CN110943653A

CN110943653A - Rotor position adjusting method in motor starting stage

Info

Publication number: CN110943653A
Application number: CN201911398888.8A
Authority: CN
Inventors: 张毅鸣
Original assignee: United Automotive Electronic Systems Co Ltd
Current assignee: United Automotive Electronic Systems Co Ltd
Priority date: 2019-12-30
Filing date: 2019-12-30
Publication date: 2020-03-31
Anticipated expiration: 2039-12-30
Also published as: CN110943653B

Abstract

The invention discloses a method for adjusting the position of a rotor in the starting stage of a motor, which judges whether the relative position between a stator and the rotor meets the expected condition or not after the motor finishes the external synchronization open loop acceleration stage. If the rotor is not at the expected position, the rotor finally reaches the expected position by adjusting the relative position of the stator and the rotor and the speed of the rotor, and finally the switching of the control state of the motor is completed. Compared with the prior art, the scheme provided by the invention has the advantages that manual off-line calibration is replaced by a self-adaptive control algorithm without manually calibrating the switchable motor rotating speed and the switching time, so that the calibration workload is reduced. The motor starting anti-interference capability and the self-adaption capability to working condition deviation can be effectively improved, and the motor starting stability can be improved. The invention realizes the closed-loop regulation of the relative position of the stator and the rotor by an algorithm, and aims to correct the relative position error of the stator and the rotor accumulated in the starting process so as to meet the switching condition.

Description

Rotor position adjusting method in motor starting stage

Technical Field

The invention belongs to the technical field of motor control, and particularly relates to a method for adjusting the position of a rotor in a motor starting stage.

Background

The method for detecting the zero crossing point of the back electromotive force requires that the motor reaches a certain rotating speed, so that the zero speed needs a starting stage of the motor when reaching the certain rotating speed, a three-stage starting scheme is generally adopted, namely a rotor positioning stage, an external synchronous open loop acceleration stage and a running state are switched to a self-synchronous running state, the rotating speed change trend of each stage can be shown in figure 2, the rotor positioning stage (① in figure 2) has the function of determining the initial position of a motor rotor, the purpose is that the rotor can be started from a fixed position each time when the motor is static, a magnetic braking rotor positioning mode is adopted under the condition of light load of the general low-power brushless direct current motor, the magnetic flux formed in the motor can be forcibly attracted to the magnetic flux direction of the motor rotor in a certain time by conducting any two phases of the motor, and the electrifying time and PWM duty ratio on any two groups of windings can be calibrated.

The method comprises an external synchronous open-loop acceleration stage (② in fig. 2) for artificially changing an external voltage or a phase change signal of a motor to enable the motor to gradually increase the rotating speed from a static state, wherein after a rotor is successfully positioned, the external voltage and the phase change signal of the motor are artificially changed to drive the motor to do acceleration motion, and the aim of accelerating to a speed at which the strength of a back electromotive force can be used for detecting a zero crossing point requirement is achieved.

In the prior art, the following two switching methods are adopted. One is to determine the switchable motor speed by off-line calibration, and to switch when this speed is reached. And in the other mode, the time reaching the preset switching rotating speed is detected through tests, and switching can be carried out when the switching time is counted by a software timer. The success rate of switching in the two technical schemes provided by the prior art depends heavily on the accuracy of offline calibration and test, and is only applicable to specific working conditions of specific loads. However, in practical applications, the characteristics of the motor and the load are affected by the environment (the supply voltage and the temperature), and the motor body also has differences, so the solutions proposed by the prior art have the following disadvantages:

relying on precise calibration: all calibrated accuracies are affected by the performance of the test equipment, the test object and the actual operation of the test personnel. For example, in the application of an oil pump motor of a hydraulic control system of a double-clutch automatic gearbox, the motor is already integrated in a gearbox valve body, and the rotating speed of the motor cannot be measured. The controller adopts a mode of directly connecting a valve body connector, and three phase currents cannot be actually measured;

incomplete working condition coverage: all calibrations can only be completed under specific load and test conditions, and considering cost, time and technical limitations, the calibration of each working point under the full-application working condition and the full-environment working condition is difficult to be completely realized. For example, in the application of an oil pump motor of a hydraulic control system of a double-clutch automatic gearbox, the combination action of oil pressure (0-83 bar), 4 shifting forks and 2 clutches needs to be considered under the full application working condition. The whole environment working condition comprises oil temperature (-40-125 ℃) and power supply voltage (10.5-14.8V, including steady state and fluctuation), and the combination of the whole application working condition and the whole environment working condition is too complex;

the robustness is poor: the actual system operation is also influenced by other factors, such as motor body difference, aging, vibration, electromagnetic interference, unexpected load change and the like. For example, in the application of an oil pump motor of a hydraulic control system of a gearbox, the performance of products of all batches cannot be guaranteed to be consistent by the motor process, various vertical deviations and aging exist, and different control results can be generated by the same calibration parameter. The oil circuit may also be mixed with impurities to cause accidental changes of the load, and the original calibration parameters cannot be self-adaptive to the disturbance.

Therefore, there is a need to provide a solution to the problems of the prior art.

Disclosure of Invention

The invention aims to provide a method for adjusting the position of a rotor in the starting stage of a motor, which is used for solving the problems of dependence on accurate calibration, incomplete working condition coverage and poor robustness in the prior art.

In order to solve the technical problem, the invention provides a method for adjusting the position of a rotor in the starting stage of a motor, which comprises the following steps:

s1: judging whether the relative position between the stator and the rotor meets the expected condition, if so, entering S3, otherwise, entering S2;

s2: adjusting the relative position between the stator and the rotor, and returning to S1;

s3: and the motor enters the zero crossing point detection of the back electromotive force and is started normally.

Optionally, whether the relative position between the stator and the rotor meets the expected condition is judged according to the suspended opposite electromotive force signal of the motor and the bus voltage.

Optionally, the S1 specifically includes:

s11: respectively sampling hanging back electromotive force signals e1 and e2 and bus voltages U1 and U2 at the time t1 and the time t 2;

s12: judging whether the relative position between the stator and the rotor meets the expected condition comprises the following steps: determining whether the e1, the e2, the U1, and the U2 satisfy:

(e1<0.5U1) and (e2>0.5U2), or (e1>0.5U1) and (e2<0.5U 2);

s13: if yes, go to S3; if not, the process proceeds to S2.

Optionally, the S2 specifically includes:

if (e1 is less than or equal to 0.5U1) and (e2 is less than or equal to 0.5U2), the rotor position lags behind the stator commutation and does not reach the expected position, the stator magnetic field force is increased or the stator commutation frequency is slowed down so as to adjust the relative position between the stator and the rotor;

if (e1 is more than or equal to 0.5U1) and (e2 is more than or equal to 0.5U2), the rotor position exceeds the stator commutation and exceeds the prefabricated position, the stator magnetic field force is reduced or the stator commutation frequency is accelerated to adjust the relative position between the stator and the rotor; and returns to S1.

Optionally, if the rotor position lags behind the stator commutation and does not reach the expected position, the stator magnetic field force is increased or the stator commutation frequency is slowed down so as to adjust the relative position between the stator and the rotor; if the rotor position exceeds the stator commutation position, the stator magnetic field force is reduced or the stator commutation frequency is accelerated to adjust the relative position between the stator and the rotor.

Optionally, the stator magnetic field force is reduced or increased by changing the output duty ratio r of the motor, and the magnitude of r is in direct proportion to the magnitude of the stator magnetic field force.

Optionally, the initial value of the output duty cycle of the motor is r_iSaid r_iA function satisfying the following parameters:

r_i＝f(θ,U_DC,t_m,T_L) Wherein theta is the included angle between the electromagnetic acting force direction of the stator and the magnetic field direction of the rotor, U_DCSupply voltage to the motor, t_mIs the motor temperature, T_LIs the motor load.

Optionally, the r is_iProportional to theta, and U_DCIn inverse relation to said t_mIn direct proportion to the T_LIn direct proportion.

Optionally, in an ideal state, the initial value of the stator commutation frequency is f_iSaid f_iSatisfies the following conditions:

wherein n is_minThe lowest rotating speed of the motor is represented by p, and the number of pole pairs of the motor is represented by p.

Optionally, the unit adjustment amount of the output duty ratio is Δ r, and the unit adjustment amount Δ f of the stator commutation frequency satisfies a function of the following parameters:

Δr＝f(U_DC,t_m,ΔT_L,D_e) Wherein Δ T_LAs rate of change of motor load, D_eFor stator to rotor position deviations, Δ r and U_DCIn inverse relation to said t_mIn direct proportion to the Δ T_LIn direct proportion to the D_eIn direct proportion.

Alternatively, if (e1 ≦ 0.5U1) and (e2 ≦ 0.5U2), Δ r may satisfy a function of the following parameters:

wherein

The deviation of the actual position of the rotor from the expected position is taken as the deviation;

if (e1 ≧ 0.5U1) and (e2 ≧ 0.5U2), Δ r satisfies a function of the following parameters:

wherein

The actual position of the rotor is advanced by the deviation of the expected position.

Optionally, Δ f satisfies a function of:

Δf＝f(U_DC,t_m,ΔT_L,D_e) Wherein Δ T_LAs rate of change of motor load, D_eFor stator to rotor position deviations, Δ r and U_DCIn inverse relation to said t_mIn direct proportion to the Δ T_LIn direct proportion to the D_eIn direct proportion.

Alternatively, if (e1 ≦ 0.5U1) and (e2 ≦ 0.5U2), then Δ f may satisfy a function of the following parameters:

wherein

if (e1 ≧ 0.5U1) and (e2 ≧ 0.5U2), Δ f satisfies a function of the following parameters:

wherein

Optionally, the S2 includes:

s21: judging whether the relative position between the stator and the rotor and the number of times of adjusting the speed of the rotor exceed threshold values, if so, turning off the motor, and if not, entering S22;

s22: the relative position between the stator and the rotor is adjusted, and the process returns to S1.

The invention provides a method for adjusting the position of a rotor in the starting stage of a motor. If the rotor is not at the expected position, the rotor finally reaches the expected position by adjusting the relative position of the stator and the rotor and the speed of the rotor, and finally the switching of the control state of the motor is completed. Compared with the prior art, the scheme provided by the invention has the advantages that manual off-line calibration is replaced by a self-adaptive control algorithm without manually calibrating the switchable motor rotating speed and the switching time, so that the calibration workload is reduced. The motor starting anti-interference capability and the self-adaption capability to working condition deviation can be effectively improved, and the motor starting stability can be improved. In the prior art, the motor motion track in the external synchronous acceleration stage is strictly calibrated, and the switching is directly carried out after the motor motion track is completely calibrated.

In addition, in order to ensure that the starting performance is met under the full application working condition and the full environment working condition in the prior art, the most appropriate parameters need to be calibrated at the working condition points as full as possible; the invention only needs to select a plurality of key working conditions to carry out parameter calibration, other parameters can be obtained through a linear interpolation algorithm, and the aim is to determine the control quantity of the relative position of the rotor in the next dynamic correction under different working conditions.

The difference from the prior art is that the prior art is only suitable for application scenarios with unchanged load characteristics, good consistency and small external interference. The method provided by the invention is not only suitable for the application scene suitable for the prior art, but also suitable for the influences of variable load, external interference and various mechanical deviation aging, and aims to enhance the control robustness and the anti-interference performance.

Drawings

FIG. 1 is a schematic diagram of a control scheme of a brushless DC motor without a position sensor in the prior art;

FIG. 2 is a diagram illustrating a trend of a three-stage start-up of a prior art;

FIG. 3 is a schematic structural diagram of a brushless DC motor;

FIG. 4 is a schematic diagram of a stator conduction mode of a B-phase conduction power supply and a C-phase conduction ground;

FIG. 5 is a schematic diagram of a stator conduction mode of a B-phase conduction power supply and an A-phase conduction ground;

FIG. 6 is a schematic diagram of a stator conduction mode of a C-phase conduction power supply and an A-phase conduction ground;

FIG. 7 is a schematic diagram of a stator conduction mode of a C-phase conduction power supply and a B-phase conduction ground;

FIG. 8 is a schematic diagram of the stator conduction mode being phase A conduction power and phase B conduction ground;

FIG. 9 is a schematic diagram of the stator conduction mode being phase A conduction power and phase C conduction ground;

FIG. 10 is a schematic view of the stator and rotor positions during the outer synchronous switching self-synchronizing phase;

fig. 11 is a schematic diagram of a suspended phase voltage waveform of any phase of the three-phase brushless dc motor;

fig. 12 is a flowchart of a method for adjusting a rotor position during a motor starting phase according to an embodiment of the present invention;

fig. 13 is a flowchart of another method for adjusting a rotor position during a motor starting phase according to an embodiment of the present invention.

Detailed Description

The following describes in more detail embodiments of the present invention with reference to the schematic drawings. Advantages and features of the present invention will become apparent from the following description and claims. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "upper", "lower", "left", "right", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

Fig. 3 is a schematic structural diagram of an electrically controlled brushless dc motor, which can be divided into a stator side and a rotor side, wherein the stator side is formed by winding a coil winding on an iron core, the connection modes of three-phase winding lead-out wires can be divided into a star connection method and a triangle connection method, and the rotor side is formed by a permanent magnet and is installed on a central rotating shaft. When direct current is conducted between any two phases of the motor, the stator winding generates magnetic field force in a fixed direction and attracts the rotor magnetic field to align, so that the purpose of drawing the rotor to rotate is achieved. The traction force and the traction time mainly depend on the size of the electromagnetic force on the stator side generated by the modulation of the PWM signal and the included angle of the magnetic fields of the stator and the rotor.

For a square wave driven three-phase brushless dc motor, the three phases of the motor can be divided into a phase, B phase and C phase, and there are 6 optional conventional conduction modes (as shown in fig. 4): phase a conduction power supply phase B conduction (as shown in fig. 8, the stator magnetic field force direction is 240 °, the optimal rotor motion trajectory is 120 ° → 180 °), phase a conduction power supply phase C conduction (as shown in fig. 9, the stator magnetic field force direction is 180 °, the optimal rotor motion trajectory is 60 ° → 120 °), phase B conduction power supply phase a conduction (as shown in fig. 5, the stator magnetic field force direction is 60 °, the optimal rotor motion trajectory is 300 ° → 360 °), phase B conduction power supply phase C conduction (as shown in fig. 4, the stator magnetic field force direction is 0 °, the optimal rotor motion trajectory is 240 ° → 300 °), phase C conduction power supply phase a conduction (as shown in fig. 6, the stator magnetic field force direction is 120 °, the optimal rotor motion trajectory is 0 ° → 60 °), and phase C conduction power supply phase B conduction (as shown in fig. 7, the stator magnetic field force direction is 300 °, the optimal rotor motion trajectory is 180 ° → 240 °). When the rotor sweeps the shaded sector of 60 degrees, the stator is triggered to change the phase, the magnetic field force of the stator is switched to the next 60-degree direction, and the stator sequentially relays to drive the rotor to complete the 360-degree rotary motion. The successful condition for switching from outer synchronization to self synchronization is that the direction of the magnetic field force of the stator at the switching moment and the movement track of the rotor and the moment of the current movement satisfy the relationship as shown in the figure. The included angle between the stator magnetic field and the rotor magnetic field should be controlled to be about 90 degrees (usually in the range of 60-120 degrees) as much as possible to ensure the maximum torque output. When the speed of the external synchronous open loop is accelerated and switched to the self synchronous closed loop, the three conditions of sufficient electromagnetic force, a proper stator and rotor magnetic field included angle and sufficient rotor speed need to be met simultaneously, and the motor can continue to operate stably after the switching to the self synchronization.

The invention mainly provides a self-adaptive control algorithm aiming at external synchronous switching to a self-synchronization link, namely, the relative position between rotors is detected at the stage, a motor software control module dynamically adjusts the relative position of a stator and a rotor and the speed of the rotor according to the self-adaptive algorithm by adjusting the commutation frequency and the three-phase output driving voltage at the stator side, so that the rotating speed of the rotor exactly reaches the threshold value requirement and stably follows the magnetic potential of the stator to rotate by a fixed angular phase (60-120 degrees of electric angle), thereby meeting the switching condition from external synchronization to self-synchronization and enabling the motor to smoothly and stably transition to the zero crossing point of the reverse electromotive force to detect the commutation driving motor to work.

The specific implementation scheme of the present invention is shown in fig. 10 and fig. 11, and compared with the prior art, the present invention adopts an adaptive control algorithm, and after the external synchronization acceleration stage is completed, whether a rotor sector reaches an expected rotor position (as shown in fig. 4 to 9) specified in the current stator conduction mode is determined by detecting a motor-suspended counter electromotive force signal, a bus voltage, and a zero crossing point (as shown in fig. 11). If the rotor position does not reach the expected position, i.e. the rotor movement is considered to be behind the stator commutation, the stator magnetic field force needs to be increased or the stator commutation frequency needs to be slowed down. If the rotor position exceeds the expected position, i.e., the stator commutation is considered to be behind the rotor motion, it is desirable to reduce the stator magnetic field force or to speed up the stator commutation frequency. After multiple adjustments, the rotor movement meets the appointed expected rotor position under the current stator conduction mode, namely, the switching condition is met. It is noted that the zero-crossing point refers to a direct current having positive and negative polarities, such as a pulse voltage, or an alternating current having positive and negative amplitudes, from positive to negative or from negative to positive, which must pass through a zero point, such as a position in a circle in fig. 11. The invention judges whether the rotor reaches the expected position by using a back electromotive force zero crossing point detection method, whether the voltage value of any phase end of the motor is half of the voltage value of a target bus is judged, and if the voltage value is half of the voltage value of the target bus, the back electromotive force zero crosses.

As shown in fig. 12, the present invention provides a method for adjusting a rotor position during a motor start phase, including the following steps:

The invention provides a method for adjusting the position of a rotor in the starting stage of a motor, and the implementation scheme of the method is based on the existing three-stage type position-sensorless brushless direct current motor starting control method, and realizes dynamic correction of the relative position of a stator and the rotor through software control, and the principle of the method is shown in figure 10. After the motor finishes the outer synchronous open loop acceleration stage, whether the relative position between the stator and the rotor meets the expected condition or not is judged, namely whether the rotor reaches the expected position or not is judged. If the rotor is not at the expected position, the rotor finally reaches the expected position by adjusting the relative position of the stator and the rotor and the speed of the rotor, and finally the switching of the control state of the motor is completed. Compared with the prior art, the scheme provided by the invention has the advantages that manual off-line calibration is replaced by a self-adaptive control algorithm without manually calibrating the switchable motor rotating speed and the switching time, so that the calibration workload is reduced. The motor starting anti-interference capability and the self-adaption capability to working condition deviation can be effectively improved, and the motor starting stability can be improved. In the prior art, the motor motion track in the external synchronous acceleration stage is strictly calibrated, and the switching is directly carried out after the motor motion track is completely calibrated.

Optionally, in step S1 of the method provided in the embodiment of the present invention, it may be determined whether the relative position between the stator and the rotor meets an expected condition by detecting a floating back electromotive force signal of the motor, a bus voltage, and a zero crossing point.

As shown in fig. 11, after the motor completes the outer synchronization open loop acceleration phase, it is determined whether the relative position between the stator and the rotor meets the expected condition by detecting the motor-suspended counter electromotive force signal, the bus voltage, and the zero crossing point, that is, it is determined whether the rotor sector reaches the expected rotor position specified in the current stator conduction mode, that is, the position relationship shown in fig. 4 to 9, by detecting the motor-suspended counter electromotive force signal, the bus voltage, and the zero crossing point. It should be noted that if the rotor position does not reach the desired position, i.e., the rotor movement is considered to lag the stator commutation, it can be adjusted by increasing the stator magnetic field force or slowing the stator commutation frequency. If the rotor position exceeds the expected position, i.e., the stator commutation is considered to be behind the rotor motion, the adjustment can be made by reducing the stator magnetic field force or increasing the stator commutation frequency. After multiple adjustments, the rotor moves to an expected rotor position which is specified under the current stator conduction mode, and the switching condition is also met.

Based on the first stator conduction mode of the operation state switching stage, the corresponding expected position of the rotor can be obtained according to the corresponding relation in fig. 4 to fig. 9, and whether the rotor just moves to the vicinity of the expected position is judged by sampling the suspended phase voltage and the bus voltage at least two time points (which can be t1 time and t2 time) at fixed time, and the judgment principle is whether the counter electromotive force zero crossing point of the suspended phase occurs between t1 and t 2.

Specifically, the process of determining whether the relative position between the stator and the rotor in S1 meets the expected condition may specifically be as follows:

s12: determining whether the e1, the e2, the U1, and the U2 satisfy:

(e1<0.5U1) and (e2>0.5U2) or (e1>0.5U1) and (e2<0.5U 2);

s13: if yes, go to S3; if not, the process proceeds to S2.

Optionally, the S2 specifically includes:

During each stator commutation period, the above-mentioned detection and regulation process is performed once, and when the condition is not switched, the stator conduction mode change (or commutation) is triggered according to the stator commutation frequency updated by each algorithm. When the switching condition is met, the zero crossing point detected in the current commutation period can be adopted to calculate the commutation moment and trigger commutation, and then the zero crossing point detection method can be used for driving the motor to run.

Optionally, if the rotor position lags behind the stator commutation and does not reach the expected position, increasing the stator magnetic field force or slowing down the stator commutation frequency to adjust the relative position between the stator and the rotor; if the rotor position exceeds the stator commutation position, the stator magnetic field force is reduced or the stator commutation frequency is accelerated to adjust the relative position between the stator and the rotor.

Optionally, the stator magnetic field force is reduced or increased by changing the output duty ratio r of the motor, and the magnitude of r is in direct proportion to that of the stator magnetic field force.

Optionally, the r_iProportional to theta, and U_DCIn inverse relation to said t_mIn direct proportion to the T_LIn direct proportion.

Alternatively, the unit adjustment amount of the output duty ratio is Δ r, and the unit adjustment amount of the stator commutation frequency is Δ f.

Optionally, the Δ r satisfies a function of:

wherein

wherein

Optionally, the Δ f satisfies a function of:

wherein

wherein

Optionally, the S2 includes:

It should be noted that, in the embodiment of the present invention, the position sensorless brushless dc motor driven by square waves is designed as a target object and based on a "three-stage" starting technology, and the method provided by the present invention is still applicable to other motor control system applications that require adjustment of the relative position of the stator and the rotor at any time. The method provided by the invention adopts a mode of sampling voltage by software to obtain phase voltage and bus voltage to judge the zero crossing point, and the technical scheme of adopting external hardware or other intelligent chips to identify the zero crossing point still can be used as a flexible design of the technical scheme provided by the invention.

The software technology of the invention is realized as shown in fig. 13, and when the motor completes external synchronous acceleration, the duty ratio r is output_iAnd commutation frequency f_iThe parameters for the last execution of the outer sync acceleration phase. Based on the first stator conduction mode in the switching stage, the corresponding expected position of the rotor can be obtained according to the relation of figures 4-9, and the suspended phase voltage e is sampled at fixed time through at least two time points (which can be set as t1 time and t2 time)_A(time t1 is e1, time t2 is e2) and the bus voltage (i.e., the motor supply voltage) U_DC(U1 at time t1 and U2 at time t2) to determine whether the rotor is moving right to the vicinity of the desired position, and the principle of the determination is whether the counter electromotive force zero crossing point of the suspension phase occurs between t1 and t2, that is to say, the following conditions are satisfied:

(e1<0.5U1) and (e2>0.5U2) or (e1>0.5U1) and (e2<0.5U2) (1)

If the relation is not satisfied, further judgment is needed. When (e1 ≦ 0.5U1) and (e2 ≦ 0.5U2), it is said that the rotor movement lags the expected position by Δ r⁺Increase by incrementAdding the current duty cycle output or by Δ f^-Decrementing to reduce the current stator commutation frequency.

When (e1 ≧ 0.5U1) and (e2 ≧ 0.5U2), the rotor movement is described as being advanced by the expected position by Δ r^-Decrement to reduce current duty cycle output or by Δ f⁺Increments to increase the current stator commutation frequency.

During each stator commutation period, the detection and the regulation are executed once, and when the condition of the formula (1) is not satisfied, the stator conduction mode conversion (or commutation) is triggered according to the stator commutation frequency updated by each algorithm. And an upper limit threshold value of the adjusting times can be set, and if the switching condition is not met when the adjusting times reach the upper limit, the current motor can be stopped from being started and the motor can be tried to be restarted. When the condition of the formula (1) is satisfied, the zero crossing point detected in the current commutation period can be adopted to calculate the commutation moment and trigger commutation, and then the zero crossing point detection method can be used for driving the motor to run.

Through the analysis, several key control parameters need to be determined in the method provided by the invention, namely the initial duty ratio, the initial stator commutation frequency, the primary duty ratio and the unit adjustment quantity of the stator commutation frequency. The determination of these several parameters is analyzed one by one below.

Determination of initial duty cycle of synchronization phase:

the duty cycle of the output directly determines the magnitude of the electromagnetic force generated on the stator windings. Initial duty cycle r of the synchronization phase_iThe duty ratio output from the last phase change period of the external synchronous acceleration stage is inherited, and the duty ratio needs to ensure that the rotating speed does not fall off under the current load driven by proper stator electromagnetic force traction. The required electromagnetic force mainly depends on the included angle theta between the electromagnetic acting force direction of the stator and the magnetic field direction of the rotor and the load size T_L(torque form). Due to the supply voltage U of the motor_DCDirectly influencing the electromagnetic force on the stator side of the motor, the motor temperature t_mBut also directly influences the electromagnetic property of the motor, so the initial duty ratio r_iIs a function of the following parameters:

r_i＝f(θ,U_DC,t_m,T_L)

generally, the greater θ or U_DCThe smaller or T_LThe greater or t_mThe larger the value r_iThe larger.

For oil pump motor control, for example, the duty cycle is determined by an oil pump stand (start-up load determination) test, and the calibration condition is defined as θ being 120 ° and an allowable supply voltage range and an allowable motor operating temperature range.

Determination of the commutation frequency of the initial stator of the synchronization phase:

initial commutation frequency f of the synchronization phase_iThe method inherits the last phase change period of an external synchronous acceleration stage, and the included angle (60-120 degrees) of a stator and a rotor needs to be maintained to meet the requirement that the rotating speed is not dropped under the current load, so that the rotor is prevented from rotating in a blocking mode. Ideally (generally, the working condition of no load, no disturbance and no sampling error) the initial commutation frequency should be equivalent to the lowest rotating speed n that the counter electromotive force of the motor can collect_min(typically provided by the motor supplier), commutation frequency f_iIs a function of the following parameters, namely:

wherein p is the number of pole pairs of the motor. It should be noted that in non-ideal situations, the back emf signal can be accurately acquired by increasing the initial commutation frequency.

Determining the unit regulating quantity of the primary duty ratio and the stator commutation frequency in the synchronization stage:

the magnitude of the one-time adjustment determines how quickly the synchronization phase and the accuracy of the position correction can be completed. Unit regulating quantity and load change rate delta T in regulating process_LCorrelation with stator-rotor position deviation D_eCorrelation (

A deviation of the actual position of the rotor behind the expected position,

to advance the actual position of the rotor by a deviation from the expected position) and the motor temperature t, due to the fact that the motor supply voltage directly affects the electromagnetic force on the stator side of the motor_mAnd directly influences the electromagnetic characteristics of the motor, so that the delta r and the delta f are functions of the following parameters:

Δr＝f(U_DC,t_m,ΔT_L,D_e)；

Δf＝f(U_DC,t_m,ΔT_L,D_e)；

typically, both Δ r and Δ f are the same as U_DCIn inverse relation to said t_mIn direct proportion to the Δ T_LIn direct proportion to the D_eIn direct proportion.

Besides the three parameters of initial duty ratio, initial stator commutation frequency and unit adjustment quantity of primary duty ratio and stator commutation frequency, a rotor expected position check point in the synchronization stage needs to be determined:

as shown in fig. 13, is a 60 ° commutation period T_c＝(f_i±Δf)^-1The ideal zero-crossing of the back emf should occur at the 30 deg. center point instant t_zI.e. the phase voltage before the centre point should be lower than half the bus voltage and the phase voltage after the centre point should be higher than half the bus voltage. One or more pairs of sampling moments (t1, t2) can be arranged before and after the central point at equal distance, and the error D of the actual zero-crossing point deviating from the expected zero-crossing point (30 DEG central point) is judged through two or more groups of voltage differences_e. The sampling time needs to satisfy the following function:

|t₁-t_z|＝|t₂-t_z|；

typically, the selectable checkpoints are (15 °, 45 °) or (20 °, 40 °), depending on the tolerance of the deviation allowed by the system. The closer the checkpoint is to the central point, the more stringent the switching conditions.

It should be noted that, as will be understood by those skilled in the art, the method for adjusting the rotor position in the starting stage of the motor provided in the embodiment of the present invention is not only suitable for controlling the brushless dc motor without a position sensor, but also can be used for diagnosis and redundancy in controlling a general motor; besides, the method is applicable to the synchronous stage of the starting control of the brushless direct current motor without the position sensor, and can also be used for detecting and adjusting the relative position of the stator and the rotor in the acceleration stage. The specific process is similar to that of a brushless dc motor without a position sensor, and is not described herein.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example" or "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. And the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments. Furthermore, various embodiments or examples described in this specification can be combined and combined by those skilled in the art.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any way. It will be understood by those skilled in the art that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A method for adjusting the position of a rotor in the starting stage of a motor is characterized by comprising the following steps:

2. The method for adjusting the position of the rotor during the starting phase of the motor as claimed in claim 1, wherein the method determines whether the relative position between the stator and the rotor meets the expected condition according to the suspended counter electromotive force signal of the motor and the bus voltage.

3. The method for adjusting the rotor position during the starting phase of the motor according to claim 2, wherein the step S1 specifically includes:

(e1<0.5U1) and (e2>0.5U2), or (e1>0.5U1) and (e2<0.5U 2);

s13: if yes, go to S3; if not, the process proceeds to S2.

4. The method for adjusting the rotor position during the starting phase of the motor according to claim 3, wherein the step S2 specifically includes:

5. The method of claim 1, wherein if the rotor position is behind the stator commutation and does not reach the expected position, the stator field force is increased or the stator commutation frequency is decreased to adjust the relative position between the stator and the rotor; if the rotor position exceeds the stator commutation position, the stator magnetic field force is reduced or the stator commutation frequency is accelerated to adjust the relative position between the stator and the rotor.

6. A method for adjusting the position of a rotor during the starting phase of a motor according to any one of claims 4 and 5, wherein the magnetic force of the stator is reduced or increased by changing the output duty ratio r of the motor, and the magnitude of r is in direct proportion to that of the magnetic force of the stator.

7. A method of adjusting the position of a rotor during a start-up phase of an electrical machine as claimed in claim 6, wherein the initial value of the output duty cycle of the electrical machine is r_iSaid r_iA function satisfying the following parameters:

8. The method of claim 7, wherein r is a number of times the rotor is rotated during the starting phase of the motor_iProportional to theta, and U_DCIn inverse relation to said t_mIn direct proportion to the T_LIn direct proportion.

9. Method for adjusting the position of a rotor during the starting phase of an electric machine according to any one of claims 4 and 5, characterized in that, ideally, the initial value of the commutation frequency of the stator is f_iSaid f_iSatisfies the following conditions:

10. A method of adjusting the position of a rotor during the starting phase of an electric motor, as set forth in claim 6, characterized in that the unit adjustment of the output duty cycle is Δ r and the unit adjustment of the commutation frequency of the stator is Δ f, said Δ r satisfying a function of the following parameters:

Δr＝f(U_DC,t_m,ΔT_L,D_e) Wherein Δ T_LAs rate of change of motor load, D_eFor stator to rotor position deviations, Δ r and U_DCIn inverse relation to said t_mThe direct-current voltage is in direct proportion,and said Δ T_LIn direct proportion to the D_eIn direct proportion.

11. A method of adjusting the position of a rotor during a starting phase of an electric motor according to claim 10, wherein if (e1 ≦ 0.5U1) and (e2 ≦ 0.5U2), Δ r satisfies the function of the following parameters:

wherein

wherein

12. A method of adjusting the position of a rotor during a start-up phase of an electrical machine according to claim 10, wherein Δ f is a function of:

13. A method of adjusting the position of a rotor during a starting phase of an electric motor according to claim 12, wherein if (e1 ≦ 0.5U1) and (e2 ≦ 0.5U2), Δ f is satisfied as a function of the following parameters:

wherein

wherein

14. The method for adjusting the position of the rotor during the starting phase of the motor according to claim 1, wherein the step S2 includes: