An AC soft-start circuit for energy storage converter

Abstract

The utility model discloses an AC soft-start circuit of an energy storage converter, which is used for being connected to a three-phase four-wire energy storage converter and comprising a parallel soft-start rectifier circuit and a soft-start bus capacitor. The soft-start rectifier circuit is located on the AC side and is respectively connected to the AC-L side and the AC-N side of the AC power grid; the two ends of the soft-start bus capacitor are respectively connected to the connection line between the rectifier topology circuit and the AC bus capacitor in the three-phase four-wire energy storage converter; the connection lines between the soft-start rectifier circuit and the AC-L side and the AC-N side of the AC power grid are respectively provided with soft-start capacitors. The utility model has a reasonable design structure. It can use a soft-start capacitor plus a relay solution to make the capacitor as an energy storage device without generating loss. At the same time, it uses the characteristics of the capacitor to make the bus voltage rise slowly after rectification, which can effectively reduce the impact on the bus electrolytic capacitor, avoid initial large current charging to protect the entire system, and solve the problem that the resistor consumes power and reduces the efficiency of the converter during traditional startup.

Description

Technical Field

[0001] The utility model relates to the technical field of alternators, in particular to an alternating current soft-start circuit of an energy storage converter. Background Art

[0002] With the vigorous development of new energy and energy storage industries, energy storage power stations using three-phase four-wire energy storage inverters are in operation. In order to protect the safety of energy storage inverters and the entire energy storage system, in the early stage of inverter operation, the equivalent resistance of the bus capacitor of the energy storage inverter is small and cannot withstand the impact of high voltage and large current. It is necessary to use an AC soft-start circuit to pre-charge the bus capacitor. After the bus voltage stabilizes, the main circuit charging is started to ensure safe and reliable operation of the system.

[0003] The traditional soft-start circuit allows the current to pass through the power resistor and relay in sequence at the moment when the energy storage AC converter begins to charge, reducing the grid pressure and the stress on the equipment startup. However, during startup, the resistor will consume power and reduce the efficiency of the converter. For this reason, we provide an AC soft-start circuit for the energy storage converter to solve the above problems. Utility Model Content

[0004] The purpose of the utility model is to make up for the deficiencies of the prior art and to provide an AC soft-start circuit for an energy storage converter.

[0005] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0006] An AC soft-start circuit of an energy storage converter is used for grid-connection with a three-phase four-wire energy storage converter, comprising a soft-start rectifier circuit and a soft-start bus capacitor connected in parallel, wherein the soft-start rectifier circuit is located on the AC side and is respectively connected to the AC-L side and the AC-N side of the AC grid; the two ends of the soft-start bus capacitor are respectively connected to the connection line between the rectifier topology circuit and the AC bus capacitor in the three-phase four-wire energy storage converter;

[0007] Soft-start capacitors are respectively arranged on the connection lines between the soft-start rectifier circuit and the AC-L side and the AC-N side of the AC power grid.

[0008] Furthermore, a soft-start relay is provided on the connection line between the soft-start rectifier circuit and the AC-L side of the AC power grid, and the soft-start relay is located between the soft-start capacitor and the soft-start rectifier circuit.

[0009] Furthermore, the soft-start rectifier circuit is a bridge rectifier circuit.

[0010] Furthermore, the bridge rectifier circuit includes a first bridge arm and a second bridge arm connected in parallel;

[0011] The first bridge arm and the second bridge arm both include diodes connected in series;

[0012] The AC-L side and the AC-N side of the AC power grid are respectively connected to the connection point of the first bridge arm and the second bridge arm.

[0013] Furthermore, the first bridge arm and the second bridge arm are respectively composed of two diodes connected in series.

[0014] Compared with the prior art, the AC soft-start circuit of the energy storage converter has the following beneficial effects:

[0015] The utility model adopts a soft-start capacitor to use the capacitor as an energy storage device without generating loss. At the same time, the characteristics of the capacitor are utilized to make the bus voltage rise slowly after rectification, which can effectively reduce the impact on the bus electrolytic capacitor, avoid initial large current charging to protect the entire system, and solve the problem that the resistor consumes power and reduces the efficiency of the converter during traditional startup. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the soft-start circuit structure of the energy storage converter of the utility model;

[0017] Figure 2 The utility model is a schematic diagram of the grid-connected structure of the AC soft-start circuit of the energy storage converter and the three-phase four-wire energy storage converter.

[0018] 1. The first soft-start capacitor; 2. The second soft-start capacitor; 3. The soft-start relay; 4. The first diode; 5. The second diode; 6. The third diode; 7. The fourth diode; 8. The soft-start bus capacitor. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0020] like Figure 1-2As shown, the utility model provides a technical solution: an AC soft-start circuit of an energy storage converter, which is used for grid-connected use with a three-phase four-wire energy storage converter, and includes a soft-start rectifier circuit and a soft-start bus capacitor 8 connected in parallel, wherein the soft-start rectifier circuit is located on the AC side and is respectively connected to the AC-L side and the AC-N side of the AC grid; the two ends of the soft-start bus capacitor 8 are respectively connected to the connection line between the rectifier topology circuit and the alternating bus capacitor in the three-phase four-wire energy storage converter; soft-start capacitors are respectively arranged on the connection lines between the soft-start rectifier circuit and the AC-L side and the AC-N side of the AC grid; a soft-start relay 3 is also arranged on the connection line between the soft-start rectifier circuit and the AC-L side of the AC grid, and the soft-start relay 3 is located between the soft-start capacitor and the soft-start rectifier circuit.

[0021] When in use, the soft-start capacitor includes a first soft-start capacitor 1 and a second soft-start capacitor 2. The AC-L side is connected to the soft-start rectifier circuit through the first soft-start capacitor 1 and the soft-start relay 3, and the AL-N side is connected to the soft-start rectifier circuit through the second soft-start capacitor 2; the AC-L side is connected to the hot line in the three-phase four-wire main circuit, and the AC-N side is connected to the neutral line, and then through the soft-start capacitor and the soft-start relay 3, the characteristics of the capacitor are utilized to act as an energy storage device in the circuit without generating losses, so that the bus voltage rises slowly after rectification, effectively reducing the impact of the bus electrolytic capacitor, playing a role in protecting the soft-start bus capacitor 8 and reducing system losses; the three-phase four-wire energy storage converter can provide A / B / C / N AC voltage for grid connection, select A / N as the AC input or select an external unidirectional power grid as the AC input source of the AC soft-start circuit, and charge the soft-start bus capacitor 8 after passing through the soft-start capacitor and the rectifier bridge, which is beneficial to protecting the energy storage converter.

[0022] The soft-start rectifier circuit is a bridge rectifier circuit; the bridge rectifier circuit includes a first bridge arm and a second bridge arm connected in parallel; the first bridge arm and the second bridge arm both include diodes connected in series; the AC-L side and the AC-N side of the AC power grid are respectively connected to the connection points of the first bridge arm and the second bridge arm; the first bridge arm and the second bridge arm are respectively composed of two diodes connected in series; when in use, the first diode 4 and the second diode 5 are connected in series, the third diode 6 and the fourth diode 7 are connected in series, and the first diode 4 and the second diode 5 are connected in parallel with the third diode 6 and the fourth diode 7; the input connection point between the first diode 4 and the second diode 5 is connected to the AC-L side through the first soft-start capacitor 1 and the soft-start relay 3, the input connection point between the third diode 6 and the fourth diode 7 is connected to the AC-N side through the second soft-start capacitor 2, and the output connection points between the first diode 4 and the third diode 6 and the second diode 5 and the fourth diode 7 are respectively connected to the soft-start bus capacitor 8;

[0023] When in use, AC power is input through the AC-L side and the AC-N side, so that the AC power passes through the soft-start capacitor and then the rectifier bridge to charge the soft-start bus capacitor 8, thereby pre-charging the soft-start bus capacitor 8, improving the efficiency of the energy storage converter, and being beneficial to protecting the energy storage converter and improving the economic benefits of the power station.

Claims

1. An AC soft-start circuit for an energy storage converter, used for grid-connection with a three-phase four-wire energy storage converter, characterized in that: It comprises a soft-start rectifier circuit and a soft-start bus capacitor (8) connected in parallel, wherein the soft-start rectifier circuit is located on the AC side and is respectively connected to the AC-L side and the AC-N side of the AC power grid; the two ends of the soft-start bus capacitor (8) are respectively connected to the connection line between the rectifier topology circuit and the AC bus capacitor in the three-phase four-wire energy storage converter; Soft-start capacitors are respectively arranged on the connection lines between the soft-start rectifier circuit and the AC-L side and the AC-N side of the AC power grid.

2. The AC soft-start circuit of the energy storage converter according to claim 1, characterized in that: A soft-start relay (3) is also provided on the connection line between the soft-start rectifier circuit and the AC-L side of the AC power grid, and the soft-start relay (3) is located between the soft-start capacitor and the soft-start rectifier circuit.

3. The AC soft-start circuit of the energy storage converter according to claim 1, characterized in that: The soft-start rectifier circuit is a bridge rectifier circuit.

4. The AC soft-start circuit of the energy storage converter according to claim 3, characterized in that: The bridge rectifier circuit comprises a first bridge arm and a second bridge arm connected in parallel; The first bridge arm and the second bridge arm both include diodes connected in series; The AC-L side and the AC-N side of the AC power grid are respectively connected to the connection point of the first bridge arm and the second bridge arm.

5. The AC soft-start circuit of the energy storage converter according to claim 4, characterized in that: The first bridge arm and the second bridge arm are respectively composed of two diodes connected in series.

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