Wound rotor brushless doubly-fed motor

• US 8,928,199 B2
• Filed: 07/08/2011
• Issued: 01/06/2015
• Est. Priority Date: 03/27/2009
• Status: Active Grant

• Current Assignee: China Changjiang National Shipping Group Motor Factory, Huazhong University of Science & Technology
• Original Assignee: China Changjiang National Shipping Group Motor Factory, Huazhong University of Science & Technology
• Inventors: Wang, Xuefan, Shu, Dixian
• Primary Examiner(s): Nguyen, Tran
• Assistant Examiner(s): Truong, Thomas
• Application Number:
  US13/178,542
• Publication Number:
  US 20120007461A1
• Time in Patent Office: 1,278 Days
• Field of Search: 310/178, 310/180, 310/179, 310/166, 310/171, 310/173, 310/211, 310/212, 310/184, 310/185, 310/195, 310/197
• US Class Current: 310/198
• CPC Class Codes: H02K 17/165 characterised by the squirrel-cage or other short-circuited windings
• CPC Class Codes: H02K 3/12 arranged in slots
• CPC Class Codes: H02K 3/28 Layout of windings or of connections between windings windings for pole-changing H02K17/06, H02K17/14, H02K19/12, H02K19/32

Abstract

A wound rotor brushless doubly-fed motor includes a stator and a rotor. The stator includes two sets of three-phase windings and the number of pole pairs is p₁ and p₂ respectively. The rotor includes a multi-phase wound winding and phase number m is satisfied with the relation m=(p₁+p₂)/m_k, in which, when p₁+p₂ is odd, m_k=1; when p₁+p₂ is even, m_k=2. Rotor slots are evenly distributed along the circumference of the air gap and the number of the rotor slots Z′ is satisfied with the relation Z′=n(p₁+p₂), in which n is a positive integer. Rotor winding coils are multi-turn structure, coil number of each phase winding is nm_k and each coil has the same span, but turn ratios among the coils are different. When the phase winding coils number ≦nm_k, all coils within the phase winding are automatically connected in short after being connected in series. The advantage of this invention is that the winding coil span can be changed flexibly and number of turns of each coil may be different so as to weaken high-order harmonics to the maximum extent.

Claims

1. A wound rotor brushless doubly-fed motor for connecting to a power grid power supply and a variable-frequency power supply, the wound rotor brushless doubly-fed motor comprising:

an air gap having a circumference;

a stator comprising a first set of three-phase windings and a second set of three-phase windings, each winding having pole pairs, wherein there are p₁ in number of pole pairs in the first set of the three-phase windings and there are p₂ in number of pole pairs in the second set of the three-phase windings; and

a rotor comprising a plurality of slots evenly distributed along the circumference, a number of the plurality of slots being Z′

; and

one set of multi-phase windings having a plurality of phases, a number of the plurality of phases being m, and having a plurality of winding coils in each phase, each of the plurality of winding coils having an equal span;

wherein;

Z′

equals to n(p₁+p₂), wherein n is a positive integer and n is equal to or greater than two;

the first set of the three-phase windings is adapted to be connected to the power grid power supply and to receive current from the power grid power supply;

the second set of the three-phase windings is adapted to be connected to the variable-frequency power supply and to receive current from the variable-frequency power supply;

the rotor is adapted to induce a first rotating MMF and a second rotating MMF in response to the current from the power grid power supply and the current from the variable-frequency power supply, respectively, and rotating direction of the first rotating MMF and rotating direction of the second rotating MMF are opposite to each other;

when in use, the rotational speed of the wound rotor brushless doubly-fed motor is variable in response to the variation of the frequency of the variable-frequency power supply;

the plurality of winding coils in each phase of the one set of multi-phase windings is disposed in the plurality of slots, and a number of the plurality of winding coils in each of the plurality of slots is zero or one;

when p₁+p₂ is odd, m equals to p₁+p₂, and a number of the plurality of winding coils in each phase of the one set of multi-phase windings is equal to or smaller than n; and

when p₁+p₂ is even, m equals to (p₁+p₂)/2, and a number of the plurality of winding coils in each phase of the one set of multi-phase windings is equal to or smaller than 2n.

2. The motor of claim 1, wherein each of the plurality of winding coils in each phase of the one set of multi-phase windings has an equal number of coil turns.

3. The motor of claim 1, wherein each of the plurality of slots has an equal number of a slot fill factor.

4. The motor of claim 1, wherein:

the plurality of winding coils in each phase of the multi-phase winding comprises a first group of winding coils and a second group of winding coils; and

the first group of winding coils is connected in series and the second group of winding coils is connected in series whereby two closed-loop circuits are formed in each phase of the multi-phase winding.

5. The motor of claim 1, wherein none of the plurality of winding coils in each phase of the one set of multi-phase windings is disposed in each of at least one of the plurality of slots.

6. In a wound rotor brushless doubly-fed motor for connecting to a power grid power supply and a variable-frequency power supply, the wound rotor brushless doubly-fed motor comprising a three-phase power winding having p₁ pole pairs, a three-phase control winding having p₂ pole pairs, and a multi-phase winding having a plurality of phases and having a plurality of winding coils in each phase, a number of the plurality of phases being m, the multi-phase winding being disposed in a plurality of slots, and a number of the plurality of slots being Z′

;

the improvement comprising that;

a) Z′

=n(p₁+p₂), n is a positive integer and n is equal to or greater than two;

b) when p₁+p₂ is odd, m equals to p₁+p₂, when p₁+p₂ is even, m equals to (p₁+p₂)/2;

c) the first set of the three-phase windings is adapted to be connected to the power grid power supply and to receive current from the power grid power supply;

d) the second set of the three-phase windings is adapted to be connected to the variable-frequency power supply and to receive current from the variable-frequency power supply;

e) the rotor is adapted to induce a first rotating MMF and a second rotating MMF in response to the current from the power grid power supply and the current from the variable-frequency power supply, respectively, and rotating direction of the first rotating MMF and rotating direction of the second rotating MMF are opposite to each other;

f) when in use, the rotational speed of the wound rotor brushless doubly-fed motor is variable in response to the variation of the frequency of the variable-frequency power supply;

g) the plurality of winding coils in each phase of the multi-phase winding is disposed in the plurality of slots, and a number of the plurality of winding coils in each of the plurality of slots is zero or one; and

h) when p₁+p₂ is odd, a number of the plurality of winding coils in each phase of the multi-phase winding is equal to or smaller than n; and

when p₁+p₂ is even, a number of the plurality of winding coils in each phase of the multi-phase winding is equal to or smaller than 2n.

7. The motor of claim 6, wherein none of the plurality of winding coils in each phase of the one set of multi-phase windings is disposed in each of at least one of the plurality of slots.

8. A wound rotor brushless doubly-fed motor for connecting to a power grid power supply and a variable-frequency power supply, the wound rotor brushless doubly-fed motor comprising:

an air gap having a circumference;

a stator comprising a first set of three-phase windings and a second set of three-phase windings, each winding having pole pairs, there being 4 pole pairs in the first set, and there being 2 pole pairs in the second set; and

a rotor comprising a plurality of slots evenly distributed along the circumference; and

one set of multi-phase windings having a plurality of phases and having a plurality of winding coils in each phase, each of the plurality of winding coils having an equal span;

wherein;

a number of the plurality of slots is 54;

a number of the plurality of phases of the one set of multi-phase windings is 3;

the first set of the three-phase windings is adapted to be connected to the power grid power supply and to receive current from the power grid power supply;

the second set of the three-phase windings is adapted to be connected to the variable-frequency power supply and to receive current from the variable-frequency power supply;

the rotor is adapted to induce a first rotating MMF and a second rotating MMF in response to the current from the power grid power supply and the current from the variable-frequency power supply, respectively, and rotating direction of the first rotating MMF and rotating direction of the second rotating MMF are opposite to each other;

when in use, the rotational speed of the wound rotor brushless doubly-fed motor is variable in response to the variation of the frequency of the variable-frequency power supply;

none of the plurality of winding coils is disposed in 8 of the 18 slots in each phase of the one set of multi-phase windings; and

one of the plurality of winding coils is disposed in each of the remaining 10 slots in each phase of the one set of multi-phase windings.