Localized AC and DC power supply isolation output switching device
By combining hardware and software interlocking design with protection circuits, the problems of interlocking reliability and device lifespan in existing AC and DC power switching devices have been solved. This has enabled domestically produced, low-cost, and highly reliable power switching, meeting the power supply continuity and power quality requirements in critical applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- AVIC EAST CHINA OPTOELECTRONICS CO LTD
- Filing Date
- 2026-01-29
- Publication Date
- 2026-05-08
AI Technical Summary
Existing AC and DC power switching devices suffer from problems such as insufficient interlock reliability, significant impact on devices during switching, reliance on imported core components leading to high costs, and unstable transient output during switching, making it difficult to meet the power supply continuity and power quality requirements in critical applications.
It adopts a dual interlock design combining hardware contact interlock and software program interlock, and combines RC absorption circuit and freewheeling diode to protect relay contacts. It uses domestic microcontroller and high-power relay to achieve seamless switching and stable power supply of AC and DC power, and is equipped with status display and alarm module.
It achieves highly reliable and low-cost power switching, avoids power short circuits, extends device life, ensures the continuity and stability of power supply, has the advantage of domestic production, and supports remote monitoring and protection functions.
Smart Images
Figure CN122001071A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of power management technology, specifically relating to a domestically produced AC and DC power isolation output switching device. Background Technology
[0002] In critical applications requiring continuous power supply (such as military equipment, communication base stations, and industrial control systems), a dual-redundant power supply system consisting of an AC main power supply and a DC backup power supply is often used. When the main power supply fails, it must automatically switch to the backup power supply to ensure uninterrupted power supply to the load.
[0003] Currently, devices that achieve automatic switching between dual power supplies mainly suffer from the following technical defects: Insufficient interlock reliability and short-circuit risk: Common switching devices often employ a single interlock logic (such as hardware interlock relying solely on normally closed relay contacts, or interlock relying solely on control software). A single interlock method poses a significant risk of both main and backup power relays conducting simultaneously if hardware contacts stick together or the software program malfunctions, potentially leading to a short circuit and equipment burnout.
[0004] The switching process places a significant impact on devices and shortens their lifespan: When a relay disconnects an inductive or capacitive load, an electric arc or back electromotive force is generated between the contacts. Existing designs often lack specific protection, resulting in severe erosion of the relay contacts, susceptibility of the coil drive circuit to high-voltage surges, and reduced device reliability and lifespan.
[0005] The reliance on imported core components leads to high costs and significant supply chain risks: High-reliability automatic switching devices often use imported dedicated switching chips, relays, and processors, resulting in high costs and challenges to supply chain security and self-control in certain fields.
[0006] Unstable transient output during switching: Some solutions have excessively long switching times, or voltage dips and glitches occur during switching, failing to meet the stringent power quality requirements of precision loads. Simple circuit designs cannot provide continuous energy buffering for downstream loads during switching.
[0007] Therefore, there is an urgent need for an AC / DC power isolation switching device that is cost-effective, highly reliable, quick to switch, and suitable for domestic production environments. Summary of the Invention
[0008] The present invention aims to provide a device for switching between AC 220V and DC 24V isolated outputs, avoiding the incompatibility between AC and DC outputs, and enabling seamless switching when AC and DC power are supplied simultaneously.
[0009] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: An AC / DC power isolation output switching device, comprising: The power input and preprocessing module is used to connect to the AC main power supply and the DC backup power supply, and to perform preprocessing protection for the two power supplies respectively. The power detection and control module is used to collect the electrical parameters of the AC main power supply and DC backup power supply in real time, determine the power supply status based on the collection results, and output control signals. The relay isolation switching module includes two relays corresponding to the main power supply branch and the backup power supply branch, respectively, and realizes physical isolation and automatic switching of AC and DC power supplies based on the control signal. The output adapter and protection module is used to provide corresponding output branches according to the load type and to protect the output power supply. The two relays are interlocked to ensure that they do not conduct at the same time.
[0010] In a preferred embodiment, the interlock design includes hardware interlocks and software interlocks; The hardware interlock is achieved by connecting the normally closed contact of the first relay in series with the coil circuit of the second relay, and the normally closed contact of the second relay in series with the coil circuit of the first relay. The software interlock ensures that the control signals of the two relays are mutually exclusive through the control program.
[0011] In a preferred embodiment, the power input and preprocessing module includes: The AC input branch consists of an air switch, an EMI filter module, and a varistor connected in series. The DC input branch consists of a DC fuse and a DC filter capacitor connected in series.
[0012] In a preferred embodiment, the power detection and control module includes a microcontroller that collects the voltage and frequency of the AC main power supply and the voltage and current of the DC backup power supply in real time; when a main power supply fault is detected, a switching control signal is output within 10ms; when the main power supply returns to normal, a switching control signal is output after a delay of 3-5s.
[0013] In a preferred embodiment, the relay isolation switching module further includes a contact protection circuit, which includes: An RC snubber circuit with relay contacts connected in parallel in the AC main power supply branch; And / or, a freewheeling diode connected in reverse parallel across the relay coil of the DC backup power supply branch.
[0014] In a preferred embodiment, the output adaptation and protection module includes: AC load output branch, series overcurrent protection relay; And / or, in the DC load output branch, a transient suppression diode is connected in parallel and a current sampling resistor is connected in series.
[0015] In a preferred embodiment, a status display and alarm module is also included to display the power status and to issue an alarm in case of power failure.
[0016] In a preferred embodiment, the status display and alarm module includes LED indicator lights and a buzzer, and can be expanded with a communication interface to upload fault information to the monitoring system.
[0017] In a preferred embodiment, a capacitor connected in parallel after the output stage is also included to maintain power supply to the load during power switching.
[0018] In a preferred embodiment, the power detection circuit of the power detection and control module includes: The AC detection branch converts AC power into DC signals and transmits them to the microcontroller. The DC detection branch divides the DC power supply and connects it to the ADC pin of the microcontroller, and collects the DC current through a current detection chip.
[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. Achieves ultra-high reliability interlocking isolation, completely eliminating power short circuits: Through a unique dual interlocking mechanism combining "hardware contact interlocking" and "software program interlocking," even if one interlocking method fails, the other can still ensure that the relays in the main and backup power supply branches do not conduct simultaneously. This provides redundancy protection at both the physical and logical levels, reducing the risk of accidental simultaneous conduction to an extremely low level, and significantly improving system security.
[0020] 2. Targeted protection for switching devices significantly extends device lifespan: For the AC branch, an RC snubber circuit is connected in parallel with the relay contacts to effectively suppress arcing during disconnection and reduce contact erosion; for the DC branch, a freewheeling diode is connected in reverse parallel across the coil to eliminate the impact of reverse electromotive force on the drive circuit. This differentiated protection design significantly improves the electrical life of the relay and the reliability of the entire device.
[0021] 3. Meets the requirements of domestic production, with low cost and easy implementation: The core control of the device adopts a domestic general-purpose microcontroller, and the execution element is a domestic high-power relay. Combined with a simple and efficient circuit design, it breaks the monopoly of foreign special-purpose chips, effectively reduces costs while ensuring high performance, and improves supply chain security and independent controllability.
[0022] 4. Achieves truly fast, seamless, and smooth switching: Based on a microcontroller-based real-time detection algorithm, it can complete switching within 10ms after detecting a main power supply failure, far exceeding the response time of a typical relay. During switching, the energy storage capacitor after the output stage discharges to maintain voltage stability; simultaneously, a 3-5 second delay switching logic after the main power supply is restored avoids frequent malfunctions caused by power fluctuations, ensuring the continuity and stability of the load power supply.
[0023] 5. Possesses comprehensive monitoring and protection functions with a high degree of intelligence: It integrates status display and fault audible and visual alarms, and can be expanded with a remote communication interface to realize local and remote real-time monitoring of the device status. The output branches are equipped with multiple protections such as overcurrent and overvoltage (TVS), further ensuring the safety of the load equipment.
[0024] The present invention will be explained in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description
[0025] Figure 1 This is a schematic diagram of the device of the present invention; Figure 2 This is a schematic diagram of the relay isolation switching module of the present invention. Detailed Implementation
[0026] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be given below with reference to the accompanying drawings, which illustrate several embodiments of the present invention. However, the present invention can be implemented in different forms and is not limited to the embodiments described in the text. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete.
[0027] Figure 1 The diagram shows the switching device module, which includes an AC input branch connected to a 220V AC main power supply. A series air switch provides overload and short-circuit protection, an EMI filter suppresses interference, and a varistor provides surge protection to prevent damage to the core components of the device. Another DC input branch is connected to a 24V or 12V DC backup power supply. A series DC fuse provides short-circuit protection, and a DC filter capacitor stabilizes the DC voltage and filters out ripple.
[0028] The power detection and control module uses a domestic manufacturer's Qinheng microcontroller (such as CH32F103) as its core to collect the voltage and frequency of the AC main power supply and the voltage and current of the DC backup power supply in real time, to determine whether the power supply is supplying power normally and to determine the current power supply status.
[0029] Normal state: When the main power supply is on, the control module outputs a level that disconnects the backup power branch relay and connects the main power branch relay, allowing the load to be powered by the AC main power supply. Fault state: Upon detecting a main power supply fault, the control module switches its output level within 10ms, disconnecting the main power branch relay and connecting the backup power branch relay, seamlessly switching the load to DC backup power supply. Recovery state: After the main power supply returns to normal, the control module delays for 3-5 seconds (to avoid accidental switching) before switching the relays again, switching the load back to main power supply and simultaneously disconnecting the backup power branch to reduce energy consumption.
[0030] The relay isolation switching module adopts Figure 2 The high-power electromagnetic relays, Hongfa HF18FF-G / A220-3Z53GD, correspond to the main power supply branch and the backup power supply branch respectively, realizing physical isolation and switching of AC and DC power supplies. Relay coil power supply: An independent 12V DC power supply is used (powered by the main power supply through a rectifier and voltage regulator module; in case of main power failure, it switches to the backup power supply through a step-down module), ensuring stable relay operation; Relay contact protection: The AC branch relay contacts are connected in parallel with an RC absorption circuit (resistor + capacitor) to suppress the arc generated when the contacts open, extending contact life; the DC branch relay contacts are connected in parallel with a freewheeling diode to eliminate the back electromotive force when the coil is de-energized; Switching logic: The dual relays adopt an "interlock design" (interlocking via microcontroller I / O ports + hardware contact interlocking) to avoid short circuits caused by simultaneous conduction of the main power supply and backup power supply, providing double protection for switching safety.
[0031] The output adapter and protection module designs output branches according to the load type (AC / DC), taking into account both adaptability and safety: AC load output: The main power relay contacts are directly connected to the load, and an overcurrent protection relay is connected in series. When the load current exceeds the rated value, the output is automatically cut off to protect the load and the device; DC load output: The backup power relay contacts are connected to the load, or the main power supply is converted to DC by a rectifier bridge and voltage regulator module. A transient voltage suppressor diode (TVS) is connected in parallel at the output terminal to resist voltage spikes, and a current sampling resistor is connected in series to work with the control module to realize overcurrent alarm and power failure protection.
[0032] Status display and alarm module Status display: The power status is displayed in real time via LED indicator lights (green light for normal main power, yellow light for normal backup power, and red light for normal load power supply), providing intuitive feedback on the device's operating status.
[0033] Fault Alarm: When the main power supply or backup power supply fails, the control module triggers a buzzer-based audible and visual alarm. It can also be expanded with an RS485 communication interface to upload fault information to the monitoring system for convenient remote monitoring.
[0034] Core Circuit Design 1. Power Supply Detection Circuit AC Detection: 220V AC power is converted to 12V DC through a step-down transformer (220V→12V), rectifier bridge, filter capacitor, and voltage regulator chip, and supplied to the voltage detection chip. The chip collects the voltage signal and transmits it to the microcontroller. The microcontroller calculates the actual AC voltage and determines whether it is normal. DC Detection: 24V or 12V DC power is divided by a step-down resistor (down to the microcontroller ADC sampling range of 0-3.3V) and connected to the microcontroller ADC pin. At the same time, the DC current is collected by the current detection chip. This dual monitoring of the DC power supply status avoids undervoltage and overcurrent.
[0035] 2. Relay Interlock Switching Circuit Hardware Interlock: The normally closed contact of the main power relay K1 is connected in series in the coil circuit of the backup power relay K2, and the normally closed contact of K2 is connected in series in the coil circuit of K1. When K1 is on, its normally closed contact is open, and the K2 coil cannot be energized; the same applies to the reverse, preventing both relays from being on simultaneously. Software Interlock: The microcontroller's IO1 controls the K1 coil to drive the transistor, and IO2 controls the K2 coil to drive the transistor. The program sets the logic: when IO1 outputs a high level, IO2 is forced to output a low level, and vice versa. This double interlock ensures safety.
[0036] 3. Contact protection circuit AC branch RC absorption circuit: A resistor (100Ω / 2W) and a capacitor (0.1μF / 400V) are connected in series and in parallel across the K1 contact to absorb the arc when the contact is opened, reduce contact wear, and extend the service life of the relay; DC branch freewheeling diode: The diode is connected in reverse parallel across the K2 coil, with the diode anode connected to the negative terminal of the coil and the cathode connected to the positive terminal of the coil. When the coil is de-energized, the reverse electromotive force forms a circuit through the diode, preventing the drive transistor from being damaged.
[0037] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. An AC and DC power supply isolation output switching device, characterized in that, include: The power input and preprocessing module is used to connect to the AC main power supply and the DC backup power supply, and to perform preprocessing protection on the two power supplies respectively. The power detection and control module is used to collect the electrical parameters of the AC main power supply and DC backup power supply in real time, determine the power supply status based on the collection results, and output control signals. The relay isolation switching module includes two relays corresponding to the main power supply branch and the backup power supply branch, respectively, and realizes physical isolation and automatic switching of AC and DC power supplies based on the control signal. The output adapter and protection module is used to provide corresponding output branches according to the load type and to protect the output power supply. The two relays are interlocked to ensure that they do not conduct at the same time.
2. The AC and DC power supply isolation output switching device according to claim 1, characterized in that, The interlock design includes hardware interlocks and software interlocks; The hardware interlock is achieved by connecting the normally closed contact of the first relay in series with the coil circuit of the second relay, and the normally closed contact of the second relay in series with the coil circuit of the first relay. The software interlock ensures that the control signals of the two relays are mutually exclusive through the control program.
3. The AC and DC power supply isolation output switching device according to claim 1, characterized in that, The power input and preprocessing module includes: The AC input branch consists of an air switch, an EMI filter module, and a varistor connected in series. The DC input branch consists of a DC fuse and a DC filter capacitor connected in series.
4. The AC and DC power supply isolation output switching device according to claim 1, characterized in that, The power detection and control module includes a microcontroller that collects the voltage and frequency of the AC main power supply and the voltage and current of the DC backup power supply in real time. When a main power supply fault is detected, a switching control signal is output within 10ms. When the main power supply returns to normal, a switching control signal is output after a delay of 3-5s.
5. The AC and DC power supply isolation output switching device according to claim 1, characterized in that, The relay isolation switching module further includes a contact protection circuit, which includes: An RC snubber circuit with relay contacts connected in parallel in the AC main power supply branch; And / or, a freewheeling diode connected in reverse parallel across the relay coil of the DC backup power supply branch.
6. The AC and DC power supply isolation output switching device according to claim 1, characterized in that, The output adaptation and protection module includes: AC load output branch, series overcurrent protection relay; And / or, in the DC load output branch, a transient suppression diode is connected in parallel and a current sampling resistor is connected in series.
7. The AC and DC power supply isolation output switching device according to claim 1, characterized in that, It also includes a status display and alarm module, which displays the power status and alarms when the power fails.
8. The AC and DC power supply isolation output switching device according to claim 7, characterized in that, The status display and alarm module includes LED indicators and a buzzer, and can be expanded with a communication interface to upload fault information to the monitoring system.
9. The AC and DC power supply isolation output switching device according to claim 1, characterized in that, It also includes a capacitor connected in parallel after the output stage to maintain power supply to the load during power switching.
10. The AC and DC power supply isolation output switching device according to claim 4, characterized in that, The power detection circuit of the power detection and control module includes: The AC detection branch converts AC power into DC signals and transmits them to the microcontroller. The DC detection branch divides the DC power supply and connects it to the ADC pin of the microcontroller, and collects the DC current through a current detection chip.