Electricity: motive power systems – Positional servo systems – With particular 'error-detecting' means
Reexamination Certificate
2000-09-06
2002-12-24
Dang, Khanh (Department: 2837)
Electricity: motive power systems
Positional servo systems
With particular 'error-detecting' means
C318S254100, C318S715000
Reexamination Certificate
active
06498451
ABSTRACT:
TECHNICAL FIELD
The invention is directed to electric power steering systems, particularly towards a torque ripple free system for electric power steering.
BACKGROUND OF THE INVENTION
Electric power steering (EPS) has been the subject of development by auto manufacturers and suppliers for over a decade because of its fuel economy and ease-of-control advantages compared with traditional hydraulic power steering. However, commercialization of EPS systems has been slow and is presently limited to small and midget-class cars due to cost and performance challenges. Among the most challenging technical issues is the annoying pulsating feel at the steering wheel and the audible noise associated with the type of high performance electric drives needed to meet the steering requirements.
SUMMARY OF THE INVENTION
The so-called “Torque-Ripple Free” (TRF) system is an advanced electric drive concept, which was devised with the specific objectives of reducing the motor torque pulsation and audible noise in electric power steering systems to ultra-low levels comparable to those experienced in cars equipped with hydraulic power steering systems. In theory, and under ideal conditions, the new concept should produce no torque ripple at all, and hence the name. However, due to practical limitations discussed below, some low levels of torque ripple unavoidably remain.
The key elements of the TRF electric drive concept include:
(a) A sinusoidal drive to reduce commutation torque ripple to ultra-low levels. This is accomplished by:
(1) A sinusoidal inverter/controller to switch currents into the three-phases to be in synchronism with the rotor at all times. The currents are controlled to have sinusoidal waveforms
(2); Permanent magnets designed to produce a sinusoidal magnetic field distribution in the windings region of the machine, thus inducing voltages in the machine windings of sinusoidal waveforms, and
A low cost, higher resolution position sensor to provide the controller with accurate rotor position information, necessary to control the current waveform to the desired sinusoidal shape.
(b) An electrical machine with slotless winding to eliminate both cogging torque and pulsating radial forces.
FIG. 3
illustrates a schematic of the TRF motor cross-section for illustration.
(c) A composite iron stator yoke to replace laminated yoke and eliminate its associated whining noise. It simultaneously functions also as a housing for the stator, thus reducing the stator manufacturing cost and defraying some of the added cost of the more expensive magnet and position sensor required for this concept.
(d) A composite reinforced plastic rotor core and shaft, which is another cost saver because it can be molded to shape instead of machined. In addition it will help with lowering the rotor inertia due to its lower density compared with steel, thus compensating for the increased inertia due to a needed larger magnet. While using a plastic rotor core tends to reduce its torsional stiffness, it is found to yield acceptable angular strain.
(e) A gear reduction box with a high gear ratio to reduce the motor size and cost.
REFERENCES:
patent: 3898544 (1975-08-01), Tanikoshi
patent: 3919609 (1975-11-01), Klautschek et al.
patent: 4027213 (1977-05-01), De Valroger
patent: 4135120 (1979-01-01), Hoshimi et al.
patent: 4217508 (1980-08-01), Uzuka
patent: 4240020 (1980-12-01), Okuyama et al.
patent: 4392094 (1983-07-01), Kiihnlein
patent: 4447771 (1984-05-01), Whited
patent: 4511827 (1985-04-01), Morinaga et al.
patent: 4556811 (1985-12-01), Hendricks
patent: 4558265 (1985-12-01), Hayashida et al.
patent: 4628499 (1986-12-01), Hammett
patent: 4633157 (1986-12-01), Streater
patent: 4686437 (1987-08-01), Langley et al.
patent: 4688655 (1987-08-01), Shimizu
patent: 4745984 (1988-05-01), Shimizu
patent: 4780658 (1988-10-01), Koyama
patent: 4789040 (1988-12-01), Morishita et al.
patent: 4814677 (1989-03-01), Plunkett
patent: 4835448 (1989-05-01), Dishner et al.
patent: 4837692 (1989-06-01), Shimizu
patent: 4868477 (1989-09-01), Anderson et al.
patent: 4868970 (1989-09-01), Schultz et al.
patent: 4882524 (1989-11-01), Lee
patent: 4912379 (1990-03-01), Matsuda et al.
patent: 4988273 (1991-01-01), Faig et al.
patent: 4992717 (1991-02-01), Marwin et al.
patent: 5006774 (1991-04-01), Rees
patent: 5040629 (1991-08-01), Matsuoka et al.
patent: 5063011 (1991-11-01), Rutz et al.
patent: 5069972 (1991-12-01), Versic
patent: 5076381 (1991-12-01), Daido et al.
patent: 5122719 (1992-06-01), Bessenyei et al.
patent: 5223775 (1993-06-01), Mongeau
patent: 5239490 (1993-08-01), Masaki et al.
patent: 5331245 (1994-07-01), Burgbacher et al.
patent: 5345156 (1994-09-01), Moreira
patent: 5349278 (1994-09-01), Weeden
patent: 5361210 (1994-11-01), Fu
patent: 5428285 (1995-06-01), Koyama et al.
patent: 5433541 (1995-07-01), Hieda et al.
patent: 5444341 (1995-08-01), Kneifel, II et al.
patent: 5460235 (1995-10-01), Shimizu
patent: 5461293 (1995-10-01), Rozman et al.
patent: 5467275 (1995-11-01), Takamoto et al.
patent: 5469215 (1995-11-01), Nashiki
patent: 5475289 (1995-12-01), McLaughlin et al.
patent: 5493200 (1996-02-01), Rozman et al.
patent: 5517415 (1996-05-01), Miller et al.
patent: 5554913 (1996-09-01), Ohsawa
patent: 5568389 (1996-10-01), McLaughlin et al.
patent: 5569994 (1996-10-01), Taylor et al.
patent: 5579188 (1996-11-01), Dunfield et al.
patent: 5585708 (1996-12-01), Richardson et al.
patent: 5616999 (1997-04-01), Matsumura et al.
patent: 5623409 (1997-04-01), Miller
patent: 5625239 (1997-04-01), Persson et al.
patent: 5642044 (1997-06-01), Weber
patent: 5656911 (1997-08-01), Nakayama et al.
patent: 5668721 (1997-09-01), Chandy
patent: 5672944 (1997-09-01), Gokhale et al.
patent: 5701065 (1997-12-01), Ishizaki
patent: 5739650 (1998-04-01), Kimura et al.
patent: 5760562 (1998-06-01), Woodland et al.
patent: 5777449 (1998-07-01), Schlager
patent: 5780986 (1998-07-01), Shelton et al.
patent: 5803197 (1998-09-01), Hara et al.
patent: 5811905 (1998-09-01), Tang
patent: 5852355 (1998-12-01), Turner
patent: 5867380 (1999-02-01), Lee
patent: 5881836 (1999-03-01), Nishimoto et al.
patent: 5898990 (1999-05-01), Henry
patent: 5919241 (1999-07-01), Bolourchi et al.
patent: 5920161 (1999-07-01), Obara et al.
patent: 5929590 (1999-07-01), Tang
patent: 5962999 (1999-10-01), Nakamura et al.
patent: 5963706 (1999-10-01), Baik
patent: 5977740 (1999-11-01), McCann
patent: 5984042 (1999-11-01), Nishimoto et al.
patent: 5992556 (1999-11-01), Miller
patent: 6002226 (1999-12-01), Collier-Hallman et al.
patent: 6002234 (1999-12-01), Ohm et al.
patent: 6008599 (1999-12-01), Beck
patent: 6009003 (1999-12-01), Yeo
patent: 6013994 (2000-01-01), Endo et al.
patent: 6034460 (2000-03-01), Tajima
patent: 6034493 (2000-03-01), Boyd et al.
patent: 6043624 (2000-03-01), Masaki et al.
patent: 6049182 (2000-04-01), Nakatani et al.
patent: 6104150 (2000-08-01), Oohara et al.
patent: 6129172 (2000-10-01), Yoshida et al.
patent: 6184638 (2001-02-01), Kinpara
patent: 6281659 (2001-08-01), Giuseppe
IEEE, Low Cost Phase Current Sensing in DSP Based AC Drives, Francesco Parasiliti, et al., 7/99.
IEEE, Single Current Sensor Technique in the DC Link of Three-Phase PWM-VS Inverters, Frede Blaabjerg et al., vol. 35, No. 5, Sep./Oct. 1997.
Conference Record of the IEEE Catalog No. 87CH2499-2, Oct. 18-23, 1987.
Conference Record of the IEEE Catalog No. 87CH2565-0, Oct. 2-7, 1988.
Brown Boveri Review, vol. 51, No. 8/9, Aug./Sep. 1964.
Power Electronics, vol. 8, Jan. 1993.
Power Electronics, vol. 8, Apr. 1993.
IEEE Translations on Industry Applications, vol. 25, Jan./Feb. 1989.
Bernard Bruno Patrice
Boules Nady
Chen Shaotang
Henry Rassem Ragheb
Namuduri Chandra Sekhar
Anderson Edmund P.
Dang Khanh
Delphi Technologies Inc.
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