Energy recovery protection circuit, BMS protection board and energy storage device

Abstract

The invention relates to the technical field of battery energy storage, and discloses an energy recovery protection circuit, a BMS protection board and an energy storage device.The energy recovery protection circuit is arranged between a battery and an output end and comprises an absorption unit located between a positive electrode and a negative electrode of the output end, and the absorption unit comprises an absorption capacitor and a follow current device which are arranged in series; the voltage conversion unit is connected with the absorption unit and an output capacitor between the positive electrode and the negative electrode of the battery. The absorption unit is used for enabling the loop current to flow through the conducted follow current device and then charge the absorption capacitor when the positive electrode and the negative electrode of the output end are communicated to generate the loop current; and the voltage conversion unit is used for entering a working state when the absorption capacitor is charged to exceed the starting voltage of the voltage conversion unit so as to charge the battery after voltage conversion is carried out on the output voltage of the absorption capacitor. The circuit realizes energy recovery when the output end of the external load is short-circuited, and can also prevent the two ends of the discharge switch from being damaged due to overhigh peak voltage generated at the two ends of the discharge switch.

Description

Technical Field

[0001] The present application relates to the field of battery energy storage technology, and in particular to an energy recovery protection circuit, a BMS protection board and an energy storage device. Background Art

[0002] When the existing energy storage battery pack is used to connect an external load at the output end, it is easy for manual operation errors or other factors to cause the output ends used to connect the load to be short-circuited through wires, that is, the positive and negative poles of the output end are connected, and a large current will be generated between the positive and negative poles of the output end. Since most of the current battery pack energy storage products use the AFE to control the charge and discharge management of the negative pole of the battery pack, the AFE (analog front end) circuit is first used to control the disconnection of the discharge switch tube (such as MOS tube) at the negative pole of the battery pack to achieve protection. However, since the connecting wire between the output ends has an inductive characteristic, a very high reverse voltage spike will be generated at both ends after the discharge switch tube is turned off, which is easy to damage the discharge switch tube. Summary of the invention

[0003] In view of this, the present application proposes an energy recovery protection circuit, a BMS protection board and an energy storage device, which realize the energy recovery function when the output end of the external load is short-circuited, and also protect the discharge switch tube used to control the output.

[0004] In a first aspect, an embodiment of the present application provides an energy recovery protection circuit, which is arranged between a battery and an output terminal, wherein the positive electrode and the negative electrode of the battery are respectively connected to the positive electrode and the negative electrode of the output terminal; a discharge switch tube is also arranged between the negative electrode of the battery and the negative electrode of the output terminal; the energy recovery protection circuit comprises:

[0005] An absorption unit, the absorption unit is located between the positive electrode and the negative electrode of the output end, and the absorption unit includes an absorption capacitor and a freewheeling device arranged in series;

[0006] A voltage conversion unit, the voltage conversion unit is connected to the absorption unit, and the voltage conversion unit is also connected to an output capacitor located between the positive electrode and the negative electrode of the battery;

[0007] The absorption unit is used for charging the absorption capacitor after the loop current flows through the turned-on freewheeling device when the positive and negative electrodes of the output end are connected to generate a loop current and the discharge switch tube is turned off;

[0008] The voltage conversion unit is used to enter a working state when the absorption capacitor is charged to a voltage exceeding the starting voltage of the voltage conversion unit, so as to charge the battery after performing voltage conversion on the output voltage of the absorption capacitor.

[0009] In some embodiments, the absorption unit further includes an absorption resistor and a clamping diode arranged in parallel with the absorption capacitor.

[0010] In some embodiments, the freewheeling device is a diode or a MOS tube.

[0011] In some embodiments, when the freewheeling device is a MOS tube, the control end of the MOS tube is used to connect to the front-end analog circuit;

[0012] The energy recovery protection circuit further includes a current detection unit, and the current detection unit is used to detect the loop current flowing through the MOS tube;

[0013] The MOS tube is used to be in an on state when the discharge switch tube is turned off and the loop current exists; and to be in an off state when the loop current does not exist.

[0014] In some embodiments, the voltage conversion unit is a reverse DC buck unit, which includes a first power control chip, a first switch tube and an energy storage freewheeling branch, the energy storage freewheeling branch is connected in parallel with the output capacitor, and the first switch tube is respectively connected to the positive electrode of the absorption capacitor and the energy storage freewheeling branch;

[0015] The power supply end and the ground end of the first power control chip are respectively connected to the positive electrode of the absorption capacitor and the positive electrode of the output end. After entering the working state, the first power control chip is used to control the on and off of the first switch tube to utilize the energy storage freewheeling branch to step down the output voltage of the absorption capacitor and then input it into the battery.

[0016] In some embodiments, the reverse DC buck unit further includes a driving subunit, and the driving subunit is respectively connected to the signal control terminal of the first power control chip and the control terminal of the first switch tube;

[0017] The first power control chip is used to output a pulse modulation signal to the driving sub-unit after entering a working state, so as to control the driving sub-unit to be turned on or off, thereby turning the first switch tube on or off accordingly.

[0018] In some embodiments, the energy storage freewheeling branch includes a first inductor and a first freewheeling diode connected in series;

[0019] One end of the first inductor is connected to the positive electrode of the output capacitor, the other end of the first inductor is connected to the cathode of the first freewheeling diode, and the anode of the first freewheeling diode is connected to the negative electrode of the output capacitor.

[0020] In some embodiments, the reverse DC buck unit further includes a current sampling subunit, the current sampling subunit is connected to the first inductor, and the current sampling subunit is also connected to the signal feedback terminal of the first power control chip;

[0021] The first power control chip is further used to adjust the duty cycle of a control signal for controlling the first switch tube according to the loop current flowing through the first inductor collected by the current sampling subunit, using the loop current.

[0022] In some embodiments, the current sampling subunit includes a sampling resistor, the sampling resistor is connected in series between the positive electrode of the output capacitor and the first inductor, and the series node of the sampling resistor and the first inductor is connected to the signal feedback end of the first power control chip.

[0023] In some embodiments, the voltage conversion unit is a BUCK buck unit, which includes a second power control chip, a second switch tube, a second inductor, and a second freewheeling diode, wherein the first end of the second switch tube is connected to the positive electrode of the absorption capacitor, the second end of the second switch tube is connected to the second inductor, the anode of the second freewheeling diode is connected to the negative electrode of the output capacitor, and the cathode is connected to the series node of the second end of the second switch tube and the second inductor;

[0024] The power supply end and the ground end of the second power supply control chip are respectively connected to the positive electrode of the absorption capacitor and the negative electrode of the output end. After entering the working state, the second power supply control chip is used to control the on and off of the second switch tube to use the second inductor and the second freewheeling diode to step down the output voltage of the absorption capacitor and input it into the battery.

[0025] In a second aspect, an embodiment of the present application further provides a BMS protection board, including an output terminal, an output capacitor, a charge and discharge switch group, and the energy recovery protection circuit;

[0026] The two ends of the output capacitor are used to respectively connect to the positive electrode and the negative electrode of the battery;

[0027] The positive electrode and the negative electrode of the output terminal are used to connect the positive electrode and the negative electrode of the battery respectively;

[0028] The charge and discharge switch group is arranged in series between the negative electrode of the battery and the negative electrode of the output end; wherein the charge and discharge switch group comprises a charge switch tube and a discharge switch tube arranged in series;

[0029] The energy recovery protection circuit is arranged between the battery and the output end;

[0030] The BMS protection board is used to control the discharge switch tube to turn off when the positive and negative electrodes of the output end are connected to generate a loop current, so that the loop current is recovered to the battery through the energy recovery protection circuit.

[0031] In a third aspect, an embodiment of the present application provides an energy storage device, including the energy recovery protection circuit or the BMS protection board.

[0032] The embodiments of the present application have the following beneficial effects:

[0033] The energy recovery protection circuit provided by the embodiment of the present application includes an absorption unit and a voltage conversion unit, wherein the absorption unit is located between the positive and negative electrodes of the output terminal and includes an absorption capacitor and a freewheeling device arranged in series; the voltage conversion unit is respectively connected to the absorption unit and the output capacitor between the positive and negative electrodes of the battery; the absorption unit is used to charge the absorption capacitor after the loop current flows through the conducting freewheeling device when the positive and negative electrodes of the output terminal are connected to generate a loop current; the voltage conversion unit is used to enter a working state when the absorption capacitor is charged to a voltage exceeding the starting voltage of the voltage conversion unit, so as to charge the battery after performing voltage conversion on the output voltage of the absorption capacitor. The energy recovery protection circuit realizes energy recovery of the generated loop current when the output terminal for connecting an external load is short-circuited, and also solves the problem that the discharge switch tube is easily damaged by high-voltage spike voltage when performing circuit-breaking protection in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope of protection of the present invention. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative work.

[0035] Figure 1 A first circuit schematic diagram of an energy recovery protection circuit according to an embodiment of the present application is shown;

[0036] Figure 2 A schematic diagram showing a structure in which the freewheeling device of an embodiment of the present application is a diode;

[0037] Figure 3 A schematic diagram showing a structure in which the freewheeling device of an embodiment of the present application is a MOS tube;

[0038] Figure 4 A schematic diagram of the structure of a reverse DC buck unit in an embodiment of the present application is shown;

[0039] Figure 5A circuit diagram of a reverse DC buck unit according to an embodiment of the present application is shown;

[0040] Figure 6 A schematic diagram of the structure of a BUCK step-down unit in an embodiment of the present application is shown;

[0041] Figure 7 A structural schematic diagram of a BMS protection board according to an embodiment of the present application is shown.

[0042] Description of main component symbols:

[0043] 10-energy recovery protection circuit; 101-absorption unit; 102-voltage conversion unit; C0-output capacitor; C1-absorption capacitor; T1-freewheeling device; R0-absorption resistor; D0-clamping diode; 103-current detection unit; 102a-reverse DC buck unit; U1-first power supply control chip; 1021-energy storage freewheeling branch; 1022-driving subunit; 1023-current sampling subunit; Q1-first switch tube; L1-first inductor; D1-first freewheeling diode; Rf-sampling resistor; 102b-BUCK buck unit; U2-second power supply control chip; Q2-second switch tube; L2-second inductor; D2-second freewheeling diode; 20-BMS protection board; 201-charge and discharge switch group. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0045] The components of the embodiments of the present invention generally described and shown in the drawings herein may be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0046] Hereinafter, the terms "including", "having" and their cognates, which may be used in various embodiments of the present invention, are intended only to indicate specific features, numbers, steps, operations, elements, components or combinations 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 combinations of the foregoing items or adding the possibility of one or more features, numbers, steps, operations, elements, components or combinations of the foregoing items.

[0047] Furthermore, the terms “first”, “second”, “third”, etc. are merely used for distinguishing descriptions and are not to be understood as indicating or implying relative importance.

[0048] 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 invention 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 invention.

[0049] When the output end of the existing energy storage battery pack is used for an external load, if the positive and negative electrodes of the output end are connected, the discharge switch tube is easily damaged. Although the existing solution has adopted a transient voltage suppression diode (TVS tube) connected in parallel at both ends of the discharge switch tube to absorb the reverse spike voltage at both ends of the discharge switch tube, both the discharge switch tube and the TVS tube need to have a large voltage stress requirement, and the spike voltage can only be absorbed as useless energy.

[0050] Based on this, the inventor proposed the idea of ​​"it is better to unblock than to block", and proposed a method of adding an energy recovery protection circuit 10 at the output end. On the one hand, it can reduce the stress requirement of the terminal voltage of the discharge switch tube and play a protective role; on the other hand, by absorbing and storing the generated reverse peak high voltage and converting the voltage for battery charging, it realizes the design of "turning waste into treasure" and increases energy utilization.

[0051] It can be understood that the energy recovery protection circuit 10 of the embodiment of the present application is arranged between the battery and the output end. In order to facilitate the subsequent description, the structure between the battery and the output end is first explained here.

[0052] It should be understood that the battery described in the embodiments of the present application can be a single battery pack, a plurality of battery packs connected in series and / or in parallel, or a battery module, etc., which is not limited here. The above-mentioned output terminal can be used to connect various external loads, which is not limited here, so it is sometimes also called load terminal or load output terminal.

[0053] Among them, the battery includes a positive electrode B+ of the battery and a negative electrode B- of the battery, and the output end includes a positive electrode P+ of the output end and a negative electrode P- of the output end. The positive electrode B+ and the negative electrode B- of the battery are respectively connected to the positive electrode P+ and the negative electrode P- of the output end, that is, the positive electrode B+ of the battery is connected to the positive electrode P+ of the output end, and the negative electrode B- of the battery is connected to the negative electrode P- of the output end. It can be understood that the energy recovery protection circuit 10 of the present application is mainly based on the application scenario of the common positive electrode, that is, the positive electrode B+ of the battery is directly connected to the positive electrode P+ of the output end; accordingly, the above-mentioned charging switch tube and the discharge switch tube are located between the negative electrode B- of the battery and the negative electrode P- of the output end. It can be understood that for all energy storage products with a common negative electrode, the energy recovery protection circuit 10 of the present application can be added to the structure of the existing BMS protection board with as little modification as possible.

[0054] The energy recovery protection circuit 10 is described below in conjunction with some specific embodiments.

[0055] Figure 1 The figure shows a schematic diagram of the structure of the energy recovery protection circuit 10 of the embodiment of the present application. Exemplarily, the energy recovery protection circuit 10 includes an absorption unit 101 and a voltage conversion unit 102, wherein the absorption unit 101 is located between the positive electrode P+ and the negative electrode P- of the output end; the voltage conversion unit 102 is connected to the absorption unit 101, and the voltage conversion unit 102 is also connected to the output capacitor C0 located between the positive electrode B+ and the negative electrode B- of the battery.

[0056] In this embodiment, the absorption unit 101 includes an absorption capacitor C1 and a freewheeling device T1 arranged in series. The absorption unit 101 is used to charge the absorption capacitor C1 after the loop current flows through the conducting freewheeling device T1 when the positive electrode P+ and the negative electrode P- of the output end are connected to generate a loop current and the discharge switch tube is turned off. For example, the output end can be short-circuited by a wire, and the wire has an inductance characteristic at both ends. Furthermore, the voltage conversion unit 102 is used to enter a working state when the absorption capacitor C1 is charged to a voltage exceeding the starting voltage of the voltage conversion unit 102, so as to convert the output voltage of the absorption capacitor C1 into a voltage and then charge the battery.

[0057] Among them, the above-mentioned freewheeling device T1 mainly plays a freewheeling role. It can be understood that when it is detected that the positive electrode P+ and the negative electrode of the output end are connected, usually, the AFE on the BMS protection board will first control the discharge switch tube to disconnect. Since the generated loop current cannot change suddenly, the output end will generate a reverse voltage at both ends of the discharge switch tube to maintain the current to run in the original direction. Therefore, the reverse voltage will flow to the absorption capacitor C1 through the freewheeling device T1 in the absorption unit 101 for energy storage, and the absorption capacitor C1 is also charged at this time. For example, the freewheeling device T1 can be a diode, or it can be a MOS tube, etc., which is not limited here. Among them, when a MOS tube is used, when the MOS tube is turned on, due to the small internal resistance, the overcurrent capacity of the circuit will be stronger at this time.

[0058] like Figure 2 As shown, in one embodiment, if a diode is used, the anode of the diode is connected to the negative electrode P- of the output terminal, and the cathode of the diode is connected to the positive electrode of the absorption capacitor C1. It can be understood that the diode does not have a controllable end. When the voltage input to the diode is greater than its conduction voltage, the diode will be in a conducting state, that is, when the reverse voltage at both ends of the discharge switch tube is greater than the conduction voltage of the diode, it will flow through the diode to charge the absorption capacitor C1 set in series.

[0059] like Figure 3 As shown, in another embodiment, if a MOS tube is used, the first end of the MOS tube is used to connect the positive electrode of the absorption capacitor C1, and the second end is used to connect the negative electrode P- of the output end. Since the MOS tube is a controllable switching device, the control end of the MOS tube is also used to connect the AFE circuit in the BMS protection board. Among them, AFE is one of the core components in the BMS (power management system) protection board, which is mainly used to collect information such as battery cell voltage and temperature, and can also be used to control the charging switch tube and the discharging switch tube. Of course, in some other embodiments, the control end of the MOS tube can also be connected to other control units, which is not limited here.

[0060] It can be understood that when the discharge switch tube is turned off, the AFE can control the MOS tube to be in the on state. It is worth noting that when the battery output is normal, the MOS tube as the freewheeling device T1 can only be in the off state, so it needs to be turned off in time after controlling it to be turned on, otherwise it will cause damage to the external load or cause problems such as failure to work.

[0061] In the case of using a MOS tube, the energy recovery protection circuit 10 also includes a current detection unit 103, which is used to detect the loop current flowing through the MOS tube in real time. Exemplarily, when the current detection unit 103 detects that the loop current flowing through the MOS tube still exists, the MOS tube is maintained in the on state, and the discharge switch tube is in the off state; conversely, when it is detected that the loop current does not exist, the MOS tube is controlled to switch to the off state immediately. For example, the current detection unit 103 can be implemented by a current sampling resistor or other structures, which is not limited here.

[0062] As an alternative, Figure 4 As shown, the absorption unit 101 includes, in addition to the absorption capacitor C1 and the freewheeling device T1 mentioned above, an absorption resistor R0 and a clamping diode D0 which are arranged in parallel with the absorption capacitor C1.

[0063] The absorption resistor R0 and the absorption capacitor C1 form a discharge loop for completely releasing the remaining electricity in the absorption capacitor C1 to avoid the residual electric energy in the absorption capacitor C1 affecting the normal operation of subsequent circuits.

[0064] The clamping diode D0 is used to clamp the voltage across the absorption capacitor C1 to a preset voltage value, wherein the preset voltage value can be set according to the nominal voltage or required voltage of the battery, etc., which is not limited here. For example, the clamping diode D0 can be a TVS tube, etc.

[0065] In this embodiment, the voltage conversion unit 102 is mainly used to convert the output voltage of the absorption capacitor C1 and input it into the battery to charge the battery. There are many ways to implement it, which are not limited here. It is worth noting that in order to reduce the setting of additional power supply units and reduce circuit complexity, the voltage conversion unit 102 will be used to make full use of the electrical energy in the absorption capacitor C1. Exemplarily, when the absorption capacitor C1 is charged to a voltage exceeding the starting voltage of the voltage conversion unit 102, the voltage conversion unit 102 enters the working state and starts voltage conversion.

[0066] The start-up voltage mainly refers to the voltage required for the corresponding chip or device in the voltage conversion unit 102 to enter a normal working state, such as 8V to 9V. It can be understood that the voltage conversion unit 102 is mainly used for step-down conversion. This is because the voltage at the battery end is fixed, such as 24V, 36V, 48V, etc., and the reverse voltage generated by the short circuit has a large range, such as sometimes exceeding 50V, etc., so it needs to be stepped down before it can be input into the battery.

[0067] In one implementation, the voltage conversion unit 102 is implemented using a reverse DC step-down unit 102a. Figure 4As shown, the reverse DC buck unit 102a includes a first power control chip U1, a first switch tube Q1 and an energy storage freewheeling branch 1021, wherein the energy storage freewheeling branch 1021 is connected in parallel with the output capacitor C0, and the first switch tube Q1 is respectively connected to the positive electrode of the absorption capacitor C1 and the energy storage freewheeling branch 1021; the power supply end (VCC) of the first power control chip U1 is connected to the positive electrode of the absorption capacitor C1, and the ground end (GND) of the first power control chip U1 is connected to the positive electrode P+ of the output end.

[0068] Optionally, a filter capacitor C2 may be provided between the power supply terminal (VCC) and the ground terminal (GND) to increase the stability of the chip power supply, etc.; and the ground terminal (GND) of the first power control chip U1 may be connected to the positive electrode P+ of the output terminal through a current limiting resistor R2 to increase the grounding reliability, etc. In addition, the signal control terminal (OP) of the first power control chip U1 is connected to the control terminal of the first switch tube Q1 (such as the gate of the MOS tube, etc.). It can be understood that the above description only reflects the connection relationship of several key pin terminals of the first power control chip U1. In actual application scenarios, the first power control chip U1 will also combine other peripheral devices according to the instructions for use of the chip to ensure the normal use of the chip, and no excessive description is given here.

[0069] Exemplarily, after the first power control chip U1 enters the working state, it controls the on-off of the first switch tube Q1 to use the energy storage freewheeling branch 1021 to step down the output voltage of the absorption capacitor C1 and input it to the battery. The first switch tube Q1 can be a MOS tube, for example.

[0070] It is worth noting that the power supply voltage of the reverse DC step-down unit 102a is derived from the positive electrode of the absorption capacitor C1 and the positive electrode P+ of the output end, and the input voltage is from the positive electrode to the negative electrode of the absorption capacitor C1 (also the positive electrode P+ of the output end), and the voltage output to the battery is from the positive electrode B+ to the negative electrode B- of the battery, where the positive electrode B+ of the battery and the positive electrode P+ of the output end are equipotential points, that is, the input is positive at the bottom and negative at the top, and the output is positive at the top and negative at the bottom, so it is called a reverse charging process.

[0071] It can be understood that the model of the first power control chip U1 is not limited here, as long as it can drive the above-mentioned first switch tube Q1 and adjust the output according to feedback. For example, some commonly used current-type power driver chips can be used to reduce costs. It should be understood that the connection between the signal control terminal (OP) of the first power control chip U1 and the control terminal of the second switch tube Q2 can be a direct connection or an indirect connection, which can be determined specifically according to the selected power control chip. Among them, for indirect connection, related units or devices for increasing driving force can usually be set between the two.

[0072] For example, in one embodiment, when a common current-type power driver chip is used, the reverse DC buck unit 102a further includes a driver unit 1022, wherein the driver unit 1022 is respectively connected to the signal control terminal (OP) of the first power control chip U1 and the control terminal of the first switch tube Q1. Exemplarily, after the first power control chip U1 enters the working state, it outputs a pulse width modulation signal to the driver unit 1022 to control the on or off of the driver unit 1022, thereby turning on or off the first switch tube Q1 accordingly.

[0073] like Figure 5 As shown, the driving subunit 1022 mainly includes a driving switch tube (such as a MOS tube). In one embodiment, for example, the control end of the driving switch tube is connected to the signal control end (OP) of the first power control chip U1, the first end of the driving switch tube is connected to the control end of the first switch tube Q1 through a current limiting resistor, and the second end is connected to the ground end (GND). Based on the above connection method, when the first power control chip U1 controls the driving switch tube to turn on, since the gate of the first switch tube Q1 is in a low level state, the first switch tube Q1 is turned on at this time; conversely, when the driving switch tube is turned off, the gate of the first switch tube Q1 is in a high level state, and the first switch tube Q1 is turned off at this time. It should be understood that the above circuit is only a feasible example and is not the only limitation. It can be adaptively adjusted in actual application.

[0074] In one embodiment, if Figure 5 As shown, the energy storage freewheeling branch 1021 includes a first inductor L1 and a first freewheeling diode D1 connected in series; one end of the first inductor L1 is connected to the positive electrode of the output capacitor C0, the other end of the first inductor L1 is connected to the cathode of the first freewheeling diode D1, and the anode of the first freewheeling diode D1 is connected to the negative electrode of the output capacitor C0.

[0075] Taking the above structure as an example, the main working process of the reverse DC buck unit 102a is as follows: the power supply terminal (VCC) of the first power control chip U1 takes power from the positive electrode of the absorption capacitor C1, and starts working when the absorption capacitor C1 is charged to a voltage exceeding the starting voltage of the voltage conversion unit 102; the signal control terminal (OP) of the first power control chip U1 is used to output a control signal to drive the first switch tube Q1 to turn on, so that the loop current flows from the positive electrode of the absorption capacitor C1 through the first switch tube Q1, and then through the first inductor L1 loop to the negative electrode of the absorption capacitor C1, that is, the first loop is formed; at this time, the current stores energy in the first inductor L1. Then, the signal control terminal (OP) of the first power control chip U1 drives the first switch tube Q1 to turn off, and the current on the first inductor L1 flows through the output capacitor C0 and the battery, and the first freewheeling diode D1 in sequence to form a second loop, and the battery is charged at this time.

[0076] As an optional solution, in order to realize closed-loop control, the reverse DC buck unit 102a further includes a current sampling subunit 1023, which is connected to the first inductor L1, and the current sampling subunit 1023 is also connected to the signal feedback terminal (FB) of the first power control chip U1. In this embodiment, the first power control chip U1 is also used to adjust the duty cycle of the control signal used to control the first switch tube Q1 according to the size of the loop current flowing through the first inductor L1 collected by the current sampling subunit 1023, so as to make the energy recovery protection circuit 10 automatically adjust the output, such as making the output current stable at the set value (i.e., in a constant current output state).

[0077] For example, in combination with the energy storage freewheeling branch 1021 of the above structure, Figure 5 As shown, the current sampling subunit 1023 may include a sampling resistor Rf arranged in series with the first inductor L1, for example, the sampling resistor Rf is connected in series between the positive electrode of the output capacitor C0 and the first inductor L1, or the sampling resistor Rf is located between the first inductor L1 and the first freewheeling diode D1; at the same time, the series node of the sampling resistor Rf and the first inductor L1 is also connected to the signal feedback terminal (FB) of the first power control chip U1. Optionally, the series node of the sampling resistor Rf and the first inductor L1 is connected to the signal feedback terminal (FB) through a voltage divider resistor. Therefore, the first power control chip U1 dynamically adjusts the duty cycle of the control signal used to control the first switch tube Q1 through the size of the loop current collected by the sampling resistor Rf.

[0078] For example, when the loop current is sampled to be larger, the duty cycle of the PWM signal can be reduced to narrow the waveform of the drive signal of the first switch tube Q1, thereby reducing the output current. Alternatively, when the loop current is sampled to be smaller, the duty cycle of the PWM signal can be increased to widen the waveform of the drive signal of the first switch tube Q1, thereby increasing the output current, etc.

[0079] In another implementation, the voltage conversion unit 102 may also be implemented using a BUCK step-down unit 102b. Figure 6 As shown, the BUCK buck unit 102b includes a second power control chip U2, a second switch tube Q2, a second inductor L2 and a second freewheeling diode D2; wherein the second switch tube Q2, the second inductor L2 and the second freewheeling diode D2 are used to constitute the main components of the BUCK buck. The second power control chip U2 usually adopts a dedicated power management chip that supports BUCK buck.

[0080] The first end of the second switch tube Q2 is connected to the positive electrode of the absorption capacitor C1, the second end of the second switch tube Q2 is connected to the first end of the second inductor L2, the anode of the second freewheeling diode D2 is connected to the negative electrode of the output capacitor C0, and the cathode is connected to the series node between the second inductor L2 and the second end of the second switch tube Q2. The power supply terminal (VCC) and the ground terminal (GND) of the second power control chip U2 are respectively connected to the positive electrode of the absorption capacitor C1 and the negative electrode P- of the output terminal, and the signal control terminal (OP) of the second power control chip U2 is also connected to the control terminal of the second switch tube Q2.

[0081] It can be understood that the connection between the signal control terminal and the control terminal of the second switch tube Q2 can be a direct connection or an indirect connection. For the indirect connection, a device for increasing the driving force can be set between the two. In addition, the above description only reflects the connection relationship between several key pins of the second power control chip U2. In actual application scenarios, the second power control chip U2 will also combine other peripheral devices according to the instructions for use of the chip to ensure the normal use of the chip, which will not be described in detail here.

[0082] Exemplarily, after the second power supply control chip U2 enters the working state, it controls the on and off of the second switch tube Q2, so as to use the second inductor L2 and the second freewheeling diode D2 to step down the output voltage of the absorption capacitor C1 and then input it into the battery. For example, when the second switch tube Q2 is turned on, the loop current flows from the positive electrode of the absorption capacitor C1 through the second switch tube Q2, and then through the second inductor L2 loop to the negative electrode of the absorption capacitor C1, forming a first loop, at which time energy will be stored on the second inductor L2. After the second switch tube Q2 is turned off, the current on the second inductor L2 flows through the output capacitor C0 and the battery, and the second freewheeling diode D2 in sequence, forming a second loop, and charging the battery at this time. Optionally, the feedback end of the second power supply control chip U2 is also connected to the second inductor L2 to collect the loop current, so that the second power supply control chip U2 adjusts the duty cycle used to control the second switch tube Q2 to stabilize the output, etc.

[0083] It can be understood that when the BUCK buck structure is adopted, since the input of the BUCK buck unit 102b is from the positive electrode of the absorption capacitor C1 to the negative electrode P- of the output end, and the output is from the positive electrode B+ to the negative electrode B- of the battery, both are positive at the top and negative at the bottom, it is a traditional unidirectional buck process. For the specific working principle of the BUCK buck, please refer to the relevant documents that have been published, and will not be described here.

[0084] The energy recovery protection circuit 10 of this embodiment realizes energy recovery when the output end is short-circuited by utilizing the absorption unit 101 and the voltage conversion unit 102, and further provides a current sampling unit to feedback to the power control chip, so that it can dynamically adjust the driving signal of the switch tube used for output control, thereby forming a closed-loop regulation, increasing the output stability, and being able to cope with more scenarios, etc.

[0085] Combined with the energy recovery protection circuit 10 of the above structure, Figure 7 As shown, the embodiment of the present application further proposes a BMS protection board 20. Exemplarily, the BMS protection board 20 includes an output terminal, an output capacitor C0, a charge and discharge switch group 201 and the energy recovery protection circuit 10 in the above embodiment.

[0086] The two ends of the output capacitor C0 are respectively used to connect the positive electrode B+ and the negative electrode of the battery; it can be understood that the output capacitor C0 is relative to the battery. The positive electrode P+ and the negative electrode of the output end are respectively used to connect the positive electrode B+ and the negative electrode of the battery.

[0087] The charge and discharge switch group 201 is arranged in series between the battery and the output terminal, wherein the charge and discharge switch group 201 includes a charge switch tube and a discharge switch tube arranged in series. For example, in one embodiment, the positive electrode of the battery connection terminal is directly connected to the positive electrode P+ of the output terminal, that is, when a common positive connection mode is adopted, the charge and discharge switch group 201 is arranged between the negative electrode of the battery connection terminal and the negative electrode P- of the output terminal. Alternatively, the negative electrode of the battery connection terminal is directly connected to the negative electrode P- of the output terminal, that is, when a common negative connection mode is adopted, the charge and discharge switch group 201 is arranged between the positive electrode of the battery connection terminal and the positive electrode P+ of the output terminal.

[0088] The energy recovery protection circuit 10 is arranged between the battery and the output terminal. For the specific connection relationship of the energy recovery protection circuit 10 on the BMS protection board 20, please refer to the description in the above embodiment, which will not be repeated here.

[0089] In this embodiment, the BMS protection board 20 is used to control the discharge switch tube to turn off when the positive electrode P+ and the negative electrode P- of the output end are connected to generate a loop current, so that the loop current is recovered to the battery through the energy recovery protection circuit 10.

[0090] As an optional solution, the freewheeling device T1 in the energy recovery protection circuit 10 can be implemented by a diode or a MOS tube. It is worth noting that when a MOS tube is used, the BMS protection board 20 includes an AFE chip. At this time, the control end of the MOS tube can be connected to the AFE chip, so that after the AFE chip controls the discharge switch tube to be turned off, the MOS tube is controlled to be turned on at the same time, so that the loop current flows through the MOS tube to charge the absorption capacitor C1, and then the voltage conversion unit 102 is used to realize energy recovery to the battery.

[0091] It can be understood that the specific working principle of the energy recovery protection circuit 10 on the BMS protection board 20 is described in the above embodiment, and will not be repeated here. In addition, the options for the energy recovery protection circuit 10 in the above embodiment are also applicable to this embodiment.

[0092] The embodiment of the present application also proposes an energy storage device, for example, it can be a power battery in a variety of different application scenarios. Exemplarily, the energy storage device includes the energy recovery protection circuit 10 or the BMS protection board 20 described in the above embodiment. It can be understood that the options in the above embodiment are also applicable to this embodiment, so they will not be repeated here.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] The above description is only a specific implementation manner 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 included in the protection scope of the present application.

Claims

1. An energy recovery protection circuit, characterized in that: It is arranged between the battery and the output end, and the positive electrode and negative electrode of the battery are respectively connected to the positive electrode and negative electrode of the output end; a discharge switch tube is also arranged between the negative electrode of the battery and the negative electrode of the output end; the energy recovery protection circuit includes: An absorption unit, the absorption unit is located between the positive electrode and the negative electrode of the output end, and the absorption unit includes an absorption capacitor and a freewheeling device arranged in series; A voltage conversion unit, the voltage conversion unit is connected to the absorption unit, and the voltage conversion unit is also connected to an output capacitor located between the positive electrode and the negative electrode of the battery; The absorption unit is used for charging the absorption capacitor after the loop current flows through the turned-on freewheeling device when the positive and negative electrodes of the output end are connected to generate a loop current and the discharge switch tube is turned off; The voltage conversion unit is used to enter a working state when the absorption capacitor is charged to a voltage exceeding the starting voltage of the voltage conversion unit, so as to charge the battery after performing voltage conversion on the output voltage of the absorption capacitor.

2. The energy recovery protection circuit according to claim 1, characterized in that: The absorption unit further includes an absorption resistor and a clamping diode which are arranged in parallel with the absorption capacitor.

3. The energy recovery protection circuit according to claim 1, characterized in that: The freewheeling device is a diode or a MOS tube.

4. The energy recovery protection circuit according to claim 3, characterized in that: When the freewheeling device is a MOS tube, the control end of the MOS tube is used to connect to the front-end analog circuit; The energy recovery protection circuit further includes a current detection unit, and the current detection unit is used to detect the loop current flowing through the MOS tube; The MOS tube is used to be in an on state when the discharge switch tube is turned off and the loop current exists; and to be in an off state when the loop current does not exist.

5. The energy recovery protection circuit according to claim 1, characterized in that: The voltage conversion unit is a reverse DC buck unit, which includes a first power control chip, a first switch tube and an energy storage freewheeling branch, the energy storage freewheeling branch is connected in parallel with the output capacitor, and the first switch tube is respectively connected to the positive electrode of the absorption capacitor and the energy storage freewheeling branch; The power supply end and the ground end of the first power control chip are respectively connected to the positive electrode of the absorption capacitor and the positive electrode of the output end. After entering the working state, the first power control chip is used to control the on and off of the first switch tube to utilize the energy storage freewheeling branch to step down the output voltage of the absorption capacitor and then input it into the battery.

6. The energy recovery protection circuit according to claim 5, characterized in that: The reverse DC buck unit further includes a driving subunit, and the driving subunit is respectively connected to the signal control terminal of the first power control chip and the control terminal of the first switch tube; The first power control chip is used to output a pulse width modulation signal to the driving sub-unit after entering a working state, so as to control the driving sub-unit to be turned on or off, thereby turning the first switch tube on or off accordingly.

7. The energy recovery protection circuit according to claim 5, characterized in that: The energy storage freewheeling branch comprises a first inductor and a first freewheeling diode connected in series; One end of the first inductor is connected to the positive electrode of the output capacitor, the other end of the first inductor is connected to the cathode of the first freewheeling diode, and the anode of the first freewheeling diode is connected to the negative electrode of the output capacitor.

8. The energy recovery protection circuit according to claim 7, characterized in that: The reverse DC buck unit further includes a current sampling subunit, the current sampling subunit is connected to the first inductor, and the current sampling subunit is also connected to the signal feedback terminal of the first power control chip; The first power control chip is further used to adjust the duty cycle of a control signal used to control the first switch tube according to the loop current flowing through the first inductor collected by the current sampling subunit, using the loop current.

9. The energy recovery protection circuit according to claim 8, characterized in that: The current sampling subunit includes a sampling resistor, which is connected in series between the positive electrode of the output capacitor and the first inductor, and a series node between the sampling resistor and the first inductor is connected to the signal feedback end of the first power control chip.

10. The energy recovery protection circuit according to claim 1, characterized in that: The voltage conversion unit is a BUCK step-down unit, which includes a second power control chip, a second switch tube, a second inductor, and a second freewheeling diode, wherein a first end of the second switch tube is connected to the positive electrode of the absorption capacitor, a second end of the second switch tube is connected to the second inductor, an anode of the second freewheeling diode is connected to the negative electrode of the output capacitor, and a cathode is connected to a series node of the second end of the second switch tube and the second inductor; The power supply end and the ground end of the second power supply control chip are respectively connected to the positive electrode of the absorption capacitor and the negative electrode of the output end. After entering the working state, the second power supply control chip is used to control the on and off of the second switch tube to use the second inductor and the second freewheeling diode to step down the output voltage of the absorption capacitor and input it into the battery.

11. A BMS protection board, characterized in that: It comprises an output terminal, an output capacitor, a charge and discharge switch group and an energy recovery protection circuit as claimed in any one of claims 1 to 10; The two ends of the output capacitor are used to respectively connect to the positive electrode and the negative electrode of the battery; The positive electrode and the negative electrode of the output terminal are used to connect the positive electrode and the negative electrode of the battery respectively; The charge and discharge switch group is arranged in series between the negative electrode of the battery and the negative electrode of the output end; wherein the charge and discharge switch group comprises a charge switch tube and a discharge switch tube arranged in series; The energy recovery protection circuit is arranged between the battery and the output end; The BMS protection board is used to control the discharge switch tube to turn off when the positive and negative electrodes of the output end are connected to generate a loop current, so that the loop current is recovered to the battery through the energy recovery protection circuit.

12. An energy storage device, characterized in that: It comprises the energy recovery protection circuit as described in any one of claims 1 to 10 or the BMS protection board as described in claim 11.

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