WO2013018122A1 - Brush-less exciter and full-bridge inverter employed by the same - Google Patents

Brush-less exciter and full-bridge inverter employed by the same Download PDF

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Publication number
WO2013018122A1
WO2013018122A1 PCT/JP2011/004341 JP2011004341W WO2013018122A1 WO 2013018122 A1 WO2013018122 A1 WO 2013018122A1 JP 2011004341 W JP2011004341 W JP 2011004341W WO 2013018122 A1 WO2013018122 A1 WO 2013018122A1
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WO
WIPO (PCT)
Prior art keywords
winding
rotor
sub
windings
sub field
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Application number
PCT/JP2011/004341
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French (fr)
Inventor
Shouichi Tanaka
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Three Eye Co., Ltd.
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Publication date
Application filed by Three Eye Co., Ltd. filed Critical Three Eye Co., Ltd.
Priority to PCT/JP2011/004341 priority Critical patent/WO2013018122A1/en
Publication of WO2013018122A1 publication Critical patent/WO2013018122A1/en

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
    • H02P9/14—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field
    • H02P9/26—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field using discharge tubes or semiconductor devices
    • H02P9/30—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field using discharge tubes or semiconductor devices using semiconductor devices
    • H02P9/302—Brushless excitation
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K11/00—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
    • H02K11/04—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection for rectification
    • H02K11/042—Rectifiers associated with rotating parts, e.g. rotor cores or rotary shafts
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K19/00—Synchronous motors or generators
    • H02K19/16—Synchronous generators
    • H02K19/38—Structural association of synchronous generators with exciting machines

Definitions

  • the present invention relates to a brush-less exciter and a full-bridge inverter employed by the brush-less exciter, in particular to a brush-less exciter employed for a wound rotor electric rotary machine.
  • U. S. Patent No. 5,519,275, No. 6,608,473 and No. 6,995,485 describe a single-phase brush-less exciter supplying a field current to a field winding wound on a rotor of an electric rotary machine such as an alternator.
  • the exciter of 275' patent shown in Figure 1 has a full bridge inverter 102, a rotary transformer 100 and a rectifier 101.
  • the rotary transformer 100 has a pair of one primary winding 103 and one secondary winding 105.
  • One secondary winding 105 and the rectifier 101 are fixed on a rotor 104 of the alternator.
  • a secondary alterative voltage induced across the secondary winding 105 is applied to a field winding 106 of the alternator via the rectifier 101 consisting of full bridge diode rectifier having four diodes.
  • the exciter of 473' patent shown in Figure 2 has a full bridge inverter 102, a rotary transformer 100 and another rectifier.
  • the rotary transformer 100 of 473' patent has one primary winding 103 and two secondary windings 105.
  • a first secondary voltage induced across the first secondary winding is applied to a common field winding 106 via a first diode of the rectifier 101.
  • a second secondary voltage induced across the second secondary winding 105 is applied to the common field winding 106 via a second diode of rectifier 101.
  • Full bridge inverters 102 shown in Figures 1 and 2 consist of four MOS transistors each. Inverter 102 supplies an alternative current to primary winding 103 with a large leakage inductance value, because rotary transformer 100 has an electro-magnetic air gap between a primary core and a secondary core. It is considered that full bridge inverter 102 must be operated with simple switching method for reducing a power loss.
  • FIG. 3 Another contact-less exciter 200, which is called a rotating three-phase exciter, is shown in Figure 3.
  • the exciter 200 employed by a three-phase synchronous generator has a rotating three-phase excitation winding 201 fixed on an axis of a rotor.
  • a three-phase voltage generated across the winding 201 is supplied to a field winding 202 via a three-phase diode rectifier 203 fixed on an axis.
  • the field current always flows through winding 201.
  • a generating voltage of the three-phase synchronous generator is controlled by means of controlling a DC current Idc supplied to a static winding 204 wound on stator poles arranged around the rotating three-phase winding 201.
  • secondary winding 105 and excitation winding 201 of the above exciters have a large power loss, because most or the entire field current flows through the windings 105 and 201.
  • the electric rotary machines with the above exciters become large and heavy, because the windings 105 and 201 must have a large cross-section for reducing a copper loss.
  • rotary transformers 100 has a large magnetic resistance each. It causes to increase an exciting current and a power loss. It is effective to increase a diameter or an axial width of the electro-magnetic air gap of rotary transformer 100 for reducing the magnetic resistance.
  • rotary transformer 100 becomes large and heavy. It causes that the alternator becomes large and heavy.
  • An object of the invention is to provide a compact brush-less exciter with an excellent efficiency. Another object of the invention is to provide a full bridge inverter having simple switching operation and a low power loss.
  • a field winding of an electric rotary machine with a wound rotor which is called the wound motor, is powered by a brush-less exciter.
  • a generation winding of the exciter includes a secondary winding of a rotary transformer and a rotating generation winding of a three-phase synchronous generator. The induced voltage across the generation winding is applied to the field winding via a rotating rectifier having at least two diodes.
  • the field winding includes at least two sub field windings. Each of the sub field windings is wound on each different rotor pole of the rotor.
  • the first diode of the rectifier is connected in parallel to the first sub field winding.
  • the second diode is connected in parallel to the second sub field winding.
  • Each free-wheeling current supplied from each sub field winding flows through each diode, when the induced current supplied from the generation winding to the field winding is stopped.
  • the generation winding consists of a secondary winding of the rotary transformer.
  • the contact-less electric rotary machine with a wound rotor becomes compact and has an excellent efficiency.
  • the exciter has a full-bridge inverter.
  • a first half bridge of the full-bridge inverter, which has two transistors, is PWM-switched complimentarily.
  • a second half bridge of the full-bridge inverter, which has two transistors, is PWM-switched complimentarily.
  • the four transistors always have a PWM duty ratio of 50% each.
  • the output power of the inverter is controlled by means of shifting a phase difference between gate voltages of the first leg and the second leg in order to control the field current. Accordingly, the full-bridge inverter is controlled simply.
  • the electric rotary machine consists of two Lundell-type rotor cores (1A and 1B) fixed to the axis (3) in tandem.
  • the sub field windings are wound different rotor cores respectively.
  • the tandem machine with at least two Lundell rotors can have a low power loss and a small rotary transformer.
  • a transverse flux machine has a plurality stator/rotor pairs arranged in tandem. Each of the sub field windings is wound on each different rotor core of the stator/rotor pairs.
  • a multi-phase TFM can have a low power loss and a small rotary transformer.
  • the electric rotary machine has at least four rotor poles, on which at least four sub field windings are wound respectively.
  • the rectifier has at least six diodes.
  • a rotor pole number is changed by means of changing field current directions of the field windings. The rotor pole number is changed easily.
  • the electric rotary machine has a stator winding driven by a six-phase inverter.
  • the six-phase inverter is capable of changing an equivalent stator pole number by means of switching the six-phase inverter. A torque of the machine is changed easily.
  • the rotary transformer has a bowl-shaped primary core and a bobbin-shaped secondary core.
  • the primary core has a disc portion and a cylinder portion.
  • the secondary core has a large disc portion, a small disc portion and a boss portion.
  • the large disc portion is near a bearing for supporting the axis.
  • the small disc portion is far from the bearing for supporting the axis.
  • the rotary transformer has two electro-magnetic gaps.
  • the first electro-magnetic gap between the large disc portion and the cylinder portion consists of a cylinder-shaped radial air gap.
  • the second electro-magnetic gap between the small disc portion and the disc portion consists of a disc-shaped axial gap.
  • the generation winding consists of a three rotating windings of a rotating three-phase generator for generating the field winding.
  • Each of six diodes of the rectifier is connected in parallel to each of six sub field windings of the field winding.
  • the three rotating windings are connected to three pairs of the six sub field windings respectively.
  • a compact rotating three-phase generator with a high efficiency is constructed in order to supply the field current.
  • Figure 1 is a schematic cross-section showing a prior wound rotor machine with a rotary transformer type exciter.
  • Figure 2 is a schematic cross-section showing a prior wound rotor machine with a rotary transformer type exciter.
  • Figure 3 is a circuit topology configuration showing a prior rotating three-phase exciter supplying a field current to a synchronous generator with a wound rotor.
  • Figure 4 is a circuit topology configuration showing a rotary transformer type exciter of the embodiment.
  • Figure 5 is a schematic cross-section showing a radial section of a rotor of a synchronous machine excited by the exciter shown in Figure 4.
  • Figure 6 is a circuit topology configuration showing operation of the exciter shown in Figure 4.
  • Figure 7 is a circuit topology configuration showing the operation of the exciter shown in Figure 4.
  • Figure 8 is a circuit topology configuration showing the operation of the exciter shown in Figure 4.
  • Figure 9 is a timing chart showing the operation of the exciter shown in Figure 4.
  • Figure 10 is a schematic cross-section showing an alternator with rotors arranged in tandem.
  • Figure 11 is a circuit topology configuration showing an arranged circuit of the exciter shown in Figure 4.
  • Figure 12 is a schematic cross-section showing a transverse flux machine (TFM) having four sub field windings wound on four rotor cores arranged in tandem.
  • Figure 13 is a schematic cross-section showing a radial cross section of a rotor with eight rotor poles on which eight sub field windings are wound respectively.
  • TFM transverse flux machine
  • Figure 14 is a circuit topology configuration showing another arranged exciter employed by a synchronous machine with the rotor shown in Figure 13.
  • Figure 15 is a drawing for showing a six-phase inverter for supplying a six-phase voltage to a stator of the synchronous machine with the rotor shown in Figure 13.
  • Figure 16 is an axial cross-section showing a rotary transformer having a radial electro-magnetic gap and an axial electro-magnetic gap between a primary core and a secondary core of the rotary transformer.
  • Figure 17 is a circuit topology configuration showing a rotating three-phase exciter employed by a three-phase synchronous generator.
  • Figure 18 is a circuit topology configuration showing an equivalent circuit of the exciter shown in Figure 4.
  • Figure 19 is a diagram showing power consumptions of the prior exciter and the exciter of the embodiment.
  • FIG. 4 is a circuit topology configuration.
  • the exciter 1 is fixed on a rotating axis of a wound rotor electric rotary machine.
  • Exciter 1 supplying a field current to a field winding 9 of the wound rotor motor consists of a single-phase full bridge inverter 6, a rotary transformer 2 and a diode rectifier 7.
  • the inverter 6 has two legs (two half bridges) consisting of four MOS transistors 61-64.
  • the first leg consists of an upper transistor 61 and a lower transistor 62, which are connected in series to each other.
  • the second leg consists of an upper transistor 63 and a lower transistor 64, which are connected in series to each other.
  • Inverter 6 applies a single-phase alternative voltage to a primary winding 28 of the rotary transformer 2.
  • a secondary voltage induced across a secondary winding 24 of rotary transformer 2 is supplied to a field winding 9 consisting of four sub field winding 91-94, which are connected in series to each other.
  • a diode rectifier 7 consists of two diodes 7A and 7B, which are connected in series to each other.
  • the diode 7A is connected in parallel to the sub field windings 91 and 92.
  • the diode 7B is connected in parallel to the sub field windings 93 and 94.
  • a connecting line 90 connecting a center point of field winding 9 is connected to both of anodes of diodes 7A and 7B.
  • the connecting line 90 can be connected to both of cathodes of diodes 7A and 7B.
  • Figure 5 is a schematic cross-section of a rotor 8 of the wound rotor motor powered by the exciter 1 shown in Figure 4.
  • the rotor 8 press-fixed on the axis 3 has four rotor poles 8A, 8B, 8C and 8D in turn to the circumferential direction of the rotor 8.
  • Sub field winding 91 is wound on the rotor pole 8A.
  • Sub field winding 92 is wound on the rotor pole 8B.
  • Sub field winding 93 is wound on the rotor pole 8C.
  • Sub field winding 94 is wound on the rotor pole 8D.
  • FIG. 6-8 shows the currents in exciter 1.
  • Figure 9 is a schematic timing chart showing gate voltages V1, V2, V3 and V4 applied to full bridge inverter 6 and currents I1, I2, If1 and If2 flowing in exciter 1.
  • Figure 6 schematically shows a positive-current period T2 when transistors 61 and 64 are turned on.
  • Inverter 6 supplies a positive half of a primary alternative current Ii to primary winding 28.
  • a secondary voltage induced across secondary winding 24 supplies a first current I1 to sub field windings 91 and 92 through diode 7B.
  • a second free-wheeling current If2 flows through sub field windings 93 and 94 via diode 7B.
  • Figure 7 schematically shows the free-wheeling periods T1 and T3 when all transistors 61-64 are turned off. Inverter 6 stops to supply the primary alternative current Ii to primary winding 28. In the free-wheeling periods T1 and T3, the second free-wheeling current If2 flows through sub field windings 93 and 94 via diode 7B. A first free-wheeling current If1 flows through sub field windings 91 and 92 via diode 7A.
  • Figure 8 schematically shows a negative current period T4 when transistors 62 and 63 are turned on.
  • Inverter 6 supplies a negative half of primary alternative current Ii to primary winding 28.
  • a secondary voltage induced across secondary winding 24 supplies a second current I2 to sub field windings 93 and 94 through diode 7A.
  • the first free-wheeling current If1 flows through sub field windings 91 and 92 via diode 7A.
  • the free-wheeling periods T1 and T3 become zero, when the duty ratio becomes 50%.
  • rotary transformer 2 has a compact magnetic core.
  • the diode rectifier 7 with two diodes 7A and 7B is similar to a known current-doubler. However, it is not known that a current-doubler-like rectifier 7, of which diodes 7A and 7B are connected in parallel to two sub field windings respectively.
  • a feature of full-bridge inverter 6 shown in Figure 4 is explained referring to Figure 9.
  • Each of transistors 61-64 is switched with the PWM-switching method having a predetermined value of a career frequency, for example 20 kHz.
  • a length of the positive current period T2 and a length of the negative current period T4 are controlled by means of shifting a phase difference To between gate voltages V1 and V4 and gate voltages V2 and V3. Accordingly, positive current period T2 and negative current period T4 can be controlled very easily by means of the shifting of the phase difference To.
  • FIG. 1 An arranged embodiment 1
  • the arranged embodiment 1 is explained referring to Figure 10 showing a schematic axial cross-section of a so-called tandem alternator, which has two rotor cores 1A and 1B fixed in tandem to the rotating axis 3.
  • the adjacent rotor cores 1A and 1B of the Lundell type are located inside of a stator core 10 with a stator winding 11.
  • the alternator has the field winding consisting of sub field windings 91 and 93.
  • Sub field winding 91 is wound on a boss portion of a first rotor core 1A.
  • Sub field winding 93 is wound on a boss portion of a second rotor core 1B.
  • Secondary winding 24 of rotary transformer 2 is wound on secondary core 21 of rotary transformer 2.
  • Secondary core 21 is press-fixed to rotating axis 3.
  • a skilled engineer is capable of understanding that the tandem alternator has the same performance as the synchronous motor shown in Figures 4-9.
  • rectifier 7 has four diodes 7A, 7B, 7C and 7D.
  • Diode 7A is connected in parallel to sub field winding 91.
  • Diode 7B is also connected in parallel to sub field winding 93.
  • the cathode of diode 7B is connected to the anode of diode 7A.
  • rectifier 7 shown in Figure 11 is essentially equal to rectifier 7 shown in Figure 4.
  • FIG. 12 Another arranged embodiment 3 is explained referring to Figure 12 showing a schematic axial cross-section of a transverse flux machine (TFM) with four stator/rotor pairs, which are equal to four single-phase transverse flux motor.
  • TFM transverse flux machine
  • Each of rotors is arranged in tandem to the axial direction AX of the rotating axis (not shown).
  • Four ring-shaped stator cores 41-44 of stator 4 are arranged in tandem to axial direction AX.
  • Four ring-shaped stator windings 46-48 of stator 4 are accommodated in ring-shaped slots of stator cores 41-44 respectively.
  • Stator cores 41-44 have left teeth 4L and right teeth 4R each.
  • the left teeth 4L and the right teeth 4R of each stator core are connected by a ring-shaped stator yoke portion of each stator core.
  • the left teeth 4L and the right teeth 4R are arranged to the circumferential direction each.
  • Rotor 5 has four ring-shaped rotor cores 51-54 located inside of ring-shaped stator 4. Rotor cores 51-54 are arranged in tandem to axial direction AX. Four ring-shaped sub field windings 91-94 are accommodated in ring-shaped slots of rotor cores 51-54 respectively. Rotor cores 51-54 have left teeth 5L and right teeth 5R each.
  • the left teeth 5L and the right teeth 5R of each rotor core are connected by a ring-shaped rotor yoke portion of each rotor core.
  • the left teeth 5L and the right teeth 5R are arranged to the circumferential direction.
  • Left teeth 4L of each stator core face left teeth 5L of each rotor core across a ring-shaped electro-magnetic air gap.
  • Right teeth 4R of each stator core face right teeth 5R of each rotor core across a ring-shaped electro-magnetic air gap.
  • Sub field windings 91 and 92 connected in series to each other are connected in parallel to diode 7A of diode rectifier 7.
  • Sub field windings 93 and 94 connected in series to each other are connected in parallel to diode 7B of diode rectifier 7.
  • rectifier 7 shown in Figure 12 is essentially equal to rectifier 7 shown in Figure 4.
  • FIG. 13 shows a schematic axial cross-section of a rotor 5 of a synchronous motor with a wound rotor.
  • the rotor 5 has a rotor core with eight rotor poles 301-308 projecting radial outward.
  • the rotor poles 301-308 are connected magnetically to a cylinder-shaped rotor yoke portion press-fixed to the rotating axis 3.
  • Eight sub field windings 91-98 are wound on eight rotor poles 301-308 respectively.
  • the field current is supplied to sub field windings 91-97 from secondary winding 24 of rotary transformer 2 via rectifier 7 having six diodes 7A, 7B and 71-74 and two MOS transistors 75 and 76 as shown in Figure 14.
  • Diode 7A is connected in parallel to sub field windings 93 and 98, which are connected in series to each other.
  • Diode 7B is connected in parallel to sub field windings 94 and 97, which are connected in series to each other.
  • Sub field windings 91 and 96 are connected in series to each other.
  • Sub field windings 92 and 95 are connected in series to each other.
  • Diode 71 is connected in parallel to sub field windings 91 and 96 via transistor 75.
  • Diode 72 is connected in parallel to sub field windings 92 and 95 via transistor 75.
  • Diode 73 is connected in parallel to sub field windings 91 and 96 via the transistor 76.
  • Diode 74 is connected in parallel to sub field windings 92 and 95 via transistor 76.
  • the anode of diode 73 in connected to the cathode of diode of diode 71.
  • the anode of diode 74 in connected to the cathode of diode of diode 72.
  • Transistor 75 is capable of stopping a current passing through diodes 71 and 72.
  • Transistor 76 is capable of stopping a current passing through diodes 73 and 74.
  • diode 7A can be connected in parallel to sub field windings 93 and 94 which are connected in series.
  • Diode 7B can be connected in parallel to sub field windings 97 and 98 which are connected in series.
  • diode 71 can be connected in parallel to sub field windings 91 and 92 which are connected in series via transistor 75.
  • Diode 72 can be connected in parallel to sub field windings 95 and 96 which are connected in series via transistor 75.
  • Diode 73 can be connected in parallel to sub field windings 91 and 92 which are connected in series via transistor 76.
  • Diode 74 can be connected in parallel to sub field windings 95 and 96 which are connected in series via transistor 76.
  • Rectifying operation of diodes 7A and 7B shown in Figure 14 is essentially equal to the rectifying operation of diodes 7A and 7B shown in Figure 4.
  • Top surfaces of rotor poles 304 and 308 have N poles by the magnetizing of sub field windings 94 and 98.
  • top surfaces of rotor poles 303 and 307 have S poles by the magnetizing of sub field windings 93 and 97.
  • top surfaces of rotor poles 301 and 305 have S poles by the magnetizing of sub field windings 91 and 95.
  • top surfaces of rotor poles 302 and 306 have N poles by the magnetizing of sub field windings 92 and 96. Consequently, rotor 5 has eight poles as shown in Figure 13.
  • a controller shown in Figure 14 controls transistors 75 and 76 in accordance with a control signal in order to change the pole number of the rotor core.
  • the control signal can be transmitted to the controller via rotary transformer 2.
  • a DC power is supplied to the controller from secondary winding 24 of rotary transformer 2.
  • control signal is transmitted by means of the frequency modulation (FM) method or the amplitude modulation (AM) method.
  • a career frequency for the signal transmission is higher than the career frequency for the power transmission for separating the control signal. Any another technology can be employed for transmitting the control signal.
  • stator pole number of stator 4 is changed in accordance with the changing of the above rotor pole number. Changing operation of the stator pole number is explained referring to Figure 15.
  • Figure 15 is a schematic drawing for showing twelve stator poles 40 and a six-phase inverter 6A with six legs 401-406.
  • Stator 4 has a stator core having twelve stator poles (stator teeth) 40. each sub stator winding of two groups of twelve sub stator windings S1-S6 is wound on each stator pole 40 as shown in Figure 15.
  • the leg 401 of the six-phase inverter 6A outputs a first phase voltage to the first stator winding S1.
  • the leg 402 of the six-phase inverter 6A outputs a second phase voltage to the second stator winding S2.
  • the leg 403 of the six-phase inverter 6A outputs a third phase voltage to the third stator winding S3.
  • the leg 404 of the six-phase inverter 6A outputs a fourth phase voltage to the fourth stator winding S4.
  • the leg 405 of the six-phase inverter 6A outputs a fifth phase voltage to the fifth stator winding S5.
  • the leg 406 of the six-phase inverter 6A outputs a sixth phase voltage to the sixth stator winding S6.
  • the eight-pole mode 'A' is explained referring to Figure 15.
  • Eight-pole mode 'A' is executed, when the rotor 5 has eight poles.
  • Each of the legs 401 and 404 outputs a U-phase voltage U to sub stator windings S1 and S4, which are the concentrated windings.
  • Each of the legs 402 and 405 outputs a V-phase voltage U to sub stator windings S2 and S5, which are the concentrated windings.
  • Each of the legs 403 and 406 outputs a W-phase voltage W to sub stator windings S3 and S6, which are the concentrated windings.
  • stator 4 has four times of 360 electrical degrees.
  • Rotor 5 with eight poles can be rotated synchronously in accordance with a rotating magnetic field formed by the two groups of sub stator windings S1-S6, when rotor 5 has eight poles.
  • Each phase angle among sinusoidal phase voltages U, V and W are 120 degrees.
  • Six sub stator windings S1-S6 are arranged to the circumferential direction PH in turn.
  • the first four-pole mode 'B' is explained referring to Figure 15.
  • Four-pole mode 'B' is executed, when the rotor 5 has four poles equivalently.
  • Leg 401 outputs a U-phase voltage U to sub stator windings S1 and S4.
  • Leg 402 outputs a -W-phase voltage -W to sub stator windings S2.
  • Leg 403 outputs a V-phase voltage V to sub stator windings S3.
  • Leg 404 outputs a -U-phase voltage -U to sub stator windings S4.
  • Leg 405 outputs a W-phase voltage W to sub stator windings S5.
  • Leg 406 outputs a -V-phase voltage -V to sub stator windings S6.
  • stator 4 has two times of 360 electrical degrees.
  • sub stator windings S1-S6 become so-called distributed windings equivalently.
  • Rotor 5 with four poles can be rotated synchronously in accordance with a rotating magnetic field formed by the two groups of sub stator windings S1-S6, when rotor 5 has four poles.
  • the first four-pole mode 'C' The second four-pole mode 'C' is explained referring to Figure 15.
  • Four-pole mode 'C' is executed, when the rotor 5 has four poles equivalently.
  • Adjacent two legs 401 and 402 output a U-phase voltage U to sub stator windings S1 and S2.
  • Adjacent two legs 403 and 404 output a V-phase voltage V to sub stator windings S3 and S5.
  • Adjacent two legs 405 and 406 output a W-phase voltage W to sub stator windings S5 and S6.
  • stator 4 has two times of 360 electrical degrees. In the other words, adjacent two stator poles (stator teeth) has same phase. It is known as the one-phase/two-teeth method.
  • Rotor 5 with four poles can be rotated synchronously in accordance with a rotating magnetic field formed by the two groups of sub stator windings S1-S6, when rotor 5 has four poles.
  • Figure 16 is an axial cross-section view showing a half of rotary transformer 2 supplying an inductive power to a field winding wound on the Lundell-type rotor core (not shown) fixed on axis 3.
  • a front housing (not shown) and a rear housing 1000 of an alternator support the rotating axis 3.
  • An end portion of axis 3 projects backward from the rear housing 1000.
  • Rotary transformer 2 consists of a secondary core 21, secondary winding 24, a primary core 25 and primary winding 28.
  • the bobbin-shaped secondary core 21 and the bowl-shaped primary core 25 consist of a ferrite core each.
  • Secondary core 21 consists of a boss portion 241, a large disc portion 243 and a small disc portion 244.
  • the boss portion 241 press-fixed to axis 3 has a center hole 242 in which the end portion of axis 3 is inserted.
  • the large disc portion 243 extends radial outward from a front portion of boss portion 241.
  • the small disc portion 244 extends radial outward from a rear portion of boss portion 241.
  • Secondary winding 24 is wound on boss portion 241 between two disc portions 243 and 244.
  • An outer diameter of secondary winding 24 is mostly equal to a diameter of small disc portion 244.
  • Large disc portion 243 has larger diameter than small disc portion 244.
  • Bowl-shaped primary core 25 fixed to the rear housing 1000 consists of a disc portion 251 and a cylinder portion 252.
  • the cylinder portion 252 extends frontward from outer peripherary of disc portion 251.
  • Primary winding 28 is accommodated in the bowl-shaped primary core 25.
  • An outer surface of primary core 25 comes to contact with an inner surface of cylinder portion 252.
  • a rear surface of primary core 25 comes to contact with a front surface of disc portion 251.
  • the cylinder portion 252 extends frontward from primary winding 28, and has a ring-shaped electro-magnetic surface S14 facing a ring-shaped electro-magnetic surface S13 of large disc portion 243 across a ring-shaped small air gap.
  • the electro-magnetic surface S13 consists of an outer circumferential surface of large disc portion 243.
  • the disc portion 251 extends radial inward from primary winding 28, and has a disc-shaped electro-magnetic surface S12 facing a disc-shaped electro-magnetic surface S11 of small disc portion 244 across a disc-shaped small air gap.
  • the electro-magnetic surface S12 consists of a ring-plate-shaped front surface of disc portion 251.
  • the electro-magnetic surface S11 consists of disc-shaped rear surface of small disc portion 244.
  • rotary transformer 2 has two electro-magnetic gaps between two cores 21 and 25.
  • the cylinder-shaped electro-magnetic gap formed between the surfaces S13 and S14 has a large diameter and is near rear housing 1000.
  • the disc-shaped electro-magnetic gap formed between the surfaces S11 and S12 has a small diameter and is far from rear housing 1000.
  • rotary transformer 2 has smaller magnetic resistance than the prior rotary transformer shown in the prior arts. Moreover, the vibrating force of the axis is reduced, because projecting axial length of rotary transformer 2 is short.
  • rotary transformer 2 shown in Figure 16 is compact in comparison with a prior rotary transformer of which a secondary core is fixed to an end portion of an axis. Furthermore, the current of secondary winding 24 is largely reduced in comparison with a prior rotary transformer, because the freewheeling current is not flow through the secondary winding 24.
  • a small secondary winding realizes a small secondary core and a small primary core.
  • cooling wind 'CA' flowing through a through-hole 253 and electro-magnetic air gaps radiates primary winding 28 and secondary winding 24 well.
  • Figure 17 is a schematic circuit topology configuration of a rotating three-phase exciter employed for supplying a field current to a three-phase synchronous generator.
  • the three-phase exciter has a three-phase excitation winding 400, a diode rectifier 7 and a current controller 500.
  • the three-phase excitation winding 400 which is the three-phase generation winding of the exciter, consists of a U-phase winding 400U, a V-phase winding 400V and a W-phase winding 400W.
  • Three phase windings 400U, 400V and 400W are wound on a rotor core of the exciter fixed on an axis of the three-phase synchronous generator.
  • the exciter has a stator core surrounding the rotor core on which the winding 400 is wound.
  • a static winding 503 is wound on stator poles of the stator core in order to producing a DC static magnetic field. Accordingly, a three-phase voltage is induced across three-phase winding 400, when three-phase winding 400 rotates in the DC static magnetic field.
  • a rotor of the three-phase synchronous generator has six rotor poles. Each of six sub field windings S1-S6 is wound on each rotor pole of the six rotor poles.
  • the diode rectifier 7 consists of diodes 71-76.
  • the diode 71 is connected in parallel to sub field winding S1.
  • the diode 72 is connected in parallel to sub field winding S2.
  • the diode 73 is connected in parallel to sub field winding S3.
  • the diode 74 is connected in parallel to sub field winding S4.
  • the diode 75 is connected in parallel to sub field winding S5.
  • the diode 76 is connected in parallel to sub field winding S6.
  • Star-connected three-phase winding 400 is connected to field winding 9 having six sub field windings S1-S6 with the star connection. Both neutral points of three-phase winding 400 and field winding 9 are connected with a neutral line 70.
  • the neutral line 70 can be abbreviated.
  • U-phase induced voltage of winding 400U is applied to sub field windings S1 and S2, which are connected in series to each other.
  • V-phase induced voltage of winding 400V is applied to sub field windings S3 and S4, which are connected in series to each other.
  • W-phase induced voltage of winding 400W is applied to sub field windings S5 and S6, which are connected in series to each other.
  • Windings 400U and diodes 71 and 72 constitutes a single-phase exciter, which is essentially equal to the exciter shown in Figure 4.
  • windings 400V and diodes 73 and 74 constitutes a single-phase exciter, which is essentially equal to the exciter shown in Figure 4.
  • windings 400W and diodes 75 and 76 constitutes a single-phase exciter, which is essentially equal to the exciter shown in Figure 4.
  • three-phase rotating exciter shown in Figure 17 has essentially same performance as the exciter shown in Figure 4.
  • the field current passing through field winding 9 is controlled by means of controlling a PWM-duty of transistor 502 connected in series to static winding 503.
  • a freewheeling current is circulated via the freewheeling diode 501 connected in parallel to static winding 503.
  • Figure 18 is a circuit topology configuration showing an equivalent circuit of the exciter shown in Figure 4.
  • Secondary winding 24 has an electric resistance value R2.
  • a field winding of the rotor has an electric resistance value Rf.
  • the resistance value R2 is 40% of the resistance value Rf.
  • a total of the field current If is equal to a sum of the secondary current I2 and a freewheeling current Id passing through diodes 7A and 7B.
  • the field current If is equal to the secondary current I2, and the freewheeling current Id is zero.

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Abstract

An exciter has a rectifier for rectifying an alternative voltage applied from a generation winding, for example a secondary winding of a rotary transformer. The rectifier has a pair of diodes, which are connected in parallel to a pair of sub field windings of a field winding respectively. The generation winding becomes compact and has a low power loss, because free-wheeling current component of the field current flowing through the field winding is bypassed by the diodes. A full-bridge inverter with two legs consists of two half bridges. Each leg has a PWM duty ratio of 50% each. An output power of the inverter is controlled by means of shifting a phase difference between gate voltages of the first leg and gate voltages of the second leg. The full-bridge inverter is controlled very simply.

Description

BRUSH-LESS EXCITER AND FULL-BRIDGE INVERTER EMPLOYED BY THE SAME
The present invention relates to a brush-less exciter and a full-bridge inverter employed by the brush-less exciter, in particular to a brush-less exciter employed for a wound rotor electric rotary machine.
U. S. Patent No. 5,519,275, No. 6,608,473 and No. 6,995,485 describe a single-phase brush-less exciter supplying a field current to a field winding wound on a rotor of an electric rotary machine such as an alternator.
The exciter of 275' patent shown in Figure 1 has a full bridge inverter 102, a rotary transformer 100 and a rectifier 101. The rotary transformer 100 has a pair of one primary winding 103 and one secondary winding 105. One secondary winding 105 and the rectifier 101 are fixed on a rotor 104 of the alternator. A secondary alterative voltage induced across the secondary winding 105 is applied to a field winding 106 of the alternator via the rectifier 101 consisting of full bridge diode rectifier having four diodes.
The exciter of 473' patent shown in Figure 2 has a full bridge inverter 102, a rotary transformer 100 and another rectifier. The rotary transformer 100 of 473' patent has one primary winding 103 and two secondary windings 105. A first secondary voltage induced across the first secondary winding is applied to a common field winding 106 via a first diode of the rectifier 101. A second secondary voltage induced across the second secondary winding 105 is applied to the common field winding 106 via a second diode of rectifier 101.
In Figures 1 and 2, the field current mostly flows through secondary winding 105. It causes to increase a copper loss of the exciter. Moreover, the rotary transformer must be radiated.
Full bridge inverters 102 shown in Figures 1 and 2 consist of four MOS transistors each. Inverter 102 supplies an alternative current to primary winding 103 with a large leakage inductance value, because rotary transformer 100 has an electro-magnetic air gap between a primary core and a secondary core. It is considered that full bridge inverter 102 must be operated with simple switching method for reducing a power loss.
Another contact-less exciter 200, which is called a rotating three-phase exciter, is shown in Figure 3. The exciter 200 employed by a three-phase synchronous generator has a rotating three-phase excitation winding 201 fixed on an axis of a rotor. A three-phase voltage generated across the winding 201 is supplied to a field winding 202 via a three-phase diode rectifier 203 fixed on an axis. The field current always flows through winding 201. A generating voltage of the three-phase synchronous generator is controlled by means of controlling a DC current Idc supplied to a static winding 204 wound on stator poles arranged around the rotating three-phase winding 201.
After all, secondary winding 105 and excitation winding 201 of the above exciters have a large power loss, because most or the entire field current flows through the windings 105 and 201. Particularly, the electric rotary machines with the above exciters become large and heavy, because the windings 105 and 201 must have a large cross-section for reducing a copper loss.
According to 275' patent and 473' patent, rotary transformers 100 has a large magnetic resistance each. It causes to increase an exciting current and a power loss. It is effective to increase a diameter or an axial width of the electro-magnetic air gap of rotary transformer 100 for reducing the magnetic resistance. However, rotary transformer 100 becomes large and heavy. It causes that the alternator becomes large and heavy.
United States Patent No. 5,519,275 United States Patent No. 6,608,473 United States Patent No. 6,995,485
An object of the invention is to provide a compact brush-less exciter with an excellent efficiency. Another object of the invention is to provide a full bridge inverter having simple switching operation and a low power loss.
According to a first aspect of the invention, a field winding of an electric rotary machine with a wound rotor, which is called the wound motor, is powered by a brush-less exciter. A generation winding of the exciter includes a secondary winding of a rotary transformer and a rotating generation winding of a three-phase synchronous generator. The induced voltage across the generation winding is applied to the field winding via a rotating rectifier having at least two diodes.
The field winding includes at least two sub field windings. Each of the sub field windings is wound on each different rotor pole of the rotor. The first diode of the rectifier is connected in parallel to the first sub field winding. The second diode is connected in parallel to the second sub field winding. Each free-wheeling current supplied from each sub field winding flows through each diode, when the induced current supplied from the generation winding to the field winding is stopped.
Large inductance values of sub field windings keep for the free-wheeling currents to flow via diodes without passing through the generation winding. A copper loss of the generation winding is abbreviated in the free-wheeling period. The generation winding is radiated easily, because the current of the generation winding is decreased. After all, the exciters with the rotary transformer or the rotating three-phase generator become compact.
According to a preferred embodiment, the generation winding consists of a secondary winding of the rotary transformer. The contact-less electric rotary machine with a wound rotor becomes compact and has an excellent efficiency.
According to another preferred embodiment and a second aspect of the invention, the exciter has a full-bridge inverter. A first half bridge of the full-bridge inverter, which has two transistors, is PWM-switched complimentarily. Similarly, a second half bridge of the full-bridge inverter, which has two transistors, is PWM-switched complimentarily. The four transistors always have a PWM duty ratio of 50% each. The output power of the inverter is controlled by means of shifting a phase difference between gate voltages of the first leg and the second leg in order to control the field current. Accordingly, the full-bridge inverter is controlled simply.
According to another preferred embodiment, the electric rotary machine consists of two Lundell-type rotor cores (1A and 1B) fixed to the axis (3) in tandem. The sub field windings are wound different rotor cores respectively. The tandem machine with at least two Lundell rotors can have a low power loss and a small rotary transformer.
According to another preferred embodiment, a transverse flux machine has a plurality stator/rotor pairs arranged in tandem. Each of the sub field windings is wound on each different rotor core of the stator/rotor pairs. A multi-phase TFM can have a low power loss and a small rotary transformer.
According to another preferred embodiment, the electric rotary machine has at least four rotor poles, on which at least four sub field windings are wound respectively. The rectifier has at least six diodes. A rotor pole number is changed by means of changing field current directions of the field windings. The rotor pole number is changed easily.
According to another preferred embodiment, the electric rotary machine has a stator winding driven by a six-phase inverter. The six-phase inverter is capable of changing an equivalent stator pole number by means of switching the six-phase inverter. A torque of the machine is changed easily.
According to another preferred embodiment, the rotary transformer has a bowl-shaped primary core and a bobbin-shaped secondary core. The primary core has a disc portion and a cylinder portion. The secondary core has a large disc portion, a small disc portion and a boss portion. The large disc portion is near a bearing for supporting the axis. The small disc portion is far from the bearing for supporting the axis. The rotary transformer has two electro-magnetic gaps. The first electro-magnetic gap between the large disc portion and the cylinder portion consists of a cylinder-shaped radial air gap. The second electro-magnetic gap between the small disc portion and the disc portion consists of a disc-shaped axial gap. A compact rotary transformer of which the secondary core is fixed to an end portion of a rotating axis is constructed.
According to another preferred embodiment, the generation winding consists of a three rotating windings of a rotating three-phase generator for generating the field winding. Each of six diodes of the rectifier is connected in parallel to each of six sub field windings of the field winding. The three rotating windings are connected to three pairs of the six sub field windings respectively. A compact rotating three-phase generator with a high efficiency is constructed in order to supply the field current.
Figure 1 is a schematic cross-section showing a prior wound rotor machine with a rotary transformer type exciter. Figure 2 is a schematic cross-section showing a prior wound rotor machine with a rotary transformer type exciter. Figure 3 is a circuit topology configuration showing a prior rotating three-phase exciter supplying a field current to a synchronous generator with a wound rotor. Figure 4 is a circuit topology configuration showing a rotary transformer type exciter of the embodiment. Figure 5 is a schematic cross-section showing a radial section of a rotor of a synchronous machine excited by the exciter shown in Figure 4. Figure 6 is a circuit topology configuration showing operation of the exciter shown in Figure 4. Figure 7 is a circuit topology configuration showing the operation of the exciter shown in Figure 4. Figure 8 is a circuit topology configuration showing the operation of the exciter shown in Figure 4. Figure 9 is a timing chart showing the operation of the exciter shown in Figure 4. Figure 10 is a schematic cross-section showing an alternator with rotors arranged in tandem. Figure 11 is a circuit topology configuration showing an arranged circuit of the exciter shown in Figure 4. Figure 12 is a schematic cross-section showing a transverse flux machine (TFM) having four sub field windings wound on four rotor cores arranged in tandem. Figure 13 is a schematic cross-section showing a radial cross section of a rotor with eight rotor poles on which eight sub field windings are wound respectively. Figure 14 is a circuit topology configuration showing another arranged exciter employed by a synchronous machine with the rotor shown in Figure 13. Figure 15 is a drawing for showing a six-phase inverter for supplying a six-phase voltage to a stator of the synchronous machine with the rotor shown in Figure 13. Figure 16 is an axial cross-section showing a rotary transformer having a radial electro-magnetic gap and an axial electro-magnetic gap between a primary core and a secondary core of the rotary transformer. Figure 17 is a circuit topology configuration showing a rotating three-phase exciter employed by a three-phase synchronous generator. Figure 18 is a circuit topology configuration showing an equivalent circuit of the exciter shown in Figure 4. Figure 19 is a diagram showing power consumptions of the prior exciter and the exciter of the embodiment.
A first embodiment of a single-phase brush-less exciter 1 is explained referring to Figure 4, which is a circuit topology configuration. In Figure 4, the exciter 1 is fixed on a rotating axis of a wound rotor electric rotary machine.
Exciter 1 supplying a field current to a field winding 9 of the wound rotor motor consists of a single-phase full bridge inverter 6, a rotary transformer 2 and a diode rectifier 7. The inverter 6 has two legs (two half bridges) consisting of four MOS transistors 61-64. The first leg consists of an upper transistor 61 and a lower transistor 62, which are connected in series to each other. The second leg consists of an upper transistor 63 and a lower transistor 64, which are connected in series to each other. Inverter 6 applies a single-phase alternative voltage to a primary winding 28 of the rotary transformer 2.
A secondary voltage induced across a secondary winding 24 of rotary transformer 2 is supplied to a field winding 9 consisting of four sub field winding 91-94, which are connected in series to each other. A diode rectifier 7 consists of two diodes 7A and 7B, which are connected in series to each other. The diode 7A is connected in parallel to the sub field windings 91 and 92. The diode 7B is connected in parallel to the sub field windings 93 and 94. A connecting line 90 connecting a center point of field winding 9 is connected to both of anodes of diodes 7A and 7B. The connecting line 90 can be connected to both of cathodes of diodes 7A and 7B.
Figure 5 is a schematic cross-section of a rotor 8 of the wound rotor motor powered by the exciter 1 shown in Figure 4. The rotor 8 press-fixed on the axis 3 has four rotor poles 8A, 8B, 8C and 8D in turn to the circumferential direction of the rotor 8. Sub field winding 91 is wound on the rotor pole 8A. Sub field winding 92 is wound on the rotor pole 8B. Sub field winding 93 is wound on the rotor pole 8C. Sub field winding 94 is wound on the rotor pole 8D.
Magnetizing operation of exciter 1 is explained referring to Figures 6-9. Figures 6-8 shows the currents in exciter 1. Figure 9 is a schematic timing chart showing gate voltages V1, V2, V3 and V4 applied to full bridge inverter 6 and currents I1, I2, If1 and If2 flowing in exciter 1.
Figure 6 schematically shows a positive-current period T2 when transistors 61 and 64 are turned on. Inverter 6 supplies a positive half of a primary alternative current Ii to primary winding 28. A secondary voltage induced across secondary winding 24 supplies a first current I1 to sub field windings 91 and 92 through diode 7B. In the positive current period T2, a second free-wheeling current If2 flows through sub field windings 93 and 94 via diode 7B.
Figure 7 schematically shows the free-wheeling periods T1 and T3 when all transistors 61-64 are turned off. Inverter 6 stops to supply the primary alternative current Ii to primary winding 28. In the free-wheeling periods T1 and T3, the second free-wheeling current If2 flows through sub field windings 93 and 94 via diode 7B. A first free-wheeling current If1 flows through sub field windings 91 and 92 via diode 7A.
Figure 8 schematically shows a negative current period T4 when transistors 62 and 63 are turned on. Inverter 6 supplies a negative half of primary alternative current Ii to primary winding 28. A secondary voltage induced across secondary winding 24 supplies a second current I2 to sub field windings 93 and 94 through diode 7A. In this negative current period T4, the first free-wheeling current If1 flows through sub field windings 91 and 92 via diode 7A.
A controller (not shown) for controlling the field current controls a duty ratio (=T2 / (T1+T2+T3+T4) =T4 / (T1+T2+T3+T4)). The free-wheeling periods T1 and T3 become zero, when the duty ratio becomes 50%.
It is considered that the field current supplied to the field winding 9 becomes more than double in comparison with a total value of the secondary currents I1 and I2 passing through secondary winding 24, because the total field current includes free-wheeling currents If1 and If2. As the result, secondary winding 24 become small, and a copper loss of secondary winding 24 is decreased. Furthermore, rotary transformer 2 has a compact magnetic core.
It is capable to construct a small wound rotor motor with a brush-less exciter. Moreover, it is capable to improve an efficiency of a wound rotor motor with a brush-less exciter. The diode rectifier 7 with two diodes 7A and 7B is similar to a known current-doubler. However, it is not known that a current-doubler-like rectifier 7, of which diodes 7A and 7B are connected in parallel to two sub field windings respectively.
A feature of full-bridge inverter 6 shown in Figure 4 is explained referring to Figure 9. Each of transistors 61-64 is switched with the PWM-switching method having a predetermined value of a career frequency, for example 20 kHz. Duty ratios (= one turned on period / (one turned-on period + one turned-off period)) of all transistors 61-64 are always a value of 0.5 each. A length of the positive current period T2 and a length of the negative current period T4 are controlled by means of shifting a phase difference To between gate voltages V1 and V4 and gate voltages V2 and V3. Accordingly, positive current period T2 and negative current period T4 can be controlled very easily by means of the shifting of the phase difference To.
(An arranged embodiment 1)
The arranged embodiment 1 is explained referring to Figure 10 showing a schematic axial cross-section of a so-called tandem alternator, which has two rotor cores 1A and 1B fixed in tandem to the rotating axis 3. The adjacent rotor cores 1A and 1B of the Lundell type are located inside of a stator core 10 with a stator winding 11. The alternator has the field winding consisting of sub field windings 91 and 93. Sub field winding 91 is wound on a boss portion of a first rotor core 1A.
Sub field winding 93 is wound on a boss portion of a second rotor core 1B. Secondary winding 24 of rotary transformer 2 is wound on secondary core 21 of rotary transformer 2. Secondary core 21 is press-fixed to rotating axis 3. A skilled engineer is capable of understanding that the tandem alternator has the same performance as the synchronous motor shown in Figures 4-9.
(Another arranged embodiment 2)
Another arranged embodiment 2 is explained referring to Figure 11 showing another schematic circuit topology of single-phase brush-less exciter 1 with rotary transformer 2. According to Figure 11, rectifier 7 has four diodes 7A, 7B, 7C and 7D. Diode 7A is connected in parallel to sub field winding 91. Diode 7B is also connected in parallel to sub field winding 93. However, the cathode of diode 7B is connected to the anode of diode 7A.
The positive half of secondary voltage of secondary winding 24 is applied to sub field winding 91 through diode 7C. The negative half of the secondary voltage of secondary winding 24 is applied to sub field winding 93 through diode 7D. A skilled engineer is capable of understanding that rectifier 7 shown in Figure 11 is essentially equal to rectifier 7 shown in Figure 4.
(Another arranged embodiment 3)
Another arranged embodiment 3 is explained referring to Figure 12 showing a schematic axial cross-section of a transverse flux machine (TFM) with four stator/rotor pairs, which are equal to four single-phase transverse flux motor. Each of rotors is arranged in tandem to the axial direction AX of the rotating axis (not shown). Four ring-shaped stator cores 41-44 of stator 4 are arranged in tandem to axial direction AX. Four ring-shaped stator windings 46-48 of stator 4 are accommodated in ring-shaped slots of stator cores 41-44 respectively.
Stator cores 41-44 have left teeth 4L and right teeth 4R each. The left teeth 4L and the right teeth 4R of each stator core are connected by a ring-shaped stator yoke portion of each stator core. The left teeth 4L and the right teeth 4R are arranged to the circumferential direction each.
Rotor 5 has four ring-shaped rotor cores 51-54 located inside of ring-shaped stator 4. Rotor cores 51-54 are arranged in tandem to axial direction AX. Four ring-shaped sub field windings 91-94 are accommodated in ring-shaped slots of rotor cores 51-54 respectively. Rotor cores 51-54 have left teeth 5L and right teeth 5R each.
The left teeth 5L and the right teeth 5R of each rotor core are connected by a ring-shaped rotor yoke portion of each rotor core. The left teeth 5L and the right teeth 5R are arranged to the circumferential direction. Left teeth 4L of each stator core face left teeth 5L of each rotor core across a ring-shaped electro-magnetic air gap. Right teeth 4R of each stator core face right teeth 5R of each rotor core across a ring-shaped electro-magnetic air gap.
Sub field windings 91 and 92 connected in series to each other are connected in parallel to diode 7A of diode rectifier 7. Sub field windings 93 and 94 connected in series to each other are connected in parallel to diode 7B of diode rectifier 7. A skilled engineer is capable of understanding that rectifier 7 shown in Figure 12 is essentially equal to rectifier 7 shown in Figure 4.
(Another arranged embodiment 4)
Another arranged embodiment 4 is explained referring to Figure 13 showing a schematic axial cross-section of a rotor 5 of a synchronous motor with a wound rotor. The rotor 5 has a rotor core with eight rotor poles 301-308 projecting radial outward. The rotor poles 301-308 are connected magnetically to a cylinder-shaped rotor yoke portion press-fixed to the rotating axis 3. Eight sub field windings 91-98 are wound on eight rotor poles 301-308 respectively.
The field current is supplied to sub field windings 91-97 from secondary winding 24 of rotary transformer 2 via rectifier 7 having six diodes 7A, 7B and 71-74 and two MOS transistors 75 and 76 as shown in Figure 14. Diode 7A is connected in parallel to sub field windings 93 and 98, which are connected in series to each other. Diode 7B is connected in parallel to sub field windings 94 and 97, which are connected in series to each other.
Sub field windings 91 and 96 are connected in series to each other. Sub field windings 92 and 95 are connected in series to each other. Diode 71 is connected in parallel to sub field windings 91 and 96 via transistor 75. Diode 72 is connected in parallel to sub field windings 92 and 95 via transistor 75. Diode 73 is connected in parallel to sub field windings 91 and 96 via the transistor 76. Diode 74 is connected in parallel to sub field windings 92 and 95 via transistor 76.
The anode of diode 73 in connected to the cathode of diode of diode 71. The anode of diode 74 in connected to the cathode of diode of diode 72. Transistor 75 is capable of stopping a current passing through diodes 71 and 72. Transistor 76 is capable of stopping a current passing through diodes 73 and 74.
It is considered that a first diode pair consisting of diodes 7A and 7B is essentially equal to diode rectifier 7 shown in Figure 4. It is considered that a second diode pair of diodes 71 and 72 is essentially equal to diode rectifier 7 shown in Figure 4, if transistor 75 is ignored. It is considered that a second diode pair of diodes 73 and 74 is essentially equal to diode rectifier 7 shown in Figure 4, if transistor 76 is ignored. According to another example, diode 7A can be connected in parallel to sub field windings 93 and 94 which are connected in series. Diode 7B can be connected in parallel to sub field windings 97 and 98 which are connected in series.
Similarly, diode 71 can be connected in parallel to sub field windings 91 and 92 which are connected in series via transistor 75. Diode 72 can be connected in parallel to sub field windings 95 and 96 which are connected in series via transistor 75. Diode 73 can be connected in parallel to sub field windings 91 and 92 which are connected in series via transistor 76. Diode 74 can be connected in parallel to sub field windings 95 and 96 which are connected in series via transistor 76.
Operation of rectifier 7 shown in Figure 14 is explained. Rectifying operation of diodes 7A and 7B shown in Figure 14 is essentially equal to the rectifying operation of diodes 7A and 7B shown in Figure 4. Top surfaces of rotor poles 304 and 308 have N poles by the magnetizing of sub field windings 94 and 98. Similarly, top surfaces of rotor poles 303 and 307 have S poles by the magnetizing of sub field windings 93 and 97.
When transistor 75 is turned on, and transistor 76 is turned off, top surfaces of rotor poles 301 and 305 have S poles by the magnetizing of sub field windings 91 and 95. Similarly, top surfaces of rotor poles 302 and 306 have N poles by the magnetizing of sub field windings 92 and 96. Consequently, rotor 5 has eight poles as shown in Figure 13.
When transistor 75 is turned off, and transistor 76 is turned on, directions of the field currents passing through sub field windings 91, 92, 95 and 96 become opposite. Accordingly, top surfaces of rotor poles 301 and 305 have N poles by the magnetizing of sub field windings 91 and 95. Similarly, top surfaces of rotor poles 302 and 306 have S poles by the magnetizing of sub field windings 92 and 96. Consequently, rotor 5 has four poles equivalently as shown in Figure 13. Skilled engineers can understand that rotor 5 can change the pole number equivalently.
A controller shown in Figure 14 controls transistors 75 and 76 in accordance with a control signal in order to change the pole number of the rotor core. The control signal can be transmitted to the controller via rotary transformer 2. Furthermore, a DC power is supplied to the controller from secondary winding 24 of rotary transformer 2.
It is preferable that the control signal is transmitted by means of the frequency modulation (FM) method or the amplitude modulation (AM) method. A career frequency for the signal transmission is higher than the career frequency for the power transmission for separating the control signal. Any another technology can be employed for transmitting the control signal.
The stator pole number of stator 4 is changed in accordance with the changing of the above rotor pole number. Changing operation of the stator pole number is explained referring to Figure 15. Figure 15 is a schematic drawing for showing twelve stator poles 40 and a six-phase inverter 6A with six legs 401-406. Stator 4 has a stator core having twelve stator poles (stator teeth) 40. each sub stator winding of two groups of twelve sub stator windings S1-S6 is wound on each stator pole 40 as shown in Figure 15.
The leg 401 of the six-phase inverter 6A outputs a first phase voltage to the first stator winding S1. The leg 402 of the six-phase inverter 6A outputs a second phase voltage to the second stator winding S2. The leg 403 of the six-phase inverter 6A outputs a third phase voltage to the third stator winding S3. The leg 404 of the six-phase inverter 6A outputs a fourth phase voltage to the fourth stator winding S4. The leg 405 of the six-phase inverter 6A outputs a fifth phase voltage to the fifth stator winding S5. The leg 406 of the six-phase inverter 6A outputs a sixth phase voltage to the sixth stator winding S6.
(The eight-pole mode 'A')
The eight-pole mode 'A' is explained referring to Figure 15. Eight-pole mode 'A' is executed, when the rotor 5 has eight poles. Each of the legs 401 and 404 outputs a U-phase voltage U to sub stator windings S1 and S4, which are the concentrated windings. Each of the legs 402 and 405 outputs a V-phase voltage U to sub stator windings S2 and S5, which are the concentrated windings. Each of the legs 403 and 406 outputs a W-phase voltage W to sub stator windings S3 and S6, which are the concentrated windings.
Accordingly, stator 4 has four times of 360 electrical degrees. Rotor 5 with eight poles can be rotated synchronously in accordance with a rotating magnetic field formed by the two groups of sub stator windings S1-S6, when rotor 5 has eight poles. Each phase angle among sinusoidal phase voltages U, V and W are 120 degrees. Six sub stator windings S1-S6 are arranged to the circumferential direction PH in turn.
(The first four-pole mode 'B')
The first four-pole mode 'B' is explained referring to Figure 15. Four-pole mode 'B' is executed, when the rotor 5 has four poles equivalently. Leg 401 outputs a U-phase voltage U to sub stator windings S1 and S4. Leg 402 outputs a -W-phase voltage -W to sub stator windings S2. Leg 403 outputs a V-phase voltage V to sub stator windings S3. Leg 404 outputs a -U-phase voltage -U to sub stator windings S4. Leg 405 outputs a W-phase voltage W to sub stator windings S5. Leg 406 outputs a -V-phase voltage -V to sub stator windings S6.
Accordingly, stator 4 has two times of 360 electrical degrees. In the other words, sub stator windings S1-S6 become so-called distributed windings equivalently. Rotor 5 with four poles can be rotated synchronously in accordance with a rotating magnetic field formed by the two groups of sub stator windings S1-S6, when rotor 5 has four poles.
(The first four-pole mode 'C')
The second four-pole mode 'C' is explained referring to Figure 15. Four-pole mode 'C' is executed, when the rotor 5 has four poles equivalently. Adjacent two legs 401 and 402 output a U-phase voltage U to sub stator windings S1 and S2. Adjacent two legs 403 and 404 output a V-phase voltage V to sub stator windings S3 and S5. Adjacent two legs 405 and 406 output a W-phase voltage W to sub stator windings S5 and S6.
Accordingly, stator 4 has two times of 360 electrical degrees. In the other words, adjacent two stator poles (stator teeth) has same phase. It is known as the one-phase/two-teeth method. Rotor 5 with four poles can be rotated synchronously in accordance with a rotating magnetic field formed by the two groups of sub stator windings S1-S6, when rotor 5 has four poles.
(Another arranged embodiment 5)
Structure of rotary transformer 2 is explained referring to Figure 16. Figure 16 is an axial cross-section view showing a half of rotary transformer 2 supplying an inductive power to a field winding wound on the Lundell-type rotor core (not shown) fixed on axis 3. A front housing (not shown) and a rear housing 1000 of an alternator support the rotating axis 3. An end portion of axis 3 projects backward from the rear housing 1000.
Rotary transformer 2 consists of a secondary core 21, secondary winding 24, a primary core 25 and primary winding 28. The bobbin-shaped secondary core 21 and the bowl-shaped primary core 25 consist of a ferrite core each. Secondary core 21 consists of a boss portion 241, a large disc portion 243 and a small disc portion 244. The boss portion 241 press-fixed to axis 3 has a center hole 242 in which the end portion of axis 3 is inserted.
The large disc portion 243 extends radial outward from a front portion of boss portion 241. The small disc portion 244 extends radial outward from a rear portion of boss portion 241. Secondary winding 24 is wound on boss portion 241 between two disc portions 243 and 244. An outer diameter of secondary winding 24 is mostly equal to a diameter of small disc portion 244. Large disc portion 243 has larger diameter than small disc portion 244.
Bowl-shaped primary core 25 fixed to the rear housing 1000 consists of a disc portion 251 and a cylinder portion 252. The cylinder portion 252 extends frontward from outer peripherary of disc portion 251. Primary winding 28 is accommodated in the bowl-shaped primary core 25. An outer surface of primary core 25 comes to contact with an inner surface of cylinder portion 252. A rear surface of primary core 25 comes to contact with a front surface of disc portion 251.
The cylinder portion 252 extends frontward from primary winding 28, and has a ring-shaped electro-magnetic surface S14 facing a ring-shaped electro-magnetic surface S13 of large disc portion 243 across a ring-shaped small air gap. The electro-magnetic surface S13 consists of an outer circumferential surface of large disc portion 243.
The disc portion 251 extends radial inward from primary winding 28, and has a disc-shaped electro-magnetic surface S12 facing a disc-shaped electro-magnetic surface S11 of small disc portion 244 across a disc-shaped small air gap. The electro-magnetic surface S12 consists of a ring-plate-shaped front surface of disc portion 251. The electro-magnetic surface S11 consists of disc-shaped rear surface of small disc portion 244.
After all, rotary transformer 2 has two electro-magnetic gaps between two cores 21 and 25. The cylinder-shaped electro-magnetic gap formed between the surfaces S13 and S14 has a large diameter and is near rear housing 1000. The disc-shaped electro-magnetic gap formed between the surfaces S11 and S12 has a small diameter and is far from rear housing 1000.
Thus, rotary transformer 2 has smaller magnetic resistance than the prior rotary transformer shown in the prior arts. Moreover, the vibrating force of the axis is reduced, because projecting axial length of rotary transformer 2 is short.
After all, rotary transformer 2 shown in Figure 16 is compact in comparison with a prior rotary transformer of which a secondary core is fixed to an end portion of an axis. Furthermore, the current of secondary winding 24 is largely reduced in comparison with a prior rotary transformer, because the freewheeling current is not flow through the secondary winding 24. A small secondary winding realizes a small secondary core and a small primary core. Moreover, cooling wind 'CA' flowing through a through-hole 253 and electro-magnetic air gaps radiates primary winding 28 and secondary winding 24 well.
(Another arranged embodiment 6)
Another arranged embodiment 6 is explained referring to Figure 17. Figure 17 is a schematic circuit topology configuration of a rotating three-phase exciter employed for supplying a field current to a three-phase synchronous generator. The three-phase exciter has a three-phase excitation winding 400, a diode rectifier 7 and a current controller 500.
The three-phase excitation winding 400, which is the three-phase generation winding of the exciter, consists of a U-phase winding 400U, a V-phase winding 400V and a W-phase winding 400W. Three phase windings 400U, 400V and 400W are wound on a rotor core of the exciter fixed on an axis of the three-phase synchronous generator. The exciter has a stator core surrounding the rotor core on which the winding 400 is wound. A static winding 503 is wound on stator poles of the stator core in order to producing a DC static magnetic field. Accordingly, a three-phase voltage is induced across three-phase winding 400, when three-phase winding 400 rotates in the DC static magnetic field.
A rotor of the three-phase synchronous generator has six rotor poles. Each of six sub field windings S1-S6 is wound on each rotor pole of the six rotor poles. The diode rectifier 7 consists of diodes 71-76.
The diode 71 is connected in parallel to sub field winding S1. The diode 72 is connected in parallel to sub field winding S2. The diode 73 is connected in parallel to sub field winding S3. The diode 74 is connected in parallel to sub field winding S4. The diode 75 is connected in parallel to sub field winding S5. The diode 76 is connected in parallel to sub field winding S6.
Star-connected three-phase winding 400 is connected to field winding 9 having six sub field windings S1-S6 with the star connection. Both neutral points of three-phase winding 400 and field winding 9 are connected with a neutral line 70. The neutral line 70 can be abbreviated.
U-phase induced voltage of winding 400U is applied to sub field windings S1 and S2, which are connected in series to each other. V-phase induced voltage of winding 400V is applied to sub field windings S3 and S4, which are connected in series to each other. W-phase induced voltage of winding 400W is applied to sub field windings S5 and S6, which are connected in series to each other.
Windings 400U and diodes 71 and 72 constitutes a single-phase exciter, which is essentially equal to the exciter shown in Figure 4. Similarly, windings 400V and diodes 73 and 74 constitutes a single-phase exciter, which is essentially equal to the exciter shown in Figure 4. Similarly, windings 400W and diodes 75 and 76 constitutes a single-phase exciter, which is essentially equal to the exciter shown in Figure 4.
After all, three-phase rotating exciter shown in Figure 17 has essentially same performance as the exciter shown in Figure 4. The field current passing through field winding 9 is controlled by means of controlling a PWM-duty of transistor 502 connected in series to static winding 503. A freewheeling current is circulated via the freewheeling diode 501 connected in parallel to static winding 503.
Comparison between the prior exciter shown in Figure 2 and the exciter shown in Figure 4 is explained referring to Figures 18 and 19. Figure 18 is a circuit topology configuration showing an equivalent circuit of the exciter shown in Figure 4. Secondary winding 24 has an electric resistance value R2. A field winding of the rotor has an electric resistance value Rf. In this example, the resistance value R2 is 40% of the resistance value Rf.
According to the exciter shown in Figure 4, a total of the field current If is equal to a sum of the secondary current I2 and a freewheeling current Id passing through diodes 7A and 7B. According to the prior exciter shown in Figure 2, the field current If is equal to the secondary current I2, and the freewheeling current Id is zero.
As shown in Figure 19, a total power loss P1 of the prior exciter becomes a relative value 1.4 consisting of a field winding power loss P3 (=1.0) and a secondary winding power loss P4 (0.4). A total power loss P2 of the exciter shown in Figure 4 becomes a relative value 1.0-1.2 consisting of a field winding power loss P3 (=1.0) and a secondary winding power loss P5 (0-0.2). After all, the power loss of the exciter is decreased.
(Another arranged embodiment 7)
A skilled engineer understands permanent magnets can be fixed on or in the rotor in order to reduce the field current.

Claims (10)

  1. A brush-less exciter for supplying a field current to a field winding of an electric rotary machine with a wound rotor, the exciter having an generation winding (24, 400) and a rectifier (7), wherein:
    the rectifier (7) has at least two diodes (7A and 7B, 71 and 72);
    the field winding consists of at least two sub field windings (91 and 93, S1 and S2) for magnetizing different rotor poles respectively;
    the first diode (7A, 71) is connected in parallel to the first sub field winding (91, S1) for circulating a first free-wheeling current of the first sub field winding (91, S1);
    the second diode (7B, 72) is connected in parallel to the second sub field winding (93, S2) for circulating a second free-wheeling current of the second sub field winding (93, S2); and
    the rectifier (7) applies a positive component of the alternative voltage to the first sub field winding (91, S1), and applies a negative component of the alternative voltage to the second sub field winding (93, S2).
  2. The brush-less exciter according to claim 1, wherein the generation winding (24, 400) consists of a secondary winding (24) of a rotary transformer (2) of which a secondary core (21) is fixed to an axis (3) of the electric rotary machine.
  3. The brush-less exciter according to claim 2, wherein:
    the rotary transformer (2) is powered by a full-bridge inverter (6) with four transistors (61-64);
    the transistors (61) and (62) consisting of the first leg of the full-bridge inverter (6) are switched complimentarily with a predetermined career frequency and a PWM duty ratio of 50%;
    the transistors (63) and (64) consisting of the second leg of the full-bridge inverter (6) are switched complimentarily with the predetermined career frequency and a PWM duty ratio of 50%; and
    the full-bridge inverter (6) controls a phase difference between gate voltages of the first leg and gate voltages of the second leg in order to control the field current.
  4. The brush-less exciter according to claim 2, wherein:
    the electric rotary machine consists of two Lundell type rotor cores (1A and 1B) fixed to the axis (3) in tandem;
    the first sub field winding (91) is wound on the first Lundell type rotor core (1A); and
    the second sub field winding (93) is wound on the second Lundell type rotor core (1B).
  5. The brush-less exciter according to claim 2, wherein:
    the electric rotary machine consists of a transverse flux machine having at least two stator/rotor pairs arranged in tandem;
    the first sub field winding (91) is wound on the first rotor core (51) of the first stator/rotor pair; and
    the second sub field winding (92) is wound on the second rotor core (52) of the second stator/rotor pair.
  6. The brush-less exciter according to claim 2, wherein:
    the electric rotary machine has at least four rotor poles (301-308) on which at least four sub field windings (91-98) are wound respectively;
    the rectifier (7) has essentially six diodes (7A and 7B and 91-94);
    the first and the second diodes (7A and 7B) are connected to a first field winding (93) and a second sub field windings (94) in order to supply a first field current to the first and the second sub field windings (93 and 94);
    the third and the fourth diodes (71 and 72) are connected to a third field winding (91) and a fourth sub field windings (92) in order to supply a second field current to the third and the fourth sub field windings (91 and 92) via a first transistor (75);
    the fifth and the sixth diodes (73 and 74) are connected to a third field winding (91) and a fourth sub field windings (92) in order to supply a third field current to the third and the fourth sub field windings (91 and 92) via a second transistor (76); and
    the first and the second transistors (75 and 76) give opposite directions to the second field current and the third field current to each other.
  7. The brush-less exciter according to claim 6, wherein:
    the electric rotary machine has a stator winding (4S) driven by a six-phase inverter (6A); and
    the six-phase inverter (6A) is capable of changing an equivalent stator pole number by means of switching the transistors of the six-phase inverter (6A).
  8. The brush-less exciter according to claim 2, wherein
    the rotary transformer (2) has a bowl-shaped primary core (25), a bobbin-shaped secondary core (21) and two electro-magnetic gaps between the primary core (25) and the secondary core (21);
    the secondary core (21) fixed to an end portion of the axis (3) has a boss portion (241), a large disc portion (243) and a small disc portion (244);
    the primary core (25) fixed to a motor housing (1000) has a disc portion (251) and a cylinder portion (252);
    the first electro-magnetic gap has a radial gap between the large disc portion (243) and the cylinder portion (252);
    the second electro-magnetic gap has an axial gap between the small disc portion (244) and the disc portion (251); and
    the large disc portion (243) is disposed at nearer position in the axial direction than the small disc portion (244).
  9. The brush-less exciter according to claim 1, wherein:
    the generation winding (400) consists of a three rotating windings (400U, 400V and 400W) of a rotating three-phase generator;
    each of six diodes (71-76) of the rectifier (7) is connected in parallel to each of six sub field windings (S1-S6) of the field winding (9);
    the three rotating windings (400U, 400V and 400W) of the generation winding (400) has either one of a star-connection and a delta-connection; and
    the six sub field windings (S1-S6) of the field winding (9) have either one of a star-connection and a delta-connection.
  10. A full bridge inverter having a first leg and a second leg, the first leg having an upper transistor (61) and a lower transistor (62) connected in series to each other, the second leg having an upper transistor (63) and a lower transistor (64) connected in series to each other, wherein:
    the transistors (61) and (62) are switched complimentarily with a PWM switching method having a predetermined career frequency and a PWM duty ratio of 50%;
    the transistors (63) and (64) are switched complimentarily with a PWM switching method having the predetermined career frequency and the PWM duty ratio of 50%; and
    the full-bridge inverter (6) controls a phase difference between gate voltages of the first leg and gate voltages of the second leg in order to control the field current.
PCT/JP2011/004341 2011-07-29 2011-07-29 Brush-less exciter and full-bridge inverter employed by the same WO2013018122A1 (en)

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PCT/JP2011/004341 WO2013018122A1 (en) 2011-07-29 2011-07-29 Brush-less exciter and full-bridge inverter employed by the same

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Application Number Priority Date Filing Date Title
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109936269A (en) * 2019-04-04 2019-06-25 沈阳理工大学 A kind of non-contact commutation power supply motor of three-phase alternating current wound rotor

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62185539A (en) * 1986-02-07 1987-08-13 Sawafuji Electric Co Ltd Brushless three-phase generator
WO2000007283A1 (en) * 1998-07-30 2000-02-10 Robert Bosch Gmbh Electrical motor, especially a three-phase alternator
JP2002186294A (en) * 2000-11-09 2002-06-28 Robert Bosch Gmbh Electric machine, particularly three-phase ac generator
JP2010045956A (en) * 2008-08-18 2010-02-25 Denso Corp Motor

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62185539A (en) * 1986-02-07 1987-08-13 Sawafuji Electric Co Ltd Brushless three-phase generator
WO2000007283A1 (en) * 1998-07-30 2000-02-10 Robert Bosch Gmbh Electrical motor, especially a three-phase alternator
JP2002186294A (en) * 2000-11-09 2002-06-28 Robert Bosch Gmbh Electric machine, particularly three-phase ac generator
JP2010045956A (en) * 2008-08-18 2010-02-25 Denso Corp Motor

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109936269A (en) * 2019-04-04 2019-06-25 沈阳理工大学 A kind of non-contact commutation power supply motor of three-phase alternating current wound rotor

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