Magnet-less and brush-less internally excited synchronous machine

Abstract

The synchronous machine (202) includes at least one rotor (102) and at least one stator (108). The rotor (102) includes a first set of windings (104) and a second set of windings (106). The stator (108) includes a third set of windings (110) and a fourth set of windings (112). The rotor (102) is positioned relative to stator (108) in order to electrically couple the second set of windings (106) and the first set of windings (104) based on a supply of power to the third set of windings (110) and the fourth set of windings (112). Further, the electrical coupling of the first set of windings (104) internally excites the synchronous machine (202).

Description

MAGNET-LESS AND BRUSH-LESS INTERNALLY EXCITED SYNCHRONOUSMACHINECross-Reference to Related Application

[0001] This application claims priority benefits of Indian provisional Application No. 202411004858, filed on January 24, 2024, entitled “MAGNETLESS AND BRUSH-LESS INTERNALLY EXCITED SYNCHRONOUS MACHINE,” which is hereby incorporated by reference in its entirety.DESCRIPTIONTechnical Field

[0001] This disclosure relates generally to electrical vehicles, and more particularly to electrical motors used in electrical vehicles and the method of their control.BACKGROUND

[0002] Every Electric Vehicle (EV) uses an electric motor to power the drive train of the vehicle. Preferably, the electric motor used in the EV must be light in weight and compact in size with high efficiency and high-power density. Presently, the most common type of electric motors used in EVs are the asynchronous motor (ASM) and the permanent magnet synchronous motor (PMSM) with magnets on surface or interior. On one hand, ASM has low efficiency, and its torque-speed characteristic is far from ideal.

[0003] On the other hand, the PMSM may overcome some of the limitations of ASM such as low efficiency and copper losses but since the PMSM uses permanent magnets on the rotor, their use is not sustainable due to environmental andgeopolitical challenges. Permanent magnets are manufactured by a variety of processes including mining rare earth minerals from the earth’s crust which may cause severe damage to the environment. Further, China dominates the rare earth minerals with about 85% market share in 2016. With this advantage, China has utilized rare earth minerals as a coercion tool against other nations including blocking exports to Japan and threatening to limit exports to the United States.

[0004] Therefore, there exists a great need for a brushless and magnet less electric machine. There is a need for a cost-effective synchronous machine with contactless energy transfer, overall reduced size, and longer life due to the reduced wear on its rotating parts.SUMMARY

[0005] In an embodiment, a magnet-less and brush-less internally excited synchronous machine is disclosed. The synchronous machine may include a rotor. Further, the rotor may include a first set of windings and a second set of windings. Further, the second set of windings may be electrically coupled to the first set of windings. Further, the synchronous machine may include a stator. The stator may include a third set of windings and a fourth set of windings. The third set of windings and the fourth set of windings may be configured to receive an AC current from at least one power source. Further, based on the supply of the AC current to the third set of windings, an AC current may be induced in the second set of windings. Further, the AC current that induced in the second set of windings may be rectified and transmitted as a DC current to the first set of windings in order to internally excite the synchronous machine.

[0006] A magnet-less and brush-less internally excited synchronous machine is disclosed. The synchronous machine may include at least one rotor. Further, the at least one rotor may include a first set of windings and a second set of windings. Further, the synchronous machine may include at least one stator. Further, the at least one stator may include a third set of windings and a fourth set of windings. Further, the at least one rotor may be positioned relative to the at least one stator in order to electrically couple the first set of windings and the second set of windings based on a supply of an AC current to the third set of windings and the fourth set of windings. Further, the electrical coupling of the first set of windings may internally excite the synchronous machine.

[0007] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate exemplary embodiments and, together with the description, serve to explain the disclosed principles.

[0009] FIG. 1 illustrates an electric circuit of the synchronous machine, in accordance with an embodiment of the present disclosure.

[0010] FIG. 2 illustrates an exploded perspective view of a salient pole or nonsalient pole inner or outer rotor synchronous machine, in accordance with an embodiment of the present disclosure.

[0011] FIG. 3 illustrates a circuit diagram of the second set of windings and the third set of windings of the synchronous machine, in accordance with another embodiment of the present disclosure.DETAILED DESCRIPTION

[0012] The foregoing description has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which forms the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying other devices, systems, assemblies and mechanisms for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristics of the disclosure, to its device or system, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

[0013] The terms “including”, “comprises”, “comprising”, “comprising of’ or any other variations thereof, are intended to cover a non-exclusive inclusions, such that a system or a device that comprises a list of components or steps does not includeonly those components or steps but may include other components or steps not expressly listed or inherent to such setup or device. In other words, one or more elements in a system or apparatus proceeded by “comprises... a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.

[0014] Reference will now be made to the exemplary embodiments of the disclosure, as illustrated in the accompanying drawings. Wherever possible, same numerals have been used to refer to the same or like parts. The following paragraphs describe the present disclosure with reference to FIGs. 1 -3. It is to be noted that motor of the present disclosure may be employed in any mechanical system such as vehicles, generators, etc.

[0015] In an embodiment, with reference to FIG. 1 , illustrates an electrical circuit 100 of a synchronous machine, in accordance with an embodiment of the present disclosure. The synchronous machine (not shown) may be a magnet-less and brush-less internally excited synchronous machine that may include a rotor 102. Further, the rotor 102 may include a first set of windings 104 and a second set of windings 106. Further, the second set of windings 106 may be electrically coupled to the first set of windings 104. It should be noted that the first set of windings 104 and the second set of windings 106 may be coupled in many ways, such as series, parallel, star-delta, etc. In an embodiment, the stator 108 may include a third set of windings 110 and a fourth set of windings 112. It may be noted that the first set of windings 104 may be Direct Current (DC) field windings, the second set of windings 106 may be AC poly-phase receiver windings, the third set of windings110 may be AC poly-phase transmitter windings and the fourth set of windings 112 may be AC poly-phase field windings.

[0016] The third set of windings 110 and the fourth set of windings 112 may be configured to receive an Alternating Current (AC) from at least one power source. In an embodiment, each of the third set of windings 110 and the fourth set of windings 112 may be separately powered by different power sources. The power source may include, but not limited to, a DC source, an AC source, a direct connection, etc. It should be noted that, based on the supply of the AC current to the third set of windings 1 10, an AC current may be induced in the second set of windings 106. Thus, there is a contactless transmission of power from the third set of windings 110 to the second set of windings 106. The power transfer is done through the air gap between the third set of windings 110 and the second set of windings 106. Further, the AC current that is induced in the second set of windings 106 may be rectified and transmitted as a DC current to the first set of windings 104 in order to internally excite the synchronous machine. A poly-phase rectifier 114 is used to rectify the AC current and transmit the DC current to the first set of windings 104. It should be noted that the fourth set of windings 112 may generate stator Magneto Motive Force (MMF) based on the received AC current and the first set of windings 104 generates rotor magnetic field based on the transmitted DC current. Further an alignment of the rotor magnetic field with the stator MMF may rotate the rotor 102 upon excitation of the synchronous machine.

[0017] Further, when the synchronous machine excites, the speed of rotation of the rotor 102 may depend on a frequency of the AC current that is supplied to the thirdset of windings 110 and the fourth set of windings 112. Further, the speed of the rotor 102 with a fixed frequency may be calculated in accordance with equation (1 );Ns=60f / P=120f / p . (1)Where, f = frequency of the AC current (Hz) p = total number of poles per phaseP = total pair number of poles per phase.For instance, if the frequency is set to 50 Hz and the motor has four poles (p=4), the synchronous machine speed is:Ns= (120*50) / 4=1500 RPMBy increasing or decreasing the frequency of the AC supply that is supplied to the third set of windings 110 and the fourth set of windings 112, the rotor 102 speed can be adjusted.

[0018] Referring now to FIG. 2, an exploded perspective view 200 of a salient pole inner rotor 102 synchronous machine 202, in accordance with an embodiment of the present disclosure. As can be seen, the synchronous machine 202 may include a rotor 102 and a stator 108. As can be seen the synchronous machine 202 may include a shaft 204. The shaft 204 may include a first end 204A and a second end 204B. Further, the rotor 102 may be co-axially mounted on the shaft 204 and positioned between the first end 204A and the second end 204B. Further, the stator 108 may be co-axially mounted on the rotor 102 between the first end 204A and the second end 204B.

[0019] In an embodiment, the rotor 102 may have a set of rotor poles and the stator 108 may have a set of stator poles. Further, the set of rotor poles may have a first rotor pole and a second rotor pole. The first set of windings 104 are coupled to the first rotor pole and the second set of windings 106 are coupled to the second rotor pole. Furthermore, the set of stator poles may include a first stator pole and a second stator pole. Further, the third set of windings 110 may be coupled to the first stator pole and the fourth set of windings 1 12 may be coupled to the second stator pole. It may be noted that the set of rotor poles and the set of stator poles may be made of electromagnetic steel. It should be noted that the third set of windings 110 and the fourth set of windings 112 may be stranded windings or hairpin windings.

[0020] It should be noted that the rotor 102 may be a salient rotor or a non-salient rotor and may be an inner configuration rotor or an outer configuration rotor. Further, the rotor 102 may be made of material such as, but not limited to, laminated silicon steel. The stator 108 may be an inner configuration stator or an outer configuration stator. The stator 108 may be configured to operate at any voltage level between a rated voltage of the synchronous machine 202. Further, the synchronous machine 202 may include a housing 206 having a first opening 206A and a second opening 206B. Further, the housing 206 may be configured to mechanically support the stator 108.

[0021] It may be noted that the synchronous machine 202 may be assembled by placing the components of the synchronous machine in the housing 206. In anembodiment, the housing 206 may be cast and may feature cooling fins (not shown) in order to ensure proper ventilation and heat exchange.

[0022] Further, the synchronous machine 202 may include a first endcap 208A and a second endcap 208B. The first endcap 208A and the second endcap 208B may be configured to enclose the first opening 206A and the second opening 206B respectively of the housing 206. The first endcap 208A may attach to the first opening 206A and the second endcap 208B may be attached to the second opening 206B respectively of the housing 206. In an embodiment, the first endcap 208A and the second endcap 208B may be cast in a manner that they are capable of withstanding radial loads.

[0023] Further, the first endcap 208A and the second endcap 208B may support the first end 204A and the second end 204B of the shaft 204 using bearings 210A and 210B respectively on both ends. The first endcap 208A may include an aperture 212 to allow an external radial load to connect a first end 204A of the shaft 204. The second endcap 208B may include a groove or a cup 214 as a means to support the second end 204B of the shaft 204 respectively in order for it to be suspended in the housing 206.

[0024] Further, when the synchronous machine internally excites, the cup 214 may enable rotational movement of the shaft 204. Furthermore, the cup 214 may be steel dimensioned to fatigue and may be capable of withstanding alternating stress due to bending movement and static stress due to output torque. In an embodiment, each of the first end 204A and the second end 204B of the shaft 204are provided with seals 216, which may be dust seals capable of operating at high speeds and temperatures.

[0025] Further, the poly-phase rectifier 114 may be coaxially mounted towards the second end 204B of the shaft 204. In an embodiment, the poly-phase rectifier 1 14 may be a poly-phase bridge diode rectifier. In case the rotor 102 is an inner configuration rotor and the poly-phase rectifier 114 may be fixed to the shaft 204. In case the rotor 102 is an outer configuration rotor, the poly-phase rectifier 1 14 may be mounted on the shaft 204 via a bearing (not shown). Further, the polyphase rectifier 1 14 may include a plurality of diodes that may be selected in a way that the plurality of diodes must withstand the high temperatures inside the synchronous machine 202.

[0026] It should be noted that the poly-phase rectifier 1 14 may be selected from a group of well-known poly-phase rectifiers, but with selected diodes that withstand the high temperatures near the windings and hold firmly to the PCB while simultaneously resisting centrifugal stresses.

[0027] Further, the rotor 102 and the stator 108 are positioned with respect to each other such that the first set of windings 104 and the second set of windings 106 are electrically coupled based on a supply of power to the third set of windings 1 10 and the fourth set of windings 112. lt may be noted that the rotor 102 and the stator 108 may be proximally coupled to each other by being positioned at predefined axial distance with respect to each other. In an embodiment, an AC power source may be used to provide AC current to the third set of windings 110 and the fourthset of windings 112. Upon receiving power, the third set of windings 110 may induce an AC current in the second set of windings 106.

[0028] Further, the poly-phase rectifier 114 may electrically couple the second set of windings 106 and the first set of windings 104. Further, the poly-phase rectifier 114 may rectify the AC current induced in the second set of windings 106 to a DC current that may be transmitted to the first set of windings 104 of the rotor 102 in order to internally excite the synchronous machine 202. The fourth set of windings 112 generates stator Magneto Motive Force (MMF) based on the received AC current and the first set of windings 104 generates rotor magnetic field based on the transmitted DC current. An alignment of the rotor magnetic field with the stator MMF rotates the rotor 102 upon excitation of the synchronous machine 202.

[0029] Though the assembly of the synchronous machine 202 in FIG. 2 is explained with a radial flux motor topology, those skilled in art will recognize that the invention disclosed here can be applied to axial flux motor topology, linear motor topology, shaft less motor topology, and external rotor motor topology. Similarly, it can also be applied to motoring applications or generating applications. Further, the synchronous machine 202 may be shaft-less as well. Similarly, the synchronous machine 202 may include a plurality of rotors 102 and a plurality of stators 108 that may be positioned relative to each other such that the first set of windings 104 and the second set of windings 106 are electrically coupled based on a supply of power to the third set of windings 110 and the fourth set of windings 112 to rotate the plurality of rotors 102 based on internal excitation.

[0030] Referring now to FIG. 3, an electric circuit 300 of the third set of windings 110 and the second set of windings 106 of the synchronous machine 202 is illustrated, in accordance with an embodiment of the present disclosure.

[0031] A synchronous motor operates fundamentally on alignment torque, but it can also operate on reluctance torque, generally at high speeds. To provide alignment torque, the machine needs a rotor MMF (Magneto Motive Force), generally denoted by (Fr). When applying a symmetrical and balanced three-phase current system to a three-phase symmetrical winding, a rotating MMF will give place in the machine airgap (Fs). The rotor MMF (Fr) will tend to align with the (Fs), for providing torque. As (Fs) is constantly rotating, (Fr) will be rotating too, and with it the shaft 204 will also rotate.

[0032] In order to produce (Fr), the synchronous machine 202 includes the first set of windings 104 that are DC field windings in its rotor 102. The first set of windings 104 replace magnets used in conventional motors. To provide DC current to the rotor 102 without the use of brushes, the inventive synchronous machine 202 is equipped with the third set of windings 110 within the stator 108 and the second set of windings 106 within the rotor 102 combined with the rectifier 114. The combination of these components, a correct design and an adequate control will yield an endurable, efficient, and power dense machine of our present disclosure. The inventive third set of windings 110 and the second set of windings 106 allow for full speed range sensor-less control and sensor-less detection of rotor temperature. And because it has no magnets, it can handle high temperatures anddemagnetizing currents, a valuable characteristic that makes it implementable in small vehicles, 3-Wheelers and bikes.

[0033] In some embodiments, the fourth set of windings 112 that are poly-phase AC field windings of the stator 108 may be excited by an AC power source. Upon excitation of the AC field windings of the stator 108, the stator 108 may produce a rotating magnetic-field. Further, the first set of windings 104 that are DC field windings of the rotor 102 may be excited by the DC current. Upon excitation of the first set of windings 104 of the rotor 102, the rotor 102 may produce a stationary magnetic-field relative to the rotor 102. It should be noted that the first set of windings 104 of the rotor 102 is excited by the DC current received based on rectified AC current induced by the third set of windings 110 in the second set of windings 106.

[0034] Further, the rotating magnetic-field of the stator 108 may align with the rotor magnetic-field of the rotor 102 and the rotor 102 may rotate in synchronization with the frequency of the stator 108. In simpler words, the speed of rotation of the rotor 102 may depend on the frequency of the alternating current supplied to the stator 108 and the number of poles. Further, the speed of the rotor 102 may be calculated in accordance with equation (1 ) mentioned earlier.

[0035] It should be noted that the electrical circuit 300 is the equivalent single-phase electrical circuit of the third set of windings 110 and the second set of windings 106. When applying a poly-phase current to the third set of windings 110, high frequency magnetic field is created within the machine 202, and a voltage isinduced in the second set of windings 106 which may then be fed to the rectifier114.

[0036] It should be noted that the third set of windings 110 and the second set of windings 106 does not produce torque. As the first set of windings 104 of the rotor 102 is a DC winding, thus the poly-phase rectifier 114 may convert the AC electric power from the second set of windings 106 into DC electric power.

[0037] In some embodiments, a problem may arise with respect to the third set of windings 110 and the second set of windings 106 in terms of frequency as the machine speed may be variable. By way of an example, if the poly-phase rectifier 114 is designed to operate at about 10kHz, but at some speed the frequency goes below that, rectifying will lose quality and current ripple may take place in the field windings which may produce torque oscillations in the synchronous machine 202. The current disclosure provides a solutions to solve this problem.

[0038] It should be noted that depending on spinning direction of the synchronous machine 202, frequency ( / r) of the second set of windings 106 may increase or decrease as per equation (2) below. fr - fs ± prNs . (2) where, fs frequency of the second set of windings 106; pr: count of the set of rotor poles; Ns: shaft speed.Accordingly, to keep the frequency (fr) of the second set of windings 106 constant, a solution may be to keep the number of poles as low as possible.

[0039] In some embodiments, one of the design constraint may be that the output frequency of the synchronous machine 202 must remain within the rectifier’s 114adequate frequency limits regardless of the rotor speed. To ensure this, the number of set of stator poles and the set of rotor poles must be minimized in the second set of windings 106 and the third set of windings 110 to ensure low output frequency variation with respect to the rotor speed. It should be noted that the count of the set of rotor poles and the set of stator poles to which the second set of windings 106 and the third set of windings 110 may be coupled must be equal in a way to induce the same magnitude of the AC current in the second set of windings 106 as in the third set of windings 110. Further, at stall condition, the second set of windings 106 frequency may be same as the frequency of the third set of windings 110 but at positive speed the second set of windings 106 frequency may change according to below equation: fr - fs + prNsBut for negative speed, the second set of windings 106 output frequency may change according to: fr - fs - prNs

[0040] Thus, the poly-phase rectifier 114 may be designed to operate correctly within the range of fr. If the number of poles is very high, the output frequency may be very low at significant negative speeds which may produce current oscillations in the poly-phase AC field windings and consequently, torque ripples in the synchronous machine 202.

[0041] In some embodiments, one of the design constraint may be that the synchronous machine 202 must be efficient across the whole motor operating speed region. To ensure the high efficiency of the synchronous machine 202, thefrequency of the second set of windings 106 and the third set of windings 110 may be increased, thus reducing the magnetizing current. Further, the count of the set of stator poles and the set of rotor poles may be kept minimum such that the magnetizing inductance increase, thus reducing the magnetizing current.

[0042] In another embodiment, in order to keep output frequency of the synchronous machine 202 within the rectifier's adequate frequency limits regardless of the rotor speed, different pole combinations may work. But for optimal performance, number of poles of the third set of windings 110 and the second set of windings 106 may be reduced to ensure low receiver frequency variation with respect to rotor speed. For example, for a given operation frequency, a 2-pole for third set of windings 1 10 and for the second set of windings 106 may perform better than a 4-pole.

[0043] In case the rotor 102 speed is negative, the rectifier 114 will have to be designed to operate correctly within the range of fr. However, if the count of poles of the second set of windings 106 and the count of poles of the third set of windings 110 is very high, output frequency (the frequency of the second set of windings 106 which is then rectified) could be very low at significant negative speeds, producing current oscillations in the field winding, and consequently, torque ripple.

[0044] Further, the third set of windings 110 and the second set of windings 106 may be, but not limited to, a distributed winding type. It is to be noted that the second set of windings 106 and the third set of windings 110 may be different types of windings.

[0045] In an embodiment, the rectifier 114 may be a poly-phase or single-phase full bridge inverter used to control the third set of windings 110 and the second set of windings 106. Commutation devices are selected depending on the current, voltage and frequency of the third set of windings 110 and the second set of windings 106. Known PWM techniques may be used to ensure full usage of the DC bus. In simpler words, the field current may be controlled by controlling the current in the second set of windings 106 which may be further controlled by the third set of windings 110. In an embodiment, the frequency of the third set of windings 110 shall remain fixed, but stator voltage may be changed depending on the desired field current.

[0046] Referring now to FIG. 1 to FIG. 3, in an embodiment, the synchronous machine 202 may operate fundamentally on alignment torque but the synchronous machine 202 may operate on reluctance torque at high speeds. To generate alignment torque, the synchronous machine 202 may need a rotor Magneto Motive Force (MMF) denoted by (Fr). When applying a symmetrical and balanced three phase current system to a three-phase symmetrical winding, a rotating MMF may generate in the synchronous machine 202 airgap, this may be denoted by (Fs). The rotor MMF (Fr) may tend to align (Fs) providing the torque. As (Fs) is constantly rotating, (Fr) will be rotating too, and with it the shaft 204 of the synchronous machine 202 will rotate.

[0047] Further, in order to produce (Fr), the machine 100 may need the DC field winding in the rotor 102. To provide the DC current to the rotor 102 without the use of brushes, the second set of windings 106 and the third set of windings 110 maybe used in combination with the poly-phase bridge rectifier 114. It should be noted that the third set of windings 1 10 and the second set of windings 106 must operate at positive speed, negative speed, and at stall condition and the receiver winding output frequency must remain as constant as possible independently on rotor speed as to ensure a quality DC current output from the rectifier 114. Further, the third set of windings 110 and the second set of windings 106 may allow full speed range sensor-less control and rotor temperature sensor-less detection. Accordingly, the third set of windings 110 and the second set of windings 106 may be controlled via a poly-phase full bridge inverter instead of rectifier 114 using one or more modulation techniques such as, but not limited to, a pulse width modulation technique, etc. It should be noted that the second set of windings 106 may be mounted on the rotor 102 which may be configured to rotate with the action of torque on the rotor 102. Further, the second set of windings 106 may feed the AC current to the rectifier 114 which may be further fed to the DC field windings of the rotor 102. It should be noted that the rectifier 1 14 may be mounted on the rotor 102 which may be configured to rotate with the rotor 102.

[0048] In some embodiments, the synchronous machine 202 may be capable of controlling the DC current in the first set of windings 104 of the rotor 102 without a current sensor in the rotor 102. A lookup table may be preferred rather than online calculation, linear interpolation may be used to estimate values that may not be in the table, but within its range.

[0049] In some embodiments, the synchronous machine 202 may be capable of detecting the temperature (T) of the first set of windings 104 of the synchronousmachine 202 without a temperature sensor. The temperature (T) may be easily calculated if the resistance of the first set of windings 104 (RFref) is known at a reference temperature Tref and at the operating temperature T.

[0050] where T=234.5 °C for copper in the operating temperature ranges of the machine and Tref may be 25 degree Celsius or predefined based on design choice. The resistance of the first set of windings 104 may be determined as per equation (6):and the value of UDC and IDC may be calculated using machine parameters such as resistance, inductance, etc.

[0051] In some embodiments, the detection of the EMF produced by the magnetic field of the synchronous machine 202 may help in detecting the rotor 102 position without using sensors. However, there may be some problems in detecting the position of the rotor 102. One of the problem may be that the EMF cannot be measured, it must be calculated with a machine mathematical model, which may be very inaccurate and may depend on temperature and saturation of the synchronous machine 202. Further, if the rotor 102 is at stall, then there may not be any EMF in the machine 100, thus the position of the rotor 102 may not be known.

[0052] In an embodiment, the rotor position may be determined based on EMF esiproduced in the stator phases due to the machine main flux. EMF esimay be calculated using equation below:is a DC field current and a> the rotor angular speed. Note that the EMF is zero if rotor speed a> is zero.

[0053] Further, current is I2 in the second set of windings 106 in the rotor 102 is an AC current, which creates a flux that induces electromotive forces in each of the stator phases. These electromotive forces are used to calculate the rotor position. Accordingly, the synchronous machine 202 may be coupled to a controller configured to determine a position of the rotor 102 based on determination of electromotive force in each of the stator phases, the DC current is transmitted to the first set of windings 104.

[0054] The techniques described above relate to a magnet-less and brush-less internally excited synchronous machine. The above techniques provide a cost- effective solution for reducing wear and tear in a synchronous machine. The techniques provide a more efficient and reliable synchronous machine that may be used for variety of purposes. The synchronous machine includes the set of transmitter windings and the set of receiver windings that may replace the brushes and the slip rings in the machine thus reducing friction, and wear and tear. The techniques may also provide full speed range sensor-less control and rotortemperature sensor-less detection in the synchronous machine 202. Further, the technique provides a method to design synchronous machines without magnets which may be beneficial for the environment. The synchronous machine 202 may handle high temperatures and demagnetizing currents as it has no magnets. Further, the techniques provide the capability for the synchronous machine to operate at any voltage between the operating range of voltage. The synchronous machine may also operate at any speed between the operating range of speed. The synchronous machine may operate at an approximately constant frequency resulting in minimum power losses thus increased efficiency.

Claims

AMENDED CLAIMS received by the International Bureau on 18 July 2025 ( 18.07.2025) l / We Claim:

1. A magnet-less and brush-less internally excited synchronous machine (202), comprising: a rotor (102), comprising: a first set of windings (104) configured to generate a rotor magnetic field, wherein the first set of windings are Direct Current (DC) field windings; and a second set of windings (106) electrically coupled to the first set of windings (104), wherein the second set of windings is AC poly-phase receiver windings; a stator (108) comprising: a third set of windings (110, wherein the third set of windings is AC poly-phase transmitter windings; and a fourth set of windings (112) configured to generate stator Magneto Motive Force (MMF), wherein the fourth set of windings is AC poly-phase field windings, wherein the third set of windings (110) and the fourth set of windings(112) are configured to receive AC current from at least one power source, wherein based on the AC current supplied to the third set of windings(110), AC current is induced in the second set of windings (106), wherein the AC current induced in the second set of windings (106) is rectified and transmitted as a DC current to the first set of windings (104) in order to internally excite the synchronous machine (202), and28wherein an alignment of the rotor magnetic field with the stator MMF causes rotation of the rotor (102) upon excitation of the synchronous machine (202).

2. The magnet-less and brush-less internally excited synchronous machine (202) as claimed in claim 1 , wherein speed of the rotation of the rotor (102) depends on a frequency of the AC current supplied by the at least one power source.

3. The magnet-less and brush-less internally excited synchronous machine (202) as claimed in claim 1 , wherein the rotor (102) comprises a set of rotor poles and the stator comprises a set of stator poles, wherein a count of the set of rotor poles is equal to a count of the set of stator poles.

4. The magnet-less and brush-less internally excited synchronous machine (202) as claimed in claim 3, wherein the set of rotor poles comprises: a first rotor pole and a second rotor pole, wherein the first set of windings (104) are coupled to the first rotor pole, and wherein the second set of windings (106) are coupled to the second rotor pole, and wherein the set of stator poles comprises: a first stator pole and a second stator pole,wherein the third set of windings (110) are coupled to the first stator pole, and wherein the fourth set of windings (112) are coupled to the second stator pole.

5. The magnet-less and brush-less internally excited synchronous machine (202) as claimed in claim 1 , comprising a poly-phase rectifier (114) electrically coupling the second set of windings (106) and the first set of windings (104), wherein the poly-phase rectifier (114) rectifies the AC current induced in the second set of windings (106) to the DC current transmitted to the first set of windings (104).

6. The magnet-less and brush-less internally excited synchronous machine (202) as claimed in claim 1 , comprises: a shaft (204) mechanically coupled to the rotor (102); the rotor (102) is proximally coupled to the stator (108); and a housing (206) configurable to mechanically support the stator (108).

7. The magnet-less and brush-less internally excited synchronous machine (202) as claimed in claim 7, wherein the rotor (102) is co-axially mounted on the shaft (204), wherein the stator (108) is co-axially mounted over the rotor (102), wherein the housing (206) comprises a first opening (206A) and a second opening (206B), andwherein a first endcap (208A) is attached to the first opening (206A) and a second endcap (208B) is attached to the second opening (206B).

8. The magnet-less and brush-less internally excited synchronous machine (202) as claimed in claim 8, wherein the first endcap (208A) comprises an aperture (212) configured to allow an external radial load to connect to a first end (204A) of the shaft (204).

9. The magnet-less and brush-less internally excited synchronous machine (202) as claimed in claim 8, wherein the second endcap (208B) comprises a cup (214) configured to support a second end (204B) of the shaft (204) and enable rotational movement of the shaft (204) upon internal excitation of the synchronous machine (202).

10. A magnet-less and brush-less internally excited synchronous machine (202), comprising: at least one rotor (102) comprising: a first set of windings (104) configured to generate a motor magnetic field, and wherein the first set of windings are Direct Current (DC) field windings a second set of windings (106), wherein the second set of windings is AC poly-phase receiver windings; at least one stator (108) comprising:a third set of windings (110), wherein the third set of windings is AC poly-phase transmitter windings; and a fourth set of windings (112) configured to generate stator Magneto Motive Force (MMF), wherein the fourth set of windings is AC poly-phase field windings, wherein the at least one rotor (102) is positioned relative to the at least one stator (108) in order to electrically couple the first set of windings (104) and the second set of windings (106) based on a supply of power to the third set of windings (110) and the fourth set of windings (112), and wherein the electrical coupling of the first set of windings (104) internally excites the synchronous machine (202).11 . The magnet-less and brush-less internally excited synchronous machine (202) as claimed in claim 10, wherein the induced AC current in the second set of windings (106) is rectified into a DC current by a poly-phase rectifier (114), and wherein the DC current is transmitted to the first set of windings (104) in order to internally excite the synchronous machine (202).

12. The magnet-less and brush-less internally excited synchronous machine (202) as claimed in claim 10, wherein a position of the rotor (102) is determined based on determination of electromotive force in each phase of the stator (108), the DC current transmitted to the first set of windings (104) by a controller.

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