Coil winding pattern for enhanced motor efficiency

Abstract

To provide an intravascular blood pump that increases the flow rate produced by electric motors while maintaining or increasing the efficiency of the motors.SOLUTION: An intravascular blood pump comprises a slotless motor having p magnet pole pairs and n phases, where p is an integer greater than zero and n is an integer greater than or equal to 3. The motor comprises a stator winding having 2np coils 360-365. The 2np coils are wound to form two coils per phase per magnet pole pair such that a coil from each phase is circumferentially arranged next to a coil from a different phase in a sequential order of phase. The arrangement is repeated along the stator winding such that each coil spans 360° / (2np) about the cross section of the stator winding. The motor also comprises a permanent magnet rotor 150 supported for rotation and configured to generate a magnetic flux for interaction with the stator winding. The two coils per phase per magnet pole pair are connected in series.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Provisional Patent Application No. 62 / 853,999, filed May 29, 2019, which is incorporated herein by reference. [Background technology]

[0002] background Intravascular blood pumps, such as the Impella® pump by Abiomed, Inc. of Danvers, Massachusetts, USA, are quickly becoming the current standard for ventricular assist devices. The Impella® pump family currently includes the Impella 2.5® pump, the Impella 5.0® pump, the Impella CP® pump, and the Impella LD® pump. These pumps are percutaneously inserted into the patient through a single access point (e.g., radial access, femoral access, axillary access) so that the pump head can be placed at a desired site in the patient's body via a small diameter (6-7 Fr) catheter. Such desired sites include, but are not limited to, the left or right ventricle of the patient's heart. The pump head includes an electric motor that includes a stator winding that is configured to magnetically interact with a rotor for rotation of the pump head resulting in volumetric blood flow through the rotor and thus through the patient's heart. There is a need for an efficient electric motor that produces good flow rates. Summary of the Invention

[0003] overview Currently, Impella® pumps can pump blood at flow rates of about 2.5 to about 5.0 liters per minute (lpm). However, as the number of surgical procedures using Impella® increases, there is an increasing need to increase the blood flow rate produced beyond these levels. This means that higher rotor speeds are required from the motor. However, due to the small geometry required, increasing the rotor speed has several effects that may affect the operation of such small pumps. For example, increasing the rotor speed may be accompanied by increased heat generation (Joule heating) in the motor. When the device is inserted percutaneously into the patient's body, such increased heating can have devastating effects on the surrounding tissue. Another consideration is the resistive load placed on the device, and modifications to the motor to achieve higher flow rates may lead to reduced motor efficiency due to resistive losses.

[0004] In view of the above-mentioned shortcomings of the state of the art, there is a great need to increase the flow rate produced by an electric motor while maintaining or improving the efficiency of the motor.

[0005] Disclosed herein is an apparatus for addressing various problems and shortcomings of the state of the art, as discussed above. More specifically, disclosed herein is an intravascular blood pump for insertion into a patient's body. Typically, the apparatus is placed in the patient's vasculature, such as, but not limited to, the patient's heart or aorta. In some aspects, a portion of the apparatus (e.g., a motor or rotor of a pump portion of the apparatus) is located outside the patient's heart (i.e., within the aorta) and another portion of the apparatus (e.g., a cannula) extends into the patient's heart (e.g., the left ventricle). Although certain aspects of the invention are described with the pump placed in the heart, one skilled in the art will understand that the pump may be placed in other locations in the patient's vasculature. The description of the pump being placed in the patient's heart is provided as an illustration of one possible placement of the apparatus in the patient's vasculature, and not as a limitation. The blood pump includes an elongated housing having a proximal end connected to a catheter and a distal end connected to the pump, the housing having a longitudinal axis. The blood pump also includes a slotless permanent magnet motor contained within the housing, the motor having p pole pairs and n phases, where p is an integer greater than zero and n is an integer greater than or equal to 3. The motor includes a stator winding having 2np coils wound to form two coils per phase per pole pair, with a coil from each phase positioned circumferentially next to a coil from a different phase in phase sequence, this arrangement repeated along the stator winding such that each coil of the 2np coils spans 360 / (2np) mechanical angles around a cross section of the stator winding. The motor also includes a permanent magnet rotor supported for rotation and configured to generate magnetic flux for interaction with the stator winding.The blood pump is configured such that the two coils per phase per pole pair of the stator winding are connected in series such that the direction of current flow through a first of the two coils is opposite to the direction of current flow in a second of the two coils, and the current flow in the first coil and the current flow in the second coil interact with opposite polarities of the rotor magnetic flux to generate torque in the same direction, thereby assisting in rotation of the rotor for blood flow through the pump.

[0006] In another aspect, a slotless permanent magnet motor is provided having p pole pairs and n phases, where p is an integer greater than zero and n is an integer greater than or equal to 3, and the motor has a longitudinal axis. The motor includes a stator winding having 2np coils wound to form two coils per phase per pole pair, with a coil from each phase positioned circumferentially next to a coil from a different phase in phase sequence, and this arrangement repeated along the stator winding such that each coil of the 2np coils spans 360 / (2np) mechanical angles around a cross section of the stator winding. The motor also includes a permanent magnet rotor supported for rotation and configured to generate magnetic flux for interaction with the stator winding. The electric motor is configured such that the two coils per phase per pole pair of the stator winding are connected in series such that the direction of current flow through a first of the two coils is opposite to the direction of current flow in the second of the two coils, and the current flow in the first coil and the current flow in the second coil interact with opposite polarities of the rotor magnetic flux to generate torque in the same direction, thereby assisting in rotation of the rotor.

[0007] In some implementations, each of the coils includes either N / 2 turns for even values ​​of N, or (N±1) / 2 turns for odd values ​​of N, where N is the number of coil turns of a conventional stator winding with np coils wound to form one coil per phase per pole pair, and N is an integer equal to or greater than 1. In certain implementations, the resistance of the two coils connected in series per phase is equivalent to the resistance of one coil of a conventional stator winding. In other implementations, the two coils per phase are connected in series such that their beginnings or their ends are connected to each other.

[0008] In certain implementations, the two coils per phase are connected to the coils of the other phases in either a star or delta configuration. In some implementations, the 2np coils include one of a helical winding, a rhombic winding, a conventional winding, and a hybrid winding. In other implementations, the stator winding has a coil duty function that defines the perpendicular component of the coil relative to the longitudinal length of the stator winding that interacts with the rotor's magnetic field and contributes to the torque generated by the motor. In certain implementations, for a helical coil winding, the coil duty function is maximized when the perpendicular component is two-thirds the longitudinal length of the stator winding. In some implementations, the coil duty function has the same shape for all phases, but is offset by 360 / n electrical degrees for each phase.

[0009] In further implementations, the coil utilization function defines the perpendicular component of the coil relative to the longitudinal length of the stator winding that contributes to the torque generated by the motor. In some implementations, the motor comprises a three-phase, two-pole machine. In other implementations, the motor comprises a six-coil, two-pole machine, with each coil spanning 60 machine degrees around the cross section of the stator winding. In certain implementations, the motor generates a torque constant that is approximately 15.5% greater than the torque constant of a motor having a conventional stator winding with n coils wound to form one coil per phase per pole pair.

[0010] In other implementations, the rotor pumps blood at a flow rate of about 1.0 lpm to about 6.0 lpm. In some implementations, the pump can be inserted into the right ventricle of the patient's heart. In further implementations, the pump can be inserted into the left ventricle of the patient's heart.

[0011] A stator winding according to an embodiment of the present disclosure uses two coils per phase per pole pair connected as described above. This increases the torque constant of a motor using such a stator winding by 15.5% compared to a conventional motor having a stator winding with one coil per phase per pole pair. Such a stator configuration reduces Joule heating in the motor because it does not increase the resistive load on the stator. In short, the motor of the present disclosure provides a stator coil winding pattern that improves motor efficiency. [Brief description of the drawings]

[0012] These and other objects and advantages will become apparent from the following detailed description considered in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout. [Figure 1] FIG. 1 illustrates an exemplary longitudinal cross-section of an intravascular blood pump according to one embodiment of the present disclosure. [Diagram 2] 2A-2D are diagrams illustrating exemplary coil winding patterns known in the art that may be used in the blood pump of FIG. [Diagram 3] Figure 3A shows an exemplary cross-section at the top of a conventional stator winding known in the art that may be used in the blood pump of Figure 1. Figure 3B shows an exemplary cross-section at the top of a stator winding according to one embodiment of the present disclosure that may be used in the blood pump of Figure 1. [Figure 4] 4A and 4B are example circuit diagrams illustrating the electrical connections of the coils that make up the stator winding of FIG. 3A when arranged in a star configuration, according to one embodiment of the present disclosure. [Diagram 5]FIG. 5 illustrates an exemplary cross-section of the stator winding of FIG. 3B during operation of the blood pump of FIG. 1 according to one embodiment of the disclosure. [Figure 6] FIG. 6 is a diagram illustrating an example cross section of a stator winding of an electric motor having three phases and two pole pairs for use in the blood pump of FIG. 1 according to one embodiment of the disclosure. [Figure 7] FIG. 7 is a diagram illustrating an example cross section of a stator winding of an electric motor having five phases and one pole pair for use in the blood pump of FIG. 1 according to one embodiment of the disclosure. [Figure 8] 8A to 8D are diagrams showing coil winding patterns of the conventional spiral winding of FIG. 3A. [Figure 9] 9A-9D are diagrams illustrating coil winding patterns for the helical winding coil of FIG. 3B according to one embodiment of the present disclosure. [Figure 10] Figure 10A shows the direction of current in the coils of one phase of the conventional stator winding of Figure 3A at one instant during operation, and Figure 10B shows the percentage of coil usage in one phase of the conventional stator winding of Figure 3A when used in the blood pump of Figure 1. [Figure 11] 11A and 11B are diagrams illustrating the direction of current in the coils of one phase of the stator winding of FIG. 3B at one instant during operation according to one embodiment of the present disclosure, and the coil utilization percentage of one phase of the stator winding of FIG. 3B when used in the blood pump of FIG. 1 according to one embodiment of the present disclosure. [Figure 12] 12A-12D are diagrams illustrating an increase in the torque constant of a blood pump motor using the stator winding of FIG. 3B according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Detailed Description To provide an overall understanding of the devices described herein, certain exemplary embodiments will be described. Although the embodiments and features described herein are specifically described for use in connection with an intravascular blood pump, it will be understood that all components and other features outlined below may be combined with one another in any suitable manner and adapted and applied to other types of procedures requiring efficient electric motors with high rotor speeds.

[0014] The devices and methods described herein relate to an intravascular blood pump for insertion into a patient's body (i.e., the patient's vasculature, such as the heart, aorta, etc.). The blood pump includes an elongated housing having a proximal end connected to a catheter and a distal end connected to the pump, the housing having a longitudinal axis. The blood pump also includes a slotless permanent magnet electric motor contained within the housing, the motor having p pole pairs and n phases, where p is an integer greater than zero and n is an integer greater than or equal to 3. The motor includes a stator winding having 2np coils wound to form two coils per pole pair per phase, with a coil from each phase being circumferentially positioned next to a coil from a different phase in phase sequence, this arrangement being repeated along the stator winding such that each coil of the 2np coils spans 360 / (2np) mechanical angles around a cross section of the stator winding. The motor also includes a permanent magnet rotor supported for rotation and configured to generate a magnetic flux for interaction with the stator winding. The blood pump is configured such that the two coils per phase per pole pair of the stator winding are connected in series such that the direction of current flow through a first of the two coils is opposite to the direction of current flow in a second of the two coils, and the current flow in the first coil and the current flow in the second coil interact with opposite polarities of the rotor magnetic flux to generate torque in the same direction, thereby assisting in rotation of the rotor for blood flow through the pump.

[0015] The intravascular blood pump of the present disclosure allows for improved motor efficiency by incorporating a double helical stator winding. Such a stator winding includes two coils per phase per pole pair connected in the above configuration. This provides a 15.5% increase in torque constant over conventional blood pumps using one coil per phase per pole pair. Such a stator configuration reduces Joule heating in the motor since it does not increase the resistive load on the stator. In short, the motor of the present disclosure provides a stator coil winding pattern that provides improved motor efficiency.

[0016] 1 illustrates an exemplary intravascular blood pump 100 for insertion into a patient's body, according to one embodiment of the disclosure. The blood pump 100 includes an electric motor unit 110 and a pump unit 120 arranged along a longitudinal axis 105. The electric motor unit 110 includes an electric motor including a stator winding 140 and a rotor 150 housed within a housing 112. The stator winding 140 extends along the length of the electric motor unit 110 from a proximal end 142 to a distal end 143 and includes wires 144 wound in a particular pattern, details of which are provided below. The stator winding 140 defines a central lumen 145 within which the rotor 150 is disposed. The stator winding 140 is of the slotless type, such that the wires 144 are wound on themselves, rather than on a conventional laminated stator core. Power feeders 146, 147 provide the necessary external electrical connections from the pump 100 to the stator windings 140 for operation of the motor unit 110. Each of the wires 144 may have an insulating coating (not shown), and optionally the wound stator wires 144 may be encapsulated or overmolded with a synthetic epoxide resin (also not shown).

[0017] 1, the stator windings 140 and the housing 112 are shown as separate components, it will be understood that the stator windings 140 may be encapsulated within the housing 112 to form a single component. The housing 112 includes a proximal end 114 and a distal end 116. The proximal end 114 of the housing 112 is coupled to a distal end 134 of a catheter 130, which may include a flexible tube. The catheter 130 includes a lumen 132 that extends toward a physician for control and operation of the blood pump 100.

[0018] The rotor 150 includes a permanent magnet 152 rotatably supported around a shaft 153 within the lumen 145 of the stator 140. The magnet 152 may include a cylindrical permanent magnet that surrounds the shaft 153 within the motor unit 110. The shaft 153 extends from the motor unit 110 into the pump unit 120 and aids in the rotation of the impeller 160 to pump blood. In certain implementations, the rotor 150 may include several permanent magnets arranged radially around the shaft 153, or an electromagnet with its own rotor winding. For example, in the case of a motor with one pole pair, the magnet 152 may include one north pole N and one south pole S. As a further example, in the case of a motor with two pole pairs, the magnet 152 may include two north poles N1 and N2 and two south poles S1 and S2 arranged alternately around the shaft 153.

[0019] 1 shows rotor 150 rotatable within stator 140, motor 110 may be configured as a cylinder in which stator 140 is held stationary about shaft 153 and rotor 150 rotates about stator 140. Shaft 153 extends along the length of motor unit 110 and into cylindrical housing 122 of pump unit 120. In some implementations, shaft 153 is hollow and may include a lumen 154, for example, for passage of a guidewire.

[0020] The distal end of shaft 153 is coupled to an impeller 160 located within pump housing 112. Interaction between stator 140 and rotor 150 of motor unit 110 generates a torque on rotor 150 that rotates shaft 153, which in turn rotates impeller 160 within cylindrical pump housing 122. As this occurs, blood is drawn into the pump via axial inlet 124 for axial transport and the blood exits laterally through opening 126 and flows axially along housing 112. In this manner, pump 100 generates blood flow within the patient's heart.

[0021] 2A-2D illustrate exemplary stator winding patterns 210-213 according to one embodiment of the disclosure. Although Figures 2A-2D show a single coil winding pattern in a stator, such as wire 142 in Figure 1, it will be understood that a complete stator winding, such as stator winding 140 in Figure 1, may be achieved by axial arrangement of multiple similarly wound wires about a longitudinal axis of the motor unit 110, such as longitudinal axis 105 in Figure 1.

[0022] 2A-2D show exemplary coil winding patterns used in a two-pole electric machine where one mechanical angle is equal to one electrical angle. The coil winding patterns of FIGS. 2A-2D may be used to form the stator winding 140 of the electric motor unit 110 of FIG. 1. FIG. 2A shows a conventional stator winding pattern 210 in which each wire 214 in the stator extends along the length of the stator 220 from a proximal end 221 to a distal end 225. At the distal end 225, the wire 214 follows the circumference of the stator for 180 mechanical angles and returns to the proximal end 221. Because both ends of the wire 214 terminate at the proximal end 221, the conventional coil winding pattern 210 may face end turn stack-up issues where each of the multiple wire ends at the proximal end 221 of the stator winding 210 must be electrically connected to a stator feed line, which may further cause congestion and connection issues. 2B shows a diamond-shaped stator winding pattern 211 in which each wire 215 is arranged in a bent configuration. Unlike the conventional winding 210 of FIG. 2A, the diamond-shaped winding includes one continuous wire wound several times and shifts axially to form the stator coil for each complete turn. The bent configuration of the diamond-shaped winding may require post-assembly.

[0023] FIG. 2C shows a helical stator winding pattern 212 in which each wire 216 is arranged in an elliptical configuration around the stator. The helical stator winding pattern 212 is similar to the diamond winding pattern 211 of FIG. 2B, but without the bends, simplifying the coil winding process. The helical winding 212 is a one-stage winding that can be easily formed without requiring a post-assembly step. FIG. 2D shows a hybrid stator winding pattern 213, which includes windings that are a mixture of the conventional winding shown in FIG. 2A and the diamond winding shown in FIG. 2B. Such a hybrid stator winding allows for an optimal ratio of torque to resistance by adjusting the vertical length x and / or horizontal angular extent y of the coil.

[0024] In the following disclosure, each stator winding utilizes the helical winding pattern 212 of Figure 2B. However, it will be understood that the stator windings in this disclosure may use any of the winding patterns as described in connection with Figures 2A-2D. Additionally, any other stator winding pattern may be used in some implementations of the present disclosure.

[0025] Aspects of the present disclosure are described with reference to a conventional stator winding having one coil per phase per permanent magnet pole pair. Figures 3A and 3B show cross sections of an exemplary stator winding for use in an electric motor, such as the stator winding 140 of the electric motor unit 110 of Figure 1. Figure 3A shows a conventional stator winding 300 including one coil per phase per permanent magnet pole pair for use in a three-phase electric motor having one pole pair (i.e., one north pole N and one south pole S). In this disclosure, the three phases of the motor are referred to as phase A, phase B, and phase C. In the conventional stator winding 300, each phase includes one coil, i.e., phase A (labeled "A") coil 310, phase B (labeled "B") coil 311, and phase C (labeled "C") coil 312. Each of the coils 310-312 includes a winding having a number N of turns, where N is an integer and N>1, and each coil has the same number of turns. The windings are formed from wire wound in a particular manner as described in connection with Figures 2A-2D, such that each coil has a beginning and an end, as indicated by wire ends 320-325 in Figure 3A. Although aspects of the present disclosure are described with respect to stator windings having helical coils, it will be understood that any winding type may be used.

[0026] 3A, the lateral distribution of the coils 310-312 is such that the coils 310-312 are evenly distributed around the stator winding 300, with each coil spanning 120 electrical degrees (equal to 120 mechanical degrees in a two-pole electric machine) of the circumference of the cross section of the stator winding 300. The stator winding 300 is used in a three-phase motor having one coil per pole pair, but for a typical motor having n phases and p pole pairs, each coil of a conventional stator winding 300 having one coil per phase per pole pair would span 360 / (np) mechanical degrees of the circumference of the cross section of the stator winding. With respect to the axial distribution of the coils about the longitudinal axis of the conventional stator winding 300, the windings of the coils 310-312 are configured such that they are each wound from a proximal end of the stator winding 300 (such as the proximal end 142 of the stator winding 140 in FIG. 1), extend longitudinally toward a distal end (such as the distal end 143 of the stator winding 140 in FIG. 1), and return to the proximal end. In this manner, each of the coils 310-312 of the stator winding 300 includes substantially an inner layer and an outer layer, with the outer layer overlying the inner layer, as shown in cross section in FIG. 3A. In this configuration, the leads of each of the coils 310-312 are located at the proximal end of the stator winding 300 for connection with electrical power supplies to the motor, such as the leads 146, 147 shown in FIG. 1.

[0027] 3B illustrates a stator winding 350 including two coils per phase per pole pair for use in a three-phase motor having one pole pair according to one embodiment of the disclosure. In this arrangement, the stator winding 350 is a dual coil winding, and if implemented with a helical coil as shown in FIG. 2C, the stator winding 350 is a dual helical coil winding. In the stator winding 350, each phase A, B, and C of the three-phase motor includes two coils. Thus, phase A includes coil 360 (labeled "A1") and coil 361 (labeled "A2"), phase B includes coil 362 (labeled "B1") and coil 363 (labeled "B2"), and phase C includes coil 364 (labeled "C1") and coil 365 (labeled "C2"). With reference to the conventional stator winding 300 of FIG. 3A, if each coil 310-312 includes a winding having N turns (N is an integer and is equal to or greater than 1), then each of the coils 360-365 of the stator winding 350 includes a winding having either N / 2 turns for an even value of N, or (N±1) / 2 turns for an odd value of N, with each coil having the same number of turns. Thus, each coil of the stator winding 350 includes approximately half the number of turns of the coils of the conventional stator winding 300 of FIG. 3A. For example, if the coils 310-312 of the conventional stator winding 300 each include 100 turns, then the coils 360-365 of the stator winding 350 will each include approximately 50 turns. The number of turns of the winding of each of the coils 360-365 may include any of the winding types previously described, such as, for example, a helical winding.

[0028] The lateral distribution of the coils 360-365 is such that they are evenly distributed around the stator winding 350, with each coil spanning 60 mechanical degrees of the circumference of the cross section of the stator winding 350. The stator winding 350 is used in a three-phase motor having two coils per phase per pole pair, but for a typical motor having n phases and p pole pairs, each coil of the stator winding 350 of the present disclosure, with two coils per phase per pole pair, would span 360 / (2np) mechanical degrees of the circumference of the cross section of the stator winding. The axial distribution of the coils in the stator coil 350 is similar to the axial distribution of the conventional stator coil 300. The axial distribution of the coils about the longitudinal axis of the stator winding 350 is such that the turns of the coils 360-365 are each wound from a proximal end of the stator winding 350 (such as the proximal end 142 of the stator winding 140 in FIG. 1 ), extend longitudinally toward a distal end (such as the distal end 143 of the stator winding 140 in FIG. 1 ), and return to the proximal end. In this manner, each of the coils 360-365 of the stator winding 350 includes substantially an inner layer and an outer layer, as shown in cross section in FIG. 3B , with the outer layer overlying the inner layer. In this configuration, the lead of each of the coils 360-365 is located at the proximal end of the stator winding 300 for connection with a power supply to the motor, such as the leads 146, 147 shown in FIG. 1 .

[0029] The coils 310-312 of the conventional stator winding 300 and the coils 360-365 of the stator winding 350 of the present disclosure may be electrically connected in any configuration for an electric motor, such as, for example, star or delta. FIG. 4A shows the coils 310-312 of the stator winding 300 of FIG. 3A connected in an exemplary star configuration 400. The coils 310-312 are represented as resistive loads RA, RB, and RC, respectively. In the star configuration 400, the end point "Ae" of the coil 310, the end point "Be" of the coil 311, and the end point "Ce" of the coil 330 are interconnected. The start point "As" of the coil 310, the start point "Bs" of the coil 311, and the start point "Cs" of the coil 312 are connected to power feeds, such as the power feeds 143, 144 of the blood pump 100 of FIG. 1. In this manner, each branch of the star configuration 400 includes a single load corresponding to the coils of each phase of the stator winding 300 .

[0030] 4B illustrates an example electrical connection of coils in stator winding 350 according to one embodiment of the present disclosure, where coils 360-361 are represented as resistive loads RA1 and RA2, respectively, of phase A, coils 362-363 are represented as resistive loads RB1 and RB2, respectively, of phase B, and coils 364-365 are represented as resistive loads RC1 and RC2, respectively, of phase C. As previously mentioned, coils 360-365 of stator winding 350 each include half the number of turns as coils 310-312 of stator winding 300. Thus, the resistive load per phase of dual stator winding 350 is the same as the resistive load per phase of conventional stator winding 300, i.e., RA=RA1+RA2, RB=RB1+RB2, and RC=RC1+RC2. Thus, the dual coil configuration of the stator winding 350 does not impose an additional resistive load on the motor when compared to the load presented by the conventional stator winding 300.

[0031] As shown in the connection diagram of FIG. 4B, each branch of the star configuration 450 includes two coils with their like terminals connected, i.e., the two coils are connected back to back. For example, for phase A, coils 360-361, represented by resistive loads RA1 and RA2, respectively, are connected such that their terminals "A1e" and "A2e" are connected to each other. Similarly, terminals "B1e" and "B2e" of coils 362-363 of phase B, represented by resistive loads RB1 and RB2, respectively, are connected to each other, and terminals "C1e" and "C2e" of coils 364-365 of phase C, represented by resistive loads RC1 and RC2, respectively, are connected to each other. The start point "A1s" of resistive load RA1 of phase A coil 360, the start point "B1s" of resistive load RB1 of phase B coil 362, and the start point "C1s" of resistive load RC1 of phase C coil 364 are connected to power feed lines, such as power feed lines 143, 144 of blood pump 100 of Figure 1. In addition, the start point "A2s" of resistive load RA2 of phase A coil 361, the start point "B2s" of resistive load RB2 of phase B coil 363, and the start point "C2s" of resistive load RC2 of phase C coil 365 are interconnected.

[0032] The manner in which the coils 360-365 of the dual stator winding 350 of the present disclosure are connected is important because it determines how the coils 360-365 interact with the magnetic flux generated by the rotor during operation of the motor. In a star configuration 450 as shown in FIG. 4B, the direction of current through coil A1 of the stator winding 350 is opposite to the direction of current through coil A2. Similarly, the direction of current through coil B1 of the stator winding 350 is opposite to the direction of current through coil B2, and the direction of current through coil C1 of the stator winding 350 is opposite to the direction of current through coil C2. This means that coil A1, having a first direction of current through coil A1, interacts with a first pole of the rotor, and coil A2, having a second direction of current through coil A2, opposite to the first direction of current in coil A1, interacts with a second pole of the rotor opposite to the first pole. Additionally, coil B1 having a first direction of current flowing through coil B1 interacts with a first pole of the rotor, and coil B2 having a second direction of current flowing through coil B2 opposite the first direction of current in coil B1 interacts with a second pole of the rotor opposite the first pole. Additionally, coil C1 having a first direction of current flowing through coil C1 interacts with a first pole of the rotor, and coil C2 having a second direction of current flowing through coil C2 opposite the first direction of current in coil C1 interacts with a second pole of the rotor opposite the first pole. The interaction of the coils of stator winding 350 with the magnetic flux of the rotor during operation is described in conjunction with FIG. 5.

[0033] FIG. 5 illustrates an exemplary cross section 500 of the blood pump 100 of FIG. 1 using the stator winding 350 in a three-phase, two-pole motor taken along line X-X' during operation. As previously discussed, the stator winding 350 is suitable for operation of a three-phase motor having two coils per phase per pole pair, although stator windings for motors having any number of phases, n, and pole pairs, p, bringing the total number of coils used to 2np, may be used within the scope of this disclosure. In FIG. 5, coils marked with "x" indicate current flowing into the page perpendicular to the plane of the page, and coils marked with "·" indicate current flowing out of the page perpendicular to the plane of the page. As shown, phase A coils 360-361 are connected as described in connection with FIG. 4B such that the direction of current flowing through coil 360 is opposite the direction of current flowing through coil 361. Due to the physical arrangement and electrical connections of coils 360 - 361 as described above, the polarity of the magnetic field generated by permanent magnet stator 150 with which coil 360 interacts is opposite to the polarity with which coil 361 interacts.

[0034] Similarly, coils 362-363 of phase B of the motor are connected such that the direction of current through coil 362 is opposite to the direction of current through coil 363. Due to the physical arrangement and electrical connections of coils 362-363 as described above, the polarity of the magnetic field emanating from permanent magnet stator 150 with which coil 362 interacts is opposite to the polarity that interacts with coil 363. Additionally, coils 364-365 of phase C of the motor are connected such that the direction of current through coil 362 is opposite to the direction of current through coil 363. In this arrangement, coils 364-365 each see a different polarity than the stator pole pair. Due to the physical arrangement and electrical connections of coils 364-365 as described above, the polarity of the magnetic field emanating from permanent magnet stator 150 with which coil 364 interacts is opposite to the polarity that interacts with coil 365. During operation, the interaction of the coils of stator winding 350 with the magnetic flux of the rotor produces a torque that acts on the rotor to rotate it.

[0035] FIG. 6 illustrates another example cross-section of a dual coil stator winding 600 for use in a motor having three phases A, B, and C and two permanent magnet pole pairs N1-S1 and N2-S2, according to one embodiment of the disclosure. According to the general definition above, a motor using stator winding 600 has n=3 and p=2. As discussed in connection with stator winding 350 of FIG. 4A, stator winding 600 also includes two coils per phase per pole pair, resulting in a total of twelve coils 610-621. In stator winding 600, each phase A, B, and C of the three-phase motor includes two coils since there are two pole pairs in the motor. Thus, phase A includes coils 610-613 (labeled "A1", "A2", "A3", and "A4", respectively), phase B includes coils 614-617 (labeled "B1", "B2", "B3", and "B4", respectively), and phase C includes coils 618-621 (labeled "C1", "C2", "C3", and "C4", respectively). As shown in Figure 6, the coils from each phase are circumferentially arranged next to coils from different phases in phase order, and the arrangement is repeated along the stator winding such that each coil spans 360° / (2np)=360° / (2x3x2)=30° around the cross section of the stator winding 600.

[0036] Similar to the coils of the stator winding 350, the coils 610-621 may be electrically connected in either a star or delta configuration, with (i) the phase A coils 610-613 connected back-to-back with like terminals along the phase A branch of the star or delta connection, (ii) the phase B coils 614-617 connected back-to-back with like terminals along the phase B branch of the star or delta connection, and (iii) the phase C coils 618-621 connected back-to-back with like terminals along the phase C branch of the star or delta connection. In such electrical connections, (i) the direction of current flowing through coils A1 and A3 is opposite to the direction of current flowing through coils A2 and A4, (ii) the direction of current flowing through coils B1 and B3 is opposite to the direction of current flowing through coils B2 and B4, and (iii) the direction of current flowing through coils C1 and C3 is opposite to the direction of current flowing through coils C2 and C4.

[0037] In this way, coil A1, having a first direction of current flowing through it, interacts with the first pole N1 of the rotor, coil A2, having a second direction of current flowing through coil A2 opposite to the first direction of current in coil A1, interacts with the second pole S1 of the rotor opposite to the first pole N1, coil A3, having a first direction of current flowing through coil A3, interacts with the third pole N2 of the rotor, and coil A4, having a second direction of current flowing through coil A4 opposite to the first direction of current in coil A3, interacts with the fourth pole S2 of the rotor opposite to the third pole N2. Similarly, coil B1, having a first direction of current flowing through it, interacts with a first pole N1 of the rotor, coil B2, having a second direction of current flowing through coil B2 opposite to the first direction of current in coil B1, interacts with a second pole S1 of the rotor opposite to the first pole N1, coil B3, having a first direction of current flowing through coil B3, interacts with a third pole N2 of the rotor, and coil B4, having a second direction of current flowing through coil B4 opposite to the first direction of current in coil B3, interacts with a fourth pole S2 of the rotor opposite to the third pole N2. Finally, coil C1, having a first direction of current flowing through it, interacts with a first pole N1 of the rotor, coil C2, having a second direction of current flowing through coil C2 opposite the first direction of current in coil C1, interacts with a second pole S1 of the rotor opposite the first pole N1, coil C3, having a first direction of current flowing through coil C3, interacts with a third pole N2 of the rotor, and coil C4, having a second direction of current flowing through coil C4 opposite the first direction of current in coil C3, interacts with a fourth pole S2 of the rotor opposite the third pole N2. The interaction of the coils of the stator winding 600 with the magnetic flux of the rotor during operation generates a torque that acts on the rotor and causes it to rotate.

[0038] 7 illustrates a further example cross-section of a dual coil stator winding 700 for use in a motor having five phases A, B, C, D, and E and one permanent magnet pole pair N-S, according to one embodiment of the present disclosure. In accordance with the general definition above, a motor using stator winding 700 has n=5 and p=1. As discussed in connection with stator winding 350 and stator winding 600, stator winding 700 also includes two coils per phase per pole pair, resulting in a total of ten coils 710-719. Phase A includes coils 710-711 (labeled "A1" and "A2", respectively), phase B includes coils 712-713 (labeled "B1" and "B2", respectively), phase C includes coils 714-715 (labeled "C1" and "C2", respectively), phase D includes coils 716-717 (labeled "D1" and "D2", respectively), and phase E includes coils 718-719 (labeled "E1" and "E2", respectively). As shown in FIG. 7, the coils from each phase are circumferentially arranged next to coils from different phases in phase order, and the arrangement is repeated along the stator winding 700 such that each coil spans 360° / (2np)=360° / (2×5×1)=36° around the cross section of the stator winding 700.

[0039] Similar to the coils of stator winding 350 and stator winding 600, coils 710-719 may be electrically connected in either a star or delta configuration, with (i) phase A coils 710-711 connected back-to-back with like terminals along the phase A branch of the star or delta connection, (ii) phase B coils 712-713 connected back-to-back with like terminals along the phase B branch of the star or delta connection, (iii) phase C coils 714-715 connected back-to-back with like terminals along the phase C branch of the star or delta connection, (iv) phase D coils 716-717 connected back-to-back with like terminals along the phase D branch of the star or delta connection, and (v) phase E coils 718-719 connected back-to-back with like terminals along the phase E branch of the star or delta connection. In such electrical connections, (i) the direction of current through coil A1 is opposite to the direction of current through coil A2, (ii) the direction of current through coil B1 is opposite to the direction of current through coil B2, (iii) the direction of current through coil C1 is opposite to the direction of current through coil C2, (iv) the direction of current through coil D1 is opposite to the direction of current through coil D2, and (v) the direction of current through coil E1 is opposite to the direction of current through coil E2.

[0040] In this way, coil A1, having a first direction of current flowing through coil A1, interacts with a first pole N of the rotor, and coil A2, having a second direction of current flowing through coil A2, opposite to the first direction of current in coil A1, interacts with a second pole S of the rotor opposite to the first pole N. Similarly, coil B1, having a first direction of current flowing through coil B1, interacts with a first pole N of the rotor, and coil B2, having a second direction of current flowing through coil B2, opposite to the first direction of current in coil B1, interacts with a second pole S of the rotor opposite to the first pole N. Furthermore, coil C1, having a first direction of current flowing through coil C1, interacts with a first pole N of the rotor, and coil C2, having a second direction of current flowing through coil C2, opposite to the first direction of current in coil C1, interacts with a second pole S of the rotor opposite to the first pole N. Coil D1, having a first direction of current flowing through it, interacts with a first pole N of the rotor, and coil D2, having a second direction of current flowing through coil D2, opposite the first direction of current in coil D1, interacts with a second pole S of the rotor opposite the first pole N. Finally, coil E1, having a first direction of current flowing through coil E1, interacts with the first pole N of the rotor, and coil E2, having a second direction of current flowing through coil E2, opposite the first direction of current in coil E1, interacts with the second pole S of the rotor opposite the first pole N. The interaction of the coils of the stator winding 700 with the magnetic flux of the rotor during operation generates a torque that acts on the rotor and causes it to rotate.

[0041] The interaction of the current flowing through the coils of the stator windings 350 and the magnetic flux density of the two-pole rotor during operation is now described with reference to FIG. 5. As described in relation to FIG. 1, the rotor 150 is in constant rotation during use. FIG. 5 illustrates the position of the rotor 150 at an instant when the rotor is radially positioned as shown, with the direction of current flowing through the coils of the stator windings 350 indicated. In the position shown, the permanent magnet rotor 150 generates a magnetic flux density B represented by a magnetic field pattern including magnetic field lines 510. The magnetic field lines 510 originate at the north pole N of the rotor 150 and terminate at the south pole S. According to Lenz's law, the interaction between the magnetic flux density B and the length of the stator windings L in a direction perpendicular to the magnetic flux density B produces a torque T in the rotor 150 for its rotation which is determined by the following equation: TIFF2025076437000002.tif4128 During the ceremony, TIFF2025076437000003.tif3128 is a direction parallel to the longitudinal axis 105 of the rotor 150, TIFF2025076437000004.tif3128 is the radial component of the magnetic flux density perpendicular to the longitudinal axis 105 of the rotor 150, TIFF2025076437000005.tif3128 is the perpendicular component of the coil winding parallel to the longitudinal access of the motor rotor, and x represents the vector cross product. Thus, current flow in the stator windings 350 induces rotation of the rotor 150 about the longitudinal axis 105, which induces corresponding rotation of the impeller 160 coupled to the distal end of the rotor shaft 153.

[0042] FIG. 8A illustrates a conventional stator winding 300 in use in a three-phase, two-pole motor in which one electrical angle equals one mechanical angle. The horizontal axis of the plot represents angular position along the circumference of the stator winding 300, and the vertical axis represents the longitudinal length of the stator winding 300 moving from the distal end to the proximal end of the stator winding 300. As previously discussed, each of the coils 310-312 includes multiple wires wound in a particular manner, such as the helical winding of FIG. 2C. In FIG. 8A, the wires are wound in a helical fashion, and each of the coils 310-312 is shown as a band disposed between the proximal end (top of the plot) and the distal end (bottom of the plot) of the stator winding 300. Due to the manner in which the helical coils 310-312 are wound, each band in FIG. 8A overlaps to form the stator winding 300. For improved visualization, FIGS. 8B-8D show the winding patterns of each of the phase A, phase B, and phase C coils 310-312 of the stator winding 300 when viewed separately. That is, when the coils shown in FIGS. 8B-8D are superimposed, the stator winding 300 is obtained as shown in FIG. 8A. In addition, it should be noted that each band representing the coils 310-312 includes multiple wires, but only nine representative wires per coil are shown in FIGS. 8A-8D. The wire ends or leads 320-325 of each of the coils 310-312 are also shown at the proximal end of the stator winding 300. The direction shown on each lead 320-325 represents the direction in which the wire forming the respective coil 310-312 is wound. For example, the direction shown on lead 320 represents the start of the wire forming winding 310, and the direction shown on lead 321 represents the end of the wire forming winding 310. The coils 310-312 are arranged angularly symmetrically within the stator winding 300 such that a coil from each phase is circumferentially positioned next to a coil from a different phase in phase sequence, resulting in the stator winding pattern shown in Figure 8A. The coil span of each of the coils 310-312 of the stator winding 300 is 360° / (np)=360° / (3×1)=120°.

[0043] During operation of the motor, current from the motor controller is passed through the stator winding 300 via feeders (e.g., feeders 146-147 in FIG. 1) connected to the line ends 320-325 such that the magnitude of the current through each of the coils 310-312 is the same. Because the coils 310-312 overlap in their arrangement within the stator winding 300, the effect of the current in each of the coils may be influenced by the current in adjacent or overlapping coils. Thus, due to the physical arrangement of the coils 310-312 within the stator winding, the net effect of the currents flowing through all of the coils 310-312 in the stator winding 300 cancel each other. This effect is discussed further in relation to FIG. 10A.

[0044] FIG. 10A shows only a coil 310 (coil A) of the stator winding 300 in use. Coil A corresponds to phase A. Although the coil 310 is shown to include only five representative winding wires 910-914, it will be understood that the coil 310 may include multiple wires forming bands (as shown in FIG. 8A). As shown, the paths taken by the current in each of the winding wires 910-914 have regions of overlap as the wires are wound between the proximal and distal ends of the stator winding 300 (such as the proximal and distal ends 142 and 143 shown in FIG. 1). For example, the winding direction of the wires 910-914 in the coil 310 causes the current in the wires 910-914 to flow into a triangular region 920 and then turn around and leave the triangular region 920. As the wires 910-914 turn and leave the triangular region 920, the longitudinal components of the currents in the wires change. This is shown in FIG. 10A, where the current I flowing in the wire 914 entering the triangular region 920 has a directional component I z and I θ (longitudinal and angular components, respectively). Upon leaving the triangular region 920, the current I changes direction and has a directional component, −I z and I θ Therefore, the longitudinal component of the current leaving the triangular region 920, −I z is the longitudinal component I of the current entering the triangular region 920 zSimilarly, the currents in wires 910-914 flow into triangular region 930 and then turn around and leave region 930. As wires 910-914 turn around and leave triangular region 930, the longitudinal components of the currents in the wires change and become completely opposite to the longitudinal components of the currents in the wires that enter triangular region 930. Because the magnitudes of the currents in wires 910-914 are the same and the longitudinal components of current flow into and out of triangular regions 920 and 930 are completely opposite to each other, the effect on the rotor of the longitudinal components of the currents in wires 910-914 (represented by arrows 940-942 in FIG. 10A ) cancel out in triangular regions 920 and 930 as shown in FIG. 10A , i.e., I z -I z = 0. Thus, the longitudinal components of the currents in the wires 910-914 in the triangular region 920 and the triangular region 930 do not contribute to the torque generated in the rotor according to equation (1).

[0045] As stated in equation (1), the torque T generated in the rotor 150 depends on the longitudinal length L of the wires carrying the current in the coils in a direction parallel to the longitudinal axis 105 of the rotor 150. Thus, only the vertical components of the wires 910-914 in FIG. 10A contribute to the generation of the torque T in the rotor. The vertical components of the wires 910-914 can be easily visualized by drawing a vertical line in FIG. 10A and determining the direction of the longitudinal component current flowing in the wires 910-914 at the intersections of the wires 910-914 with the vertical line.

[0046] The contribution of the mechanical arrangement of the wires in the coils to the generated torque T is described by a coil utilization function 950, as shown in Figure 10B. The vertical components of the wires 910-914 that contribute to the torque T in the rotor are shown in Figure 10A where the wires 910-914 carrying currents with longitudinal components in opposite directions do not overlap. For example, for coil angular positions θ of 120° to 180° around the stator winding 300, there is no wire overlap and the currents flowing in the wires 910-914 have longitudinal components in the same direction, whereas for angular positions θ of 60° and 240°, respectively, around the stator winding 300, the wires overlap and the longitudinal components of the currents flowing in the overlapped wires 910-914 are in completely opposite directions.

[0047] Thus, the coil duty function has a maximum value when the longitudinal components of the currents flowing in the wires 910-914 are in the same direction, as shown in Figure 10B for 120° < θ < 180° and 300° < θ < 360° around the stator winding 300, where there are no overlapping wires carrying currents with longitudinal components in opposite directions. This maximum value is about 2 / 3 of the total length of the stator winding 300 for a three-phase, two-pole motor, as shown in Figure 10B where the coil duty is maximum at about 66.7%. The coil duty function is zero at θ = 60° and θ = 240° around the stator winding 300, where the wires overlap and the longitudinal components of the currents in the overlapping wires are equal but opposite in direction. For completeness, for 0°<θ<60°, 60°<θ<120°, 180°<θ<240°, and 240°<θ<300°, wires 910-915 partially overlap with currents having opposite longitudinal components, resulting in some contribution to the torque T generated in the rotor. This can be seen in Figure 9B, where the coil duty cycle varies linearly with θ for 0°<θ<60°, 60°<θ<120°, 180°<θ<240°, and 240°<θ<300°.

[0048] FIG. 9A illustrates a stator winding 350 according to one embodiment of the present disclosure in use in a three-phase, two-pole motor at a moment in time during operation. As previously discussed, the coils 360-365 are wound using helical windings, such as the helical winding 212 of FIG. 2C, although any winding type may be used. In FIG. 9A, the coils 360-365 are shown as bands disposed between the proximal end (top of the plot) and the distal end (bottom of the plot) of the stator winding 350. Due to the manner in which the helical coils 360-365 are wound, the bands in FIG. 9A overlap to form the stator winding 350. As with FIGS. 8B-8D, for improved visualization, FIGS. 9B-9D illustrate the winding patterns of the phase A, phase B, and phase C coils 360-365 of the stator winding 350 when viewed separately. That is, when the coils shown in Figures 9B-9D are stacked together, the result is the stator winding 350 shown in Figure 9A. Additionally, note that each band representing coils 360-365 includes multiple wires, although only five representative wires per coil are shown in Figures 9A-9D. The wire ends or leads of each of the coils 360-365 are also shown at the proximal end of the stator winding 350, with arrows indicating the direction of winding of the wires forming each of the coils 360-365.

[0049] The coils 360-365 are arranged angularly symmetrically within the stator winding 350 such that a coil from each phase A, B, C is positioned circumferentially next to a coil from a different phase, in phase order, resulting in a stator winding pattern as shown in FIG. 9A. As previously mentioned, the present disclosure is directed to a stator winding having two coils per phase per pole pair. Thus, in FIGS. 9A-9D, phase A is shown to include coils 360-361 of FIG. 9B, phase B is shown to include coils 362-363 of FIG. 9C, and phase C is shown to include coils 364-365. The coil span of each of the coils 360-365 of the stator winding 350 is 360° / (2np)=360° / (2×3×1)=60°.

[0050] During operation of the motor, DC from a six-stage DC controller (not shown) is passed through the stator winding 350 via feeders (e.g., feeders 146-147 in FIG. 1) connected to leads at the proximal end of the stator winding 350 such that the magnitude of the current through each of the coils 360-365 is the same. Because the coils 360-365 overlap in their arrangement within the stator winding 350, the effect of current flow in each of the coils may be influenced by the current flow in adjacent or overlapping coils. Unlike the conventional stator winding 300 shown in FIG. 8A, the effect of current flow through the coils 360-365 do not cancel out due to the physical arrangement of the coils within the stator winding 350.

[0051] FIG. 11A shows only coils 360-361 (coil A1 and coil A2) of a stator winding 350 according to one embodiment of the present disclosure in use. Coil A1 and coil A2 correspond to phase A. Although coil 360 is shown as including five representative winding wires 1010-1014 and coil 361 is shown as including five representative winding wires 1015-1019, it will be understood that each of coils 360-361 includes multiple wires that form bands (as shown in FIG. 9A). As shown, the path taken by the current in each of winding wires 1010-1019 has regions of overlap as the wires are wound between the proximal and distal ends of the stator winding 350 (e.g., proximal end 142 and distal end 143 shown in FIG. 1). For example, the current in wires 1010-1014 flows into triangular regions 1020 and 1021, then turns around and leaves triangular regions 1020-1021. Similarly, the current in wires 1015-1019 flows into triangular regions 1022-1023, then turns around and leaves triangular regions 1022-1023.

[0052] As described in relation to Fig. 10A, when the wires 1010-1014 turn and leave the triangular regions 1020-1021, and when the wires 1015-1019 turn and leave the triangular regions 1022-1023, the longitudinal component of the current in each wire changes. In the wires 1010-1014, (i) the longitudinal component of the current flowing out of the triangular region 1020 is opposite to the longitudinal component of the current flowing into the triangular region 1020, and (ii) the longitudinal component of the current flowing out of the triangular region 1021 is opposite to the longitudinal component of the current flowing into the triangular region 1021. When the wires 1010-1014 turn and leave the triangular regions 1020-1021, the longitudinal component of the current in the wire changes and becomes completely opposite to the longitudinal component of the current flow in the wire entering the triangular regions 1020-1021.

[0053] Similarly, for wires 1015-1019, (iii) the longitudinal component of the current flowing out of triangular region 1022 is opposite to the longitudinal component of the current flowing into triangular region 1022, and (iv) the longitudinal component of the current flowing out of triangular region 1023 is opposite to the longitudinal component of the current flowing into triangular region 1023. As wires 1015-1019 turn and leave triangular regions 1022-1023, the longitudinal component of the current in the wires changes and becomes completely opposite to the longitudinal component of the current in the wires entering triangular regions 1022-1023. Because the magnitudes of the currents in the wires 1010-1019 are the same and the longitudinal components of current flow into and out of the triangular regions 1020-1023 in complete opposition to one another, the effects of the currents in the wires 1010-1019 (represented by arrows 1040-1043 in FIG. 11A ) cancel in the regions 1020-1023 as shown in FIG. 11A , i.e., I z -I z =0.

[0054] However, because the stator winding 350 has two coils per phase per pole pair, i.e., dual windings, the coils 360-361 also include additional diamond-shaped overlapping regions 1030-1031. As shown in FIG. 11A, these diamond-shaped overlapping regions occur away from the proximal or distal ends of the coils 360-361. In effect, these diamond-shaped regions are actually back-to-back triangular regions that result when the bands from coils A1 and A2 overlap one another. In these diamond-shaped regions, the longitudinal component of the current in the wires 1010-1019 flows into the regions 1030-1031 in one direction and then leaves the regions 1030-1031 in the same direction. Because the magnitudes of the currents in the wires 1010-1019 are the same and the longitudinal components of the current flow are the same in the regions 1030-1031, the effects of the currents in the wires 1010-1019, represented by the arrows 1040-1043 in FIG. 11A, do not cancel but add up in the regions 1030-1031, i.e., I z +I z =2I z 11A illustrates the effect of current flow in phase A coils 360-361 of stator winding 350, a similar effect will be seen from the current flow in phase B and phase C coils 362-365 of stator winding 350.

[0055] It should be noted that in the stator winding 350 according to the embodiment of the present disclosure, the regions 1020-1023 are essentially dead zones where the effects of current flowing through the winding are cancelled out. These dead zones are much smaller compared to the regions 920 and 930 of the conventional stator winding 300. At the same time, the manner in which the stator winding 350 is formed creates additional positive zones that enhance the performance of the stator winding 350.

[0056] As explained in connection with equation (1), the torque T generated in the rotor 150 depends on the longitudinal length L of the wires carrying the current in the coils in a direction parallel to the longitudinal axis 105 of the rotor 150. Virtually only the vertical components of the wires 1010-1019 in FIG. 11A contribute to the generation of the torque T in the rotor. The vertical components of the wires 1010-1019 can be easily visualized by drawing a vertical line on FIG. 11A and determining the direction of the current flowing in the wires 1010-1019 that intersect with the vertical line.

[0057] The contribution of the mechanical arrangement of the wires in the coil 350 to the generated torque T is described by the coil utilization function 1050, as shown in Figure 11B. The vertical components of the wires 1010-1019 that contribute to the torque T on the rotor 150 are shown in Figure 11A where the wires 1010-1019 carrying currents with longitudinal components in opposite directions do not overlap. For example, at 60° < θ < 180° around the stator winding 350, the currents flowing in the wires 1010-1019 have longitudinal components in the same direction (even though the wires overlap in regions 1030 and 1031), but at coil angle positions θ of 30° and 210°, respectively, around the stator winding 350, the wires overlap and the longitudinal components of the currents flowing in the overlapped wires 1010-1019 are in completely opposite directions.

[0058] Thus, the coil utilization function reaches a maximum when the longitudinal components of the currents flowing in the wires 1010-1019 are in the same direction, as shown in FIG. 11B for 60°≦θ≦180° and 240°≦θ≦360° around the stator winding 350, where there are no overlapping wires carrying currents with longitudinal components in opposite directions. As with the stator winding 300, this maximum is approximately 2 / 3 of the total length of the stator winding 350 for a three-phase, two-pole motor, as shown in FIG. 11B where the coil utilization is maximum at approximately 66.7%. Note that the maximum coil utilization of the stator winding 350 (coil angle range (120°)) is twice the maximum coil utilization of the stator winding 300 (coil angle range (60°)). The coil duty function is zero at θ=30° and θ=210° around the stator winding 350 where the wires overlap and the longitudinal components of current flow in the overlapped wires are equal but completely opposite. For completeness, for 0°<θ<30°, 30°<θ<60°, 180°<θ<210°, and 210°<θ<240°, the wires 1010-1019 partially overlap and provide some contribution to the torque T generated by the rotor. This can be seen in FIG. 11B where the coil duty varies linearly with θ for 0°<θ<30°, 30°<θ<60°, 180°<θ<210°, and 210°<θ<240°.

[0059] FIG. 12A shows coil duty cycle functions 1100-1102, respectively, for all three phases A, B, and C of a conventional stator winding 300. The duty cycle functions for each phase in FIG. 12A are identical to those shown in FIG. 10B. FIG. 12B shows coil duty cycle functions 1110-1112, respectively, for all three phases A, B, and C of a stator winding 350 according to one embodiment of the present disclosure. The duty cycle functions for each phase in FIG. 12B are identical to those shown in FIG. 11B. The duty cycle functions shown in FIG. 12A-12B are similar in shape for all three phases, with the curves for each phase shifted 120° from the previous phase. FIG. 12C shows the variation of magnetic flux density B around the angular position of a stator winding of a motor having one pole pair at a given instant in time. As the magnetic rotor of the motor rotates over time, the magnetic flux density curve in FIG. 12C has the same shape but moves along the horizontal axis as the north and south poles rotate about the longitudinal axis 105 of the rotor 150.

[0060] From FIGS. 12A-12C, using Lenz's law (Equation (1)), the torque T generated by the conventional stator winding 300 and the stator winding 350 of the present disclosure can be determined using the following relationships: TIFF2025076437000006.tif5128This is essentially the area under the flux density curve of FIG. 12C multiplied by the coil duty cycle function of each of FIGS. 12A-12B. By definition, the torque constant k T is the torque T per unit current I, so the torque constant can be determined using the following relationship: TIFF2025076437000007.tif4128

[0061] FIG. 12D shows the resultant torque constant K generated by a conventional stator winding 300 (labeled “single helix”) and a stator winding 350 according to an embodiment of the present disclosure (labeled “double helix”) for one complete torque cycle. T12D. Using a six-stage DC motor controller, one complete torque cycle spans 60°. As shown in FIG. 12D, for one torque cycle of the motor, the torque constant of the dual coil stator winding 350 is increased by about 15.5% over the torque constant of the conventional stator winding 300. By "about," we mean that this value is subject to variation of about 20%, i.e., the torque increase provided by the dual helical stator winding 350 of the present disclosure may range from 12.4% to 18.6%. This definition of "about" applies to all other statements in this disclosure. In some implementations of the present disclosure, the torque increase may be at least about 15.5%.

[0062] Table 1 shows representative data for two blood pumps having three-phase, two-pole motors with single and double helical stator windings. Specifically, the single helical stator winding is similar to the conventional stator winding 300 as described above, implemented with a helical winding type 212 as shown in FIG. 2C. The double helical stator winding is similar to the stator winding 350 as described above, also implemented with a helical winding type. As shown, the double helical stator winding has the same coil resistance of 5.25 Ω / phase as the conventional single helical winding, and 1.182×10 -3 This results in a motor with an increased torque constant of N·m / A, i.e., an increase of 15.5% from the torque constant of a conventional single helical winding. Notably, the average current in the coils of the double helical stator winding is reduced by about 13.3%, thus indicating that heating in the coils of the double helical stator winding is also reduced (since the resistance of the coils is unchanged). The results in Table 1 confirm that the double helical stator winding according to embodiments of the present disclosure increases the efficiency of the motor, and therefore of the blood pump using such a stator winding. A blood pump using the above-described stator winding including two coils per phase per permanent magnet pole pair is configured to operate at flow rates of about 1.0 lpm and about 6.0 lpm, where "lpm" denotes liters per minute.

[0063] (Table 1) Performance of blood pumps with various stator coil configurations TIFF2025076437000008.tif33128

[0064] The foregoing is merely illustrative of the principles of the present disclosure, and the apparatus and methods may be practiced with other than the described implementations, which are presented for purposes of illustration and not limitation. It should be understood that while the apparatus described herein is shown with respect to a double helix stator winding in a motor for a blood pump, it may be applied to other systems where increased torque and motor efficiency are desired.

[0065] It will be understood that in the foregoing disclosure, the term "about" should be interpreted to mean ±20% of the stated value. Furthermore, the term electric motor should be interpreted as synonymous with the term electric machine, as is well known in the art. All degree measures (having units of °) should be interpreted as mechanical angles, unless otherwise specified.

[0066] Variations and modifications will occur to those skilled in the art after considering this disclosure. The features disclosed may be implemented in any combination and subcombination (including multiple subcombinations and subcombinations) with one or more other features described herein. The various features described or illustrated above may be combined or integrated in other systems, including any components thereof. Furthermore, certain features may be omitted or not implemented.

[0067] Examples of changes, substitutions, and alterations can be ascertained by one skilled in the art and made without departing from the scope of the information disclosed herein. All references cited herein are incorporated by reference in their entirety and made a part of this application.

Claims

1. 1. An intravascular blood pump for insertion into a patient's body, the intravascular blood pump comprising: a housing having a proximal end connected to the catheter and a distal end connected to the pump; and a slotless permanent magnet motor having p pole pairs and n phases contained within the housing; Including, p is an integer greater than zero and n is an integer greater than or equal to 3; The electric motor, a stator winding having 2np coils wound to form two coils per phase per pole pair, with a coil from each phase positioned circumferentially next to a coil from a different phase in phase sequence, the arrangement repeated along the stator winding such that each coil of the 2np coils spans 360 / (2np) mechanical angles around a cross section of the stator winding, each coil including an inner layer and an outer layer, the outer layer overlying the inner layer; and a permanent magnet rotor supported for rotation and configured to generate magnetic flux for interaction with the stator windings; Including, the stator windings include perpendicular components of the coils selected relative to a longitudinal length of the stator winding that interact with the rotor magnetic field and contribute to torque generated by the motor according to a coil duty function, the coil duty function having the same form for each phase but offset by 360 / n electrical degrees for each phase; Intravascular blood pump.

2. The intravascular blood pump of claim 1, wherein the coil utilization function is maximized when the vertical component is two-thirds the longitudinal length of the stator winding.

3. An intravascular blood pump as described in claim 1, wherein the two coils for each phase of each pole pair of the stator winding are connected in series so that the direction of current flow through a first of the two coils is opposite to the direction of current flow in a second of the two coils.

4. An intravascular blood pump as described in claim 3, wherein the current flow in the first coil and the current flow in the second coil interact with opposite polarities of the magnetic flux of the rotor to generate a torque in the same direction, thereby assisting in rotation of the rotor for blood flow through the pump.

5. 2. The intravascular blood pump of claim 1, wherein each of said coils includes either N / 2 turns or (N±1) / 2 turns, where N is the number of turns in a conventional stator winding having np coils wound to form one coil per phase per pole pair, and N is an integer greater than or equal to 1.

6. 6. The intravascular blood pump according to claim 1, wherein the two coils per phase are connected in series such that their start or end are connected to each other.

7. 6. The intravascular blood pump according to claim 1, wherein the two coils of each phase are connected to the coils of the other phase in either a star configuration or a delta configuration.

8. 6. The intravascular blood pump of claim 1, wherein the 2np coils include one of a helical winding, a rhomboidal winding, a conventional winding, and a hybrid winding.

9. The intravascular blood pump of any one of claims 1 to 5, wherein the electric motor comprises a three-phase, two-pole motor.

10. 6. The intravascular blood pump of claim 1, wherein the electric motor comprises a six-coil, two-pole motor, each coil spanning 60 mechanical degrees around the cross-section of the stator winding.

11. A slotless permanent magnet motor having p pole pairs and n phases, where p is an integer greater than zero and n is an integer greater than or equal to 3; the motor having a longitudinal axis; and a stator winding having 2np coils wound to form two coils per phase per pole pair, with a coil from each phase positioned circumferentially next to a coil from a different phase in phase sequence, the arrangement repeated along the stator winding such that each coil of the 2np coils spans 360 / (2np) mechanical angles around a cross section of the stator winding, each coil including an inner layer and an outer layer, the outer layer overlying the inner layer; and a permanent magnet rotor supported for rotation and configured to generate magnetic flux for interaction with the stator windings; Including, the stator windings include perpendicular components of the coils selected relative to a longitudinal length of the stator winding that interact with the rotor magnetic field and contribute to torque generated by the motor according to a coil duty function, the coil duty function having the same form for each phase but offset by 360 / n electrical degrees for each phase; Slotless permanent magnet motor.

12. The slotless permanent magnet motor of claim 11, wherein said coil utilization function is maximized when said vertical component is two-thirds the longitudinal length of said stator winding.

13. A slotless permanent magnet motor as described in claim 11, wherein the two coils for each phase of each pole pair of the stator winding are connected in series so that the direction of current flow through a first of the two coils is opposite to the direction of current flow in a second of the two coils.

14. A slotless permanent magnet motor as described in claim 13, wherein the current flow in the first coil and the current flow in the second coil interact with opposite polarities of the magnetic flux of the rotor to generate the torque in the same direction, thereby assisting in rotation of the rotor.

15. 12. The slotless permanent magnet motor of claim 11, wherein each of the coils includes either N / 2 turns for even values ​​of N, or (N±1) / 2 turns for odd values ​​of N, where N is the number of coil turns in a conventional stator winding having n coils wound to form one coil per phase per pole pair, and N is an integer equal to or greater than 1.

16. 16. The slotless permanent magnet motor of claim 11, wherein the two coils per phase are connected in series such that their start ends or end ends are connected to each other.

17. 16. The slotless permanent magnet motor of claim 11, wherein the two coils per phase are connected to the coils of the other phase in either a star or delta configuration.

18. 16. The slotless permanent magnet motor of claim 11, wherein the 2np coils include one of a helical winding, a diamond winding, a conventional winding, and a hybrid winding.

19. The slotless permanent magnet motor of any one of claims 11 to 15, comprising a three-phase, two-pole machine.

20. 16. The slotless permanent magnet motor of claim 11, wherein the motor comprises a six-coil, two-pole machine, each coil spanning 60 mechanical degrees around the cross-section of the stator winding.

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