JP2010268589A - Rotating electric machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the generation of an copper loss resulting from the magnetic flux of a fundamental wave frequency. <P>SOLUTION: This rotating electric machine comprises secondary coils 19a, 20a and 21a which are not electrically connected to armature coils 16a, 17a and 18a and wound around teeth 13a, 14a and 15a of a stator 12, and the secondary coils 19a, 20a and 21a are connected in series to one another. According to such a constitution, since unnecessary currents do not flow to the secondary coils 19a, 20a and 21a by an induction voltage, the generation of the copper loss resulting from the magnetic flux of the fundamental wave frequency can be suppressed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rotating electrical machine having magnetic flux suppression means for reducing a field magnetic flux interlinked with an armature coil.

  Conventionally, a rotor having a permanent magnet for forming a field, a stator core disposed opposite to the permanent magnet of the rotor via a magnetic gap, an armature coil wound in a slot of the stator core, and a stator core 2. Description of the Related Art A rotating electric machine having a short-circuited coil wound around a tooth portion is known. In this rotating electric machine, when the rotational speed of the rotor increases, the current flowing through the short-circuited coil (short-circuit current) increases, so that the field magnetic flux (harmonic magnetic flux) linked to the armature coil is reduced (weakened). Field).

JP-A-8-172742

  The conventional rotating electric machine has a configuration in which a short-circuit coil is wound around the tooth portion of the stator iron core independently of the armature coil, and thus is caused by a magnetic flux having a fundamental frequency (electrical angular frequency) that drives the rotating electric machine. Then, an induced voltage is generated in the short-circuited coil, and unnecessary current flows through the short-circuited coil due to the induced voltage, thereby causing copper loss.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a rotating electrical machine capable of suppressing the occurrence of copper loss due to the magnetic flux having the fundamental frequency.

  In the rotating electrical machine according to the present invention, the stator includes a plurality of coils different from the armature coil, and the plurality of coils are connected to each other.

  According to the rotating electrical machine according to the present invention, since unnecessary current does not flow through the plurality of coils due to the induced voltage, it is possible to suppress the occurrence of copper loss due to the magnetic flux of the fundamental frequency.

It is a block diagram which shows the structure of the electric vehicle used as embodiment of this invention. It is sectional drawing which shows the structure of the rotary electric machine shown in FIG. It is a schematic diagram which shows the structure of the tooth | gear part, armature coil, and secondary coil of a rotary electric machine driven by a three-phase alternating current. It is a schematic diagram which shows the phase difference of a three-phase carrier signal. It is a schematic diagram which shows the phase difference of the carrier signal in the rotary electric machine which has 3 sets of tooth parts by which the armature coil of 3 phases was wound. It is a vector diagram for demonstrating the phase of the induced voltage which generate | occur | produces in a secondary coil. It is a schematic diagram which shows the connection form of the secondary coil in the rotary electric machine which has 3 sets of tooth | gear parts by which the armature coil of 3 phases was wound.

  The rotating electrical machine according to the present invention can be applied to an electric vehicle 1 (such as a hybrid vehicle or an electric vehicle) as shown in FIG. Hereinafter, a configuration of an electric vehicle 1 according to an embodiment of the present invention to which a rotating electrical machine according to the present invention is applied will be described with reference to the drawings.

[Configuration of electric vehicle]
As shown in FIG. 1, an electric vehicle 1 according to an embodiment of the present invention includes a PWM drive type inverter (INV) that converts a DC current of a battery 2 into a three-phase (U-phase, V-phase, W-phase) AC current. 3 and a motor 5 (rotating electrical machine) that rotationally drives the rear wheels 4c and 4d using the three-phase alternating current supplied from the inverter 3. In the present embodiment, the motor 5 rotates the rear wheels 4c and 4d. However, the front wheels 4a and 4b or both the front wheels 4a and 4b and the rear wheels 4c and 4d may be driven to rotate.

[Motor configuration]
As shown in FIG. 2, the motor 5 includes a rotor 11 having a permanent magnet (not shown) for forming a field, and a stator 12 arranged to face the permanent magnet of the rotor 11 via a magnetic gap. Have. The stator 12 has three sets of three-phase (U-phase, V-phase, W-phase) tooth portions arranged at equiangular intervals (U-phase tooth portions 13a-13c, V-phase tooth portions 14a-14c, W-phase). Tooth portions 15a to 15c) and armature coils (see FIG. 3) wound around the respective tooth portions. FIG. 3 shows one set of three-phase tooth portions (U-phase tooth portion 13a, V-phase tooth portion 14a, W-phase tooth portion 15a) and armature coils 16a and 17a wound around each tooth portion. , 18a is schematically shown.

  A secondary coil (secondary coils 19a, 20a, and 21a in the configuration shown in FIG. 3) is wound around each tooth portion of the three phases, independently of the armature coil. The secondary coils of each set are connected in series between the V-phase secondary coil (secondary coil 20a in the configuration shown in FIG. 3) and the W-phase secondary coil (secondary coil 21a in the configuration shown in FIG. 3). A resistance element R is inserted into the. According to such a configuration, the phase of the induced voltage induced in the U-phase, V-phase, and W-phase teeth due to the magnetic flux at the fundamental frequency is shifted by 120 ° between the phases. The induced voltage generated in the coils (secondary coils 19a, 20a, 21a in the configuration shown in FIG. 3) is zero. Therefore, the copper loss of the secondary coil caused by the magnetic flux having the fundamental frequency can be reduced to zero.

By the way, according to the said structure, since the phase of the magnetic flux of fundamental wave frequency has shifted | deviated 120 degree | times between phases, the electric current which weakens the magnetic flux of fundamental wave frequency does not flow into a secondary coil. At this time, if the phase of the high-frequency magnetic flux is also shifted by 120 ° between phases, the harmonic magnetic flux cannot be weakened. As an example, in order to show the phase of the harmonic magnetic flux generated when power is supplied by the inverter 3 of the PWM drive system, the PWM output voltage having the same phase as the harmonic magnetic flux is shown in Equations 1 and 2. In Equation 1, the parameter n represents an odd number of 1 or more, and the parameter k represents an even number of 2 or more. In Equation 2, the parameter n represents an even number of 2 or more, and the parameter k represents an odd number of 1 or more. In Equations 1 and 2, parameter v ₁ is the output voltage, parameter _Ed is the DC voltage, parameter a is the modulation factor, parameter ω ₀ is the electrical angular velocity (= 2πf ₀ ), parameter f ₀ is the electrical angular frequency, and parameter ψ _0. Is the phase difference of the fundamental wave from the U phase, the parameter ω _s is the carrier angular velocity, and the parameter f _s is the carrier frequency.

As is clear from Equations 1 and 2, when the value of parameter k is not a multiple of 3, the harmonic phases of the U phase, V phase, and W phase are shifted by 120 °, so the harmonic magnetic flux cannot be weakened. . Therefore, in the present embodiment, in order to be able to attenuate the magnetic flux having a frequency whose parameter k is not a multiple of 3, as shown in FIG. 4, the switching element S1 of U phase, V phase, and W phase constituting the inverter 3 is used. A phase difference is provided for the carrier signals of .about.S6. When a phase difference is provided in the carrier signals of the switching elements of the U phase, the V phase, and the W phase, the PWM output voltage is expressed by the following equations 3 and 4. In Equation 3, the parameter n represents an odd number of 1 or more, and the parameter k represents an even number of 2 or more. In Equation 4, parameter n represents an even number of 2 or more, and parameter k represents an odd number of 1 or more. In Equations 3 and 4, the parameter ψ _S indicates the phase difference from the U-phase carrier signal.

  As is clear from Equations 3 and 4, when a phase difference is provided in the carrier signals of the switching elements of the U phase, V phase, and W phase, the phase of the U-phase, V-phase, and W-phase harmonic magnetic flux is 120 °. It will not shift. Therefore, the induction voltage caused by the harmonic magnetic flux is generated in the secondary coil, so that the high frequency magnetic flux can be reduced.

  By the way, when the secondary coil is connected in series and the phase of the carrier signal of the three-phase switching elements constituting the inverter 3 is shifted, the three-phase switching elements are not simultaneously turned on or off when the modulation factor is 0. Wave current may occur. Therefore, when there are three sets of U-phase, V-phase, and W-phase teeth, triangular waves are compared using carrier signals of the same phase within the same set. Further, as shown in FIG. 5, the secondary coil is wound around the secondary coil 19a wound around the U-phase tooth portion 13a of the first set and the V-phase tooth portion 14b of the second set. The secondary coil 20b thus made and the secondary coil 21c wound around the third phase W-phase tooth portion 15c are connected in series. A resistance element R is inserted between the secondary coil 19a and the secondary coil 21c.

  According to such a configuration, since the harmonic magnetic flux passing through each of the secondary coils connected in series has a different phase, the current flows through the secondary coil and the harmonic magnetic flux can be reduced. Since the phase of each carrier signal is the same, it is possible to prevent a harmonic current from being generated in the armature coil due to the phase shift of the carrier signal. In the present embodiment, the motor 5 is a three-phase × three-set motor. However, the motor 5 can be similarly realized in a P-phase × Q-set motor (P and Q are arbitrary natural numbers).

  Next, some examples of how to shift the phase of the carrier signal will be described.

[Example 1]
Since the secondary coil wound around each phase is connected in series, if the phase of the induced voltage generated in the secondary coil of each phase becomes the same phase, a current flows through the secondary coil and the magnetic flux can be reduced. . Therefore, in the first embodiment, the phase of the carrier signal is used in order to make the induced voltage generated in the secondary coil wound around the tooth portion of each phase the same phase for the component of the angular velocity nω _s + kω ₀ in Equations 3 and 4. [psi _S is shifted only the carrier signal phase Keipusai ₀ such that kψ _0. Specifically, when the number of phases is 3 and k = 1, the phase (ψ _S ) of the carrier signal of the U phase (kψ ₀ = 0) is 0, and the phase of the carrier signal of the V phase (kψ ₀ = 120) ( ψ _S ) is 120 °, and the phase (ψ _S ) of the carrier signal of the W phase (kψ ₀ = 240) is 240 °. As a result, the component of the angular velocity nω _s + kω ₀ of the induced voltage generated in the secondary coil wound in the U-phase, V-phase, and W-phase becomes the same phase, and current flows through the secondary coil, and the angular velocity nω _s + kω. _Zero magnetic flux is reduced. On the other hand, in the component of the angular velocity nω _s −kω ₀ , the induced voltage of the three phases shifts by 120 °, so that the induced voltage generated in the secondary coil cancels out and the current does not flow and is not reduced.

When the number of phases is 3 and k = 1, when the phase of the carrier signal (carrier phase) is not shifted, the induced voltage generated in the secondary coils of the U phase, V phase, and W phase as shown in FIG. The phases (vectors V1, V′2, V′3) of the angular velocity nω _s + kω ₀ and the angular velocity nω _s −kω ₀ are shifted by 120 °. On the other hand, when the V-phase and W-phase carrier phases are shifted by 180 ° with respect to the U-phase carrier phase, the angular velocities nω _s + kω ₀ and the angular velocities of the induced voltages generated in the U-phase, V-phase, and W-phase secondary coils. The phase of nω _s −kω ₀ component (vectors V1, V2, V3) is shifted by 60 °. That is, when the V-phase and W-phase carrier phases are shifted by 180 ° with respect to the U-phase carrier phase, the angular velocity nω _s + kω ₀ and the angular velocity of the induced voltage generated in the U-phase, V-phase, and W-phase secondary coils. For both the components of nω _s −kω ₀ , the sum of the induced voltage vectors of each phase does not become 0, and a current flows through the secondary coil, so that the magnetic flux of both frequency components can be reduced. Therefore, the phase of the V-phase and W-phase carrier signals may be shifted by 180 ° with respect to the phase of the U-phase carrier signal.

[Example 2]
In the second embodiment, the phase of the carrier signal is calculated using mathematical formulas so as to minimize the iron loss. As an example, the angular velocity component of a motor driven by a three-phase alternating current will be described below. When the amplitude of the magnetic flux generated in the tooth portion of each phase by the armature coil and the permanent magnet is φ, the magnetic flux φ _u ′ of the U-phase tooth portion attenuated by the secondary coil is expressed as the following Expression 5. The In Equation 5, parameters φ _uv ′ and φ _uw ′ indicate the phase difference between the U-phase carrier signal and the V-phase carrier signal and the phase difference between the U-phase carrier signal and the W-phase carrier signal, respectively.

Similarly, the magnetic fluxes φ _V ′ and φ _W ′ of the V-phase and W-phase teeth attenuated by the secondary coil are expressed as in the following equations 6 and 7.

Assuming that the relations shown in Formulas 5 to 7 are generalized and the iron loss is proportional to the square of the product of the frequency and the magnetic flux density, the harmonic magnetic flux is calculated by the following Formulas 8 and 9. Therefore, the iron loss W can be minimized by calculating the phase ψ _S of the carrier signal that minimizes the iron loss W using the phase ψ _{S of the} carrier signal as a variable. In Equation 8, the parameter n represents an odd number of 1 or more, and the parameter k represents an even number of 2 or more. In Equation 9, the parameter n represents an even number of 2 or more, and the parameter k represents an odd number of 1 or more. In Equations 8 and 9, parameter m represents the number of phases, and parameter K represents the iron loss coefficient.

  As is clear from the above description, in the electric vehicle 1 according to the embodiment of the present invention, the tooth portion 13a of the stator 12 that is not electrically connected to the armature coils 16a to 16c, 17a to 17c, and 18a to 18c. Secondary coils 19a to 19c, 20a to 20c, and 21a to 21c wound around ~ 13c, 14a to 14c, and 15a to 15c, and the secondary coils 19a to 19c, 20a to 20c, and 21a to 21c are connected in series. ing. According to such a configuration, unnecessary current does not flow through the secondary coils 19a to 19c, 20a to 20c, and 21a to 21c due to the induced voltage, thereby suppressing the occurrence of copper loss due to the magnetic flux of the fundamental frequency. can do. Moreover, in the electric vehicle 1 which becomes embodiment of this invention, the phase of the carrier signal which drives the inverter 3 so that the electric current which suppresses a specific harmonic magnetic flux may flow into the secondary coils 19a-19c, 20a-20c, 21a-21c. Therefore, when the secondary coils 19a to 19c, 20a to 20c, and 21a to 21c are connected in series, it is possible to prevent the specific harmonic magnetic flux from being attenuated.

  In a rotating electrical machine having three sets of teeth around which U-phase, V-phase, and W-phase armature coils are wound as shown in FIG. 5, as shown in FIG. 7, the first set of U-phase teeth 13a The secondary coil 19a wound around the secondary coil 19b wound around the second set of U-phase teeth 13b, and the secondary coil 19c wound around the third set of U-phase teeth 13c. May be connected in parallel via resistance elements R1 to R3. According to such a configuration, since the fundamental frequency of the U phase is the same between the three sets, no current due to the magnetic flux of the fundamental frequency flows through the secondary coils connected in parallel. Therefore, it is possible to prevent the copper loss due to the current caused by the magnetic flux having the fundamental frequency in the secondary coil. Although not shown, the same effect can be obtained by winding secondary coils in the V phase and the W phase and connecting them in parallel.

  When the harmonic magnetic flux generated in the tooth portion around which the secondary coils 19a, 19b, and 19c are wound has the same phase, the induced voltage due to the harmonic magnetic flux is canceled in the secondary coil. Thus, the harmonic current does not flow, and the harmonic magnetic flux generated in the tooth portion cannot be reduced. In this case, if the current is supplied from the PWM drive type inverter, the current of the carrier signal of the inverter supplying the current to the first set of the three phases and the current of the second set of the three phases are supplied. By making the phase of the carrier signal of the current inverter different from the phase of the carrier signal of the inverter that supplies current to the third phase of the third set, harmonic current flows through the secondary coil, reducing harmonic flux can do.

  The embodiment to which the invention made by the present inventors is applied has been described above, but the present invention is not limited by the description and the drawings that constitute a part of the disclosure of the present invention. That is, it is needless to say that other embodiments, examples, operational techniques, and the like made by those skilled in the art based on the present embodiment are all included in the scope of the present invention.

1: Electric vehicle 2: Battery 3: Inverter (INV)
4a, 4b: front wheels 4c, 4d: rear wheels 5: motor 11: rotor 12: stators 13a-13c, 14a-14c, 15a-15c: teeth 16a-16c, 17a-17c, 18a-18c: armature coil 19a -19c, 20a-20c, 21a-21c: secondary coil

Claims (5)

A rotor, a stator, and an armature coil wound around the stator are provided, and alternating magnetic flux is generated in a magnetic circuit formed by the rotor and the stator by passing a multiphase alternating current through the armature coil. In the rotating electrical machine
The stator includes a plurality of coils different from the armature coils, and the plurality of coils are connected to each other. In the rotating electrical machine according to claim 1,
The rotating electric machine, wherein the plurality of coils are not electrically connected to the armature coil. The rotating electrical machine according to claim 2,
The rotating electrical machine, wherein the plurality of coils are connected in series. The rotating electrical machine according to claim 2,
The rotating electrical machine, wherein the plurality of coils are connected in parallel. In the rotating electrical machine according to claim 3 or claim 4,
The multiphase alternating current is energized to the plurality of coils by an inverter circuit driven by a plurality of carrier signals, and the inverter circuit has a plurality of carriers such that a current for suppressing a specific harmonic magnetic flux flows through the plurality of coils. A rotating electrical machine characterized by shifting the phase of a signal.

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