Pre-charging circuit for alternating current side of bus capacitor of energy storage converter

Abstract

The utility model provides a bus capacitor alternating current side pre-charging circuit of an energy storage converter. The pre-charging circuit comprises any one input phase of a three-phase alternating current, a first silicon controlled rectifier, a second silicon controlled rectifier, a positive bus capacitor, a negative bus capacitor, a first energy storage inductor and a second energy storage inductor. The anode end of the first silicon controlled rectifier is connected with the cathode end of the second silicon controlled rectifier; any input phase of the three-phase alternating current is respectively connected with the anode end of the first silicon controlled rectifier and the cathode end of the second silicon controlled rectifier; the signal end of the first silicon controlled rectifier serves as the control electrode signal end of the positive bus controlled pre-charged silicon controlled rectifier, and the signal end of the second silicon controlled rectifier serves as the control electrode signal end of the negative bus controlled pre-charged silicon controlled rectifier. The beneficial effects of the utility model lie in that compared with a traditional method of controlling the pre-charging circuit by using a relay, the pre-charging link boost is higher, and the pre-charging link is faster; the maximum value of the peak value of the input current in the whole bus boosting process is greatly reduced, and the safety performance is greatly improved.

Description

Technical Field

[0001] The utility model relates to the technical field of energy storage circuits, in particular to an AC side pre-charging circuit for a bus capacitor of an energy storage converter. Background Art

[0002] Before the main loop control of the energy storage converter (PCS) in DC constant voltage mode is started, the bus capacitor must be pre-charged on the AC side input. Only after the bus capacitor is charged to the required voltage level can the constant voltage mode be officially started until the DC side outputs a stable DC voltage. Because of the I-type three-level main power circuit, a large capacitor will be connected in parallel on the DC bus. If the DC bus voltage is zero, when the main power circuit is started, the DC bus capacitor will be quickly charged at the moment the power is turned on. At this time, the entire boost circuit from the AC side to the DC bus capacitor is close to a short-circuit state, and the input current will be very large. The input switch and input fuse will be directly damaged under the impact of the large current close to the short circuit, and it will also cause a considerable impact on the input power grid. Before the main power loop control of the energy storage converter (PCS) in DC constant voltage mode is started, the DC bus capacitor must be pre-charged on the AC side input.

[0003] Traditional pre-charging control uses pre-charging current limiting resistors in conjunction with relay control to implement the pre-charging process of the positive and negative bus capacitors.

[0004] Conventional pre-charge circuits such as Figure 1 As shown, RLY1: bus positive pre-charge relay; RLY2: bus negative pre-charge relay; R1, R2: bus positive pre-charge resistors; R3, R4: bus negative pre-charge resistors; D5, D6: rectifier diodes; ACIN-A: three-phase AC input phase A; NEUTRAL: three-phase AC input zero (N); C1, E1, E3: positive bus capacitors; C2, E2, E4: negative bus capacitors; RERELAY_CTROL-A: A-phase positive and negative pre-charge relay control signal (can control the relay to be closed or disconnected).

[0005] Control process analysis: During the pre-charging process, the three-phase AC input A phase electricity passes through the D5 and D6 rectifier diodes, and then the relay control signal RERELAY_CTROL-A is set low, the pre-charging relay is energized, and the positive and negative busbars are slowly pre-charged through the current limiting resistor. Due to the existence of the current limiting resistors R1, R2 and R3, R4 in the loop, the current limiting function is played. The rectifier components are protected from being damaged by the instantaneous short-circuit current of the capacitor.

[0006] Measured waveform: In the following oscilloscope waveform, channel 1 is the positive bus voltage pre-charging process waveform; channel 2 is the input A phase current waveform; channel 3 is the input B phase current waveform; channel 4 is the input C phase current waveform.

[0007] Among them, the bus precharge waveform is as follows Figure 2 The cursor shows that the bus voltage is pre-charged and boosted to 240V. Figure 3 The cursor shows that the charging time required to boost the bus voltage to 240V is 8.16 seconds. Figure 4 The cursor shows that the maximum input current peak value during the entire boost process is 61.6A. Figure 5 shown.

[0008] Disadvantages: From the above measured waveforms, it can be seen that using this traditional relay in combination with a resistor to control bus pre-charging, it takes 8.16 seconds to pre-charge to the bus half voltage of 240V, and the maximum input current peak value of the entire bus boost process is 61.6A. There are several disadvantages. First, the maximum input current peak value of the entire bus boost process is 61.6A, which is too large. Second, it takes 8.16 seconds to pre-charge to the bus half voltage of 240V, and the charging time is too long. Third, the pre-charging link charges the bus half voltage to 240V, and the boost link when the main power loop starts running needs to boost the bus half voltage to 320V-450V. Therefore, the pre-charging to the bus half voltage of 240V is too low, and when it is boosted to 450V, the instantaneous current will be very large. Fourth, this control pre-charging circuit has a limit on the pre-charging time. If the pre-charging time is too long, the charging current limiting resistors R1, R2 and R3, R4 are easily burned out due to excessive temperature. Fifth, the control pre-charging circuit increases the hardware cost due to the addition of this part of the pre-charging circuit. Sixth, it makes the rectifier circuit part more redundant and complex. Utility Model Content

[0009] The technical problem to be solved by the utility model is to provide a pre-charging circuit on the AC side of a bus capacitor of an energy storage converter, aiming at reducing the peak value of the input current and improving safety.

[0010] In order to solve the above technical problems, the technical solution adopted by the utility model is: a pre-charging circuit of the AC side of the bus capacitor of the energy storage converter, comprising any input phase of the three-phase AC, a first thyristor, a second thyristor, a positive bus capacitor, a negative bus capacitor, a first energy storage inductor, and a second energy storage inductor;

[0011] The anode terminal of the first thyristor is connected to the cathode terminal of the second thyristor, and any input phase of the three-phase AC is respectively connected to the anode terminal of the first thyristor and the cathode terminal of the second thyristor, the cathode terminal of the first thyristor is connected to one end of the first energy storage inductor, the other end of the first energy storage inductor is connected to the anode terminal of the first diode, the cathode terminal of the first diode is connected to one end of the positive bus capacitor, and the other end of the positive bus capacitor is connected to one end of the negative bus capacitor; the other end of the negative bus capacitor is connected to the anode terminal of the second diode, the cathode of the second diode is connected to one end of the second inductor, and the other end of the second inductor is connected to the anode terminal of the second thyristor; the signal terminal of the first thyristor serves as the thyristor control electrode signal terminal for the positive bus control pre-charge, and the signal terminal of the second thyristor serves as the thyristor control electrode signal terminal for the negative bus control pre-charge.

[0012] Furthermore, the connection point between the positive bus capacitor and the negative bus capacitor is connected to the neutral line.

[0013] Furthermore, the anode terminal of the first diode and the cathode terminal of the second diode are connected to the switch tube of the upper half bridge in the boost circuit and the switch tube of the lower half bridge in the boost circuit.

[0014] Furthermore, a connection point between the switch tube of the upper half bridge in the boost circuit and the switch tube of the lower half bridge in the boost circuit is connected to a neutral line.

[0015] Furthermore, the UP_I GBT port of the switch tube of the upper half bridge in the boost circuit is used to access the drive signal for controlling the switch tube of the upper half bridge in the boost circuit to be turned on and off; the DOWN_I GBT port of the switch tube of the lower half bridge in the boost circuit is used to access the drive signal for controlling the switch tube of the lower half bridge in the boost circuit to be turned on and off.

[0016] Furthermore, the number of the positive bus capacitors is one, two or three.

[0017] Furthermore, the number of the negative bus capacitors is one, two or three.

[0018] Furthermore, the connection point of the positive bus capacitor and the negative bus capacitor is connected to the neutral line.

[0019] The beneficial effects of the utility model are: the first thyristor and the second thyristor are used to control the pre-charging of the AC side of the bus capacitor of the energy storage converter, which has a higher voltage boost and a faster pre-charging link than the traditional pre-charging circuit controlled by a relay; the peak maximum value of the input current in the entire bus voltage boosting process is greatly reduced, and the safety performance is greatly improved; the response is faster, opening and closing within microseconds, lower cost, higher efficiency, contactless operation, no sparks, and no noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the utility model 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 utility model. For ordinary technicians in this field, other drawings can be obtained based on the mechanisms shown in these drawings without paying creative work.

[0021] Figure 1 It is a schematic diagram of a conventional pre-charging circuit in the prior art;

[0022] Figure 2 A schematic diagram of busbar precharging waveforms of a conventional precharging circuit in the prior art;

[0023] Figure 3 A schematic diagram of the prior art of precharging and boosting the bus voltage to 240V;

[0024] Figure 4 A schematic diagram of a bus voltage pre-charging time of 8.16 seconds in the prior art;

[0025] Figure 5 A schematic diagram of a boost process in the prior art in which the maximum input current peak value is 61.6A;

[0026] Figure 6 This is a schematic diagram of the AC side pre-charging circuit of the bus capacitor of the energy storage converter according to an embodiment of the utility model;

[0027] Figure 7 A schematic diagram showing the relationship between the positive electrode PFC_UP_SCR_DRA1 pulse signal and the AC input A phase power of an embodiment of the utility model;

[0028] Figure 8 A schematic diagram showing the relationship between the PFC_DOWN_SCR_DRA1 pulse signal of the negative electrode and the AC input A phase power of an embodiment of the utility model;

[0029] Fig. 9 A schematic diagram showing that the negative half of the thyristor drive pulse high level should be in the alternating current sine wave;

[0030] Fig.10 A schematic diagram of busbar pre-charging waveforms according to an embodiment of the utility model;

[0031] Fig.11 This is a schematic diagram of precharging and boosting the bus voltage to 310V in an embodiment of the utility model;

[0032] Fig.12 This is a schematic diagram of a bus voltage pre-charging time of 3.68 seconds in an embodiment of the utility model;

[0033] Fig.13 This is a schematic diagram showing that the maximum value of the pre-charge input current peak value is 13A according to an embodiment of the utility model. DETAILED DESCRIPTION

[0034] 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 of 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.

[0035] It should be noted that the descriptions of "first", "second", etc. in the present utility model are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0036] like Figure 6 As shown, the embodiment of the utility model is: a pre-charging circuit of the bus capacitor AC side of an energy storage converter, comprising any input phase of a three-phase AC, a first thyristor, a second thyristor, a positive bus capacitor, a negative bus capacitor, a first energy storage inductor, and a second energy storage inductor;

[0037] The anode terminal of the first thyristor is connected to the cathode terminal of the second thyristor, and any input phase of the three-phase AC is respectively connected to the anode terminal of the first thyristor and the cathode terminal of the second thyristor, the cathode terminal of the first thyristor is connected to one end of the first energy storage inductor, the other end of the first energy storage inductor is connected to the anode terminal of the first diode, the cathode terminal of the first diode is connected to one end of the positive bus capacitor, and the other end of the positive bus capacitor is connected to one end of the negative bus capacitor; the other end of the negative bus capacitor is connected to the anode terminal of the second diode, the cathode of the second diode is connected to one end of the second inductor, and the other end of the second inductor is connected to the anode terminal of the second thyristor; the signal terminal of the first thyristor serves as the thyristor control electrode signal terminal for the positive bus control pre-charge, and the signal terminal of the second thyristor serves as the thyristor control electrode signal terminal for the negative bus control pre-charge.

[0038] Wherein, the connection point between the positive bus capacitor and the negative bus capacitor is connected to the neutral line.

[0039] The anode terminal of the first diode and the cathode terminal of the second diode are connected to the switch tube of the upper half bridge in the boost circuit and the switch tube of the lower half bridge in the boost circuit.

[0040] Wherein, a connection point between the switch tube of the upper half bridge in the boost circuit and the switch tube of the lower half bridge in the boost circuit is connected to a neutral line.

[0041] Among them, the UP_I GBT port of the switch tube of the upper half bridge in the boost boost circuit is used to access the drive signal for controlling the switch tube of the upper half bridge in the boost boost circuit to turn on and off; the DOWN_I GBT port of the switch tube of the lower half bridge in the boost boost circuit is used to access the drive signal for controlling the switch tube of the lower half bridge in the boost boost circuit to turn on and off.

[0042] Wherein, the number of the positive bus capacitors is one, two or three.

[0043] Wherein, the number of the negative bus capacitors is one, two or three.

[0044] Wherein, the connection point of the positive bus capacitor and the negative bus capacitor is connected to the neutral line.

[0045] like Figure 1 As shown in the figure, taking the three-phase AC input phase A as an example, the actual three phases have the same circuit structure, but the carrier is staggered 120 degrees during boost control to reduce the impact current. The circuit completely omits the pre-charging circuit controlled by the relay in the traditional mode, and directly uses the thyristor to replace the rectifier diode, pre-charging relay and pre-charging current limiting resistor to realize the bus capacitor pre-charging link.

[0046] in:

[0047] LA1: three-phase AC input phase A;

[0048] Q1: SCR pre-charged on the positive bus;

[0049] Q2: SCR pre-charged on negative bus;

[0050] C1: positive bus capacitor;

[0051] C2: negative bus capacitor;

[0052] D1: diode, protection function, to prevent positive bus current from backflow;

[0053] D2: diode, protection function, to prevent negative bus current from flowing back;

[0054] PFC_UP_SCR_DRA1: positive bus control pre-charge thyristor control electrode signal terminal;

[0055] PFC_DOWN_SCR_DRA1: Negative bus control pre-charge thyristor control electrode signal terminal;

[0056] L1, inductor, the inductor of the positive half of the busbar of the boost circuit, is used to store energy and then release the energy to charge the positive half of the busbar capacitor;

[0057] L2, inductor, the inductor of the negative half of the busbar of the boost circuit, is used to store energy and then release the energy to charge the negative half of the busbar capacitor;

[0058] Q3, IGBT, the switch tube of the upper half bridge in the boost circuit, allows the L1 inductor to continue current and store energy by turning on, and releases the L1 inductor capacity to the positive bus capacitor by turning off;

[0059] Q4, I GBT, the switch tube of the lower half bridge in the boost circuit, allows the L2 inductor to continue current and store energy by turning on, and releases the L2 inductor capacity to the negative bus capacitor by turning off;

[0060] UP_I GBT, driving signal to control the opening and closing of Q3;

[0061] DOWN_I GBT, driving signal that controls the on and off of Q4.

[0062] The overall working process of this circuit is: Q3 and Q4 are turned off first in the pre-charging stage. The control strategy of controlling the thyristor is designed to make the thyristor open and close at the designed time in each cycle. The positive bus pre-charging circuit is a slow and controllable pre-charging through the alternating current L1 to the thyristor Q1 to the inductor L1 to the diode D1 to the positive bus capacitor C1. The negative bus pre-charging is similar, through the alternating current L1 to the thyristor Q2 to the inductor L2 to the diode D2 to the negative bus capacitor C2 slowly and controllably pre-charged. After pre-charging to a certain voltage, the boost circuit can be used to control the DC bus capacitor to charge to a voltage that cannot be charged by rectification alone. For example, the AC power with a phase voltage of 220V is rectified to 310V, and then the boost circuit is used to boost the DC bus voltage to 400V, which is an effect that cannot be achieved by rectification alone. The specific boost link is, taking the upper half bridge as an example, first turn on Q3 IGBT through the UP_IGBT drive signal, so that the positive half-axis AC passes through the thyristor Q1 through L1 through Q3 IGBT to N, to store energy for the inductor L1, and then turn off Q3 I GBT through the UP_IGBT drive signal, so that the energy stored in the inductor L1 is released to the capacitor C1 through the diode D1, so that the voltage of C1 can be controlled to rise to a height that cannot be reached by rectification for subsequent use. The DC voltage level that needs to be output can be flexibly controlled. The negative half is the same.

[0063] The following is the unique control pre-charge drive signal generation process of the thyristor.

[0064] The entire pre-charging process is to input the three-phase AC A phase voltage, control the charging through the thyristor, charge the positive bus capacitor and the negative bus capacitor to about 310V, and then perform the power circuit conversion and voltage regulation. During the pre-charging process, the positive and negative bus capacitors are pre-charged by controlling the thyristor control electrode's wave pulse signal, namely the two pulse signals PFC_UP_SCR_DRA1 and PFC_DOWN_SCR_DRA1. These two signals need to be controlled separately.

[0065] Taking the positive electrode as an example, the relationship between the positive electrode's specific PFC_UP_SCR_DRA1 pulse signal and the AC input A phase power is as follows: Figure 7 shown.

[0066] Figure 7 In the figure, the sinusoidal curve is the AC input A phase electricity, and the intersection of the middle horizontal line and the A phase sinusoidal AC is the zero point. The rectangular wave above the curve is the drive pulse signal of the upper half thyristor control electrode PFC_UP_SCR_DRA1. The upper half thyristor control signal must be turned on and off once in each AC cycle. The high level of the rectangle represents the control of the thyristor to turn on, and the low level represents the control of the thyristor to turn off. In each AC cycle, this drive signal is turned on before the zero point of the positive half-wave of the AC, and then turned off a little before the zero point. The difference is that in each AC cycle, the opening moment is gradually moved forward, that is, the time for the high level to control the thyristor to turn on is gradually increased, and the voltage is gradually increased when it is turned on at the forward voltage of the AC. In fact, there is an AC cycle of 20ms. If the entire pre-charging process is calculated as 8 seconds, there are 400 cycles of opening and closing, and each forward moment is also extremely small and precise. Figure 7Only four cycles are drawn to represent the schematic. Then the significance of turning on and off the thyristor in each cycle is analyzed in detail. The moment when the first drive signal is turned on is very important. It must be just a little bit before the positive half axis crosses the zero point to ensure that the initial pre-charge voltage is extremely small and short, so that the charging impact can be controlled to be extremely small and smooth. Then the drive pulse signal of the control electrode gradually widens before crossing the zero point, and the step length of the widening is very small. The first control pulse is issued a little bit before the positive half wave crosses the zero point. At this time, since the control electrode has a high level of the drive pulse signal, the thyristor is turned on and the bus capacitor is charged. However, because the control pulse is only a little bit ahead of zero, once the input crosses the zero point, the thyristor will reach the shutdown condition and turn off when it crosses the zero point. Therefore, the thyristor is only turned on for a little bit in the first positive half wave, and the charging time for the bus capacitor is also very short. In addition, the voltage of the AC power is also low at the moment before the zero point, which will not cause the consequences of excessive charging current and damage the rectifier element. The charging control is extremely gentle. The high level of the driving wave pulse of the control electrode is gradually widened, that is to say, the conduction time of the thyristor is gradually lengthened in each cycle, and the time for charging the bus capacitor and the voltage level of the AC power are increased little by little until the whole pre-charging process is completed and the positive bus capacitor pre-charging is completed. A safe, stable and controllable bus capacitor pre-charging process is achieved.

[0067] Taking the negative half charging as an example, the pre-charging process and driving wave generation process of the negative half of the busbar are explained.

[0068] Taking the negative half charging process of the bus as an example, the relationship between the negative electrode specific PFC_DOWN_SCR_DRA1 pulse signal and the AC input A phase power is as follows: Figure 8 shown.

[0069] Unlike the positive half, the negative half uses the negative half of the AC to charge the negative bus capacitor, so the biggest difference is that the negative half thyristor drive pulse high-level signal must be turned on before the negative half of the sine wave passes through zero, rather than the positive half. The negative half charging and positive half charging drive pulse high-level signals are controlled independently.

[0070] Figure 8The middle sine curve is the AC input A phase electricity, and the intersection of the middle horizontal line and the A phase sinusoidal AC is the zero point. The rectangular wave above the curve is the drive pulse signal of the negative half thyristor control electrode PFC_DOWN_SCR_DRA1. As can be seen from the schematic diagram, the thyristor control signal of the lower half must be turned on and off once in each AC cycle. The high level of the rectangle represents the control of the thyristor to turn on, and the low level represents the control of the thyristor to turn off. As can be seen from the figure, in each AC cycle, this drive signal is turned on at the position before the zero crossing point of the negative half wave of the AC, and then turned off a little before the zero crossing point. The difference is that in each AC cycle, the opening time point is gradually moved forward, that is, the high level control thyristor conduction time is gradually increased, and the voltage is gradually increased when the AC is turned on. The first control pulse is issued a little before the negative half wave crosses the zero point. At this time, since the negative half thyristor control electrode has a high level of the drive pulse signal, the thyristor is turned on and the negative bus capacitor is charged. However, because the control pulse is only slightly ahead of zero, once the input passes through zero, the thyristor will reach the shutdown condition and will be shut down when it passes through zero. Therefore, the thyristor on the negative half is only turned on for a short time in the first negative half-wave, and the charging time for the bus capacitor is also extremely short. In addition, the voltage of the AC power is also low just before the zero point, which will not cause the consequences of excessive charging current and damage to the rectifier components. The charging control is extremely gentle. Then, the high level of the driving wave pulse of the control electrode is gradually widened little by little, that is, the conduction time of the thyristor is gradually lengthened little by little in each cycle, and the time to charge the negative half bus capacitor and the voltage level of the AC power are increased little by little until the entire pre-charging process is completed and the pre-charging of the negative half bus capacitor is completed.

[0071] Therefore, the pre-charging process of the positive and negative half thyristor control is independently controlled and does not affect each other. The difference is that the positive half thyristor drive pulse high level must be turned on and off before the positive half axis of the AC sine wave passes through zero, while the negative half thyristor drive pulse high level must be turned on before the negative half axis of the AC sine wave passes through zero, such as Fig. 9 shown.

[0072] Among them, the high level of the driving pulse turned on and off before the positive half axis passes through zero is the thyristor driving signal of the positive bus, and the high level of the driving pulse turned on and off before the negative half axis passes through zero is the thyristor driving signal of the negative bus. The same step size will make the charging speed of the bus capacitors on the positive and negative sides consistent. It is safe and reliable, without impact current.

[0073] Measured waveform: In the following oscilloscope waveform, channel 1 is the positive bus voltage pre-charging process waveform; channel 2 is the input A phase current waveform; channel 3 is the input B phase current waveform; channel 4 is the input C phase current waveform.

[0074] Among them, the bus precharge waveform is as follows Fig.10The bus voltage with cursor is shown as follows: The half voltage of the bus voltage is pre-charged and boosted to 310V. Fig.11 The cursor shows that the charging time required to boost the bus half voltage to 310V is 3.68 seconds. Fig.12 The cursor shows that the maximum input current peak value of the entire bus boost process is 13A. Fig.13 shown.

[0075] It can be seen from the above measured waveform that the AC side pre-charging circuit of the energy storage converter bus capacitor takes 3.68 seconds to pre-charge to the bus half voltage of 310V, and the maximum input current peak value of the entire bus boost process is 13A.

[0076] Compared with the traditional method of controlling the pre-charging circuit using relays, the present application has the following advantages: First, the pre-charging step has a significantly higher boost. The traditional method boosts the voltage to 240V for the half side of the bus, while the control method using thyristors can boost the voltage to 310V for the half side of the bus during the pre-charging step. Then, the boost circuit can be used to freely control the DC bus voltage level to a voltage level that cannot be reached by pre-charging. Second, the pre-charging step is faster. The control method using thyristors can charge the half side of the bus to 310V within 3.68 seconds, while the traditional relay control method requires 8.16 seconds to pre-charge the half side of the bus to 240V, which is more than twice as fast. Third, the peak maximum value of the input current is greatly reduced during the entire bus boosting process. Safety performance is greatly improved. The maximum peak value of the input current of the traditional control method is 61.6A, while the peak value of the input current of the new thyristor controlled pre-charging method during the entire bus boost process is only 13A, which is about one-fifth of the original value. It is extremely safe, and the software program can also control the thyristor drive signal wave step length to make the impact smaller. Fourth, it has great advantages over the traditional pre-charging mode controlled by relays. It has faster response, turns on and off within microseconds, lower cost, higher efficiency, contactless operation, no sparks, and no noise. Therefore, in the design of the constant voltage mode in the PCS, the control mode of using thyristors and the supporting new control strategy to control the pre-charging of the DC bus capacitor on the AC side has significant advantages.

[0077] The above description is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A pre-charging circuit for the AC side of a bus capacitor of an energy storage converter, characterized in that: It includes any input phase of three-phase AC, a first thyristor, a second thyristor, a positive bus capacitor, a negative bus capacitor, a first energy storage inductor, and a second energy storage inductor; The anode terminal of the first thyristor is connected to the cathode terminal of the second thyristor, and any input phase of the three-phase AC is respectively connected to the anode terminal of the first thyristor and the cathode terminal of the second thyristor, the cathode terminal of the first thyristor is connected to one end of the first energy storage inductor, the other end of the first energy storage inductor is connected to the anode terminal of the first diode, the cathode terminal of the first diode is connected to one end of the positive bus capacitor, and the other end of the positive bus capacitor is connected to one end of the negative bus capacitor; the other end of the negative bus capacitor is connected to the anode terminal of the second diode, the cathode of the second diode is connected to one end of the second inductor, and the other end of the second inductor is connected to the anode terminal of the second thyristor; the signal terminal of the first thyristor serves as the thyristor control electrode signal terminal for the positive bus control pre-charge, and the signal terminal of the second thyristor serves as the thyristor control electrode signal terminal for the negative bus control pre-charge.

2. The energy storage converter bus capacitor AC side pre-charging circuit as claimed in claim 1, characterized in that: The connection point between the positive bus capacitor and the negative bus capacitor is connected to the neutral line.

3. The energy storage converter bus capacitor AC side pre-charging circuit as claimed in claim 1, characterized in that: The anode terminal of the first diode and the cathode terminal of the second diode are connected to the switch tube of the upper half bridge in the boost circuit and the switch tube of the lower half bridge in the boost circuit.

4. The energy storage converter bus capacitor AC side pre-charging circuit as claimed in claim 3, characterized in that: A connection point between the switch tube of the upper half bridge in the boost circuit and the switch tube of the lower half bridge in the boost circuit is connected to a neutral line.

5. The energy storage converter bus capacitor AC side pre-charging circuit as claimed in claim 3, characterized in that: The UP_IGBT port of the switch tube of the upper half bridge in the boost circuit is used to access the drive signal for controlling the switch tube of the upper half bridge in the boost circuit to turn on and off; the DOWN_IGBT port of the switch tube of the lower half bridge in the boost circuit is used to access the drive signal for controlling the switch tube of the lower half bridge in the boost circuit to turn on and off.

6. The energy storage converter bus capacitor AC side pre-charging circuit as claimed in claim 1, characterized in that: The number of the positive bus capacitors is one, two or three.

7. The energy storage converter bus capacitor AC side pre-charging circuit as claimed in claim 6, characterized in that: The number of the negative bus capacitors is one, two or three.

8. The energy storage converter bus capacitor AC side pre-charging circuit as claimed in claim 7, characterized in that: The connection point of the positive bus capacitor and the negative bus capacitor is connected to the neutral line.

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