Relay overload protection circuit and protection method thereof, and energy storage converter topology system

Abstract

The application relates to a relay overload protection circuit and a protection method thereof and an energy storage converter topology system. The relay overload protection circuit comprises a controller, a sampling unit, a protection unit, a logic judgment unit and a relay. The first output end of the controller is connected to the input end of a power side circuit. The input end and the output end of the sampling unit are respectively connected to the output end of the power side circuit and the input end of the controller. The input end of the protection unit is connected to the output end of the sampling unit. Two input ends of the logic judgment unit are respectively connected to the second output end of the controller and the output end of the sampling unit. The input end of the relay is connected to the output end of the logic judgment unit. The protection unit and the controller judge whether the power side circuit is overloaded according to the sampling signal of the sampling unit. The logic judgment unit outputs a relay driving signal according to the protection signal output by the protection unit and the control signal output by the control unit, so as to control the opening or closing of the relay.

Description

Technical Field

[0001] This application relates to the field of converter overload protection technology, and in particular to a relay overload protection circuit and its protection method, and an energy storage converter topology system. Background Technology

[0002] With the transformation of the global energy structure and the large-scale deployment of renewable energy, energy storage technology has become a key component of the power system. As the core equipment of an energy storage system, the performance and efficiency of the power conversion system (PCS) directly affect the economic benefits and technical feasibility of the entire energy storage system.

[0003] In a typical energy storage converter topology, the DC side and battery side are controlled by DC relays or contactors to switch the power-side circuit on and off, while the AC side and grid side are controlled by AC relays to achieve bidirectional energy conversion. During normal startup, the relays are usually closed first, and then the charging / discharging power is adjusted until the required value is reached. During normal shutdown, the charging / discharging power is usually reduced to enter standby mode, and the relays are disconnected. However, when the energy storage converter experiences faults such as overcurrent, overvoltage, or control terminal abnormalities, the control-side circuit will immediately block the inverter or rectifier control output upon detecting the fault and disconnect the relays. However, if the system current of the energy storage converter topology exceeds the maximum disconnect current of the relays, directly disconnecting the relays can damage them. Summary of the Invention

[0004] Therefore, it is necessary to provide a relay overload protection circuit and its protection method, as well as an energy storage converter topology system, to achieve overload protection for the relay and reduce or avoid the risk of damage to the relay.

[0005] This application provides a relay overload protection circuit, including:

[0006] A controller, wherein the first output terminal of the controller is connected to the input terminal of a power-side circuit for sending a power signal to the power-side circuit;

[0007] A sampling unit, the input terminal of which is connected to the output terminal of the power-side circuit, and the output terminal of which is connected to the input terminal of the controller, is used to collect the operating parameters of the power-side circuit and output a sampling signal according to the operating parameters;

[0008] A protection unit, wherein the input terminal of the protection unit is connected to the output terminal of the sampling unit, is used to receive the sampling signal and output a protection signal according to the sampling signal;

[0009] A logic judgment unit, wherein the two input terminals of the logic judgment unit are respectively connected to the second output terminal of the controller and the output terminal of the sampling unit, and is used to output a relay drive signal according to the protection signal and the control signal, wherein the control signal is the signal transmitted by the controller to the logic judgment unit;

[0010] A relay, the input terminal of which is connected to the output terminal of the logic judgment unit, is used to receive the relay drive signal and adjust the relay to be turned on or off according to the relay drive signal.

[0011] In one embodiment, the protection unit includes a hysteresis comparator, wherein the upper threshold of the hysteresis comparator is the maximum interrupt current value of the relay, and the lower threshold of the hysteresis comparator is the rated current value of the relay.

[0012] The in-phase hysteresis comparator is used to output an invalid protection signal when the sampling current value of the sampling signal is less than the lower threshold; and to output an active protection signal when the sampling current value is greater than the upper threshold; wherein, the low-level protection signal is invalid and the high-level protection signal is active.

[0013] In one embodiment, the logic judgment unit includes an OR gate circuit, the two input terminals of which are respectively connected to the second output terminal of the controller and the output terminal of the non-inverting hysteresis comparator, and the output terminal of the OR gate circuit is connected to the input terminal of the relay.

[0014] In one embodiment, the protection unit includes a hysteresis comparator and a single-threshold comparator, and the protection signal output by the protection unit includes a first protection signal output by the hysteresis comparator and a second protection signal output by the single-threshold comparator.

[0015] The upper threshold of the hysteresis comparator is the maximum interrupt current value of the relay, the lower threshold of the hysteresis comparator is the rated current value of the relay, and the ultimate threshold of the single-threshold comparator is the extreme overcurrent value of the power-side circuit, and the ultimate threshold is greater than the upper threshold.

[0016] The in-phase hysteresis comparator is used to output an invalid first protection signal when the sampling current value of the sampling signal is less than the lower threshold; it is also used to output an valid first protection signal when the sampling current value is greater than the upper threshold.

[0017] The single-threshold comparator is used to output an invalid second protection signal when the sampled current value is greater than or equal to the limit threshold; it is also used to output an valid second protection signal when the sampled current value is less than the limit threshold.

[0018] Specifically, a low-level first protection signal is disabled, while a high-level first protection signal is enabled; a high-level second protection signal is disabled, while a low-level second protection signal is enabled.

[0019] In one embodiment, the in-phase hysteresis comparator includes a first comparator, a first resistor, a second resistor, a third resistor, a first capacitor, a second capacitor, and a first reference source;

[0020] Wherein, the output terminal of the first reference source is connected to the inverting input terminal of the first comparator, and the inverting input terminal of the first comparator is grounded through the first capacitor; the output terminal of the sampling unit is connected to the non-inverting input terminal of the first comparator through the first resistor, the non-inverting input terminal of the first comparator is connected to the output terminal of the first comparator through the second resistor, the output terminal of the first comparator is grounded through the third resistor and the second capacitor, and the end of the third resistor away from the first comparator is connected to the logic judgment unit as the output terminal of the non-inverting hysteresis comparator.

[0021] In one embodiment, the single-threshold comparator includes a second comparator, a fourth resistor, a fifth resistor, a sixth resistor, a third capacitor, a fourth capacitor, a fifth capacitor, and a second reference source;

[0022] The output of the second reference source is connected to the inverting input of the second comparator, and the inverting input of the second comparator is grounded through the third capacitor; the output of the sampling unit is connected to the non-inverting input of the second comparator through the fourth resistor, and the non-inverting input of the second comparator is grounded through the fifth resistor, and the fourth capacitor and the fifth resistor are connected in parallel; the output of the second comparator is grounded through the sixth resistor and the fifth capacitor, and the end of the sixth resistor furthest from the second comparator is connected to the logic judgment unit as the output of the single-threshold comparator.

[0023] In one embodiment, when the logic judgment unit includes a first NOR gate and a second NOR gate, the two inputs of the first NOR gate are respectively connected to the second output of the controller and the output of the non-inverting hysteresis comparator, for receiving the first protection signal and the control signal and outputting an intermediate signal; the two inputs of the second NOR gate are respectively connected to the output of the first NOR gate and the output of the single-threshold comparator, for receiving the intermediate signal and the second protection signal and outputting the relay drive signal.

[0024] In one embodiment, the protection unit includes a dual-threshold comparator, wherein the first-level threshold of the dual-threshold comparator is less than the maximum interruption current value of the relay, and the second-level threshold of the dual-threshold comparator is the extreme overcurrent value of the power-side circuit.

[0025] The dual-threshold comparator is used to output an invalid protection signal when the sampled current value of the sampled signal is greater than the secondary threshold or less than the primary threshold; it is also used to output an active protection signal when the sampled current value is between the primary threshold and the secondary threshold; wherein, a low-level protection signal invalidates the protection signal, and a high-level protection signal enables the protection signal.

[0026] In one embodiment, the dual-threshold comparator includes a third comparator, a fourth comparator, a third reference source, a fourth reference source, a first diode, a second diode, a plurality of threshold resistors, and a plurality of threshold capacitors;

[0027] The output of the third reference source is connected to the non-inverting input of the third comparator, and the non-inverting input of the third comparator is grounded through a first threshold capacitor; the output of the sampling unit is connected to the inverting input of the third comparator through a first threshold resistor, and the inverting input of the third comparator is grounded through a second threshold resistor, and the second threshold capacitor and the second threshold resistor are connected in parallel.

[0028] The output terminal of the fourth reference source is connected to the inverting input terminal of the fourth comparator; the inverting input terminal of the fourth comparator is grounded through the third threshold capacitor; the output terminal of the sampling unit is connected to the non-inverting input terminal of the fourth comparator through the third threshold resistor; the non-inverting input terminal of the fourth comparator is grounded through the fourth threshold resistor; and the fourth threshold capacitor and the fourth threshold resistor are connected in parallel.

[0029] The output of the third comparator is connected to the negative terminal of the first diode through a fifth threshold resistor, the output of the fourth comparator is connected to the negative terminal of the second diode through a sixth threshold resistor, the positive terminal of the first diode is connected to the positive terminal of the power supply through a seventh threshold resistor, the positive terminal of the second diode is grounded through a fifth threshold capacitor, and the positive terminals of the first diode and the second diode are connected and serve as the output of the dual-threshold comparator.

[0030] In one embodiment, the logic judgment unit includes an OR gate circuit, the two input terminals of which are respectively connected to the second output terminal of the controller and the output terminal of the dual-threshold comparator, and the output terminal of the OR gate circuit is connected to the input terminal of the relay.

[0031] In one embodiment, the sampling unit includes a sensor, an operational amplifier, multiple sampling resistors, and multiple sampling capacitors;

[0032] The sensor converts the current signal from the power-side circuit into a differential voltage signal. This differential voltage signal is transmitted to the non-inverting input of the operational amplifier via a first sampling resistor. The non-inverting input of the operational amplifier is grounded via a second sampling resistor, and a first sampling capacitor is connected in parallel with the second sampling resistor. The sensor transmits the differential voltage signal to the inverting input of the operational amplifier via a third sampling resistor. The inverting input of the operational amplifier is connected to its output via a fourth sampling resistor, and a second sampling capacitor is connected in parallel with the fourth sampling resistor. The output of the operational amplifier is grounded via a fifth sampling resistor and the third sampling capacitor, and is connected to the input of the protection unit. The end of the fifth sampling resistor furthest from the operational amplifier is connected to the input of the controller.

[0033] In one embodiment, the operating parameters collected by the sampling unit include at least one of inverter voltage parameters, grid voltage parameters, and AC current parameters.

[0034] In one embodiment, the power-side circuit includes a power drive unit and a power loop device;

[0035] The power drive unit is used to issue a power drive signal according to the power signal, and the power circuit device adjusts the output power according to the power drive signal.

[0036] In one embodiment, the power circuit device includes at least one of an insulated gate bipolar transistor device and a silicon carbide power device.

[0037] Accordingly, this application also provides an overload protection method, which uses the relay overload protection circuit described above for overload protection, including:

[0038] Acquire the sampling signal of the power-side circuit; the sampling signal is related to the operating parameters of the power-side circuit;

[0039] If the sampling current value of the sampling signal is greater than the first threshold current and less than the second threshold current, the relay remains on and the power signal output to the power side circuit is stopped; the first threshold current is the maximum cut-off current value of the relay, and the second threshold current is the extreme overcurrent value of the power side circuit.

[0040] If the sampled current value drops below the first threshold current and the control signal is ineffective, the relay is controlled to disconnect.

[0041] In one embodiment, controlling the relay to disconnect when the sampled current value drops below the first threshold current and the control signal is disabled includes:

[0042] When the sampled current value is between the third threshold current and the first threshold current, the relay is disconnected if the control signal enable is invalid, and the relay is turned on if the control signal enable is valid; the third threshold current is the rated current value of the relay, and the third threshold current is less than the first threshold current;

[0043] If the sampled current value drops below the third threshold current and the control signal is disabled, the relay is controlled to disconnect.

[0044] In one embodiment, the overload protection method further includes:

[0045] If the sampled current value is greater than the second threshold current, the relay is controlled to disconnect.

[0046] Accordingly, this application also provides an energy storage converter topology system, including:

[0047] Energy storage battery side circuit;

[0048] The power-side circuit is connected to the energy storage battery-side circuit via a DC contactor;

[0049] The control-side circuit includes the relay overload protection circuit described above, or performs the overload protection method described above.

[0050] The grid-side circuit is connected to the power-side circuit via a relay in the relay overload protection circuit.

[0051] In summary, this application provides a relay overload protection circuit and method, as well as an energy storage converter topology system. The sampling unit collects operating parameters of the power-side circuit and outputs sampling signals. The protection unit and controller determine whether an overload has occurred in the power-side circuit based on the sampling signals, and respectively input protection signals and control signals to the logic judgment unit. The logic judgment unit outputs relay drive signals based on the protection signals and control signals to control the relay's opening or closing, thereby achieving overload protection for the relay and reducing or avoiding the risk of relay damage. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a system block diagram of a relay overload protection circuit provided in one embodiment of this application.

[0054] Figure 2 This is a schematic diagram of the circuit structure of the sampling unit in a relay overload protection circuit provided in one embodiment of this application.

[0055] Figure 3 The following is a system block diagram corresponding to the case where the protection unit of the relay overload protection circuit provided in one embodiment of this application includes a non-inverting hysteresis comparator.

[0056] Figure 4 This is a schematic diagram of the hysteresis curve of the same-direction hysteresis comparator in a relay overload protection circuit provided in one embodiment of this application.

[0057] Figure 5 This is a schematic diagram of the circuit structure of the non-inverting hysteresis comparator in a relay overload protection circuit provided in one embodiment of this application.

[0058] Figure 6 This is a schematic diagram of the circuit structure corresponding to the case where the protection unit of the relay overload protection circuit provided in one embodiment of this application includes a non-inverting hysteresis comparator.

[0059] Figure 7 The following is a system block diagram corresponding to the case where the protection unit of the relay overload protection circuit provided in one embodiment of this application includes a non-inverting hysteresis comparator and a single-threshold comparator.

[0060] Figure 8This is a schematic diagram of the circuit structure of a single-threshold comparator in a relay overload protection circuit provided in one embodiment of this application.

[0061] Figure 9 This is a schematic diagram of the circuit structure corresponding to the case where the protection unit of the relay overload protection circuit provided in one embodiment of this application includes a non-inverting hysteresis comparator and a single-threshold comparator.

[0062] Figure 10 The following is a system block diagram corresponding to the case where the protection unit of the relay overload protection circuit provided in one embodiment of this application includes a dual-threshold comparator.

[0063] Figure 11 This is a schematic diagram of the circuit structure of a dual-threshold comparator in a relay overload protection circuit provided in one embodiment of this application.

[0064] Figure 12 This is a schematic diagram of the circuit structure corresponding to the case where the protection unit of the relay overload protection circuit provided in one embodiment of this application includes a dual-threshold comparator.

[0065] Figure 13 This is a system block diagram of an energy storage converter topology system provided in one embodiment of this application.

[0066] The reference numerals in the attached figures include: 100-controller; 110-sampling unit; 111-sensor; 120-protection unit; 121-same-direction hysteresis comparator; 121a-first reference source; 122-single-threshold comparator; 122a-second reference source; 123-dual-threshold comparator; 123a-third reference source; 123b-fourth reference source; 130-logic judgment unit; 131-first NOR gate circuit; 132-second NOR gate circuit; 140-relay; 150-power side circuit; 151-power drive unit; 152-power loop device; 200-energy storage battery side circuit; 210a-DC contactor; 220-control side circuit; 230-grid side circuit. Detailed Implementation

[0067] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0068] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0069] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, parts, regions, layers, doping types, and / or portions, these elements, parts, regions, layers, doping types, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, part, region, layer, doping type, or portion from another element, part, region, layer, doping type, or portion. Therefore, without departing from the teachings of this application, the first element, component, region, layer, doping type, or portion discussed below may be represented as a second element, component, region, layer, or portion; for example, the first doping type may be referred to as the second doping type, and similarly, the second doping type may be referred to as the first doping type; the first doping type and the second doping type are different doping types, for example, the first doping type may be P-type and the second doping type may be N-type, or the first doping type may be N-type and the second doping type may be P-type.

[0070] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein to describe the relationship between one element or feature shown in the figure and other elements or features. It should be understood that, in addition to the orientation shown in the figure, spatial relation terms also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, the element or feature described as “below,” “under,” or “below” will be oriented “above” the other element or feature. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. Furthermore, the device may also include other orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptive terms used herein will be interpreted accordingly.

[0071] When used herein, the singular forms of “a,” “an,” and “ / the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, in this specification, the term “and / or” includes any and all combinations of the associated listed items.

[0072] Figure 1 This is a system block diagram of a relay overload protection circuit provided in one embodiment of this application. See also... Figure 1 One embodiment of this application provides a relay overload protection circuit including a controller 100, a sampling unit 110, a protection unit 120, a logic judgment unit 130, and a relay 140. The first output terminal of the controller 100 is connected to the input terminal of a power-side circuit 150, used to send a power signal to the power-side circuit 150. The input terminal of the sampling unit 110 is connected to the output terminal of the power-side circuit 150, and the output terminal of the sampling unit 110 is connected to the input terminal of the controller 100. The sampling unit 110 is used to collect the operating parameters of the power-side circuit 150 and output a sampling signal according to the operating parameters. The protection unit 120... The input terminal of element 120 is connected to the output terminal of sampling unit 110 to receive sampling signals and output protection signals according to the sampling signals; the two input terminals of logic judgment unit 130 are respectively connected to the second output terminal of controller 100 and the output terminal of sampling unit 110, and are used to output relay drive signals according to protection signals and control signals, wherein the control signal is the signal transmitted from controller 100 to logic judgment unit 130; the input terminal of relay 140 is connected to the output terminal of logic judgment unit 130 to receive relay drive signals and adjust the opening or closing of relay 140 according to relay drive signals.

[0073] As described above, the relay overload protection circuit acquires the operating parameters of the power-side circuit through a sampling unit and outputs a sampling signal. The protection unit and the controller determine whether the power-side circuit is overloaded based on the sampling signal, and respectively input protection signals and control signals to the logic judgment unit. The logic judgment unit outputs relay drive signals based on the protection signals and the control signals to control the relay to open or close, thereby achieving overload protection for the relay and reducing or avoiding the risk of damage to the relay.

[0074] See Figure 1 In one embodiment, the controller 100 includes an analog-to-digital converter (ADC). In other embodiments of this application, a suitable controller may be selected according to actual needs, and this application does not impose any limitations on this.

[0075] Continue reading Figure 1 In one embodiment, the power-side circuit 150 includes a power drive unit 151 and a power loop device 152; wherein, the power drive unit 151 is used to generate a power drive signal according to a power signal, and the power loop device 152 adjusts the output power according to the power drive signal. Optionally, the power drive unit 151 includes a pulse width modulation (PWM) drive module. Optionally, the power loop device 152 includes at least one of an insulated gate bipolar transistor (IGBT) and a silicon carbide power device (SiC). It should be noted that in other embodiments of this application, the specific structure of the power-side circuit and the related power devices used can be adjusted according to actual needs, and this application does not impose any limitations on this.

[0076] See Figure 1 and Figure 2 In one embodiment, the sampling unit 110 includes a sensor 111, an operational amplifier U1A, multiple sampling resistors, and multiple sampling capacitors. The sensor 111 converts the current signal from the power-side circuit 150 into a differential voltage signal, which is transmitted to the non-inverting input of the operational amplifier U1A via a first sampling resistor R1. The non-inverting input of the operational amplifier U1A is grounded via a second sampling resistor R2, and the first sampling capacitor C1 is connected in parallel with the second sampling resistor R2. The sensor 111 transmits the differential voltage signal to the inverting input of the operational amplifier U1A via a third sampling resistor R3. The inverting input of the operational amplifier U1A is connected to the output of the operational amplifier U1A via a fourth sampling resistor R4. The second sampling capacitor C2 is connected in parallel with the fourth sampling resistor R4. The output of the operational amplifier U1A is grounded via a fifth sampling resistor R5 and the third sampling capacitor C3, and the output of the operational amplifier U1A is connected to the input of the protection unit 120. The end of the fifth sampling resistor R5 furthest from the operational amplifier U1A is connected to the input of the controller 100.

[0077] It should be noted that after the sensor converts the operating parameters (such as current signals) in the power-side circuit into differential voltage signals, these signals can be amplified by a differential operational amplifier formed by operational amplifier U1A and multiple sampling resistors to obtain the corresponding sampled voltage values, which are then output to the protection unit 120 and the controller 100. Optionally, the resistance values ​​of the sampling resistors can be adjusted according to actual needs, thereby adjusting the amplification factor between the operating parameters acquired by the sensor and the sampled signals. For example, the amplification factor between the system current value and the sampled voltage value acquired by the sensor can be adjusted by adjusting the resistance values ​​of multiple sampling resistors.

[0078] In one embodiment, the operating parameters collected by the sampling unit include at least one of the inverter voltage parameters, grid voltage parameters, and AC current parameters in the power-side circuit. Optionally, the sampling unit uses sensors to collect operating parameters in the power-side circuit (e.g., power loop devices), uses a combination of multi-stage sampling resistors and operational amplifiers to convert the operating parameter signals into sampling signals, and outputs the sampling signals to the controller and protection unit.

[0079] See Figure 3 and Figure 4 In one embodiment, the protection unit 120 includes a hysteresis comparator 121, wherein the upper threshold of the hysteresis comparator 121 is the maximum cut-off current value of the relay 140, and the lower threshold of the hysteresis comparator 121 is the rated current value of the relay 140; the hysteresis comparator 121 is used to output an invalid protection signal when the sampled current value of the sampled signal is less than the lower threshold; and is also used to output an effective protection signal when the sampled current value is greater than the upper threshold; wherein a low-level protection signal enables invalid protection, and a high-level protection signal enables effective protection.

[0080] See Figure 5 In one embodiment, the non-inverting hysteresis comparator 121 includes a first comparator U2A, a first resistor R6, a second resistor R7, a third resistor R8, a first capacitor C4, a second capacitor C5, and a first reference source 121a; wherein, the output terminal of the first reference source 121a is connected to the inverting input terminal of the first comparator U2A, and the inverting input terminal of the first comparator U2A is grounded through the first capacitor C4; the output terminal of the sampling unit 110 is connected to the non-inverting input terminal of the first comparator U2A through the first resistor R6, the non-inverting input terminal of the first comparator U2A is connected to the output terminal of the first comparator U2A through the second resistor R7, the output terminal of the first comparator U2A is grounded through the third resistor R8 and the second capacitor C5, and the end of the third resistor R8 away from the first comparator U2A serves as the output terminal of the non-inverting hysteresis comparator 121 and is connected to the logic judgment unit 130.

[0081] It should be noted that when the sampled signal is transmitted to the protection unit 120, the in-phase hysteresis comparator 121, as described above, configures a suitable voltage division ratio by adjusting the resistance values ​​of the first resistor R6 and the second resistor R7, and configures a suitable reference voltage value (VREF) through the first reference source 121a to obtain the required upper and lower threshold values. When the sampled signal is greater than the upper threshold value, the in-phase hysteresis comparator 121 outputs a high level; when the sampled signal is less than the lower threshold value, the in-phase hysteresis comparator 121 outputs a low level. The interval between the lower and upper threshold values ​​is the hysteresis interval of the in-phase hysteresis comparator 121.

[0082] It should be emphasized that the non-inverting hysteresis comparator includes, but is not limited to, the circuit implementation described above. In other embodiments of this application, the circuit structure of the non-inverting hysteresis comparator can be adjusted according to the actual situation, and this application does not impose any restrictions on it.

[0083] See Figure 3 and Figure 6 In one embodiment, the logic judgment unit 130 includes an OR gate circuit. The two inputs of the OR gate circuit are respectively connected to the second output of the controller 100 and the output of the non-inverting hysteresis comparator 121, and the output of the OR gate circuit is connected to the input of the relay 140. In other embodiments of this application, the logic judgment unit 130 can also be replaced with other equivalent logic control circuits, as long as the overload protection function of the relay can be implemented. This application does not impose any restrictions on this.

[0084] Continue reading Figure 3 In one embodiment, a suitable relay model can be selected based on the current-carrying capacity, rated current value, rated switching voltage value, and maximum interruption current value of the relay 140. Optionally, if the relay 140 is selected as a 250A model, the relay 140 has a current-carrying capacity of 250A in the open state (i.e., the energized state), a rated current value of 55A in both the open and closed states (i.e., the disconnected state), and a maximum interruption current value of 275A.

[0085] See Figure 3 In one embodiment, the operation of the relay overload protection circuit includes at least the normal operation of the power side circuit 150 and the overload operation of the power side circuit 150. The operation of the relay overload protection circuit under different conditions will be described in detail below with reference to the specific structure of the relay overload protection circuit.

[0086] When the power side circuit 150 is working normally, the sampling current value of the sampling signal is less than or equal to the upper threshold (i.e., the maximum cut-off current value of the relay 140), the protection signal output by the protection unit 120 is low level, and the relay drive signal output by the logic judgment unit 130 changes with the change of the control signal output by the controller 100, thereby controlling the opening and closing of the relay 140 through the controller 100.

[0087] When a system fault occurs in the power-side circuit 150, leading to overload operation, the sampling current value of the sampling signal is greater than the upper threshold, and the protection signal output by the protection unit 120 is high. At the same time, the controller 100 determines that a system fault has occurred in the power-side circuit 150 based on the sampling current value and performs waveform blocking, stopping the transmission of power signals to the power-side circuit 150. The control signal output by the controller 100 to the logic judgment unit 130 is low. At this time, since the protection signal is high and the control signal is low, and the logic judgment unit 130 includes an OR gate circuit, the relay drive signal output by the logic judgment unit 130 is still high, controlling the relay 140 to remain in the open state (i.e., the energized state), so as to avoid the relay 140 being damaged due to direct disconnection when the sampling current value is higher than the maximum cut-off current value, thus realizing the overload protection of the relay 140.

[0088] It should be emphasized that when the controller 100 performs waveform blocking, as the power signal stops, the sampling current value sampled by the sampling unit 110 gradually decreases. When the sampling current value drops below the lower threshold (i.e., the rated current value of the relay 140), the protection signal output by the protection unit 120 switches to a low level, and the control signal output by the controller 100 also switches to a low level. Therefore, the relay drive signal output by the logic judgment unit 130 also switches to a low level, controlling the relay 140 to switch to the open state, so as to achieve the safe disconnection of the relay 140, thereby helping to improve the service life of the relay 140 and reduce production costs.

[0089] It should be noted that, in the relay overload protection circuit described above, the combination structure of the protection unit including a non-inverting hysteresis comparator and the logic judgment unit including an OR gate circuit is one implementation of the relay overload protection circuit. In other embodiments of this application, the specific structure of the protection unit and the logic judgment unit can be adjusted according to the actual situation, as long as it is ensured that the relay overload protection circuit can still achieve the same logic control function, so as to ensure that the relay overload protection circuit has the overload protection effect.

[0090] Figure 3 and Figure 6 In the relay overload protection circuit shown, when an overload fault occurs in the power-side circuit 150 and is blocked, the relay is only controlled to disconnect when the sampled current value drops below the relay's rated current value, thus maximizing the lifespan of the relay 140. However, Figure 3 and Figure 6The provided relay overload protection circuit does not consider extreme faults (such as shoot-through of power circuit devices or load short circuit). If the cut-off delay is too long (i.e., the relay 140 remains in the open state for too long when the sampled current value is greater than the maximum cut-off current value), the excessive current is likely to damage the power side circuit or other structures in the relay overload protection circuit, and in severe cases, even safety problems may occur.

[0091] See Figure 3 and Figure 7 To avoid the above situation, the circuit structure of the protection unit 120 can be adjusted based on the relay overload protection circuit described above, in order to cope with extreme faults in the relay overload protection circuit and improve the safety and reliability of the relay overload protection circuit.

[0092] See Figure 7 In one embodiment, the protection unit 120 includes not only a co-directional hysteresis comparator 121 but also a single-threshold comparator 122. The protection signal output by the protection unit 120 includes a first protection signal output by the co-directional hysteresis comparator 121 and a second protection signal output by the single-threshold comparator 122. The upper threshold of the co-directional hysteresis comparator 121 is the maximum cutting current value of the relay 140, the lower threshold of the co-directional hysteresis comparator 121 is the rated current value of the relay, and the ultimate threshold of the single-threshold comparator 122 is the extreme overcurrent value of the power-side circuit 150 (i.e., the maximum current at which the power-side circuit can operate normally), and the ultimate threshold is greater than the upper threshold. Hysteresis comparator 121 is used to output a first protection signal that disables the current when the sampled current value is less than the lower threshold; and to output a first protection signal that enables the current when the sampled current value is greater than the upper threshold. Single-threshold comparator 122 is used to output a second protection signal that disables the current when the sampled current value is greater than or equal to the limit threshold; and to output a second protection signal that enables the current when the sampled current value is less than the limit threshold. A low-level first protection signal disables the current, while a high-level first protection signal enables the current; a high-level second protection signal disables the current, while a low-level second protection signal enables the current. Optionally, when the relay model is selected as 250A, the lower threshold can be 55A, the upper threshold range is 270A~275A, and the limit threshold can be 500A.

[0093] See Figure 8In one embodiment, the single-threshold comparator 122 includes a second comparator U3A, a fourth resistor R9, a fifth resistor R10, a sixth resistor R11, a third capacitor C6, a fourth capacitor C7, a fifth capacitor C8, and a second reference source 122a. The output of the second reference source 122a is connected to the inverting input of the second comparator U3A, and the inverting input of the second comparator U3A is grounded through the third capacitor C6. The output of the sampling unit 110 is connected to the non-inverting input of the second comparator U3A through the fourth resistor R9, and the non-inverting input of the second comparator U3A is grounded through the fifth resistor R10. The fourth capacitor C7 and the fifth resistor R10 are connected in parallel. The output of the second comparator U3A is grounded through the sixth resistor R11 and the fifth capacitor C8, and the end of the sixth resistor R11 furthest from the second comparator U3A serves as the output of the single-threshold comparator 122 and is connected to the logic judgment unit 130.

[0094] It should be noted that when the sampled signal is transmitted to the protection unit 120, the single-threshold comparator 122, as described above, configures a suitable voltage division ratio by adjusting the resistance values ​​of the fourth resistor R9 and the fifth resistor R10, and configures a suitable reference voltage value (VREF) through the second reference source 122a to obtain the required limit threshold. When the sampled signal is greater than or equal to the limit threshold, the single-threshold comparator 122 outputs a high level; when the sampled signal is less than the limit threshold, the single-threshold comparator 122 outputs a low level.

[0095] It should be emphasized that the single-threshold comparator includes, but is not limited to, the circuit implementation described above. In other embodiments of this application, the circuit structure of the single-threshold comparator can be adjusted according to the actual situation, and this application does not impose any restrictions on it.

[0096] See Figure 7 and Figure 9 In one embodiment, when the logic judgment unit 130 includes a first NOR gate circuit 131 and a second NOR gate circuit 132, the two input terminals of the first NOR gate circuit 131 are respectively connected to the second output terminal of the controller 100 and the output terminal of the non-inverting hysteresis comparator 121, for receiving the first protection signal and the control signal and outputting an intermediate signal. The two input terminals of the second NOR gate circuit 132 are respectively connected to the output terminal of the first NOR gate circuit 131 and the output terminal of the single-threshold comparator 122, for receiving the intermediate signal and the second protection signal and outputting a relay drive signal.

[0097] In one embodiment, the operation of the relay overload protection circuit includes at least the following scenarios: normal operation of the power-side circuit, overload operation of the power-side circuit, and extreme fault occurrence of the relay overload protection circuit. The following description, in conjunction with... Figure 7 and Figure 9The detailed structure of the relay overload protection circuit shown is explained in detail, illustrating the operation of the relay overload protection circuit under different conditions.

[0098] In the event of an extreme fault in the relay overload protection circuit, the sampling current value of the sampling signal is greater than the extreme threshold. At this time, the second protection signal output by the single threshold comparator 122 is high. Therefore, regardless of the output level of the in-phase hysteresis comparator 121, the relay drive signal output by the second NOR gate circuit 132 is low, and controls the relay 140 to disconnect, so as to protect the power side circuit from damage.

[0099] When the power-side circuit 150 is overloaded, the sampling current value of the sampling signal is between the upper threshold and the extreme threshold. At this time, the first protection signal output by the in-phase hysteresis comparator 121 is high, and the second protection signal output by the single-threshold comparator 122 is low. Therefore, the intermediate signal output by the first NOR gate circuit 131 is low, and the relay drive signal output by the second NOR gate circuit 132 is high, controlling the relay 140 to remain open, so as to avoid the relay 140 from disconnecting when the sampling current value is greater than the maximum cut-off current value of the relay 140, thereby reducing or even avoiding the risk of damage to the relay 140.

[0100] Meanwhile, it should be emphasized that when the power-side circuit 150 is overloaded, the controller 100 determines that a system fault has occurred in the power-side circuit 150 by sampling the current value and performs waveform blocking, stopping the transmission of power signals to the power-side circuit 150. The control signal output by the controller 100 to the logic judgment unit 130 is also low. During waveform blocking by the controller 100, as the power signal stops, the sampling current value obtained by the sampling unit 110 gradually decreases. When the sampling current value drops below the lower threshold (i.e., the rated current value of the relay 140), the first protection signal output by the in-phase hysteresis comparator 121 switches to a low level, and the control signal output by the controller 100 also becomes low. At this time, the intermediate signal output by the first NOR gate circuit 131 also switches to a high level, and the relay drive signal output by the second NOR gate circuit 132 switches to a low level, controlling the relay 140 to switch to the open state, thereby achieving safe disconnection of the relay 140, which helps to extend the service life of the relay 140 and reduce production costs.

[0101] When the sampling current value of the sampling signal is less than the lower threshold, the first protection signal output by the in-phase hysteresis comparator 121 is low, and the control signal output by the controller 100 is also low. At this time, the control signal is opposite to the intermediate signal, and the intermediate signal is opposite to the relay drive signal. That is, the control signal and the relay drive signal are in the same direction. The relay drive signal changes with the change of the control signal. The opening or closing of the relay 140 can be realized by the software program in the controller 100.

[0102] When the sampling current value of the sampling signal is between the lower threshold and the upper threshold, the level output characteristics and control response logic of each module can be analyzed according to the actual situation. The specific changes can be referred to Table 1 below.

[0103] Table 1 Figure 7 The corresponding changes in the level of different signals in the relay overload protection circuit

[0104]

[0105] Note: A represents the sampled current value, X1 represents the lower threshold, X2 represents the upper threshold, X3 represents the extreme threshold, H represents the high level state, L represents the low level state, and " / " indicates that the change in the level state of this signal will not affect the level state of the relay drive signal.

[0106] It should be noted that, in the relay overload protection circuit described above, the protection unit includes a non-inverting hysteresis comparator and a single-threshold comparator, and the logic judgment unit includes a first NOR gate circuit and a second-level NOR gate circuit. In other embodiments of this application, the specific structure of the protection unit and the logic judgment unit can be adjusted according to the actual situation, as long as it is ensured that the relay overload protection circuit can still achieve the same logic control function, so as to ensure that the relay overload protection circuit has the overload protection effect and the ability to cope with extreme faults.

[0107] See Figure 10 In one embodiment, the protection unit 120 may include a dual-threshold comparator 123, wherein the first-level threshold of the dual-threshold comparator 123 is less than the maximum cut-off current value of the relay 140, and the second-level threshold of the dual-threshold comparator 123 is the extreme overcurrent value of the power-side circuit 150; the dual-threshold comparator 123 is used to output an invalid protection signal when the sampled current value of the sampled signal is greater than the second-level threshold or less than the first-level threshold; it is also used to output an effective protection signal when the sampled current value is between the first-level threshold and the second-level threshold; wherein a low-level protection signal enables invalid protection, and a high-level protection signal enables effective protection.

[0108] See Figure 11In one embodiment, the dual-threshold comparator 123 includes a third comparator U4A, a fourth comparator U5A, a third reference source 123a, a fourth reference source 123b, a first diode D1, a second diode D2, multiple threshold resistors, and multiple threshold capacitors. The output of the third reference source 123a is connected to the non-inverting input of the third comparator U4A, and the non-inverting input of the third comparator U4A is grounded through the first threshold capacitor C9. The output of the sampling unit 110 is connected to the inverting input of the third comparator U4A through the first threshold resistor R12, and the inverting input of the third comparator U4A is grounded through the second threshold resistor R13. The second threshold capacitor C10 is connected in parallel with the second threshold resistor R13. The output of the fourth reference source 123b is connected to the inverting input of the fourth comparator U5A. The output of the fourth comparator U5A is connected to the inverting input of the fourth comparator U5A. The input terminal is grounded through the third threshold capacitor C11; the output terminal of the sampling unit 110 is connected to the non-inverting input terminal of the fourth comparator U5A through the third threshold resistor R14, the non-inverting input terminal of the fourth comparator U5A is grounded through the fourth threshold resistor R15, and the fourth threshold capacitor C12 is connected in parallel with the fourth threshold resistor R15; the output terminal of the third comparator U4A is connected to the negative terminal of the first diode D1 through the fifth threshold resistor R16, the output terminal of the fourth comparator U5A is connected to the negative terminal of the second diode D2 through the sixth threshold resistor R17, the positive terminal of the first diode D1 is connected to the positive terminal of the power supply (VCC) through the seventh threshold resistor R18, the positive terminal of the second diode D2 is grounded (GND) through the fifth threshold capacitor C13, and the positive terminals of the first diode D1 and the second diode D2 are connected and serve as the output terminal of the dual-threshold comparator 123.

[0109] It should be noted that when the sampled signal is transmitted to the protection unit 120, the dual-threshold comparator 123, as described above, configures a suitable voltage division ratio by adjusting the resistance values ​​of the first threshold resistor R12, the second threshold resistor R13, the third threshold resistor R14, and the fourth threshold resistor R15. It also configures suitable high reference voltage values ​​(VREFH) and low reference voltage values ​​(VREFL) by adjusting the circuit structures of the third reference source 123a and the fourth reference source 123b, thereby obtaining the required secondary and primary threshold values. When the sampled signal is between the primary and secondary threshold values, the dual-threshold comparator 123 outputs a high level; when the sampled signal is greater than the secondary threshold value or less than the primary threshold value, the dual-threshold comparator 123 outputs a low level.

[0110] It should be emphasized that the dual-threshold comparator includes, but is not limited to, the circuit implementation described above. In other embodiments of this application, the circuit structure of the dual-threshold comparator can be adjusted according to the actual situation, and this application does not impose any restrictions on it.

[0111] See Figure 12 In one embodiment, the logic judgment unit 130 includes an OR gate circuit, the two input terminals of which are respectively connected to the second output terminal of the controller 100 and the output terminal of the dual threshold comparator 123, and the output terminal of the OR gate circuit is connected to the input terminal of the relay 140.

[0112] In one embodiment, the operation of the relay overload protection circuit includes at least the following scenarios: normal operation of the power-side circuit, overload operation of the power-side circuit, and extreme fault occurrence of the relay overload protection circuit. The following description, in conjunction with... Figure 10 and Figure 12 The detailed structure of the relay overload protection circuit shown is explained in detail, illustrating the operation of the relay overload protection circuit under different conditions.

[0113] In the event of an extreme fault in the relay overload protection circuit, the sampling current value of the sampling signal is greater than the secondary threshold. When the controller 100 determines that an extreme fault has occurred in the power side circuit 150, the output control signal is low. The protection signal output by the protection unit 120 is also low. Therefore, the relay drive signal output by the logic judgment unit 130 is also low, and the relay 140 is controlled to disconnect to protect the power side circuit from damage.

[0114] When the power-side circuit 150 is overloaded, the sampling current value of the sampling signal is between the first-level threshold and the second-level threshold. At this time, the control signal output by the controller 100 is low, and the protection signal output by the dual-threshold comparator 123 is high. Therefore, the relay drive signal output by the logic judgment unit 130 is high, and the relay 140 is kept open to prevent the relay 140 from disconnecting when the sampling current value is greater than the maximum cut-off current value of the relay 140, thereby reducing or even avoiding the risk of damage to the relay 140.

[0115] Meanwhile, it should be emphasized that when the power-side circuit 150 experiences overload operation, the controller 100 determines a system fault in the power-side circuit 150 by sampling the current value and performs waveform blocking, stopping the transmission of power signals to the power-side circuit 150. During waveform blocking by the controller 100, as the power signal stops, the sampling current value obtained by the sampling unit 110 gradually decreases. When the sampling current value drops below the first-level threshold (i.e., the rated current value of the relay 140), the protection signal output by the dual-threshold comparator 123 switches to a low level. At this time, since the control signal output by the controller 100 is also low, the relay drive signal output by the logic judgment unit 130 switches to a low level along with the change in the protection signal, controlling the relay 140 to switch to the open state, thereby achieving safe disconnection of the relay 140, which helps to extend the service life of the relay 140 and reduce production costs.

[0116] When the power side circuit 150 is working normally, the sampling current value of the sampling signal is less than or equal to the first-level threshold (i.e., the maximum cutting current value of the relay 140). The protection signal output by the protection unit 120 is low level. The relay drive signal output by the logic judgment unit 130 changes with the change of the control signal output by the controller 100. The controller 100 controls the opening and closing of the relay 140.

[0117] It should be noted that, in the relay overload protection circuit described above, the combination structure of the protection unit including a dual-threshold comparator and the logic judgment unit including an OR gate circuit is one implementation of the relay overload protection circuit. In other embodiments of this application, the specific structure of the protection unit and the logic judgment unit can be adjusted according to the actual situation, as long as it is ensured that the relay overload protection circuit can still achieve the same logic control function, so as to ensure that the relay overload protection circuit has the overload protection effect and the ability to cope with extreme faults.

[0118] As described above, the relay overload protection circuit not only prevents damage caused by directly disconnecting the relay when a low-level overload fault occurs in the power-side circuit, but also ensures that the system response can be quickly cut off by shutting down the relay when extreme overcurrent faults occur in the power-side circuit. This improves the safety and reliability of the relay overload protection circuit and shortens its response time to overload faults and extreme overcurrent faults. Furthermore, the specific structure of the protection unit and logic judgment unit in this application can be adjusted according to actual needs, enhancing the flexibility and applicability of the relay overload protection circuit.

[0119] Accordingly, one embodiment of this application also provides an overload protection method, which uses the relay overload protection circuit described above for overload protection. The overload protection method includes: first, acquiring a sampling signal of the power-side circuit; the sampling signal is related to the operating parameters of the power-side circuit; then, when the sampling current value of the sampling signal is greater than a first threshold current and less than a second threshold current, keeping the relay on and stopping the output of the power signal to the power-side circuit; the first threshold current is the maximum cutting-off current value of the relay, and the second threshold current is the extreme overcurrent value of the power-side circuit; when the sampling current value drops to less than the first threshold current and the control signal is ineffective, controlling the relay to disconnect.

[0120] The overload protection method described above keeps the relay conducting when the sampled current value is greater than the first threshold current and less than the second threshold current, until the sampled current value drops to less than the first threshold current, at which point the relay is controlled to disconnect. This avoids the relay disconnecting directly when the maximum cutting-off current value is exceeded, thereby preventing damage to the relay and effectively improving the service life of the relay.

[0121] In one embodiment, the process of controlling the relay to disconnect when the sampled current value drops below a first threshold current and the control signal is ineffective includes: controlling the relay to disconnect when the sampled current value is between a third threshold current and a first threshold current and the control signal is ineffective, and controlling the relay to open when the control signal is effective, to ensure that the power side circuit in the relay overload protection circuit can operate normally; and controlling the relay to disconnect when the sampled current value drops below a third threshold current and the control signal is ineffective. Here, the third threshold current is the rated current value of the relay, and the third threshold current is less than the first threshold current.

[0122] In one embodiment, the overload protection method further includes: controlling the relay to disconnect when the sampled current value is greater than a second threshold current. It should be noted that when the sampled current value is greater than the second threshold current, the relay needs to be disconnected as quickly as possible to reduce or avoid damage to the power-side circuit or other structures in the relay overload protection circuit.

[0123] Accordingly, see Figure 13One embodiment of this application also provides an energy storage converter topology system, including an energy storage battery-side circuit 200, a power-side circuit 150, a control-side circuit 220, and a grid-side circuit 230; wherein, the power-side circuit 150 is connected to the energy storage battery-side circuit 200 via a DC contactor 210a; the control-side circuit 220 includes the relay overload protection circuit described above, or executes the overload protection method described above; the grid-side circuit 230 is connected to the power-side circuit 150 via a relay 140 in the relay overload protection circuit (not shown in the figure). In other embodiments of this application, the specific structure of the energy storage converter topology system can be adjusted according to actual needs, and this application does not impose any limitations on it.

[0124] During the normal startup of the energy storage converter topology system, the relay closes, and the power-side circuit adjusts the charging / discharging power until the required value is reached; during the normal shutdown of the energy storage converter topology system, the power-side circuit first reduces the charging / discharging power, enters standby mode, and then disconnects the relay.

[0125] In the event of overload conditions (overload conditions include overcurrent, overvoltage and other faults) and extreme faults (extreme faults include control terminal abnormality, load short circuit, power tube shoot-through and other faults) in the energy storage converter topology system, the control side circuit will determine the fault type based on the sampled signal and adjust the opening and closing timing of the relays according to different fault types.

[0126] Optionally, in the event of an overload in the energy storage converter topology system, the control-side circuit keeps the relay open and immediately blocks the inverter or rectifier control output from the power-side circuit. As the power-side circuit blocks the inverter or rectifier control output, the system current decreases, and the sampled current value collected by the control-side circuit also decreases. When the sampled current value drops to the relay's maximum cutoff current, the control-side circuit closes the relay to ensure it is not damaged. Optionally, in the event of an extreme fault in the energy storage converter topology system, the control-side circuit immediately closes the relay to ensure that other circuit structures in the energy storage converter topology system are not damaged, preventing more serious safety accidents.

[0127] In summary, this application provides a relay overload protection circuit and method, as well as an energy storage converter topology system. The sampling unit collects operating parameters of the power-side circuit and outputs sampling signals. The protection unit and controller determine whether an overload has occurred in the power-side circuit based on the sampling signals, and respectively input protection signals and control signals to the logic judgment unit. The logic judgment unit outputs relay drive signals based on the protection signals and control signals to control the relay's opening or closing, thereby achieving overload protection for the relay and reducing or avoiding the risk of relay damage.

[0128] In the description of this specification, the references to terms such as "some embodiments," "other embodiments," "ideal embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example that are included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0129] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features of the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0130] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A relay overload protection circuit, characterized in that, include: A controller, wherein the first output terminal of the controller is connected to the input terminal of a power-side circuit for sending a power signal to the power-side circuit; A sampling unit, the input terminal of which is connected to the output terminal of the power-side circuit, and the output terminal of which is connected to the input terminal of the controller, is used to collect the operating parameters of the power-side circuit and output a sampling signal according to the operating parameters; A protection unit, wherein the input terminal of the protection unit is connected to the output terminal of the sampling unit, is used to receive the sampling signal and output a protection signal according to the sampling signal; A logic judgment unit, wherein the two input terminals of the logic judgment unit are respectively connected to the second output terminal of the controller and the output terminal of the sampling unit, and is used to output a relay drive signal according to the protection signal and the control signal, wherein the control signal is the signal transmitted by the controller to the logic judgment unit; A relay, wherein the input terminal of the relay is connected to the output terminal of the logic judgment unit, for receiving the relay drive signal and adjusting the opening or closing of the relay according to the relay drive signal; The protection unit includes a hysteresis comparator, wherein the upper threshold of the hysteresis comparator is the maximum cutting current value of the relay, and the lower threshold of the hysteresis comparator is the rated current value of the relay. The in-phase hysteresis comparator is used to output an inactive protection signal when the sampled current value of the sampled signal is less than the lower threshold; it is also used to output an active protection signal when the sampled current value is greater than the upper threshold, controlling the relay to remain in the open state and causing the controller to perform waveform blocking processing until the sampled current value drops below the lower threshold, at which point the relay is controlled to switch to the open state; wherein, a low-level protection signal inactively enables the protection signal, and a high-level protection signal actives the protection signal. Alternatively, the protection unit includes a dual-threshold comparator, wherein the first-level threshold of the dual-threshold comparator is less than the maximum interruption current value of the relay, and the second-level threshold of the dual-threshold comparator is the extreme overcurrent value of the power-side circuit; The dual-threshold comparator is used to output an invalid protection signal when the sampled current value of the sampled signal is greater than the secondary threshold or less than the primary threshold; it is also used to output an valid protection signal when the sampled current value is between the primary threshold and the secondary threshold, controlling the relay to remain in the open state and causing the controller to perform waveform blocking processing until the sampled current value drops below the primary threshold, at which point the relay is controlled to switch to the open state; wherein, a low-level protection signal invalidates the protection signal, and a high-level protection signal enables the protection signal.

2. The relay overload protection circuit according to claim 1, characterized in that, When the protection unit includes a hysteresis comparator, the logic judgment unit includes an OR gate circuit. The two inputs of the OR gate circuit are respectively connected to the second output of the controller and the output of the hysteresis comparator, and the output of the OR gate circuit is connected to the input of the relay.

3. The relay overload protection circuit according to claim 1, characterized in that, The protection unit includes a hysteresis comparator and a single-threshold comparator. The protection signal output by the protection unit includes a first protection signal output by the hysteresis comparator and a second protection signal output by the single-threshold comparator. The limit threshold of the single-threshold comparator is the extreme overcurrent value of the power-side circuit, and the limit threshold is greater than the upper threshold threshold. The in-phase hysteresis comparator is used to output an invalid first protection signal when the sampling current value of the sampling signal is less than the lower threshold; it is also used to output an valid first protection signal when the sampling current value is greater than the upper threshold. The single-threshold comparator is used to output an invalid second protection signal when the sampled current value is greater than or equal to the limit threshold; it is also used to output an valid second protection signal when the sampled current value is less than the limit threshold. Specifically, a low-level first protection signal is disabled, while a high-level first protection signal is enabled; a high-level second protection signal is disabled, while a low-level second protection signal is enabled.

4. The relay overload protection circuit according to claim 1 or 3, characterized in that, The in-phase hysteresis comparator includes a first comparator, a first resistor, a second resistor, a third resistor, a first capacitor, a second capacitor, and a first reference source; Wherein, the output terminal of the first reference source is connected to the inverting input terminal of the first comparator, and the inverting input terminal of the first comparator is grounded through the first capacitor; the output terminal of the sampling unit is connected to the non-inverting input terminal of the first comparator through the first resistor, the non-inverting input terminal of the first comparator is connected to the output terminal of the first comparator through the second resistor, the output terminal of the first comparator is grounded through the third resistor and the second capacitor, and the end of the third resistor away from the first comparator is connected to the logic judgment unit as the output terminal of the non-inverting hysteresis comparator.

5. The relay overload protection circuit according to claim 3, characterized in that, The single-threshold comparator includes a second comparator, a fourth resistor, a fifth resistor, a sixth resistor, a third capacitor, a fourth capacitor, a fifth capacitor, and a second reference source; The output of the second reference source is connected to the inverting input of the second comparator, and the inverting input of the second comparator is grounded through the third capacitor; the output of the sampling unit is connected to the non-inverting input of the second comparator through the fourth resistor, and the non-inverting input of the second comparator is grounded through the fifth resistor, and the fourth capacitor and the fifth resistor are connected in parallel; the output of the second comparator is grounded through the sixth resistor and the fifth capacitor, and the end of the sixth resistor furthest from the second comparator is connected to the logic judgment unit as the output of the single-threshold comparator.

6. The relay overload protection circuit according to claim 3, characterized in that, When the logic judgment unit includes a first NOR gate circuit and a second NOR gate circuit, the two input terminals of the first NOR gate circuit are respectively connected to the second output terminal of the controller and the output terminal of the non-inverting hysteresis comparator, and are used to receive the first protection signal and the control signal and output an intermediate signal. The two input terminals of the second NOR gate circuit are respectively connected to the output terminal of the first NOR gate circuit and the output terminal of the single-threshold comparator, and are used to receive the intermediate signal and the second protection signal and output the relay drive signal.

7. The relay overload protection circuit according to claim 1, characterized in that, The dual-threshold comparator includes a third comparator, a fourth comparator, a third reference source, a fourth reference source, a first diode, a second diode, multiple threshold resistors, and multiple threshold capacitors; The output of the third reference source is connected to the non-inverting input of the third comparator, and the non-inverting input of the third comparator is grounded through a first threshold capacitor; the output of the sampling unit is connected to the inverting input of the third comparator through a first threshold resistor, and the inverting input of the third comparator is grounded through a second threshold resistor, and the second threshold capacitor and the second threshold resistor are connected in parallel. The output terminal of the fourth reference source is connected to the inverting input terminal of the fourth comparator; the inverting input terminal of the fourth comparator is grounded through the third threshold capacitor; the output terminal of the sampling unit is connected to the non-inverting input terminal of the fourth comparator through the third threshold resistor; the non-inverting input terminal of the fourth comparator is grounded through the fourth threshold resistor; and the fourth threshold capacitor and the fourth threshold resistor are connected in parallel. The output of the third comparator is connected to the negative terminal of the first diode through a fifth threshold resistor, the output of the fourth comparator is connected to the negative terminal of the second diode through a sixth threshold resistor, the positive terminal of the first diode is connected to the positive terminal of the power supply through a seventh threshold resistor, the positive terminal of the second diode is grounded through a fifth threshold capacitor, and the positive terminals of the first diode and the second diode are connected and serve as the output of the dual-threshold comparator.

8. The relay overload protection circuit according to claim 1, characterized in that, When the protection unit includes a dual-threshold comparator, the logic judgment unit includes an OR gate circuit. The two input terminals of the OR gate circuit are respectively connected to the second output terminal of the controller and the output terminal of the dual-threshold comparator, and the output terminal of the OR gate circuit is connected to the input terminal of the relay.

9. The relay overload protection circuit according to claim 1, characterized in that, The sampling unit includes a sensor, an operational amplifier, multiple sampling resistors, and multiple sampling capacitors; The sensor converts the current signal from the power-side circuit into a differential voltage signal. This differential voltage signal is transmitted to the non-inverting input of the operational amplifier via a first sampling resistor. The non-inverting input of the operational amplifier is grounded via a second sampling resistor, and a first sampling capacitor is connected in parallel with the second sampling resistor. The sensor transmits the differential voltage signal to the inverting input of the operational amplifier via a third sampling resistor. The inverting input of the operational amplifier is connected to its output via a fourth sampling resistor, and a second sampling capacitor is connected in parallel with the fourth sampling resistor. The output of the operational amplifier is grounded via a fifth sampling resistor and the third sampling capacitor, and is connected to the input of the protection unit. The end of the fifth sampling resistor furthest from the operational amplifier is connected to the input of the controller.

10. The relay overload protection circuit according to claim 1, characterized in that, The operating parameters collected by the sampling unit include at least one of the following: inverter voltage parameters, grid voltage parameters, and AC current parameters.

11. The relay overload protection circuit according to claim 1, characterized in that, The power-side circuit includes a power drive unit and power loop devices; The power drive unit is used to issue a power drive signal according to the power signal, and the power circuit device adjusts the output power according to the power drive signal.

12. The relay overload protection circuit according to claim 11, characterized in that, The power circuit device includes at least one of an insulated gate bipolar transistor device and a silicon carbide power device.

13. An overload protection method for providing overload protection to a relay overload protection circuit as described in any one of claims 1 to 12, characterized in that, include: Acquire the sampling signal of the power-side circuit; the sampling signal is related to the operating parameters of the power-side circuit; If the sampling current value of the sampling signal is greater than the first threshold current and less than the second threshold current, the relay remains on and the power signal output to the power side circuit is stopped; the first threshold current is the maximum cut-off current value of the relay, and the second threshold current is the extreme overcurrent value of the power side circuit. If the sampled current value drops below the first threshold current and the control signal is ineffective, the relay is controlled to disconnect.

14. The overload protection method according to claim 13, characterized in that, The step of controlling the relay to disconnect when the sampled current value drops below the first threshold current and the control signal is disabled includes: When the sampled current value is between the third threshold current and the first threshold current, the relay is disconnected if the control signal enable is invalid, and the relay is turned on if the control signal enable is valid; the third threshold current is the rated current value of the relay, and the third threshold current is less than the first threshold current; If the sampled current value drops below the third threshold current and the control signal is disabled, the relay is controlled to disconnect.

15. The overload protection method according to claim 13, characterized in that, The overload protection method further includes: If the sampled current value is greater than the second threshold current, the relay is controlled to disconnect.

16. An energy storage converter topology system, characterized in that, include: Energy storage battery side circuit; The power-side circuit is connected to the energy storage battery-side circuit via a DC contactor; The control-side circuit includes a relay overload protection circuit as described in any one of claims 1 to 12, or performs an overload protection method as described in any one of claims 13 to 15; The grid-side circuit is connected to the power-side circuit via a relay in the relay overload protection circuit.

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