Overvoltage protection circuit and non-isolated switching power supply

Abstract

The invention provides an overvoltage protection circuit and a non-isolated switching power supply, and relates to the technical field of switching power supplies. The non-isolated switching power supply comprises a load, a power supply and at least one energy storage inductor. The overvoltage protection circuit comprises a control module, an overvoltage detection module and a switch module, wherein the switch module at least comprises a switch unit. The overvoltage detection module is connected with the output end of the load and the control module and is used for detecting the output voltage of the load; the control module is further connected with the control end of the switch unit. Wherein the control module comprises a plurality of working states; when the control module judges that the output voltage exceeds a first preset threshold value, the control module is in a first working state and sends a first control signal to the switch unit, so that the switch unit is switched on, and the power supply is short-circuited. On the basis that the structural size and the manufacturing cost of the non-isolated switching power supply are not increased, the problem of overvoltage at the output end caused by direct connection between the input source and the load can be avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of switching power supply, in particular to a kind of overvoltage protection circuit and non-isolated switching power supply. BACKGROUND

[0002] In prior art, non-isolated DC-DC topology structure is as a simplified DC-DC converter circuit, compared with isolated DC-DC topology structure, it does not contain isolation transformer, but is directly connected between power supply and load, and input source and load share a current path, to convert the required output DC voltage from input DC voltage, while controlling the flow direction and size of current through the turn-on and turn-off of switch tube, to realize the conversion of voltage.

[0003] Due to the limitation of structure, non-isolated DC-DC topology structure is often set in low-power non-isolated switching power supply, although it has the advantages of simple structure, high efficiency and low cost, but also has some limitations. For example, due to the absence of isolation transformer, the above-mentioned non-isolated switching power supply is prone to electromagnetic interference; or due to the fact that input source and load share a current path, the switch tube in non-isolated DC-DC topology structure may be damaged during operation, resulting in direct connection between input source and load, and overvoltage at output terminal. The technical personnel usually set an overvoltage protection circuit, such as voltage stabilizing diode, overvoltage protection chip, etc. in the above-mentioned non-isolated switching power supply, to cut off the power supply or suppress the voltage in time when overvoltage occurs, however, this scheme will increase the structure size and manufacturing cost of non-isolated switching power supply, and for switching power supply with high power density requirement, there is no extra space for adding an independent overvoltage protection circuit.

[0004] Therefore, there is an urgent need for an overvoltage protection circuit, which can avoid the problem of direct connection between input source and load and overvoltage at output terminal without increasing the structure size and manufacturing cost of non-isolated switching power supply. SUMMARY

[0005] The purpose of the present application is to provide an overvoltage protection circuit and non-isolated switching power supply, which can avoid the problem of direct connection between input source and load and overvoltage at output terminal without increasing the structure size and manufacturing cost of non-isolated switching power supply.

[0006] Embodiments of the present application can be implemented as follows:

[0007] In a first aspect, the present application provides an overvoltage protection circuit applied to a non-isolated switching power supply, wherein the non-isolated switching power supply comprises a load, a power supply, and at least one energy storage inductor; the overvoltage protection circuit comprises a control module, an overvoltage detection module, and a switching module; the switching module comprises at least one switching unit, a first end of the switching unit is connected with the power supply, a second end of the switching unit is connected with an input end of the load through the energy storage inductor, and a third end of the switching unit is grounded.

[0008] The overvoltage detection module is connected with an output end of the load and the control module, and is configured to detect an output voltage of the load.

[0009] The control module is further connected with a control end of the switching unit; wherein the control module comprises multiple working states.

[0010] When the control module determines that the output voltage exceeds a first preset threshold, the control module is in a first working state, sends a first control signal to the switching unit, so as to make the switching unit conductive and short-circuit the power supply.

[0011] Preferably, the switching unit comprises a first switching component and a second switching component; a first end of the first switching component is connected with the power supply; a second end of the first switching component is connected with a first end of the second switching component and a first end of the energy storage inductor respectively; a second end of the energy storage inductor is connected with the input end of the load; a second end of the second switching component is grounded; control ends of the first switching component and the second switching component are connected with the control module.

[0012] When the control module determines that the output voltage exceeds the first preset threshold, the control module is in the first working state, sends the first control signal to the first switching component and the second switching component respectively, the first switching component is conductive, the second switching component is conductive, and the power supply is short-circuited.

[0013] Preferably, when the number of the switching units is multiple, the number of the energy storage inductors is the same as the number of the switching units, and the overvoltage protection circuit further comprises at least one resonance module; wherein each of the switching units is connected in parallel through one of the resonance modules and is connected with the input end of the load through one of the energy storage inductors.

[0014] Preferably, when the switch module comprises a first switch unit and a second switch unit, and the resonance module comprises a resonance capacitor, a resonance inductor and an excitation inductor, a first end of the resonance capacitor is connected to a third end of a first switch component in the first switch unit, a second end of the resonance capacitor is connected to a first end of the resonance inductor, a second end of the resonance inductor is connected to a first end of the excitation inductor, and a second end of the excitation inductor is connected to a third end of a first switch component in the second switch unit.

[0015] Preferably, when the switch module comprises a first switch unit and a second switch unit, and the non-isolated switching power supply comprises a first energy storage inductor and a second energy storage inductor, the first switch component in the first switch unit comprises a first switch tube and a second switch tube, and the first switch component in the second switch unit comprises a third switch tube and a fourth switch tube.

[0016] The first end of the first switch tube and the first end of the third switch tube are connected to the power supply, the second end of the first switch tube is connected to the first end of the resonance module and the first end of the second switch tube, the second end of the second switch tube is connected to the first end of the first energy storage inductor, the second end of the third switch tube is connected to the second end of the resonance module and the first end of the fourth switch tube, the second end of the fourth switch tube is connected to the first end of the second energy storage inductor, and the second end of the first energy storage inductor and the second end of the second energy storage inductor are connected to the input end of the load.

[0017] Preferably, the control module is further configured to, when the output voltage exceeds the second preset threshold value and is less than the first preset threshold value, be in a second working state, and send a second control signal to the first switch component and the second switch component respectively, so that the first switch component is turned off and the second switch component is turned off.

[0018] Preferably, the overvoltage protection circuit further comprises a shunt module, and the shunt module is connected in parallel with the load.

[0019] Preferably, the shunt module comprises a fifth switch tube and a first inductor, a first end of the first inductor is connected to the output end of the energy storage inductor, a second end of the first inductor is connected to a first end of the fifth switch tube, a second end of the fifth switch tube is connected to the output end of the load, and a control end of the fifth switch tube is connected to the control module.

[0020] When the control module determines that the output voltage exceeds the first preset threshold value, the control module is in a first working state, and sends a first control signal to the switch unit and the fifth switch tube respectively, so that the switch unit and the fifth switch tube are turned on.

[0021] Preferably, the control module is further configured to, when the control module determines that the output voltage is less than the second preset threshold, enter a third working state and send a third control signal to the switching unit, so that the switching unit turns on or off according to the timing corresponding to the third control signal, and converts the output voltage of the power supply into the required output voltage; wherein, the first preset threshold is greater than the second preset threshold.

[0022] In a second aspect, the present invention also provides a non-isolated switching power supply, including a load, a power supply, at least one energy storage inductor, and an overvoltage protection circuit as described in any one of the first aspects above.

[0023] The beneficial effects of the embodiments of the present invention include, for example:

[0024] This invention provides an overvoltage protection circuit and a non-isolated switching power supply, wherein the overvoltage protection circuit is applied to a non-isolated switching power supply. The non-isolated switching power supply includes a load, a power supply, and at least one energy storage inductor. The overvoltage protection circuit includes a control module, an overvoltage detection module, and a switching module. The switching module includes at least one switching unit; the first terminal of the switching unit is connected to the power supply; the second terminal of the switching unit is connected to the input terminal of the load through the energy storage inductor; and the third terminal of the switching unit is grounded. The overvoltage detection module is connected to the output terminal of the load and the control module, and is used to detect the output voltage of the load. The control module is also connected to the control terminal of the switching unit; wherein the control module includes multiple operating states; when the control module determines that the output voltage exceeds a first preset threshold, the control module is in a first operating state and sends a first control signal to the switching unit to turn on the switching unit and short-circuit the power supply. This invention can avoid the problem of overvoltage at the output terminal caused by direct connection between the input source and the load without increasing the structural size and manufacturing cost of the non-isolated switching power supply. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is one of the structural schematic diagrams of an overvoltage protection circuit provided by the present invention;

[0027] Figure 2 A second schematic diagram of an overvoltage protection circuit provided by the present invention;

[0028] Figure 3A third schematic diagram of an overvoltage protection circuit provided by the present invention;

[0029] Figure 4 This is one of the structural schematic diagrams of the switching unit in this invention;

[0030] Figure 5 This is a schematic diagram showing the connection between the switching unit and the harmonic module in this invention;

[0031] Figure 6 This is a schematic diagram of the circuit structure of the harmonic module in this invention;

[0032] Figure 7 One of the circuit structure diagrams of an overvoltage protection circuit provided by the present invention;

[0033] Figure 8 This is a schematic diagram of the third control signal in this invention;

[0034] Figure 9 The fourth schematic diagram of an overvoltage protection circuit provided by the present invention;

[0035] Figure 10 This is a circuit diagram of the current shunt module in this invention;

[0036] Figure 11 A second schematic diagram of the circuit structure of an overvoltage protection circuit provided by the present invention;

[0037] Figure 12 This is a schematic diagram of a non-isolated switching power supply provided by the present invention.

[0038] Icons: 100 - Non-isolated switching power supply; 101 - Overvoltage protection circuit; 102 - Load; 103 - Power supply; 104 - Energy storage inductor; 201 - Control module; 202 - Overvoltage detection module; 203 - Switching module; 204 - Switching unit; 205 - Resonant module; 206 - Shunt module; 301 - First switching assembly; 302 - Second switching assembly; Cr - Resonant capacitor; Lm - Magnetizing inductor; Lr - Resonant inductor; Np - Secondary winding; Q1 - First switch; Q2 - Second switch; Q3 - Third switch; Q4 - Fourth switch; Ns1_1 - First energy storage inductor; Ns2_1 - Second energy storage inductor; SR2 - Fifth switch; Ns2_2 - First inductor; Ns1_2 - Second inductor; SR1 - Sixth switch; SR3 - Seventh switch; SR4 - Eighth switch; Cout - Output filter capacitor; Cin - Input filter capacitor. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0041] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0042] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0043] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0044] It should be noted that, where there is no conflict, the features in the embodiments of the present invention can be combined with each other.

[0045] As described in the background section, non-isolated DC-DC topologies do not include an isolation transformer, and their input source and load share a single current path to convert the input DC voltage into the required output DC voltage. The direction and magnitude of the current are controlled by the switching transistor, thereby achieving voltage conversion. However, the absence of an isolation transformer in a non-isolated DC-DC topology increases the probability of transistor failure during operation, leading to a direct connection between the input source and load, resulting in overvoltage at the output. To avoid overvoltage, engineers typically add an overvoltage protection device to promptly cut off the power supply or suppress the voltage in case of overvoltage. Examples include Zener diodes and overvoltage protection chips. However, such methods often increase the design and manufacturing costs of the switching power supply, especially for high-power-density switching power supplies, where there is limited space for additional overvoltage protection circuits or even power-off devices. Furthermore, the aforementioned optimization methods require additional protection devices to prevent power supply failures from damaging the load.

[0046] Based on this, the present invention provides an overvoltage protection scheme that eliminates the need for additional overvoltage protection circuits or devices in the power supply module. This avoids the problem of overvoltage at the output terminal caused by direct connection between the input source and the load, without increasing the structural size and manufacturing cost of the non-isolated switching power supply. Furthermore, it is applicable to switching power supplies with high power density.

[0047] The above overvoltage protection scheme will be described in detail below.

[0048] Firstly, please refer to Figure 1 This invention provides an overvoltage protection circuit 101 applied to a non-isolated switching power supply 100. The non-isolated switching power supply 100 includes a load 102, a power supply 103, and at least one energy storage inductor 104. The overvoltage protection circuit 101 includes a control module 201, an overvoltage detection module 202, and a switching module 203. The switching module 203 includes at least one switching unit 204. The first end of the switching unit 204 is connected to the power supply 103. The second end of the switching unit 204 is connected to the input end of the load 102 through the energy storage inductor 104. The third end of the switching unit 204 is grounded.

[0049] Continue to refer to Figure 1The overvoltage detection module 202 is connected to the output terminal of the load 102 and the control module 201, and is used to detect the output voltage of the load 102. The control module 201 is also connected to the control terminal of the switching unit 204. The control module 201 includes multiple working states. When the control module 201 determines that the output voltage exceeds a first preset threshold, the control module 201 is in the first working state and sends a first control signal to the switching unit 204 to turn on the switching unit 204 and short-circuit the power supply 103.

[0050] In this embodiment, when the control module 201 determines that the output voltage exceeds a first preset threshold, the control module 201 is in a first working state. At this time, the control module 201 can send a first control signal to the switching unit 204 to turn on the switching unit 204. Since the first end of the switching unit 204 is connected to the power supply 103, and the second end of the switching unit 204 is connected to the input end of the load 102 through the energy storage inductor 104, the switching unit 204 at the input end of the non-isolated switching power supply 100 is fully turned on, the power supply 103 is short-circuited, and the input voltage cannot be transmitted to the output end. This continues until the fuse of the switching unit 204 or the power supply 103 blows, thereby protecting the load 102 connected to the output end.

[0051] In another possible implementation, in this embodiment, the switching unit 204 can also be in a normal state, where the control module 201 determines that the output voltage is at the output state corresponding to the normal threshold. At this time, the control module 201 is in a normal operating state and can send a third control signal to the switching unit 204. This third control signal causes the switching unit 204 to turn on or off according to a timing sequence, so as to normally convert the input DC voltage into the required output DC voltage. Thus, the direction and magnitude of the current flow can be controlled by turning the switching unit 204 on and off, thereby achieving voltage conversion. In one possible implementation, the normal threshold is a multiple of the second preset threshold and the first preset threshold.

[0052] Based on this, the overvoltage protection circuit provided by the present invention can avoid the problem of overvoltage at the output terminal caused by direct connection between the input source and the load without increasing the structural size and manufacturing cost of the non-isolated switching power supply.

[0053] Please refer to Figure 2In this embodiment, the switching unit 204 includes a first switching component 301 and a second switching component 302. The first end of the first switching component 301 is connected to the power supply 103; the second end of the first switching component 301 is connected to the first end of the second switching component 302 and the first end of the energy storage inductor 104, respectively; the second end of the energy storage inductor 104 is connected to the input end of the load 102; the second end of the second switching component 302 is grounded; the control ends of both the first switching component 301 and the second switching component 302 are connected to the control module 201.

[0054] When the control module determines that the output voltage exceeds the first preset threshold, the control module is in the first working state. At this time, the control module sends the first control signal to the first switch component and the second switch component respectively. The first switch component is turned on and the second switch component is turned on to short-circuit the power supply.

[0055] In one possible implementation, this first preset threshold is a multiple of the normal threshold, for example, 150% of the normal threshold. That is, when the output voltage is greater than 150% of the normal threshold, the control module switches to the first working state and sends the first control signal to the first switch component and the second switch component respectively to turn on the first switch component and the second switch component. At this time, all switch units are turned on, and the power supply is short-circuited.

[0056] In this embodiment, the control module is also used to, when the output voltage exceeds the second preset threshold and is less than the first preset threshold, be in a second working state and send a second control signal to the first switch component and the second switch component respectively, so that the first switch component is turned off and the second switch component is turned off.

[0057] This second preset threshold is a multiple of the normal threshold, for example, 120% of the normal threshold. That is, when the output voltage is greater than 120% of the normal threshold but less than 150% of the normal threshold, the control module switches to the second working state and sends a second control signal to the first switch component and the second switch component respectively to turn off the first switch component and the second switch component. At this time, all switch units are disconnected.

[0058] Please see Figure 3 When there are multiple switching units 204, the number of energy storage inductors 104 is the same as the number of switching units 204, and the switching units 204 are connected in parallel. The circuit branch is formed by the sequential connection of the power supply 103, any switching unit 204, energy storage inductor 104 and load 102.

[0059] In this embodiment, to avoid mutual interference between electrical signals of each branch, please refer to [link / reference needed]. Figure 4The overvoltage protection circuit 101 also includes at least one resonant module 205. The resonant module 205 is disposed between two adjacent switching units 204, such that if the number of switching units 204 is n (a positive integer), then the corresponding number of resonant modules 205 is n-1, and the number of circuit branches is n. Each switching unit 204 is connected in parallel through a resonant module 205 and connected to the input terminal of the load 102 through an energy storage inductor 104.

[0060] In one possible implementation, please refer to Figure 5 The switching unit 204 with serial number N=1 and the switching unit 204 with serial number N=2 are connected through the resonant module 205 with serial number M=1. The switching unit 204 with serial number N=1 is connected to the load 102 through the energy storage inductor 104 with serial number L=1; the switching unit 204 with serial number N=2 is connected to the load 102 through the energy storage inductor 104 with serial number L=2. N, M, and L are all positive integers. Figure 5 The connection between the aforementioned switching unit and the harmonic module is also omitted. Similarly, the switching unit 204 with serial number N = n-1 and the switching unit 204 with serial number N = n are connected through the resonant module 205 with serial number M = n-1.

[0061] In this embodiment, please refer to Figure 6 The resonant module 205 includes a resonant capacitor Cr, a resonant inductor Lr, and a magnetizing inductor Lm connected in series. In one possible implementation, please refer to [reference needed]. Figure 7 The first terminal of the resonant capacitor Cr is connected to the third terminal of the first switching assembly 301 in the first switching unit with serial number N=1; the second terminal of the resonant capacitor Cr is connected to the first terminal of the resonant inductor Lr; the second terminal of the resonant inductor Lr is connected to the first terminal of the magnetizing inductor Lm; and the second terminal of the magnetizing inductor Lm is connected to the third terminal of the first switching assembly 301 in the second switching unit with serial number N=2. The magnetizing inductor Lm is also connected in parallel with a secondary winding Np.

[0062] Please continue reading. Figure 7 When the switching module 203 includes a first switching unit and a second switching unit; and the non-isolated switching power supply 100 includes a first energy storage inductor Ns1_1 and a second energy storage inductor Ns2_1, the first switching component 301 in the first switching unit includes a first switching transistor Q1 and a second switching transistor; and the first switching component 301 in the second switching unit includes a third switching transistor Q3 and a fourth switching transistor Q4. Figure 7For example, in this embodiment, the first switching unit, the second switching unit, the first energy storage inductor Ns1_1, and the second energy storage inductor Ns2_1 can be the switching unit 204 with serial number N=1, the switching unit 204 with serial number N=2, the energy storage inductor 104 with serial number L=1, and the energy storage inductor 104 with serial number L=2 described above.

[0063] Among them, continue to refer to Figure 7 In this embodiment, the first terminal of the first switch Q1 and the first terminal of the third switch Q3 are both connected to the power supply 103. The second terminal of the first switch Q1 is connected to the first terminal of the resonant module 205 and the first terminal of the second switch, respectively. The second terminal of the second switch is connected to the first terminal of the first energy storage inductor Ns1_1. The second terminal of the third switch Q3 is connected to the second terminal of the resonant module 205 and the first terminal of the fourth switch Q4, respectively. The second terminal of the fourth switch Q4 is connected to the first terminal of the second energy storage inductor Ns2_1. The second terminals of the first energy storage inductor Ns1_1 and the second energy storage inductor Ns2_1 are both connected to the input terminal of the load 102.

[0064] It should be noted that, in this embodiment, the third terminal of the first switching assembly 301 is the connection terminal between the first switching transistor Q1 and the second switching transistor Q2, and the third terminal of the second switching assembly 302 is the connection terminal between the third switching transistor Q3 and the fourth switching transistor Q4. Understandably, taking the resonant capacitor Cr in the resonant module 205 as an example, the first terminal of the resonant capacitor Cr is connected to the connection terminal between the first switching transistor Q1 and the second switching transistor Q2. Based on this, the switching unit and the harmonic module in this invention, through the above connection method, can reduce electrical signal interference between adjacent switching units and avoid electrical signal loss.

[0065] In one possible implementation, when the switching module 203 includes only the first switching unit, the non-isolated switching power supply 100 may include a first energy storage inductor Ns1_1, and the first switching assembly 301 in the first switching unit includes a first switching transistor Q1 and a second switching transistor Q2; the second switching assembly 302 includes a sixth switching transistor SR1.

[0066] When the control module determines that the output voltage exceeds a first preset threshold, the control module enters a first operating state. At this time, the control module sends first control signals to the first switch Q1, the second switch Q2, and the sixth switch SR1, respectively, and all three switches are turned on. Based on this, the output voltage of the power supply unit can be short-circuited to cause the switches or the input voltage fuse to blow, thereby achieving overvoltage protection at the output terminal through a self-destruction method that induces a short circuit.

[0067] When the control module determines that the output voltage exceeds the second preset threshold but is less than the first preset threshold, the control module enters a second operating state. At this time, the control module sends second control signals to the first switch Q1, the second switch Q2, and the sixth switch SR1, respectively. All three switches are then turned off. Based on this, the output voltage of the power supply unit can be disconnected, thereby cutting off the voltage output within an adjustable range and effectively protecting the load 102 from overvoltage damage.

[0068] When the control module determines that the output voltage is less than the second preset threshold, the control module is in the third working state. The control module sends a third control signal to the first switch Q1, the second switch Q2 and the sixth switch SR1 respectively. In this embodiment, the third control signal is a timing signal so that the above-mentioned switches are turned on or off in an orderly manner according to the timing requirements, so as to convert the output voltage of the power supply 103 into the required output voltage.

[0069] In one possible implementation, the third control signal includes a first PWM signal and a second PWM signal. The first PWM signal is used to control the first switch Q1 and the sixth switch SR1; the second PWM signal is used to control the second switch Q2. (See also...) Figure 8 In this embodiment, the first PWM signal and the second PWM signal are signals that are 180 degrees out of phase and have the same polarity. When the first PWM signal is on the rising edge, it is active high, and the first switch Q1 and the sixth switch SR1 are in the on state. At this time, the corresponding second PWM signal is on the falling edge, active low, and the second switch Q2 is in the off state.

[0070] Similarly, when the first PWM signal is at its falling edge, it is active low, and the first switch Q1 and the sixth switch SR1 are in the off state. When the corresponding second PWM signal is at its rising edge, it is active high, and the second switch Q2 is in the on state.

[0071] In this embodiment, to increase the current-carrying capacity of the overvoltage protection circuit, please refer to... Figure 9 The overvoltage protection circuit 101 also includes a shunt module 206; the shunt module 206 is connected in parallel with the load 102. In this embodiment, the number of shunt modules 206 is the same as the number of switching units 204.

[0072] In one possible implementation method, please refer to Figure 10The shunt module 206 includes a fifth switch SR2 and a first inductor Ns2_2. The first terminal of the first inductor Ns2_2 is connected to the output terminal of the energy storage inductor 104, and the second terminal of the first inductor Ns2_2 is connected to the first terminal of the fifth switch SR2. The second terminal of the fifth switch SR2 is connected to the output terminal of the load 102. The control terminal of the fifth switch SR2 is connected to the control module 201. The overvoltage protection circuit also includes an output filter capacitor Cout, which is connected in parallel with the load. In this embodiment, the load can be a load resistor Rout.

[0073] When the control module 201 determines that the output voltage exceeds the first preset threshold, the control module 201 is in the first working state and sends the first control signal to the fifth switch SR2, at which time the fifth switch SR2 is turned on.

[0074] Similarly, when the control module 201 determines that the output voltage exceeds the second preset threshold and is less than the first preset threshold, the control module 201 is in the second working state. At this time, the control module 201 sends a second control signal to the fifth switch SR2, and the fifth switch SR2 is turned off.

[0075] Similarly, when the control module 201 determines that the output voltage is less than the second preset threshold, the control module 201 enters the third operating state. The control module 201 sends a third control signal to the fifth switch SR2 to cause the fifth switch SR2 to be turned on or off in an orderly manner according to timing requirements. For example, the third control signal includes a first PWM signal and a second PWM signal. The first PWM signal is used to control the first switch Q1 and the sixth switch SR1; the second PWM signal is used to control the second switch Q2 and can also be used to control the fifth switch SR2.

[0076] When the first PWM signal is at its rising edge, the first switch Q1 and the sixth switch SR1 are in the ON state, and when the corresponding second PWM signal is at its falling edge, the second switch Q2 is in the OFF state. Similarly, when the first PWM signal is at its falling edge, the first switch Q1 and the sixth switch SR1 are in the OFF state, and when the corresponding second PWM signal is at its rising edge, the second switch Q2 is in the ON state.

[0077] In another possible implementation, when the switching module 203 includes multiple switching units 204, such as a first switching unit and a second switching unit, the overvoltage protection circuit 101 further includes two shunt modules 206. Each shunt module 206 is connected in parallel with the second switching component 302 in the first switching unit and the second switching unit, respectively. In this case, the non-isolated switching power supply 100 includes a corresponding number of energy storage inductors 104, such as a first energy storage inductor Ns1_1 and a second energy storage inductor Ns2_1. The overvoltage protection circuit also includes an input filter capacitor Cin, which is connected in parallel with the power supply 103.

[0078] Please refer to Figure 11 , Figure 11 A circuit diagram of an overvoltage protection circuit is shown. In the first switching unit, the first switching assembly 301 includes a first switching transistor Q1 and a second switching transistor Q2; the second switching assembly 302 in the first switching unit includes a sixth switching transistor SR1; the first switching assembly 301 in the second switching unit includes a third switching transistor Q3 and a fourth switching transistor Q4; and the second switching assembly 302 in the second switching unit includes an eighth switching transistor SR4. The shunt module 206 includes a sixth switching transistor SR1, a seventh switching transistor SR3, a first inductor Ns2_2, and a second inductor Ns1_2.

[0079] In this embodiment, when the control module 201 determines that the output voltage is less than the second preset threshold, the control module 201 is in a third operating state. The control module 201 sends a third control signal to the fifth switch SR2 so that the fifth switch SR2 is turned on or off in an orderly manner according to the timing requirements. For example, the third control signal includes a first PWM signal and a second PWM signal. The first PWM signal is used to control the first switch Q1, the fourth switch Q4, the sixth switch SR1, and the seventh switch SR3; the second PWM signal is used to control the second switch Q2, the third switch Q3, the fifth switch SR2, and the eighth switch SR4. The control signals corresponding to the first switch component 301 in the first switch unit and the first switch component 301 in the second switch unit are opposite, so that the output voltage of the power supply 103 can be converted into the required output voltage.

[0080] Based on this, this embodiment provides an overvoltage protection circuit, including: a control module, an overvoltage detection module, and a switching module. The switching module includes at least one switching unit, with its first terminal connected to the power supply; its second terminal connected to the input terminal of the load via an energy storage inductor; and its third terminal grounded. The overvoltage detection module is connected to the output terminal of the load and the control module, and is used to detect the output voltage of the load. The control module is also connected to the control terminal of the switching unit; wherein, the control module includes multiple operating states; when the control module determines that the output voltage exceeds a first preset threshold, the control module is in a first operating state, sending a first control signal to the switching unit to turn it on and short-circuit the power supply.

[0081] This embodiment can avoid the problem of overvoltage at the output terminal caused by direct connection between the input source and the load without increasing the structural size and manufacturing cost of the non-isolated switching power supply.

[0082] For the same concept as the first aspect, please refer to... Figure 12 The present invention also provides a non-isolated switching power supply 100, including a load 102, a power supply 103, an energy storage inductor 104, and an overvoltage protection circuit 101 according to any one of the first aspects described above. The overvoltage protection circuit 101 includes a control module 201, an overvoltage detection module 202, and a switching module 203. The switching module 203 includes at least one switching unit 204. The first terminal of the switching unit 204 is connected to the power supply 103; the second terminal of the switching unit 204 is connected to the input terminal of the load 102 through the energy storage inductor 104; and the third terminal of the switching unit 204 is grounded. The overvoltage detection module 202 is connected to the output terminal of the load 102 and the control module 201, and is used to detect the output voltage of the load 102. The control module 201 is also connected to the control terminal of the switching unit 204.

[0083] This embodiment includes all the technical means and features of the previous embodiment. That is, it can avoid the problem of overvoltage at the output terminal caused by direct connection between the input source and the load without increasing the structural size and manufacturing cost of the non-isolated switching power supply.

[0084] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An overvoltage protection circuit applied to a non-isolated switching power supply, wherein the non-isolated switching power supply includes a load, a power supply, and at least one energy storage inductor; characterized in that, The overvoltage protection circuit includes: a control module, an overvoltage detection module, and a switching module; the switching module includes at least one switching unit, the first terminal of which is connected to the power supply; the second terminal of which is connected to the input terminal of the load through the energy storage inductor; and the third terminal of which is grounded. The overvoltage detection module is connected to the output terminal of the load and the control module, and is used to detect the output voltage of the load; The control module is also connected to the control terminal of the switching unit; wherein, the control module includes multiple operating states; When the control module determines that the output voltage exceeds a first preset threshold, the control module is in a first working state and sends a first control signal to the switching unit to turn on the switching unit and short-circuit the power supply.

2. The overvoltage protection circuit according to claim 1, characterized in that, The switching unit includes a first switching assembly and a second switching assembly; a first terminal of the first switching assembly is connected to the power supply; a second terminal of the first switching assembly is connected to both the first terminal of the second switching assembly and the first terminal of the energy storage inductor; a second terminal of the energy storage inductor is connected to the input terminal of the load; a second terminal of the second switching assembly is grounded; and control terminals of both the first and second switching assemblies are connected to the control module. When the control module determines that the output voltage exceeds a first preset threshold, the control module is in a first working state and sends a first control signal to the first switch assembly and the second switch assembly respectively. The first switch assembly is turned on and the second switch assembly is turned on to short-circuit the power supply.

3. The overvoltage protection circuit according to claim 2, characterized in that, When there are multiple switching units, the number of energy storage inductors is the same as the number of switching units, and the overvoltage protection circuit further includes at least one resonant module; wherein, each of the switching units is connected in parallel through one of the resonant modules, and is connected to the input terminal of the load through one of the energy storage inductors.

4. The overvoltage protection circuit according to claim 3, characterized in that, When the switching module includes a first switching unit and a second switching unit, the resonant module includes a resonant capacitor, a resonant inductor, and a magnetizing inductor; the first end of the resonant capacitor is connected to the third end of the first switching component in the first switching unit; the second end of the resonant capacitor is connected to the first end of the resonant inductor; the second end of the resonant inductor is connected to the first end of the magnetizing inductor; and the second end of the magnetizing inductor is connected to the third end of the first switching component in the second switching unit.

5. The overvoltage protection circuit according to claim 3, characterized in that, When the switching module includes a first switching unit and a second switching unit; and the non-isolated switching power supply includes a first energy storage inductor and a second energy storage inductor, the first switching component in the first switching unit includes a first switching transistor and a second switching transistor; and the first switching component in the second switching unit includes a third switching transistor and a fourth switching transistor. The first terminal of the first switching transistor and the first terminal of the third switching transistor are both connected to the power supply; the second terminal of the first switching transistor is connected to the first terminal of the resonant module and the first terminal of the second switching transistor, respectively; the second terminal of the second switching transistor is connected to the first terminal of the first energy storage inductor; the second terminal of the third switching transistor is connected to the second terminal of the resonant module and the first terminal of the fourth switching transistor, respectively; the second terminal of the fourth switching transistor is connected to the first terminal of the second energy storage inductor; the second terminals of the first energy storage inductor and the second energy storage inductor are both connected to the input terminal of the load.

6. The overvoltage protection circuit according to claim 2, characterized in that, The control module is further configured to, when the output voltage exceeds a second preset threshold and is less than the first preset threshold, be in a second operating state, and send a second control signal to the first switch component and the second switch component respectively, wherein the first switch component is turned off and the second switch component is turned off.

7. The overvoltage protection circuit according to claim 1, characterized in that, The overvoltage protection circuit also includes a shunt module; the shunt module is connected in parallel with the load.

8. The overvoltage protection circuit according to claim 7, characterized in that, The current shunt module includes a fifth switching transistor and a first inductor; a first terminal of the first inductor is connected to the output terminal of the energy storage inductor, and a second terminal of the first inductor is connected to the first terminal of the fifth switching transistor; a second terminal of the fifth switching transistor is connected to the output terminal of the load; and a control terminal of the fifth switching transistor is connected to the control module. When the control module determines that the output voltage exceeds the first preset threshold, the control module is in the first working state and sends the first control signal to the switching unit and the fifth switching transistor respectively, and both the switching unit and the fifth switching transistor are turned on.

9. The overvoltage protection circuit according to claim 1, characterized in that, The control module is further configured to, when the control module determines that the output voltage is less than the second preset threshold, enter a third working state and send a third control signal to the switching unit, so that the switching unit turns on or off according to the timing corresponding to the third control signal, and converts the output voltage of the power supply into the required output voltage; wherein, the first preset threshold is greater than the second preset threshold.

10. A non-isolated switching power supply, characterized in that, It includes a load, a power supply, at least one energy storage inductor, and the overvoltage protection circuit described in any one of claims 1 to 9.

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