Control circuit

Abstract

The invention discloses a control circuit. The circuit comprises a discharge MOSFET, the drain electrode of the discharge MOSFET is connected with the positive electrode of a battery pack, and the source electrode of the discharge MOSFET is connected with a load; the first end of the first switch module is connected with the grid electrode of the discharging MOSFET; the first end of the energy consumption module is connected with the second end of the first switch module, and the second end of the energy consumption module is connected with the source electrode of the discharging MOSFET; the first switch module is used for conducting according to the turn-off instruction, so that the discharge MOSFET, the first switch module and the energy consumption module form a closed loop; the turn-off instruction is an instruction for turning off the discharge MOSFET. According to the embodiment of the invention, the discharge MOSFET can be turned off.

Description

[0001] Case Analysis

[0002] This invention is a divisional application of a Chinese patent filed on April 9, 2020, with application number 202010276317.3 and invention title "Switch-off Circuit". Technical Field

[0003] This invention relates to the field of new energy, and in particular to a control circuit. Background Technology

[0004] Electric vehicles replacing gasoline-powered vehicles has become a trend in the automotive industry. The driving range, lifespan, and safety of battery packs are all particularly important for the use of electric vehicles. A common power supply solution for electric vehicles is for the battery pack to power the load.

[0005] To enhance market competitiveness, metal-oxide-semiconductor field-effect transistors (MOSFETs) are typically used as switches to control the power supply from the battery pack to the load. MOSFETs contain parasitic capacitance. When the discharge MOSFET is closed, the battery pack can supply power to the load. However, when a short circuit occurs in the external load, the discharge MOSFET needs to be turned off. Therefore, a switch turn-off circuit is required to shut down the discharge MOSFET. Summary of the Invention

[0006] This invention provides a control circuit capable of turning off a discharge MOSFET.

[0007] This invention provides a control circuit, which includes a switch-off circuit, the switch-off circuit comprising:

[0008] The drain of the discharge MOSFET is connected to the positive terminal of the battery pack, and the source of the discharge MOSFET is connected to the load.

[0009] The first switching module has its first terminal connected to the gate of the discharge MOSFET.

[0010] An energy consumption module, the first terminal of which is connected to the second terminal of the first switching module, and the second terminal of which is connected to the source of the discharge MOSFET;

[0011] The first switching module is used to turn on according to the turn-off command, so that the discharge MOSFET, the first switching module and the energy consumption module form a closed loop; the turn-off command is the command to turn off the discharge MOSFET.

[0012] In one embodiment, the control circuit further includes a drive module for controlling the first switch module to conduct based on a received shutdown command.

[0013] In one embodiment, the control circuit further includes:

[0014] The unidirectional conduction module has its first terminal connected to the gate of the discharge MOSFET and its second terminal connected to the drive module. The current direction of the unidirectional conduction module is from the second terminal to the first terminal.

[0015] The drive module is connected to the third terminal of the first switch module.

[0016] In one embodiment, the first switching module includes a transistor;

[0017] The emitter of the transistor is connected to the gate of the discharge MOSFET, the base of the transistor is connected to the drive module, and the collector of the transistor is connected to the first terminal of the energy consumption module.

[0018] In one embodiment, the energy consumption module includes a first resistor network, a first end of which is connected to a second end of a first switching module, and the second end of which is connected to the source of a discharge MOSFET.

[0019] In one embodiment, the unidirectional conduction module includes a diode, the anode of which is connected to a first terminal of the drive module, and the cathode of which is connected to the gate of the discharge MOSFET.

[0020] In one embodiment, the control circuit further includes:

[0021] The first current limiting module has its first end connected to the driver module, and its second end connected to the second end of the unidirectional conduction module.

[0022] In one embodiment, the first current limiting module includes a second resistor network, a first end of which is connected to the driving module, and a second end of which is connected to the second end of the unidirectional conduction module.

[0023] In one embodiment, the control circuit further includes a capacitor module, and the drive module includes a second switch module and a third resistor network.

[0024] The first terminal of the drive module is connected to the first terminal of the second switch module and the second terminal of the unidirectional conduction module; the second terminal of the second switch module is connected to the first terminal of the third resistor network; and the second terminal of the drive module is connected to the second terminal of the third resistor network, the first terminal of the capacitor module, and the source of the discharge MOSFET.

[0025] The second terminal of the capacitor module is connected to the negative terminal of the battery pack;

[0026] The drive module is used to control the second switch module to turn on when a shutdown command is received, and to control the first terminal of the drive module to not output voltage, so as to control the first switch module to turn on.

[0027] In one embodiment, the drive module is further configured to control the discharge MOSFET to turn on upon receiving an instruction to close the discharge MOSFET.

[0028] According to an embodiment of the present invention, when the first switching module is turned on according to the turn-off command of the discharge MOSFET, the parasitic capacitance of the discharge MOSFET, the first switching module and the energy consumption module form a discharge circuit of the parasitic capacitance, thereby realizing the turn-off of the discharge MOSFET. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This diagram shows a schematic of the switch-off circuit provided in the first embodiment of the present invention.

[0031] Figure 2 Show Figure 1 A schematic diagram of the discharge circuit for parasitic capacitance in the middle;

[0032] Figure 3 This diagram shows a schematic of the switch-off circuit provided in the second embodiment of the present invention.

[0033] Figure 4 This diagram shows a schematic diagram of the switch-off circuit provided in the third embodiment of the present invention.

[0034] Figure 5 This diagram shows a schematic of the switch-off circuit provided in the fourth embodiment of the present invention.

[0035] Figure 6 This diagram shows a schematic of the switch-off circuit provided in the fifth embodiment of the present invention.

[0036] Figure 7 This diagram shows a schematic of the switch-off circuit provided in the sixth embodiment of the present invention.

[0037] Figure 8 This diagram shows a schematic diagram of the switch-off circuit provided in the seventh embodiment of the present invention.

[0038] Figure 9A schematic diagram of the switch-off circuit provided in the eighth embodiment of the present invention is shown. Detailed Implementation

[0039] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the invention.

[0040] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0041] Figure 1 A schematic diagram of the switch-off circuit provided in the first embodiment of the present invention is shown. Figure 1 As shown, the circuit includes a battery pack P1, a charging MOSFET Q1, a discharging MOSFET Q2, a driver chip, resistors R1, R2, R4, and R5, and capacitors C1 and C2.

[0042] In this configuration, the source of the charging MOSFET Q1 is connected to the positive terminal of the battery pack P1, the drain of the charging MOSFET Q1 is connected to the drain of the discharging MOSFET Q2, and the gate of the charging MOSFET Q1 is connected to the first terminal of the resistor R1.

[0043] In this configuration, the gate of the discharge MOSFET Q2 is connected to the first terminal of resistor R2, and the source of the discharge MOSFET Q2 is connected to both the first terminal of the load and the first terminal of resistor R5. The second terminal of the load is connected to the negative terminal of battery pack P1.

[0044] The driver chip has DSG, CHG, PACK, GND, and BAT pins. It also includes a resistor R3 and a switch K0.

[0045] The CHG pin of the driver chip is connected to the second terminal of resistor R1. The DSG pin of the driver chip is connected to the second terminal of resistor R2 and the first terminal of switch K0, respectively. The PACK pin of the driver chip is connected to the first terminals of resistor R3, resistor R5, and capacitor C1, respectively. The GND pin of the driver chip is connected to the negative terminal of battery pack P1. The BAT pin of the driver chip is connected to the first terminal of resistor R4 and capacitor C2, respectively.

[0046] Specifically, the second terminal of switch K0 is connected to the second terminal of resistor R3. The second terminal of capacitor C1 is connected to the negative terminal of battery pack P1. The second terminal of resistor R4 is connected to the positive terminal of battery pack P1. The second terminal of capacitor C2 is connected to power ground GND.

[0047] Battery pack P1 has two switches for discharging externally: a charging MOSFET Q1 and a discharging MOSFET Q2. When both charging MOSFET Q1 and discharging MOSFET Q2 are closed, the positive and negative terminals of battery pack P1 discharge power to the load; therefore, the discharging MOSFET can also be called a "discharge switch." (See also...) Figure 1 , Figure 1 The switching off circuit also includes a current detection module I. The first terminal of current detection module I is connected to the negative terminal of battery pack P1, and the second terminal is connected to the load. Current detection module I is used to detect the current in the discharge circuit of battery pack P1. When external loads or other factors cause a short circuit between P+ (the source of discharge MOSFET Q2) and P- (the negative terminal of battery pack P1) or a very low impedance, the current in the discharge circuit of battery pack P1 can reach several hundred amperes or even higher. At this time, after the current detection module detects that the current in the discharge circuit exceeds the set short-circuit threshold, it sends a command to the driver chip to turn off discharge MOSFET Q2, thereby protecting the safety of battery pack P1, the load, and the user.

[0048] See Figure 1 The normal discharge process of battery pack P1 to the load is as follows:

[0049] When the driving chip receives the discharge instruction, the DSG pin of the driving chip outputs a voltage, making the voltage difference Vgs between the gate and the source of the discharge MOSFET Q2 greater than the preset threshold Vgs_threshold. For example, if Vgs_threshold is 4V, the DSG pin of the driving chip outputs a voltage greater than the source voltage of MOSFET Q2 + 4V, that is, making Vgs of the discharge MOSFET Q2 = 4V (where the size of the preset threshold is related to the model of the discharge MOSFET Q2). At this time, the discharge MOSFET Q2 is closed.

[0050] During the normal discharge process, if due to abnormal load or other factors, P+ is shorted to P- or the impedance is very small, and an external short circuit is detected at this time, the current detection module I sends an instruction to turn off the discharge MOSFET Q2 to the driving chip.

[0051] See Figure 1 , when the driving chip receives the instruction to turn off the discharge MOSFET Q2, the DSG pin of the driving chip no longer outputs a voltage externally, but controls the switch K0 to close. The driving chip internally connects the DSG pin of the driving chip to the PACK pin of the driving chip through the resistor R3 (the resistance value of the resistor R3 of different driving chips is different). Turning off the discharge MOSFET Q2 must make Vgs < Vgs_threshold (preferably Vgs = 0V), but due to the existence of the parasitic capacitance Cgs of the discharge MOSFET Q2, the Vgs voltage cannot be instantaneously reduced to 0V. Therefore, the charge stored in Cgs needs to be discharged to achieve the turn-off of the discharge MOSFET Q2. At this time, the parasitic capacitance Cgs of the discharge MOSFET Q2, the resistor R2, the resistor R3, and the resistor R5 form a discharge circuit for Cgs. See Figure 2 the circuit shown by the arrow in

[0052] Combined with Figure 1 where Figure 2 the resistance of the discharge circuit of the parasitic capacitance Cgs of the discharge MOSFET Q2 in

[0053] is R2 + R3 + R5, so the discharge time constant of the parasitic capacitance Cgs of the discharge MOSFET Q2 is t = (R2 + R3 + R5) * Cgs.

[0053] Among them, the functions of the resistors R2 and R5 are to prevent electrostatic discharge and hot plugging, so the resistance values are generally selected to be relatively large. Therefore, Figure 2The total resistance of the discharge circuit for the parasitic capacitance Cgs of the discharge MOSFET Q2 is relatively large, and it takes a certain amount of time to completely dissipate the charge within Cgs. During the discharge process of Cgs, because Vgs > Vgs_threshold, the discharge MOSFET Q2 remains in the on-state. Furthermore, under short-circuit conditions, the current is very large, and the turn-off process of the discharge MOSFET Q2 generates a significant amount of heat, which can easily lead to thermal damage to the discharge MOSFET Q2.

[0054] Therefore, in order to turn off the discharge MOSFET Q2, embodiments of the present invention provide a method that... Figure 1 A completely different switching circuit is used to achieve the effect of turning off and discharging MOSFET Q2. A detailed description is provided below with reference to the accompanying drawings and embodiments.

[0055] Figure 3 A schematic diagram of the switch-off circuit provided in the second embodiment of the present invention is shown. Figure 3 As shown, the switch-off circuit provided in this embodiment of the invention includes:

[0056] The discharge MOSFET (discharge switch) Q2 has its drain (first terminal) connected to the positive terminal of the battery pack P1, and its source (second terminal) connected to the load.

[0057] The first switch module K1 has its first terminal connected to the gate (third terminal) of the discharge MOSFET Q2.

[0058] Energy consumption module N, the first terminal of energy consumption module N is connected to the second terminal of the first switching module K1, and the second terminal of energy consumption module N is connected to the source (second terminal) of discharge MOSFET Q2.

[0059] The first switching module K1 is used to turn on according to the turn-off command, so that the discharge MOSFET Q2, the first switching module K1, and the energy consumption module N form a closed loop. The turn-off command is the command to turn off the discharge MOSFET Q2.

[0060] Among them, the source (second terminal) of the discharge MOSFET Q2 is connected to the first terminal of the load, and the second terminal of the load is connected to the negative terminal of the battery pack P1.

[0061] In an embodiment of the present invention, when the first switching module K1 is turned on according to the turn-off command of the discharge MOSFET Q2, the parasitic capacitance of the discharge MOSFET Q2, the first switching module K1, and the energy consumption module N form a discharge circuit for the parasitic capacitance. When a certain amount of charge is released from the parasitic capacitance, the voltage difference Vgs between the source (second terminal) and the gate (third terminal) of the discharge MOSFET Q2 is less than the preset threshold Vgs_threshold, then the discharge MOSFET Q2 can be turned off, so that the voltage difference Vgs between the source (second terminal) and the gate (third terminal) of the discharge MOSFET Q2 is finally 0V.

[0062] The closed loop formed by the discharge MOSFET Q2, the first switching module K1, and the energy consumption module N is the discharge loop formed by the parasitic capacitance of the discharge MOSFET Q2, the first switching module K1, and the energy consumption module N.

[0063] Since the discharge time of the parasitic capacitor is determined by the impedance of the first switching module K1 and the impedance of the energy consumption module N, the impedance of the first switching module K1 is generally very small after it is turned on. By further controlling the impedance of the energy consumption module N, the discharge time of the parasitic capacitor can be reduced, thereby accelerating the turn-off of the discharge MOSFET Q2.

[0064] for Figure 3 In the switching off circuit, the switching off time t of the discharging MOSFET Q2 is t = (R C +R N )*Cgs. Where R C The on-resistance of the first switching module K1, R N The impedance of the energy-consuming module N. Because... Figure 1 The impedances of R2 and R5 in the circuit are generally quite large, and... Figure 1 Compared to the switch-off circuit in the middle, Figure 3 The switch-off circuit provided can select the first switch module K1 and the energy consumption module N according to the requirements, thereby reducing the impedance of the discharge circuit of the parasitic capacitance Cgs of the discharge MOSFET Q2, so as to reduce the discharge time of the parasitic capacitance Cgs.

[0065] In embodiments of the present invention, the turn-off speed of MOSFET Q2 can be controlled by selecting appropriate resistance values ​​for the first switching module K1 and the energy consumption module N, thereby controlling the heat generation of the first switching module K1. As an example, the sum of the on-resistance of the first switching module K1 and the impedance of the energy consumption module N (i.e., R...) C +R N It needs to meet a first preset condition. For example, the first preset condition is R. C +R NThe resistance is less than the first preset value. The first preset value is determined by the ratio of the maximum tolerable turn-off time of the discharge MOSFET Q2 under load short-circuit conditions to the parasitic capacitance Cgs of the discharge MOSFET Q2. It should be noted that the maximum tolerable turn-off time of the discharge MOSFET Q2 under load short-circuit conditions can be measured offline in advance.

[0066] By making R C +R N Meeting the first preset condition allows the discharge MOSFET Q2 to be safely turned off without damage.

[0067] In embodiments of the present invention, the first switch module K1 can be selected from those with low on-resistance. The resistance value of the energy consumption module N cannot be too large, as this will not achieve the effect of rapid turn-off; nor can it be too small, as this will cause the first switch module K1 to generate excessive heat and be easily damaged. Therefore, when R... C +R N When the first preset condition is met, in order to protect the first switching module K1 from damage, the impedance of the energy consumption module N also meets the second preset condition. (Rc+R) N Under the condition that the first preset condition is met, the second preset condition is that the heat generated by the first switching module K1 is less than the maximum heat generated that the first switching module K1 can tolerate when the load is short-circuited. The maximum heat generated that the first switching module K1 can tolerate can be measured offline.

[0068] By using the first and second preset conditions, the resistance values ​​of the first switching module K1 and the energy consumption module N can be reasonably set, which can protect the first switching module K1 from damage and safely turn off the discharge MOSFET Q2.

[0069] In some embodiments of the present invention Figure 3 The switching off circuit also includes a drive module G ( Figure 3 (Not shown in the image). The drive module G controls the first switch module K1 to turn on based on the received turn-off command. That is, a control circuit can be provided here, in which the switch turn-off circuit and the drive module G are disposed. When the first switch module K1 is turned on, the parasitic capacitance of the discharge MOSFET Q2, the first switch module K1, and the energy consumption module N form a discharge circuit for the parasitic capacitance, thereby turning off the discharge MOSFET Q2.

[0070] It should be noted that, with Figure 1 Similar to the switch-off circuit in [the context of the circuit], for Figure 3 The switching off circuit in the battery pack may also include a charging MOSFET positioned between the positive terminal of battery pack P1 and the discharge MOSFET Q2, which will not be elaborated upon here. Figure 3 As shown in the image.

[0071] When the drive module G receives a discharge command, that is, a command to close the discharge MOSFET Q2, it outputs a drive voltage to make the difference between the voltage at the gate of the discharge MOSFET Q2 and the voltage at the source of the discharge MOSFET Q2 greater than a preset threshold, so that the discharge MOSFET Q2 is turned on.

[0072] Figure 4 A schematic diagram of the switch-off circuit provided in the third embodiment of the present invention is shown. Figure 4 The switching off circuit in the middle includes not only Figure 3 The components also include a drive module G and a one-way conduction module C.

[0073] The first terminal of the unidirectional conduction module C is connected to the gate of the discharge MOSFET Q2, and the second terminal of the unidirectional conduction module C is connected to the drive module G. The current direction of the unidirectional conduction module C is: from the second terminal of the unidirectional conduction module C to the first terminal of the unidirectional conduction module C.

[0074] The drive module G is connected to the third terminal of the first switch module K1.

[0075] In an embodiment of the present invention, by utilizing the unidirectional conduction module C, the charge of the parasitic capacitance of the discharge MOSFET Q2 can be prevented from affecting the drive module G, and preparation is also made for turning on the first switch module K1.

[0076] During normal discharge, due to abnormal load or other factors, P+ may be short-circuited to P- or the impedance may be very small. In this case, the current detection module I detects a short circuit in the P+ to P- circuit and sends a command to turn off the discharge MOSFET Q2. The drive module G is used to stop outputting voltage or outputting a first preset voltage upon receiving the command to turn off the discharge MOSFET Q2, so as to drive the first switching module K1 to turn on and turn off the discharge MOSFET Q2.

[0077] It should be noted that the first preset voltage output by the drive module G needs to meet the conduction condition of the first switch module K1.

[0078] Figure 5 A schematic diagram of the switch-off circuit provided in the fourth embodiment of the present invention is shown. Figure 4 The difference in the switch-off circuit is that, Figure 5 The switch-off circuit also shows the specific structure of the unidirectional conduction module C, the first switch module K1, and the energy consumption module N in the discharge circuit of the parasitic capacitance of the discharge MOSFET Q2.

[0079] In some embodiments, the unidirectional conduction module C includes a diode D1, the anode of which is connected to the drive module G, and the cathode of which is connected to the gate of the discharge MOSFET Q2.

[0080] In an embodiment of the present invention, by utilizing the unidirectional conduction module C, the charge of the parasitic capacitance of the discharge MOSFET Q2 can be prevented from affecting the drive module G, and preparation is also made for turning on the first switch module K1.

[0081] In some embodiments, the first switching module K1 includes a transistor Q3, the emitter (first terminal) of transistor Q3 is connected to the gate (third terminal) of discharge MOSFET Q2, the base (third terminal) of transistor Q3 is connected to the second terminal of unidirectional conduction module C, and the collector (second terminal) of transistor Q3 is connected to the first terminal of energy consumption module N.

[0082] When the drive module G receives a command to turn off the discharge MOSFET Q2, due to the unidirectional conduction characteristic of the unidirectional conduction module C, the voltage Ve at the emitter (first terminal) of transistor Q3 is equal to the gate voltage Vg of the discharge MOSFET Q2. If the drive module G stops outputting voltage, the voltage Ve at the emitter (first terminal) of transistor Q3 is greater than the voltage Vb at the base (third terminal) of transistor Q3, thus satisfying the conduction condition of transistor Q3.

[0083] In other embodiments, the driving module G can also output a first preset voltage, in which case the voltage Vb at the base (third terminal) of transistor Q3 is the first preset voltage, so that the voltage Ve at the emitter (first terminal) of transistor Q3 is greater than the voltage Vb at the base (third terminal) of transistor Q3. When P+ is short-circuited to P- or the impedance is very small, the voltage P+ is very low, and the voltage Vc at the collector (second terminal) of transistor Q3 is also very low. Therefore, the first preset voltage is set to be greater than the voltage Vc at the collector (second terminal) of transistor Q3, i.e., Ve>Vb>Vc, to meet the conduction condition of transistor Q3, so that transistor Q3 is turned on, thereby turning off the discharge MOSFET Q2.

[0084] In some embodiments, the energy consumption module N includes a first resistor network, a first end of which is connected to a second end of the first switching module K1, and a second end of which is connected to the source of the discharge MOSFET Q2.

[0085] In some specific embodiments, the first resistor network includes a resistor R6. A first terminal of resistor R6 is connected to a second terminal of the first switching module K1, and the second terminal of resistor R6 is connected to the source of the discharge MOSFET Q2.

[0086] When the first switching module K1 includes a transistor Q3 and the unidirectional conduction module C includes a diode D1, the anode of diode D1 is connected to both the driving module G and the base of transistor Q3, and the cathode of diode D1 is connected to the emitter of transistor Q3. The emitter of transistor Q3 is connected to the gate of discharge MOSFET Q2. The collector of transistor Q3 is connected to the first terminal of resistor R6.

[0087] When the drive module G receives the instruction to turn off the discharge MOSFET Q2, the parasitic capacitance Cgs of the discharge MOSFET Q2, the transistor Q3, and the resistor R6 form the discharge circuit of the parasitic capacitance. Figure 5 The dashed arrow in the figure shows the current flow direction of the discharge circuit of the parasitic capacitance Cgs of the discharge MOSFET Q2.

[0088] When the drive module G receives a command to turn off the discharge MOSFET Q2, the drive module G either does not output voltage or outputs a first preset voltage to turn on the transistor Q3. The parasitic capacitance Cgs of the discharge MOSFET Q2 is then released through... Figure 5 The discharge circuit shown in the diagram discharges. Specifically, in... Figure 5 In the discharge circuit, the resistance of the discharge circuit for the parasitic capacitance Cgs of the discharge MOSFET Q2 is R. Q3 +R6, therefore the discharge time constant of the parasitic capacitance Cgs of the discharging MOSFET Q2 is t=(R Q3 +R6)*Cgs. Where R Q3 This is the on-resistance of the transistor.

[0089] and Figure 1 Compared to the switch-off circuit in the previous example, the impedance R after transistor Q3 is turned on is... Q3 Since the resistance of R6 is very small, it is easy to control the value of R6 to a smaller value. Therefore, the switch-off circuit provided in this embodiment of the invention can greatly reduce the impedance of the discharge circuit and achieve the purpose of timely switching off of the discharge MOSFET Q2 within the required time.

[0090] Figure 6 A schematic diagram of the switch-off circuit provided in the fifth embodiment of the present invention is shown. Figure 5 The difference between the switch-off circuit and the circuit is that... Figure 6 The switch-off circuit also includes a first current-limiting module L.

[0091] The first end of the first current limiting module L is connected to the driving module G, and the second end of the first current limiting module L is connected to the second end of the unidirectional conduction module C.

[0092] In an embodiment of the present invention, the first current limiting module L can protect the drive module G and the discharge MOSFET Q2. At the moment the discharge MOSFET Q2 is closed, it plays a current limiting role to prevent the inrush current from being too large and damaging the drive module G and the discharge MOSFET Q2.

[0093] In some embodiments, the first current limiting module L includes a second resistor network, a first end of which is connected to the driving module G, and a second end of which is connected to the second end of the unidirectional conduction module C.

[0094] Figure 7 A schematic diagram of the switch-off circuit provided in the sixth embodiment of the present invention is shown. Figure 6 The difference between the switch-off circuit and the circuit is that... Figure 7 The switch-off circuit illustrates the specific structure of the first current-limiting module L.

[0095] As a specific example, the second resistor network includes resistor R7. The first end of resistor R7 is connected to the drive module G, and the second end of resistor R7 is connected to the second end of the unidirectional conduction module C.

[0096] The protection of the drive module G and the discharge MOSFET Q2 can be easily and conveniently achieved by using resistor R7.

[0097] Figure 8 A schematic diagram of the switch-off circuit provided in the seventh embodiment of the present invention is shown. Figure 7 The difference between the switch-off circuit and the switch-off circuit is that... Figure 8 The switching off circuit also includes a capacitor module C', and the specific structure of the drive module G is given.

[0098] The drive module G includes a second switch module K2 and a third resistor network R'.

[0099] The first terminal of the drive module G is connected to the second terminal of the unidirectional conduction module C and the first terminal of the second switch module K2; the second terminal of the second switch module K2 is connected to the first terminal of the third resistor network R'; and the second terminal of the drive module G is connected to the second terminal of the third resistor network R', the first terminal of the capacitor module C', and the source of the discharge MOSFET Q2.

[0100] The second terminal of capacitor module C' is connected to the negative terminal of battery pack P1.

[0101] The drive module G is used to control the second switch module K2 to turn on and stop the output voltage when it receives the instruction to turn off the discharge MOSFET Q2, so as to control the first switch module K1 to turn on.

[0102] The capacitor module C' serves as a decoupling and filtering component. External interference can be pre-filtered before entering the driver module G. The decoupling capacitor module C' filters out noise interference generated by the switching frequency within the driver module G, preventing it from affecting external circuits or other chips.

[0103] In an embodiment of the present invention, where a control circuit is provided, the unidirectional conduction module C, the first current limiting module L, and the capacitor module C' can all be arranged together with the drive module G in the control circuit.

[0104] In an embodiment of the present invention, when the driving module G receives an instruction to turn off the discharge MOSFET Q2, it controls the second switching module K2 to turn on and controls the first terminal of the driving module G to stop outputting voltage, so that the first switching module K1 turns on. Due to the unidirectional conduction characteristic of the unidirectional conduction module C, the emitter voltage Ve of the transistor Q3 is equal to the gate voltage Vg of the discharge MOSFET Q2.

[0105] When battery pack P1 is discharging normally, charge accumulates on capacitor module C'. When a command to turn off MOSFET Q2 is received, the charge on capacitor module C' has not yet been released, so the second terminal of driver module G still has voltage. Since driver module G has no output voltage and the second switch module K2 is closed, the base voltage Vb of transistor Q3 is equal to the voltage at the second terminal of driver module G.

[0106] When P+ is short-circuited to P- or the impedance is very small, the voltage of P+ is very low, and the collector voltage Vc of transistor Q3 is also very low. Therefore, Ve>Vb>Vc, which satisfies the conduction condition of transistor Q3, making transistor Q3 conduct and thus turning off the discharge MOSFET Q2.

[0107] See also Figure 8 The capacitor module C' includes a first capacitor. The first terminal of the first capacitor is connected to the second terminal of the drive module G and the source of the discharge MOSFET Q2, respectively. The second terminal of the first capacitor is connected to the second terminal of the load and the negative terminal of the battery pack P1, respectively.

[0108] In some embodiments, Figure 8 The second switch module K2 in the middle can be Figure 1 In the circuit, switch K0 and the third resistor network R' can be... Figure 1 The resistor R3 in the middle, the first capacitor can be Figure 1 The capacitor C1 in the middle. That is to say, Figure 8 For targeting Figure 1The improved circuit of the switch-off circuit can make the parasitic capacitance Cgs of the discharge MOSFET Q2 bypass resistors R2, R3 and R5 during discharge, so that the transistor Q3 and resistor R6 can be used to discharge the parasitic capacitance Cgs of the discharge MOSFET Q2, which greatly reduces the impedance of the discharge circuit, achieves the purpose of fast turn-off, and improves the reliability of the turn-off process of the discharge MOSFET Q2.

[0109] In embodiments of the present invention, transistor Q3 and resistor R6 can also be adjusted by selecting appropriate resistance values ​​to regulate the turn-off speed of MOSFET Q2 and control the heat generation of transistor Q3. Specifically, transistor Q3 can be selected with a lower on-resistance. The resistance value of resistor R6 cannot be too large, as this will not achieve the effect of rapid turn-off; nor can it be too small, as this will lead to excessive heat generation of transistor Q3 and easy damage. Therefore, the sum of the on-resistance of transistor Q3 and the impedance of resistor R6 needs to meet a first preset condition, and the impedance of resistor R6 also needs to meet a second preset condition. By adjusting the on-resistance of transistor Q3 and the impedance of resistor R6, the purpose of rapidly turning off the discharge MOSFET Q2 is achieved, improving the reliability of the turn-off process of discharge MOSFET Q2, thereby improving the safety of battery pack P1 and the load, and ensuring the safety of the user.

[0110] Figure 9 A schematic diagram of the switch-off circuit provided in the eighth embodiment of the present invention is shown. Figure 4 The difference in the switch-off circuit is that, Figure 9 The switch-off circuit in the middle also includes Figure 1 The circuit includes a charging MOSFET Q1, resistors R1, R2, R4, and R5, and capacitors C1 and C2. Figures 4-8 The driver module in the middle can be Figure 1 , Figure 2 and Figure 9 The driver chip in the process.

[0111] In other words, Figure 9 The switch-off circuit in the middle is Figure 1 This design is an improvement upon the switch-off circuit in the original circuit. It not only includes circuitry for preventing electrostatic discharge and hot-plugging, but also a circuit for discharging the parasitic capacitance of the MOSFET Q2. Figure 1 The switch-off circuit in the middle has been improved by adding a unidirectional conduction module C, a first switch module K1, and an energy consumption module N.

[0112] The connection relationships between the charging MOSFET Q1, resistors R1, R2, R4, R5, capacitors C1 and C2, and the driver chip can be found above. Figure 1The description in the text is already provided and will not be repeated here. (And...) Figure 1 The difference lies in the connection relationships of the components in the switch-off circuit. Figure 9 The first terminal of resistor R2 is connected to the second terminal of unidirectional conduction module C. The first terminal of unidirectional conduction module C is connected to the gate of discharge MOSFET Q2 and the first terminal of first switching module K1. The second terminal of first switching module K1 is connected to the first terminal of energy consumption module N, and the third terminal of first switching module K1 is connected to the second terminal of unidirectional conduction module C. The second terminal of energy consumption module N is connected to the source of discharge MOSFET Q2. Wherein, (R2+R3+R5) is greater than (R... C +R N ).

[0113] In some embodiments, Figure 9 The unidirectional conduction module C can be a diode D1, the first switch module K1 can be a transistor Q3, and the energy consumption module N can be a resistor R6, which will not be elaborated further here. Where (R2+R3+R5) is greater than (R... Q3 +R6).

[0114] See Figure 9 When the driver chip receives the command to turn off the discharge MOSFET Q2, the DSG pin of the driver chip no longer outputs voltage and controls switch K0 to close. However, due to... Figure 8 The circuit contains a unidirectional conduction module C. This unidirectional conduction module C has a unidirectional conduction characteristic, leading to... Figure 2 The discharge circuit shown cannot be turned on, so the parasitic capacitance Cgs of the discharge MOSFET Q2 no longer discharges from the circuit. Figure 2 The discharge circuit shown in the figure discharges.

[0115] When the driver chip receives the instruction to turn off the discharge MOSFET Q2, due to the unidirectional conduction characteristic of the unidirectional conduction module C, the voltage Ve of the emitter of the transistor Q3 is equal to the gate voltage Vg of the discharge MOSFET Q2.

[0116] When battery pack P1 is discharging normally, charge accumulates on capacitor C1. When a command to turn off MOSFET Q2 is received, the charge on capacitor C1 has not yet been released, so the PACK pin of the driver chip still has a certain voltage. Since the DSG pin of the driver chip no longer outputs voltage and switch K0 is closed, the base voltage Vb of transistor Q3 is equal to the voltage of the PACK pin of the driver chip.

[0117] When P+ is short-circuited to P- or the impedance is very small, the P+ voltage is very low, and therefore the collector voltage Vc of transistor Q3 is also very low. Thus, Ve > Vb > Vc, satisfying the conduction condition of transistor Q3, causing it to conduct. The parasitic capacitance Cgs of the discharging MOSFET Q2, transistor Q3, and resistor R6 form the discharge circuit for this parasitic capacitance. Therefore, the discharge time constant of the parasitic capacitance Cgs is (R... Q3 +R6)*Cgs.

[0118] for Figure 1 The circuit in Figure 9 The switching circuit in the circuit includes both a working circuit, which can perform the functions of a working circuit, such as preventing electrostatic discharge and hot-plugging, and a discharge circuit for parasitic capacitance. Furthermore, since the discharge time constant of the parasitic capacitance Cgs of the discharging MOSFET Q2 is (R2+R3+R5)*Cgs, since (R... Q3 +R6) is less than (R2+R3+R5), which makes the turn-off time of MOSFET Q2 less than Figure 1 The switching turn-off circuit in the circuit controls the turn-off time of the discharge MOSFET Q2, thus achieving rapid turn-off of the discharge MOSFET Q2. By selecting the values ​​of transistor Q3 and resistor R6, the turn-off speed of MOSFET Q2 can be adjusted, the heat generation of transistor Q3 can be controlled, and the reliability and safety of the turn-off process of discharge MOSFET Q2 can be improved.

[0119] The above are merely specific embodiments of the present invention. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A control circuit, characterized in that, The control circuit includes a switch-off circuit, and the switch-off circuit includes: A discharge switch, wherein the first end of the discharge switch is connected to the positive terminal of the battery pack, the second end of the discharge switch is connected to the first end of the load, and the second end of the load is connected to the negative terminal of the battery pack; A first switch module, wherein a first end of the first switch module is connected to a third end of the discharge switch; An energy consumption module, wherein a first end of the energy consumption module is connected to a second end of the first switch module, and a second end of the energy consumption module is connected to a second end of the discharge switch; The first switch module is used to turn on according to the turn-off command, so that the parasitic capacitance of the discharge switch, the first switch module and the energy consumption module form a discharge circuit of the parasitic capacitance, and turn off the discharge switch when the voltage difference between the second and third terminals of the discharge switch is less than a preset threshold; the turn-off command is the command to turn off the discharge switch.

2. The control circuit according to claim 1, characterized in that, The switching off time of the discharge switch is related to the on-resistance of the first switch module, the impedance of the energy consumption module, and the parasitic capacitance of the discharge switch, and the sum of the on-resistance of the first switch module and the impedance of the energy consumption module satisfies a first preset condition.

3. The control circuit according to claim 2, characterized in that, The sum of the on-resistance of the first switching module and the impedance of the energy consumption module satisfies a first preset condition, including: the sum of the on-resistance of the first switching module and the impedance of the energy consumption module is less than a first preset resistance value. The first preset resistance value is determined based on the ratio of the maximum tolerable turn-off time of the discharge switch when the load is short-circuited to the parasitic capacitance of the discharge switch.

4. The control circuit according to claim 2, characterized in that, The impedance of the energy consumption module also meets the second preset condition; The second preset condition is that the heat generated by the first switching module is less than the maximum heat generated that the first switching module can tolerate when the load is short-circuited.

5. The control circuit according to any one of claims 1 to 4, characterized in that, The control circuit further includes a drive module, wherein: The drive module is connected to the third terminal of the switch module; The driving module is used to control the first switch module to turn on based on the received shutdown command.

6. The control circuit according to claim 5, characterized in that, The control circuit also includes a unidirectional conduction module, wherein: The first end of the unidirectional conduction module is connected to the third end of the discharge switch, and the second end of the unidirectional conduction module is connected to the drive module; the current direction of the unidirectional conduction module is: from the second end of the unidirectional conduction module to the first end of the unidirectional conduction module; The driving module is used to stop outputting voltage or outputting a first preset voltage when receiving the shutdown command, so as to drive the first switching module to conduct.

7. The control circuit according to claim 6, characterized in that, The unidirectional conduction module includes a diode, the anode of which is connected to the drive module, and the cathode of which is connected to the third terminal of the discharge switch.

8. The control circuit according to claim 6, characterized in that, The first switching module includes a transistor, wherein: The first terminal of the transistor is connected to the third terminal of the discharge switch, the third terminal of the transistor is connected to the drive module, and the second terminal of the transistor is connected to the first terminal of the energy consumption module. The driving module is used to stop outputting voltage or outputting a first preset voltage when receiving the shutdown command, so that the voltage at the first terminal of the transistor is greater than the voltage at the third terminal of the transistor, thereby driving the first switching module to conduct.

9. The control circuit according to any one of claims 1 to 4, characterized in that, The energy consumption module includes a first resistor network, wherein: The first end of the first resistor network is connected to the second end of the first switch module, and the second end of the first resistor network is connected to the second end of the discharge switch.

10. The control circuit according to claim 6, characterized in that, The control circuit also includes: A first current limiting module, wherein a first end of the first current limiting module is connected to the driving module, and a second end of the first current limiting module is connected to the second end of the unidirectional conduction module.

11. The control circuit according to claim 10, characterized in that, The first current limiting module includes a second resistor network, a first end of which is connected to the driving module, and a second end of which is connected to the second end of the unidirectional conduction module.

12. The control circuit according to claim 6, characterized in that, The control circuit also includes a capacitor module, and the drive module includes a second switch module and a third resistor network. The first end of the driving module is connected to the first end of the second switch module and the second end of the unidirectional conduction module; the second end of the second switch module is connected to the first end of the third resistor network; and the second end of the driving module is connected to the second end of the third resistor network, the first end of the capacitor module, and the second end of the discharge switch. The second terminal of the capacitor module is connected to the negative terminal of the battery pack. The drive module is used to control the second switch module to turn on when it receives the shutdown command, and to control the first terminal of the drive module not to output voltage, so as to control the first switch module to turn on.

13. The control circuit according to claim 5, characterized in that, The drive module is also configured to output a drive voltage upon receiving an instruction to close the discharge switch, so that the difference between the voltage at the third terminal of the discharge switch and the voltage at the second terminal of the discharge MOSFE is greater than a preset threshold, thereby controlling the discharge switch to be turned on.

14. A control circuit, characterized in that, The control circuit includes a switch-off circuit, and the switch-off circuit includes: A discharge metal-oxide-semiconductor field-effect transistor (MOSFET) is wherein the drain of the discharge MOSFET is connected to the positive terminal of the battery pack, the source of the discharge MOSFET is connected to the first terminal of the load, and the second terminal of the load is connected to the negative terminal of the battery pack. A first switching module, wherein a first terminal of the first switching module is connected to the gate of the discharge MOSFET; An energy consumption module, wherein a first terminal of the energy consumption module is connected to a second terminal of the first switching module, and a second terminal of the energy consumption module is connected to the source of the discharge MOSFET; The first switching module is used to turn on according to the turn-off command, so that the parasitic capacitance of the discharge MOSFET, the first switching module and the energy consumption module form a discharge circuit of the parasitic capacitance, and turn off the discharge MOSFET when the voltage difference between the source and gate of the discharge MOSFET is less than a preset threshold; the turn-off command is the command to turn off the discharge MOSFET.

15. The control circuit according to claim 14, characterized in that, The switching off time of the discharge MOSFET is related to the on-resistance of the first switching module, the impedance of the energy consumption module, and the parasitic capacitance of the discharge MOSFET, and the sum of the on-resistance of the first switching module and the impedance of the energy consumption module satisfies a first preset condition.

16. The control circuit according to claim 15, characterized in that, The sum of the on-resistance of the first switching module and the impedance of the energy consumption module satisfies a first preset condition, including: the sum of the on-resistance of the first switching module and the impedance of the energy consumption module is less than a first preset resistance value. The first preset resistance value is determined based on the ratio of the maximum tolerable turn-off time of the discharge MOSFET when the load is short-circuited to the parasitic capacitance of the discharge MOSFET.

17. The control circuit according to claim 15, characterized in that, The impedance of the energy consumption module also meets the second preset condition; The second preset condition is that the heat generated by the first switching module is less than the maximum heat generated that the first switching module can tolerate when the load is short-circuited.

18. The control circuit according to any one of claims 14 to 17, characterized in that, The control circuit further includes a drive module, wherein: The drive module is connected to the third terminal of the switch module; The driving module is used to control the first switch module to turn on based on the received shutdown command.

19. The control circuit according to claim 18, characterized in that, The control circuit also includes a unidirectional conduction module, wherein: The first terminal of the unidirectional conduction module is connected to the gate of the discharge MOSFET, and the second terminal of the unidirectional conduction module is connected to the driving module; the current direction of the unidirectional conduction module is: from the second terminal of the unidirectional conduction module to the first terminal of the unidirectional conduction module; The driving module is used to stop outputting voltage or outputting a first preset voltage when receiving the shutdown command, so as to drive the first switching module to conduct.

20. The control circuit according to claim 19, characterized in that, The unidirectional conduction module includes a diode, the anode of which is connected to the driving module, and the cathode of which is connected to the gate of the discharge MOSFET.

21. The control circuit according to claim 19, characterized in that, The first switching module includes a transistor, wherein: The emitter of the transistor is connected to the gate of the discharge MOSFET, the base of the transistor is connected to the driving module, and the collector of the transistor is connected to the first terminal of the energy consumption module. The driving module is used to stop outputting voltage or outputting a first preset voltage when receiving the shutdown command, so that the voltage of the emitter of the transistor is greater than the voltage of the base of the transistor, so as to drive the first switching module to conduct.

22. The control circuit according to any one of claims 14 to 17, characterized in that, The energy consumption module includes a first resistor network, wherein: The first end of the first resistor network is connected to the second end of the first switching module, and the second end of the first resistor network is connected to the source of the discharge MOSFET.

23. The control circuit according to claim 19, characterized in that, The control circuit also includes: A first current limiting module, wherein a first end of the first current limiting module is connected to the driving module, and a second end of the first current limiting module is connected to the second end of the unidirectional conduction module.

24. The control circuit according to claim 23, characterized in that, The first current limiting module includes a second resistor network, a first end of which is connected to the driving module, and a second end of which is connected to the second end of the unidirectional conduction module.

25. The control circuit according to claim 19, characterized in that, The control circuit also includes a capacitor module, and the drive module includes a second switch module and a third resistor network. The first terminal of the driving module is connected to the first terminal of the second switching module and the second terminal of the unidirectional conduction module, respectively; the second terminal of the second switching module is connected to the first terminal of the third resistor network; and the second terminal of the driving module is connected to the second terminal of the third resistor network, the first terminal of the capacitor module, and the source of the discharge MOSFET, respectively. The second terminal of the capacitor module is connected to the negative terminal of the battery pack. The drive module is used to control the second switch module to turn on when it receives the shutdown command, and to control the first terminal of the drive module not to output voltage, so as to control the first switch module to turn on.

26. The control circuit according to claim 18, characterized in that, The driving module is further configured to output a driving voltage upon receiving an instruction to close the discharge MOSFET, such that the difference between the gate voltage of the discharge MOSFET and the source voltage of the discharge MOSFET is greater than a preset threshold, thereby controlling the discharge MOSFET to turn on.

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