Autonomous current sharing method for input parallel output parallel voltage-doubler resonant converter

Abstract

The application discloses a kind of self-averaging current methods of input parallel output parallel of voltage-doubler resonant converter, the method is as follows: one, design the topology structure of input parallel output parallel of voltage-doubler resonant converter;Two, parameter design is carried out to resonant capacitor;Three, multiple voltage-doubler resonant converter input parallel output parallel constitutes multiple module parallel voltage-doubler resonant converter, when the power of converter is less than set value, the voltage gain of converter slowly drops with the increase of output power, when the power of converter increases to set value, the voltage gain of power module rapidly drops with the increase of output power, the power difference of different power modules under the same voltage gain is very small, and the self-averaging current of multiple modules of converter is realized.The application solves the uneven current problem caused by parameter deviation between power modules of multiple module parallel voltage-doubler resonant converter, and ensures the stable operation of each power module under rated power.

Description

Technical Field

[0001] The invention belongs to the field of power electronic transformers and relates to an autonomous current sharing method of a voltage-doubling resonant converter. Background Art

[0002] In recent years, resonant converters have become a key research topic in the field of power electronic transformers in DC power systems, thanks to their high power density, high efficiency, low cost, and isolation capabilities. They are widely used in energy storage devices, electric vehicles, and DC aggregation and transmission. In high-power, high-current applications, single-module resonant converters exhibit large output current ripple, and their capacity design is insufficient to meet MW-level requirements. This necessitates the use of multiple resonant converters connected in parallel to reduce ripple while improving reliability and capacity.

[0003] However, during the actual operation of resonant converters, there are problems such as manufacturing process and component aging. There are parameter deviations between different modules of the parallel converter, resulting in differences in the output current of each phase, affecting the efficiency, service life, safety and reliability of the entire converter.

[0004] In response to the above-mentioned uneven current problem, CN115037158A provides a solution for phase compensation through an AC current source. By detecting the difference in the output current of each phase in real time and adjusting the phase of the AC current source injected into each phase, the current equalization of a multi-module parallel resonant converter is achieved. This method has a good effect in achieving equal current, but the real-time detection of the current of each phase has high requirements on equipment, the control is more complicated, and the cost is increased. From a topological perspective, CN114825957A connects the resonant inductors of each module in parallel to offset the impact of the deviation of the resonant inductor parameters. This method does not require a complex control system and does not require the addition of unnecessary components. However, it cannot achieve the staggered operation of multiple modules and is prone to causing distortion of the resonant current waveform, which has certain limitations.

[0005] Therefore, it is necessary to develop an autonomous current sharing technology that is simple to control, has good current sharing effect, and can achieve staggered operation to ensure efficient and reliable operation of the resonant converter when the input and output are connected in parallel. Summary of the Invention

[0006] To address the problem of uneven current distribution across phases caused by parameter inconsistencies between power modules in multi-module parallel resonant converters, the present invention provides an autonomous current-sharing method for parallel input and output connections in voltage-doubling resonant converters. This method solves the problem of uneven current distribution across power modules in multi-module parallel resonant converters due to parameter deviations, ensuring stable operation of each power module at rated power, protecting components, reducing losses, and improving converter reliability. The method has application in power electronics.

[0007] The application aims at the following technical scheme

[0008] A self-flowing method of input parallel output parallel of a voltage-doubler resonant converter, comprising the following steps:

[0009] Step one, designing a topology structure of input parallel output parallel of a voltage-doubler resonant converter

[0010] The topology structure comprises N power modules with the same structure, the N power modules are connected in an input parallel output parallel mode, the positive pole of the DC input end of the parallel connection of the low-voltage side of the N power modules is connected with the positive pole of a low-voltage DC bus, and the negative pole of the DC input end is connected with the negative pole of the low-voltage DC bus; the positive pole of the DC output end of the parallel connection of the medium-voltage side of the N power modules is connected with the positive pole of a medium-voltage DC bus, and the negative pole of the DC output end is connected with the negative pole of the medium-voltage DC bus

[0011] The power module comprises a voltage-doubler resonant converter and a clamping diode, the voltage-doubler resonant converter comprises an input filter capacitor C i , an inverter bridge circuit, a transformer, a resonant inductor L r , a first resonant capacitor C r1 , a second resonant capacitor C r2 , a rectifier bridge circuit, and an output filter capacitor C o ; the inverter bridge circuit is a half-bridge structure or a full-bridge structure, and the rectifier bridge circuit is an n times voltage-doubler structure; the clamping diode comprises a first clamping diode D c1 and a second clamping diode D c2 ; the first clamping diode D c1 and the second clamping diode D c2 are arranged at the two ends of the first resonant capacitor C r1 and the second resonant capacitor C r2 of the voltage-doubler resonant converter

[0012] Step two, parameter design of the resonant capacitor

[0013] The parameter design of the first resonant capacitor C r1 and the second resonant capacitor C r2 is as follows:

[0014]

[0015] Wherein, the parameter a is used to distinguish the structure configuration of the rectifier bridge circuit, a=n / 2, n represents that the rectifier bridge is an n times voltage-doubler structure, n is an even number, M represents the voltage gain of the resonant converter, M=U o / U i , U o is the output voltage, U i is the input voltage, and n TTransformer ratio, P o Transformer rated output power, f s Switching frequency

[0016] Step three, a plurality of voltage multiplication type resonant converters input in parallel output in parallel constitute a multi-module parallel voltage multiplication type resonant converter, when the power of the converter is less than the set value, the voltage gain of the converter slowly decreases with the increase of the output power, when the power of the converter increases to the set value, the relationship between the voltage gain of the converter and the output power is:

[0017]

[0018] Wherein, the resonant capacitor C r =C r1 =C r2 The voltage gain of each power module rapidly decreases with the increase of the output power after the power of each power module reaches the set value, the power difference of different power modules under the same voltage gain is small, and the self-current sharing of the multi-module converter is realized.

[0019] Compared with the prior art, the present application has the following advantages:

[0020] 1. The present application realizes the self-current sharing of the multi-module voltage multiplication type resonant converter input in parallel output in parallel by increasing the structure configuration of the clamping diode and the design of the resonant parameters, avoids the problem of uneven power distribution caused by inconsistent parameters, improves the operation safety and reliability of the resonant converter, and prolongs the service life.

[0021] 2. The present application can realize the staggered operation of the multi-module parallel voltage multiplication type resonant converter, and reduce the output voltage ripple.

[0022] 3. The present application only increases the clamping diode, without increasing complex control and precise sampling instruments, and has high cost-effectiveness. DETAILED DESCRIPTION

[0023] Figure 1 It is a whole structure schematic diagram of a multi-module parallel voltage multiplication type resonant converter proposed by the present application;

[0024] Figure 2 It is a single module topology structure schematic diagram of a voltage multiplication type resonant converter proposed by the present application;

[0025] Figure 3 It is a voltage gain and output power relationship schematic diagram of a parallel resonant converter proposed by the present application;

[0026] Figure 4 It is a resonant current and output current simulation waveform schematic diagram of a traditional parallel resonant converter;

[0027] Figure 5 The simulation waveform diagram of the resonant current and the output current of the parallel voltage-doubler resonant converter proposed in the application is shown in the figure;

[0028] Figure 6 The two-level half-bridge inverter topology structure diagram of the multi-module parallel voltage-doubler resonant converter proposed in the application is shown in the figure;

[0029] Figure 7 The two-level full-bridge inverter topology structure diagram of the multi-module parallel voltage-doubler resonant converter proposed in the application is shown in the figure;

[0030] Figure 8 The three-level half-bridge inverter topology structure diagram of the multi-module parallel voltage-doubler resonant converter proposed in the application is shown in the figure;

[0031] Figure 9 The three-level full-bridge inverter topology structure diagram of the multi-module parallel voltage-doubler resonant converter proposed in the application is shown in the figure;

[0032] Figure 10 The two-voltage-doubler rectifier topology structure diagram of the multi-module parallel voltage-doubler resonant converter proposed in the application is shown in the figure.

[0033] Figure 11 The four-voltage-doubler rectifier topology structure diagram of the multi-module parallel voltage-doubler resonant converter proposed in the application is shown in the figure.

[0034] Figure 12 The n-voltage-doubler rectifier topology structure diagram of the multi-module parallel voltage-doubler resonant converter proposed in the application is shown in the figure. DETAILED DESCRIPTION

[0035] The technical solutions of the application are further described below with reference to the accompanying drawings, but are not limited thereto, and any modification or equivalent replacement of the technical solutions of the application without departing from the spirit and scope of the technical solutions of the application shall be covered in the protection scope of the application.

[0036] The application provides a topology structure of a voltage-doubler resonant converter input parallel output parallel, as shown in the figure. Figure 1 N power modules are connected in an input parallel output parallel manner. The positive pole of the DC input end of the N power modules connected in parallel at the low-voltage side is connected to the positive pole of the low-voltage DC bus, and the negative pole of the DC input end is connected to the negative pole of the low-voltage DC bus; the positive pole of the DC output end of the N power modules connected in parallel at the medium-voltage side is connected to the positive pole of the medium-voltage DC bus, and the negative pole of the DC output end is connected to the negative pole of the medium-voltage DC bus.

[0037] Figure 2 The topology structure diagram of a power module of a voltage-doubler resonant converter proposed in the application is shown in the figure. The circuit comprises an input filter capacitor C i, inverter bridge circuit, transformer, resonant inductor L r , the first resonant capacitor C r1 , the second resonant capacitor C r2 , rectifier bridge circuit, output filter capacitor C o And the additional first clamping diode D c1 and the second clamping diode D c2 The inverter bridge circuit is a full-bridge structure, including a first switch tube S1, a second switch tube S2, a third switch tube S3, and a fourth switch tube S4; the rectifier bridge circuit is a half-bridge double voltage structure, which includes a first resonant capacitor C r1 , the second resonant capacitor C r2 , the first diode D1 and the second diode D2. The positive electrode of the input terminal is connected to the input filter capacitor C i The positive electrode of the input terminal is connected to the drain of the first switch tube S1, and the negative electrode of the input terminal is connected to the drain of the first switch tube S1 through the input filter capacitor C i The negative electrode of the first switch tube S1 is connected to the source of the second switch tube S2, the drain of the first switch tube S1 is connected to the drain of the third switch tube S3, the source of the first switch tube S1 is connected to the drain of the second switch tube S2, the source of the third switch tube S3 is connected to the drain of the fourth switch tube S4, the source of the second switch tube S2 is connected to the source of the fourth switch tube S4, the source of the first switch tube S1 is connected to one end of the primary side of the transformer, the source of the third switch tube S3 is connected to the other end of the primary side of the transformer, and the same-name end of the secondary side of the transformer is connected via the resonant inductor L r With the first resonant capacitor C r1 The negative electrode and the second resonant capacitor C r2 The positive electrode of the transformer is connected, the non-identical end of the secondary side of the transformer is connected to the anode of the first diode D1 and the cathode of the second diode D2, and the first resonant capacitor C r1 The positive electrode is connected to the cathode of the first diode D1, and the second resonant capacitor C r2 The cathode of the output terminal is connected to the anode of the second diode D2, and the anode of the output terminal is connected to the output filter capacitor C o The positive electrode of the output terminal is connected to the cathode of the first diode D1, and the negative electrode of the output terminal is connected to the output filter capacitor C o The cathode of the first clamping diode D is connected to the anode of the second diode D2. c1 and the second clamping diode D c2 Configured in the first resonant capacitor C r1 and the second resonant capacitor C r2 The two ends of the first clamping diode D c1 The anode and the first resonant capacitor C r1 The cathode of the first clamping diode D c1 The cathode of the first resonant capacitor C r1 The positive electrode of the second clamping diode Dc2 anode of the second clamping diode D r2 connected to the cathode of the second resonant capacitor C c2 anode of the second clamping diode D r2 connected to the cathode of the second resonant capacitor C

[0038] Figure 3 Fig. 2 is a schematic diagram showing the relationship between the voltage gain and the output power of the parallel resonant converter according to the present application, and the relationship between the voltage gain and the output power of the converter is as follows: when the power of the converter is less than a set value, the voltage gain of the converter decreases very slowly with the increase of the output power; when the power of the converter increases to the set value, the resonant capacitor voltage is clamped by the clamping diode, and the relationship between the voltage gain and the output power of the converter is as follows:

[0039]

[0040] wherein the parameter a is used to distinguish the structural configuration of the rectifier bridge circuit, a = n / 2, n represents that the rectifier bridge is n times voltage structure, M represents the voltage gain of the resonant converter, M = U o / U i , U o is the output voltage, U i is the input voltage, n T is the transformer ratio, P o is the rated output power of the converter, f s is the switching frequency, the resonant capacitor C r = C r1 = C r2 . After the power of the converter reaches the set value, the voltage gain of the converter decreases very quickly with the increase of the output power.

[0041] the first resonant capacitor C r1 , the second resonant capacitor C r2 , the parameter design method is as follows:

[0042]

[0043] the resonant inductor L r , the parameter design method is as follows:

[0044]

[0045] wherein f r represents the resonant frequency of the resonant converter, the resonant capacitor C r = C r1 = C r2 .

[0046] The multiple voltage doubling type resonant converters are input parallel and output parallel, and constitute a multiple module parallel voltage doubling type resonant converter, when the power of each power module reaches a set value, the voltage gain of the power module decreases quickly with the increase of the output power.

[0047] Figure 4 It is a current simulation waveform diagram of a traditional parallel resonant converter, the resonant type converter with two modules in parallel is simulated under the condition of 300kW 1.5kV / 1.5kV, the inverter bridge circuit structure is a full-bridge structure, the rectifier bridge circuit is a half-bridge double voltage structure, the resonant inductance and the resonant capacitance are respectively deviated by 10%, the simulation waveform obtained from top to bottom is the output current of two modules, the resonant current of the first module and the resonant current of the second module, and it can be obtained that the current sharing error of the traditional parallel resonant converter is large, up to 53.71%, the power difference of the two modules is large, and the converter is easily damaged.

[0048] Figure 5 It is a current simulation waveform diagram of a parallel voltage doubling type resonant converter proposed in the application, the resonant type converter with two modules in parallel is simulated under the condition of 300kW 1.5kV / 1.5kV, the inverter bridge circuit structure is a full-bridge structure, the rectifier bridge circuit is a half-bridge double voltage structure, the resonant inductance and the resonant capacitance are respectively deviated by 10%, the simulation waveform obtained from top to bottom is the output current of two modules, the resonant current of the first module and the resonant current of the second module, and it can be obtained that after the clamping diode is added and the resonant parameters are designed, the current sharing error of the parallel resonant converter is very small, only 1.33%, and the current sharing effect of the method is very good under the same condition.

[0049] Figure 6 It is a two-level half-bridge inverter topology structure diagram of a multiple module parallel voltage doubling type resonant converter, the self-current sharing method of the multiple module voltage doubling type resonant converter input parallel and output parallel proposed in the application is suitable for the inverter bridge circuit structure being a two-level half-bridge structure.

[0050] Figure 7 It is a two-level full-bridge inverter topology structure diagram of a multiple module parallel voltage doubling type resonant converter, the self-current sharing method of the multiple module voltage doubling type resonant converter input parallel and output parallel proposed in the application is suitable for the inverter bridge circuit structure being a two-level full-bridge structure.

[0051] Figure 8 It is a three-level half-bridge inverter topology structure diagram of a multiple module parallel voltage doubling type resonant converter, the self-current sharing method of the multiple module voltage doubling type resonant converter input parallel and output parallel proposed in the application is suitable for the inverter bridge circuit structure being a three-level half-bridge structure.

[0052] Figure 9The application discloses a self-regulating current sharing method for a multi-module parallel voltage-doubled resonant converter, and relates to the technical field of power electronic converters.

[0053] Figure 10 The application discloses a self-regulating current sharing method for a multi-module parallel voltage-doubled resonant converter, and relates to the technical field of power electronic converters.

[0054] Figure 11 The application discloses a self-regulating current sharing method for a multi-module parallel voltage-doubled resonant converter, and relates to the technical field of power electronic converters.

[0055] Figure 12 The application discloses a self-regulating current sharing method for a multi-module parallel voltage-doubled resonant converter, and relates to the technical field of power electronic converters.

Claims

1. A method for autonomous current sharing of voltage-doubling resonant converters with parallel input and output connections, characterized in that The autonomous current sharing method comprises the following steps: Step 1: Design a topology for a voltage-doubling resonant converter with parallel input and parallel output The topology structure includes N power modules with the same structure, and the N power modules are connected in parallel input and output. The positive pole of the DC input terminal of the N power modules after the low-voltage sides are connected in parallel is connected to the positive pole of the low-voltage DC bus, and the negative pole of the DC input terminal is connected to the negative pole of the low-voltage DC bus; the positive pole of the DC output terminal of the N power modules after the medium-voltage sides are connected in parallel is connected to the positive pole of the medium-voltage DC bus, and the negative pole of the DC output terminal is connected to the negative pole of the medium-voltage DC bus; The power module includes a voltage-doubling resonant converter and a clamping diode. The rectifier bridge circuit of the voltage-doubling resonant converter is a half-bridge double-voltage structure. The half-bridge double-voltage structure includes a first resonant capacitor C r1 , the second resonant capacitor C r2 , the first diode D1 and the second diode D2, the transformer secondary side of the voltage doubler resonant converter has the same name end through the resonant inductor L r With the first resonant capacitor C r1 The negative electrode and the second resonant capacitor C r2 The positive electrode of the transformer is connected, the non-identical end of the secondary side of the transformer is connected to the anode of the first diode D1 and the cathode of the second diode D2, and the first resonant capacitor C r1 The positive electrode is connected to the cathode of the first diode D1, and the second resonant capacitor C r2 The cathode of the first clamping diode D is connected to the anode of the second diode D2. c1 and the second clamping diode D c2 , the first clamping diode D c1 and the second clamping diode D c2 They are respectively configured in the first resonant capacitor C of the voltage doubler resonant converter r1 and the second resonant capacitor C r2 Both ends of Step 2: Design parameters of the resonant capacitor The first resonant capacitor C r1 , the second resonant capacitor C r2 The parameter design is: Among them, the parameter a is used to distinguish the structural configuration of the rectifier bridge circuit, a=n / 2, n means that the rectifier bridge is an n-times voltage structure, M represents the voltage gain of the resonant converter, M = U o / U i , U o is the output voltage, U i is the input voltage, n T is the transformer ratio, P o is the rated output power of the converter, f s is the switching frequency; Step 3. Multiple voltage-doubling resonant converters are input and output in parallel to form a multi-module parallel voltage-doubling resonant converter. When the power of the converter is less than the set value, the voltage gain of the converter slowly decreases as the output power increases. When the power of the converter increases to the set value, the voltage gain of the power module decreases rapidly as the output power increases. The power difference between different power modules at the same voltage gain is very small, thereby realizing autonomous current sharing of multiple modules of the converter.

2. The autonomous current balancing method for parallel input and parallel output of voltage-doubling resonant converter according to claim 1, characterized in that When the power of the converter increases to a set value, the relationship between the voltage gain and the output power of the converter is: Among them, the resonant capacitor C r =C r1 =C r2 .

3. The autonomous current balancing method for parallel input and parallel output of voltage-doubling resonant converter according to claim 1, characterized in that The voltage doubler resonant converter includes an input filter capacitor C i , inverter bridge circuit, transformer, resonant inductor L r , the first resonant capacitor C r1 , the second resonant capacitor C r2 , rectifier bridge circuit, output filter capacitor C o .

4. The autonomous current balancing method for parallel input and parallel output of voltage-doubling resonant converters according to claim 3, characterized in that The inverter bridge circuit is a half-bridge structure or a full-bridge structure.

5. The autonomous current balancing method for parallel input and parallel output of voltage-doubling resonant converters according to claim 3, characterized in that The rectifier bridge circuit is an n-voltage multiplication structure.

6. The autonomous current balancing method for parallel input and parallel output of voltage-doubling resonant converters according to claim 3, characterized in that The resonant inductor L r The parameter design method is: Among them, f r Represents the resonant frequency of the resonant converter, and the resonant capacitor C r =C r1 =C r2 .

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