Motor stalling protection method and circuit

Abstract

The invention provides a motor stalling protection method and circuit applied to a motor driving chip, the motor driving chip comprises a high-side switch QHA, a high-side switch QHB, a low-side switch QLA and a low-side switch QLB, the source electrode of the high-side switch QHA is connected with the drain electrode of the low-side switch QLA to serve as a first output pin OUTA of the motor driving chip, and the source electrode of the high-side switch QHA is connected with the drain electrode of the low-side switch QLB to serve as a second output pin OUTA of the motor driving chip. The source electrode of the high-side switch QHB and the drain electrode of the low-side switch QLB are connected to serve as a second output pin OUTB of the motor driving chip, and the source electrode of the low-side switch QLA and the source electrode of the low-side switch QLB are grounded; comprising the steps that when a motor enters a locked-rotor protection mode, a high-side switch QHA and a high-side switch QHB are controlled to be turned off, meanwhile, a low-side switch QLA is controlled to be turned on, because the voltage of a first output pin OUTA is equivalent to grounding when the low-side switch QLA is turned on, negative voltage does not exist, and compared with an existing chip'hard reactor ', the problem of logic disorder is reduced, and the chip technology is further simplified.

Description

Technical Field

[0001] The present invention relates to the technical field of motor protection, and particularly to a motor locked-rotor protection method and circuit. Background Art

[0002] During the test of the motor locked-rotor experiment, it is found that after the motor drive chip is protected, it conducts again, showing a situation of off-conduction-off oscillation. Due to continuous oscillation, the internal protection of the chip cannot be closed in time, which is likely to cause the chip to burn out. The schematic diagram of the current during the use of the motor is as Figure 1 shown in the red direction. When the locked-rotor protection is activated, the high-side switches QHA and QLA are turned off. At the moment of turning off, due to the inductive characteristic of the motor, the current will continuously flow from the OUTA terminal to the OUTB terminal. The current flows along Figure 1 the blue direction in the figure from QLA to QHB. Since QLA and QHB are turned off, the voltage of OUTA will be lower than GND by a PN junction voltage, that is, a negative PN junction voltage will appear at OUTA, about -0.6V. This negative voltage will cause the logic of the control circuit inside the chip to be chaotic, resulting in the power switch that was originally turned off to conduct again, which is likely to cause damage.

[0003] Currently, most chips let the chip "resist" the negative voltage "hard", so the chip process is relatively demanding. Summary of the Invention

[0004] The present invention provides a motor locked-rotor protection method and circuit to solve the defect that the locked-rotor protection in the prior art is prone to generate negative voltage, resulting in chaotic control circuits.

[0005] In a first aspect, the present invention provides a motor locked-rotor protection method applied to a motor drive chip. The motor drive chip includes a high-side switch QHA, a high-side switch QHB, a low-side switch QLA, and a low-side switch QLB. The source of the high-side switch QHA is connected to the drain of the low-side switch QLA as the first output pin OUTA of the motor drive chip. The source of the high-side switch QHB is connected to the drain of the low-side switch QLB as the second output pin OUTB of the motor drive chip. Both ends of the motor are respectively connected to the first output pin OUTA and the second output pin OUTB of the chip. The sources of the low-side switch QLA and the low-side switch QLB are grounded. The method includes:

[0006] When the motor enters the locked-rotor protection mode, control the high-side switch QHA and the high-side switch QHB to turn off, and at the same time control the low-side switch QLA to conduct, so as to control the first output pin OUTA to be grounded through the low-side switch QLA.

[0007] According to the motor locked-rotor protection method provided by the present invention, after controlling the low-side switch QLA to conduct, it further includes:

[0008] Control the low-side switch QLB to conduct, so as to control the second output pin OUTB to be grounded through the low-side switch QLB.

[0009] A motor stall protection method provided by the present invention, the motor drive chip includes a logic control unit, a comparator and a QLA control unit;

[0010] The control to turn on the low-side switch QLA includes:

[0011] When the voltage signal converted from the stall current is greater than the protection threshold voltage, the comparator outputs a low level;

[0012] Control the low-side switch QLA to conduct through the low level and the logic control unit together.

[0013] A motor stall protection method provided by the present invention, the motor drive chip further includes a QLB control unit;

[0014] After the control to turn on the low-side switch QLA, it further includes:

[0015] When the voltage signal converted from the stall current is greater than the protection threshold voltage, the comparator outputs a low level;

[0016] Control the low-side switch QLB to conduct through the low level and the logic control unit together.

[0017] A motor stall protection method provided by the present invention, the motor drive chip further includes: an AND gate;

[0018] The control to turn off the high-side switch QHA and the high-side switch QHB includes:

[0019] When the voltage signal converted from the stall current is greater than the protection threshold voltage, the comparator outputs a low level;

[0020] Control the high-side switch QHA and the high-side switch QHB to turn off through the low level and the AND gate together.

[0021] A motor stall protection method provided by the present invention further includes:

[0022] The control priority of the stall protection mode is higher than that of the normal working mode.

[0023] A motor stall protection method provided by the present invention further includes:

[0024] Sample the currents of the high-side switch QHA and the high-side switch QHB to obtain sampled currents;

[0025] When the sampled current is greater than a preset current, overcurrent limit is conducted. When it is detected that the chip temperature is greater than a preset temperature during overcurrent limit, overtemperature protection is conducted.

[0026] When overcurrent limit and overtemperature protection are triggered simultaneously, the motor is controlled to enter the stall protection mode.

[0027] In a second aspect, the present invention also provides a motor stall protection circuit, including: a control module and a drive module, the control module is connected to the drive module;

[0028] The drive module includes a high-side switch QHA, a high-side switch QHB, a low-side switch QLA, and a low-side switch QLB. The source of the high-side switch QHA is connected to the drain of the low-side switch QLA as the first output pin OUTA of the motor drive chip. The source of the high-side switch QHB and the drain of the low-side switch QLB are connected as the second output pin OUTB of the motor drive chip. Both ends of the motor are respectively connected to the first output pin OUTA and the second output pin OUTB of the chip. The sources of the low-side switch QLA and the low-side switch QLB are grounded;

[0029] When the motor enters the stall protection mode, the control module is used to control the high-side switch QHA and the high-side switch QHB to turn off, and control the low-side switch QLA and the low-side switch QLB to turn on.

[0030] According to a motor stall protection circuit provided by the present invention, the control module includes: a logic control unit, a comparison unit, and a logic gate circuit;

[0031] Both the logic control unit and the comparison unit are connected to the drive module through the logic gate circuit;

[0032] The logic control unit and the comparison unit are used as inputs of the logic gate circuit to control the conduction or turn-off of the high-side switch QHA, the high-side switch QHB, the low-side switch QLA, and the low-side switch QLB.

[0033] According to a motor stall protection circuit provided by the present invention, the logic gate circuit includes: a first AND gate, a second AND gate, a first NOT gate, a second NOT gate, a first XOR gate, and a second XOR gate;

[0034] The input ends of the first AND gate and the second AND gate are respectively connected to the comparison unit and the logic control unit. The output end of the first AND gate is used to control the turn-off or conduction of the high-side switch QHA. The output end of the second AND gate is used to control the turn-off or conduction of the high-side switch QHB;

[0035] The input terminals of the first NOT gate and the second NOT gate are both connected to the output terminal of the comparison unit. The output terminal of the first NOT gate and the logic control unit are both connected to the input terminal of the first XOR gate. The output terminal of the second NOT gate and the logic control unit are both connected to the input terminal of the second XOR gate. The output terminal of the first XOR gate is used to control the conduction or cut-off of the low-side switch QLA, and the output terminal of the second XOR gate is used to control the conduction or cut-off of the low-side switch QLB.

[0036] The motor stall protection method and circuit provided by the present invention are applied to a motor drive chip. The motor drive chip includes a high-side switch QHA, a high-side switch QHB, a low-side switch QLA, and a low-side switch QLB. The high-side switch QHA and the low-side switch QLA are connected to the first output pin OUTA, the high-side switch QHB and the low-side switch QLB are connected to the second output pin OUTB, the first output pin OUTA is connected to the second output pin OUTB, and the low-side switch QLA and the low-side switch QLB are grounded. The method includes: when the motor enters the stall protection mode, controlling the high-side switch QHA and the high-side switch QHB to turn off, and at the same time controlling the low-side switch QLA to conduct, so as to control the first output pin OUTA to be grounded through the low-side switch QLA. Since the voltage of the first output pin OUTA is equivalent to ground when the low-side switch QLA conducts, there will be no negative voltage. Compared with the existing chips "resisting hard", the problem of damage or logic confusion caused by negative voltage on the chip pins is reduced, and the chip process can be further streamlined. Description of the Drawings

[0037] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0038] Figure 1 is a schematic diagram of the current flow direction during motor stall protection in the prior art;

[0039] Figure 2 is a schematic diagram of the principle of the current flow direction during motor stall protection provided in this embodiment;

[0040] Figure 3 is a schematic diagram of the logic control principle of the motor drive chip provided in this embodiment;

[0041] Figure 4 is a schematic diagram of the motor stall protection process provided in this embodiment;

[0042] Figure 5It is a schematic diagram of the currents of the first output pin OUTA and the second output pin OUTB during locked-rotor protection in the prior art;

[0043] Figure 6 It is a schematic diagram of the currents of the first output pin OUTA and the second output pin OUTB when locked-rotor protection occurs by sampling the method of the present invention. Specific embodiments

[0044] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without any creative efforts shall fall within the protection scope of the present invention.

[0045] The present invention is a brush motor drive chip. VCC is the power supply pin of the chip, GNDA is the source pin of the low-side switch on the A side, GNDB is the source pin of the low-side switch on the B side, INA is the clockwise input pin, INB is the counterclockwise input pin, CS is the load current detection pin, SEL0 is the diagnostic control pin, and further includes a PWM pin. OUTA is the source / drain pin of the high-side switch on the A side / low-side switch, and OUTB is the source / drain pin of the high-side switch on the B side / low-side switch. Among them, INA and INB can be directly interfaced with a microcontroller to adjust the rotation direction and braking state of the motor. The SEL0 pin can transmit the collected current detection information to the processor through a truth table in combination with the signal states of INA and INB. The PWM signal can control the rotation speed of the motor.

[0046] Figure 2 It is a schematic diagram of the principle of current flow during locked-rotor protection of the motor provided in this embodiment.

[0047] Such as Figure 2As shown in the figure, a motor stall protection method provided by an embodiment of the present invention is applied to a motor drive chip. The motor drive chip includes a high-side switch QHA, a high-side switch QHB, a low-side switch QLA, and a low-side switch QLB. The source of the high-side switch QHA is connected to the drain of the low-side switch QLA as the first output pin OUTA of the motor drive chip. The source of the high-side switch QHB and the drain of the low-side switch QLB are connected as the second output pin OUTB of the motor drive chip. Both ends of the motor are respectively connected to the first output pin OUTA and the second output pin OUTB of the chip. The sources of the low-side switch QLA and the low-side switch QLB are both grounded. Among them, QHA, QHB, QLA, and QLB in the high-side switch QHA, the high-side switch QHB, the low-side switch QLA, and the low-side switch QLB do not have any limiting effect, and are only for matching with the attached drawings to more clearly describe the working principle and process.

[0048] The method mainly includes the following steps:

[0049] When the motor enters the stall protection mode, control the high-side switch QHA and the high-side switch QHB to turn off, and at the same time control the low-side switch QLA to conduct, so as to control the first output pin OUTA to be grounded through the low-side switch QLA. The logic control unit is connected to the gates of the high-side switch and the low-side switch, and the high-side and low-side switches are turned on and off through the truth table. For example, when the INA input is high, the INB input is low, the SEL0 is high, and the PWM is high, the high-side current on the A side is monitored through the CS pin, and QHA conducts and QHB turns off.

[0050] Specifically, when the low-side switch QLA conducts, since the low-side switch QLA is grounded, the voltage of the first output pin OUTA is equal to GND, so there will be no negative voltage, and therefore, the internal control logic of the chip will not be confused due to the negative voltage.

[0051] Furthermore, in order to completely avoid risks, on the basis of turning on the low-side switch QLA, control the low-side switch QLB to conduct, so as to control the second output pin OUTB to be grounded through the low-side switch QLB, so that the current direction is as Figure 2 shown by the blue arrow. Based on the inductance characteristics of the motor, the current flowing through the motor will not suddenly disappear, and still discharges according to the original current direction. The energy stored in the motor will be released as soon as possible, and there will be no negative voltage on both the first output pin OUTA and the second output pin OUTB, completely avoiding the risks.

[0052] Figure 3 is the logic control schematic diagram of the motor drive chip provided in this embodiment.

[0053] As Figure 3As shown in the figure, in this embodiment, the conduction and shutdown control of the high-side switch QHA, high-side switch QHB, low-side switch QLA, and low-side switch QLB are described in detail as follows:

[0054] The motor drive chip includes a logic control unit, a comparator, a QLA control unit, a QLB control unit, an AND gate U1, and an AND gate U2; the QLA control unit includes a NOT gate U4 and an XOR gate U5, and the QLB control unit includes a NOT gate U6 and an XOR gate U7.

[0055] The original control logic of QHA is connected to the first input terminal of the AND gate U1, the output terminal of the comparator U3 is connected to the second input terminal of the AND gate U1. The comparator U3 is used to compare the Vx voltage with the reference voltage Vth. The output terminal of U1 is connected to the gate of the high-side switch QHA. The GHA signal is used to control the conduction and shutdown of the high-side switch QHA.

[0056] The original control logic of QHB is connected to the first input terminal of the AND gate U2, the output terminal of the comparator U3 is connected to the second input terminal of the AND gate U2. The output terminal of U2 is connected to the gate of the high-side switch QHB. The GHB signal is used to control the conduction and shutdown of the high-side switch QHB.

[0057] The original control logic of QLA is connected to the second input terminal of the XOR gate U5. The output terminal of the comparator U3 is connected to the input terminal of the NOT gate U4, and the output terminal of the NOT gate U4 is connected to the first input terminal of the XOR gate U5. The output terminal of U5 is connected to the gate of the low-side switch QLA. The GLA signal is used to control the conduction and shutdown of the low-side switch QLA.

[0058] The original control logic of QLB is connected to the second input terminal of the XOR gate U7. The output terminal of the comparator U3 is connected to the input terminal of the NOT gate U6, and the output terminal of the NOT gate U6 is connected to the first input terminal of the XOR gate U7. The output terminal of U5 is connected to the gate of the low-side switch QLB. The GLB signal is used to control the conduction and shutdown of the low-side switch QLB.

[0059] The specific working principle is as follows:

[0060] Vx is the voltage signal converted from the locked-rotor current I after the motor is locked. Vth is the protection threshold voltage set inside the chip. When Vx≥Vth, that is, when entering the locked-rotor protection mode, the output of the comparator U3 is at a low level, and the outputs of GHA and GHB are both at a low level. The high-side switches QHA and QHB are turned off. At this time, the outputs of the NOT gates U4 and U6 are at a high level, and the outputs of the XOR gates U5 and U7 are both at a high level. The low-side switches QLA and QLB are turned on, and the current flows from QLA to QLB. The energy stored in the motor will be released as soon as possible, and no negative voltage will appear at the first output pin OUTA and the second output pin OUTB, completely avoiding the risk.

[0061] When Vx < Vth, the output of U3 is high level, and the outputs of NOT gates U4 and U6 are both low level: At this time, the high or low levels of GHA and GHB depend on the original control logic of high-side switch QHA and high-side switch QHB. When the control logic output of QHA is high level, GHA is high and high-side switch QHA conducts; when the control logic output of QHA is low level, GHA is low and high-side switch QHA turns off. Similarly, the high or low levels of GLA and GLB depend on the original control logic of low-side switch QLA and low-side switch QLB. When the original control logic output of QLA is high level, GLA is high and low-side switch QLA conducts; when the original control logic output of QLA is low level, GLA is low and low-side switch QLA turns off.

[0062] Therefore, the on and off control of high-side switch QHA, high-side switch QHB, low-side switch QLA, and low-side switch QLB is efficiently achieved. Moreover, to ensure the control effect, the control priority of the stall protection mode is higher than that of the normal working mode. That is, when entering the stall mode, regardless of the current working mode, directly control high-side switch QHA and high-side switch QHB to turn off, and at the same time control low-side switch QLA and low-side switch QLA to conduct, so as to protect the chip in a timely manner.

[0063] Furthermore, based on the above embodiments, the motor stall protection method in this embodiment further includes determining whether to enter the stall protection mode;

[0064] Specifically, as Figure 4 shown, it is a schematic diagram of the stall protection process. Sample the currents of high-side switch QHA and high-side switch QHB to obtain the sampled currents. Select the detection according to the motor working state. When the INA signal output by the single-chip microcomputer MCU is high, detect the current of QHA; when the INB signal output by the single-chip microcomputer MCU is high, detect the current of QHB.

[0065] The sampled current is calculated to obtain Vx, and compared with the internally preset current threshold Vth. When the sampled current is greater than the preset current, current limiting is conducted. When current limiting occurs, the power consumption of high-side switch QHA / QHB will increase, and the heat generation will rise rapidly, resulting in an increase in the chip temperature. When it is detected that the chip temperature is greater than the preset temperature, over-temperature protection is conducted. When the chip temperature is too high, the drive circuit will be turned off to protect the circuit.

[0066] When over-current limiting and over-temperature protection are triggered simultaneously, the motor is controlled to enter the stall protection mode. When over-current occurs, the current of the motor will be limited to prevent the circuit from short-circuiting. After the stall protection mode is triggered, the chip will mask the normal working logic, forcefully turn off high-side switch QHA and high-side switch QHB, and conduct low-side switch QLA and low-side switch QLB. During normal operation, QHA / QHB / QLA / QLB control the motor to rotate forward or reverse according to the preset control logic.

[0067] Based on the same general inventive concept, the present invention also protects a motor locked-rotor protection circuit for implementing the motor locked-rotor protection method of any of the above embodiments, as Figure 3 shown, the circuit includes: a control module and a drive module, and the control module is connected to the drive module;

[0068] The drive module includes a high-side switch QHA, a high-side switch QHB, a low-side switch QLA, and a low-side switch QLB. The high-side switch QHA and the low-side switch QLA are connected to a first output pin OUTA, the high-side switch QHB and the low-side switch QLB are connected to a second output pin OUTB, the first output pin OUTA is connected to the second output pin OUTB, and the low-side switch QLA and the low-side switch QLB are grounded;

[0069] When the motor enters the locked-rotor protection mode, the control module is used to control the high-side switch QHA and the high-side switch QHB to turn off, and control the low-side switch QLA and the low-side switch QLB to turn on.

[0070] Further, the control module includes: a logic control unit, a comparison unit, and a logic gate circuit; both the logic control unit and the comparison unit are connected to the drive module through the logic gate circuit; the logic control unit and the comparison unit are used as inputs of the logic gate circuit to control the conduction or turn-off of the high-side switch QHA, the high-side switch QHB, the low-side switch QLA, and the low-side switch QLB.

[0071] The logic gate circuit includes: a first AND gate U1, a second AND gate U2, a first NOT gate U4, a second NOT gate U6, a first XOR gate U5, and a second XOR gate U7;

[0072] The input ends of the first AND gate U1 and the second AND gate U2 are respectively connected to the comparison unit U3 and the logic control unit. The output end of the first AND gate U1 is used to control the turn-off or conduction of the high-side switch QHA, and the output end of the second AND gate U2 is used to control the turn-off or conduction of the high-side switch QHB;

[0073] The input ends of the first NOT gate U4 and the second NOT gate U6 are both connected to the output end of the comparison unit U3. The output end of the first NOT gate U4 and the logic control unit are both connected to the input end of the first XOR gate U5. The output end of the second NOT gate U5 and the logic control unit are both connected to the input end of the second XOR gate U7. The output end of the first XOR gate U5 is used to control the conduction or turn-off of the low-side switch QLA, and the output end of the second XOR gate U7 is used to control the conduction or turn-off of the low-side switch QLB.

[0074] Among them, the working principle of the circuit part is understood with reference to the method embodiment, and no further explanation will be given one by one.

[0075] Figure 5It is a schematic diagram of the currents of the first output pin OUTA and the second output pin OUTB during locked-rotor protection in the prior art. Figure 6 It is a schematic diagram of the currents of the first output pin OUTA and the second output pin OUTB when locked-rotor protection occurs by adopting the method of the present invention.

[0076] As Figure 5 and Figure 6 shown, the yellow curve of the first channel CH1 is the voltage at the first output pin OUTA, the green curve of the second channel CH2 is the VCC current, and the purple curve of the third channel CH3 is the voltage at the second output pin OUTB. At time t1, the electrode experiences locked-rotor, and a large current flows through. At time t2, locked-rotor protection is triggered. Due to the inductive characteristics of the motor, in the prior art, a negative voltage will appear at the first output pin OUTA (CH1) at time t2, and the reverse-biased PN junction will conduct, causing the chip to conduct again. After conduction, protection is triggered again, that is, oscillations are generated by repeated switching between t2 and t3. Due to the failure to protect in a timely manner, the chip is directly damaged after time t3. Figure 5 The corresponding times of the three red lines in Figure 6 are t1, t2, t3 in sequence. Figure 6 The corresponding times of the two red lines in

[0077] It can be seen that the advantage of adopting this patent is that after time t2, the first output pin OUTA and the second output pin OUTB ports quickly return to zero, solving the problem of negative voltage appearing at the first output pin OUTA and the second output pin OUTB after locked-rotor. At time t2, the voltage immediately drops to zero, there is no negative voltage and no oscillation, fundamentally solving the negative voltage problem. Therefore, under the same manufacturing process, the method of the present invention effectively improves the service life of the chip.

[0078] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on such an understanding, the essence of the above technical solution, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of each embodiment of the present invention.

Claims

1. A motor stall protection method, characterized in that: The invention is applied to a motor driving chip, wherein the motor driving chip comprises a high-side switch QHA, a high-side switch QHB, a low-side switch QLA and a low-side switch QLB, wherein the source of the high-side switch QHA is connected to the drain of the low-side switch QLA as a first output pin OUTA of the motor driving chip, the source of the high-side switch QHB is connected to the drain of the low-side switch QLB as a second output pin OUTB of the motor driving chip, the two ends of the motor are respectively connected to the first output pin OUTA and the second output pin OUTB of the chip, and the source of the low-side switch QLA and the source of the low-side switch QLB are grounded; the method comprises: When the motor enters the stall protection mode, the high-side switch QHA and the high-side switch QHB are controlled to be turned off, and the low-side switch QLA is controlled to be turned on, so as to control the first output pin OUTA to be grounded through the low-side switch QLA to prevent negative voltage from being generated at the first output pin OUTA.

2. The motor stall protection method according to claim 1, characterized in that: After controlling the low-side switch QLA to be turned on, the method further includes: The low-side switch QLB is controlled to be turned on, so as to control the second output pin OUTB to be grounded through the low-side switch QLB.

3. The motor stall protection method according to claim 1, characterized in that: The motor drive chip includes a logic control unit, a comparator and a QLA control unit; The controlling the low-side switch QLA to be turned on comprises: When the voltage signal converted by the locked-rotor current is greater than the protection threshold voltage, the comparator outputs a low level; The low-side switch QLA is controlled to be turned on by the low level and the logic control unit.

4. The motor stall protection method according to claim 3, characterized in that: The motor drive chip also includes a QLB control unit; After controlling the low-side switch QLA to be turned on, the method further includes: When the voltage signal converted by the locked-rotor current is greater than the protection threshold voltage, the comparator outputs a low level; The low-side switch QLB is controlled to be turned on by the low level and the logic control unit.

5. The motor stall protection method according to claim 3, characterized in that: The motor drive chip further includes: an AND gate; The controlling the high-side switch QHA and the high-side switch QHB to turn off includes: When the voltage signal converted by the locked-rotor current is greater than the protection threshold voltage, the comparator outputs a low level; The high-side switch QHA and the high-side switch QHB are controlled to be turned off through the low level and the AND gate.

6. The motor stall protection method according to claim 1, characterized in that: Also includes: The control priority of the stall protection mode is higher than that of the normal working mode.

7. The motor stall protection method according to claim 1, characterized in that: Also includes: Sampling the current of the high-side switch QHA and the high-side switch QHB to obtain a sampled current; When the sampled current is greater than the preset current, overcurrent limiting is initiated; when the chip temperature is detected to be greater than the preset temperature during overcurrent limiting, overtemperature protection is initiated; When the over-current limit and over-temperature protection are triggered at the same time, the motor is controlled to enter the stall protection mode.

8. A motor stall protection circuit, characterized in that: Used to execute the motor stall protection method according to any one of claims 1 to 6, the circuit comprises: a control module and a drive module, the control module is connected to the drive module; The driving module includes a high-side switch QHA, a high-side switch QHB, a low-side switch QLA and a low-side switch QLB, the source of the high-side switch QHA is connected to the drain of the low-side switch QLA as a first output pin OUTA of a motor driving chip, the source of the high-side switch QHB is connected to the drain of the low-side switch QLB as a second output pin OUTB of the motor driving chip, the two ends of the motor are respectively connected to the first output pin OUTA and the second output pin OUTB of the chip, and the source of the low-side switch QLA and the source of the low-side switch QLB are grounded; When the motor enters the stall protection mode, the control module is used to control the high-side switch QHA and the high-side switch QHB to be turned off, and control the low-side switch QLA and the low-side switch QLB to be turned on.

9. The motor stall protection circuit according to claim 8, characterized in that: The control module includes: a logic control unit, a comparison unit and a logic gate circuit; The logic control unit and the comparison unit are both connected to the driving module through the logic gate circuit; The logic control unit and the comparison unit are used as inputs of the logic gate circuit to control the on or off of the high-side switch QHA, the high-side switch QHB, the low-side switch QLA, and the low-side switch QLB.

10. The motor stall protection circuit according to claim 9, characterized in that: The logic gate circuit comprises: a first AND gate, a second AND gate, a first NOT gate, a second NOT gate, a first XOR gate and a second XOR gate; The input ends of the first AND gate and the second AND gate are connected to the comparison unit and the logic control unit respectively, the output end of the first AND gate is used to control the closing or conducting of the high-side switch QHA, and the output end of the second AND gate is used to control the closing or conducting of the high-side switch QHB; The input ends of the first NOT gate and the second NOT gate are both connected to the output end of the comparison unit, the output end of the first NOT gate and the logic control unit are both connected to the input end of the first XOR gate, the output end of the second NOT gate and the logic control unit are both connected to the input end of the second XOR gate, the output end of the first XOR gate is used to control the on or off of the low-side switch QLA, and the output end of the second XOR gate is used to control the on or off of the low-side switch QLB.

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