ELECTRIC ACTUATOR WITH A REFINED CASCADE CONTROL UNIT
BACKGROUND OF THE INVENTION The invention relates to an electric actuator consisting of a first actuator body, a second actuator body that is mounted by means of pivots with respect to the first actuator body through an angle of rotation on the actuator. an axis of rotation, electric power mechanisms for executing an electromagnetic torque in the second actuator body, and an electric control unit for controlling the rotation angle of the second actuator body, said control unit consists of an electrical input to receive an electrical signal corresponding to the required angle of rotation of the second actuator body and an electrical output to supply an electrical signal corresponding to the electrical current required through the energy mechanisms. The invention also relates to a sealing apparatus for use in an air inlet of an internal combustion engine, which sealing apparatus consists of a neck valve case, an air passage that is connectable with the air inlet, a neck valve that is attached to the neck valve housing so that it can be mounted by means of pivots in the air passage, and an electric actuator to pivot the neck valve. An electric actuator of the type mentioned in the introduction paragraph is discovered in chapter 15.2 entitled "Linear Position Control", from the book "Control of Electric Drives", by W. Leonhard, ISBN 3-540-13650-9 Springer- Verlag Berlin New York Tokyo. The known actuator control unit has a so-called cascade control structure consisting of a system of several control loops superimposed for the electromagnetic torques, the angular acceleration, the rotation speed and the rotation angle of the actuator. actuator The control loop for the electromagnetic torque consists of a control piece with an electrical input for receiving an electrical signal corresponding to a required angular acceleration and an electrical output for supplying an electrical signal corresponding to the electric current required through the energy mechanisms. The cascade control structure provides a natural control sequence that corresponds to the structure and operation of the actuator. As a result, the cor.trol unit has a transparent structure and can be designed and optimized step by step. A. The disadvantage of the known actuator is that the response of the known actuator control unit to changes in the signal corresponding to the required angle of rotation is relatively slow if the dependence of the electromagnetic, magnetostatic or mechanical characteristics of the actuator on the angle rotation of the second actuator or of the current through the energy mechanisms is strongly non-linear. Due to non-linearity characteristics, the number of iterative calculations that have to be made by the control unit before a required angle of rotation is alceed, is relatively high. OBJECTIVES OF THE INVENTION It is an object of the invention to provide an electric actuator of the type mentioned in the introductory paragraph having a control unit with a cascade control structure, wherein the response time of the cascade is improved. '.a control unit to alterations of the signal corresponding to the required angle of rotation. According to the invention, the electric actuator is characterized in that the control unit comprises a first control piece with an electrical input to receive the signal corresponding to the required electromagnetic torque and an electrical output to supply an electrical signal corresponding to the the electromagnetic torque required in the second actuator body, and a second control part with an electrical input to receive the signal corresponding to the required electromagnetic torque and an electrical output to supply the signal corresponding to the required current. Due to the use of said first and second control parts, the control unit consists of a refined control sequence in which the signal corresponding to the required angle of rotation is first converted into a signal corresponding to the electromagnetic torque required by the first control piece and subsequently the signal corresponding to the moment The required torque is converted into a signal corresponding to the current required through the energy mechanisms by the second control piece. In this way, the first control piece allows a specific calculation of the required electromagnetic torque, taking into account the mechanical and magnetostatic properties of the actuator, while the second control piece allows a specific calculation for the required current taking into account the Electromagnetic properties of the actuator. Since the properties of the actuator, on the other hand, are taken into account separately, knowledge of these properties of the actuator is taken into account in a detailed and relatively specific manner, so that the calculations of the first and second control pieces are relatively accurate , and the cooperation between the first and second control parts is very effective. In this way, the number of iterative calculations that have to be made by the control pieces is limited before a required angle of rotation is reached. A particular embodiment of an electric actuator according to the invention is characterized in that the first control part consists of an electric adder with an electrical output to supply the signal corresponding to the required electromagnetic torque, the adder consists of a first electrical input to receive the front power control signal, determined by the signal corresponding to the required rotation angle, and a second electrical input to receive a feedback control signal determined by the signal corresponding to the required rotation angle and by a signal The electric motor is supplied by a rotational angle sensor and corresponds to a measured angle of rotation of the second actuator body. By adding such forward feed and feedback control signals, a fast and accurate calculation and control of the required torque is achieved. Another embodiment of the electromagnetic actuator according to the invention is characterized in that the first control part consists of a profile generator having a first electrical input for receiving a signal corresponding to the measured rotation angle, and an electrical output for supplying a reference electric signal corresponding to the angle of rotation profile versus the time coefficient emitted by the profile generator, the front power control signal is proportional to the required angular acceleration of the second actuator body corresponding to the profile of angle of rotation against time. The rotation angle profile against time generated by the profile generator extends from the measured rotation angle to the required angle of rotation. In this way, a discontinuous, instantaneous alteration of the signal corresponding to the required angle of rotation is converted by the profile generator into a profile of the reference signal that is feasible in view of the controllability and dynamic properties of the electric actuator. A special embodiment of the electric actuator according to the invention is characterized in that the first control piece consists of a comparator having a first electrical input to receive the signal corresponding to the measured rotation angle, a second electrical input to receive the reference signal, and an electrical output to supply a differential signal that is proportional to a difference between the signal corresponding to the measured angle of rotation and the reference signal, the first control piece also consists of a regulator with an electrical input for receive the differential signal and an electrical output to supply the feedback signal of feedback. Said regulator determines the feedback control signal in such a way that said differential signal, is equal to zero, so that the measured angle of rotation changes precisely according to the angle profile of rotation versus time, generated by the profile generator - by having the regulator control that differential signal instead of a signal that is proportional to the difference between the signal corresponding to the measured angle of rotation and the signal corresponding to the required angle of rotation, it is achieved that the so-called winding effects and track overruns of the regulator can be avoided. A particular embodiment of an electric actuator according to the invention is characterized in that the adder consists of a third electrical input to receive an electrical signal corresponding to a load torque that is executed in the second actuator body, and which is dependent on the angle of rotation of the second quadrant of the actuator and substantially independent of the current through the energy mechanisms. The load torque is executed in the second actuator body, for example, by means of a pneumatic, magnetic or mechanical device such that a mechanical spring deforms when the second actuator body is mounted by pivots. , and is used, for example, to restore u: second actuator body to a rest position when the current through the energy mechanisms is zero. The addition of an electrical signal corresponding to a torque of load to the foregoing feed and feedback control signals mentioned above results in that the forward feed control signal does not have to be calculated to include a component of the moment of electromagnetic torsion necessary to compensate for said moment of torsion of load. In this way, the response time and the accuracy of the control unit are improved. Another embodiment of an electric actuator according to the invention is characterized in that the load torque is a moment of magnetostatic torque which is executed in the second actuator body by the first actuator body. Said moment of magnetostatic torsion is a moment of magnetic torsion that is executed by the first body of the actuator in the second body of the actuator independently of the current through the energy mechanisms. The moment of magnetostatic torsion is dependent on the angle of rotation of the second actuator body and constitutes a restoring torque which drives the second actuator body towards the rest position. Since the moment of magnetostatic torsion is determined by the structure of the first and second bodies of the actuator, the signal corresponding to the torque of load can be calculated as a function of the angle of rotation of the second body of the actuator. A special embodiment of an electric actuator according to the invention is characterized in that the first control piece consists of an electrical memory with an electrical input to receive the signal corresponding to the measured rotation angle and an electrical output to supply the signal corresponding to the At the moment of torsion of load, the nemoria is provided with a tabular relationship between the torque of load and the angle of rotation. Because the relationship between the load torque and the angle of rotation of the second actuator body is loaded in said memory of the first control piece in tabular form, the value of the load torque is relatively accurate and Read in a simple way without substantial delay. In this way, the response time and the accuracy of the control unit are improved. Another embodiment of an electric actuator according to the invention is characterized in that the first control piece consists of a disturbance observer for calculating a loadable torsional moment executed in the second actuator body on the basis of a mathematical model of an actuator. electric actuator, the adder consists of a third electrical input to receive an electrical output signal from the disturbance observer corresponding to a value of the charging torque calculated by the disturbance observer. During the operation, the angle of rotation of the second actuator body is influenced or disturbed by the internal torsional moments of disturbance, such as friction or torsional moments of the electric actuator bearings, and by the moment of magnetostatic torsion executed in the second actuator body by the first actuator body, and by external torsion loading torque moments executed in the second actuator body. Such perturbation load torques are not directly measurable or measurable only with great difficulty. The perturbation observer calculates the total torque of the disturbance load on the basis of a mathematical model of the electric actuator, i.e. on the basis of a group of first-order differential equations describing the physics of the electric actuator. The addition of the disturbance observer's output signal to the feedback front feed control signal results in the feedback control signal not needing to be II
calculated by the regulator of the first control piece, to include a component of the required electromagnetic torque required to compensate for the torque of disturbance. In this way, the convergence time of the feedback control loop and, consequently, the response time of the control unit is greatly improved. A particular embodiment of an electric actuator according to the invention is characterized in that the first control piece consists of an electrical limiter for limiting the signal corresponding to the required electromagnetic torque if said signal exceeds a predetermined limit value. In this way, the value of the required electromagnetic torque, to be generated by the energy mechanisms, is limited to the value that is feasible in view of the thermal, electrical, mechanical properties of the actuator, which avoids an over-torque of electromagnetic torsion, which could result in damage or malfunction of the actuator. Another embodiment of the electric actuator according to the invention is characterized in that the second control part consists of an electrical memory with a first electric input to receive the signal corresponding to the electromagnetic torque, a second electrical input to receive the corresponding signal At the measured angle of rotation, and an electrical output to supply the signal corresponding to the required current, the memory is provided with a tabular relationship between the electromagnetic torque, the angle of rotation and the current. Because the moment of electromagnetic torsion is determined by the structure of the first and second actuator bodies and the energy mechanisms, the signal corresponding to the required electromagnetic torque can be calculated as a function of the rotation angle of the second body of the actuator. actuator, and the electric current through the energy mechanisms. Due to the relationship between the electromagnetic torque, the rotation angle of the second actuator body and the current through the energy mechanisms, the second control part is stored in a tabular form in said memory. Current value is relatively accurate and is read in a simple form without substantial delay. In this way, the time and precision of the control unit are also improved. A special embodiment of an electric actuator according to the invention is characterized in that the control unit consists of a comparator having a first electric input to receive the signal corresponding to the required current, a second electric input to receive a electrical signal that is supplied by means of an electric current sensor and that corresponds to a current measured through the energy mechanisms, and an electrical output to supply a differential signal that is proportional to the difference between the corresponding signal the required current and the signal corresponding to the measured current, the control unit also consists of a regulator with an electric input to receive said differential signal and an electrical output to supply an electrical signal corresponding to an electric current supplied to the mechanisms of energy. Said comparator, current sensor and regulator belong to a control loop of the control unit. Said regulator determines the corresponding signal of the electric current supplied to the energy mechanisms in such a way that said differential signal is equal to zero, so that the current measured through the energy mechanisms is precisely equal to the current determined by the control unit . Another embodiment of an electric actuator according to the invention is characterized in that the disturbance observer has an electrical input to receive the signal corresponding to the current measured through the energy mechanisms, the disturbance observer calculates the angle of rotation , an angular velocity the second actuator body, and the load torque M
at the base of three state equations for the electric actuator. The signal corresponding to the measured current is supplied by the current sensor which is used in the current control loop of the control unit. Because the control unit consists of a current control loop, the value of the current through the electric power actuator mechanisms is imposed by the current control bucl2 and not by the electrical voltage. imbedded in the energy mechanisms. In this way, the value of the current through the energy mechanisms is prescribed by the current control loop, so that the mathematical model of the actuator that underlies the disturbance observer can supply a differential equation for the current as a function of a imposed voltage. Due to these reasons the mathematical model consists only of three equations, the disturbance observer is relatively simple and appropriate for an online computation. Another incorporation of an electric actuator according to the invention is characterized in that the disturbance observer consists of another electrical input to receive the signal corresponding to the measured angle of rotation, a comparator to determine a deviation between the measured angle of rotation and the angle calculated for rotation, and an adder to correct the calculated angle of rotation, the calculated angular velocity and the load torque calculated by a value proportional to said deviation. In this embodiment, the inaccuracies of the values of the angle of rotation, the angular velocity and the torque of load calculated by the perturbation observer and caused by the inaccuracies of the mathematical model that underlies the disturbance observer, are corrected by means of a feedback loop. The corrected angle of rotation is the sum of the calculated angle of rotation and the product of such deviation and a first weight factor, the corrected angular velocity is the sum of the calculated angular velocity and the product of said deviation and a second weight factor , and the corrected load torque is the sum of the corrected load torsion moment and the product of said deviation and a third weight weight, the first, second and third weight factors are determined by means of a called, pole positioning method. A particular embodiment of an electric actuator according to the invention is characterized in that the control unit consists of an electrical limiter that limits the signal corresponding to the current if the signal exceeds a predetermined limit value. In this way, the value of: the electric current through the energy mechanisms is limited to a value that is feasible in view of the thermal properties of the energy mechanisms, in order to avoid an overcurrent, which could give as a result, overheating of the power and actuator mechanisms. An obturator apparatus of the type mentioned in the introductory paragraph is characterized in that the electric actuator applied thereto is an electric actuator according to the invention. The sealing apparatus is used in an air inlet of an internal combustion engine of a vehicle and is adjustable, for example, by means of an accelerator pedal. The accelerator pedal is not mechanically coupled to the sealing collar of the sealing apparatus, but the electric actuator has an electrical input for receiving an electrical signal corresponding to a desired angle of rotation of a sealing collar in the air passage of the sealing apparatus, said electrical signal is supplied, for example, by an electronic motor steering system that also controls the fuel injection and ignition systems of the internal combustion engine. The angle of rotation of the sealing collar in the outlet passage of the sealing apparatus is adjusted by means of the engine steering system not only as a function of the position of the accelerator pedal, but also as a function of, for example, the r.p.m. of the machine, the pressure and temperature of the air inlet, and the temperature of the machine. In this way, the performance, fuel consumption and composition of the exhaust gases of the internal combustion engine are improved. Because the sealing collar of the sealing apparatus is operated by means of an electric actuator according to the invention, the angle of rotation of the sealing collar required by the motor steering system is reached in a precise manner and the response time which is necessary to carry out the alterations of the required angle of rotation is strongly limited.
BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be explained in more detail below, with reference to the drawings in which: Figure 1 shows diagrammatically a sealing apparatus according to the invention, used in an air inlet of an internal combustion machine . Figure 2a is a cross section of an electric actuator according to the invention, applied in the sealing apparatus of Fig. 1, in a condition without power, Figure 2b shows the electric actuator of Fig. 2a in a condition with Figure 3 schematically shows a control unit of the electric actuator of Fig. 2a, Fig. 4a shows a profile of angle of rotation against the time generated by a profile generator of the control unit of Fig. 3, Fig. 4b shows a profile of angle of rotation against the time generated by a profile generator of the control unit of Fig. 3, Fig. 4c shows an angular acceleration profile against the time corresponding to the profile of rotation angle against the time of Fig. 4b, Fig. 5 schematically shows an alternative control unit of an electric actuator of Fig. 2a, and Fig. 6 shows schematically a perturbation observer of the alternative control unit of figure 5. DETAILED DESCRIPTION OF THE INVENTION The sealing apparatus shown in Fig. 1, shows a box 1 of the sealing collar with a tubular air passage 3 and a rim 5 by means of which the sealing apparatus can be connected to an air or multiple inlet of an internal combustion machine not shown in the drawing. The sealing apparatus further comprises a disc-shaped neck valve 7 which is mounted on a shaft 9 extending in the diameter through the air passage 3. The shaft 9 is stiffened by means of pivots in the rim 5 of the neck 1 of the neck valve, so that the valve 7 of the roller is mounted by means of pivots in the air passage 3. When the neck valve 7 is mounted by means of pivots, the opening of the air passage 3 and the air flow to the combustion chambers of the internal combustion machine are altered. The neck valve 7 is mounted by means of pivots in the air passage 3 by means of an electric actuator 11 consisting of a first actuator body 13 which is mounted in an actuator box 15 of the valve housing 1 neck and a second actuator body 17 which is mounted on the shaft 9. As shown in Figs. 2a and 2b, the second actuator body 17 consists of a cylindrical permanent magnet rotor body 19 which is magnetized in its diameter and has a north N pole and a south S pole. The first body 13 of the actuator consists of a 21-shaped stator body; A fact of material that has a high magnetic permeability, such as sintered iron, or magnetic steel sheets. The U-shaped stator body 21 consists of two flanks 23, 25 which are interconnected by a base 27. The electric actuator 11 further comprises energy mechanisms 2 having an electric coil 31 which is held by the base 27. The flanks 23, 25 of the body 21 stator, each is provided with pole shoes 33, 35; each of the pole shoes 33, 35 has a surface 37, 39 curves. As shown in Figs. 2a and 2b, the surfaces 37, 39 curves of the pole shoes 33, 35 surround the permanent magnet rotor body 19, the surface 37 defines an air space 41 between the rotor body 19 and the pole shoe 33 and the surface 39 defining an air space 43 between the rotor body 10 and the pole shoe 35. In addition, a first space 45 and a second space 47 are present between the pole shoes 33, 35, while a first slot 49 is provided centrally on the surface 37 of the pole shoe 33, and a second slot 51 is centrally provided. on the surface 39 of; the shoe 35 of polo. In this way, the surface 37 is divided into a first surface portion 53 and a second surface portion 55, and the surface 39 is divided into two.n a first surface portion 57 and a second surface portion 59, while the air space 41 is divided into a first air space portion 61 and a second air space portion 63, and the space 43: air is divided into a first portion 65 of air space and a second portion 67 of air space. As shown in Figs. 2a and 2b, the width of the opposite portions 61, 67 of air spaces of the diameter, is less than the width of the opposite portions 63, 65 of air space of the diameter. Because the width of the air gap portions 61, 67 is less than the width of the air gap portions 63, 65, a magnetostatic torsion moment TMS is executed by the first actuator body 13 in the second body 17 of the actuator, actuating the second body 17 of the actuator to a rest position, shown in Fig. 2a when the electric coil 31 has no power. To increase the magnetostatic torsion moment TMS, the auxiliary permanent magnets 69, which are indicated in Figs. 2a and 2b, with broken lines, may alternatively be mounted on the first portion 53 of the surface of the pole shoe 33 and on the second surface portion 59 of the pole shoe 35. When the coil 31 is energized, an electromagnetic moment TEM is executed in the second actuator body 17, and the second actuator body 17 is pivotally mounted from the rest position shown in Fig. 2a to a position shown in Fig. 2b, which is characterized by a rotation angle F of the second body 17 of the relative actuator with the rest position. Leaving the external forces of the neck valve 7 out of consideration, the electromagnetic torsion TEM mo is equated to the torque TMS of torsion in the position shown in Fig. 2b. When the current through the coil 31 is turned off, the second body 17 of the actuator and the neck valve 7 will return to its rest position, again under the influence of the moment TMS of magnetostatic torsion. The value of the angle of rotation F in the position shown in Fig. 2b is determined by the value of the electric current through the electric coil 31 and is adjustable by adjusting the current through the coil 31 in the manner which is described below. It should be noted that the rest position of the electric actuator 11 shown in Fig. 2a does not correspond exactly to the position occupied by the second body 17 of the actuator, and the neck valve 7 when the electric bobina 31 has no power . As shown in Fig. 1, the sealing apparatus also consists of a mechanical stop 71, and the second body 17 of the actuator consists of a cam 73 which rests against the stop 71 when the coil 31 has no emergy. The position of the second body 17 of the actuator e: which the cam 73 rests against the stop 71, differs slightly from the position of the second body 17 of the actuator shown in figure 2a, so that the cam 73 rests against the stop 71 under the influence of the moment TMS.O. of magnetostatic torsion. As shown in Fig. 1, this position corresponds to a so-called weak position of stay of the neck valve 7 in the air passage 3 which differs slightly from the so-called idle position of the neck valve 7 in whose opening of air passage 3 is minimal. In the weak stay position of the neck valve 7, which occurs, for example, when the electrical power supply of the sealing apparatus fails, the opening of the air passage 3 allows a small flow of air to the combustion chambers of the neck. the internal combustion machine, so that the emergency operation of the machine is possible. The stop 71 is mechanically adjustable, so that the air flow through the passage 3 gives air in the weak stay position of the neck valve 7 is adjustable. In the other positions of the neck valve 7, including the idle and total seal positions, in which the opening of the passage 3 is minimum and maximum, respectively, an electric current is supplied through the coil 31. As shown in Fig. 1, an electric actuator 11 also it consists of a control unit 75 by means of which the rotation angle F of the neck valve 7 is controlled. The control unit 75 is shown diagrammatically in FIG. 3 and consists of an electrical input 77 for receiving an electrical signal uf corresponding to the required rotation angle F of the second body 17 of the actuator and of the valve 7 of neck, and an electrical outlet 79 for supplying an uc signal that determines an electric current through the power mechanisms 29 of the actuator 11. The uf signal is supplied by means of an electronic engine management system of the combustion engine. internal system, whose system is not shown in the drawing. The 2?
The motor steering system determines the value of the uf signal not only as a function of the position of an accelerator pedal operated by a driver, but also as a function of other parameters such as, for example, r.p.m. from . "The machine, the pressure and temperature of the air inlet, and the temperature of the machine, and the machine management system controls the speed of the machine during and after a cold start of the machine. , so that the usual airflow systems are not necessary.The engine management system also controls the fuel injection and the ignition devices of the machine.This way, the operation of the fuel injection is synchronized, ignition and shutter apparatuses of the machine, so that the performance, fuel consumption and composition of the exhaust gases of the machine are improved.As also shown in Fig. 3, the control unit 75 consists of a first control piece 81 and a second control foot 83. The first control piece 81 consists of an electrical input 77 of the control unit 75 and an output 85 to supply a UEM signal corresponding to a mome. The TEH electromagnetic torsion required to be executed in the second body 17 of the actuator. The second control piece 83 consists of an electrical input 87 for receiving the signal UEM of the first control part 81 and an electrical output 88 for supplying an ut signal corresponding to an electric current required through the mechanisms 29. of energy. As shown in Fig. 3, the first control part 81 consists of a profile generator 89 with a first electric input 91 for receiving the uf signal and a second electrical input 93 for receiving the uff signal corresponding to a measured angle. of rotation of the second body 17 of the actuator and of the neck valve 7. The uff signal is supplied by a rotation angle sensor 95 of the shutter apparatus through a common high frequency filter 97. As shown in Fig. 1, the rotation angle sensor 95 is mounted in the neck valve housing 1 near an end of the shaft 9 which is remote from the electric actuator 11. The profile generator 89 generates a rotation angle profile against time that extends from the current measured angle of rotation FM to the required rotation angle FR. Fig. 4a shows an example of an angle of rotation profile versus time required by the engine steering system wherein the angle of rotation discontinuously alters from FM to FR at a time point t0. Such a profile can not be realized by the electric actuator 11 because the electromagnetic torque is infinitely high. Fig. 4b shows the angle profile of rotation against time generated by the profile generator 89 where the angle of rotation runs smoothly from FM FR between time points t0 and t:. Fig. 4c shows a profile of angular acceleration against time corresponding to the profile of rotation angle versus time of Fig. 4b. The profile generator 89 consists of a first electrical output 99 to supply a forward power control signal luFF which is the product of an angular acceleration required in accordance with the profile of angular acceleration against time and a moment of inertia of the mountable parts by pivots of the sealed device. Therefore, the signal uFF corresponds to an electromagnetic torque component necessary to perform said angular acceleration. The profile generator 89 also consists of a second electrical output 101 for supplying a reference electric ufR signal corresponding to the rotation angle profile against time generated by the profile generator 89. In this way, an instantaneous alteration signal uf, which is supplied by the motor steering system, is converted by means of the profile generator 89 into profiles of the forward power control signal uFF and the uR signal of reference which are feasible only in view of the dynamic properties of the electric actuator 11 but also in view of the controllability of the actuator 11.
As also shown in Fig. 3, a first control piece 81 consists of a comparator 103 with a first electrical input 105 for receiving the signal uff and a second electrical input for receiving the reference signal ufR. The comparator 103 consists of an electrical output 109 that supplies a differential uDF signal, which is proportional to the difference between the signals uff and ufR. The uDf signal is supplied to an electrical input 111 of an L13 PID regulator which also consists of an electrical output 115 for supplying a feedback control uFB signal. The forward power control signal uFF and the feedback control signal u? B are supplied to a first electrical input 117 and a second electrical input 119, respectively, of an electric adder 121 of the first control piece 81. As shown in Fig. 3, the adder 121 further comprises a third electrical input 123 for receiving an electrical UMS signal corresponding to a TMS moment of estimated magnetostatic torque performed by the first body 13 of the actuator in the second body. 17 of the actuator. The value of the magnetostatic torsion moment TMS which drives the second body 17 of the actuator and the neck valve 7 towards the weak position of stay as discussed above, depends on the rotation angle F and is substantially independent of 2H
the current through the energy mechanisms 31. The ratio TMg and F is determined by the structure and composition of the first and second bodies 13, 17 of the actuator. Said ratio is calculated or measured and stored in a tabular form in an electrical memory 125 of the first control part 81, said memory consists of an electrical input 127 for receiving the signal uFF and an electrical output 129 for supplying the uMS signal to the adder 121. By storing the relationship between the magnetostatic torque and the angle of rotation in a tabular form in said memory 125, it is achieved that the value of the magnetostatic torque is read in an imprecise and relatively simple manner without delay substantial In this way, the supply of the uMS signal to the adder 121 does not increase the response time of the control unit 75. The adder 121 consists of an electrical output 131 for supplying the electric emu signal corresponding to the electromagnetic torque to be executed in the second body 17 of the actuator. The uEM signal is the mathematic sum of the signals uFF, uFB, uMS. In this way, the required electromagnetic torsion torque TEM is the sum of an electromagnetic torque component that is necessary to perform the required angular acceleration of the neck valve 7, the estimated magnetic moment of torque TMS, and the Torque moment component 2")
Electromagnetic feedback represented by the uFB signal. The PID regulator 113 determines the signals UFB and UEM in such a way that the differential signal uDF is set equal to zero, so that the measured angle of rotation of the neck valve 7 changes precisely in accordance with the angle of rotation profile against time generated by profile generator 89. Because the comparator 103, as is common, does not determine a difference between the signals uff and uf, but determines the difference between the signals uff and uf, the control of the uFB and uEM signals by the PID controller 113 is very stable, so that the normal winding effects and the dynamic overflow of the 113 PID regulator do not occur. In addition, the control of the UFB and UEM signals by the PID controller 113 is very fast as a result of the adder 121. Because the uFF and uMS signals are added to the uFB signal, the 113 PID regulator does not need to calculate the component. at the moment of electromagnetic torsion necessary to realize the required angular acceleration of the neck valve 7 and the torque component necessary to compensate the TMS moment of magnetostatic torsion. The calculation of these components of electromagnetic torsion moments by the PID controller in a feedback control bail will not demand several times of control samples, the ratio between the magnetostatic torque TMS and M is greater.
the angle of rotation F is strongly non-linear, so that the response time of the control unit 75 is not impaired and the instability of the PID controller increases. With the adder 121, the 113 PID regulator need not calculate only a number of components of electromagnetic torques that are less in relation to the Torques mentioned above, as a component that compensates for airflow forces and a component that compensates for mechanical friction forces. In this way, the response time and accuracy of the control unit 75 are improved.
988345'738475'3847 • As shown in Fig. 3, the first control part 81 further consists of an electrical limiter 133 for limiting the uEM signal when the uEM signal exceeds a predetermined limit value. Said limit value of the signal EM is determined in such a way that the electromagnetic torsion moment executed in the second body 17 of the actuator in the neck valve 7 never exceeds a predetermined maximum value of torque. In this way, mechanical damage or malfunction of the electric actuator 11 as well as overheating of the energy mechanisms 29 are avoided. When the uEM signal supplied by the adder 121 exceeds said predetermined limit value, the value of the uEM signal is adjusted to said limit value by the limiter 133. As also shown in Fig. 3, the second part 83 control of the control unit 75 consists of an electrical memory 135 with a first electrical input 137 for receiving the uEM signal from the input 87 of the second control part 83, and a second electrical input 139 for receiving the uf signal from the angle-of-rotation sensor 95, and an electrical output 141 for supplying the electric signal Uj corresponding to the electric current through the electric coil 31 of the energy mechanisms 29 necessary to achieve the electromagnetic torsion moment TEM. The value of the EM moment of electromagnetic torsion depends on the angle F of rotation of the second body 17 of the actuator and the value of the electric current through the coil 31. The relation between the electromagnetic torsion moment TEM, the angle of rotation F and ICL current through the coil 31 depends on the structure and composition of the first and second bodies 13, 17 of the actuator and of the energy mechanisms 29. Said ratio is calculated or measured and is stored in a tabular form in the memory 135. In this way the value of the current necessary to reach a required electromagnetic torque at the measured angle of rotation, ss reads from the memory 135 in a precise and simple form without substantial delay. It should be noted that the calculation of a current required by a normal computer would yield a substantial amount of time, greater as the ratio between the electro-magnetic torque, the angle of rotation and the current is strongly non-linear. With the use of the memory 135, the short response time of the control unit 75 that is obtained by means of the PID controller 113, in combination with the adder 121, is not deteriorated by the second control piece 83. The control unit 75 further comprises a comparator 143 having a first electrical input 145 for receiving the signal t from the output 88 of the second control piece 83, a second electrical input 147 for receiving a signal u ?: electric which corresponds to the electric current measured through the energy mechanisms 29, and an electrical output 149 to supply a signal uD1 that is proportional to the difference between the signals ut and u? t. The signal u] X is supplied by means of a current sensor 151 through a common filter 153 of high frequency. The current sensor 151 measures the electrical current that is supplied to the power mechanisms 29 by an energy end stage 155 of the electric actuator 11. In Fig. 3, the current sensor 151 and the power end stage 155 are only shown in 1 *
diagramatic form. In addition, the control unit 75 consists of a regulator 157 PI with an electric input 159 for receiving a differential signal uD1 and an output 161 for supplying a signal u'j corresponding to the electric current to be supplied by the power mechanisms 29 through; the energy end stage 155. The regulator 157 P] determines the signal u'x in such a way that the differential signal uD1 is equalized to zero, so that the measured current that was supplied by the current end stage 155 to the energy mechanisms 29 equals the required current determined by the second control piece 83. As also shown in FIG. 3, the power end stage 155 of the electric actuator 11 is powered by a constant electrical voltage, for example, a battery. The power end stage 155 consists of four NPN transistors, ie, two upper transistors 163, 165 and two lower transistors 167, 169, and two electric inverters 171, 173. Transistors 163, 165, 167, 169 and inverters 171 , 173, are interconnected in a usual bridge configuration. The transistors 163, 165, 167, 169 are driven in a common way by a pulse width modulator 175 of the control unit 75, which consists of a first electrical input 177 for receiving the signal u'I (supplied by the regulator 157 PI and a second electric input 179 to receive the signal ul t supplied by the current sensor 171. A first output 181 of the pulse width modulator 175 is connected to the base of the lower transistor 167 and through the inverter 171 to the base of the upper transistor 163, while a second electrical output 183 of the pulse width modulator 175 is connected to the base of the lower transistor 1.69 and through the inverter 173 to the base of the upper transistor 165. The signal u'x is The pulse width modulator 175 is converted into mutually complementary signals driven by pulses uc Y ~ uc in the first and second electrical outputs 181 and 183, respectively, of the modulator 1. 75 of pulse width. Depending on the polarity of the signals uc and -uc, the lower transistor 167 and the upper transistor 165 open where an electrical current in the mechanisms 29 of; energy is admitted in one direction, or the lower transistor 169 and the upper transistor 163 open where an electrical current in the energy mechanisms 29 is admitted in an opposite direction. The pulse width modulator 175 further comprises an electric limiter for limiting the pulse width of the signals uc and -uc when the signal -uc supplied to the current sensor 151 exceeds a predetermined limit value. In this way, the pulse width of an electric current through the coil 31 is limited to a value that is feasible in view of the thermal properties of the energy mechanisms 29. In this way, an overcurrent in the coil 31 is prevented, which could lead to overheating of the energy mechanisms 29 and the electric actuator 11. The control unit 75 described above has the cascade control structure according to which the signal uf corresponding to the required angle of rotation is first converted into a signal corresponding to the required angular acceleration, the signal corresponding to the angular acceleration The required signal is subsequently converted into a UEM signal corresponding to the required electromagnetic torque, and the UEM signal corresponding to the required electromagnetic torque is finally converted into a ux signal corresponding to an electric current required through the energy mechanisms 29. . As described above, this cascade control structure refined with the first and second control parts 81, 83 allows a specific calculation of the required electromagnetic torsion moment TEM, taking into account the mechanical and magnetostatic properties of the electric actuator 11, and a specific calculation of the required current, taking into account the electromagnetic properties of the actuator 11. This structure of con-
The refined cascade troll leads to a response time of the control unit 75 which is short in relation to the common and usual control structures according to which the required current is calculated in an iterative manner by means of a loop of feedback control without or with few intermediate control steps. Said structures: common and usual could require a greater number of iterative calculations and therefore result in a very long response time, particularly because the relationship between the required current and the angle of rotation is strongly non-linear. In the control unit 75 described above, the third input 123 of the adder 121 receives the electrical uMS signal corresponding to a magnetostatic torque moment TMa executed by the first body 13 of the actuator in the second body 17 of the actuator. The TMS moment of magnetostatic torsion is an internal load torsion moment that influences or perturbs the angle of rotation of the second body 17 of the actuator and the neck valve 7. The angle of rotation of the second body 17 of the actuator is also disturbed by other internal torsional load moments such as friction and the torsional moments of fixing the bearings of the electric actuator 11. The angle of rotation of the second body 17 of the actuator is also disturbed by means of torsional moments of external load axis: in the second body 17 of the actuator and of the neck valve 7, as a torsional moment. caused by the air flow forces performed on the control valve 7, by the air flowing through the air passage 3. Figure 5 shows an alternate control unit 185 of an electric actuator 11 in which the electrical memory 1.25 of the control unit 75 is replaced by a so-called disturbance observer 187 for calculating the torque of the charge of perturbation. total executed in the second body 17 of the actuator and the neck valve 7 at the base of a mathematical model of the sealing apparatus and of the electric actuator 11. The disturbance observer 187, which will be described in more detail below, consists of an electrical output 189 for supplying a uCLT signal corresponding to a load torque value calculated by the perturbation observer 187. Said uCLT signal is supplied to a third input 123 of the adder 121. With the use of the disturbance observer 187, a direct measurement of the disturbance load torque is avoided, which is very difficult or even impossible. Also, the. PID regulator 113 does not need to calculate the component of the electromagnetic torque needed to compensate for the total torque of the disturbance load torque executed in the second body 17 of the actuator and the neck valve 7. With the perturbation observer 187, the PID regulator 113 only needs to calculate a relatively small deviation between the calculated load torque and the load torque that is currently influencing the neck valve 7 and the second body 17 of the actuator In this way, the response time and the accuracy of the control unit 185 are improved. As mentioned above, the disturbance observer 187 is used to calculate the load torsion moment executed in the second body 17 of the actuator and the neck valve 7 with the base of a mathematical model of the sealing apparatus and the electric actuator 11, so that you: avoid a difficult and unreliable measurement of the torque load. The mathematical model that supports the observer 187 of perturbation is based on a group of three differential equations of the first degree that are read as follows: J.d? / Dt = K (F). IACT - TCARGA (1)? = dF / dt (2) dTCPRGA / dt = 0 (3) Equation (1) is an equation of the movement of the valve 7 of the neck and of the second body 17 of the actuator, where J is the moment of inertia of the parts mounted by pivots of the shutter,? is the angular velocity of the parts mounted by pivots of the sealing apparatus, k (F). IACT is the moment of torsion T EM executed in the second body 17 of the actuator, k (F) is a factor that depends on the angle of rotation F and IACT is the current through the energy mechanisms 29, and TCARGA is the torsion moment executed in the neck valve 7 and the second body 17 of the water carrier. Equation (2) describes the relationship between speed? angle and the angle F of rotation of the neck valve 1. Equation (3) consists of an assumption for the moment of torsion of load, principally that the torque of load torque is constant. Due to the value of the IACT current through the energy mechanisms 9 it is determined by the 157 PI regulator of the. control unit 75 and not by the electrical voltage by which the end power stage 155 of the electric actuator 11 is powered, the mathematical model that supports the perturbation observer 187 may function with a fourth differential equation describing a relationship between the current through the energy and voltage mechanisms: imposed on the energy mechanisms 29. As shown in FIG. 5, the disturbance observer 187 has a first electrical input 191 for receiving the signal u?: Supplied by the current sensor 151 and corresponding to the electric current measured through the devices 29 of energy. The disturbance observer 187 calculates the rotation angle F, the velocity? angular, and the MEOST TCARGA of the torque of load on the basis of the input signal uIS and the three differential equations (1), (2) and (3) mentioned above. Because: the mathematical model that supports the disturbance observer 187, consists of only three differential first-degree equations, the disturbance observer 187 is relatively simple and appropriate for on-line computation. In the form of structure, the group of equations (1), e as follows:
.k (F) .1 ACT.
In addition, the disturbance observer 187 is based on the following formulas: Fk + l Fk T "?? klr + T2 / 2J. k (F). IACT - T2 / 2J. TCARGA? K + l ~? K + T / J. k (F). IACT - T / J. Tauta; where Fk + 1 and? k + 1 are the values of the angle of rotation and the angular velocity calculated by the observer 187 of perturbation at a time point k + 1, where Fkf? k and TCARGA are l ° s values of the angle of rotation, the angular velocity and the load torque calculated by the perturbation observer 187 at a time point k, where T is a time interval between the time points k and k + 1. With these formulas, the group of equations (1), (2), and (3) in the form of a structure are read as follows xk +? = F-X + H.k (F) .IACT
The vectors xk and xk + x are the state vectors for the time points k and k + 1, the structure Fes the structure of the system and the structure H is the input structure. Equations (1), (2) and (3) are implemented in the disturbance observer 187 in the form of a computer program. Fig. 6 diagrammatically shows the disturbance observer 187 in the form of a number of function blocks representing the computer program. As mentioned above, the disturbance observer 187 consists of a first electrical input 191 for receiving the uXI signal corresponding to the IACT current through the energy mechanisms 29. In addition, the disturbance observer 125 comprises a second electrical input 193 for receiving the signal uff corresponding to a measured angle of rotation. The uf signal is used by the disturbance observer 187 in a manner to be described later. As shown in Fig. 6, disturbance observer 187 consists of a first function block 195 for multiplying the IACT value by a constant K-factor that represents an average value of the factor k (F). Alternatively, function block 195 may contain a relation between k (F) and F, for example, in tabular form, in which case function block 195 consists of an input 197 for receiving an input uf signal. In Fig. 6, alternative entry 197 is shown with a broken line. The disturbance observer 187 further comprises a second function block 199 for multiplying the input structure H by the K.IACT value or by the value k (F) .IA-T, an output of the function block 199 representing the Hk value (F) .IAct. The disturbance observer 187 further comprises a third function block 201 for summing the vector H.k (F). IACT and the vector xcorr to be described hereafter, an output of the third function block 201 represents the new state of the vector xk + 1. In addition, the disturbance observer 187 comprises a fourth function pad 203 for supplying the TCARGAk + 1 component of the new state vectorxk + 1 to the output 189 4.3
of the observer 187 of disturbance. In addition, the function of the fourth block 203 brings the vector xk + 1 to a fifth function block 205 that multiplies the vector xk + 1 by the structure of the system F. An output of the fifth function block 205 represents the F value .xk. As described above, the disturbance observer 187 calculates the values of the rotation angle F, the angular velocity? and the moment T ^ a ^ on the basis of the group of equations (1), (2) and (3). Because the value of the rotation angle F is also measured by the rotation angle sensor 95, the measured value of the rotation angle can be used to correct inaccuracies of the mathematical model supporting the perturbation observer 187 and the inaccuracies of the formulas of equations (1), (2) and (3). For this purpose, the disturbance observer 187 consists of a sixth function block 207 for comparing the measured value of the rotation angle represented by the input signal uFF and the value Fk + 1 of the angle of rotation that is supplied by the fourth block 203 of function. An output value? F of the sixth function block 207 corresponds to a deviation between said measured rotation angle and said calculated rotation angle and leads to a seventh function block 209 that multiplies the corrective structure by the value? F. The corrective structure hx consists of a first weight factor Lx, a second factor L2 and a third factor L3 of weight to correct respectively the calculated value of the angle of rotation, the calculated value of the angular velocity, and the calculated value of the torque of load, said weight factors are determined by means of of a so-called method of pole positioning that is known and usual per se. An output vector L.?F of the seventh function block 209 leads to an eighth function block 211 of the disturbance observer 187 which is used to sum the output vector L.? F of the seventh function block 209 and the F.xk vector In this manner, the vector XCORR of the eighth function block 211 is read as follows: XCORR = F. xk + L.? F;
, L = L3 Therefore, the new state vector is read as follows: xk + 1 = F.xk + H.k (F). ? ACT + L.? F. In the electric actuator 11 described above, the first actuator body 13 executes a magnetostatic torque in the second actuator body 17, said magnetostatic torque being dependent on the rotational angle. of the second body 17 of the actuator relative to the first caerpo 13 of the actuator. It should be noted that the invention also relates to other types of electric actuators with a first actuator body, a second actuator body that can be pivotally mounted relative to the first actuator body through a limited angle of rotation , energy mechanisms for executing a moment of electromagnetic torsion in the second actuator body, and a control unit for controlling said angle of rotation. The actuator can, for example, be provided with a mechanical torsion spring to execute a mechanical spring torque in the second actuator body instead of or in addition to the magnetostatic torque. In such a case, the memory 125 of the first control part 81 is omitted and replaced by a memory in which a relation between said mechanical spring torque and the angle of rotation is stored in a tabular form, said memory supplies an electrical signal that corresponds to an estimated torque of mechanical spring. It should also be noted that the uEM signal corresponding to an electromagnetic torque can also be determined in an alternative way by the first part 8 :. of control, while the signal ux corresponding to the electric current required through the energy mechanisms 29 can also be determined in an alternative way by means of the second control piece 83. In the first control piece 81, for example, the profile generator 89 can be omitted or a comparator having the signals uf and uf can be used as the input signals. In addition, the memory 125 can be replaced by a calculator that contains a mathematical relationship between the magnetostatic torque and the angle of rotation. In addition, depending on the structure and composition of the electric actuator, a different load torque executed in the second actuator body depending on the angle of rotation can be determined by the memory 125 or the calculator instead of the magnetostatic torque. . Finally, the memory 135 of the second control piece 83 can be replaced by a calculator having a mathematical relationship between the electromagnetic torque, the rotation angle of the second actuator body, and the current through the mechanisms of energy. It should finally be noted that the electric actuator according to the invention can also be applied in other apparatuses in which the angular position of an axis must be controlled at a variable or constant reference angle. The electric actuator can, for example, be used in servo-operated valves in chemical plants or power stations or in devices for deflecting the control surfaces of a flying machine. The actuator can be used for a so-called main actuator without a transmission in which case the actuator directly drives a body to be displaced, as in the embodiment of the invention described above, or in combination with a transmission to convert a movement of the actuator. rotation in another movement of rotation or in a linear movement, case in which the linear position of a body can be controlled precisely by the electric actuator.