Method for determining rotation angle error

Abstract

In a method for determining a rotation angle error, a vehicle slides in a star-closed state, a rotation detection unit detects a rotation angle of a motor and includes a periodic error uniquely determined according to the rotation angle, a current detection unit detects a current flowing through the motor, a frequency analysis unit performs frequency analysis on the current detected by the current detection unit, and an error determination unit determines a rotation angle error according to the periodic error. And an angle error estimation unit that estimates, as an angle error estimation value, the angle error comprising the specific frequency component on the basis of the amplitude, phase, or amplitude and phase calculated by the frequency analysis unit, and calculates the amplitude, phase, or amplitude and phase of the specific frequency component corresponding to the angle error. The angle error correction unit corrects the angle error with respect to the rotation angle of the motor detected by the rotation detection unit using the angle error estimation value. According to the method and the angle error correction device, the rotation angle error can be accurately solved, due to the fact that the star sealing and sliding speed is very low, resonance cannot be generated, and the detection time is short.

Description

Technical Field

[0001] This invention relates to the field of elevator traction machine and crane motor control technology, and particularly to a method for calculating rotation angle error. It is applicable to control devices for elevator traction machines, control devices for crane motors, etc., and corrects the angle error of the rotation detection unit, including a periodic error uniquely determined based on the rotation angle of the motor. Background Technology

[0002] Rotary transformers are mechanically robust and can withstand harsh environments, making them suitable for detecting various rotational angles (or rotational positions). However, compared to encoders used for detecting rotational angles (e.g., in traction machines), rotary transformers have disadvantages such as larger detection errors and lower detection accuracy. Figure 1 The detection error exhibits a periodic error that is uniquely determined by the rotation angle of the motor. This error needs to be corrected.

[0003] When determining the error correction value for each rotary transformer, for example, a large inertia (inertial body) is added to the traction machine, and the rotational inertia of this inertia is used to achieve pulsation-free constant rotation. Then, during continuous rotation, the actual angle and the detection angle are measured to detect the detection error contained in the detection angle. The detected detection errors are compiled, and the actual angle and the detection angle are mapped to the computer memory and stored as a table. Then, the detection error is actually corrected for the detection angle using the above method. Utilizing inertia to measure the detection error based on the actual angle and the detection angle in a state without rotational fluctuations has the advantage of improving correction accuracy. However, in many cases, this is often difficult, especially after the traction machine has been equipped with wire ropes and the car and counterweight have been suspended.

[0004] Chinese invention application publication CN105492871A discloses an angle error correction device and method for a position detector capable of accurately estimating and correcting angle errors. The position detector detects the rotational position of a motor, a current detection unit detects the current flowing through the motor, and a frequency analysis unit uses the motor's rotational position to perform frequency analysis on the current detected by the current detection unit, calculating the amplitude of a specific frequency component corresponding to the angle error. An angle error estimator estimates the angle error composed of the specific frequency component based on the amplitude calculated by the frequency analysis unit and the motor's rotational position, using this as an angle error estimate. An angle error correction unit uses this angle error estimate to correct the angle error based on the motor's rotational position detected by the position detector. The principle is that when using a position detector containing a periodic angle error uniquely determined by the motor's rotational position for speed feedback control, it generates current pulsations or current command values ​​containing frequency components of the same frequency as the angle error. However, this method, in order to increase the amplitude of the current pulsations, requires a relatively high elevator operating speed, which can easily cause the specific frequency corresponding to the angle error to coincide with the elevator's resonant frequency, thus leading to a decrease in the accuracy of the angle error estimation. In addition, due to the limitations of the operating range of the mechanical system installed on the motor, the rotation distance that can be rotated is limited. When the termination condition is not met, multiple estimations need to be performed repeatedly, and each estimation requires driving the motor to rotate, resulting in a long time. Summary of the Invention

[0005] To address the above problems, the present invention proposes a method for calculating the rotation angle error.

[0006] To achieve the above-mentioned objective, the present invention provides a method for determining rotation angle error, which may include: a rolling motion in a sealed state; a rotation detection unit detecting the rotation angle of a motor, including a periodic error uniquely determined based on the rotation angle; a current detection unit detecting the current flowing through the motor; a frequency analysis unit performing frequency analysis on the current detected by the current detection unit, calculating the amplitude, or phase, or amplitude and phase of a specific frequency component corresponding to the angle error; an angle error estimation unit estimating the angle error constituted by the specific frequency component based on the amplitude, or phase, or amplitude and phase calculated by the frequency analysis unit as an angle error estimate; and an angle error correction unit using the angle error estimate to correct the angle error for the rotation angle of the motor detected by the rotation detection unit.

[0007] One method for determining rotation angle error according to the present invention may further include: During a runaway motion in a sealed state, a rotation detection unit detects the rotation angle of a motor, including a periodic error uniquely determined based on the rotation angle; the angle error is calculated by referencing an ideal position value and the rotation angle of the motor detected by the rotation detection unit. A frequency analysis unit performs frequency analysis on the angle error, calculating the amplitude, or phase, or amplitude and phase of a specific frequency component corresponding to the angle error; an angle error estimation unit estimates the angle error composed of the specific frequency component as an angle error estimate based on the amplitude, or phase, or amplitude and phase calculated by the frequency analysis unit; and an angle error correction unit uses the angle error estimate to correct the angle error for the rotation angle of the motor detected by the rotation detection unit.

[0008] One method for determining the rotation angle error according to the present invention may further include: During a runaway motion in a sealed state, a rotation detection unit detects the rotation angle of a motor, including a periodic error uniquely determined based on the rotation angle; the rotation angle of the motor detected by the rotation detection unit is differentiated to obtain a detection speed; a frequency analysis unit performs frequency analysis on the detection speed or speed error, calculating the amplitude, or phase, or amplitude and phase of a specific frequency component corresponding to the angle error; an angle error estimation unit estimates the angle error composed of the specific frequency component as an angle error estimate based on the amplitude, or phase, or amplitude and phase calculated by the frequency analysis unit; and an angle error correction unit uses the angle error estimate to correct the angle error for the rotation angle of the motor detected by the rotation detection unit.

[0009] In a preferred embodiment of the present invention, the angle error estimation unit assumes that the estimated angle error is represented by a sine wave or a cosine wave as a function of the mechanical angle of the motor. It estimates the amplitude and phase of the angle error. First, the amplitude of the angle error is fixed to a predetermined initial value. Then, the phase of the angle error is varied and corrected starting from the predetermined initial value. A corrected value that minimizes the current amplitude composed of a specific frequency component is selected as the phase estimate. The phase estimation of the angle error ends when the estimation termination condition is met. Next, the phase of the angle error is fixed to the phase estimate. The amplitude of the angle error is varied and corrected starting from the predetermined initial value. A corrected value that minimizes the current amplitude composed of a specific frequency component is selected as the amplitude estimate. The amplitude estimation of the angle error ends when the estimation termination condition is met.

[0010] In a preferred embodiment of the present invention, the angle error estimation unit assumes that the estimated angle error is represented by a sine wave or a cosine wave as a function of the mechanical angle of the motor, estimates the amplitude or phase of the angle error, and makes the amplitude or phase of the specific frequency component calculated by the frequency analysis unit correspond to the frequency characteristics of the current pulsation of the motor, and estimates the angle error, wherein the frequency characteristics are the characteristics of the angle error acting on the current after coordinate transformation of the current output by the current detection unit.

[0011] In a preferred embodiment of the present invention, the angle error estimation unit assumes that a sine wave or a cosine wave is used as a function of the mechanical angle of the motor to represent the estimated angle error value, and estimates the amplitude or phase of the angle error. The angle error estimation unit includes: an error amplitude estimation unit, which, based on the output of the current detection unit, confirms the amplitude of the current pulsation at a specific frequency calculated by the frequency analysis unit, and makes the amplitude of the specific frequency change with time while performing angle correction, and takes the value at which the amplitude calculated by the frequency analysis unit reaches its minimum as the amplitude estimate of the angle error; and an error phase estimation unit, which, based on the output of the current detection unit, confirms the amplitude of the current pulsation at a specific frequency calculated by the frequency analysis unit, and makes the phase of the specific frequency change with time while performing angle correction, and takes the value at which the amplitude calculated by the frequency analysis unit reaches its minimum as the phase estimate of the angle error.

[0012] In a preferred embodiment of the present invention, the angle error estimation unit estimates the angle error while keeping the speed of the motor constant.

[0013] In a preferred embodiment of the present invention, a coordinate transformer is further provided, which transforms the phase current of the motor detected by the current detection unit into the shaft current of the motor, and the frequency analysis unit performs frequency analysis on the shaft current of the motor.

[0014] In a preferred embodiment of the present invention, the coordinate transformer transforms the phase current of the motor detected by the current detection unit into dq-axis coordinates, and the frequency analysis unit performs frequency analysis on any current among the d-axis current and q-axis current transformed by the coordinate transformer.

[0015] By adopting the above technical solution, the present invention can obtain a method and an angle error correction device that can accurately calculate the rotation angle error. Since the speed of the sealing trolley is very slow, resonance will not occur, and the detection time is short. Attached Figure Description

[0016] Figure 1This is an example diagram illustrating the detection angle error of the present invention.

[0017] Figure 2 This is a schematic diagram of electronic satellite sealing in one embodiment of the present invention.

[0018] Figure 3 This is a schematic diagram of the contactor sealing in one embodiment of the present invention.

[0019] Figure 4 This is a waveform diagram of the elevator slipping after the permanent magnet synchronous motor is sealed in one embodiment of the present invention.

[0020] Figure 5 This is an overall structural block diagram of the apparatus included in the method for determining rotation angle error in one embodiment of the present invention.

[0021] Figure 6 This is a block diagram of the angle error estimation unit in one embodiment of the present invention. Detailed Implementation

[0022] Implementation Method 1

[0023] Figure 5 This is a block diagram showing the overall structure of the apparatus included in the method for determining the rotation angle error of the present invention. The elevator car 4 and the counterweight 5 are connected to each other by traction ropes 6 and suspended in a bottle-like manner on the pulley 3. The pulley 3 is connected to the motor 1, which serves as the drive motor for the car 4, and the car 4 is raised and lowered by the power of the motor 1. The motor 1 that raises and lowers the car 4 is a permanent magnet synchronous motor (PM motor).

[0024] A rotation detection unit 2 is mounted on the same shaft as the motor 1 and the pulley 3 to detect the rotation angle of either the motor 1 or the pulley 3. The angle information includes a periodic error uniquely determined corresponding to the rotation angle of the motor 1. This angle information is the rotation angle of the motor 1 output by the rotation detection unit 2, which is, for example, composed of a rotary transformer, an encoder, or a magnetic sensor. Here, the periodic error uniquely determined corresponding to the rotation angle of the motor 1 refers to an error that is reproducible to the rotation angle, such as pulse omissions and uneven pulse intervals caused by detection errors in the rotary transformer or gap defects in an optical encoder; that is, an error generated at the same rotation angle position in each revolution.

[0025] The periodic angular error θ in the angle contained in the output of the rotation detection unit 2 err The periodic angular error of the rotation detection unit 2 can be approximated using a sine wave as shown in equation (1). Furthermore, since there is no essential difference between the expression based on a sine wave and the expression based on a cosine wave, the expression based on a sine wave is unified in this invention.

[0026]

[0027] In equation (1), θ m A represents the mechanical angle of motor 1, A1 represents the error amplitude at order N1, A2 represents the error amplitude at order N2, A... n N represents n Error amplitude at order number This represents the phase shift (initial phase) of the mechanical angle of motor 1 relative to the N1 order. This represents the phase shift of the mechanical angle of motor 1 relative to the N2 order. Relative to N n Phase shift of the mechanical angle of motor 1 at order number.

[0028] In addition, N1, N2…N in equation (1) n The spatial order does not need to be 1, 2...N n Instead of consecutive integers, the spatial order of the principal component of the periodic error is uniquely determined by the rotational position of motor 1. The principal component referred to here is the component with a larger amplitude at this spatial order compared to amplitudes at other frequencies.

[0029] Furthermore, equation (1) is expressed as a formula that synthesizes more than three frequency components, but the periodic angular error θ err The frequency components can also be composed of one or two, or more than two components.

[0030] The contactor-controlled or electronically controlled star-stop 11, by shorting the three-phase input of motor 1, utilizes the braking force generated by the permanent magnet of the PM motor to slow down the elevator or limit its running speed. "Electronic star-stop," such as... Figure 2 This means that while the inverter blocks the drive signal of the upper (lower) bridge arm, it controls the switching transistor of the lower (upper) bridge arm to conduct, thereby short-circuiting the three-phase input of motor 1. Contactor star-on, such as... Figure 3 A "sealed-plane contactor" is used, which is added between the frequency converter and motor 1 to short-circuit the three-phase input of motor 1. When the mass of the elevator car 4 and the counterweight 5 are not equal, the brake of motor 1 (not shown) is released, and the elevator car 4 accelerates from rest. When the sealed-plane braking torque of motor 1 equals the unbalanced torque generated by the mass difference between car 4 and counterweight 5, the speed of the car becomes constant. Generally, the speed of the car is less than 0.3 m / s.

[0031] Current detector 7 detects the current of motor 1. For example, in the case of motor 1 being a three-phase motor, it is more common to measure the phase current of two phases (such as phase U). u ,V phase i vHowever, it can also measure the phase currents of the three phases. Furthermore, when the contactor is star-sealed, a current detector needs to be placed between the star-sealing contactor and motor 1 so that the current of motor 1 can be detected when the contactor slips during star-sealing. The phase current is obtained by coordinate transformation (not shown) to obtain the shaft current of motor 1 (such as the d-axis current i in vector control). d q-axis current i q (as shown in equation (2)).

[0032]

[0033] In equation (2), i α i β Let α be the α-axis current and β be the β-axis current in the stationary coordinate system, and θ be the rotor electrical position angle of motor 1. When the zero position of the rotation detection unit 2 is aligned with the magnetic pole position of motor 1, θ is the number of pole pairs n of motor 1. p Multiply by the rotation angle of the motor 1 output by the rotation detection unit 2, i.e., n p θ m +n p θ err .

[0034] The frequency analysis unit 8 performs frequency analysis on the axis current obtained after coordinate transformation of the phase current detected by the current detector 7, and outputs the amplitude, or amplitude and phase at a specific frequency. Here, it is desirable that the frequency analysis unit 8 be a structure that obtains the amplitude and phase of the input signal at a specific frequency, such as through Fourier transform, discrete Fourier transform, Fourier series expansion, or fast Fourier transform. However, it could also be a structure that extracts a specific frequency signal, such as a filter combining a notch filter and / or a bandpass filter, and calculates the amplitude and phase of the input signal at a specific frequency by performing amplitude and phase calculations on the output current of, for example, a bandpass filter, using an amplitude detection unit and / or a phase detection unit (not shown). Furthermore, the filter used here can be an electrical filter combining resistors, capacitors, coils, etc., or it can be a process performed within a computer. The frequency analysis unit 8 will be described below with a structure configured to perform a Fourier transform.

[0035] Furthermore, in Embodiment 1 of the present invention, the structure of the frequency analysis unit 8 is not limited as long as it is a structure capable of detecting information proportional to the amplitude of the desired frequency or information proportional to the power of the amplitude.

[0036] In addition, Figure 5The intermediate frequency analysis unit 8 adopts a structure that takes the rotation angle information of the motor 1 output by the rotation detection unit 2 as input, but it is not limited to this. It can also take the corrected angle information obtained by the angle error correction unit 10 after correcting the rotation angle of the motor 1 output by the rotation detection unit 2 as input. Alternatively, it can take the product of the period of the phase current and the number of pole pairs of the motor 1 as input, so that the frequency analysis unit 8 can perform frequency analysis on the shaft current of the motor 1 rotating one or several times.

[0037] Furthermore, the signal of the desired frequency (specific frequency) mentioned here refers to the periodic angular error θ of the rotation detection unit 2. err The, and the angle error θ err The signals with the same principal component frequency.

[0038] In Embodiment 1 of the present invention, the desired frequency is represented as a spatial frequency, but there is no essential difference even when considering the time frequency.

[0039] Here, spatial frequency refers to the frequency within a specific range, which in Embodiment 1 of the present invention refers to the frequency at which the motor 1 rotates once. Furthermore, the signal of the periodic N waves generated when the motor 1 rotates one mechanical angle is referred to as a wave of spatial order N.

[0040] The angle error estimation unit 9 takes the output of the frequency analysis unit 8, namely the current amplitude or current amplitude and phase value of the desired frequency component, and the angle information corrected by the angle error correction unit 10 as input, and estimates the periodic angle error θ, which is uniquely determined based on the rotational position of the motor 1, using the estimation method described later. err The estimated angle error is output as angle information to the angle error correction unit 10.

[0041] The angle error correction unit 10 adds or subtracts the rotation angle of the motor 1 output from the rotation detection unit 2 and the angle error estimation value output from the angle error estimation unit 9, and outputs the corrected angle information.

[0042] Furthermore, as shown in equation (1) above, when there are multiple frequency components of the angle error, the angle error can be estimated by summing up each component sequentially or by estimating multiple frequency components simultaneously. In this case, compared with estimating the angle error by estimating each component sequentially, simultaneous estimation can shorten the estimation time. Here, for simplicity, we will explain the case where the angle error consists of only a single frequency component.

[0043] Here, during the coasting phase in the star-locked state, the phase current of motor 1 is detected by current detector 7. Since the rotation of motor 1 at this time depends on the unbalanced torque generated by the mass difference between car 4 and counterweight 5, the resistance and inductance of each phase winding of motor 1, along with the back electromotive force generated by the motor's rotation, form a braking circuit. As the motor's speed increases, the generated back electromotive force e increases, the current flowing through this braking circuit increases, and the resulting star-locked braking torque also increases. When the unbalanced torque equals the star-locked braking torque, the coasting speed of motor 1 remains constant. Therefore, coasting in the star-locked state is an open-loop operation, meaning it is not a closed-loop vector control using the rotation detection unit 2. Figure 4 This is a waveform diagram of the elevator slipping after the star-sealing operation is performed on motor 1. 41 represents the rotation angle of motor 1 output by the rotation detection unit 2, and 42 and 43 are the phase currents of the two phases measured by the current detector 7, respectively. The phase currents of motor 1 in the star-sealing state, as well as the α-axis and β-axis currents in the stationary coordinate system, do not contain the periodic angular error θ from the rotation detection unit 2. err The specific frequency component. However, through the dq coordinate transformation, as shown in equation (2), the rotation angle of the output of the rotation detection unit 2 is introduced, so the d-axis current or q-axis current contains current ripples with frequency components of the same order as the angle error. Therefore, if the angle error is estimated and corrected in order to suppress the axis current ripples, the angle error of the output of the rotation detection unit 2 can be reduced.

[0044] Therefore, for example, in order to minimize the current amplitude of the Nnth order of the d-axis current or q-axis current obtained through the frequency analysis in the frequency analysis unit 8, the angle error estimation unit 9 only needs to estimate the angle error. The estimated angle error has the same form as equation (1), that is, it only needs to estimate the amplitude estimate A. n_est and phase estimate That's all.

[0045] Furthermore, when performing frequency analysis using the current detection value of either the d-axis current or the q-axis current, it is particularly desirable to perform the estimation under the condition that the motor 1 rotates at a constant speed with zero acceleration, i.e., when the speed of the sealing wheel reaches a stable state.

[0046] Here, in Embodiment 1 of the present invention, when the angle error estimation unit 9 estimates the angle error using frequency analysis of the current, it first estimates the angle error relative to N. n The phase deviation of the mechanical angle of motor 1 in order of order is relative to the phase deviation, and then N is estimated. n Error amplitude in the order number. Figure 6 The structure of the angle error estimation unit 9 is shown.

[0047] The processing flow of the angle error estimation unit 9 in Embodiment 1 of the present invention will be described below.

[0048] First, the amplitude estimate A n_est and phase estimate By assigning an arbitrary and appropriate initial value (predetermined initial value), correction is performed, and motor 1 is rotated in a sealed-plane manner to perform frequency analysis and obtain the current amplitude of the principal component of the angle error.

[0049] Next, only the phase estimate is made The changes are corrected, and the motor 1 is rotated in a sealed trolley for frequency analysis. The current amplitude of the principal component of the angle error is searched to minimize it and determined as the phase estimate.

[0050] Next, the phase estimate determined in the above steps is fixed. And make the amplitude estimate A n_est The changes are corrected, and motor 1 is subjected to frequency analysis by sealing the track, searching for the A value that minimizes the current amplitude of the principal component of the angle error. n_est This is determined as the amplitude estimate.

[0051] This invention can also be applied using binary search or other linear search, hill climbing, tabu search, simulated annealing, and other search algorithms.

[0052] Furthermore, for example, if the maximum error of the rotation detection unit 2 is known in advance according to specifications, the initial value for amplitude estimation can be set between the maximum error and 0.

[0053] Furthermore, the termination condition for estimation is determined by the number of trials, the accuracy of the calibrated position detection unit, or the pulsation amplitude of the current. When the termination condition for estimation is met, the angle error estimation unit 9 maintains the phase estimate and the amplitude estimate, and outputs the angle error estimate corresponding to the above equation (1).

[0054] Here, the phase current of motor 1 in the sealed state, as well as the α-axis current and β-axis current in the stationary coordinate system, do not contain the periodic angular error θ of the rotation detection unit 2. err The specific frequency components allow for the storage of one mechanical cycle's phase current or α-axis current, β-axis current, and the rotation angle of motor 1 output by rotation detection unit 2 when the speed of the star-sealing trolley reaches stability. This same set of data is then used to search for the optimal amplitude estimate A. n_est and phase estimate This minimizes the current amplitude of the principal component of the angle error. Compared to requiring a sealed-off runway for each search, storing a set of current and angle information from the sealed-off runway and then performing multiple frequency analyses is more flexible and faster, and can be done offline. For example, the data can be exported to smart devices such as mobile phones or computers for searching and optimization, and the estimated angle error results can be recorded in storage media (e.g., non-volatile memory). During normal operation, the recorded estimated values ​​are read out, and the angle error corresponding to the rotation position is corrected. However, the disadvantage is that some storage space is required so that the discretely acquired phase current or α-axis current, β-axis current, and the rotation angle of motor 1 output by rotation detection unit 2 do not introduce too much error when performing frequency analysis at a specific frequency.

[0055] In addition, the angle error estimation unit 9 can only use the amplitude estimate A n_est and phase estimate The angle error is output as an estimated value to the angle error correction unit 10. At this time, the angle error estimation unit 9 does not need to take the angle information corrected by the angle error correction unit 10 as input. The angle error correction unit 10 generates an angle error corresponding to the above formula (1) based on the angle error estimated value output by the angle error estimation unit 9, generates an angle error correction signal to cancel the error, adds it to the rotation angle of the motor 1 output from the rotation detection unit 2, and outputs the corrected angle information.

[0056] The amplitude, or amplitude and phase, of the current ripple output by the frequency analysis unit 8 at a specific frequency is determined, for example, by calculating the Fourier coefficients of the current ripple corresponding to the specific frequency. The following explains the calculation of the Fourier coefficients of the current ripple for the q-axis current. The Fourier coefficients of the current ripple at the frequency M1 [Hz] of the q-axis current corresponding to the angular error frequency can be calculated using the following formula (3).

[0057]

[0058] In equation (3), i q (t) represents the instantaneous value of the q-axis current, and T represents the current ripple period at frequency M1 [Hz]. Furthermore, T = 1 / M1. Where A n1 B n1 These represent the coefficients of the cosine wave and the sine wave, respectively.

[0059] Furthermore, Equation (3) shows the solution in the form of time integration, but it can also be obtained by integrating according to the rotation angle of motor 1. Also, Equation (3) is a continuous-time domain expression, but when installed in a computer such as a microcomputer, it is transformed into a discrete-time domain expression for installation. In addition, Equation (3) can be operated by any signal generator, multiplier, or integrator that generates a cosine wave or sine wave, and therefore can be easily installed in a computer.

[0060] Furthermore, while Equation (3) calculates the Fourier coefficients by integrating the signal over one cycle, it is also possible to integrate over several cycles and obtain the value by dividing the integral by the number of cycles. In this case, since the average value over several cycles is calculated, the deviation of current ripples and the influence of external interference can be reduced. Moreover, it is preferable to start the integration from a reference point (e.g., zero degrees) of the rotation angle of motor 1. Thus, the Fourier coefficients based on the rotation angle of motor 1 can be obtained.

[0061] Here, the amplitude A of the current pulsation component can be obtained from the Fourier coefficients of equation (3) using the following equation (4). t1 and phase

[0062]

[0063] The angle error estimation unit 9 stores the amplitude A obtained using equation (4). i1 and phase Alternatively, the Fourier coefficients A can also be stored. n1 B n1 The amplitude and phase are calculated using equation (4).

[0064] The estimated result of the angle error corresponding to the magnetic pole position of the traction machine is recorded in a storage medium (e.g., a non-volatile memory). During normal operation, the estimated angle error value corresponding to the output of the rotation detection unit 2 is read from the storage medium for correction. Regarding the information related to the angle error recorded in the storage medium, the angle error can be calculated as the error amplitude and phase deviation of the angle error by calculation according to the above equation (1), or it can be based on the correction angle information corresponding to the magnetic pole position of the traction machine, such as tables. In this case, in order to minimize the information, it is desirable to store the phase information and amplitude information in advance and perform correction by calculation.

[0065] As described above, according to Embodiment 1, when the car is in a sealed state, the rotation detection unit detects the rotation angle of the motor, including a periodic error uniquely determined based on the rotation angle. The current detection unit detects the current flowing through the motor. The frequency analysis unit performs frequency analysis on the current detected by the current detection unit and calculates the amplitude of a specific frequency component corresponding to the angle error. The angle error estimator estimates the angle error composed of the specific frequency component based on the amplitude calculated by the frequency analysis unit as an angle error estimate. The angle error correction unit uses the angle error estimate to correct the angle error for the rotation angle of the motor detected by the rotation detection unit.

[0066] Furthermore, the angle error estimation unit assumes that a sine wave or cosine wave is used as a function of the mechanical angle of the motor to represent the angle error estimate. It estimates the amplitude and phase of the angle error. First, the amplitude of the angle error is fixed to a predetermined initial value. For the phase of the angle error, it is varied and corrected starting from the predetermined initial value. The corrected value that minimizes the current amplitude composed of a specific frequency component is selected as the phase estimate. The phase estimation of the angle error ends when the estimation termination condition is met. Next, the phase of the angle error is fixed to the phase estimate. For the amplitude of the angle error, it is varied and corrected starting from the predetermined initial value. The corrected value that minimizes the current amplitude composed of a specific frequency component is selected as the amplitude estimate. The amplitude estimation of the angle error ends when the estimation termination condition is met.

[0067] Therefore, it is possible to accurately estimate the angle error and make corrections.

[0068] Implementation Method 2

[0069] In Implementation 1, it is necessary to search for the phase and amplitude estimates of the angle error through multiple satellite-sealed runaway and frequency analysis, which results in an excessively long search time; or it is necessary to store the current and angle information in the satellite-sealed runaway and perform multiple frequency analyses to search for the phase and amplitude estimates of the angle error.

[0070] In Embodiment 2 of the present invention, the following will be described: When the train is in a sealed state, the angle error estimation unit 9 directly estimates the angle error by utilizing the frequency characteristics of the current pulsation in the d-axis current or q-axis current, which contains a frequency component of the same order as the angle error. Furthermore, the structure of the angle error correction device in Embodiment 2 of the present invention is the same as that in Embodiment 1 described above; only the function of the angle error estimation unit 9 is different. Therefore, the description of the device structure is omitted.

[0071] Assuming the U, V, and W phase current values ​​i are in the sealed-off rolling state. u i v i wfor

[0072]

[0073] In the formula, I s , The amplitude and initial phase of the phase current depend on the motor's inherent parameters and the PM motor's speed. θ e Let θ be the rotor electrical position angle, and θ be the rotor electrical position angle. e =n p θ m .

[0074] Then the α-axis current i in the stationary coordinate system α β-axis current i β for

[0075]

[0076] The d-axis current i after dq coordinate transformation by equation (2) d q-axis current i q for

[0077]

[0078] As can be seen from equation (7), the current pulsation components of the d-axis and q-axis are the same as those during the runaway motion. Related to angle error. When the car is coasting in the sealed state, Generally in The maximum error of the rotating detection unit 2 is generally less than From equation (7), it can be seen that the current pulsation components of the d-axis and q-axis are approximately sinusoidal waveforms, and the q-axis current i q Phase of pulsating components Approximately And the d-axis current i d Phase of pulsating components Approximately That is, by performing frequency analysis on the d-axis current or q-axis current through the frequency analysis unit 8, the phase estimate of the angle error can be obtained.

[0079] Since the current pulsations of the d-axis and q-axis are approximately sinusoidal, the amplitude estimate A1 of the angle error can be easily calculated using formula (7). The following uses the d-axis current i d Taking frequency analysis as an example, let's examine the q-axis current i. q Frequency analysis can also yield an estimate of the amplitude of the angular error. Because in Less than When the rate of change of the sine waveform is greater than that of the cosine waveform, it is preferable to use the d-axis current i. d Perform frequency analysis.

[0080] When using d-axis current i d When performing frequency analysis, it can be seen from formula (7) that the d-axis current i d At the rotational position of motor 1 When it reaches its peak value And in When it reaches its trough value Right now

[0081]

[0082] In the formula A id1 For d-axis current i d Amplitude obtained from frequency analysis.

[0083] From equation (8), the amplitude estimate A1 of the angle error is:

[0084]

[0085] The amplitude estimate A1 of the angle error can also be based on A id1 Approximately get

[0086]

[0087] Furthermore, when there is only one frequency component of the angle error, and the U, V, and W phase currents only have the fundamental wave in the state of star sealing and rolling, it can be seen from formula (7) that θ can be used. m d-axis current i for any value d Instantaneous value or q-axis current i q The amplitude estimate A1 of the angle error is directly obtained from the instantaneous value, preferably using θ. m =0.

[0088] Additionally, when the initial phase of the current of some PM motors is switched off from the satellite, When the speed is relatively small, by blocking the drive signals of the upper (lower) bridge arm in the frequency converter and reducing the duty cycle of the switching transistors of the lower (upper) bridge arm, the speed of the slewing device can be increased, thereby increasing the speed of the slewing device.

[0089] When the speed of the star-tracking accelerator reaches a stable level, the aforementioned initial phase of the current... or or It can be easily obtained using existing technologies.

[0090] Implementation Method 3

[0091] Similar to Embodiment 3 of CN105492871A, firstly, the frequency analysis unit 8 uses, for example, a bandpass filter or notch filter with good real-time performance to extract only the signal of the desired frequency. Next, the frequency analysis unit 8 calculates the amplitude of the extracted frequency signal or a quantity equivalent to the amplitude (hereinafter, both are referred to as "amplitude"). Then, the difference between the calculation result and the current ripple command value (which can be set to zero) is used as the input of the error amplitude / phase estimator. The error amplitude / phase estimator, for example, uses PID control to change the amplitude / phase according to time correction. By making the current ripple command value zero, the current ripple after frequency analysis is controlled to become zero, that is, the error amplitude / phase becomes the true value.

[0092] Implementation Method 4

[0093] like Figure 1 The angle error is obtained by the difference between the straight line S2, the ideal value of the rotation angle, and the angle detection data S1.

[0094] When the speed of the sealing track reaches a stable point, the ideal value of the rotation angle, linear S2, can be obtained by integrating the average speed of the sealing track. This value is then subtracted from the rotation angle information of the motor 1 output by the rotation detection unit 2 to obtain the angle error. The frequency analysis unit performs frequency analysis on the angle error, calculating the amplitude, or phase, or amplitude and phase of a specific frequency component corresponding to the angle error. The angle error estimation unit estimates the angle error composed of the specific frequency component based on the amplitude, or phase, or amplitude and phase calculated by the frequency analysis unit, as an angle error estimate. The angle error correction unit uses the angle error estimate to correct the angle error for the rotation angle of the motor detected by the rotation detection unit.

[0095] In addition, the ideal value of the rotation angle, the straight line S2, can also be obtained by detecting the current of the motor 1 through the current detector 7, and the actual rotation angle of the motor 1 can be obtained based on the current.

[0096] Implementation Method 5

[0097] When the speed of the sealing star trolley reaches a stable state, the rotation angle of the motor 1 output by the rotation detection unit 2 is differentiated to obtain the detection speed. Frequency analysis is performed on the detection speed or speed error to calculate the detection error of each frequency component. The calculated detection errors are then combined to generate an angle error estimate.

[0098] The periodic angular error shown in equation (1) can be converted into a periodic velocity error as shown in equation (11) by differentiation.

[0099]

[0100] The frequency analysis unit 8 performs frequency analysis on the detected speed or speed error, and calculates the amplitude, or phase, or amplitude and phase of a specific frequency component corresponding to the angle error. The angle error estimation unit estimates the angle error composed of the specific frequency component based on the amplitude, or phase, or amplitude and phase calculated by the frequency analysis unit as the angle error estimate. The angle error correction unit uses the angle error estimate to correct the angle error for the rotation angle of the motor detected by the rotation detection unit.

[0101] Furthermore, the trolley speed of motor 1 is obtained by using the frequency of the phase current. The speed error is obtained by subtracting the speed obtained by differentiating the rotation angle of motor 1 output by the rotation detection unit 2. Frequency analysis is performed on the speed error to calculate the detection error of each frequency component. The calculated detection errors are then combined to generate an angle error estimate.

[0102] Furthermore, the methods for estimating the amplitude and phase of the angle error and the methods for frequency analysis can be combined with the methods of Embodiments 1 to 5 of the present invention. For example, phase estimation of the angle error can be performed using Embodiment 2, and then amplitude estimation of the angle error can be performed using Embodiment 1, thereby reducing the search time. The methods of Embodiments 1 to 5 of the present invention can also be combined with the methods used in Chinese Invention Application Publication No. CN105492871A, such as those for frequency analysis and angle error estimation of current pulsations or current command value pulsations during speed feedback closed-loop vector control using a rotation detection unit 2.

[0103] In addition, embodiments 1 to 5 can use the rotation angle of the motor 1 and / or phase current or α-axis current and β-axis current output by the rotation detection unit 2 of one or more mechanical cycles as described in embodiment 1, and then use this same set of data to estimate the angle error. Alternatively, the stored data can be exported to a smart device such as a computer or mobile phone for analysis and estimation.

[0104] Furthermore, embodiments 1 to 5 can estimate the angle error multiple times by performing multiple satellite rollouts, and use the average of these multiple estimates as the estimated angle error value. Additionally, it can be easily extended to cases where there are multiple frequency components of the angle error.

Claims

1. A method for determining rotation angle error, characterized in that, When the motor is in a sealed state, the rotation detection unit detects the rotation angle of the motor, including a periodic error uniquely determined by the rotation angle. The current detection unit detects the current flowing through the motor. The frequency analysis unit performs frequency analysis on the current detected by the current detection unit and calculates the amplitude, or phase, or amplitude and phase of a specific frequency component corresponding to the angle error. The angle error estimation unit estimates the angle error composed of the specific frequency component based on the amplitude, or phase, or amplitude and phase calculated by the frequency analysis unit as the angle error estimate. The angle error correction unit uses the angle error estimate to correct the angle error for the rotation angle of the motor detected by the rotation detection unit.

2. A method for determining rotation angle error, characterized in that, In the sealed-off state, the rotation detection unit detects the rotation angle of the motor, including a periodic error uniquely determined by the rotation angle. The angle error is calculated by referencing the ideal position value and the motor rotation angle detected by the rotation detection unit. The frequency analysis unit performs frequency analysis on the angle error, calculating the amplitude, or phase, or amplitude and phase of a specific frequency component corresponding to the angle error. The angle error estimation unit estimates the angle error composed of the specific frequency component based on the amplitude, or phase, or amplitude and phase calculated by the frequency analysis unit as an angle error estimate. The angle error correction unit uses the angle error estimate to correct the angle error for the motor rotation angle detected by the rotation detection unit.

3. A method for determining rotation angle error, characterized in that, When the motor is in a sealed state, the rotation detection unit detects the rotation angle of the motor, including a periodic error uniquely determined by the rotation angle. The rotation angle of the motor detected by the rotation detection unit is differentiated to obtain the detection speed. The frequency analysis unit performs frequency analysis on the detection speed or speed error, and calculates the amplitude, or phase, or amplitude and phase of a specific frequency component corresponding to the angle error. The angle error estimation unit estimates the angle error composed of the specific frequency component based on the amplitude, or phase, or amplitude and phase calculated by the frequency analysis unit as the angle error estimate. The angle error correction unit uses the angle error estimate to correct the angle error for the rotation angle of the motor detected by the rotation detection unit.

4. The method for determining the rotation angle error according to claim 1, characterized in that, The angle error estimation unit assumes that the estimated angle error is represented by a sine wave or cosine wave as a function of the mechanical angle of the motor. It estimates the amplitude and phase of the angle error. First, the amplitude of the angle error is fixed to a predetermined initial value. Then, the phase of the angle error is varied and corrected starting from the predetermined initial value. The corrected value that minimizes the current amplitude composed of a specific frequency component is selected as the phase estimate. The phase estimation of the angle error ends when the estimation termination condition is met. Next, the phase of the angle error is fixed to the phase estimate. Then, the amplitude of the angle error is varied and corrected starting from the predetermined initial value. The corrected value that minimizes the current amplitude composed of a specific frequency component is selected as the amplitude estimate. The amplitude estimation of the angle error ends when the estimation termination condition is met.

5. The method for determining the rotation angle error according to claim 1, characterized in that, The angle error estimation unit assumes that a sine wave or cosine wave is used as a function of the mechanical angle of the motor to represent the estimated angle error value, estimates the amplitude or phase of the angle error, and makes the amplitude or phase of the specific frequency component calculated by the frequency analysis unit correspond to the frequency characteristics of the current pulsation of the motor to estimate the angle error. The frequency characteristics are the characteristics of the current after coordinate transformation of the current output by the current detection unit.

6. The method for determining the rotation angle error according to claim 1, characterized in that, The angle error estimation unit assumes that a sine wave or cosine wave is used as a function of the mechanical angle of the motor to represent the estimated angle error value, and estimates the amplitude or phase of the angle error. The angle error estimation unit includes: an error amplitude estimation unit, which, based on the output of the current detection unit, confirms the amplitude of the current pulsation at a specific frequency calculated by the frequency analysis unit, and makes the amplitude of the specific frequency change with time while performing angle correction, and takes the value at which the amplitude calculated by the frequency analysis unit reaches its minimum as the estimated amplitude value of the angle error; and an error phase estimation unit, which, based on the output of the current detection unit, confirms the amplitude of the current pulsation at a specific frequency calculated by the frequency analysis unit, and makes the phase of the specific frequency change with time while performing angle correction, and takes the value at which the amplitude calculated by the frequency analysis unit reaches its minimum as the estimated phase value of the angle error.

7. The method for determining the rotation angle error according to any one of claims 1 to 6, characterized in that, The angle error estimation unit estimates the angle error under the condition that the rolling speed of the motor is constant.

8. The method for calculating the rotation angle error according to any one of claims 1, 4, 5, and 6, characterized in that, It also includes a coordinate transformer that converts the phase current of the motor detected by the current detection unit into the shaft current of the motor, and the frequency analysis unit performs frequency analysis on the shaft current of the motor.

9. The method for determining the rotation angle error according to claim 8, characterized in that, The coordinate transformer transforms the phase current of the motor detected by the current detection unit into dq-axis coordinates, and the frequency analysis unit performs frequency analysis on any current among the d-axis current and q-axis current after transformation by the coordinate transformer.

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