Method and apparatus for measuring rotational speed of motor, motor driving circuit, and air conditioner

Abstract

The present disclosure provides a method and apparatus for measuring a rotational speed of a motor, a motor driving circuit, and an air conditioner. The method comprises: in response to a motor stop instruction, controlling a target motor to decelerate to a setting value; adjusting a motor driving circuit and acquiring the maximum phase current value of the target motor; and on the basis of a pre-stored correspondence between rotational speeds and currents as well as the maximum phase current value, calculating the rotational speed of the target motor. According to the method provided by the present disclosure, the current rotational speed of a motor can be calculated on the basis of a sampled current of a brushless motor without adding a counter-electromotive force measurement circuit and other circuits, so as to complete sensorless control of the brushless motor. The present invention has the characteristics of high integration, compact structure and low cost.

Description

Motor speed detection method, device, motor drive circuit and air conditioner

[0001] This disclosure claims priority to a Chinese patent application filed with the Patent Office of China on June 28, 2023, with application number 202310780975.X and invention name “A motor speed detection method, device, motor drive circuit and air conditioner”, the entire contents of which are incorporated by reference into this disclosure. Technical Field

[0002] The present disclosure relates to the technical field of motor control, and in particular to a motor speed detection method and device, a motor drive circuit, and an air conditioner. Background Art

[0003] Brushless DC motors have superior performance and are therefore widely used in industries such as automotive, aviation, medical electronics, and industrial automation. They are also increasingly used in home appliances such as air conditioners, fans, hair dryers, washing machines, and vacuum cleaners.

[0004] However, for proper startup, many brushless DC motors require a position sensor to determine the rotor's relative position to the stator. This sensor, which can include a Hall effect sensor, measures the angle between the rotor's magnetic field and the stator's. This not only increases the cost and size of the brushless DC motor, but also potentially limits its application in harsh operating conditions such as high temperature, high humidity, and highly corrosive gases.

[0005] To further improve brushless DC motors, starting control of Hall-less brushless DC motors has become a research hotspot. In some motor control applications, such as air conditioner indoor units, the host computer needs to obtain motor speed information for subsequent logic control. This also poses new challenges for brushless motor systems that require no position sensor, or sensorless control. When the motor is running at low speeds, the sensorless control system has difficulty detecting the motor's operating angle and speed, making it difficult to achieve precise control of the brushless motor system. Existing sensorless brushless motors require a motor back-electromotive force (BEMF) circuit, which increases circuit cost and size, and is inconvenient to use.

[0006] Summary of the Invention

[0007] In order to solve the problem that the existing sensorless motor speed is difficult to accurately detect, the present invention provides a motor speed detection method, device, motor drive circuit and air conditioner, which can accurately calculate the motor speed without increasing the circuit structure and improve the reliability of control.

[0008] In one aspect, a method for detecting a motor speed is provided, the method comprising:

[0009] Respond to the motor stop command and control the target motor to decelerate and run to the set value;

[0010] Adjusting the motor drive circuit and obtaining the maximum phase current of the target motor;

[0011] The speed of the target motor is calculated based on the pre-stored corresponding relationship between the speed and the current and the maximum phase current.

[0012] In some embodiments, before responding to the motor stop instruction, the method further includes:

[0013] In response to a motor start instruction, an offset calibration is performed on the three-phase current sampling channel of the target motor, and the target motor is started to run.

[0014] In some embodiments, the motor drive circuit includes a three-phase half-bridge power circuit;

[0015] The adjustment motor drive circuit includes:

[0016] Turning off the driving signal of the first bridge arm of the three-phase half-bridge power circuit and controlling the second bridge arm of the three-phase half-bridge power circuit to be turned on according to the carrier frequency;

[0017] The duty cycle of the three-phase half-bridge power circuit is adjusted to be smaller than a pre-stored first threshold.

[0018] In some embodiments, the method further comprises:

[0019] The corresponding relationship between the rotational speed and the current is established based on the source motor and the target motor.

[0020] In some embodiments, establishing the corresponding relationship between the rotational speed and the current based on the source motor experimental platform and the target motor includes:

[0021] Controlling the source motor to drive the target motor to run at a preset test speed;

[0022] Obtaining the peak value of the phase current of the target motor at each test speed;

[0023] The corresponding relationship between the rotational speed and the current is established based on the phase current peak value of the test rotational speed.

[0024] In another aspect, a motor speed detection device is provided, the device comprising:

[0025] A stop command receiving module is configured to respond to a motor stop command and control the target motor to decelerate and run to a set value;

[0026] a drive circuit adjustment module, configured to adjust the motor drive circuit and obtain a maximum phase current of the target motor;

[0027] The motor speed calculation module is configured to calculate the speed of the target motor based on a pre-stored corresponding relationship between the speed and the current and the maximum phase current.

[0028] In some embodiments, the device further includes a motor start control module configured to respond to a motor start instruction before responding to a motor stop instruction, perform offset calibration on the three-phase current sampling channel of the target motor, and start the target motor.

[0029] In some embodiments, the motor drive circuit includes a three-phase half-bridge power circuit;

[0030] The driving circuit adjustment module is specifically configured to:

[0031] Turning off the driving signal of the first bridge arm of the three-phase half-bridge power circuit and controlling the second bridge arm of the three-phase half-bridge power circuit to be turned on according to the carrier frequency;

[0032] The duty cycle of the three-phase half-bridge power circuit is adjusted to be smaller than a pre-stored first threshold.

[0033] In some embodiments, the apparatus further includes a correspondence establishing module configured to:

[0034] The corresponding relationship between the rotational speed and the current is established based on the source motor and the target motor.

[0035] In some embodiments, the correspondence establishing module is specifically configured to:

[0036] Controlling the source motor to drive the target motor to run at a preset test speed;

[0037] Obtaining the peak value of the phase current of the target motor at each test speed;

[0038] The corresponding relationship between the rotational speed and the current is established based on the phase current peak value of the test rotational speed.

[0039] On the other hand, a computer device is provided, which includes a processor and a memory, wherein the memory stores at least one instruction, at least one program, code set or instruction set, and the processor can load and execute at least one instruction, at least one program, code set or instruction set to implement the motor speed detection method provided in the above-mentioned application embodiment.

[0040] On the other hand, a motor drive circuit is provided, characterized in that the motor drive circuit includes:

[0041] A main control chip, a driver chip, and a three-phase half-bridge power circuit; the main control chip includes the computer device described above;

[0042] The input end of the main control chip is connected to the host computer, and the output end of the main control chip is connected to the input end of the driver chip; the output end of the driver chip is connected to the input end of the three-phase half-bridge power circuit; and the output end of the three-phase half-bridge power circuit is connected to the target motor.

[0043] In another aspect, an air conditioner is provided, comprising a target motor and the motor driving circuit as described above.

[0044] On the other hand, a computer-readable storage medium is provided, in which at least one instruction, at least one program, code set or instruction set is stored. The processor can load and execute at least one instruction, at least one program, code set or instruction set to implement the motor speed detection method provided in the above-mentioned embodiment of the present disclosure.

[0045] In another aspect, a computer program product or computer program is provided. The computer program product or computer program includes computer program instructions stored in a computer-readable storage medium. A processor reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing a computer device to perform the motor speed detection method described in any of the above embodiments.

[0046] The technical solutions provided by the present disclosure provide at least the following beneficial effects: The embodiments of the present disclosure provide a motor speed detection method, device, motor drive circuit, and air conditioner, wherein the method comprises responding to a motor shutdown command to control a target motor to decelerate to a set value; adjusting the motor drive circuit and obtaining the maximum phase current of the target motor; and calculating the speed of the target motor based on a pre-stored speed-current correspondence and the maximum phase current. The method provided by the embodiments of the present disclosure can calculate the current speed of the motor using the sampled brushless motor current without adding a back electromotive force detection circuit or other circuits, thereby completing sensorless control of the brushless motor. The method has the characteristics of high integration, compact structure, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0048] FIG1 shows a schematic diagram of an implementation flow of a motor speed detection method provided by an exemplary embodiment of the present disclosure;

[0049] FIG2 shows a schematic structural diagram of an experimental device in a motor speed detection method provided by an exemplary embodiment of the present disclosure;

[0050] FIG3 shows a structural diagram of a motor speed detection device provided by an exemplary embodiment of the present disclosure;

[0051] FIG4 shows a schematic structural diagram of a computer device corresponding to a motor speed detection method provided by an exemplary embodiment of the present disclosure;

[0052] FIG5 shows a schematic structural diagram of a motor drive circuit provided by an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0053] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0054] The method provided by the present disclosure can accurately calculate the motor speed without increasing the circuit structure, thereby improving the reliability of control.

[0055] Example 1

[0056] The sensorless angle estimation or measurement of the brushless motor is mainly based on the ideal motor equation as a model. However, when the brushless motor is at low speed, the error of the ideal model is large, making it difficult to estimate the angle and speed of the brushless motor.

[0057] FIG1 shows a schematic diagram of an implementation flow of a motor speed detection method provided by an embodiment of the present disclosure.

[0058] 1 , the motor speed detection method provided by the embodiment of the present disclosure may include steps 101 to 103 .

[0059] Step 101: responding to the motor stop command, controlling the target motor to decelerate and run to a set value.

[0060] In some embodiments, the target motor comprises a sensorless brushless motor.

[0061] In some embodiments, the target motor includes an indoor motor of an air conditioner, ie, a fan.

[0062] In some embodiments, step 101 specifically includes: after receiving the shutdown command, the main control chip MCU controls the brushless motor to decelerate to the set value n1, and the brushless motor control algorithm stops running.

[0063] In some embodiments, before step 101 , the method includes responding to a motor start instruction, performing offset calibration on the three-phase current sampling channels of the target motor, and starting the target motor to operate.

[0064] Specifically, before the motor starts, the main control MCU calibrates and updates the offset of the ADC channel.

[0065] Step 102: Adjust the motor drive circuit and obtain the maximum phase current of the target motor.

[0066] In some embodiments, the motor drive circuit includes a three-phase half-bridge power circuit.

[0067] Step 102 includes: turning off the driving signal of the first bridge arm of the three-phase half-bridge power circuit, and controlling the second bridge arm of the three-phase half-bridge power circuit to be turned on according to the carrier frequency;

[0068] The duty cycle of the three-phase half-bridge power circuit is adjusted to be smaller than a pre-stored first threshold.

[0069] In some embodiments, the first bridge arm is an upper bridge arm, and the second bridge arm is a lower bridge arm.

[0070] The second bridge arm is opened according to the carrier frequency, including the lower bridge arm opening one or more phases according to the carrier frequency.

[0071] In a specific example, the value of the first threshold Y is between 0.04 and 0.1.

[0072] Step 103: Calculate the speed of the target motor based on the pre-stored corresponding relationship between the speed and the current and the maximum phase current.

[0073] The corresponding relationship between the speed and the current may include but is not limited to an NI fitting curve or an NI data table, that is, a speed-current fitting curve or data table.

[0074] Specifically, the maximum value Imax of the phase current is obtained by sampling and calculation, and Imax is input into the NI fitting curve or NI data table to calculate the current corresponding speed.

[0075] In some implementations, the main control chip MCU outputs the rotation speed to a corresponding host computer.

[0076] In some embodiments, the method further comprises:

[0077] The corresponding relationship between the rotational speed and the current is established based on the source motor and the target motor.

[0078] Specifically, after the motor is manufactured and installed in the air conditioner or other system, the motor is tested using a towing platform.

[0079] During the test, the source motor drives the fan. This method accurately measures the relationship between speed and current when the motor is not driven. The test involves setting the source motor to drive the motor under test at speeds of n1 / 1, n1 / 2, n1 / 3, n1 / 4, ..., n1 / m, and measuring the current data.

[0080] FIG2 shows a schematic structural diagram of a source motor and target motor experimental system provided by an embodiment of the present disclosure.

[0081] Referring to FIG2 , the source motor experimental platform is set to drive the motor under test to rotate.

[0082] In some embodiments, establishing the corresponding relationship between the rotational speed and the current based on the source motor experimental platform and the target motor includes:

[0083] Controlling the source motor to drive the target motor to run at a preset test speed;

[0084] Obtaining the peak value of the phase current of the target motor at each test speed;

[0085] The corresponding relationship between the rotational speed and the current is established based on the phase current peak value of the test rotational speed.

[0086] Specifically, use a source motor to drive the motor under test at speeds of n1 / 1, n1 / 2, n1 / 3, n1 / 4, ..., n1 / m, where n1 is the set value. During this time, the main MCU does not control the brushless motor, and the brushless motor operates in generator mode. Record the peak phase currents at each speed to plot an NI fit curve or NI data sheet.

[0087] The motor speed detection method provided by the disclosed embodiments can detect low-speed motor speed information, specifically the rotor position and magnetic field of a permanent magnet synchronous motor, achieving comparable performance to sensored control without increasing control costs. This solution can be used in the sensorless module of an air conditioner indoor unit, resolving the issue of the sensorless module failing to output the motor FG signal when operating at low speeds.

[0088] The method provided in the embodiment of the present disclosure can be applied to the fan of the indoor unit of the air conditioner to achieve sensorless control and drive of the fan.

[0089] Example 2

[0090] FIG3 shows a schematic structural diagram of a motor speed detection device provided by an embodiment of the present disclosure.

[0091] 3 , the motor speed detection device provided by the embodiment of the present disclosure includes:

[0092] The stop command receiving module 201 is configured to respond to the motor stop command and control the target motor to decelerate and run to a set value;

[0093] A drive circuit adjustment module 202 is configured to adjust the motor drive circuit and obtain a maximum phase current of the target motor;

[0094] The motor speed calculation module 203 is configured to calculate the speed of the target motor based on a pre-stored correspondence between the speed and the current and the maximum phase current.

[0095] In some embodiments, the device further includes a motor start control module configured to respond to a motor start instruction before responding to a motor stop instruction, perform offset calibration on the three-phase current sampling channel of the target motor, and start the target motor.

[0096] In some embodiments, the motor drive circuit includes a three-phase half-bridge power circuit;

[0097] The driving circuit adjustment module 202 is specifically configured to:

[0098] Turning off the driving signal of the first bridge arm of the three-phase half-bridge power circuit and controlling the second bridge arm of the three-phase half-bridge power circuit to be turned on according to the carrier frequency;

[0099] The duty cycle of the three-phase half-bridge power circuit is adjusted to be smaller than a pre-stored first threshold.

[0100] In some embodiments, the apparatus further includes a correspondence establishing module configured to:

[0101] The corresponding relationship between the rotational speed and the current is established based on the source motor and the target motor.

[0102] In some embodiments, the correspondence establishing module 203 is specifically configured to:

[0103] Controlling the source motor to drive the target motor to run at a preset test speed;

[0104] Obtaining the peak value of the phase current of the target motor at each test speed;

[0105] The corresponding relationship between the rotational speed and the current is established based on the phase current peak value of the test rotational speed.

[0106] To sum up, the device provided by the embodiment of the present disclosure can calculate the current speed of the motor by using the sampled brushless motor current without adding a back electromotive force detection circuit and other circuits, thereby completing the sensorless control of the brushless motor, and has the characteristics of high integration, compact structure and low cost.

[0107] Example 3:

[0108] FIG4 shows a schematic diagram of the structure of a computer device provided by an exemplary embodiment of the present disclosure, the computer device comprising:

[0109] The processor 301 includes one or more processing cores. The processor 301 executes various functional applications and data processing by running software programs and modules.

[0110] The receiver 302 and transmitter 303 can be implemented as a communication component, which can be a communication chip. In some embodiments, the communication component can include signal transmission functionality. That is, the transmitter 303 can be configured to transmit control signals to the image acquisition device and the scanning device, and the receiver 302 can be configured to receive corresponding feedback instructions.

[0111] The memory 304 is connected to the processor 301 via a bus 305 .

[0112] The memory 304 may be configured to store at least one instruction, and the processor 301 may be configured to execute the at least one instruction to implement steps 101 to 102 in the above-mentioned motor speed detection method embodiment.

[0113] Those skilled in the art will understand that Figure 4 is merely an example of a computer device and does not constitute a limitation on the computer device. The computer device may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the computer device may also include a network access device, etc.

[0114] The processor 301 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0115] The memory 304 may be an internal storage unit of the computer device, such as a hard disk or memory of the computer device. The memory 304 may also be an external storage device of the computer device, such as a plug-in hard disk equipped on the computer device, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. In some embodiments, the memory 304 may also include both an internal storage unit of the computer device and an external storage device. The memory 304 is configured to store the computer program and other programs and data required by the terminal device. The memory 304 may also be configured to temporarily store data that has been output or is to be output.

[0116] Example 4:

[0117] FIG5 shows a schematic structural diagram of a motor drive circuit provided by an embodiment of the present disclosure.

[0118] 5 , an embodiment of the present disclosure further provides a motor drive circuit, characterized in that the motor drive circuit includes:

[0119] A main control chip MCU, a driver chip HVIC and a three-phase half-bridge power circuit; the main control chip includes the computer device as described above;

[0120] The input end of the main control chip is connected to the host computer, and the output end of the main control chip is connected to the input end of the driver chip; the output end of the driver chip is connected to the input end of the three-phase half-bridge power circuit; and the output end of the three-phase half-bridge power circuit is connected to the target motor.

[0121] The main control chip (MCU) is the module's integrated processing unit, responsible for AD sampling, fault detection, algorithm execution, logic processing, and command interaction. The MCU outputs a speed output signal (FG) as a square wave whose frequency is an integer multiple of the motor's speed.

[0122] The driver chip HVIC is a driver IC that can drive power devices according to the low-voltage electrical signal logic of the MCU. It has high-voltage isolation function and driving capability, and converts the logic level output by the MCU into the driving level of the power device.

[0123] The three-phase half-bridge power circuit includes six power devices, which may be IGBT devices or MOS devices.

[0124] The main control MCU is equipped with VDD power supply, VSP / Duty speed command, CW / CCW steering command, FG speed output signal, SWD debugging port, Vdc bus voltage sampling signal, Iu+ / Iu- / Iv+ / Iv- / Iw+ / Iw- motor current sampling signal, Ibus+ bus current signal, Tx / Rx communication serial port and Uup / Udown / Vup / Vdown / Wup / Wdown drive signal ports.

[0125] The driver chip HVIC is equipped with a VCC power supply, a FO fault output, and six output ports. Each output port is connected to a power device to control the on and off of the power device.

[0126] Specifically, the main control MCU performs algorithm calculations by sampling the VDC voltage and the three-phase currents Iu, Iv, and Iw, that is, the three-phase currents of the motor, and issues drive pulse instructions to control the operation of the motor.

[0127] In some embodiments, the brushless appliance startup process is as follows.

[0128] The master MCU controls the brushless motor using a three-stage startup process, including positioning, open-loop operation, and closed-loop operation. During open-loop operation, the FG output speed information is determined by the master MCU. When the motor switches to closed-loop operation, the FG output speed information is derived by the master MCU using a sensorless control algorithm. This means that the real-time angle and speed of the brushless motor are determined based on sensorless angle estimation or observation. During this process, the master MCU obtains real-time speed information for the brushless motor and outputs the corresponding FG signal to the host computer.

[0129] In some embodiments, the shutdown process of the brushless motor is as follows.

[0130] When the intelligent sensorless module receives a shutdown command, the main MCU controls the brushless motor to decelerate. However, when the motor speed falls below the set value n1, the main MCU loses closed-loop control of the motor. The MCU then blocks the PWM signal output, causing the motor to transition from a motoring state to a generating state, effectively free-wheeling deceleration. During this phase, the main MCU cannot obtain FG information about the electrode speed. Without an FG signal being output to the host computer, the host computer will interpret the motor as shut down, leading to other control logic errors. For example, in an air conditioner indoor unit, the host computer panel may close the air damper when the FG signal is 0, while the fan motor is still running, causing wind noise and other issues.

[0131] Example 5

[0132] An embodiment of the present disclosure further provides an air conditioner, comprising a target motor and the motor driving circuit as described above.

[0133] Example 6

[0134] An embodiment of the present disclosure further provides a computer-readable storage medium, which stores at least one instruction, at least one program, a code set, or an instruction set, to be loaded and executed by a processor to implement the above-mentioned motor speed detection method.

[0135] In some embodiments, the computer-readable storage medium may include: a read-only memory (ROM), a random access memory (RAM), a solid-state drive (SSD), or an optical disk, etc. Among them, the random access memory may include a resistance random access memory (ReRAM) and a dynamic random access memory (DRAM).

[0136] Example 7

[0137] The present disclosure further provides a computer program product or computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computer device to perform the motor speed detection method described in any of the above embodiments.

[0138] The serial numbers of the above-mentioned embodiments of the present disclosure are for description only and do not represent the quality of the implementation.

[0139] Those skilled in the art will understand that all or part of the steps of implementing the above embodiments can be completed by hardware or by instructing the relevant hardware to complete the steps through a program. The program can be stored in a computer-readable storage medium, and the above-mentioned storage medium can be a read-only memory, a magnetic disk, or an optical disk. Those skilled in the art will clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example. In actual application, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into a single unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other and are not used to limit the scope of protection of this disclosure. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the above-mentioned method embodiment and will not be repeated here.

[0140] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0141] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this disclosure.

[0142] The computer program includes computer program code, which may be in source code form, object code form, executable file, or some intermediate form. The computer-readable medium may include any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a mobile hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electric carrier signal, a telecommunications signal, and a software distribution medium. It should be noted that the content of the computer-readable medium may be appropriately increased or decreased based on the requirements of legislation and patent practice within a jurisdiction. For example, in some jurisdictions, based on legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunications signals.

[0143] The embodiments described above are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present disclosure, and should all be included in the scope of protection of the present disclosure.

Claims

1. A method for detecting motor speed, the method comprising: Respond to the motor stop command and control the target motor to decelerate and run to the set value; Adjusting the motor drive circuit and obtaining the maximum phase current of the target motor; The speed of the target motor is calculated based on the pre-stored corresponding relationship between the speed and the current and the maximum phase current.

2. The method according to claim 1, wherein: Before responding to the motor stop instruction, the method further includes: In response to a motor start instruction, an offset calibration is performed on a three-phase current sampling channel of the target motor, and the target motor is started to run.

3. The method according to claim 1, wherein: The motor drive circuit includes a three-phase half-bridge power circuit; The adjusting motor driving circuit comprises: Turning off the driving signal of the first bridge arm of the three-phase half-bridge power circuit and controlling the second bridge arm of the three-phase half-bridge power circuit to be turned on according to the carrier frequency; The duty cycle of the three-phase half-bridge power circuit is adjusted to be smaller than a pre-stored first threshold.

4. The method according to any one of claims 1 to 3, wherein: The method further comprises: The corresponding relationship between the rotation speed and the current is established based on the source motor and the target motor.

5. The method according to claim 4, wherein: The establishing of the corresponding relationship between the rotation speed and the current based on the source motor experimental platform and the target motor includes: Control the source motor to drive the target motor to run at a preset test speed; Obtaining the phase current peak value of the target motor at each test speed; The corresponding relationship between the rotation speed and the current is established based on the phase current peak value of the test rotation speed.

6. A motor speed detection device, comprising: A stop command receiving module is configured to respond to a motor stop command and control the target motor to decelerate and run to a set value; A drive circuit adjustment module, configured to adjust the motor drive circuit and obtain a maximum phase current of the target motor; The motor speed calculation module is configured to calculate the speed of the target motor based on a pre-stored corresponding relationship between the speed and the current and the maximum value of the phase current.

7. A computer device, comprising a processor and a memory, wherein the memory stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, at least one program, a code set or an instruction set is loaded and executed by the processor to implement the motor speed detection method as described in any one of claims 1 to 5.

8. A motor drive circuit, comprising: A main control chip, a driver chip and a three-phase half-bridge power circuit; the main control chip includes the computer device as claimed in claim 7; The input end of the main control chip is connected to the host computer, and the output end of the main control chip is connected to the input end of the drive chip; the output end of the drive chip is connected to the input end of the three-phase half-bridge power circuit; and the output end of the three-phase half-bridge power circuit is connected to the target motor.

9. An air conditioner comprising a target motor and the motor driving circuit according to claim 8.

10. A computer-readable storage medium, wherein the computer-readable storage medium stores at least one instruction, at least one program, code set or instruction set, wherein the at least one instruction, at least one program, code set or instruction set is loaded and executed by a processor to implement the motor speed detection method as described in any one of claims 1 to 5.

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