WO2012073387A1 - Electric machine - Google Patents

Abstract

An object of the invention is to provide a transverse flux machine (TFM) with superior strength and magnetic characteristic. At least one of a stator core or a rotor core is made of axially-laminated soft magnetic plates, which are laminated to an axial direction. The soft magnetic plate has two groups of stator teeth, two groups of diagonal portions and a yoke portion. The two groups of stator teeth arranged to the circumferential direction each are disposed across a stator winding extending to a circumferential direction. The one group of the stator teeth is joined to the yoke portion via the one group of the diagonal portions. The other one group of the stator teeth is joined to the yoke portion via the other one group of the diagonal portions. The yoke portion extends to the circumferential direction. The one group of the teeth and the other one group of the teeth are arranged alternately in the circumferential direction.

Description

ELECTRIC MACHINE Cross-Reference to related application

This application claims benefit, for example less than 35 U.S.C.119, from PCT/JP2010/007034 filed on Dec/02/2010, the title of TRANSVERSE FLUX MACHINE, of which the entire content is incorporated herein reference.

Background of Invention

1. Field of the Invention
The present invention relates to an electric machine, in particular to a transverse flux machine (TFM). The machine is provided for converting between torque and electric power.

2. Description of the Related Art
A mega torque motor producing a large torque in a low speed range is preferable for a direct-drive in-wheel motor, the DD in-wheel motor. The DD motor reduces a power loss and a weight of a reduction gear mechanism, which is more than 10%. It means that a battery vehicle can run for longer time without increasing the battery. The DD machine is preferable for a traction motor and a wind turbine, if it is capable to decrease a weight of the DD motor.

It is known that a TFM can increase the motor torque without increasing the weight, because it is easy to increase pole numbers of a stator and a rotor. Generally, the pole number is proportional to the torque. The TFM includes the radial gap type, the axial gap type and the linear type. The single-sided TFM has one rotor surface facing one stator. The dual-sided TFM has both rotor surfaces facing two stators.

The TFM, which essentially consists of a single-phase motor, has a stator winding extending toward the moving direction of a rotor or a mover. The TFM with a permanent magnet rotor is called the TFPM, which is the transverse flux permanent magnet machine. The TFM with rotor salient without the permanent magnet is called the TFRM, which is the transverse flux reluctance machine. It is well known that the TFRM includes the transverse flux switched reluctance machine (TFSRM) and the transverse flux synchronous reluctance machine (TFSynRM).

A rotor can have a field-coil wound on the rotor. It is called the wound-rotor transverse flux machine, the WRTFM. They are called the synchronous TFM. Generally, the stator winding of a radial gap type motor consists of a ring-shaped winding. A three-phase TFM is constructed by arranging three single-phase TFMs to the axial direction.

Generally, a stator core and a rotor core of the TFM are made from the SMC (soft magnetic composites) in order to flow the magnet flux in the axial direction across the ring-shaped stator winding. However, robustness and magnetic characteristic of the SMC core are not enough for the in-wheel motor in comparison with the conventional laminated steel cores including laminated amorphous iron cores.

Figure 1 schematically shows an axial cross-section of the SMC-TFM. Figure 2 shows a schematic side view of the SMC-TFM of the independent-yoke type. Each of the U-shaped stator cores 2 of a stator 1 has two stator teeth 21 and a yoke portion 22. A ring-shaped stator winding 3 is accommodated in a ring-shaped slot 23 formed between two groups of stator teeth 21. The stator 1 surrounds a rotor 4.

Figure 3 is a perspective view showing a linear TFM, which has a stator 1 with a common yoke 24. Figure 4 shows an elevation view of the linear TFM shown in Figure 3. Stator teeth 21 project from the common yoke 23 toward a mover 4. The mover 4 has a plurality of permanent magnet bars 5 fixed to a soft ferromagnetic core 6 of the mover 4. United Patent No. 7,339,290 proposes one example of the linear SMC-TFM.

United States Patent No. 4,973,868 proposes the U-shaped stator core made of a wound steel core, so-called the cut core. However, large number of the U-shaped cut core with two stator teeth needs complicated production process. Consequently, the prior TFM is not used broadly yet, because of the poor hardness and the poor magnetic characteristic of the SMC and the complicated production process of the cut core.

Generally, three-phase TFM consisting of three TFMs are employed in order to decide the moving direction. Each phase of the three TFMs is driven by each full-bridge single-phase inverter. For example, United States Patent No. 4,849,871 describes the three-phase inverter consisting of three full-bridge single-phase inverters. However, three full-bridge inverters driving the three-phase TFM is expensive, because the each phase requires one full bridge inverter. Accordingly, the motor-driving apparatus of the three-phase TFM becomes expensive.

United Patent No. 7,339,290 United Patent No. 4,973,868

An object of the present invention is to provide a transverse flux machine (TFM) having at least one of a stator core or a rotor core with superior mechanical strength and excellent magnetic characteristic. Another object of the present invention is to provide the TFM with simple structure and a simple production process.

The transverse flux machine of the invention is explained hereinafter referring to an inner-rotor type. An aspect of the invention, each of soft magnetic plates (7) laminated to the axial direction has left teeth (71L), right teeth (71R), a yoke portion (74) and left diagonal portions (75L) and right diagonal portions (75R). The left diagonal portions (75L) extending diagonally joins the yoke portion (74) and the left teeth (71L). The right diagonal portions (75R) extending diagonally joins the yoke portion (74) and the right teeth (71R). The left teeth (71L) and the right teeth (71R) are arranged alternately in the moving direction (PH).

Accordingly, the stator of the TFM can be formed by means of press process, for example by means of pressing of a flat soft iron sheet or an amorphous iron sheet. As the result, the TFM can have excellent strength and magnetic characteristic than the TFM with the soft magnetic composite, the SMC.

According to a preferred embodiment, the rotor core (4U) has same structure as the above stator. Accordingly, the rotor of the TFM can be formed by means of press process, for example by means of pressing of a flat soft iron sheet or an amorphous iron sheet. As the result, the TFM can have excellent strength and magnetic characteristic than the TFM with the soft magnetic composite, the SMC.

According to another preferred embodiment, the left rotor teeth (41L) face the left stator teeth (21L), when the right rotor teeth (41R) face the right stator teeth (21R). Accordingly, the TFM can consist of laminated soft magnetic plates with simple structure.

According to another preferred embodiment, the rotor core (4U) has a permanent magnet. North pole areas of the permanent magnet face the left stator teeth (21L), when south pole areas of the permanent magnet face the right stator teeth (21R). Accordingly, the TFPM can consist of the stator cores and rotor cores, which consists of laminated soft magnetic plates made with simple process.

According to another preferred embodiment, the laminated soft magnetic plates (7) have spacers (71g) between each two teeth (71L, 71R) being adjacent each other. The laminated soft magnetic plates (7) have spacers (74g) between each two yoke portions (74) being adjacent each other. Accordingly, vibration of the laminated core can be reduced.

According to another preferred embodiment, the stator core (2U) and the rotor core (4) have a ring-shaped soft magnetic plates (7) laminated to the direction (AX). Accordingly, the simple and strong TFM is realized.

According to another preferred embodiment, the stator (1) has star-connected three phase windings (3U, 3V and 3W) consisting of a stator winding of a single-phase transverse flux motor each. The three stator windings (3U, 3V and 3W) are driven by a three-phase inverter (500) having three legs consisting of three half bridges. Accordingly, the three-phase TFM is driven by the simple driving apparatus.

According to another preferred embodiment, the stator (100) has even number of AC phase windings (301-306), which is an AC stator winding of a single-phase transverse flux motor each. Each pair (301 and 304, 302 and 305, and 303 and 306) of the phase windings (301-306) is driven by each of full bridge inverters (801-803). The stator (100) has even number of DC windings (501-506), which is a DC stator winding of a single-phase transverse flux motor each. Each of DC windings (501-506) is connected in series to each other. Accordingly, the power loss of a power converter of the TFSRM can be saved. This embodiment can be employed by a conventional SRM.

According to another preferred embodiment, the stator (100) has even number of AC phase windings (301-306), which is an AC stator winding of a single-phase transverse flux motor each. Each pair (301 and 304, 302 and 305, and 303 and 306) of the phase windings (301-306) is driven by each of half bridge inverters (801A-803A). The stator (100) has even number of DC windings (501-506), which is a DC stator winding of a single-phase transverse flux motor each. Each of DC windings (501-506) is connected in series to each other. Accordingly, the induced voltage of the DC winding is reduced. This embodiment can be employed by a conventional SRM.

According to another preferred embodiment, each phase AC current with sinusoidal waveform is supplied to each AC phase windings (301-306) with the star connection. Accordingly, the TFSRM can be driven with the simple power converter. This embodiment can be employed by a conventional SRM.

According to another preferred embodiment, the transverse flux machine has two phase windings (901, 902) energized by two asynchronous power converters (H1 and H2) having an upper switch (903, 905), a lower switch (904, 906). A connecting point between a first phase winding (901) and the lower switch (904) is connected to a connecting point between a second phase winding (902) and the upper switch (905) without a diode. Accordingly, the power loss of the power converter is reduced.
According to another preferred embodiment, the rotor teeth (41L, 41R) have short-circuited windings (300) wound around rear portions (212L, 212R) of the rotor teeth (41L, 41R). Accordingly, the transverse flux machine can work as a single-phase induction motor.

Figure 1 is an axial cross section of schematically showing a prior TFM with a SMC stator core. Figure 2 is a side view of a prior TFM with a plurality of SMC stator cores. Figure 3 is a perspective view of a linear TFM having a SMC stator core with a common stator yoke. Figure 4 is an elevation view of the linear TFM shown in Figure 3. Figure 5 is an axial cross section of schematically showing a three-phase TFSRM of the first embodiment. Figure 6 is a schematic view showing of a laminating process of the stator core shown in Figure 5. Figure 7 is an enlarged axial cross-section of schematically showing the enlarged stator core shown in Figure 5. Figure 8 is a partial side view of the ring-shaped stator shown in Figure 5. Figure 9 is a partial circumferential development of the ring-shaped U-phase stator core shown in Figure 5. Figure 10 is an axial cross-section of a rotor of a TFM turbo-charger of the second embodiment. Figure 11 is an axial cross-section of a three-phase TFRM of the third embodiment. Figure 12 is a schematic side view of the three-phase TFRM shown in Figure 11. Figure 13 is a schematic side view showing a ring-shaped iron plate before and after bending in order to form the diagonal portions. Figure 14 is a schematic cross-section showing the bending process of one soft steel plate. Figure 15 is a schematic cross-section showing the bending process of the soft steel plate. Figure 16 is a schematic cross-section showing the bending process of the soft steel plate. Figure 17 is a schematic cross-section showing the bending process of the soft steel plate. Figure 18 is a transverse cross-section showing a linear TFM of the fourth embodiment. Figure 19 is a schematic side view showing the linear TFM shown in Figure 18. Figure 20 is an enlarged cross-section of three steel plates laminated to the axial direction. Figure 21 is an enlarged cross-section of the three steel plates shown in Figure 20. Figure 22 is an enlarged axial cross-section near the electro-magnetic gap between the stator teeth and the rotor teeth. Figure 23 is an axial cross-section of the three-phase TFPM of the fifth embodiment. Figure 24 is a partial development of the stator teeth shown in Figure 23. Figure 25 is a partial development showing the outer circumferential surface of a rotor shown in Figure 23. Figure 26 is an arranged partial development showing the outer circumferential surface of the rotor shown in Figure 23. Figure 27 is an axial cross-section of the three-phase TFPM of the sixth embodiment. Figure 28 is a partial development of the stator teeth shown in Figure 27. Figure 29 is a partial development showing the outer circumferential surface of the U-phase rotor shown in Figure 27. Figure 30 is an axial cross-section of U-phase rotor along a line X-X shown in Figure 29. Figure 31 is an axial cross-section of U-phase rotor along a line Y-Y shown in Figure 29. Figure 32 is a circuit diagram showing a motor-driving circuit of the seventh embodiment. Figure 33 is an axial cross section of the six-phase TFSRM of the eighth embodiment. Figure 34 is a partial axial cross section showing the rotor teeth of the six-phase TFSRM shown in Figure 33. Figure 35 is a circuit diagram showing a six-phase power converter for driving the six-phase TFSRM shown in Figure 33. Figure 36 is a timing chart showing waveforms of the three-phase AC phase currents supplied to the six-phase TFSRM shown in Figure 33. Figure 37 is an enlarged timing chart showing waveforms of U-phase and U'-phase shown in Figure 36. Figure 38 is a diagram showing the U-phase AC current and U-phase DC current, which are shown in Figure 37. Figure 39 is a timing chart showing an arrangement of the ninth embodiment, which supplies the AC phase currents with sinusoidal waveforms to the AC windings having the inductances with sinusoidal waveforms. Figure 40 is a circuit diagram showing a three-phase power converter applying the three-phase sinusoidal voltage to star-connected AC phase windings. Figure 41 is a partial side view of the rotor teeth and stator teeth, which has curved corners. Figure 42 is a schematic view of showing a soft magnetic plate with center teeth and left teeth. Figure 43 is a schematic view of showing a soft magnetic plate with center teeth, left teeth and right teeth. Figure 44 is a circuit diagram showing a prior well-known two-phase asynchronous power converter for driving a conventional SRM. Figure 45 is a circuit diagram showing a two-phase asynchronous power converter of the tenth embodiment. Figure 46 is a timing chart of two phase currents supplying to two phase windings of the tenth embodiment. Figure 47 is a circuit diagram showing currents of the tenth embodiment. Figure 48 is a circuit diagram showing currents of the tenth embodiment. Figure 49 is a circuit diagram showing a motor-driving apparatus of the eleventh embodiment. Figure 50 is an axial cross-section showing a three-phase TFSRM of the twelfth embodiment. Figure 51 is an axial cross-section showing a single-phase induction TFM of the thirteenth embodiment. Figure 52 is a circumferential development of the single-phase induction TFM shown in Figure 51. Figure 53 is an axial cross-section showing a two-phase reluctance TFM of the fourteenth embodiment. Figure 54 is a circumferential development of the two-phase reluctance TFM shown in Figure 53.

Detailed Description of the Preferred Embodiment

The electric machine of the present invention is explained referring to a TFM with the inner-rotor type and the linear type. Every skilled engineer can imagine the outer-rotor type and the axial type referring to embodiments explained as follows.

(The first embodiment)
The TFM of the first embodiment is explained referring to Figures 5-9. Figure 5 schematically shows an axial cross-section showing a three-phase TFSRM. A stator 1 of the three-phase TFSRM has a ring-shaped U-phase stator 1U, a ring-shaped V-phase stator 1V and a ring-shaped W-phase stator 1W, which are adjacent to each other in the axial direction AX of a rotor 4. The U-phase stator 1U has a ring-shaped stator core 2U and a ring-shaped U-phase winding 3U. The V-phase stator 1V has a ring-shaped stator core 2V and a ring-shaped V-phase winding 3V. The W-phase stator 1W has a ring-shaped stator core 2W and a ring-shaped W-phase winding 3W.

Each of the stator cores 2U, 2V and 2W consists of left stator teeth 21L, right stator teeth, a ring-shaped yoke portion 24, and left diagonal portions 25L and right diagonal portions 25R. Each of stator teeth 21L and 21R projects inward in the radial direction RA of the rotor 4. Each yoke portion 24 extends to the circumferential direction PH of the rotor 4.

Each left stator tooth 21L is arranged to each other to the circumferential direction PH. Each right stator tooth 21R is arranged to each other to the circumferential direction PH. Each left diagonal portion 25L is arranged to each other to the circumferential direction PH. Each right diagonal portion 25R is arranged to each other to the circumferential direction PH. Each left diagonal portion 25L joins each left stator tooth 21L and yoke portion 24. Each right diagonal portion 25R joins each right stator tooth 21R and yoke portion 24.

The left diagonal portion 25L extends diagonally from yoke portion 24 toward the forward direction of the axial direction AX. The right diagonal portion 25R extends diagonally from yoke portion 24 toward the rear direction of the axial direction AX. The left stator teeth 21L and right stator teeth 21R of U-phase stator core 2U are adjacent to each other in the axial direction AX across the ring-shaped U-phase winding 3U. The left stator teeth 21L and right stator teeth 21R of V-phase stator core 2V are adjacent to each other in the axial direction AX across the ring-shaped V-phase winding 3V. The left stator teeth 21L and right stator teeth 21R of W-phase stator core 2W are adjacent to each other in the axial direction AX across the ring-shaped W-phase winding 3W.

The rotor 4 of the three-phase TFSRM has a ring-shaped U-phase rotor core 4U, a ring-shaped V-phase rotor core 4V and a ring-shaped W-phase rotor core 4W, which are adjacent to each other in the axial direction AX. Each of the rotor cores 4U, 4V and 4W consists of left rotor teeth 41L; right rotor teeth 41R, a ring-shaped yoke portion 44, left diagonal portions 45L and right diagonal portions 45R each. The left rotor teeth 41L and the right rotor teeth 41R project outward in the radial direction RA. Each yoke portion 44 extends to the circumferential direction PH.

Left rotor tooth 41L are arranged to each other to the circumferential direction PH. Right rotor teeth 41R are arranged to each other to the circumferential direction PH. Left diagonal portions 45L are arranged to each other to the circumferential direction PH. Right diagonal portions 45R are arranged to each other to the circumferential direction PH. Each left diagonal portion 45L joins each left rotor tooth 41L and yoke portion 44. Each right diagonal portion 45R joins each right rotor tooth 41R and yoke portion 44. The left diagonal portion 45L extends diagonally from yoke portion 44 toward the forward direction. The right diagonal portion 45R extends diagonally from yoke portion 44 toward the rear direction.

Left rotor teeth 41L and right rotor teeth 41R of U-phase rotor core 4U are adjacent to each other in the axial direction AX across a ring-shaped non-magnetic spacer 6. Left rotor teeth 41L and right rotor teeth 41R of V-phase rotor core 4V are adjacent to each other in the axial direction AX across another ring-shaped non-magnetic spacer 6.

Left rotor teeth 41L and right rotor teeth 41R of W-phase rotor core 4W are adjacent to each other in the axial direction AX across another ring-shaped non-magnetic spacer 6. Left rotor teeth 41L faces the left stator teeth 21L with the same phase across a ring-shaped electro-magnetic gap 'g'. Right rotor teeth 41R face the right stator teeth 21R with the same phase across the ring-shaped electro-magnetic gap 'g'.

Each of cores 2U, 2V, 2W, 4U, 4V and 4W is made of a plurality of disc-shaped soft steel plates 7 laminated to the axial direction AX as shown in Figures 5 and 6. A spirally-laminated soft steel plate can be employed instead of a plurality of laminated soft steel plates 7. Laminated amorphous iron plates 7 or spirally-laminated amorphous iron plate can be employed instead of laminated soft steel plates 7 or the spirally-laminated soft steel plate.

Figure 6 shows two axially-laminated soft steel plates 7 and one soft steel plates 7 being laminating axially now. Each of soft steel plates 7 consists of left teeth 71L, right teeth 71R, a ring-shaped yoke portion 74, and left diagonal portions 75L and right diagonal portions 75R. The left teeth 71L and the right teeth 71R project radially inward. The yoke portion 74 extends to the circumferential direction. The left diagonal portions 75L extending diagonally joins left teeth 71L and yoke portion 74.

The right diagonal portions 75R extending diagonally joins right teeth 71R and yoke portion 74. Consequently, each of stator cores 2U, 2V and 2W is constructed by predetermined number of the laminated soft steel plates 7. Similarly, each of rotor cores 4U, 4V and 4W is constructed by predetermined number of laminated soft steel plates.

Left diagonal portions 75L and right diagonal portions 75R are formed by means of pressing a flat steel plate. Each of ring-shaped spacers 80 having triangle-shaped cross-section is inserted between the left stator teeth 21L and the right stator teeth 21R as shown in Figure 5. The ring-shaped non-magnetic spacer 80 comes into contact with diagonal portions 25L and 25R. Accordingly, an axial gap between the left stator teeth 21L and the right stator teeth 21R is kept by the ring-shaped non-magnetic spacer 80. Similarly, ring-shaped non-magnetic spacer 6 keeps an axial gap between the left rotor teeth 41L and the right stator teeth 41R.

Figure 7 is an enlarged cross-section, which schematically shows U-phase stator 1U with ring-shaped stator core 2U and ring-shaped U-phase winding 3U. It is considered that each ring-shaped gap 74g is formed between each pair of yoke portions 74 being adjacent to each other in the axial direction AX. Similarly, each teeth-shaped gap 71g is formed between each pair of left teeth 71L being adjacent to each other in the axial direction AX. Furthermore, each teeth-shaped gap 71g is formed between each pair of right teeth 71R being adjacent to each other in the axial direction AX, too. The gaps 74g and 71g can be buried with resin material or resin films. The resin films can include soft iron powder. Yoke portions 74 and teeth 71L and 71R can be curved in the axial direction in order to reduce axial vibration of yoke portions 74 and teeth 71L and 71R.

Figure 8 is a partial side view of U-phase stator 1U. Figure 9 partially shows a circumferential development of the ring-shaped U-phase stator core 2U. Left stator teeth 21L are arranged to the circumferential direction PH. Right stator teeth 21R are arranged to the circumferential direction PH. Two of the left stator teeth 21L are adjacent to each other across one non-magnetic spacer 8. The left diagonal portions 25L are arranged to the circumferential direction PH. The right diagonal portions 25R are arranged to the circumferential direction PH.

In Figure 8, left stator teeth 21L and left diagonal portions 25L are illustrated, but right stator teeth 21R and right diagonal portions 25R are hidden by non-magnetic spacers 8 disposed between right stator teeth 21R and right diagonal portions 25R, which are adjacent to each other in the circumferential direction. The non-magnetic spacers 8 are formed by molding resin material or non-magnetic metal. Left diagonal portion 25L and right diagonal portion 25R are arranged alternately in the circumferential direction PH. The rotor 4 is made with the same method explained above.

Similarly, U-phase rotor core 4U, V-phase rotor core 4V and W-phase rotor core 4W are constructed with the same method for constructing the three-phase stators 1U, 1V and 1W. The U-phase single-phase switched reluctance motor consists of the stator 1U and the rotor 4U. The V-phase single-phase switched reluctance motor consists of the stator 1V and the rotor 4V. The W-phase single-phase switched reluctance motor consists of the stator 1W and the rotor 4W. Each of three single-phase SRMs is operated by each single-phase pulse voltage, which has the phase-difference of 120 electrical degrees to each other.

For example, an inductance of U-phase winding 3U becomes the largest, when U-phase rotor teeth 41L and 41R face U-phase stator teeth 21L and 21R perfectly. The inductance of U-phase winding 3U becomes the smallest, when U-phase rotor teeth 41L and 41R are positioned between two U-phase stator teeth 21L and 21R. Driving operation of the switched reluctance motor is already well-known. Each of the single-phase pulse voltage for driving the single-phase SRM can be produced by a well-known a single-phase asynchronous power converter.

(The second embodiment)
A motor turbo-charger employing the TFPM is explained referring to Figures 10. Figure 10 is an axial cross-section of a rotor of a turbo-charger 9 with the single-phase TFPM. The turbo-charger 9 has a rotor 91 and a rotor 92. The rotor 91 of a radial compressor has blade-shaped wings 91A extending. The rotor 92 of a radial turbine has blade-shaped wings 92A. Two rotors 91 and 92 are fixed on an axis 93 of the turbo charger. The rotor 4 of the single-phase TFPM 10 is fixed on an intermediate portion of the axis 93. The TFPM 10 arranged between rotors 91 and 92 has the ring-shaped stator 1 surrounding rotor 4. The rotor 4 is made of a permanent magnet rotor 4 on which north poles and south poles are arranged in the circumferential direction alternately.

The TFPM turbo-charger shown in Figure 10 has benefits. Firstly, the stator winding 3 of the single-phase TFM 10 is accommodated in the ring-shaped stator core 2. Accordingly, stator winding 3 is protected from heat radiation of turbine rotor 92, which is extremely hot. Furthermore, the non-magnetic spacer 8 shown in Figure 8 shields the heat radiated by turbine rotor 92. Consequently, stator winding 3 can avoid super-heating.

Secondly, TFPM 10 can have a short axial length in comparison with the conventional motor having a conventional concentrated stator winding or a conventional distributed stator winding. Because, the conventional radial-gap-type motor has a pair of coil-ends of the stator winding, which projects to the axial direction AX. As the result, vibration of the axis 93 is reduced, because the axis 93 is shortened. A TFRM can be employed instead of the TFPM shown in Figure 10.

(The third embodiment)
The TFRM (transverse flux reluctance motor) of the third embodiment is explained referring to Figures 11 and 12. Figure 11 is an axial cross-section of a three-phase TFRM of the third embodiment. Figure 12 schematically shows a side view of a three-phase TFRM shown in Figure 11. As shown in Figure 12, the three-phase TFRM has two pairs of single-phase U-phase stator s 10U and 11U, two pairs of single-phase V-phase stators TFRMs 10V and 11V and two pairs of single-phase W-phase stators 10W and 11W. These six pairs of stators 10U and 11U, 10V and 11V and 10W and 11W are arranged in turn to the circumferential direction of the rotor 4 as shown in 12.

As shown in Figure 11, two of U-phase stators 10U and 11U are adjacent to each other in the axial direction AX. Similarly, two of V-phase stators 10V and 11V are adjacent to each other in the axial direction AX. Two of W-phase stators 10W and 11W are adjacent to each other in the axial direction AX. Each of six non-magnetic spacers 88 is disposed between two pairs of stators TFRMs, which are adjacent to each other in the circumferential direction. Each of stators 10U, 11U, 10V, 11V, 10W and 11W has arc-shape as shown in Figure 12.

A rotor 4 accommodated in the ring-shaped three-phase TFRM has a SMC (soft magnetic composite) ring 49 and a non-magnetic rotor disc 48 press-fixed on a rotating axis 93. The SMC ring 49 is fixed on an outer circumferential surface of the rotor disc 48. The SMC ring 49 has predetermined number of salient projecting radially outward.

Each of U-phase stators 10U and 11U shown in Figure 11 is essentially same as the stator 1U shown in Figure 5. However, each of stator 10U, 11U, 11V, 10W and 11W has arc-shape, but the stator 1U shown in Figure 5 has ring-shape. An arc-shaped U-phase winding consists of an arc-shaped going-half portion 30U and an arc-shaped coming-half portion 31U. One end of a conductor line of the going-half portion 30U is joined to one end of a conductor line of the coming-half portion 31U. In the other words, the U-phase winding consisting of going-half portion 30U and coming-half portion 31U is a concentrated winding wound on two arc-shaped stators 10U and 11U. Both ends U+ and U- of the U-phase winding are pulled out from non-magnetic spacers 88.

Similarly, the arc-shaped V-phase winding consisting of a going-half portion and a coming-half portion is a concentrated winding wound on the arc-shaped V-phase stators 10V and 11V. Both ends V+ and V- of the V-phase winding are pulled out from non-magnetic spacers 88. Similarly, the arc-shaped W-phase winding consisting of going-half portion and coming-half portion is a concentrated winding wound on the arc-shaped W-phase stators 10W and 11W. Both ends W+ and W- of the W-phase winding are pulled out from non-magnetic spacers 88.

One benefit of the above three-phase TFRM with arc-shaped stators is that conductor lines of the phase winding can be pulled out easily. Furthermore, the three-phase TFRM shown in Figures 12 has a thin thickness in the axial direction AX.

One production process of the ring-shaped stator core shown in Figure 5 is explained referring to Figures 13-17. Figure 13 is a schematic side view showing one ring-shaped soft steel plate 100 before and after bending in order to form the left diagonal portions 25L and the right diagonal portions 25R. Firstly, the ring-shaped plate 100 is made by cutting and pressing a flat soft steel plate. As shown in Figure 13, the ring-shaped plate 100 has many cut lines 101 extending to the radial direction.

An outer peripheral portion 102 of ring-shaped plate 100 does not have the cut lines 101, because the outer peripheral portion 102 becomes the ring-shaped yoke portion 24. An inner portion of ring-shaped plate 100 is divided to odd segments 103A and even segments 103B. Secondly, odd segments 103A are bent toward one side of the axial direction. As the result, the left diagonal portions 25L and the left stator teeth 21L are formed on the odd segments 103A. Boundary lines 200 are formed between the left diagonal portions 25L and the left stator teeth 21L.

Thirdly, even segments 103A are bent toward the other side of the axial direction. The right diagonal portions 25R and the right stator teeth 21R are formed on the even segments 103B. Boundary lines 200 are formed between the right diagonal portions 25R and the right stator teeth 21R. Left stator teeth 21L are apart from right stator teeth 21R in the axial direction. Ring-shaped stator winding 3U is accommodated in the ring-shaped gap between left stator teeth 21L and right stator teeth 21R as shown in Figure 13.

One example of the bending process is explained referring to Figures 14-17. Firstly, even segments 103B are bended as shown in Figures 14 and 15 in order to produce the right diagonal portions 202R and the right stator teeth 203R. The right diagonal portions 202R and the right stator teeth 203R are formed on the even segments 103B. Secondly, odd segments 103A are bended as shown in Figures 16 and 17 in order to produce the left diagonal portions 202L and the left stator teeth 203L. The left diagonal portions 202L and the left stator teeth 203L are formed on the odd segments 103A.

In Figures 14 and 15, three dies 301-303 are employed in order to make the right teeth portions 203R and the right diagonal portions 202R. In Figures 16 and 17, two dies 304-305 are employed in order to make the left teeth portions 203L and the left diagonal portions 202L. The left stator teeth 21L consist of laminated left teeth portions 203L. The right stator teeth 21R consists of laminated left teeth portions 203R. The left diagonal portion 25L consists of laminated left diagonal portions 202L. The right diagonal teeth 25R consists of laminated right diagonal portions 202R.

(The fourth embodiment)
A linear TFSRM apparatus 400 of the fourth embodiment is explained referring to Figures 18 and 19. Figure 18 is a transverse cross-section of the linear TFM apparatus 400. Figure 19 schematically shows a side view of the linear TFM apparatus 400 shown in Figure 18. In Figure 18, a rectangular-block-shaped housing 401 of the linear TFM apparatus 400 is made from aluminum alloy. The housing 401 has two through- holes 404 and 405 accommodating linear movers 402 and 403 respectively.

The linear mover 402 is accommodated between a pair of six stators 2. The linear mover 403 is accommodated between another pair of six stators 2. Each stator 2 is fixed to a non-magnetic housing 401. The linear movers 402 and 403 can have both of permanent magnets and soft magnetic composites in order to form the movers of a linear TFPM. As shown in Figure 19, a pair of top portions of the linear movers 402 and 403 is fixed to one head 406 connecting one piston (not shown). A pair of the other top portions of the linear movers 402 and 403 is fixed to the other one head 407 connecting the other piston (not shown). Coil springs 408 and 409 are wound around movers 402 and 403 in order to force the heads 406 and 407 elastically. Accordingly, the TFPMs drives the two pistons to the axial direction AX.

In a preferred embodiment, the linear TFSRM apparatus 400 of the fourth embodiment shown in Figures 18 and 19 is employed for a linear type internal combustion engine (a linear ICE) or a linear gas compressor. For example, the one head 406 shown in Figure 19 is connected to one piston of sliding on an inner surface of a first cylinder of the linear ICE of the dual-cylinder type. The other head 407 shown in Figure 19 is connected to the other piston of sliding on an inner surface of a second cylinder of the linear ICE of the dual-cylinder type. The linear TFM apparatus 400 drives the reciprocating pistons toward both sides of the axial direction AX in order to start the linear ICE.

After starting the linear ICE, linear TFM apparatus 400 generates an electric power for driving a traction motor. Accordingly, a series-hybrid vehicle having the above linear ICE can have very simple and compact structure with a light weight, because the linear ICE does not need rotating mechanism around a crank shaft of the ICE. As the result, the hybrid vehicle can have a compact drive train with the light weight. The above ICE does not need a conventional starter and an alternator, too.

In the above-explained embodiments, the stator core having the ring-shape or the arc-shape is constructed with the axially-laminated steel sheets having the ring-shape or the arc-shape, which are separated from the long and flat steel sheet and bent by means of press process. However, the stator core can be constructed with a spirally-wound steel sheet, which is laminated axially by means of employing plastic deformation of a flat tape-shaped steel sheet. The ring-shaped or arc-shaped yoke portion can be has convex portions projecting to the axial direction.

Another arrangement is explained referring to Figures 20 and 21. Figure 20 is an enlarged cross-section of three steel plates 7 laminated to the axial direction AX. Figure 21 is an enlarged cross-section of the three steel plates 7 shown in Figure 20. 'PH' shows the circumferential direction. Each of steel plates 7 has curved boundary portions between teeth 71 and diagonal portions 75. Each of steel plates 7 has curved boundary portions between diagonal portions 75 and ring-shaped yoke portion 74.

A plurality of teeth spacers 71g are disposed between each two stator teeth 71 being adjacent in the axial direction AX to each other. Cooling air passages 71a are formed between two teeth spacers 71g being adjacent in the circumferential direction PH to each other as shown in Figure 21. Similarly, a plurality of yoke spacers 74g are disposed between each two yoke portions 74 being adjacent in the axial direction AX to each other. Cooling air passages are formed between two teeth spacers 74g being adjacent in the circumferential PH to each other. Cooling air flows in the passages to the radial direction RA. Each of steel plates 7 are cooled well by the cooling air produced by rotation of rotor 4.

The magnet flux MF in the electro-magnetic gap 'g' between the stator teeth and the rotor teeth is shown in Figure 22. Thickness of each steel plate 7 is 0.35 mm. Thickness of each air gap between two steel plates 7 is 0.14 mm. The magnet flux MF is formed in the electro-magnetic gap 'g' between steel plates 7 of stator teeth 21 and rotor teeth 41. The magnet flux MF is curved, because spacers 71g are disposed between two steel plates 7 being adjacent to each other in the axial direction AX. It means that the magnetic resistance of the gap 'g' is reduced.

(The fifth embodiment)
A three-phase TFPM of the fifth embodiment is explained referring to Figures 23-25. Figure 23 is an axial cross-section of the three-phase TFPM (transverse flux permanent magnet machine). Figure 24 is a partial development of the stator teeth shown in Figure 23. Figure 25 is a partial development showing the outer circumferential surface of a rotor 4 shown in Figure 23.

Stator 1 has the ring-shaped U-phase stator core 2U, the ring-shaped V-phase stator core 2V and the ring-shaped W-phase stator core 2W, which are left stator teeth 21L and right stator teeth 21R each. The electrical angle between the left stator teeth 21L and the right stator teeth 21R is 180 degrees. The electrical angle between left stator teeth 21L of each-phase is 120 degrees. The three-phase stator 1 is essentially same as the stator 1 shown in Figure 5.

The rotor 4 has a non-magnetic rotor disc 48 and a cylinder-shaped permanent magnet rotor core 49 fixed on an outer circumferential surface of the rotor disc 48. The rotor disc 48 is made from aluminum alloy, and the rotor core 49 is made from permanent magnet material for example the ferrite magnet. The outer circumferential surface of permanent magnet rotor core 49 has north pole areas 49N and south pole areas 49S, which are arranged alternately to the circumferential direction PH as shown in Figure 25. Each circumferential width of pole areas 49N and 49S is equal to an electrical angle of 180 degrees.

Left stator teeth 21L faces north pole areas 49N, when right stator teeth 21R faces south pole areas 49S. Left stator teeth 21L faces south pole areas 49S, when right stator teeth 21R faces north pole areas 49N. Each pole areas 49N and 49S extend to the axial direction AX. As the result, three-phase TFPM is produced.

One arrangement of rotor 4 is shown in Figure 26. Figure 26 is a partial development showing the outer circumferential surface of the cylinder-shaped rotor core 49. Rotor core 49 consists of a cylinder-shaped soft magnetic composite core 49X and the rectangular-segment-shaped permanent magnets 49N and 49S. The permanent magnets 49N form the north pole areas. The permanent magnets 49S forms the south pole areas. The permanent magnets 49N and 49S are fixed on the cylinder-shaped SMC core 49X. The rotors 4 shown in Figure 25 and 26 consist of the permanent magnet rotor.

(The sixth embodiment)
A three-phase TFPM is explained referring to Figures 27-31. Figure 27 is an axial cross-section of the three-phase TFPM (transverse flux permanent magnet machine). Figure 28 is a partial development of the stator teeth shown in Figure 27. Figure 29 is a partial development showing the outer circumferential surface of the U-phase rotor 4U shown in Figure 27. Figure 30 is an axial cross-section of U-phase rotor 4U along a line X-X. Figure 31 is an axial cross-section of U-phase rotor 4U along a line Y-Y.

Stator 1 has same structure as stator 1 shown in Figure 23. Stator 1 consists of a U-phase stator 1U, a V-phase stator 1V and a W-phase stator 1W. U-phase stator 1U has U-phase winding 3U accommodated in U-phase stator core 2U. V-phase stator 1V has V-phase winding 3V accommodated in V-phase stator core 2V. W-phase stator 1W has W-phase winding 3W accommodated in W-phase stator core 2W.

However, circumferential positions of stator teeth 21L, 21R of each phase are arranged as shown in Figure 28. In the other words, left stator teeth 21L of each phase have equal positions to each other in the circumferential direction PH. Similarly, right stator teeth 21R of each phase have equal positions to each other in the circumferential direction PH. Each of ring-shaped non-magnetic spacers 300 is disposed between two of three stator cores 2U, 2V and 2W. Accordingly, mutual inductances and leakage inductances between two phases are reduced.

U-phase rotor 4U is explained referring to Figures 29-31. U-phase rotor 4U has the laminated rotor core and a permanent magnet ring 49. The laminated rotor core, which is essentially same as the rotor core 4U shown in Figure 5, consists of left rotor teeth 41L, right rotor teeth 41R, left diagonal portions 45L, right diagonal portions 45R and ring-shaped common rotor yoke 44. The permanent magnet ring 49 is formed from resin including magnet powder. The permanent magnet ring 49 is buried in a space surrounding rotor teeth 41L and 41R. As the result, the outer circumferential surface of the rotor 4U has a cylinder-shape surface. The outer circumferential surface of permanent magnet ring 49 is magnetized as shown in Figure 29. The areas 401 and 404 become the north pole areas. The areas 402 and 403 become the south pole areas.

Right stator teeth 21R face north pole area 401, when left stator teeth 21L face south pole area 402. Right stator teeth 21R face south pole area 403, when stator teeth 21U face north pole area 404. Left stator teeth 21L face left rotor teeth 41L, when right stator teeth 21R face right rotor teeth 41R. Relation between V-phase stator 1V and V-phase rotor 4V has essentially same as relation between U-phase stator 1U and U-phase rotor 4U. Relation between W-phase stator 1W and W-phase rotor 4W has essentially same as relation between U-phase stator 1U and U-phase rotor 4U. In the other words, rotor teeth 41L and 41R produce q-axis flux passages. As the result, the above three-phase TFPM can produce the reluctance torque and the magnetic torque. Moreover, permanent magnet ring 49 reduces vibration of the rotor teeth 41L and 41R.

(The seventh embodiment)
Figure 32 is a circuit diagram showing a motor-driving circuit for driving the three single-phase TFSMs without the three-phase TFSRM explained above. The TFSM means the transverse flux synchronous motor including the permanent magnet type and the synchronous reluctance type. In this embodiment, U-phase stator winding 3U, V-phase stator winding 3V and W-phase stator winding 3W are driven by a conventional three-phase inverter 500 having six switches 11, 12, 21, 22, 31 and 32. In prior arts of driving the three single-phase TFMs, three of full-bridge single-phase inverters are employed in order to driving three TFMs. However, the three full-bridge single-phase inverters need twelve switching transistors. The three-phase inverter shown in Figure 32 requires only six switching transistors. Accordingly the inverter can become simple.

(The eighth embodiment)
The eighth embodiment shown in Figures 33-38 discloses a six-phase DC-current-assisted TFSRM. Figure 33 is a partial cross section of the six-phase TFSRM having a stator 100 and a rotor core 400. The stator 100 has six single-phase stators 101-106 and six rotor cores 401-406. The six single-phase stators 101-106 are fixed to an inner circumferential surface of a non-magnetic motor housing 600. The six rotor cores 401-406 are fixed to an outer circumferential surface of a non-magnetic rotor disc 700.

The stator 101 has a DC winding 501 and an AC winding 301. The stator 102 has a DC winding 502 and an AC winding 302. The stator 103 has a DC winding 503 and an AC winding 303. The stator 104 has a DC winding 504 and an AC winding 304. The stator 105 has a DC winding 505 and an AC winding 305. The stator 106 has a DC winding 506 and an AC winding 306. All of DC windings 501-506 and AC windings 301-306 have ring-shape.

Stator core 101 has left stator teeth 21L and right stator teeth 21R. Stator core 102 has left stator teeth 22L and right stator teeth 22R. Stator core 103 has left stator teeth 23L and right stator teeth 23R. Stator core 104 has left stator teeth 24L and right stator teeth 24R. Stator core 105 has left stator teeth 25L and right stator teeth 25R. Stator core 106 has left stator teeth 26L and right stator teeth 26R.

Rotor core 401 has left rotor teeth 41L and right rotor teeth 41R. Rotor core 402 has left rotor teeth 42L and right rotor teeth 42R. Rotor core 403 has left rotor teeth 43L and right rotor teeth 43R. Rotor core 404 has left rotor teeth 44L and right rotor teeth 44R. Rotor core 405 has left rotor teeth 45L and right rotor teeth 45R. Rotor core 406 has left rotor teeth 46L and right rotor teeth 46R. Circumferential positions of left rotor teeth 41L, 42L, 43L, 44L, 45L and 46L is shown in Figure 34. Each of left stator teeth 21L, 22L, 23L, 24L, 25L and 26L is disposed at equal circumferential positions to each other.

An angle between left rotor teeth 41L and 42L is 120 electrical degrees. An angle between rotor teeth 42L and 43L is 120 electrical degrees. An angle between rotor teeth 41L and 44L is 180 electrical degrees. An angle between rotor teeth 42L and 45L is 180 electrical degrees. An angle between rotor teeth 43L and 46L is 180 electrical degrees.

Figure 35 is a circuit diagram showing a six-phase power converter 800 for driving a six-phase DC-current-assisted TFSRM shown in Figure 33. The power converter 800 has three full-bridge inverters 801-803. The U-phase AC windings 301 and 304 connected in series to each other are driven by the full-bridge inverter 801 consisting of two half- bridge legs 801A and 801B. The V- phase AC windings 302 and 305 connected in series to each other are driven by the full-bridge inverter 802 consisting of two half- bridge legs 802A and 802B. The W- phase AC windings 303 and 306 connected in series to each other are driven by the full-bridge inverter 803 consisting of two half-bridge legs 803A and 803B. The full-bridge inverter 801 controls a U-phase AC current Iu supplied to U-phase AC windings 301 and 304 with the PWM method. The full-bridge inverter 802 controls a V-phase AC current Iv supplied to V-phase AC winding 302 and 305 with the PWM method. The full-bridge inverter 803 controls a W-phase AC current Iw supplied to W- phase AC windings 303 and 306 with the PWM method.

Furthermore, the power converter 800 has a DC-current-controlling switch 804 and a free-wheeling diode 805. The DC-current-controlling switch 804 is connected to the series-connected DC windings 501-506 in series. The free-wheeling diode 805 is connected to the series-connected DC windings 501-506 in parallel. A DC current Idc flowing through the DC windings 501-506 is controlled by the PWM-switched DC-current-controlling switch 804.

Figure 36 is a timing chart showing waveforms of three AC phase currents Iu, Iv and Iw, DC current Idc, inductances of six phase windings L301-L306 and torques T301-T306. U-phase winding 301 with the inductance L301 produces a torque T301. V-phase winding 302 with the inductance L302 produces a torque T302. W-phase winding 303 with the inductance L303 produces a torque T303. U-phase winding 304 with the inductance L304 produces a torque T304. V-phase winding 305 with the inductance L305 produces a torque T305. W-phase winding 306 with the inductance L306 produces a torque T306. Consequently, a sum of six-phase torques becomes flat.

Figure 37 is an enlarged timing chart showing waveforms of U-phase. From 0 electrical degrees to 120 electrical degrees, U-phase left stator teeth 21L is magnetized to the north pole by both of U-phase current Iu and DC current Idc, which are supplied to U-phase winding 301 and U-phase DC winding 501. Ampere-turns of windings 301 and 501 are equal to each other. As the result, total ampere-turns given to U-phase left stator teeth 21L becomes mostly double in comparison with only the AC winding 301.

However, from 0 electrical degrees to 120 electrical degrees, U-phase left stator teeth 24L is magnetized to the south pole by U-phase current Iu supplied to U-phase winding 304. But, U-phase left stator teeth 24L is also magnetized to the north pole by DC current Idc supplied to DC winding 504. Ampere-turns of windings 304 and 504 are equal to each other. As the result, total ampere-turns given to U-phase left stator teeth 24L becomes mostly zero. Consequently, U-phase left stator teeth 21L is magnetized strongly, and U-phase left stator teeth 24L is not magnetized in a period from 0 electrical degrees to 120 electrical degrees. Similarly, U-phase left stator teeth 24L is magnetized strongly, and U-phase left stator teeth 21L is not magnetized in a period from 180 electrical degrees to 300 electrical degrees.

Similarly, V-phase left stator teeth 22L is magnetized, and V-phase left stator teeth 25L is not magnetized in a period 120 electrical degrees to 240 electrical degrees. Similarly, V-phase left stator teeth 22L is not magnetized, and V-phase left stator teeth 25L is magnetized in a period 300 electrical degrees to 60 electrical degrees. Similarly, W-phase left stator teeth 23L is magnetized, and W-phase left stator teeth 26L is not magnetized in a period 240 electrical degrees to 0 electrical degrees. Similarly, W-phase left stator teeth 23L is not magnetized, and W-phase left stator teeth 25L is magnetized in a period 60 electrical degrees to 180 electrical degrees.

As shown in Figure 38, from 180 degrees to 300 degrees, U-phase left stator teeth 21L is magnetized to the south pole by U-phase current Iu supplied to U-phase winding 301. But, U-phase left stator teeth 21L is magnetized to the north pole by DC current Idc supplied to DC winding 501. Ampere-turns of windings 301 and 501 are equal to each other. As the result, total ampere-turns given to U-phase left stator teeth 21L becomes mostly zero.

However, from 180 degrees to 300 degrees, U-phase left stator teeth 24L is magnetized to the north pole by both of U-phase current Iu and DC current Idc, which are supplied to U-phase winding 304 and U-phase DC winding 504. Ampere-turns of windings 304 and 504 are equal to each other. As the result, total ampere-turns given to U-phase left stator teeth 24L becomes mostly double in comparison with only the AC winding 304.

In the other words, the AC phase current of this embodiment can become half of the conventional SRM. As the result, a power loss of U-phase full-bridge 801 is largely decreased. V-phase full-bridge 802 and W-phase full-bridge 803 can have the reduced power loss each, too. Furthermore, magnetic energy accumulated periodically in the AC phase winding 301-306 becomes mostly 25%, because the amplitudes of the AC phase currents become half. Moreover, total magnetic energy of phase winding 301 and 304 becomes constant for the period from 0 electrical degrees to 120 electrical degrees. The magnetic energy is transported alternately between windings 301 and 304.

The turns of DC windings 501-506 are further more than AC windings 301-306. An inductive influence of DC winding 501, which is given by U-phase winding 301, becomes opposite and mostly equal amplitude in comparison with an inductive influence of DC winding 504, which is given by U-phase winding 301, when U-phase AC current Iu is changed. Because total inductances value of AC windings 301 and 304 are not changed. As the result, a sum of induced voltages of DC windings 501 and 504 becomes zero. The amplitude of DC current Idc should be kept to equal to the absolute amplitude of the each of AC current except the transient period of the AC current by means of switching the switch 804.

(Arrangements)
Permanent magnets disposed on the stator core can be employed instead of DC windings 501-506, if the required torque is not variable. Similarly, a four-phase SRM is driven by two-full bridge inverter, too. Moreover, the above-explained DC-current-assisted TFSRM having the DC winding and the AC phase windings can be employed by a conventional TFSRM or a conventional SRM. The conventional TFSRM or the conventional SRM are driven by the full bridge inverter as shown in Figure 35.

(The ninth embodiment)
The ninth embodiment is explained referring to Figures 39-41. One feature of this embodiment is that each of three AC phase currents Iu, Iv and Iw has sinusoidal waveform shown in Figure 39. Accordingly, the power converter can consists of a conventional three-phase inverter with three half inverters 801A, 802A and 803A as shown in Figure 40. Three-phase AC phase windings 301-306 accommodated in six stator cores shown in Figure 33 can have the star connection or the delta connection, because a sum of three phase currents Iu, Iv and Iw becomes zero. The iron loss of the motor can be reduced, too.

Another feature of this embodiment is that each of inductances L301-L306 of AC windings 301-306 has sinusoidal waveforms changing in accordance with the rotation as shown in Figure 39. Each of three phase currents Iu, Iv and Iw become large in a period when each of inductances L301-L306 changes rapidly. For example, each corner of at least one of the stator teeth and the rotor teeth has a curved shape in order to give the sinusoidal waveform to the inductances L301-L306 as shown in Figure 41.

Japan unexamined patent publication 2010-193700 applied by the applicant of this application discloses the conventional SRM with the DC winding. However, the publication 2010-193700 does not supply the AC phase current with the sinusoidal waveforms.

Other arrangements of the soft magnetic plate 7 are shown in Figures 42 and 43. The plates 7 shown in Figures 42 and 43 have a center teeth 71c extending straightly from the yoke portion 74. Accordingly, the left teeth 71L, the center teeth 71C and the right teeth 71R are arranged in the circumferential direction. These arranged teeth structure is included in this invention.

(The tenth embodiment)
The tenth embodiment is explained referring to Figures 44-48. This embodiment shows a power converter driving an even-phase TFSRM or an even-phase conventional SRM. Figure 44 is a circuit diagram showing a prior well-known two-phase asynchronous power converter for driving a conventional SRM. One asynchronous converter H1 for driving a phase winding 901 has an upper switch 903, a lower switch 904 and free-wheeling diodes D1 and D2. Another asynchronous converter H2 for driving another phase winding 902 has an upper switch 905, a lower switch 906 and free-wheeling diodes D3 and D4. The phase winding 901 has the inductance L901. The phase winding 902 has the inductance L902. A connecting diode D5 can be employed.

Figure 45 is a circuit diagram showing a two-phase asynchronous power converter for driving a conventional SRM or the TFSRM having at least two-phase being opposite to each other. The power converter shown in Figure 45 is essentially same as the power converter shown in Figure 44. However, the power converter shown in Figure 45 has a connecting line 907 connecting the low potential end of one phase winding 901 to the high potential end of another phase winding 902.

Figure 46 is a timing chart showing waveforms of phase current Iu1, Iu2, inductances L901 and L902. The phase current Iu1 is supplied to the phase windings 901 having the inductance L901. The phase current Iu2 is supplied to the phase windings 902 having the inductance L902. Two inductances have opposite wave forms to each other. Two phase currents Iu1 and Iu2 have opposite wave forms to each other. In the other words, the phase difference between two phase currents Iu1 and Iu2 is 180 electrical degrees. The phase difference between two inductances L901 and L902 is 180 electrical degrees.

In a first transient period T1 from a time point t1 and a time point t2, the inductance L901 has the smallest value Lmin, and the inductance L902 has the largest value Lmax. In a second transient period T2 from a time point t3 and a time point t4, the inductance L901 has the largest value Lmax, and the inductance L902 has the smallest value Lmin.

Figure 47 is a circuit diagram showing currents Iu1 and If in the period T2. The switches 903 and 904 of the power converter H1 are turned off, and the switches 905 and 906 of the power converter H2 are turned on. A free-wheeling current If of the phase winding 901 flows through upper switch 905 instead of the free-wheeling diode D2. As the result, a power loss of the diode D2 is reduced. Moreover, the phase current Iu2 flowing to the phase winding 902 through upper switch 905 is decreased by the free-wheeling current If. As the result, a power loss of upper switch 905 is reduced.

Figure 48 is a circuit diagram showing currents Iu2 and If in the period T1. The switches 903 and 904 of the power converter H1 are turned on, and the switches 905 and 906 of the power converter H2 are turned off. A free-wheeling current If of the phase winding 902 flows through lower switch 904 instead of the free-wheeling diode D3. As the result, a power loss of the diode D3 is reduced. Moreover, the current Iu1 flowing to the phase winding 901 through lower switch 904 is decreased by the free-wheeling current If. As the result, the power loss of lower switch 904 is reduced. Consequently, the two-phase power converter shown in Figures 45 can save the power consumption, when the converter drives the two-phase TFSRM or the two-phase conventional SRM. An even-phase SRM with more phases can be driven by a plurality of the above two-phase power converter shown in Figure 45.

(The eleventh embodiment)
The eleventh embodiment is explained referring to Figure 49. This embodiment shows a motor-driving apparatus for driving a three-phase TFSynRM 910, which is a three-phase transverse flux synchronous reluctance motor. The three-phase sinusoidal voltage is applied to a three-phase synchronous reluctance motor 910 such like the three-phase TFRM shown in Figure 41. The three-phase TFSynRM 910 is driven by the AC/DC/AC converter 911 via a three-phase relay 913. Moreover, a three-phase line of a grid network is connected to TFSynRM 910 via a three-phase relay 912. The AC/DC/AC converter 911 has a three-phase AC/DC converter and three-phase inverter. The three-phase inverter such like three-phase power converter shown in Figure 40 applies the three-phase voltage, for example the three-phase voltage shown in Figure 39.

Operation of the motor-driving apparatus shown in Figure 49 is explained. Firstly, the relay 913 is turned on, after the relay 912 is turned off. Next, the AC/DC/AC converter 911 applies the three-phase voltage to TFSynRM 910. After a rotation speed is synchronized with the frequency of the three-phase grid network, the relay 912 is turned on after the relay 913 is turned off. Consequently, the power loss of the AC/DC/AC converter 911 is reduced, when the converter 911 drives the three-phase SynRM including TFSynRM 910 with a constant speed. The motor-driving apparatus with less-phase can drive a single-phase or two-phase TFSynRM, too.

(The twelfth embodiment)
The twelfth embodiment is explained referring to Figure 50. Figure 50 is an axial cross-section showing a three-phase TFSRM accommodated in a motor housing 600. The TFSRM shown in Figure 50 is essentially same as the TFSRM shown in Figure 5 or Figure 33. The feature of this embodiment is on the motor housing 600 consisting of side discs 601 and 604 and intermediate rings 602 and 603. Three stator cores 2U, 2V and 2W are fixed to the motor housing 600. In particular, the side disc 601 has projections 610 projecting between two left stator teeth of the U-phase stator core 2U. The side disc 604 has projections 611 projecting between two right stator teeth of the W-phase stator core 2W.

The intermediate rings 602 and 603 have projections 610 and 611. The projections 610 of intermediate rings 602 project between two right stator teeth of U-phase stator core 2U. The projections 611 of intermediate rings 602 project between two left stator teeth of V-phase stator core 2V. The projections 610 of intermediate rings 603 project between two right stator teeth of V-phase stator core 2V. The projections 611 of intermediate rings 603 project between two left stator teeth of W-phase stator core 2W. Accordingly, vibration of stator teeth can be suppressed by motor housing 600. The projections come into contact with the stator teeth across electrical insulation resin layer. Accordingly, the eddy current is reduced. Similarly, the rotor disc 700 has projections 710 and 711 projecting between two rotor teeth, which are adjacent to each other in the circumferential direction.

The TFSRM shown in Figure 50 constitutes an in-wheel motor of a battery vehicle. Heat of rotor cores 4U, 4V and 4W is transferred to a rotating axis (not shown) via the rotor disc 700. The rotating axis can have a cooling disc disposed out of the motor housing 600. The heat of the rotor core 4U, 4V and 4W is radiated by the cooling disc fixed to the rotating axis. The heat of stator cores 2U, 2V and 2W and stator windings 3U, 3V and 3W is transferred to the vehicle body (not shown) via motor housing 600. It is preferable to connect motor hosing and the vehicle body by a flexible heat pipe. The heat of the stator is transferred to the vehicle body.

(The thirteenth embodiment)
The thirteenth embodiment is explained referring to Figures 51 and 52. Figure 51 is an axial cross-section showing a single-phase induction TFM accommodated in a motor housing consisting of a left bowl portion 600A and a right bowl portion 600B. Figure 52 is a circumferential development of the single-phase induction TFM shown in Figure 51.

A pair of stator 1 and the rotor core 4U is essential same as the pair of one-phase stator and one-phase rotor, which are explained above. Stator 1 has the single-phase stator core 2U and single-phase stator winding 3U accommodated between the left stator teeth 21L and the right stator teeth 21R. Stator core 2U is fixed to a pair of the left bowl portion 600A and the right bowl portion 600B made from aluminum.

Single-phase rotor core 4U has the left rotor teeth 41L and the right rotor teeth 41R. Rotor core 4U is buried in the rotor disc 700 made from aluminum except top portions, which is pole portions, of rotor teeth 41L and 41R. As the result, rotor disc 700 consists of the well-known squirrel-cage winding of a single-phase induction motor.

(The fourteenth embodiment)
The fourteenth embodiment is explained referring to Figures 53 and 54. Figure 53 is an axial cross-section showing a double-sided two-phase reluctance TFM accommodated in a motor housing 600 consisting of disc portions 600A and 600B and a center cylindrical portion 600C. Figure 54 is a circumferential development of the TFM shown in Figure 53.

Stator 1 has a first pair of U-phase stators 200U and 201U and a second pair of V-phase stators 200V and 201V. The U-phase stator 200U is fixed between portions 600A and 600C. The V-phase stator 200V is fixed between portions 600C and 600B. The U-phase stator 201U is fixed on the left-side disc portions 600A. The V-phase stator 201V is fixed on the right-side disc portions 600B.

Rotor 4 has four groups of rotor teeth 401-404 fixed to a rotor disc 700 made from aluminum alloy. The rotor disc 700 has a left cylinder portion 701A and a right cylinder portion 701B. Two cylinder portions 701A and 701B have through-holes for accommodating rectangular-segment-shaped rotor teeth 401-404. The cylinder portions 701A and 701B have slits 702 extending to the axial direction AX from the inner through-holes for accommodating the inner rotor teeth 402 and 403. The rotor teeth 401-404 made from laminated soft steel sheets are press-fixed into the through-holes. The through-holes disposed in order to protect the eddy currents can be abbreviated, when the TFM is the induction TFM. The rotor has a pair of resin discs 703 covering the side surfaces of the cylinder portions 701A and 701B.

The left stator teeth of U-phase stator 200U and 201U face the rotor teeth 401. The right stator teeth of U-phase stator 200U and 201U face the rotor teeth 402. The left stator teeth of V-phase stator 200V and 201V face the rotor teeth 403. The right stator teeth of V-phase stator 200V and 201V face the rotor teeth 404. The U-phase voltage is applied to ring-shaped U-phase windings 300U and 301U, which are connected in series. The V-phase voltage is applied to ring-shaped V-phase windings 300V and 301V, which are connected in series. A benefit of the double-sided TFM shown in Figures 57 and 58 is on a short axial length of cylinder portions 701A and 702 projecting to the axial direction AX, because the inner phase windings 301U and 301V do not need the coil ends of the conventional phase windings of the conventional double-sided motor.

The above two-phase motor can be driven by a two-phase inverter having two full-bridge inverters consisting of two half-bridges each. In order to operate the PWM-switching of the full-bridge inverter, the one of two half-bridges can be PWM-switched, and the other of two half-bridges can be not PWM-switched. In this case, Transistors of the PWM-switched half-bridge can have lower turned-on-resistances than transistors of the PWM-switch-less half-bridge. As the result, the inverter cost is reduced.

Claims (11)

1. An electric machine comprising:
   a rotor core (4U) capable of including a mover of a linear machine; and
   a stator (1) having a stator core (2U) and a stator winding (3U) accommodating in the stator core (2U);
   wherein the stator core (2U) has left stator teeth (21L), right stator teeth (21R), which are extending from a stator yoke portion (24) toward the rotor core (4U) each;
   the stator winding (3U) extending to a moving direction (PH) of the rotor core (4U) is accommodated between the left stator teeth (21L) and the right stator teeth (21R);
   the left stator teeth (21L) and the right stator teeth (21R) are arranged to the moving direction (PH) each;
   the stator core (2U) has soft magnetic plates (7) laminated to a direction (AX) that is mostly equal to a right angle for the moving direction (PH);
   each soft magnetic plate (7) of the stator core (2U) has left teeth (71L), right teeth (71R), a yoke portion (74) and left diagonal portions (75L) and right diagonal portions (75R);
   the left diagonal portions (75L) extending diagonally joins the yoke portion (74) as the stator yoke portion (24) and the left teeth (71L) as the left stator teeth;
   the right diagonal portions (75R) extending diagonally joins the yoke portion (74) as the stator yoke portion (24) and the right teeth (71R) as the right stator teeth; and
   the left teeth (71L) and the right teeth (71R) are arranged alternately in the moving direction (PH).
2. The electric machine according to claim 1:
   wherein the rotor core (4U) has left rotor teeth (41L), right rotor teeth (41R), which are extending from a rotor yoke portion (44) toward the stator core (2U) each;
   the left rotor teeth (41L) and the right rotor teeth (41R) are arranged to the moving direction (PH) each;
   the rotor core (4U) has soft magnetic plates (7) laminated to a direction (AX) that is mostly equal to a right angle for the moving direction (PH);
   each soft magnetic plate (7) of the rotor core (4U) has left teeth (71L), right teeth (71R), a yoke portion (74) and left diagonal portions (75L) and right diagonal portions (75R);
   the left diagonal portions (75L) extending diagonally joins the yoke portion (74) as the rotor yoke portion (44) and the left teeth (71L) as the left rotor teeth;
   the right diagonal portions (75R) extending diagonally joins the yoke portion (74) as the rotor yoke portion (44) and the right teeth (71R) as the right rotor teeth; and
   the left teeth (71L) and the right teeth (71R) are arranged alternately in the moving direction (PH).
3. The electric machine according to claim 2:
   wherein the left rotor teeth (41L) faces the left stator teeth (21L), when the right rotor teeth (41R) faces the right stator teeth (21R).
4. The electric machine according to claim 1:
   wherein the rotor core (4U) has a permanent magnet; and
   North Pole areas of the permanent magnet face the left stator teeth (21L), when South Pole areas of the permanent magnet face the right stator teeth (21R).
5. The electric machine according to claim 1:
   wherein the laminated soft magnetic plates (7) have spacers (71g) between each two teeth (71L, 71R) being adjacent each other, and
   the laminated soft magnetic plates (7) have spacers (74g) between each two yoke portions (74) being adjacent each other.
6. The electric machine according to claim 1:
   wherein the stator core (2U) has ring-shaped soft magnetic plates (7) laminated to the direction (AX);
   the rotor core (4) has a ring-shaped soft magnetic plates (7) laminated to the direction (AX); and
   the ring-shaped stator winding (3U) is accommodated between the left stator teeth (21L) and the right stator teeth (21R) of the stator core (2U).
7. The electric machine according to claim 1:
   wherein the stator (1) has star-connected three phase windings (3U, 3V and 3W), which is a stator winding of a single-phase transverse flux motor each; and
   the three stator windings (3U, 3V and 3W) are driven by a three-phase inverter (500) having three legs consisting of three half bridges.
8. The electric machine according to claim 1:
   wherein the stator (100) has even number of AC phase windings (301-306), which is an AC stator winding of a single-phase transverse flux motor each;
   each pair (301 and 304, 302 and 305, and 303 and 306) of the phase windings (301-306) is driven by each of full bridge inverters (80A-803);
   the stator (100) has even number of DC windings (501-506), which is a DC stator winding of a single-phase transverse flux motor each; and
   each DC windings (501-506) is connected in series to each other.
9. The electric machine according to claim 1:
   wherein the stator (100) has even number of AC phase windings (301-306), which is an AC stator winding of a single-phase transverse flux motor each;
   each pair (301 and 304, 302 and 305, and 303 and 306) of the phase windings (301-306) is driven by each of half bridge inverters (801A-803A);
   the stator (100) has even number of DC windings (501-506), which is a DC stator winding of a single-phase transverse flux motor each; and
   each DC windings (501-506) is connected in series to each other.
10. The electric machine according to claim 9:
    wherein each phase AC current with sinusoidal waveform is supplied to each AC phase winding (301-306).
11. The electric machine according to claim 1:
    wherein the rotor teeth (41L, 41R) have short-circuited windings (300) wound around rear portions (212L, 212R) of the rotor teeth.

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