of the product increases due to the adoption of the heat dissipation plate, and thus the heat dissipation type is mainly employed.

In constructing a non-heating type switching circuit for connecting a contactless relay and a magnetic relay in parallel to control a power supply to a load such as a heater or a motor, a conventional method of simultaneously turning on or off a magnetic relay and a contactless relay at the same time. Was taken. However, when these two devices are turned on or off at the same time, a much larger inrush current flows than the steady state current, causing sparks in the contactless relay, causing a malfunction of the spark noise. The contact point of and triac may burn out, and its performance may be reduced to reduce durability.

Fig. 1 is a block diagram schematically showing a switching driving circuit 10 of a contactless relay-magnetic relay of a simultaneous switching method according to the related art, and Fig. 2 shows an opening and closing operation by the switching driving circuit 10. Show a time chart. Referring to FIG. 1, a solid state relay 14 and a magnetic relay 16 are connected in parallel between a power supply and a load 18, and the solid state relay 14 and the magnetic relay 16 are turned on / off. The off control is performed by the transistor circuit 12. That is, the control of the current flow of the photocoupler (not shown) of the solid state relay 14 and the excitation coil of the magnetic relay 16 is commonly performed by the collector (not shown) current of the transistor circuit 12.

As a result, the on / off control of these two switching elements, the contactless relay 14 and the magnetic relay 16, is always performed simultaneously. As shown in FIG. 2, when the control signal for turning on the relay 14 and the magnetic relay 16 is input from the outside as illustrated in FIG. 2, the transistor circuit 12 immediately includes the first switching signal CS1 and the second switching signal ( CS2) is simultaneously provided to the control stages of the solid state relay 14 and the magnetic relay 16. The same applies to a case where an externally provided control signal is an off signal. In response to the first and second switching signals CS1 and CS2 provided from the transistor circuit 12, the contactless relay 14 and the magnetic relay 16 are turned on or off at the same time.

As described above, since the on / off control of the solid state relay 14 and the magnetic relay 16 is made by using an output signal of an analog circuit such as the transistor circuit 12, the magnetic contactless relay 14 and the magnetic relay 16 are magnetic. It is inevitable that the relay 16 is turned on or off at the same time. However, when these two elements 14 and 16 are turned on or off at the same time, a larger amount of inrush current flows in the circuit. Therefore, both relays generate spark noise and sparks. As a result, there are problems such as burnout of the relay contact, deterioration of the performance of the triac, and reduced durability. It can also cause malfunctions due to noise in peripheral circuits. There is a demand for improvement to solve this problem.

In order to solve the above problems, the present invention in the switching drive circuit in which the solid-state relay and the magnetic relay in parallel to open and close the two switching elements with a predetermined time difference, the spark noise and sparks during the on / off operation It is an object of the present invention to provide a switching drive circuit which can prevent the occurrence of the above-mentioned and improve the durability of these switching elements and their peripheral circuits.

According to the present invention for achieving the above object, a magnetic relay is connected between the load and the power source to open and close the current supply path for the load depending on the magnetization of the excitation coil; A contactless relay (SSR) connected to the magnetic relay in parallel to open and close a current supply path to the load according to a switching signal applied to a control terminal; And a separate output terminal is connected to the magnetic relay and the contactless relay, and when a control signal for supplying power to the load is applied, a first switching signal for turning on the contactless relay and And a microcontroller programmed to sequentially provide a second switching signal for turning on the magnetic relay to the contactless relay and the control terminal of the magnetic relay sequentially with a first predetermined time difference. A relay-magnetic relay switching drive circuit is provided. In addition, the microcontroller may be configured to output a second switching signal for turning off the magnetic relay and a first switching signal for turning off the contactless relay in response to a control signal for shutting off power to the load. The second predetermined time difference is sequentially programmed to provide to the control terminals of the magnetic relay and the contactless relay, respectively. In order to prevent spark noise in the magnetic relay, the magnetic relay is turned on or off with the contactless relay always turned on.

In the switching driving circuit, the first and second predetermined time differences are preferably 100 milliseconds or more and 200 milliseconds or less. Furthermore, when the control signal for supplying power to the load is applied, the output of the first switching signal is made after a predetermined time of 100 milliseconds or more and 200 milliseconds from the time when the control signal is applied. When the control signal for cutting the power to the load is applied, the second switching signal is output immediately after the control signal is applied.

 In addition, it is preferable to further include a spark killer circuit connected to the relay contact of the magnetic relay in parallel to absorb the spark noise and to prevent propagation to the load.

Furthermore, the switching driving circuit can be configured for three phases. To this end, three contactless relays and three magnetic relays are provided for each of three phases, and three photocouplers of three contactless relays are connected in series with each other and one side thereof is connected in series with a transistor Q1. Three excitation windings of the three magnetic relays are connected in parallel with each other, and one side of each of them is commonly connected to the transistor Q2.

Since the solid-state relay and the magnetic relay are sequentially opened and closed instead of simultaneously opened and closed, excessive inrush current flows to cause damage to the device does not occur, and as a result, spark noise that causes malfunction of the switching drive circuit and degradation of durability. Or sparks do not occur.

Hereinafter, with reference to the drawings of the present invention will be described in more detail.

3 is a block diagram schematically showing a switching driving circuit 40 of a sequential open / close contactless relay-magnetic relay according to the present invention, and FIG. 4 is a time chart of opening and closing operation of the switching driving circuit 40. . Compared with the conventional switching driving circuit 10 of FIG. 1, there is a big difference in that a microcontroller 42 that generates a switching signal through the execution of software is employed in place of the transistor circuit 12.

Specifically, according to the switching drive circuit 40 of the present invention, the contactless relay 44 and the magnetic relay 46 is connected between the load 48 and the power source, where the contactless relay 44 and the magnetic The relay 46 takes a parallel connection. In addition, a microcontroller 42 is connected to each control terminal of the solid state relay 44 and the magnetic relay 46, and in particular, the microcontroller 42 connected to the solid state relay 44 and the magnetic relay 46. The output terminals of are different output terminals. The input end of the microcontroller 42 is connected to an external means (not shown) that provides a control signal for turning on / off the solid state relay 44 and the magnetic relay 46.

The microcontroller 42 has a program for generating switching signals MCS1 and MCS2 for controlling the on / off of the solid state relay 44 and the magnetic relay 46 in response to a control signal provided by an external means. It is built in. By the execution of the built-in program, the contactless relay 44 and the magnetic relay 46 are controlled to be sequentially turned on or off with a predetermined time difference, not simultaneously.

5 is a flowchart illustrating the logic of a program embedded in the microcontroller 42. Referring to this, the microcontroller 42 periodically checks whether a control signal is input from an external means. When the level of the control signal is checked in step S10 and determined to be a high level signal, that is, an "on" signal, the microcontroller 42 may select the first switching signal MCS1 and the second switching signal MCS2 of the "high level". Outputs to the contactless relay 44 and the magnetic relay 46, respectively. At this time, as shown in FIG. 4, the microcontroller 42 first contacts the high level first switching signal MCS1 after the predetermined time T1 has elapsed from the time when the high level control signal is input. After the predetermined time T2 passes again, the second switching signal MCS2 of the high level is provided to the control terminal of the magnetic relay 46 (step S12). . In this way, the magnetic relay 46 is fed in the state where the contactless relay 44 is fed. It is preferable that predetermined time T1 and T2 are decided in 100-200 ms here, for example.

The same applies to the case where the control signal applied to the microcontroller 42 is an "off" signal. That is, when it is determined in step S14 that the control signal is a low level signal, that is, an "off" signal, the microcontroller 42 does not apply the first switching signal MCS1 and the second switching signal MCS2 of the "low level", respectively. Output to contact relay 44 and magnetic relay 46. Even when the two relays 44 and 46 are turned off, it is preferable to release the magnetic relay 46 in the state where the contactless relay 44 is turned on. To this end, as shown in FIG. 4, the microcontroller 42 provides the low level second switching signal MCS2 to the control terminal of the magnetic relay 46 as soon as the control signal is converted to the low level. After the predetermined time T3 has elapsed, the low level first switching signal MCS1 is provided to the control terminal of the contactless relay 44 (step S16). Here, it is preferable that predetermined time T3 is also determined, for example in 100-200 ms.

The solid state relay 44 and the magnetic relay 46 are turned on or off according to the level of the signal as soon as the first and second switching signals MCS1 and MCS2 are applied to the control terminal. The supply of power to () is made or cut off. The microcontroller 42 repeats the above process.

When the switching signal is generated in the same manner as in FIG. 4, the magnetic relay 46 is turned on or turned off while the load 48 is always in contact with the solid state relay 44. The reason for this is that when the magnetic relay 46 is turned on or off, the contactless relay 44 always has the load 48 in the closed state, so that spark noise is applied to the magnetic relay 46. This is to prevent the occurrence.

Since the switching time is controlled by software, the switching time difference between the two switching elements 44 and 46 can be appropriately set according to the characteristics of the element. In the actual configuration, considering the device characteristics of the contactless relay 44 and the magnetic relay 46 employed, it is possible to calculate the minimum time difference that these two devices can be opened and closed without being damaged. What is necessary is just to reflect the appropriate time difference more than the opening / closing time difference which was made in the program built into the microcontroller 42. It is preferable to set the driving time difference of the two relays in the range of at least 100 milliseconds or more and 200 milliseconds or less. If the switching time difference between the two relays 44 and 46 is set too short, less than 100 milliseconds, it is not good due to a malfunction. The drive time difference values of the two relays 44 and 46 are light weights of the inventors as a result of the effort obtained through numerous repeated experiments and analyzes.

6 shows a specific embodiment of the switching driving circuit according to the present invention. The photocoupler of the solid state relay 44 is connected to the transistor Q1 and the exciting coil RL-A of the magnetic relay 46 is also connected to the transistor Q2. The microcontroller 42 outputs the first switching signal MCS1 through the output port 7 after the time T1 has elapsed since the on or off control signal is applied to the input port, and then the time T2 has passed again. Next, the second switching signal MCS2 is output through the output port 8. The first and second switching signals MCS1 and MCS2 are applied with a time difference T2 at the bases of the two transistors Q1 and Q2. This causes transistors Q1 and Q2 to turn on or off with a time difference of T2, respectively, so that the triac and relay contact RL-B also turn on or turn while having approximately the same time difference T2. It turns off.

When the control signal is converted to a low level signal, the operation is similar to that described above. In this regard, a description thereof will be omitted to avoid duplication.

In order to further improve the stability against spark noise, the spark killer circuit (TNR1, C, R) connected in parallel to the relay contact (RL-B) of the magnetic relay 46 to absorb the spark noise and block it from propagating to the load. ) May be added.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art various modifications and changes of the present invention without departing from the spirit and scope of the present invention described in the claims below You can. For example, as long as it is a device capable of generating two switching signals MCS1 and MCS2 sequentially by embedding the above program, it is not necessarily the microcontroller 42. Furthermore, the switching driving circuit of the present invention can be applied to a three-phase circuit. That is, a solid state relay and a magnetic relay are separately provided for each phase, and three three-phase photocouplers are connected in series, one side thereof is connected to the transistor Q1, and three three-phase excitation windings are connected in parallel. Each side may be connected to the transistor Q2 in common. Accordingly, all changes that come within the meaning or range of equivalency of the claims are to be embraced within their scope.

According to the present invention as described above, by sequentially opening and closing the two switching elements 44, 46 with a time difference, the flow of excessive current caused by opening and closing the two elements at the same time does not occur in the switching drive circuit 40 of the present invention. As a result, spark noise and sparks that do not cause the durability of the switching elements 44 and 46 do not occur, so that the malfunction of the switching driving circuit does not occur and the life of the switching elements 44 and 46 can be extended.

Claims (6)

A magnetic relay connected between a load and a power source to open and close a current supply path to the load depending on whether the excitation coil is magnetized; A contactless relay (SSR) connected to the magnetic relay in parallel to open and close a current supply path to the load according to a switching signal applied to a control terminal; And Separate output terminals are respectively connected to the magnetic relay and the contactless relay, and in response to a control signal for supplying power to the load, a switching signal for turning on the contactless relay and the magnetic relay in response thereto. A switching signal for turning on the signal is sequentially provided to the control terminals of the contactless relay and the magnetic relay at a first predetermined time difference, and in response to the control signal for disconnecting power from the load, A microprogrammed to sequentially provide the switching signal for turning off the magnetic relay and the switching signal for turning off the contactless relay to the control terminals of the magnetic relay and the contactless relay sequentially with a time difference of a second firing. With a controller, When the control signal for supplying power to the load is applied, the output of the switching signal for turning on the solid state relay is a predetermined time of 100 milliseconds or more and 200 milliseconds from the time when the control signal is applied. Next, when the control signal for shutting off the power to the load is applied, the output of the switching signal for turning off the magnetic relay is made immediately after the control signal is applied contactless relay-magnetic Relay switching drive circuit. The method of claim 1, wherein the time difference T2 for sequentially turning on the contactless relay and the magnetic relay and the time difference T3 for turning off sequentially are respectively determined within a range of 100 milliseconds to 200 milliseconds. Solid-state relay-magnetic relay switching drive circuit characterized in. delete delete The contactless relay-magnetic relay switching drive circuit according to claim 1, further comprising a spark killer circuit connected in parallel to a relay contact of the magnetic relay to absorb spark noise and block propagation to a load. in. The contactless relay and the magnetic relay are provided in three phases, respectively, for three phases. Three photocouplers of the three contactless relays are connected in series with one side thereof and are connected in series with the transistor Q1. And three excitation windings of the three magnetic relays are connected in parallel with each other, and one side of the three magnetic relays is connected in common to the transistor Q2.

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