A power conversion circuit, a control method thereof and an energy storage device

Abstract

The present application relates to the field of electronic circuit technology, and discloses a power conversion circuit, a control method thereof, and an energy storage device, including a control unit, at least one sampling resistor, and a plurality of parallel drive units, each drive unit including at least one inductor and a first half-bridge formed by two switch tubes connected in series; a control unit for obtaining the working mode of the power conversion circuit and the state parameters corresponding to the current working mode, and determining the target current value of the inductor according to the state parameters; the control unit is also used to obtain the dual current sampling value of the sampling resistor corresponding to the current working mode, and control each drive unit according to the dual current sampling value and the target current value of the inductor to charge or discharge the battery. The present application achieves the purpose of reducing the volume of the switch tube and the inductor by staggered parallel connection of multiple small-volume drive units, which can not only provide power density. The drive unit is also controlled by the dual sampling value and the target current value of the inductor to reduce energy loss.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to a power conversion circuit, a control method thereof, and an energy storage device. Background Art

[0002] In existing high-rate battery charging and discharging scenarios (e.g., data center backup power, industrial and commercial energy storage, etc.), the power density is low due to hardware structure problems of the power conversion circuit. In addition, during the operation, there is energy loss, which leads to low battery charging and discharging efficiency, making it impossible to achieve high-rate charging and discharging functions. Summary of the invention

[0003] In view of this, the embodiments of the present application provide a power conversion circuit, a control method thereof, and an energy storage device, which can effectively solve the problems of low charging and discharging efficiency and low power density.

[0004] In a first aspect, an embodiment of the present application provides a power conversion circuit, which is arranged between a battery and a load, and the power conversion circuit includes a control unit, at least one sampling resistor and a plurality of drive units connected in parallel, each of the drive units includes at least one inductor and a first half bridge formed by two switch tubes connected in series;

[0005] The control unit is used to obtain the working mode of the power conversion circuit and the state parameters corresponding to the current working mode, and determine the inductor target current value according to the state parameters;

[0006] The control unit is further used to obtain the dual current sampling value of the sampling resistor corresponding to the current working mode, and control each driving unit according to the dual current sampling value and the inductor target current value to charge or discharge the battery.

[0007] In some embodiments, the first end of each of the drive units is connected in parallel to connect to the positive terminal of the load; the second end of each of the drive units is connected in parallel to connect to the negative terminal of the battery and the negative terminal of the load respectively; the third end of each of the drive units is connected in parallel to connect to the positive terminal of the battery.

[0008] In some embodiments, the upper arm of the first half bridge is connected to the positive terminal of the load, the lower arm of the first half bridge is respectively connected to the negative terminal of the load and the negative terminal of the battery, and the middle point of the first half bridge is connected to the positive terminal of the battery through the inductor.

[0009] In some embodiments, the upper arm of the first half bridge is connected to the positive terminal of the battery, the lower arm of the first half bridge is respectively connected to the negative terminal of the load and the negative terminal of the battery, and the middle point of the first half bridge is connected to the positive terminal of the load through the inductor.

[0010] In some embodiments, each of the driving units includes the inductor, the first half-bridge and the second half-bridge forming an H-bridge with the first half-bridge; the upper bridge arm of the first half-bridge is connected to the positive terminal of the load, the lower bridge arm of the first half-bridge is connected in parallel with the lower bridge arm of the second half-bridge and is respectively connected to the negative terminal of the load and the negative terminal of the battery, and the upper bridge arm of the second half-bridge is connected to the positive terminal of the battery.

[0011] In some embodiments, the power conversion circuit includes a discharge sampling resistor and / or a charge sampling resistor;

[0012] The discharge sampling resistor is connected in series between the driving unit and the load;

[0013] The charging sampling resistor is connected in series between the driving unit and the battery.

[0014] In some embodiments, the types of the working modes include a charging boost mode, a discharging boost mode, and a discharging buck mode;

[0015] In the charging boost mode, the power conversion circuit includes the charging sampling resistor, or the charging sampling resistor and the discharging sampling resistor;

[0016] In the discharge boost mode or the discharge buck mode, the power conversion circuit includes a discharge sampling resistor, or a discharge sampling resistor and a charge sampling resistor.

[0017] In a second aspect, an embodiment of the present application provides a control method for a power conversion circuit, which is applied to the above-mentioned power conversion circuit; the control unit performs the following steps, including:

[0018] Obtaining the working mode of the power conversion circuit and the state parameters corresponding to the current working mode, and sequentially turning on the target switch tube in each target half-bridge and turning off another switch tube in the target half-bridge according to the preset phase difference and the state parameters, wherein the target half-bridge is the half-bridge in the driving unit;

[0019] Determining a target inductor current value according to the state parameter;

[0020] A dual current sampling value of the sampling resistor corresponding to the current working mode is obtained, and each driving unit is controlled according to the dual current sampling value and the inductor target current value, so that the battery is charged or discharged.

[0021] In some embodiments, controlling each driving unit according to the dual current sampling value and the inductor target current value includes:

[0022] When the double current sampling values ​​are both greater than the inductor target current value, two switch tubes in the corresponding target half-bridge are controlled to be complementary turned on in the next switching cycle of each target switch tube;

[0023] When complementary conduction occurs, if any current sampling value of the dual current sampling values ​​is less than the target inductor current value, the target switch tube pulse width in the corresponding target half bridge is controlled to be turned on and the other switch tube is turned off in the next switching cycle of each target switch tube.

[0024] In some embodiments, the state parameters include a duty cycle and a switching period of each target switch tube, a voltage across the battery, and a voltage across the load;

[0025] The step of determining the target inductor current value according to the state parameter comprises:

[0026] The inductor target current value is determined according to the duty cycle, the switching period, the voltage across the battery, and the voltage across the load.

[0027] In some embodiments, the dual current sampling value includes a first current sampling value and a second current sampling value;

[0028] The sampling time of the first current sampling value is the midpoint of the current rise time in each switching cycle of the reference switch tube, and the sampling time of the second current sampling value is the midpoint of the current fall time in each switching cycle of the reference switch tube. The reference switch tube is one of all the target switch tubes.

[0029] In some embodiments, the preset phase difference is determined according to a switching period of the target switch tube and a total number of the driving units.

[0030] In a third aspect, an embodiment of the present application provides an energy storage device, comprising the above-mentioned power conversion circuit, wherein the power conversion circuit comprises a control unit, and the control unit is used to execute the control method of the above-mentioned power conversion circuit.

[0031] The embodiments of the present application have the following beneficial effects:

[0032] The present application proposes a power conversion circuit, including a control unit, at least one sampling resistor and a plurality of parallel drive units, each of the drive units including at least one inductor and a first half-bridge formed by two switch tubes connected in series; the control unit is used to obtain the working mode of the power conversion circuit and the state parameters corresponding to the current working mode, and determine the target current value of the inductor according to the state parameters; the control unit is also used to obtain the dual current sampling value of the sampling resistor corresponding to the current working mode, and control each drive unit according to the dual current sampling value and the target current value of the inductor, so that the battery is charged or discharged. The present application achieves the purpose of reducing the volume of the switch tube and the inductor by staggered parallel connection of multiple small-volume drive units, which can not only provide power density, but also can be integrated into a PCB (Printed Circuit Board) board. At the same time, the drive unit is controlled by dual sampling values ​​and the target current value of the inductor to reduce energy loss and improve energy conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 An application scenario diagram of the power conversion circuit proposed in an embodiment of the present application is shown;

[0035] Figure 2 A first structural schematic diagram of a power conversion circuit proposed in an embodiment of the present application is shown;

[0036] Figure 3 A second structural schematic diagram of a power conversion circuit proposed in an embodiment of the present application is shown;

[0037] Figure 4 A third structural schematic diagram of a power conversion circuit proposed in an embodiment of the present application is shown;

[0038] Figure 5 A fourth structural schematic diagram of a power conversion circuit proposed in an embodiment of the present application is shown;

[0039] Figure 6 A schematic diagram of a flow chart of a control method for a power conversion circuit proposed in an embodiment of the present application is shown;

[0040] Figure 7 A schematic diagram of a current-time triangle wave diagram of an inductor in a power conversion circuit proposed in an embodiment of the present application is shown.

[0041] Explanation of main component symbols: 100-power conversion circuit; 200-battery; 300-load; 110-drive unit; 111-first half bridge; 1111-first upper bridge arm; 1112-first lower bridge arm; 112-second half bridge; 1121-second upper bridge arm; 1122-second lower bridge arm; L-inductor; R1-charging sampling resistor; R2-discharging sampling resistor. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0043] The components of the embodiments of the present application generally described and shown in the drawings herein may be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0044] Hereinafter, the terms "including", "having" and their cognates that can be used in various embodiments of the present application are intended only to indicate specific features, numbers, steps, operations, elements, components or a combination of the foregoing items, and should not be understood as first excluding the existence of one or more other features, numbers, steps, operations, elements, components or a combination of the foregoing items or increasing the possibility of one or more features, numbers, steps, operations, elements, components or a combination of the foregoing items. In addition, the terms "first", "second", "third" and the like are only used to distinguish descriptions and cannot be understood as indicating or implying relative importance.

[0045] Unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meanings as those generally understood by those skilled in the art to which the various embodiments of the present application belong. The terms (such as those defined in generally used dictionaries) will be interpreted as having the same meanings as the contextual meanings in the relevant technical field and will not be interpreted as having idealized meanings or overly formal meanings unless clearly defined in the various embodiments of the present application.

[0046] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0047] In existing high-rate battery charging and discharging scenarios such as data center backup power, industrial and commercial energy storage, and base station energy storage backup power, the power conversion circuit has a large hardware volume, such as inductors and switches, which leads to low power density and narrow application scenarios and directions. In addition, during the operation, there is energy loss, which leads to low battery charging and discharging efficiency, making it impossible to achieve high-rate charging and discharging functions.

[0048] Therefore, in order to solve the above problem, the present application proposes a power conversion circuit 100 .

[0049] Figure 1 FIG. 1 shows an application scenario diagram of a power conversion circuit 100 provided in an embodiment of the present application. Figure 1 As shown, the power conversion circuit 100 is disposed between the battery 200 and the load 300, and is used to adjust the voltage output by the battery 200 to provide the required voltage to the load 300, or to adjust the voltage output by the load 300 to provide a charging voltage to the battery 200. Of course, the above-mentioned battery 200 and load 300 can both be regarded as a load 300 with charging and discharging characteristics, that is, a load device including the battery 200, specifically, depending on the application scenario, and is not limited here.

[0050] The power conversion circuit 100 provided in the present application can be applied to electronic devices such as energy storage devices. The energy storage device can be an electronic device with energy storage function, including self-moving devices such as automotive equipment, lawn mowing equipment, sweeping equipment, and cruise equipment, and also includes mobile energy storage equipment, household energy storage equipment, base station energy storage equipment, industrial and commercial energy storage equipment, data center energy storage equipment and other energy storage equipment, or can also be applied to electrical equipment such as refrigerators, air conditioners, washing machines, or other electronic devices including battery packs. The energy storage device may also include a client device, which includes but is not limited to any electronic product that can interact with the customer through a keyboard, mouse, remote control, touchpad or voice control device, such as a personal computer, tablet computer, smart phone, digital camera, etc.

[0051] It should be noted that the energy storage device is only an example, and other existing or future electronic products that are suitable for the present application should also be included in the protection scope of the present application and included here by reference.

[0052] The following will be combined Figures 2 to 4 The structure of the power conversion circuit 100 provided in the present application is illustrated by way of example.

[0053] In some possible implementations, such as Figure 2A schematic diagram of a power conversion circuit 100 provided in an embodiment of the present application is shown. The power conversion circuit 100 includes a control unit (not shown), a plurality of parallel drive units 110 and at least one sampling resistor (not shown), each drive unit 110 includes at least an inductor L and a first half bridge (not shown) formed by two switch tubes connected in series.

[0054] In some feasible implementations, the power conversion circuit 100 has multiple operating modes, including a boost mode and a buck mode. The control unit controls the switch tube in the power conversion circuit 100 by acquiring the operating mode of the power conversion circuit 100 and the state parameters corresponding to the current operating mode. Among them, the state parameters include the duty cycle and switching cycle of each target switch tube, the voltage across the battery 200 and the voltage across the load 300, etc. Among them, the target switch tube is a switch tube in the first half bridge, and each operating mode corresponds to a target switch tube, that is, the target switch tube in the first half bridge can be determined according to the operating mode.

[0055] Furthermore, when each drive unit 110 is in a stable working state, its inductance L satisfies the "input and output balance" law, that is, the rising value of the current in each switching cycle is equal to the falling value of the current. Based on the law of inductor current change, the inductor target current value when the inductor L is in a stable working state is determined according to the state parameter. Then the dual current sampling value of the sampling resistor corresponding to the current working mode is obtained, and the current state of the power conversion circuit 100 is determined according to the dual current sampling value and the inductor target current value, and then each drive unit 110 is controlled according to the current state of the power conversion circuit 100, so as to adjust the charging or discharging of the battery 200. Among them, the current state of the power conversion circuit 100 includes an energy loss state and a normal state. Among them, the dual current sampling value is two current values ​​calculated respectively according to the two voltage sampling values ​​of the same sampling resistor.

[0056] It is understandable that in existing high-rate charge and discharge applications, large-volume switch tubes and inductors L are usually used to meet the needs of high-rate charge and discharge functions. However, this not only has a narrow application range due to the large size (i.e., it is only suitable for high-rate charge and discharge scenarios), but also reduces the power density. For this problem, the present application reduces the volume of each switch tube and inductor L and other devices, and realizes the high-rate charge and discharge function under the premise of a small volume through the parallel connection of multiple drive units 110, and also improves the power density. Not only that, because the volume of each device is small, the present application is also suitable for integration into a PCB board (Printed Circuit Board) to improve the power density. It is also possible to increase or reduce the number of drive units 110 (which can be detachable) to achieve high versatility in multiple different rate charge and discharge fields.

[0057] In order to solve the problem that energy loss leads to low charging and discharging efficiency of the battery 200, thereby failing to realize high-rate charging and discharging functions, the present application further analyzes the causes of energy loss (which will be described in detail below), and solves the problem of energy loss by determining the target current value of the inductor to control the drive unit 110, thereby effectively improving the energy conversion efficiency.

[0058] In some feasible implementations, the drive unit 110 in this solution includes at least three ports, such as Figure 2 As shown, the first end of each drive unit 110 is connected in parallel to the positive end of the load 300. The second end of each drive unit 110 is connected in parallel to the negative end of the battery 200 and the negative end of the load 300; the third end of each drive unit 110 is connected in parallel to the positive end of the battery 200.

[0059] Of course, the positions of the positive and negative terminals of the load 300 and the battery 200 are not absolute and can be adjusted according to the usage scenario, but the premise is that the positive and negative terminals of the load 300 and the battery 200 correspond.

[0060] In some feasible implementations, due to the versatility of the power conversion circuit 100 of the present application, it can be applied to a variety of scenarios, for example, including a power conversion circuit 100 for charging the battery 200, a power conversion circuit 100 for discharging the battery 200, and a power conversion circuit 100 for discharging and charging the battery 200. The following are examples for explanation.

[0061] In some possible implementations, such as Figure 3 As shown, the upper bridge arm (i.e., the first upper bridge arm 1111) of the first half bridge 111 of the driving unit 110 is connected to the positive terminal of the load 300, the lower bridge arm (i.e., the first lower bridge arm 1112) of the first half bridge 111 is respectively connected to the negative terminal of the load 300 and the negative terminal of the battery 200, and the middle point of the first half bridge 111 is connected to the positive terminal of the battery 200 through the inductor L. The middle point refers to the point where the two switch tubes are connected, and this point is used as the output terminal.

[0062] It should be noted that the types of working modes of the drive unit 110 include a charging boost mode, a discharging boost mode, and a discharging buck mode. If the working mode of the drive unit 110 is the charging boost mode, the power conversion circuit 100 at least includes a charging sampling resistor R1, that is, there are two solutions, the first is that the power conversion circuit 100 includes a charging sampling resistor R1; the second is that the power conversion circuit 100 includes a charging sampling resistor R1 and a discharging sampling resistor R2 (such as Figure 3If the working mode of the driving unit 110 is the discharge boost mode, the power conversion circuit 100 at least includes a discharge sampling resistor R2. There are two solutions. The first is that the power conversion circuit 100 includes a discharge sampling resistor R2; the second is that the power conversion circuit 100 includes a charge sampling resistor R1 and a discharge sampling resistor R2 (such as Figure 3 The power conversion circuit 100 shown).

[0063] In some possible implementations, such as Figure 4 As shown, the upper bridge arm of the first half bridge 111 of the driving unit 110 (i.e., the first upper bridge arm 1111) is connected to the positive terminal of the battery 200, the lower bridge arm of the first half bridge 111 (i.e., the first lower bridge arm 1112) is respectively connected to the negative terminal of the load 300 and the negative terminal of the battery 200, and the middle point of the first half bridge 111 is connected to the positive terminal of the load 300 through the inductor L.

[0064] It should be noted that if the working mode of the driving unit 110 is the discharge buck mode, the power conversion circuit 100 at least includes a discharge sampling resistor R2, that is, there are two solutions. The first is that the power conversion circuit 100 includes a discharge sampling resistor R2; the second is that the power conversion circuit 100 includes a charging sampling resistor R1 and a discharge sampling resistor R2 (such as Figure 4 The power conversion circuit 100 shown).

[0065] In some possible implementations, such as Figure 5 As shown, each driving unit 110 includes an inductor L, a first half-bridge 111 and a second half-bridge 112 that forms an H bridge with the first half-bridge 111; the upper bridge arm of the first half-bridge 111 (i.e., the first upper bridge arm 1111) is connected to the positive terminal of the load 300, the lower bridge arm of the first half-bridge 111 (i.e., the first lower bridge arm 1112) and the lower bridge arm of the second half-bridge 112 (i.e., the second lower bridge arm 1122) are connected in parallel and are respectively connected to the negative terminal of the load 300 and the negative terminal of the battery 200, and the upper bridge arm of the second half-bridge 112 (i.e., the second upper bridge arm 1121) is connected to the positive terminal of the battery 200.

[0066] It should be noted that the present embodiment includes an H bridge, a charging sampling resistor R1 and a discharging sampling resistor R2, so bidirectional charging and discharging can be performed, that is, the battery 200 can be charged or discharged. When the working mode of the driving unit 110 is the charging boost mode or the discharging boost mode, the upper arm of the second half bridge 112 is always turned on, and the lower arm of the second half bridge 112 is always turned off (the structure of the driving unit 110 can be equivalent to Figure 3 If the working mode of the driving unit 110 is the discharge buck mode, the upper bridge arm of the first half bridge 111 is always turned on, and the lower bridge arm of the first half bridge 111 is always turned off (the driving unit 110 structure can be equivalent to Figure 4 10 structure of the driving unit 110 in FIG.

[0067] In the above embodiment, the power conversion circuit 100 includes a discharge sampling resistor R2 and / or a charge sampling resistor R1. When the power conversion circuit 100 includes a discharge sampling resistor R2, the discharge sampling resistor R2 is connected in series between the drive unit 110 and the load 300. When the power conversion circuit 100 includes a charge sampling resistor R1, the charge sampling resistor R1 is connected in series between the drive unit 110 and the battery 200.

[0068] In some feasible implementations, the power conversion circuit 100 includes two filter capacitors, which are respectively connected in parallel across the battery 200 and across the load 300 to filter the input or output voltage.

[0069] The structure of the power conversion circuit 100 has been described. Next, the control principle of the power conversion circuit 100 will be described. Figure 6 As shown, in the control method of the power conversion circuit 100, the control unit executes the following steps. According to different requirements, the order of the steps in the flowchart can be changed.

[0070] Step S210, obtaining the working mode of the power conversion circuit 100 and the state parameters corresponding to the current working mode, and sequentially turning on the target switch tube in each target half bridge and turning off the other switch tube in the target half bridge according to the preset phase difference and the state parameters.

[0071] In some feasible implementations, since a plurality of driving units 110 are included, after power-on, the target switch tubes in the target half bridge of each driving unit 110 can be turned on in sequence according to the preset phase difference. Each operating mode corresponds to a target half bridge and a target switch tube, and the target half bridge and the target switch tube can be determined according to the operating mode.

[0072] For example, Figure 3 In the driving unit 110 shown, if the current working mode is the charging buck mode or the discharging boost mode, the target half-bridge is the only first half-bridge 111. However, the target switch tube in the charging buck mode is the switch tube in the upper bridge arm of the first half-bridge 111, that is, in this working mode, the upper bridge arm of each first half-bridge 111 is turned on in sequence according to the preset phase difference and state parameters, and the lower bridge arm of each first half-bridge 111 is disconnected. The target switch tube in the discharging boost mode is the switch tube in the lower bridge arm of the first half-bridge 111, that is, in this working mode, the lower bridge arm of each first half-bridge 111 is turned on in sequence according to the preset phase difference and state parameters, and the upper bridge arm of each first half-bridge 111 is disconnected.

[0073] For example, Figure 4For the driving unit 110 shown, if the current working mode is the discharge buck mode, the target half bridge is the only first half bridge 111, and the target switch tube is the upper bridge arm of the first half bridge 111, that is, in this working mode, the upper bridge arm of each first half bridge 111 is turned on in sequence with a pulse width according to the preset phase difference and state parameters, and the lower bridge arm of each first half bridge 111 is disconnected.

[0074] For example, Figure 5 For the drive unit 110 shown, if the current working mode is the charging buck mode, the target half bridge is the first half bridge 111, and the target switch is the switch in the upper arm of the first half bridge 111. If the current working mode is the discharging boost mode, the target half bridge is the first half bridge 111, and the target switch is the switch in the lower arm of the first half bridge 111. If the current working mode is the discharging buck mode, the target half bridge is the second half bridge 112, and the target switch is the switch in the upper arm of the second half bridge 112. For specific control methods, please refer to Figure 3 to Figure 4 The control method of the drive unit 110 in will not be repeated here.

[0075] Optionally, the preset phase difference is determined according to a switching period of the target switch tube and the total number of the driving units 110 .

[0076] For example, Figure 7 As shown, for easy distinction, each inductor L is marked as L 1 , L 2 ,…,L n If the total number of drive units 110 is 6, the preset phase difference is 360 / N=60 degrees. That is, in each switching cycle, the first drive unit 110 is pulse-connected at the 0-degree phase moment, the second drive unit 110 is pulse-connected at the 60-degree phase moment, ..., the sixth drive unit 110 is pulse-connected at the 300-degree phase moment, and the cycle is repeated in sequence according to this rule.

[0077] Step S220: determine the inductor target current value according to the state parameter.

[0078] Step S230 , obtaining the dual current sampling value of the sampling resistor corresponding to the current working mode, and controlling each driving unit 110 according to the dual current sampling value and the inductor target current value, so that the battery 200 is charged or discharged.

[0079] In the actual operation process of the target switch tube with pulse width, when the target switch tube changes from the on state to the off state, the energy stored in the inductor L will be carried out in the form of current through the parasitic diode in another switch tube in the target half-bridge, resulting in a large energy loss. Figure 3For example, when the target switch tube of the upper half bridge is closed, the inductor L is charged. When the target switch tube is disconnected, the inductor L will not change suddenly immediately but will continue to flow to the switch tube in the lower half bridge, thereby causing power loss. The power consumption is the product of the voltage drop U of the switch tube in the lower half bridge and the current I passing through. If the current pulse width conduction of a single target switch tube is switched to complementary conduction of two switch tubes at this time, the current released by the inductor L will flow through another complementary conduction switch tube instead of flowing through the parasitic diode, thereby reducing power loss. Furthermore, if the current released by the inductor L continues to flow from the parasitic diode of another disconnected switch tube, and the voltage drop of the parasitic diode is 0.7v, the continuous flow current is I 1 , the power loss is 0.7I 1 If the current generated by the inductor L flows through the complementary conducting switch tube, since the resistance R of the switch tube is only a few milliohms, if the current flowing through the switch tube is I 2 , then the power consumption is Obviously, when complementary conduction occurs, the power loss will be very small.

[0080] It should be noted that the charging and discharging process of the inductor L is relatively complicated. In each switching cycle, in the first part of the switching cycle, when the target switch is turned on, the inductor current will continue to rise, and in the second part of the switching cycle, the inductor current will continue to decrease. The current of the inductor L will change in real time. When the current of the inductor L is too small, turning on another switch tube for complementary conduction will cause the current to flow back. Figure 3 For example, if the target switch tube is turned off and the other switch tube is turned on in a complementary manner, and the current of the inductor L is too small at this time, the current of the battery 200 will flow back to the inductor L to charge the inductor L, which will not only fail to achieve the purpose of charging the battery 200, but also make the battery 200 have a lower power. Therefore, the complementary conduction of the two switch tubes cannot be turned on immediately when the target switch tube is turned off. The complementary conduction of the two switch tubes can only be turned on when the current of the main circuit (that is, the sum of the currents of multiple inductors in parallel) reaches a certain value (that is, the target current value of the inductor). Therefore, the target current value of the inductor needs to be determined first.

[0081] Furthermore, in each switching cycle, the current of the inductor L will rise first and then fall. If the current rising or falling stage is selected for sampling to obtain the current sampling value, and the current sampling value meets the inductor target current value condition, the inductor L is in a discontinuous state at this time, and there may be a risk of current backflow, and the more inductors L are currently connected in parallel, the greater the risk of current backflow. Therefore, in order to ensure that the current cannot flow back, sampling cannot be selected at any stage of current rising or current falling to obtain the sampling value, but sampling is performed at the same time in the inductor current rising stage and the inductor current falling stage to obtain a double current sampling value. Only when the double current sampling values ​​obtained by sampling in the inductor current rising stage and the inductor current falling stage both meet the inductor target current value condition, there will be no risk of current backflow when complementary conduction is performed.

[0082] So far, we have analyzed why it is necessary to determine the target inductor current value and select the dual current sampling value. Next, we will explain the conditions for the dual current sampling value to meet the target inductor current value.

[0083] In some feasible implementations, controlling each driving unit 110 according to the dual current sampling value and the inductor target current value includes:

[0084] When the dual current sampling values ​​are both greater than the target inductor current value, the two switch tubes in the corresponding target half-bridge are controlled to be complementary turned on in the next switching cycle of each target switch tube.

[0085] When complementary conduction occurs, if any current sampling value in the dual current sampling values ​​is less than the target inductor current value, the target switch tube pulse width in the corresponding target half bridge is controlled to be turned on and the other switch tube is turned off in the next switching cycle of each target switch tube.

[0086] It is understandable that, since the driving unit 110 is pulse-width turned on at the beginning of each power-on, the two switch tubes in the target half-bridge will be turned on in a complementary conduction state only when the above conditions are met. When the complementary conduction is on, if the above conditions are not met, the complementary conduction state needs to be turned off to prevent the backflow phenomenon from occurring.

[0087] It is understandable that complementary conduction means that when the target switch tube is turned on, the other switch tube is turned off; when the target switch tube is turned off, the other switch tube is turned on. Therefore, the pulse width conduction state of the target switch tube does not need to be turned off, and it is only necessary to turn on or off the complementary conduction state of the other switch tube. In addition, even if it is determined that the complementary conduction state needs to be turned on at the current moment, there is no need to immediately perform complementary conduction on the other switch. This is because the duty cycle of the target switch tube may be different in each cycle. If the complementary conduction is turned on or off, the duty cycle also needs to be adjusted. Therefore, in order to reduce the error, complementary conduction is required in the next switching cycle.

[0088] In some feasible implementations, the state parameters include the duty cycle and switching period of each target switch tube, the voltage across the battery 200 and the voltage across the load 300. Step S220 includes:

[0089] The target current value of the inductor is determined according to the duty cycle, the switching period, the voltage across the battery 200 and the voltage across the load 300 .

[0090] In some feasible implementations, the periodic variation value of the inductor current in each switching cycle may be determined based on the duty cycle, the switching cycle, the voltage across the battery 200, and the voltage across the load 300. The periodic variation value of the inductor current is the current variation value of the inductor L in each switching cycle. Then, the target inductor current value is determined based on the periodic variation value of the inductor current.

[0091] Taking the driving unit 110 in the charging and voltage reduction state as an example, according to the circuit characteristics, the following formula can be obtained:

[0092] L L *D i / T / D=V p -V b ;

[0093] V b =D*V p ;

[0094] Among them, L L represents the inductance of the inductor L; T represents the switching period; D i represents the periodic variation of the inductor current; D represents the duty cycle of the target switch; V p Indicates the voltage across the load 300; V b Indicates the voltage across the battery 200.

[0095] According to the above two formulas, the calculation formula of the periodic change value of the inductor current can be obtained:

[0096] D i =T*V b *(V p -V b ) / V p / L L .

[0097] According to the change principle of inductor current: in one switching cycle, the rising value of current is equal to the falling value of current. Figure 7 According to the above formula, the calculation formula of the inductor target current value in the power conversion circuit of the six drive units 110 is:

[0098] I t1 =I t2=(1 / 6+1 / 6+3 / 6+3 / 6+5 / 6+5 / 6)*Di=(1 / 6+2 / 6+3 / 6+4 / 6+5 / 6+1 / 2)*Di;

[0099] Among them, I t1 Indicates that at the first sampling time T 1 The first current sampling value obtained by downsampling, I t2 Indicates that at the second sampling time T 2 The second current sampling value is obtained by downsampling.

[0100] Similarly, the calculation formula for the target inductor current value in the power conversion circuit 100 of the N drive units 110 can be derived as follows:

[0101] I t1 =I t2 =(1 / N+2 / N+3 / N+……+(N-2) / N+(N-1) / N+1 / 2)*Di.

[0102] Similarly, when the driving unit 110 is in the discharge boost mode or the discharge buck mode, the above reasoning process can be referred to, and the calculation formula for the double current sampling value in the power conversion circuit 100 of the N driving units 110 can be obtained as follows:

[0103] I t1 =I t2 =(1 / N+2 / N+3 / N+……+(N-2) / N+(N-1) / N+1 / 2)*Di.

[0104] It is understandable that when the inductor L is in a critical state, the first current sampling value and the second current sampling value are equal, and when both current sampling values ​​in the real-time dual current sampling values ​​are greater than the current sampling value in the critical state, it is determined that the inductor L is in a continuous state. Therefore, the first current sampling value or the second current sampling value when the inductor L is in a critical state is used as the inductor target current value, as a basis for determining complementary conduction.

[0105] In some feasible implementations, the dual current sampling value includes a first current sampling value and a second current sampling value;

[0106] The sampling time of the first current sampling value is the midpoint of the current rise time in each switching cycle of the reference switch tube, and the sampling time of the second current sampling value is the midpoint of the current fall time in each switching cycle of the reference switch tube. The reference switch tube is one of all the target switch tubes.

[0107] Figure 7The current-time triangle wave diagram of each inductor L in the critical mode is shown. In the critical mode, the rise time and fall time of the inductor L are equal. Considering that the switching cycle is very short, for example, 50 microseconds, the rise time and fall time of the inductor L are both 25 microseconds. The sampling durations of the first sampling time period (the rise time period of the inductor L) and the second sampling time period (the fall time period of the inductor L) are both short. In each sampling time period, if a sampling moment that is too early is selected, the sampling error will be large because the current has not stabilized yet; if a sampling moment that is too late is selected, the sampling window will be too small, and the next sampling time period may arrive before the current is sampled. Therefore, optionally, each sampling moment is positioned at the midpoint of the corresponding sampling time period. Taking the critical mode as an example, the first sampling moment T 1 The second sampling time T is T / 4 in each switching cycle T. 1 The reference switch is one of all target switches and can be set according to the specific usage. There is no restriction here. Each sampling cycle is the switching cycle of the reference switch. Figure 7 The reference switch tube in is the first switch tube L1.

[0108] It should be noted that the dual current sampling values ​​here are real-time sampled data, and the inductor L is not necessarily in a critical state. Therefore, the first current sampling value and the second current sampling value may not be equal. When the inductor L is in a current discontinuous state, the first current sampling value and the second current sampling value are not equal. When the inductor L is in a current critical state and a current continuous state, the first current sampling value and the second current sampling value are equal. Therefore, it is necessary to use real-time dual current sampling values ​​to judge the state of the inductor L, and then judge whether the target half-bridge needs to be complementary turned on.

[0109] The present application proposes a power conversion circuit 100, including a control unit, at least one sampling resistor and a plurality of parallel drive units 110, each drive unit 110 includes at least an inductor L and a first half bridge 111 formed by two switch tubes connected in series; the control unit is used to obtain the working mode of the power conversion circuit 100 and the state parameters corresponding to the current working mode, and determine the target current value of the inductor according to the state parameters; the control unit is also used to obtain the double current sampling value of the sampling resistor corresponding to the current working mode, and control each drive unit 110 according to the double current sampling value and the target current value of the inductor, so that the battery 200 is charged or discharged. The present application achieves the purpose of reducing the volume of the switch tube and the inductor L by staggered parallel connection of multiple small-volume drive units 110, which can not only provide power density, but also can be integrated into a PCB (Printed Circuit Board) board. At the same time, the drive unit 110 is also controlled by the double sampling value and the target current value of the inductor to reduce energy loss and improve energy conversion efficiency.

[0110] Furthermore, the present application can minimize the number of switches while minimizing energy loss, thereby reducing switching losses.

[0111] The present application also proposes an energy storage device, including the above-mentioned power conversion circuit 100, wherein the power conversion circuit 100 includes a control unit, and the control unit is used to execute the control method of the above-mentioned power conversion circuit 100.

[0112] It can be understood that the device of this embodiment corresponds to the control method of the power conversion circuit 100 of the above embodiment, and the options in the above embodiment are also applicable to this embodiment, so they will not be described repeatedly here.

[0113] Wherein, the control unit includes a processor and a memory, and the processor can be an integrated circuit chip with signal processing capability. The processor can be a general-purpose processor, including a central processing unit (CPU), a graphics processing unit (GPU), a network processor (NP), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or at least one of other programmable logic devices, discrete gates or transistor logic devices, and discrete hardware components. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor, etc., which can implement or execute the disclosed methods, steps and logic block diagrams in the embodiments of the present application.

[0114] The memory may be, but is not limited to, a random access memory (RAM), a read only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), etc. The memory is used to store a computer program, and the processor may execute the computer program accordingly after receiving an execution instruction.

[0115] The present application also provides a computer-readable storage medium for storing the computer program used in the above energy storage device. For example, the computer-readable storage medium may include, but is not limited to, various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0116] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely schematic. For example, the flowcharts and structure diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of a code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in an alternative implementation, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the structure diagram and / or the flow diagram, and the combination of boxes in the structure diagram and / or the flow diagram, can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0117] In addition, the functional modules or units in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0118] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a smart phone, a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in the various embodiments of the present application.

[0119] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be covered by the protection scope of the present application.

Claims

1. A power conversion circuit, characterized in that: The power conversion circuit is arranged between the battery and the load, and includes a control unit, at least one sampling resistor and a plurality of parallel driving units, each of which includes at least one inductor and a first half bridge formed by two switch tubes connected in series; The control unit is used to obtain the working mode of the power conversion circuit and the state parameters corresponding to the current working mode, and determine the inductor target current value according to the state parameters; The control unit is further used to obtain the dual current sampling value of the sampling resistor corresponding to the current working mode, and control each driving unit according to the dual current sampling value and the inductor target current value to charge or discharge the battery.

2. The power conversion circuit according to claim 1, characterized in that: The first end of each of the drive units is connected in parallel to connect to the positive end of the load; the second end of each of the drive units is connected in parallel to connect to the negative end of the battery and the negative end of the load respectively; the third end of each of the drive units is connected in parallel to connect to the positive end of the battery.

3. The power conversion circuit according to claim 2, characterized in that: The upper bridge arm of the first half bridge is connected to the positive terminal of the load, the lower bridge arm of the first half bridge is respectively connected to the negative terminal of the load and the negative terminal of the battery, and the middle point of the first half bridge is connected to the positive terminal of the battery through the inductor.

4. The power conversion circuit according to claim 2, characterized in that: The upper bridge arm of the first half bridge is connected to the positive terminal of the battery, the lower bridge arm of the first half bridge is respectively connected to the negative terminal of the load and the negative terminal of the battery, and the middle point of the first half bridge is connected to the positive terminal of the load through the inductor.

5. The power conversion circuit according to claim 2, characterized in that: Each of the driving units includes the inductor, the first half-bridge and the second half-bridge forming an H-bridge with the first half-bridge; the upper bridge arm of the first half-bridge is connected to the positive terminal of the load, the lower bridge arm of the first half-bridge is connected in parallel with the lower bridge arm of the second half-bridge and is respectively connected to the negative terminal of the load and the negative terminal of the battery, and the upper bridge arm of the second half-bridge is connected to the positive terminal of the battery.

6. The power conversion circuit according to claim 1, characterized in that: The power conversion circuit includes a discharge sampling resistor and / or a charge sampling resistor; The discharge sampling resistor is connected in series between the driving unit and the load; The charging sampling resistor is connected in series between the driving unit and the battery.

7. The power conversion circuit according to claim 6, characterized in that: The types of working modes include charging boost mode, discharging boost mode and discharging buck mode; In the charging boost mode, the power conversion circuit includes the charging sampling resistor, or the charging sampling resistor and the discharging sampling resistor; In the discharge boost mode or the discharge buck mode, the power conversion circuit includes a discharge sampling resistor, or a discharge sampling resistor and a charge sampling resistor.

8. A control method for a power conversion circuit, characterized in that: Applicable to the power conversion circuit of claim 1; the control unit performs the following steps, including: Obtaining the working mode of the power conversion circuit and the state parameters corresponding to the current working mode, and sequentially turning on the target switch tube in each target half-bridge and turning off another switch tube in the target half-bridge according to the preset phase difference and the state parameters, wherein the target half-bridge is the half-bridge in the driving unit; Determining an inductor target current value according to the state parameter; A dual current sampling value of the sampling resistor corresponding to the current working mode is obtained, and each driving unit is controlled according to the dual current sampling value and the inductor target current value, so that the battery is charged or discharged.

9. The control method of the power conversion circuit according to claim 8, characterized in that: The controlling each driving unit according to the double current sampling value and the inductor target current value comprises: When the double current sampling values ​​are both greater than the inductor target current value, two switch tubes in the corresponding target half-bridge are controlled to be complementary turned on in the next switching cycle of each target switch tube; When complementary conduction occurs, if any current sampling value of the dual current sampling values ​​is less than the target inductor current value, the target switch tube pulse width in the corresponding target half bridge is controlled to be turned on and the other switch tube is turned off in the next switching cycle of each target switch tube.

10. The control method of the power conversion circuit according to claim 8, characterized in that: The state parameters include the duty cycle and switching period of each target switch tube, the voltage across the battery and the voltage across the load; The step of determining the target inductor current value according to the state parameter comprises: The inductor target current value is determined according to the duty cycle, the switching period, the voltage across the battery, and the voltage across the load.

11. The control method of the power conversion circuit according to claim 8, characterized in that: The dual current sampling value includes a first current sampling value and a second current sampling value; The sampling time of the first current sampling value is the midpoint of the current rise time in each switching cycle of the reference switch tube, and the sampling time of the second current sampling value is the midpoint of the current fall time in each switching cycle of the reference switch tube. The reference switch tube is one of all the target switch tubes.

12. The control method of the power conversion circuit according to claim 8, characterized in that: The preset phase difference is determined according to the switching period of the target switch tube and the total number of the driving units.

13. An energy storage device, characterized in that: The power conversion circuit comprises the power conversion circuit as described in any one of claims 1 to 7, wherein the power conversion circuit comprises a control unit, and the control unit is used to execute the control method of the power conversion circuit as described in any one of claims 8 to 12.

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