Electricity: power supply or regulation systems – External or operator controlled – Phase controlled switching using electronic tube or a three...
Patent
1997-04-28
1998-08-18
Sterrett, Jeffrey L.
Electricity: power supply or regulation systems
External or operator controlled
Phase controlled switching using electronic tube or a three...
323237, 323241, 323320, G05F 1455
Patent
active
057962456
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a process and a device for controlling the electric power supplied to a load powered by an AC voltage source via a system of generalized phase adjustment.
Prior art techniques used to control a loaded power adjuster either divide the supply voltage of the sector according to a phase angle that can be set as a function of the required power while the load is being supplied, or control, in the so-called wave train method, by altenrnately placing the load in circuit and then out of circuit according to a frequency selected by the user.
The first control mode by phase division, when the control power called full wave is high, prevents a whole range of phase angle adjustments which in turn leads to current harmonics that are too high which obstructs users connected to the same power source.
As to the second control mode, the so-called wave train, it is seen to be unusable particularly for control of the speed of electric motors for vacuum cleaners or washing machines, for example. Thus, such a control leads to variations of speed generating noise that are very annoying to the users.
As can be seen in FIGS. 1 and 3, the conventional phase control, applied either to a resistive load, or to a slightly inductive load such as a motor, consists in dividing an AC voltage from a power source, such as for example the conventional network U=230V.50 Hz, according to an invariable phase angle .alpha..sub.0 corresponding to a duration t.sub.0 during which the AC current is zero. This repetition of the phase angle permits obtaining a predetermined power for the necessary duration of use. So as to obtain several powers, the angle can be varied by means of a conventional variable switch, for example of the TRIAC type.
FIG. 2 shows a sinusoidal supply voltage U of the same type as shown in FIG. 1 and divided according to a wave train comprising a duration t.sub.3 during which the load of the resistive type is supplied, followed by a duration t.sub.4 during which the supply of the load is interrupted. This type of supply is suitable for resistive loads of the heating type but is not suitable for resistive loads of the lighting type or inductances of the electric motor type because it gives rise to variations of voltage which generate frequencies of the motor in troublesome spectra, either visible, giving rise to sparking, or acoustical and vibratory, giving rise to impermissible noise.
The diagram shown in FIG. 4 shows a curve traced according to Standard EN60555-3, showing the relative variations of voltage .DELTA.U/U as a function of the number of these variations per second, this curve delimiting an authorized region located between itself and the axis of the abscissae and in which the FLICKER effect is at an acceptable level.
The table of FIG. 5 comprises, in a first column, the order of the different harmonics, and in the second column the effective current limitations imposed particularly by Standard EN60555-2.
SUMMARY OF THE INVENTION
The object of the invention is to overcome these drawbacks and to satisfy particularly the standards concerning the limitation of disturbances imposed on the circuits by electrical apparatus particularly the Standards EN60555-2, CEI555-2, as well as their modifications EN61000-3-2 and CEI1000-3-2, limiting the levels of harmonic currents, and the Standards EN60555-3, CEI555-3, as well as their modifications EN61000-3-3 and CEI1000-3-3, limiting the relative variations of voltage as a function of the number of these variations per time unit for an impedance source defined by the standard and which are the cause of disturbances known as "FLICKER".
According to a predetermined set power, there is delivered successively to the load, periodically, a sequence of a whole number p of elements, p being greater than one, each element, of number i, of the sequence being characterized by a whole number of n.sub.i of periods T during which the AC voltage U is divided symmetrically according to a phase angle .alpha..sub.i corresponding to a
REFERENCES:
patent: 4528494 (1985-07-01), Bloomer
patent: 4567425 (1986-01-01), Bloomer
patent: 5519311 (1996-05-01), Widmayer
Beaulieu Alain Bernard Marc
Chapellier Laurent
Epinat Pierre
Moulinex S. A.
Sterrett Jeffrey L.
LandOfFree
Process and device for controlling the power of a load via a pha does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process and device for controlling the power of a load via a pha, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process and device for controlling the power of a load via a pha will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1117775