Power-off delay device based on high-precision real-time clock and without auxiliary power supply
Through the control circuit of high-precision real-time clock and dual-coil magnetic latching relay, the problems of inaccurate counting and auxiliary power supply required in existing power-off delay devices in harsh environments are solved, and a high-precision, long-delay, low-cost and high-reliability power-off delay effect is achieved.
Patent Information
- Application Number
- CN202510705238.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-29
- Publication Date
- 2025-10-10
AI Technical Summary
Existing power-off delay devices have inaccurate counting frequencies in harsh environments, making it difficult to achieve long-term delays and requiring additional auxiliary power supplies, resulting in large timing errors, high costs, and equipment instability.
A power-off delay device based on a high-precision real-time clock is used, combined with a dual-coil magnetic latching relay and its control circuit, including a step-down circuit, a power-off detection circuit, a dial delay setting circuit and a single-chip microcomputer control circuit. The charging circuit of the energy storage capacitor and the reset capacitor realizes high-precision delay timing without an auxiliary power supply.
It achieves high precision and long time delay, reduces device cost and volume, improves equipment reliability and stability, supports input in a wide voltage range, and has simple circuit design and easy operation.
Smart Images
Figure CN120768328A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to a power-off delay device, in particular to a power-off delay device based on a high-precision real-time clock and without an auxiliary power supply. BACKGROUND
[0002] With the continuous progress of science and technology and the increasing popularity of industrial automation, the complexity and precision of power systems and equipment are constantly improving. In many application scenarios, such as factory automation production lines and medical equipment, the stability and continuity of power supply are crucial to the normal operation of the equipment. In these scenarios, the equipment often needs to continue to perform certain key operations after power failure to ensure the safe and stable operation of the entire system, so a power-off delay device is needed.
[0003] At present, common power-off delay devices generally use programmable timers or CMOS counting and frequency dividing integrated circuits to realize the delay counting of the power-off delay device, but such power-off delay devices generally use adjustable resistors to adjust the counting frequency of the circuit to realize the setting of the delay. On the one hand, power-off delay devices are generally used in industrial applications, and the relatively harsh use environment may cause the resistance value of the adjustable resistor to change, thereby causing the counting frequency of the circuit to change greatly, so it is difficult and inaccurate to set the delay parameters of the circuit, the timing error is large, and the adjustment is not convenient. On the other hand, in order to realize a longer delay range, the existing power-off delay device usually needs an additional auxiliary power supply or uses a complex logic circuit design, which not only increases the size and manufacturing cost of the device, but also may reduce its reliability and stability. SUMMARY
[0004] The purpose of the present application is to provide a power-off delay device to improve the problems of low delay setting precision, low delay precision, short delay range, dependence on auxiliary power supply for wide delay, large size, etc.
[0005] Technical scheme: A power-off delay device based on a high-precision real-time clock and without an auxiliary power supply, comprising a double-coil magnetic latching relay and a control circuit thereof, the double-coil magnetic latching relay comprising a group of delay normally open contacts, a group of delay normally closed contacts, an action coil and a reset coil, characterized in that:
[0006] The control circuit comprises a first step-down circuit, a second step-down circuit, a power-off detection circuit, a dial delay setting circuit, an energy storage capacitor charging circuit, a relay reset capacitor charging circuit, a single-chip microcomputer control circuit and a relay driving circuit, wherein the relay driving circuit comprises a relay power-on driving circuit and a relay reset driving circuit; the input power source is connected with the first step-down circuit; the first step-down circuit is connected with the second step-down circuit, the power-off detection circuit, the relay power-on driving circuit and the relay reset capacitor charging circuit; the second step-down circuit is connected with the energy storage capacitor charging circuit and the dial delay setting circuit; the energy storage capacitor charging circuit is connected with the single-chip microcomputer control circuit; the single-chip microcomputer control circuit is connected with the power-off detection circuit and the dial delay setting circuit; the relay reset driving circuit is connected with the single-chip microcomputer control circuit and the relay reset capacitor charging circuit; the relay power-on driving circuit controls the action coil; and the relay reset driving circuit controls the reset coil.
[0007] When the input power source is powered on, the delay normally open contact is momentarily closed, the delay normally closed contact is momentarily opened, and the state is maintained during power-on; when the input power source is powered off, the delay timing is started, the delay normally open contact is opened, the delay normally closed contact is closed, and the state is maintained until the next power-on and power-off.
[0008] Further, the input power source is an AC power source or a DC power source, and the first step-down circuit is an AC / DC switching power supply circuit or a DC / DC switching power supply circuit.
[0009] The AC / DC switching power supply circuit is that the AC power source is first transmitted to the EMI filter circuit one through the fuse F1 and the pressure-sensitive resistor MOV1, then transmitted to the input of the AC / DC switching power supply U1 through the capacitor CX1, the common-mode inductor L1, the capacitor CY1 and the capacitor CY2 in the EMI filter circuit one; and the DC / DC switching power supply circuit is that the DC power source is first transmitted to the EMI filter circuit two through the fuse F2, the pressure-sensitive resistor MOV2 and the gas discharge tube G1, then transmitted to the input of the DC / DC switching power supply U2 through the common-mode inductor L2, the capacitor CP1 and the inductor LB1 in the EMI filter circuit two.
[0010] The output of the AC / DC switching power supply U1 or the output of the DC / DC switching power supply U2 is transmitted to the second step-down circuit, and then transmitted to the low-voltage power output through the low-dropout linear regulator in the second step-down circuit.
[0011] Further, the relay drive circuit is: the output of the first-stage voltage reduction circuit is connected to the connection point B through the current-limiting resistor R5, the capacitor C7, the first pin of the relay K, the anode of the diode D1, and the cathode of the diode D2, the connection point B is connected to the ground through the capacitor C7 and the resistor R6, the connection point A of the capacitor C7 and the resistor R6 is connected to the base of the transistor Q1, the collector of the transistor Q1 is connected to the 16th pin of the relay K and the anode of the diode D2, the emitter of the transistor Q1 is connected to the ground, the cathode of the diode D1 is connected to the capacitor C8, the other end of the capacitor C8 is connected to the ground, the connection point C of the cathode of the diode D1 and the capacitor C8 is connected to the second pin of the relay K and the cathode of the diode D3, the 15th pin of the relay K is connected to the anode of the diode D3 and the collector of the transistor Q2, the emitter of the transistor Q2 is connected to the ground, the base of the transistor Q2 is connected to the resistor R8 and the resistor R7, the other end of the resistor R8 is connected to the ground, and the other end of the resistor R7 is connected to the relay reset control signal.
[0012] Further, the power-off detection circuit includes a photoelectric coupler, the primary side of the photoelectric coupler is connected to the output of the first-stage voltage reduction circuit, and the secondary side is connected to the output of the second-stage voltage reduction circuit; when the input power is turned on, the secondary side outputs a high-level signal; and when the input power is turned off, the secondary side outputs a low-level signal.
[0013] Further, the output of the second-stage voltage reduction circuit is a charging power source of an energy storage capacitor in the energy storage capacitor charging circuit, and a diode D2 is connected in series in the energy storage capacitor charging circuit; when the input power is turned off, the diode D2 prevents the energy storage capacitor from supplying power to the second-stage voltage reduction circuit in reverse; the output of the first-stage voltage reduction circuit is a charging power source of a reset capacitor in the relay reset capacitor charging circuit, and a diode D1 is connected in series in the relay reset capacitor charging circuit; when the input power is turned off, the diode D1 prevents the reset capacitor from supplying power to the first-stage voltage reduction circuit in reverse.
[0014] Further, the single-chip microcomputer control circuit includes an M0 kernel single-chip microcomputer, a chip program download circuit, a reset circuit, and a quartz crystal oscillator; after the input power is turned off, the M0 kernel single-chip microcomputer runs in a standby mode, and the real-time clock counts to a set delay time to wake up the M0 kernel single-chip microcomputer; the single-chip microcomputer sends a command to make the relay reset.
[0015] Further, the dial code delay setting circuit includes two 8421 BCD encoders, which are used to set a time base and a time multiple respectively, and the final delay time is the product of the two corresponding values.
[0016] The working process of the power-off delay device is as follows: when the input power is powered on, the relay power-on driving circuit provides power for the relay action coil through the output power of the first step-down circuit, the relay is momentarily actuated, the output power of the first step-down circuit charges the reset capacitor, and the output power of the second step-down circuit charges the energy storage capacitor, and the delay time of the two encoders is set before or during power-on; when the input power is powered off, the energy storage capacitor provides power support for the power-off delay device without an external auxiliary power supply, the single-chip microcomputer enters standby mode, the real-time clock function is used to calculate the delay time, and the single-chip microcomputer is awakened after the predetermined delay time is reached, the single-chip microcomputer sends a reset signal, the relay reset driving circuit uses the energy stored in the reset capacitor to reset the relay, and the real-time clock and the low-power single-chip microcomputer with a wide voltage working range can effectively reduce the power consumption of the power-off delay device and prolong the delay time of the power-off delay device. Without an additional auxiliary power supply, the delay precision can be improved while the cost and size of the power-off delay device are reduced, and the reliability of the equipment is improved.
[0017] Advantages: the power-off delay device has the following advantages:
[0018] 1. High delay precision: the power-off delay device is based on high-precision real-time clock technology, cooperates with a reliable power-off detection circuit and a corresponding delay algorithm, and has extremely high timing precision, thereby ensuring the ultra-high delay precision of the power-off delay device.
[0019] 2. Long delay time: the power-off delay device stores sufficient energy in the energy storage capacitor during power-on, and after power-off, the single-chip microcomputer immediately enters standby mode, only the real-time clock is in the working state, the rest of the peripherals are in the power-off state, the single-chip microcomputer runs at extremely low power consumption, and the single-chip microcomputer is awakened only when the set delay time is reached. On the other hand, the power-off delay device adopts a single-chip microcomputer with a wide voltage working range, which can work in a relatively large voltage range.
[0020] 3. Wide power supply range: the power-off delay device supports AC 220V (85-265V) and DC 24V (18-36V) input power supplies of two different voltages, and adopts a two-stage step-down circuit and a high-efficiency switching power supply technology, thereby having a wide voltage input range.
[0021] 4. Relatively simple circuit design: the power-off delay device does not require an additional auxiliary power supply, and the circuit design is relatively simple, thereby reducing the cost.
[0022] 5. Convenient delay setting: the power-off delay device uses two 8421 BCD encoders to set the delay time, is simple to configure, does not require deep understanding of complex electronic or circuit knowledge, and is easy, accurate and reliable to operate.
[0023] 6. Strong versatility: the power-off delay device has the characteristics of high delay precision, long delay range, support for two voltage inputs, small size, etc. The device can be widely used in various devices that require power-off delay or time control;
[0024] 7. High reliability: the power-off delay device uses high-precision real-time clock technology, reliable energy storage devices and single-chip microcomputers, providing high reliability and stability during operation. BRIEF DESCRIPTION OF DRAWINGS
[0025] Figure 1 is a system block diagram of the power-off delay device;
[0026] Figure 2 is a working timing diagram of the power-off delay device;
[0027] Figure 3 is a hardware circuit diagram of the first-stage voltage reduction circuit and the second-stage voltage reduction circuit;
[0028] Figure 4 is a hardware circuit diagram of the relay driving circuit;
[0029] Figure 5 is Figure 4 is the voltage change curve of the connection point A and the connection point B;
[0030] Figure 6 is a hardware circuit diagram of the power-off detection circuit;
[0031] Figure 7 is Figure 6 is the change curve of the output signal of the photoelectric coupler, the 5V direct current and the reset signal of the single-chip microcomputer;
[0032] Figure 8 is a hardware circuit diagram of the energy storage capacitor charging circuit;
[0033] Figure 9 is a hardware circuit diagram of the relay reset capacitor charging circuit;
[0034] Figure 10 is Figure 8 is the charging voltage change curve of the energy storage capacitor, Figure 9 is the charging voltage change curve of the reset capacitor;
[0035] Figure 11 is a hardware circuit diagram of the single-chip microcomputer control circuit;
[0036] Figure 12 is the complete change curve of the energy storage capacitor, the reset capacitor, the power-off detection signal and the reset control signal in the working process;
[0037] Figure 13 is Figure 12 is the t AA partial magnified view of the moment;
[0038] Figure 14 This is a schematic diagram of the appearance of the power-off delay device. DETAILED DESCRIPTION
[0039] The present application is further explained below with reference to the accompanying drawings and specific embodiments.
[0040] A power-off delay device based on a high-precision real-time clock and without auxiliary power supply, including a relay and its control circuit. The relay adopts a double-coil magnetic latching relay, which includes a set of delayed normally open contacts, a set of delayed normally closed contacts, an action coil, and a reset coil. The HFE60P / 5-1HDSTG-L2 model can be used. Figure 1 This is a system block diagram of a power-off delay device. The control circuit includes a primary step-down circuit, a secondary step-down circuit, a power-off detection circuit, a dial-code delay setting circuit, an energy storage capacitor charging circuit, a relay reset capacitor charging circuit, a single-chip microcomputer control circuit, and a relay drive circuit. The relay drive circuit includes a relay power-on drive circuit and a relay reset drive circuit. The input power supply is connected to the primary step-down circuit, which is connected to the secondary step-down circuit, the power-off detection circuit, the relay power-on drive circuit, and the relay reset capacitor charging circuit. The secondary step-down circuit is connected to the energy storage capacitor charging circuit and the dial-code delay setting circuit. The energy storage capacitor charging circuit is connected to the single-chip microcomputer control circuit, which is connected to the power-off detection circuit and the dial-code delay setting circuit. The relay reset drive circuit is connected to the single-chip microcomputer control circuit and the relay reset capacitor charging circuit. The relay power-on drive circuit controls the actuation coil, and the relay reset drive circuit controls the reset coil.
[0041] Attachment Figure 2 This is the operating timing diagram of the power-off delay device. When the input power is applied to the power-off delay device, the normally open contact of the delay device instantly closes and the normally closed contact of the delay device instantly opens, and this state remains for the duration of the power-on period. When the input power is cut off, the delay timer begins. When the set delay time is reached, the normally open contact of the delay device opens and the normally closed contact of the delay device closes, and this state remains until the next power-on and power-off period. To ensure that the device's stored energy can continue to support operation for 10 minutes after a power outage, the minimum input power-on time must be no less than 500ms.
[0042] The primary step-down circuit and the secondary step-down circuit are the power sources of the power-off delay device. Figure 3 This is the hardware circuit diagram of the first-stage buck circuit and the second-stage buck circuit.
[0043] The input power supply is AC power supply or DC power supply, only one form of electrical energy can be connected each time, the first-stage voltage reduction circuit is AC / DC switching power supply circuit or DC / DC switching power supply circuit. The AC / DC switching power supply circuit is: 220V AC power supply input, first through 3A 250V fuse F1, then through 470V voltage-dependent resistor MOV1, and then delivered to EMI filter circuit one, the function of the EMI filter circuit is to suppress the differential mode interference and common mode interference on the power supply line, the EMI filter circuit one is through capacitor CX1, common mode inductor L1, capacitor CY1, capacitor CY2, and finally delivered to the input of AC / DC switching power supply U1, through the AC / DC switching power supply circuit, the input power supply 220V alternating current is converted into 5V direct current; the AC / DC switching power supply U1 selects the AC / DC switching power supply of Tesla FA3-220S05A2A-1 type, which integrates AC / DC rectifier circuit and DC / DC chopper circuit. The DC / DC switching power supply circuit is: 24V DC power supply input, first through 3A 250V fuse F2, then through 470V voltage-dependent resistor MOV2 and 3KA discharge capacity gas discharge tube G1 protection, and then delivered to EMI filter circuit two, the EMI filter circuit two is through LC filter composed of common mode inductor L2, capacitor CP1 and inductor LB1, and finally delivered to the input of DC / DC switching power supply U2, through the DC / DC switching power supply circuit, the input power supply 24V direct current is converted into 5V direct current; the DC / DC switching power supply U2 selects the DC / DC switching power supply of Jinshengyang WRB2405-3W type. The front end of the AC / DC switching power supply U1 and the DC / DC switching power supply U2 is provided with surge protection and EMI filter circuit, which prevents the device from being damaged by lightning and transient high voltage, and prevents the input power supply interference from affecting the power-off delay device and the equipment from affecting the input power supply. In this application, the AC power supply can also use 85-265V voltage, and the DC power supply can also use 18-36V voltage, which are all converted into 5V direct current voltage.
[0044] The 5V direct current output by the first-stage voltage reduction circuit supplies power to the 5V system of the power-off delay device, and the 5V direct current is converted into 3.8V direct current through the second-stage voltage reduction circuit, and the 3.8V direct current output by the second-stage voltage reduction circuit supplies power to the 3.8V system of the power-off delay device; the 5V direct current is converted into 3.8V direct current through the low dropout linear regulator in the second-stage voltage reduction circuit.
[0045] The reliable drive circuit is the key of the power-off delay device, on the one hand, it ensures that the relay can act and reset reliably, on the other hand, the relay cannot be powered for a long time to save energy. Figure 4The hardware circuit diagram of the relay driving circuit is shown in the figure. The relay driving circuit includes the relay power-on driving circuit and the relay reset driving circuit. The relay power-on driving circuit is realized by hardware and does not need the signal control of the single-chip microcomputer.
[0046] The relay driving circuit is: the output of the first-stage voltage reduction circuit is connected to the connection point B through the current-limiting resistor R5, the capacitor C7, the first pin of the relay K, the anode of the diode D1 and the cathode of the diode D2, the connection point B is connected to the connection point A of the capacitor C7 and the resistor R6 and GND, the connection point A of the capacitor C7 and the resistor R6 is connected to the base of the transistor Q1, the collector of the transistor Q1, the 16th pin of the relay K and the anode of the diode D2 are connected, the emitter of the transistor Q1 is connected to GND, the cathode of the diode D1 is connected to the capacitor C8, the other end of the capacitor C8 is connected to GND, the connection point C of the cathode of the diode D1 and the capacitor C8 is connected to the second pin of the relay and the cathode of the diode D3, the 15th pin of the relay K is connected to the anode of the diode D3 and the collector of the transistor Q2, the emitter of the transistor Q2 is connected to GND, the base of the transistor Q2 is connected to the resistor R8 and the resistor R7, the other end of the resistor R8 is connected to GND, the other end of the resistor R7 is connected to the relay reset control signal, the fifth pin and the eighth pin of the relay K are the normally open pins, the ninth pin and the 12th pin of the relay K are the normally open pins, and the two groups of normally open pins are a group of delay normally open contacts and a group of delay normally closed contacts.
[0047] The relay power-on driving circuit is composed of resistors, capacitors and NPN transistors, and the principle is the RC charging circuit. The 5V direct current charges the capacitor C7 through the current-limiting resistor R5. In the power-on instant, there is no charge in the capacitor C7, which is equivalent to a short circuit. The potential of the connection point A is clamped at 0.7V by the equivalent transistor between the base and the emitter of the transistor Q1. At this time, the transistor Q1 is in the conducting state. The 5V direct current provides energy for the action coil of the relay. With the continuous rise of the voltage across the capacitor, the voltage of the connection point A continuously decreases until it approaches the ground potential voltage 0V. In the power-on process of the power-off delay device, the relay power-on driving circuit can provide a wide pulse voltage for the action coil of the relay, ensuring the reliable action of the relay. The voltage change curves of the connection point A and the connection point B are shown in the attached figure. In the power-on instant of the power-off delay device, a wide voltage pulse of about 25ms is provided for the action coil of the relay, ensuring the reliable action of the relay, and the width of the pulse can be adjusted by adjusting the size of the resistor R6 and the capacitor C7 in the relay power-on driving circuit. Figure 5
[0048] The relay reset drive circuit is controlled by an NPN transistor. When the set delay time is reached, the microcontroller controls the transistor Q2 to conduct for a period of time to ensure reliable reset of the relay.
[0049] Since the power-off delay device can support input power sources of two different forms of electrical energy, AC and DC, two power-off detection circuits are required if the input signal is detected directly. Therefore, it is sufficient to directly detect the output voltage of the AC / DC switching power supply U1 and the DC / DC switching power supply U2. The dynamic response of the switching power supply is very fast. After the input voltage, whether the AC power supply or the DC power supply, is disconnected, the output of the switching power supply will immediately be zero.
[0050] Attachment Figure 6 This is the hardware circuit diagram of the power-off detection circuit. It uses a Toshiba LTP187 photocoupler. The primary side of the photocoupler is connected to the 5V DC output of the first-stage step-down circuit, and the secondary side is connected to the 3.8V DC output of the second-stage step-down circuit. When the input power is on, the secondary side outputs a high-level signal. When the input power is off, the secondary side outputs a low-level signal. The microcontroller only needs to detect whether the secondary side output of the photocoupler is a high or low-level signal to determine whether the power-off delay device is in the power-on state or the power-off state. The curves of the photocoupler's secondary side output signal, 5V DC, and the microcontroller reset signal are shown in the attached figure. Figure 7 As shown, it can be seen that after the power-off delay device is powered off, the output signal of the secondary side of the optocoupler begins to change from high level to low level, and it takes about 250ms to change from high level to low level signal. The microcontroller needs to delay for 250ms after power off to recognize that the power-off delay device is powered off. The microcontroller has determined that the delay is within this range after multiple detections. Therefore, this part of time is subtracted from the microcontroller real-time clock delay program to improve the delay accuracy.
[0051] Attachment Figure 8 This is the hardware circuit diagram of the energy storage capacitor charging circuit, attached Figure 9 This is the hardware circuit diagram of the relay reset capacitor charging circuit. The output of the secondary step-down circuit is the charging power supply for the energy storage capacitor in the energy storage capacitor charging circuit. A diode D2 is connected in series in the energy storage capacitor charging circuit. When the input power is cut off, the diode D2 prevents the energy storage capacitor from reversely supplying power to the secondary step-down circuit. The output of the primary step-down circuit is the charging power supply for the reset capacitor in the relay reset capacitor charging circuit. A diode D1 is connected in series in the relay reset capacitor charging circuit. When the input power is cut off, the diode D1 prevents the reset capacitor from reversely supplying power to the primary step-down circuit. Figure 10For the charging voltage variation curve of the energy storage capacitor and the reset capacitor, it can be seen that the energy storage capacitor and the reset capacitor can reach 3.2V / 4.4V and 3.24V / 4.52V respectively after 150ms and 500ms of power-on, and the energy stored in the energy storage capacitor and the reset capacitor within 500ms can meet the power supply requirements of the power-off delay device for long-time work after power-off.
[0052] The single-chip microcomputer control circuit includes an M0 kernel single-chip microcomputer, a chip program download circuit, a reset circuit, a quartz crystal oscillator, an Figure 11 (a) is a hardware circuit diagram of the M0 kernel single-chip microcomputer, an Figure 11 (b) is a hardware circuit diagram of the chip program download circuit, an Figure 11 (c) is a hardware circuit diagram of the reset circuit, an Figure 11 (d) is a hardware circuit diagram of the quartz crystal oscillator. The M0 kernel single-chip microcomputer uses an STM32G031F6P6 low-power chip, and the main GPIO interface has perfect anti-static protection.
[0053] The power-off delay device is miniaturized and light-weighted, and based on this feature, the energy storage capacitor cannot select a large-capacity capacitor, so the stored energy is limited. After the power-off delay device is powered off, the power supply of the entire single-chip microcomputer control system comes from the energy stored in the energy storage capacitor. Therefore, the single-chip microcomputer runs in a low-power mode after the power-off delay device is powered off. This type of single-chip microcomputer has three low-power running modes, namely sleep mode, stop mode and standby mode. The sleep mode only closes the kernel and keeps the peripherals running. The stop mode closes all clocks and still has a large power consumption, so the standby mode is selected. In standby mode, the single-chip microcomputer closes the kernel power supply, but the real-time clock and backup registers still have power supply, which means that the counter of the real-time clock will not stop working, and the real-time clock can perform accurate timing. When the timing reaches the set delay time, the real-time clock wakes up the single-chip microcomputer, and the single-chip microcomputer sends a command to reset the relay. Figure 12 For the complete variation curve of the energy storage capacitor, the reset capacitor, the power-off detection signal and the reset control signal of the power-off delay device during work, an Figure 13 For the Figure 12 In the local enlarged view at time t A It can be seen that in a very short power-on time (500ms), after power-off, the energy stored in the energy storage capacitor and the reset capacitor can ensure the reliable and high-precision work of the power-off delay device for a long time.
[0054] The dial code delay setting circuit includes two 8421 BCD encoders, and the two encoders set the time base and the time multiple respectively. The final delay time is the product of the corresponding values of the two dials.
[0055] TheFigure 14 The figure is a schematic diagram of the appearance of the power-off delay device. A1 and A2 are two different forms of input power connection terminals, K1.1 and K1.2 are a group of delay normally closed contacts, and K2.1 and K2.2 are a group of delay normally open contacts.
[0056] The working process of the power-off delay device is as follows: when the input power is powered on, the relay power-on driving circuit provides power to the relay action coil through the output power of the first step-down circuit, the relay is momentarily actuated, the output power of the first step-down circuit charges the reset capacitor, and the output power of the second step-down circuit charges the energy storage capacitor. The delay time of the two encoders is set before or during power-on; when the input power is powered off, the energy storage capacitor provides power support for the power-off delay device without the need for an external auxiliary power supply. The single-chip microcomputer enters standby mode, calculates the delay time using the real-time clock function, and wakes up the single-chip microcomputer when the predetermined delay time is reached. The single-chip microcomputer sends a reset signal, and the relay reset driving circuit uses the energy stored in the reset capacitor to reset the relay. The use of a real-time clock and a low-power single-chip microcomputer with a wide voltage operating range can effectively reduce the power consumption of the power-off delay device and prolong the delay time of the power-off delay device. Without additional auxiliary power supply, the delay precision can be improved while reducing the cost and size of the power-off delay device, and the reliability of the equipment is improved.
[0057] The power-off delay device has the following advantages:
[0058] 1. High delay precision: The power-off delay device is based on high-precision real-time clock technology, combined with reliable power-off detection circuit and corresponding delay algorithm, with extremely high timing accuracy, ensuring the ultra-high delay precision of the power-off delay device.
[0059] 2. Long delay time: The power-off delay device stores enough energy in the energy storage capacitor during power-on, and after power-off, the single-chip microcomputer immediately enters standby mode, only the real-time clock is in working state, the rest of the peripherals are in power-down state, the single-chip microcomputer runs with extremely low power consumption, and the single-chip microcomputer is awakened only when the set delay time is reached. On the other hand, the power-off delay device uses a single-chip microcomputer with a wide voltage operating range, which can work in a wide voltage range.
[0060] 3. Wide power supply range: The power-off delay device supports AC 220V (85-265V) and DC 24V (18-36V) input power, and uses a two-stage step-down circuit, using high-efficiency switching power supply technology, the power-off delay device has a wide voltage input range.
[0061] 4. Relatively simple circuit design: The power-off delay device does not require an additional auxiliary power supply, and the circuit design is relatively simple, reducing the cost.
[0062] 5. Convenient delay setting: The power-off delay device uses two 8421BCD encoders to set the delay time. The configuration is simple and does not require in-depth knowledge of complex electronics or circuits. The operation is convenient, accurate and reliable.
[0063] 6. Strong versatility: The power-off delay device has the characteristics of high delay accuracy, long delay range, support for two voltage inputs, and small size. The device can be widely used in various equipment that require power-off delay or time control;
[0064] 7. High reliability: The power-off delay device adopts high-precision real-time clock technology, reliable energy storage devices and single-chip microcomputer, and the device provides high reliability and stability during operation.
Claims
1. A power-off delay device based on a high-precision real-time clock and without an auxiliary power supply, comprising a dual-coil magnetic latching relay and its control circuit. The dual-coil magnetic latching relay includes a set of delayed normally open contacts, a set of delayed normally closed contacts, an operating coil, and a reset coil. The device is characterized by: The control circuit includes a primary step-down circuit, a secondary step-down circuit, a power-off detection circuit, a dial delay setting circuit, an energy storage capacitor charging circuit, a relay reset capacitor charging circuit, a single-chip microcomputer control circuit, and a relay drive circuit. The relay drive circuit includes a relay power-on drive circuit and a relay reset drive circuit. The input power supply is connected to the primary step-down circuit, the primary step-down circuit is connected to the secondary step-down circuit, the power-off detection circuit, the relay power-on drive circuit, and the relay reset capacitor charging circuit, the secondary step-down circuit is connected to the energy storage capacitor charging circuit and the dial delay setting circuit, the energy storage capacitor charging circuit is connected to the single-chip microcomputer control circuit, the single-chip microcomputer control circuit is connected to the power-off detection circuit and the dial delay setting circuit, the relay reset drive circuit is connected to the single-chip microcomputer control circuit and the relay reset capacitor charging circuit, the relay power-on drive circuit controls the action coil, and the relay reset drive circuit controls the reset coil. At the moment the input power is energized, the delayed normally open contact is instantaneously closed and the delayed normally closed contact is instantaneously disconnected, and this state is maintained during the power-on period; when the input power is disconnected, the delay timing starts. When the set delay setting is reached, the delayed normally open contact is disconnected and the delayed normally closed contact is closed, and this state is maintained until the next power on and off.
2. The power-off delay device based on a high-precision real-time clock and without an auxiliary power supply according to claim 1, characterized in that: The input power supply is an AC power supply or a DC power supply, and the first-stage step-down circuit is an AC / DC switching power supply circuit or a DC / DC switching power supply circuit; The AC / DC switching power supply circuit is as follows: the AC power first passes through fuse F1, then through varistor MOV1, and is then delivered to EMI filter circuit 1. Inside EMI filter circuit 1, it passes through capacitor CX1, common-mode inductor L1, capacitor CY1, and capacitor CY2, and is finally delivered to the input of AC / DC switching power supply U1. The DC / DC switching power supply circuit is as follows: the DC power first passes through fuse F2, then through varistor MOV2 and gas discharge tube G1, and is then delivered to EMI filter circuit 2. Inside EMI filter circuit 2, it passes through common-mode inductor L2, capacitor CP1, and inductor LB1, and is finally delivered to the input of DC / DC switching power supply U2. The output of the AC / DC switching power supply U1 or the output of the DC / DC switching power supply U2 passes through a secondary step-down circuit, passes through a low voltage difference linear regulator in the secondary step-down circuit, and finally outputs a low voltage power.
3. The power-off delay device based on a high-precision real-time clock and without an auxiliary power supply according to claim 1, characterized in that: The relay drive circuit is as follows: the output of the first-stage step-down circuit is connected to the connection point B through the current limiting resistor R5, the capacitor C7, the 1st pin of the relay K, the anode of the diode D1, and the cathode of the diode D2. The connection point B is connected to the resistor R6 and GND through the capacitor C7. The connection point A of the capacitor C7 and the resistor R6 is connected to the base of the transistor Q1. The collector of the transistor Q1 is connected to the 16th pin of the relay K and the anode of the diode D2. The emitter of the transistor Q1 is connected to GND. The cathode of the diode D1 is connected to the 16th pin of the relay K and the anode of the diode D2. The cathode of diode D1 is connected to capacitor C8, the other end of capacitor C8 is connected to GND, the connection point C between the cathode of diode D1 and capacitor C8 is connected to the 2nd pin of relay and the cathode of diode D3, the 15th pin of relay K is connected to the anode of diode D3 and the collector of transistor Q2, the emitter of transistor Q2 is connected to GND, the base of transistor Q2 is connected to resistor R8 and resistor R7, the other end of resistor R8 is connected to GND, and the other end of resistor R7 is connected to the relay reset control signal.
4. The power-off delay device based on a high-precision real-time clock and without an auxiliary power supply according to claim 1, characterized in that: The power-off detection circuit includes a photocoupler. The primary side of the photocoupler is connected to the output of the first-stage step-down circuit, and the secondary side is connected to the output of the second-stage step-down circuit. When the input power is powered on, the secondary side outputs a high-level signal. When the input power is powered off, the secondary side outputs a low-level signal.
5. The power-off delay device based on a high-precision real-time clock and without an auxiliary power supply according to claim 1, characterized in that: The output of the secondary step-down circuit is the charging power supply for the energy storage capacitor in the energy storage capacitor charging circuit. A diode D2 is connected in series in the energy storage capacitor charging circuit. When the input power is cut off, the diode D2 prevents the energy storage capacitor from reversely supplying power to the secondary step-down circuit. The output of the primary step-down circuit is the charging power supply for the reset capacitor in the relay reset capacitor charging circuit. A diode D1 is connected in series in the relay reset capacitor charging circuit. When the input power is cut off, the diode D1 prevents the reset capacitor from reversely supplying power to the primary step-down circuit.
6. The power-off delay device based on a high-precision real-time clock and without an auxiliary power supply according to claim 1, characterized in that: The single-chip microcomputer control circuit includes an M0 core single-chip microcomputer, a chip program download circuit, a reset circuit, and a quartz crystal oscillator; after the input power is cut off, the M0 core single-chip microcomputer runs in standby mode, and the M0 core single-chip microcomputer is awakened when the real-time clock times to the set delay time, and the single-chip microcomputer sends a command to reset the relay.
7. The power-off delay device based on a high-precision real-time clock and without an auxiliary power supply according to claim 1, characterized in that: The DIP delay setting circuit includes two 8421BCD encoders, which set the time base and time multiplier respectively. The final delay time is the product of the two corresponding values.