A non-isolated AC / DC dual-purpose seamless switching LED constant voltage driving power supply circuit

Abstract

The application relates to the technical field of lighting power supply, and particularly discloses a non-isolated AC / DC dual-purpose seamless switching LED constant-voltage driving power supply circuit which comprises a commercial power input rectification filtering module, a non-isolated voltage reduction main constant-voltage module, a battery charging and discharging management module, an electronic seamless switching module and a lithium battery multiple protection module; the non-isolated voltage reduction main constant-voltage module is electrically connected with the commercial power input rectification filtering module, the battery charging and discharging management module and the electronic seamless switching module respectively; and the lithium battery multiple protection module and the electronic seamless switching module are electrically connected with the battery charging and discharging management module. The circuit design of the commercial power supply path and the lithium battery emergency discharge path shares a main power loop and a voltage sampling network, non-isolated voltage reduction main constant-voltage modules are matched with electronic seamless switching modules to realize non-contact seamless switching, the lamps do not flicker and do not extinguish in the whole process, the circuit anti-surge and anti-power grid fluctuation ability are improved, and the overall operation stability is improved.

Description

Technical Field

[0001] This invention relates to the field of lighting power supply technology, and in particular to a non-isolated AC / DC dual-use LED constant voltage drive power supply circuit with seamless switching. Background Technology

[0002] With the rapid development of LED lighting technology, its high efficiency, energy saving, and long lifespan have led to its widespread application globally. To drive LEDs, a dedicated LED driver power supply is needed to provide stable voltage or current. When a power outage occurs, the driver power supply will not receive power, causing the LED lighting fixtures it drives to go out and cease providing illumination. In public places such as shopping malls, office buildings, and hospitals, emergency lighting is needed to guide evacuation during power outages. For home users, complete darkness after a power outage also brings many inconveniences.

[0003] To cope with power outages, some LED emergency drivers with backup batteries have emerged in the existing technology. These power supplies typically use mains power to power the LEDs and charge the backup battery when the mains power is normal; when the mains power fails, they automatically switch to the backup battery to power the LEDs, thus providing emergency lighting.

[0004] However, existing emergency drive power supplies mostly employ dual-circuit non-isolated emergency drives, requiring the construction of two independent power circuits. This results in inconsistent output voltages between the two circuits, leading to fluctuations in light brightness and flickering of LED strips. Furthermore, existing emergency drive power supplies often use mechanical or electromagnetic relays for power switching, which introduces mechanical contact issues, jitter, and delays. This makes LED lights prone to blackouts and flickering, failing to meet the requirements for uninterrupted lighting in fire emergency lighting. Additionally, there is a risk of relay aging and failure, and contact oxidation. Therefore, it is necessary to further improve the existing technology. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a non-isolated AC / DC dual-use LED constant voltage drive power supply circuit that addresses the above-mentioned deficiencies of the prior art. The circuit adopts a design in which the AC power supply path and the lithium battery emergency discharge path share a main power circuit and voltage sampling network. Through the non-isolated step-down main constant voltage module and the electronic seamless switching module, contactless seamless switching is achieved, and the lamp is flicker-free and does not turn off throughout the process. At the same time, the circuit’s surge resistance and grid fluctuation resistance are improved, and the overall operational stability is enhanced.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A non-isolated AC / DC dual-use LED constant voltage driver power supply circuit includes an AC input rectification and filtering module, a non-isolated step-down main constant voltage module, a battery charge / discharge management module, an electronic seamless switching module, and a lithium battery multi-protection module. The non-isolated step-down main constant voltage module is electrically connected to the AC input rectification and filtering module, the battery charge / discharge management module, and the electronic seamless switching module, respectively. The lithium battery multi-protection module and the electronic seamless switching module are both electrically connected to the battery charge / discharge management module.

[0007] Preferably, the non-isolated step-down constant voltage module includes a non-isolated constant voltage and constant current control chip U2, a MOSFET Q2, a rectifier bridge DB1, a transformer T2, and a transformer TX1. The MOSFET Q2 is connected to the rectifier bridge DB1 and the non-isolated constant voltage and constant current control chip U2, and the transformer T2 is connected to the non-isolated constant voltage and constant current control chip U2 and the transformer TX1.

[0008] Preferably, the mains input rectifier and filter module includes a fuse FU, a varistor VR1, an inductor L1, a filter capacitor CX1, and an inductor L2. The varistor VR1 is connected to the fuse FU and the inductor L1, the filter capacitor CX1 is connected to the inductor L1 and the inductor L2, and the inductor L2 is connected to the rectifier bridge DB1.

[0009] Preferably, the battery charging and discharging management module includes a power driver IC chip U3, a voltage regulator chip U6, a Zener diode ZD2, a Zener diode ZD3, a Zener diode ZD4, and a Zener diode ZD5. The power driver IC chip U3 is connected to the rectifier bridge DB1, the voltage regulator chip U6, the Zener diode ZD2, the Zener diode ZD3, the Zener diode ZD4, and the Zener diode ZD5, respectively.

[0010] Preferably, the electronic seamless switching module includes an inductor L3, a voltage detection and control chip U4, and a MOSFET Q3. The voltage detection and control chip U4 is connected to the inductor L3, the MOSFET Q3, and the transformer TX1, respectively. The inductor L3 is connected to the rectifier bridge DB1.

[0011] Preferably, the lithium battery multi-protection module includes battery BAT1, voltage regulator chip U5 and battery BAT2, the voltage regulator chip U5 is connected to the power driver IC chip U3 and battery BAT1 respectively, and the voltage regulator chip U6 is connected to battery BAT2.

[0012] By adopting the above technical solution, the present invention provides a non-isolated AC / DC dual-use seamless switching LED constant voltage driver power supply circuit, which has the following beneficial effects: The non-isolated step-down main constant voltage module in the LED constant voltage driver power supply circuit is electrically connected to the mains input rectification and filtering module, the battery charge and discharge management module, and the electronic seamless switching module, respectively. The lithium battery multi-protection module and the electronic seamless switching module are both electrically connected to the battery charge and discharge management module. Unlike the traditional dual-circuit non-isolated emergency drive, the present invention adopts a single-channel non-isolated step-down power circuit reuse design, sharing the same step-down constant voltage main control chip, the same power MOSFET, and the same freewheeling inductor for both normal mains power operation and battery emergency discharge modes. Using the same set of voltage divider sampling resistors eliminates the need for two independent power circuits, completely resolving issues such as inconsistent output voltage between dual circuits, fluctuations in light brightness, and LED strip flicker. The circuit design utilizes a shared main power circuit and voltage sampling network for both the mains power supply path and the lithium battery emergency discharge path. Through a non-isolated step-down main constant voltage module combined with an electronic seamless switching module, contactless seamless switching is achieved. There are no mechanical contacts, no jitter, and no delay throughout the process, preventing LED lights from blacking out or flickering. This meets the requirement for uninterrupted lighting in fire emergency lighting while mitigating the risks of relay aging and contact oxidation. Furthermore, it enhances the circuit's surge and grid fluctuation resistance, improving overall operational stability. Attached Figure Description

[0013] Figure 1 This is the circuit schematic diagram of the present invention. Detailed Implementation

[0014] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0015] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0016] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0017] like Figure 1 As shown, this non-isolated AC / DC dual-use LED constant voltage driver power supply circuit includes a mains input rectification and filtering module, a non-isolated step-down main constant voltage module, a battery charge / discharge management module, an electronic seamless switching module, and a lithium battery multi-protection module. The non-isolated step-down main constant voltage module is electrically connected to the mains input rectification and filtering module, the battery charge / discharge management module, and the electronic seamless switching module, respectively. The lithium battery multi-protection module and the electronic seamless switching module are both electrically connected to the battery charge / discharge management module. It can be understood that this invention is a fully non-isolated step-down LED constant voltage driver power supply circuit, without an isolation transformer, optocoupler isolation devices, or an isolated high-voltage circuit. The overall circuit is divided into five modules: a mains input rectification and filtering module, a non-isolated step-down main constant voltage module, a battery charge / discharge management module, an electronic seamless switching module, and a lithium battery multi-protection module. Mains power supply and battery emergency power supply completely reuse a single non-isolated step-down main power circuit, belonging to the category of low-cost non-isolated mains lighting + power outage battery emergency dual-mode constant voltage driver power supply technology.

[0018] Specifically, the non-isolated buck main constant voltage module includes a non-isolated constant voltage and constant current control chip U2, a MOSFET Q2, a rectifier bridge DB1, a transformer T2, and a transformer TX1. The MOSFET Q2 is connected to both the rectifier bridge DB1 and the non-isolated constant voltage and constant current control chip U2, and the transformer T2 is connected to both the non-isolated constant voltage and constant current control chip U2 and the transformer TX1. It is understood that the non-isolated constant voltage and constant current control chip U2 uses a BP2519 chip, which helps the circuit achieve stable voltage and current output. Unlike traditional dual-loop non-isolated emergency drives, this invention adopts a single-channel non-isolated buck power loop reuse design. Both the normal mains power operation and battery emergency discharge modes share the same buck constant voltage main control chip, the same power MOSFET, the same freewheeling inductor, and the same set of voltage divider sampling resistors, eliminating the need to build two independent power circuits. Its working logic is as follows: Mains mode: After rectification and filtering, the AC mains power outputs high-voltage DC, which is directly connected to the non-isolated step-down main circuit. After step-down and voltage regulation, a constant voltage is output to drive the LED strip / LED module. Simultaneously, the main circuit draws power from the voltage divider to provide a small current trickle charge for the downstream lithium battery. Emergency mode: After a mains power failure, the lithium battery outputs low-voltage DC, which is reversed and connected to the original non-isolated step-down main circuit. The step-down inductor, power switch, and voltage divider sampling circuit are reused to boost and regulate the voltage to the rated output voltage, continuously driving the LED load with a constant voltage. Compared to traditional dual non-isolated circuit solutions, this completely solves the problems of inconsistent output voltage between the two circuits, fluctuations in light brightness, and LED strip flicker.

[0019] Specifically, the mains input rectifier and filter module includes a fuse FU, a varistor VR1, an inductor L1, a filter capacitor CX1, and an inductor L2. The varistor VR1 is connected to both the fuse FU and the inductor L1. The filter capacitor CX1 is connected to both the inductor L1 and the inductor L2. The inductor L2 is connected to the rectifier bridge DB1. Understandably, to address the inherent shortcomings of non-isolated circuits—lack of transformer isolation and weak surge protection—a fuse, varistor, and RC discharge circuit are added to the mains input terminal. This improves the ability to suppress mains surges and voltage spikes without increasing isolation devices or costs. Simultaneously, the addition of an input differential-mode filter capacitor reduces conducted interference from the non-isolated circuit itself, meeting the basic EMC requirements for residential lighting fixtures.

[0020] Specifically, the battery charge and discharge management module includes a power driver IC chip U3, a voltage regulator chip U6, a Zener diode ZD2, a Zener diode ZD3, a Zener diode ZD4, and a Zener diode ZD5. The power driver IC chip U3 is connected to the rectifier bridge DB1, the voltage regulator chip U6, the Zener diode ZD2, the Zener diode ZD3, the Zener diode ZD4, and the Zener diode ZD5. The lithium battery multi-protection module includes a battery BAT1, a voltage regulator chip U5, and a battery BAT2. The voltage regulator chip U5 is connected to the power driver IC chip U3 and the battery BAT1, and the voltage regulator chip U6 is connected to the battery BAT2. Understandably, the power driver IC chip U3 uses the QW288M chip, and the voltage regulator chips U5 and U6 both use the QW3001 chip. To address the operating characteristics of the low-voltage battery side in non-isolated circuits, a dedicated battery protection chip is used to achieve comprehensive protection for the lithium battery. All protection circuits are integrated on the driver board, eliminating the need for an external protection board: 1. Battery overcharge protection: Automatically cuts off charging when the charging voltage reaches 4.2V to prevent battery overcharging and bulging. 2. Battery over-discharge protection: Automatically locks the discharge circuit when the discharge voltage is below 2.5V to prevent deep battery depletion; 3. Discharge overcurrent protection: Quickly shuts off the discharge switch when the emergency discharge current exceeds the limit; 4. Output short circuit protection: The power circuit is shut off instantly when the LED load is short-circuited to protect the power supply and battery; Battery reverse connection protection: An anti-reverse connection MOSFET is added so that the circuit will not be burned if the positive and negative terminals of the battery are installed in reverse.

[0021] Specifically, the electronic seamless switching module includes an inductor L3, a voltage detection and control chip U4, and a MOSFET Q3. The voltage detection and control chip U4 is connected to the inductor L3, the MOSFET Q3, and the transformer TX1, respectively. The inductor L3 is connected to the rectifier bridge DB1. Understandably, the voltage detection control chip U4 uses the QW2021 chip, a dedicated voltage detection control chip. This invention eliminates the electromagnetic relay of the traditional solution, and uses this dedicated voltage detection control chip in conjunction with a MOS electronic switch to build a switching circuit to detect the bus voltage after mains rectification in real time. When the mains power is normal: the bus voltage is within the threshold range, the electronic switch shuts off the battery discharge path, the battery stops supplying power, the circuit operates in mains lighting mode, and the trickle charging circuit is activated to replenish power. 2. When the mains power fails: the bus voltage drops rapidly, the voltage detection chip immediately triggers the electronic switch to conduct, the battery connects to the main power circuit, and the entire switching time is ≤0.7ms. There are no mechanical contacts, no jitter, and no delay throughout the process, and the LED lights will not experience blackouts or flickering, meeting the requirements for uninterrupted lighting in fire emergency lighting, while avoiding the risk of relay aging failure and contact oxidation.

[0022] In practical applications, AC power is input into the circuit. The fuse FU acts as the first line of defense, rapidly melting and cutting off the power supply in the event of severe overcurrent or short circuit. Varistors (VR1, VR2) are connected in parallel to the input line; when subjected to instantaneous high voltage such as lightning strikes or power surges, their resistance rapidly decreases, discharging most of the energy to ground and protecting subsequent circuits. EMI... Filtering: A filter network composed of common-mode inductors, safety capacitors, and Y capacitors rigorously filters the input power supply for electromagnetic interference, ensuring that the power supply complies with electromagnetic compatibility (EMC) standards, is neither affected by external interference nor generates external interference. Rectification: The filtered AC power enters the rectifier bridge and is converted into pulsating DC power. Output Filtering: The rectified DC power enters the output filter stage, where an LC filter network composed of one or more large-capacity electrolytic capacitors (CAP1, CAP3) and inductors performs smooth filtering. The purpose of this step is to minimize the ripple and noise of the output voltage, ultimately obtaining a very stable, clean DC power supply that meets the load requirements. Overcurrent Protection: The output current is monitored by detecting the voltage drop across the sampling resistor connected in series in the circuit. When the current exceeds the set value, the protection circuit activates, reducing the PWM. The power supply can be shut off by adjusting the duty cycle of the signal or directly cutting off the power until the fault is cleared; Overvoltage protection: Monitors the output voltage. When the voltage rises abnormally for some reason (such as a feedback loop fault) and exceeds the safety threshold, the protection circuit quickly cuts off the output to prevent damage to the load equipment; Undervoltage protection: When the input voltage is lower than the minimum voltage required for normal operation of the power supply, the power supply will stop working or enter a low-power mode to avoid instability or damage caused by working in an undervoltage state; Overtemperature protection: Monitors the temperature inside the power supply (especially the power components) through a built-in temperature sensor. When the temperature is too high, the power supply will automatically reduce the output power (derating operation) or shut down completely to protect the components from burning out due to overheating.

[0023] Understandably, this invention is rationally designed and uniquely constructed, possessing the following advantages: 1. It eliminates mechanical relays, employing a purely electronic switch to achieve millisecond-level seamless switching during mains power outages, ensuring the lamp remains flicker-free and uninterrupted throughout operation; 2. It integrates a unified lithium battery protection circuit, providing comprehensive protection against overcharging, over-discharging, overcurrent, short circuits, and reverse connection, extending the lithium battery's lifespan; 3. The same voltage sampling circuit is reused for both mains power mode and battery emergency mode, ensuring completely consistent LED output voltage and brightness in both operating modes, making it suitable for voltage-sensitive LED strip loads; 4. The non-isolated front-end protection circuit is optimized, enhancing the circuit's surge and grid fluctuation resistance capabilities, improving overall operational stability while retaining the low-cost advantages of non-isolated operation.

[0024] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A non-isolated AC / DC dual-use LED constant voltage drive power supply circuit, characterized in that: It includes an AC power input rectification and filtering module, a non-isolated step-down main constant voltage module, a battery charge and discharge management module, an electronic seamless switching module, and a lithium battery multi-protection module. The non-isolated step-down main constant voltage module is electrically connected to the AC power input rectification and filtering module, the battery charge and discharge management module, and the electronic seamless switching module, respectively. The lithium battery multi-protection module and the electronic seamless switching module are both electrically connected to the battery charge and discharge management module.

2. The non-isolated AC / DC dual-use seamless switching LED constant voltage drive power supply circuit according to claim 1, characterized in that: The non-isolated step-down constant voltage module includes a non-isolated constant voltage and constant current control chip U2, a MOSFET Q2, a rectifier bridge DB1, a transformer T2, and a transformer TX1. The MOSFET Q2 is connected to the rectifier bridge DB1 and the non-isolated constant voltage and constant current control chip U2, and the transformer T2 is connected to the non-isolated constant voltage and constant current control chip U2 and the transformer TX1.

3. The non-isolated AC / DC dual-use seamless switching LED constant voltage drive power supply circuit according to claim 2, characterized in that: The mains input rectifier and filter module includes a fuse FU, a varistor VR1, an inductor L1, a filter capacitor CX1, and an inductor L2. The varistor VR1 is connected to the fuse FU and the inductor L1, the filter capacitor CX1 is connected to the inductor L1 and the inductor L2, and the inductor L2 is connected to the rectifier bridge DB1.

4. The non-isolated AC / DC dual-use seamless switching LED constant voltage drive power supply circuit according to claim 2, characterized in that: The battery charging and discharging management module includes a power driver IC chip U3, a voltage regulator chip U6, a Zener diode ZD2, a Zener diode ZD3, a Zener diode ZD4, and a Zener diode ZD5. The power driver IC chip U3 is connected to the rectifier bridge DB1, the voltage regulator chip U6, the Zener diodes ZD2, ZD3, ZD4, and ZD5, respectively.

5. The non-isolated AC / DC dual-use seamless switching LED constant voltage drive power supply circuit according to claim 2, characterized in that: The electronic seamless switching module includes an inductor L3, a voltage detection and control chip U4, and a MOSFET Q3. The voltage detection and control chip U4 is connected to the inductor L3, the MOSFET Q3, and the transformer TX1, respectively. The inductor L3 is connected to the rectifier bridge DB1.

6. The non-isolated AC / DC dual-use seamless switching LED constant voltage drive power supply circuit according to claim 4, characterized in that: The lithium battery multi-protection module includes battery BAT1, voltage regulator chip U5 and battery BAT2. The voltage regulator chip U5 is connected to the power driver IC chip U3 and battery BAT1 respectively, and the voltage regulator chip U6 is connected to battery BAT2.

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