Dynamic motor coil control method

Abstract

A method for controlling an electric machine, the electric machine comprising a rotor and a stator, the stator comprising a plurality of coils isolated from each other. The method comprises the following steps: applying a dynamic adjustable sinusoidal current to each motor coil; obtaining an electrical parameter for each motor coil, the electrical parameter being an average voltage over the coil or an instantaneous voltage over the coil; and utilizing a feedback-based vector control algorithm. The algorithm receives the electrical parameter and the applied sinusoidal current for each motor coil to calculate a target current vector, the target current vector determined based on the electrical parameter and the applied sinusoidal current for each motor coil. The method further involves dynamically adjusting, for each motor coil, the sinusoidal current applied to that motor coil based on the target current vector.

Description

Technical Field

[0001] This invention relates to the field of motor control systems, and more specifically to methods and apparatus for controlling the operation of motors. Background Technology

[0002] In the field of motor control, particularly for applications involving stepper motors and brushless DC (BLDC) motors, the pursuit of efficiency, accuracy, and reliability is constant. Traditional methods for controlling these motors involve open-loop systems or basic closed-loop systems that do not fully utilize the potential of modern electronics and control theory to optimize motor performance.

[0003] One of the main challenges in this field is achieving high precision and efficiency in the dynamic control of motor speed, torque, and position. In conventional systems, control strategies typically rely on fixed parameters and do not adapt in real-time to changes in load or desired performance outcomes. This can lead to suboptimal motor performance, including excessive energy consumption, insufficient torque generation, or inadequate control over motor speed and position. Furthermore, these traditional control methods may not adequately compensate for inherent motor characteristics or external disturbances, resulting in reduced reliability and increased wear on the motor and associated mechanical components.

[0004] Another significant challenge is the detection and prevention of motor stall, as well as the accurate estimation of the motor's rotor position. In many applications, the ability to rapidly detect stall conditions and accurately estimate rotor position without the need for additional sensors can significantly enhance the overall performance and reliability of the system. However, conventional control methods often struggle to provide this level of performance, especially under dynamically changing operating conditions.

[0005] Furthermore, acoustic noise and heat generation associated with motor operation are concerns in many applications. Reducing these factors not only improves the user experience but also contributes to the lifespan and reliability of the motor and the equipment it powers. However, traditional motor control technologies often fail to effectively address these issues, resulting in noisier operation and higher temperatures.

[0006] Despite advancements in motor control technology, including the development of more sophisticated open-loop and closed-loop control systems, a significant need for further innovation remains. The challenges of optimizing motor performance under varying operating conditions, improving energy efficiency, reducing acoustic noise and heat generation, and enhancing reliability and responsiveness remain prominent. Therefore, the field of motor control continues to seek advancements that can address these challenges, paving the way for more efficient, reliable, and high-performance motor control systems. Summary of the Invention

[0007] The objective of embodiments of the present invention is to enhance the dynamic response, energy efficiency, and / or stall detection of a motor by dynamically adjusting the frequency and / or amplitude and / or phase of the sinusoidal current for each coil based on the obtained coil voltage. According to the invention, this objective is achieved by a method for controlling a motor, which involves: applying a dynamically adjustable sinusoidal current to each motor coil, and using a feedback-based vector control algorithm to calculate a target current vector and adjusting the current applied to each coil based on the calculated target current vector.

[0008] In a first aspect, the present invention relates to a method for controlling an electric motor, the motor comprising a rotor and a stator, the stator comprising a plurality of coils isolated from each other, the method comprising:

[0009] A sinusoidal current is applied to each motor coil, wherein the sinusoidal current is dynamically adjustable;

[0010] Obtain the electrical parameters for each motor coil, where for each motor coil, the electrical parameter is either the average voltage across the coil or the instantaneous voltage across the coil;

[0011] A feedback-based vector control algorithm is used, which receives electrical parameters for each motor coil and an applied sinusoidal current to calculate a target current vector, wherein the target current vector is determined based on the electrical parameters for each motor coil and the applied sinusoidal current.

[0012] Based on the target current vector, the sinusoidal current applied to each motor coil is dynamically adjusted.

[0013] In embodiments of the invention, the average voltage can be measured within the modulation cycle as current is applied through modulation. This allows for accurate voltage measurement synchronized with current modulation.

[0014] In embodiments of the invention, the method may further include the steps of: estimating the rotor position based on the calculated target current vector and the obtained voltage; and using the estimated rotor position to convert the target current vector into a target current value for each coil. This achieves accurate rotor position tracking for optimal current control.

[0015] In embodiments of the present invention, the feedback-based vector control algorithm can additionally use predefined motor parameters to calculate the target current vector. Utilizing known motor characteristics improves the accuracy of the current vector calculation.

[0016] In embodiments of the invention, dynamically adjusting the sinusoidal current for each motor coil may include dynamically adjusting the amplitude, and / or phase, and / or frequency of the sinusoidal current based on a target current vector. This allows for real-time optimization of the motor current to achieve the desired performance.

[0017] In a second aspect, the present invention relates to a motor control device for controlling an electric motor, the electric motor including a rotor and a stator, the stator including a plurality of coils isolated from each other, the motor control device comprising:

[0018] A current controller is configured to apply a sinusoidal current to each motor coil, wherein the sinusoidal current is dynamically adjustable;

[0019] The feedback module is configured to obtain electrical parameters for each motor coil, wherein for each motor coil, the electrical parameters are the average voltage across the coil or the instantaneous voltage across the coil;

[0020] The control module is configured to execute a feedback-based vector control algorithm that receives electrical parameters and an applied sinusoidal current for each motor coil, calculates a target current vector based on the electrical parameters and the applied sinusoidal current for each motor coil, and dynamically adjusts the sinusoidal current applied to that motor coil based on the target current vector for each motor coil.

[0021] In embodiments of the invention, the feedback module can be configured to obtain an average voltage by averaging the voltage over a modulation cycle when current is applied via modulation. This provides an efficient method for measuring coil voltage.

[0022] In embodiments of the invention, the control module may be further configured to: estimate the rotor position based on the calculated target current vector and the obtained voltage; and use the estimated rotor position to convert the target current vector into a target current value for each coil. Combining rotor position estimation enhances the dynamic performance of the motor control.

[0023] In embodiments of the present invention, the control module can use predefined motor parameters to calculate the target current vector. More precise current control is achieved by utilizing motor specifications.

[0024] In embodiments of the invention, the control module can be configured to dynamically adjust the amplitude, and / or phase, and / or frequency of a sinusoidal current based on a target current vector. This allows the current to be optimized in real time to achieve the desired motor operation.

[0025] In a third aspect, the present invention relates to a motor control system comprising:

[0026] An electric motor includes a rotor and a stator, the stator comprising multiple coils isolated from each other.

[0027] And a motor control device according to any embodiment of the second aspect.

[0028] In embodiments of the present invention, the motor may be a stepper motor. The disclosed control method is well-suited for precise positioning control of stepper motors.

[0029] In embodiments of the invention, the motor may be a bipolar stepper motor. The bipolar stepper motor benefits from the enhanced current control provided by the present invention.

[0030] In embodiments of the present invention, the motor may be a brushless DC motor. Vector control algorithms can optimize the performance of the BLDC motor.

[0031] In an embodiment of the present invention, the motor may be a 3-phase brushless DC motor.

[0032] The advantages of embodiments of the present invention lie in the ability to dynamically adjust the sinusoidal current applied to each motor coil based on a calculated target current vector, thereby allowing precise control of motor operating parameters such as speed, torque, and / or energy efficiency. A further advantage of embodiments of the present invention is the availability of electrical parameters, including average or instantaneous voltages across the motor coils, enabling feedback-based vector control algorithms to accurately calculate the target current vector. Additionally, embodiments of the present invention offer the advantage that using predefined motor parameters (such as phase resistance and phase inductance) in the feedback-based vector control algorithm allows for more accurate determination of the target current vector, thereby optimizing motor performance. Furthermore, embodiments of the present invention offer the advantage that the ability to dynamically adjust the amplitude, phase, or frequency of the applied sinusoidal current based on the target current vector helps achieve desired operating states, including specific motor speeds, torque levels, and improved energy efficiency. Moreover, embodiments of the present invention offer the advantage that the inclusion of a control module, comprising a microchip with embedded software for executing the feedback-based control algorithm, simplifies the implementation of complex control strategies, making them easier to use in various applications. In alternative embodiments of the present invention, these functions may be hard-coded rather than executed via embedded software. This is a so-called state machine-based solution. The two options are equivalent. Another advantage of embodiments of the invention is that the feedback module, equipped with sensors for measuring electrical parameters of the motor coils, supports the accurate execution of the feedback-based vector control algorithm by providing reliable data. Another advantage of embodiments of the invention is that the motor control device can include a user interface for setting the desired operating state, providing user-friendly interaction with the control system. In embodiments of the invention, filtering processes applied to the obtained electrical parameters and / or the amplitude and / or phase of the applied sinusoidal current reduce noise and improve the accuracy of the target current vector calculation, further enhancing the overall performance of the motor control system.

[0033] Specific and preferred aspects of the invention are set forth in the appended independent and dependent claims. Features from the dependent claims may be suitably combined with features of the independent claims and other dependent claims, and not merely as expressly set forth in the claims.

[0034] The above and other features, characteristics, and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, which illustrate the principles of the invention by way of example. This description is given for illustrative purposes only and does not limit the scope of the invention. The references to the drawings cited below refer to the accompanying drawings. Attached Figure Description

[0035] Figure 1This is a flowchart of an exemplary method for controlling a motor according to an embodiment of the present invention.

[0036] Figure 2 This is a schematic diagram of a motor control device and a motor control system according to an embodiment of the present invention.

[0037] Figure 3 This is an exemplary flowchart illustrating a first exemplary method for obtaining a target current vector using a feedback-based vector control algorithm according to an embodiment of the present invention.

[0038] Figure 4 This is an exemplary flowchart illustrating a second exemplary method for obtaining a target current vector using a feedback-based vector control algorithm according to an embodiment of the present invention.

[0039] Figure 5 This is a schematic diagram of a bipolar stepper motor that can be controlled using a method or apparatus according to an embodiment of the present invention.

[0040] Figure 6 A current controller using a motor control device according to an embodiment of the present invention is shown. Figure 5 The sinusoidal current signal of the coil of the bipolar stepper motor.

[0041] Figure 7 This is a schematic diagram of a BLDC motor that can be controlled using a method or apparatus according to an embodiment of the present invention.

[0042] Any reference numerals in the claims should not be construed as limiting the scope.

[0043] In different accompanying drawings, the same reference numerals refer to the same or similar elements. Detailed Implementation

[0044] The invention will be described with reference to specific embodiments and particular drawings, but the invention is not limited thereto but is defined only by the claims. The described drawings are merely illustrative and not restrictive. In the drawings, some elements may be enlarged and not drawn to scale for illustrative purposes. Dimensions and relative dimensions do not correspond to an actual reduction in scale for the practice of the invention.

[0045] The terms first, second, third, etc., used in the specification and claims are used to distinguish between similar elements and are not necessarily used to describe a temporal, spatial, hierarchical, or any other order. It should be understood that the terms thus used are interchangeable where appropriate, and the embodiments of the invention described herein can operate in an order different from that described or illustrated herein.

[0046] Furthermore, terms such as "top" and "above" in the specification and claims are used for descriptive purposes and not necessarily to describe relative positions. It should be understood that such terms are interchangeable where appropriate, and embodiments of the invention described herein can operate in orientations different from those described or illustrated herein.

[0047] It should be noted that the term "comprising," also used in the claims, should not be construed as limiting itself to the means listed thereafter; it does not exclude other elements or steps. Therefore, the term should be interpreted as specifying the presence of the stated features, integers, steps, or components as mentioned, but does not exclude the presence or addition of one or more other features, integers, steps, or components, or groups thereof. Thus, the scope of the statement "an apparatus comprising means A and B" should not be construed as limiting it to an apparatus consisting only of components A and B. This means that for the present invention, the only relevant components of the apparatus are A and B. Therefore, the term "comprising" covers both the case where only the stated features are present and the case where these features are present along with one or more other features. Therefore, the term "comprising" according to the invention also includes an embodiment where no further components are present. When the term "comprising" is used to describe embodiments in this application, it should be understood that alternative versions of the same embodiments (where the term "comprising" is replaced by "consisting of") are also covered within the scope of the invention.

[0048] Similarly, it is worth noting that the term "coupled" should not be interpreted as limited to direct connection. The terms "coupled" and "connected" and their derivatives can be used. It should be understood that these terms are not intended to be synonyms with each other. Therefore, the scope of the expression "device A coupled to device B" should not be limited to devices or systems where the output of device A is directly connected to the input of device B. This implies that there is a path between the output of A and the input of B, which can include other devices or apparatuses. "Coupled" can mean that two or more elements are in direct physical or electrical contact, or that two or more elements are not in direct contact with each other but still cooperate or interact with each other.

[0049] Throughout this specification, the reference to "an embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment of the invention. Therefore, the phrase "in one embodiment" or "in an embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, but may refer to the same embodiment. Furthermore, in one or more embodiments, as will be apparent to those skilled in the art from this disclosure, particular features, structures, or characteristics may be combined in any suitable manner.

[0050] Similarly, it should be understood that in the description of exemplary embodiments of the invention, for the purpose of simplification and aiding in the understanding of one or more of the various inventive aspects, features of the invention are sometimes grouped together in a single embodiment, drawing, or description thereof. However, this method of disclosure should not be construed as reflecting an intention to claim more features than are expressly recited in each claim. Rather, as reflected in the appended claims, the inventive aspect lies in fewer features than all the features of a single foregoing disclosed embodiment. Thus, the claims appended to the Detailed Description are thereby explicitly incorporated into this Detailed Description, wherein each claim itself represents a separate embodiment of the invention.

[0051] Furthermore, while some embodiments described herein include features found in other embodiments but not in those other embodiments, combinations of features from different embodiments are intended to fall within the scope of the invention and form different embodiments as will be understood by those skilled in the art. For example, any embodiment of the claimed embodiments in the appended claims may be used in any combination.

[0052] Furthermore, some embodiments described herein are described as methods or combinations of elements of methods that can be implemented by a processor of a computer system or by other means of performing functions. Thus, a processor having the necessary instructions for performing the elements of such methods or methods forms means for performing the elements of such methods or methods. Moreover, the elements of the means embodiments described herein are examples of means for performing functions performed by the elements for the purposes of carrying out the invention.

[0053] Numerous specific details are set forth in the description provided herein. However, it should be understood that embodiments of the invention can be practiced without these specific details. In other instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0054] The following terms are provided separately to aid in understanding the invention.

[0055] As used herein, and unless otherwise stated, the term "sinusoidal current" refers to a current that varies with time in the form of a sine wave. Examples of sinusoidal currents include, but are not limited to, currents having a single sine wave form, currents having multiple superimposed sine waves with different frequencies, and currents having a fundamental sine wave and additional harmonic components.

[0056] As used herein, and unless otherwise stated, the term "electrical parameter" refers to a measurable property or characteristic of an electrical system or component. Examples of electrical parameters include, but are not limited to, voltage, current, resistance, capacitance, inductance, power, frequency, and phase.

[0057] As used herein, and unless otherwise stated, the term "feedback-based vector control algorithm" refers to a control algorithm that uses feedback from acquired system parameters to calculate and adjust the control output in the vector space. Examples of feedback-based vector control algorithms include, but are not limited to, field-oriented control (FOC), direct torque control (DTC), and space vector modulation (SVM) based control.

[0058] As used herein, and unless otherwise stated, the term “target current vector” refers to the desired or reference current value represented in vector space, typically representing the magnitude and phase of the desired current.

[0059] As used herein, and unless otherwise stated, the term "modulation cycle" refers to the complete cycle of a modulated waveform used to apply current to a motor coil. Examples of modulation cycles include, but are not limited to, pulse width modulation (PWM) cycles.

[0060] As used herein, and unless otherwise stated, the term "predefined motor parameter" refers to a known or measured characteristic of the motor used in the control algorithm. Examples of predefined motor parameters include, but are not limited to, coil resistance and coil inductance.

[0061] The invention will now be described in detail through several embodiments thereof. It will be apparent that other embodiments of the invention can be configured based on the knowledge of those skilled in the art without departing from the technical teachings of the invention, which is limited only by the terminology of the appended claims.

[0062] In a first aspect, the present invention relates to a method for controlling an electric motor, the motor comprising a rotor (210) and a stator (220), the stator (220) comprising a plurality of coils (221) isolated from each other, the method comprising:

[0063] A sinusoidal current (110) is applied to each motor coil, wherein the sinusoidal current is dynamically adjustable;

[0064] Obtain (120) electrical parameters for each motor coil, wherein for each motor coil, the electrical parameter is the average voltage across the coil or the instantaneous voltage across the coil;

[0065] Using a feedback-based vector control algorithm (130), which receives electrical parameters for each motor coil and an applied sinusoidal current to calculate a target current vector, wherein the target current vector is determined based on the electrical parameters for each motor coil and the applied sinusoidal current;

[0066] Based on the target current vector, the sinusoidal current applied to that motor coil is dynamically adjusted (140) for each motor coil.

[0067] In embodiments of the present invention, the sinusoidal current has a dynamically adjustable frequency and / or amplitude and / or phase.

[0068] In embodiments of the present invention, the sinusoidal current is dynamically adjusted based on the target current vector to achieve a desired operating state. The desired operating state may include at least one of the following: a specific motor speed, a specific motor torque, or a specific motor efficiency.

[0069] In embodiments of the present invention, using an applied sinusoidal current to calculate a target current vector means that the amplitude and / or phase of the applied sinusoidal current are used.

[0070] In embodiments of the present invention, the feedback-based vector control algorithm further includes converting the obtained electrical parameters and the applied sinusoidal current into a format suitable for calculating the target current vector, and adjusting the sinusoidal current signal includes real-time modulation of the frequency and / or amplitude and / or phase of the current signal based on the target current vector. An advantage of embodiments of the present invention is that, by using the feedback-based vector control algorithm, the motor can change its speed more quickly. Another advantage of embodiments of the present invention is that the energy consumption of the motor can be reduced, and the responsiveness and reliability of the motor can be improved.

[0071] In embodiments of the invention, the modulation cycle corresponds to one complete PWM cycle (e.g., 50 μs when it is 20 kHz).

[0072] In embodiments of the present invention, a filtering process can be applied to the obtained electrical parameters and / or the amplitude and / or phase of the applied sinusoidal current to reduce noise and improve the accuracy of the target current vector calculation.

[0073] In embodiments of the present invention, the predefined motor parameters used in the feedback-based vector control algorithm are coil resistance and / or coil inductance.

[0074] Figure 1A flowchart of an exemplary method (100) for controlling a motor (200) is shown. The motor (200) includes a rotor (210) and a stator (220), the stator (220) including a plurality of coils (221) isolated from each other. The method (100) includes applying (110) a sinusoidal current to each motor coil, wherein the sinusoidal current is dynamically adjustable. Electrical parameters for each motor coil are obtained (120), wherein for each motor coil, the electrical parameters are either an average voltage across the coil or an instantaneous voltage across the coil. In embodiments of the invention, the average voltage can be obtained by measurement within a modulation cycle when the current is applied via modulation. This allows for accurate voltage measurement synchronized with the current modulation. The method (100) utilizes (130) a feedback-based vector control algorithm that receives the electrical parameters for each motor coil and the applied sinusoidal current to calculate a target current vector, wherein the target current vector is determined based on the electrical parameters for each motor coil and the applied sinusoidal current. In embodiments of the invention, the method may further include the steps of: estimating (135) the rotor position based on the calculated target current vector and the obtained voltage; and using the estimated rotor position to convert the target current vector into a target current value for each coil (221). This achieves accurate rotor position tracking for optimal current control. In embodiments of the invention, the feedback-based vector control algorithm may additionally use predefined motor parameters to calculate the target current vector. Utilizing known motor characteristics improves the accuracy of the current vector calculation. The sinusoidal current applied to each motor coil is then dynamically adjusted (140) based on the target current vector. In embodiments of the invention, dynamically adjusting (140) the sinusoidal current for each motor coil may include dynamically adjusting the amplitude, and / or phase, and / or frequency of the sinusoidal current based on the target current vector. This allows for real-time optimization of the motor current to achieve the desired performance.

[0075] When current is applied to all motor coils, the average or instantaneous voltage across each coil needs to be known. When the voltage is modulated, the average voltage over the entire modulation cycle needs to be known. When the voltage is analog, the instantaneous voltage needs to be known. In an embodiment of the invention, the current controller (310) is configured to apply a sinusoidal current to each motor coil, which can be done by applying a certain voltage or duty cycle to each motor coil. The applied voltage or duty cycle (representing the applied voltage) can be passed from the current controller (310) to the control module (330) by the feedback module (320). In this case, the feedback module (320) is configured to obtain electrical parameters from the current controller (310) and pass them to the control module (330). When this is not the case, the feedback module (320) can be configured to measure electrical parameters, wherein for each motor coil, the electrical parameter is the average voltage across the coil or the instantaneous voltage across the coil.

[0076] In embodiments of the invention, for each coil, there exists a known current setpoint and an acquired voltage. This information, along with motor parameters, is used to execute the FOC algorithm. The FOC algorithm calculates the desired target current vector, which can be applied to each coil after transformation.

[0077] In a second aspect, the present invention relates to a motor control device (300) for controlling a motor (200), the motor (200) including a rotor (210) and a stator (220), the stator (220) including a plurality of coils (221) isolated from each other. The motor control device includes:

[0078] A current controller (310) is configured to apply a sinusoidal current (110) to each motor coil, wherein the sinusoidal current is dynamically adjustable;

[0079] The feedback module (320) is configured to obtain (120) electrical parameters for each motor coil, wherein for each motor coil, the electrical parameter is an average voltage across the coil or an instantaneous voltage across the coil; and wherein the feedback module (320) may include a sensor for measuring the electrical parameters of the motor coil (221);

[0080] A control module (330) is configured to execute a feedback-based vector control algorithm that receives electrical parameters and an applied sinusoidal current for each motor coil, calculates a target current vector based on the electrical parameters and the applied sinusoidal current for each motor coil, and dynamically adjusts (140) the sinusoidal current applied to that motor coil based on the target current vector for each motor coil. The control module (330) may include a microchip with embedded software for executing the feedback-based control algorithm.

[0081] Figure 2 A schematic diagram of a motor control device (300) for controlling a motor (200) is shown. The motor (200) includes a rotor (210) and a stator (220), the stator (220) including a plurality of coils (221) isolated from each other. The motor control device (300) includes a current controller (310) configured to apply (110) a sinusoidal current to each motor coil, wherein the sinusoidal current is dynamically adjustable. A feedback module (320) is configured to obtain (120) electrical parameters for each motor coil, wherein for each motor coil, the electrical parameter is an average voltage or an instantaneous voltage across the coil. In an embodiment of the invention, the feedback module (320) may be configured to obtain an average voltage by averaging the voltage within a modulation cycle when the current is applied by modulation. This provides an efficient method for measuring coil voltage. The control module (330) is configured to execute a feedback-based vector control algorithm that receives electrical parameters for each motor coil and an applied sinusoidal current to calculate a target current vector based on the electrical parameters for each motor coil and the applied sinusoidal current, and to dynamically adjust (140) the sinusoidal current applied to that motor coil based on the target current vector for each motor coil. In embodiments of the invention, the control module (330) may be further configured to: estimate the rotor position based on the calculated target current vector and the obtained voltage; and use the estimated rotor position to convert the target current vector into a target current value for each coil (221). Combining rotor position estimation enhances the dynamic performance of motor control. In embodiments of the invention, the control module (330) may use predefined motor parameters to calculate the target current vector. More precise current control is achieved using motor specifications. In embodiments of the invention, the control module (330) may be configured to dynamically adjust the amplitude, and / or phase, and / or frequency of the sinusoidal current based on the target current vector. This allows the current to be optimized in real time to achieve the desired motor operation. The motor control device (300) may further include a user interface for setting the desired operating state.

[0082] In a third aspect, the present invention relates to a motor control system (400), the motor control system (400) comprising:

[0083] An electric motor (200) includes a rotor (210) and a stator (220), the stator (220) including a plurality of coils (221) isolated from each other.

[0084] And the motor control device (300) according to any embodiment of the second aspect.

[0085] Figure 2 A motor control system (400) including a motor (200) and motor control equipment (300) is also shown. As will be illustrated in the examples below, the motor may be, for example, a stepper motor, a bipolar stepper motor, a brushless DC motor, or a three-phase brushless DC motor.

[0086] Figure 3 This is an exemplary flowchart illustrating a first exemplary method for obtaining a target current vector using a feedback-based vector control algorithm according to an embodiment of the present invention. The angle and amplitude of the target current are known because they are the output of the FOC algorithm. A dynamically adjustable sinusoidal current (110) is applied to each motor coil. Also known are the obtained (120) coil voltage and predefined (125) motor parameters: coil resistance R and inductance L.

[0087] Figure 3 The exemplary method of the present invention illustrated in the figure utilizes (130) a feedback-based vector control algorithm that receives these values ​​to determine a target current vector. In this exemplary embodiment of the invention, the feedback-based vector control algorithm uses an applied (110) current, a voltage obtained (120) (e.g., by measurement), and predefined (125) motor parameters to obtain an IB angle (observer step), the IB angle is used to obtain a speed (controller step), and the speed is used to obtain the angle of the target current vector (integration step). In an embodiment of the invention, the desired amplitude of the current (i.e., the current amplitude setpoint) and the angle of the target current vector are transformed into a target current for each coil. Thus, a feedback-based vector control algorithm (130) is utilized, which receives electrical parameters for each motor coil and an applied sinusoidal current to calculate the target current vector. The sinusoidal current applied (110) to each motor coil is dynamically adjusted (140) based on the target current vector.

[0088] In the first stage of this exemplary method, an observer is used to calculate the angle between the reverse electromagnetic force (BEMF) and the current vector.

[0089] The obtained coil voltage is transformed to α-β coordinates by Clarke. How this transformation is performed depends on the configuration of the motor coils.

[0090] The following are examples of 4-phase bipolar stepper motors and 3-phase BLDC motors.

[0091] In an embodiment of the present invention, the obtained coil voltage is transformed from the Cartesian coordinate system to the polar coordinate system to obtain the voltage angle ∠V and the peak voltage V. pk .

[0092] ∠V=atan2(V β Vα )

[0093]

[0094] The angle IV between the voltage and current vectors can be calculated using the current phase and amplitude, which are known because they have been set in previous iterations.

[0095] IV = ∠V - ∠L

[0096] The voltage V created by the current through the phase resistance R Calculated:

[0097] V R =I pk R

[0098] The voltage V created by the current through the phase inductor Zy Calculated:

[0099] V Zy =I pk Lω

[0100] In this equation, ω is the (estimated) speed of the rotor, in rad / s.

[0101] Using the IV angle, voltage is mapped onto current to obtain V. Ix and V Iy .

[0102] V Ix =V pk cos(IV)

[0103] V Iy =V pk sin(IV)

[0104] After understanding the voltage and current of the current mapping, the BEMF of the current mapping is calculated:

[0105] B Ix =V Ix -V R

[0106] B Iy =V Iy –V Zy

[0107] The angle IB between BEMF and the current vector is calculated:

[0108] IB = atan2(B Iy B Ix )

[0109] As will be explained in the next example, this IB angle can be used to calculate the rotor angle. In the current example, the IB angle is immediately used as an input to the controller. The target IB angle is typically close to zero, and the controller's output is the velocity of the requested current vector, which is integrated to become the angle of the requested current vector. In embodiments of the invention, a feedback module can transmit the velocity from the current controller to the control module. The feedback module can, for example, be an interface on the current controller that interfaces with the control module.

[0110] The angle and amplitude of the target current vector are transformed into their corresponding target current values ​​for each individual coil (221). This transformation depends on the coil configuration of the motor. Some examples are given below.

[0111] Figure 4 An exemplary flowchart illustrating a second exemplary method, according to an embodiment of the invention, for obtaining a target current vector using a (130) feedback-based vector control algorithm, which employs an applied (110) current, a (120) voltage obtained (e.g., by measurement), and predefined (125) motor parameters. Since the output of this example consists of current in an α-β coordinate system, a polar coordinate transformation is performed on the current target to obtain the current angle ∠I and the peak current I. pk .

[0112] ∠I=atan2(I β ,I α )

[0113]

[0114] With Figure 3 The same method is used to perform the calculation up to the IB angle (observer step). Then, the IB angle, the current angle ∠I, and the 90° offset are used ( Figure 4 (An additional part of the observer step) to calculate the rotor angle θ.

[0115] θ = IB + ∠I - 90°

[0116] If desired, it is possible to continue using this originally calculated rotor angle or filter this result.

[0117] Using rotor angle θ for DC and quadrature current targets (I) d +I qThe setpoint is then subjected to an inverse Parker transformation to generate α-β currents (inverse Parker step). These α-β currents are transformed into their respective target current values ​​for each individual coil (221). How this transformation (transformation into coil setpoint step) is performed depends on the configuration of the motor coils. The sinusoidal current applied (110) to each motor coil is dynamically adjusted (140) based on the target current vector.

[0118] Figure 5 A schematic diagram of a bipolar stepper motor that can be controlled using a method (100) or apparatus (300) according to an embodiment of the invention is shown. The stator configuration shows coils U, V, W, and T. Figure 6 The current controller (310) of the motor control device (300) according to an embodiment of the present invention is shown to... Figure 5 A sinusoidal current is applied to the coils of a bipolar stepper motor. A sinusoidal current with the desired amplitude and frequency is applied through coils U and W. Another sinusoidal current with the desired amplitude and frequency is applied through coils V and T, phase-shifted by 90 degrees compared to the sinusoidal current applied through coils U and W.

[0119] In an exemplary embodiment of the invention, the current controller (310) applies a sinusoidal current signal having a known desired amplitude and frequency between the U and W phases of the bipolar stepper. The current controller (310) also applies (110) another sinusoidal current signal having a known desired amplitude and frequency between the V and T phases of the bipolar stepper, but this second signal is phase-shifted by 90 electrical degrees compared to the first signal between U and W. The current controller may have a different current driver for each phase.

[0120] In the next step, it is necessary to obtain (120) the average or instantaneous voltage (i.e., electrical parameters) between phases U and W, and between phases V and T. When the voltage is modulated, it is necessary to obtain (120) the average voltage over the entire modulation cycle. When the voltage is analog, it is necessary to obtain (120) the instantaneous voltage. This is achieved using a feedback module (320). The feedback module can measure the average or instantaneous voltage, or it can obtain the average or instantaneous voltage from the current controller (310). The current controller (310) may include the functionality of the feedback module (320) and provide information about the voltage or duty cycle.

[0121] After obtaining the voltage value (120), the Clarke transform of the voltage is calculated:

[0122] V α =V U -V W

[0123] V β =V V-V T

[0124] The voltage after Clarke transformation can be used in the FOC algorithm, which calculates the optimal frequency, period, or angle of the applied current signal.

[0125] When using Figure 3 When using the FOC algorithm, the target α-β current can be immediately used as the coil current target. Figure 4 When using the FOC algorithm, the coil current target can be calculated as follows:

[0126] I α =I UW =I pk cos(∠I)

[0127] I β =I VT =I pk sin(∠I)

[0128] In an embodiment of the present invention, the motor (200) may be a brushless DC motor. A vector control algorithm can optimize the performance of the BLDC motor. In an embodiment of the present invention, the motor (200) may be a 3-phase brushless DC motor. Figure 7 A schematic diagram of a BLDC motor that can be controlled using a method (100) or apparatus (300) according to an embodiment of the present invention is shown. The three phases U, V, and W are decoupled from each other.

[0129] In an embodiment of the invention, the current controller (310) is configured to apply a sinusoidal current signal with a 120° phase shift across the three phases. Similarly, the duty cycle or voltage can be read or measured by the feedback module (320) and subjected to a Clarke transform.

[0130] V α =V U

[0131]

[0132] These Clark-transformed voltages can be used in the FOC algorithm in the control module (330).

[0133] When using Figure 4 When using the FOC algorithm, the coil current target can be calculated by performing the inverse Clarke transform: when using Figure 3 When using the FOC algorithm, the coil current target can be calculated as follows:

[0134] I U =I pk cos(∠I)

[0135] I V =Ipk cos(∠I-120°)

[0136] I W =I pk cos(∠I+120°)

[0137] In an embodiment of the present invention, the coils of the motor are current-controlled by hardware logic in a microchip to dynamically adjust the sinusoidal current on each coil.

[0138] In embodiments of the present invention, the objective is to convert an open-loop hardware current-controlled stepper into a closed-loop field-oriented control (FOC) driver by obtaining the obtained coil voltage and adjusting the sinusoidal current frequency and / or amplitude and / or phase.

[0139] It should be understood that while preferred embodiments, specific structures and configurations, and materials have been discussed herein with respect to the device according to the invention, various changes or modifications in form and detail may be made without departing from the scope of the invention. For example, any formulas given above merely indicate procedures that may be used. Functionality may be added to or removed from the block diagrams, and operations may be interchanged between functional blocks. Steps may be added to or removed from the methods described within the scope of the invention.

Claims

1. A method (100) for controlling an electric motor (200), the electric motor (200) including a rotor (210) and a stator (220), the stator (220) including a plurality of coils (221) isolated from each other, the method (100) comprising: A sinusoidal current (110) is applied to each motor coil, wherein the sinusoidal current is dynamically adjustable; Obtain (120) electrical parameters for each motor coil, wherein for each motor coil, the electrical parameter is the average voltage across the coil or the instantaneous voltage across the coil; Using a feedback-based vector control algorithm (130), the feedback-based vector control algorithm receives electrical parameters for each motor coil and an applied sinusoidal current to calculate a target current vector, wherein the target current vector is determined based on the electrical parameters for each motor coil and the applied sinusoidal current; Based on the target current vector, the sinusoidal current applied to that motor coil is dynamically adjusted (140) for each motor coil.

2. The method (100) according to claim 1, wherein, When current is applied through modulation (110), the average voltage (120) is obtained by measurement within the modulation cycle.

3. The method (100) according to claim 1, further comprising the following steps: The rotor position (135) is estimated based on the calculated target current vector and the obtained voltage; And the estimated rotor position is used to convert the target current vector into a target current value for each coil (221).

4. The method (100) according to claim 1, wherein, The feedback-based vector control algorithm further uses predefined motor parameters to calculate the target current vector.

5. The method (100) according to claim 1, wherein, Dynamically adjusting (140) the sinusoidal current for each motor coil includes dynamically adjusting the amplitude, and / or phase, and / or frequency of the sinusoidal current based on the target current vector.

6. A motor control device (300) for controlling a motor (200), the motor (200) including a rotor (210) and a stator (220), the stator (220) including a plurality of coils (221) isolated from each other, the motor control device (300) comprising: A current controller (310) is configured to apply a sinusoidal current (110) to each motor coil, wherein the sinusoidal current is dynamically adjustable; Feedback module (320) is configured to obtain (120) electrical parameters for each motor coil, wherein for each motor coil, the electrical parameters are the average voltage across the coil or the instantaneous voltage across the coil; A control module (330) is configured to execute a feedback-based vector control algorithm that receives electrical parameters and an applied sinusoidal current for each motor coil to calculate a target current vector based on the electrical parameters and the applied sinusoidal current for each motor coil, and to dynamically adjust (140) the sinusoidal current applied to that motor coil based on the target current vector for each motor coil.

7. The motor control device (300) according to claim 6, wherein, The feedback module (320) is configured to obtain an average voltage by averaging the voltage within the modulation cycle when the current is applied through modulation (110).

8. The motor control device (300) according to claim 6, wherein, The control module (330) is further configured to: estimate the rotor position based on the calculated target current vector and the obtained voltage; And the estimated rotor position is used to convert the target current vector into a target current value for each coil (221).

9. The motor control device (300) according to claim 6, wherein, The control module (330) uses predefined motor parameters to calculate the target current vector.

10. The motor control device (300) according to claim 6, wherein, The control module (330) is configured to dynamically adjust the amplitude, and / or phase, and / or frequency of the sinusoidal current based on the target current vector.

11. A motor control system (400), the motor control system comprising: An electric motor (200) comprising a rotor (210) and a stator (220), the stator (220) comprising a plurality of coils (221) isolated from each other. And the motor control device (300) according to claim 6.

12. The motor control system (400) according to claim 11, wherein, The motor (200) is a stepper motor.

13. The motor control system (400) according to claim 12, wherein, The motor (200) is a bipolar stepper motor.

14. The motor control system (400) according to claim 11, wherein, The motor (200) is a brushless DC motor.

15. The motor control system (400) according to claim 14, wherein, The motor (200) is a 3-phase brushless DC motor.

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