DE102005024173A1 - Switching unit controlling and regulating method for e.g. proportional hydraulic valve of motor vehicle, involves separately adapting pulse width modulation ratios assigned to intermediately lying impulses by adjusted gradation for impulses - Google Patents

Abstract

The method involves constantly keeping a pulse width modulation (PMW) basic ratio (PMW-GV) under consideration of symmetry from intensification and retraction of PMW ratios (PMW-SV). The ratios (PMW-SV) are controlled and regulated such that the ratios (PMW-SV) assigned to impulses are raised or lowered. The ratios (PMW-SV) assigned to intermediately lying impulses are separately adapted by adjusted gradation for the impulses.

Description

The The invention relates to a method for controlling and / or regulating of switching elements, in particular for proportional hydraulic valves, with at least one coil, an armature and a control to realize the pulse-width modulation (PWM) or for processing and / or generating the drive signals of the switching element, wherein via a certain number of pulses have a pulse-width-modulation-base-ratio (PWM-GV) at least two specific pulse width modulation ratios (PWM-SV) is determined.

In the prior art, from which the invention proceeds, are for controlling switching elements in hydraulic systems in motor vehicles, in particular for the control of proportional hydraulic valves having a coil and an armature for processing and / or generating the control signals of the switching element certain methods, in particular the pulse-width modulation PWM known. This is vzw. determined over a certain number of pulses, a pulse-width modulation-base ratio PWM-GV from two specific pulse-width modulation ratios PWM SV, the two specific pulse width modulation ratios PWM SV for pulse widths Modulation fundamental ratio PWM-GV are different or shifted by a certain variation value. For example. In order to keep a valve in sliding friction, it is common that this constantly has to swing around the operating point. This is achieved by a high pulse width modulation frequency and corresponding specific pulse width modulation ratio (PWM-SV). A method is known in which the specific pulse-width-modulation ratio (PWM-SV) is constantly increased for a certain number of pulses and then lowered again for exactly as many pulses. This should be through 1 be made clearer.

1 shows a schematic representation of the known in the prior art method for controlling switching elements by means of the pulse-width modulation (PWM) and a variation value. In 1 It can be seen that a constant increase and decrease by means of a variation value of here 10% over a total of 10 pulses with "per n = 5 raised and n = 5 lowered pulses" is realized, namely the specific pulse width modulation ratio PWM-SV is 50% for the first 5 raised pulses and 30% for the second 5 lowered pulses 1 This curve is shown as a solid line with "PWM-SV." Constantly increasing and decreasing over a total of 10 pulses, the average value or pulse-width-modulation basic ratio PWM-GV is kept constant at 40% 1 is shown as a dashed line. The number of pulses is usually dependent on the set frequency and the resonance frequency of the controlled valve. In the prior art, the magnitude of the variation value has been adjusted so far that the valve oscillates.

Furthermore, it is known in the prior art that when using the pulse-width modulation or pulse inverters, in addition to the frequency and the current or voltage fundamental can be set on the inverter. The bridge branches of the pulse inverters are equipped with adjustable valves, for example transistors or GTO thyristors. The adjustment of the fundamental voltage is carried out by means of the pulse method. Best known here is the mentioned pulse width modulation (PWM). The pulse pattern generation is done so far in the prior art so that, for example, the harmonic content in the output variables is low and unwanted ordinal numbers do not occur as possible. Of the pulse methods best known is, for example, the sinusoidal method ( EP 1 099 828 A2 ) or also called undershoot method. A sinusoidal reference voltage is sampled accordingly. In accordance with the sampling ratio, a pulse width modulated output voltage is produced. Depending on the degree of modulation, the ratio of the peak values of the reference voltage and the scanning voltage, a linear increase in the output voltage fundamental oscillation occurs in the range between 0 and 1. The maximum pulse frequency is to be selected taking into account the permissible switching frequency of the semiconductor components used. If high pulse frequencies can be used, then the course of the motor current can always approach the sine curve better.

The design of these methods known in the prior art for the control of switching elements, in particular for proportional hydraulic valves is not yet optimal. When controlling valves, in particular proportional hydraulic valves with a constant variation value, that is to say with specific pulse width modulation ratios (PWM-SV), it is possible for the valves to become "stuck" or to increase noise, which not only leads to The disadvantage with the known methods is that at too high a pulse width modulation frequency, the valves of the Sliding into the static friction, which leads to the so-called "slip-stick effect". As a result, a response to a fine change in the control is no longer possible and this effect is referred to as "sticking." Furthermore, it is disadvantageous at low pulse width modulation frequency, the valve piston violently vibrates, so that it causes a strong noise in the upper and lower stop. In the medium frequency range, both problem cases occur in part, which again involves a problem with regard to controllability and, in turn, has a negative influence on the noise development and influences the wear, the service life and the maintenance costs. Furthermore, the control or controllability of the valves used in the prior art by disturbances easily influenced, which may lead to a failure or malfunction of the switching element, vzw. of the valve and thus could also result in an unsafe system state.

Of the Invention is therefore the object of the aforementioned Method for controlling switching elements, in particular for proportional hydraulic valves, in such a way and further develop that in the control of valves, in particular of proportional hydraulic valves Gluing the valves as well as the raised noise is avoided.

The previously indicated object is now achieved in that the control the pulse-width-modulation-base ratio under consideration a symmetry of amplification and return the respective specific pulse-width-modulation ratios on average of the considered impulses essentially constant, but the specific pulse width modulation ratios be controlled and / or regulated so that each one first pulse associated with specific pulse width modulation ratio raised and / or lowered and each associated with a last pulse specific Pulse-width modulation ratio is lowered accordingly far and / or raised, with the each intervening pulses associated with specific Pulse-width modulation ratios by means of adjustable grading for the respective pulse can be adjusted separately. The valve current reacts due to the inductances, vzw. For hydraulic valves accordingly slow to changes the specific pulse-width modulation ratio (PWM-SV). By the respective intervening pulses assigned specific pulse-width modulation ratios (PWM-SV) is adjustable by means of Grading for the respective pulse a separate adjustment of the vibration effect especially with a small pulse width modulation basic ratio (PWM-GV) realized. Here, the specific pulse width modulation ratio (PWM-SV) raised or lowered at each first pulse and at each lowered or raised last pulse accordingly and the one in between lying specific pulse width modulation ratios (PWM-SV) are adjusted step by step separately. Through this adaptation it avoids sticking of the valves and noise significantly reduced. This happens vzw. through the steeper current rise and steeper current drop at the same mean, thereby acting namely a stronger one Impulse on the anchor and this breaks easier or overcomes easier the stiction in the anchor guide. Vzw. The force acting on the armature is proportional to the electrical force Electricity in the coil. The anchor then becomes light by driving kept swinging at a certain position. Thus reduced the wear of the Switching element, vzw. of the valve and its life is increased as well reduced maintenance costs. This results in a faster increasing current during the increase or a faster sinking current during the Lowering in the pulse-width modulation. Due to the steeper current edges at constant pulse-width-modulation-basic-ratio (PWM-GV) he follows a sure swing of the valve piston even with a smaller Pulse width modulation basic ratio (PWM-GV) and a transition from the sliding friction is excluded, so far the known "slip-stick effect" not to bear comes. An improvement of the reaction to a subtle change the control is given and the controllability of the valve especially considering of disturbances clearly improved. additionally is the problem or danger at low pulse width modulation frequency the noise significantly reduced in the upper and lower stop of the valve piston. In the middle frequency range both problem cases and the difficult controllability are eliminated by the method according to the invention and thus the reliability is increased and reduces the risk of failures. As a result, the aforementioned disadvantages are avoided.

It There are different possibilities now Invention in an advantageous manner to design and develop. Therefor may first refer to the patent claim 1 and to the subordinate claims become. In the following, however, a preferred embodiment the invention with reference to the following drawings and the accompanying description be explained in more detail. In the drawing shows:

2 a schematic representation of the method according to the invention with a pulse-width modulation-basic ratio PWM-GV, taking into account a symmetry of amplification and withdrawal of the respective specific pulse-width modulation ratios PWM SV by means of sepa rat adjusted adjusted grading for the respective pulse.

In 2 is the pulse-width modulation-base ratio PWM-GV, taking into account a symmetry of amplification and withdrawal of the respective specific pulse-width modulation ratios PWM SV in the average of the considered pulses substantially constant. This is clearly visible by the dashed line at 40% PWM ratio.

However, the specific pulse-width modulation ratios PWM-SV are now controlled and / or regulated in such a way that the specific pulse-width-modulation ratio PWM-SV assigned to the respective first pulse is raised and / or lowered and that of the last pulse assigned specific pulse width modulation ratio PWM SV corresponding far lowered and / or raised, wherein the respective intervening pulses associated specific pulse width modulation ratios PWM SV are adjusted by means of adjustable gradation for the respective pulse separately , This is shown in 2 by the solid lines shown here, namely for every 2 × 5 pulses, namely for a total of 10 pulses (n = 5, n _Ges = 2 × n = 10).

The The disadvantages mentioned above are now also in particular avoided that by the steeper current increase or steeper Current drop at the same average a stronger impulse on the armature acts and this easier breaks loose or easier stiction in the anchor guide overcomes. The anchor is easily oscillated by the control according to the invention kept in a constant position.

The control, not shown here is a certain pulse-width modulation-basic ratio PWM-GV, in the example shown here this vzw. with 40% and as PWM-GV in 2 clearly shown. Furthermore, a constant variation value is provided here vzw. 10%. In addition, a maximum specific pulse-width-modulation ratio PWM-SV is set via a grading and, accordingly, a minimal specific pulse-width-modulation ratio PWM-SV results from this. This results in a corresponding respective curve for the specific pulse width modulation ratio PWM SV, which in 2 with PWM-SV and raised for the first 5 and the following 5 lowered pulses is shown.

The control not shown here can vzw. be designed as an electronic control unit, in particular as a microprocessor, so that hereby the corresponding current and voltage conditions in the system can be realized accordingly. The fundamental principle of the method according to the invention will now be explained.
At the here in 2 Pulse-width modulation PWM shown by way of example are taken into account in total 2 × n = 10 pulses, ie 2 phases of 5 pulses, plotted on the x-axis in FIG 2 , The y-axis shows the pulse width modulation ratio PWM.

Of another is here of a constant variation value of 10% in connection with a linear graduation assumed here of 7.5% different specific pulse width modulation ratios PWM-SV within the considered 2 × n = 10 pulses.

The first raised pulse is assigned a specific pulse-width modulation ratio PWM-SV. This is calculated from the pulse-width-modulation-basic-ratio PWM-GV (40%) + variation value (10%) + gradation (7.5%) · (n-1) / 2 to 65% and is in the 2 marked with "A".

The specific pulse-width modulation ratio PWM-SV assigned to the last of the five pulses in the first phase is lowered with the stepping (n-1) / 2. This results in the pulse-width modulation PWM of the last pulse, a special pulse-width modulation ratio PWM SV of pulse-width modulation-basic ratio PWM-GV (40%) + variation value (10%) - gradation (7 , 5%) · (n-1) / 2 to 35% as in the 2 marked with "B".

At the first lowered pulse (of the second 5 pulses), the associated PWM-SV specific pulse width modulation ratio is scaled down (7.5%) * (n-1) / 2 and is calculated to be 15% due to: pulse width modulation basic ratio PWM-GV (40%) - variation value (10%) - grading (7.5%) · (n-1) / 2 as in the 2 marked with "C".

Finally, at the last pulse of the second phase, the associated specific pulse width modulation ratio PWM-SV is increased with the stepping (7.5%) * (n-1) / 2, resulting in a value of 45%, namely PWM-GV (40%) - Variation value (10%) + grading (7.5%) · (n-1) / 2, in the 2 marked with "D".

In the pulse width modulation PWM method according to the invention, the specific pulse width modulation ratios PWM-SV of all the pulses between the first and the last of the ever because n = 5 pulses in this embodiment, interpolated stepwise linearly, vzw. for the two phases of 2 × n = 10 pulses, ie linearly interpolated for every 5 pulses.

Which in the illustrated example, the pulses of the first phase or the associated specific pulse width modulation ratios PWM SV a total reduction of 30%, namely from 65% to 35% and with the given after the initial first pulse remaining 4 increments gives a reduction of 7.5% per pulse or the specific pulse width modulation ratio PWM SV has an initial value of 65%, as in 2 represented with "A".

In the illustrated example results in the linear interpolation at the pulses of the second phase or the associated specific pulse width modulation ratios PWM SV an increase of a total of 30% (from 15% to 45%) and - after the first lowered Impulse - with the given remaining 4 increments an increase of 7.5% per pulse. The result is a specific pulse width modulation ratio PWM SV from the initial value of 15% as in 2 represented by "C" for the first lowered pulse.

Farther is beneficial for this embodiment, that by the predetermined pulse-width modulation PWM vzw. with proportional hydrauklik valves a nearly constant positioning of the armature is achieved and Thus, the aforementioned disadvantages are avoided. Furthermore becomes due to the predetermined pulse width modulation PWM at valves with return one Virtually constant force is exerted on the armature and the control holds at a constant Actuation of the valve piston in a nearly constant position. additionally the fundamental PWM frequency is kept far above the natural frequency and thus the mean coil current kept as constant as possible, so with the PVM ratio the same values can still be set.

Of Furthermore, the control preferably has a control function in the sawtooth and stops thereby swinging the anchor slightly on a nearly constant Position.

Conceivable are also versions where the gradation between the first and the last impulse of a Phase or the associated specific pulse width modulation ratio PWM SV not linearly interpolated, but also different functions to have a basis. For example, here the specific pulse width modulation ratio PWM SV on operating conditions individually ideally adapted separately.

PWM

Pulse-width modulation

PWM GV

Pulse-width modulation-background ratio

PWM SV

specific Pulse-width modulation ratio

A

the first specific pulse associated specific

Pulse width modulation ratio of the first phase

B

the specific pulse width assigned to the last pulse

Modulation ratio of first phase

C

the first lowered pulse associated specific

Pulse width modulation ratio of the second phase

D

the specific pulse width assigned to the last pulse

Modulation ratio of second phase

Claims (18)

Method for controlling and / or regulating switching elements, vzw. Valves, in particular for proportional hydraulic valves, having at least one coil, an armature and a control element for implementing the pulse-width modulation (PWM) or for processing and / or generating the control signals of the switching element, wherein over a certain number of pulses a pulse Wide-modulation basic ratio (PWM-GV) of at least two specific pulse-width modulation ratios (PWM-SV) is determined, characterized in that the control of the pulse width modulation basic ratio (PWM-GV) taking into account a symmetry of amplification and withdrawal of the respective specific pulse-width modulation ratios (PWM-SV) in the mean of the considered pulses is substantially constant, but the specific pulse-width modulation ratios (PWM-SV) controlled in such and / / or regulated, that each of a first pulse associated specific pulse width modulation ratio (PWM-SV) raised and / o which is lowered and the particular pulse-width-modulation ratio (PWM-SV) assigned to each last pulse is lowered and / or raised correspondingly, whereby the specific pulse-width-modulation ratios (PWM-) assigned to the respectively intermediate pulses SV) can be adapted separately by means of adjustable graduation for the respective pulse. Method according to Claim 1, characterized in that the control element has a specific pulse-width modulation basic ratio (PWM-GV). and specifies a constant variation value and, with the addition of a step, a maximum specific pulse-width-modulation ratio (PWM-SV) is set. Method according to one of claims 1 to 2, characterized that in pulse width modulation (PWM) a total of 2 × n pulses considered be, namely the PWM ratio for n pulses the first phase and the PWM ratio for subsequent n pulses of second phase is set. Method according to one of claims 1 to 3, characterized in pulse width modulation (PWM), a constant variation value in Connection with a linear graduation is realized and thus different specific pulse width modulation ratios (PWM-SV) within considered n pulses are given. Method according to one of claims 1 to 4, characterized that the specific pulse width modulation ratio (PWM-SV) assigned to the first pulse the first phase in addition the variation value and the gradation · (n-1) / 2 is raised. Method according to one of claims 1 to 5, characterized that in the pulse width modulation (PWM) of the first pulse of the first phase a specific pulse-width-modulation-ratio (PWM-SV) of pulse-width-modulation-base-ratio (PWM-GV) + variation value + Grading · (n-1) / 2 realized becomes. Method according to one of claims 1 to 6, characterized the specific pulse width modulation ratio (PWM-SV) assigned to the last pulse of the first phase lowered with the gradation · (n-1) / 2 becomes. Method according to one of claims 1 to 7, characterized that in pulse width modulation (PWM) of the last pulse of the first phase a special pulse width modulation ratio (PWM-SV) of pulse-width-modulation-basic-ratio (PWM-GV) + variation value - graduation · (n-1) / 2 realized becomes. Method according to one of claims 1 to 8, characterized in that the specific pulse width modulation ratio (PWM-SV) assigned to the first pulse of the second phase lowered with the gradation · (n-1) / 2 becomes. Method according to one of claims 1 to 9, characterized that in the pulse width modulation (PWM) of the first pulse of the second phase a special pulse width modulation ratio (PWM-SV) of pulse-width-modulation-basic-ratio (PWM-GV) - variation value - gradation · (n-1) / 2 realized becomes. Method according to one of claims 1 to 10, characterized the specific pulse width modulation ratio (PWM-SV) assigned to the last pulse of the second phase raised with the gradation · (n-1) / 2 becomes. Method according to one of claims 1 to 11, characterized that in pulse width modulation (PWM) of the last pulse of the second Phase a specific pulse-width modulation ratio (PWM-SV) of pulse-width-modulation-basic-ratio (PWM-GV) - variation value + Grading · (n-1) / 2 realized becomes. Method according to one of claims 1 to 12, characterized that in pulse width modulation (PWM) the respectively assigned special pulse-width modulation ratio (PWM-SV) of all n-pulses a phase between the first and the last impulse gradually is linearly interpolated. Method according to one of claims 1 to 13, characterized that by the given pulse width modulation (PWM) with proportional hydraulic valves a nearly constant positioning of the armature is achieved. Method according to one of claims 1 to 14, characterized that by the given pulse width modulation (PWM) in valves with Return one almost constant force is exerted on the anchor. Method according to one of claims 1 to 15, characterized that the control with appropriate control the valve piston holds a valve in a nearly constant position. Method according to one of claims 1 to 16, characterized that the fundamental PWM frequency far above the natural frequency of the each system is kept and the average coil current as possible is kept constant. Method according to one of claims 1 to 17, characterized that the control preferably has a control function in the sawtooth profile pretends and thereby the armature of a valve slightly swinging up a nearly constant position is maintained.