Relay device
By introducing a loss reduction circuit into the relay and reducing the wire-pack current with switching devices, the problem of large wire-pack loss of existing relays is solved, and design simplification, volume reduction and heat dissipation effect are achieved.
Patent Information
- Application Number
- CN202421191233.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-27
- Publication Date
- 2025-05-09
- Estimated Expiration
- 2034-05-27
AI Technical Summary
When existing relays work, the wire pack loss is large, resulting in complex design, large size, and is not conducive to miniaturized design.
By introducing a loss reduction circuit into the relay, the switching device operating in the saturation zone is used to reduce the current flowing through the wire packet after the contacts are attracted, thereby reducing the voltage across the wire packet.
It effectively reduces the loss of wire packs during relay operation, simplifies design, reduces volume, is suitable for miniaturized design needs, and improves heat dissipation effect.
Smart Images
Figure CN222851330U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of circuits, in particular to a relay device. Background Art
[0002] A relay is an electrical control device. When the change in the input quantity (i.e. the excitation quantity) reaches the specified requirement, it causes the controlled quantity to undergo a predetermined step change in the electrical output circuit. It is usually used in automatic control circuits. It is actually an "automatic switch" that uses a small current to control the operation of a large current. It plays the role of automatic adjustment, safety protection, and circuit conversion in the circuit.
[0003] The main structure of the relay is simple and reliable, mainly composed of coils and contacts. When used, it has few peripheral circuits and low power supply requirements, so it is widely used. In order to reduce the loss of the coil, the existing technology usually reduces the coil voltage by connecting multiple power resistors in parallel after the relay is energized, thereby reducing the loss of the coil. This design increases the number and volume of components, has high requirements for layout, and is not conducive to the design requirements of product miniaturization. Summary of the invention
[0004] The utility model provides a relay device to effectively reduce the loss of a coil when the relay is working.
[0005] The utility model provides a relay device, the device comprising: a relay, a starting circuit, a loss reduction circuit, and an auxiliary power supply; the relay comprises a wire package and a contact; one end of the wire package is connected to the starting circuit, and the other end of the wire package is connected to the auxiliary power supply; the loss reduction circuit is connected to one end of the wire package and the starting circuit;
[0006] After the first loop is disconnected, the loss reduction circuit reduces the current flowing through the coil from the first current to the second current by using a switch device operating in a saturation region.
[0007] Optionally, the loss reduction circuit comprises: a first switch tube, a sampling resistor, and a feedback circuit; the first switch tube is respectively connected to one end of the coil, the sampling resistor, and the feedback circuit;
[0008] After the first switch tube is turned on, the current flowing through the coil is reduced from the first current to the second current;
[0009] The feedback circuit controls the source-drain current of the first switch tube to remain stable.
[0010] Optionally, the feedback circuit includes:
[0011] A negative feedback operational amplifier, wherein one input terminal of the negative feedback operational amplifier inputs the sampled voltage on the sampling resistor, the other input terminal inputs the reference voltage, and the output terminal of the negative feedback operational amplifier is connected to the gate of the first switch tube;
[0012] The negative feedback operational amplifier amplifies and outputs the voltage difference between the sampling voltage and the reference voltage, and feeds back the output result to the negative phase input terminal of the operational amplifier.
[0013] Optionally, the feedback circuit further includes: an output resistor connected to the output end of the negative feedback operational amplifier.
[0014] Optionally, the feedback circuit further includes: a driving resistor connected to the gate of the first switch tube and the output resistor.
[0015] Optionally, the first switch tube is a MOS tube.
[0016] Optionally, the starting circuit includes: a second switch tube is turned on when the relay starts to work; when the second switch tube is turned on, the current flowing through the coil is the first current.
[0017] Optionally, the device further includes: a controller, configured to control the on and off of the first switch tube and the second switch tube.
[0018] Optionally, the device further comprises: a slow-start resistor connected in parallel with the relay.
[0019] Optionally, the relay further includes: a freewheeling diode connected in parallel with the coil, and a bus capacitor connected to the contact.
[0020] In the relay device provided by the embodiment of the utility model, when the relay starts to work, a first current flows through the relay coil, thereby triggering the contact of the relay to close. After the contact is closed, the current flowing through the coil is reduced to a second current by using a switch device working in a saturation region. Since the output characteristic of the switch tube is a constant current state when working in the saturation region, the resistance value of the internal resistance of the switch tube is fixed. Therefore, the internal resistance of the switch tube and the parasitic resistance of the coil are connected in series to share the voltage applied to the coil when the relay is started, thereby reducing the current flowing through the coil, that is, reducing the voltage at both ends of the coil, so that it only needs to maintain the voltage of the contact closing to ensure the normal operation of the relay. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 It is a structural schematic diagram of an existing relay contact detection circuit;
[0022] Figure 2 It is a structural schematic diagram of a relay device provided by an embodiment of the utility model;
[0023] Figure 3 It is a specific structural schematic diagram of the relay device provided by the embodiment of the utility model;
[0024] Figure 4 yes Figure 3 A specific structural diagram of the feedback circuit in the embodiment shown;
[0025] Figure 5 It is another specific structural schematic diagram of the relay device provided in the embodiment of the utility model. DETAILED DESCRIPTION
[0026] In order to make the above-mentioned objects, features and beneficial effects of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.
[0027] In order to better reflect the difference between the solution of the utility model and the prior art, the existing solution of reducing the coil loss by connecting multiple resistors in parallel is briefly described below.
[0028] like Figure 1 As shown, it is a structural schematic diagram of a relay device in the prior art that uses multiple resistors in parallel to reduce winding loss.
[0029] In the existing relay device, two groups of switch tubes plus peripheral circuits are used to achieve the loss reduction function. Among them, one group of switch tubes Q1 is directly connected to the relay coil. After Q1 is turned on, the voltage at both ends of the coil is V2, and the contact K1 is energized; the other group of switch tubes Q2, the coil and the parallel-connected power resistors R2, R5, and R6 are connected in series. After the contact K1 is energized, when the V4 voltage is established, the V3 voltage is 0, Q1 is turned off and Q2 is turned on. The parallel power resistors R2, R5 and R6 share the V2 voltage with the parasitic resistance of the coil, so that the voltage at both ends of the coil is reduced, for example, reduced to about half of the V2 voltage, which plays a role in maintaining the contact energization.
[0030] Although the coil voltage is reduced to achieve the purpose of reducing coil losses, the power resistors R2, R5, and R6 are added, and the heat is concentrated on the power resistors. In addition, in order to avoid the problem of overheating of the resistor (such as damage to the resistor or fire) caused by using a single resistor, multiple power resistors need to be connected in parallel. Since the power resistor is large in size, it puts forward higher requirements for the layout of the board, and is not conducive to the application in space-constrained products.
[0031] In response to the above problems, an embodiment of the utility model provides a low-loss relay device, which does not require the use of multiple parallel resistors. Instead, after the relay contacts are closed, a switching device operating in a saturation region is used to reduce the current flowing through the coil, thereby reducing the voltage across the coil so that it only maintains the voltage required for the contacts to be closed, thereby ensuring the normal operation of the relay.
[0032] like Figure 2 , which is a structural schematic diagram of a relay device provided in an embodiment of the utility model.
[0033] The relay device of this embodiment includes: a relay K1, a starting circuit 21, a loss reduction circuit 22, and an auxiliary power supply V2; the relay K1 includes a coil and a contact. One end of the coil is connected to the starting circuit 21, and the other end of the coil is connected to the auxiliary power supply V2; the loss reduction circuit 22 is connected to one end of the coil and the starting circuit 21.
[0034] In addition, similar to the existing relay device, the relay device of this embodiment further includes an input voltage source V1, a freewheeling diode D1 connected in parallel with the coil, and a bus capacitor C1 connected to the input voltage source V1 and the contact K1. Wherein:
[0035] The start-up circuit 21 is configured to control the auxiliary power supply V2 and the coil to form a first loop when the relay K1 starts to work, so as to trigger the contact to close; after the contact is closed, the first loop is disconnected. Specifically, after the relay K1 is connected to the input voltage source V1, the auxiliary power supply V2 acts on the coil through the first loop to generate a first current, thereby triggering the relay contact to close; after the contact is closed, the start-up circuit 21 disconnects the first loop.
[0036] The loss reduction circuit 22 is configured to reduce the first current flowing through the relay coil to a second current by using a switching device operating in a saturation region after the first circuit is disconnected. The second current is smaller than the first current but can enable the voltage at both ends of the coil to maintain the contacts closed, that is, to reduce the voltage at both ends of the coil so that only the voltage at which the contacts are closed is maintained, thereby ensuring the normal operation of the relay.
[0037] In this embodiment, the input voltage source V1 is an external power source, which is used to charge the bus capacitor C1 when powered on to establish a starting voltage. After the voltage across the capacitor C1 is established, the voltage of the auxiliary power source V2 is added to the ends of the coil through the control of the starting circuit 21, so that the contacts of the relay are attracted. At this time, the loss reduction circuit 22 starts to work, and the first current flowing through the relay coil is adjusted to the second current by using the switching device working in the saturation area, so that the voltage across the coil meets the maintenance voltage required to maintain the contact attraction state, and the contacts of the relay K1 can work safely.
[0038] like Figure 3, which is a schematic diagram of a specific structure of a relay device provided in an embodiment of the utility model.
[0039] In this embodiment, the loss reduction circuit includes: a first switch tube Q2, a sampling resistor R5, and a feedback circuit 221, and also includes a driving resistor R4 of the first switch tube Q2. The first switch tube Q2 is connected to one end of the coil, the sampling resistor R5, and the feedback circuit 221 respectively. Wherein:
[0040] The first switch tube Q2 is configured to be turned on after the first loop is disconnected; accordingly, after the first switch tube Q2 is turned on, the current flowing through the coil is reduced from the first current to the second current. Figure 3 As shown, after the first switch tube Q2 is turned on, the first switch tube Q2, the coil, the auxiliary power supply V2, and the sampling resistor R5 form a second loop, and the current flowing through the coil can be reduced to a second current through the second loop.
[0041] The feedback circuit 221 is configured to control the source-drain current of the first switch tube to remain stable. Figure 3 As shown, the feedback circuit 221 can adjust the gate voltage of the first switch tube Q2 according to the sampling voltage on the sampling resistor R5, so as to keep the source-drain current of the first switch tube Q2 stable.
[0042] The working area of the switch tube is divided into a variable resistance area, a saturation area and a cut-off area. In this solution, the first switch tube Q2 works in the saturation area, the source-drain current remains constant, and the output current of the first switch tube Q2 can be controlled by changing the gate voltage of the first switch tube Q2.
[0043] Reference Figure 3 , the startup circuit may include: a second switch tube Q1 and a driving resistor R3.
[0044] In this embodiment, at startup, the input voltage source V1 charges the bus capacitor C1 to establish a startup voltage. After the voltage across the capacitor C1 is established, a drive signal is input to the second switch tube Q1, and the turn-on voltage of the second switch tube Q1 is provided through the drive resistor R3, the second switch tube Q1 is turned on, the auxiliary power supply V2, the coil, and the second switch tube Q1 form a first loop, and the voltage of the auxiliary power supply V2 through the first loop is applied to the two ends of the coil, and the contacts of the relay are attracted.
[0045] Then, stop inputting the driving signal to the second switch tube Q1, and the second switch tube Q1 is turned off. Since the second switch tube Q1 is turned off, the first loop is disconnected. At this time, the first switch tube Q2, the coil, the auxiliary power supply V2, and the sampling resistor R5 form a second loop. Through the second loop, the current flowing through the coil is reduced to the second current. The feedback circuit 221 obtains the sampling voltage on the sampling resistor R5, and adjusts the gate voltage of the first switch tube Q2 according to the sampling voltage, so that the source-drain current of the first switch tube Q2 remains stable. Not only does it reduce the voltage on the coil, meeting the loss reduction requirements, but it can also keep the voltage at both ends of the coil stable, ensuring the stability of the operation of the relay K1.
[0046] It should be noted that the control of the gate voltage of the second switch tube Q1 can be achieved by the controller 211 (such as a DSP controller) inside the relay device, that is, the controller 211 outputs a corresponding level signal to control the conduction or shutdown of the second switch tube Q1; or the drive resistor can be directly connected or disconnected with the internal power supply (not shown) through a switch to control the conduction or shutdown of the second switch tube Q1, which is not limited in this embodiment of the utility model.
[0047] like Figure 4 , which is a specific structural diagram of a non-limiting embodiment of the feedback circuit 221 in the relay device.
[0048] In this example, the feedback circuit 221 includes: a negative feedback operational amplifier U1 and its peripheral circuits, wherein resistors R6 and R7 are proportional resistors of the operational amplifier, connected to the negative phase input terminal of the negative feedback operational amplifier U1, and R8 is an output resistor.
[0049] Combined with Figure 3 and Figure 4 The positive input terminal of the negative feedback operational amplifier U1 inputs the reference voltage Vref, the negative input terminal inputs the sampling voltage through the resistor R6, and the output terminal is connected to the gate input resistor R4 of the first switch tube Q2 through the output resistor R8.
[0050] In this example, the negative feedback operational amplifier U1 amplifies and outputs the voltage difference between the sampled voltage and the reference voltage, and feeds back the output result to the negative phase input terminal of the operational amplifier U1 through the resistor R7.
[0051] It should be noted that the first switch tube Q2 and the second switch tube Q1 can be implemented by some conventional switch devices. For example, considering that MOS tubes have the advantages of low driving power, high efficiency, fast switching speed, and small size, MOS tubes can be preferably used for implementation.
[0052] The relay device provided by the embodiment of the utility model has a first current flowing through the relay coil when the relay starts working, thereby triggering the contact of the relay to close. After the contact is closed, the current flowing through the coil is reduced to the second current by using the switch device working in the saturation region. Since the output characteristic of the switch tube is a constant current state when it works in the saturation region, the resistance value of the internal resistance of the switch tube is fixed. Therefore, the internal resistance of the switch tube and the parasitic resistance of the coil are connected in series to share the voltage applied to the coil when the relay is started, thereby reducing the current flowing through the coil, that is, reducing the voltage at both ends of the coil, so that it only needs to maintain the voltage of the contact closing to ensure the normal operation of the relay. The prior art reduces the coil loss by connecting multiple power resistors in parallel, and the heat is concentrated on the power resistor, and the power resistor is relatively large. Therefore, compared with the prior art, the solution of the utility model can obtain a better heat dissipation effect. For example, a switch tube in the form of a patch can be used to transfer heat through the copper foil on the PCB board; and it is convenient for layout and application in space-constrained products.
[0053] In some application scenarios, such as slow start circuits or scenarios that require switching, at the moment of power-on, if the bus capacitor is directly charged, the instantaneous impact current is large, and multiple impacts will have a direct impact on the life of the bus capacitor. For this reason, in another non-limiting embodiment of the relay device of the utility model, the hidden dangers caused by the large impact current can also be reduced by connecting a resistor in parallel with the relay.
[0054] like Figure 5 , which is another specific structural schematic diagram of the relay device provided in an embodiment of the utility model.
[0055] In this embodiment, R1 is a slow-start resistor connected in parallel with the relay K1. The structure of the starting circuit and the loss reduction circuit can refer to the previous Figure 3 and Figure 4 The working power supply of the negative feedback operational amplifier U1 can be the auxiliary power supply V2 or other internal power supplies, which is not limited in this embodiment.
[0056] Assuming that the pull-in voltage of the relay K1 coil is 12V, when the ambient temperature is 85℃, the voltage to maintain the coil pull-in is 5.4V to 6.6V. Considering the redundant design, the coil maintenance voltage is selected to be 6V, and the coil impedance is 58Ω. According to Ohm's law, the current to maintain the coil pull-in is 0.1A. As long as the current of the switch tube Q2 is controlled to 0.1A, the purpose of reducing the coil loss can be achieved.
[0057] Combine the following Figure 5 Describe the working process of the relay device.
[0058] When powered on, the input voltage source V1 charges the bus capacitor C1 through the snubber resistor R1. The snubber resistor R1 acts as a shunt, which reduces the charging current on the capacitor C1 and reduces the impact of the instantaneous current, thereby reducing the impact on the capacitor C1.
[0059] The internal voltage source V3 is turned on, and the start voltage of the second switch tube Q1 is provided through the driving resistor R3. After the second switch tube Q1 is turned on, the voltage of the auxiliary power supply V2 is applied to both ends of the coil. At this time, the voltage at both ends of the coil is 12V, and the contacts of the relay K1 are attracted. At this time, the slow-start resistor R1 is short-circuited by the contacts of the relay K1, and the slow-start resistor R1 no longer flows with current, completing the charging task of the bus capacitor C1.
[0060] After the contacts of relay K1 are energized, the coil voltage does not need to be maintained at 12V all the time, otherwise the coil loss will be large. As the ambient temperature increases, it will cause heat accumulation in the relay, affecting the service life of the device. At this time, the voltage source V3 is disconnected, that is, when the output voltage is 0, the second switch tube Q1 is turned off, and the current of the coil energized no longer passes through the second switch tube Q1 to form a loop, but flows through another branch through the first switch tube Q2 and the current sampling resistor R5 to form a loop.
[0061] The current passes through the first switch tube Q2, generating a voltage on the sampling resistor R5, namely the sampling voltage, which is sent to the negative phase input terminal of the negative feedback operational amplifier U1 and compared with the reference voltage Vref at the positive phase input terminal to form a negative feedback circuit.
[0062] When the current flowing through the sampling resistor R5 is greater than 0.1A, the output voltage of the negative feedback operational amplifier U1 decreases, the gate voltage of the first switch tube Q2 decreases, the parasitic impedance of the first switch tube Q2 increases, and the current flowing through decreases;
[0063] When the current flowing through the sampling resistor R5 is less than 0.1A, the output voltage of the negative feedback operational amplifier U1 increases, the gate voltage of the first switch tube Q2 increases, the parasitic impedance of the first switch tube Q2 decreases, and the current flowing through increases.
[0064] It can be seen that through the feedback control of the negative feedback operational amplifier U1, the source-drain current Ids on the first switch tube Q2 can always be maintained at no more than 0.1 A. Since the coil impedance is 58Ω, the voltage on the coil is only 5.8V, which meets the maintenance voltage of the coil and has a certain margin, so the contacts of the relay K1 can work safely.
[0065] In a specific application, the reference voltage Vref can be provided by a corresponding controller, such as Figure 2In addition, it should be noted that the specific values of the above-mentioned proportional resistors R6 and R7, the reference voltage Vref, and other resistance and capacitance components can be determined according to the model and parameters of the relay; the models of the switch tube, negative feedback operational amplifier U1 and other components can also be selected according to actual needs, and there is no limitation on this.
[0066] The relay device provided by the embodiment of the utility model can effectively reduce the loss of the coil while ensuring the normal operation of the relay, and can also effectively avoid the impact of the instantaneous charging current on the relay bus capacitor during power-on, thereby increasing the service life of the relay.
[0067] The relay device provided in the embodiment of the utility model can be better applied to slow-start circuits or scenarios requiring switching, such as charging pile power unit products, to ensure the safety of the charging pile and increase its service life.
[0068] It should be understood that the term "and / or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article indicates that the associated objects before and after are in an "or" relationship.
[0069] The "plurality" appearing in the embodiments of the present invention refers to two or more than two.
[0070] The first, second, etc. descriptions appearing in the embodiments of the present invention are only used for illustration and distinction of the description objects. There is no order, nor does it indicate any special limitation on the number of devices in the embodiments of the present invention, and cannot constitute any limitation on the embodiments of the present invention.
[0071] Although the utility model is disclosed as above, the utility model is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the utility model. Therefore, the protection scope of the utility model shall be subject to the scope defined by the claims.
Claims
1. A relay device, characterized in that: The device comprises: a relay, a starting circuit, a loss reduction circuit, and an auxiliary power supply; the relay comprises a coil and a contact; one end of the coil is connected to the starting circuit, and the other end of the coil is connected to the auxiliary power supply; the loss reduction circuit is connected to one end of the coil and the starting circuit; After the first loop is disconnected, the loss reduction circuit reduces the current flowing through the coil from the first current to the second current by using a switch device operating in a saturation region.
2. The relay device according to claim 1, characterized in that The loss reduction circuit includes: a first switch tube, a sampling resistor, and a feedback circuit; the first switch tube is respectively connected to one end of the coil, the sampling resistor, and the feedback circuit; After the first switch tube is turned on, the current flowing through the coil is reduced from the first current to the second current; The feedback circuit controls the source-drain current of the first switch tube to remain stable.
3. The relay device according to claim 2, characterized in that: The feedback circuit comprises: A negative feedback operational amplifier, wherein one input terminal of the negative feedback operational amplifier inputs the sampled voltage on the sampling resistor, the other input terminal inputs the reference voltage, and the output terminal of the negative feedback operational amplifier is connected to the gate of the first switch tube; The negative feedback operational amplifier amplifies and outputs the voltage difference between the sampling voltage and the reference voltage, and feeds back the output result to the negative phase input terminal of the operational amplifier.
4. The relay device according to claim 3, characterized in that: The feedback circuit further includes: an output resistor connected to the output end of the negative feedback operational amplifier.
5. The relay device according to claim 4, characterized in that The feedback circuit further includes: a driving resistor connected to the gate of the first switch tube and the output resistor.
6. The relay device according to claim 5, characterized in that The first switch tube is a MOS tube.
7. The relay device according to claim 2, characterized in that: The startup circuit comprises: The second switch tube is turned on when the relay starts to work; when the second switch tube is turned on, the current flowing through the coil is the first current.
8. The relay device according to claim 7, characterized in that The device also includes: A controller is used to control the on and off of the first switch tube and the second switch tube.
9. The relay device according to any one of claims 1 to 8, characterized in that: The device further comprises: a slow-start resistor connected in parallel with the relay.
10. The relay device according to any one of claims 1 to 8, characterized in that: The relay further includes: a freewheeling diode connected in parallel with the coil, and a bus capacitor connected with the contact.