Electricity: motive power systems – Synchronous motor systems – Hysteresis or reluctance motor systems
Patent
1998-07-22
2000-01-11
Ro, Bentsu
Electricity: motive power systems
Synchronous motor systems
Hysteresis or reluctance motor systems
318254, 318448, H02P 505, H02P 306
Patent
active
060140011
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for supplying a variable reluctance motor with electronic switching. It also relates to a supply circuit for practicing this process.
The supply of DC current of a variable reluctance motor with electronic switching from a mono-phase power supply generally uses a rectifier stage and a converter stage comprising electronic switching means that is driven from instructions and positional information from detectors, to supply the different phases of this motor. The present invention relates more particularly to the case of variable reluctance motors with electronic switching supplied from a capacitor of the C-Dump type with current monitored as shown for example in the article "Switched Reluctance Drives: New Aspects", IEEE Transactions on Power Electronics, Volume 5, No. 4, October 1990.
It is to be noted that in present processes for supplying a motor with electronic switching, and particularly in the supply process used for the C-Dump type converter, the rectified current delivered by the rectifier stage is subject to disturbances with multiple frequencies of the frequency sector. These disturbances can lead to exceeding the harmonic values of current permitted by the European standard CEI 555-2. At present, this problem is handled by filtering the current delivered by the rectifier stage so as to eliminate current harmonics higher than the frequency of the sector. There is inserted for example a passive filter (based on filters L, C) or an active filter (of the PFC: "Power Factor Correction" type), between the rectifier stage and the converter stage, as shown for example by the article "Effect of Power Factor Correction Circuit on Switched Reluctance Motor Drives for Appliances" by R. KRISHNAN and S. LEE, APEC 94, Volume 1, Orlando, Feb. 13-17, 1994. The addition of a filter upstream of the converter stage however leads to a significant increase in electronic costs when the powers to be controlled exceeds several hundred Watts.
The object of the invention is to overcome these drawbacks by providing a process to supply a variable reluctance motor with electronic switching, which permits satisfying both the requirements of low cost and respect for the harmonic limit levels imposed by the mentioned European standard.
These objects are achieved by a process for supplying a variable reluctance motor with electronic switching from a single phase AC voltage source, comprising: AC source to supply a rectified voltage, from the rectifier stage toward said phase to which is applied the rectified voltage by closing switching means associated with said phase, said phase toward a storage condenser common to all the phases, while said switching means is opened, and rectifier stage by control of chopping means in series with the storage capacitor.
According to the invention, the process comprises monitoring the energy return toward the rectifier stage, so as to correct disturbances of the rectified supply current.
It thus becomes possible to correct the disturbances of the supply current and to be in conformity with the present requirements as to compatibility of electromagnetic material, without having to use systematically a passive or active filter upstream of the converter stage, and by using in a rational manner the energy resources normally present in the condenser of a converter of the C-Dump type. There results a significant economic gain relative to known solutions.
There is meant more generally by disturbance of the current, any deformation of the current wave relative to a reference current wave, this deformation being able to be induced by any physical phenomenon identified or not, of an origin internal or external to the drive system in question.
Disturbances of the rectified supply current can for example be corrected relative to a reference current wave. In a particular embodiment of the process according to the invention, the monitoring of the returned energy comprises a modulation of the cyclic chopping ratio. It can be provided for example that this cyclic rati
REFERENCES:
patent: 5115181 (1992-05-01), Sood
patent: 5424624 (1995-06-01), Senak, Jr.
patent: 5710699 (1998-01-01), King et al.
patent: 5742146 (1998-04-01), Langhorst
Krishnan et al., "Effect of Power Factor Correction Circuit on Switched Reluctance Motor Drives for Appliances", Proceedings from the Annual Applied Power Electronics Conference and Exposition, Orlando Feb. 13, 1994, vol. 1 pp. 83-89.
Ehsani et al., "Development of a Unipolar Converter for Variable Reluctance Motor Drive", IEEE Transactions on Industry Applications, vol. IA-23, No. 3, May 1987, pp. 545-552.
Moulinex (S.A.)
Ro Bentsu
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