Back electromotive force absorption protection circuit and electric control mainboard of motor

Abstract

The invention provides a target detection de-weight positioning method and system for a double-arm cooperation wheel-tracked robot, and relates to the technical field of motor back electromotive force protection, and a back electromotive force absorption protection circuit comprises an electromotive force absorption circuit, a switch element driving circuit and a comparator circuit; a first switch element in the switch element driving circuit is switched on when the back electromotive force is greater than or equal to a threshold value and a second switch element is switched on, and is switched off when the back electromotive force is smaller than a preset threshold value; the battery supplies power to the second switch element to conduct the second switch element; the comparator circuit turns off the second switching element when the counter electromotive force is greater than or equal to a preset threshold value, and further turns off the first switching element. When the motor generates the counter electromotive force, the voltage of the counter electromotive force can be rapidly compared, the voltage is turned off when the voltage exceeds the normal input voltage, under other conditions, battery absorption or resistance-capacitance discharge is carried out, the size is small, the generated heat is low, the response is rapid, and wide-range counter electromotive force absorption protection is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of motor back electromotive force protection, and more particularly, to a back electromotive force absorption protection circuit and an electronic control main board of a motor. Background Art

[0002] Currently, most rehabilitation medical products are powered by various types of motors. The composition of the motor has an electromagnetic effect, resulting in the generation of back electromotive force when the motor continues to rotate after power-off. For example, a smart wheelchair can still be pushed manually when powered off. The pushing will drive the motor to rotate, thus generating back electromotive force, which will affect components such as circuit boards, leading to problems such as overheating, mis-triggering, or damage.

[0003] Most of the existing solutions are to add a discharge resistor module. The working principle of the discharge resistor module is based on Ohm's law and the principle of capacitor discharge. It includes a capacitor and a discharge resistor. When the circuit is turned off, the charge on the capacitor gradually discharges through the discharge resistor.

[0004] If the resistance value is too large, the discharge time will be too long; if the resistance value is too small, a large power consumption will be generated during the discharge process, resulting in heat generation. Since the discharge resistor generates heat during operation, its heat dissipation requirements need to be met. Usually, appropriate packaging, installation methods, and adding heat sinks are used to improve the heat dissipation efficiency. There are disadvantages such as the large volume and high price of the discharge resistor module. Summary of the Invention

[0005] To solve the above problems, an embodiment of the present invention provides a back electromotive force absorption protection circuit, including an electromotive force absorption circuit, a switch element drive circuit, and a comparator circuit; the input end of the electromotive force absorption circuit is used to input the back electromotive force, and the output end is connected to the switch element drive circuit and the charging end of the battery; the switch element drive circuit includes a first switch element and a second switch element; the first switch element conducts when the back electromotive force is greater than or equal to a preset threshold and the second switch element is conducting, so that the back electromotive force enters the comparator circuit; the first switch element turns off when the back electromotive force is less than the preset threshold, so that the back electromotive force is absorbed by the electromotive force absorption circuit or charges the battery; the battery is connected to the control end of the second switch element to supply power to the second switch element to make it conduct; the comparator circuit is used to turn off the second switch element when the back electromotive force is greater than or equal to the preset threshold, and the second switch element turns off, thereby turning off the first switch element.

[0006] The back electromotive force absorption protection circuit provided by the embodiment of the present invention can quickly compare the voltage of the back electromotive force when the motor generates the back electromotive force. If it exceeds the normal input voltage, it will be turned off. In other cases, it is absorbed by the battery or discharged through a resistor-capacitor. It has a small volume, low heat generation, and rapid response, achieving a wide range of back electromotive force absorption protection.

[0007] Optionally, the first switching element is a MOS transistor, and the second switching element is a triode; the drain of the MOS transistor is connected to the back electromotive force, the source is connected to the comparator circuit, and the gate is connected to the collector of the second switching element; the emitter of the second switching element is grounded, and the base is connected to the discharge end of the battery and the control signal output end of the comparator circuit.

[0008] In the embodiment of the present invention, the on and off of the circuit are realized based on the first switching element and the second switching element, thereby dynamically changing the connection with the subsequent circuit.

[0009] Optionally, the switching element driving circuit further includes a first voltage dividing resistor and a second voltage dividing resistor; the first voltage dividing resistor and the second voltage dividing resistor are connected in series between the drain of the MOS transistor and the collector of the triode, and the gate of the MOS transistor is connected between the first voltage dividing resistor and the second voltage dividing resistor; the resistance values of the first voltage dividing resistor and the second voltage dividing resistor satisfy: when the back electromotive force is greater than or equal to a preset threshold, the first voltage dividing resistor and the second voltage dividing resistor divide the voltage to make the MOS transistor conduct.

[0010] In the embodiment of the present invention, the first voltage dividing resistor and the second voltage dividing resistor play a role in dividing the back electromotive force. By reasonably setting their resistance values, the MOS transistor can be made to conduct when the back electromotive force is greater than or equal to the preset threshold, so that the comparator circuit compares the back electromotive force. If it exceeds the normal input voltage, it will be turned off to prevent it from entering the subsequent circuit.

[0011] Optionally, the comparator circuit includes a comparator and a third switching element; the third switching element is a triode; the first input terminal of the comparator is connected to the source, the second input terminal is connected to a reference voltage, and the output terminal is connected to the base of the third switching element; the emitter of the third switching element is grounded, and the collector is connected to the base of the second switching element; the comparator is used to output a high-level signal when the back electromotive force is greater than or equal to the preset threshold, so that the third switching element conducts.

[0012] In the embodiment of the present invention, when the third switching element conducts, the base of the second switching element is grounded, thereby pulling down the base voltage of the second switching element and turning off the second switching element.

[0013] Optionally, the comparator circuit further includes a third voltage-dividing resistor and a fourth voltage-dividing resistor; the third voltage-dividing resistor and the fourth voltage-dividing resistor are connected in series between the source of the MOS transistor and the ground, and the first input terminal of the comparator is connected between the third voltage-dividing resistor and the fourth voltage-dividing resistor; the resistance values of the third voltage-dividing resistor and the fourth voltage-dividing resistor satisfy that when the back electromotive force is greater than or equal to a preset threshold, the third voltage-dividing resistor and the fourth voltage-dividing resistor divide the voltage so that the comparator outputs a high-level signal.

[0014] In the embodiment of the present invention, a voltage-dividing resistor is provided in the comparator circuit to play a role in dividing the back electromotive force.

[0015] Optionally, the electromotive force absorption circuit includes a diode, a discharge resistor, and a capacitor; the positive electrode of the diode is grounded, and the negative electrode is connected to the back electromotive force; the discharge resistor and the capacitor are connected in parallel between the back electromotive force and the ground.

[0016] In the embodiment of the present invention, the electromotive force absorption circuit discharges based on Ohm's law and the principle of capacitor discharge.

[0017] Optionally, the electromotive force absorption circuit further includes a protection resistor; the protection resistor is connected between the back electromotive force and the charging terminal of the battery.

[0018] In the embodiment of the present invention, the protection resistor is connected between the back electromotive force and the charging terminal of the battery to play a role in protecting the battery.

[0019] Optionally, it further includes a buck module; the input terminal of the buck module is connected to the source of the MOS transistor.

[0020] In the embodiment of the present invention, the circuit includes a buck module, which can achieve DC bucking.

[0021] Optionally, the electromotive force absorption circuit further includes a bucking resistor; the bucking resistor is connected between the discharging terminal of the battery and the base of the second switching element.

[0022] In the embodiment of the present invention, the bucking resistor is connected between the discharging terminal of the battery and the base of the second switching element, and can reduce the output voltage of the battery to a level suitable for not damaging the second switching element and keeping it conducting.

[0023] The embodiment of the present invention provides an electronic control main board for a motor, including the back electromotive force absorption and protection circuit described in any one of the above.

[0024] The electronic control main board for a motor provided by the embodiment of the present invention can achieve the same technical effects as the above back electromotive force absorption and protection circuit. Description of the Drawings

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to the provided drawings.

[0026] Figure 1 It is an exemplary circuit diagram of an electromotive force absorption protection circuit provided by an embodiment of the present invention. Specific embodiments

[0027] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following will specifically describe the embodiments of the present invention with reference to the drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] The solution proposed by the embodiment of the present invention effectively solves the above problems through components such as switching elements and comparators, and has the advantages of wide voltage absorption protection, small size, and low heat generation.

[0029] An embodiment of the present invention provides an electromotive force absorption protection circuit, which specifically includes an electromotive force absorption circuit, a switching element drive circuit, and a comparator circuit.

[0030] Among them, the input end of the electromotive force absorption circuit is used to input the back electromotive force, and the output end is connected to the switching element drive circuit and the charging end of the battery.

[0031] The function of the electromotive force absorption circuit is to discharge and consume the lower back electromotive force. Specifically, the back electromotive force lower than the battery charging voltage can be discharged through a resistor-capacitor. Since the voltage is small, the generated heat can be dissipated through the copper foil of the circuit board, etc. For the back electromotive force higher than the battery charging voltage and less than the high voltage threshold (for example, 24V), the battery can absorb it. For the back electromotive force exceeding the high voltage threshold, the switching element drive circuit performs a cut-off operation to avoid damaging the subsequent circuit.

[0032] The switching element drive circuit includes a first switching element and a second switching element. Among them, the first switching element conducts when the back electromotive force is greater than or equal to the preset threshold, so that the back electromotive force enters the comparator circuit; the first switching element turns off when the back electromotive force is less than the preset threshold, so that the back electromotive force is absorbed by the electromotive force absorption circuit or charges the battery. The battery is connected to the control end of the second switching element to supply power to the second switching element to make it conduct.

[0033] There are two switching elements in the switching element drive circuit. The first switching element is controlled by the back electromotive force and the second switching element. Specifically, the battery provides a high voltage to the control terminal of the second switching element to turn on the second switching element. After the second switching element is turned on, a path is formed between the back electromotive force and the ground. When the back electromotive force is greater than or equal to the preset threshold, the high voltage turns on the first switching element, and then the back electromotive force enters the subsequent comparator circuit through the first switching element. When the back electromotive force is less than the preset threshold, or when the second switching element is turned off, the first switching element is turned off, and the back electromotive force cannot enter the subsequent circuit, playing a protective role.

[0034] The comparator circuit is used to turn off the second switching element when the above-mentioned back electromotive force is greater than or equal to the preset threshold, and the second switching element is turned off and then the first switching element is turned off.

[0035] The function of the comparator circuit is to compare whether the back electromotive force is much greater than the above-mentioned preset threshold. If so, a high-level control signal is output from the comparator to another switching element, and the switching element is turned on to pull down the voltage at the control terminal of the second switching element, so that it is turned off. In this case, the path between the back electromotive force and the ground is disconnected, and the voltage at the control terminal of the first switching element is pulled down, so that it is also turned off, finally cutting off the connection between the back electromotive force and the subsequent circuit.

[0036] The back electromotive force absorption protection circuit provided by the embodiment of the present invention can quickly compare the voltage of the back electromotive force when the motor generates the back electromotive force. When it exceeds the normal input voltage, it is turned off. In other cases, it is absorbed by the battery or discharged through the resistor-capacitor. It has a small volume, low heat generation, and rapid response, realizing a wide range of back electromotive force absorption protection.

[0037] Optionally, the above-mentioned electromotive force absorption circuit includes a diode, a discharge resistor, and a capacitor. The positive electrode of the diode is grounded, and the negative electrode is connected to the back electromotive force; the discharge resistor and the capacitor are connected in parallel between the back electromotive force and the ground. The electromotive force absorption circuit discharges based on Ohm's law and the principle of capacitor discharge.

[0038] Among them, the electromotive force absorption circuit may further include a protection resistor. The protection resistor is connected between the back electromotive force and the charging terminal of the battery, playing a role in protecting the battery.

[0039] Among them, the electromotive force absorption circuit may further include a step-down resistor. The step-down resistor is connected between the discharge terminal of the battery and the base of the second switching element, reducing the output voltage of the battery to a level suitable for not damaging the second switching element and keeping it turned on.

[0040] Optionally, the above-mentioned back electromotive force absorption protection circuit may further include a step-down module. The input end of the step-down module is connected to the source electrode of the MOS transistor, and the high voltage in the circuit can be stepped down and output to the subsequent circuit.

[0041] Optionally, the first switching element is a MOS transistor (Metal-Oxide-Semiconductor Field-Effect Transistor), and the second switching element is a triode.

[0042] The drain of the MOS transistor is connected to the back electromotive force, the source is connected to the comparator circuit, and the gate is connected to the collector of the second switching element. The emitter of the second switching element is grounded, and the base is connected to the discharge terminal of the battery and the control signal output terminal of the comparator circuit.

[0043] Among them, the second switching element is controlled by the output voltage of the battery. When the output voltage of the battery satisfies the conduction voltage condition of the triode, the triode conducts, and then the gate of the MOS transistor is connected to the ground. The MOS transistor is controlled by the back electromotive force and conducts when the back electromotive force is greater than or equal to a preset threshold. It should be noted that once the triode is turned off, the MOS transistor will also be turned off.

[0044] Furthermore, the switching element driving circuit may further include a first voltage dividing resistor and a second voltage dividing resistor. The first voltage dividing resistor and the second voltage dividing resistor are connected in series between the drain of the MOS transistor and the collector of the triode, and the gate of the MOS transistor is connected between the first voltage dividing resistor and the second voltage dividing resistor. The resistance values of the first voltage dividing resistor and the second voltage dividing resistor satisfy: when the back electromotive force is greater than or equal to the preset threshold, the first voltage dividing resistor and the second voltage dividing resistor divide the voltage to make the MOS transistor conduct.

[0045] The first voltage dividing resistor and the second voltage dividing resistor play a role in dividing the back electromotive force. By reasonably setting their resistance values, the MOS transistor can be made to conduct when the back electromotive force is greater than or equal to the preset threshold, so that the comparator circuit compares the back electromotive force and turns off when it exceeds the normal input voltage to prevent it from entering the subsequent circuit.

[0046] Optionally, the comparator circuit includes a comparator and a third switching element. For example, the third switching element is a triode.

[0047] The first input terminal of the comparator can be connected to the source of the MOS transistor, the second input terminal is connected to the reference voltage, and the output terminal is connected to the base of the third switching element. The emitter of the third switching element is grounded, and the collector is connected to the base of the second switching element. The comparator is used to output a high-level signal when the back electromotive force is greater than or equal to the preset threshold to make the third switching element conduct.

[0048] When the third switching element conducts, the base of the second switching element is grounded, thereby pulling down the base voltage of the second switching element to turn off the second switching element.

[0049] Furthermore, the comparator circuit may further include a third voltage-dividing resistor and a fourth voltage-dividing resistor. The third voltage-dividing resistor and the fourth voltage-dividing resistor are connected in series between the source of the MOS transistor and the ground, and the first input terminal of the comparator is connected between the third voltage-dividing resistor and the fourth voltage-dividing resistor.

[0050] The resistance values of the third voltage-dividing resistor and the fourth voltage-dividing resistor satisfy that when the back electromotive force is greater than or equal to a preset threshold, the third voltage-dividing resistor and the fourth voltage-dividing resistor divide the voltage so that the comparator outputs a high-level signal.

[0051] A voltage-dividing resistor is provided in the comparator circuit to divide the back electromotive force. The divided voltage is adapted to the reference voltage of the comparator. When the back electromotive force is greater than or equal to the preset threshold, the divided voltage is greater than the reference voltage.

[0052] Figure 1 FIG. shows an exemplary circuit diagram of the back electromotive force absorption protection circuit provided by an embodiment of the present invention. The back electromotive force absorption protection circuit specifically includes an electromotive force absorption circuit, a MOS transistor driving circuit (i.e., the aforementioned switching element driving circuit), and a comparator circuit.

[0053] The electromotive force absorption circuit is composed of a diode D1, discharge resistors R1, R2, a capacitor C1, and a lithium battery module. The normal operating voltage of this circuit is 24V. When the system is powered off, the rotation of the motor will generate a back electromotive force that is poured in from IN, and the magnitude of the back electromotive force voltage is unknown. When the back electromotive force is less than 24V and less than the charging voltage of the lithium battery module, the back electromotive force is consumed through R1, C1, and D1. When the back electromotive force is less than 24V and greater than the charging voltage of the lithium battery module, the MOS transistor Q1 (i.e., the aforementioned first switching element) is not turned on, and the voltage is absorbed through the lithium battery module.

[0054] The MOS transistor driving circuit is composed of a MOS transistor Q1, a triode Q2 (i.e., the aforementioned second switching element), and resistors R3, R4, and R5. According to the property that the turn-on voltage Vth of the MOS transistor Q1 ≤ the gate-source voltage Vgs, Q1 is turned on when the input voltage is greater than 24V by dividing the voltage through R3 and R5. When Q1 is not turned on, the input voltage will first charge the lithium battery module. For a charged lithium battery, the output voltage is approximately equal to the charging voltage. When the charging stops, the output voltage is discharged by the lithium battery. The output voltage of the lithium battery causes Q2 to turn on through the resistor R4. At this time, the input voltage causes Q1 to turn on through R3 and R5, and the input voltage can pass through the MOS transistor to the next-level 24V-to-5V power supply module.

[0055] The function of Q2 is as follows: The discharge of the lithium battery causes Q2 to turn on, enabling R3 and R5 to divide the voltage, controlling the turn-on and turn-off of Q1; when the generated back electromotive force is greater than or equal to 24V and Q1 turns on, the comparator in the subsequent stage determines whether there is overvoltage. If it is greater than 24V, Q2 is turned off to protect the subsequent circuit from overvoltage damage.

[0056] The comparator circuit consists of resistors R6, R7, R8, comparator U1D, and triode Q3 (i.e., the above-mentioned third switching element). When the input voltage is greater than 24V, Q1 turns on and reaches the next stage. The voltage is divided by R6 and R7 and compared with 5V. When the input voltage is significantly greater than 24V, the divided voltage is greater than 5V. At this time, the comparator outputs a high level, and the base voltage of Q2 is pulled low through R8 and Q3. At this time, Q1 is turned off to achieve the protection of the next stage. Since the back electromotive force is not a DC constant voltage, when the back electromotive force is greater than 24V and Q1 is turned off, the generated back electromotive force will be absorbed by the lithium battery module, realizing the protection of the subsequent circuit.

[0057] When the hub motor generates a back electromotive force in the rehabilitation medical device according to the embodiment of the present invention, the above circuit can quickly compare the voltage of the back electromotive force. If it exceeds the normal input voltage, it is turned off. In other cases, it is absorbed by the lithium battery module. When it is lower than the lithium battery charging voltage, it is discharged through the resistor-capacitor, realizing wide-range back electromotive force absorption protection.

[0058] The original discharge resistor module charges and discharges through a large capacitor and a cement resistor, generating a large amount of heat and taking a long time. The embodiment of the present invention compares the high-voltage back electromotive force, blocks the influence on the subsequent circuit, absorbs the back electromotive force through the lithium battery, reduces the generation of heat, and is energy-efficient and environmentally friendly. The back electromotive force lower than the lithium battery charging voltage is discharged through the resistor-capacitor. Since the voltage is small, the generated heat can be dissipated through the copper foil of the circuit board. The advantages of the embodiment of the present invention are small volume, low heat generation, rapid response, and wide-voltage-range protection.

[0059] The embodiment of the present invention provides an electronic control main board for a motor, including the above-mentioned back electromotive force absorption protection circuit.

[0060] The electronic control main board of the motor in the embodiment of the present invention can achieve the same technical effects as the above-mentioned back electromotive force absorption protection circuit.

[0061] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope defined by the claims.

[0062] Finally, it should also be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising said element.

[0063] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other. For the system disclosed in the embodiments, since it corresponds to the method disclosed in the above embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description in the method section.

[0064] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electromotive force absorption protection circuit, characterized in that It includes an electromotive force absorption circuit, a switching element drive circuit, and a comparator circuit; The input terminal of the electromotive force absorption circuit is used to input the back electromotive force, and the output terminal is connected to the switching element drive circuit and the charging terminal of the battery; The switching element drive circuit includes a first switching element and a second switching element; The first switching element conducts when the back electromotive force is greater than or equal to a preset threshold and the second switching element is conducting, so that the back electromotive force enters the comparator circuit; The first switching element turns off when the back electromotive force is less than the preset threshold, so that the back electromotive force is absorbed by the electromotive force absorption circuit or the battery is charged; the battery is connected to the control terminal of the second switching element to supply power to the second switching element to make it conduct; The comparator circuit is used to turn off the second switching element when the back electromotive force is greater than or equal to the preset threshold, and the second switching element turns off and then the first switching element turns off.

2. The back electromotive force absorption protection circuit according to claim 1, wherein The first switching element is a MOS transistor, and the second switching element is a triode; The drain of the MOS transistor is connected to the back electromotive force, the source is connected to the comparator circuit, and the gate is connected to the collector of the second switching element; The emitter of the second switching element is grounded, and the base is connected to the discharge terminal of the battery and the control signal output terminal of the comparator circuit.

3. The back electromotive force absorption protection circuit according to claim 2, wherein The switching element drive circuit further includes a first voltage dividing resistor and a second voltage dividing resistor; The first voltage dividing resistor and the second voltage dividing resistor are connected in series between the drain of the MOS transistor and the collector of the triode, and the gate of the MOS transistor is connected between the first voltage dividing resistor and the second voltage dividing resistor; The resistance values of the first voltage dividing resistor and the second voltage dividing resistor satisfy that when the back electromotive force is greater than or equal to the preset threshold, the first voltage dividing resistor and the second voltage dividing resistor divide the voltage to make the MOS transistor conduct.

4. The back electromotive force absorption protection circuit according to claim 2, wherein The comparator circuit includes a comparator and a third switching element; the third switching element is a triode; The first input terminal of the comparator is connected to the source, the second input terminal is connected to the reference voltage, and the output terminal is connected to the base of the third switching element; The emitter of the third switching element is grounded, and the collector is connected to the base of the second switching element; The comparator is used to output a high-level signal when the back electromotive force is greater than or equal to the preset threshold, so that the third switching element conducts.

5. The back electromotive force absorption protection circuit according to claim 4, wherein The comparator circuit further includes a third voltage dividing resistor and a fourth voltage dividing resistor; The third voltage dividing resistor and the fourth voltage dividing resistor are connected in series between the source of the MOS transistor and the ground, and the first input terminal of the comparator is connected between the third voltage dividing resistor and the fourth voltage dividing resistor; The resistance values of the third voltage dividing resistor and the fourth voltage dividing resistor satisfy that when the back electromotive force is greater than or equal to the preset threshold, the third voltage dividing resistor and the fourth voltage dividing resistor divide the voltage to make the comparator output a high-level signal.

6. The back electromotive force absorption protection circuit according to claim 1, characterized in that, The electromotive force absorption circuit includes a diode, a discharge resistor, and a capacitor; The positive electrode of the diode is grounded, and the negative electrode is connected to the back electromotive force; The discharge resistor and the capacitor are connected in parallel between the back electromotive force and the ground.

7. The back electromotive force absorption protection circuit according to claim 6, characterized in that, The electromotive force absorption circuit further includes a protection resistor; The protection resistor is connected between the back electromotive force and the charging terminal of the battery.

8. The back electromotive force absorption protection circuit according to claim 2, characterized in that, A buck module is further included; The input end of the buck module is connected to the source electrode of the MOS transistor.

9. The back electromotive force absorption protection circuit according to claim 2, characterized in that, The electromotive force absorption circuit further includes a buck resistor; The buck resistor is connected between the discharge terminal of the battery and the base of the second switching element.

10. An electronic control main board of a motor, characterized in that, It includes the back electromotive force absorption and protection circuit according to any one of claims 1-9.

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