SE451355B - PROCEDURE AND DEVICE FOR REDUCING THE OVERTON CONTENT WHEN CONTROLING A SELF-CONTROLLED CONVERTER - Google Patents

Description

451 355 The invention is explained in more detail in connection with the exemplary embodiment illustrated in the drawings.

In the drawings, Fig. 1 shows a multiple diagram of different quantities over the minimum distance angle b ß ß proportional to fl, and more specifically E, in particular the different intermediate commutation angles0gßX¿ ..., of different harmonic measuring functions F1, F2, which are assigned control areas with different intermediate commutation numbers M1, M2. .. (attributed to a quarter period of the fundamental frequency fl) and serves to optimize the intermediate commutation phase angles in these areas, as well as a standardized fundamental frequency output voltage amplitude U1, and Fig. 2 a principle switch for performing an intermediate commutation switch according to Fig. 1.

In Fig. 1, four control ranges are indicated by A ° 4 = 3600. Tt. fl, i.e. also of f itself with a corresponding proportionality factor, between 0o and 15 with the intermediate commutation numbers M = 4, 3, 2, 1. In the practical example this essentially corresponds to a control of fl between 0 and 190 Hz, i.e. a large relative total control range , which so far has not been able to be realized without further ado with acceptable harmonic suppression. The above-mentioned limit values förw6 = K for switching between the different values of M are denoted medilya '3.5-2' '1. In principle, its switching limit values can also be predetermined by corresponding values of fl.

In the individual control ranges, corresponding to an optimal harmonic suppression, determined values or functional dependencies of the intermediate commutation phase angles of «s ° <are determined. This optimization finds its expression in the corresponding section of the harmonic measurement functions F4 ...

F1, in the case selected as an example, a square mean value (proportional to the root from the sum of the amplitude squares) of the harmonics.

Possibly also the per se known way the fi niax fi eldirr- k factor comes into consideration for these measuring functions. In a particularly advantageous manner, in the case chosen by way of example, the limit values Û 4 .... X'2 are determined as the intersection point abscesses for the functions F4 and F3 in riåïc 35§frrrrr and F3 and F2 and FZ and F1, respectively, so that an optimal total progress is obtained over the control area, because the measurement function values of adjacent areas correspond in the switching points.

The uppermost switching point at Åk corresponds to a transition until intermediate commutation-free basic frequency rate control with M = 0.

As shown in Fig. 1, the values of the intermediate commutation phase angles change from AIX = 0 with constant sections corresponding to the function F 4 to the point ¥ '4 in slightly curved areas, the distance angles A5 * of the commutation between them not falling below the minimum distance angle, as must be the case. Apart from the decreasing slope of the curved curve sections from ° 44¿ ... c itself for compliance with this condition. This means that the functions F4 .... Fl with its intersections are also largely optimized.

In the connecting control areas, the curves for the intermediate commutation phase angles change with approximation to the limit value according to -60 * in ascending sections, whereby in the last section it is moved to í'l on the straight boundary line AU = A ° <, ie also rises. In this way, the optimized overall course of the equipment is obtained. The introduced curve sections of Ul show that in the whole area a high basic oscillation yield is achieved.

In the circuit according to Fig. 2, the switching points at E1'1-4 are realized by limit value switches G1-G4, which are connected as differential generators to an input for A ° <and emit corresponding binary outputs to subsequent AND gates Al-A The latter are connected via corresponding inputs to pre-connected 4 difference limit value switches G5-G8, which are partly directly affected by a fl assigned signal and partly by predetermined limit values fT / 3, fT / 5, fT / 7, fT / 9. The latter correspond to the specified fractions of the maximum switching frequency fT and correspond to one of the observations of the distance condition of the intermediate commutations according to 4 $ 0C Independent optimization of the harmonic suppression. Thus, when the latter condition is uncritical, the limit values fT / 3 ....... fT / 9 only remain effective and enable even further optimization. In the switching according to Fig. 1, the reverse case is assumed.

The locking gates A5-A7 arranged after the AND gates A1-A4 provide a mutual locking of the limit value switches corresponding to the predetermined switching sequence. Finally, from the outputs of the logic circuit thus formed, the commutation signal transmitters KSU-KS4, which in a manner not described in more detail, emit commutation signals at angles 00 and 1800 (for the basic frequency timing), res5 = CÅ 1 ~ CX4 at each time in the appropriate combinations for the control ranges with M = 1 to M = 4.

Claims (7)

5,451,355 Claims A method for controlling a self-controlled growth rectifier with a variable fundamental frequency, in the event of a reduction in the harmonic voltage in the resulting output voltage or the output current within fundamental frequency pulses to predetermined phase commutations is controlled, wherein depending on a controlled change in the fundamental frequency (fl) or one of this unambiguously arranged quantity (Au) an automatic switching of the number of input commutations (M) opposite to the change of the fundamental frequency (fl) is carried out, the switching taking place in condition that at least one fundamental frequency limit value is exceeded, can be drawn that this fundamental frequency limit value is determined by the fact that before and after this switching the additional commutation phase and associated commutation phase angles (a1, a2 ..) of the harmonic harmonics are approximately equal. 2. A method according to claim 1, characterized in that square coefficients of the harmonic amplitudes (F1, F2 ..) are used as the harmonic measure. 3. A method according to claim 1 or 2, characterized in that in the upper control range of the fundamental frequency (fl) a switching is performed between pure fundamental frequency timing (M = 0) and a minimum value for the input commutation time (M = 1). Method according to one of the preceding claims, characterized in that the additional commutation phase angles within each case a basic frequency control interval, which is assigned to a certain additional commutation time (M), change as the distance angle (a1, a1, o3-) ) -in successive commutations tili one to the fundamental frequency (fl) proportioneii, minimum ti11- ïåten distance angle (Au), in accordance with an increasing control of the fundamental frequency (fl). A control device for performing the method according to claim 1, which device comprises a first commutation signal transmitter (KS0), which generates a first, predetermined number (M) of commutation signals for a predetermined phase position, and a binary logic switch, which has a limit value switch. ) which on the input side has a first control variable (Au) proportional to the fundamental frequency, characterized in that the control commutation of the first commutation signal (K50) is connected via an inverting means to the output of said limit value switch (G1). at least one second commutation signal sensor (ksl) is connected on the control side via a blocking means (A5) to the output of the first difference limit value switch (G1), which second commutation signal transmitter (KS1) determines a second predetermined number of commutation signals for the second phase (45). al), that between the first difference limit- v The ground switch (G1) and the inverting means and the second commutation signal transmitter (KS1), respectively, are connected to an AND gate (A1), which is connected on the input side, except with the output of the first difference limit value switch (G1), also with the output of a second di reference limit switch (G5), which is supplied with a second control variable (fl) corresponding to the ground frequency. Control device according to Claim 5, characterized in that the first difference limit value switch (G1) has a difference limit value (Y1), which is determined in dependence on the harmonic parameters (F1 ... F4), in particular in dependence on the square mean value of the harmonic amplitudes. . Control device according to Claim 5 or 6, characterized in that through the correlation signal transmitters (KS0, KS1) commutation signals are determinable with a mutual phase angle distance which is greater than a minimum permissible distance angle proportional to the fundamental frequency, in particular the minimum distance angle (Au).