Control method for realizing zero pressure difference pull-in of input relay and related device

Abstract

The invention provides a control method for realizing zero pressure difference pull-in of an input relay and a related device. The method comprises the following steps: determining a target energy transfer strategy according to a working mode of a control system; controlling a post-stage voltage conversion circuit to transmit electric energy to the direct-current bus according to the target energy transmission strategy; and a driving signal is sent to the preceding-stage controller so as to indicate the preceding-stage controller to control the preceding-stage voltage conversion circuit to invert electric energy on the direct-current bus into three-phase alternating-current voltage, and when it is detected that the phase and amplitude of the three-phase alternating-current voltage are the same as the phase and amplitude of the power grid voltage, the input relay is controlled to be closed. Thus, when the input relay is controlled to be closed, the voltage states at the two ends of the contact are the same, zero-voltage-difference closing of the input relay is achieved, the phenomenon that the input relay is damaged due to the voltage difference between the two ends of the contact when the input relay is closed is avoided, and safety and reliability are improved.

Description

Technical Field

[0001] The present application relates to the field of electronic power, and in particular to a control method and related device for realizing zero-voltage difference pickup of an input relay. Background Art

[0002] With the rapid development of electronic power technology, the application scenarios of bidirectional AC / DC conversion control systems are increasing, such as in new energy vehicles for implementing V2G (Vehicle-to-Grid) technology. Among them, the input relays are located in each phase of the three-phase input, and the traditional control method is usually to directly attract the input relay when starting. However, since the grid voltage at the front end of the input relay changes instantaneously, there will be a voltage difference between the two ends of the contact of the input relay when it is attracted, which is easy to cause sparking, arcing and other phenomena, which will sharply reduce the life of the relay and affect the reliability of the relay. Summary of the invention

[0003] The embodiment of the present application provides a control method and related devices for achieving zero-pressure difference attraction of an input relay, so as to achieve zero-pressure difference attraction of the input relay, avoid damage to the relay due to the voltage difference between the two ends of the contacts when the input relay is attracted, and improve safety.

[0004] In a first aspect, an embodiment of the present application provides a control method for realizing zero-voltage differential pickup of an input relay, which is applied to a post-stage controller in a control system, wherein the control system includes the post-stage controller, a post-stage voltage conversion circuit, a pre-stage controller, and a pre-stage voltage conversion circuit, wherein the post-stage voltage conversion circuit is connected to the pre-stage voltage conversion circuit via a DC bus, the pre-stage voltage conversion circuit is connected to a power grid via an input relay, and the post-stage voltage conversion circuit is connected to a DC power supply terminal, wherein the method includes: Determine the target energy transmission strategy according to the working mode of the control system, the working mode includes a rectification mode and a grid-connected mode, the rectification mode refers to a working mode of taking power from the grid and converting it into direct current, and the grid-connected mode refers to a working mode of taking power from the DC power supply terminal and converting it into alternating current; Controlling the subsequent voltage conversion circuit to transmit electric energy to the DC bus according to the target energy transfer strategy; A drive signal is sent to the front-stage controller to instruct the front-stage controller to control the front-stage voltage conversion circuit to invert the electric energy on the DC bus into a three-phase AC voltage, and control the input relay to be energized when it is detected that the phase and amplitude of the three-phase AC voltage are the same as the phase and amplitude of the grid voltage.

[0005] In a second aspect, an embodiment of the present application provides a control device for realizing zero-voltage differential closure of an input relay, which is applied to a post-stage controller in a control system, wherein the control system includes the post-stage controller, a post-stage voltage conversion circuit, a pre-stage controller, and a pre-stage voltage conversion circuit, wherein the post-stage voltage conversion circuit is connected to the pre-stage voltage conversion circuit via a DC bus, the pre-stage voltage conversion circuit is connected to a power grid via an input relay, and the post-stage voltage conversion circuit is connected to a DC power supply terminal, wherein the device includes: A determination unit, used to determine a target energy transmission strategy according to an operating mode of the control system, wherein the operating mode includes a rectification mode and a grid-connected mode, wherein the rectification mode refers to an operating mode in which power is taken from the grid and converted into direct current, and the grid-connected mode refers to an operating mode in which power is taken from the DC power supply terminal and converted into alternating current; A control unit, configured to control the subsequent voltage conversion circuit to transmit electric energy to the DC bus according to the target energy transmission strategy; A signal sending unit is used to send a driving signal to the front-stage controller to instruct the front-stage controller to control the front-stage voltage conversion circuit to invert the electric energy on the DC bus into a three-phase AC voltage, and control the input relay to be energized when it is detected that the phase and amplitude of the three-phase AC voltage are the same as the phase and amplitude of the grid voltage.

[0006] In a third aspect, an embodiment of the present application provides a controller comprising a processor, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the processor, and the program comprises instructions for executing the steps in the first aspect of the embodiment of the present application.

[0007] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium having a computer program / instructions stored thereon, which, when executed by a processor, implement the steps in the first aspect of the embodiment of the present application.

[0008] It can be seen that in the embodiment of the present application, the rear-stage controller determines the target energy transmission strategy according to the working mode of the control system, and controls the rear-stage voltage conversion circuit to transmit electric energy to the DC bus according to the target energy transmission strategy, and finally sends a driving signal to the front-stage controller, so that the front-stage controller controls the front-stage voltage conversion circuit to invert the electric energy on the DC bus into a three-phase AC voltage, and controls the input relay to close when it detects that the phase and amplitude of the three-phase AC voltage are the same as the phase and amplitude of the grid voltage. In this way, when the input relay is controlled to be closed, the voltage states at both ends of its contacts are the same, realizing zero-voltage differential closure of the input relay, avoiding damage and failure of the input relay due to the voltage difference at both ends of the contacts when it is closed, and improving safety and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0010] Figure 1 It is a structural block diagram of a control system provided by an embodiment of the present application; Figure 2 is a structural block diagram of another control system provided in an embodiment of the present application; Figure 3 It is a flow chart of a control method for realizing zero-voltage differential pickup of an input relay provided in an embodiment of the present application; Figure 4 This is a structural block diagram of a DC power supply terminal provided in an embodiment of the present application; Figure 5 It is a structural block diagram of a control device for realizing zero-pressure difference pickup of an input relay provided in an embodiment of the present application; Figure 6 It is a structural block diagram of another control device for realizing zero-pressure difference pickup of an input relay provided in an embodiment of the present application; Figure 7 It is a structural block diagram of a controller provided in an embodiment of the present application. DETAILED DESCRIPTION

[0011] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0012] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.

[0013] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0014] At present, in order to achieve zero-voltage differential closure of input relays, the commonly used solution in the prior art is to collect the voltage of each phase, and control the relay of each phase to closure when the voltage of each phase passes through the zero point. However, due to the influence of the sampling circuit and the accuracy of the analog-to-digital converter (ADC), there will be errors in the judgment when the voltage passes through the zero point, and there will be a certain delay in the action of the input relay itself. Due to the coupling of various factors, there will still be a voltage difference between the two ends of the contacts of the input relay when it is closure, so it is extremely ideal to achieve zero-voltage differential closure based on the existing solution.

[0015] To solve the above problems, the embodiments of the present application provide a control method and related devices for realizing zero-voltage difference attraction of an input relay, aiming to use a front-stage voltage conversion circuit to invert the electric energy on the DC bus into a three-phase AC voltage with the same amplitude and phase as the grid voltage, so that the voltage difference across the input relay contacts is zero.

[0016] See also Figure 1 , Figure 1 is a structural block diagram of a control system provided by an embodiment of the present application. Figure 1As shown, the control system 10 includes a post-stage controller 11, a post-stage voltage conversion circuit 12, a front-stage controller 13 and a front-stage voltage conversion circuit 14, wherein the post-stage voltage conversion circuit 12 is connected to the front-stage voltage conversion circuit 14 via a DC bus 15, the front-stage voltage conversion circuit 14 is connected to a power grid 17 via an input relay 16, the post-stage voltage conversion circuit 12 is connected to a DC power supply terminal 18, and the post-stage controller 11 is in communication connection with the front-stage controller 13. In the embodiment of the present application, the control system 10 also includes a soft start circuit 19, one end of which is connected to the power grid 17 and the other end is connected to the DC bus 15, and is used to take power from the power grid 17 in a standby state and rectify it into DC power to supply power to the DC bus 15, so as to support the power demand of the front-stage controller 13, the post-stage controller 11 and other devices in a standby state. Among them, the post-stage controller 11 and the front-stage controller 13 can be specifically implemented as a DSP (Digital Signal Processor), the post-stage voltage conversion circuit 12 can be specifically implemented as a bidirectional DC-DC (direct current - direct current) main power topology such as a dual active bridge DAB (Dual Active Bridge) and a bidirectional full-bridge CLLC (Capacitor-Inductor-Inductor-Capacitor), and the front-stage voltage conversion circuit 14 can be specifically implemented as a bidirectional AC-DC (alternating current - direct current) main power topology such as a three-phase four-bridge arm, a three-phase three-bridge arm, and an active neutral point clamped three-level topology ANPC (Active Neutral Point Clamped).

[0017] For further information, see Figure 2 , Figure 2 is a structural block diagram of another control system provided in an embodiment of the present application. Figure 2As shown, the input relay 16 includes a first relay S1, a second relay S2 and a third relay S3, which are respectively located in the input of each phase of the three-phase to connect the power grid 17 and the front-stage voltage conversion circuit 14. Among them, the rear end of each phase input relay 16 is also provided with a corresponding capacitor and inductor, for example, the rear end of the first relay S1 is provided with a first capacitor C1 and a first inductor L1, the rear end of the second relay S2 is provided with a second capacitor C2 and a second inductor L2, and the rear end of the third relay S3 is provided with a third capacitor C3 and a third inductor L3. The first capacitor C1, the second capacitor C2 and the third capacitor C3 are used to store the alternating current generated by the front-stage voltage conversion circuit 14 to characterize the rear end voltage of each phase input relay 16. The DC bus 15 includes a fourth capacitor C4 and a fifth capacitor C5. It can be understood that the transmission of electric energy to the DC bus involved in the embodiment of the present application specifically refers to charging the fourth capacitor C4 and / or the fifth capacitor C5. The soft start circuit 19 may be specifically composed of a first resistor R1, a second resistor R2, a fourth relay S4, a fifth relay S5 and a rectifier bridge D1-D4. It is understandable that when the system is in a standby state, the first relay S1, the second relay S2, and the third relay S3 are all in a disconnected state, and the fourth relay S4 and the fifth relay S5 are normally closed. The soft start circuit 19 draws power from the power grid 17 and rectifies it into direct current to supply power to the fourth capacitor C4 and / or the fifth capacitor C5 on the DC bus 15 side, so as to support the power demand of some components in the system in the standby state.

[0018] It should be noted that the DC bus voltage that the current soft start circuit can theoretically obtain through the rectifier bridge is , where U1 refers to the DC bus voltage, and U2 refers to the root mean square voltage, that is, the effective value of the grid phase voltage at the front end of the input relay. For example, assuming that the grid phase voltage U2 at the front end of the input relay is 220V, then the DC bus voltage obtained by the soft start circuit is 622V, but because there is a resistor on the soft start circuit, and the DC bus capacitor needs to be stepped down through the auxiliary source transformer to supply power to loads such as the front and rear controllers, the actual DC bus voltage cannot reach the theoretical value. In this way, the DC bus voltage obtained by rectifying the grid voltage through the soft start circuit is not enough to invert and establish a three-phase AC voltage with the same amplitude as the grid voltage. Therefore, in order to ensure that there is enough energy on the DC bus capacitor to invert the AC voltage, it is necessary to reversely transmit energy to the DC bus capacitor through the rear voltage conversion circuit to support the DC bus voltage to invert the three-phase AC voltage.

[0019] See also Figure 3 , Figure 3 : is a flow chart of a control method for realizing zero-voltage differential pickup of an input relay provided in an embodiment of the present application, which is applied to Figure 1 In the post-stage controller 11 shown, as Figure 3As shown, the method includes: S301, determining a target energy transfer strategy according to the working mode of the control system.

[0020] The working mode includes a rectification mode and a grid-connected mode. The rectification mode refers to a working mode in which power is taken from the grid and converted into direct current, and the grid-connected mode refers to a working mode in which power is taken from the DC power supply terminal and converted into alternating current. Specifically, the post-stage controller can continuously monitor the power-on instruction when the control system is in the standby state, and when the power-on instruction is received, the working mode of the control system is determined according to the power-on instruction.

[0021] S302: Control the subsequent voltage conversion circuit to transmit electric energy to the DC bus according to the target energy transfer strategy.

[0022] S303, sending a driving signal to the pre-stage controller to instruct the pre-stage controller to control the pre-stage voltage conversion circuit to invert the electric energy on the DC bus into a three-phase AC voltage, and controlling the input relay to be energized when it is detected that the phase and amplitude of the three-phase AC voltage are the same as the phase and amplitude of the grid voltage.

[0023] Among them, after receiving the driving signal, the front-stage controller collects the grid voltage at the front end of the input relay through the hardware circuit and performs phase-locking operations, and then enables the front-stage voltage conversion circuit to use the DC bus voltage to invert the three-phase AC voltage on the X capacitor, and collects the AC instantaneous voltage on the X capacitor through the hardware circuit for loop control and amplitude and phase determination. When it is detected that the grid voltage and the three-phase AC voltage have the same phase and amplitude, the front-stage controller sends a control signal, thereby realizing the zero-voltage difference pull-in of the input relay.

[0024] After the rear-stage controller controls the rear-stage voltage conversion circuit to transmit electric energy to the DC bus according to the target energy transmission strategy, the DC bus voltage can be collected in real time through the voltage sampling circuit, and after detecting that the DC bus voltage reaches a preset standard value, a driving signal is sent to the front-stage controller. The preset standard value is used to indicate that the electric energy on the DC bus is sufficient to support the inversion into a three-phase AC voltage.

[0025] It can be seen that in the embodiment of the present application, the rear-stage controller determines the target energy transmission strategy according to the working mode of the control system, and controls the rear-stage voltage conversion circuit to transmit electric energy to the DC bus according to the target energy transmission strategy, and finally sends a driving signal to the front-stage controller, so that the front-stage controller controls the front-stage voltage conversion circuit to invert the electric energy on the DC bus into a three-phase AC voltage, and controls the input relay to close when it detects that the phase and amplitude of the three-phase AC voltage are the same as the phase and amplitude of the grid voltage. In this way, when the input relay is controlled to be closed, the voltage states at both ends of its contacts are the same, realizing zero-voltage differential closure of the input relay, avoiding damage and failure of the input relay due to the voltage difference at both ends of the contacts when it is closed, and improving safety and reliability.

[0026] In one possible example, the operating mode of the control system is the grid-connected mode, the DC power supply end includes a DC side capacitor, a pre-charging relay and a DC battery in a sufficient energy state, and the target energy transmission strategy is determined according to the operating mode of the control system, including: determining the target energy transmission strategy as a first energy transmission strategy, and the first energy transmission strategy is used to characterize that the post-stage controller controls the pre-charging relay to be energized, and controls the post-stage voltage conversion circuit to extract part of the energy of the DC battery to transmit electrical energy to the DC bus.

[0027] Among them, when the control system works in the grid-connected mode, its business control process is that the rear-stage voltage conversion circuit extracts the energy of the DC battery and inverts it into AC power through the front-stage voltage conversion circuit, and then connects it to the grid after the input relay is energized. Therefore, its DC side must be connected to a DC battery with sufficient energy. Figure 4 As shown, the DC power supply terminal 18 includes a DC side capacitor C6, a pre-charge relay S6 and a DC battery 181, and the DC battery 181 is in a sufficient energy state. Furthermore, the DC power supply terminal 18 also includes a third resistor R3 and a diode D5. As mentioned above, in order to achieve the zero-voltage difference pull-in of the input relay, the rear-stage voltage conversion circuit is required to take power from the DC power supply terminal 18 and reversely generate waves to charge the DC bus, so as to support the front-stage voltage conversion circuit to be able to invert and establish a three-phase AC voltage with the same phase and amplitude as the grid voltage on the X capacitor. In this example, since the DC power supply terminal 18 must include a DC battery 181 in a sufficient energy state in the grid-connected mode, the rear-stage controller can directly determine the target energy transmission strategy as the first energy transmission strategy, that is, control the pre-charge relay S6 to pull in, and control the rear-stage voltage conversion circuit to extract part of the capacity of the DC battery 181 to transmit enough electrical energy to the DC bus to support the inversion of three-phase AC power.

[0028] It can be seen that in this example, when the working mode of the control system is the grid-connected mode, the DC power supply end must include a DC battery in a sufficient energy state. At this time, the rear-stage controller can directly determine the target energy transfer strategy as the first energy transfer strategy to control the pre-charge relay to be energized, and extract part of the energy from the DC battery to charge the DC bus to support the front-stage voltage conversion circuit to invert and establish a three-phase AC voltage, ultimately achieving zero-voltage difference energization of the input relay, thereby improving safety.

[0029] In one possible example, the operating mode of the control system is the rectification mode, and determining the target energy transmission strategy according to the operating mode of the control system includes: obtaining a first sampled voltage, the first sampled voltage is used to characterize the battery state of the DC power supply end, the battery state includes a first state and a second state, the first state means that the DC power supply end includes a DC battery in a sufficient energy state, and the second state means that the DC power supply end does not include a DC battery in a sufficient energy state; determining the target energy transmission strategy according to the battery state of the DC power supply end.

[0030] Among them, when the control system works in the rectification mode, its business control process is that after the input relay is energized, the front-stage voltage conversion circuit takes power from the power grid and rectifies it into direct current to supply power to the DC bus. In the rectification mode, there are two battery states at the DC power supply end, namely the first state and the second state mentioned above. Among them, the DC power supply end does not include a DC battery in a sufficient energy state, which specifically means that the DC power supply end does not include a DC battery, or the DC power supply end includes a DC battery with insufficient energy. In this example, after determining that the working mode of the control system is the rectification mode, the back-stage controller obtains the first sampling voltage to determine the battery state of the DC power supply end. Specifically, when the first sampling voltage is greater than or equal to the first preset voltage, it is determined that the battery state of the DC power supply end is the first state; when the first sampling voltage is less than the first preset voltage, it is determined that the battery state of the DC power supply end is the second state.

[0031] It can be seen that in this example, when the working mode of the control system is the rectification mode, the post-stage controller obtains the first sampling voltage to determine the battery status of the DC power supply end, and then determines the target energy transmission strategy according to the battery status of the DC power supply end, so that it can adaptively determine the optimal energy transmission method according to the different battery status of the DC power supply end, thereby improving reliability.

[0032] In one possible example, the battery state of the DC power supply end is the first state, the DC power supply end includes a DC side capacitor, a pre-charging relay and a DC battery in a sufficient energy state, and determining the target energy transfer strategy according to the battery state of the DC power supply end includes: obtaining a second sampling voltage, the second sampling voltage is used to characterize the energy state of the DC side capacitor; determining the target energy transfer strategy according to the first sampling voltage and the second sampling voltage.

[0033] When the battery state of the DC power supply end is the first state, its circuit structure can be equivalent to Figure 4 For example, the DC power supply end includes a DC side capacitor C6, a pre-charge relay S6 and a DC battery 181 in a sufficient energy state. At this time, in order to avoid damage to the pre-charge relay S6 due to a large voltage difference between the two ends of the contacts when it is energized, it is necessary to detect and compare the voltages across its contacts to further determine the energy transfer strategy. It is understandable that the first sampling voltage is also used to characterize the rear end voltage of the pre-charge relay S6, and the second sampling voltage is also used to characterize the front end voltage of the pre-charge relay S6. By comparing the first sampling voltage and the second sampling voltage, it is determined whether to energize the pre-charge relay S6 during energy transfer, thereby determining the energy transfer strategy.

[0034] It can be seen that in this example, when the working mode of the control system is the rectification mode and the battery state of the DC power supply end is the first state, the post-stage controller obtains the second sampling voltage to determine the energy state of the DC side capacitor, and determines the target energy transfer strategy based on the first sampling voltage and the second sampling voltage, so that the energy transfer method can be determined according to the voltage state at both ends of the pre-charge relay contacts, thereby improving safety.

[0035] In a possible example, determining the target energy transfer strategy based on the first sampling voltage and the second sampling voltage includes: detecting that the difference between the first sampling voltage and the second sampling voltage is less than a preset value, and determining that the target energy transfer strategy is the first energy transfer strategy.

[0036] Among them, when the difference between the first sampling voltage and the second sampling voltage is less than the preset value, it indicates that the voltage difference between the two ends of the pre-charging relay contact is not large. At this time, the post-stage controller can control the pre-charging relay to be energized to control the post-stage voltage conversion circuit to draw power from the DC battery and reversely transmit power to the DC bus. The preset value is an empirical value obtained through statistical analysis of historical data. That is, in this example, when the working mode of the control system is the rectification mode, and the battery state of the DC power supply end is the first state, and the difference between the first sampling voltage and the second sampling voltage is less than the preset value, the energy transmission strategy of the post-stage controller is the same as the energy transmission strategy when the working mode of the control system is the grid-connected mode, both of which are the first energy transmission strategy.

[0037] It can be seen that in this example, when the difference between the first sampling voltage and the second sampling voltage is less than the preset value, it can be determined that the pre-charging relay meets the closure condition, and the post-stage controller determines the target energy transfer strategy as the first energy transfer strategy, controls the pre-charging relay to close, and controls the post-stage voltage conversion circuit to extract part of the energy of the DC battery to transmit electrical energy to the DC bus, so as to support the front-stage voltage conversion circuit to invert and establish a three-phase AC voltage, and finally realize the zero-voltage difference closure of the input relay, thereby improving safety.

[0038] In one possible example, determining the target energy transfer strategy based on the first sampling voltage and the second sampling voltage includes: detecting that the difference between the first sampling voltage and the second sampling voltage is greater than a preset value, determining that the target energy transfer strategy is the second energy transfer strategy, and the second energy transfer strategy is used to characterize that the post-stage controller controls the post-stage voltage conversion circuit to extract energy from the DC side capacitor to transmit electrical energy to the DC bus.

[0039] Among them, when the difference between the first sampling voltage and the second sampling voltage is greater than the preset value, it indicates that the voltage difference between the two ends of the pre-charge relay contact is large. If it is attracted at this time, it may cause damage to the pre-charge relay. Therefore, the post-stage controller determines that the target energy transfer strategy is the second energy transfer strategy, that is, the pre-charge relay is not attracted, and the energy of the DC side capacitor is directly extracted to transmit electrical energy to the DC bus. It can be understood that in this example, the DC battery charges the DC side capacitor C6 through the diode D5 and the third resistor R3, and the post-stage controller controls the post-stage voltage conversion circuit to reversely generate waves to extract the energy of the DC side capacitor C6 and transmit electrical energy to the DC bus.

[0040] It can be seen that in this example, when the difference between the first sampling voltage and the second sampling voltage is greater than the preset value, it can be determined that the pre-charge relay does not meet the closure condition, and the post-stage controller determines the target energy transfer strategy as the second energy transfer strategy, and controls the post-stage voltage conversion circuit to extract the energy of the DC side capacitor to transmit electrical energy to the DC bus, so as to support the front-stage voltage conversion circuit to invert and establish a three-phase AC voltage, and finally achieve zero-voltage difference closure of the input relay, thereby improving safety.

[0041] In one possible example, the battery state of the DC power supply end is the second state, and the DC power supply end includes a DC side capacitor. The target energy transmission strategy is determined according to the battery state of the DC power supply end, including: determining the target energy transmission strategy as a third energy transmission strategy, and the third energy transmission strategy is used to characterize that the post-stage controller extracts energy from the DC bus to charge the DC side capacitor, and extracts energy from the DC side capacitor to transmit electrical energy to the DC bus when it is detected that the second sampling voltage reaches the target voltage.

[0042] Among them, when the battery state of the DC power supply end is the second state, the DC power supply end does not include a DC battery in a state of sufficient power, that is, it is impossible to draw power from the DC battery to support the DC bus. At this time, the rear-stage controller determines that the target energy transmission strategy is the third energy transmission strategy, that is, first control the rear-stage voltage conversion circuit to forward energy transmission, extract energy from the DC bus to charge the DC side capacitor, until it is detected that the second sampling voltage reaches the target voltage, control the rear-stage voltage conversion circuit to reverse energy transmission, extract the energy of the DC side capacitor to transmit electrical energy to the DC bus. Among them, the target voltage is used to characterize the state in which the DC side capacitor reaches sufficient energy. It can be understood that in the forward energy transmission stage, the energy on the DC bus is the energy obtained by rectification of the soft start circuit. This part of energy cannot be inverted into a three-phase AC voltage in theory. Therefore, the rear-stage controller first controls the rear-stage voltage conversion circuit to forward energy transmission, and continuously transmits the energy obtained by rectification of the soft start circuit to the DC side capacitor, and then reversely transmits energy to charge the DC bus to support the front-stage voltage conversion circuit to invert and establish a three-phase AC voltage, and finally realize the zero-voltage difference attraction of the input relay.

[0043] It can be seen that in this example, when the battery state of the DC power supply end is in the second state, the post-stage controller determines that the target energy transmission strategy is the third energy transmission strategy, first controls the post-stage voltage conversion circuit to transmit energy in the forward direction, extracts energy from the DC bus to charge the DC side capacitor, and then reversely transmits energy to extract energy from the DC side capacitor to transmit electrical energy to the DC bus, so that the energy on the DC bus is sufficient to support the front-stage voltage conversion circuit to invert and establish a three-phase AC voltage, thereby achieving zero-voltage difference attraction of the input relay and improving safety.

[0044] In accordance with the above-mentioned embodiments, please refer to Figure 5 , Figure 5 is a structural block diagram of a control device for realizing zero-voltage differential pickup of an input relay provided in an embodiment of the present application, wherein the device is applied to Figure 1 In the post-stage controller 11 shown, the control device 50 for realizing zero-voltage difference closure of the input relay includes: a determination unit 501, which is used to determine a target energy transmission strategy according to the working mode of the control system, the working mode includes a rectification mode and a grid-connected mode, the rectification mode refers to a working mode of taking power from the power grid and converting it into direct current, and the grid-connected mode refers to a working mode of taking power from the DC power supply end and converting it into alternating current; a control unit 502, which is used to control the post-stage voltage conversion circuit to transmit electric energy to the DC bus according to the target energy transmission strategy; a signal sending unit 503, which is used to send a drive signal to the front-stage controller to instruct the front-stage controller to control the front-stage voltage conversion circuit to invert the electric energy on the DC bus into a three-phase AC voltage, and control the input relay to close when it is detected that the phase and amplitude of the three-phase AC voltage are the same as the phase and amplitude of the grid voltage.

[0045] In a possible example, the operating mode of the control system is the grid-connected mode, the DC power supply end includes a DC side capacitor, a pre-charging relay and a DC battery in a sufficient energy state, and in determining the target energy transmission strategy according to the operating mode of the control system, the determination unit 501 is specifically used to: determine that the target energy transmission strategy is a first energy transmission strategy, and the first energy transmission strategy is used to characterize that the post-stage controller controls the pre-charging relay to be energized, and controls the post-stage voltage conversion circuit to extract part of the energy of the DC battery to transmit electrical energy to the DC bus.

[0046] In a possible example, the operating mode of the control system is the rectification mode. In terms of determining the target energy transmission strategy according to the operating mode of the control system, the determination unit 501 is specifically used to: obtain a first sampled voltage, the first sampled voltage is used to characterize the battery state of the DC power supply end, the battery state includes a first state and a second state, the first state means that the DC power supply end includes a DC battery in a sufficient energy state, and the second state means that the DC power supply end does not include a DC battery in a sufficient energy state; determine the target energy transmission strategy according to the battery state of the DC power supply end.

[0047] In a possible example, the battery state of the DC power supply end is the first state, and the DC power supply end includes a DC side capacitor, a pre-charging relay, and a DC battery in a sufficient energy state. In terms of determining the target energy transfer strategy based on the battery state of the DC power supply end, the determination unit 501 is specifically used to: obtain a second sampling voltage, and the second sampling voltage is used to characterize the energy state of the DC side capacitor; determine the target energy transfer strategy based on the first sampling voltage and the second sampling voltage.

[0048] In one possible example, in determining the target energy transfer strategy based on the first sampling voltage and the second sampling voltage, the determination unit 501 is specifically used to: detect that the difference between the first sampling voltage and the second sampling voltage is less than a preset value, and determine that the target energy transfer strategy is the first energy transfer strategy.

[0049] In one possible example, in determining the target energy transfer strategy based on the first sampling voltage and the second sampling voltage, the determination unit 501 is specifically used to: detect that the difference between the first sampling voltage and the second sampling voltage is greater than a preset value, determine that the target energy transfer strategy is the second energy transfer strategy, and the second energy transfer strategy is used to characterize that the post-stage controller controls the post-stage voltage conversion circuit to extract energy from the DC side capacitor to transmit electrical energy to the DC bus.

[0050] In one possible example, the battery state of the DC power supply end is the second state, and the DC power supply end includes a DC side capacitor. In terms of determining the target energy transmission strategy according to the battery state of the DC power supply end, the determination unit 501 is specifically used to: determine that the target energy transmission strategy is a third energy transmission strategy, and the third energy transmission strategy is used to characterize that the post-stage controller extracts energy from the DC bus to charge the DC side capacitor, and extracts energy from the DC side capacitor to transmit electrical energy to the DC bus when it is detected that the second sampling voltage reaches the target voltage.

[0051] It can be understood that since the method embodiment and the device embodiment are different presentation forms of the same technical concept, the content of the method embodiment part in this application should be synchronously adapted to the device embodiment part and will not be repeated here.

[0052] In the case of an integrated unit, such as Figure 6 As shown, Figure 6 is a structural block diagram of another control device for realizing zero-voltage differential pickup of an input relay provided in an embodiment of the present application. Figure 6 In the embodiment, the control device 50 for realizing zero-pressure difference closure of the input relay includes: a processing module 52 and a communication module 51. The processing module 52 is used to control and manage the actions of the control device for realizing zero-pressure difference closure of the input relay, for example, to execute the steps of the determination unit 501, the control unit 502 and the signal sending unit 503, and / or to execute other processes of the technology described in this article. The communication module 51 is used to support the interaction between the control device for realizing zero-pressure difference closure of the input relay and other devices. Figure 6 As shown, the control device for realizing zero-pressure difference pickup of the input relay may further include a storage module 53, and the storage module 53 is used to store program codes and data of the control device 50 for realizing zero-pressure difference pickup of the input relay.

[0053] Among them, all relevant contents of each scenario involved in the above method embodiment can be referred to the functional description of the corresponding functional module, and will not be repeated here. The above control device 50 for realizing zero-voltage differential pickup of the input relay can execute the above Figure 2 The control method for realizing zero-voltage difference closure of input relay is shown.

[0054] See also Figure 7 , Figure 7 is a structural block diagram of a controller provided in an embodiment of the present application. Figure 7As shown, the controller may include one or more of the following components: a processor 701, a memory 702 coupled to the processor 701, wherein the memory 702 may store one or more computer programs, and the one or more computer programs may be configured to implement the method described in the above embodiment when executed by one or more processors 701. The controller may specifically refer to the post-stage controller 11 involved in the above embodiment.

[0055] It can be understood that the DC-DC converter may include more or fewer structural elements than those in the above structural block diagram, which is not limited here.

[0056] An embodiment of the present application also provides a computer storage medium, on which a computer program / instruction is stored. When the computer program / instruction is executed by a processor, part or all of the steps of any method recorded in the above method embodiments are implemented.

[0057] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0058] In the several embodiments provided in the present application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device embodiments described above are merely schematic; for example, the division of the units is only a logical function division, and there may be other division methods in actual implementation; for example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0059] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0060] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may be physically included separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0061] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions without departing from the spirit and scope of the present invention, and can make various changes and modifications, including the combination of the above-mentioned different functions and implementation steps, including software and hardware implementation methods, all of which are within the scope of protection of the present invention.

Claims

1. A control method for realizing zero-voltage differential pickup of an input relay, characterized in that: A post-stage controller applied to a control system, the control system comprising the post-stage controller, a post-stage voltage conversion circuit, a front-stage controller and a front-stage voltage conversion circuit, the post-stage voltage conversion circuit being connected to the front-stage voltage conversion circuit via a DC bus, the front-stage voltage conversion circuit being connected to a power grid via an input relay, the post-stage voltage conversion circuit being connected to a DC power supply terminal, the method comprising: Determine the target energy transmission strategy according to the working mode of the control system, the working mode includes a rectification mode and a grid-connected mode, the rectification mode refers to a working mode of taking power from the grid and converting it into direct current, and the grid-connected mode refers to a working mode of taking power from the DC power supply terminal and converting it into alternating current; Controlling the subsequent voltage conversion circuit to transmit electric energy to the DC bus according to the target energy transfer strategy; A drive signal is sent to the front-stage controller to instruct the front-stage controller to control the front-stage voltage conversion circuit to invert the electric energy on the DC bus into a three-phase AC voltage, and control the input relay to be energized when it is detected that the phase and amplitude of the three-phase AC voltage are the same as the phase and amplitude of the grid voltage.

2. The method according to claim 1, characterized in that The working mode of the control system is the grid-connected mode, the DC power supply end includes a DC side capacitor, a pre-charge relay and a DC battery in a sufficient energy state, and the target energy transmission strategy is determined according to the working mode of the control system, including: The target energy transfer strategy is determined to be a first energy transfer strategy, where the first energy transfer strategy is used to characterize that the subsequent-stage controller controls the pre-charging relay to be energized, and controls the subsequent-stage voltage conversion circuit to extract part of the energy of the DC battery to transmit electrical energy to the DC bus.

3. The method according to claim 2, characterized in that The working mode of the control system is the rectification mode, and the target energy transmission strategy is determined according to the working mode of the control system, including: Acquire a first sampled voltage, where the first sampled voltage is used to characterize a battery state of the DC power supply end, where the battery state includes a first state and a second state, where the first state means that the DC power supply end includes a DC battery in a sufficient energy state, and the second state means that the DC power supply end does not include a DC battery in a sufficient energy state; The target energy transfer strategy is determined according to the battery status of the DC power supply end.

4. The method according to claim 3, characterized in that The battery state of the DC power supply end is the first state, the DC power supply end includes a DC side capacitor, a pre-charge relay, and a DC battery in a sufficient energy state, and determining a target energy transmission strategy according to the battery state of the DC power supply end includes: Acquire a second sampled voltage, where the second sampled voltage is used to characterize the energy state of the DC link capacitor; A target energy transfer strategy is determined according to the first sampling voltage and the second sampling voltage.

5. The method according to claim 4, characterized in that The determining a target energy transfer strategy according to the first sampling voltage and the second sampling voltage includes: It is detected that the difference between the first sampling voltage and the second sampling voltage is smaller than a preset value, and the target energy transfer strategy is determined to be the first energy transfer strategy.

6. The method according to claim 4, characterized in that The determining a target energy transfer strategy according to the first sampling voltage and the second sampling voltage includes: It is detected that the difference between the first sampling voltage and the second sampling voltage is greater than a preset value, and the target energy transfer strategy is determined to be the second energy transfer strategy, and the second energy transfer strategy is used to characterize that the post-stage controller controls the post-stage voltage conversion circuit to extract energy from the DC side capacitor to transmit electrical energy to the DC bus.

7. The method according to claim 3, characterized in that The battery state of the DC power supply end is the second state, the DC power supply end includes a DC side capacitor, and determining the target energy transmission strategy according to the battery state of the DC power supply end includes: Determine that the target energy transfer strategy is a third energy transfer strategy, and the third energy transfer strategy is used to characterize that the post-stage controller extracts energy from the DC bus to charge the DC side capacitor, and extracts energy from the DC side capacitor to transmit electrical energy to the DC bus when it is detected that the second sampling voltage reaches the target voltage.

8. A control device for realizing zero-pressure difference pickup of an input relay, characterized in that: A rear-stage controller used in a control system, the control system comprising the rear-stage controller, a rear-stage voltage conversion circuit, a front-stage controller and a front-stage voltage conversion circuit, the rear-stage voltage conversion circuit being connected to the front-stage voltage conversion circuit via a DC bus, the front-stage voltage conversion circuit being connected to a power grid via an input relay, the rear-stage voltage conversion circuit being connected to a DC power supply terminal, the device comprising: A determination unit, used to determine a target energy transmission strategy according to an operating mode of the control system, wherein the operating mode includes a rectification mode and a grid-connected mode, wherein the rectification mode refers to an operating mode in which power is taken from the grid and converted into direct current, and the grid-connected mode refers to an operating mode in which power is taken from the DC power supply terminal and converted into alternating current; A control unit, configured to control the subsequent voltage conversion circuit to transmit electric energy to the DC bus according to the target energy transmission strategy; A signal sending unit is used to send a driving signal to the front-stage controller to instruct the front-stage controller to control the front-stage voltage conversion circuit to invert the electric energy on the DC bus into a three-phase AC voltage, and control the input relay to be energized when it is detected that the phase and amplitude of the three-phase AC voltage are the same as the phase and amplitude of the grid voltage.

9. A controller, characterized in that: The method comprises a processor, a memory and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the processor, and the programs include instructions for executing the steps in the method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program / instruction stored thereon, characterized in that: When the computer program / instructions are executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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