CN220492970U - Direct current solid state relay - Google Patents
Direct current solid state relay Download PDFInfo
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- CN220492970U CN220492970U CN202321882369.0U CN202321882369U CN220492970U CN 220492970 U CN220492970 U CN 220492970U CN 202321882369 U CN202321882369 U CN 202321882369U CN 220492970 U CN220492970 U CN 220492970U
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- 239000007787 solid Substances 0.000 title claims abstract description 43
- 238000012544 monitoring process Methods 0.000 claims abstract description 26
- 238000002955 isolation Methods 0.000 claims description 38
- 230000002159 abnormal effect Effects 0.000 abstract description 8
- 230000006378 damage Effects 0.000 abstract description 4
- 230000003685 thermal hair damage Effects 0.000 abstract description 3
- 238000000034 method Methods 0.000 description 5
- 238000001514 detection method Methods 0.000 description 4
- 230000017525 heat dissipation Effects 0.000 description 4
- 238000005070 sampling Methods 0.000 description 4
- 239000004065 semiconductor Substances 0.000 description 4
- 239000003990 capacitor Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 230000005856 abnormality Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
Abstract
The utility model discloses a direct current solid state relay which comprises an isolated power supply circuit, a control input circuit, a fault output circuit, a logic control circuit, an overcurrent short-circuit monitoring circuit, a power driving circuit and a power output circuit. The logic control circuit realizes the basic on-off function of the solid state relay by switching on and off the output power device MSOFET or IGBT according to the input control signal. When load abnormal short circuit occurs, load current can rapidly rise, meanwhile, output voltage drop of an output power device MOSFET or IGBT can rapidly rise synchronously, through monitoring the abnormal rise of the output voltage drop, a logic control circuit rapidly closes output to cut off the load current and self-locks and outputs fault signals, so that damage of a solid state relay caused by continuous load short circuit current is avoided, meanwhile, over-temperature protection also avoids thermal damage of the solid state relay, and application reliability of the solid state relay is effectively improved.
Description
Technical Field
The utility model belongs to the technical field of relays, and particularly relates to a direct-current solid-state relay.
Background
At present, direct current output solid state relays in the market generally adopt optocoupler isolation for input and output, the isolation voltage is more than 2500Vac, output power devices mainly comprise triodes, MOSFETs and IGBTs, wherein the low cost of the triodes and the low power consumption of the MOSFETs take major advantages in low current and low voltage occasions, and the IGBTs have irreplaceable advantages in high voltage and high current application occasions. However, when the IGBT is turned on, a high voltage drop occurs, and when the current is high, the heat productivity is increased synchronously, so heat dissipation is a necessary measure for the application of the solid state relay, poor heat dissipation conditions can cause thermal damage of the solid state relay, and when serious, fire disasters can also occur. Also, the large current in the load short circuit can cause permanent damage to the power devices at the output of the solid state relay.
For overcurrent and short-circuit protection of a direct-current solid-state relay, patent CN218826845U proposes to connect a sampling resistor in series at an output end for detection, and patent CN109672433a proposes to detect current by using a current sensor, which can face some problems when the relay is produced in a high-current occasion.
Patent CN218826845U proposes that the output end is connected in series with a sampling resistor for overcurrent and short circuit detection, the sampling resistor has larger power consumption and heating in a large current occasion, the heating of the superimposed output power device brings higher requirements to the heat dissipation of the solid-state relay, and meanwhile, the volume of the sampling resistor can greatly increase the volume and the cost of the whole solid-state relay.
The patent CN109672433a proposes to detect the current by using a current sensor, which is a relatively common method for detecting the current, and the current sensor is to be placed inside the solid state relay, which also faces the problem of large volume, and in addition, the current increases rapidly in the case of short circuit, and the response processing time of the current sensor is also examined.
Disclosure of Invention
The utility model aims to provide a direct-current solid-state relay, which is internally provided with over-temperature and short-circuit protection, so that the reliability and the safety of the application of the solid-state relay are effectively improved.
In order to solve the problems, the technical scheme of the utility model is as follows:
a direct current solid state relay comprising: the device comprises an isolation power supply circuit, a control input circuit, a fault output circuit, a logic control circuit, an overcurrent short-circuit monitoring circuit, a power driving circuit and a power output circuit;
the output end of the isolation power supply circuit is electrically connected with the power supply end of the logic control circuit;
the control input circuit comprises a current limiting resistor R1 and an isolation optocoupler P1, wherein one end of the R1 is connected with the light emitting device end of the P1 in series; the other end of R1 is an external voltage input end, and the photosensitive device end of P1 is electrically connected with the first signal end of the logic control circuit;
the fault output circuit comprises an isolation optocoupler P2, wherein a light emitting device end of the P2 is connected with a second signal end of the logic control circuit, and a photosensitive device end of the P2 is a fault signal output end;
the overcurrent short-circuit monitoring circuit comprises a voltage comparator IC1, a high-voltage isolation diode D1, divider resistors R2 and R3, wherein the output end of the IC1 is connected with a third signal end of the logic control circuit, the negative input end of the IC1 is connected with a reference voltage end of the logic control circuit, the positive input end of the IC1 is connected with the positive electrode of the D1, and the negative electrode of the D1 is connected with the positive output end of the relay; one end of R2 is connected with a voltage input end, the other end of R2 is connected with one end of R3 and is electrically connected with the positive electrode of D1, and the other end of R3 is grounded;
the power driving circuit comprises a push-pull output circuit composed of resistors R4, R5 and R6 and triodes Q1 and Q2, one end of R4 is connected with a fourth signal end of the logic control circuit, and one end of R6 is connected with the power output circuit;
the power output circuit is a power device, and the power device is connected between a positive output end and a negative output end of the relay.
According to an embodiment of the present utility model, the dc solid state relay further includes a temperature monitoring circuit, the temperature monitoring circuit is a temperature sensor, and the temperature sensor is tightly attached to the housing of the power device; and the signal output end of the temperature sensor is connected with the fifth signal end of the logic control circuit.
According to an embodiment of the utility model, the isolation voltage of the isolation power supply circuit is greater than 2500Vac.
According to an embodiment of the present utility model, the optocoupler signal isolation voltage of the input control circuit is greater than 2500Vac.
According to an embodiment of the present utility model, the isolation voltage of the fault output circuit is greater than 2500Vac.
According to an embodiment of the present utility model, the overcurrent short-circuit monitoring circuit includes a plurality of high-voltage isolation diodes connected in series.
According to an embodiment of the utility model, the power device is a MOSFET or an IGBT.
According to an embodiment of the utility model, the power device is a component formed by connecting a plurality of MOSFETs or a plurality of IGBTs in parallel.
By adopting the technical scheme, the utility model has the following advantages and positive effects compared with the prior art:
1) The direct current solid state relay in one embodiment of the utility model comprises an isolated power supply circuit, a control input circuit, a fault output circuit, a logic control circuit, an overcurrent short circuit monitoring circuit, a power driving circuit and a power output circuit. When load abnormal short circuit occurs, load current can rapidly rise, meanwhile, output voltage drop of an output power device MOSFET or IGBT can simultaneously and rapidly rise, an overcurrent short circuit monitoring circuit monitors the abnormal rise of the output voltage drop, a logic control circuit rapidly closes output to cut off the load current and outputs a fault signal, so that damage of a solid state relay caused by continuous load short circuit current is avoided, meanwhile, over-temperature protection also avoids thermal damage of the solid state relay, and application reliability of the solid state relay is effectively improved.
2) The negative electrode of the high-voltage isolation diode D1 is connected with the positive output end of the relay so as to prevent the load from being damaged by high voltage and the overcurrent short-circuit monitoring circuit.
Drawings
Fig. 1 is a schematic diagram of a dc solid state relay in an embodiment of the utility model.
Reference numerals illustrate:
1: a relay; 2: isolating the power supply circuit; 3: a control input circuit; 4: a fault output circuit; 5: a logic control circuit; 6: an overcurrent short-circuit monitoring circuit; 7: a power driving circuit; 8: a power output circuit; 9: and a temperature monitoring circuit.
Detailed Description
The utility model provides a direct current solid state relay which is further described in detail below with reference to the accompanying drawings and specific embodiments. Advantages and features of the utility model will become more apparent from the following description and from the claims.
The present embodiment provides a dc solid state relay, please refer to fig. 1, the relay 1 includes an isolated power circuit 2, a control input circuit 3, a fault output circuit 4, a logic control circuit 5, an overcurrent short-circuit monitoring circuit 6, a power driving circuit 7, a power output circuit 8, and a temperature monitoring circuit 9. The output end of the isolation power supply circuit 2 is electrically connected with the power supply end of the logic control circuit 5. The control input circuit 3 comprises a current limiting resistor R1 and an isolation optocoupler P1, wherein one end of the R1 is connected with the light emitting device end of the P1 in series; the other end of R1 is an external voltage input end, and the photosensitive device end of P1 is electrically connected with the first signal end of the logic control circuit 5. The fault output circuit 4 comprises an isolation optocoupler P2, the light emitting device end of the isolation optocoupler P2 is connected with the second signal end of the logic control circuit 5, and the photosensitive device end of the isolation optocoupler P2 is a fault signal output end. The overcurrent short-circuit monitoring circuit 6 comprises a voltage comparator IC1, a high-voltage isolation diode D1, voltage dividing resistors R2 and R3, wherein the output end of the IC1 is connected with a third signal end of the logic control circuit 5, the negative input end of the IC1 is connected with a reference voltage end of the logic control circuit 5, the positive input end of the IC1 is connected with the positive electrode of the D1, and the negative electrode of the D1 is connected with the positive output end of the relay; one end of R2 is connected with a voltage input end, the other end of R2 is connected with one end of R3 and is electrically connected with the positive electrode of D1, and the other end of R3 is grounded. The power driving circuit 7 comprises a push-pull output circuit composed of resistors R4, R5 and R6 and triodes Q1 and Q2, one end of the R4 is connected with a fourth signal end of the logic control circuit 5, and one end of the R6 is connected with the power output circuit 8. The power output circuit 8 is a power device connected between the positive output terminal and the negative output terminal of the relay 1. The load is connected to the positive output of the relay 1.
The principle of each circuit is described in detail below:
the isolated power supply circuit 2 provides a direct current power supply for the solid state relay system, the input of the isolated power supply circuit can be direct current or alternating current, the output of the isolated power supply circuit is direct current, and the isolated power supply circuit provides working power supply for the logic control circuit 5, the overcurrent short circuit monitoring circuit 6 and the power driving circuit 7. The isolated power supply circuit 2 is typically a transformer isolated power supply with an isolated voltage above 2500Vac.
The input control circuit 3 mainly comprises a current limiting resistor R1 and an isolation optocoupler P1, when a control input voltage is externally applied, the current of the current limiting loop of R1 causes the light emitting diode in the optocoupler P1 to emit light, and triggers the output triode of the optocoupler to be connected, so that the logic control circuit 5 recognizes an input connection signal. On the contrary, when the control input voltage is externally removed, the optocoupler P1 is turned off and the logic control circuit 5 recognizes the input off signal. The optocoupler signal isolation voltage of the input control circuit 3 is above 2500Vac.
The fault output circuit 4 provides a fault output signal for the solid state relay when the solid state relay works abnormally, the optocoupler output is in an off state when the solid state relay internal logic control circuit 5 detects that the load current is in an overcurrent short circuit or the temperature is over-temperature, the optocoupler P2 in the fault output circuit 4 is conducted, and the fault output is in an on state. The optocoupler isolation voltage is greater than 2500Vac.
The logic control circuit 5 is connected with the input control circuit 3, the fault output circuit 4, the overcurrent short-circuit monitoring circuit 6, the power driving circuit 7 and the temperature monitoring circuit 9, and realizes the identification of input on-off signals, the output of fault signals, the identification of overcurrent short-circuits, the provision of reference voltages, the on-off of power output and the identification and processing of temperature detection signals.
The overcurrent short-circuit monitoring circuit 6 includes a voltage comparator IC1, a high-voltage isolation diode D1, and voltage dividing resistors R2, R3. When the load current is normal, the voltage drop of the output power device Q3 is usually between 1V and 3V, the voltage of the positive input terminal of the IC1 is pulled to be less than 4V through the isolation diode D1, and is lower than the voltage value set by v_ref when the overcurrent is short-circuited, so that the IC1+ voltage is smaller than the IC 1-voltage, and the voltage comparator IC1 outputs a current normal signal to the logic control circuit 5. When the load current is abnormally increased due to the short circuit of the load, the voltage drop of the output power device Q3 is rapidly increased, the positive input terminal voltage of the IC1 is rapidly pulled to be above the set value of V_REF through the isolation diode D1 and the pull-up resistor R2, the voltage of the IC1+ is enabled to be larger than the IC 1-voltage, and the voltage comparator IC1 outputs a current abnormality signal to the logic control circuit 5. The high voltage isolation diode D1 may be arranged as a plurality of diodes in series according to the isolation voltage requirement.
The power driving circuit 7 mainly comprises a push-pull output circuit composed of resistors R4, R5 and R6 and triodes Q1 and Q2. When the logic control circuit 5 gives a high turn-on level, the triode Q1 is turned on, the triode Q2 is turned off, and the VDD voltage rapidly charges the power IGBT gate capacitor through the gate resistor R6, so that the IGBT output is turned on. When the logic control circuit 5 gives off a low level, the triode Q1 is turned off, the triode Q2 is turned on, the grid electrode resistor R6 rapidly discharges the grid electrode capacitor of the power IGBT, and the IGBT output is turned off.
The power output circuit 8 is a semiconductor power device IGBT with direct current output, and may be a parallel combination of a plurality of MOSFETs or IGBTs according to different voltage and current specifications.
The temperature monitoring circuit 9 is a temperature detection NTC, and is internally and closely attached to the casing of the output power device Q3.
The working process of the direct current solid state relay is described as follows:
the normal on and off process of the solid state relay is as follows: the isolation power supply circuit 2 is powered on, and when the control input circuit 3 gives a switch-on signal, the logic control circuit 5 gives a switch-on signal to the power drive circuit 7, so that the output power semiconductor device IGBT is output to be conducted, and the solid state relay output ends OUT+ and OUT-are switched on. On the contrary, when the control input circuit 3 gives off signals, the logic control circuit 5 gives off signals to the power driving circuit 7, so that the output of the output power semiconductor device IGBT is cut off, and the output ends OUT+ and OUT-of the solid state relay are cut off.
The overcurrent short-circuit protection process of the solid-state relay comprises the following steps: when the output of the solid-state relay is in a connection state, abnormal short-circuit current appears in the load, the voltage drop of the power device Q3 at the output end rises sharply at the moment, the overcurrent short-circuit monitoring circuit 6 gives out current abnormal signals rapidly, the logic control circuit 5 sends out a turn-off signal after receiving the current abnormal signals, the power device Q3 at the output end is turned off through the power driving circuit 7 and is locked by itself, and the self-locking can be released only by removing the turn-on signal given by the control input circuit 3. The output voltage drop is detected rapidly, the output is turned off rapidly due to the abnormal overcurrent and short circuit, and therefore the output power device is effectively protected from being damaged by continuous overcurrent or short circuit current.
The solid-state relay over-temperature protection process comprises the following steps: when the solid state relay output is in an on state, when the logic control circuit 5 detects that the shell temperature of the power device Q3 of the temperature sensor Rts exceeds the set safety temperature, the logic control circuit 5 sends an off signal, the power device Q3 at the output end is turned off through the power driving circuit 7, and meanwhile, the solid state relay is self-locked, and the self-locking can be released only by removing the on signal given by the control input circuit 3. Thereby effectively protecting the output semiconductor power device Q3 from being damaged by the continuous over-temperature.
By the above description, the direct current solid state relay provided by the utility model realizes rapid overcurrent short-circuit protection by adopting a mode of detecting the voltage drop of the MOSFET or IGBT of the output power device, and meanwhile, the built-in overheat protection is realized, so that the overheat damage of the solid state relay caused by poor heat dissipation is avoided. Thereby effectively improving the application reliability and safety of the direct current solid state relay.
In this embodiment, a single IGBT is used as the power output device for detailed description, but other voltage-driven power devices (such as MOSFETs) and multiple parallel dc solid state relays are all within the scope of the present utility model.
In this embodiment, a single voltage isolation diode D1 is used as the high voltage isolation circuit, but a connection mode of using a plurality of diodes to serially boost isolated voltages is within the protection scope of the present utility model.
The embodiments of the present utility model have been described in detail with reference to the drawings, but the present utility model is not limited to the above embodiments. Even if various changes are made to the present utility model, it is within the scope of the appended claims and their equivalents to fall within the scope of the utility model.
Claims (8)
1. A dc solid state relay comprising: the device comprises an isolation power supply circuit, a control input circuit, a fault output circuit, a logic control circuit, an overcurrent short-circuit monitoring circuit, a power driving circuit and a power output circuit;
the output end of the isolation power supply circuit is electrically connected with the power supply end of the logic control circuit;
the control input circuit comprises a current limiting resistor R1 and an isolation optocoupler P1, wherein one end of the R1 is connected with the light emitting device end of the P1 in series; the other end of R1 is an external voltage input end, and the photosensitive device end of P1 is electrically connected with the first signal end of the logic control circuit;
the fault output circuit comprises an isolation optocoupler P2, wherein a light emitting device end of the P2 is connected with a second signal end of the logic control circuit, and a photosensitive device end of the P2 is a fault signal output end;
the overcurrent short-circuit monitoring circuit comprises a voltage comparator IC1, a high-voltage isolation diode D1, divider resistors R2 and R3, wherein the output end of the IC1 is connected with a third signal end of the logic control circuit, the negative input end of the IC1 is connected with a reference voltage end of the logic control circuit, the positive input end of the IC1 is connected with the positive electrode of the D1, and the negative electrode of the D1 is connected with the positive output end of the relay; one end of R2 is connected with a voltage input end, the other end of R2 is connected with one end of R3 and is electrically connected with the positive electrode of D1, and the other end of R3 is grounded;
the power driving circuit comprises a push-pull output circuit composed of resistors R4, R5 and R6 and triodes Q1 and Q2, one end of R4 is connected with a fourth signal end of the logic control circuit, and one end of R6 is connected with the power output circuit;
the power output circuit is a power device, and the power device is connected between a positive output end and a negative output end of the relay.
2. The direct current solid state relay of claim 1, further comprising a temperature monitoring circuit, the temperature monitoring circuit being a temperature sensor, the temperature sensor being in close proximity to a housing of the power device; and the signal output end of the temperature sensor is connected with the fifth signal end of the logic control circuit.
3. The dc solid state relay of claim 1, wherein the isolated power circuit has an isolated voltage greater than 2500Vac.
4. The dc solid state relay of claim 1, wherein the optocoupler signal isolation voltage of the control input circuit is greater than 2500Vac.
5. The dc solid state relay of claim 1, wherein the isolation voltage of the fault output circuit is greater than 2500Vac.
6. The dc solid state relay of claim 1, wherein the over-current short circuit monitoring circuit comprises a plurality of high voltage isolation diodes connected in series.
7. A dc solid state relay according to any one of claims 1 to 6, wherein the power device is a MOSFET or an IGBT.
8. The direct current solid state relay of claim 7, wherein the power device is a component of a plurality of MOSFETs or a plurality of IGBTs in parallel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321882369.0U CN220492970U (en) | 2023-07-18 | 2023-07-18 | Direct current solid state relay |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321882369.0U CN220492970U (en) | 2023-07-18 | 2023-07-18 | Direct current solid state relay |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN220492970U true CN220492970U (en) | 2024-02-13 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202321882369.0U Active CN220492970U (en) | 2023-07-18 | 2023-07-18 | Direct current solid state relay |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN220492970U (en) |
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2023
- 2023-07-18 CN CN202321882369.0U patent/CN220492970U/en active Active
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