Rotor position detection method, detection circuit and driving module for three-phase permanent magnet motor

Abstract

The embodiment of the application discloses a rotor position detection method and detection circuit of a three-phase permanent magnet motor, acquires two-phase back electromotive force; performs coordinate transformation on the two-phase back electromotive force to obtain a rotating transformation component, and adjusts an estimated angular velocity according to a real-time value of the rotating transformation component, so that the real-time position of the motor rotor can be obtained, and the accuracy of the position of the motor rotor is ensured.

Description

Technical Field

[0001] This application relates to the field of electronic circuits, specifically to a rotor position detection method, detection circuit, and drive module for a three-phase permanent magnet motor. Background Technology

[0002] In existing technologies, three-phase permanent magnet motors require sensorless control to reduce control costs and save installation space for position sensors. The most common method for sensorless control is to determine the motor position by observing the motor's back electromotive force.

[0003] The existing solution is to observe the back electromotive force of one phase by detecting the single-phase current and update the rotor position θ0 at the zero-crossing point of the back electromotive force. This method can only ensure that the rotor position is relatively accurate only at the zero-crossing point of the back electromotive force in each electrical cycle. The other position angles are calculated by θ=θ0+ωt, which will lead to a large difference between the angle used for control and the actual angle during motor operation. It may also cause error accumulation, resulting in large fluctuations in the steady-state current of the motor and easy loss of transient synchronism. Summary of the Invention

[0004] This application provides a rotor position detection method for a three-phase permanent magnet motor, comprising: acquiring the back electromotive force (EMF) of two phases; performing a Clark transformation on the back EMF of the two phases to obtain the two-phase stationary coordinate components of the EMF in a two-phase stationary coordinate system; performing a Park transformation on the two-phase stationary coordinate components based on an estimated angle to obtain a rotational transformation component, and adjusting the estimated angular velocity according to the real-time value of the rotational transformation component until the rotational transformation component approaches zero, so as to configure the estimated angular velocity at that moment as the actual angular velocity; and performing an integral operation on the estimated angular velocity to obtain the actual angle of the rotor.

[0005] On the other hand, this application embodiment also provides a rotor position detection circuit for a three-phase permanent magnet motor, including: a back electromotive force (EMF) generation module for acquiring the back EMF of two phases; a Clark transformation module for performing a Clark transformation on the back EMF of the two phases to obtain the two-phase stationary coordinate components of the EMF in the two-phase stationary coordinate system; a feedback adjustment module for performing a Park transformation on the two-phase stationary coordinate components based on the estimated angle to obtain a rotational transformation component, and adjusting the estimated angular velocity according to the real-time value of the rotational transformation component until the rotational transformation component approaches zero, so as to configure the estimated angular velocity at that moment as the actual angular velocity; and an integrator for performing an integral operation on the estimated angular velocity to obtain the actual angle of the rotor.

[0006] This application provides a rotor position detection method and detection circuit for a three-phase permanent magnet motor. It can obtain the real-time angular position information of the motor rotor through coordinate transformation and loop feedback adjustment, thereby ensuring the accuracy of the motor rotor position, reducing error accumulation, reducing motor current fluctuations, and reducing problems such as transient step loss. Attached Figure Description

[0007] The above and other objects, features, and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0008] Figure 1 This is a circuit diagram of a three-phase permanent magnet motor system according to an embodiment of this application;

[0009] Figure 2 This is a structural block diagram of a rotor position detection circuit for a three-phase permanent magnet motor according to an embodiment of this application;

[0010] Figure 3 This is another structural block diagram of the rotor position detection circuit of the three-phase permanent magnet motor according to an embodiment of this application. Detailed Implementation

[0011] The present application is described below based on embodiments, but it is not limited to these embodiments. In the detailed description of the present application below, certain specific details are described in detail. Those skilled in the art can fully understand the present application without these details. To avoid obscuring the substance of the present application, well-known methods, processes, flows, elements, and circuits are not described in detail.

[0012] Those skilled in the art will understand that the accompanying drawings provided herein are for illustrative purposes and are not necessarily drawn to scale.

[0013] It should be understood that, in the following description, "circuit" refers to a conductive loop consisting of at least one element or sub-circuit connected by an electrical or electromagnetic connection. When an element or circuit is said to be "connected" to another element, or when an element / circuit is said to be "connected" between two nodes, it can be a direct connection or a connection to another element, or there may be intermediate elements. The connection between elements can be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly connected" to another element, it means that there are no intermediate elements between them.

[0014] Unless the context explicitly requires it, words such as "including," "etc." throughout the application should be interpreted as having the meaning of "including but not limited to," rather than "exclusive" or "exhaustive."

[0015] In the description of this application, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0016] Figure 1 This is a circuit diagram of a three-phase permanent magnet motor system according to the present invention. Figure 1 As shown, the three-phase permanent magnet motor system includes a three-phase permanent magnet motor 12, a rotor position detection circuit 11 for the three-phase permanent magnet motor, a control circuit 13, and a three-phase inverter circuit 14. The rotor position detection circuit 11 and the control circuit 13 of the three-phase permanent magnet motor constitute the drive module of the three-phase permanent magnet motor.

[0017] In this embodiment, the three-phase permanent magnet motor 12 is illustrated using a brushless DC motor as an example. Figure 1 As shown, a brushless DC motor is equivalent to a three-phase structure consisting of three stator windings, a, b, and c. The three phases of the brushless DC motor are symmetrical, with each phase consisting of a corresponding phase resistance, phase inductance, and back electromotive force. Here, the phase resistance is set to Ra = Rb = Rc, and the phase inductance to La = Lb = Lc, where Ea, Eb, and Ec are the back electromotive forces of phases a, b, and c, respectively.

[0018] The control circuit 13 is used to obtain the actual angle information of the motor rotor according to the rotor position detection circuit of the three-phase permanent magnet motor, and then generate the PWM chopping duty cycles PWMa, PWMb and PWMc of the three-phase bridge arm according to the motor rotor position and DC bus voltage, thereby controlling the PWM chopping duty cycle of the three-phase bridge arm.

[0019] The three-phase inverter circuit 14 is controlled by the PWM chopping duty cycles PWMa, PWMb, and PWMc of the three-phase bridge arms to ensure that the drive current of the three-phase permanent magnet motor is a sinusoidal current. Specifically, as an example, in this embodiment, the drive circuit 24 is composed of a three-phase inverter circuit. Transistors Q1 and Q2, Q3 and Q4, and Q5 and Q6 serve as the switching transistors for the upper and lower bridge arms of the a-phase stator winding, the upper and lower bridge arms of the b-phase stator winding, and the upper and lower bridge arms of the c-phase stator winding, respectively. The transistors Q1 to Q6 are controlled by the PWM chopping duty cycles PWMa, PWMb, and PWMc of the three-phase bridge arms to ensure that one of a, b, and c is connected to the positive terminal of the DC bus voltage Udc, another is connected to the negative terminal of the DC bus voltage Udc, and the third is in a de-energized state. It can be understood that each of transistors Q1 to Q6 has a freewheeling diode connected in parallel. Therefore, the control circuit 23 can control the drive signal output by the drive circuit 24 to the brushless DC motor by controlling the PWM (pulse width modulation) value of each transistor.

[0020] This application provides a rotor position detection circuit for a three-phase permanent magnet motor and a corresponding detection method thereof. The rotor position detection circuit for the three-phase permanent magnet motor is as follows: Figure 2 As shown, the system includes a back EMF generation module 112, a Clark transformation module 113, a feedback adjustment module 114, and an integrator 115. The back EMF generation module 112 acquires the back EMF of the two phases at the sampling time. The Clark transformation module 113 performs a Clark transformation on the back EMF of the two phases to generate the two-phase stationary coordinate components of the EMF in the two-phase stationary coordinate system. The feedback adjustment module 114 performs a Park transformation on the two-phase stationary coordinate components based on the estimated angle to obtain a rotational transformation component, and adjusts the estimated angular velocity according to the real-time value of the rotational transformation component until the rotational transformation component approaches zero, thus configuring the estimated angular velocity at the moment when the rotational transformation component approaches zero as the actual angular velocity. The integrator 115 performs an integration operation on the estimated angular velocity to obtain the actual angle of the rotor.

[0021] As an example, in this embodiment, the back electromotive force (EMF) generation module 112 generates the back EMF for the corresponding two phases based on the difference between the sum of the phase voltage of the corresponding phase, the voltage across the phase resistance, and the voltage across the phase inductance. Specifically, the relationship between the back EMF and the voltage, current, phase resistance, and phase inductance can be obtained from the motor voltage equation as shown in equation (1):

[0022]

[0023] In equation (1), Let be the back electromotive force of phase a. The phase voltage signal of phase a. Let I be the phase resistance of phase a, and Ia be the sampled signal of the phase current of phase a. Let be the phase inductance of phase a. Let be the back electromotive force of phase a. The phase voltage signal of phase a Subtract the phase resistance of phase a Phase inductance of phase a The voltage on the phase a is such that the phase voltage signal of phase a at each moment can be calculated or obtained through detection / sampling. Phase current of phase a The back electromotive force of phase a can then be calculated. .

[0024] Similarly, as long as the phase voltage signal of phase b at each moment can be calculated or obtained through detection / sampling, Phase current of phase b The back electromotive force of phase b can then be calculated. :

[0025]

[0026] In equation (2), Let Ub be the back electromotive force of phase b, Ub be the phase voltage signal of phase b, and Rb be the phase resistance of phase b. This is the sampling signal of the phase current of phase b. Let be the phase inductance of phase b.

[0027] Alternatively, the back electromotive force Ec of phase c can be calculated as long as the phase voltage signal Uc and the phase current Ic of phase c at each moment can be obtained through detection / sampling.

[0028] The phase voltage of phase a can be calculated from the PWM chopper duty cycles PWMa, PWMb, and PWMc of the three-phase bridge arms and the detected DC bus voltage Udc. The calculation formula is as follows:

[0029] (3)

[0030] In formula (2) The voltage of phase a of the motor. This is the DC bus voltage. PWMb and PWMc are the PWM chopping duty cycles of phases a, b, and c in the three-phase bridge arm. Similarly, the phase voltage of phase b is:

[0031] (4)

[0032] As an example, the phase a current can be reconstructed from the bus current sampled by the sampling resistor; the phase a resistance and inductance are known or can be measured by instruments; the voltage drop across the inductor involves the derivative of the current, and the derivative term can be obtained in a discrete control system using the following formula:

[0033]

[0034] Where Ts is the system sampling period, Ia[kTs] is the current sampled at time kTs, and Ia[(k-1)Ts] is the current sampled at time (k-1)Ts. The current differential is calculated from these values. Substituting equations (3) and (5) into equation (1), the discretized back electromotive force a is calculated as follows:

[0035]

[0036]

[0037] Similarly, the phase b current can be reconstructed from the bus current sampled by the sampling resistor; the phase b resistance and inductance are known or can be measured by instruments; the voltage drop across the inductor involves the derivative of the current, and the derivative term can be obtained in a discrete control system using the following formula:

[0038]

[0039] Substituting equations (4) and (7) into equation (2), we can obtain the following formula for calculating the discretized back electromotive force b:

[0040]

[0041] (8)

[0042] The back electromotive force of phase a and phase b of the motor at the sampling time can be calculated using formulas (6) and (8). and .

[0043] And the back electromotive force of phases a, b, and c , and Satisfy the following formula:

[0044] (9)

[0045] The back electromotive force of the two phases is subjected to Clark transformation, and the stationary coordinate components of the electromotive force in the stationary coordinate system are obtained by formula (9). and :

[0046]

[0047]

[0048] in, , It is related to the rotor position angle θ, and its expression is:

[0049]

[0050]

[0051] in, ω is the back electromotive force coefficient, ω is the rotor angular velocity, and θ is the rotor angle.

[0052] In this embodiment, as an example, the process of obtaining rotational transformation components by performing Park transformation on the two-phase stationary coordinate components based on the estimated angle includes: performing sine and cosine transformations on the estimated angle to obtain sine transformation quantities and cosine transformation quantities; and performing Park transformation on the two-phase stationary coordinate components according to the sine transformation quantities and the cosine transformation quantities.

[0053] like Figure 3The diagram shows the structural block diagram of a three-phase permanent magnet motor rotor position detection circuit. The circuit also includes a delta converter 116. The delta converter 116 receives the estimated angle output from the integrator 115 and performs sine and cosine transformations on the estimated angle θ0 to obtain the sine transformation quantity sinθ0 and the cosine transformation quantity cosθ0. These quantities are then output to the Park transformation module in the feedback adjustment module. The feedback adjustment module 114 includes a Park transformation module and a PI controller. The Park transformation module performs a Park transformation on the two-phase stationary coordinate components based on the estimated angle to generate a rotational transformation component. The PI controller uses the rotational transform component. The input signal is the estimated angular velocity ω0, and the output signal is the rotational transformation component. The real-time value adjusts the estimated angular velocity ω0; when the rotational transformation component When the value approaches zero, the output signal ω0 at that moment is configured as the actual angular velocity.

[0054] It should be noted that, in Figure 3 In this circuit, the feedback adjustment module 114, integrator 115, and triangular converter 116 can be considered as a phase-locked loop (PLL). The PLL performs closed-loop feedback adjustment on the estimated angle θ0 to converge the estimated angle θ0 of the rotor to the actual angle θ of the rotor. The integrator 115 integrates the estimated angular velocity ω0 to obtain the estimated angle θ0 of the rotor. The rotational transformation component... When the value approaches zero, the estimated angle θ0 is equal to the actual angle of the rotor.

[0055] like Figure 3 As shown, as an example, the Park transformation module receives the stationary coordinate component of the electromotive force obtained from equations (12) and (13). and The estimated angle θ0 output by the integrator is transformed by trigonometric transformation to obtain sinθ0 and cosθ0. The two-phase coordinate system components of the electromotive force and the sinθ0 and cosθ0 are then subjected to Park transformation according to equation (14) to obtain the rotational transformation component of the electromotive force. .

[0056] Based on the estimated angle, the two-phase stationary coordinate system components of the electromotive force in equations (12) and (13) are subjected to Park transformation to obtain the rotation transformation components of the rotating coordinate system of the electromotive force:

[0057]

[0058] Substituting equations (12) and (13) into equation (14), we get:

[0059]

[0060] like Figure 3 As shown, the estimated angle is adjusted via closed-loop feedback through a phase-locked loop so that the rotational transformation component... When it is 0, When θ0 = θ, the estimated angle θ0 of the rotor is converged to the actual angle θ of the rotor, and the real-time actual angle of the rotor is the estimated angle θ0.

[0061] The adjustment of the estimated angle via the PI controller includes: adjusting the rotational transformation component. The input signal is the estimated angular velocity ω0, and the output signal is the estimated angular velocity ω0. The estimated angular velocity ω0 is adjusted based on the real-time value of the rotational transformation component; when the rotational transformation component... When the value approaches zero, the estimated angular velocity ω0 output by the PI controller at that moment is configured as the actual angular velocity ω.

[0062] In this embodiment, the regulator equation of the PI regulator is:

[0063]

[0064] in, For proportional gain, is the integration time constant.

[0065] if <0 (θ0 lags behind θ), the PI controller will increase the output estimated angular velocity ω0, thereby accelerating the growth of the estimated angle θ0 to catch up with the actual angle θ. If When the angular velocity ω0 > 0 (θ0 leads θ), the PI controller decreases the output of the estimated angular velocity ω0, thereby slowing down the growth of the estimated angle θ0, waiting for the actual angle θ. When When ω = 0, the PI controller outputs a stable estimated angular velocity ω0, which is equal to the actual angular velocity ω.

[0066] In addition, the rotor position detection circuit of the three-phase permanent magnet motor may also include a sampling module to obtain sampling signals that represent the phase currents of two phases and / or phase voltage signals that represent two phases, and input the sampled signals to the back electromotive force generation module, so as to obtain the back electromotive force of the corresponding phase based on formula (6) or (8).

[0067] It should be noted that in this embodiment, the detection of phase a and phase b is used as an example. In other embodiments, it can also be phase a and phase c or phase b and phase c, any two of the three phases.

[0068] In summary, this application provides a rotor position detection method and detection circuit for a three-phase permanent magnet motor. The method involves acquiring the back electromotive force (EMF) of two phases; performing a Clark transformation on the back EMF to obtain the two-phase stationary coordinate components of the EMF in a two-phase stationary coordinate system; performing a Park transformation on the two-phase stationary coordinate components based on an estimated angle to obtain a rotational transformation component; adjusting the estimated angular velocity according to the real-time value of the rotational transformation component until the rotational transformation component approaches zero, thus configuring the estimated angular velocity at that moment as the actual angular velocity; and integrating the estimated angular velocity to obtain the real-time angle signal of the rotor. This method enables the real-time angular position information of the motor rotor to be obtained through coordinate transformation and loop feedback adjustment, thereby ensuring the accuracy of the motor rotor position, reducing error accumulation, reducing motor current fluctuations, and minimizing transient synchronism issues.

[0069] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for detecting the rotor position of a three-phase permanent magnet motor, characterized in that, include: Obtain the back electromotive force of the two phases; The back electromotive force of the two phases is subjected to Clark transformation to obtain the two-phase stationary coordinate components of the electromotive force in the two-phase stationary coordinate system. The two-phase stationary coordinate components are transformed by Park based on the estimated angle to obtain the rotational transformation component. The estimated angular velocity is adjusted according to the real-time value of the rotational transformation component. When the rotational transformation component approaches zero, the estimated angular velocity at that moment is configured as the actual angular velocity. The estimated angular velocity is integrated to obtain the actual angle of the rotor.

2. The detection method according to claim 1, characterized in that, Based on the estimated angle, the Park transformation of the two-phase stationary coordinate components yields the rotational transformation components, including: The estimated angle is subjected to sine and cosine transformations to obtain the sine transformation quantity and the cosine transformation quantity; Based on the sine transform and the cosine transform, the two-phase stationary coordinate components are subjected to Park transform.

3. The detection method according to claim 2, characterized in that, The rotational transformation component is configured as follows: Wherein, θ0 is the estimated angle. These are the two-phase stationary coordinate components.

4. The detection method according to claim 1, characterized in that: When the rotational transformation component is less than 0, the growth of the estimated angle is accelerated by increasing the estimated angular velocity; when the rotational transformation component is greater than 0, the growth of the estimated angle is slowed down by decreasing the estimated angular velocity.

5. The detection method according to claim 1, characterized in that: The back electromotive force of a phase is generated based on the difference between the phase voltage, the voltage across the phase resistor, and the voltage across the phase inductor.

6. The detection method according to claim 5, characterized in that, The phase voltage of the corresponding phase is calculated using the following formula: In the formula, Udc is the DC bus voltage, PWMa, PWMb, and PWMc are the PWM chopping duty cycles of phases a, b, and c in the three-phase bridge arm, respectively; Ux is the phase voltage of phase a when Ua is used, and PWM is the phase voltage of phase a. X This corresponds to PWMa; when Ux is Ub, it represents the phase voltage of phase b, PWM X This corresponds to PWMb; when Ux is Uc, it is the phase voltage of phase c, PWM X This corresponds to PWMc.

7. A rotor position detection circuit for a three-phase permanent magnet motor, characterized in that, include: Back EMF generation module, used to obtain the back EMF of two phases; The Clark transformation module is used to perform Clark transformation on the back electromotive force of two phases to obtain the two-phase stationary coordinate components of the electromotive force in the two-phase stationary coordinate system. The feedback adjustment module performs a Park transformation on the two-phase stationary coordinate components based on the estimated angle to obtain a rotational transformation component, and adjusts the estimated angular velocity according to the real-time value of the rotational transformation component. When the rotational transformation component approaches zero, the estimated angular velocity at that moment is configured as the actual angular velocity. An integrator performs an integral operation on the estimated angular velocity to obtain the actual angle of the rotor.

8. The detection circuit according to claim 7, characterized in that: The feedback adjustment module includes a Park transformation module and a PI regulator; The Park transformation module performs a Park transformation on the two-phase stationary coordinate components based on the estimated angle to generate a rotational transformation component. The PI controller takes the rotational transformation component as the input signal and the estimated angular velocity as the output signal, and adjusts the estimated angular velocity according to the real-time value of the rotational transformation component; when the rotational transformation component approaches zero, the output signal at that moment is configured as the actual angular velocity.

9. The detection circuit according to claim 8, characterized in that: The rotational transformation component is configured as follows: Wherein, θ0 is the estimated angle. These are the two-phase stationary coordinate components.

10. The detection circuit according to claim 8, characterized in that: When the rotational transformation component is less than 0, the PI controller increases the output of the estimated angular velocity, thereby accelerating the growth of the estimated angle; when the rotational transformation component is greater than 0, the PI controller decreases the output of the estimated angular velocity, thereby slowing down the growth of the estimated angle.

11. The detection circuit according to claim 8, characterized in that: The rotor position detection circuit also includes a triangular transformer, which receives the estimated angle output by the integrator, performs sine and cosine transformations on the estimated angle, and outputs the sine and cosine transformation quantities to the feedback adjustment module.

12. The detection circuit according to claim 7, characterized in that: The rotor position detection circuit of the three-phase permanent magnet motor also includes a sampling module to obtain sampling signals that represent the phase currents of two phases respectively.

13. A three-phase permanent magnet motor drive module, characterized in that, include: The rotor position detection circuit of the three-phase permanent magnet motor according to any one of claims 7-12; as well as, The control circuit is used to control the PWM chopping duty cycle of the three-phase bridge arm based on the actual angle of the rotor obtained by the rotor position detection circuit.

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