Permanent Magnet Synchronous Motor (PMSM) Integrated Position Sensing

Abstract

A permanent magnet synchronous motor (PMSM) includes a hollow cylindrical stator with stator windings and a magnetic rotor with M pole pairs arranged to rotate around an axis of rotation within the stator by a rotor shaft. The stator windings are energized to generate a rotating magnetic field in response to the rotational position of the magnetic rotor. Two or more analog magnetic flux sensors are positioned within the hollow cylindrical stator, concentrically arranged around the axis of rotation around the stator and at a constant mechanical angle relative to each other equal to a constant electrical angle divided by M. The magnetic flux sensors are directly spaced from the magnetic rotor across a radial gap (X), allowing the magnetic rotor's magnetic flux to act unimpeded on the analog magnetic flux sensors. As a result, the sensors output two or more sinusoidal signals, phase-separated by a constant electrical angle, which can be evaluated to determine the rotational position of the magnetic rotor. Sensor integration eliminates the need for additional sensing magnets and the placement of Hall sensors and CCAs external to the motor housing, resulting in a lower-cost and more compact motor package. Integration also facilitates the use of PMSMs in high-temperature or high-shock (high-g) environments, such as in artillery-launched guided munitions or hypersonic missiles.

Description

[Technical Field]

[0001] Priority claims This application claims the benefit of priority to U.S. Patent Application No. 18 / 118,968, filed March 8, 2023, which is incorporated herein by reference in its entirety. [Background technology]

[0002] Field The present disclosure relates to electric motors, particularly permanent magnetic synchronous motors (PMSMs), and more particularly to measuring motor position to feed servo control algorithms that generate multiphase waveforms to move the motor and generate torque. 2. Description of Related Art

[0003] Electric motors that require a controlled armature current waveform (e.g., to rotate smoothly) also require accurate rotor position sensing. Some motors use sensorless techniques, but these techniques do not provide accurate rotor position sensing at very low speeds, and motor starting is not smooth. Other motors cannot inherently use sensorless techniques and must incorporate a rotor position sensing mechanism. Some motors use either an encoder or a resolver, along with associated electronics, to determine rotor position. However, depending on the required resolution, these solutions can be prohibitively expensive within applications requiring low-cost motors.

[0004] In particular, many electric motor applications require smooth rotation and / or precise control. Brushless motors, including permanent magnetic synchronous motors (PMSMs), and those that do not use permanent magnets, such as switched reluctance motors, typically achieve this by using a three-phase sinusoidal current and a precise rotor position detector, usually in the form of an encoder or resolver. The precise rotor position detector ensures that the sinusoidal current remains synchronous with the rotor, thereby avoiding commutation-induced torque ripple. The methods currently used in industry to precisely detect rotor position use encoders and resolvers, which have been known and employed in motor drives for many years.

[0005] Ring magnet and digital Hall effect sensors are often used as rotor position sensing mechanisms in brushless direct current (DC) motor applications where square wave or six-step drives are used. This sensing method has low resolution, typically providing six position steps per electrical cycle when using three sensors. However, this is acceptable because six-step drives do not require high-resolution rotor position sensing. At the same time, these drive methods also do not provide ripple-free torque from the motor, which may make them unacceptable in various applications.

[0006] U.S. Patent No. 6,552,130, "Accurate Rotor Position Sensor and Method Using Magnet and Sensors Mounted Adjacent to the Magnet and Motor," includes a sense ring magnet and two analog Hall-effect sensors. The sense ring is magnetized in a north-south alternating direction with a number of poles corresponding to the number of motor poles. The Hall-effect sensors are positioned to measure magnetic flux tangential to the sense ring. Referring to FIG. 7 of the '130 patent, a sense ring 200 is mounted on a shaft 712 and rotates with a rotor 724 about an axis 714. A Hall-effect sensor 722 is positioned near the sense ring 200. The Hall-effect sensor is preferably positioned at a distance from the sense ring such that the Hall-effect sensor's output waveform is substantially triangular, with a highly linear portion centered at zero magnetic flux between the minimum and maximum waveform peaks. The linear portion of the waveform is decoded using an A / D converter and control software to provide an accurate measurement of rotor position.

[0007] U.S. Patent Application Publication No. 2002 / 0167310, entitled "Angle Transmitter," discloses an angle transmitter integrated with a miniature electric motor that provides a phase-shifted signal. The angle transmitter includes at least one magnetic component having poles arranged alternately on the end surface and at least one sensor positioned opposite the at least one magnetic component. The at least one sensor has at least two sensor elements arranged at an angle relative to each other. The at least two sensor elements are rotated relative to each other by 90° or 60°. The at least two sensor elements intersect each other.

[0008] As shown in Figures 1A-1C herein, the current state of the art for PMSMs is very similar to the sensing configuration of the '130 patent, incorporating sensing magnets and Hall sensors inside the motor, significantly increasing the overall size of the motor assembly and making it impractical in itself. In practice, a permanent magnet 100 (single pole pair) is mounted on the end of a motor shaft 102 outside a motor housing 104 of a PMSM 106. A Hall sensor chip 108 containing a pair of analog Hall sensors is mounted on a card carrying assembly (CCA) 110 adjacent to the permanent magnet 100 and positioned to measure magnetic flux tangential to the permanent magnet 100. The Hall sensors are separated by 90° electrical angle = magnetic angle. The stator windings are energized with a three-phase waveform, generating a rotating magnetic field inside the motor housing 104. This rotating field rotates the motor shaft 102 and permanent magnet 100, which in turn generates a rotating magnetic field (B) 112. The pairs of Hall sensors are positioned so that they measure the magnetic flux from the B field 112 tangential to the dipole magnet 100 .

[0009] As explained in section 502, "Principle of Magnetic Encoder," of "Principle and Advantages of Magnetic Encoder" (Asahi Kasei Microdevices, accessed February 3, 2023), when the motor shaft 102 rotates, the magnetic field 112 generated by the permanent magnet 100 attached to the end of the shaft also rotates. The magnetic field rotates with a constant intensity in the area near the center of the rotation axis. The Hall element detects this change in the magnetic field distribution and converts it into an electrical signal. The Hall element is a magnetic sensor that can only detect the strength of the magnetic field in a single direction. Therefore, to detect the rotational position on the XY rotation plane, a Hall element is required to detect the intensity of the X-axis component (Bx) 114 and a Hall element is required to detect the intensity of the Y-axis component (BY) 116.

[0010] The magnetic field information of the X-axis and Y-axis components converted into electrical signals by the Hall elements is then converted into digital signals by an AD converter. This is then sent to an arithmetic circuit and converted into angle information using trigonometric functions. The planar diagram obtained by combining the mutually orthogonal X-axis and Y-axis components is called a Lissajous figure (or Lissajous waveform). Under a shaft end configuration with no misalignment, the strength of the rotating magnetic field does not change, so the Lissajous figure forms a perfect circle 118. Therefore, the angle output result converted by trigonometric functions has zero error. Furthermore, even if the position of the Hall element detecting the horizontal magnetic field strength is misaligned, the magnetic field input to the Hall element does not change significantly, so the angle error included in the calculation result is small. When the X-axis component is Bx and the Y-axis component is By, the rotation angle θ120 can be obtained as an absolute angle by calculating arctan(BY / Bx).

[0011] U.S. Patent No. 8,896,163, entitled "Electric Micromotor," describes a motor with an outer diameter (D AThe present invention discloses a miniature electric motor (1) having a hollow cylindrical stator (2) with stator coils (8) and a magnetic rotor (4) rotatably disposed within the stator (2) around a rotation axis (16) by a rotor shaft (10). The stator coils (8) can be energized to generate a rotating magnetic field in response to the rotational position of the magnetic rotor (4). A sensor chip (20) having at least one magnetic field sensor (22) is positioned in an area axially adjacent to a front surface of the magnetic rotor (4) and in a plane perpendicular to the rotation axis (16), such that the magnetic field sensor (22) is affected by the magnetic field. As a result, the rotational position of the rotor can be evaluated. As best shown in FIG. 1, the sensor chip (20) is separated from the adjacent front surface of the magnetic rotor (4) by an axial gap (A). As best shown in FIG. 2, the sensor chip (20) is offset from the rotation axis (16) and is outside the hollow cylindrical stator (2). In column 5, line 50, it states, "In the preferred embodiment, it can be seen that the magnetic field of the magnetic rotor 4 passes through several components until it reaches the area of ​​the sensor chip 20. Surprisingly, the magnetic field can still be detected..."

[0012] As shown in particular in FIG. 8 of the '163 patent, the sensor chip 20 preferably has four integrated magnetic field sensors 22, which are particularly designed as Hall effect sensors. The figure shows that all magnetic field sensors 22 shown in FIG. 8 are arranged in the area covering the protrusions of the magnetic rotor 4, and are arranged in a specific, particularly radially symmetrical, peripheral distribution on a reference circle 24 around the elongated rotation axis 16 or rotor shaft 10. The reference circle 24 is located on a diameter D of the rotor shaft 10. W Diameter D located in the area between T and this diameter D W is the inner diameter of the hollow cylindrical magnetic rotor 4 and extends to the outer diameter DR of the magnetic rotor 4. In the preferred embodiment shown in FIG. TA reference circle 24 having a reference radius 24b is located within the outer half of the circular cross section of the magnetic rotor 4. Four magnetic field sensors 22 are preferably arranged radially symmetrically, spaced circumferentially at 90° intervals from each other. Due to their small design size, the sensor chips 20 are arranged inside the cross section enclosed by the return element 6. Summary of the Invention

[0013] The following is a summary to provide a basic understanding of some aspects of the disclosure. This summary is not intended to identify key or critical elements of the disclosure or to delineate the scope of the disclosure. Its sole purpose is to present some concepts of the disclosure in a simplified form as a prelude to the more detailed description and defined claims that are presented later.

[0014] The present disclosure provides position sensing integrated into permanent magnet synchronous motors (PMSMs). Integration eliminates the need for additional sensing magnets and placement of Hall sensors and CCAs external to the motor housing, providing a lower cost and more compact motor package. Integration also facilitates use of PMSMs in high temperature or high shock (high g) environments, such as artillery-launched guided munitions or hypersonic missiles.

[0015] In one embodiment, a PMSM includes a hollow cylindrical stator with stator windings and a magnetic rotor having M pole pairs arranged to rotate about an axis of rotation within the stator by a rotor shaft. The stator windings are energized to generate a rotating magnetic field in response to the rotational position of the magnetic rotor. Two or more analog magnetic flux sensors (e.g., analog Hall effect sensors) are positioned within the hollow cylindrical stator, concentrically arranged about the axis of rotation around the stator and at a constant mechanical angle relative to each other equal to the constant electrical angle divided by M. The magnetic flux sensors are directly spaced apart from the magnetic rotor by a radial gap (X), allowing the magnetic rotor's magnetic flux to act on the analog magnetic flux sensors without impediment. As a result, the sensors output two or more sinusoidal signals separated in phase by a constant electrical angle, which can be evaluated to determine the rotational position of the magnetic rotor.

[0016] In a particular embodiment, the hollow cylindrical stator has an outer diameter greater than 20 mm to allow for the integration of analog flux sensors within the PMSM.

[0017] In general, integrated position sensing is applicable to magnetic rotors having M=1 or more pole pairs, although the integrated flux sensor configuration is particularly applicable to magnetic rotors having two or more pole pairs.

[0018] In one embodiment, two or more analog magnetic flux sensors are positioned at one end of a hollow cylindrical stator adjacent to the stator windings. A magnetic rotor extends beyond the stator windings and is spaced apart directly opposite the two or more analog magnetic flux sensors. This allows for integration of the sensors without affecting the motor design, particularly the stator windings. The sensors are preferably positioned such that their sensing axes are perpendicular to the extended magnetic rotor and are aligned with the rotor's magnetic field. In different embodiments, the sensors can be positioned within a single plane or in different planes perpendicular to the axis of rotation. The sensors can be positioned at both ends of the stator windings, with the magnetic rotor extending beyond both ends of the stator windings.

[0019] In different embodiments, the sensors may be embedded in one or more pockets formed in the hollow cylindrical stator or may be surface mounted to the inner surface of the hollow cylindrical stator.

[0020] In one embodiment, the open ends of the hollow cylindrical stator and two or more analog magnetic flux sensors are contained within an encapsulated stator winding, while allowing the rotor shaft to pass through and rotate. The encapsulation allows for use in high temperature or high shock environments.

[0021] In different embodiments, the number of analog flux sensors can be two or three, with more becoming redundant. Two sensors have a fixed mechanical angle of 90° electrical / m, and three sensors have a fixed mechanical angle of 120° electrical / m. Packaging considerations may require or favor three sensors. L groups of two or three sensors may be used to provide two or three average sinusoidal signals to compensate for different strengths of the rotor magnets. L groups of two or three sensors are arranged at 360 mechanical degrees / m electrical. L=M provides a measurement for each pole. L>M again becomes redundant.

[0022] In one embodiment, two or three sinusoidal signals are evaluated to determine the rotational position of the magnetic sensor, which is then used as an input to determine the waveform used to drive the stator windings to rotate the rotor shaft. A conventional four-quadrant inverse tangent function or angle tracking observer (ATO) can be used to extract the magnetic rotor mechanical angle, which indicates the rotational position of the magnetic rotor, from the sinusoidal signals. The ATO is a closed-loop position estimator with adjustable bandwidth and damping parameters, which reduces noise in the calculated magnetic rotor mechanical angle and improves the accuracy of low-speed position estimation. If three signals are received, they are first converted from three phases to two phases.

[0023] These and other features and advantages of the present disclosure will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0024] [Figure 1A] As described above, a PMSM is shown provided with an external sensing magnet and Hall sensors to extract the mechanical angle of the magnetic rotor. [Figure 1B] 1 shows a PMSM provided with a sensed sinusoidal signal. [Figure 1C] 1 shows a PMSM provided with a conventional four-quadrant inverse tangent function. [Figure 2A] FIG. 1 shows a side view of an embodiment of a PMSM with integrated position sensing showing a pair of flux sensors spaced at a constant mechanical angle of 30° for a constant electrical angle of 90° relative to a rotor magnet with M=3 pole pairs. [Figure 2B] FIG. 1 shows a cross-sectional view of an embodiment of a PMSM with integrated position sensing showing a pair of flux sensors spaced at a constant mechanical angle of 30° for a constant electrical angle of 90° for a rotor magnet with M=3 pole pairs. [Figure 2C] FIG. 1 illustrates an end view of an embodiment of a PMSM with integrated position sensing showing a pair of flux sensors spaced at a constant mechanical angle of 30° for a constant electrical angle of 90° for a rotor magnet with M=3 pole pairs. [Figure 3] 1 is a plot of measured sinusoidal signals separated by a constant electrical angle of 90°. [Figure 4A] FIG. 1 is a schematic diagram of a conventional control algorithm based on a four-quadrant arctangent function for calculating the rotational position of a magnetic rotor relative to a pair of magnetic flux sensors. [Figure 4B] FIG. 10 is a schematic diagram of a variation of a control algorithm using an angle tracking observer (ATO) to calculate the rotational position of the magnetic rotor relative to a pair of magnetic flux sensors. [Figure 5A] FIG. 1 is a side view showing three magnetic flux sensors spaced at a constant mechanical angle of 40° for a constant electrical angle of 120° for a rotor magnet with M=3 pole pairs. [Figure 5B]FIG. 1 is an end view showing three magnetic flux sensors spaced at a constant mechanical angle of 40° by a constant electrical angle of 120° for a rotor magnet with M=3 pole pairs. [Figure 5C] 1 is a plot of measured sinusoidal signals separated by a constant electrical angle of 120. [Figure 6A] FIG. 1 is a schematic diagram of a conventional control algorithm based on a four-quadrant arctangent function that uses a three-phase to two-phase transformation to calculate the rotational position of a magnetic rotor relative to a pair of magnetic flux sensors. [Figure 6B] FIG. 10 is a schematic diagram of a variation of the control algorithm using an angle tracking observer (ATO) that uses a three-phase to two-phase transformation to calculate the rotational position of the magnetic rotor relative to a pair of magnetic flux sensors. [Figure 7] End view showing L=3 pairs of sensors, each pair spaced apart by a group electrical angle of 360 / 3=120°. The sensors in each pair are spaced apart by a constant mechanical angle of 30° for a constant electrical angle of 90°. The measured sinusoidal signals are averaged to compensate for the different strengths of the rotor magnets. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present disclosure provides position sensing integrated into permanent magnet synchronous motors (PMSMs). Integration eliminates the need for additional sensing magnets and placement of Hall sensors and CCAs external to the motor housing, providing a lower cost and more compact motor package. Integration also facilitates use of PMSMs in high temperature or high shock (high g) environments, such as artillery-launched guided munitions or hypersonic missiles.

[0026] A PMSM includes a hollow cylindrical stator with stator windings and a magnetic rotor having M pole pairs (M is one or more) arranged to rotate around an axis of rotation within the stator by a rotor shaft. The stator windings are energized to generate a rotating magnetic field in response to the rotational position of the magnetic rotor. Two or more analog magnetic flux sensors (e.g., analog Hall effect sensors) are positioned within the hollow cylindrical stator, concentrically arranged about the axis of rotation around the stator and at a constant mechanical angle relative to each other equal to the constant electrical angle divided by M. The magnetic flux sensors are directly spaced apart from the magnetic rotor by a radial gap (X), allowing the magnetic rotor's magnetic flux to act on them unimpeded. As a result, the sensors output two or more sinusoidal signals, phase-separated by a constant electrical angle, which can be evaluated to determine the rotational position of the magnetic rotor.

[0027] 2A-2C, 3, and 4A-4B, a two-sensor embodiment of a PMSM 200 with integrated position sensing includes a hollow cylindrical stator 202, suitably having an outer diameter of at least 20 mm, with stator windings 204 and a magnetic rotor 206. The magnetic rotor 206 has M pole pairs 208 (M=1 or more) arranged for rotation about an axis of rotation 210 within the stator by a rotor shaft 212. As shown, the magnetic rotor 206 is a surface-mounted permanent magnet, but may be an internal permanent magnet or a linked-pole permanent magnet. The stator windings are energized to generate a rotating magnetic field 214 in response to the rotational position of the magnetic rotor. Two or more analog magnetic flux sensors 216 and 218 (e.g., analog Hall-effect sensors) are positioned within the hollow cylindrical stator and arranged concentrically about the axis of rotation 210 around the stator and at a fixed mechanical angle 219 relative to each other equal to a fixed electrical angle of 90° divided by M. In this example, M=3, so the constant mechanical angle 219 is 30°. The magnetic flux sensor is spaced directly from the magnetic rotor 206 across a radial gap 220 (X), allowing the magnetic rotor magnetic flux 214 to act unimpeded on the analog magnetic flux sensor 216. As a result, the sensor outputs two or more sinusoidal signals 222 and 224, phase-separated by a constant electrical angle 226, which can be evaluated to determine the rotational position Θ of the magnetic rotor. M 228 can be determined.

[0028] In one embodiment, analog flux sensors 216 and 218 are located at one end of hollow cylindrical stator 202 adjacent to stator windings 204. The sensors are embedded in one or more pockets 230 formed in the stator. If radial air gap 220 is large enough, the sensors may be surface-mounted on the inner surface of the stator. Magnetic rotor 206 extends beyond stator windings 204 and is spaced apart directly opposite the analog flux sensors. This allows for integration of the sensors without affecting the motor design, particularly the stator windings. The sensors are preferably positioned so that their sensing axes 232 are perpendicular to the extended magnetic rotor 206 and align the sensing axes with the rotor's magnetic field 214. In different implementations, the sensors may be positioned in a single plane, as shown herein, or in different planes perpendicular to the axis of rotation. The sensors may be located at both ends of stator windings 204, with the magnetic rotor extending beyond both ends of the stator windings. If the magnetic rotor 206 is not extended, the sensor may be tilted to better align the sensing axis 232 with the rotor's magnetic field 214 .

[0029] The open end of the hollow cylindrical stator 206 and the two analog magnetic flux sensors 216 and 218 are encased in an encapsulant 234, such as epoxy, which seals the stator windings 204 and allows the rotor shaft 212 to rotate through. The encapsulation allows for use in high temperature or high shock environments. Without the encapsulation, the motor and position sensing functions would be limited to approximately 250 gs. With the encapsulation, the motor and position sensing functions can operate at over 5,000 gs and potentially over 20,000 gs.

[0030] The sinusoidal signals 222 and 224 are output from the PMSM 200 to an external controller (not shown), which evaluates the signals and calculates the rotational speed of the magnetic sensor Θ M 228 rotational position is determined, and that rotational position is then used as an input to determine the waveforms that will be used to drive the stator windings to rotate the rotor shaft.

[0031] 4A, in response to the two sinusoidal signals 224 and 226, the controller scales and maps signal 240 to a predetermined range and calculates a four-quadrant arctangent function 242 to generate the magnetic rotor electrical angle that repeats with the number of pole pairs M. The controller then expands magnetic rotor electrical angle 244 and converts the magnetic rotor electrical angle into a magnetic rotor mechanical angle Θ that indicates the rotational position of the magnetic rotor. M 228 (246). This technique is widely known and is described in Faulhaber's Application Note 162 "Analog Hall Sensors" (2021), Method B in Figure 5.

[0032] Referring now to FIG. 4B, the controller is responsive to the two sinusoidal signals 224 and 226 to condition and map the signal 250 to a predetermined range, and implements an angle tracking observer (ATO) 252 to generate the deployed rotor electrical angle and convert the magnetic rotor electrical angle to the magnetic rotor mechanical angle Θ M 228 (246). The ATO is a closed-loop position estimator with adjustable bandwidth and damping parameters, which reduces noise in the calculated magnetic rotor mechanical angle and improves the accuracy of low-speed position estimation. The ATO for resolver interfaces is described in Figures 1 and 5 and Section 3.2 of AN3943, "Using the Resolver Interface eTPU Function," by Freescale Semiconductor (2009). The application of the ATO to determine the rotational position of the magnetic rotor using analog flux sensors in PMSMs is new.

[0033] 5A-5C and 6A-6B, a three-sensor embodiment of a PMSM 300 with integrated position sensing includes a hollow cylindrical stator 302, suitably having an outer diameter of at least 20 mm, with stator windings 304 and a magnetic rotor 306 having M pole pairs 308 (M=1 or greater) and arranged for rotation by a rotor axis 312 around an axis of rotation 310 within the stator. As shown, the magnetic rotor 306 is a surface-mounted permanent magnet, but it could also be an internal permanent magnet or a linked-pole permanent magnet. The stator windings are energized to generate a rotating magnetic field 314 in response to the rotational position of the magnetic rotor. Three analog magnetic flux sensors 316, 317, and 318 (e.g., analog Hall-effect sensors) are positioned within the hollow cylindrical stator and arranged concentrically about the axis of rotation 310 around the stator and at a fixed mechanical angle 319 relative to each other equal to 120° electrical angle divided by M. In this example, M=3, so the constant mechanical angle 319 is 40°. The magnetic flux sensors are spaced directly from the magnetic rotor 306 across a radial gap 320 (X), allowing the magnetic rotor magnetic flux 314 to act unimpeded on the analog magnetic flux sensors 316, 317, and 318. This configuration causes the sensors to output two or more sinusoidal signals 322, 323, and 324, phase-separated by a constant electrical angle 326, which can be evaluated to determine the rotational position Θ of the magnetic rotor. M 328 can be determined.

[0034] As shown, analog flux sensors 316, 317, and 318 are located at one end of the hollow cylindrical stator 302 adjacent to the stator windings 304. The sensors are embedded in respective pockets 330 formed in the stator. If the radial air gap 320 is large enough, the sensors may be surface-mounted on the inner surface of the stator. The magnetic rotor 306 extends beyond the stator windings 304 and is spaced apart directly opposite the analog flux sensors. This allows for integration of the sensors without affecting the motor design, particularly the stator windings. The sensors are preferably positioned so that their sensing axes 332 are perpendicular to the extended magnetic rotor 306 and align the sensing axes with the rotor's magnetic field 314. In this embodiment, the sensors are positioned in different planes perpendicular to the axis of rotation. The sensors may be located at both ends of the stator windings 304, with the magnetic rotor extending beyond both ends of the stator windings. If the magnetic rotor 306 is not extended, the sensor may be tilted to better align the sensing axis 332 with the rotor's magnetic field 314 .

[0035] The open end of hollow cylindrical stator 306 and three analog flux sensors 316, 317, and 318 are encased in an encapsulant 334, such as epoxy, which seals stator windings 304 and allows rotor shaft 312 to rotate through. The encapsulation allows for use in high temperature or high shock environments. Without the encapsulation, the motor and position sensing functions would be limited to approximately 250 gs. With the encapsulation, the motor and position sensing functions can operate at over 5,000 gs and potentially over 20,000 gs.

[0036] The sinusoidal signals 322, 323 and 324 are output from the PMSM 300 to an external controller (not shown) which evaluates the signals to determine the rotational position Θ of the magnetic sensor. M 328 and then uses that rotational position as an input to determine the waveforms that will be used to drive the stator windings to rotate the rotor shaft.

[0037] 6A, the controller responds to the three sinusoidal signals 322, 323, and 324 by scaling and mapping the signal 340 to a predetermined range, performing a three-phase to two-phase transformation (e.g., a Claret transform) 341, and calculating a four-quadrant arctangent function 342 to generate the magnetic rotor electrical angle that iterates over the number of pole pairs M. The controller then expands the magnetic rotor electrical angle 344 and converts the magnetic rotor electrical angle into a magnetic rotor mechanical angle Θ that indicates the rotational position of the magnetic rotor. M Convert to 328 (346).

[0038] 6B, the controller responds to the two sinusoidal signals 322, 323, and 324 by scaling and mapping the signal 350 to a predetermined range, performing a three-phase to two-phase transformation (e.g., a Claret transformation) 352, and implementing an angle tracking observer (ATO) 354 to generate the deployed rotor electrical angle. The deployed rotor electrical angle is converted to the magnetic rotor mechanical angle Θ M 328 (346). The ATO is a closed-loop position estimator with adjustable bandwidth and damping parameters, which reduces noise in the calculated magnetic rotor mechanical angle and improves the accuracy of the low-speed position estimate.

[0039] Referring now to FIG. 7, to compensate for the different strengths of the rotor magnets, two or three analog magnetic flux sensors 700 can be formed into L groups 702, with L instances of each of the two or three sensors. The outputs of the L sensors are averaged together to create two or three sinusoidal waves. The individual sensors are separated by a mechanical angle 704 equal to the electrical angle (depending on the number of sensors) / M. The groups 702 are separated by an electrical angle 706 = 360 mechanical degrees divided by M pole pairs. For L = 1, the two or three sensor configuration defaults to the one shown previously. Typically, L ranges between 2 and M, with anything above M being redundant. As shown here, L = M = 3, so the mechanical angle 704 is 30° for the two sensors and the electrical angle 706 is 120° for the three groups.

[0040] While several exemplary embodiments of the present disclosure have been shown and described, numerous variations and alternative embodiments will occur to those skilled in the art. Such variations and alternative embodiments are contemplated and can be made without departing from the scope of the invention as defined in the appended claims.

Claims

1. A permanent magnet synchronous motor (PMSM), a hollow cylindrical stator having stator windings; a magnetic rotor having M pole pairs arranged to rotate about a rotation axis within the hollow cylindrical stator by a rotor shaft, the magnetic rotor having M pole pairs arranged to rotate about a rotation axis within the hollow cylindrical stator by a rotor shaft, the stator windings being energized to generate a rotating magnetic field according to a rotational position of the magnetic rotor; and two or more analog magnetic flux sensors positioned within the hollow cylindrical stator and arranged concentrically with respect to the axis of rotation around the hollow cylindrical stator and at a constant mechanical angle relative to each other equal to the constant electrical angle divided by M, the analog magnetic flux sensors being directly spaced apart from the magnetic rotor via a radial gap (X) such that magnetic flux of the magnetic rotor acts on the analog magnetic flux sensors unimpeded and outputs two or more sinusoidal signals separated in phase by the constant electrical angle, which signals can be evaluated to determine a rotational position of the magnetic rotor.

2. 10. The PMSM of claim 1, wherein an outer diameter of the hollow cylindrical stator is greater than 20 mm.

3. 2. The PMSM of claim 1, wherein the two or more analog magnetic flux sensors are disposed at one end of the hollow cylindrical stator adjacent the stator windings, and the magnetic rotor extends beyond the stator windings and is spaced apart directly opposite the two or more analog magnetic flux sensors.

4. 4. The PMSM of claim 3, wherein each of the analog magnetic flux sensors has a sensing axis, and the two or more analog magnetic flux sensors are positioned with their sensing axes pointing toward and perpendicular to the magnetic rotor.

5. The PMSM of claim 3 , wherein the two or more analog magnetic flux sensors are arranged in a single plane perpendicular to the axis of rotation.

6. The PMSM of claim 3 , wherein the two or more analog magnetic flux sensors are positioned in different planes perpendicular to the axis of rotation.

7. 4. The PMSM of claim 3, wherein one end of the hollow cylindrical stator and the two or more analog magnetic flux sensors are contained within an enclosed stator winding while allowing the rotor shaft to pass and rotate.

8. The PMSM of claim 1 , wherein the two or more analog magnetic flux sensors are embedded in one or more pockets formed in the hollow cylindrical stator.

9. The PMSM of claim 1 , wherein the two or more analog magnetic flux sensors are surface mounted to an inner surface of the hollow cylindrical stator.

10. 2. The PMSM of claim 1, wherein the permanent magnet synchronous motor includes two analog flux sensors positioned at an electrical angle of 90 degrees relative to each other.

11. 11. The PMSM of claim 10, further comprising: a controller external to the PMSM that is responsive to the two sinusoidal signals to scale and map the signals to a predetermined range, calculate a four-quadrant arctangent function to generate a magnetic rotor electrical angle that repeats with a number M of pole pairs, unfold the magnetic rotor electrical angle, and convert the magnetic rotor electrical angle to a magnetic rotor mechanical angle that indicates the rotational position of the magnetic rotor.

12. 11. The PMSM of claim 10, further comprising: a controller external to the PMSM that is responsive to the two sinusoidal signals to condition and map the signals to a predetermined range, implements an angle tracking observer (ATO) to generate a deployed rotor electrical angle, and converts the deployed rotor electrical angle to a magnetic rotor mechanical angle indicative of the rotational position of the magnetic rotor.

13. 13. The PMSM of claim 12, wherein the ATO is a closed-loop position estimator with adjustable bandwidth and damping parameters to reduce noise in the calculated magnetic rotor mechanical angle and improve accuracy of low-speed position estimation.

14. 10. The PMSM of claim 1, wherein the permanent magnet synchronous motor includes three analog flux sensors having an electrical angle of 120 degrees.

15. 15. The PMSM of claim 14, further comprising: a controller external to the PMSM that is responsive to the three sinusoidal signals to scale and map the signals to a predetermined range, perform a three-phase to two-phase conversion to generate two sinusoidal signals, calculate a four-quadrant arctangent function to generate a magnetic rotor electrical angle that repeats with a number of pole pairs, M, and unfold the magnetic rotor electrical angle to convert the magnetic rotor electrical angle to a magnetic rotor mechanical angle that indicates the rotational position of the magnetic rotor.

16. 15. The PMSM of claim 14, further comprising: a controller external to the PMSM that is responsive to the three sinusoidal signals to condition and map signals to a predetermined range, perform a three-phase to two-phase conversion to generate two sinusoidal signals, implement an angle tracking observer (ATO) to generate a deployed rotor electrical angle, and convert the deployed rotor electrical angle to a magnetic rotor mechanical angle indicative of a rotational position of the magnetic rotor.

17. 17. The PMSM of claim 16, wherein the ATO is a closed-loop position estimator with adjustable bandwidth and damping parameters to reduce noise in the calculated mechanical angle of the magnetic rotor and improve accuracy of low speed position estimation.

18. 10. The PMSM of claim 1, wherein L groups of two or three analog magnetic flux sensors are spaced apart by a group electrical angle of 360 mechanical degrees divided by M pole pairs.

19. 19. The PMSM of claim 18, wherein L=M.

20. A permanent magnet synchronous motor (PMSM), a hollow cylindrical stator having sealed stator windings; a magnetic rotor having M pole pairs arranged to rotate about a rotation axis within the hollow cylindrical stator by a rotor shaft, the magnetic rotor having M pole pairs arranged to rotate about a rotation axis within the hollow cylindrical stator by a rotor shaft, the stator windings being energized to generate a rotating magnetic field according to a rotational position of the magnetic rotor; two or more analog magnetic flux sensors positioned within the hollow cylindrical stator and included in the sealed stator windings, the analog magnetic flux sensors being arranged concentrically about the axis of rotation of the hollow cylindrical stator at a constant mechanical angle relative to each other equal to the constant electrical angle divided by M, and spaced directly apart from the magnetic rotor across a radial gap (X), allowing unimpeded magnetic flux of the magnetic rotor to act on the analog magnetic flux sensors and output two or more sinusoidal signals separated in phase by the constant electrical angle, which can be evaluated by an angle tracking observer (ATO) to generate an electrical angle of the deployed rotor, and which can be determined to convert the electrical angle of the deployed rotor to a mechanical angle of the magnetic rotor indicative of the rotational position of the magnetic rotor; The PMSM including the sealed stator winding and analog magnetic flux sensor capable of withstanding shocks in excess of 5,000 gs.

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