Sensorless speed and position detection method for electric lifting table

Abstract

The present invention discloses a sensorless speed and position detection method for an electric lifting table, which is used to detect the speed and position of the electric lifting table without using a sensor, and includes step S1: a speed curve generation module generates a reference speed when the electric lifting table is lifted or lowered according to demand, and transmits the reference speed to a speed control loop module, so that the motor located at the electric lifting table obtains the reference speed through the speed control loop module; step S2: a current ripple rotor position detection module detects the motor in real time and generates current data after processing the obtained motor current. The present invention discloses a sensorless speed and position detection method for an electric lifting table, which extracts the position information of the rotor of the motor through the dynamic current ripple when the motor is running, thereby obtaining higher detection accuracy of position and speed.

Description

Technical Field

[0001] The invention belongs to the technical field of electric lifting tables, and in particular relates to a sensorless speed position detection method for an electric lifting table. Background Art

[0002] The value of the lifting table is to help office workers say goodbye to long periods of sitting and achieve standing work. With the continuous development of the lifting table, the demand for the desktop position memory driven by the controller is increasing. The existing solution is to use an optical encoder or Hall effect sensor installed on the motor body to provide a feedback loop for the motor controller to identify speed and position. Adding a Hall sensor or optical encoder inside the motor greatly increases the complexity of the motor structure itself, while also increasing the failure rate, thereby increasing the overall cost of the system. In addition to economic factors, once the sensor fails, the entire lifting table drive part needs to be completely replaced, which increases the difficulty of product maintenance.

[0003] Therefore, further improvements are made to the above problems. Summary of the invention

[0004] The main purpose of the present invention is to provide a sensorless speed and position detection method for an electric lifting table, which extracts the position information of the motor's rotor through the dynamic current ripple when the motor is running, thereby obtaining higher position and speed detection accuracy.

[0005] Another object of the present invention is to provide a sensorless speed and position detection method for an electric lifting table. Due to cost and structural limitations, the existing conventional scheme generally only installs one Hall switch inside the motor, and the motor can only generate one pulse signal when it runs one circle. The present invention is based on the detection of current ripple, based on the motor commutator and the number of poles of the rotor coil, and can detect multiple position pulses when the motor rotates one circle, which greatly improves the accuracy of position and speed detection and achieves better control performance.

[0006] Another object of the present invention is to provide a sensorless speed position detection method for an electric lifting table, which simplifies the complexity of the motor structure design and reduces the motor cost. Since the installation structure of the Hall switch is eliminated, the internal space of the motor is simplified and the heat dissipation efficiency is improved; at the same time, the assembly process is also simplified, and the Hall switch assembly and testing links are eliminated.

[0007] Another object of the present invention is to provide a sensorless speed position detection method for an electric lifting table. The lifting table detection of the present invention adopts a speed closed-loop control scheme, which provides better speed response and operating performance compared to conventional open-loop control.

[0008] Another object of the present invention is to provide a sensorless speed and position detection method for an electric lifting table, which provides dynamic compensation control of the power supply voltage through the motor controller input. When the motor drive power supply voltage fluctuates, the PWM duty cycle is adjusted according to the compensation coefficient, which can effectively eliminate the speed changes caused by power supply fluctuations.

[0009] To achieve the above objectives, the present invention provides a sensorless speed and position detection method for an electric lift table, which is used to detect the speed and position of the electric lift table without using a sensor, and comprises the following steps:

[0010] Step S1: The speed curve generation module generates a reference speed when the electric lifting table is lifted or lowered according to the demand, and transmits the reference speed to the speed control loop module, so that the motor located at the electric lifting table obtains the reference speed through the speed control loop module;

[0011] Step S2: The current ripple rotor position detection module detects the motor in real time and generates current data after processing the obtained motor current, so as to extract the position of the motor rotor according to the dynamic current ripple when the motor is running. The speed position detection module generates a feedback speed after receiving the current data transmitted by the current ripple rotor position detection module and transmits the feedback speed to the speed control loop module, so that the motor located at the electric lifting table obtains the feedback speed through the speed control loop module;

[0012] Step S3: The speed control loop module processes (makes a difference) the obtained reference speed and feedback speed to generate drive data (pwm_duty) and transmits the drive data to the PWM drive module, so that the PWM drive module outputs a PWM drive waveform to the motor according to the given drive data, thereby enabling the electric lifting table to move to a preset position through the motor.

[0013] As a further preferred technical solution of the above technical solution, step S1 is specifically implemented as follows:

[0014] Step S1.1: The speed curve generation module generates a first reference speed when the electric lifting table is lifted or lowered according to demand, and transmits the first reference speed to the first speed control loop module, so that the first motor located at the electric lifting table obtains the first reference speed through the first speed control loop module;

[0015] Step S1.2: The speed curve generation module generates a second reference speed when the electric lifting table is raised or lowered according to demand, and transmits the second reference speed to the second speed control loop module, so that the second motor located on the electric lifting table obtains the second reference speed through the second speed control loop module.

[0016] As a further preferred technical solution of the above technical solution, step S2 is specifically implemented as the following steps:

[0017] Step S2.1: The first current ripple rotor position detection module connected to the first motor detects the first motor in real time and generates first current data after processing the obtained first motor current. The first speed position detection module generates a first feedback speed after receiving the first current data transmitted by the first current ripple rotor position detection module and transmits the first feedback speed to the first speed control loop module, so that the first motor located at the electric lifting table obtains the first feedback speed through the first speed control loop module;

[0018] Step S2.2: The second current ripple rotor position detection module connected to the second motor detects the second motor in real time and generates second current data after processing the obtained second motor current. The second speed position detection module generates a second feedback speed after receiving the second current data transmitted by the second current ripple rotor position detection module and transmits the second feedback speed to the second speed control loop module, so that the second motor located on the electric lifting table obtains the second feedback speed through the second speed control loop module.

[0019] As a further preferred technical solution of the above technical solution, step S3 is specifically implemented as the following steps:

[0020] Step S3.1: the first speed control loop module processes (makes a difference) the first reference speed and the first feedback speed to generate first drive data (pwm_duty) and transmits the first drive data to the first PWM drive module, so that the first PWM drive module outputs a PWM drive waveform to the first motor according to the given first drive data, thereby enabling the electric lifting table to move to a preset position through the first motor;

[0021] Step S3.2: The second speed control loop module processes (subtracts) the obtained second reference speed and the second feedback speed to generate second drive data (pwm_duty) and transmits the second drive data to the second PWM drive module, so that the second PWM drive module outputs a PWM drive waveform to the second motor according to the given second drive data, thereby enabling the electric lifting table to move to a preset position through the second motor.

[0022] As a further preferred technical solution of the above technical solution, in the process that the PWM drive module in step S3 outputs the PWM drive waveform (through the motor drive circuit) to the motor according to the given drive data, the voltage compensation module dynamically adjusts the duty cycle of the PWM drive according to the change of the voltage input at the input end of the motor (obtained by the current ripple rotor position detection module), and then adjusts the PWM drive waveform input to the motor to eliminate the speed fluctuation caused by the change of the power supply voltage.

[0023] As a further preferred technical solution of the above technical solution, in the process in which the speed control loop module in step S3 processes the obtained reference speed and feedback speed, the position deviation PI controller respectively receives the position feedback data about the first motor fed back by the first speed position detection module and the position feedback data about the second motor fed back by the second speed position detection module, thereby calculating the height difference generated by the first motor and the second motor on both sides of the electric lifting table, and then the position deviation PI controller adjusts the second reference speed related to the second motor to make the heights generated by the first motor and the second motor on both sides of the electric lifting table consistent.

[0024] As a further preferred technical solution of the above technical solution, step S3 further includes:

[0025] Step S4: the motor stall detection module obtains the motor current of the corresponding motor through the current ripple rotor position detection module, and determines whether the corresponding motor is stalled according to the motor current.

[0026] As a further preferred technical solution of the above technical solution, the current ripple rotor position detection module includes a current sensing amplifier circuit, a bandpass filter circuit, a differential amplifier circuit and a comparison circuit, the input end of the current sensing amplifier circuit inputs the sampling current of the motor and the output end of the current sensing amplifier circuit is electrically connected to the input end of the bandpass filter circuit, the output end of the bandpass filter circuit is electrically connected to the input end of the differential amplifier circuit and the differential amplifier circuit is electrically connected to the comparison circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is an overall schematic diagram of the sensorless speed position detection method for an electric lifting table of the present invention.

[0028] Figure 2 The present invention is a current sensing amplifier circuit diagram of a sensorless speed position detection method for an electric lifting table.

[0029] Figure 3 The present invention is a bandpass filter circuit diagram of a sensorless speed position detection method for an electric lifting table.

[0030] Figure 4 The invention discloses a differential amplifier circuit diagram of a sensorless speed position detection method for an electric lifting table.

[0031] Figure 5 It is a comparative circuit diagram of the sensorless speed position detection method for an electric lifting table of the present invention.

[0032] Figure 6 The present invention is a reference voltage circuit diagram of a sensorless speed position detection method for an electric lifting table.

[0033] Figure 7 It is a schematic diagram of the sensorless speed position detection method for an electric lifting table of the present invention.

[0034] The reference numerals include: 1. current sensing amplifier circuit; 2. bandpass filter circuit; 3. differential amplifier circuit; 4. comparison circuit. DETAILED DESCRIPTION

[0035] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0036] In the preferred embodiment of the present invention, those skilled in the art should note that the lifting table and motor involved in the present invention can be regarded as prior art.

[0037] Preferred embodiments.

[0038] The present invention discloses a sensorless speed and position detection method for an electric lifting table, which is used to detect the speed and position of the electric lifting table without using a sensor, and comprises the following steps:

[0039] Step S1: The speed curve generation module generates a reference speed when the electric lifting table is lifted or lowered according to the demand, and transmits the reference speed to the speed control loop module, so that the motor located at the electric lifting table obtains the reference speed through the speed control loop module;

[0040] Step S2: The current ripple rotor position detection module detects the motor in real time and generates current data after processing the obtained motor current, so as to extract the position of the motor rotor according to the dynamic current ripple when the motor is running. The speed position detection module generates a feedback speed after receiving the current data transmitted by the current ripple rotor position detection module and transmits the feedback speed to the speed control loop module, so that the motor located at the electric lifting table obtains the feedback speed through the speed control loop module;

[0041] Step S3: The speed control loop module processes (makes a difference) the obtained reference speed and feedback speed to generate drive data (pwm_duty) and transmits the drive data to the PWM drive module, so that the PWM drive module outputs a PWM drive waveform to the motor according to the given drive data, thereby enabling the electric lifting table to move to a preset position through the motor.

[0042] Specifically, step S1 is implemented as follows:

[0043] Step S1.1: The speed curve generation module generates a first reference speed when the electric lifting table is lifted or lowered according to demand, and transmits the first reference speed to the first speed control loop module, so that the first motor (Motor1) located at the electric lifting table obtains the first reference speed through the first speed control loop module;

[0044] Step S1.2: The speed curve generation module generates a second reference speed when the electric lifting table is raised or lowered according to demand, and transmits the second reference speed to the second speed control loop module, so that the second motor (Motor2) located on the electric lifting table obtains the second reference speed through the second speed control loop module.

[0045] More specifically, step S2 is implemented as follows:

[0046] Step S2.1: The first current ripple rotor position detection module connected to the first motor detects the first motor in real time and generates first current data after processing the obtained first motor current. The first speed position detection module generates a first feedback speed (speed feedback 1) after receiving the first current data transmitted by the first current ripple rotor position detection module and transmits the first feedback speed to the first speed control loop module, so that the first motor located at the electric lifting table obtains the first feedback speed through the first speed control loop module;

[0047] Step S2.2: The second current ripple rotor position detection module connected to the second motor detects the second motor in real time and generates second current data after processing the obtained second motor current. The second speed position detection module generates a second feedback speed (speed feedback 2) after receiving the second current data transmitted by the second current ripple rotor position detection module and transmits the second feedback speed to the second speed control loop module, so that the second motor located on the electric lifting table obtains the second feedback speed through the second speed control loop module.

[0048] Furthermore, step S3 is specifically implemented as the following steps:

[0049] Step S3.1: the first speed control loop module processes (makes a difference) the first reference speed and the first feedback speed to generate first drive data (pwm_duty) and transmits the first drive data to the first PWM drive module, so that the first PWM drive module outputs a PWM drive waveform to the first motor according to the given first drive data, thereby enabling the electric lifting table to move to a preset position through the first motor;

[0050] Step S3.2: The second speed control loop module processes (subtracts) the obtained second reference speed and the second feedback speed to generate second drive data (pwm_duty) and transmits the second drive data to the second PWM drive module, so that the second PWM drive module outputs a PWM drive waveform to the second motor according to the given second drive data, thereby enabling the electric lifting table to move to a preset position through the second motor.

[0051] Furthermore, in the process of the PWM drive module in step S3 outputting a PWM drive waveform (through a motor drive circuit) to the motor according to given drive data, the voltage compensation module dynamically adjusts the duty cycle of the PWM drive according to changes in the voltage input at the input end of the motor (obtained through the current ripple rotor position detection module), and then adjusts the PWM drive waveform input to the motor to eliminate speed fluctuations caused by changes in the power supply voltage.

[0052] Preferably, in the process of the speed control loop module in step S3 processing the obtained reference speed and feedback speed, the position deviation PI controller respectively receives the position feedback data about the first motor fed back by the first speed position detection module and the position feedback data about the second motor fed back by the second speed position detection module, thereby calculating the height difference generated by the first motor and the second motor on both sides of the electric lifting table, and then the position deviation PI controller adjusts the second reference speed related to the second motor so that the heights generated by the first motor and the second motor on both sides of the electric lifting table are consistent.

[0053] Preferably, after step S3, the following steps are further included:

[0054] Step S4: the motor stall detection module obtains the motor current of the corresponding motor through the current ripple rotor position detection module, and determines whether the corresponding motor is stalled according to the motor current (for detection of faults such as collision).

[0055] Preferably, the current ripple rotor position detection module includes a current sensing amplifier circuit, a bandpass filter circuit, a differential amplifier circuit and a comparison circuit, the input end of the current sensing amplifier circuit inputs the sampling current of the motor and the output end of the current sensing amplifier circuit is electrically connected to the input end of the bandpass filter circuit, the output end of the bandpass filter circuit is electrically connected to the input end of the differential amplifier circuit and the differential amplifier circuit is electrically connected to the comparison circuit.

[0056] The current sensing amplifier circuit includes a current sampling unit P1 and an amplifier U1A, and the output end of the current sampling unit P1 is electrically connected to the input end of the amplifier U1A;

[0057] The bandpass filter circuit includes a bandpass filter U1B, and the output end of the amplifier U1A is electrically connected to the negative input end of the bandpass filter U1B;

[0058] The differential amplifier circuit includes a differential amplifier U1C, and the output end of the bandpass filter U1B is electrically connected to the input end of the differential amplifier U1C;

[0059] The comparison circuit includes a comparator U2C, and the output end of the differential amplifier U1C is electrically connected to the input end of the comparator U2C.

[0060] Specifically, the pin 1 of the current sampling unit P1 is electrically connected to the positive input terminal of the amplifier U1A through the resistor R11 and the resistor R12 in sequence, and the pin 2 of the current sampling unit P1 is electrically connected to the negative input terminal of the amplifier U1A through the resistor R4 and the resistor R5 in sequence, and the common terminal of the resistor R4 and the resistor R5 is electrically connected to the common terminal of the resistor R11 and the resistor R12 through the capacitor C5;

[0061] A resistor R1 is connected between the negative input terminal and the output terminal of the amplifier U1A, and the output terminal of the amplifier U1A is grounded via a resistor R8 and a capacitor C6 in sequence.

[0062] More specifically, the negative input terminal of the bandpass filter U1B is electrically connected to the common terminal of the resistor R8 and the capacitor C6 through the resistor R7 and the capacitor C4 in sequence, and a resistor R2 is connected between the negative input terminal and the output terminal of the bandpass filter U1B, and the two ends of the resistor R2 are connected in parallel with the capacitor C1.

[0063] Furthermore, the negative input terminal of the differential amplifier U1C is electrically connected to the output terminal of the bandpass filter U1B through the resistor R6 and the positive input terminal of the differential amplifier U1C is electrically connected to the output terminal of the bandpass filter U1B through the resistor R10;

[0064] The positive input terminal of the differential amplifier U1C is also grounded through a capacitor C8 and a resistor R3 is connected between the negative input terminal and the output terminal of the differential amplifier U1C. The output terminal of the differential amplifier U1C is grounded through a resistor R9 and a capacitor C7 in turn.

[0065] Furthermore, the negative input terminal (pin 4) of the comparator U2C is electrically connected to the common terminal of the resistor R9 and the capacitor C7, a resistor R17 is connected between the positive input terminal and the output terminal of the comparator U2C, and the output terminal of the comparator U2C is grounded through the resistor R15 and the capacitor C9 in turn.

[0066] Preferably, the sensorless speed position detection circuit for the electric lifting table further comprises a reference voltage circuit, and the reference voltage circuit is electrically connected to the current sensing amplifier circuit, the bandpass filter circuit and the differential amplifier circuit respectively;

[0067] The reference voltage circuit includes a voltage reference unit U3 and an operational amplifier U1D. Pin 8 of the voltage reference unit U3 is electrically connected to the positive input terminal of the operational amplifier U1D, and the output terminal of the operational amplifier U1D outputs a reference voltage (REF_2.5V) through a resistor R19.

[0068] Preferably, the positive input terminal of the amplifier U1A inputs the reference voltage through a resistor R13, the positive input terminal of the bandpass filter U1B inputs the reference voltage, and the positive input terminal of the differential amplifier U1C inputs the reference voltage through a resistor R14.

[0069] The principle of the present invention is:

[0070] Sensorless motor control is a drive technology that does not rely on sensors to determine the actual motor position or speed. It determines the position of the motor based on electrical parameters such as back-electromagnetic field feedback or motor current feedback present when the motor is running. The current in the motor can be monitored by placing a current sensing resistor in series with the motor. The sensed current is converted to a measurable voltage by a current sensing amplifier across the resistor terminals as a position or speed feedback signal for closed-loop motor control. In this application, the periodic changes in the current feedback caused by the electromechanical structure of the motor can be observed. The displacement caused by the motor rotation can be determined by counting the number of these periodic changes during the operation of the motor.

[0071] For the brushed DC motor used in the present invention, the AC component current is generated by the rotation of the motor and the periodic changes in the motor coil impedance caused by the motor brushes shorting adjacent commutator poles. The amplitude and frequency of this component also vary due to the mechanical load on the motor and the design of the motor itself. This AC component contains ripple that should be measured and is proportional to the actual motor speed. Each ripple corresponds to a commutator pole rotation across the armature brushes. By knowing the total number of poles in the motor, it can be captured by total subdivision of one full rotation.

[0072] In order to effectively count and convert the current ripple into MCU-readable pulses, the current flowing through the motor needs to go through various signal conditioning and filtering stages. Each stage includes: current sensing amplifier circuit, bandpass filter circuit, differential amplifier circuit and comparison circuit.

[0073] Preferably, for the current sensing amplifier circuit: because the detection current is relatively small, a current amplifier circuit needs to be added. A simple common-mode RC input filter can be used at the input of the device to reduce the noise generated by the high-frequency motor brush and potential PWM switching noise.

[0074] Preferably, for the bandpass filtering circuit: the output of the current sensing amplifier is filtered with an active bandpass filter to observe the motor ripple signal and eliminate additional noise and DC component variance.

[0075] Preferably, for the differential amplifier circuit, the output of the active bandpass filter provides a clean amplified AC signal, but the initial current peak is not filtered out in the process. In addition, the high pass portion of the bandpass filter has been set to 100Hz in the previous stage. This configuration produces a rather large time constant that prohibits the DC signal component from settling quickly. Since the motor is already running and generating ripple, this causes the comparator to miss these startup ripples. Failure to detect and convert the startup ripple current into a comparator pulse will result in a missing pulse and an inaccurate ripple count. The problem with startup current ripple is solved by using a differential amplifier stage in the second signal conditioning stage. This low speed, high amplitude current spike is removed from the signal with the unique use of a differential amplifier stage. The output of the bandpass filter is used for the positive and negative inputs of the amplifier, but one side of the amplifier is filtered very lightly with a low pass RC filter. This small RC filter causes a very slight phase shift and attenuation of the ripple signal, but has little effect on the large DC offset spikes. The common mode remains essentially the same on both inputs and is negated by the amplifier. The phase and amplitude differences between the AC signals on the two inputs cause the differential output to retain the ripple frequency component.

[0076] Preferably, for the comparison circuit: the designed comparator stage generates the final 0-5V signal used by the microcontroller for counting. These output pulses are used as input to the counting algorithm of the firmware. When the input signal moves up and down beyond the threshold level, the comparator hysteresis circuit will generate corresponding high and low pulse signals. This can prevent the output pulse from oscillating and avoid switching noise caused by a small amount of parasitic feedback during level conversion.

[0077] It is worth mentioning that the technical features such as the lifting table and motor involved in the patent application of this invention should be regarded as the prior art. The specific structure, working principle and possible control method and spatial layout method of these technical features can be selected according to the conventional selection in the field, and should not be regarded as the inventive point of this patent. This patent will not be further elaborated.

[0078] For those skilled in the art, it is still possible to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A sensorless speed and position detection method for an electric lift table, which is used to detect the speed and position of the electric lift table without using a sensor, characterized in that: The following steps are involved: Step S1: The speed curve generation module generates a reference speed when the electric lifting table is lifted or lowered according to the demand, and transmits the reference speed to the speed control loop module, so that the motor located at the electric lifting table obtains the reference speed through the speed control loop module; Step S1 is specifically implemented as follows: Step S1.1: The speed curve generation module generates a first reference speed when the electric lifting table is lifted or lowered according to demand, and transmits the first reference speed to the first speed control loop module, so that the first motor located at the electric lifting table obtains the first reference speed through the first speed control loop module; Step S1.2: The speed curve generation module generates a second reference speed when the electric lifting table is lifted or lowered according to demand, and transmits the second reference speed to the second speed control loop module, so that the second motor located at the electric lifting table obtains the second reference speed through the second speed control loop module; Step S2: The current ripple rotor position detection module detects the motor in real time and generates current data after processing the obtained motor current, so as to extract the position of the motor rotor according to the dynamic current ripple when the motor is running. The speed position detection module generates a feedback speed after receiving the current data transmitted by the current ripple rotor position detection module and transmits the feedback speed to the speed control loop module, so that the motor located at the electric lifting table obtains the feedback speed through the speed control loop module; Step S3: the speed control loop module processes the obtained reference speed and feedback speed to generate driving data and transmits the driving data to the PWM driving module, so that the PWM driving module outputs a PWM driving waveform to the motor according to the given driving data, thereby enabling the electric lifting table to move to a preset position through the motor; Step S3 is specifically implemented as the following steps: Step S3.1: the first speed control loop module processes the obtained first reference speed and the first feedback speed to generate first drive data and transmits the first drive data to the first PWM drive module, so that the first PWM drive module outputs a PWM drive waveform to the first motor according to the given first drive data, thereby enabling the electric lifting table to move to a preset position through the first motor; Step S3.2: The second speed control loop module processes the obtained second reference speed and the second feedback speed to generate second drive data and transmits the second drive data to the second PWM drive module, so that the second PWM drive module outputs a PWM drive waveform to the second motor according to the given second drive data, thereby enabling the electric lifting table to move to a preset position through the second motor.

2. A sensorless speed position detection method for an electric lifting table according to claim 1, characterized in that: Step S2 is specifically implemented as follows: Step S2.1: The first current ripple rotor position detection module connected to the first motor detects the first motor in real time and generates first current data after processing the obtained first motor current. The first speed position detection module generates a first feedback speed after receiving the first current data transmitted by the first current ripple rotor position detection module and transmits the first feedback speed to the first speed control loop module, so that the first motor located at the electric lifting table obtains the first feedback speed through the first speed control loop module; Step S2.2: The second current ripple rotor position detection module connected to the second motor detects the second motor in real time and generates second current data after processing the obtained second motor current. The second speed position detection module generates a second feedback speed after receiving the second current data transmitted by the second current ripple rotor position detection module and transmits the second feedback speed to the second speed control loop module, so that the second motor located on the electric lifting table obtains the second feedback speed through the second speed control loop module.

3. A sensorless speed position detection method for an electric lifting table according to claim 2, characterized in that: In the process of the PWM driving module outputting the PWM driving waveform to the motor according to the given driving data in step S3, the voltage compensation module dynamically adjusts the duty cycle of the PWM driving according to the change of the voltage input at the input end of the motor, and then adjusts the PWM driving waveform input to the motor to eliminate the speed fluctuation caused by the change of the power supply voltage.

4. A sensorless speed position detection method for an electric lifting table according to claim 3, characterized in that: In the process of the speed control loop module in step S3 processing the obtained reference speed and feedback speed, the position deviation PI controller respectively receives the position feedback data about the first motor fed back by the first speed position detection module and the position feedback data about the second motor fed back by the second speed position detection module, so as to calculate the height difference generated by the first motor and the second motor on both sides of the electric lifting table, and then the position deviation PI controller adjusts the second reference speed related to the second motor so that the heights generated by the first motor and the second motor on both sides of the electric lifting table are consistent.

5. A sensorless speed position detection method for an electric lifting table according to claim 4, characterized in that: After step S3, the following steps are also included: Step S4: the motor stall detection module obtains the motor current of the corresponding motor through the current ripple rotor position detection module, and determines whether the corresponding motor is stalled according to the motor current.

6. A sensorless speed position detection method for an electric lifting table according to claim 5, characterized in that: The current ripple rotor position detection module includes a current sensing amplifier circuit, a bandpass filter circuit, a differential amplifier circuit and a comparison circuit. The input end of the current sensing amplifier circuit inputs the sampling current of the motor and the output end of the current sensing amplifier circuit is electrically connected to the input end of the bandpass filter circuit, the output end of the bandpass filter circuit is electrically connected to the input end of the differential amplifier circuit and the differential amplifier circuit is electrically connected to the comparison circuit.

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