A self-balancing bipolar converter and a control method thereof

Abstract

The application relates to the technical field of switching power supplies, and provides a self-balancing bipolar converter and a control method thereof. The self-balancing bipolar converter comprises a Buck-Boost circuit, a DAB circuit, a first output capacitor, a second output capacitor, a first load and a second load. The Buck-Boost circuit comprises a first switch tube bridge arm, a second switch tube bridge arm, a power supply, a direct-current inductor and an input capacitor. The DAB circuit comprises the second switch tube bridge arm, a transformer, an excitation inductor and a third switch tube bridge arm. The control method comprises the following steps: controlling the first switch tube bridge arm and the second switch tube bridge arm by using a first duty cycle; constructing a balance relationship formula; solving the balance relationship formula to obtain a second duty cycle; and controlling the third switch tube bridge arm by using the second duty cycle. The self-balancing bipolar converter can adaptively balance bipolar output voltages.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of switching power supply, in particular to a self-balancing bipolar converter and a control method thereof. BACKGROUND

[0002] With the development of renewable energy and distributed power supply technology, DC microgrid has attracted extensive attention due to its advantages of clean and efficient, simplified structure and easy access to distributed power supply. According to the power supply voltage level, the DC system can be divided into single-pole and bipolar structures. Compared with the single-pole DC system, the bipolar DC system adopts a three-wire configuration, which can provide three voltage levels and adapt to various DC-DC (Direct Current to Direct Current) converters, and has higher flexibility and reliability. The dual active bridge bidirectional DC converter is one of the typical solutions of the isolated bidirectional DC converter. This kind of converter is composed of two full-bridge conversion units, an energy transmission inductor and an isolation transformer. The traditional dual active bridge bidirectional DC converter usually adopts phase-shifted control, which has a simple control method and realizes power control by adjusting the phase-shift angle. However, in a wide input or output voltage range, the soft switching range is limited. When it is applied in a bipolar output occasion, the current and soft switching characteristics change. Moreover, the energy is coupled between the two output ports, and under the influence of load resistance, line resistance and renewable energy distribution, there is a problem of uneven bipolar output voltage of the converter. SUMMARY

[0003] The present application provides a self-balancing bipolar converter and a control method thereof, which can solve the problem of uneven bipolar output voltage of the converter.

[0004] In a first aspect, the present application provides a self-balancing bipolar converter, comprising: a Buck-Boost circuit, a DAB circuit, a first output capacitor, a second output capacitor, a first load, and a second load.

[0005] The Buck-Boost circuit comprises a first switch tube bridge arm, a second switch tube bridge arm, a power supply, a DC inductor, and an input capacitor.

[0006] The DAB circuit comprises a second switch tube bridge arm, a transformer, an excitation inductor, and a third switch tube bridge arm.

[0007] The positive pole of the power supply is connected with the first end of the first switch tube bridge arm, the negative pole of the power supply is connected with the second end of the first switch tube bridge arm, the second end of the second switch tube bridge arm and the second end of the input capacitor respectively, the first end of the input capacitor is connected with the first end of the second switch tube bridge arm, the third end of the first switch tube bridge arm is connected with the first end of the primary side of the transformer and the first end of the direct current inductor respectively, the second end of the direct current inductor is connected with the third end of the second switch tube bridge arm and the second end of the primary side of the transformer respectively, the first end of the third switch tube bridge arm is connected with the first end of the first output capacitor and the first end of the first load respectively, the second end of the third switch tube bridge arm is connected with the second end of the second output capacitor and the second end of the second load respectively, the first end of the secondary side of the transformer is connected with the third end of the third switch tube bridge arm and the first end of the excitation inductor respectively, the second end of the secondary side of the transformer is connected with the second end of the excitation inductor, the second end of the first output capacitor, the first end of the second output capacitor and the ground end respectively, and the second end of the first load is connected with the first end of the second load.

[0008] Optionally, the first switch tube bridge arm comprises a first switch tube and a third switch tube.

[0009] The drain of the first switch tube is the first end of the first switch tube bridge arm, the source of the third switch tube is the second end of the first switch tube bridge arm, and the source of the first switch tube and the drain of the third switch tube are the third end of the first switch tube bridge arm.

[0010] Optionally, the second switch tube bridge arm comprises a second switch tube and a fourth switch tube.

[0011] The drain of the second switch tube is the first end of the second switch tube bridge arm, the source of the fourth switch tube is the second end of the second switch tube bridge arm, and the source of the second switch tube and the drain of the fourth switch tube are the third end of the second switch tube bridge arm.

[0012] Optionally, the third switch tube bridge arm comprises a fifth switch tube and a sixth switch tube.

[0013] The drain of the fifth switch tube is the first end of the third switch tube bridge arm, the source of the sixth switch tube is the second end of the third switch tube bridge arm, and the source of the fifth switch tube and the drain of the sixth switch tube are the third end of the third switch tube bridge arm.

[0014] Optionally, the transformer comprises a leakage inductor and an ideal transformer.

[0015] The first end of the leakage inductor is the first end of the primary side of the transformer, the second end of the primary side of the ideal transformer is the second end of the primary side of the transformer, the first end of the secondary side of the ideal transformer is the first end of the secondary side of the transformer, and the second end of the secondary side of the ideal transformer is the second end of the secondary side of the transformer.

[0016] The second end of the leakage inductor is connected with the first end of the primary side of the ideal transformer.

[0017] Optionally, the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube and the sixth switch tube are MOSFET tubes.

[0018] In a second aspect, the present application provides a control method of a self-balancing bipolar converter, the control method comprising:

[0019] controlling the first switch tube bridge arm and the second switch tube bridge arm of the self-balancing bipolar converter by using a first duty ratio;

[0020] constructing a balance relationship between a first output voltage of a first load and a second output voltage of a second load; the balance relationship is used to describe the relationship between the first output voltage and the second output voltage;

[0021] solving the balance relationship to obtain a second duty ratio;

[0022] controlling the third switch tube bridge arm of the self-balancing bipolar converter by using the second duty ratio.

[0023] Optionally, the controlling the first switch tube bridge arm and the second switch tube bridge arm of the self-balancing bipolar converter by using the first duty ratio comprises:

[0024] setting the duty ratios of the first switch tube and the third switch tube in the first switch tube bridge arm as and setting the duty ratios of the second switch tube and the fourth switch tube in the second switch tube bridge arm as ; the first duty ratio is represented as

[0025] generating a driving signal according to the duty ratios of the first switch tube and the third switch tube, and controlling the first switch tube and the third switch tube;

[0026] generating a driving signal according to the duty ratios of the second switch tube and the fourth switch tube, and controlling the second switch tube and the fourth switch tube.

[0027] Optionally, the balance relationship is:

[0028] ;

[0029] wherein, the first output voltage is represented as the second output voltage is represented as the second duty ratio is represented as

[0030] Optionally, the controlling the third switch tube bridge arm of the self-balancing bipolar converter by using the second duty ratio comprises:

[0031] The duty cycle of the fifth switch tube in the third switch tube bridge arm is set as The duty cycle of the sixth switch tube in the third switch tube bridge arm is set as ;

[0032] A driving signal is generated according to the duty cycle of the fifth switch tube, and the fifth switch tube is controlled;

[0033] A driving signal is generated according to the duty cycle of the sixth switch tube, and the sixth switch tube is controlled.

[0034] The above-mentioned scheme of the present application has the following beneficial effects:

[0035] In the embodiment of the present application, the self-balancing bipolar converter includes a Buck-Boost circuit, a DAB circuit, a first output capacitor, a second output capacitor, a first load, and a second load, so that the output voltage is adjusted by controlling the duty cycles of the first switch tube bridge arm and the second switch tube bridge arm through two groups of driving signals, the duty cycle of the transformer secondary side switch tube is constant to realize automatic bipolar voltage balance, when the load is unbalanced, the bias current generated by the excitation inductance compensates for the unbalanced power, that is, the bipolar output and voltage automatic balance can be met, the bipolar voltage stability can be maintained autonomously under the condition of load imbalance, and the two output ports can stably output bipolar voltages with the same size and opposite directions.

[0036] In addition, the Buck-Boost circuit and the DAB circuit switch tube are multiplexed, which effectively reduces the volume, weight and energy loss of the converter.

[0037] Other beneficial effects of the present application will be described in detail in the subsequent specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0039] Figure 1 A topological structure diagram of the self-balancing bipolar converter provided by an embodiment of the present application is provided.

[0040] Figure 2 A flowchart of the control method of the self-balancing bipolar converter provided by an embodiment of the present application is provided.

[0041] Figure 3 A waveform diagram of the self-balancing bipolar converter provided by an embodiment of the present application is provided.

[0042] Figure 4 Fig. 1 shows a schematic diagram of a circuit path of a first mode according to an embodiment of the present application;

[0043] Figure 5 Fig. 2 shows a schematic diagram of a circuit path of a second mode according to an embodiment of the present application;

[0044] Figure 6 Fig. 3 shows a schematic diagram of a circuit path of a third mode according to an embodiment of the present application;

[0045] Figure 7 Fig. 4 shows a schematic diagram of a circuit path of a fourth mode according to an embodiment of the present application. DETAILED DESCRIPTION

[0046] In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular architectures, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods, devices, circuits, and

[0047] It will be understood that the terms "comprises" and / or "comprising," when used in this specification, include the presence of one or more features, integers, steps, operations, elements, and / or components described in the specification, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0048] It will be understood that the term "and / or," when used in the specification and in the claims, is intended to mean one or more of the associated listed items can be present, and, further, that any combination of the associated listed items can be present.

[0049] As used in the description of the application and the appended claims, the term "if' can be interpreted to mean "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrase "if it is determined" or "if [a described condition or event] is detected" can be interpreted to mean "upon determining" or "in response to determining" or "upon [the described condition or event] being detected" or "in response to [the described condition or event] being detected," depending on the context.

[0050] In addition, the terms "first," "second," "third," etc. are used herein only to describe different instances of elements, and are not intended to imply or suggest relative importance of the elements.

[0051] Reference throughout this application to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. The appearances of the phrase "in one embodiment" or "in some embodiments" in various places in the specification are not necessarily all referring to the same embodiment, however, and can refer to one or more but less than all of the embodiments of the application, unless otherwise specified. The terms "including," "comprising," "having" and variations thereof herein are meant to be open-ended terms that can cover the presence of substrates, integers, steps, operations, elements, components, objects, and / or the like, but not excluding the presence of one or more other substrates, integers, steps, operations, elements, components, objects, and / or the like.

[0052] In order to solve the problem of uneven bipolar output voltage of the existing converter, the application provides a self-balancing bipolar converter and a control method thereof. The self-balancing bipolar converter comprises a Buck-Boost circuit, a DAB circuit, a first output capacitor, a second output capacitor, a first load, and a second load. The duty cycle of the first switch bridge arm and the second switch bridge arm is controlled by two groups of driving signals respectively to adjust the output voltage. The duty cycle of the switch on the secondary side of the transformer is constant to realize automatic bipolar voltage balancing. When the loads are unbalanced, the bias current generated by the excitation inductance compensates for the unbalanced power, so that the bipolar output and voltage automatic balancing can be met, the bipolar voltage stability can be maintained autonomously under the condition of load imbalance, and the two output ports can stably output bipolar voltages with the same size and opposite directions.

[0053] In addition, the switch tubes of the Buck-Boost circuit and the DAB circuit are multiplexed, which effectively reduces the volume, weight and energy loss of the converter.

[0054] Next, the structure of the self-balancing bipolar converter provided by the application will be described by way of example.

[0055] As shown in Figure 1 , the self-balancing bipolar converter comprises a Buck-Boost circuit, a DAB circuit, a first output capacitor ( Figure 1 in the ), a second output capacitor ( Figure 1 in the ), a first load ( Figure 1 in the ), and a second load ( Figure 1 in the ).

[0056] The Buck-Boost circuit comprises a first switch bridge arm, a second switch bridge arm, a power supply ( Figure 1 in the ), a direct-current inductor ( Figure 1 in the ), and an input capacitor ( Figure 1In ).

[0057] The DAB circuit includes the second switching bridge arm, a transformer, and a magnetizing inductor. Figure 1 In ), the third switch tube bridge arm.

[0058] The positive terminal of the power supply ( Figure 1 The + sign in the circuit is connected to the first end of the first switching bridge arm, and the negative terminal of the power supply is ( Figure 1 The -) in the diagram are respectively connected to the second end of the first switching bridge arm, the second end of the second switching bridge arm, and the second end of the input capacitor. The first end of the input capacitor is connected to the first end of the second switching bridge arm, and the third end of the first switching bridge arm ( Figure 1 Point A in the diagram is connected to the first terminal of the primary winding of the transformer and the first terminal of the DC inductor, respectively. The second terminal of the DC inductor is connected to the third terminal of the second switching bridge arm. Figure 1 Point B in the diagram is connected to the second terminal of the primary side of the transformer. The first terminal of the third switching bridge arm is connected to the first terminal of the first output capacitor and the first terminal of the first load, respectively. The second terminal of the third switching bridge arm is connected to the second terminal of the second output capacitor and the second terminal of the second load, respectively. The first terminal of the secondary side of the transformer is connected to the third terminal of the third switching bridge arm. Figure 1 Point C in the diagram) is connected to the first terminal of the magnetizing inductor, and the second terminal of the transformer secondary is connected to the second terminal of the magnetizing inductor and the second terminal of the first output capacitor, respectively. Figure 1 Point D in the diagram is connected to the first terminal of the second output capacitor and the ground terminal, and the second terminal of the first load is connected to the first terminal of the second load.

[0059] The first switching transistor bridge arm includes the first switching transistor ( Figure 1 In ) and the third switching transistor ( Figure 1 In ).

[0060] The drain of the first switching transistor is the first end of the first switching transistor bridge arm, the source of the third switching transistor is the second end of the first switching transistor bridge arm, and the source of the first switching transistor and the drain of the third switching transistor are the third ends of the first switching transistor bridge arm.

[0061] The second switching transistor bridge arm includes the second switching transistor ( Figure 1 In ) and the fourth switch ( Figure 1 In ).

[0062] The drain of the second switch is the first end of the second switch bridge arm, the source of the fourth switch is the second end of the second switch bridge arm, and the source of the second switch and the drain of the fourth switch are the third ends of the second switch bridge arm.

[0063] The third switch tube bridge arm includes a fifth switch tube (Q5) Figure 1 ) and a sixth switch tube (Q6) Figure 1 ).

[0064] The drain of the fifth switch tube is the first end of the third switch tube bridge arm, the source of the sixth switch tube is the second end of the third switch tube bridge arm, and the source of the fifth switch tube and the drain of the sixth switch tube are the third end of the third switch tube bridge arm.

[0065] The transformer includes a leakage inductance (L1) Figure 1 ) and an ideal transformer (T1) Figure 1 , and the turns ratio of the primary side and the secondary side is n:1.

[0066] The first end of the leakage inductance is the first end of the transformer primary side, the second end of the ideal transformer primary side is the second end of the transformer primary side, the first end of the ideal transformer secondary side is the first end of the transformer secondary side, and the second end of the ideal transformer secondary side is the second end of the transformer secondary side.

[0067] The second end of the leakage inductance is connected to the first end of the ideal transformer primary side.

[0068] For example, the leakage inductance, the excitation inductance, and the ideal transformer can be regarded as a whole transformer.

[0069] Figure 2 is the voltage between point A, which is the source of the first switch tube, and point B, which is the drain of the fourth switch tube, is the voltage between point C, which is the source of the fifth switch tube, and point D, which is the first end of the second output capacitor, is the current of the excitation inductance, is the first output voltage of the first load, i.e., output terminal 1, is the second output voltage of the second load, i.e., output terminal 2.

[0070] It should be noted that the first switch tube, the second switch tube, the third switch tube, the fourth switch tube, the fifth switch tube, and the sixth switch tube are all MOSFET tubes.

[0071] The working principle of the self-balancing bipolar converter of the present application is as follows:

[0072] The duty cycle of the first switch tube and the third switch tube, and the duty cycle of the second switch tube and the fourth switch tube are controlled by two groups of driving signals to adjust the voltage of the transformer primary side, and the first duty cycle is controlled to make and ​​​​​The volt-second product in a half cycle is equal to broaden the zero voltage switching (ZVS); by controlling the bridge phase shift duty cycle to adjust the output power, the duty cycle of the transformer secondary side switch tube is constant 0.5 to realize automatic bipolar voltage balance. When the load is unbalanced, the excitation inductance current generates a bias current to compensate for the unbalanced power, that is, the bipolar output and voltage automatic balance can be met. Specifically, assuming that the total power is , the upper and lower port powers are and When , , the power demand of the side increases, a positive DC bias current is generated in the excitation inductance, which flows to the side, compensates for the power shortage of the , and finally makes the two port voltages symmetrical and consistent.

[0073] It is worth mentioning that the self-balancing bipolar converter of the application can meet the bipolar output and voltage automatic balance, realize self-maintenance of bipolar voltage stability under load imbalance, and the two output ports can stably output bipolar voltage with the same size and opposite direction.

[0074] In addition, the Buck-Boost circuit and the DAB circuit switch tube are multiplexed, which effectively reduces the volume, weight and energy loss of the converter.

[0075] The control method of the self-balancing bipolar converter provided by the application will be exemplarily described below.

[0076] As shown in Figure 3 , the control method of the self-balancing bipolar converter provided by the application includes the following steps:

[0077] Step 21, controlling the first switch tube bridge arm and the second switch tube bridge arm of the self-balancing bipolar converter by using the first duty cycle.

[0078] The first switch bridge arm, the second switch bridge arm, the direct current inductor and the input capacitor constitute the primary side of the self-balancing bipolar converter.

[0079] Specifically, the duty cycles of the first switch tube and the third switch tube in the first switch tube bridge arm are set to , and the duty cycles of the second switch tube and the fourth switch tube in the second switch tube bridge arm are set to ; The first duty cycle represents the first duty cycle; the driving signal is generated according to the duty cycles of the first switch tube and the third switch tube, and the first switch tube and the third switch tube are controlled; the driving signal is generated according to the duty cycles of the second switch tube and the fourth switch tube, and the second switch tube and the fourth switch tube are controlled.

[0080] Exemplarily, the unipolar carrier modulation method and the PWM generating circuit can be used to generate the driving signal according to the duty ratio, and the driving signal can be used to control the on-off of the corresponding switch tube.

[0081] Step 22, a balance relationship between the first output voltage of the first load and the second output voltage of the second load is constructed.

[0082] The balance relationship is used to describe the relationship between the first output voltage and the second output voltage.

[0083] The balance relationship is:

[0084] ;

[0085] wherein, the first output voltage is represented by Vout1, the second output voltage is represented by Vout2, and the second duty ratio is represented by D2.

[0086] Step 23, the balance relationship is solved to obtain the second duty ratio.

[0087] It should be noted that, in order to balance the first output voltage and the second output voltage, in the above balance relationship, the first output voltage is equal to the second output voltage, and the second duty ratio obtained by solving is equal to 0.5.

[0088] Step 24, the second duty ratio is used to control the third switch tube bridge arm of the self-balancing bipolar converter.

[0089] The third switch tube bridge arm, the first output capacitor, the second output capacitor, the first load and the second load constitute the secondary side of the self-balancing bipolar converter.

[0090] Specifically, the duty ratio of the fifth switch tube in the third switch tube bridge arm is set to , the duty ratio of the sixth switch tube in the third switch tube bridge arm is set to , a driving signal is generated according to the duty ratio of the fifth switch tube, and the fifth switch tube is controlled, and a driving signal is generated according to the duty ratio of the sixth switch tube, and the sixth switch tube is controlled.

[0091] Exemplarily, the unipolar carrier modulation method and the PWM generating circuit can be used to generate the driving signal according to the duty ratio, and the driving signal can be used to control the on-off of the corresponding switch tube.

[0092] It should be noted that when connected to an unbalanced load, the unbalanced load will not affect the left side leakage inductance current waveform. Assuming that the total power is , the upper and lower port powers are and When When, The increase of the power demand on the side generates a positive DC bias current in the excitation inductance, which flows to the side, compensates for the power shortage, and finally makes the two-port voltages symmetrical and consistent. The converter can achieve voltage balance without any additional voltage balancer.

[0093] It is worth mentioning that the control method of the application can provide a DC bias current to achieve autonomous maintenance of bipolar voltage stability under load imbalance, and the two output ports can stably output bipolar voltages of the same size and opposite directions.

[0094] The self-balancing bipolar converter of the application will be exemplarily described below in combination with a specific example.

[0095] Under balanced load, the waveform diagram of the self-balancing bipolar converter when working is as shown in Figure 3 , Figure 4 In , , , , are time points in a switching period , represents the current of the leakage inductance, represents the current of the excitation inductance, represents the current of the DC inductance, represents the voltage between point A and point B, represents the voltage between point C and point D, represents the phase shift angle between the second switch tube and the sixth switch tube, represents the first duty ratio, represents the second duty ratio, represents the first switch tube, represents the second switch tube, represents the fifth switch tube, represents the sixth switch tube.

[0096] A switching period includes four switching modes, which are as follows:

[0097] Mode 1 ~ ): The circuit path of this mode is as shown in Figure 5 , the first switch tube, the fourth switch tube and the sixth switch tube are in the on state, and the second switch tube, the third switch tube and the fifth switch tube are in the off state. At the beginning of this mode, the full-bridge circuit is connected with the power supply, the secondary side current flows through the sixth switch tube, the DC inductance, the leakage inductance and the excitation inductance all start to store energy, and the current linearly increases.​ At this time, the change amount expressions of the direct current inductor current , the leakage current , and the excitation inductor current are:

[0098]

[0099]

[0100]

[0101] wherein, represents the turns ratio of the primary side and the secondary side of the transformer.

[0102] Mode two ( ): The circuit path of this mode is shown in FIG. 2, the first switch tube, the fourth switch tube, and the fifth switch tube are in the on state, and the second switch tube, the third switch tube, and the sixth switch tube are in the off state. In this mode, the direct current inductor and the leakage current continue to increase, the excitation inductor current changes direction, and the secondary side current continues to flow through the sixth switch tube, Figure 6 At this time, the change amount expressions of the direct current inductor current , the leakage current , and the excitation inductor current are:

[0103]

[0104]

[0105]

[0106] Mode three ( ): The circuit path of this mode is shown in FIG. 3, the second switch tube, the third switch tube, and the fifth switch tube are in the on state, and the first switch tube, the fourth switch tube, and the sixth switch tube are in the off state. In this mode, the full-bridge circuit connection is disconnected with the power supply, the direct current inductor begins to discharge, the leakage current changes direction, and the excitation inductor current continues to increase, Figure 7 At this time, the change amount expressions of the direct current inductor current , the leakage current , and the excitation inductor current​​​​​​​​​​​​​​​​​​​ The expression for the change is:

[0107] ;

[0108] ;

[0109] ;

[0110] Modal 4 ( ~ The circuit path for this mode is as follows: Figure 3 As shown, when the second, third, and sixth switches are in the ON state, and the first, second, and fifth switches are in the OFF state, in this mode, the DC inductor and the magnetizing inductor release their stored energy, and the leakage inductance current increases linearly. = , = At this time, the DC inductor current... Leakage inductance current and excitation inductor current The expression for the change is:

[0111] ;

[0112] ;

[0113] ;

[0114] The leakage current value at each moment can be calculated from the above formula, and the expression for the average output power can be obtained. It can be seen from the expression that the transmission power is only related to the phase shift duty cycle within the bridge and the phase shift duty cycle between the bridges.

[0115] Simulations were performed on the self-balancing bipolar converter provided in this application under unbalanced load conditions, and the obtained simulation waveforms are shown below. Figure 1 The waveform shown is under balanced load. ​ To.

[0116] Therefore, the self-balancing bipolar converter of this application can automatically balance the bipolar output voltage under different loads, realize the autonomous maintenance of bipolar voltage stability under load imbalance, greatly reduce the influence of external load, and has good soft switching characteristics. It can complete wide voltage and high efficiency conversion in single-stage isolation conversion, improve power transmission efficiency, and ensure the stability of signal generation.

[0117] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0118] The above are preferred embodiments of the present application, it should be pointed out that, for those skilled in the art, without departing from the principles described in the present application, can make a number of improvements and refinements, these improvements and refinements should also be considered as the scope of protection of the present application.

Claims

1. A self-balancing bipolar converter, characterized by, include: Buck-Boost circuit, DAB circuit, first output capacitor, second output capacitor, first load, second load; The Buck-Boost circuit includes a first switching bridge arm, a second switching bridge arm, a power supply, a DC inductor, and an input capacitor. The DAB circuit includes a second switching bridge arm, a transformer, a magnetizing inductor, and a third switching bridge arm. The positive terminal of the power supply is connected to the first end of the first switching bridge arm. The negative terminal of the power supply is connected to the second end of the first switching bridge arm, the second end of the second switching bridge arm, and the second end of the input capacitor. The first end of the input capacitor is connected to the first end of the second switching bridge arm. The third end of the first switching bridge arm is connected to the first end of the primary side of the transformer and the first end of the DC inductor. The second end of the DC inductor is connected to the third end of the second switching bridge arm and the second end of the primary side of the transformer. The first end of the third switching bridge arm is connected to the first end of the first output capacitor and the first end of the first load. The second end of the third switching bridge arm is connected to the second end of the second output capacitor and the second end of the second load. The first end of the secondary side of the transformer is connected to the third end of the third switching bridge arm and the first end of the magnetizing inductor. The second end of the secondary side of the transformer is connected to the second end of the magnetizing inductor, the second end of the first output capacitor, the first end of the second output capacitor, and ground. The second end of the first load is connected to the first end of the second load.

2. The self-balancing bipolar converter according to claim 1, characterized in that, The first switch bridge arm includes a first switch and a third switch; The drain of the first switching transistor is the first end of the first switching transistor bridge arm, the source of the third switching transistor is the second end of the first switching transistor bridge arm, and the source of the first switching transistor and the drain of the third switching transistor are the third ends of the first switching transistor bridge arm.

3. The self-balancing bipolar converter according to claim 2, characterized in that, The second switch bridge arm includes a second switch and a fourth switch; The drain of the second switch is the first end of the second switch bridge arm, the source of the fourth switch is the second end of the second switch bridge arm, and the source of the second switch and the drain of the fourth switch are the third ends of the second switch bridge arm.

4. The self-balancing bipolar converter according to claim 3, characterized in that, The third switch bridge arm includes a fifth switch and a sixth switch; The drain of the fifth switch is the first end of the third switch bridge arm, the source of the sixth switch is the second end of the third switch bridge arm, and the source of the fifth switch and the drain of the sixth switch are the third ends of the third switch bridge arm.

5. The self-balancing bipolar converter according to claim 4, characterized in that, The transformer includes leakage inductance and an ideal transformer; The first end of the leakage inductance is the first end of the primary side of the transformer, the second end of the primary side of the ideal transformer is the second end of the primary side of the transformer, the first end of the secondary side of the ideal transformer is the first end of the secondary side of the transformer, and the second end of the secondary side of the ideal transformer is the second end of the secondary side of the transformer. The second end of the leakage inductance is connected to the first end of the primary side of the ideal transformer.

6. The self-balancing bipolar converter according to claim 5, characterized in that, The first, second, third, fourth, fifth, and sixth switching transistors are all MOSFETs.

7. A control method for a self-balancing bipolar converter, characterized in that, The control method, applied to the self-balancing bipolar converter as described in any one of claims 1 to 6, comprises: The first and second switching bridge arms of the self-balancing bipolar converter are controlled using the first duty cycle. A balance equation is constructed between the first output voltage of the first load and the second output voltage of the second load; the balance equation is used to describe the relationship between the first output voltage and the second output voltage. Solving the aforementioned balance equation yields the second duty cycle; The third switching bridge arm of the self-balancing bipolar converter is controlled using the second duty cycle.

8. The control method according to claim 7, characterized in that, The control of the first and second switching bridge arms of the self-balancing bipolar converter using the first duty cycle includes: Set the duty cycle of the first and third switching transistors in the first switching transistor bridge arm to... The duty cycles of the second and fourth switches in the second switch bridge arm are set to... ; Indicates the first duty cycle; Drive signals are generated based on the duty cycles of the first and third switching transistors, and the first and third switching transistors are controlled accordingly. Drive signals are generated based on the duty cycles of the second and fourth switches, and the second and fourth switches are controlled accordingly.

9. The control method according to claim 8, characterized in that, The equilibrium relationship is as follows: ； in, Indicates the first output voltage. Indicates the second output voltage. This indicates the second duty cycle.

10. The control method according to claim 9, characterized in that, The control of the third switching bridge arm of the self-balancing bipolar converter using the second duty cycle includes: Set the duty cycle of the fifth switch in the third switch bridge arm to... The duty cycle of the sixth switch in the third switch bridge arm is set to... ; A drive signal is generated based on the duty cycle of the fifth switch, and the fifth switch is controlled accordingly. A drive signal is generated based on the duty cycle of the sixth switch, and the sixth switch is controlled.

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