Electric motor with selective flux stator

Abstract

The embodiments of this disclosure generally relate to electric motors with selective flux stators. Synchronous motors capable of operating multiphase power are configured to operate in a rated flux configuration and a high flux configuration. To achieve the high flux configuration, some coils wound around the stator of the motor can be designated as bypass coils and can be selectively disconnected from the power source supplying power to the motor. The remaining permanent coils continue to receive all line power and generate a rotating magnetic field with increased flux. Upon starting from a standstill, the bypass coils are selectively disconnected, resulting in a flux boost and a corresponding increase in the output torque of the motor.

Description

Technical Field

[0001] This disclosure relates to the field of electric motors. Background Technology

[0002] An electric motor is a device that converts electrical electricity into a power mechanical force as a torque output associated with the shaft of a rotating machine. Electric motors operate on various operating principles and can utilize different types of electrical power. One example is an AC synchronous motor that receives alternating current from a suitable power source. The alternating current is conductively guided through multiple conductive windings or coils arranged circumferentially around the stator of the motor. The conduction of the alternating current in the windings generates a magnetic field or magnetic flux that can electromagnetically interact with the rotor, which is rotatably mounted in the stator and concentrically surrounded by the stator. The periodic or waveform nature of the alternating current causes the magnetic field generated by the stator windings to cause the rotor to rotate concentrically around the stator, following its direction.

[0003] A characteristic of synchronous motors is that the rotational speed of the rotor is synchronized with the frequency of the alternating current conducted through the stator windings. Synchronization causes the rotor to rotate at the same speed as the rotating magnetic field. The speed at which the magnetic field rotates around the stator and the locked rotational speed of the rotor are called the synchronous speed. One disadvantage of synchronous motors (such as direct-start permanent magnet motors or cage-rotor permanent magnet motors) is that, during startup, they must quickly reach and maintain the synchronous speed, and therefore may include additional starting devices or circuit configurations. Therefore, the aforementioned types of synchronous motors may not be suitable for high-inertia load conditions, such as rotating industrial fans, blowers, or pumps that require a large amount of synchronous energy during startup. This disclosure relates to stator winding configurations for AC synchronous motors, which are particularly suitable for starting under high-inertia load conditions. Summary of the Invention

[0004] This disclosure provides an electric motor, which may be a synchronous motor suitable for operation on multiphase power. The motor may include a rotor having a motor shaft rotatably and concentrically housed in a fixed stator having a plurality of stator teeth and alternating stator slots radially disposed in concentric inner surfaces of the stator. To start the motor from a standstill and move a high-inertia load to which it may be coupled, the motor may operate in a rated flux configuration or a high flux configuration. In high flux operation, coils made of conductive wire wound around the stator teeth can generate a rotating magnetic field with an increased flux magnitude compared to operation during the rated flux configuration. To switch between the rated flux configuration and the high flux configuration, some coils may be designated as permanent coils that continuously receive all line power from the power supply, and other coils may be designated as bypass coils that can be selectively disconnected from the power supply during startup. Reducing the number of coils also reduces the effective number of turns in the motor that receive all line power; the effective number of turns is inversely proportional to the flux generated by the remaining permanent coils and the effective turns associated with them, which produces a flux boost and increases the output torque of the motor. Once the motor has reached synchronous speed, the bypass coil can be reconnected to the power supply, and the motor returns to its rated flux configuration.

[0005] One potential advantage of this disclosure is that synchronous motors (such as direct-start permanent magnet motors or cage rotor permanent magnet motors) can achieve better synchronous speeds when coupled to high-inertia loads without the need for additional drives or circuitry. Another potential advantage is that synchronous motors can replicate the starting capability of induction motors, enabling their use in high-inertia applications such as industrial fans and pumps. These and other potential advantages and features will become apparent from the following detailed description and accompanying drawings. Attached Figure Description

[0006] Figure 1 It is a perspective view depicting the axis of rotation of an electric motor configured for AC synchronous operation.

[0007] Figure 2 It is a schematic diagram of the stator of an electric motor having multiple teeth arranged concentrically and configured for operation on multiphase alternating current, the teeth alternating with multiple stator slots that accommodate multiple coils.

[0008] Figure 3 This is a schematic diagram of a possible selective reconfiguration arrangement of the coils in a phase, which is used to alternately generate a high flux state and a rated flux state according to this disclosure.

[0009] Figure 4 This is a schematic diagram of another arrangement of the coil with selective reconfiguration, which is used to alternately generate a high flux state and a rated flux state according to this disclosure.

[0010] Figure 5 This is a schematic diagram of the lap winding arrangement and concentric winding configuration of the stator windings for an electric motor according to this disclosure.

[0011] Figure 6 This is an alternative schematic diagram of a coil in which phases are selectively arranged using leads of different power.

[0012] Figure 7 This is a flowchart of an exemplary method for selectively configuring the coils of a motor between a high flux configuration and a rated flux configuration during startup. Detailed Implementation

[0013] Referring now to the accompanying drawings, in which like reference numerals denote like elements, an example of a rotary electric motor is shown, and specifically, an electric motor 100 for converting electrical energy into mechanical force in the form of torque that can be transmitted via a rotary motor shaft 102. The motor shaft 102 protrudes from the front end of a motor housing 104, which encloses and houses the internal operating components of the electric motor 100. The motor housing 104 can be made of any suitable structural material, such as cast iron, steel, aluminum, or other suitable materials, and the housing can be configured according to conventional or standardized frame dimensions that determine the location and arrangement of mounting features such as mounting feet 106 and / or eye hooks 108. Furthermore, the electric motor housing 104 can be specified according to any housing type, such as open drip-proof (ODP) or fully enclosed fan-cooled (TEFC), which determines how the electric motor 100 is constructed to interact with the operating environment to provide cooling and protect internal components from contaminants such as moisture and dust. For reference purposes, the motor shaft 102 is supported to rotate relative to the rotation axis 110 of the motor 100 and defines the rotation axis 110 of the motor 100.

[0014] To receive current from an external power source, the motor 100 may include a conduit box or junction box 112 located at a suitable position on the motor housing 104, from which extend multiple power leads 114, such as insulated wires. The power leads 114 may be electrically connected to and circuit with the external power source, which provides power with appropriate electrical characteristics and properties for the operation of the motor 100. For example, the motor 100 may be configured to operate on a multiphase alternating current (AC) power supply. In a multiphase power system, the multiple power leads 114 will each conduct AC current of the same frequency and voltage to the motor, but the AC current conducted in each power lead will be out of phase with the AC current in the other power leads. Therefore, the cyclic oscillation of the AC current in each power lead 114 between 0° and 360° will be delayed or advanced relative to the current in the other power leads. As an example, a three-phase motor 100 may include three power leads 114 and a fourth neutral or ground lead 115. The three power leads 114 conduct alternating current that is 120° out of phase with each other, and the fourth neutral or ground lead 115 may be connected to an electrical ground (e.g., the motor frame) and used as a reference. However, while aspects of this disclosure can be described with respect to multiphase AC power systems, these aspects will also apply to other types of power systems and motor configurations.

[0015] refer to Figure 2 To actuate the rotation of the motor shaft 102, a generally cylindrical rotor 116 is assembled around an extension of the shaft, which is located within a housing 104 and configured to electromagnetically interact with an annular stator 118 in which the rotor is disposed. The cylindrical rotor 116 and the annular stator 118 are concentrically aligned with the axis of rotation 110 of the motor 100 defined by the motor shaft 102. To impart electromagnetic properties to the rotor 116, the rotor may include one or more permanent magnets 120 embedded in a magnetically permeable body of the rotor. Each permanent magnet 120 has a north pole 122 and a south pole 124 and may be arranged such that the magnetic poles are close to the cylindrical surface of the rotor 116. In one example, the permanent magnets 120 may be offset relative to the axis of rotation 110 and arranged as electric cords in the rotor 116 such that the north poles 122 and south poles 124 are circumferentially alternating in position around the cylindrical surface of the rotor body; however, other arrangements of the permanent magnets are contemplated. The permanent magnet 120 responds to a magnetic field that can be generated by the stator, and the north pole 122 and south pole 124 will follow the opposite polarity of the magnetic field as they travel circumferentially around the annular stator 118, thereby causing the rotor 116 and the motor shaft 102 attached to the rotor to rotate. To allow rotation relative to the motor housing 104, the motor shaft 102 can be rotatably supported on bearings fixedly mounted to the housing. To increase electromagnetic interaction, the permanent magnet 120 can extend the axial length of the rotor 116.

[0016] To improve electromagnetic interaction with the generated magnetic field, rotor 116 can be of the cage rotor permanent magnet (“CRPM”) type, wherein the induction rotor cage 126 is embedded in the rotor body. The induction rotor cage 126 can be in the form of a cage with multiple longitudinal conductive bars made of, for example, copper or aluminum, extending generally parallel to the axis of rotation 110 and circumferentially arranged around a cylindrical surface of the rotor body. The conductive bars are electrically connected at the axial ends of rotor 116 via conductive rings. When the rotating magnetic field penetrates rotor 116, the magnetic field can cut across the conductive bars and generate a magnetic counter-field due to Faraday's law. The induced counter-field will tend to follow the stator field, thereby further exciting the rotation of rotor 116. Therefore, rotor cage 126 can facilitate starting the motor 100 from a stationary or locked rotor state. In other examples, rotor 116 may include conductive windings that receive excitation current via brushes and act as electromagnets to generate the counter-field.

[0017] An annular stator 118 may be concentrically fixed around the rotor 116 and may be spaced apart from and separated from the rotor 116 by an annular air gap 128. The stator 118 includes a stator core 130, which may be made of a magnetically permeable material such as iron or steel. In a conventional design, the stator core 130 may be made of multiple annular core laminations arranged axially in a stacked manner and extending coaxially along the axis of rotation 110. The stator core 130 may be fixed to and encapsulated within a motor housing 104, which may include fins or the like to facilitate cooling.

[0018] To accommodate the conductive windings that conduct current to generate an electromagnetic field, the stator core 130 may include a plurality of stator teeth 132 arranged radially in the circumferential direction around the rotation axis 110 and circumferentially separated from each other by stator slots 134 arranged radially in the inner cylindrical surface of the stator core 130. Thus, a stator slot 134 is provided between every two adjacent stator teeth 132, such that the teeth and slots alternate circumferentially around the inner cylindrical surface of the stator core 130. The alternating stator teeth 132 and stator slots 134 may extend axially along the axial length of the stator core 130 relative to the rotation axis 110.

[0019] The conductive winding can be a thin wire of copper or other conductive material, wound or looped around stator teeth 132 and housed in stator slots 134. The conductive winding can be wound around one or more stator teeth 132 multiple times consecutively, each turn referred to as a "turn". The total number of turns of the conductive winding around the same one or more stator teeth 132 forms a "coil". For example, a coil can be formed by a three-turn, four-turn, or five-turn conductive winding. The conductive wires of the conductive winding can then be continuously wound around additional stator teeth 132 concentrically spaced from the initial coil until the conductive winding surrounds the inner circumference of the stator core 130. The path and geometry of the conductive winding around the stator core 130 can be referred to as a "winding pattern", and the winding pattern can take various arrangements and can determine the electrical characteristics and operating principle of the motor 100.

[0020] For example, the winding pattern can be assigned or distributed to the coils by phase 136 and pole phase group 138. (Reference) Figure 2 Phase 136 may include a coil electrically connected in series with the same electrical phase of a multiphase power supply. For example, refer to... Figure 3 In a three-phase power system, for a motor 100 used to receive three-phase power, the first phase conductor 140 can be associated with the "A" phase current, the second phase conductor 142 can be associated with the "B" phase current, and the third phase conductor 144 can be associated with the "C" phase current. Phase conductors 140, 142, and 144 can be associated with... Figure 1 The power lead 114 is described as electrically connected. For reference, the conduction path of "A" phase can be represented by a short dashed line, the conduction path of "B" phase by a longer dashed line, and the conduction path of "C" phase by a solid line. A series of coils electrically connected to the respective phase conductors in the first phase conductor 140, the second phase conductor 142, and the third phase conductor 144 are referred to as phases 136. The number of coils included with each phase 136 depends on the number of stator teeth 132 and stator slots 134. In the example of the large electric motor 100 of this disclosure, the stator core 130 may include 48 stator teeth 132 separated by 48 stator slots 134, such that each phase 136 includes 16 coils (48 coils ÷ 3 phases = 16 coils / phase).

[0021] The coils can also be associated with multiple magnetic pole phase groups 138 (referred to herein as phase groups), each phase group providing a single electromagnetic pole for a single phase. A pair of phase groups 138 associated with the north and south poles of the magnetic field can be located on radially opposite sides of the inner circumferential surface of the stator core 130. In an example of a three-phase four-pole motor 100 with 48 coils arranged around the stator 118, the motor 100 would include 12 phase groups 138 (48 coils ÷ (4 poles) = 12 phase groups), where each phase group also includes 4 coils. Figure 2In the diagram, each of the 12 phase groups 138 is represented as an arc of a conductive winding, where each arc spans an adjacent stator tooth 132.

[0022] In operation, when the first phase conductor 140, the second phase conductor 142, and the third phase conductor 144 are energized by an alternating current having a 120° phase difference with the corresponding conductors, the current flowing in the multiple phases 136 generates a magnetic field of varying polarity that rotates circumferentially around the axis of rotation 110. As the polarity of a phase 136 connected to the first conductor 140 begins to change, for example, from the north pole to the south pole, the polarity of adjacent phases 136 becomes stronger due to the periodic reversal of the direction of the alternating current associated with phase "A," as they are connected to the second phase conductor 142 or the third phase conductor 144 carrying a current that is 120° phase different from the first conductor 130. The north pole 122 and the second magnetic pole 124 of the permanent magnet 120 disposed in the rotor 116 are magnetically attracted to the opposite polarity associated with the magnetic field generated by the multiple coils included in each phase 136, and will follow this polarity as it moves from one phase to an adjacent phase. Thus, the rotor 116 rotates relative to the axis of rotation 110.

[0023] The motor 100 may be a synchronous motor, such that the rotational speed of the rotor 116 is locked in sync with the frequency of the alternating current supplied to each of the three phase conductors 140, 142, 144. As explained, synchronous motors may be difficult to start in high-inertia applications, where the motor shaft 102 is coupled to large or heavy loads requiring significant torque to achieve synchronization with the rotating magnetic field. Inertia is the property of an object to remain stationary and resist movement, and torque is the rotational force required to rotate an object. Therefore, synchronous motors typically require special starting devices or circuits and are generally not suitable for direct-on-line (“DOL”) or direct-start applications. In DOL applications, the full line power, including the entire line voltage of the power supply, is immediately applied to the motor windings associated with the stator 118 to generate a magnetic field. Under locked rotor (or zero-speed) conditions, the inrush current drawn by the motor windings will increase due to the rotor 116’s resistance to reaching a speed synchronized with the magnetic field. Because DOL configurations typically include circuit breakers between the motor 100 and the power supply, the circuit breakers may trip, thus stopping the motor 100.

[0024] Therefore, to facilitate starting the AC synchronous motor 100 under high inertial loads, the winding configuration is arranged such that at least one phase of phases 136 includes one or more permanent coils and at least one bypass coil. For example, refer to Figure 3An exemplary phase 136 is shown, comprising both permanent coils 150 and bypass coils 150. In the example provided above, where the stator core 130 comprises 48 coils, phase 136, associated with one of the phase conductors 140, 142, or 144, comprises 16 total coils, which may be distributed among 12 permanent coils 150 and 4 bypass coils 152. The permanent coils 150 are arranged such that they are permanently connected to one of the phase conductors 140, 142, and 144 to continuously supply the permanent coils 150 with the full line power, including all line voltage and current, when the motor power switch is turned on and the motor 100 is connected to the power supply.

[0025] Under typical operating conditions, for example, when the motor 100 operates at synchronous speed, the bypass coil 152 can also be electrically connected to the corresponding phase conductors of the first phase conductor 140, the second phase conductor 142, and the third phase conductor 144 to receive all the line power. Because all the line power is supplied to all the permanent coils 150 and bypass coils 152 connected in series in each phase 136, the coils receive the same current and produce magnetic fields with equal magnetic flux, which can be referred to as the "normal" or "rated" flux configuration of the motor 100, where the motor operates at its rated or designed operating parameters. This configuration can also be referred to as a low flux configuration due to the relatively low magnetic flux generated by the multiple permanent coils 150 and bypass coils 152.

[0026] However, the bypass coil 152 can be selectively disconnected from all the line power conducted in the corresponding first phase conductor 140, second phase conductor 142, or third phase conductor 144 at selective times, so that the bypass coil does not conduct AC or power. The bypass coil 152 is effectively removed from the series connection of phase 136, and only the permanent coil 150 receives all the line power from the power source, and the change in the conduction path is concentrated in the AC applied in the permanent coil 150. Because the magnetic flux generated by each phase 136 and each phase group 138 varies inversely with the number of coils connected in series and the effective number of turns of each coil, reducing the total number of coils increases the magnitude of the generated magnetic flux. This results in a high flux configuration of the motor, in which the permanent coils 150 of phase 136, which remain connected in series, generate a magnetic field with a higher or increased magnetic flux or magnitude relative to the rated flux configuration described above. Therefore, the high flux configuration results in a flux boost, in which the magnitude of the magnetic flux generated by the stator 118 and attracting the permanent magnets 120 disposed in the rotor 116 is stronger. Because the mechanical torque generated by the motor 100 is proportional to the square of the magnetic flux applied to the rotor 116, the alternating current directed to the permanent coil 150 is increased by bypassing the bypass coil 152, and thus the magnitude of the magnetic flux generated by the permanent coil increases the torque output by the motor to move and synchronize high-inertia loads.

[0027] To selectively connect and disconnect the bypass coil 152 to the corresponding phase conductor of the first phase conductor 140, the second phase conductor 142, or the third phase conductor 144, and the permanent coil 150, phase 136 may include or be connected to the conductor via a switching device 156. The switching device 156 may be any suitable switching device for interrupting current or diverting current from one conductive path to another, such as a relay switch or a solid-state device. In the illustrated example, the bypass coil 152 may be most recently connected to the corresponding phase conductor of the first phase conductor 140, the second phase conductor 142, or the third phase conductor 144, and the permanent coil 150 may subsequently be connected in series with the bypass coil 152. Thus, in the rated flux configuration, the switching device 156 is configured such that both the bypass coil 152 and the permanent coil 150 receive full line power. This configuration of the switching device 156 is indicated by solid line connections.

[0028] However, in the high flux configuration, the switching device 156 can be activated to directly "tap" to the permanent coils 150, placing them in direct electrical connection with the corresponding phase conductors of the first phase conductor 140, the second phase conductor 142, or the third phase conductor 144, and bypassing or disconnecting the bypass coil 152, which is electrically isolated from the power supply to the motor 100. This configuration of the switching device 156 is indicated by a dashed line connection. As explained above, in this high flux configuration, only the permanent coils 150 receive the full line current and thus generate a magnetic field of increased magnitude. To restore the rated flux configuration, the switching device 156 can be reconfigured from the tap position to directly connect to the bypass coil 152.

[0029] The switching device 156 can be incorporated into the housing of the motor 100 or located outside the motor. In an example of an external switching device, such as... Figure 1 The additional power lead 114 shown can be directly guided from the motor 100, and in the example of a three-phase motor, three additional power leads may be included. Additionally, in the example of a three-phase motor, the switching device 156 and the additional leads may be included in each of the three phases 136 contained in the motor 100.

[0030] refer to Figure 4 This illustrates another winding configuration for phase 136 of motor 100, arranged to achieve a rated flux configuration when the motor operates at synchronous speed and a high flux configuration when starting from a stationary or locked rotor state. This can be achieved... Figure 4In the example shown, the stator 118 has a plurality of teeth and slots such that each phase 136 has a plurality of permanent coils 150 and bypass coils 152. The permanent coils 150 can be arranged in a first parallel circuit 160, in which the permanent coils are evenly distributed to one of two parallel branches. The bypass coils 152 can also be arranged in a second parallel circuit 162, in which the bypass coils are evenly distributed to one of two parallel branches. The first parallel circuit 160 and the second parallel circuit 162 can be arranged in series with each other. The first parallel circuit 160 and the second parallel circuit 162 can also be selectively connected to corresponding phase conductors of the first phase conductor 140, the second phase conductor 142, and the third phase conductor 143 via a switching device 166.

[0031] To achieve the rated flux configuration, a switching device 156 can be configured such that phase conductors 140, 142, and 144 are directly connected to a second circuit 162 upstream of the bypass coil 152 of the first circuit 160, allowing all coils of phase 136 to receive the full line power, including all line voltage and current. To achieve a high flux configuration, the switching device 160 is directly branched into the first circuit 160, bypassing the second circuit 162, and the corresponding phase conductors of the first phase conductor 140, second phase conductor 142, and third phase conductor 144 direct all line current to the permanent coil 160, thereby increasing the flux generated therein. This configuration of the switching device 166 is indicated by the dashed line configuration. The aforementioned winding pattern allows for further redirection of current through phase 136 by including the first parallel circuit 160 and the second parallel circuit 162, thereby improving the electrical characteristics and operation of the motor 100.

[0032] This disclosure can be implemented using various winding patterns already developed in the art for forming and arranging phases and phase groups. (See also...) Figure 5 The diagram shows a graphical representation of two winding patterns: "lapped winding" and "concentric winding". Figure 5In the lap winding pattern shown at the top, one side of each coil constituting phase group 138 will be positioned at the bottom of a specific stator slot 134, while the other side will be positioned at the top of another stator slot located circumferentially at several stator slot positions. The “side” of a coil can be a series of winding half-turns aligned in the same axial direction of the multiple winding turns forming the coil. The bottom and top of stator slots 134 can refer to the radial depth (or height) of the stator slots arranged in the stator core. Coils can be wound around one or more stator teeth 132 (indicated by vertical lines), and each coil in the phase group should surround the same number of stator teeth. Furthermore, the series of corresponding sides or winding half-turns of each coil will be separated by and surround the same number of adjacent stator slots 134. Thus, the individual coils of phase group 138 overlap each other within the stator slots 134 included in the arc defining phase group 138.

[0033] Because each phase group 138 includes multiple coils, the voltage applied to the phase group is distributed among the multiple coils in the group. Distribution factor (“K”) d The vector sum of voltages represents the ratio of the sum of voltages when all conducting windings are distributed among multiple coils in each phase group determined by the number of phases and poles of the motor, to the vector sum of voltages when all conducting windings are concentrated in a single coil. Distribution factor K d This represents the ratio of the voltage in a case where all turns of a set are concentrated in a single coil to the vector sum in a case where the turns are distributed across a coil with 60° phase bands.

[0034]

[0035] The combined voltage of a single lumped coil can be determined from the following formula:

[0036] Equation 2: R VCC = V C (#Coils for each phase group)

[0037] Where V C It is the voltage of each coil in the phase group.

[0038] The combined voltage (R) of the distributed coil VCD The sum of the vectors of all coils is the sum of the sums of the individual coils. Assuming the coils are distributed within a specific segment or band (called a phase band) of the 360° cycle of alternating current, for example, a 60° electrical angle in the case of a four-pole, three-phase, 48-slot motor, then the resultant voltage R is... VCD for:

[0039] Equation 3: R VCD = V C (1∠15 + 1∠30 + 1∠45 + 1∠60).

[0040] In the example of the electric motor described herein, each phase group 138 includes four coils, and the windings of the coils can be configured as follows: Figure 5 As shown. For example, the first coil 170 of phase group 138 may wrap around ten stator teeth, and thus the coil sides are located in the first and eleventh stator slots. The span or distance between the first and eleventh stator slots may be referred to as the coil throw or pitch. The second coil 172 may be circumferentially offset by one stator slot 134, such that the coil sides are distributed in the second and twelfth stator slots. Similarly, the third coil 174 may be offset by one stator slot 134 to wrap around the third to thirteenth stator slots, and the fourth coil 176 may be offset by one stator slot 134 to wrap around the fourth to thirteenth stator slots.

[0041] The span or pitch of the coil can be used to calculate the pitch factor (“K”). p The pitch factor relates the actual number of stator teeth the coils wind around to the theoretical number of stator teeth that can be allocated to the 138 phases of the motor. For a four-pole motor with 48 stator teeth:

[0042] Equation 4: K p = sin (teeth per coil / (48 teeth / 4 poles)) = sin (teeth per coil / 12)

[0043] To switch the motor between rated flux configuration during synchronous operation and high flux operation at startup, one of the first coil 170, second coil 172, third coil 174, or fourth coil 176 can be designated as a bypass coil and can be selectively disconnected from the corresponding phase conductors 140, 142, 144 and isolated from the power supply. For example, phase group 138 can typically be directly connected to the corresponding phase conductors 140, 142, 144 at the main position 178 at the beginning of the first coil 170, such that the second coil 172, third coil 174, and fourth coil 176 are connected in series to the first coil to receive all line power, including all line current. To switch to the high flux configuration, the corresponding phase conductors 140, 142, 144 can be tapped to tap position 179 and directly connected to the second coil 172, third coil 174, and fourth coil 176, thereby bypassing the first coil 170. Therefore, only the second coil 170, the third coil 172, and the fourth coil 174 receive the entire line current, thereby generating a larger magnetic flux.

[0044] If the number of winding turns, including the coils, is equal among the first coil 170, the second coil 172, the third coil 174, and the fourth coil 176, then bypassing the first coil 170 should reduce the number of conductive windings in the phase group by 25%, resulting in a corresponding increase in the total line power directed to the remaining 75% of the conductive windings in the remaining three coils. However, the coils of phase group 138 may include different numbers of winding turns, referred to as turns per coil (“TPC”), which can affect the magnitude of the magnetic flux produced by each coil between the rated flux configuration and the high flux configuration. This is because the produced magnetic flux is proportional to the number of winding turns included in the coil.

[0045] For example, phase group 138 can have a 5-4-4-4 TPC pattern, meaning that the first coil 170 includes five winding turns, and the second coil 172, third coil 174, and fourth coil 176 each include four winding turns. If the first coil 170 is designated as a bypass coil, isolating and bypassing the first coil by removing more winding turns from phase group 138 will have a correspondingly greater impact on the increase in flux in the high flux configuration. By way of example only, the flux increase ratio between the rated flux configuration and the high flux configuration could be 1.385.

[0046] If phase group 138 has a 4-5-4-4 TPC pattern, meaning that the second coil 172 includes five winding turns and the first coil 170 (as well as the second coil 174 and the third coil 176) includes four winding turns, then bypassing the first coil 170 has a more limited impact because the number of winding turns per coil isolated from the full line power is relatively small. As another example, the flux boost ratio between the rated flux configuration and the high flux configuration can be 1.285. It should be understood that different TPC patterns can be used to produce different flux ratios.

[0047] Based on the pitch factor of the electric motor K P Distribution factor K d Based on TPC and other characteristics, a theoretical equivalent circuit can be determined, which translates these characteristics into effective series conductors per phase of the motor, where the motor is conceptualized as multiple conductors connected in series. The effective series conductors per phase can be determined as follows:

[0048]

[0049] According to the above equation, and as indicated by the above discussion of the number of turns per coil winding and the magnetic flux generated by each coil, increasing the TPC or the number of turns per coil will increase the effective series conductor per phase.

[0050] refer to Figure 5At the bottom, in the concentric winding pattern, the coils within phase group 138 are concentrically organized such that the sides of each coil are separated by a different number of slot positions. For example, the first coil 180 can be the outermost coil and can wrap around 14 stator teeth. To achieve a concentric position, the sides of the first coil 180 can be located in the 1st and 14th stator slots. The second coil 182 can be concentrically arranged inside the first coil 180 and can be wound around 11 stator teeth, such that the sides of the second coil are located in the 2nd and 13th stator slots. Similarly, the third coil 184 can be wound inside a smaller number of stator teeth 132, with its coil sides located in the 3rd and 11th stator slots, and the fourth coil 186, being the innermost concentric layer, can have its coil sides located in the 4th and 11th stator slots.

[0051] Because the coil pitch differs among the first coil 180, second coil 182, third coil 184, and fourth coil 186, and assuming each coil has the same number of turns per coil, each coil comprises different winding turns of varying lengths, increasing from the innermost concentric fourth coil 186 to the outermost concentric first coil 180. Therefore, designating different coils in the concentric winding pattern as bypass coils can alter the flux ratio between the rated flux configuration and the high flux configuration of the motor. For example, in the rated flux configuration, the first coil 180, second coil 182, third coil 184, and fourth coil 186 of phase group 138 can be electrically connected in series, with the first coil 180 directly connected at the main position 188 to the corresponding phase conductor of the first phase conductor 140, second phase conductor 142, or third phase conductor 144. Thus, all four coils receive the full line power. If the first coil 180 is designated as a bypass coil, it can be bypassed by directly connecting the second coil 182 at tap position 189, so that only the second coil 182, the third coil 184, and the fourth coil 186 receive all the line power. Because magnetic flux is inversely proportional to the number of coils in a series circuit, disconnecting the bypass coil increases the generated magnetic flux.

[0052] Ideally, lap winding and concentric winding modes for motors of the same size would have identical starting and performance characteristics; however, geometric differences between the lap and concentric modes lead to certain performance differences. To assess and reduce these differences, the equations for the effective series conductors per phase described above can be used. In particular, during motor design, variables in the equations can be determined for both the lap and concentric winding modes, and these variables can be adjusted until equivalence in performance characteristics is achieved.

[0053] Because the outermost first coil 180 has a larger number of turns than the second coil 182, third coil 184, and fourth coil 186, bypassing the first coil has a significantly greater impact on the flux boost between rated flux operation and high flux operation. In one example, to better balance the effects of bypassing certain coils in a concentric winding pattern, the number of turns per coil, or TPC, can vary between the first coil 180, second coil 182, third coil 184, and fourth coil 186. For example, phase group 138 can have a 4-5-4-4 TPC pattern, meaning that the second coil 182 includes five turns, and the first coil 180, third coil 184, and fourth coil 186 each include four turns. The increased number of turns associated with the second coil 182 can mitigate the effects of bypassing the first coil 180. Alternatively, phase group 138 can have a 5-4-4-4 TPC configuration, thus including five winding turns in the first coil 180, such that bypassing the first coil has an increasing effect on the flux ratio when bypassed. In another example, the position of tap position 189 can be changed to bypass different coils, such as the concentric innermost fourth coil 186.

[0054] refer to Figure 6 An example of phase 136 with winding modes for achieving both a rated flux configuration and a high flux configuration in a concentric winding mode is shown. Phase 136 may include a total of 16 coils and includes a permanent coil 150 arranged to continuously receive all line power and a bypass coil 152 that can be selectively isolated and disconnected from all line power sources. To achieve the concentric winding mode, the bypass coil 152 corresponds to the outermost first coil 180 of the concentric winding, and the permanent coil 150 may correspond to the above-mentioned... Figure 5 The concentric inner layers are described as the second coil 182, the third coil 184, and the fourth coil 186.

[0055] Therefore, the four coils corresponding to the bypass coil 152 of phase 136 are wound around 13 stator teeth 132 and located in the first and 14th stator slots. Similarly, moving concentrically inward, the four permanent coils 150 in phase 136, corresponding to the second coil 182 of the concentric pattern, are wound around 11 stator teeth 134 and located in the second and 13th stator slots; the four permanent coils 150 in phase 136, corresponding to the third coil 184 of the concentric pattern, are wound around 9 stator teeth 134 and located in the third and 12th stator slots; and the four permanent coils 150 in phase 136, corresponding to the fourth coil 186 of the concentric winding pattern, are wound around 7 stator teeth 134 and located in the fourth and 11th stator slots.

[0056] Similar to Figure 4 The winding mode, Figure 6Phase 136 can be arranged in different parallel and series circuits. To achieve the rated flux configuration, phase 136 is electrically approached via its main position 188, which is connected to the corresponding phase conductor in the first phase conductor 140, second phase conductor 142, or third phase conductor 144, to the first coil 180 corresponding to the bypass coil 152. The permanent coil 150 and bypass coil 152 of phase 136, as well as the first coil 180, second coil 182, third coil 184, and fourth coil 186 in a concentric winding pattern, all receive the full line power.

[0057] To achieve a high flux configuration, the corresponding phase conductor of the first phase conductor 140, the second phase conductor 142, or the third phase conductor 144 is tapped to a tap position 189 that is electrically close to the second coil 182 in a concentric winding pattern. Therefore, only the second coil 182, the third coil 184, and the fourth coil 186, which correspond to the permanent coil 150 and are arranged in series, receive all the line power, and the first coil 180 is bypassed.

[0058] refer to Figure 7 The following exemplary process, according to the present disclosure, is illustrated by which motor 100 can synchronize with a high-inertia load connected to it from a stationary state. As described, motor 100 may be a synchronous multiphase motor having multiple magnetic poles and a rotor cage. In the initial startup step 200, motor 100 is connected to the high-inertia load and started in a direct-on-line (“DOL”) configuration, in which full-rated power from the power source is applied to the permanent coils of the motor and at least one bypass coil, which may be electrically connected in series. During this time, in rated flux operation 202, motor 100 operates in rated flux conditions, wherein alternating current is distributed to both permanent coil 150 and bypass coil 152 such that all coils generate magnetic fields of approximately equal flux.

[0059] To generate a flux boost when the motor attempts to reach synchronous speed, the motor can be reconfigured from a rated flux configuration to a high flux configuration by disconnecting the bypass coil. Disconnecting the bypass coil can be achieved using a switching device 156, which is operatively associated with the power leads to the motor. To actuate the switching device 156, a first detection step 204 detects control parameters for actuating the switching device 156 and bypassing the bypass coil 152 in actuation step 206.

[0060] The switching device 156 may be a timer configured to be actuated after a predetermined acceleration time during which the motor attempts to accelerate to synchronous speed. The switching device 156 may switch from a position where the bypass coil is directly connected to the power supply to a tap position where only the permanent coil is directly connected to the power supply. Alternatively, the switching device 156 may be a relay switch actuated by control parameters. The control parameters may be the rotational speed of the motor 100. For example, if the motor operates below synchronous speed, the relay switch 156 may be actuated to selectively operate the motor with a high flux configuration. In another example, the control parameter may be the current drawn by the motor 100 at startup. If the motor 100 operates below synchronous speed, the inrush current drawn may be higher than the rated current, which may be used as a control signal to actuate the relay switch.

[0061] In the high flux configuration during which the bypass coil 152 is disconnected from the power supply and is operated by high flux 208, all line power is transferred only to the permanent coil 150. Because the flux generated by the coils (e.g., per phase group) varies inversely with the number of coils connected in series, reducing the total number of coils increases the magnitude of the generated flux. This produces a flux boost in the rotating magnetic field, which increases the magnetic attraction of the permanent magnets in the rotor, thereby increasing the output torque of the motor 100. The additional torque caused by the flux boost can be used to synchronize the motion of high-inertia loads to which the motor is connected. In a possible example, the flux boost generated in the high flux configuration can be, for example, 1.3 to 1.5 times the rated flux generated in the rated flux configuration.

[0062] When the motor achieves synchronous speed—which can be determined in synchronization detection step 210 or after a predetermined time period—the motor can be reconfigured to operate again in its rated flux configuration, since the additional torque generated in the high flux configuration is no longer needed to initiate motion with a high inertia load. This can be achieved in the second actuation step 212, where the switching device 156 is actuated to directly connect the bypass coil 152 to the power supply. Because the bypass coil 152 is connected in series with the permanent coil 150, all coils in the motor receive full line power and generate a magnetic field with reduced flux. In the example where the switching device 156 is a timer, the predetermined synchronization period can be used as a control parameter for actuating the switching device. The aforementioned synchronization and acceleration periods can be determined empirically. In the example where the switching device is a relay switch, the control signal can be the motor's rotational speed, which will be approximately equal to the synchronous speed, or it can be the current drawn, which will decrease to the rated current.

[0063] In the context of describing the invention (especially in the context of the appended claims), the use of the terms “a” and “an,” “the,” and “at least one,” and similar indicators, should be interpreted to cover both singular and plural, unless otherwise stated herein or obviously contradicted by the context. The use of the term “at least one” followed by a list of one or more items (e.g., “at least one of A and B”) should be interpreted to mean one item selected from the listed items (A or B) or any combination of two or more items from the listed items (A and B), unless otherwise stated herein or obviously contradicted by the context. The terms “comprising,” “having,” “including,” and “containing” should be interpreted as open-ended terms (i.e., meaning “including but not limited to”), unless otherwise stated. All methods described herein may be performed in any suitable order, unless otherwise stated herein or obviously contradicted by the context. Unless otherwise stated, the use of any and all examples or exemplary language (e.g., “such as”) provided herein is intended only to better illustrate the invention and does not constitute a limitation on the scope of the invention. No language in the specification should be construed as indicating that any unclaimed element is necessary for the practice of the invention.

Claims

1. A multiphase synchronous motor, comprising: Rotor, including the motor shaft that outlines the axis of rotation; A stator is concentrically arranged around the rotor. The stator includes a stator core and a plurality of radially arranged stator teeth. The plurality of stator teeth are concentrically separated from each other by a plurality of stator slots, which are radially arranged in the inner cylindrical stator surface of the stator core. Multiple coils are formed by conductive windings, each of which is wound around one or more stator teeth of the plurality of stator teeth. The multiple coils are arranged in multiple phases, each of which is operatively associated with an electrical phase. At least one phase includes one or more permanent coils and at least one bypass coil. The multiple coils are arranged in a concentric winding pattern, wherein the outermost concentric coil of the concentric winding pattern is the at least one bypass coil. The main position is electrically connected to the permanent coil and the bypass coil; The tap position is electrically connected to the permanent coil; as well as The switching device is configured to selectively switch between delivering power to the tap position to bypass the bypass coil and delivering power to the main position.

2. The electric motor according to claim 1, wherein the permanent coils of the phase are electrically connected in series.

3. The electric motor of claim 2, wherein the at least one bypass coil of the phase is electrically connected to the permanent coil when not bypassed.

4. The electric motor of claim 1, wherein the one or more permanent coils and the at least one bypass coil have different numbers of turns per coil with respect to the conductive windings included in the one or more permanent coils and the at least one bypass coil.

5. The electric motor according to claim 1, wherein the electric motor is a three-phase motor having three phases, and the plurality of coils in each phase are 16 coils having 12 permanent coils and 4 bypass coils.

6. The electric motor of claim 1, wherein the electric motor is a four-pole motor, and the plurality of coils are further arranged in a plurality of phase groups, each of the plurality of phase groups having three permanent coils and one bypass coil.

7. The electric motor of claim 1, wherein the switching device is a timer configured to switch from the master position to the tap position after a predetermined acceleration period, and to switch from the tap position to the master position after a predetermined synchronization period.

8. The electric motor according to claim 1, wherein the switching device is a relay switch, and the control parameters for switching the relay switch are selected from the group consisting of motor speed and current consumption.

9. The electric motor according to claim 1, wherein the rotor is a cage rotor permanent magnet type including an induction rotor cage.

10. A method for operating an electric motor, the method comprising: The motor shaft of a multiphase synchronous motor is connected to a high-inertia load. The motor includes a plurality of coils arranged in at least one phase, the plurality of coils being arranged in a concentric winding pattern, wherein the outermost concentric coil of the concentric winding pattern is at least one bypass coil. Starting from a standstill, full line power is applied to the plurality of coils during the rated flux condition; Using a switching device, at least one bypass coil of the plurality of coils in at least one phase is disconnected from all the line power; During high flux conditions, full line power is applied to one or more permanent coils of the plurality of coils in the at least one phase; as well as After achieving synchronous operation of the motor, the switching device is used to reconnect at least one bypass coil of the plurality of coils in at least one phase to return to the rated flux configuration, and all line power is applied to the at least one bypass coil.

11. The method of claim 10, wherein after a predetermined acceleration period, the step of disconnecting the electrical connection of the at least one bypass coil occurs.

12. The method of claim 10, wherein after detecting control parameters selected from the group including motor speed and current consumption, the step of disconnecting the electrical connection of the at least one bypass coil occurs.

13. The method of claim 10, wherein the difference between the high flux condition and the rated flux condition determines the flux boost of the motor.

14. A synchronous motor, comprising: Rotor, including the motor shaft that outlines the axis of rotation; A stator, concentrically arranged around the rotor, the stator including a stator core having a plurality of radially arranged stator teeth, the plurality of stator teeth being concentrically separated from each other by a plurality of stator slots, the plurality of stator slots being radially arranged in the inner cylindrical stator surface of the stator core; Multiple coils are formed by conductive windings, each of which is wound around one or more stator teeth of the plurality of stator teeth. The plurality of coils include one or more permanent coils and at least one bypass coil connected in series. The plurality of coils are arranged in a concentric winding pattern, wherein the outermost concentric coil of the concentric winding pattern is the at least one bypass coil. In the main position, electrically connect the bypass coil and the permanent coil to the power lead; In the tap position, only the permanent coil is electrically connected to the power lead; as well as The switching device is configured to selectively switch between a rated flux condition and a high flux condition, wherein the rated flux condition connects the primary position to the power lead, and the high flux condition connects the permanent coil to the power lead to bypass the bypass coil.

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