DE19530622A1 - Torque control for railway vehicle rotary field machine - Google Patents

Abstract

The stator frequency of the rotating field machine is rapidly calculated by measuring the time between the change-over points in the stator frequency from a selected time. This provides a rapid measure of the instant torque which is compared with a required value of torque to determine the onset of wheel spin. The torque is determined by measuring the stator frequency over a set number of change-over points. At the onset of wheelspin the target torque is reduced to a modified level. If wheelslip is detected. ie. the wheel speed is less than that required for the actual speed of the vehicle, the target torque is increased.

Description

Technical field

The invention is based on a method for Torque control of a three-phase machine according to the generic term of claim 1.

State of the art

With the preamble of claim 1, the invention takes to a state of the art reference, as it comes from the German Company magazine: BBC-Nachrichten, 65 (1983) Heft 11, S. 375- 384, is known. Static frequency converters are used there Supply of squirrel cage motors after Undershoot process operated, where speed and Torque can be specified independently and independently can be changed continuously. The rotor speed is about Current transformers detected in the feed lines to the asynchronous machine and the machine control. The Rotor speed through filtering from the machine currents derived, resulting in an undesirable delay from about 20 ms regarding the availability of the current Rotor speed leads.

In addition to the relevant state of the art German magazine: etz Archive, Volume 7 (1985) Issue 7, pp. 211- 218, referred to a direct self-regulation (DSR) for highly dynamic three-phase drives with converter supply is known, as in the present invention for Application can come.  

A dissertation by Michael Jänecke at the Faculty of Electrical Engineering at the Ruhr University Bochum: "The direct self-regulation when used in the traction area", Bochum 1991, pp. 59-86, pointed out in the in addition to Self-regulation procedure also a procedure for indirect Self-regulation is given, as is the case with the present Invention can also be used.

Presentation of the invention

The invention as defined in claim 1 solves the task of a method for torque control Three-phase machine of the type mentioned above to develop further that this regulation is faster.

Advantageous embodiments of the invention are in the dependent claims defined.

An advantage of the invention is that a Intervention for a slip control of the Induction machine can be done quickly enough to a optimal power transmission at constant speed guarantee.

The frequency increase of the induction machine can be so strong be limited to a constant speed, regardless of the changing coefficient of friction between wheel and rail of a rail vehicle.

Brief description of the drawings

The invention is illustrated below with reference to embodiments play explained. Show it:

Fig. 1 is a schematic diagram of a torque control of an asynchronous machine,

Fig. 2 shows a torque characteristic of an asynchronous machine according to Fig. 1,

Fig. 3 frequency curves during acceleration and deceleration of the rotor speed of the asynchronous machine in accordance with Fig. 1,

Fig. 4 is a frequency to the curves of Fig. 3 belonging torque signal diagram,

Fig. 5 is a space vector of stator voltage and Flußraumzeigerbahnen for a direct self-regulation of the asynchronous machine in accordance with Fig. 1 and

Fig. 6 is a space vector for the stator voltage and Flußraumzeigerbahnen for indirect self-control of the induction of FIG. 1.

Ways of Carrying Out the Invention

In the figures, the same parts have the same reference numerals featured.

Fig. 1 shows in a functional circuit diagram for a torque control of a 3-phase rotating field machine or asynchronous machine (5) with alternating current phases (R, S, T) a torque controller (3) to which a modified target torque (M _set1) is supplied to the input side and the output side via a Inverter ( 4 ) controls the torque of the asynchronous machine ( 5 ). A rotor (not shown) of the asynchronous machine ( 5 ) is mechanically connected via a drive axle to a drive wheel set or to a drive wheel ( 6 ) of a rail vehicle, not shown, which can roll on a rail ( 7 ) or slip with high tractive power transmission.

The torque controller ( 3 ) can be operated with a direct self-regulation (DSR) as described in the publication etz Archiv (1985) pp. 211-217 mentioned at the beginning, or with an indirect self-regulation as described in the dissertation mentioned at the beginning is. On the output side, the torque controller ( 3 ) also supplies an actual value of the torque (M _ist ) for a higher-level control (not shown) and a measured or calculated stator frequency (f _x ), which is fed to the 1st and 2nd function transmitters ( 1 , 2 ) .

The 1st function generator ( 1 ) calculates depending on this stator frequency (f _x ) and on a z. B. predeterminable from the superordinate control target torque (M _soll) a maximum allowed stator frequency (f _xmax) in the running mode (F) according to:

f _xmax = f _x + _(S × M f _soll) / M _max + f _Smin (1)

and in the braking mode (B) according to:

f _xmax = f _x - (f _S × M _soll) / M _max -f _Smin. (2)

Here, f _{S means} a predeterminable rotor slip in the range of 0.5 Hz-5 Hz, which can depend on the characteristic (see FIG. 2) of the asynchronous machine ( 5 ), and f _Smin a minimally desired slip in the range of 0.5 Hz -5 Hz. The change in the maximum frequency (f _xmax ) is limited to a range of 0.1 Hz / s-1 Hz / s.

The second function generator (2) is calculated in dependence upon the stator frequency (f _{x) (to} M) of the target torque and the maximum allowed stator frequency (f _xmax) the modified target torque (M _set1) in driving (F) according to:

M _set1 = M _intended for f _x f _xmax and (3)

M _set1 = 0.1 × M _soll. . . 0.5 x M _{x intended} for f <f _xmax, (4)

compare the curve in FIGS. 3 and 4 between times (t1) and (t2),
and in the braking mode (B) according to:

M _set1 = M _intended for f _x f _xmax and (5)

M _set1 = 0.6 × M _should. . . 0.9 x M _{x intended} for f <f _xmax, (6)

compare the curve in FIGS . 3 and 4 between times (t8) and (t9). Then the value of M _{soll1 rises} to 100% in a ramp. The same applies to driving (F) after time (t5).

In Fig. 3, the frequency (f) and the abscissa represents time (t) is plotted on the ordinate. The maximum permitted stator frequency (f _xmax ) is shown in dashed lines and the rotor frequency (f _R ) of the asynchronous machine ( 5 ) and its stator frequency (f _x ) are shown in solid lines.

Fig. 4 shows the torque (M) in function of time (t) corresponding to the course of the maximum allowed stator frequency (f _xmax) in Fig. 3. In the driving (F), the target torque takes (M _soll) from a time point ( t1) to a time point (t2) the value 1 and then to a time point (t3) at a constant stator frequency (f _x) to 0. upon further increase in frequency until the time (t4), the target torque (M _soll) the value 1. as a result of spin (8) in the time interval t5-t4, wherein the stator frequency (f _x) is greater than the maximum allowed stator frequency (f _xmax) is softened, the modified target torque (M _{set1) (to} M) of the target torque down to values in the range of 10% -50% of the value of (M _soll ), in order to then rise again to 100% in the form of a ramp. In the area between times (t6) and (t7), the stator frequency (f _x ) remains unchanged and accordingly the target torque (M _soll ) at the value 0.

In the braking (B) state, the stator frequency (f _x ) decreases between times (t7) and (t10) and then after a time (t11), a sliding ( 9 ) occurring at a time interval t9-t8 at which the stator frequency (f _x ) is less than the maximum permitted stator frequency (f _xmax ). In this time interval, the value of the modified target _torque (M _soll1 ) changes from -1 to a value in the range of -0.4. . . Increased -0.9. After the time (t9), the value of the modified target _torque (M _soll1 ) _decreases again to the value -1 in the form of a ramp.

From the torque characteristic shown in FIG. 2, in which the torque (M) is plotted on the ordinate and the frequency (f) of the asynchronous machine ( 5 ) is plotted on the ordinate, that stator frequency (f _x ) that can be determined must be applied in order to generate a predeterminable torque (M1) at which a mechanical rotor frequency (f _R ) has the value (f _R1 ).

Fig. 5 shows the trajectory of the stator flow space pointer (ψ) for direct self-regulation of the asynchronous machine ( 5 ), the magnetic stator flux (ψ) being guided in a hexagon. In the case of a 3- phase asynchronous machine ( 5 ), which is fed by a constant DC input voltage, the space vector of the stator voltage (U) can only assume 7 discrete values, which are identified by switchover points (P0) - (P6). In each of the switchover points (P1) - (P6) the space vector of the stator voltage (U) remains 1/6 of the voltage period during stationary operation, ie during a time interval (Δts). The stator frequency (f _x ) can be determined from this according to:

f _x = 1 / (6 × Δts). (7)

The stator flow space pointer (ψ) moves on a straight line from the changeover point (P1) towards the changeover point (P2) when the space pointer of the stator voltage (U) from the changeover point (P0) to the changeover point (P3) is applied by the inverter ( 4 ), which is the has the same direction as a pointer from the switchover point (P1) to the switchover point (P2). If the space pointer of the stator voltage (U) is applied at the changeover point (P0), then the stator flow space pointer (ψ) stops. With the clock ratio of the space pointer points (P3) and (P0) the speed of the stator flow space pointer (ψ) can be specified. In order to detect the time interval (Δts), the time of switching, e.g. B. changeover point (P1), stored until the changeover point (P2) is reached, etc. at each changeover point of the hexagon. The time interval (Δts) is the result of the time difference.

Fig. 6 shows the trajectory of the stator flow space pointer (ψ) for an indirect self-regulation of the asynchronous machine ( 5 ), the magnetic stator flow pointer (ψ) being guided on a circle. The switchover points (P1) - (P6) correspond to the possible voltage points that can be applied to the asynchronous machine ( 5 ). The room pointer of the stator voltage U = 0 corresponds to the switchover point (P0). In order to be able to generate a specific operating point (Px), the voltage points (P1), (P2) and (P0) are clocked so that the resulting stator flux space pointer (ψ) points from the switchover point (P0) to the operating point (Px). In the event that the operating point should lie exactly in the middle between the switching points (P1) and (P2), the pulse duty factor of the voltage points (P1) and (P2) would be 1: 1.

In the area of indirect self-regulation, the asynchronous machine ( 5 ) rotates slowly, ie the stator flow space pointer (ψ) is slowly guided past 6 switching points (P1 ′) - (P6 ′) lying on a circle. It takes a long time until a new calculated value for the stator frequency (f _x ) is available again. As described above, additional switching points, e.g. B. (P12 ') in the middle between the 6 switching points (P1') - (P6 '), can be used to calculate the stator frequency (f _x ). So you get z. B. 12 switching points on the circumference at which a calculation of the stator frequency (f _x ) is possible. The time at which a changeover point is passed, e.g. B. (P1 ') saved. When passing the next switching point (P12 '), the time can be recorded again and a time difference or a time interval (Δts') can be calculated from this for the angle covered. The stator frequency (f _x ) can be determined from this according to:

f _x = 1 / (12 × Δts ′).

In this way, e.g. B. 24 switching points can also be generated if the pulse duty factor 1/4 : 3/4 or 3/4: 1/4 is evaluated.

Reference list

1 , 2 function transmitter
3 torque regulators for 5
4 inverters
5 asynchronous machine, induction machine
6 Drive wheel, drive wheel set of a rail vehicle
7 rail
8 Area of skidding while driving
9 area of sliding in braking
ASM asynchronous machine
B Brakes area
DSR direct self-regulation
f frequency
f1, f2 functions
f _R rotor frequency of 5
f _R1 rotor frequency for M1
f _x measured / calculated stator frequency of 5
f _xmax maximum permitted stator frequency
F Driving area
ISR indirect self-regulation
M torque
M1 specified torque of 5
M _{is the} actual value of the torque
M _should target torque of 5
M _target1 modified target _torque of 5
P0-P6, P1′-P6 ′, P12 ′ switching points of space pointers
Px operating point
R, S, T AC phases
t time
t1-t11 times
U voltage space pointer
Δts, Δts ′ time differences, time intervals
ψ magnetic flux

Claims (7)

1. Method for torque control of a three-phase machine

• a) _to a function of a predeterminable reference torque (M) and
• b) an electrically detected speed or frequency (f _x ) of the induction machine ( 5 ),
• c) wherein in the induction machine ( 5 ) a rotating field of a magnetic base (ψ) is generated by switching stator voltages (U) in predefinable switching points (P0- P6; P1'-P6 ', P12'),
  characterized,
• d) that the time period (Δts, Δts') between predetermined switchover points (P0-P6; P1'-P6 ', P12') measured and
• e) depending on this, a stator frequency (f _x ) of the induction machine ( 5 ) is calculated, depending on which the induction machine ( 5 ) is regulated.

2. The method according to claim 1, characterized in that the time period (Δts, Δts') measured at least between two successive switching points (P0-P6; P1'-P6 ', P12') and evaluated to calculate the stator frequency (f _x ) becomes. 3. The method according to claim 1 or 2, characterized in that the point in time at the beginning of an acquisition of the period (Δts, Δts') is stored. 4. The method according to claim 2 or 3, characterized in that the stator frequency f _{x is} calculated according to: f _x = 1 / (n × Δts), where n is the number of switching points (P0-P6; P1'-P6 ', P12' ) per full revolution of 360 ° and Δts mean the time interval between 2 successive changeover points (P0-P6; P1'-P6 ', P12'). 5. The method according to any one of the preceding claims, characterized in

• a) that the target torque (M _soll ) in the event of a skid ( 8 ) of the _{induction machine} ( 5 ) is reduced to a modified target _torque (M _soll1 ) and
• b) is increased in the case of sliding ( 9 ).

6. The method according to claim 5, characterized in

• a) that the target torque (M _Soll ) in the event of a skid ( 8 ) of the induction machine ( 5 ) by 10%. . . 50% reduced to a modified setpoint _torque (M _set1 ) and
• b) in the case of sliding ( 9 ) by 10%. . . 40% is increased.

7. The method according to claim 5 or 6, characterized in that

• a) that skidding ( 8 ) is detected when the stator frequency (f _x ) is greater than a predeterminable, maximum permitted stator frequency (f _xmax ), and
• b) that sliding ( 9 ) is detected when the stator frequency (f _x ) is less than the maximum permitted stator frequency (f _xmax ).