Motor Control Methods

Abstract

The present invention provides a motor control method, which includes: a step of calculating an ideal position of a motor rotor based on a Hall sensor signal; a step of calculating a current position of the motor rotor based on a rotation speed of the motor rotor; and a step of calculating a difference between the ideal position of the motor rotor and the current position of the motor rotor as a Hall sensor deflection angle.

Description

Technical Field

[0001] The present invention relates to a motor control method, and more particularly to a technology for accurately controlling the position and speed of a motor rotor by correcting a deflection angle of a Hall sensor installed on the motor. Background Art

[0002] Typically, in order to control the 3-phase brushless motor of an electric power steering, it is necessary to accurately calculate the position of the motor rotor.

[0003] The stator of the motor uses magnets formed by current flowing through the three-phase coils, and the rotor uses permanent magnets that alternately form N-pole and S-pole. In order to make the motor rotate continuously, it is necessary to form a continuous rotor system of the motor. In order to form a continuous rotor system, it is necessary to rectify the current flowing through the armature phase coils at the appropriate time. In order to rectify appropriately, it is necessary to accurately identify the position of the rotor.

[0004] Rectification refers to changing the direction of the current in the stator coil of the motor in such a way that the rotor can rotate.

[0005] In order for this motor to run smoothly, the rotor position and the switching time points of the phase current must be precisely aligned. For this purpose, a device for detecting the rotor position is required. Usually, in order to detect the rotor position, a Hall sensor whose potential difference changes according to the change of magnetic flux is used, or a CT (current transformer) is set in each phase of the stator.

[0006] In particular, a permanent magnet motor with a permanent magnet as a rotor is used in the air blowing component of the air supply system of the fuel cell. In order to control this permanent magnet motor, it is necessary to sense the current position of the rotor. Considering the packaging and cost, a relatively small and inexpensive Hall sensor is used to sense the current position of the rotor. In the Hall sensor, the position sensor is attached to the rotor and the stator to determine the rotor position. Due to the manufacturing deviation of the attached position sensor, there is a deflection angle when the rotor position is sensed by the Hall sensor.

[0007] In addition, the problem of position deviation of the Hall sensor occurs during the use of the motor. This causes errors in rotor position sensing, which causes the precision of inverter current control to decrease, thereby reducing inverter efficiency. Therefore, it is necessary to measure the deflection angle of the Hall sensor and correct it before current control.

[0008] The matters described as the background technology described above are only used to enhance the understanding of the background of the present invention and should not be regarded as an admission that they belong to the common knowledge known to those skilled in the art.

[0009] Prior art literature

[0010] Patent Literature

[0011] (Patent Document 1) KR 10-1749522 B

[0012] (Patent Document 2) KR 10-2008-0097732 A Summary of the invention

[0013] Technical problem to be solved by the invention

[0014] The present invention is proposed to solve this problem, and aims to provide a motor control method for performing compensation control by calculating a total of 6 deflection angles on the rising and falling edges of each phase (U phase, V phase, W phase) of the Hall sensor signal.

[0015] Technical solutions for solving technical problems

[0016] The motor control method of the present invention for achieving the above-mentioned purpose includes: a step of calculating the ideal position of the motor rotor based on the Hall sensor signal; a step of calculating the current position of the motor rotor based on the rotation speed of the motor rotor; and a step of calculating the difference between the ideal position of the motor rotor and the current position of the motor rotor as the Hall sensor deflection angle.

[0017] Before the step of calculating the ideal position of the motor rotor, the method may further include the step of calculating the rotation speed of the motor.

[0018] In the step of calculating the rotation speed of the motor, the rotation speed of the motor may be calculated using the following mathematical formula.

[0019] T Hall_update =T Hall -T Hall_old

[0020] ω r : Electrical rotation speed of the motor [rad / s], T Hall_update : The time required for the Hall sensor value to change, T Hall : The time point when the value of the Hall sensor changes, T Hall_old : The time point when the value of the previous Hall sensor changes, N: The number of poles of the motor

[0021] After the step of calculating the rotation speed of the motor, a step of determining whether a change in the motor rotation speed is less than a specified reference change may be included. When the change in the motor rotation speed is less than the specified reference change, the ideal position of the motor rotor and the current position of the motor rotor are calculated.

[0022] In the step of calculating the ideal position of the motor rotor, the ideal position of the motor rotor may be calculated based on the time point at which the signal of the Hall sensor changes.

[0023] In the step of calculating the ideal position of the motor rotor, the ideal position of the motor rotor may be calculated using the following mathematical formula.

[0024]

[0025] θ Hall : Current position angle of the Hall sensor [deg], θ Edge : The ideal position angle at the time when the Hall sensor signal changes, ω r : The electrical rotation speed of the motor [rad / s], ΔT: The time from the point in time when the Hall sensor signal changes

[0026] In the step of calculating the current position of the motor rotor, the current position of the motor rotor may be calculated based on the angle at which the motor rotor rotates from the position of the motor rotor at the time of the previous PWM switch duty cycle calculation.

[0027] In the step of calculating the current position of the motor rotor, the current position of the motor rotor may be calculated using the following mathematical formula.

[0028]

[0029] θ Spd : The position angle of the motor rotor when the current PWM switch duty cycle is calculated [deg], θ Old : The position angle of the motor rotor during the previous PWM switch duty cycle calculation [deg], ω r : Electrical rotation speed of the motor [rad / s], T PWM : PWM switch duty cycle calculation period

[0030] After the step of calculating the rotation speed of the motor, a step of determining whether the motor rotation speed is above a specified reference rotation speed may be included. When the motor rotation speed is above the specified reference rotation speed, the ideal position of the motor rotor and the current position of the motor rotor are calculated.

[0031] In the step of calculating the ideal position of the motor rotor and the current position of the motor rotor, the ideal position of the motor rotor and the current position of the motor rotor can be calculated using the signal change time point of the U phase, W phase or V phase of the Hall sensor as the reference time point.

[0032] In the step of calculating the ideal position of the motor rotor and the current position of the motor rotor, the ideal position of the motor rotor and the current position of the motor rotor can be synchronized to the ideal position of the motor rotor based on the signal change time point of the Hall sensor as the reference time point each time the signal change time point of the Hall sensor as the reference time point is repeated.

[0033] In the step of calculating the Hall sensor deflection angle, the Hall sensor deflection angle at remaining Hall sensor signal change time points other than the Hall sensor signal change time point serving as the reference time point may be calculated.

[0034] Before the step of calculating the Hall sensor deflection angle, there may be a step of calculating the Hall sensor deflection angle at a time point when the signal of the Hall sensor changes as a reference time point. In the step of calculating the Hall sensor deflection angle at a time point when the signal of the Hall sensor changes as a reference time point, the current applied to the motor is blocked to perform inertial braking, and the calculation is performed based on the d-axis voltage and q-axis voltage of the synchronous coordinate system during inertial braking.

[0035] After the step of calculating the Hall sensor deflection angle, the method may further include a step of controlling the motor based on the actual motor rotor position calculated by compensating the calculated Hall sensor deflection angle.

[0036] Effects of the Invention

[0037] According to the motor control method of the present invention, it is possible to accurately calculate the position of the motor rotor by calculating the deflection angle of the Hall sensor.

[0038] Furthermore, there is an effect that the precision of motor control can be ensured by using a relatively low-cost Hall sensor.

[0039] Furthermore, by precisely controlling the inverter that supplies the drive current to the motor, the inverter efficiency can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a block diagram of a motor control system according to an embodiment of the present invention.

[0041] Figure 2 1 is a diagram illustrating a state in which a deflection angle of a motor hall sensor is generated.

[0042] Figure 3 FIG. 1 is a flow chart of a motor control method according to an embodiment of the present invention.

[0043] Figure 4 1 is a diagram illustrating a state in which a Hall sensor signal changes.

[0044] Figure 5A and Figure 5B The diagrams illustrate waveforms of three-phase currents applied to a motor before and after the motor control method according to an embodiment of the present invention is applied.

[0045] Description of Reference Numerals

[0046] 10: Motor 20: Hall sensor

[0047] 30: Inverter 40: Fuel Cell Controller (FCU)

[0048] 50: Inverter controller DETAILED DESCRIPTION

[0049] The specific structural or functional descriptions of the embodiments of the present invention disclosed in this specification or application are merely exemplified for the purpose of illustrating the embodiments of the present invention. The embodiments of the present invention can be implemented in a variety of ways and should not be construed as being limited to the embodiments described in this specification or application.

[0050] The embodiments of the present invention may be modified in various ways and may have various forms, so specific embodiments are illustrated in the drawings and described in detail in this specification or application. However, this is not intended to limit the embodiments of the concepts of the present invention to specific disclosed forms, and should be understood to include all changes, equivalents and substitutes included in the concept and technical scope of the present invention.

[0051] The terms "first" and "second" are used to describe various components, but the above components are not limited by the above terms. The above terms are only used to distinguish one component from other components. For example, without departing from the scope of rights of the concept according to the present invention, the first component can be named as the second component, and similarly, the second component can also be named as the first component.

[0052] When a certain component is described as being “connected” or “linked” to another component, it may be directly connected or linked to the other component, but it should be understood that other components may exist between them. However, when a certain component is described as being “directly connected” or “directly linked” to another component, it should be understood that no other components exist between them. Other expressions that describe the relationship between components, such as “between” and “immediately between” or “adjacent to” and “directly adjacent to”, etc., should also be interpreted in the same way.

[0053] The terms used in this specification are only used to illustrate specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions when the context does not clearly indicate different meanings. In this specification, the terms "including" or "having" should be understood to refer to the existence of the features, numbers, steps, actions, constituent elements, parts or combinations thereof provided, and do not preclude the existence or additional possibility of one or more features and numbers, steps, actions, constituent elements, parts or combinations thereof.

[0054] In the absence of any contrary definition, all terms used herein, including technical or scientific terms, have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. Terms defined in commonly used dictionaries should be interpreted as having the same meaning as when considered in the context of the relevant art, and should not be interpreted as an ideal or excessive form of meaning if not clearly defined in this specification.

[0055] Hereinafter, the preferred embodiments of the present invention will be described with reference to the accompanying drawings, and the present invention will be described in detail. The same reference symbols shown in the various drawings represent the same components.

[0056] The motor of the present invention is a motor having a permanent magnet inside, and the speed and torque of the motor can be controlled by an inverter. Specifically, the motor of the present invention can be a motor used in an air blower that supplies air to a fuel cell system.

[0057] A permanent magnet motor may include a Hall sensor to measure the position and speed of a rotating rotor with a permanent magnet mounted inside. High-precision resolver sensors can be used in expensive drive train motors, but inexpensive Hall sensors are installed in motors used in ordinary pumps, compressors, or blowers.

[0058] The change time point of the Hall sensor signal can be a rising edge from 0 to 1 and a falling edge from 1 to 0. The digital signal receiving unit for receiving such a Hall sensor signal can generate an interrupt for accurately notifying the CPU of the time point at the Hall sensor signal change time point. The CPU receives absolute time information (operation time) through the clock.

[0059] In recent high-performance microcomputers (MCUs), a CPU that performs various logical operations, a signal processing unit, a clock, and the like can be physically integrated.

[0060] Generally speaking, in a normal motor, the Hall sensor signal is composed of three phases of U phase, V phase, and W phase arranged electrically at intervals of 120 degrees, but it can be a variety of structures such as single phase, two phases, and four phases depending on the situation.

[0061] Figure 1 It is a block diagram of a motor control system according to an embodiment of the present invention.

[0062] refer to Figure 1 In a motor control system according to an embodiment of the present invention, a motor (10) is controlled by an inverter (30), and an inverter controller (50) is used to control the inverter (30).

[0063] The inverter controller (50) receives a speed instruction from a fuel cell controller (FCU, 40) as a superior controller and issues a three-phase current instruction to the inverter (30). The inverter (30) provides the motor (10) with a three-phase current according to the three-phase current instruction.

[0064] The motor (10) is equipped with a Hall sensor (20) for measuring the position and speed of the motor rotor, etc. The measured signal of the Hall sensor (20) can be used for feedback control of a speed controller (51) inside an inverter controller (50).

[0065] Specifically, a current controller (52) inside the inverter controller (50) receives a current target value (Id*, Iq*) of a synchronous coordinate system from a speed controller (51), and transmits a voltage target value (Vd*, Vq*) of the synchronous coordinate system to a coordinate converter (53). The coordinate converter (53) can convert the voltage target value of the synchronous coordinate system into a three-phase voltage target value (a-phase, b-phase, c-phase) and provide it to the inverter (30). Based on the received three-phase voltage target value (a-phase, b-phase, c-phase), the inverter (30) can provide a three-phase current to the motor (10) through a PWM output duty ratio of a three-phase switching circuit.

[0066] In particular, in the case of a surface-mounted permanent magnet synchronous motor, the drive current provided from the inverter (30) to the motor (10) is a three-phase current, which can be proportional to the synchronous coordinate system q-axis current (Iq), wherein the synchronous coordinate system d-axis current (Id) can be 0 [A].

[0067] A control value can be applied to the inverter (30) by a current controller (52) in such a manner that a measured value of a driving current supplied by the inverter (30) to the motor (10) follows a target value. A current sensor (not shown) for measuring the driving current supplied from the inverter (30) to the motor (10) can be arranged between the inverter (30) and the motor (10). The sensor (not shown) can measure two currents among the three-phase driving currents and then feed back to the current controller (52) via a coordinate converter (53). The current controller (52) can perform feedback control in such a manner that a measured value (Id, Iq) of the driving current actually measured follows a current target value (Id*, Iq*) input by a speed controller (51).

[0068] A current sensor (not shown) for sensing the three-phase current supplied to the motor (10) generally senses the current of two phases among the three-phase current, but a current sensor (not shown) may be installed in one phase or all three phases depending on the situation.

[0069] Figure 2 1 is a diagram illustrating a state in which a deflection angle of a motor hall sensor is generated.

[0070] refer to Figure 2 A three-phase Hall sensor can be installed on a permanent magnet motor. When the permanent magnet motor, Hall sensor and the installation position of the Hall sensor are ideally and accurately made, the three-phase Hall sensor signals (U phase, V phase and W phase) change at intervals of 120[deg] (degrees), and the rising edge of each Hall sensor signal changing from 0 to 1 and the falling edge changing from 1 to 0 will become 180[deg] intervals.

[0071] However, in the actual permanent magnet motor, it is difficult to accurately form the permanent magnet itself at 180 degrees, and it is also difficult to assemble the three-phase Hall sensors at intervals of 120 degrees. Therefore, the Hall sensor signal does not change at intervals of 180 degrees due to manufacturing errors. Therefore, as shown by the dotted line in the figure, a Hall sensor deflection angle is generated, which represents the error between the ideal Hall sensor signal change and the actual Hall sensor signal change.

[0072] Therefore, as shown in the figure, there are Hall sensor deflection angles for the rising edges and falling edges of the Hall sensor signals of the three phases, and thus there are a total of six Hall sensor deflection angles.

[0073] In order to find the deflection angle of each Hall sensor, first, a certain ideal Hall sensor signal change time point can be used as the reference time point. Here, the rising edge of the U-phase Hall sensor signal is defined as 0 [deg] as the reference time point. Thus, it can be defined at 60 degree intervals such as W-phase rising edge 60 [deg], V-phase rising edge 120 [deg], U-phase falling edge 180 [deg], W-phase falling edge 240 [deg], V-phase falling edge 300 [deg]. Regarding the reference time point, any of the 6 Hall sensor signal changes can be used as the reference time point.

[0074] The ideal position of the motor rotor and the current position of the motor rotor can be calculated by taking the U-phase, W-phase or V-phase signal change time point of the Hall sensor as the reference time point. Therefore, the following describes a method for calculating the remaining 5 Hall sensor deflection angles using the rising edge of the U-phase Hall sensor signal as the reference time point.

[0075] Figure 3 FIG. 1 is a flow chart of a motor control method according to an embodiment of the present invention.

[0076] refer to Figure 3Among the deflection angles of the rising and falling edges of the three phases of the Hall sensors U, V, and W, only the deflection angle calculation method of the falling edge of the U-phase Hall sensor signal is illustrated in the flowchart. If the deflection angle calculation method for the remaining Hall sensor signals is included in the flowchart, the flowchart will become too complicated, so it is omitted. The remaining deflection angles can also be calculated in the same way, and can be calculated in parallel with the deflection angle calculation of the falling edge of the U-phase Hall sensor signal.

[0077] An embodiment of the present invention involves a motor control method including: a step of calculating an ideal position of a motor rotor based on a Hall sensor signal (S400); a step of calculating a current position of the motor rotor based on a rotation speed of the motor rotor (S500); and a step of calculating a difference between the ideal position of the motor rotor and the current position of the motor rotor as a Hall sensor deflection angle (S600).

[0078] Before the step ( S400 ) of calculating the ideal position of the motor rotor, the method may further include the step ( S110 ) of calculating the rotation speed of the motor.

[0079] The motor's rotation speed can be calculated using the following mathematical formula.

[0080] T Hall_update =T Hall -T Hall_old

[0081] ω r : Electrical rotation speed of the motor [rad / s], T Hall_update : The time required for the Hall sensor value to change, T Hall : The time point when the value of the Hall sensor changes, T Hall_old : The time point when the value of the Hall sensor changes before

[0082] The actual rotation speed of the motor may be N times the electrical rotation speed of the motor depending on the number of poles of the motor.

[0083] Figure 4 1 is a diagram illustrating a state in which a Hall sensor signal changes.

[0084] refer to Figure 4 , as shown in the figure, T Hall_update It can be calculated as the time elapsed between the time point at which the value of the Hall sensor changes and the time point at which the value of the Hall sensor changes before.

[0085] Among them, about T Hall_updateAlthough the U phase, V phase or W phase can be used, it is more accurate to calculate with the U phase as the reference time point. More specifically, the figure shows the time from the rising edge to the falling edge, but the method of measuring the time from the rising edge to the next rising edge and dividing it by 2 is more accurate because it is not affected by the deflection angle of the Hall sensor.

[0086] Refer to Figure 3 In the step (S400) of calculating the ideal position of the motor rotor, the ideal position of the motor rotor can be calculated based on the time point when the signal of the Hall sensor changes. Specifically, the ideal position of the motor rotor can be calculated using the following mathematical formula.

[0087]

[0088] θ Hall : Current position angle of the Hall sensor [deg], θ Edge : The ideal position angle at the time when the Hall sensor signal changes, ω r : The electrical rotation speed of the motor [rad / s], ΔT: The time from the point in time when the Hall sensor signal changes

[0089] When the rising edge of phase U is used as the reference time point, θ Edge It can be the position angles of the remaining five signal change time points.

[0090] Since the motor controller uses a switching frequency of several kHz to tens of kHz, it needs to perform complex calculations related to motor control in about 100us to determine the PWM duty cycle, so the calculation load is very high. Therefore, due to the limitation of the calculation load of the motor controller, it is impossible to shorten the signal confirmation cycle of the Hall sensor indefinitely.

[0091] The inverter controller has a three-phase switching circuit for controlling the three-phase output, and performs PWM duty cycle control on the six switches in the three-phase switching circuit at a frequency of several kHz to tens of kHz, thereby implementing current control for controlling the motor output. In each PWM duty cycle update period (T PWM ), the inverter controller performs various operations required to determine the PWM duty cycle (calculating motor position and speed, 3-phase current sensing, current control, determining the next 3-phase voltage output value, determining the next PWM duty cycle, etc.).

[0092] At this time, in order to accurately control the current of the current controller included in the inverter controller, it is necessary to know the accurate position and speed information of the motor in each PWM duty cycle. PWM) measures the Hall sensor signal to calculate the position angle of the motor rotor. That is, the PWM switch duty cycle calculation period (T PWM ) can be the same as the position angle measurement cycle of the motor rotor.

[0093] In the step of calculating the current position of the motor rotor (S500), the current position of the motor rotor can be calculated by the angle of rotation of the motor rotor from the position of the motor rotor when the PWM switch duty cycle was previously calculated. Specifically, the current position of the motor rotor can be calculated using the following mathematical formula.

[0094]

[0095] θ Spd : The position angle of the motor rotor when the current PWM switch duty cycle is calculated [deg], θ Old : The position angle of the motor rotor during the previous PWM switch duty cycle calculation [deg], ω r : Electrical rotation speed of the motor [rad / s], T PWM : PWM switch duty cycle calculation period

[0096] After the step (S110) of calculating the rotation speed of the motor, the method may further include a step (S120) of determining whether the change in the rotation speed of the motor is less than a predetermined reference change. When the change in the rotation speed of the motor is less than the predetermined reference change, the ideal position of the motor rotor and the current position of the motor rotor are calculated. If the change in the rotation speed of the motor is greater than the predetermined reference change, the measurement time (T1) and the number of calculations of the Hall sensor deflection angle (COUNT1) may be reset to 0 (S130).

[0097] That is, when the change amount of the motor rotation speed is smaller than the reference change amount, it can be assumed that the motor is driven at a constant speed. In addition, a condition may be added that the time when the change amount of the motor rotation speed is smaller than the reference change amount lasts for a certain period of time or more.

[0098] This is because the accuracy of the speed-based rotor position calculation value used to calculate the Hall sensor deflection angle increases when the motor is driven at a constant speed. The accuracy of the speed-based rotor position calculation value can only be ensured when the calculated speed is accurate. In the acceleration and deceleration range, there is an error between the measured speed and the actual speed, so the precision may decrease. In the constant speed range, the error between the speed measured and the actual speed is almost close to 0.

[0099] Although not shown in the figure, in the motor control method of the present invention involved in other embodiments, after the step of calculating the rotation speed of the motor (S110), a step of determining whether the motor rotation speed is above a specified reference rotation speed (not shown) may be included, and when the motor rotation speed is above the specified reference rotation speed, the ideal position of the motor rotor and the current position of the motor rotor are calculated.

[0100] Instead of the step of confirming whether it is the constant speed driving state ( S120 ), the Hall sensor deflection angle calculation may be performed in the same manner as in the constant speed state after confirming whether the rotation speed of the motor is equal to or higher than a predetermined reference rotation speed.

[0101] The reason for confirming whether it is the reference rotation speed is that the Hall sensor signal changes slowly at low speeds and the speed cannot be upgraded, which increases the error between the actual speed and the calculated speed. When the conditions above the reference speed are met, the Hall sensor deflection angle can also be calculated under variable speed conditions. If the Hall sensor deflection angle is derived from the value that is calculated repeatedly several times and averaged, the error generated in the variable speed range can be reduced.

[0102] In the steps (S400, S500) of calculating the ideal position of the motor rotor and the current position of the motor rotor, the ideal position of the motor rotor and the current position of the motor rotor can be calculated with the signal change time point of the U phase, W phase or V phase of the Hall sensor as the reference time point. That is, the reference time point can be one of the six time points of the rising edge and falling edge of the U phase, W phase or V phase of the Hall sensor. In this specification, the rising edge of the U phase is used as the reference time point for explanation.

[0103] In the step (S600) of calculating the Hall sensor deflection angle, the Hall sensor deflection angles at the remaining Hall sensor signal change time points other than the Hall sensor signal change time point as the reference time point can be calculated. Here, a method of calculating the Hall sensor deflection angle at the falling edge of the U phase is representatively described. The Hall sensor deflection angles at the rising and falling edges of the V phase and the W phase can also be calculated in the same manner.

[0104] In the steps (S400, S500) of calculating the ideal position of the motor rotor and the current position of the motor rotor, the ideal position of the motor rotor and the current position of the motor rotor can be synchronized to the ideal position of the motor rotor based on the signal change time point of the Hall sensor as the reference time point whenever the signal change time point of the Hall sensor as the reference time point is repeated. (S400', S500')

[0105] When the rising edge of the U phase is set as the reference time point, each time the rising edge of the U phase is repeated, it is possible to synchronize to the ideal position of the motor rotor calculated using the same mathematical formula as follows based on the repeated rising edge of the U phase.

[0106]

[0107] θ Hall : Current position angle of the Hall sensor [deg], θ Spd : The position angle of the motor rotor when the current PWM switch duty cycle is calculated [deg], ω r : The electrical rotation speed of the motor [rad / s], ΔT: The time from the point in time when the signal of the Hall sensor changes.

[0108] About θ Spd The rotation angle within the operation time is calculated based on the speed and integrated to calculate the position angle. Therefore, the error of the position angle due to the speed error increases as the number of operations increases.

[0109] Therefore, the rising edge of the U-phase Hall sensor signal (the ideal position reference of the motor rotor) is used as the starting point, and the synchronization θ Hall and θ Spd The calculated value can eliminate the θ caused by the integral error of the position value based on the speed as the speed increases. Spd Initialization and synchronization can be performed simultaneously at each rotation, starting from the rising edge of the U-phase Hall sensor signal at 0[deg].

[0110] In order to further improve the accuracy, the number of calculations of the Hall sensor deflection angle is counted (S610), and it is determined whether the counted number of calculations is above a benchmark number (S620). When the number of calculations reaches above the benchmark number, the multiple measured and calculated Hall sensor deflection angles can be averaged to calculate the final Hall sensor deflection angle (S630).

[0111] Before the step of calculating the Hall sensor deflection angle (S600), there may be a step (not shown) of calculating the Hall sensor deflection angle at the time point when the signal of the Hall sensor changes as a reference time point. In the step of calculating the Hall sensor deflection angle at the time point when the signal of the Hall sensor changes as a reference time point, the current applied to the motor may be blocked to perform inertial braking, and the calculation may be performed based on the d-axis voltage and q-axis voltage of the synchronous coordinate system during inertial braking.

[0112] Here, the Hall sensor deflection angle of the rising edge of the U phase of the Hall sensor as the reference time point can be calculated. First, confirm whether the motor is inertial braking. When it is determined that the motor enters inertial braking, the calculation of the Hall sensor deflection angle begins. Specifically, the following mathematical formula can be used to calculate the d-axis voltage and q-axis voltage of the synchronous coordinate system during inertial braking, thereby calculating the Hall sensor deflection angle.

[0113]

[0114]

[0115] In the angle calculation step, it is assumed that id=0 and iq=0 to calculate the skew angle.

[0116]

[0117] When the Hall sensor deflection angle does not occur, Vd becomes 0 and θ also becomes 0 according to the above voltage equation. The Hall sensor deflection angle can be calculated as θ calculated using the above mathematical formula.

[0118] Thereby, the Hall sensor deflection angle at the rising edge of the U-phase signal change serving as a reference and the Hall sensor deflection angles at the remaining five signal changes can all be calculated.

[0119] After the step of calculating the Hall sensor deflection angle ( S600 ), the method may further include a step of controlling the motor based on the actual motor rotor position calculated by compensating the calculated Hall sensor deflection angle ( S700 ).

[0120] By adding the position angles of the rising and falling edges of the U-phase, V-phase and W-phase to the Hall sensor deflection angle, the angle at which the Hall sensor signal change actually occurs can be calculated. Specifically, compensation can be performed as follows.

[0121] Actual U-phase Hall sensor falling edge position angle = U-phase Hall sensor falling edge ideal position angle + Hall sensor deflection angle

[0122] Not only the falling edge of phase U, but all the Hall sensor signal change time points can be compensated in the same way.

[0123] By correcting the Hall sensor deflection angle at the time when the Hall sensor signal changes, the actual motor rotor position angle can be accurately calculated. The motor can be controlled based on the actual motor rotor position calculated close to the actual value.

[0124] Figure 5A and Figure 5B The diagrams illustrate waveforms of three-phase currents applied to a motor before and after the motor control method according to an embodiment of the present invention is applied.

[0125] refer to Figure 5A and Figure 5B , showing the 3-phase current before compensating the Hall sensor deflection angle and the 3-phase current after compensating the Hall sensor deflection angle of the present invention. As shown in the figure, it can be seen that the ripple current of the 3-phase current is greatly reduced.

[0126] That is, before compensating the deflection angle of the Hall sensor, the position angle error causes the current control to be unstable, resulting in the problem of 3-phase current oscillation. However, after compensating the deflection angle of the Hall sensor, the current control becomes stable.

[0127] As the control of the three-phase current is stabilized, the motor's rotation speed precision and the motor's driving torque precision are improved, and as oscillation is suppressed, noise and vibration are reduced, and the motor's power consumption is reduced, thereby improving the driving efficiency and the durability of the motor.

[0128] In particular, when controlling the rotation speed, position, etc. of the motor or controlling the torque of the motor, the position calculation accuracy of the motor rotor can be ensured at the level of a rotary transformer. In motors such as drive system motors that require precise torque control, Hall sensors that are relatively cheaper than rotary transformers can be used to ensure the same level of torque control accuracy.

[0129] Although specific embodiments of the present invention have been illustrated and described, it is self-evident to those skilled in the art that the present invention is capable of various improvements and modifications within the limits of the technical concept of the present invention provided within the scope of the claims.

Claims

1. A motor control method, characterized in that: include: The step of calculating the ideal position of the motor rotor based on the Hall sensor signal; The step of calculating the current position of the motor rotor based on the rotation speed of the motor rotor; and The step of calculating the Hall sensor deflection angle is as follows: The step of calculating the current position of the motor rotor is calculated by the angle at which the motor rotor rotates from the position of the motor rotor when the PWM switch duty cycle was previously calculated. Among them, in the step of calculating the current position of the motor rotor, the current position of the motor rotor is calculated using the following mathematical formula: θ S pd: The position angle of the motor rotor during the current PWM switch duty cycle calculation [deg], θ Old : The position angle of the motor rotor during the previous PWM switch duty cycle calculation [deg], ω r : Electrical rotation speed of the motor [rad / s], T PWM : PWM switch duty cycle calculation period.

2. The motor control method according to claim 1, characterized in that: Before the step of calculating the ideal position of the motor rotor, the method further includes the step of calculating the rotation speed of the motor.

3. The motor control method according to claim 2, characterized in that: In the step of calculating the rotation speed of the motor, the electrical rotation speed of the motor is calculated using the following mathematical formula: T Hall_update =T Hall -T Hall_old ω r : Electrical rotation speed of the motor [rad / s], T Hall_update : The time required for the Hall sensor value to change, T Hall : The time point when the value of the Hall sensor changes, T Hall_old : The time point when the value of the previous Hall sensor changes.

4. The motor control method according to claim 2, characterized in that: After the step of calculating the rotation speed of the motor, the method further includes the step of determining whether the change in the rotation speed of the motor is less than a predetermined reference change. When the change in the motor rotation speed is less than a predetermined reference change, the ideal position of the motor rotor and the current position of the motor rotor are calculated.

5. The motor control method according to claim 1, characterized in that: In the step of calculating the ideal position of the motor rotor, the ideal position of the motor rotor is calculated based on the time point when the signal of the Hall sensor changes.

6. The motor control method according to claim 5, characterized in that: In the step of calculating the ideal position of the motor rotor, the ideal position of the motor rotor is calculated using the following mathematical formula: θ Hall : Current position angle of the Hall sensor [deg], θ Edge : The ideal position angle at the time when the Hall sensor signal changes, ω r : The electrical rotation speed of the motor [rad / s], ΔT: The time from the point in time when the signal of the Hall sensor changes.

7. The motor control method according to claim 2, characterized in that: After the step of calculating the rotation speed of the motor, the method further includes the step of determining whether the rotation speed of the motor is above a predetermined reference rotation speed. When the motor rotation speed is equal to or higher than a predetermined reference rotation speed, the ideal position of the motor rotor and the current position of the motor rotor are calculated.

8. The motor control method according to claim 1, wherein: In the step of calculating the ideal position of the motor rotor and the current position of the motor rotor, any time point of the signal change time point of the U phase, W phase or V phase of the Hall sensor is used as the reference time point to calculate the ideal position of the motor rotor and the current position of the motor rotor.

9. The motor control method according to claim 8, characterized in that: In the step of calculating the ideal position of the motor rotor and the current position of the motor rotor, each time the signal change time point of the Hall sensor serving as the reference time point is repeated, the ideal position of the motor rotor and the current position of the motor rotor are synchronized to the ideal position of the motor rotor based on the signal change time point of the Hall sensor serving as the reference time point.

10. The motor control method according to claim 8, characterized in that: In the step of calculating the Hall sensor deflection angle, the Hall sensor deflection angle at the remaining Hall sensor signal change time points except the Hall sensor signal change time point serving as the reference time point is calculated.

11. The motor control method according to claim 8, characterized in that: Before the step of calculating the Hall sensor deflection angle, the method further includes the step of calculating the Hall sensor deflection angle at a time point at which the Hall sensor signal changes as a reference time point. In the step of calculating the Hall sensor deflection angle at the time point of signal change of the Hall sensor as the reference time point, the current applied to the motor is blocked to perform inertia braking, and the calculation is performed based on the d-axis voltage and q-axis voltage of the synchronous coordinate system during inertia braking.

12. The motor control method according to claim 1, characterized in that: After the step of calculating the Hall sensor deflection angle, the method further includes a step of controlling the motor based on an actual motor rotor position calculated by compensating for the calculated Hall sensor deflection angle.

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