WO2006117865A1

WO2006117865A1 - Motor for electric power steering and electric power steering system using the same

Info

Publication number: WO2006117865A1
Application number: PCT/JP2005/008185
Authority: WO
Inventors: Masashi Kitamura; Fumio Tajima; Noriaki Hino; Shoichi Kawamata; Takashi Ishigami; Osamu Koizumi; Toshiyuki Innami; Mitsuaki Mirumachi
Original assignee: Hitachi, Ltd.
Priority date: 2005-04-28
Filing date: 2005-04-28
Publication date: 2006-11-09
Also published as: JPWO2006117865A1; JP4865704B2

Abstract

A motor for an electric power steering enabling a reduction in fluctuation of torque, capable of generating a large torque, and excellent in both a reduction in fluctuation of torque and generation of large torque and an electric power steering system using the motor for the electric power steering. A stator (110) comprises a stator core (112) and multi-phase stator coils (114) assembled in the stator core (112). The stator core (112) is formed by connecting a plurality of divided core pieces to each other. Each of the plurality of divided core pieces comprises a T-shaped core piece formed by integrating one of the core pieces provided by dividing a back core part into a plurality of parts in a circumferential direction with the core piece corresponding to the teeth part of the core piece. The stator core part (112) is formed by connecting the plurality of T-shaped core pieces to each other in the circumferential direction. The stator coils (114) are stored in slot parts, and wrapped around the teeth parts of the back core pieces with a concentrated winding.

Description

Specification

Electric power steering motor and electric power steering system using the same

Technical field

The present invention relates to an electric power steering motor and an electric power steering system using the same.

Background art

In conventional electric power steering motors, for example, as described in JP-A-2001-275325 and JP-A-2003-250254, there is a need to reduce torque pulsation. Known.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2001-275325

Patent Document 2: Japanese Patent Laid-Open No. 2003-250254

Disclosure of the invention

Problems to be solved by the invention

[0004] Efforts have been made to reduce torque pulsation, but it has not been sufficiently reduced.

One of the problems to be solved is that it is necessary to further reduce torque pulsation and generate large torque for the power steering motor. For example, if the steering wheel is rotated while the vehicle is stopped or running very slowly (the so-called “stationary state”), the friction between the steering wheel and the ground is large. Must generate a large torque. In addition, the larger the displacement, the heavier the vehicle body, and the greater the output torque of the power steering motor that is required at the time of stationary.

[0005] That is, an object of the present invention is to use a power steering motor capable of reducing torque pulsation and generating large torque and excellent in both reducing torque pulsation and generating large torque, and using the same. An object is to provide an electric power steering system.

Means for solving the problem

[0006] In the embodiments described below, it is desirable to use a power steering motor. B. Solve various problems. These will be described in the following embodiments.

[0007] The present invention provides a power steering motor excellent in both reduction of torque pulsation and generation of large torque, and an electric power steering system using the same.

[0008] The most representative feature of the present invention is that the stator core is formed by joining a plurality of divided core pieces, and the divided core pieces have a knock core portion in the circumferential direction. A T-shaped core piece in which one piece of a core piece obtained by dividing the core piece into a plurality of pieces and a core piece corresponding to the tea score portion are integrated, and the stator core has the T-shaped core piece in the circumferential direction. The stator coil is housed in the slot portion and wound around the tea score portion with a concentrated rod, and the number of magnets (number of poles) and the number of slot portions are determined. There are 8 poles, 9 slots, 10 poles, 9 slots, or 10 poles, 12 slots.

The invention's effect

[0009] According to the present invention, both the reduction of torque pulsation and the generation of large torque are excellent.

Brief Description of Drawings

FIG. 1 is a system configuration diagram showing a configuration of an electric power steering using an electric power steering motor of the present embodiment.

FIG. 2 is a cross-sectional view showing a configuration of an electric power steering motor according to the present embodiment.

FIG. 3 is a cross-sectional view taken along the line AA in FIG.

FIG. 4 is an explanatory diagram of the relationship between the number of poles P and the number of slots S of a synchronous motor.

FIG. 5 is an explanatory diagram of measured values of cogging torque in the electric power steering motor of the present embodiment.

FIG. 6 is a connection diagram of a stator coil in the electric power steering motor of the present embodiment.

FIG. 7 is a side view showing a connection state of a stator coil in the electric power steering motor of the present embodiment.

FIG. 8 is a functional block diagram showing a configuration of a control device for controlling the electric power steering motor of the present embodiment. FIG. 9 is a circuit diagram showing a circuit configuration of a control device for controlling an electric power steering motor according to an embodiment of the present invention.

FIG. 10 is a perspective view showing the structure of a control device for controlling the electric power steering motor of the present embodiment.

Explanation of symbols

[0011] 110 ... stator

112 ... Stator core

114 ... Stator coil

112 (U1 +), 112 (U1-), 112 (U2 +), 112 (U2—), 112 (V1 +), 112 (V1-), 112 (V2 +), 112 (V2-), 112 ( W1 +), 112 (W1—), 112 (W2 +), 112 (W2—)… T-shaped core piece

130 Rotor

132 ··· Rotor core

134… Magnet

150 ... frame

BEST MODE FOR CARRYING OUT THE INVENTION

The most representative and best embodiment of the electric power steering motor according to the present invention is as follows.

[0013] That is, an electric power steering motor that is driven by multi-phase AC power and outputs a steering torque, the frame, a stator fixed to the frame, and the stator via a gap. The stator includes a stator core and a multi-phase stator coil incorporated in the stator core, and the stator core is configured to couple a plurality of divided core pieces. The plurality of core pieces divided as described above correspond to one piece of core pieces obtained by dividing the back core portion into a plurality of pieces in the circumferential direction and the tea score portion. A T-shaped core piece integrally formed with the core piece, and the stator core is formed by connecting a plurality of the T-shaped core pieces in the circumferential direction; Between the teeth core portions which contact and slot portion is formed, together with the stator coil is accommodated in the slot unit, The rotor is wound around the tea score portion in a concentrated manner, and the rotor is an electric power steering motor including a rotor core and a plurality of magnets fixed to the outer peripheral surface of the rotor core.

[0014] The most representative and best embodiment of the electric power steering system according to the present invention is as follows.

[0015] That is, the in-vehicle power source and the in-vehicle power source power also convert DC power supplied via the wire harness into multi-phase AC power, and control its output in accordance with torque applied to the steering. An electric power steering system having a control device and an electric power steering motor that is driven by the AC power supplied from the control device power and outputs a steering torque. A stator, a stator fixed to the frame, and a rotor opposed to the stator via a gap. The stator includes a stator core and a multi-phase stator coil incorporated in the stator core. The stator core is formed by joining a plurality of divided core pieces. The plurality of divided core pieces are obtained by integrating one piece of a core piece obtained by dividing the back core portion into a plurality of pieces in the circumferential direction and a core piece corresponding to the tea score portion. The stator core is formed by connecting a plurality of the T-shaped core pieces in the circumferential direction, and a slot portion is formed between the tea core portions adjacent to the stator core. The stator coil is housed in the slot portion and wound around the tea score portion in a concentrated manner, and the rotor includes a rotor core and a plurality of stator cores fixed to the outer peripheral surface of the rotor core. There are 8 poles-9 slots or 10 poles-9 slots or 10 poles-12 slots between the number of magnets (number of poles) and the number of slots. In the electric power steering system that there is.

Hereinafter, the configuration and operation of an electric power steering motor according to an embodiment of the present invention will be described with reference to FIGS.

First, the system configuration of an electric power steering using the electric power steering motor of this embodiment will be described with reference to FIG.

FIG. 1 shows an electric power steer using the electric power steering motor of this embodiment. FIG.

[0019] When the steering ST is rotated, the rotational driving force is decelerated by the manual steering gear STG via the rod RO, transmitted to the left and right tie rods TR1, T2, and transmitted to the left and right wheels WH1, WH2. Steering the left and right wheels WH1, WH2.

[0020] The EPS motor 100 according to the present embodiment is attached in the vicinity of the rod RO of the steering ST, and transmits the driving force to the rod RO via the gear GE. A torque sensor TS is attached to the rod RO, and the rotational driving force (torque) applied to the steering ST is detected. Based on the output of the torque sensor TS, the control device 200 controls the energization current to the motor 100 so that the output torque of the EPS motor 100 becomes the target torque. The power for the control device 200 and the EPS motor 100 is supplied from the battery BA.

[0021] It should be noted that the above configuration is also applied to a rack-type power steering equipped with a force EPS motor near the rack and pion gear, which is a column-type power steering equipped with an EPS motor near the steering. The EPS motor 100 in the example can be applied similarly.

[0022] First, the energy balance of the EPS motor 100, the control device 200, and the battery BA will be described. For example, when a battery BA that is a power source of the EPS motor 100 is 12V, 80A, the output is about 1 kW (960 W). Battery BA and control device 200 are connected by a wire harness, and even if the resistance is reduced by using a thick wire harness (in consideration of ease of towing, a wire with a conductor cross-sectional area of about 8 square mm is used. If a large current flows as described above, the power consumption of the wire harness is about 200W. Further, even if the internal resistance value of the control device 200 itself is reduced, the power consumption is about 200 to 300 W. Therefore, about half of the power (about lkW) that can be output from the battery BA is consumed by the wire harness and the control device 200, and the power that can be consumed by the EPS motor 100 is halved.

[0023] As a conventionally used EPS motor, a 4-pole 12-slot permanent magnet type distributed winding brushless motor is known. This EPS motor is used in vehicles with small displacement (total weight of small vehicles). Currently, hydraulic power steering devices have been put to practical use in vehicles with large displacements (large vehicle gross weight). Such a large displacement (large vehicle gross weight) It was practically impossible to use a conventional 4-pole, 12-slot permanent magnet brushless motor for a vehicle with a displacement of 1.8 L or more (total displacement of 1.5 L or more, for example). The reason for this is that for a vehicle with a large displacement (large total vehicle weight), the vehicle weight is too large in the stationary state, so the friction between the steering and the ground is too great, and there is also a force that makes the stationary impossible. is there.

[0024] In the conventional 4-pole 12-slot permanent-magnet distributed winding brushless motor, the reason why the torque at low speed cannot be increased is that, due to the above-mentioned energy balance, the copper loss of the motor is large. By not flowing in. Therefore, first, in this embodiment, it is necessary to use an EPS motor with a small copper loss.

[0025] Further, as a characteristic required for the EPS motor, it is necessary to suppress the torque pulsation to 100 to 200 mNm in both amplitude values. In this regard, a 4-pole 12-slot brushless motor also has a problem that torque pulsation increases, and it is essential to cancel the torque pulsation by means such as rotor skew. On the other hand, in a 4-pole 12-slot brushless motor, since the cogging torque due to the inner-diameter roundness error of the stator is large, even if the inner-diameter roundness error force S is small, the cogging torque becomes relatively large. Therefore, secondly, in the present embodiment, it is necessary to use an EPS motor having a small cogging torque due to an error in the inner circularity of the stator.

[0026] Further, the problem of noise is raised. In particular, in column-type power steering, the EPS motor is placed in the passenger compartment, so the problem of noise becomes significant. Vehicles with large displacements are classified as high-end vehicles, and therefore quiet interiors are required. Here, EPS motor noise is generally evaluated by its tone. In short, it is required that the sound is not harsh or very small. Specifically, the timbre in question may be an audible or squeezed sound that involves electromagnetic sounds in the tens to hundreds of Hz band. Therefore, thirdly, it is necessary to use a low-noise EPS motor that reduces these noises.

[0027] The EPS motor according to this embodiment achieves these problems.

Next, the configuration of the electric power steering motor of this embodiment will be described with reference to FIG. 2 and FIG. FIG. 2 is a cross-sectional view showing the configuration of the electric power steering motor of the present embodiment. FIG. 3 is a cross-sectional view taken along the line AA in FIG. Fig. 3 (A) shows an overall cross-sectional view, and Fig. 3 (B) shows a cross-sectional view of the main part.

[0030] Electric power steering motor (hereinafter referred to as EPS motor) 100 is a surface magnet type synchronous motor including a stator 110 and a rotor 130 rotatably supported inside the stator 110. . The EPS motor 100 is equipped with a battery-powered battery, such as a 14-volt power supply (battery output voltage is 12 volts), a 24-volt power supply or a 42-volt power supply (battery output voltage 36 volts), or 48 volts. It is driven by the power supplied from the system power supply.

The stator 110 includes a stator core 112 made of a magnetic material in which silicon steel plates are laminated, and a stator coil 114 held in a slot of the stator core 112. As will be described later with reference to FIG. 3, the stator core 112 is composed of twelve T-shaped teeth-integrated divided back cores, which are integrated into a stator core 112. T-shaped teeth A stator coil 114 is wound in advance on each of the teeth portions of the integral split back core. The stator coil 114 is wound in a concentrated winding system and in an aligned winding system.

[0032] By making the stator coil 114 a concentrated rod, the coil end length of the stator coil 114 can be shortened. Thereby, the length of the EPS motor 100 in the rotation axis direction can be shortened. Further, since the length of the coil end of the stator coil 114 can be shortened, the resistance of the stator coil 114 can be reduced, and the temperature rise of the motor can be suppressed. In addition, by using concentrated winding, the stator coil can be wound in advance on the teeth portion with an alignment rod, so that the space factor of the stator coil with respect to the status lot formed between adjacent teeth can be improved. In addition, since the coil end length can be shortened compared to the case of the distribution wrinkle, the overall length of the coil can be shortened. Accordingly, since the coil resistance can be reduced, the copper loss of the motor can be reduced. For the above reasons, the proportion of energy consumed by copper loss in the input energy to the motor can be reduced, and the efficiency of output torque with respect to the input energy can be improved. The maximum output torque at low speed (low rotation) can be improved by 30 to 40%. The result is a large displacement car It can be put to practical use as an EPS motor for both (large vehicle weight vehicles).

[0033] The EPS motor is driven by the power source mounted on the vehicle as described above. The above power supplies often have low output voltage. The switching elements constituting the inverter between the power supply terminals, the motor, and other means for connecting the current supply circuit constitute an equivalent series circuit. In the circuit, the sum of the terminal voltages of the respective circuit components is between the power supply terminals. Since it becomes a voltage, the terminal voltage of the motor for supplying current to the motor is lowered. In order to secure the current flowing into the motor in such a situation, it is extremely important to keep the copper loss of the motor low. From this point of view, it is desirable that the power source mounted on the vehicle should be concentrated on the stator coil 114 with many low voltage systems of 50 volts or less. This is especially important when using a 12-volt power supply.

[0034] Further, the EPS motor is required to be miniaturized for any force that may be placed near the steering column or near the rack and pion. In addition, it is necessary to fix the stator winding with a miniaturized structure, and it is also important that the winding operation is easy. Compared with the distribution rod, the concentrated rod is easier to perform the winding operation and the fixing operation.

[0035] The coil end of the stator coil 114 is molded. EPS motors sometimes cut the inside of the stator again after assembling the stator part where it is desirable to suppress torque fluctuations such as cogging torque. Such machining generates cutting dust. It is necessary to prevent this cutting powder from entering the coil end of the stator coil, and a coil end mold is desirable. The coil end refers to a portion where the stator coil 114 protrudes in the axial direction from both axial ends of the stator core 112. In this embodiment, the mold resin covering the coil end of the stator coil 114 and the force frame with a space between the frame 150, the front flange 152F and the rear flange 152R are in contact with the mold. You may fill with rosin. By doing so, heat generated from the stator coil 114 can be directly transmitted from the coil end to the frame 150, the front flange 152F and the rear flange 152R via the mold grease, and can be radiated to the outside. The temperature rise of the stator coil 114 can be reduced compared to the case where heat is transferred.

[0036] The stator coil 114 is composed of a U-phase, a V-phase, and a W-phase three-phase force, each having a plurality of units. Coil force composed. As will be described later with reference to FIG. 4, the plurality of unit coils are connected for each of the three phases by a connection ring 116 provided on the left side of the drawing.

[0037] A large torque is required for the EPS motor. For example, if the steering wheel (NANDLE) is rotated quickly when the car is in a driving stop condition or a driving condition that is close to stopping, the motor requires a large torque due to the frictional resistance between the steering wheel and the ground. . At this time, a large current is supplied to the stator coil. It is very important to use the connection ring 116 in order to safely supply such a large current and to reduce the heat generated by the current. By supplying current to the stator coil through the connection ring 116, the connection resistance can be reduced, and the voltage drop due to copper loss can be suppressed. This makes it easy to supply a large current. In addition, the current rise time constant force accompanying the operation of the inverter element is effective.

[0038] Stator core 112 and stator coil 114 are integrally molded by a resin (having electrical insulation), and are integrally formed to constitute a stator SubAssy. The integrally formed stator SubAssy is molded while being press-fitted and fixed inside a cylindrical frame 150 made of metal such as aluminum. The integrally formed stator SubAssy may be molded with the stator coil 114 incorporated in the stator core 112 and then press-fitted into the frame 1.

[0039] Various vibrations are applied to EPS mounted on automobiles. In addition, an impact from the wheel is applied. Moreover, it is used in a state where the temperature change is large. An ambient temperature of minus 40 degrees Celsius is also conceivable, and the temperature of the motor body may be more than 100 degrees Celsius due to temperature rise. In addition, water must be prevented from entering the motor. In order to fix the stator to the yoke 150 under such conditions, at least the outer periphery of the stator core of the cylindrical frame is not provided with holes other than screw holes, and the stator portion (SubAssy ) Is desirable. Further, after press-fitting, it may be screwed from the outer periphery of the frame. In addition to press-fitting, it is desirable to make a stop.

[0040] The rotor 130 is provided on a rotor core 132 having a magnetic strength obtained by laminating silicon steel plates, a magnet 134 that is a plurality of permanent magnets fixed to the surface of the rotor core 132 by an adhesive, and an outer periphery of the magnet 134. With magnet cover 136 that also has non-magnetic physical strength Yes. The magnet 134 is a rare earth magnet such as Nd—Fe—B. The rotor core 132 is fixed to the shaft 138. A plurality of magnets 134 are fixed to the surface of the rotor core 132 by an adhesive, and the outer periphery of the magnet 134 is covered with a magnet cover 136 to prevent the magnet 134 from scattering! The magnet cover 136 is made of stainless steel (commonly known as S US). ,.

[0041] At one end of the cylindrical frame 150, a front flange 152F is provided. Frame 150 and front flange 152F are fixed by bolt B1. A rear flange 152R is press-fitted into the other end of the frame 150. Bearings 154F and 154R are attached to the front flange 152F and rear flange 152R, respectively. These bearings 154F, 154R [from here, the shaft 138 and this shaft 138] is fixedly supported by the stator 110.

[0042] The front flange 152F is provided with an annular protrusion (or extension). The projecting portion of the front flange 152F projects in the axial direction, and extends from the side surface of the front flange 152F on the coil end side to the coil end side. When the front flange 152F is fixed to the frame 150, the front end of the protruding portion of the front flange 152F is inserted into the gap formed between the mold material at the coil end on the front flange 152F side and the frame 150. It has become. In order to improve heat dissipation from the coil end, it is preferable that the protrusion of the front flange 152F is in close contact with the mold material of the coil end on the front flange 152F side.

[0043] The rear flange 152R is provided with a cylindrical recess. The recess of the rear flange 152R is concentric with the central axis of the shaft 138 and enters the axially inner side (stator core 112 side) of the axial end of the frame 150. The tip of the recess of the rear flange 152R extends to the inner diameter side of the coil end on the rear flange 152R side, and faces the coil end on the rear flange 152R side in the radial direction. A bearing 154R is held at the tip of the recess of the rear flange 152R. The axial end of the shaft 138 on the rear flange 152R side extends further axially outward (opposite to the rotor core 132 side) than the bearing 154R, and is slightly closer to or near the opening of the recess in the rear flange 152R. It reaches the position protruding outward in the axial direction. A resolver 156 is disposed in a space formed between the inner peripheral surface of the recess of the rear flange 152R and the outer peripheral surface of the shaft 138. The resolver 156 includes a resolver stator 156S and a resolver rotor 156R, and is located on the axially outer side (opposite to the rotor core 132 side) than the bearing 154R. The resolver rotor 156R is fixed to one end portion (left end portion in the drawing) of the shaft 138 with a nut N1. The resolver stator 156S is fixed to the inner peripheral side of the recess of the rear flange 152R by fixing the resolver holding plate 156B to the rear flange 152R with a screw SC1, and is opposed to the resolver rotor 156R through a gap. The resolver stator 156S and the resolver rotor 156R constitute a resolver 156, and the rotation of the resolver rotor 156R is detected by the resolver stator 156S, whereby the positions of the plurality of magnets 134 can be detected. More specifically, the resolver includes a resolver rotor 156R whose outer peripheral surface is uneven (for example, an elliptical shape or a petal shape), two output coils (electrically shifted by 90 °), and an excitation coil. And a resolver stator 156S wound around a core. When an AC voltage is applied to the excitation coil, the AC voltage corresponding to the change in the length of the gap between the resolver rotor 156R and the resolver stator 156S has a phase difference proportional to the rotation angle. It occurs with. In this way, the resolver is for detecting two output voltages with a phase difference. The magnetic pole position of the rotor 130 can be detected by obtaining the phase angle from the phase difference between the two detected output voltages. A rear holder 158 is attached to the outer periphery of the rear flange 152R so as to cover the resolver 156.

[0045] Electric power is supplied to the U-phase, V-phase, and W-phase connected by the connection ring 116 via the power cable 162. The power cable 162 is attached to the frame 150 by a grommet 164. The magnetic pole position signal detected from the resolver stator 156S is taken out by the signal cable 166. The signal cable 1 66 is attached to the rear Honoreda 158 by a grommet 168. A part of the connection ring 116 and the power cable 1 is molded with a coil end by a molding material.

Next, the configuration of the stator 110 and the rotor 130 will be described more specifically based on FIG. FIG. 3 is a view taken along arrows A—A in FIG. Fig. 3 (B) is an enlarged cross-sectional view of the main part of Fig. 3 (A). is there. The same reference numerals as those in FIG. 2 denote the same parts.

[0047] In this example, 12 T-shaped teeth integrated split back cores 112 (U1 +), 112 (U 1-), 112 (U2 +), 112 (U2-), 112 (V1 +) , 112 (V1−), 112 (V2 +), 112 (V2−), 112 (W1 +), 112 (W1−), 112 (W2 +), 112 (W2−) force. Teeth integrated split back cores 112 (U1 +),..., 112 (W2—) each have a structure in which a thin magnetic plate such as a silicon steel plate is punched out by press forming and laminated.

[0048] Teeth integrated split back core 112 (U1 +), ···, 112 (W2—) has teeth on the teeth, respectively, stator coils 114 (U1 +), 114 (U1—), 114 (U2 + ), 114 (U2—), 114 (V1 +), 114 (V1-), 114 (V2 +), 114 (V2—), 114 (W1 +), 114 (W1—), 114 (W2 +), 114 (W2—) has been wound in a concentrated manner.

Here, the stator coil 114 (U1 +) and the stator coil 114 (U1−) are wound so that the direction of the current flowing through the coils is opposite. Similarly, the stator coil 114 (U2 +) and the stator coil 114 (U2−) are wound so that the direction of the current flowing through the coils is opposite. Further, the stator coil 114 (U1 +) and the stator coil 114 (U 2 +) are wound so that the directions of currents flowing through the coils are the same direction. Similarly, the stator coil 114 (U1—) and the stator coil 114 (U2—) are wound so that the direction of the current flowing through the coils is the same direction. Stator coils 114 (VI +), 11 4 (V1-), 114 (V2 +), 114 (V2—) current flow direction, and stator coils 114 (W1 +), 114 (W1—), 114 ( The relationship between the current flow directions of W2 +) and 114 (W2−) is the same as in the U phase.

[0050] After winding the stator coils 114 (U1 +),..., 114 (W2—) on the teeth integrated split back core 112 (U1 +),. , Teeth integrated split back core 112 (U1 +), ..., 112 (W2—), press-fitting the recesses formed on the circumferential end face and the mating projections to assemble the stator 110 Complete. Next, the stator core 112 and the stator coil 114 are integrally molded with a thermosetting resin MR in a state where a plurality of locations on the outer peripheral side of the knock core 112B are press-fitted into the inner peripheral side of the frame 150, thereby forming a stator SubAssy. . In this embodiment, the stator coil 114 is incorporated in the stator core 112. This is the force described in the case where the stator core 112 and the stator coil 114 are molded together with the stator core 112 and the stator coil 114 being integrally molded. Then, the stator core 112 may be press-fitted into the frame 150.

[0051] When molding with the molding material, the coil end portion of the stator core 114 and the stator coil 114 in which the axial end force of the stator core 112 protrudes in the axial direction is surrounded by a jig and a frame 150 (not shown). The jig (not shown) is attached to the structure composed of the stator core 112, the stator core 112, and the frame 150, and a fluid mold material is injected into the structure surrounded by the jig (not shown) and the frame 150, Fill the mold end with the mold material and solidify the mold material by filling the gap between the stator core 112, the stator coil 114, the stator coil 114, the gap between the stator core 112 and the stator coil 114, and the gap between the stator core 112 and the frame 150. When the mold material is solidified, the jig not shown is removed.

[0052] The inner peripheral surface of the molded stator SubAssy, that is, the tip of the teeth part of the teeth integrated split back core 112 (U1 +),..., 112 (W2—), and the diameter of the rotor 130 Cutting is performed on the surface side facing the direction as necessary. Thereby, variation in the gap length between the stator 110 and the rotor 130 can be reduced, and the inner diameter roundness of the stator 110 can be further improved. Further, by integrally molding by molding, heat dissipation of heat generated by energizing the stator coil 114 can be improved as compared with the case where the molding is not performed. Further, the stator coil can be prevented from vibrating by molding. In addition, the cogging torque based on the inner diameter roundness can be reduced by cutting the inner diameter after molding. By reducing the cogging torque, the steering feel of the steering can be improved.

[0053] For example, when the gap length between the outer periphery of the rotor core of the rotor 130 and the inner periphery of the teeth of the stator 110 is 3 mm (3000 m), the manufacturing error of the back core 112B, the manufacturing of the teeth 1 12T The roundness of the inner diameter is about ± 30 m due to errors and assembly errors when press fitting the knock core 112B and teeth 112T. This roundness is equivalent to 1% of the gap (= 30 μm / 3000 μm), so the roundness of the inner diameter makes the cogging torque Occurs. However, the cogging torque based on the inner diameter roundness can be reduced by cutting the inner diameter after molding. By reducing the cogging torque, the steering feel of the steering can be improved.

[0054] A convex portion 150T is formed inside the frame 150. A recess 112B02 is formed on the outer periphery of the back core 112B so as to correspond to the protrusion 150T. The convex portion 150T and the concave portion 112B02 constitute an engaging portion IP having mutually different curvatures, and are formed continuously in the axial direction and provided at eight intervals in the circumferential direction. Being The engaging part also serves as a press-fitting part. That is, when fixing the stator core 112 to the frame 150, the concave portion 112B02 of the back core 112B is press-fitted into the convex portion 150T of the frame 150 so that the projecting end surface of the convex portion 150T of the engaging portion and the bottom surface of the concave portion 112B02 are pressed against each other. Thus, in this embodiment, the stator core 112 is fixed to the frame 150 by partial press-fitting. Due to the press-fitting, a fine gap is formed between the frame 150 and the stator core 112. In the present embodiment, when the stator core 112 and the stator coil 114 are molded with the molding material MR, the gap formed between the frame 150 and the stator core 112 is filled with the molding material RM at the same time. The engaging portion also serves as a detent portion for preventing the stator core 112 from rotating in the circumferential direction with respect to the frame 150.

As described above, in this embodiment, since the stator core 112 is partially press-fitted into the frame 150, the slip between the frame 150 and the stator core 112 can be increased and the rigidity of the frame 150 can be decreased. Thereby, in the present embodiment, the noise attenuation effect between the frame 150 and the stator core 112 can be improved. In the present embodiment, since the gap between the frame 150 and the stator core 112 is filled with the molding material, the noise attenuation effect can be further improved.

[0056] It should be noted that the convex portion 150T and the concave portion 112B02 are not in contact with each other, and both are used only as detents, and the back core 112B is not against the inner peripheral surface of the frame 150 other than the convex portion 150T and the concave portion 112B02. It may be configured to press fit the outer peripheral surface.

In addition, the stator coils 114 (U1 +), 114 (U1—) and 114 (U2 +), 114 (U2—) are arranged at symmetrical positions with respect to the center of the stator 110. That is, the stator coils 114 (U1 +) and 114 (U1-) are arranged adjacent to each other, and the stator coil 114 (U2 + ) And 114 (U2—) are also arranged adjacent to each other. Further, the stator coils 114 (U1 +) and 114 (U1—) and the stator coils 114 (U2 +) and 114 (U2—) are arranged symmetrically with respect to the center of the stator 110. That is, the broken line C passing through the center of the shaft 138—the stator coil 114 (U1 +) and the stator coil 114 (U2 +) are arranged in line symmetry, and the stator coil 114 (U1-) 114 (U2—) are arranged in line symmetry.

[0058] The stator coils 114 (VI +) and 114 (V1—) and 114 (V2 +) and 114 (V2—) are similarly arranged in line symmetry, and the stator coils 114 (W1 +) and 114 (W1— ), 114 (W2 +), 11 4 (W2−) are arranged in line symmetry.

[0059] In addition, adjacent stator coils 114 having the same phase are wound continuously by a single wire. In other words, the stator coils 114 (U1 +) and 114 (U1—) consist of two wound coils that are wound around a tooth. Yes. The stator coils 114 (U2 +) and 114 (U2—) are also wound continuously by a single wire. Stator coils 114 (VI +) and 114 (VI—), stator coils 114 (V2 +) and 114 (V2—), stator coils 114 (W1 +) and 114 (W1—), stator coils 114 (W2 +) And 114 (W2—) are also wound continuously on one line.

[0060] By arranging such a line-symmetric arrangement and winding two adjacent in-phase coils with a single wire, as described later with reference to FIG. When connecting with, the configuration of the connection ring can be simplified.

Next, the configuration of the rotor 130 will be described. The rotor 130 includes a rotor core 132 having magnetic strength and ten magnets 1 34 (134A, 134B, 134C, 134D, 134E, 134F, 134G, 134H, 1341, 13 and 13 fixed to the surface of the rotor core 132 with an adhesive. J) and a magnet cover 136 provided on the outer periphery of the magnet 134. The rotor core 1 32 is fixed to the shaft 138.

[0062] Magnet 134 has a radial direction so that its front side (side facing stator teeth 112T) is N-pole, and its back side (side bonded to rotor core 132) is S-pole. Is magnetized. Further, when the surface of the magnet 134 (the side facing the stator teeth 112T) is the S pole, the back side (the side bonded to the rotor core 132) is the N pole. Some are magnetized in the radial direction. Adjacent magnets 134 are magnetized so that the magnetized polarities alternate in the circumferential direction. For example, if the surface side of the magnet 134A is magnetized to the N pole, the S side poles of the adjacent magnets 134B and 13J are magnetized! That is, when the surface side of the magnets 134A, 134C, 134E, 134G, 1341 is magnetized to the negative pole, the surface side of the magnets 134B, 134D, 134F, 134H, 13 J is magnetized to the S pole Yes.

[0063] In addition, each of the magnets 134 has a cross-sectional shape such that the upper surface thereof, that is, the surface facing the inner peripheral side of the stator 110 is curved so that the central portion protrudes (kamaboko-shaped). Shape). The force-bump shape is a structure that is thinner in the circumferential direction than the radial thickness in the radial direction on the left and right. By adopting such a force-bump shape, the magnetic flux distribution in the gap can be made sinusoidal, and the induced voltage waveform generated by rotating the EPS motor can be made sinusoidal. Pulsation and cogging torque can be reduced. By reducing torque pulsation and cogging torque, the steering feel can be improved. It should be noted that the same effect of reducing torque pulsation and cogging torque can be obtained by controlling the magnetic force that can be applied even if a ring-shaped (cylindrical) magnet is applied to the rotor 130.

Further, the magnet 134 is divided into two in the axial direction of the motor 100. The magnet 134 divided in two may be arranged in the circumferential direction of the rotor 130 with a mechanical angle shifted by 3 to 6 degrees as necessary. In this way, the electromagnetic excitation force in a relatively low-order mode can be reduced by arranging the two-divided magnets with a mechanical angle shifted by 3 to 6 degrees. The reduction of magnetic flux utilization due to the above skew is less than a few percent, and it is not a big problem. In addition, the cogging torque can be reduced by shifting the magnet in two parts by 3 degrees with the mechanical angle to give a skew effect. Furthermore, as described above, when using a ring-shaped (cylindrical) magnet, the magnetization direction must be continuously skewed by a predetermined angle (6 degrees mechanical angle) as it advances in the axial direction. Similarly, the cogging torque can be reduced.

[0065] The rotor core 132 is formed with 10 through holes 132H having a large diameter on a concentric circle, and 5 recesses 132K having a small diameter on the inner periphery thereof. Rotor core 132 is a magnetic steel sheet It has a structure in which thin sheets of magnetic material such as are punched out by press molding and laminated.

. The recess 132K is formed by pressing a thin plate during press molding. When stacking a plurality of thin plates, the recess 132K is fitted to each other for positioning. The through hole 132H is for reducing the inertia. The outer periphery side of the magnet 134 is covered with a magnet cover 136 to prevent the magnet 134 from scattering. The knock core 112B and the rotor core 132 are simultaneously formed by press punching from the same thin plate.

[0066] As described above, the rotor 130 of this embodiment includes ten magnets 134 and has ten poles. As described above, the number of teeth 112T is twelve, and the number of slots formed between adjacent teeth is twelve. That is, the EPS motor of the present embodiment is a 10-pole 12-slot surface magnet type synchronous motor.

[0067] The stator core is composed of an annular back core and 12 teeth that are separated from the back core, and then mechanically a plurality of teeth on the knock core. A fixed configuration was also studied. It has been found that such a split tooth with a split tooth is disadvantageous in terms of the roundness of the inner diameter compared with the split knock core system with integrated teeth shown in Figs. That is, in the split tooth type split core method, a gap is required in the portion where the end of the tooth is inserted into the groove of the back core. The gap is affected by the gap. In this divided tooth type split core system, the error in the inner diameter roundness is larger than that in the divided back core system with integrated teeth. Therefore, compared with the split tooth type split core method, the tooth integrated split back core method of this embodiment has a force that can reduce the cutting amount or the inner diameter even when the inner diameter cutting is performed on the stator core. It is also possible to use no cutting.

[0068] In addition, in the split tooth type split core method, the backlash is large! /, And vibration is generated in submicron units due to the electromagnetic excitation force at the time of torque generation, which is likely to cause noise. There was found. On the other hand, in the teeth integrated split back core method of the present embodiment, the back core itself is divided! However, the combined back core has high rigidity and is stored and held in the frame, so that the stator core as a whole can be obtained. Stiffness can be increased. Therefore, since the amplitude of vibration can be reduced, the viewpoint of noise reduction is also advantageous.

[0069] As described above, the teeth integrated split back core method of this example was able to reduce vibration. As a result, noise can also be reduced. In other words, it is represented by the above-mentioned woo or thunder sound.

We could reduce the faint noise by several dB, and even when evaluating the motor noise by timbre, we were able to confirm that it was a noise level with no audible problems.

Here, the relationship between the number of poles P and the number of slots S in the synchronous motor will be described with reference to FIG.

FIG. 4 is an explanatory diagram regarding the number of poles P and the number of slots S of the synchronous motor.

[0072] In Fig. 4, the number of poles that can be used as a three-phase synchronous motor (brushless motor) when the maximum number of poles and slots is limited to 10 and 15, respectively, with hatching by horizontal lines P And the number of slots S. That is, as a three-phase synchronous motor, 2 pole 3 slot, 4 pole 3 slot, 4 pole 6 slot, 6 pole 9 slot, 8 pole 6 slot, 8 pole 9 slot, 8 pole 12 slot, 10 pole 9 slot, 10 The combination of pole 12 slots and 10 poles 15 slots is established. Among these, the 10 poles and 12 slots of the combination with left and right oblique lines are the number of poles and the number of slots of the motor according to this embodiment. The 8-pole 9-slot and 10-pole 9-slot with diagonal lines on the left will be described later. The EPS motor shown in Fig. 1 is a small motor with an outer diameter of 85φ. In such a small motor, when the number of poles N is 12 or more, the increase in the number of poles causes a manufacturing problem. Since the disadvantages are large, the illustration is omitted!

[0073] Here, 2-pole 3-slot, 4-pole 3-slot, 4-pole 6-slot, 6-pole 9-slot, 8-pole 6-slot, 8-pole 12-slot, 10-pole 15-slot motors with similar characteristics Here, a 6 pole 9 slot slot is described as a representative example.

[0074] Compared with the 6-pole 9-slot synchronous motor, the 10-pole 12-slot motor of this embodiment can increase the utilization rate of the magnetic flux. That is, in the 6-pole 9-slot synchronous motor, the winding coefficient (coil utilization factor) kw is 0.87 and the skew coefficient ks is 0.96, so the magnet flux utilization factor (kw'ks) Becomes “0.83”. On the other hand, in the 10-pole 12-slot motor of this embodiment, the winding coefficient kw is 0.93 and the skew coefficient ks is 0.99, so the utilization rate (kw'ks) of the magnetic flux is It becomes “0.92.” Therefore, the 10-pole 12-slot motor of this embodiment is preferable from the viewpoint of increasing torque because the utilization factor (kw'ks) of the magnetic flux can be increased.

[0075] The cogging torque cycle is the least common multiple of the number of poles P and the number of slots S. The period of the cogging torque in the synchronous motor in the slot is “18”. In the 10-pole 12-slot motor of this embodiment, it can be set to “60”, so the viewpoint power for reducing the cogging torque is also very significant lj.

Further, the cogging torque due to the error of the inner diameter roundness can be reduced. That is, if the cogging torque (relative value) due to the error in the roundness of the inner diameter of the 6-pole 9-slot synchronous motor is “3.7”, the 10-pole 12-slot motor of this embodiment has “2.4”. Therefore, there is a feature that is robust with respect to the cogging torque due to the error of the inner diameter roundness. In addition, in the conventional 4-pole 12-slot synchronous motor, the cogging torque due to the error in the roundness of the inner diameter is “3.0”. On the other hand, the 10-pole 12-slot motor of this embodiment also has The viewpoint power of the cogging torque due to the error in the roundness of the inner diameter is also advantageous. In other words, the combination of 10 poles and 12 slots tends to cause errors in the roundness of the inner diameter that causes cogging torque, can improve the defects of the stator core due to the split construction method, and can reduce the copper loss of the motor. The advantages of the stator core due to the construction method can be utilized. Furthermore, in this embodiment, the inner diameter of the molded stator SubAssy is cut to improve the inner diameter roundness, and further, the cogging torque due to the inner diameter roundness error can be reduced.

Here, the measured value of the cogging torque in the electric power steering motor of this embodiment will be described with reference to FIG.

[0079] Fig. 5 (A) shows the measured cogging torque (mNm) in the 360 ° range where the angle (mechanical angle) is 0 to 360 °. Fig. 5 (B) shows the peak value (mNm) of the harmonic components of the cogging torque shown in Fig. 5 (A), separated for each time order. As described above, the time order “60” is a period of cogging torque in a 10-pole 12-slot motor, and the generated cogging torque is almost zero. The time order “12” is due to variations in the amount of magnetization (field magnetic force) of the 10-pole magnet and errors in the attachment position. The time order “10” is due to variations in the teeth of the 12-slot stator (such as the roundness of the inner diameter and the fall of the teeth). As a result of improving the roundness of the inner diameter by cutting after molding, the cogging torque due to variation in teeth can be reduced to 2.6 mNm. The time order “0” is a DC component and is a so-called loss torque (friction torque generated when the rotational speed is almost zero). Loss torque can be reduced to 26.3 mNm, so even if the steering force is released, the steering force is smaller than the restoring force of the steering to return to the straight direction. There is no.

[0081] As described above, as a result of reducing each cogging torque component, the cogging torque can be reduced to about 9 mNm as shown in FIG. 5 (A). For example, if the maximum torque of an EPS motor is 4.5 Nm, the cogging torque can be reduced to 0.2% (= 9 mNm / 4.5 Nm). Also, the loss torque is as small as 0.6% (= 26.3 mNm / 4. 5 Nm).

[0082] The EPS motor 100 of the present embodiment is a motor that uses a battery (for example, output voltage 12V) as a power source. The EPS motor 100 is installed in the vicinity of the rack of the rack and pion gear that transmits the steering rotational force to the wheels in the vicinity of the steering. Therefore, it is necessary to reduce the mounting position limit force. On the other hand, a large torque is required to power assist the steering.

[0083] If you want to output the required torque with an AC servo motor that uses AC 100V as the power source, the motor current may be about 5A. However, when driving with 14V AC converted from DC14V to DCZAC as in this example, it is necessary to set the motor current to 70A to 100A in order to output the same level of torque with the same level of motor. is there. In order to pass such a large current, the diameter of the stator coil 114 needs to be large. The number of turns of the stator coil 114 is 9 to 21 T depending on the wire diameter of the stator coil 114 and the coil connection method. For example, when the diameter of the stator coil 114 is 1.8 φ, the number of turns is 9 mm. In recent vehicles, there is an electric vehicle equipped with a 42V battery, etc. In this case, the motor current can be reduced, so the number of turns of the stator coil 114 is 20 to 3 mm.

[0084] In the adjacent teeth 112 間隔, the opening interval W1 of the tip of the teeth 112T (the side facing the rotor 130) W1 (for example, the interval between the openings of the tips of the teeth 112Τ (U1—) and the teeth 112Τ (W1—)) W1 (circumferential interval between parts closest to the circumferential direction) is 1 mm. As described above, by narrowing the tooth interval, the magnetic structure of the inner periphery of the stator core 112 becomes uniform, so that the cogging torque can be reduced. Moreover, the motor Even if vibration is applied to the stator coil 114, the stator coil 114 is more linear than the interval W1, so that it is possible to prevent the stator coil 114 from falling to the rotor side from between the teeth. The interval W1 between adjacent teeth is preferably, for example, 0.5 mm to 1.5 mm which is equal to or smaller than the wire diameter of the stator coil 114. Thus, in this embodiment, the interval W1 between adjacent teeth is set to be equal to or smaller than the wire diameter of the stator coil 114.

Next, the connection relationship of the stator coils in the electric power steering motor of this embodiment will be described with reference to FIG. 6 and FIG.

FIG. 6 is a connection diagram of a stator coil in the electric power steering motor of the present embodiment. FIG. 7 is a side view showing a connection state of the stator coil in the electric power steering motor of this embodiment. FIG. 7 is a view taken along the line BB in FIG. The same reference numerals as those in FIG. 3 denote the same parts.

In FIG. 6, a coil U1 + indicates the stator coil 112T (U1 +) shown in FIG. Coils Ul—, U2 +, U2-, V1 +, VI −, V2 +, V2, W1 +, Wl—, W2 +, W2— are also the stator coils 112T (U1—), ..., 112T (W2-) is shown.

In the stator coil of this embodiment, the U phase, the V phase, and the W phase are connected as delta (Δ) connections. Each phase forms a parallel circuit. In other words, looking at the U phase, the series circuit of coil U2 + and coil U2— is connected in parallel to the series circuit of coil U1 + and coil U1—. Here, as described above, the coil U1 + and the coil U1— constitute a coil by continuously winding one wire. The same applies to the V and W phases.

The connection method can be a star connection, but by using a delta connection, the terminal voltage can be lowered as compared with the star connection. For example, when the voltage at both ends of the U-phase series-parallel circuit is E, the terminal voltage is 3E for a force star connection with E as the terminal voltage. Since the terminal voltage can be lowered, the number of turns of the coil can be increased, and a thin wire can be used. In addition, by using a parallel circuit, it is possible to use a wire with a small wire diameter, which can reduce the current flowing through each coil compared to the case where four coils are connected in series. The property is also good. This is advantageous for increasing the space factor. [0090] Next, the connection method for each of the three phases and each phase by the connection ring will be described with reference to FIG. 6 and FIG.

[0091] As shown in FIG. 6, the coils Ul-, U2-, V1 +, V2 + are connected by a connection ring CR (UV). Coils VI—, V2-, W1 +, W2 + are connected by connection ring CR (VW). Coils U1 +, U2 +, W1- and W2— are connected by a connection ring CR (UW). If connected as described above, a three-phase delta connection can be achieved.

Therefore, as shown in FIG. 7, three connection rings CR (UV), CR (VW), and CR (UW) are used. The connection rings CR (UV), CR (VW), and CR (UW) are made by bending a bus bar type connection plate into an arc shape so that a large current can flow. Each connection ring has the same shape. For example, the connection ring CR (UV) has a shape in which a small radius arc and a large radius arc are connected. The other connection rings CR (VW) and CR (UW) have the same configuration. These connection rings CR (UV), CR (VW), and CR (UW) are held by holders HI, H2, and H3 while being shifted by 120 degrees in the circumferential direction. The connection ring CR and the holders HI, H2, H3 are molded together with the coil end portion by a molding material.

On the other hand, in FIG. 7, the stator coil end portion T (U1 +) is one end portion of the stator coil 114 (U 1 +) wound around the teeth 112 (111+). The stator coil end portion T (U 1−) is one end portion of the stator coil 114 (U1−) wound around the teeth 112T (U1−). As described above, the stator coil 114 (U1 +) and the stator coil 114 (U1—) form a continuous coil with a single wire, so two coils 114 (U1 +), 1 14 For (U1−), there are two ends T (U1 +) and T (U1−). End of stator coil T (U2 +), T (U2−), T (V1 +), T (Vl−), T (V2 +), T (V2−), T (W1 +), T (Wl− ), T (W2 +), and T (W2−) are one ends of the stator coils 114 (U2 +),..., (W2 +), respectively.

[0094] Stator coil ends T (U1—), T (U2—), T (V1 +), T (V2 +)

(UV), and this connects the coils Ul—, U2—, V1 +, V2 + shown in Fig. 6 with the connection ring CR (UV). Stator coil end T (VI—), T (V2-), T (W1 +), T (W2 +) are connected by the connection ring CR (VW). —, V2-, W1 +, W2 + connection ring CR (VW) is connected It is. The stator coil ends T (W1—), T (W2-), T (U1 +), T (U2 +) are connected by the connection ring CR (UW). +, U2 +, W1-,

W2—Connection ring CR (UW) is used for connection.

Next, the configuration of a control device that controls the electric power steering motor of this embodiment will be described with reference to FIG.

FIG. 8 is a functional block diagram showing a configuration of a control device that controls the electric power steering motor of the present embodiment.

The control device 200 includes a power module 210 that functions as an inverter, and a control module 220 that controls the power module 210. The DC voltage from the battery BA is converted into a three-phase AC voltage by the power module 210 functioning as an inverter, and supplied to the stator coil 114 of the EPS motor 100.

[0098] The torque control 221 in the control module 220 calculates the torque Te from the torque Tf of the steering ST detected by the torque sensor TS and the target torque Ts, and provides PI control (P

: Proportional term, I: integral term) etc., that is, torque command, ie current command Is and rotation angle of rotor 130

Θ 1 is output.

The phase shift circuit 222 shifts and outputs the norse from the encoder E, that is, the rotor position information Θ in accordance with the rotation angle θ 1 command from the torque control circuit (ASR) 221. The sine wave 'cosine wave generator 2223 includes a resolver 156 that detects the position of the permanent magnet magnetic pole of the rotor 130, and a stator coil based on the position information Θ of the phase-shifted rotor from the phase shift circuit 222. A sine wave output is generated by shifting the induced voltage of each of the 114 windings (here, three phases). The phase shift amount may be zero.

[0099] The two-phase / three-phase conversion circuit 224 sends current commands Isa, Isb, Isc to each phase according to the current command Is from the torque control circuit (ASR) 221 and the output of the sine wave-cosine wave generator 223. Output. Each phase has its own current control system (ACR) 225A, 225B, 225C, and the current commands Isa, Isb, Isc and the current detection signals from the current detector CT are signals corresponding to the current detection signals Ifa, Ifb, Ifc. Send to 210 to control each phase current. In this case, the current of each phase combination is always formed at a position perpendicular to the field flux or shifted in phase.

[0100] The above explanation is for a 10-pole 12-slot EPS motor. Next, the 8-pole 9-slot and 10-pole 9-slot EPS motors shown in Fig. 4 with diagonal lines on the left are explained.

[0101] Compared to the 6-pole 9-slot synchronous motor, the 8-pole 9-slot and 10-pole 9-slot motors can use the magnetic flux more efficiently. That is, the utilization factor (kw'ks) of the magnetic flux in the 6-pole 9-slot synchronous motor is “0.83” as described above. On the other hand, in the 8-pole 9-slot and 10-pole 9-slot motors, the winding coefficient kw is 0.95 and the skew coefficient ks is 1.00, so the magnetic flux utilization factor (kw'ks) is “0.94”. Therefore, the 8-pole 9-slot and 10-pole 9-slot motors of this embodiment can increase the magnetic flux utilization factor (kw'ks), which is preferable from the viewpoint of increasing torque.

[0102] Also, since the cogging torque cycle is the least common multiple of the number of poles P and the number of slots S, the cycle of the cogging torque in a 6-pole 9-slot synchronous motor is "18", which is 8 poles 9 slots and 10 The motor with 9 poles can be set to “72”, so the viewpoint power to reduce the cogging torque is very significant.

[0103] Further, the cogging torque due to the error of the inner diameter roundness can be reduced. In other words, if the cogging torque (relative value) due to the error in the roundness of the inner diameter of a 6-pole 9-slot synchronous motor is "3.7", the 8-pole 9-slot and 10-pole 9-slot motors are "1.4. Therefore, there is a feature that is robust with respect to cogging torque due to an error in the roundness of the inner diameter. In other words, the combination of 8-pole 9-slot and 10-pole 9-slot can improve the defects of the stator core due to the split construction method, which tends to cause errors in the roundness of the inner diameter, which causes cogging torque, and the copper of the motor The advantage of the stator core by the split construction method that can reduce the loss can be utilized. Furthermore, the inner diameter of the molded stator SubAssy is cut to improve the inner diameter roundness, and the cogging torque due to the inner diameter roundness error can be further reduced.

[0104] In the case of the 8-pole 9-slot and 10-pole 9-slot motors, for example, in the case of the U phase, as in the 10-pole 12-slot EPS motor described in FIG. A configuration in which the series circuit of coil U2 + and coil U2− is connected in parallel to the series circuit of U1− cannot be used, and the coils of each phase must be connected in series.

[0105] 8 pole 9 slot and 10 pole 9 slot EPS motor! Next, the structure of the control device for controlling the electric power steering motor of this embodiment will be described with reference to FIGS.

FIG. 9 is a circuit diagram showing a circuit configuration of a control device that controls an electric power steering motor according to an embodiment of the present invention.

[0107] The motor control device 200 includes a power module 210, a control module 220, and a conductor module 230.

[0108] In the conductor module 230, a bus bar 230B serving as a power line is integrally formed by molding. In the figure, a thick solid line portion indicates a bus bar. In conductor module 230, common filter CF, normal filter NF, capacitor CC1, CC2, relay RY 1 power Bus bar that connects the power supply battery BA and the semiconductor switching element SSW collector terminal such as IGBT of power module 210 Are connected as shown.

[0109] Also, in the figure, the portion indicated by a double circle indicates a welded connection! For example, the four terminals of the common filter CF are connected to the bus bar terminals by welding. The two terminals of the normal filter NF, the two terminals of the ceramic capacitors CC1 and CC2, and the two terminals of the relay RY1 are also connected to the bus bar terminals by welding. Common filter CF and normal filter NF are installed to prevent radio noise.

[0110] Also, a bus bar is used for the wiring in which the motor current is supplied from the power module 210 to the motor 100. Relays RY2 and RY3 are connected to the bus bar wiring from power module 210 to motor 100 by welding. Relays RY1, RY2, and RY3 are used for fail-safe to cut off the power to the motor when the motor is abnormal or the control module is abnormal.

The control module 220 includes a CPU 222 and a driver circuit 224. Based on the torque detected by the torque sensor TS and the rotational position of the motor 100 detected by the resolver 156, the CPU 222 sends a control signal to the driver circuit 224 for on / off control of the semiconductor switching element SSW of the power module 210. Output. The driver circuit 224 drives the semiconductor switching element SSW of the power module 210 on and off based on a control signal supplied from the CPU 222. Provided to motor from power module 210 The supplied motor current is detected by motor current detection resistors (shunt resistors) DR1 and DR2, amplified by amplifiers API and AP2, and input to the CPU 222. The CPU 222 performs feedback control so that the motor current becomes a target value. The CPU 222 is connected to an external engine control unit ECU or the like by CAN or the like, and is configured to exchange information.

[0112] Here, in the figure, Δ marks indicate portions connected by soldering using a lead frame. The structure uses a lead frame to relieve stress. The shape of the lead frame will be described later with reference to FIG. The electrical connection between the control module 220 and the power module 210 or the conductor module 230 is a solder connection using a lead frame.

[0113] The power module 210 includes six semiconductor switching elements SSW such as IGBTs. The semiconductor switching element SSW is connected in series to the upper arm and the lower arm for each of the three phases (U phase, V phase, W phase). Here, in the figure, X indicates an electrical connection portion connected by wire bonding. That is, the force by which the motor current is supplied from the power module 210 to the motor 100 via the bus bar of the conductor module 230. This current is, for example, a large current of 100A. Therefore, a structure that can flow a large current and relieve stress is connected by wire bonding. Details of this will be described later with reference to FIG. The power supply line and earth line for the semiconductor switching element SSW are also connected by wire bonding.

FIG. 10 is a perspective view showing the structure of a control device that controls the electric power steering motor of this embodiment. The same reference numerals as those in FIG. 9 denote the same parts.

FIG. 10 shows a state in which the power module 210 and the conductor module 230 are attached in the case 240, and the control module 220 in FIG. 9 shows an unattached state.

[0116] In the conductor module 230, a plurality of bus bars BB1, BB2, BB3, BB4, BB5, BB6, and BB7 are molded. The terminals of the bus bar and the terminals of electrical components such as common filter CF, normal filter NF, capacitors CC1, CC2, relays RY1, RY2, RY3 are connected by TIG welding (arc welding). In power module 210, a wiring pattern is formed on a metal substrate via an insulator, and a semiconductor switching element SSW such as a MOSFET (field effect transistor) is attached thereon. The power module 210 and the conductor module 230 are electrically connected by wire bonding WB1, WB2, WB3, WB4, WB5 at five power points. As for one wire bonding WB1, for example, five aluminum wires with a diameter of 500 μm are connected in parallel.

[0118] Case 240 is made of aluminum. At the time of assembly, the power module 210 and the conductor module 230 are respectively screwed into the case 240. Next, the control module 220 is also screwed in a position above the power module 210 and the conductor module 230. The multiple ends of the lead frame 210LF are soldered to the terminals of the control module 220. Finally, the motor control device 200 is manufactured by screwing the shield cover 250 with screws.

[0119] The power module 210 and the conductor module 230 are arranged to face each other on the same plane. That is, the power module 210 is disposed on one side of the case 240, and the conductor module 230 is disposed on the other side of the case 240. Therefore, the wire bonding operation can be easily performed.

[0120] According to the present invention, a power steering motor capable of reducing torque pulsation and generating large torque, excellent both in reducing torque pulsation and generating large torque, and an electric power steering system using the same Can be obtained.

Claims

The scope of the claims

An electric power steering motor that is driven by multi-phase AC power and outputs steering torque,

Frame (150),

A stator (110) fixed to the frame;

A rotor (130) disposed opposite to the stator via a gap;

Have

The stator (110)

A stator core (112);

A multiphase stator coil (114) incorporated in the stator core;

With

The stator core (112)

Formed by joining a plurality of divided core pieces,

The plurality of divided core pieces are formed in a letter shape in which one piece of a core piece obtained by dividing the back core portion into a plurality of portions in the circumferential direction and a core piece corresponding to the tea score portion are integrated. The core piece,

The stator core is formed by connecting a plurality of the T-shaped core pieces in the circumferential direction,

A slot portion is formed between the adjacent tee score portions of the stator core, and the stator coil (114) is housed in the slot portion and wound around the tee score portion in a concentrated manner. ,

The rotor (130)

Rotor core (132),

A plurality of magnets (134) fixed to the outer peripheral surface of the rotor core;

With

Between the number of magnets (number of poles) and the number of slots, there is a relationship of 8 poles 9 slots or 10 poles-9 slots or 10 poles-12 slots. An electric power steering motor.

[2] In the electric power steering motor according to claim 1,

The electric power steering motor, wherein the stator core (112) and the stator coil (114) are molded by a molding material (MR) in a state where the stator coil is incorporated in the stator core!

[3] In the electric power steering motor according to claim 2,

The stator core (112) is press-fitted into the frame,

The stator core is press-fitted into the frame partially at a plurality of locations in the circumferential direction,

The electric power steering motor, wherein the molding material is filled between the stator core and the frame.

[4] In the electric power steering motor according to claim 1,

The plurality of magnets (134) are covered with an outer peripheral side non-magnetic tubular member and fixed on the outer peripheral surface of the rotor core.

An electric power steering motor.

[5] In the electric power steering motor according to claim 1,

The stator coil (114) is configured by electrically connecting a plurality of phase coils by a delta connection method,

The plurality of phase coils may be configured by electrically connecting a plurality of the unit coils in series electrically.

An electric power steering motor.

[6] In the electric power steering motor according to claim 1,

The electric power steering motor is attached in the vicinity of the steering rod, and transmits the driving force to the rod.

The electric power steering motor is disposed in a vehicle cabin.

An electric power steering motor.

[7] In-vehicle power supply power converter that converts the obtained power into multi-phase AC power and outputs it. Power controlled motor that outputs torque for steering. And

Frame (150),

A stator (110) fixed to the frame;

A rotor (130) disposed opposite to the stator via a gap;

Have

The stator (110)

A stator core (112);

A multi-phase stator coil (114) incorporated in the stator core;

With

The stator core (112)

Formed by joining a plurality of divided core pieces,

A slot portion is formed between the adjacent tee score portions of the stator core, and the stator coil is housed in the slot portion and wound around the tee score portion in a concentrated manner.

The rotor (130)

Rotor core (132),

With

Between the number of magnets (number of poles) and the number of slots, there is a relationship of 8 poles 9 slots or 10 poles-9 slots or 10 poles-12 slots.

An electric power steering motor.

The electric power steering motor according to claim 7, The electric power steering motor, wherein the stator core (112) and the stator coil (114) are molded by a molding material (MR) in a state where the stator coil is incorporated in the stator core!

[9] The electric power steering motor according to claim 7,

An electric power steering motor.

[10] The electric power steering motor according to claim 9,

The stator coil (112) is configured by electrically connecting a plurality of phase coils by a delta connection method,

An electric power steering motor.

[11] In the electric power steering motor according to claim 7,

The electric power steering motor is disposed in a vehicle cabin.

An electric power steering motor.

[12] On-vehicle power supply,

A control device (200) that converts the DC power supplied via the in-vehicle power supply wire harness into multiphase AC power and controls the output according to the torque applied to the steering wheel,

An electric power steering system having an electric power steering motor (100) driven by the AC power supplied from the controller and outputting steering torque,

The electric power steering motor (100) is:

Frame (150),

A stator (110) fixed to the frame; A rotor (130) disposed opposite to the stator via a gap;

Have

The stator (110)

A stator core (112);

A multiphase stator coil (114) incorporated in the stator core;

With

The stator core (112)

Formed by joining a plurality of divided core pieces,

The stator core is formed by joining a plurality of the T-shaped core pieces in the circumferential direction,

The rotor (130)

Rotor core (132),

With

An electric power steering system characterized by that.

The electric power steering system according to claim 12,

The electric power steering system, wherein the stator core (112) and the stator coil (114) are molded by a molding material (MR) in a state where the stator coil is incorporated in the stator core! [14] The electric power steering system according to claim 12,

An electric power steering system characterized by that.

[15] The electric power steering system according to claim 14,

An electric power steering system characterized by that.

[16] The electric power steering system according to claim 12,

The electric power steering motor is attached in the vicinity of the steering rod and transmits the driving force to the rod.

The electric power steering system is characterized in that the electric power steering motor is disposed in a passenger compartment of a vehicle.