Power grid uninterruptible power supply automatic switching system and method and driving circuit

Abstract

The invention discloses a power grid uninterruptible power supply automatic switching system and method and a driving circuit, and belongs to the technical field of power electronics, and the system comprises a power supply module which is used for providing electric energy for the system; the relay switch unit is used for controlling the on-off of commercial power input; the acceleration turn-off unit is used for accelerating turn-off of the relay switch unit; the circuit switching unit is used for switching the large-current driving loop into a small-current driving loop after a preset time is delayed; and the control module is used for outputting a high-level signal to control the circuit switching unit to switch the large-current driving loop to accelerate the closing of the relay switch unit, and outputting a low-level signal to control the acceleration turn-off unit to accelerate the turn-off of the relay switch unit. The delay switching driving design and the acceleration turn-off unit are adopted, the power supply hardware design can be greatly simplified, the power requirement of the auxiliary power supply module is reduced, meanwhile, the turn-off time of the relay is remarkably shortened, and the stability and reliability of the power grid uninterruptible power supply in the switching process are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to an automatic switching system, method and driving circuit for an uninterruptible power supply of a power grid. Background Art

[0002] When the mains power is lost, the energy storage inverter or uninterruptible power supply needs to quickly switch to the inverter mode to ensure uninterrupted power supply to the load. In this process, the most common challenge is that the shutdown time of the mains input relay generally exceeds 10 milliseconds, which seriously affects the power supply stability of the load. To solve this problem, the existing technology usually adopts two methods: one is to use an additional SCR (silicon-controlled rectifier) ​​circuit in parallel with the relay, but although this method can accelerate the switching transition, the drive circuit is complex, the materials are many, the cost is high, and the risk of failure is increased. Another way is to adopt a dual power drive strategy, that is, switch to a low-voltage power supply after the relay is closed. Although it can reduce the heating of the relay and the power supply burden of the auxiliary power supply, this approach also adds additional costs.

[0003] When the relay is driven with rated voltage, the heating of the internal coil will accelerate the aging of the insulation material and eventually cause the relay to fail. It is also normal that the power supply burden of the auxiliary power supply increases, which not only increases the design and cost of the system, but also affects the reliability of the system. Therefore, the existing technology usually adopts a dual power supply design, using high voltage at the initial stage of relay closing to ensure reliable opening and closing, and then switching to low voltage power supply to reduce the damage caused by high voltage to the relay, but this strategy is still a high-cost and complex design. Summary of the invention

[0004] To solve the above problems, the present invention provides an automatic switching system, method and driving circuit for an uninterruptible power supply for a power grid, which adopts a delayed switching driving design and an accelerated shutdown unit, can greatly simplify the power supply hardware design, reduce the power demand of the auxiliary power supply module, and significantly shorten the shutdown time of the relay, thereby ensuring the stability and reliability of the uninterruptible power supply for the power grid during the switching process.

[0005] The above objectives can be achieved through the following solutions: A power grid uninterruptible power supply automatic switching system comprises a power module, a switching module and a control module, wherein the switching module comprises a relay switch unit, an acceleration shutdown unit and a circuit switching unit; wherein the power module is electrically connected to the acceleration shutdown unit and the circuit switching unit respectively, and is used to provide power to the system; the relay switch unit is electrically connected to the acceleration shutdown unit and the circuit switching unit respectively, and is used to control the on and off of the mains input; the acceleration shutdown unit is electrically connected to the relay switch unit and the power module respectively, and is used to accelerate the shutdown of the relay switch unit; the circuit switching unit is electrically connected to the power module, the acceleration shutdown unit, and the relay switch unit respectively, and is used to switch a large current drive circuit to a small current drive circuit after a predetermined delay time; the control module is electrically connected to the circuit switching unit, and is used to output a high level signal to control the circuit switching unit to switch the large current drive circuit, and accelerate the closing of the relay switch unit; the control module is also electrically connected to the acceleration shutdown unit, and is used to output a low level signal to control the acceleration shutdown unit to accelerate the shutdown of the relay switch unit.

[0006] Optionally, the circuit switching unit includes: a loop control subunit and a loop switching subunit, the loop control subunit includes a resistor R1, a resistor R2 and a transistor Q1; wherein one end of the resistor R1 is electrically connected to the control module, the other end of the resistor R1 is respectively electrically connected to the base of the transistor Q1 and one end of the resistor R2, the other end of the resistor R2 is respectively electrically connected to the collector and the ground end of the transistor Q1, and the emitter of the transistor Q1 is electrically connected to the loop switching subunit.

[0007] Optionally, the loop switching subunit includes: a capacitor C1, a resistor R3 and a transistor Q2; wherein, one end of the capacitor C1 is electrically connected to the power module, the other end of the capacitor C1 is electrically connected to one end of the resistor R3, the other end of the resistor R3 is electrically connected to the collector of the transistor Q2, and the emitter of the transistor Q2 is electrically connected to the relay switch unit; the end of the resistor R3 not electrically connected to the capacitor C1 is electrically connected to the emitter of the transistor Q2, and the end of the resistor R3 electrically connected to the capacitor C1 is electrically connected to the base of the transistor Q2.

[0008] Optionally, the loop switching subunit further includes: a resistor R4; wherein one end of the resistor R4 is electrically connected to the collector of the transistor Q2, and the other end of the resistor R4 is electrically connected to the emitter of the transistor Q2.

[0009] Optionally, the accelerated shutdown unit includes a diode D1, a capacitor C2, a resistor R5 and a transistor Q3; wherein, the input end of the diode D1 is electrically connected to the power module, the output end of the diode D1 is electrically connected to one end of the capacitor C2, the other end of the capacitor C2 is electrically connected to one end of the resistor R5, and the other end of the resistor R5 is electrically connected to the ground end; the end of the capacitor C2 electrically connected to the diode D1 is electrically connected to the relay switch unit, the collector of the transistor Q3 is electrically connected to the power module, and the emitter of the transistor Q3 is electrically connected to the end where the capacitor C2 and the resistor R5 are electrically connected.

[0010] Optionally, the accelerated shutdown unit further includes: a resistor R6; wherein one end of the resistor R6 is electrically connected to the base of the transistor Q3, and the other end of the resistor R6 is electrically connected to the emitter of the transistor Q1.

[0011] Optionally, the relay switch unit includes: a relay switch K1; wherein one end of the relay switch K1 is electrically connected to the emitter of the transistor Q2, and the other end of the relay switch K1 is electrically connected to the capacitor C2.

[0012] Optionally, the relay switch unit further includes: a diode D2; wherein an input end of the diode D2 is electrically connected to the emitter of the transistor Q2, and an output end of the diode D2 is electrically connected to the capacitor C2.

[0013] Based on the same inventive concept, the present invention also provides a method for automatic switching of an uninterruptible power supply for a power grid, which is applied to any of the above-mentioned automatic switching systems for an uninterruptible power supply for a power grid, and the method includes: controlling a circuit switching unit to switch to a large current drive circuit through a high-level signal, so that the relay switch K1 is quickly closed; after a predetermined delay time, the large current drive circuit is automatically switched to a small current drive circuit to keep the relay switch K1 in a closed state; when it is necessary to turn off the relay switch K1, controlling an accelerated shutdown unit through a low-level signal to instantly reduce the drive level of the relay switch K1 to zero, thereby accelerating the shutdown time of the relay switch K1.

[0014] Based on the same inventive concept, the present invention further provides an automatic switching drive circuit for an uninterruptible power supply to a power grid, wherein the drive circuit comprises an automatic switching system for an uninterruptible power supply to a power grid as described in any one of the above.

[0015] Compared with the prior art, the present invention has the following advantages: 1. The present invention significantly shortens the shutdown time of the relay by integrating an accelerated shutdown circuit. When the power supply needs to be switched, the control module outputs a high-level signal, which is quickly switched to a high-current drive circuit through a circuit switching unit, so that the relay switch K1 is quickly closed; and when the relay switch K1 needs to be turned off, the control module outputs a low-level signal, and the accelerated shutdown unit instantly lowers the drive level of the relay switch K1 to zero, thereby achieving rapid shutdown; this design ensures stability and reliability in uninterruptible power supply applications; 2. The circuit switching unit can use a large current to ensure reliable opening and closing at the initial stage of relay closing, and then automatically switch to a small current drive circuit; this can not only keep the relay switch K1 in a closed state, but also reduce current consumption, prevent the internal coil of the relay switch unit from heating up, extend the service life of the equipment, and reduce the power supply burden of the auxiliary power supply; 3. The circuit structure adopted by the present invention is simpler. By integrating the circuit design of accelerated shutdown, the design of power supply hardware is greatly simplified, and the power demand of the auxiliary power supply module is reduced. This not only reduces the cost of the system, but also improves the reliability of the system; 4. Diode D2 and other protective elements are added to the relay switch unit; when the emitter voltage of transistor Q2 rises instantly, diode D2 can be quickly turned on, and the excess current is introduced into capacitor C2, thereby protecting transistor Q2 from damage. This design enhances the stability and safety of the system.

[0016] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 The present invention is a schematic structural diagram of an automatic switching system for an uninterruptible power supply to a power grid according to an embodiment of the present invention.

[0019] Figure 2 The invention is a circuit diagram of an automatic switching system for an uninterruptible power supply of a power grid according to an embodiment of the present invention.

[0020] Figure 3The present invention is a flowchart of an automatic switching method for an uninterruptible power supply of a power grid according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Reference Figure 1 An embodiment of the present invention proposes an automatic switching system for an uninterruptible power supply for a power grid, which adopts a delayed switching drive design and an accelerated shutdown unit, can greatly simplify the power supply hardware design, reduce the power demand of the auxiliary power supply module, and significantly shorten the shutdown time of the relay, thereby ensuring the stability and reliability of the uninterruptible power supply for the power grid during the switching process.

[0023] The system of this embodiment specifically includes: a power module, a switching module and a control module, wherein the switching module includes a relay switch unit, an acceleration shutdown unit and a circuit switching unit; wherein, A power module is electrically connected to the acceleration shutdown unit and the circuit switching unit respectively, and is used to provide power to the system; Specifically, Figure 2 As shown, the power module provides stable and reliable power for the entire system. The power module can be a high-performance DC power supply that can output sufficient current to drive the relay switch K1.

[0024] The relay switch unit is connected to the acceleration shutdown unit and the circuit switching unit respectively, and is used to control the on and off of the mains input; Specifically, the relay switch unit serves as a main switch element to control the on and off of the mains input circuit.

[0025] An accelerated shut-off unit, electrically connected to the relay switch unit and the power module, respectively, and used to accelerate the shut-off of the relay switch unit; Specifically, the accelerated shutdown unit accelerates the disconnection process of the relay under the action of a low-level signal; the accelerated shutdown unit may be a circuit composed of a fast-discharging diode and a capacitor, which can discharge quickly to accelerate the disconnection of the relay.

[0026] A circuit switching unit, electrically connected to the power module, the acceleration shutdown unit and the relay switch unit, respectively, for switching the high-current drive circuit to a low-current drive circuit after a predetermined delay time; Specifically, after the relay switch unit is closed, the circuit switching unit delays a predetermined time and switches to a small current drive circuit; the circuit switching unit can be a circuit composed of a MOSFET tube and a resistor, and switching between different current circuits is achieved by controlling the conduction and cutoff of the MOSFET tube.

[0027] The control module is electrically connected to the circuit switching unit and is used to output a high-level signal to control the circuit switching unit to switch the high-current drive circuit and accelerate the closing of the relay switch unit; the control module is also electrically connected to the acceleration shutdown unit and is used to output a low-level signal to control the acceleration shutdown unit to accelerate the shutdown of the relay switch unit.

[0028] Specifically, the control module is used to output high-level signals and low-level signals to control the circuit switching unit and the accelerated shutdown unit in the switching module to achieve rapid closing and reliable disconnection of the relay switch unit; the control module can be a microcontroller (MCU). When the relay switch unit needs to be closed, the control module outputs a high-level signal to control the circuit switching unit to switch to a large current drive circuit, so that the relay switch unit receives a large current and closes quickly. When the relay switch unit needs to be disconnected, the control module outputs a low-level signal to cause the accelerated shutdown unit to discharge quickly to accelerate the disconnection process of the relay switch unit.

[0029] Exemplarily, the control module detects the conditions that require closing the relay switch unit (such as an external signal trigger) and outputs a high-level signal; after receiving the high-level signal, the circuit switching unit switches to a high-current drive circuit; the high-current drive circuit provides sufficient current for the relay switch unit to close quickly; after a delay of a period of time (such as a few milliseconds to a few seconds), the circuit switching unit automatically switches to a low-current drive circuit; the low-current drive circuit maintains the closed state of the relay switch unit, while reducing the current to prevent the internal coil of the relay switch unit from heating up.

[0030] Exemplarily, the control module detects the conditions that require disconnecting the relay switch unit (such as external signal triggering) and outputs a low-level signal; after receiving the low-level signal, the accelerated shutdown unit quickly discharges and accelerates the disconnection process of the relay switch unit; after the relay switch unit is disconnected, the circuit switching unit remains in a small current drive loop state, waiting for the next closing operation; through the above working principle, the rapid closing and reliable disconnection of the relay switch unit are achieved, while the heating of the internal coil of the relay switch unit and the power supply burden of the power module are reduced, thereby improving the stability and reliability of the system.

[0031] Furthermore, if Figure 2 As shown, the circuit switching unit includes: a loop control subunit and a loop switching subunit, and the loop control subunit includes a resistor R1, a resistor R2 and a transistor Q1; wherein, One end of the resistor R1 is electrically connected to the control module, the other end of the resistor R1 is electrically connected to the base of the transistor Q1 and one end of the resistor R2, the other end of the resistor R2 is electrically connected to the collector and the ground of the transistor Q1, and the emitter of the transistor Q1 is electrically connected to the loop switching subunit.

[0032] Specifically, the loop control subunit is mainly composed of resistor R1, resistor R2 and transistor Q1. Resistor R1 plays the role of current limiting and voltage dividing. One end of it is electrically connected to the control module to receive the control signal from the control module; the other end of resistor R1 is electrically connected to the base of transistor Q1 and one end of resistor R2 at the same time, and the other end of resistor R2 is electrically connected to the collector of transistor Q1 and the ground terminal respectively, forming a basic common-emitter amplifier circuit.

[0033] Exemplarily, when the control module outputs a high-level signal, current flows into the base of the transistor Q1 through the resistor R1, causing the transistor Q1 to be saturated and turned on; at this time, the resistance between the emitter and the collector of the transistor Q1 is very small, which is equivalent to a closed switch, allowing current to pass through the loop switching sub-unit to trigger the loop switching action; when the control module outputs a low-level signal, the base current of the transistor Q1 is zero, and the transistor Q1 is cut off; at this time, the resistance between the emitter and the collector of the transistor Q1 is very large, which is equivalent to a disconnected switch, preventing current from passing through the loop switching sub-unit.

[0034] Furthermore, if Figure 2 As shown, the loop switching subunit includes: capacitor C1, resistor R3 and transistor Q2; wherein, One end of the capacitor C1 is electrically connected to the power module, the other end of the capacitor C1 is electrically connected to one end of the resistor R3, the other end of the resistor R3 is electrically connected to the collector of the transistor Q2, and the emitter of the transistor Q2 is electrically connected to the relay switch unit; One end of the resistor R3 that is not electrically connected to the capacitor C1 is electrically connected to the emitter of the transistor Q2 , and one end of the resistor R3 that is electrically connected to the capacitor C1 is electrically connected to the base of the transistor Q2 .

[0035] Specifically, capacitor C1 is used as an energy storage element to provide instantaneous current when the loop is switched to maintain the closed state of the relay or help the relay to disconnect quickly; resistor R3 is used as a current limiting resistor to protect transistor Q2 from damage caused by excessive current and participate in forming a bias circuit of transistor Q2; transistor Q2 is used as a switching element to control the closure of the relay according to the output signal of the loop control subunit (transmitted through transistor Q1).

[0036] Specifically, one end of the capacitor C1 is electrically connected to the power module to receive a stable DC voltage; the other end of the capacitor C1 is electrically connected to one end of the resistor R3 to form a discharge loop of the capacitor; the other end of the resistor R3 (the end not directly connected to the capacitor C1) is electrically connected to the collector of the transistor Q2; the emitter of the transistor Q2 is connected to the other end of the coil of the relay switch K1; the end of the resistor R3 connected to the capacitor C1 is also connected to the base of the transistor Q2 through a small resistor or directly.

[0037] Exemplarily, when the loop control subunit outputs a high-level signal (through transistor Q1), the base voltage of transistor Q2 increases, causing it to turn on; at this time, the power module provides a large current to the relay switch K1 through capacitor C1, resistor R3 and transistor Q2, causing it to close quickly. Capacitor C1 plays a role in smoothing the current and providing instantaneous energy.

[0038] Furthermore, if Figure 2 As shown, the loop switching subunit also includes: a resistor R4; wherein, One end of the resistor R4 is electrically connected to the collector of the transistor Q2 , and the other end of the resistor R4 is electrically connected to the emitter of the transistor Q2 .

[0039] Specifically, the resistor R4 is connected between the collector and emitter of the transistor Q2, providing an additional current path for the transistor Q2 to help discharge when it is cut off; one end of the resistor R4 is electrically connected to the collector of the transistor Q2, and the other end is electrically connected to the emitter of the transistor Q2, forming a discharge loop parallel to the transistor Q2.

[0040] Exemplarily, when transistor Q2 is turned on, the power module provides a large current to the relay through resistor R3, capacitor C1 (if capacitor C1 is being charged or fully charged at this time) and transistor Q2, so that it closes quickly; resistor R4 has little effect on the circuit at this time because most of the current flows through transistor Q2; transistor Q2 is turned off after a delay period, and if capacitor C1 has been charged, it may be discharged through the parallel circuit composed of resistor R3 and resistor R4; the presence of resistor R4 provides an additional discharge channel for capacitor C1, which helps to accelerate the discharge process of capacitor C1 and ensure that the voltage between the collector and emitter of transistor Q2 is quickly reduced to a safe level; when it is necessary to switch to a small current drive circuit, transistor Q2 is turned off and discharged through the parallel circuit composed of resistor R3 and resistor R4 to form a small current drive circuit; the small current drive circuit maintains the closed state of the relay switch unit, while reducing the current to prevent the internal coil of the relay switch unit from heating up.

[0041] Furthermore, if Figure 2 As shown, the accelerated shutdown unit includes a diode D1, a capacitor C2, a resistor R5 and a transistor Q3; wherein, The input end of the diode D1 is electrically connected to the power module, the output end of the diode D1 is electrically connected to one end of the capacitor C2, the other end of the capacitor C2 is electrically connected to one end of the resistor R5, and the other end of the resistor R5 is electrically connected to the ground end; One end of the capacitor C2 electrically connected to the diode D1 is electrically connected to the relay switch unit, the collector of the transistor Q3 is electrically connected to the power module, and the emitter of the transistor Q3 is electrically connected to one end of the capacitor C2 electrically connected to the resistor R5.

[0042] Specifically, the diode D1 can withstand the output voltage of the power module and has a sufficiently fast response time. Its main function is to conduct electricity in one direction to prevent the current from flowing in the opposite direction. The capacitor C2 can be an electrolytic capacitor with appropriate capacity, which is used to store charge and release it when needed to accelerate the shutdown process. The resistor R5 is used to limit the current and protect other components in the circuit.

[0043] Furthermore, if Figure 2 As shown, the accelerated shutdown unit also includes: a resistor R6; wherein, One end of the resistor R6 is electrically connected to the base of the transistor Q3 , and the other end of the resistor R6 is electrically connected to the emitter of the transistor Q1 .

[0044] Specifically, For example, when the relay needs to be closed, the transistor Q1 is turned on, and a high-level signal is sent to the base of the transistor Q3 through the resistor R6, so that the transistor Q3 is turned on; it provides a charging path for the storage capacitor C2 (usually an electrolytic capacitor); at this time, the negative end of the capacitor C2 (i.e., the end connected to the emitter of the transistor Q3) will be charged to the power module voltage; when the relay needs to be disconnected, the control module sends a low-level signal to turn off the transistor Q1 in the loop control subunit; at the same time, the transistor Q3 in the acceleration shutdown unit will also be turned off due to the change of the control signal; when the transistor Q3 is turned off When the power is stopped, capacitor C2 loses its charging path, and due to the characteristics of the capacitor, it will start to discharge through the relay coil and other possible discharge paths (such as resistor R5); since capacitor C2 has stored energy and is now required to discharge quickly, it will reduce its negative terminal voltage to zero level (or close to zero level) in a very short time; since the positive terminal of capacitor C2 is usually connected to the power module and the negative terminal voltage has been reduced to zero, the voltage difference across the coil of relay switch K1 is rapidly reduced to zero, causing the current in the relay coil to rapidly reduce to zero, thereby accelerating the rapid disconnection of relay switch K1.

[0045] Furthermore, if Figure 2 As shown, the relay switch unit includes: a relay switch K1; wherein, One end of the relay switch K1 is electrically connected to the emitter of the transistor Q2 , and the other end of the relay switch K1 is electrically connected to the capacitor C2 .

[0046] Specifically, one end of the relay switch K1 (assuming it is the end of the normally open contact) is connected to the emitter of the transistor Q2 through a wire; when the transistor Q2 is in the on state, its emitter will output a current, and this current will flow through the relay switch K1, so that the normally open contact of the relay switch K1 is closed; the other end of the relay switch K1 (the other end opposite to the normally open contact) is connected to the capacitor C2 through a wire; the capacitor C2 here plays a key role in the accelerated shutdown unit, and it is used to store and release electrical energy to achieve rapid shutdown of the relay.

[0047] For example, assuming that the uninterruptible power supply of the power grid needs to switch to the backup power supply, the control module will output a high-level signal to the circuit switching unit; after receiving the signal, the circuit switching unit will switch to a high-current drive circuit to turn on the transistor Q2; after the transistor Q2 is turned on, the current output by its emitter will flow through the relay switch K1, so that the normally open contact of K1 is closed, thereby connecting the backup power supply circuit; when the relay switch K1 needs to be turned off, the control module will output a low-level signal to the accelerated shutdown unit; after receiving the signal, the accelerated shutdown unit will control the transistor Q3 to be cut off, and the capacitor C2 will start to discharge; since the negative end of the capacitor C2 has been connected to the ground through the transistor Q3, its voltage will drop rapidly; and one end of the relay switch K1 is connected to the capacitor C2, so the drive level of K1 will also drop rapidly, thereby realizing the rapid shutdown of the relay.

[0048] Furthermore, if Figure 2 As shown, the relay switch unit also includes: a diode D2; wherein, The input end of the diode D2 is electrically connected to the emitter of the transistor Q2, and the output end of the diode D2 is electrically connected to the capacitor C2.

[0049] Specifically, the diode D2 mainly plays a protective role here; when the relay switch K1 is closed, if the emitter voltage of the transistor Q2 increases instantaneously due to some reason (such as power supply fluctuation, load mutation, etc.), the diode D2 can be quickly turned on to introduce the excess current into the capacitor C2, thereby avoiding the transistor Q2 from being damaged due to overvoltage; at the same time, the capacitor C2 can also play a role in smoothing voltage fluctuations, further protecting the stable operation of the circuit.

[0050] Exemplarily, when the system receives a signal that the mains power is off, the control module immediately outputs a high-level signal; the high-level signal activates transistor Q2 through the large current drive circuit of the circuit switching unit, and the collector-emitter path of transistor Q2 is turned on, driving the relay switch K1 to close quickly; after the relay switch K1 is closed, the system switches to the inverter mode to provide uninterrupted power supply to the load; after a delay of one end time, the transistor Q2 is cut off, and the current passes through the resistor R4 to form a small current drive circuit; the small current drive circuit maintains the closed state of the relay switch unit and reduces the current at the same time to prevent the internal coil of the relay switch unit from heating; during the operation of the system, if the emitter voltage of the transistor Q2 increases instantaneously, the diode D2 is quickly turned on, and the excess current is introduced into the capacitor C2 to protect the transistor Q2 from damage; when the relay switch K1 needs to be turned off, the control module outputs a low-level signal, and the drive level of the relay switch K1 is instantly pulled down to zero through the accelerated shutdown unit to achieve rapid shutdown.

[0051] Based on the same inventive concept, Figure 3 As shown, the present invention also provides a method for automatically switching an uninterruptible power supply of a power grid, which is applied to the aforementioned automatic switching system for an uninterruptible power supply of a power grid, and the method comprises: The circuit switching unit is controlled by a high-level signal to switch to a high-current drive circuit, so that the relay switch K1 is quickly closed; After the preset delay time, the high current drive circuit automatically switches to the low current drive circuit, keeping the relay switch K1 in the closed state; When the relay switch K1 needs to be turned off, the driving level of the relay switch K1 is instantly lowered to zero by controlling the acceleration turning-off unit through a low-level signal, thereby accelerating the turning-off time of the relay switch K1.

[0052] Based on the same inventive concept, the present invention also provides an automatic switching driving circuit for an uninterruptible power supply for a power grid, and the driving circuit includes an automatic switching system for an uninterruptible power supply for a power grid as described above.

[0053] It should be noted that the electrical connection between the above-mentioned units does not necessarily mean the connection between the lines. The indirect connection method can be applied to the embodiments of the present invention as long as the purpose of the present invention is achieved. The above are only exemplary embodiments of the present invention and cannot limit the scope of the present invention.

[0054] That is, any equivalent changes and modifications made according to the teachings of the present invention are still within the scope of the present invention. After considering the disclosure of the specification and the truth of practice, those skilled in the art will easily think of other embodiments of the present invention. This application is intended to cover any variation, use or adaptive change of the present invention, which follows the general principles of the present invention and includes common knowledge or customary technical means in the art that are not described in the present invention.

Claims

1. An automatic switching system for uninterruptible power supply of a power grid, characterized in that: The system comprises: a power supply module, a switching module and a control module, wherein the switching module comprises a relay switch unit, an acceleration shutdown unit and a circuit switching unit; wherein, The power supply module is electrically connected to the acceleration shutdown unit and the circuit switching unit respectively, and is used to provide power to the system; The relay switch unit is connected to the acceleration shutdown unit and the circuit switching unit respectively, and is used to control the on and off of the mains input; The accelerated shut-off unit is electrically connected to the relay switch unit and the power module respectively, and is used to accelerate the shut-off of the relay switch unit; The circuit switching unit is electrically connected to the power module, the acceleration shutdown unit and the relay switch unit respectively, and is used to switch the high-current drive circuit to a low-current drive circuit after a predetermined delay time; The control module is electrically connected to the circuit switching unit and is used to output a high-level signal to control the circuit switching unit to switch the high-current drive circuit and accelerate the closing of the relay switch unit; the control module is also electrically connected to the accelerated shutdown unit and is used to output a low-level signal to control the accelerated shutdown unit to accelerate the shutdown of the relay switch unit.

2. The automatic switching system for uninterruptible power supply of power grid according to claim 1, characterized in that: The circuit switching unit includes: a loop control subunit and a loop switching subunit, wherein the loop control subunit includes a resistor R1, a resistor R2 and a transistor Q1; wherein, One end of the resistor R1 is electrically connected to the control module, the other end of the resistor R1 is electrically connected to the base of the transistor Q1 and one end of the resistor R2, the other end of the resistor R2 is electrically connected to the collector and the ground of the transistor Q1, and the emitter of the transistor Q1 is electrically connected to the loop switching subunit.

3. The automatic switching system for uninterruptible power supply of power grid according to claim 2, characterized in that: The loop switching subunit includes: capacitor C1, resistor R3 and transistor Q2; wherein, One end of the capacitor C1 is electrically connected to the power module, the other end of the capacitor C1 is electrically connected to one end of the resistor R3, the other end of the resistor R3 is electrically connected to the collector of the transistor Q2, and the emitter of the transistor Q2 is electrically connected to the relay switch unit; One end of the resistor R3 that is not electrically connected to the capacitor C1 is electrically connected to the emitter of the transistor Q2 , and one end of the resistor R3 that is electrically connected to the capacitor C1 is electrically connected to the base of the transistor Q2 .

4. The automatic switching system for uninterruptible power supply of power grid according to claim 3, characterized in that: The loop switching subunit further includes: a resistor R4; wherein, One end of the resistor R4 is electrically connected to the collector of the transistor Q2 , and the other end of the resistor R4 is electrically connected to the emitter of the transistor Q2 .

5. The automatic switching system for uninterruptible power supply of power grid according to claim 4, characterized in that: The accelerated shutdown unit includes a diode D1, a capacitor C2, a resistor R5 and a transistor Q3; wherein, The input end of the diode D1 is electrically connected to the power module, the output end of the diode D1 is electrically connected to one end of the capacitor C2, the other end of the capacitor C2 is electrically connected to one end of the resistor R5, and the other end of the resistor R5 is electrically connected to the ground end; One end of the capacitor C2 electrically connected to the diode D1 is electrically connected to the relay switch unit, the collector of the transistor Q3 is electrically connected to the power module, and the emitter of the transistor Q3 is electrically connected to one end of the capacitor C2 electrically connected to the resistor R5.

6. The automatic switching system for uninterruptible power supply of power grid according to claim 5, characterized in that: The accelerated shutdown unit further includes a resistor R6; wherein: One end of the resistor R6 is electrically connected to the base of the transistor Q3 , and the other end of the resistor R6 is electrically connected to the emitter of the transistor Q1 .

7. The automatic switching system for uninterruptible power supply of power grid according to claim 5, characterized in that: The relay switch unit comprises: a relay switch K1; wherein, One end of the relay switch K1 is electrically connected to the emitter of the transistor Q2 , and the other end of the relay switch K1 is electrically connected to the capacitor C2 .

8. The automatic switching system for uninterruptible power supply of a power grid according to claim 5, characterized in that: The relay switch unit further includes: a diode D2; wherein, The input end of the diode D2 is electrically connected to the emitter of the transistor Q2, and the output end of the diode D2 is electrically connected to the capacitor C2.

9. A method for automatically switching an uninterruptible power supply to a power grid, applied to the automatic switching system for an uninterruptible power supply to a power grid as claimed in any one of claims 1 to 8, characterized in that: The method comprises: The circuit switching unit is controlled by a high-level signal to switch to a high-current drive circuit, so that the relay switch K1 is quickly closed; After a predetermined delay time, the high current drive circuit is automatically switched to a low current drive circuit, and the relay switch K1 is kept in a closed state; When the relay switch K1 needs to be turned off, the driving level of the relay switch K1 is instantly lowered to zero by controlling the acceleration turning-off unit through a low-level signal, thereby accelerating the turning-off time of the relay switch K1.

10. An automatic switching drive circuit for an uninterruptible power supply of a power grid, characterized in that: The driving circuit includes the automatic switching system for uninterruptible power supply of a power grid as described in any one of claims 1-8.

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