Control circuit and method of relay

Abstract

The invention discloses a control circuit and method of a relay, and relates to the technical field of electronic control. The specific state switching module is configured to receive and analyze the level state of the control signal and output a corresponding internal control instruction according to the level state; the self-termination pulse generation module is triggered by the state switching module, and is configured to only generate a driving pulse which has preset duration and is self-terminated on a hardware level during each triggering through the transient characteristic of capacitor charging, so that a relay coil is prevented from being burnt out due to continuous effectiveness of a control signal; the power amplification module is electrically connected to the self-termination pulse generation module and is used for amplifying the self-termination driving pulse into a power pulse sufficient to drive a magnetic latching relay coil; and the polarity commutation module is controlled by the internal control instruction of the state switching module, and applies the power pulse to a magnetic latching relay coil with forward or reverse polarity. The invention aims to provide a novel control circuit which can be powered by a single power supply and occupies few MCU resources.

Description

Technical Field

[0001] The present invention relates to the field of electronic control technology, and in particular to a control circuit and method for a relay. Background Art

[0002] Magnetic latching relays, particularly dual-coil or single-coil bidirectional pulse-controlled ones, are widely used in various applications requiring state memory and energy conservation due to their unique self-holding characteristics, such as smart homes, power automation, industrial control systems, and remote device management. Unlike traditional relays, which require continuous power to maintain their state, magnetic latching relays only require a brief pulse of current at the moment of state switching. After the switch is complete, even if all power is removed, the armature remains reliably in its current position, either engaged or released, thanks to the magnetic force of the permanent magnet. This "pulse-driven, zero-power hold" feature offers significant advantages in energy conservation, consumption reduction, and temperature rise mitigation.

[0003] In order to drive the bidirectional pulse magnetic latching relay to achieve reliable state reversal, the following two mainstream control schemes are generally used in the existing technology: The first is a drive solution that uses a positive and negative bipolar power supply. In this solution, the control circuit typically requires a symmetrical positive and negative power supply, such as +12V and -12V or +24V and -24V. When the relay is to be closed, a control unit, such as a microcontroller (MCU), drives the power switch to conduct, applying a positive voltage pulse to both ends of the relay coil. When the relay is to be released, a negative voltage pulse of opposite polarity is applied. The advantage of this solution is its relatively simple and intuitive circuit structure. However, it also has significant drawbacks. In most electronic systems that only provide a single DC power supply, such as +5V or +12V, a negative DC-DC converter chip and its supporting components, such as inductors and capacitors, are required to generate a negative power supply. This not only significantly increases the bill of materials (BOM) cost, but more importantly, according to industry statistics, this negative voltage power supply circuit often consumes up to 40% or more of the printed circuit board (PCB) area. This runs counter to the trend of miniaturization and high integration in modern electronic products, making it particularly unacceptable in space-constrained applications.

[0004] The second approach, an H-bridge drive solution, aims to overcome the dual power supply issue. This solution uses a single positive power supply and controls the direction of current flowing through the relay coil via an H-bridge circuit consisting of four power switches. By controlling the conduction of the switches on the diagonal lines of the H-bridge, current can flow through the coil in either the forward or reverse direction, thereby controlling the engagement and release of the relay. This solution cleverly avoids reliance on a negative power supply. However, this comes at the cost of increased control complexity. Driving an H-bridge requires at least two, and sometimes up to four, independent control signals. This significantly occupies valuable MCU general-purpose input / output (GPIO) ports. In complex embedded systems, MCU I / O ports are often scarce. Using multiple I / O ports to drive a single relay limits the MCU's ability to connect to other peripherals such as sensors and communication modules, or forces designers to use a more expensive MCU with more pins.

[0005] Existing bidirectional pulse magnetic latching relay control technology has technical problems such as reliance on dual power supplies, which increases PCB area and cost, or the use of H-bridges, which leads to high MCU resource consumption and complex control. It also generally faces strict drive pulse windows and the risk of coil burnout under abnormal conditions.

[0006] Therefore, the industry urgently needs a new control circuit that can be powered by a single power supply, occupy less MCU resources, simplify timing control, and fundamentally avoid coil burning due to accidental continuous power supply at the hardware level to achieve control of the magnetic latching relay. Summary of the Invention

[0007] The main purpose of the present invention is to provide a control circuit and method for a relay, aiming to provide a new control circuit that can be powered by a single power supply, occupy less MCU resources, simplify timing control, and fundamentally avoid coil burning due to accidental continuous power supply at the hardware level.

[0008] To achieve the above object, the present invention provides a control circuit for a relay, which is powered by a single positive power supply and includes: a state switching module, the state switching module being configured to receive and analyze the level state of a single control signal and output corresponding internal control instructions accordingly; a self-terminating pulse generating module, which is triggered by the state switching module and configured to generate only one drive pulse with a predetermined duration and self-terminating at the hardware level each time it is triggered, through the transient characteristics of capacitor charging, thereby avoiding burning of the relay coil due to the continuous validity of the control signal; a power amplification module electrically connected to the self-terminated pulse generation module, configured to amplify the self-terminated drive pulse into a power pulse sufficient to drive the coil of the magnetic latching relay; The polarity switching module is controlled by the internal control instruction of the state switching module, and is used to receive the power pulse and apply the power pulse to the magnetic latching relay coil in a forward or reverse polarity by switching the current path.

[0009] In one embodiment of the present application, the state switching module specifically includes: a first NPN transistor Q2, a first relay K1, and a first resistor R2; Among them, the emitter of the first NPN transistor Q2 is directly grounded, and its base is electrically connected to the input end of the single control signal through the first resistor R2; the first coil end 1 of the first relay K1 is electrically connected to the collector of the first NPN transistor Q2; the first normally open contact 2 of the first relay K1 is grounded; the first normally closed contact 3 of the first relay K1 is connected to the polarity switching module; the first common end 4, the second common end 5, the second normally open contact 7, and the second coil end 8 of the first relay K1 are all connected to the power supply VCC; the second normally closed contact 6 of the first relay K1 is electrically connected to the self-terminating pulse generating module.

[0010] In one embodiment of the present application, the state switching module further includes: Freewheeling diode D2; The anode of the freewheeling diode D2 is electrically connected to the collector of the first NPN transistor Q2 , and the cathode of the freewheeling diode D2 is connected to the power supply VCC, so as to protect the first NPN transistor Q2 .

[0011] In one embodiment of the present application, the polarity switching module specifically includes: a second NPN transistor Q1, a second relay K2, and a second resistor R3; Among them, the first normally closed contact 3 of the first relay K1 in the state switching module is electrically connected to the base of the second NPN transistor Q1 through the second resistor R3; the emitter of the second NPN transistor Q1 is grounded, and its collector is electrically connected to the first coil terminal 1 of the second relay K2; the second coil terminal 8 of the second relay K2 is connected to the power supply VCC; the contacts of the second relay K2 are configured as an H-bridge structure, which is used to apply the power supply VCC received at its common terminal and the output signal of the power amplifier module to the coil of the magnetic latching relay KM1A with different polarities.

[0012] In one embodiment of the present application, the polarity switching module further includes: A freewheeling diode D1 ; wherein the anode of the freewheeling diode D1 is electrically connected to the collector of the second NPN transistor Q1 , and the cathode of the freewheeling diode D1 is connected to the power supply VCC, for protecting the second NPN transistor Q1 .

[0013] In one embodiment of the present application, the self-terminating pulse generating module specifically includes: A photocoupler N1, a third resistor R1, and a first capacitor C1; Among them, the second normally closed contact 6 of the first relay K1 in the state switching module is electrically connected to the first end of the third resistor R1, the second end of the third resistor R1 is connected to the first end of the first capacitor C1, and the second end of the first capacitor C1 is connected to the input anode of the photoelectric coupler N1; the input cathode of the photoelectric coupler N1 is grounded.

[0014] In one embodiment of the present application, the power amplification module specifically includes: N-channel MOS transistor Q3 and fourth resistor R4; The source of the N-channel MOS transistor Q3 is grounded, and the drain thereof is connected to the polarity switching module as a power output terminal; the fourth resistor R4 is connected between the gate of the N-channel MOS transistor Q3 and the ground; and the gate of the N-channel MOS transistor Q3 is also electrically connected to the output emitter of the optocoupler N1 in the self-termination pulse generation module.

[0015] In one embodiment of the present application, the circuit further provides a voltage stabilization circuit for the driver stage of the power amplifier module, which specifically includes: A fifth resistor R5, a voltage stabilizing diode D3 and a second capacitor C2; The fifth resistor R5 is connected in series between the power supply VCC and the output collector of the photocoupler N1 ; the voltage stabilizing diode D3 and the second capacitor C2 are connected in parallel and connected between the output collector of the photocoupler N1 and ground.

[0016] In one embodiment of the present application, the power amplification module further includes: A third capacitor C3; The third capacitor C3 is connected between the drain of the N-channel MOS transistor Q3 and the ground, and is used for output buffering or energy storage.

[0017] The present application also discloses a method for controlling a relay, comprising the following steps: monitoring a change in a level state of the single control signal from a first state to a second state; In response to the change in the level state, the following operations are automatically and synchronously performed: Based on the changed second level state, a current driving path corresponding to a forward direction or a reverse direction is automatically selected at the hardware level; A hardware timing circuit automatically generates a drive pulse having a predetermined duration and self-terminating at the end of the pulse, wherein the generation and termination of the pulse are independent of whether the single control signal continues to remain in the second state, thereby fundamentally preventing damage to the relay coil due to accidental continuous power supply; The self-terminating driving pulse is applied to the configured current driving path to drive the magnetic latching relay to complete an attraction or release action corresponding to the second state.

[0018] Using the above technical solution, firstly, the circuit only requires a single positive power supply, which greatly simplifies the power supply design and reduces material costs and circuit board area compared to the traditional solution that requires both positive and negative power supplies. Secondly, by parsing a single control signal through the state switching module, bidirectional control of the magnetic latching relay can be achieved using only an ordinary IO port of an MCU or PLC, saving valuable control resources. Thirdly, the core self-terminating pulse generation module ensures the precise width and automatic stop of the drive pulse at the hardware level, completely eliminating the risk of burning the relay coil due to inaccurate timing or continuous validity of the control signal, and significantly improving the stability and reliability of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be described in detail below with reference to specific embodiments and accompanying drawings, wherein: Figure 1 Schematic diagram of the circuit structure of the first embodiment of the present invention; Figure 2 It is a schematic diagram of the process structure of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the following specific embodiments are only used to explain the present invention and do not constitute a limitation of the present invention.

[0021] like Figure 1 As shown, in order to achieve the above-mentioned object, the present invention provides a control circuit of a relay, which is powered by a single positive power supply and includes: a state switching module, the state switching module being configured to receive and analyze the level state of a single control signal and output corresponding internal control instructions accordingly; a self-terminating pulse generating module, which is triggered by the state switching module and configured to generate only one drive pulse with a predetermined duration and self-terminating at the hardware level each time it is triggered, through the transient characteristics of capacitor charging, thereby avoiding burning of the relay coil due to the continuous validity of the control signal; a power amplification module electrically connected to the self-terminated pulse generation module, configured to amplify the self-terminated drive pulse into a power pulse sufficient to drive the coil of the magnetic latching relay; The polarity switching module is controlled by the internal control instruction of the state switching module, and is used to receive the power pulse and apply the power pulse to the magnetic latching relay coil in a forward or reverse polarity by switching the current path.

[0022] Specifically, a relay control circuit is powered by a single positive power supply. The overall circuit framework includes a state switching module, a self-terminating pulse generation module, a power amplifier module, and a polarity switching module. The state switching module, as the control core, is responsible for receiving a single external control signal and outputting internal control instructions to the self-terminating pulse generation module and the polarity switching module based on the level of the single control signal. After receiving the trigger instruction from the state switching module, the self-terminating pulse generation module generates a hardware-level self-terminating drive pulse with a predetermined duration and outputs the drive pulse to the power amplifier module. The power amplifier module amplifies the received drive pulse and outputs a power pulse sufficient to drive the final load to the polarity switching module. The polarity switching module, based on the instruction issued by the state switching module, determines whether to apply the power pulse to the magnetic latching relay coil with forward or reverse polarity, thereby completing the operation of closing or releasing the magnetic latching relay.

[0023] In one embodiment, the state switching module can be composed of discrete components, for example, an NPN transistor and a small electromagnetic relay, wherein a single control signal is connected to the base of the NPN transistor through a current-limiting resistor, the emitter of the NPN transistor is grounded, the collector of the NPN transistor is connected in series with the coil of the electromagnetic relay and then connected to a single positive power supply, and the multiple sets of contacts of the electromagnetic relay are output to other modules as internal control instructions.

[0024] In another embodiment, the state switching module can also be implemented using an integrated logic circuit, for example, an integrated circuit chip including a D flip-flop and a logic gate (such as an AND gate, a NOT gate), using the D flip-flop to detect the rising edge or falling edge change of a single control signal, and combining the logic gate circuit to parse out the trigger signal and the direction control signal as an internal control instruction.

[0025] The core function of the self-terminating pulse generation module is to utilize the transient characteristics of the capacitor to generate a fixed-width pulse that is not affected by the duration of the input signal. In one embodiment, the self-terminating pulse generation module can be composed of a resistor-capacitor differential circuit and a Schmitt trigger. The trigger instruction output by the state switching module is coupled to the input end of the Schmitt trigger through the capacitor, and a spike pulse is generated at the input end of the Schmitt trigger by utilizing the instantaneous charge and discharge characteristics of the capacitor. The Schmitt trigger then shapes the spike pulse into a square wave drive pulse with a steep edge and a predetermined width. The pulse width is determined by the time constant of the resistor and capacitor. In another embodiment, the self-terminating pulse generation module can use a dedicated monostable trigger integrated circuit, such as a timer chip, and configure it in a monostable working mode. The trigger instruction output by the state switching module is connected to the trigger pin of the timer chip. By adjusting the value of an external resistor and a capacitor, the duration of the self-terminating drive pulse generated at the output end of the timer chip can be accurately set.

[0026] The power amplifier module is used to enhance driving capability. In one embodiment, the power amplifier module can be composed of an N-channel enhancement-mode metal oxide semiconductor field-effect transistor. The drive pulse output from the termination pulse generation module is connected to the gate of the N-channel enhancement-mode MOSFET. The source of the N-channel enhancement-mode MOSFET is grounded, and the drain of the N-channel enhancement-mode MOSFET is connected to the polarity switching module as a power output terminal.

[0027] The polarity switching module is responsible for switching the direction of the current applied to the coil of the magnetic latching relay. In one embodiment, the polarity switching module can use an H-bridge circuit composed of four power transistors. The coil of the magnetic latching relay is connected across the two output terminals of the H-bridge. The internal control instructions output by the state switching module are used to control the two pairs of transistors at the diagonal ends of the H-bridge to alternately conduct, thereby achieving forward or reverse current flow. In another embodiment, the polarity switching module can use a double-pole double-throw power relay. The power pulse output by the power amplifier module is connected to the two common terminals of the double-pole double-throw relay. The coil of the magnetic latching relay is connected between two sets of normally open and normally closed contacts to form a cross connection. The internal control instructions output by the state switching module are used to drive the coil of the double-pole double-throw relay, and the direction of the current flowing through the coil of the magnetic latching relay is changed by switching the contact position of the double-pole double-throw relay.

[0028] The circuit operates as follows: When a single control signal transitions from low to high, the state switching module interprets this change and outputs an internal control instruction for forward drive to the polarity commutation module. Simultaneously, it sends a trigger instruction to the self-terminating pulse generation module. Once triggered, the self-terminating pulse generation module immediately generates a self-terminating drive pulse of a predetermined width and transmits it to the power amplifier module. The power amplifier module amplifies this drive pulse into a power pulse and transmits it to the polarity commutation module. The polarity commutation module, operating under the pre-set forward drive path, applies this power pulse to the coil of the magnetic latching relay, causing it to engage. After the pulse ends, the magnetic latching relay's state is retained due to its characteristics. When the single control signal transitions from high back to low, the state switching module interprets this change and outputs an internal control instruction for reverse drive to the polarity commutation module. This triggers the self-terminating pulse generation module to generate the same pulse again. After power amplification and application of reverse polarity, this pulse releases the magnetic latching relay.

[0029] Using the above technical solution, firstly, the circuit only requires a single positive power supply, which greatly simplifies the power supply design and reduces material costs and circuit board area compared to the traditional solution that requires both positive and negative power supplies. Secondly, by parsing a single control signal through the state switching module, bidirectional control of the magnetic latching relay can be achieved using only an ordinary IO port of an MCU or PLC, saving valuable control resources. Thirdly, the core self-terminating pulse generation module ensures the precise width and automatic stop of the drive pulse at the hardware level, completely eliminating the risk of burning the relay coil due to inaccurate timing or continuous validity of the control signal, and significantly improving the stability and reliability of the circuit.

[0030] Among them, IO port represents input and output port.

[0031] In one embodiment of the present application, the state switching module specifically includes: a first NPN transistor Q2, a first relay K1, and a first resistor R2; Among them, the emitter of the first NPN transistor Q2 is directly grounded, and its base is electrically connected to the input end of the single control signal through the first resistor R2; the first coil end 1 of the first relay K1 is electrically connected to the collector of the first NPN transistor Q2; the first normally open contact 2 of the first relay K1 is grounded; the first normally closed contact 3 of the first relay K1 is connected to the polarity switching module; the first common end 4, the second common end 5, the second normally open contact 7, and the second coil end 8 of the first relay K1 are all connected to the power supply VCC; the second normally closed contact 6 of the first relay K1 is electrically connected to the self-terminating pulse generating module.

[0032] Specifically, the state switching module specifically includes a first NPN transistor Q2, a first relay K1, and a first resistor R2. In terms of circuit connection, the emitter of the first NPN transistor Q2 is directly grounded, and the base of the first NPN transistor Q2 is electrically connected to the input end of the single control signal through the first resistor R2. The first coil end 1 of the first relay K1 is electrically connected to the collector of the first NPN transistor Q2. In order to power the relay and its contacts, the first common end 4, the second common end 5, the second normally open contact 7, and the second coil end 8 of the first relay K1 are all connected to the power supply VCC. The first normally open contact 2 of the first relay K1 is directly grounded. The first relay K1 is used to output internal control instructions, wherein the first normally closed contact 3 of the first relay K1 is connected to the polarity switching module, and the second normally closed contact 6 of the first relay K1 is electrically connected to the self-terminating pulse generation module.

[0033] The circuit operates as follows: when the single control signal is high, current flows through the first resistor R2 into the base of the first NPN transistor Q2, turning on the first NPN transistor Q2. Once turned on, the collector potential of the first NPN transistor Q2 is pulled low, creating a current path between the power supply VCC and ground through the coil of the first relay K1, thereby activating the first relay K1. Upon activation, the internal contacts of the first relay K1 switch, disconnecting the first common terminal 4 connected to the power supply VCC from the first normally closed contact 3 and connecting to the grounded first normally open contact 2. Simultaneously, the second common terminal 5 connected to the power supply VCC disconnects from the second normally closed contact 6 and connects to the second normally open contact 7, also connected to the power supply VCC. When the single control signal is low, the first NPN transistor Q2 turns off, de-energizing the coil of the first relay K1 and restoring its internal contacts to their normal state. In this normal state, the first common terminal 4 connected to the power supply VCC is connected to the first normally closed contact 3, outputting a high-level signal to the polarity switching module; at the same time, the second common terminal 5 connected to the power supply VCC is connected to the second normally closed contact 6, outputting a high-level signal to the self-terminating pulse generating module.

[0034] Using this technical solution, the first NPN transistor Q2 drives the first relay K1, allowing a weak control signal to control the relay's on / off state, achieving power amplification and electrical isolation at the control end. Furthermore, the double-pole, double-throw contact structure of the first relay K1 cleverly converts changes in a single control signal into two independent, logically coordinated internal control commands, resulting in a simple circuit structure and reliable operation.

[0035] In one embodiment of the present application, the state switching module further includes: Freewheeling diode D2; The anode of the freewheeling diode D2 is electrically connected to the collector of the first NPN transistor Q2 , and the cathode of the freewheeling diode D2 is connected to the power supply VCC, so as to protect the first NPN transistor Q2 .

[0036] Specifically, the state switching module further includes a freewheeling diode D2. The anode of the freewheeling diode D2 is electrically connected to the collector of the first NPN transistor Q2, while the cathode of the freewheeling diode D2 is connected to the power supply VCC. The core function of the freewheeling diode D2 is to protect the first NPN transistor Q2.

[0037] By adopting the above technical solution, by connecting the freewheeling diode D2 in reverse parallel at both ends of the coil of the first relay K1, an effective discharge path is provided for the reverse electromotive force generated by the coil when the first NPN transistor Q2 is turned off, which significantly enhances the stability and reliability of the circuit and effectively extends the service life of the first NPN transistor Q2.

[0038] In one embodiment of the present application, the polarity switching module specifically includes: a second NPN transistor Q1, a second relay K2, and a second resistor R3; Among them, the first normally closed contact 3 of the first relay K1 in the state switching module is electrically connected to the base of the second NPN transistor Q1 through the second resistor R3; the emitter of the second NPN transistor Q1 is grounded, and its collector is electrically connected to the first coil terminal 1 of the second relay K2; the second coil terminal 8 of the second relay K2 is connected to the power supply VCC; the contacts of the second relay K2 are configured as an H-bridge structure, which is used to apply the power supply VCC received at its common terminal and the output signal of the power amplifier module to the coil of the magnetic latching relay KM1A with different polarities.

[0039] Specifically, the polarity switching module includes a second NPN transistor Q1, a second relay K2, and a second resistor R3. The module's control input signal originates from the first normally closed contact 3 of the first relay K1 in the state switching module. This first normally closed contact 3 of the first relay K1 is electrically connected to the base of the second NPN transistor Q1 via the second resistor R3. The second NPN transistor Q1 acts as a switching element, with its emitter directly grounded and its collector electrically connected to the first coil terminal 1 of the second relay K2, controlling the on / off switching of the second relay K2. The second coil terminal 8 of the second relay K2 is connected to the power supply VCC, forming a complete drive circuit together with the second NPN transistor Q1. The core function of the second relay K2 is to switch the direction of current. To this end, the contacts of the second relay K2 are configured as an H-bridge structure. By switching the contact states, the power supply VCC received at its common terminal and the power pulse signal output by the power amplifier module can be applied to the coil of the magnetic latching relay KM1A with different polarities.

[0040] Its operating principle is as follows: When the first normally closed contact 3 of the first relay K1 outputs a high level, current flows through the second resistor R3 into the base of the second NPN transistor Q1, turning on the second NPN transistor Q1. This conduction of the second NPN transistor Q1 energizes the coil of the second relay K2, causing the H-bridge contacts of the second relay K2 to switch to the first operating state. In this state, the power supply VCC and the output signal of the power amplifier module are configured through the contacts to form a positive current path, for example, and are applied to the coil of the magnetic latching relay KM1A. Conversely, when the first normally closed contact 3 of the first relay K1 outputs a low level or high impedance state, the second NPN transistor Q1 is turned off, de-energizing the coil of the second relay K2, and its H-bridge contacts return to the second operating state (normal state). In this state, the power supply VCC and the output signal of the power amplifier module are configured through the contacts to form a current path opposite to that in the first operating state, for example, a reverse current path, and are applied to the coil of the magnetic latching relay KM1A.

[0041] By adopting the above technical solution, the second NPN transistor Q1 is used to drive the second relay K2, thereby realizing the on-off control of a power relay by utilizing the logic level signal from the state switching module.

[0042] In one embodiment of the present application, the polarity switching module further includes: A freewheeling diode D1; wherein the anode of the freewheeling diode D1 is electrically connected to the collector of the second NPN transistor Q1, and the cathode thereof is connected to the power supply VCC, for protecting the second NPN transistor Q1.

[0043] Specifically, the polarity switching module further includes a freewheeling diode D1. In terms of circuit connection, the anode of the freewheeling diode D1 is electrically connected to the collector of the second NPN transistor Q1, while the cathode of the freewheeling diode D1 is connected to the power supply VCC. The freewheeling diode D1 is added to protect the second NPN transistor Q1.

[0044] By adopting the above technical solution, a freewheeling diode D1 is connected in parallel to the switching transistor that drives the relay coil, which provides a reliable discharge channel for the reverse electromotive force generated by the inductive load when the power is cut off, thereby greatly improving the working reliability and service life of the second NPN transistor Q1, and ensuring the long-term stable operation of the entire polarity commutation module.

[0045] In one embodiment of the present application, the self-terminating pulse generating module specifically includes: A photocoupler N1, a third resistor R1, and a first capacitor C1; Among them, the second normally closed contact 6 of the first relay K1 in the state switching module is electrically connected to the first end of the third resistor R1, the second end of the third resistor R1 is connected to the first end of the first capacitor C1, and the second end of the first capacitor C1 is connected to the input anode of the photoelectric coupler N1; the input cathode of the photoelectric coupler N1 is grounded.

[0046] Specifically, the self-termination pulse generation module specifically includes a photoelectric coupler N1, a third resistor R1, and a first capacitor C1. The input signal of this module is provided by the state switching module. Specifically, the second normally closed contact 6 of the first relay K1 in the state switching module is electrically connected to the first end of the third resistor R1. The second end of the third resistor R1 is connected in series to the first end of the first capacitor C1. Subsequently, the second end of the first capacitor C1 is connected to the input anode of the photoelectric coupler N1, and the input cathode of the photoelectric coupler N1 is directly grounded. This connection mode constitutes an RC series charging circuit that responds to voltage step changes, which is used to drive the light emitting diode of the photoelectric coupler N1.

[0047] Its operating principle is as follows: when the output terminal of the second normally closed contact 6 of the first relay K1 transitions from a low level to a high level, because the voltage across the first capacitor C1 cannot change suddenly, a transient charging current immediately flows through the third resistor R1, the first capacitor C1, and the input LED of the photocoupler N1. This transient current causes the LED within the photocoupler N1 to illuminate, turning on its phototransistor and generating the starting edge of a drive pulse. As the charging process progresses, the voltage across the first capacitor C1 gradually increases, causing the charging current flowing through the entire series circuit to decay exponentially. When this current decays below the threshold that is insufficient to maintain the LED within the photocoupler N1, the LED turns off, the phototransistor turns off, and the drive pulse ends. The duration of the entire pulse is determined by the time constant determined by the values ​​of the third resistor R1 and the first capacitor C1. This achieves automatic pulse generation and termination at the hardware level, regardless of whether the second normally closed contact 6 of the first relay K1 remains at a high level.

[0048] The above technical solution, by connecting a resistor, capacitor, and optocoupler in series, cleverly exploits the transient characteristics of capacitor charging to construct a simple and reliable hardware pulse generator. This design not only automatically generates drive pulses of a defined width, eliminating the complex requirements for precise timing control in the main controller, but also achieves electrical isolation between the control signal and the subsequent power circuit through the optocoupler N1, effectively suppressing noise interference and improving the stability and anti-interference capabilities of the entire control circuit.

[0049] In one embodiment of the present application, the power amplification module specifically includes: N-channel MOS transistor Q3 and fourth resistor R4; The source of the N-channel MOS transistor Q3 is grounded, and the drain thereof is connected to the polarity switching module as a power output terminal; the fourth resistor R4 is connected between the gate of the N-channel MOS transistor Q3 and the ground; and the gate of the N-channel MOS transistor Q3 is also electrically connected to the output emitter of the optocoupler N1 in the self-termination pulse generation module.

[0050] Specifically, the power amplifier module specifically includes an N-channel MOS transistor Q3 and a fourth resistor R4. In the connection structure of the circuit, the N-channel MOS transistor Q3 serves as the main power switching element, and its source is directly grounded. The drain of the N-channel MOS transistor Q3 serves as the power output end of the entire module, and is electrically connected to the polarity switching module for transmitting amplified power pulses to the subsequent circuit. In order to ensure that the N-channel MOS transistor Q3 can be reliably turned off, the fourth resistor R4 is connected across the gate of the N-channel MOS transistor Q3 and the ground. The control input signal of this module comes from the self-termination pulse generation module of the previous stage. Specifically, the gate of the N-channel MOS transistor Q3 is also electrically connected to the output emitter of the photoelectric coupler N1 in the self-termination pulse generation module.

[0051] The circuit operates as follows: When the optocoupler N1 in the self-terminating pulse generation module is triggered and turned on, its output emitter outputs a positive drive pulse signal to the gate of the N-channel MOS transistor Q3. When this gate voltage exceeds the turn-on threshold voltage of the N-channel MOS transistor Q3, the N-channel MOS transistor Q3 rapidly turns on, exhibiting an extremely low on-resistance between its drain and source. This pulls the drain potential of the N-channel MOS transistor Q3 close to ground, forming a high-current switching path. When the drive pulse output by the optocoupler N1 ends, the fourth resistor R4 provides a discharge path to ground for the charge accumulated on the gate of the N-channel MOS transistor Q3, rapidly pulling the gate voltage down to zero. This ensures that the N-channel MOS transistor Q3 can quickly and reliably switch from the on state to the off state, avoiding mis-turn-on caused by a floating gate.

[0052] The above technical solution uses N-channel MOS transistor Q3 as a switch, leveraging its voltage-driven and low on-resistance characteristics to achieve efficient power amplification of the weak drive signal from the preceding optocoupler, capable of driving a large load current. Furthermore, the fourth resistor R4 is configured as a pull-down resistor, ensuring that the power switch is in a defined off state when no drive signal is present, enhancing the circuit's stability and anti-interference capabilities and preventing accidental connection of the power output terminal.

[0053] In one embodiment of the present application, the circuit further provides a voltage stabilization circuit for the driver stage of the power amplifier module, which specifically includes: A fifth resistor R5, a voltage stabilizing diode D3 and a second capacitor C2; The fifth resistor R5 is connected in series between the power supply VCC and the output collector of the photocoupler N1 ; the voltage stabilizing diode D3 and the second capacitor C2 are connected in parallel and connected between the output collector of the photocoupler N1 and ground.

[0054] Specifically, the circuit also includes a voltage stabilization circuit for the driver stage of the power amplifier module. This voltage stabilization circuit specifically includes a fifth resistor R5, a voltage stabilization diode D3, and a second capacitor C2. In terms of the circuit's connection structure, the fifth resistor R5 is connected in series between the power supply VCC and the output collector of the photocoupler N1. The voltage stabilization diode D3 and the second capacitor C2 are first connected in parallel with each other, and then this parallel combination is connected between the output collector of the photocoupler N1 and ground. This circuit constitutes a typical parallel voltage stabilization circuit.

[0055] By adopting the above technical solution, a voltage stabilization circuit consisting of a resistor, a voltage stabilizing diode, and a capacitor is added to the output stage of the photocoupler N1, thereby ensuring that the voltage amplitude of the drive signal is not affected by fluctuations in the main power supply VCC, thereby ensuring the stability and consistency of the gate drive voltage of the subsequent N-channel MOS transistor Q3.

[0056] In one embodiment of the present application, the power amplification module further includes: A third capacitor C3; The third capacitor C3 is connected between the drain of the N-channel MOS transistor Q3 and the ground, and is used for output buffering or energy storage.

[0057] Specifically, the power amplifier module further includes a third capacitor C3. In the circuit connection structure, the third capacitor C3 is connected between the drain of the N-channel MOS transistor Q3 and the ground. The third capacitor C3 mainly plays the role of output buffering or energy storage in the circuit.

[0058] By adopting the above technical solution, by connecting the third capacitor C3 in parallel to the output end of the power amplifier module, on the one hand, the noise and voltage spikes generated during the switching process can be effectively suppressed, thereby improving the quality of the output pulse signal and the electromagnetic compatibility of the circuit; on the other hand, it can provide instantaneous high current support, enhance the circuit's driving capability and load response speed, and make the performance of the entire power output stage more stable and reliable.

[0059] like Figure 2 As shown, the present application also discloses a control method for a relay, comprising the following steps: monitoring a change in a level state of the single control signal from a first state to a second state; In response to the change in the level state, the following operations are automatically and synchronously performed: Based on the changed second level state, a current driving path corresponding to a forward direction or a reverse direction is automatically selected at the hardware level; A hardware timing circuit automatically generates a drive pulse having a predetermined duration and self-terminating at the end of the pulse, wherein the generation and termination of the pulse are independent of whether the single control signal continues to remain in the second state, thereby fundamentally preventing damage to the relay coil due to accidental continuous power supply; The self-terminating driving pulse is applied to the configured current driving path to drive the magnetic latching relay to complete an attraction or release action corresponding to the second state.

[0060] Specifically, the circuit monitors the change in the level state of the single control signal from the first state to the second state. For example, when the voltage of the single control signal jumps from a low level representing the first state to a high level representing the second state, the circuit detects this change. In response to the change in the level state, the circuit automatically and synchronously performs a series of subsequent operations. The first operation is to automatically select a current drive path corresponding to a forward or reverse direction at the hardware level based on the changed second level state. For example, when the signal changes to a high level (the second state), the first relay K1 in the state switching module will operate, and the change in its contacts will control the second relay K2 in the polarity switching module to switch to a preset position, thereby configuring a forward current path for the upcoming power pulse that can cause the magnetic latching relay to attract.

[0061] The second parallel operation involves automatically generating a drive pulse of a predetermined duration through a hardware timing circuit that self-terminates at the end of the pulse. This operation is accomplished by the self-terminating pulse generation module. For example, a change in the contact of the first relay K1 in the state switching module triggers the charging of an RC circuit (composed of a third resistor R1 and a first capacitor C1). This charging transient generates a pulse of a fixed width determined by the RC time constant. The generation and termination of this pulse are independent of whether the single control signal remains in the second state, thereby fundamentally preventing damage to the relay coil due to accidental continuous energization. Once the RC circuit is fully charged, the pulse automatically ends, even if the single control signal remains high.

[0062] The final step involves applying the self-terminating drive pulse to the configured current drive path, driving the latching relay to engage or release, corresponding to the second state. The hardware-timed pulse generated in the previous step is amplified by the power amplifier module and applied to the forward current path selected by the polarity reversal module, thereby driving the coil of the latching relay KM1A and reliably engaging it. When the single control signal transitions from a high level (second state) back to a low level (first state), the aforementioned process is triggered again, but now the polarity reversal module is configured to use the reverse current path, ultimately driving the latching relay to release.

[0063] This approach completely integrates complex timing control logic into the hardware. The controller only needs to change the output signal level, without having to worry about pulse width and timing, significantly simplifying upper-level software control. By generating self-terminating pulses through hardware timing circuitry, the risk of expensive latching relays being damaged by abnormal control signals is eliminated, significantly improving system reliability and safety.

[0064] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention description and drawings under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A control circuit of a relay, characterized in that: The circuit operates from a single positive supply and includes: a state switching module, the state switching module being configured to receive and analyze the level state of a single control signal and output corresponding internal control instructions accordingly; a self-terminating pulse generating module, which is triggered by the state switching module and configured to generate only one drive pulse with a predetermined duration and self-terminating at the hardware level each time it is triggered, through the transient characteristics of capacitor charging, thereby avoiding burning of the relay coil due to the continuous validity of the control signal; a power amplification module electrically connected to the self-terminated pulse generation module, configured to amplify the self-terminated drive pulse into a power pulse sufficient to drive the coil of the magnetic latching relay; The polarity switching module is controlled by the internal control instruction of the state switching module, and is used to receive the power pulse and apply the power pulse to the magnetic latching relay coil in a forward or reverse polarity by switching the current path.

2. The control circuit of the relay according to claim 1, characterized in that: The state switching module specifically includes: a first NPN transistor Q2, a first relay K1, and a first resistor R2; Among them, the emitter of the first NPN transistor Q2 is directly grounded, and its base is electrically connected to the input end of the single control signal through the first resistor R2; the first coil end 1 of the first relay K1 is electrically connected to the collector of the first NPN transistor Q2; the first normally open contact 2 of the first relay K1 is grounded; the first normally closed contact 3 of the first relay K1 is connected to the polarity switching module; the first common end 4, the second common end 5, the second normally open contact 7, and the second coil end 8 of the first relay K1 are all connected to the power supply VCC; the second normally closed contact 6 of the first relay K1 is electrically connected to the self-terminating pulse generating module.

3. The control circuit of the relay according to claim 2, wherein: The state switching module also includes: Freewheeling diode D2; The anode of the freewheeling diode D2 is electrically connected to the collector of the first NPN transistor Q2 , and the cathode of the freewheeling diode D2 is connected to the power supply VCC, so as to protect the first NPN transistor Q2 .

4. The control circuit of the relay according to claim 2, wherein: The polarity switching module specifically includes: a second NPN transistor Q1, a second relay K2, and a second resistor R3; Among them, the first normally closed contact 3 of the first relay K1 in the state switching module is electrically connected to the base of the second NPN transistor Q1 through the second resistor R3; the emitter of the second NPN transistor Q1 is grounded, and its collector is electrically connected to the first coil terminal 1 of the second relay K2; the second coil terminal 8 of the second relay K2 is connected to the power supply VCC; the contacts of the second relay K2 are configured as an H-bridge structure, which is used to apply the power supply VCC received at its common terminal and the output signal of the power amplifier module to the coil of the magnetic latching relay KM1A with different polarities.

5. The control circuit of the relay according to claim 4, characterized in that: The polarity switching module further includes: A freewheeling diode D1; wherein the anode of the freewheeling diode D1 is electrically connected to the collector of the second NPN transistor Q1, and the cathode thereof is connected to the power supply VCC, for protecting the second NPN transistor Q1.

6. The control circuit of the relay according to claim 2, wherein: The self-terminating pulse generating module specifically includes: A photocoupler N1, a third resistor R1, and a first capacitor C1; Among them, the second normally closed contact 6 of the first relay K1 in the state switching module is electrically connected to the first end of the third resistor R1, the second end of the third resistor R1 is connected to the first end of the first capacitor C1, and the second end of the first capacitor C1 is connected to the input anode of the photoelectric coupler N1; the input cathode of the photoelectric coupler N1 is grounded.

7. The control circuit of the relay according to claim 6, characterized in that: The power amplification module specifically includes: N-channel MOS transistor Q3 and fourth resistor R4; The source of the N-channel MOS transistor Q3 is grounded, and the drain thereof is connected to the polarity switching module as a power output terminal; the fourth resistor R4 is connected between the gate of the N-channel MOS transistor Q3 and the ground; and the gate of the N-channel MOS transistor Q3 is also electrically connected to the output emitter of the optocoupler N1 in the self-termination pulse generation module.

8. The control circuit of the relay according to claim 7, wherein: The circuit also provides a voltage stabilization circuit for the driver stage of the power amplifier module, which specifically includes: A fifth resistor R5, a voltage stabilizing diode D3 and a second capacitor C2; The fifth resistor R5 is connected in series between the power supply VCC and the output collector of the photocoupler N1 ; the voltage stabilizing diode D3 and the second capacitor C2 are connected in parallel and connected between the output collector of the photocoupler N1 and ground.

9. The control circuit of the relay according to claim 7, wherein: The power amplification module further includes: A third capacitor C3; The third capacitor C3 is connected between the drain of the N-channel MOS transistor Q3 and the ground, and is used for output buffering or energy storage.

10. A method for controlling a relay, characterized in that: The following steps are involved: monitoring a change in a level state of a single control signal from a first state to a second state; In response to the change in the level state, the following operations are automatically and synchronously performed: Based on the changed second level state, a current driving path corresponding to a forward direction or a reverse direction is automatically selected at the hardware level; A hardware timing circuit automatically generates a drive pulse having a predetermined duration and self-terminating at the end of the pulse, wherein the generation and termination of the pulse are independent of whether the single control signal continues to remain in the second state, thereby fundamentally preventing damage to the relay coil due to accidental continuous power supply; The self-terminating driving pulse is applied to the configured current driving path to drive the magnetic latching relay to complete the pull-in or release action corresponding to the second state.

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