Medical operation high-speed permanent magnet synchronous motor rotor position detection method

Abstract

The application relates to the technical field of motor detection, in particular to a medical operation high-speed permanent magnet synchronous micro motor rotor position detection method, which comprises the following steps: acquiring output voltage and current of a cross-axis current regulator; based on the output of the cross-axis current regulator, calculating a motor rotor position error and a rotating speed error respectively; after low-pass filtering and integration of the output of the cross-axis current regulator, a decoupling rotating speed can be obtained; after integration of the decoupling rotating speed, a decoupling rotor position angle can be obtained; after low-pass filtering and compensation of the output of the direct-axis current regulator, an estimated rotor position angle can be obtained; and after differentiation, an estimated rotating speed can be obtained. The method does not depend on a motor model and does not require motor parameters, can detect the motor rotor speed from the voltage output of the cross-axis current regulator of a zero vector control system with a direct-axis current, and then can detect the rotor position after integration.

Description

Technical Field

[0001] This application relates to the field of motor testing technology, and in particular to a method for detecting the rotor position of a high-speed permanent magnet synchronous micro motor used in medical surgery. Background Technology

[0002] Key components of medical surgical power units must utilize low-noise, high-speed, and precisely controllable micromotors. In recent years, with the rapid development of power electronics technology, frequency conversion control, and high-performance, low-cost microprocessors that implement complex algorithms, vector decoupling control permanent magnet synchronous micromotors (PMSMs) that eliminate the cross-coupling of AC and DC axis PI current regulators have become the preferred choice. Based on vector decoupling control, PMSMs require real-time detection of the motor's rotor position and speed. Rotor position detection typically employs mechanical sensors (encoders, solvers, and tachogenerators), but these sensors are bulky and prone to failure due to the large number of cable connections, making them unsuitable for installation in high-speed medical surgical micromotors. To address the various shortcomings of mechanical sensors, sensorless rotor position detection has become a key research focus.

[0003] Currently, sensorless methods for rotor position detection mainly include high-frequency signal injection utilizing the salient pole effect of the motor and estimation methods using the motor's back electromotive force (EMF) or flux linkage. The high-frequency signal injection method has specific requirements for the motor structure, necessitating a salient pole rotor, making it unsuitable for high-speed, non-salient permanent magnet synchronous motors used in medical surgeries. Estimation methods mainly include the back EMF method, model reference adaptive method, sliding mode observer method, and extended Kalman filter method. The back EMF method calculates rotor position and speed using the motor's fundamental voltage and current signals; it is simple and widely used, but highly sensitive to changes in motor parameters, making precise control difficult under varying loads and resulting in poor adaptability. The sliding mode observer method has good robustness, but exhibits significant chattering at low speeds. The extended Kalman filter method requires complex matrix inversion operations, placing high computational demands on the CPU and resulting in poor real-time performance. The model reference adaptive method can only be optimized within a specific speed range; speeds below this range are prone to rotor position oscillations, while speeds above this range tend to cause significant delays in the detected rotor position. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the existing rotor position detection method relies on sensor data in the motor, which is complicated to connect, the sensor is large in size, and prone to failure, and is not suitable for detecting the motor rotor in medical surgical power devices.

[0005] Therefore, the present invention provides a method for detecting the rotor position of a high-speed permanent magnet synchronous micro motor for medical surgery. The method detects the rotor speed of the motor from the voltage output by the direct-axis current regulator of the vector control system with zero direct-axis current, and then detects the rotor position after integration.

[0006] The technical solution adopted by this invention to solve its technical problem is:

[0007] A method for detecting the rotor position of a high-speed permanent magnet synchronous micromotor in medical surgery, characterized by comprising:

[0008] Step 1: Obtain the output voltage of the quadrature-axis and direct-axis current regulator in the γ-δ coordinate system. , and current , ;

[0009] Step 2: Calculate the motor rotor position error based on the output of the AC and DC axis current regulators. and speed error The output of the quadrature axis current regulator After low-pass filtering and integration, the decoupled speed can be obtained. Then, the decoupling speed The decoupled rotor position angle can be obtained after integration. ;

[0010] Output of the direct-axis current regulator The estimated rotor position angle is obtained after low-pass filtering and compensation. And then The estimated rotational speed can be obtained by differentiation. .

[0011] Furthermore, in step two, the output voltage is adjusted based on the output of the AC / DC axis current regulator. , Error of obtaining quadrature and direct axis voltages by performing forward decoupling , .

[0012] Furthermore, the output voltage , The voltage is obtained by forward decoupling: Error of direct and quadrature axis voltages , Expressed as: ,in, , This represents the back electromotive force coefficient of the permanent magnet synchronous motor. This refers to the actual motor speed. To estimate the rotational speed, R and L represent the equivalent armature winding resistance and inductance of the motor in the γ-δ two-phase rotating coordinate system, respectively, and p is the derivative operator V. r0 V is the forward coupling voltage along the γ-axis. δ0 This is the forward coupling voltage along the delta axis. , These are the currents in the γ-δ two-phase rotating coordinate system, respectively. Given a current along the γ-axis, This is the output of the speed loop ASR regulator.

[0013] Furthermore, in steady state, , , , ,but , Output of the delta-axis current PI regulator The output of the γ-axis current PI regulator corresponds to the error between the actual and estimated rotational speeds. The error between the estimated position angle and the actual position angle of the corresponding rotor.

[0014] Furthermore, in step two, for After low-pass filtering and integration, the decoupled speed can be obtained. for: In the formula To estimate the gain for motor speed, The time constant of the delta-axis filter is used to remove... Ripple noise in the middle.

[0015] Furthermore, regarding the decoupling speed... The decoupled rotor position angle can be obtained after integration. for: .

[0016] Furthermore, regarding After low-pass filtering, the rotor position angle is compensated and decoupled to obtain the estimated rotor position angle. for: In the formula The gain is used to estimate the rotor position, and sgn is the switching function. The time constant of the γ-axis filter is used to remove... Ripple noise in the middle.

[0017] Furthermore, the estimated rotor position angle... The estimated rotational speed can be obtained by differentiation. for: .

[0018] Furthermore, in step one, the voltage equations of the permanent magnet synchronous motor under the actual rotor position in the two-phase rotating coordinate system and the three-phase stationary coordinate system are used to calculate the voltage and current in the two-phase rotating coordinate system of the direct and quadrature axes.

[0019] Furthermore, in step one, the transformation matrix C3s / 2r is used. The voltage equations of a permanent magnet synchronous motor in a three-phase stationary coordinate system are transformed into equivalent voltage equations in a two-phase rotating γ-δ coordinate system, where... To estimate the position angle.

[0020] The beneficial effects of this invention are that, on the one hand, the detection method of this application does not rely on the motor model, the algorithm is simple, and it does not require a high-requirement CPU, thus reducing production costs; on the other hand, it does not require motor parameters or other permanent magnet synchronous motor parameters, and is not sensitive to permanent magnet synchronous motor parameters. Only the back electromotive force coefficient of the permanent magnet synchronous motor is needed to quickly obtain the rotor speed and rotor position.

[0021] This application employs a method that detects the motor rotor speed from the voltage output by the direct-axis current regulator of the vector control system with zero direct-axis current, and then detects the rotor position after integration. Therefore, it is not limited by the rotor structure of the permanent magnet synchronous motor and is applicable to both salient-pole and surface-mounted permanent magnet synchronous motors. It can accurately detect the rotor position from low speed to high speed. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Figure 1 This is a schematic diagram of the structure of the analysis model of the permanent magnet synchronous micromotor in different reference coordinate systems in this invention.

[0024] Figure 2 This is a schematic diagram of the decoupling vector control logic of the permanent magnet synchronous micromotor in this invention.

[0025] Figure 3 This is a schematic diagram of the logic of the rotor position and rotor estimation method of the permanent magnet synchronous micro motor in this invention. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0027] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] A method for detecting the rotor position of a high-speed permanent magnet synchronous micromotor in medical surgery involves decoupling the output of a vector control delta-axis PI current regulator. After low-pass filtering to remove ripple noise, the decoupled speed is obtained after integration. for , To estimate the gain for motor speed, is the time constant of the δ-axis filter.

[0030] Then the decoupling speed The decoupled rotor position angle is obtained after integration. for The output of the decoupled vector control γ-axis PI current regulator will be decoupled. After low-pass filtering to remove ripple noise, multiply by the switching function. Compensate for and decouple the rotor position angle to obtain the estimated rotor position angle. for , The gain is used to estimate the rotor position, and sgn is the switching function. The time constant of the γ-axis filter; used for estimating the rotor position angle The estimated rotational speed is obtained by differentiation. for Specifically, the detection method includes the following steps:

[0031] Step 1: Obtain the output voltage of the AC / DC axis current regulator.

[0032] Since sensorless rotor position detection is not like mechanical sensor-based direct measurement, but rather based on estimation, there is a difference between the actual rotor position angle θ and the estimated position angle. There will inevitably be errors between them. .

[0033] Let the actual rotor position be represented by the two-phase rotating coordinate system dq, and the estimated rotor position by the two-phase rotating coordinate system γ-δ. The analysis models for different reference coordinate systems are as follows: Figure 1 As shown.

[0034] Based on the characteristics of PMSM, the voltage equation of a permanent magnet synchronous motor (PMSM) in a three-phase stationary coordinate system is as follows:

[0035] (1)

[0036] In the formula R s L s These are the resistance and inductance of the motor armature winding, respectively. i is the back electromotive force coefficient of the permanent magnet synchronous motor; u i v i w For three-phase current; v u v v v w denoted as three-phase voltage; p is the derivative operator.

[0037] To obtain the numerical values ​​of physical quantities in the γ-δ coordinate system, the transformation matrix C3s / 2r is required, i.e.:

[0038] (2)

[0039] Multiplying both sides of equation (1) by the transformation matrix in equation (2) on the left, we can obtain the PMSM equivalent voltage equation in the two-phase rotating γ-δ coordinate system:

[0040] (3)

[0041] In the formula: R = R s L=(3 / 2)L s , , , , , This refers to the actual motor speed. To estimate the rotational speed, R and L represent the equivalent armature winding resistance and inductance of the motor in the γ-δ two-phase rotating coordinate system, respectively. , and , These represent the voltage and current in the γ-δ two-phase rotating coordinate system, respectively.

[0042] Step 2: Detect rotor speed and calculate rotor position.

[0043] To achieve precise control of high-speed permanent magnet synchronous micromotors used in medical surgery, a decoupled vector control strategy must be adopted for the γ-δ axis PI current regulator ACR. Figure 2 The corresponding control block diagram shows the forward decoupling voltage as follows:

[0044] (4)

[0045] In the formula V r0 This is the forward coupling voltage along the γ-axis. This is the forward coupling voltage along the delta axis. Given a current along the γ-axis, This is the output of the speed loop ASR regulator.

[0046] Subtracting equation (3) from equation (4) yields the error of the direct-axis and quadrature-axis voltages:

[0047] (5)

[0048] Depend on Figure 2 It can be seen that, , These are the outputs of the AC and DC axis current PI regulators ACR, respectively, in steady state. , When estimating position angle When the rotor position angle θ is close to the actual rotor position, the error between the two is... It is relatively small at this time. , Equation (5) becomes:

[0049] (6)

[0050] (7)

[0051] From equations (6) and (7), it can be seen that the outputs of the γ-axis and δ-axis current PI regulators correspond to the motor rotor position errors, respectively. and speed error .

[0052] In actual operation, It may be greater than zero or less than zero; therefore, the algorithm for estimating the motor rotor position and speed is as follows:

[0053] Output of delta-axis current PI regulator Corresponding to actual speed Compared with estimated speed error According to the PI control rule, for After low-pass filtering and integration, the decoupled speed can be obtained. for:

[0054] (8)

[0055] In the formula To estimate the gain for motor speed, The time constant of the delta-axis filter is used to remove... Ripple noise in the middle.

[0056] Decoupling speed The decoupled rotor position angle can be obtained after integration. for:

[0057] (9)

[0058] Output of γ-axis current PI regulator Corresponding rotor estimated position angle Error with actual position angle θ According to the PI control rule, for After low-pass filtering, the rotor position angle is compensated and decoupled, thereby obtaining the estimated rotor position angle. for:

[0059] (10)

[0060] In the formula The gain is used to estimate the rotor position, and sgn is the switching function. The time constant of the γ-axis filter is used to remove... Ripple noise in the middle.

[0061] For estimating rotor position angle The estimated rotational speed can be obtained by differentiation. for:

[0062] (11)

[0063] The above detection method obtains the decoupled speed by calculating the voltage output by the quadrature-axis current regulator, and then obtains the decoupled rotor position by integration. This position is then compensated for with the rotor position error output by the direct-axis current regulator, and then integrated to obtain the rotor position estimation angle, thereby obtaining an accurate rotor speed estimation.

[0064] On the one hand, this method does not rely on a motor model, has a simple algorithm, does not require a high-performance CPU, and reduces production costs. On the other hand, this method does not require motor parameters or other permanent magnet synchronous motor parameters, and is not sensitive to permanent magnet synchronous motor parameters. It only requires the back electromotive force coefficient of the permanent magnet synchronous motor to quickly obtain the rotor speed and rotor position.

[0065] This application employs a method that detects the motor rotor speed from the voltage output by the direct-axis current regulator of the vector control system with zero direct-axis current, and then detects the rotor position after integration. Therefore, it is not limited by the rotor structure of the permanent magnet synchronous motor and is applicable to both salient-pole and surface-mounted permanent magnet synchronous motors. It can accurately detect the rotor position from low speed to high speed.

[0066] Compared with existing technologies, the method proposed in this application has high accuracy in estimating rotor position and speed, smooth response curve, low chattering, robustness to internal and external disturbances of the motor, does not depend on motor models, requires no motor parameters, has a simple algorithm, does not require a high-performance CPU, and can meet the high-performance needs of high-speed permanent magnet synchronous micromotors in medical surgery.

[0067] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined by the scope of the claims.

Claims

1. A method for detecting the position of a rotor of a high-speed permanent magnet synchronous micro motor for medical surgery, characterized in that, Comprising: Step one, obtain the output voltage of the direct and quadrature axis current regulator in the γ-δ coordinate system , and the current , ; Step two, based on the output of the direct and quadrature axis current regulators, the motor rotor position error and speed error are calculated respectively The output of the quadrature axis current regulator is low pass filtered and integrated to obtain the decoupled speed The decoupled speed is integrated to obtain the decoupled rotor position angle ;​​​ The output of the direct axis current regulator is The estimated rotor position angle is obtained by compensating the low pass filtered result The estimated rotor position angle is obtained by compensating the low pass filtered result The estimated rotor speed is obtained by differentiating the estimated rotor position angle The estimated rotor speed is obtained by differentiating the estimated rotor position angle In the step two, based on the output of the direct and quadrature axis current regulator, the error of the direct and quadrature axis voltage is obtained by forward decoupling , the output voltage , ​ Output voltage , Forward decoupling to get voltage: , error of direct and quadrature axis voltage , Expressed as: , wherein, , is the back electromotive force coefficient of permanent magnet synchronous motor, is the actual motor speed, is the estimated speed, R and L are the equivalent armature winding resistance and inductance of the motor in γ-δ two-phase rotating coordinate system, p is the derivative operator, V r0 is the forward coupling voltage of γ axis, δ0 is the forward coupling voltage of δ axis, , are the currents in γ-δ two-phase rotating coordinate system, is the given current of γ axis, is the speed loop ASR regulator output; Output of the quadrature-axis current regulator The decoupled speed is obtained by integrating the low-pass filtered , where is the motor speed estimation gain, is the delta-axis filter time constant used to remove ripple noise; the decoupled speed is integrated to obtain the decoupled rotor position angle is given by: ; To The compensated decoupled rotor position angle is low-pass filtered to obtain an estimated rotor position angle is: , where is a rotor position estimation gain, sgn is a sign function, is a filter time constant of the γ-axis filter, used to remove ripple noise in The estimated rotor position angle is differentiated to obtain an estimated speed is: .

2. The method for detecting the position of the rotor of a high-speed permanent magnet synchronous motor for medical surgery according to claim 1, characterized in that, At steady state, , , , then , , the output of the δ-axis current PI regulator corresponding to the error between the actual speed and the estimated speed, the output of the γ-axis current PI regulator corresponding to the error between the estimated position angle of the rotor and the actual position angle.

3. The method for detecting the position of the rotor of a high-speed permanent magnet synchronous motor for medical surgery according to claim 1, characterized in that, In the step one, the voltage equation of the permanent magnet synchronous motor in the actual rotor position two-phase rotating coordinate system and three-phase static coordinate system is used to calculate the voltage and current in the two-phase rotating coordinate system of the direct and quadrature axes.

4. The method of claim 3, wherein the rotor position detection method of the medical high-speed permanent magnet synchronous motor is characterized by, In the step one, a transformation matrix C3s / 2ris used, The voltage equation of the permanent magnet synchronous motor in the three-phase stationary coordinate system is converted into the equivalent voltage equation in the two-phase rotating γ-δ coordinate system, wherein, for estimating the position angle.

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