MXPA98000177A - Permanent magnet machine of double projection with capacity of weakening (or intensification) of the induc field - Google Patents

Abstract

A permanent magnet machine (10) combines both principles of variable reluctance machines or permanent magnets and comprises a rotor (II) with protruding rotor poles (12) and a stator (14) with protruding stator poles (16 and 17) a pair of curved permanent ferrite magnets (21 and 22) are embedded in the stator fork (15) pro below the respective stator poles (16 and 17) and installed symmetrically around the central axis (13) of the machine (10) An inductor winding (F) to intensify or weaken the primary flow generated by the permanent magnets (21 and 22) is wound up in a specific installation.

Description

PERMANENT DOUBLE-PROOF MAGNET MACHINE WITH THE CAPACITY OF WEAKENING (OR INTENSIFICATION) OF THE INDUCTOR FIELD BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to variable reluctance machines, and particularly, to double-ended permanent magnet machines with weakening or intensifying capabilities, which function as motors or generators. 2. Description of Background In an attempt to perform high performance in electric machines, the option of using permanent magnet (PM) materials has become increasingly popular for many applications. A common disadvantage of conventional PM machines is the low viability of the field flow control inductor, which limits the operation of these machines over a wide range of speed. Giving as a result of the effort to improve the performance of conventional PM machines, the concept of PM double output machines provides a new insight for the understanding of electrical machines. In general, the combination of the principle of variable reluctance machines and the use of PM excitation results in a machine that possesses the above mentioned advantages specifically, simple structure and high power density. In addition, this kind of machine can operate well at higher speeds when using the inherent reluctance torque. The machines of permanent magnet of double salient possess a greater densidad of power and a better performance that the conventional machines. In the double-projecting structures of the permanent magnet machines, the rotor and the stator each comprise separate poles spaced at equal angular intervals, in some double-ledge structures different angle intervals could be obtained; and the protruding poles of the stator have respective windings. Permanent magnets that produce a magnetic flux can be incorporated into the rotor; this is described, for example, in U.S. Patent No. 5,304,882, or in the stator, as described, for example, in pending application Serial No. 07 / 926,765, filed on August 6, 1992, and as shown in FIG. Figures 1 and 2 of the present application. The double projecting structure operates with the permanent magnets or the auxiliary field inductor winding to alter the magnetic circuit of the motor (or generator), thus improving the inductive coupling. While maintaining all the advantages of double-projection machines with permanent magnets buried in the stator, however, the structures mentioned above have the following inherent problems. 1. The special location of the permanent magnets in the stator leads to a square or oval shape of the machine that is not suitable for the machine housings currently available on the market. If a round machine is used, more permanent rare earth or steel magnets will be necessary, resulting in not fully using the steel in the stator fork; in addition to the total cost of the machine significantly higher. 2. Low viability to control the field flow inductor when necessary. This is also a major problem inherent in other electric machines a.c. that use permanent magnets as a means of excitation of the inductor field. It would be highly desirable to enjoy a higher output voltage, a fast response, and a higher efficiency inherent in the permanent double-nose magnetic machines in combination with the round cylindrical shape, a lower total cost, a lower inductive coupling, weakening capacity or intensification of the inductor field, an easier demagnetization protection and a lighter weight.

BRIEF SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a variable reluctance machine of a double projecting structure and having permanent magnets stationary in the stator, capable of use as a motor or an economic and efficient generator. It is another object of the present invention to provide a permanent double-pronged magnetic machine having high power density, weakening or intensifying field strength, easy demagnetization protection, low cost and light weight. It is still another object of the present invention to provide a round cylindrical double projection machine which uses permanent ferrite magnets in the stator instead of rare earth permanent magnets, these permanent magnets being installed in the stator in a special manner. It is still another object of the present invention to provide a dual-projection PM machine wherein the stator comprises two windings, one of which is always coupled to the flow path of the machine and installed in such a way as to provide a weakening or intensification of the inductor field. According to the teachings of the present invention, a permanent magnet machine includes a rotor mounted for rotation about a central axis and having the protruding rotor poles spaced at equal angular intervals and further includes a stator having a fork of stator of a round shape in its cross section with the stator poles projecting spaced at equal angular intervals around the central axis and extending inwardly from the stator fork A pair of curved permanent magnets (round in cross section) are embedded in the stator fork, each within a first or second respective section of the stator fork and below the corresponding stator poles. A winding of the inductor field is interposed between the first and second section and is wound along the length of the stator fork. The inductor field winding is permanently coupled with a main flow path. The armature windings are wound on the stator; each winding is individually wound around a pair of diametrically opposed stator poles. The first and second permanent magnets are permanent ferrite magnets, which are polarized transversely to the central axis of the machine to serve as a source of a primary flow to magnetize the machine.

Once the winding of the inductor field is excited by activation means, it is capable of producing the amperes of demagnetization or magnetization to intensify or weaken the primary flux produced by the first and second permanent magnets. If the inductor field winding is not excited, it can be used to detect the position of the rotor by measuring the induced voltage in the inductor field winding by varying the flow link of the inductor field winding by means of the armature coils as a function of a rotor angle. A suitable means converts a three-phase alternating current into an unregulated direct current. If the ratio of the rotor poles to the stator poles is 4: 6, and the armature windings are three-phase armature windings, the machine operates as a motor or as a three-phase generator. If the ratio of the rotor poles to the stator poles is 6: 4 (for example, four stator poles and six rotor poles) a pair of armature windings is wound around the stator poles; and the converter means is connected to these windings of the armature to convert the alternating current obtained from the windings of the first and second armature to the direct current, in such a way that the machine can develop as a single-phase generator. It will be appreciated by those skilled in the art that both the permanent magnet and the winding of the inductor field are not mandatory for the machine of the present invention to function. Others, simplified versions of this topology, could be made by eliminating permanent magnets (replacing them with iron), in which case only the field winding inductor is used for excitation. Alternatively, the winding of the inductor field could be removed by retaining only the permanent magnets. Even if the capacity of weakening or intensification of the inductor field is lost, the resulting machine will function satisfactorily as a PM-type machine. Other objects, features, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments and certain modifications thereof when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-section of a three-phase double-overhead PM motor of the prior art. Figure 2 is a cross-section of a single-phase double-ended PM generator of the prior art. Figure 3 is a cross-section of a three-phase double lead PM motor of the present invention. Fig. 4 is a topology of the motor converter of Fig. 3. Fig. 5 is another topology of the motor converter of Fig. 3. Fig. 6 is a topology for the control of the speed of the permanent double-byte magnet motor. of weakening of the inductor field (FWDSPM) of the present invention. Figure 7 illustrates the principles of operation of the double permanent magnet motor Weakening projection of the inductor field (FWDSPM) of Figure 3. Figure 8 illustrates the waveforms of the motor current of the present invention. Figure 9 shows a flow distribution of the permanent magnet motor with double projection weakening of the inductor field (FWDSPM) only when the excitation of the PM exists. Figure 10 shows a flux distribution of prototype permanent magnet motor with double protrusion weakening of the prototype inductor field only when there is excitation of the armature current. Figure 11 schematically shows a phase of the inductive coupling of PM versus the angle of the motor under different levels of excitation of the inductor field current. Figure 12 schematically shows the characteristics of the torque velocity of the permanent magnet motor with double projection weakening the inductor field under different levels of the inductor field excitation. Figure 13 is a cross section of a single-phase double-ended permanent magnet generator of the present invention. Fig. 14 shows the connection of the winding of the inductive field weakening inductor (BDM) permanent magnet double generator of the present invention. Fig. 15 shows the connection of the winding of the double-acting permanent magnet generator of weakening of the inductor field (UDM) of the present invention. Fig. 16 is a topology of the generator converter of Fig. 8. Fig. 17 is a control topology of the double-led permanent magnet generator for weakening the inductor field (BDM). Figure 18 is a control topology of the permanent double-salient magnet generator for weakening the inductor field (UDM). Figure 19 schematically shows the energy conversion of the double-lead permanent magnet generator of weakening of the inductor field (BDM) purchased with the VRM (W and W 'are the areas of energy conversion with the VRM and the permanent magnet of double outgoing weakening of the inducing field, respectively). Figure 20 shows diagrammatically the energy conversion of the permanent magnet generator of double outgoing weakening of the inductor field (UDM) purchased with the VRM (W and W 'are the areas of energy conversion with the VRM and the permanent magnet of double outgoing weakening of the inductor field, respectively). Figure 21 shows diagrammatically the production of torque of the permanent magnet machine with double projection weakening the inductor field in bidirectional (idealized) mode. Figure 22 schematically shows the torque output of the permanent magnet machine with double projection weakening the inductor field in the unidirectional operation mode (idealized). Figure 23 shows a flow distribution of the permanent double-salient magnet generator of weakening of the inductor field when only the excitation of the PM exists. Figure 24 shows a flow distribution of the permanent double-salient magnet generator of weakening of the inductor field when only the armature current excitation exists. Figure 25 shows the inductive coupling of the permanent phase magnet versus the angle of the rotor under different levels of excitation of the inductor field current. Figure 26 shows schematically the results of the generator simulation (UDM) of the present invention. Figure 27 schematically shows the results of the generator simulation (BDM) of the present invention. DESCRIPTION With reference to Figure 3, a cross-section of a three-phase double-ended (PM) permanent magnet machine 10 of the present invention is shown, a double-sided permanent magnet motor for weakening the inductor field (FWDSPM), a rotor 11 consisting of a plurality of discrete lamin layers, each of which is perfor to form four (4) protruding rotor poles 12 placed at angular intervals ρ r of 2 radians. Each pole of rotor 12 has a polar arc? Pr equal to or slightly gre than p / 6 radians. The rotor 11 is mounted for rotation about a central axis 13 as known to those skilled in the art. A stator 14 includes a stator fork 15 having a round shape in its cross section. The stator 14 consists of a plurality of discrete lamin layers, each being perfor to form projecting stator poles. As best shown in Figure 3, the stator 14 includes three stator poles 16 and three stator poles 17, where the stator poles 16 are placed within a first section 18 of the stator fork 15, and where the stator poles 17 are placed within a second section 19 of the stator fork 15. The first and second sections 18, 19 are similar in size and shape to one another and are installed symmetrically about the central axis 13. The poles of stator 16 and 17 are separ into angular intervals? s of p / 3 radians, each having a polar arc? ps of p / 6 radians. The first and second sections 18 and 19 are separ with each other at angular intervals 20 of p / 6 radians each.

A pair of curved ferrite permanent magnets (PM) 21, 22 are embedded in the fork of the stator 15, such that the PM 21 is located within the section 18 of the fork of the stator 15 and is interposed below the stator poles 16, and the PM 22 is located within the section 19 of the fork of the stator 15 and interposed below the stator poles 17. The PM 21 ', 22 are formed as segments of a cylinder and extend the Stator fork length 15. As best shown in Figure 1, PM 21 and 22 follow the shape of the stator fork 15 and have a circular segment shape in cross section. Therefore, PMs 21 and 22 are incorporated into the stator without excessively increasing the overall size of the motor. Since the permanent magnets 21, 22 are stationary, the magnetic force between the stator fork 15 and the PMs 21 and 22 is large enough to hold the PMs 21 and 22 in position. Therefore, any conventional device can be used to secure the PMs 21 and 22. The Stator 14 is wound with three armature windings A, B, C, corresponding to the three-phase alternating current. Each winding of the armature (for example, the winding of phase A) comprises two coils + A and A connected in series, and each winding individually around one of the stator poles 16 and one of the poles of diametrically opposite stator 17. It will be appreciated by those skilled in the art that other suitable installations of the stator / rotor poles are possible. For example, multiples of 6/4, such as 12/8, etc. can be used. The essential feature is that the PMs 21, 22 face a constant reluctance flow path all the time, i.e. the total stator / rotor pole areas must remain constant. The armature winding installation of FIG. 3 produces the following exemplary alternation phase sequence during a complete revolution: + A? + B? + C? -A? -B? -C ?, and functions in the same manner as a winding of the three-phase armature in conventional variable reluctance machines. Another essential feature of the embodiment shown in Figure 3 comprises a winding of the inductor field F interposed between the sections 18 and 19 of the stator fork 15 within the angular intervals 20 and wound along the length (not shown) of the stator fork 15. The winding of the field inductor always couples with the primary flow path generated by the PM 21 and 22 polarized transversely to the central axis 13, and has two functions: 1. When the winding of the induced field F is excitates by means known to those skilled in the art, can be used to produce the amperage demagnetization or magnetization turns necessary to weaken or intensify the existing inductor field that is established by the PM ', 21, 22. The weakening capacity of the inductor field or the intensification of the field inductor for the machine of the present invention comes with a special installation for the winding of the field in F. Particularly, in this case, the total reluctance observed by the winding of the inductor field is small enough to allow a winding of the substantial inductor field, and is capable of providing the required amperage or demagnetization turns. 2. When the inductor field winding F is not energized, it can be used to detect the position of the rotor by measuring the induced voltage in the field winding F by varying the flux linkage of the field winding F by the inductor windings. induced, + A, -A, + B, -B, + C, -C, as a function of the rotor angle. Using this feedback, control could be achieved without detecting and without coding.

Figures 4 and 5 show two alternative converter topologies suitable for use in handling the above-described embodiment of the present invention, and Figure 6 illustrates one of the possible control topologies for the double-outgoing permanent magnet motor of the weakening of the inductor field of the present invention. In the embodiment of Figure 4, a bridge rectifier 23 is provided. The bridge rectifier 23 converts a three-phase AC power input to an unregulated DC. A capacitor 24 is connected in parallel through the bridge 23 to smooth the small voltage variation. Three individual current switches 25-27 are also connected in parallel with the bridge rectifier 23 and the capacitor 24. Each current switch comprises at least two switch devices (for example, switch 25 includes switch devices 28 and 29) , which can be conventional transistors or thyristors (with auxiliary switching means) connected in series with one of the corresponding stator windings AC. Each current switch 25-27 may also include two additional switch devices (for example switch 27, may include switch devices 30 and 31) for the purpose of making the converter a bipolar converter. In addition, diodes such as 32-35 are provided in parallel through each of the switch devices to provide a path for the flow of reactive energy. In the embodiment of Figure 5, the neutral of the machine is connected to a central point on the DC bus by dividing the DC link capacitor 24 of Figure 4 into two equal capacitances. Only six switch devices are needed as compared to Figure 4. The function of each switch device is the same as in Figure 4. As shown in Figure 6, the same negative and positive currents flow in the same way. to two of the three phases of the motor while the current in the third phase is zero. In this way, the current does not flow ideally in the neutral line of the motor 38. However, when practical considerations are taken into account, small pulses of current will flow in this neutral line of the motor 38 during each period where the current of the motor engine is transferred from one phase to another. Therefore, the effect of this current on the nominal value of the DC link capacitors will be minimal. As best shown in Figure 6, delta regulation is used in the current controller and a PWM rectifier is used as the inductor field voltage controller. The functions of the inductor field voltage controller are: i) To provide the appropriate amps to weaken or intensify the inductor field of PM. The behavior of the controller in this case is similar to a DC voltage source with polarity change capability. ii) Assist current communication and reduce the small torque voltage variation by controlling the saturation level of the motor. The behavior of the controller in this case is linked more to an AC voltage source with a DC component than to a simple DC source. As a result of the mutual coupling between the winding of the field inductor and the winding of the armature, the variation of the rotor angle will result in special AC current components in the winding of the field inductor. Based on this mechanism, unencrypted control can be performed on permanent magnet motors with double projection for weakening of the inductor field. Due to the existence of the PMs and the structure of double projection of the machine, there are two kinds of torque produced in a permanent magnet motor with double projection weakening the field inductor: the torque of PM (reaction torque), and the reluctance torque. As shown in Figure 7, the currents must be appropriately controlled with the variation of the phase PM inductive coupling to obtain the maximum PM torque, which is normally the desired torque in this design. On the other hand, the reluctance torque also occurs due to the characteristic and is responsible for the small voltage variation of the torque at normal operating speed. To obtain a softer torque output, the reluctance torque should be controlled to be as small as possible. From the point of view of the design of the motor, both the magnitude and the waveform of the inductances must be carefully chosen in the design. As shown in Fig. 7, the topology of the permanent magnet motor with double projection weakening the proposed inductor field, part of the reaction flow of the armature will go through the magnets leading to a special self-inductance waveform. The advantage of this waveform is the cancellation of the reluctance torque caused by the variation of the self-inductance, which guarantees less torque pulsation in this double-salient structure. The magnitude of the inductances can also be controlled by adjusting the inductor field current. When the inductor field intensification mode is used (when magnetizing the ampere turns of the inductor field), the motor iron will saturate in a high way to limit the reaction flow of the armature. Based on this mechanism, the small voltage variation of the torque of this type of motor can be controlled without affecting the phase currents, which is a very important property of this design. As shown below, this property leads to a torque capacity of 2 p.u. of this motor (an extremely desirable feature for traction applications). The machine exposed in reference to the figures 3-7, it can operate either as an engine or as a three-phase generator. It can run at very high speeds by controlling the current to produce the reluctance torque or to maintain the normal current waveform of a lower speed operation in conjunction with the control of the weakening of the inductor field. This invention will be suitable for a variety of high performance electrical machine drive systems and electrical generation applications over a very wide speed range, without considering the power ratings, or the number of poles of the machines, as long as the ratio of the rotor pole / stator 6/4 is maintained. The equations of the phase voltage of a three-phase version of this machine can be expressed as follows: where . { ema, e ^, emc} is the emf induced due to the magnet and the inductive couplings and their time derivatives are: Laa Mba Mea Mab Lbb Mcb (2) Mac Mbc Mee Y In such a way that ua? a ema ia lia ib icl ub ia ib ic J ibla ib icj emb + ia ib = to ib + li iaa ib icl d uc ic eme Equation (4) can be interpreted as where a) input power ua Pin = [ia ib ic] ub (6) uc b) loss in copper c) PM torque d) Reluctance torque e) energy stored in the armature windings Also from (1), the dynamic equations of the permanent magnet motor of double salient weakening inductor field can be expressed by: where a) [V] is the control vector ua [V] ub (12) uc b) [E] is the PM voltage vector ema [E] emb (13) eme c) [R] is the resistance matrix The parameters of the machine in (11) can be obtained more easily based on finite element analysis (FEA) of the motor and digital computer simulations can be carried out by using the dynamic equations derived herein. In addition, vector trajectory control strategies [V] can also be studied based on this model. The PM voltage vector can be written as: where: fma- uncharged PM flux linked by phase A fmb- unloaded PM flux linked by phase B fm- unloaded PM flux linked by phase C Lma- mutual inductance between the inductor field winding and phase A Lmb- mutual inductance between the winding of the inductor field and phase B Lmc- mutual inductance between the winding of the inductor field and phase C if- current of the winding of the inductor field Usually, the inductor field current varies very slowly and the waveforms Lma, L- ^, Lmc are the same as those of fma, fmb, fmc. Consequently, equations (4-11) remain valid despite the fact that [E] is the function of the winding current of the inductor field. In this case, if it can be considered simply as another control variable. An analysis of the finite element for a permanent magnet motor with double projection weakening the 10 kW prototype inductor field has been completed to demonstrate the principle of operation. The main function of this analysis was to obtain the necessary parameters to design and control the machine. Figure 9 shows the distribution of the flow when excited only by the excitation of the PM. It can be seen that a very high concentration of magnet flux of the ratio in the region of 4 to 1 at the pole of the active stator is achieved. The flow densities in the air gap that are in the order of 1.2 Tesla can be easily obtained even when the operating point inside the ferrite magnet is only 0.3 tesla. This fact, in turn, illustrates the capacity of concentration of the flow, in a structure of permanent magnet of double salient, very far from the machines of conventional permanent magnet buried. Figure 10 shows the distribution of the flow when there is only one current of the armature. The maximum inductance position is shown, which occurs when the stator poles and the rotor poles overlap in half. The special design of the inductance profile as a function of the rotor position leads to the reduction of the small voltage variation of the torque as previously discussed.

Figure 11 shows the inductive coupling of the permanent phase magnet versus the angle of the rotor under various levels of the excitation of the inductor field current. Note that very high forcing of the inductor field is possible when the inductor field current and the magnet act to produce the flow in the same direction. Conversely, when the two inductor fields are opposed, the net flow in the interval, if necessary, can be driven to zero. The FEA indicates that the permanent magnet inductor field can be completely canceled by demagnetizing the MMF provided by the field winding inductor by using only 60-90% of the field unit's current inductor (the inductor field current unit). here it is defined as the point where the density of the copper current volume reaches 3,000 A / in2) Based on the study of the FEA, the power versus the speed characteristics of the motor can be determined as shown in figure 12. It can be observed that the initial torque capacity can be as high as 2 pu when used in inductor field intensification mode. In this case, a highly saturated condition is carried out under this mode in order to greatly reduce the magnitude of the inductances and thus the devasting torque.

Based on the above analyzes, the power density of the permanent double-stranded magnet motor of weakening of the inductor field can be obtained. Since the reluctance torque does not contribute to the average torque for the production of machine torque under normal operating conditions, only the permanent magnet torque is used to calculate the output power. The phase counter electromotive force due to the variation of inductive permanent magnet coupling can be expressed as: "Ps Npx ^ m E = -x? R (16) m? D where: Ps- stator pole number Np- lap number per pole fpm- flow of peak PM linked by a pole coil (Wv) ? r- rotor speed (rad / sec) ? d- semiperiod of the variation of the flow of PM (rad) m- number of phase Y where ns- mechanical speed (rpm).

From the surface current density: where D- inner diameter of the stator (M) Ims- rms value of phase current (A) From (19), Np can be expressed as: pD.xA ND = (20) p 2T xP The permanent magnet flow per pole is: where Kd- is the factor of the inductive coupling of the PM Le- superimposed length (M) Bg- density of the flow in the air gap (Tesla). From the (16) - (21): MxExIrmsx / 7 = kd - tpíBgx? XnaxDi 2Lt (22) where? - efficiency. Note that the output power of this motor is: = MxExK. xlrmsxt7 where Ipr? m is the average phase current and the current factor Kx is expressed as: K1 = ^ (23) rms Therefore, the output equation of the permanent double-byte magnet motor of the weakening of the inductor field can be obtained: PSanda = k.xK, (24) By comparing this result with the well-known output equation of the induction machine (IM), especially, the power density ratio of the two machines can thus be obtained, PsalldaFWDSPM_Calida ™ Note that the constant Kd for the permanent magnet motor with double projection weakening the inductor field is generally 0.8-0.9, which is approximately the same range than the power factor in an IM. The density of the air gap flow is the same as the tooth flow in a permanent magnet motor with double projection weakening the inductor field, so that it can be like the tooth flow in a double permanent magnet motor outgoing weakening of the inductor field, so that it can be chosen twice as that of the IM. Based on this analysis, the proportion of the power density can also be expressed as: 2K,? = Lt < 27 > Due to the waveform of the current in the permanent magnet motor with double projection weakening the inductor field (shown in figure 7), if 60 electrical degrees are assumed in a segment to correspond the current to the switching time of the current, K is calculated to be: ? - = - ^ (28) In such a way that 1. 09 (29) V21 From the derivation, 9% of the increase in power density is achieved without the help of the field winding inductor. Also, remember that the current densities of the stator surface for the two motors were assumed equal. However, the current density of the double-sided permanent magnet motor of the weakening of the field inductor may be greater than the IM since a permanent magnet motor with double projection weakening the field inductor does not require rotor currents. In fact, the highest power density can be achieved in the permanent double-salient magnet motor by weakening the inductor field by using the inductor field intensification mode. Assuming that an inductor field current of one p.u is used, from the FEA, the pole inductive coupling could be increased by 50%, which suggests that the torque of the resulting permanent magnet can be increased to 50%. The performance of this machine can now be verified as follows: The additional copper loss due to the excitation of the inductor field current is: Pcuf = px J x Vcuf (30) where: p- copper resistance J.- density of the volume flow VCUf- copper volume of the winding of the inductor field. The volume VCUf in the proposed design is approximately 1.5 times the volume of copper in a winding of the single-phase armature Vcu. The copper loss of the induced winding can thus be expressed by: Pcu = 3 x p x J x Vcu (31) Therefore, 1.5 1 P = P = -P (32) From the previous analysis, the output power increases to 50% and the copper loss increases to 50%. If the loss in the iron is ignored, the efficiency of the motor will remain the same. However, for an inductor field intensification mode of one p.u, the ratio of the power density without sacrificing the good overall performance of the machine will be: ? = 1.5 x 1.09 - 1.635 (33) The digital simulations can be carried out for the design of a permanent magnet motor of double salient weakening of the inductor field prototype of 10 kW three-phase. The results of the machine data and the performance calculation are shown below: Machine Data Stator Outside Diameter 10.5 Inch Stator Inner Diameter 6.0 Inch Overlap Length 7.0 Inch Stator Pole Number 6 Pole Rotor Pole Number 4 Pole Stator Pole Arc / Rotor 30 ° / 30 ° Depth stator slot 0.65 inches mechanical speed 1800 rpm Machine performance DC bus voltage 250 volts maximum inductance 1.79 mH minimum inductance 0.35 mH phase peak current 100 A RMS phase current 70.6 A output power 10.6 k efficiency 96.5% The simulation is based on the derived dynamic equations and the parameters obtained from the FEA. The current and voltage waveforms and machine torque production are shown in Figure 8 and demonstrate the basic dynamic behavior of the machine. The particular interest is the torque production of this machine, which is composed of both reluctance and PM components. Note, in particular, that only a small contribution to the total torque is made by reaction torque. Although this simulation was based on a study of the finite element, only several rotor positions were chosen to calculate the inductances as a current function. Between any of the two adjacent positions, a linear relationship is assumed to interpolate the values of the inductances. A more accurate model of the motor is present under development to stimulate in detail the complete non-linear behavior of the system. As a result of the above-referenced exposures and as shown in Figure 3-12, it will be appreciated by those skilled in the art, that the new type of double-salient PM motor capable of a 100% inductor field weakening and a 2 pu power capacity is proposed in this document, which offers improved performance, high power density, low cost, field control capability inductor, and a robust structure for variable speed drives that require a wide range of field weakening inductor. The double-led configuration of this machine provides a higher flow concentration than sinusoidal distributed flow types and a softer torque production than other double-ended PM structures due to the fact that the reluctance torque caused by the variation of self-inductance versus the angle of the rotor can be greatly cand. On the other hand, enough space is installed in this design for the use of ferrite PMs, which are less expensive than rare earth PMs. Furthermore, due to this special installation, the reluctance of the PM observed by the winding of the inductor field is completely low such that the required ampere turns are comparatively small, sufficient to guarantee the space for a winding of the wound inductor field. In fact, PM machines that have one hundred percent of the weakening capacity of the inductor field can be carried out by this method. Another advantage of this motor is that when the winding of the field inductor is working in the field of intensification of the field inductor, the initial torque capacity can be as high as 2 p.u. and the power output of this machine can be increased to 30% at normal speed. Referring to Figures 13-27, another embodiment of the present invention, operating as a single-phase double-ended PM generator 39, includes a rotor 40 comprising six protruding rotor poles 41 and a stator 42 comprising four outgoing stator poles. 43 and 44. The rotor poles 41 are placed at angular intervals? R of p / 3. Each rotor pole 41 has a curved pole? Pr. The stator 42 includes a stator fork 45, which constitutes a cylinder having a round shape in its cross section. Similar to Figure 3, the fork of the stator 45 has two sections 46, 47 separated by angular intervals 48 greater than those of Figure 3. Two poles of the stator 43 are placed within the section 46, and two poles of the stator are placed 44 within section 44 of the stator 45 fork. A pair of curved permanent ferrite magnets 49, 50 are embedded in the stator fork 45, as shown in Fig. 13, and are biased transversely to the central axis 51 to serve as a primary flow source for magnetizing the generator 39. An armature winding, first and second , 52, 53 is wound on the respective stator poles 43, 44; each of them consists of a first and second coil 54, 54 ', 55, 55' connected in series between them and individually wound around the diametrically opposite stator poles 43 and 44. The coil 54 'of the winding of the armature 52 is connected to the coil 55 of the armature winding 53. A winding of the field inductor 56 is interposed between the sections 46 and 47 and is wound along the length of the stator 45 hairpin. Once the weakening of the inductor field 56, produces the amperage turns of magnetization or demagnetization to weaken or intensify the primary flux produced by the permanent magnets 49, 50. Those skilled in the art are known to the means 57 for energizing the winding of the inductor field and shown schematically in Figure 13. To describe the operating principles and control topologies, two modes of operation of the permanent double-ended magnet generator are considered. of weakening of the inductor field, one is the "bidirectional" model (BDM) and the other is the "unidirectional" model (UDM). Figures 14, 15 and Figures 16, 17, 18 show the winding connections and the possible control topologies, respectively. As shown in Figure 16, a converter 58 serves to convert an AC obtained from the windings of the armature 52 and 53 into a single-phase DC, which is provided for the output and filtration. As shown in Figure 14, the BDM is based on two windings of the pole under a piece of the PM connected as a phase, which causes a double frequency variation of the self-inductance compared to that of the PM flow and should be considered the non-mutual inductance. In this case, the phase current is bidirectional which results in the energy conversion in two quadrants of the B-H plane (shown in Figure 19). The reluctance torque will pulse at normal speeds to cause harmonic current in such a way that the inductance of this machine should be designed as small as possible.

On the other hand, the UDM is based on a two-phase connection of the armature winding (shown in Figure 15). In this case the machine is operated similar to an SRM and energy conversions occur only in the first quadrant on the plane of? -I (shown in figures 19 and 20) such that only one half of the period for each phase it is used to produce the reaction of the armature so that it always magnetizes the inductor field of the PM and in this way leads the machine towards an approximately saturated condition. The reaction of the armature becomes useful in the UDM in the form of reluctance torque, for which higher inductance could be designated and the control topology is simpler (see figure 18) similar to that for the SRMs. The frequency of the variation of inductance versus the angle of the rotor for the UDM is the same as that of the inductive coupling of the PM, which contributes to a softer reluctance torque production. The production of torque for both modes of operation are shown in Figures 21 and 22. The equations of the phase voltage of this new machine can be expressed as follows: (34) where In such a way that [iaiblü Equation (37) can be interpreted as follows: P + T x? + T xas "+ - -W, (38) dt where a) the input power is b) with loss in copper c) the PM portion of the torque is [ia (41) d) the reluctance torque is where Laa Mba [] = Mab Lbb e) energy stored in the armature windings Also from (34), the dynamic equations of the permanent magnet generator of double outgoing weakening of the inductor field can be expressed by: (44) where 1) [V] is the control vector ua [v] (45) ub 2) [E] is the voltage vector of PM 3) [R] is the resistance matrix ra 0 [R] (46) 0 rg The parameters of the machine in (44 ) can be obtained from the finite element analysis (FEA) and digital computer simulations can be carried out using the dynamic equations, which have been presented. In addition, strategies for controlling the trajectory of vector [V] can be studied based on this model. In particular, the control characteristics of the PM inductor field of the machine must be examined and they will be the subject of a future document. The PM voltage vector can be written as: (47) where: fma- uncharged PM flux linked by phase A fmb- unloaded PM flux linked by phase B Lma- magnetization inductance of the inductor field winding for phase A Lmb- magnetization inductance winding of the inductor field for phase B if- current of the inductor field winding An analysis of the finite element for a double-salient permanent magnet generator of weakening of the prototype field of the inductor has been carried out kW of the present invention to demonstrate the principle of operation. Figure 23 shows the distribution of the flow when only the excitation of the PM exists. The very high concentration of the magnet flux at one of the stator poles is apparent. The flow densities in the air range above the order of 1.5 Tesla can be easily achieved even when the remaining flux density of the ferrite magnets was only 0.4 Tesla. This, in turn, demonstrates a focusing ability of the flow of a factor of four, far removed from conventional buried PM machines. Figure 24 shows the distribution of the flow when only the armature current exists. The maximum inductance position is shown, which occurs when the stator and rotor poles overlap in half. The reluctance torque produced by the armature current is zero at this point. The demagnetization MMF was provided by winding the inductor field only when using the 60-90% of the inductor field current per unit (unit of the inductor field current in the present is defined as the point where the density of the copper volume current reaches 3000 A / in2). Digital simulations have been carried out for the design of a permanent magnet generator of double protrusion of 5 kW prototype inductor field weakening. Machine data and performance calculation results are shown below: Machine data Stator outside diameter 28.5 cm Stator inside diameter 20.0 cm Overlap length 18.3 cm Number of stator poles 4 poles Number of rotor poles 6 poles stator pole arc / rotor 0 ° / 30 ° depth of stator groove 1.8 cm Machine performance (BDM) DB bus voltage 150 volts maximum inductance 0.81 mH minimum inductance 0.20 mH phase peak current 75 A RMS phase current 64.5 A output power 5.31 kW efficiency 96.0% Machine performance (UDM) DC bus voltage 150 volts maximum inductance 0.76 mH minimum inductance 0.57 mH phase peak current 63 A RMS phase current 55.4 A output power 5.21 kW The simulations are based on the derived dynamic equations and the parameters obtained from the FEA. The current and voltage waveforms are shown in Figures 26"and 27 for both modes of operation, respectively, although this simulation was based on a study of the finite element, several positions of the rotor were chosen to calculate the inductances and a simple variation of linear inductance between two adjacent positions was assumed Also, it can be seen that, as a result, the inductance is assumed to vary linearly and that the EMF is "square." As discussed above with reference to Fig. 13- 27, the new electric machine with capacity for the weakening of the inductor field with excitation of the PM, combined with the high power density, low cost, and a mechanically robust structure can be realized based on the proposed concept. From the analyzes, it is shown that this generator can be operated in a very wide speed range without losing the high performance, which indicates that this new type of PM generator has high potential for variable speed electric generation applications (especially high speed) . The low cost realization of the weakening capacity of the inductor field of this PM generator could make an extended use of this type of machine, possible in the near future. The machine proposed in this invention and treated in conjunction with Figures 13-27, will be suitable for a variety of high efficiency electrical generation applications, without taking into account the power or speed range, or the number of poles of the machine , as long as a stator / rotor pole ratio of 4/6 is maintained.

The combination of the principle of variable reluctance machines, with the use of specific facilities, shape, and location of the PM, using permanent ferrite magnets instead of rare earth permanent magnets results in a machine that has a lower cost , lighter weight, higher power density machine, capacity of intensification or weakening of the field inductor, and an easier demagnetization that protects the realization for the manufacturers of electrical machines. Having now fully established the preferred embodiments and certain modifications of the concept underlying the present invention, various other modalities as well as certain variations and modifications of the embodiments herein shown and described, will occur in an obvious manner for those skilled in the art until becoming familiar with the underlying concept. It is understood, therefore, that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically set forth herein.

Claims (17)

1. NOVELTY OF THE INVENTION Having described the present invention is considered as a novelty and therefore the claim described in the following claims is claimed as: 1. A permanent magnet machine comprising: a rotor mounted for rotation about a central axis and comprising: a plurality of protruding rotor poles that are spaced apart at equal angular intervals about said central axis and extending radially outwardly thereof; a stator comprising: a stator fork, the stator fork being of a round shape in its cross section and having similar, first and second sections, installed symmetrically about the central axis, a plurality, first and second, of poles of the stator projections that are spaced at equal angular intervals about the central axis and extending radially inwardly of the stator fork, said first section having said first plurality of stator poles, and said second section having said second plurality of stator poles , and curved first and second permanent magnets embedded in the stator fork, the first permanent magnet being interposed between the first stator fork section and said first plurality of the stator poles and the second permanent magnet being interposed between the second section of the stator fork and said second plurality of the poles of l stator; a plurality of armature windings, each individually wound around a stator pole of said first plurality of stator poles and one of the diametrically opposite stator poles of said second plurality of stator poles, and a winding of the field inductor permanently coupled with a primary flow path and interposed between said first and second sections and wound along the length of the stator fork. The machine according to claim 1, characterized in that the permanent magnets, first and second, extend the length of the stator fork and their cross sections are of a round shape. 3. The machine according to claim 1, characterized in that the permanent magnets, first and second, are permanent ferrite magnets. The machine according to claim 1, characterized in that said plurality of armature windings is a winding of the three-phase armature. The machine according to claim 1, characterized in that said first and second permanent magnets are transversally biased in a direction of radial magnetization to said central axis to serve as a source of the primary flow to magnetize the machine. The machine according to claim 5, characterized in that once the winding of the inductor field is excited, it produces the amperage turns of magnetization or demagnetization to weaken or to intensify the primary flow produced by the permanent magnets, first and second. The machine according to claim 5, characterized in that the winding of the inductor field detects the position of the rotor. The machine according to claim 1, characterized in that said plurality of rotor poles includes four rotor poles, said first plurality of stator poles includes three stator poles, and said second plurality of stator poles includes three stator poles, wherein said plurality of armature windings comprises three armature windings, each of said three armature windings includes two coils connected together, each of said coils being wound around one of the diametrically opposite stator poles, and each of the coils connected to each other. said armature windings to a separate phase of a three-phase alternating current source. The machine according to claim 8, characterized in that it also includes converter means connected to said armature windings and converting a three-phase alternating current power into an unregulated direct current. 10. The machine according to claim 1, characterized in that it also includes means for exciting the winding of the inductor field. The machine according to claim 1, characterized in that a proportion of said plurality of poles of the rotor to said plurality of stator poles is 4: 6. 12. The machine according to claim 11, characterized in that it operates as a motor. The machine according to claim 11, characterized in that it operates as a generator. The machine according to claim 1, characterized in that said plurality of rotor poles includes six rotor poles, wherein said plurality of rotor poles include four stator poles, and wherein said plurality of armature windings includes armature windings. , first and second, including each of said windings of the first and second armature, coils, first and second, connected in series between them, each of said coils, first and second, being wound around a diametrically opposite stator pole, the second coil of the first winding of the armature connecting to the first coil of the second winding, and said machine further includes converter means connected to the first coil of the first armature winding and to the second coil of the second armature winding, said converting means converting a current Alternating single phase obtained from the armature windings, first and second in a current di straight. 15. The machine according to claim 1, characterized in that a proportion of said plurality of rotor poles to said plurality of stator poles is 4: 6. 16. A permanent magnet machine characterized in that it comprises: a rotor mounted for rotation about a central axis and comprising: four protruding rotor poles that are spaced at equal angular intervals around said central axis and extending radially towards outside of it; a stator comprising: a stator fork, the stator fork being of a round shape in its cross section and having similar, first and second sections, installed symmetrically about the central axis, six protruding stator poles which are spaced at intervals equal angles around the central axis and extending radially inwardly of said stator fork, said first section having three first stator poles, and said second section having three other stator poles, and curved ferrite permanent magnets, first and second embedded in the stator fork and transversally polarized in a direction of radial magnetization to said central axis to serve as a source of the primary flow to magnetize the machine, the first permanent magnet interposing between the first section of the stator fork and said three first poles, and interposing the second permanent magnet between the second section of the stator fork and said other three stator poles, the permanent magnets extending, first and second, the length of the stator fork and its cross sections being of a round shape; three-phase armature windings, each winding individually around a stator pole of said first three poles of the stator and of a diametrically opposite stator pole of said other three stator poles; interposing a winding of the inductor field between said first and second sections, and winding along the length of the stator fork, wherein, when said armature winding is excited, it produces the amperes of demagnetization or magnetization to weaken or to intensify the primary flow produced by the permanent magnets, first and second; and wherein, when said induced winding is not excited, it detects the position of the rotor, each of said three windings of the armature connecting to a separate phase of a three-phase source of alternating current; converter means connected to said armature windings and converting a three-phase alternating current power into an unregulated direct current; and means for exciting the winding of the inductor field. 17. A single-phase permanent magnet generator characterized in that it comprises: a rotor mounted for rotation about a central axis and comprising: six protruding rotor poles that separate at equal angular intervals around said central axis and extending radially towards outside of it; a stator comprising: a stator fork, the stator fork being of a round shape in its cross section and having similar, first and second sections, installed symmetrically about the central axis, four protruding stator poles which are separated at intervals equal angles about the central axis and extending radially inwardly of said stator fork, said first section having two first stator poles, and said second section having two other stator poles, and curved permanent ferrite magnets, first and second embedded in the stator yoke and transversally polarized in a direction of radial magnetization to said central axis to serve as a source of the primary flow to magnetize the machine, the first permanent magnet interposing between the first section of the stator fork and said two first poles, and interposing the second permanent magnet between the second section of the stator fork and said two other stator poles, the permanent magnets extending, first and second, the length of the stator fork and its cross sections being of a round shape; armature windings, first and second, including each of said armature windings, first and second, coils, first and second, connected in series between them, each of said coils, first and second coiled individually around a diametrically opposite stator pole, connecting the second coil of the first armature winding to the first coil of the second armature winding; a winding of the armature interposed between said first and second sections, and winding along the length of the stator fork, wherein, when said winding of the inductor field is excited, it produces the amperes of demagnetization or magnetization to weaken or to intensify the primary flow produced by the permanent magnets, first and second; means for exciting the winding of the inductor field; and a converter means connected to the first coil of the first armature winding and to the second coil of the second armature winding, said converter means converting an alternating current obtained from the first and second armature windings into a single-phase direct current.