Method for controlling the drive unit for a shading device

Abstract

The invention, which relates to a method for controlling a drive unit (1) for a shading device, addresses the problem of specifying a solution by which the complexity for dissipating the braking energy generated in the generator operating mode, said braking energy being transmitted as electrical energy into a DC link of the drive unit (1), is reduced and in the case of which the complexity and the costs for the manufacturing of a drive unit (1) are reduced. This problem is solved in that a voltage U Z at the DC link (12) and / or a current I Z flowing from the inverter (5) into the DC link (12) is monitored in the drive unit (1) and in that, upon a transition from the motor operating mode of the electric motor (7) to a generator operating mode of the electric motor (7) and the reaching or exceeding of a predefined threshold value for the voltage U Z and / or for the current I Z , a switch is made to energy-reducing operation in which, in order to limit the voltage U Z and / or the current I Z to a defined value, the impressed motor current vector I S is generated by the inverter (5) such that, while the working point of the electric motor (7) is maintained, the first predefined magnitude of the torque-forming current component I S ,q <sb / > of the motor current vector I S is maintained and such that at the same time the second predefined magnitude for the field-forming current component I S ,d of the motor current vector I S is increased until the voltage U Z and / or the current I Z in the drive unit (1) no longer increases above the threshold value.

Description

[0001] Method for controlling the drive unit for a darkening device The invention relates to a method for controlling a drive unit for a darkening device, wherein in a motor operating mode of a multi-phase electric motor of the drive unit by means of an inverter of the drive unit connected to an intermediate circuit in a normal operation a multi-phase motor voltage, in particular comprising phase voltages ^ ^,^ , ^ ^,^ and ^ ^,^ , for an operating point of the electric motor of the drive unit is generated in such a way that the multiphase motor voltage produces a motor current vector ^ ^ , in particular comprising phase currents ^ ^,^ , ^ ^,^ and ^ ^,^ , which is a moment-forming current component ^ ^,^ with a first predetermined amount and a field-forming current component ^ ^,^with a second predetermined amount, whereby a rotor of the electric motor rotates. Drive units for darkening devices are known in which an electric motor and a motor control unit are arranged within a hollow cylindrical housing. Due to the shape of the housing, such drive units are also referred to as tubular motors. Due to their elongated and essentially rotationally symmetrical shape, such tubular motors are suitable, for example, for being inserted into so-called hollow shafts for power transmission and for driving these hollow shafts. One example of the use of such drive units is darkening devices, which are typically flat and are used, for example, to darken windows.Here, the drive unit is inserted into a so-called load shaft, on which, for example, the flat darkening device can be rolled up spirally like a roller shutter. Such a darkening device can also be a roller blind, an awning or a security device such as a rolling door or a rolling grille. A rotational movement of this load shaft, generated by an electric motor of the drive unit, then leads to the darkening device being rolled up or down. This makes it possible, for example, to partially or completely darken a window by unrolling the darkening device such as a roller shutter. Rolling up the roller shutter removes the darkening of the window. The electric motors or tubular motors used in such drive units usually receive their electrical power from a connection to the mains voltage of a power grid.Increasingly, drive units for blinds are also being provided with electric motors, which can be powered by solar energy or a battery. A motor control unit is provided to control the electric motor located in the drive unit, which controls an inverter arranged between the electric motor and the electrical grid or a battery. In the case of a connection to a conventional electrical grid, modules for converting the input AC voltage into DC voltage, as well as voltage stabilization modules, are also used.It is also known that such a motor control unit for controlling the inverter or a frequency converter can comprise a central control unit, wherein the central control unit can be controlled by means of a corresponding program and thus implements the control and monitoring of the drive unit with all necessary components. Such a central control unit can be a program-controlled microprocessor for controlling and monitoring the drive unit. For example, PMSM motors, also known as permanent magnet synchronous motors, are used as electric motors. There is no restriction to the use of such electric motors. It is also known to control or operate such PMSM electric motors using a suitable frequency converter.It is also common for the frequency converter to be controlled by an existing central control unit of the motor control unit. When using such drive units, for example to move a darkening device such as a roller shutter, forces arise due to the weight of the roller shutter material when lowering or closing the shutter, which can lead to undesirable acceleration when the shutter is lowered. To counteract these forces and to avoid exceeding the maximum permissible speed when lowering or closing the shutter, braking devices such as a centrifugal brake are used to increase a so-called self-holding torque of the drive units.A disadvantage of such first centrifugal brakes from the prior art is that they only become effective when a minimum speed of the electric motor and a roller shutter speed directly related to the speed are reached. It is also known to short-circuit the windings of the electric motor of the drive unit and thus generate a braking effect. To achieve such a braking effect, appropriate software is required that detects an error condition, such as the blind closing too quickly, and controls the short-circuiting of the windings of the electric motor using additional suitable elements. Systems with a friction brake as the braking means, which generate a permanent braking effect, are also known. If such a friction brake is used, the friction forces permanently applied by this friction brake must be overcome by the drive unit in order to move the blind.In this case, the electric motor of the drive unit must be dimensioned accordingly or oversized. Furthermore, the use of such friction brakes results in mechanical wear, which reduces the service life of such drive units and braking systems. DE 202018105651 U1 describes a drive unit for a blind, comprising an electric motor, a motor control unit, and a brake arranged between the motor and the motor control unit within a casing. The motor, the motor control unit, and the brake are arranged along a main axis within a hollow cylindrical housing.The problem to be solved is to provide a tubular motor which has a motor and a brake unit arranged on the back of the motor, in which the motor is connected to the electronics unit in such a way that the tubular motor is easy to manufacture and assemble, which in particular makes it possible to reduce the costs of manufacturing the tubular motors. To solve this problem, a drive unit for a window darkening device is specified which has an electric motor, a motor control unit and a brake arranged between the motor and the motor control unit within a casing. The motor, the brake and the motor control unit are arranged along the aforementioned main axis. One or more wiring elements are required to establish electrical contact between the motor control unit and the motor and are integrated into the casing of the brake as described.For the purposes of the description, one or more wiring elements can be part of the drive unit, and consequently, one or more wiring elements are integrated into the brake housing. Some or all of the wiring elements used to establish electrical contact between the motor and the motor control unit can be integrated into the brake housing. Another prior art is known from EP 1326000 A2. The subject of this document is a tubular motor drive assembly, in particular for a blind. The high speed of a DC motor used requires a reduction gear with a correspondingly large reduction ratio. This usually has several gear stages arranged one behind the other.The aim of the present teaching is to reduce the size of the reduction gear compared to gear arrangements known from the prior art. This takes into account that the space inside the winding roller is naturally limited. The core of the proposed reduction gear is a spur bevel gear, preferably in the second stage of the reduction gear. This gear stage requires little space, particularly in the direction transverse to the axis of rotation of the drive shaft of the drive motor. Furthermore, a braking arrangement is also provided, which has a brake that engages automatically when the drive shaft is at a standstill.A disadvantage of the previously known state of the art is that, with the centrifugal brakes commonly used with tubular motors, the electric motor and the load of the dimming device connected to the electric motor are only held if the motor speed does not exceed a specified speed. Such second centrifugal brakes operate in such a way that the centrifugal brake only generates a braking or holding effect below a specified speed, which is also referred to as the centrifugal brake's applied speed.If, for example, in the event of a fault in the central control unit of the motor control unit, the applied speed of such a second centrifugal brake is not undercut because the load of the darkening device is too great (pulling load on the output shaft), the drive unit for the window darkening device cannot be stopped and the load or darkening device fails. During a braking process or braking operation of the electric motor, in which the electric motor operates in what is known as the generator mode and energy is transferred from the electric motor via the inverter or the output stage of the frequency converter back into the intermediate circuit or the intermediate circuit capacitor, an impermissibly high voltage or an overvoltage can occur in the intermediate circuit, also known as the voltage intermediate circuit, of the frequency converter.Such a braking process occurs, for example, when the blind moves downwards under its own weight and an adequate braking force counteracts this movement so that the lowering speed or lowering speed of the blind specified by the central control unit is maintained. Such a braking process also occurs, for example, when the blind moves downwards independently under its own weight and this movement is counteracted by no or only insufficient braking force. In this generator mode, the energy generated by the load of the blind, which leads to the rotation of the electric motor, minus any system losses, must be absorbed by the inverter or frequency converter used.Thus, during braking operation, the so-called braking energy is transferred to the converter's intermediate circuit as electrical energy, which feeds power into the intermediate circuit, charging the intermediate circuit capacitor, and increasing the voltage of the intermediate circuit capacitor. Such a converter comprises a converter such as the inverter and the intermediate circuit capacitor arranged in the intermediate circuit. This increase in the voltage at the intermediate circuit, or the intermediate circuit voltage, must be limited to a technically reasonable or permissible level. So-called brake choppers, which are used to monitor the intermediate circuit voltage in a frequency converter, are known from the state of the art.To counteract this situation of an overvoltage occurring in the DC link, the brake chopper is equipped with a so-called braking resistor, which is switched on when a specified first upper voltage value is reached and converts the resulting excess energy in the DC link into thermal energy. This switching on of the braking resistor, which is arranged in parallel with the DC link capacitor with a switching element or an electrical switching element, is usually done in a clocked manner and using suitable control signals for the electrical switching element before the DC link voltage reaches a level that is dangerous for the components. The excess energy is then converted into thermal energy via the switched braking resistor. For this purpose, the braking resistor must be dimensioned accordingly.If the DC link voltage drops again, for example, below a specified second lower voltage value, the braking resistor is no longer connected or the brake chopper is deactivated. Such brake choppers are therefore used in an active process to limit the DC link voltage of the frequency converter. The braking energy fed back into the converter's DC link is thus converted into thermal energy. The disadvantage of this is that the components of the brake chopper must be designed with correspondingly high performance and adequate reserves, and must be appropriately cooled or cooled, which increases the manufacturing effort and the cost of a drive unit.Alternatively, overvoltage diodes or TVS diodes (transient voltage suppressors) can be used in parallel with the DC link capacitor in the converter's DC link to dissipate the braking energy fed back into the converter's DC link or convert it back into heat energy. Another disadvantage here is that the overvoltage diodes must be designed with correspondingly high power and sufficient reserves, which increases the manufacturing effort and the cost of a drive unit. The high temperatures that occur in the TVS diodes or in the area of ​​the TVS diodes due to the absorption of braking energy, for example on a circuit board, create an additional problem of material fatigue. This process is also referred to as thermal cycling of the installed circuit board.It may therefore be necessary to limit the temperature by additional cooling elements or redundancy in the design of the TVS diodes, for example by appropriately dimensioning a housing size, which also leads to additional costs. There is therefore a need for an improved method for controlling the drive unit for a dimming device. The object of the invention is to provide a method for controlling the drive unit for a dimming device, whereby the effort required to dissipate the braking energy generated in the generator mode, which is transferred as electrical energy into an intermediate circuit of the drive unit, is reduced and whereby the effort and costs for manufacturing a drive unit are reduced. This object is achieved by a method for controlling the drive unit for a dimming device with the features according to patent claim 1.Further developments are specified in the dependent patent claims. To move the darkening device in a motor operating mode of the electric motor, three phase voltages, for example, are generated by means of the drive unit's inverter. ^,^ , ^ ^,^ and ^ ^,^ , as motor voltage for the electric motor or AC motor of the drive unit, which causes the rotor of the electric motor to rotate and sets the darkening device in the desired motion. It is known to arrange a gear between the electric motor and a load shaft, on which the darkening device can be wound spirally. Generally, it is intended that the inverter of the drive unit generates the desired voltage from an input voltage applied to the input of the converter, which corresponds to a voltage ^ ^at the intermediate circuit or an intermediate circuit voltage, generates a motor voltage for the operation of an electric motor connected to the inverter output. The input voltage applied to the input of the inverter (voltage ^ ^) a direct voltage provided by a direct voltage source or a direct voltage generated by rectifying an alternating voltage. The motor voltage generated by the inverter can be a three-phase alternating voltage. In particular, when lowering or closing the darkening device, forces arise due to the darkening device's own weight, which can lead to undesired acceleration when the darkening device is lowered. If this undesired acceleration cannot be prevented, there is a transition from the controlled operating mode to an uncontrolled operating mode, in which the mechanical energy generated by the load of the darkening device leads to an increasing rotation of the rotor of the electric motor.The mechanical energy generated by the load of the dimming device is converted into electrical energy in the electric motor in generator mode. It is fed into the inverter connected to the electric motor and thus transferred to the intermediate circuit or the intermediate circuit capacitor. In the field-oriented control system used to control the electric motor, a coordinate system of a space vector of the stator current (motor current vector ^) rotates. ^) of the electric motor with the rotor of the electric motor, so that a projection of the current vector on two axes is possible. On these axes, a so-called d-component is shown as the field-generating current component and a so-called q-component as the torque-generating current component. The d-component has an angle of 90° to the q-component. In order for the machine or electric motor to generate torque, the torque-generating current component, i.e. the q-component, is required, which is in phase with the machine voltage or the internal motor voltage ^ ^^ At an angle of 90° to the q-component, almost no field-forming d-component is impressed during normal operation of the electric motor. The inverter regulates the three-phase motor voltage of the electric motor used in the drive unit, summarized as a space vector, such that during normal operation the torque-forming current component ^ ^,^ of the motor current vector ^^ maximum and the field-forming current component ^ ^,^ of the motor current vector minimal. This means that the first specified amount of the torque-generating current component ^ ^,^ maximum and the second predetermined amount of the field-forming current component ^ ^,^is minimal. Thus, the converter provides the electric motor with the optimal current flow for the specified operating point of the electric motor, and the ohmic losses in the windings of the electric motor are low or minimized. In the motor operating mode of the electric motor, this procedural normal operation is always applied. In the generator operating mode of the electric motor, below a specified threshold, the procedural normal operation is applied, and when this specified threshold is reached or exceeded, an energy-reducing procedural operation is applied, as explained below. Such a threshold can be a specified value for a voltage ^ ^ at the intermediate circuit. Such a threshold can alternatively or additionally be a fixed value for a current flowing from the inverter into the intermediate circuit ^ ^Alternatively, such a threshold can be a fixed value for the power transferred from the inverter to the intermediate circuit ^ ^ be, whereby this performance ^ ^ from the tension ^ ^ on the intermediate circuit and the current flowing into the intermediate circuit ^ ^ Thus, if the specified value is exceeded, the system switches to the energy-reducing mode according to the method. According to the invention, it is provided that, in the event that the electric motor of the drive unit switches to the generator mode and the specified threshold value is reached or exceeded, the motor current vector impressed by the inverter or frequency converter ^ ^ , which includes the individual phase currents of the electric motor, with an additional field-forming current component ^ ^,^In an example of a three-phase electric motor, the motor current vector ^ ^ three phase currents or three motor currents ^ ^,^ , ^ ^,^ ^^^ ^ ^,^ . In other words, it is intended that when the electric motor changes from a motor operating mode to a generator operating mode and the respective predefined threshold value is reached or exceeded, the impressed motor current vector ^ ^ is generated by the converter in such a way that the first specified amount of the torque-forming current component ^ ^,^ of the motor current vector ^ ^ is maintained and that at the same time the second predetermined amount for the field-forming current component ^ ^,^ of the motor current vector ^ ^ while maintaining the operating point of the electric motor until the monitored voltage ^ ^ and / or the monitored current ^ ^or the power fed into the intermediate circuit ^ ^ in the drive unit no longer increases above the respective threshold value. Increasing the second predetermined value results in an increased second value of the field-forming current component ^ ^,^ . Here, the first specified amount describes a value or an amplitude of the moment-forming current component ^ ^,^ of the motor current vector ^ ^ . The first specified amount thus corresponds to the length of the pointer or vector for the moment-forming current component ^ ^,^ . The second specified amount, as well as the increased second amount, describes a value or an amplitude of the field-forming current component ^ ^,^ of the motor current vector ^ ^. The second specified amount, as well as the increased second amount, thus corresponds to the length of the current pointer or vector for the field-forming current component ^ ^,^The specifications for the first specified amount and the second specified amount result from the selected operating point. Maintaining the operating point or maintaining a target speed of the electric motor also means a deviation from a specified target speed of up to approximately 10 percent. In an example with a specified target speed of 3000 revolutions per minute (rpm), the operating point is maintained in a range from 2700 revolutions per minute to 3300 revolutions per minute. The system or the drive unit operates in a speed-controlled manner. By specifying the speed setpoint or the target speed, the inverter, controlled by the motor control unit, influences the rotating field of the electric motor in such a way that the specified target speed and direction of rotation are achieved. Depending on the load direction, a motor operating mode or a generator operating mode results.In motor mode, the voltage in the DC link or at the DC link capacitor drops compared to an open-circuit voltage at the DC link or at the DC link capacitor, whereas in generator mode the voltage at the DC link increases compared to the open-circuit voltage of the DC link. In motor mode, electrical power is also drawn from the DC link by the inverter, whereas in generator mode the inverter feeds electrical power into the DC link. In both modes, the operating point of the drive unit's electric motor is always regulated accordingly using the motor control system. If the machine were to tip over, i.e. the pulling load is too great or the current setpoint is too low, the electric motor would accelerate accordingly and the voltage at the DC link would rise significantly.Appropriate protective measures must be provided for such a case. The operating point of an electric motor is defined as a condition in which a specific speed or target speed is generated under a specific load torque. In other words, in order to generate the required torque at a required target speed, a corresponding motor current must be applied, which results in motor power. The amplitude of the field-generating current components ^ is then measured. ^,^ of the motor current vector ^ ^ increased, the amplitude of the respective motor currents also increases ^ ^,^ , ^ ^,^ ^^^ ^ ^,^ without changing the speed of the electric motor, but the ohmic losses in the windings of the electric motor increase. According to the invention, the voltage ^ ^at the intermediate circuit or the voltage at the intermediate circuit capacitor is monitored or measured by the present method. When a specified threshold value for the voltage is reached or exceeded ^ ^ At the intermediate circuit, a transition is made from normal operation to an operation that reduces energy consumption in relation to the intermediate circuit, thus reducing the voltage ^ ^ at the intermediate circuit and at the intermediate circuit capacitor is limited to a specified value. Alternatively, it is provided that a current flowing from the inverter into the intermediate circuit ^ ^ is monitored or measured by the present method. When a predetermined threshold value for the current is reached or exceeded ^ ^ a transition is made from normal operation to an operation that reduces energy in relation to the intermediate circuit and thus the current ^ ^limited to a specified value. Alternatively, it is provided that a voltage ^ ^ at the intermediate circuit. In addition, a current flowing from the inverter into the intermediate circuit ^ ^ determined or measured. Based on the measured values ​​for the current ^ ^ and the tension ^ ^ becomes an achievement ^ ^ It is known that in the motor mode, power is taken from the intermediate circuit, while in the generator mode, power is fed into the intermediate circuit. In the method according to the invention, it is particularly provided that the power ^ ^ to monitor which is carried by a current ^ ^ after the electric motor transitions from motor mode to generator mode. Such a current directed into the intermediate circuit ^ ^ leads to a power feed-in ^^ into the intermediate circuit. If this fed-in power is ^ ^ at a predetermined switching threshold or above, the energy-reducing operation according to the invention is switched over, whereby ultimately, according to the method, the ohmic losses in the electric motor increase and, as a result, the energy or power fed back into the intermediate circuit ^ ^ reduced. In this way, the power fed into the intermediate circuit ^ ^ limited to a specified value. For sinusoidal quantities, a threshold value for the voltage ^ ^ at the intermediate circuit at a value greater than the product of the effective value of the mains voltage and the square root of two, according to ^^^^ > ^^^^^^^^^^^^ 7 :2. Alternatively, the threshold value for the voltage ^ ^at the intermediate circuit in a range between 400 volts and 460 volts, especially at a value of 430 volts. When the specified threshold value for the voltage ^ ^ at the intermediate circuit and / or the specified threshold value for the current flowing into the intermediate circuit ^ ^ or the specified threshold value for the power fed into the intermediate circuit ^ ^ is different from normal operation, in which the moment-forming current component ^ ^,^ of the motor current vector ^ ^ of the three phases maximum and the field-forming current component ^ ^,^ minimally impressed, into energy-reducing operation, in which the proportion and thus the amplitude or the second predetermined amount of the field-forming current component ^ ^,^ is increased, whereby an increased second amount of the field-forming current component ^ ^,^ and where the amplitude of the motor current vector ^ ^This transition to energy-reducing operation is achieved by appropriately controlling the inverter via the motor controller. The electric motor is assumed to be the load with its ohmic-inductive nature. The winding inductance in the electric motor acts as a reactive element, which is briefly used as an energy store in the inverter's so-called boost converter mode. The phase currents of the electric motor are each driven with a phase angle ! ^ to the respective associated internal motor voltage ^ ^^ generated, where the phase angle ! ^ In the motor mode of the electric motor and in normal operation according to the process, it is in a range between -15° and +15°, and in energy-reducing operation according to the process, it is in a range between -45° and +45°. The phase currents of a three-phase electric motor are the phase currents ^ ^,^ , ^^,^ ^^^ ^ ^,^ , where the corresponding internal motor voltage ^ ^^ the motor voltages ^ ^^,^ , ^ ^^,^ and ^ ^^,^ of the electric motor. It is also planned that the voltage monitoring ^ ^ of the intermediate circuit of the drive unit, whereby the voltage ^ ^ across the DC link capacitor or at the inverter input terminals, with which the inverter is connected to the DC link. It is also planned to monitor the current flowing into the DC link. ^ occurs, whereby the current ^ ^is measured at a current measuring point located between the intermediate circuit and the inverter. In the energy-reducing operation according to the invention, an increase in the ohmic losses in the windings of the electric motor is achieved, which leads to a portion of the energy generated by the generator mode being converted into thermal energy in the motor windings of the electric motor. Through this partial to complete reduction of the energy generated in the generator mode in the electric motor itself, the proportion of energy transferred to the intermediate circuit of the drive unit and thus the power fed into the intermediate circuit ^ ^ It is intended that once the specified threshold value for voltage ^ ^ , the current ^ ^ or the performance ^ ^ , such as a voltage ^ ^ of, for example, 430 volts, the amplitudes of the field-forming current components ^^,^ of the motor current vector ^ ^ are increased in their respective amplitude until the voltage ^ ^ at the intermediate circuit, the current flowing into the intermediate circuit ^ ^ or the power fed into the intermediate circuit ^ ^ no longer increases or increases only slightly, within a specified tolerance. If the voltage increases ^ ^ at the intermediate circuit, the current flowing into the intermediate circuit ^ ^ or the power fed into the intermediate circuit ^ ^ no longer increases, the amplitude of the field-forming current components ^ ^,^ of the motor current vector ^ ^ no longer increased, but maintained. This is achieved by appropriately controlling the amplitude of the field-forming current component ^ ^,^ of the motor current vector ^ ^by the motor control. If one of the specified threshold values, for example a voltage of 430 volts, is undershot, the amplitude of the field-forming current component ^ ^,^ of the motor current vector ^ ^ no longer increased or reduced again. A transition from the energy-reducing operation according to the invention to the normal operation of the electric motor occurs. Thus, after this transition to normal operation, the torque-generating current component ^ ^,^ of the motor current vector ^ ^ the phase currents maximum or again with their previous amplitude and the field-forming current component ^ ^,^ minimally impressed. Depending on the drive type or power, the amplitude or the second predetermined amount of the field-forming current component ^ ^,^ depending on the monitored or measured voltage ^ ^on the intermediate circuit and / or depending on the monitored or measured current flowing into the intermediate circuit ^ ^ or depending on the determined power fed into the intermediate circuit ^ ^ gradually, or continuously increased, whereby an increased amplitude or an increased second amount of the field-forming current component ^ ^,^ This increase in the amplitude or the second predetermined amount of the field-forming current component ^ ^,^ , depending on the monitored variables, is carried out stepwise or continuously by means of a P-element or I-element or PI-element. (Proportional element or integral element or PI-element with components of a P- and I-element) According to the method, it is provided that by the increases in the amplitudes or the second predetermined amounts of the field-forming current components ^ ^,^while maintaining the operating point of the electric motor, the respective phase angle! ^ increases, whereby a reactive power increases and an energy-reducing operation of the drive unit is achieved, in which due to the larger motor currents the ohmic losses caused by the resistors " ^ of the stator windings of the electric motor, whereby a part of the energy generated during generator operation of the electric motor is converted into heat in the stator winding of the electric motor. If, with a constant amplitude of the q-component, i.e. the first predetermined value, the amplitude of the d-component, i.e. the second predetermined value, is increased for each phase of the electric motor, whereby an increased second value of the field-forming current component ^ ^,^ occurs, then the amplitude of the motor current vector increases ^ ^and thus the amplitudes of the phase currents equally, without the motor rotating faster, because ultimately the phase position between the motor current vector ^ ^ and motor voltage indicator ^ ^^ increased. With constant active power or constant torque applied by the motor, the reactive power and thus the losses increase. By applying the applied motor current vector ^ ^ With an additional reactive component in the energy-reducing operation according to the invention, the amplitude of the motor current vector increases ^ ^, but without affecting the torque-generating current component. However, the ohmic losses in the electric motor or in the windings of the electric motor increase and the energy fed back into the intermediate circuit or the power fed into the intermediate circuit decreases, since a significant portion of the energy released by the load of the dimming device is already converted into heat in the electric motor itself during generator operation of the electric motor. Due to the high thermal capacity of the electric motor with its windings and stator or rotor cores, the resulting heat is distributed almost evenly throughout the electric motor and high temperature peaks in individual areas of the electric motor or on a motor board controlling the electric motor with a motor control unit can be prevented.The additional reactive component of the motor current to be impressed in the energy-reducing operation according to the invention is, for example, determined as a function of the voltage ^. ^ at the intermediate circuit of the frequency converter. This can be done by storing the function sequence in a program code to be processed by a central controller. The central controller of the motor control can monitor the voltage ^ using suitable sensors. ^ at the intermediate circuit and thus, with knowledge of the given functional curve, the additional reactive component of the motor current, i.e. the field-forming current components ^ ^,^ of the motor current vector ^ ^ by appropriate control signals to the inverter and using field-oriented control. With such a predefined function sequence, when a predefined threshold value of the monitored voltage is reached or exceeded, ^ ^At the intermediate circuit, a transition from normal operation to the energy-reducing operation according to the invention is realized by the amplitudes of the field-forming current components ^ ^,^ of the motor current vector ^ ^ and thus the phase currents are increased. The function curve realizes, for example, a continuous increase in the amplitudes of the field-forming current components ^ ^,^ of the motor current vector ^ ^ for example when monitoring the voltage ^ ^ of the intermediate circuit it is detected that this voltage ^ ^ does not increase further above the threshold and is thus limited to a specified value. Such function curves can also be used for the current flowing into the intermediate circuit ^ ^ and the power fed into the intermediate circuit ^ ^Such a function curve can be stored in a corresponding value table, which the central controller or motor controller can access when executing its program code. Depending on the drive type or the power of the electric motor used, the amplitude of the field-forming current component ^ ^,^changed stepwise or continuously depending on measured values ​​of the monitored variables. Special features of the present invention are listed below: ÷ Method for controlling a drive unit for a dimming device, in which a PMSM-based electric motor (tubular motor) is used in a drive unit, wherein the electric motor is controlled by means of an inverter and wherein the drive unit can be equipped with or without a voltage limiting system in the intermediate circuit of the converter. ÷ Control according to the method for reducing the energy or power fed into the intermediate circuit of the converter in generator mode, after reaching or exceeding a specified threshold value of a variable to be monitored, such as a voltage ^ ^ , a stream ^ ^ or a service ^ ^, to reduce the further increase of one or more of these variables above the specified threshold value or generally to limit the variables to be monitored to a specified value by means of energy-reducing operation. ÷ In generator mode, when a specified threshold value of the variable to be monitored is reached or exceeded, an additional reactive component (field-forming d-component) is added to the impressed motor currents for energy-reducing operation, which increases the amplitudes of the motor currents without, however, affecting the torque-forming current components of the motor currents, whereby the ohmic losses in the electric motor increase and the energy or power fed back into the DC link is reduced. ÷ The additional reactive component to be impressed for each motor current of the electric motor can be specified as a function of the variable of the inverter to be monitored.The control takes place stepwise or continuously by means of a P-element or I-element or PI-element (proportional element or integral element or PI element). Further details, features and advantages of embodiments of the invention emerge from the following description of exemplary embodiments with reference to the accompanying drawings. They show: Fig. 1a, 1b, 1c: several basic circuit diagrams of various drive units for darkening devices from the prior art, Fig. 2: a single-phase equivalent circuit diagram of a converter-operated, symmetrically constructed three-phase motor, Fig. 3: several effective value vectors of the resulting motor current vector associated with a generator operating mode of the electric motor according to Figure 2 without any method-related influence, and Fig.4: Several effective value vectors of the resulting motor current vector associated with a generator operating mode of the electric motor according to Figure 2 with a method-based influence. Figures 1a, 1b, and 1c each show a drive unit 1 for a prior art dimming device (not shown). In the examples of Figures 1a to 1c, each drive unit 1 is connected to a mains voltage 3 via a first switching element 2. In the example of Figures 1a to 1c, the drive units 1 each have a rectifier 4, for example in the form of a bridge rectifier, which is also referred to as a Graetz bridge or rectifier bridge. By means of the rectifier 4, the input-side mains voltage 3 is converted like an AC voltage into a DC voltage, which is fed to the respective inverters 5.The inverters 5 are each connected to a central control unit (not shown) of a motor control unit (also not shown). These central control units generate control signals for the associated inverter 5. These control signals are used to generate a multi-phase motor voltage 6 on the output side of the inverter 5 in the form of three-phase voltages ^. ^,^ , ^ ^,^ and ^ ^,^ realized. Using these three output phase voltages ^ ^,^ , ^ ^,^ and ^ ^,^of the inverter 5, an associated electric motor 7 is controlled and operated in this way. In an area between the rectifier 4 and the inverter 5, an intermediate circuit 12 is arranged, each of which has an intermediate circuit capacitor 8 for intermediate energy storage. In this area of ​​the intermediate circuit 12 between the rectifier 4 and the inverter 5 and parallel to the intermediate circuit capacitor 8, a second switching element 9 and a resistor 10 are arranged in a series circuit in Figure 1a. In this area of ​​the intermediate circuit 12 between the rectifier 4 and the inverter 5 and parallel to the intermediate circuit capacitor 8, two overvoltage diodes 11 are arranged in a series circuit in Figure 1b, for example.In this area of ​​the intermediate circuit 12 between the rectifier 4 and the inverter 5 and parallel to the intermediate circuit capacitor 8, a second switching element 9 and a resistor 10 are arranged in a first series circuit in Figure 1c, and two overvoltage diodes 11 are arranged in a second series circuit, for example. Both the resistor 10 in Figures 1a and 1c, which can be switched on via the second switching element 9, and the overvoltage diodes 11 in Figures 1b and 1c are required to reduce an undesirably high voltage in the intermediate circuit 12 or at the intermediate circuit capacitor 8 and thus to generate a braking effect on the electric motor 7, as is known from the prior art.In the example of Figure 1a, the drive unit 1 comprises the central control unit (motor control unit) (not shown), the first switching element 2, the rectifier 4, the inverter 5, the electric motor 7, and the intermediate circuit capacitor 8, the second switching element 9, and the resistor 10 arranged in the intermediate circuit 12. In the example of Figure 1b, the drive unit 1 comprises the central control unit (motor control unit) (not shown), the first switching element 2, the rectifier 4, the inverter 5, the electric motor 7, and the intermediate circuit capacitor 8 and the two overvoltage diodes 11 arranged in the intermediate circuit 12.In the example of Figure 1c, the drive unit 1 comprises the central control unit (motor control unit) not shown, the first switching element 2, the rectifier 4, the inverter 5, the electric motor 7 and the elements arranged in the intermediate circuit 12: intermediate circuit capacitor 8, second switching element 9, resistor 10 and the two overvoltage diodes 11. In Figures 1a, 1b and 1c, the voltage ^ is also shown. ^ at the intermediate circuit 12 or at the intermediate circuit capacitor 8 and the current flowing into the intermediate circuit 12 ^ ^ While the voltage ^ ^ As shown by way of example at the input terminals of the inverter 5, with which the inverter 5 is connected to the intermediate circuit 12, the current ^ ^at a current measuring point 13 located between the intermediate circuit 12 and the inverter 5, at an input terminal of the inverter 5. Figure 2 shows a single-phase equivalent circuit of a symmetrically constructed, inverter-operated three-phase electric motor 7. Due to the symmetrical design of the three-phase electric motor 7, with its concentrated winding systems offset by 120°, a single-phase equivalent circuit can be derived from a three-phase equivalent circuit. In the equivalent circuit shown in Figure 2 of an exemplary selected phase u, the phases u, v and w, or the three phase voltages ^ ^,^ , ^ ^,^ and ^ ^,^ comprising electric motor 7 is the inverter voltage or the phase voltage impressed by the inverter 5 ^ ^,^ , a resistance of the stator winding " ^ , a motor inductance # ^ , the motor current ^ ^,^and the internal motor voltage (counter EMF) ^ ^^,^ which are known to the expert. The internal motor voltage ^ ^^,^ Counter electromotive force (counter EMF), or counter electromotive force (counter EMF), is the voltage generated by flux linkage during operation of a rotating machine, i.e., electric motor 7. The amplitude of the counter EMF is proportional to the speed and independent of the load. Figures 3 and 4 show the effective value vectors associated with a generator operating mode of the electric motor, as well as the motor current vector ^ resulting at the operating point of electric motor 7. ^ with its field-forming current component ^ ^,^ and its moment-forming current component ^ ^,^As already explained, the mechanical energy generated by the load of the dimming device can cause the electric motor 7 to transition from the motor mode to the generator mode. For this case, in which the mechanical energy generated by the load of the dimming device is transferred as electrical energy into the intermediate circuit 12 of the converter, the corresponding effective value vectors are shown with and without process-related influence. In detail, Figures 3 and 4 show the current and voltage vectors of an exemplary phase u of the electrical machine, i.e., the electric motor 7, to illustrate the process. Shown is an effective value vector of the internal motor voltage ^ ^^,^ (Against EMF) of phase u, an effective value indicator of the phase voltage impressed by the inverter 5 ^ $,^the phase u, an effective value indicator for a voltage across a motor winding ^ %& , a pointer of the voltage drop across the motor impedance " $ ^ $,^ (with the resistance " $ the stator winding of the electric motor 7 and the motor current indicator of phase u) and an inductive component of the voltage across the motor winding '(# ^ ^ ^,^ . Furthermore, Figures 3 and 4 each show a moment-forming current component ^ ^,^ , a field-forming current component ^ ^,^ and the corresponding resulting motor current vector ^ ^ . Here, the first specified amount in Figures 3 and 4 is each given by the length of the pointer for the moment-forming current component ^ ^,^ Furthermore, the second predetermined amount in Figure 3 is determined by the length of the pointer for the field-forming current component ^ ^,^In Figure 4, the length of the pointer for the field-forming current component ^ ^,^ the increased second magnitude of the field-forming current component ^ ^,^ The position or orientation of the resulting motor current vector can also be seen at an angle corresponding to the angle between the motor current indicator the phase u and the internal motor voltage ^ ^^,^ , forming phase angle! ^ Figure 3 shows the described pointers or components in generator operation and in the inventive normal operation of the electric motor 7 without any method-related influence. At the corresponding operating point, a specific pointer length results for the motor current vector ^ and a very small phase shift to the internal motor voltage ^ ^^,^ , as can be seen from the size of the phase angle ! ^can be seen. Figure 4 shows the described pointers or components for the same operating point of the electric motor 7, but with a method-increased amplitude or the method-increased second amount of the field-forming current component ^ ^,^ in generator operation and energy-reducing operation according to the invention. The same operating point is achieved with a significantly larger current phasor for the field-forming current component ^ ^,^ and thus a significantly larger phase shift! ^ which results in the amplitude of the motor current vector ^ ^ and thus the amplitudes of the motor currents increase and an energy-reducing operation controlled by the process is achieved, in which due to the larger motor current vector ^ ^ the ohmic power losses increase. By changing or increasing the amplitude of the motor current vector ^ and thus the phase angle! ^ the ohmic losses caused by the resistance increase " ^ of the stator windings of the electric motor 7. This increase in the amplitude of the motor current vector and thus the phase angle! ^ Compared to the representation in Figure 3, this can be clearly seen in Figure 4. While the phase angle ! ^ in Figure 3 is only about 8°, the phase angle increases! ^ in Figure 4 with the process-based influence to approximately 35°. In the generator mode, when the specified threshold value is reached or exceeded, at least one of the variables to be monitored, such as the voltage ^ ^ at the intermediate circuit 12, the current flowing into the intermediate circuit 12 ^ ^ or the power fed into the intermediate circuit 12 ^ ^ , a transition to the energy-reducing operation according to the invention, in which the motor current vector ^ ^of the electric motor 7 is regulated in such a way that the ohmic losses in the windings of the electric motor 7 increase, with a significant portion of the braking energy being converted into heat in the stator windings of the electric motor 7. Thus, in the energy-reducing operation according to the invention, the proportion of energy or braking energy that is transferred from the electric motor 7 via the inverter 5 into the intermediate circuit 12 of the drive unit 1 or fed into the intermediate circuit 12 as power is reduced. Due to the high thermal capacity of the electric motor 7, the temperature in the drive unit 1 is distributed more evenly and high temperature peaks, for example on a motor board controlling the electric motor 7 with a motor control unit, can be prevented, which leads to a reduction in size or to the elimination of converter components such as a resistor 10 in the intermediate circuit 12 or overvoltage diodes 11.The present method ensures that a required braking torque is generated by the electric motor 7 using the impressed currents (^. $,^ , ^ $,^ ) is provided. For this purpose, the amplitude of the moment-forming current component ^ ^,^ of the motor current vector ^ ^ in Figure 4 is the same as in Figure 3, while the amplitude of the field-forming current component ^ ^,^ of the motor current vector ^ ^ increases. The following exemplary embodiment can be derived from the vectors shown in Figure 3 and Figure 4. In order to operate the electrical machine, i.e. the electric motor 7 in generator mode at its specified operating point stably at a target speed of, for example, 2700 rpm and a mechanical power of 215.7 rpm, a motor current of ^ with an amplitude of 120 with the current components ^ ^,^= 0 -1, which corresponds to the second specified amount, and ^ ^,^ = 120 -1, which corresponds to the first specified value. For a winding resistance " ^ of the stator winding of 140 «, the ohmic losses of the three-phase winding are 3.0 ^. If the current vector is now in energy-reducing operation with an increased second value, i.e. a field-forming current component ^ ^,^ = 120 -1, with constant torque-generating current component ^ ^,^ = 120 -1, this results in a resulting amplitude of the motor current vector ^ ^ of approximately 170 -1. The ohmic losses in the three-phase winding are now 6.0 ^. Neglecting the losses of the inverter 5, for one and the same operating point of the electric motor 7, the additionally impressed field-forming current component of ^ ^,^= 120 -1 a reduction of the power fed into the intermediate circuit 12 by 3.0 ^ is achieved, which means that the electrical losses in the machine are doubled.

[0002] List of reference symbols 1 Drive unit 2 First switching element 3 Mains voltage 4 Rectifier 5 Inverter 6 Motor voltage 7 Electric motor 8 Intermediate circuit capacitor 9 Second switching element 10 Resistor 11 Overvoltage diode 12 Intermediate circuit 13 Current measuring point

[0003] Formula symbol list ^ ^ Motor current vector ^ ^,^ d-component (field-forming current component) of the motor current vector ^ ^,^ q-component (torque-forming current component) of the motor current vector! ^ Phase angle between motor voltage pointer (^ ^^ ) and motor current indicator (^ $ ) " ^ Resistance of the stator winding of the electric motor ^ ^^ internal motor voltage ^^^,^, ^^^,^, ^^^,^Motor voltage of the electric motor ^ ^,^RMS value indicator of the phase voltage of phase u # ^ Motor inductance ^ ^^,^ RMS value indicator of the internal motor voltage of phase u (counter EMF) ^ %& Voltage drop across the motor winding '(# ^ ^ ^,^ inductive voltage drop across the motor winding of phase u ^ $,^ RMS value indicator of the motor current of phase u^ ^,^ , ^ ^,^ , ^ ^,^ Phase voltages of the electric motor ^ ^ Voltage at the intermediate circuit / intermediate circuit voltage ^ ^ Current in the intermediate circuit ^ ^ power fed into the intermediate circuit Phase currents of the electric motor " $ ^ $,^ Pointer voltage drop across motor impedance of phase u ^ ^ Motor current

Claims

1 Claims 1. Method for controlling a drive unit (1) for a darkening device, wherein in a motor operating mode of a multi-phase electric motor (7) of the drive unit (1) by means of an inverter (5) of the drive unit (1) connected to an intermediate circuit (12) in a normal operation a multi-phase motor voltage (6), in particular comprising phase voltages ^ ^,^ , ^ ^,^ and ^ ^,^ , for an operating point of the electric motor (7) of the drive unit (1) is generated in such a way that the multi-phase motor voltage (6) generates a motor current vector ^ ^ , in particular comprising phase currents ^ ^,^ , ^ ^,^ and ^ ^,^ , which is a moment-forming current component ^ ^,^ with a first predetermined amount and a field-forming current component ^ ^,^with a second predetermined amount, wherein a rotation of a rotor of the electric motor (7) takes place, characterized in that a monitoring of a voltage ^ ^ at the intermediate circuit (12) and / or a current flowing from the inverter (5) into the intermediate circuit (12) ^ ^ in the drive unit (1) that when the electric motor (7) changes from the motor operating mode to a generator operating mode and a predetermined threshold value for the voltage ^ is reached or exceeded ^ and / or the current ^ ^ into an energy-reducing operation in which the impressed motor current vector ^ ^ from the inverter (5) to limit the voltage ^ ^ and / or a limitation of the current ^ ^to a respective specified value in such a way that, while maintaining the operating point of the electric motor (7), the first predetermined amount of the torque-forming current component ^ ^,^ of the motor current vector ^ ^ is maintained and that at the same time the second predetermined amount for the field-forming 2 Current component ^ ^,^ of the motor current vector ^ ^ is increased until the voltage ^ ^ and / or the current ^ ^ in the drive unit (1) no longer increases above the respective threshold value.

2. Method for controlling a drive unit (1) for a darkening device, wherein in a motor operating mode of a multi-phase electric motor (7) of the drive unit (1) by means of an inverter (5) of the drive unit (1) connected to an intermediate circuit (12) in normal operation, a multi-phase motor voltage (6), in particular comprising phase voltages ^ ^,^ , ^ ^,^ and ^^,^ , for an operating point of the electric motor (7) of the drive unit (1) is generated in such a way that the multi-phase motor voltage (6) generates a motor current vector ^ ^ , in particular comprising phase currents ^ ^,^ , ^ ^,^ and ^ ^,^ , which is a moment-forming current component ^ ^,^ with a first predetermined amount and a field-forming current component ^ ^,^ with a second predetermined amount, wherein a rotation of a rotor of the electric motor (7) takes place, characterized in that a monitoring of a voltage ^ ^ at the intermediate circuit (12) and a current flowing into the intermediate circuit (12) ^ ^ in the drive unit (1) that a determination of a power fed into the intermediate circuit (12) ^ ^ from the monitored values ​​for the voltage ^ ^ and the current ^ ^occurs that when the electric motor (7) changes from the motor operating mode to a generator operating mode and a predetermined threshold value for the power is reached or exceeded ^ ^ , is transferred to an energy-reducing operation in which the impressed motor current vector ^ ^ from the inverter (5) to limit the fed-in power ^ ^ to a specified value in such a way that, while maintaining the operating point of the electric motor (7), the first predetermined amount of the torque-generating 3 Current component ^ ^,^ of the motor current vector ^ ^ is maintained and that at the same time the second predetermined amount for the field-forming current component ^ ^,^ of the motor current vector ^ ^ is increased until the power fed into the intermediate circuit (12) ^ ^no longer increases above the threshold value.

3. Method according to claim 1 or 2, characterized in that the transition to the energy-reducing operation takes place while maintaining a target speed of the electric motor (7).

4. Method according to one of claims 1 to 3, characterized in that the increase in the second predetermined amount for the field-forming current component ^ ^,^ continuously or stepwise.

5. Method according to one of claims 1 to 4, characterized in that the increase in the second predetermined amount of the field-forming current component ^ ^,^ by means of a P-element or I-element or PI-element.

6. Method according to claim 1, characterized in that the specified threshold value for the voltage ^ ^at the intermediate circuit (12) is greater than a product of an effective value of a mains voltage (3) and a square root of two.

7. Method according to claim 1, characterized in that the specified threshold value for the voltage ^ ^ at the intermediate circuit (12) in a range between 400 volts and 460 volts, in particular at a value of 430 volts.

8. Method according to one of claims 1 to 7, characterized in that the phase currents ^ ^,^ , ^ ^,^ and ^ ^,^ of the electric motor (7) each with a phase angle ! ^ to the respective associated internal motor voltage ^ ^^ generated, where the phase angle ! ^ in the 4 motor operating mode of the electric motor (7) and in the normal operation according to the method in a range between -15° and +15° and in the energy-reducing operation according to the method in a range between -45° and +45°.

9. Method according to claim 8, characterized in that by increasing the second predetermined amount of the field-forming current component ^ ^,^ while maintaining the operating point of the electric motor (7) the phase angle ! ^ increases, whereby the energy-reducing operation of the drive unit (1) is achieved, in which due to a larger amplitude of the motor current vector ^ ^ the ohmic losses caused by one resistance each " ^a stator winding of the electric motor (7), wherein a portion of the energy generated in the generator operation of the electric motor (7) is converted into heat in the stator windings of the electric motor (7).

10. Method according to one of claims 1 to 9, characterized in that the increased second predetermined amount for the field-forming current component ^ ^,^ while maintaining a target speed of the electric motor (7), in the event that the voltage ^ ^ at the intermediate circuit (12) and / or the current flowing into the intermediate circuit (12) ^ ^ or the power fed into the intermediate circuit (12) ^ ^ is above the respective threshold value and no longer increases or that the increased second predetermined amount for the field-forming current component ^ ^,^ while maintaining a target speed of the electric motor (7), in the event that the voltage ^ ^at the intermediate circuit (12) and / or the current flowing into the intermediate circuit (12) ^ ^ or the power fed into the intermediate circuit (12) ^ ^ is above the respective threshold and falls.

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