JP2016082664A - Permanent magnet synchronous machine capable of switching number of rotor magnetic poles - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a permanent magnet synchronous machine capable of switching the number of rotor magnetic poles, which suppresses losses and manufacturing costs and has both an excellent torque/weight ratio and a wide speed range.SOLUTION: Core poles 51, 53, 54, 56 that a magnetic salient pole forms are disposed at an axis-d position 180 electrical degrees apart from magnet poles 52, 55 that a permanent magnet forms. The axis-d position of a rotor is occupied by either the magnet poles or the core poles, the core poles being half or double the magnet poles. The number of stator magnetic poles is equal to the total of the magnet poles and core poles. The number of rotor magnetic poles composed of the magnet poles and the core poles is changed by the polarity alteration of the core poles. A field current or axis-d magnetizing current magnetizes the core poles that are electromagnetically juxtaposed with respect to the magnet poles.SELECTED DRAWING: Figure 5

Description

The present invention relates to a permanent magnet synchronous machine suitable for variable speed applications, and more particularly to a permanent magnet synchronous machine capable of switching the number of rotor poles.

A vehicular rotating electrical machine requires a reduction in weight. Since the output / weight ratio is improved by increasing the speed, rotating electrical machines for vehicles such as an engine starter / generator (ISG), an alternator and a traction motor generally have a very wide speed range.

Permanent magnet synchronous machines (PMSM) are used in many applications because the torque / weight ratio at low speed (referred to as low speed torque / weight) and efficiency are superior to other rotating electrical machines. However, this PMSM is essentially not suitable for vehicle applications that require a wide speed range. This is because the back electromotive force (back EMF) of the stator winding has a problem (back EMF problem) that exceeds the inverter voltage at high speed.

The back EMF of PMSM is reduced by the weak magnetic flux method in which a part of the magnet magnetic flux is canceled by the d-axis current. However, the d-axis current has a problem that efficiency is lowered because it is necessary to form a weak magnetic field in the d-axis magnetic path that penetrates the permanent magnet that is regarded as a vacuum. Furthermore, the d-axis current must be limited to avoid permanent demagnetization of the permanent magnet. For this reason, generally, an alternator or ISG employs a field coil instead of a permanent magnet, and a traction motor often employs an induction motor.

Improvement of alternator or ISG is required to improve vehicle fuel efficiency. For example, the alternator can improve fuel consumption by stopping power generation when braking the vehicle. However, since the field coil of the conventional alternator has a very large inductance, there is a problem that power generation cannot be stopped quickly during vehicle braking.

Similarly, by realizing the idling stop operation, the ISG can realize fuel efficiency improvement. However, an ISG having a field coil has a problem that the engine cannot be started quickly because the field magnetic flux cannot be increased rapidly when the engine is started. After all, it is understood that the permanent magnet synchronous machine (PMSM) as a vehicular rotating electrical machine has a back EMF problem, and the field coil synchronous machine (FCSM) as a vehicular rotating electrical machine has an inductance problem of a field coil. .

In order to improve the back EMF of the PMSM, a winding number switching PMSM and a pole number switching PMSM have been proposed. Patent Documents 1 and 2 propose a pole number conversion PMSM that reverses the polarity of some permanent magnet poles of a rotor. However, the pole number conversion PMSM requires an inverter that generates a very large d-axis pulse current for reversing the polarity of the permanent magnet. Furthermore, a stator pole number conversion circuit that changes the number of stator magnetic poles simultaneously with the polarity reversal of the permanent magnet is required. These inverter and stator pole number conversion circuits increase manufacturing costs and circuit losses.

Patent Document 3 filed by the present applicant proposes a pole number switching PMSM having two core poles between two magnet poles having different polarities. The magnet pole means a permanent magnet pole, and the core pole means a magnetic salient pole. The two core poles are arranged at the q-axis position, and the magnet pole is arranged at the d-axis position. In order to switch the number of stator poles, a double ratio stator pole number conversion circuit is employed. However, this pole switching PMSM also increases manufacturing costs and circuit losses.

JP 2013-034317 A JP 2013-183515 A Japanese Patent Application Laid-Open No. 2014-039446

One object of the present invention is to provide a rotor pole number switching type permanent magnet synchronous machine that realizes an excellent torque / weight ratio and a wide speed range while suppressing an increase in loss and manufacturing cost. The permanent magnet synchronous machine of the present invention can be used in applications such as washing machines, industrial machines, and robots in addition to mobile applications such as automobiles. Another object of the present invention is to provide an engine starter generator motor that can suppress the adverse effects of back EMF. Another object of the present invention is to provide a vehicular AC generator capable of suppressing adverse effects caused by inductance of field coils.

The rotor has a core pole formed by soft magnetic salient poles and a magnet pole formed by permanent magnets. The core pole that generates the d-axis magnetic flux or the field magnetic flux has a specific arrangement with respect to the magnet pole that generates the magnetic flux. The core pole is disposed at the next d-axis position that is 180 degrees away from the d-axis position where the magnet pole is disposed. In other words, the d-axis position of the rotor is occupied by either the magnet pole or the core pole. The core pole is half or twice the magnet pole. The number of stator magnetic poles formed by the stator winding is always equal to the sum of the magnet pole and the core pole. The number of rotor magnetic poles constituted by the magnet pole and the core pole is substantially changed by changing the polarity of the core pole.

The permanent magnet synchronous machine of the present invention has a 6-pole mode and a 2-pole mode. The 2-pole mode has a rotor pole number which is substantially 1/3 of the 6-pole mode. According to the 6-pole mode in which the number of stator magnetic poles matches the number of rotor magnetic poles, the back EMF of the stator winding increases. Therefore, torque or power generation capacity increases. According to the two-pole mode in which the number of stator magnetic poles does not match the number of rotor magnetic poles, the back EMF of the stator winding is reduced. Therefore, operation in a wide speed range is possible.

The polarity of the core pole is changed by reversing the energization direction of the d-axis current of the stator winding or the field current of the field coil. The rotor magnetic flux flowing through the core pole is mainly constituted by a d-axis magnetic flux formed by a d-axis current or a field magnetic flux formed by a field current.

The permanent magnet constituting the magnet pole can be regarded as a vacuum electromagnetically. Therefore, the magnet pole reduces the inductance of the field coil. This allows for a rapid increase in field current.

In the flux weakening method, since the d-axis magnetic field that penetrates a permanent magnet that can be regarded as a vacuum electromagnetically must be weakened, it is necessary to increase the d-axis current. On the other hand, according to the present invention, since the polarity of the core pole arranged magnetically in parallel with the magnet pole having the permanent magnet is reversed, the required d-axis current can be relatively reduced. Further, it is possible to prevent the permanent magnet from being permanently demagnetized by the d-axis current for changing the polarity of the core pole.

Other advantages of the present invention are described below. In variable speed applications such as for vehicles, it is rare that the maximum rotor flux is required. Therefore, it is uneconomical to equip the rotor with many permanent magnets for rare operating conditions (high torque conditions) such as engine starting. According to the present invention, since the number of expensive permanent magnets can be reduced, the manufacturing cost is reduced.

According to one preferred embodiment, the two core poles are arranged between two magnet poles having different polarities. According to another preferred embodiment, two magnet poles having different polarities are arranged between the two core poles.

According to another preferred embodiment, a Landel rotor is employed. According to this Landel rotor, the field coil is wound around the Landel rotor core. Therefore, this synchronous machine has the characteristics of both a conventional field coil synchronous machine (FCSM) and a conventional permanent magnet synchronous machine (PMSM). According to this aspect, since the magnet pole reduces the inductance of the field winding, the field current can be rapidly increased.

According to another preferred embodiment, the magnet pole is fixed to the claw-shaped core of the Landel rotor core. Preferably, the claw-shaped core has a circumferential width (electrical angle of 540 degrees) that is about three times that of the prior art. Thereby, the rigidity of the nail-like core is improved.

According to another preferred embodiment, the claw-shaped core has one magnet pole fixed between the two core poles. The N-pole permanent magnet is fixed to the center of the odd-numbered claw-shaped core in the circumferential direction, and the S-pole permanent magnet is fixed to the center of the even-numbered claw-shaped core in the circumferential direction. Thereby, the rotor pole number switching FCSM that can avoid a complicated rotor structure can be realized.

According to another preferred embodiment, the claw-shaped core has one core pole disposed between two magnet poles. Two N-pole permanent magnets are fixed to both ends in the circumferential direction of the odd-numbered claw-shaped core, and two S-pole permanent magnets are fixed to both circumferential ends of the even-numbered claw-shaped core. Thereby, the rotor pole number switching FCSM that can avoid a complicated rotor structure can be realized.

According to another preferred embodiment, the rotor pole number switching FCSM is employed as an alternator. According to another preferred embodiment, this rotor pole number switching FCSM is adopted as an ISG. Since the inductance of the field coil is reduced by the magnet pole, the field current can be suddenly changed.

According to another preferred embodiment, the field coil of the Landel rotor has a first coil and a second coil. According to the series mode, a field current in the first direction is passed through two coils connected in series through a series diode. According to the parallel mode of inverting the field current, the series diode is cut off, the parallel diode is turned on, and the two coils are connected in parallel.

Since the rotor pole number switching FCSM originally has a field current direction reversal circuit, series-parallel switching of two coils can be realized by adding three more diodes. Preferably, three diodes are fixed to the rotor core. The parallel connection of the two coils reduces the field coil inductance to 1/4. It is possible to shorten the time required for power generation braking of the alternator and ISG engine start.

According to another preferred embodiment, the permanent magnet of the magnet pole is fixed to a cylindrical rotor core having a multi-flux barrier structure. Multi-flux barrier structures are well known for synchronous reluctance motors (SynRM). Each flux barrier is extended in a direction that increases the ratio (Ld / Lq) of the d-axis inductance Ld and the q-axis inductance of the rotor core. Generally, each flux barrier is formed by an arc-shaped groove. In other words, each flux barrier is extended in a direction connecting two adjacent core poles and extended in a direction connecting two adjacent magnet poles. Thereby, harmful q + axis inductance Lq can be reduced. In order to reinforce the centrifugal resistance of the rotor core, it is possible to inject a resin into the flux barrier.

According to another preferred embodiment, when the generator is required to stop generating power, the total amount of core magnetic flux is made approximately equal to the total amount of magnet magnetic flux in the two-pole mode. This mode is called a power generation stop mode. According to this power generation stop mode, the power generation voltage of the stator winding induced by the difference between the total amount of core magnetic flux and the total amount of magnet magnetic flux is less than the battery voltage. Thereby, overcharging of the battery can be prevented well despite the rotor having a permanent magnet.

According to another preferred embodiment, two three-phase windings, two inverters and one bidirectional switch are provided. The first inverter is connected to the first three-phase stator winding, and the second inverter is connected to the second three-phase stator winding. One phase winding of the first three-phase winding and one phase winding of the second three-phase winding are connected through one bidirectional switch. The back EMFs of these two phase windings preferably have substantially opposite phases.

When this bidirectional switch is turned off, the two inverters are connected in parallel to the DC power supply, which is called six-phase operation. According to this six-phase operation, the number of turns of the stator winding can be substantially reduced, so that a wide speed range can be realized. Furthermore, since the stator current flows in parallel in the two stator windings, copper loss is reduced.

When this bidirectional switch is turned on, the two inverters perform two-phase operation in opposite directions. Since the four legs of the two inverters are operated, this is called four-phase operation. According to this four-phase operation, since the first three-phase winding and the second three-phase winding are substantially connected in series, the motor torque (back EMF) increases. This 4-phase / 6-phase switching type inverter circuit is described in Japanese Patent Application No. 2014-123242 filed by the present applicant. By providing this four-phase / 6-phase switching type inverter circuit, the low speed torque and speed range of the rotor pole number switching type permanent magnet synchronous machine of the present invention can be further improved.

FIG. 1 is a schematic diagram showing a Landell type ISG. FIG. 2 is a wiring diagram showing an inverter and a field current control circuit. FIG. 3 is a schematic wiring diagram showing the 6-pole mode. FIG. 4 is a schematic wiring diagram showing a two-pole mode. FIG. 5 is a side view of the Landell rotor core. FIG. 6 is a development view of the rotor magnetic pole in the circumferential direction. FIG. 7 is a schematic diagram for explaining each mode implemented by controlling the field current. FIG. 8 is a wiring diagram schematically showing the 6-pole mode. FIG. 9 is a wiring diagram schematically showing the two-pole mode. FIG. 10 is a circumferential development view showing the rotor magnetic poles. FIG. 11 is a schematic diagram for explaining each mode executed by controlling the field current. FIG. 12 is a wiring diagram showing a series-parallel switching circuit of field coils. FIG. 13 is a schematic radial cross-sectional view showing a rotor of a rotor pole number conversion type ISG. FIG. 14 is a schematic radial cross-sectional view of the rotor. FIG. 15 is a schematic diagram for explaining each mode. FIG. 16 is a schematic radial cross-sectional view showing a rotor of a rotor pole number conversion type ISG. FIG. 17 is a schematic diagram for explaining each mode. FIG. 18 is a wiring diagram showing a stator winding and an inverter.

First Embodiment A first embodiment is described below. FIG. 1 is a schematic diagram showing a Landell type ISG. The stator 1 has a stator winding 2 wound around a cylindrical stator core 7. The stator winding 2 has coil ends 2A and 2B. The Landel type rotor core 8 constitutes a Landel type rotor together with the field coil 9. The field coil 9 is surrounded by the left core and the right core of the rotor core 8.

The soft magnetic left core includes a boss 80, a pole 81, and a claw-shaped core 82. The boss 80 is fitted on the rotary shaft 6. A plurality of pole portions 81 protrude radially outward from the boss portion 80. The claw-shaped cores 82 that individually extend in the axial direction from the tip of the pole portion 81 face the inner peripheral surface of the stator core 7 with a small air gap interposed therebetween.

Similarly, the soft magnetic right core includes a boss portion 83, a pole portion 84, and a claw-shaped core 85. The boss 83 is fitted on the rotary shaft 6. The plurality of pole portions 84 protrude radially outward from the boss portion 83. The claw-shaped cores 85 that individually extend in the axial direction from the tip of the pole portion 84 face the inner peripheral surface of the stator core 7 with a small air gap interposed therebetween.

The three-phase inverter 3 supplies a stator current to the stator winding 2. The field current control circuit 11 supplies a field current to the field coil 9 through a brush and a slip ring (not shown). The controller 4 controls the inverter 3 and the field current control circuit 11.

FIG. 2 is a wiring diagram showing the inverter 3 and the field current control circuit 11. The stator winding 2 comprises a U-phase winding 2U, a V-phase winding 2V and a W-phase winding 2W which are connected in a star shape. The inverter 3 includes a U-phase leg 3U, a V-phase leg 3V, and a W-phase leg 3W. The U-phase leg 3U is connected to the U-phase winding 2U, the V-phase leg 3V is connected to the V-phase winding 2V, and the W-phase leg 3W is connected to the W-phase winding 2W. A field current control circuit 11 composed of an H bridge controls the amount and direction of the field current flowing through the field coil 9.

The controller 4 has a 6-pole mode and a 2-pole mode. The 6-pole mode in which 6N (N is an integer) rotor magnetic poles are formed is employed at least in the engine starting operation. The two-pole mode in which 2N rotor magnetic poles are substantially formed is employed at least in high-speed power generation operation. The stator winding 2 always forms 6N stator poles. In other words, the stator 1 has an electrical angle equal to N × 180 degrees.

FIG. 3 is a schematic wiring diagram showing the 6-pole mode, and FIG. 4 is a schematic wiring diagram showing the 2-pole mode. U-phase winding 2U has six U-phase conductor portions 21U-26U connected in series. The U-phase conductor portions 21U-26U are arranged substantially 180 degrees apart from each other. V-phase winding 2V has six V-phase conductor portions 21V-26V connected in series. The V-phase conductor portions 21V-26V are arranged at an electrical angle of 180 degrees from each other. W-phase winding 2W has six W-phase conductor portions 21W-26W connected in series. The W-phase conductor portions 21W-26W are arranged at an electrical angle of 180 degrees from each other.

FIG. 3 shows an example of the back electromotive force (back EMF) of the U-phase conductor portion 21U-26U in the 6-pole mode. According to this six-pole mode, the six U-phase conductor portions 21U-26U generate counter electromotive forces U1, U2, U3, U4, U5 and U6 in the same direction, so that the U-phase winding 2U has a high counter electromotive force. Is generated. Similarly, the V-phase winding 2V and the W-phase winding 2W also generate high back electromotive force.

FIG. 4 shows an example of the back electromotive force (back EMF) of the U-phase conductor portion 21U-26U in the bipolar mode. According to this two-pole mode, the counter electromotive forces U1, U3, U4, and U6 of the U-phase conductor portions 21U, 23U, 24U, and 26U are opposite to the counter-electromotive forces U2 and U5 of the U-phase conductor portions 22U and 25U. Become. The counter electromotive force of the U-phase winding 2U is the difference between the sum of the four conductor voltages U1, U3, U4, and U6 and the sum of the two conductor voltages U2 and U5. Therefore, the counter electromotive force of the U-phase winding 2U is greatly reduced. Similarly, the back electromotive force of the V-phase winding 2V and the W-phase winding 2W is also greatly reduced.

FIG. 5 is a side view of the Landel-type rotor core 8. The rotor core 8 has 12 rotor magnetic poles. The left core has two pole portions 81 separated by a spatial angle of 180 degrees. The right core also has two pole portions 84 that are 180 degrees apart from each other. The claw-like core 82 extends from the pole portion 81 in the axial direction. The claw-shaped core 85 extends from the pole portion 82 in the axial direction and in the opposite direction to the claw-shaped core 85. The claw-shaped cores 82 and 85 each have a circumferential width (space angle) of approximately 90 degrees and are alternately arranged in the circumferential direction.

The claw-shaped core 82 has two core poles 54 and 56 formed on both sides in the circumferential direction and one magnet pole 55 formed between the two core poles 54 and 56. The magnet pole 55 is fixed to a groove formed in the central portion 820 in the circumferential direction of the claw-shaped core 82. The outer peripheral surface of the magnet pole 55 made of a neodymium magnet is magnetized to the N pole.

Similarly, the claw-shaped core 85 has two core poles 51 and 53 formed on both sides in the circumferential direction and one magnet pole 52 formed between the two core poles 51 and 53. The magnet pole 52 is fixed to a groove formed in the circumferential central portion 850 of the claw-shaped core 85. The outer peripheral surface of the magnet pole 52 made of a neodymium magnet is magnetized to the S pole.

FIG. 6 is a circumferential development of the rotor magnetic poles 51-56. Core poles 54 and 56 and magnet pole 52 are disposed on the d-axis of the rotor. Core poles 51 and 53 and a magnet pole 55 are arranged on the d + axis of the rotor. The electrical angle between the d− axis and the d + axis is 180 degrees. The axial width of the stator core 7 is substantially equal to the axial width Wf of the magnetic poles 51-56.

FIG. 7 is a schematic diagram for explaining each mode. Each mode is implemented by controlling the field current. The magnet poles 52 and 55 each generate a magnet magnetic flux Fm. Each of the core poles 51, 53-54 and 56 generates a field magnetic flux Ff.

The magnetic flux arrangement pattern 101 shows a dipole mode. By causing the field current to flow in the first direction, the core poles 51 and 53 become S poles, and the core poles 54 and 56 become N poles. As a result, the magnetic poles 51-53 substantially form one S pole, and the magnetic poles 54-56 substantially form one N pole. Eventually, the six magnetic poles 51-56 substantially constitute two rotor magnetic poles. According to this two-pole mode, the spatial frequency of the rotor magnetic field is reduced, so that the iron loss of the stator core 7 is reduced.

The magnetic flux array pattern 102 indicates a power generation stop mode that is an example of a two-pole mode. By reducing the field current, the field flux Ff is about half of the magnet flux Fm. Thereby, the back electromotive force (generated voltage) of each phase winding 3U, 3V, and 3W becomes substantially zero, respectively. In other words, according to this power generation stop mode, the difference between the total magnetic flux of the core pole and the total magnetic flux of the magnet pole is such that the generated voltage induced in each phase winding 2U, 2V and 2W is less than the battery voltage. The magnetic current is controlled. Thereby, although a permanent magnet synchronous machine is used, the overcharge of a battery can be prevented. According to this power generation stop mode, the magnetic flux arrangement pattern 102 has a substantially sinusoidal shape, so that the harmonic iron loss of the stator core 7 is reduced.

When the field current cannot be controlled due to a failure of the field current control circuit 11 or the like, the magnet magnetic flux cannot be canceled by the core magnetic flux, so that the counter electromotive force (generated voltage) generated in the stator winding 2 increases. However, it is possible to prevent overcharging of the battery by increasing the current consumption of the battery.

The magnetic flux array pattern 103 shows a 6-pole mode. By causing the field current to flow in the opposite direction, the core poles 51 and 53 become N poles, and the core poles 54 and 56 become S poles. Thereby, the magnetic poles 51-56 alternately form six magnetic poles. Since each conductor portion of the stator winding 2 has a stator pole pitch equal to the rotor pole pitch in the six-pole mode, the torque is greatly increased.

According to the ISG of this embodiment, the engine starting torque can be increased by starting the engine in the 6-pole mode. By carrying out high-speed power generation in the two-pole mode, it is possible to realize stoppage of power generation and reduction of iron loss despite using permanent magnets.

By using the permanent magnet, a part of the rotor magnetic flux required for starting the engine can be generated without applying a field current. Furthermore, since the inductance of the field coil can be reduced by the area of the magnetic path occupied by the magnet pole, the remainder of the rotor magnetic flux required for starting the engine can be secured quickly.

Furthermore, according to the two-pole mode executed after the engine is started, an increase in the field magnetic flux for the torque assist operation and the dynamic braking operation can be accelerated. That is, since the inductance of the field coil is reduced by the permanent magnet, the field magnetic flux for the torque assist operation and the dynamic braking operation can be rapidly increased.

An auxiliary permanent magnet can be fixed in the gap between the two claw-like cores 82 and 85 adjacent to each other. According to one example, the auxiliary permanent magnet magnetizes the claw-shaped core 82 in the direction of magnetizing the south pole and the claw-shaped core 85 in the direction of magnetizing the north pole. Thereby, at the time of engine starting, the time for obtaining the field current value necessary for magnetizing the core poles 51 and 53 to the N pole and magnetizing the core poles 54 and 56 to the S pole can be shortened. As a result, the engine start time can be shortened.

In order to further shorten the engine start time, the number of turns of the field coil 9 is preferably reduced as compared with the conventional alternator. It is preferable to maintain the 6-pole mode of the rotor by energizing part of the field current during idle stop. For example, a field current of 40% of the rated maximum current value is supplied to the field coil 9 during the idle stop period. The copper loss of the field coil 9 during the idle stop period is about 16%. The d-axis current of the inverter 3 can be controlled when the mode is changed. The d-axis current is energized in a direction that assists in reversing the polarity of the core pole due to the mode change.

Variations of the first embodiment will be described below. This modification is characterized in that the ISG of the first embodiment is used as an alternator. The inverter 3 shown in FIGS. 1 and 2 is changed to a three-phase diode rectifier. The adoption of the 6-pole mode improves the low-speed power generation performance of this alternator. As a result, the alternator can be reduced in size and weight. By adopting the two-pole mode, it is possible to stop power generation and reduce iron loss despite using a permanent magnet.

Furthermore, according to this modification, the generated current can be greatly increased by changing from the 2-pole mode to the 6-pole mode during vehicle braking. Similarly, by adopting the power generation stop mode during vehicle acceleration, vehicle acceleration can be promoted. By reducing the inductance of the field coil, the control of the field current for stopping the power generation can be completed more quickly than the conventional alternator.

Second Embodiment A second embodiment is described below. This second embodiment is characterized in that the positions of the core pole and magnet pole of the ISG of the first embodiment are reversed. FIG. 8 is a wiring diagram schematically showing the 6-pole mode, and FIG. 9 is a wiring diagram schematically showing the 2-pole mode.

FIG. 8 shows an example of the back electromotive force of the U-phase conductor portion 21U-26U in the 6-pole mode. This 6-pole mode is essentially the same as the 6-pole mode of the first embodiment shown in FIG. Each phase winding 2U, 2V and 2W generates similar back electromotive force.

FIG. 9 shows an example of the back electromotive force of the U-phase conductor portion 21U-26U in the bipolar mode. The counter electromotive forces U1, U3, U4, and U6 of the U-phase conductor portions 21U, 23U, 24U, and 26U are in the same direction as in the 6-pole mode. The counter electromotive forces U2 and U5 of the U-phase conductor portions 22U and 25U are opposite to the 6-pole mode. Eventually, the generated voltage of the U-phase winding 2U is greatly reduced. The generated voltage of the V-phase winding 2V and the W-phase winding 2W is also reduced.

FIG. 10 is a development in the circumferential direction showing the rotor magnetic poles 51-56. In order to reduce the number of permanent magnets, the magnet poles 53 and 54 are constituted by one permanent magnet 202. Similarly, the magnet poles 51 and 56 are also composed of one permanent magnet 201. Since the permanent magnets 201 and 202 are held in a wedge shape on the claw-like cores 82 and 85, the permanent magnets 201 and 202 can be prevented from falling off despite high speed rotation (see FIG. 11).

FIG. 11 is a schematic diagram for explaining each mode. The magnet poles 51, 53, 54 and 56 generate a magnet magnetic flux Fm. The core poles 52 and 55 generate a field magnetic flux Ff. The magnetic flux arrangement pattern 101 shows a dipole mode. Since the core pole 52 becomes the S pole and the core pole 55 becomes the N pole, the magnetic poles 51-53 substantially form one S pole, and the magnetic poles 54-56 substantially form one N pole. Eventually, the six magnetic poles 51-56 substantially constitute two rotor magnetic poles. Since the spatial frequency of the rotor magnetic field is reduced, the iron loss of the stator core 7 is reduced.

The magnetic flux array pattern 103 shows a 6-pole mode. Since the core pole 52 is an N pole and the core pole 55 is an S pole, the six magnetic poles 51 to 56 form six rotor magnetic poles. The stator winding 2 has a stator magnetic pole pitch equal to the rotor magnetic pole pitch of this 6-pole mode. The ISG of the second embodiment has the same effects as the ISG of the first embodiment.

Third Embodiment A third embodiment will be described with reference to FIG. This embodiment is added to the field coil 9 of the first embodiment or the second embodiment already described. The field coil 9 includes a first coil 91 and a second coil 92 wound in the same direction on the boss portions 80 and 83 shown in FIG. A series diode 12 and a parallel diode 13-14 are fixed to the rotor core 8. A field current control circuit 11 comprising an H bridge is connected to the field coil 9 through two slip ring / brush pairs 15 and 16.

The anode of the series diode 12 is connected to one end of the first coil 91, and the other end of the first coil 91 is connected to the leg 11 </ b> A of the H bridge 11. The cathode of the series diode 12 is connected to one end of the second coil 92, and the other end of the second coil 92 is connected to the leg 11 </ b> B of the H bridge 11. The anode of the parallel diode 13 is connected to the leg 11B, and the cathode of the parallel diode 13 is connected to the anode of the series diode. The anode of the parallel diode 14 is connected to the cathode of the series diode, and the cathode of the parallel diode 14 is connected to the leg 11A.

The leg 11A has an upper arm switch 111 and a lower arm switch 114 connected in series. The leg 11B has an upper arm switch 113 and a lower arm switch 112 connected in series. The four switches 111-114 are constituted by MOS transistors having antiparallel diodes.

According to the 6-pole mode executed for starting the engine, the switches 113 and 114 are turned on and the switches 111 and 112 are turned off. The field current flows in parallel to the first coil 91 and the second coil 92 through the parallel diodes 13 and 14. Since the inductance of the field coil 9 becomes 1/4, the field current increases rapidly.

When switch 113 and switch 114 are turned off, the field current for the 6-pole mode is stopped. The residual magnetic energy of the first coil 91 and the second coil 92 causes a current to flow through the battery through the antiparallel diodes of the switches 111 and 112, respectively. Thereby, at the end of the 6-pole mode, the field current rapidly decays.

According to the two-pole mode executed for the power generation operation, the switches 111 and 112 are turned on and the switches 113 and 114 are turned off. Thereby, the field current flows through the first coil 91 and the second coil 92 connected in series through the series diode 12. Since the number of turns of the field coil 9 is doubled, the field current can be reduced.

By switching one of the switches 111 and 112 by PWM switching, the field current in the two-pole mode is controlled and the generated current is adjusted. When the switch 111 is turned off, the residual magnetic energy of the first coil 91 and the second coil 92 generates a freewheeling current that circulates through the series diode 12, the switch 112, and the switch 114. When the switch 112 is turned off, the residual magnetic energy of the first coil 91 and the second coil 92 generates a freewheeling current that circulates through the series diode 12, the switch 111, and the switch 113.

The field current control circuit of this embodiment is optimally used with the Landell-type ISG of the first and second embodiments that originally have an H-bridge 11 for reversing the direction of the field current. . However, a conventional ISG or alternator that does not change the number of rotor poles can adopt this field current control circuit.

Fourth Embodiment A fourth embodiment is described below. This embodiment is applied to a normal permanent magnet synchronous machine (PMSM). FIG. 13 is a schematic axial sectional view showing a rotor of a rotor pole number conversion type traction motor. The stator is the same as the stator 1 shown in FIG.

The rotor 8A includes a laminated steel core rotor core 800 fitted to the rotary shaft 6 and a permanent magnet fixed to the outer peripheral portion of the cylindrical rotor core 800. The outer peripheral surface of the rotor core 8A faces the inner peripheral surface of the stator core 7 with a small gap therebetween. Therefore, this synchronous machine has the same structure as an ordinary permanent magnet type synchronous motor having an inner rotor structure. A three-phase inverter 3 that supplies power to the stator winding 2 is controlled by a controller 4.

FIG. 14 is a schematic radial cross-sectional view of the rotor 8A. Two sets of rotor magnetic poles, each consisting of six rotor magnetic poles 51-56, are formed in order at the d + axis position and the d − axis position of the outer peripheral surface of the rotor core 800. Two magnet poles 52 that are 180 degrees apart from each other have an S pole. Two magnet poles 55 that are 180 degrees apart from each other have N poles. The space angle between the magnet pole 52 and the magnet pole 55 is 90 degrees. The magnet poles 52 and 55 are made of permanent magnets fixed in magnet grooves in which the outer peripheral surface of the rotor core 800 is recessed. The magnet poles 52 and 55 may be embedded in the rotor core 800.

Core poles 56 and 51 are disposed between magnet poles 55 and 52. Core poles 53 and 54 are disposed between magnet poles 52 and 55. Eventually, a total of 12 rotor magnetic poles are formed at the d + axis position and the d− axis position of the rotor 8A. The rotor core 800 has multi-flux barriers 801 and 802. Each of the multi-flux barriers 801 and 802 includes a plurality of arc-shaped grooves called flux barriers. In other words, the rotor core 800 has substantially the same multi-flux barrier structure as a conventional synchronous synchronous reluctance motor.

The multi-flux barrier 801 is formed to reduce the d-axis magnetic resistance between the adjacent core poles 53 and 54 and the d-axis magnetic resistance between the adjacent magnet poles 52 and 55. The multi-flux barrier 802 is formed to reduce the d-axis magnetic resistance between the core poles 56 and 51 adjacent to each other and the d-axis magnetic resistance between the magnet poles 55 and 52 adjacent to each other.

The spatial angle between adjacent multiflux barriers 801 and 802 is 90 degrees. Each of the multiflux barriers 801 and 802 is formed to increase the q-axis magnetic resistance between the q + axis and the q− axis adjacent to each other. In order to reduce adverse effects due to q-axis inductance, permanent magnets arranged on the d + axis and the d− axis may be extended in the adjacent q-axis direction. Eventually, the rotor 8A gives the stator winding 2 a large d-axis inductance Ld and a small q-axis inductance Lq.

The stator winding 2 forms 12 stator magnetic poles as in the first embodiment. By reversing the direction of the d-axis current Id included in the stator current supplied from the inverter 3 to the stator winding 2, the polarities of the core poles 51, 53-54 and 56 are changed.

According to the 6-pole mode, one core pole and one magnet pole adjacent to each other have opposite polarities. According to the two-pole mode, one core pole and one magnet pole adjacent to each other have the same polarity. The 6-pole mode is employed when the engine is started, for example. The bipolar mode is employed at high speed, for example. Details of the 6-pole mode and the 2-pole mode are essentially the same as in the first embodiment.

FIG. 15 is a schematic diagram for explaining each mode. The S-pole magnet pole 52 and the N-pole magnet pole 55 generate a magnet magnetic flux Fm. The core poles 51, 53-54 and 56, which are magnetized by the d-axis current and become the N pole or S pole, generate a d-axis magnetic flux Fd. The magnetic flux pattern of FIG. 15 is essentially the same as the magnetic flux pattern of FIG. However, the core poles 51, 53-54 and 56 shown in FIG. 15 generate a d-axis magnetic flux Fd instead of the field magnetic flux Ff (see FIG. 7). The details of each mode shown in FIG. 15 are essentially the same as the details of each mode shown in FIG. However, since the d-axis current magnetizes the core poles 51, 53, 54, and 56 without passing through a permanent magnet that is regarded as a vacuum, the d-axis current for polarity change can be reduced.

Fifth Embodiment A fifth embodiment is described below. This embodiment is applied to a normal permanent magnet synchronous machine (PMSM). FIG. 16 is a schematic radial cross-sectional view showing a rotor of a rotor pole number conversion traction motor. The stator is essentially the same as the stator 1 shown in FIG. However, the core pole and the magnet pole shown in FIG. 16 are disposed at positions opposite to the core pole and the magnet pole shown in FIG.

N-pole magnet poles 51 and 53 are arranged with a core pole 52 in between. The S-pole magnet poles 54 and 56 are arranged with the core pole 55 interposed therebetween. The core pole 52 is disposed at a spatial angle of 90 degrees from the core pole 55. The magnet poles 52 and 55 are fixed to grooves in which the outer peripheral surface of the rotor core 800 is recessed. Eventually, two sets of rotor magnetic poles 51-56 are arranged at the d + axis position and the d− axis position of the rotor 8A. The rotor core 800 has multi-flux barriers 801 and 802.

The multi-flux barrier 801 is formed to reduce the d-axis magnetic resistance between the magnet poles 51 and 56 adjacent to each other and the d-axis magnetic resistance between the core poles 55 and 52 adjacent to each other. The multi-flux barrier 802 is formed to reduce the d-axis magnetic resistance between the magnet poles 53 and 54 adjacent to each other and the d-axis magnetic resistance between the magnet poles 52 and 55 adjacent to each other.

The multiflux barriers 801 and 802 increase the q-axis magnetoresistance between the q + axis and the q− axis adjacent to each other. Eventually, the magnetic salient pole type rotor 8A provides the stator winding 2 with a large d-axis inductance Ld and a small q-axis inductance Lq. The permanent magnets constituting the magnet poles 52 and 54 may be embedded in the rotor core 8A.

The stator winding forms a 12-pole stator pole. By reversing the direction of the d-axis current Id included in the stator current, the polarities of the four core poles 52 and 55 are reversed. According to the 6-pole mode, the core pole has the opposite polarity to the adjacent magnet pole. According to the two-pole mode, the core pole has the same polarity as the adjacent magnet pole. The 6-pole mode is employed when the engine is started, for example. The bipolar mode is employed at high speed, for example.

FIG. 17 is a schematic diagram for explaining each mode. However, each permanent magnet is accommodated in a magnet accommodation hole formed in the rotor core 800. In other words, the rotor 8A has a known embedded magnet structure. Both end portions of each magnet accommodation hole in which no permanent magnet is accommodated constitute a flux barrier 59.

The S magnetic poles 54 and 56 and the N magnetic poles 51 and 53 generate a magnetic flux Fm. The core poles 52 and 54 generate a d-axis magnetic flux Fd. The magnetic flux pattern shown in FIG. 17 is essentially the same as the magnetic flux pattern shown in FIG. However, the core poles 52 and 55 shown in FIG. 17 generate a d-axis magnetic flux Fd instead of the field magnetic flux Ff shown in FIG. Each mode shown in FIG. 17 is essentially the same as each mode shown in FIG.

Sixth Embodiment A sixth embodiment will be described with reference to FIG. This embodiment is made to solve the serious problem that the ISG must generate a strong engine starting torque. In view of the fact that it is not yet easy to realize both the torque characteristics and the power generation characteristics required by ISG only by switching the number of rotor poles described above.

FIG. 18 is a wiring diagram showing the stator winding 2 and the inverter 3. The stator winding 2 is composed of a first three-phase winding 2A and a second three-phase winding 2B. The three-phase winding 2A includes a U-phase winding 2U1, a V-phase winding 2V1, and a W-phase winding 2W1 that are star-connected. The three-phase winding 2B includes a -U phase winding 2U2, a -V phase winding 2V2, and a -W phase winding 2W2 connected in a star shape.

The U-phase winding 2U1 and the -U-phase winding 2U2 generate U-phase voltages having opposite phases. The V-phase winding 2V1 and the -V-phase winding 2V2 generate opposite-phase V-phase voltages. W-phase winding 2W1 and -W-phase winding 2W2 generate opposite-phase W-phase voltages. In other words, the stator winding 2 is composed of six-phase windings whose phases are shifted by 60 degrees in electrical angle.

A triac 15 that is an AC switch connects the output terminal of the W-phase winding 2W1 and the -W-phase winding 2W2. The inverter 3 includes a first inverter 3A connected to the first three-phase winding 2A and a second inverter 3B connected to the second three-phase winding 2B.

The first inverter 3A includes a U-phase switching leg 3U1 and a V-phase switching leg 3V1 configured by MOS transistors, and a W-phase diode leg 3W1 configured by a diode. The second inverter 3A includes a -U phase switching leg 3U2 and a -V phase switching leg 3V2 configured by MOS transistors, and a -W phase diode leg 3W2 configured by diodes.

U-phase leg 3U1 is connected to U-phase winding 2U1, V-phase leg 3V1 is connected to V-phase winding 2V1, and W-phase leg 3W1 is connected to W-phase leg 2W1. -U-phase leg 3U2 is connected to -U-phase winding 2U2, -V-phase leg 3V2 is connected to -V-phase winding 2V2, and -W-phase leg 3W2 is connected to -W-phase leg 2W2. After all, the inverter 3 is composed of four-phase switching legs 3U1, 3V1, 3U2 and 3V2 and two-phase diode legs 3W1 and 3W2.

The operation of the inverter 3 and the triac 15 will be described below.
The triac 15 is turned on when the engine that needs to generate a large torque is started. Next, the four-phase switching legs 3U1, 3V1, 3U2, and 3V2 supply the stator winding 2 with a four-phase current having a substantially sinusoidal waveform. This mode is called a four-phase mode. Thereby, the U-phase current IU flows through the U-phase windings 2U1 and 2U2, and the V-phase current IV flows through the V-phase windings 2V1 and 2V2. As a result, a W-phase current IW flows through the W-phase winding 2W1 and the -W-phase winding 2W2. Eventually, since the two three-phase windings 2A and 2B are connected in series, a large torque can be generated by the four-phase inverter.

The triac 15 is turned off at high speed. As a result, the three-phase windings 2A and 2B generate a generated current or torque independently of each other. This mode is called the 6-phase mode. Copper loss of the stator windings 2A and 2B is reduced.

According to this embodiment, since the number of turns of the stator winding 2 can be switched by one bidirectional switch, the problem that the back EMF excessively increases during high-speed rotation by the permanent magnet is improved. As a result, it is possible to reduce the loss due to energization of the field current or the d-axis current for reducing the generated voltage described above. Furthermore, since the number of turns of the stator winding can be increased when the engine is started, the low speed torque can be improved. Other bidirectional switches can be used instead of the triac.

The stator winding switching method referred to as the 4-phase / 6-phase switching method can be used for variable speed synchronous generators such as alternators other than ISG and variable speed synchronous motors such as traction motors. It can also be employed in induction generators. When used as a generator, the inverter 3 can be composed of a 6-phase diode leg. When used as a motor, the inverter 3 can be composed of a six-phase switching leg.

Each of the above embodiments can be employed in an axial gap type rotating electric machine or a linear motor instead of the radial gap type rotating electric machine.

Claims (12)

In the rotor pole number switching type permanent magnet synchronous machine having a magnet pole and a core pole formed in the rotor core, the magnet pole is formed by a permanent magnet, and the core pole is formed by a magnetic salient pole formed in the rotor core.
The stator core that faces the rotor core has stator windings that form a number of stator poles equal to the total number of magnet poles and core poles, and current control means that switches the number of rotor poles by changing the polarity of the core poles. And
The current control means switches the mode between the 6-pole mode in which the number of rotor magnetic poles is equal to the number of stator magnetic poles and the 2-pole mode in which the number of rotor magnetic poles is substantially 1/3 of the number of stator magnetic poles. A rotor pole number switching type permanent magnet synchronous machine characterized by being implemented by modification.   2. The rotor pole number switching type permanent magnet synchronous machine according to claim 1, wherein two core poles arranged between two magnet poles having different polarities have different polarities.   2. The rotor pole number switching type permanent magnet synchronous machine according to claim 1, wherein two magnet poles disposed between two core poles having different polarities have different polarities. The current control means changes the polarity of the core pole by switching the direction of the field current supplied to the field coil wound around the Landell rotor core,
The permanent magnet synchronous machine according to claim 3, wherein the permanent magnet for forming the core pole is fixed to a claw-shaped core of the Landel rotor core.   The rotor pole number switching type permanent magnet synchronous machine according to claim 4, wherein the claw-shaped core has one magnet pole fixed between two core poles.   The rotor pole number switching type permanent magnet synchronous machine according to claim 4, wherein the claw-shaped core has one core pole formed between two magnet poles.   The field coil includes a first coil and a second coil wound around the Landel-type rotor core, and a series diode that connects the first field coil and the second field coil in series with respect to a field current flowing in the first direction. 5. The rotor pole-switching permanent magnet synchronous machine according to claim 4, further comprising two parallel diodes for connecting the first field coil and the second field coil in parallel to a field current flowing in a direction opposite to the first direction. .   2. The rotor pole number switching type permanent magnet synchronous machine according to claim 1, wherein the current control means changes the polarity of the core pole by switching the energization direction of the d-axis current energized to the stator winding.   The cylindrical rotor core reduces both the d-axis magnetoresistance between two adjacent core poles having opposite polarities and the d-axis magnetoresistance between two adjacent magnet poles having opposite polarities. The rotor pole number switching type permanent magnet synchronous machine according to claim 8, further comprising a multi-flux barrier formed in a direction to be turned.   The current control means has a power generation stop mode that disables the supply of power generation current from the stator winding to the outside by generating a total amount of core magnetic flux that is substantially equal to the total magnetic flux of the magnet magnet in the two-pole mode. The rotor pole number switching type permanent magnet synchronous machine according to Item 1.   The current control means connects the first inverter and the second inverter individually connected to the two three-phase windings constituting the stator winding, and one leg of the first inverter and one leg of the second inverter. The rotor pole number switching type permanent magnet synchronous machine according to claim 1, further comprising: a bidirectional switch configured to switch, and a controller that switches between a four-phase mode and a six-phase mode by switching the bidirectional switch. The two legs connected by the bidirectional switch are constituted by diode legs,
12. The rotor pole number switching type permanent controller according to claim 11, wherein the controller executes a torque generating operation by selecting the four-phase mode at the start of rotation, and executes a power generation operation by selecting the six-phase mode at the time of high speed rotation. Magnet synchronous machine.