Converter and energy storage system

Abstract

The invention discloses a converter and an energy storage system, the converter comprises a direct current port, an alternating current port, an inverter circuit arranged between the direct current port and the alternating current port, a bus capacitor arranged on the direct current side of the inverter circuit, and a direct current side relay arranged between the direct current port and the bus capacitor; the alternating current side relay is arranged between the inverter circuit and the alternating current port; the instruction generation module is configured to output a first level signal under the condition that any one of the direct-current side relay and the alternating-current side relay is switched on; under the condition that the relay is fully turned off, the instruction generation module outputs a second level signal in response to the received discharge instruction; and the discharging module is configured to respond to the received second level signal, and the discharging module and the bus capacitor form a discharging loop. The corresponding discharging strategy can be executed according to the state of the converter, the converter is prevented from being damaged, and the safety of workers is guaranteed.

Description

Technical Field

[0001] The present application relates to the field of energy storage, and in particular to a converter and an energy storage system. Background Art

[0002] After the inverter is shut down normally or stops due to a fault, the energy of the internal capacitor needs a long time to be released to a safe voltage, which poses a safety hazard. If the maintenance personnel do not wait long enough and open the cover of the inverter for maintenance, it is easy to cause electric shock.

[0003] There is a solution in the related art for discharging the internal electrolytic capacitor of the converter after the converter is shut down. However, the existing discharge solution may cause the converter to be discharged by mistake when the converter is operating normally, which may cause damage to the converter and create a safety hazard. Summary of the invention

[0004] In order to solve the deficiencies of the prior art, this application adopts the following technical solutions: In a first aspect, the present application provides a converter, the converter comprising a DC port, an AC port, an inverter circuit arranged between the DC port and the AC port, and a bus capacitor arranged on the DC side of the inverter circuit, the converter further comprising: A DC side relay is arranged between the DC port and the bus capacitor; An AC side relay, arranged between the inverter circuit and the AC port; An instruction generation module, wherein the instruction generation module is configured to: when any one of the DC side relay and the AC side relay is turned on, the instruction generation module outputs a first level signal; when all the relays are turned off, the instruction generation module outputs a second level signal in response to receiving a discharge instruction; A discharge module is configured to form a discharge loop with the bus capacitor in response to receiving a second level signal.

[0005] In summary, the present application provides a converter. When any relay in the converter is turned on, the instruction generation module will only output a first level signal, and the discharge module will not discharge the bus capacitor, so as to avoid accidental discharge of the bus capacitor during the operation of the converter and damage to the converter. When all the relays in the converter are turned off, the instruction generation module will be able to output a second level signal in response to receiving the discharge instruction, and the discharge module will discharge the bus capacitor to achieve rapid release of the energy of the converter bus capacitor, reduce safety hazards, and ensure the safety of staff.

[0006] Furthermore, the instruction generation module includes a composite logic gate circuit, and the composite logic gate circuit is configured as follows: When any one of the DC-side relay and the AC-side relay is not turned off, the instruction generation module outputs a high-level first-level signal; when all relays are turned off, the instruction generation module outputs a low-level second-level signal in response to receiving a discharge instruction.

[0007] Furthermore, the composite logic gate circuit comprises: NOR gate circuit and NAND gate circuit, where: The input ends of the NOR gate circuit respectively receive control signals representing the states of the DC side relay and the AC side relay. When the relay is in the off state, the control signal is at a low level; when the relay is in the on state, the control signal is at a high level. The output end of the NOR gate circuit is connected to an input end of the NAND gate circuit, and the other input end of the NAND gate circuit receives the discharge instruction. The discharge instruction is at a high level. The output end of the NAND gate circuit serves as the output end of the instruction generation module.

[0008] Furthermore, the discharge module comprises: A first optical coupler, configured to change an on-off state based on an output signal of the instruction generation module; A first switch tube, wherein a control end of the first switch tube is coupled to a secondary side of the first optical coupler, and the first switch tube is connected to the bus capacitor via a discharge resistor to form a discharge loop; The discharge module is configured as follows: When the first optical coupler is turned off, the first switch tube is turned on to discharge the bus capacitor through the discharge resistor.

[0009] Furthermore, the discharge module further includes a second switch tube, a control end of the second switch tube is electrically connected to the output end of the instruction generation module, and the second switch tube is electrically connected to the primary side of the first optocoupler.

[0010] Furthermore, the discharge module further comprises a voltage stabilizing diode, the cathode of the voltage stabilizing diode being electrically connected to the positive end of the busbar via at least one resistor, and the anode of the voltage stabilizing diode being electrically connected to the negative end of the busbar; The first switch tube is a MOS tube, the drain of the first switch tube is electrically connected to the positive end of the bus through the discharge resistor, the source of the first switch tube is electrically connected to the negative end of the bus, and the gate of the first switch tube is electrically connected to the negative end of the voltage regulator diode.

[0011] Furthermore, the discharge resistor is arranged between the positive end of the busbar and the first switch tube; The converter further comprises: A discharge feedback module, the discharge feedback module includes a second optocoupler, a primary first end of the second optocoupler is electrically connected to a common node of the discharge resistor and the first switch tube, and a primary second end of the second optocoupler is electrically connected to a negative end of the busbar, The first end of the secondary side of the second optical coupler is used as a feedback signal output end and is electrically connected to a high-level reference signal. The second end of the secondary side of the second optical coupler is grounded.

[0012] Further, the DC side relay comprises: a first DC side relay and a second DC side relay, the first DC side relay is arranged between the DC port and the bus capacitor, and the second DC side relay is arranged between the DC port and the bus capacitor through at least one resistor; The AC side relay comprises: a first AC side relay and a second AC side relay, wherein the first AC side relay is arranged between the inverter circuit and the AC port, and the second AC side relay is arranged between the inverter circuit and the AC port through at least one resistor; Control signals representing the states of the first DC side relay, the second DC side relay, the first AC relay and the second AC relay are respectively input to the four input terminals of the NOR gate.

[0013] Furthermore, the converter further comprises a control device, wherein the control device is configured to control the converter according to the following process: Controlling the second AC side relay to close so as to pre-charge the bus capacitor in the first stage; Controlling the first AC side relay to close, controlling the second AC side relay to turn off, and controlling the second DC side relay to close, so as to pre-charge the bus capacitor in the second stage; The first DC side relay is controlled to be closed, and the second DC side relay is controlled to be turned off, so as to control the converter to start.

[0014] In a second aspect, the present application also provides an energy storage system, which includes the above-mentioned converter; the energy storage system has a higher safety factor. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1a A partial structural schematic diagram of a converter provided in one embodiment of the present application; Figure 1b A partial structural schematic diagram of a converter provided in another embodiment of the present application; Figure 2 A schematic diagram of the structure of an instruction generation module in a converter provided in an embodiment of the present application; Figure 3 A circuit diagram of a discharge module in a converter provided by an embodiment of the present application; Figure 4 A schematic diagram of a discharge feedback module circuit in a converter provided by an embodiment of the present application; Figure 5 A circuit diagram of a DC side relay and an AC side relay in a converter provided by an embodiment of the present application; Figure 6 A schematic diagram of the structure of an instruction generation module in a converter provided in another embodiment of the present application. DETAILED DESCRIPTION

[0016] The present application will be described in detail below in conjunction with the specific embodiments shown in the accompanying drawings, but these embodiments do not limit the present application, and any structural, methodological, or functional changes made by a person of ordinary skill in the art based on these embodiments are included in the protection scope of the present application. (Electrical) connection includes direct (electrical) connection and indirect (electrical) connection.

[0017] In order to solve the deficiencies of the prior art, in a first aspect, the present application provides a converter, the converter comprising a DC port, an AC port, an inverter circuit arranged between the DC port and the AC port, and a bus capacitor arranged on the DC side of the inverter circuit, the converter further comprising: A DC side relay is arranged between the DC port and the bus capacitor; The AC side relay is arranged between the inverter circuit and the AC port; The instruction generation module is configured to: when any one of the DC side relay and the AC side relay is turned on, the instruction generation module outputs a first level signal; when all the relays are turned off, the instruction generation module responds to receiving the discharge instruction and outputs a second level signal; The discharge module is configured to: in response to receiving the second level signal, the discharge module and the bus capacitor form a discharge loop.

[0018] Specifically, the converter includes a DC port, an AC port, and an inverter circuit disposed between the DC port and the AC port. The DC port can be connected to a battery, a DC source, and / or a DC appliance, and the AC port can be connected to an AC source and / or an AC appliance. For ease of description, the DC port is connected to the energy storage battery and the AC port is connected to the power grid in the embodiment of the present application.

[0019] refer to Figure 1a and Figure 1bThe converter also includes a DC side relay and an AC side relay, wherein the DC side relay is arranged between the DC port and the bus capacitor C1, and the DC side relay is used to control the on-off between the energy storage battery and the bus capacitor C1; the AC side relay is arranged between the AC port and the inverter circuit, and the AC side relay is used to control the on-off between the power grid and the inverter circuit.

[0020] The instruction generation module is configured to obtain a control signal representing the switch state of the DC side relay and the AC side relay. When all the DC side relays and the AC side relays are fully turned off, the converter is not in operation at this time, and the instruction generation module responds to the received discharge instruction and outputs a second level signal; the discharge module responds to receiving the second level signal, and the discharge circuit between the discharge module and the bus capacitor is turned on, and the discharge module performs a discharge operation, discharges the bus capacitor of the converter, and quickly releases the energy of the bus capacitor of the converter to a safe voltage, thereby reducing safety hazards.

[0021] When any of the DC-side relays and the AC-side relays is turned on, it indicates that the converter is in operation (including pre-charging). At this time, the instruction generation module will only output the first level signal (that is, even if the instruction generation module receives the discharge instruction, the instruction generation module will still output the first level signal and will not output the second level signal). The discharge module responds to the first level signal, the discharge circuit between the discharge module and the bus capacitor is disconnected, and the discharge module does not perform discharge work to avoid accidental discharge of the converter in operation.

[0022] As an optional implementation, the instruction generation module includes a composite logic gate circuit, and the composite logic gate circuit is configured as follows: when any one of the DC side relays and the AC side relays is turned on, the instruction generation module outputs a high-level first-level signal; when all the relays are turned off, the instruction generation module outputs a low-level second-level signal in response to receiving a discharge instruction.

[0023] Specifically, when any one of the DC side relays and the AC side relays is turned on, it indicates that the converter is in operation. At this time, the instruction generation module will only output a high-level first-level signal, and the discharge module will respond to the high-level first-level signal. The discharge circuit between the discharge module and the bus capacitor is disconnected, and the discharge module does not perform discharge work to avoid accidental discharge of the converter in operation.

[0024] When all the DC-side relays and AC-side relays are fully turned off, indicating that the converter is not in operation at this time, the instruction generation module responds to receiving the discharge instruction, the instruction generation module outputs a low-level second-level signal, the discharge module responds to receiving the low-level second-level signal, the discharge circuit between the discharge module and the bus capacitor is connected, the discharge module performs discharge work, discharges the bus capacitor of the converter, and quickly releases the energy of the bus capacitor of the converter to a safe voltage, thereby reducing safety hazards.

[0025] Further, as an optional implementation, the composite logic gate circuit includes: a NOR gate circuit and a NAND gate circuit. Among them, the input end of the NOR gate circuit receives control signals representing the states of the DC side relay and the AC side relay respectively. In one embodiment, when the relay is in the off state, the control signal is at a low level; when the relay is in the on state, the control signal is at a high level; the control signal can also be a driving control signal of the relay. The output end of the NOR gate circuit is connected to an input end of the NAND gate circuit, the other input end of the NAND gate circuit receives the discharge instruction, and the output end of the NAND gate circuit serves as the output end of the instruction generation module.

[0026] Specifically, Figure 2 As shown, the instruction generation module includes a DSP (Digital Signal Processor) and a CPLD (Complex Programmable Logic Device). The CPLD includes a NOR gate circuit and a NAND gate circuit. The output end of the DSP is connected to the input end of the NOR gate circuit, so that the DSP can input the control signal representing the state of the DC side relay and the AC side relay into the NOR gate circuit. The other output end of the DSP is connected to an input end of the NAND gate circuit, so that the DSP can output a discharge instruction to the NAND gate circuit and set the discharge instruction to a high level.

[0027] like Figure 2 As shown, the output end of the NAND gate circuit is used as the output end of the instruction generation module, and the output end of the NAND gate circuit is marked as 11. The DSP also includes an input end 12, through which the DSP can obtain the working state of the discharge circuit.

[0028] When the relay is in the off state, the control signal representing the state of the relay is a low-level signal, recorded as 0. When the DC-side relay and the AC-side relay are all off, the input terminals of the NOR gate circuit are all low-level signals. According to the truth table of the NOR gate circuit, it is easy to know that the output of the NOR gate circuit is a high-level signal at this time. Since the output terminal of the NOR gate is connected to the ch1 input terminal of the NAND gate, the ch1 input terminal of the NAND gate receives a high-level signal. At this time, if the ch2 input terminal of the NAND gate receives a discharge instruction (high level), the output terminal 11 of the NAND gate circuit will output a low-level signal, triggering the discharge module to perform the discharge operation.

[0029] When the relay is in the on state, the control signal representing the state of the relay is a high level signal, recorded as 1. When any of the DC side relays and the AC side relays is on, at least one of the input ends of the NOR gate circuit receives a high level signal. According to the truth table of the NOR gate circuit, it is easy to know that the output of the NOR gate circuit is a low level signal at this time. Since the output end of the NOR gate circuit is connected to the ch1 input end of the NAND gate circuit, the ch1 input end of the NAND gate receives a low level signal. At this time, even if the ch2 input end of the NAND gate circuit receives a discharge instruction (high level), the output end 11 of the NAND gate circuit will still output a high level signal, and the discharge module cannot be triggered to perform the discharge operation, thereby avoiding false discharge when the converter is working.

[0030] As an optional implementation, the discharge module includes: a first optocoupler and a first switch tube. The first optocoupler is configured to change the on-off state based on the output signal of the instruction generation module, the control end of the first switch tube is coupled to the secondary side of the first optocoupler, and the first switch tube is connected to the bus capacitor through a discharge resistor to form a discharge loop. The discharge module is configured as follows: when the first optocoupler is turned off, the first switch tube is turned on to discharge the bus capacitor through the discharge resistor.

[0031] Specifically, Figure 3As shown, the first switch tube Q1 is a MOS tube, the drain of the first switch tube Q1 is electrically connected to the positive end of the bus through the discharge resistor R2, the source of the first switch tube Q1 is electrically connected to the negative end of the bus, and the gate of the first switch tube Q1 is connected to the first end of the secondary side of the first optocoupler OPT1. In addition, the first end of the secondary side of the first optocoupler OPT1 is connected to the positive end of the bus through the resistor R3, and the second end of the secondary side of the first optocoupler OPT1 is connected to the negative end of the bus. The first optocoupler OPT1 is configured to change the on-off state based on the output signal of the instruction generation module. When the instruction generation module outputs a high-level first-level signal, the first optocoupler OPT1 is turned on, the light-emitting diode of the primary side of the first optocoupler OPT1 emits light, the secondary side of the first optocoupler OPT1 is turned on, the gate voltage of the first switch tube Q1 is pulled down, the first switch tube Q1 is disconnected, the discharge circuit between the discharge module and the bus capacitor is disconnected, and the bus capacitor is not discharged. When the instruction generation module outputs a low-level second level signal, the first optical coupler OPT1 is turned off, the first switch tube Q1 is turned on, and the discharge loop between the discharge module and the bus capacitor is turned on to discharge the bus capacitor.

[0032] As an optional implementation, the discharge module further includes a second switch tube, a control end of the second switch tube is electrically connected to the output end of the instruction generation module, and the second switch tube is electrically connected to the primary side of the first optocoupler.

[0033] Specifically, Figure 3 As shown, the control end of the second switch tube Q2 is electrically connected to the output end 11 of the instruction generation module through the resistor R5, the first end of the second switch tube Q2 is electrically connected to the primary side of the first optical coupler OPT1, and the second end of the second switch tube Q2 is grounded. The second switch tube can be an NPN transistor.

[0034] When the instruction generation module outputs a high-level first-level signal, the second switch tube Q2 is turned on, and then the first optocoupler OPT1 is turned on. When the instruction generation module outputs a low-level second-level signal, the second switch tube Q2 is turned off, and then the first optocoupler OPT1 is turned off.

[0035] As an optional implementation, the discharge module further includes a voltage regulator diode, the cathode of the voltage regulator diode is electrically connected to the positive end of the busbar through at least one resistor, and the cathode of the voltage regulator diode is also electrically connected to the gate of the first switch tube, and the anode of the voltage regulator diode is electrically connected to the negative end of the busbar. In this embodiment, the conduction drive voltage of the first switch tube is generated by the voltage regulator diode and the resistor connected in series at the positive and negative ends of the bus capacitor, and the conduction drive voltage is also provided by the bus capacitor, which is conducive to further increasing the energy consumption of the bus capacitor and further improving the discharge speed of the bus capacitor.

[0036] Specifically, Figure 3As shown, the cathode of the Zener diode D1 is electrically connected to the positive end of the bus through the resistor R3, and the anode of the Zener diode D1 is electrically connected to the negative end of the bus; the gate of the first switch tube Q1 is electrically connected to the negative end of the Zener diode D1.

[0037] When the converter is powered off and needs to discharge the bus capacitor, the instruction generation module outputs a low-level second-level signal to the control end of the second switch tube Q2. At this time, the second switch tube Q2 is disconnected, the first optical coupler OPT1 is turned off, the voltage-stabilizing diode D1 and the resistor R3 divide the bus voltage, and there is a voltage at both ends of the voltage-stabilizing diode D1, thereby generating a driving voltage at the gate of the first switch tube Q1, causing the first switch tube Q1 to turn on, and the discharge circuit between the discharge module and the bus capacitor is turned on, thereby discharging the bus capacitor. In this way, the bus capacitor can be triggered to discharge when the converter needs to discharge, ensuring safety; and the driving energy of the first switch tube Q1 also comes from the bus capacitor, which is conducive to further increasing the energy consumption on the bus capacitor and further improving the discharge speed of the bus capacitor.

[0038] As an optional implementation, Figure 3 As shown, the discharge resistor R2 is arranged between the positive end of the bus and the first switch tube Q1. As another optional implementation, the discharge resistor R2 can also be arranged between the negative end of the bus and the first switch tube Q1.

[0039] At the same time, it should be noted that in the above, the first level signal is a high level and the second level signal is a low level. It is easy to understand that the instruction generation module and the discharge module can also be modified and designed accordingly, so that the first level signal is a low level signal and the second level signal is a high level signal. At this time, the composite logic gate circuit will be configured as follows: when any relay is turned on, the instruction generation module outputs a low-level first level signal; when the relay is fully turned off, the instruction generation module responds to receiving the discharge instruction and outputs a high-level second level signal. The discharge module is configured as follows: in response to receiving a high-level second level signal, the discharge module and the bus capacitor form a discharge loop. The corresponding logical settings, such as the selection of the first switch tube and the high and low levels of each signal need to be reconfigured within the essential design concept of the technical solution provided by the present invention, and should belong to the protection scope of this application.

[0040] As an optional implementation, the converter provided by the present application also includes a discharge feedback module. The discharge feedback module includes a second optocoupler, the first end of the primary side of the second optocoupler is electrically connected to the common node of the discharge resistor and the first switch tube, and the second end of the primary side of the second optocoupler is electrically connected to the negative end of the bus. The first end of the secondary side of the second optocoupler is used as a feedback signal output end, electrically connected to a high-level reference signal, and the second end of the secondary side of the second optocoupler is grounded.

[0041] Combination Figure 3 and Figure 4 , the primary first end 13 of the second optocoupler OPT2 is electrically connected to the common node n1 between the discharge resistor R2 and the first switch tube Q1, and the primary second end of the second optocoupler OPT2 is electrically connected to the negative end of the bus. The secondary first end 14 of the second optocoupler OPT2 serves as a feedback signal output terminal, and is electrically connected to a high-level reference signal through a resistor R7. In addition, in the embodiment of the present application, the DSP of the instruction generation module has an output terminal 12, the secondary first end 14 of the second optocoupler OPT2 is electrically connected to the DSP input terminal 12 of the instruction generation module, and the secondary second end of the second optocoupler OPT2 is grounded. The DSP can determine whether to discharge by judging the level of the signal received at the input terminal 12.

[0042] When the first switch tube Q1 in the discharge module is turned on (at this time, the discharge loop formed by the discharge module and the bus capacitor is turned on), the first end 13 of the primary side of the second optocoupler OPT2 is at the same potential as the second end, the light-emitting diode of the primary side of the second optocoupler OPT2 does not emit light, the second optocoupler OPT2 is turned off, and the first end 14 of the secondary side of the second optocoupler OPT2 outputs a high-level signal; that is, when the DSP input end 12 receives a high-level signal, it indicates that the bus capacitor is discharging. When the first switch tube Q1 is turned off, the first end 13 of the primary side of the second optocoupler OPT2 is at the same potential as the positive end of the bus, the light-emitting diode of the primary side of the second optocoupler OPT2 emits light, the second optocoupler OPT2 is turned on, and the first end 14 of the secondary side of the second optocoupler OPT2 outputs a low-level signal; that is, when the DSP input end 12 receives a low-level signal, it indicates that the bus capacitor is not discharging. The DSP of the instruction generation module can determine whether the discharge module is discharging the bus capacitor by detecting the level signal output by the first end 14 of the secondary side of the second optocoupler OPT2. Furthermore, the DSP can control a display device (such as an LED light) to display according to the level signal output by the secondary first end 14 of the second optocoupler OPT2, so that maintenance personnel can know whether the bus capacitor is discharging or whether the discharge is complete, which is beneficial to further improve safety.

[0043] As an optional implementation, the DC side relay includes: a first DC side relay and a second DC side relay, the first DC side relay is arranged between the DC port and the bus capacitor, and the second DC side relay is arranged between the DC port and the bus capacitor through a resistor; the AC side relay includes: a first AC side relay and a second AC side relay, the first AC side relay is arranged between the inverter circuit and the AC port, and the second AC side relay is arranged between the inverter circuit and the AC port through a resistor.

[0044] Specifically, Figure 5As shown, the first DC side relay K1 is arranged at the positive pole of the busbar, and the second DC side relay K2 is arranged in series with a resistor at the positive pole of the busbar, and the series branch of the second DC side relay K2 and the resistor in series is connected in parallel with the first DC side relay K1. Alternatively, the first DC side relay K1 can also be arranged at the negative pole of the busbar, and the second DC side relay K2 is arranged in series with a resistor at the negative pole of the busbar, and the series branch of the second DC side relay K2 and the resistor in series is connected in parallel with the first DC side relay K1.

[0045] The first AC side relay includes relay K4, relay K6, and relay K8, which are respectively arranged between the corresponding phase line and the AC port of the inverter circuit. The second AC side relay includes relay K3, relay K5, and relay K7. Relay K3, relay K5, and relay K7 are each connected in series with a resistor. The relay K3 branch connected in series with the resistor, the relay K5 branch connected in series with the resistor, and the relay K7 branch connected in series with the resistor are respectively connected in parallel with relay K4, relay K6, and relay K8, that is, they are also arranged between the corresponding phase line and the AC port of the inverter circuit. The resistor connected in series with each relay is used to limit the charging current of the bus capacitor to protect the entire circuit.

[0046] As an optional implementation, Figure 6 As shown, control signals representing the states of the first DC side relay, the second DC side relay, the first AC side relay and the second AC side relay are respectively input to the four input terminals of the NOR gate circuit. The NOR gate circuit performs logic operations according to the control signals representing the states of the above relays.

[0047] As an implementation, the converter provided in the present application further includes a control device, which is configured to control the converter according to the following process: Phase 1: Control the second AC side relay to close and pre-charge the bus capacitor in the first phase.

[0048] Specifically, the first stage is: when starting the converter, the control device controls the second AC side relay K3, relay K5, and relay K7 to close, and the AC side pre-charges the bus capacitor C1 in the first stage.

[0049] The second stage: control the first AC side relay to close, control the second AC side relay to turn off, and control the second DC side relay to close, so as to pre-charge the bus capacitor in the second stage.

[0050] Specifically, the second stage is: after completing the first stage pre-charging, the control device controls the first AC side relay K4, relay K6, and relay K8 to close, and controls the second AC side relay K3, relay K5, and relay K7 to turn off. At the same time, the control device also controls the second DC side relay K2 to close, and pre-charges the bus capacitor C1 in the second stage.

[0051] The third stage: controlling the first DC side relay to close and controlling the second DC side relay to turn off to control the start-up of the converter.

[0052] Specifically, the third stage is: after completing the second stage pre-charging, the control device controls the first DC side relay K1 to close, and controls the second DC side relay K2 to turn off, thereby completing the start-up work of the converter.

[0053] Through the above control process, during the start-up phase of the converter, at least one of the DC-side relay and the AC-side relay remains in a closed state, at least one input terminal of the NOR gate circuit receives a high-level signal, and through logical operations, the output of the NOR gate circuit is a low-level signal, and one input terminal signal ch1 of the NAND gate circuit is a low-level signal. Even if the ch2 input terminal of the NAND gate receives a discharge instruction (high level), the NAND gate will still output a high-level signal and cannot trigger the discharge module to perform the discharge operation, thereby avoiding false discharge when the converter is working; thereby preventing false discharge triggering at various stages of startup and improving system safety.

[0054] When the converter is working normally, the first AC side relay K4, relay K6, relay K8 and the first DC side relay K1 are closed. At this time, the AC side relay signal and the DC side relay signal of the DSP are both high-level signals. Through logical operation, the output of the NOR gate circuit is a low-level signal, and the input terminal signal ch1 of the NAND gate circuit is a low-level signal. At this time, even if the ch2 input terminal of the NAND gate receives a discharge instruction (high level), the NAND gate will still output a high-level signal and cannot trigger the discharge module to perform the discharge operation, thereby avoiding false discharge when the converter is working.

[0055] According to the above description, the converter provided by the embodiment of the present application will not discharge by mistake during the startup phase and the normal operation phase, and safety can be ensured. After the converter is shut down, a discharge instruction can be actively sent to control the discharge module to discharge the bus capacitor, thereby realizing the rapid release of the converter bus capacitor energy, reducing safety hazards, and ensuring the safety of the staff. In addition, when the converter fails unexpectedly, the discharge module can be triggered to discharge the bus capacitor, thereby realizing the rapid release of the converter bus capacitor energy, reducing safety hazards, and ensuring the safety of the staff.

[0056] On the second aspect, the present application also provides an energy storage system, which includes the inverter described above, and can execute corresponding discharge strategies when the inverter is in operation, shutdown, or fault state, so as to avoid damage to the inverter and ensure the safety of the staff.

[0057] It will be appreciated that the word "exemplary" as used herein means "serving as an example, instance, or illustration". Any embodiment described as "exemplary" is not necessarily preferred or superior to other embodiments and / or does not exclude the combination of features of other embodiments. It will be appreciated that certain features of the present application described in the context of separate embodiments for the sake of clarity may also be provided in a single embodiment by combination. Conversely, various features of the present application described in the context of a single embodiment for the sake of clarity may also be provided individually or in any suitable combination or as any other described embodiment of the present application.

[0058] The above disclosure is only the preferred embodiment of the present application, but it is not intended to limit the scope of rights of the present application. A person of ordinary skill in the art can understand that without departing from the spirit and scope of the present application and the appended claims, changes, modifications, substitutions, combinations, and simplifications should all be equivalent replacement methods and still fall within the scope of the invention.

Claims

1. A converter, comprising a DC port, an AC port, an inverter circuit arranged between the DC port and the AC port, and a bus capacitor arranged on the DC side of the inverter circuit, characterized in that: The converter further comprises: A DC side relay is arranged between the DC port and the bus capacitor; An AC side relay, arranged between the inverter circuit and the AC port; An instruction generation module, wherein the instruction generation module is configured to: when any one of the DC side relay and the AC side relay is turned on, the instruction generation module outputs a first level signal; when all the relays are turned off, the instruction generation module outputs a second level signal in response to receiving a discharge instruction; A discharge module is configured to form a discharge loop with the bus capacitor in response to receiving a second level signal.

2. The converter according to claim 1, characterized in that: The instruction generation module includes a composite logic gate circuit, and the composite logic gate circuit is configured as follows: When any one of the DC-side relay and the AC-side relay is turned on, the instruction generation module outputs a high-level first-level signal; when all relays are turned off, the instruction generation module outputs a low-level second-level signal in response to receiving a discharge instruction.

3. The converter according to claim 2, characterized in that: The composite logic gate circuit comprises: NOR gate circuit and NAND gate circuit, where: The input ends of the NOR gate circuit respectively receive control signals representing the states of the DC side relay and the AC side relay. When the relay is in the off state, the control signal is at a low level; when the relay is in the on state, the control signal is at a high level. The output end of the NOR gate circuit is connected to an input end of the NAND gate circuit, and the other input end of the NAND gate circuit receives the discharge instruction. The discharge instruction is at a high level. The output end of the NAND gate circuit serves as the output end of the instruction generation module.

4. The converter according to claim 3, characterized in that: The discharge module comprises: A first optical coupler, configured to change an on-off state based on an output signal of the instruction generation module; A first switch tube, wherein a control end of the first switch tube is coupled to a secondary side of the first optical coupler, and the first switch tube is connected to the bus capacitor via a discharge resistor to form a discharge loop; The discharge module is configured as follows: When the first optical coupler is turned off, the first switch tube is turned on to discharge the bus capacitor through the discharge resistor.

5. The converter according to claim 4, characterized in that: The discharge module further includes a second switch tube, a control end of the second switch tube is electrically connected to the output end of the instruction generation module, and the second switch tube is electrically connected to the primary side of the first optical coupler.

6. The converter according to claim 4, characterized in that: The discharge module further comprises a voltage stabilizing diode, the cathode of the voltage stabilizing diode being electrically connected to the positive end of the busbar via at least one resistor, and the anode of the voltage stabilizing diode being electrically connected to the negative end of the busbar; The first switch tube is a MOS tube, the drain of the first switch tube is electrically connected to the positive end of the bus through the discharge resistor, the source of the first switch tube is electrically connected to the negative end of the bus, and the gate of the first switch tube is electrically connected to the negative end of the voltage regulator diode.

7. The converter according to claim 4, characterized in that: The discharge resistor is arranged between the positive end of the busbar and the first switch tube; The converter further comprises: A discharge feedback module, the discharge feedback module comprising a second optocoupler; a primary first end of the second optocoupler is electrically connected to a common node of the discharge resistor and the first switch tube, and a primary second end of the second optocoupler is electrically connected to a negative end of the busbar, The first end of the secondary side of the second optical coupler is used as a feedback signal output end and is electrically connected to a high-level reference signal. The second end of the secondary side of the second optical coupler is grounded.

8. The converter according to any one of claims 3 to 7, characterized in that: The DC side relay comprises: a first DC side relay and a second DC side relay, wherein the first DC side relay is arranged between the DC port and the bus capacitor, and the second DC side relay is arranged between the DC port and the bus capacitor via at least one resistor; The AC side relay comprises: a first AC side relay and a second AC side relay, wherein the first AC side relay is arranged between the inverter circuit and the AC port, and the second AC side relay is arranged between the inverter circuit and the AC port through at least one resistor; Control signals representing the states of the first DC side relay, the second DC side relay, the first AC relay and the second AC relay are respectively input to the four input terminals of the NOR gate.

9. The converter according to claim 8, characterized in that The converter further comprises a control device, wherein the control device is configured to control the converter according to the following process: Controlling the second AC side relay to close so as to pre-charge the bus capacitor in the first stage; Controlling the first AC side relay to close, controlling the second AC side relay to turn off, and controlling the second DC side relay to close, so as to pre-charge the bus capacitor in the second stage; The first DC side relay is controlled to be closed, and the second DC side relay is controlled to be turned off, so as to control the converter to start.

10. An energy storage system, characterized in that: The energy storage system comprises the converter according to any one of claims 1 to 9.

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