METHOD AND DEVICE FOR REGULATING AN ELECTRIC MACHINE

Description

[0001] The invention relates to a method and a device for controlling an electric machine. Furthermore, the invention relates to an electric drive system with a corresponding device and a vehicle with an electric drive system, as well as a computer program and a computer-readable storage medium. State of the art

[0002] Patent applications US 2002 / 097015 A1, US 2013 / 193898 A1, and DE 10 2018 202967 A1 disclose methods and devices for controlling an electric machine. Patent application DE 2017 102 036 91 A1 discloses a control system for an electric machine in which a disturbance variable is simultaneously compensated and a setpoint is set. For the operation of an electric machine, a phase current is set as the setpoint. The phase current is preferably set as a sinusoidal fundamental wave. During operation of the electric machine, the phase current causes the output of a uniform average torque. Due to non-ideally sinusoidal magnetic fields, winding arrangements, slotting, tooth geometry, saturation effects, and / or other effects, harmonic overtones of the torque are also generated in addition to the uniform average torque.Such effects lead to force waves between the rotor and stator, which, in characteristic orders, act on the stator teeth as tangential and radial tooth forces. Due to the mechanical transmission behavior of the electric machine, these forces become perceptible as vibrations in the machine, the machine housing, and coupled components, and thus as structure-borne and airborne noise or surface vibrations. The harmonic overtones of the torque also cause harmonics of the electric machine's electrical frequency to appear on the phase current as disturbances. To minimize these disturbances, specific harmonics are introduced and preset, which are then superimposed on the preset phase current.

[0003] There is a need for alternative methods and devices for controlling an electrical machine, with which the harmonics can be controlled as robustly, stably, dynamically and flexibly as possible to take relevant frequency components into account. Disclosure of the invention

[0004] The invention is defined by the features of the independent claims.

[0005] A method for controlling an electric machine with a harmonic filter is provided, wherein the harmonic filter comprises a second filter and a filter output transformation. The method includes the following steps: Determining a feedback variable, wherein the feedback variable comprises an actual value of a fundamental wave and a harmonic of a given frequency in a field-oriented system; Determining a filter setpoint in a harmonic-oriented system; Filtering the filter setpoint using the second filter; Back-transforming the filtered filter setpoint using the filter output transformation to a harmonic (IdqHrmc) in the field-oriented system; Determining a filtered feedback variable without harmonic content as the difference between the feedback variable and the harmonic; Energizing at least one winding of the electrical machine as a function of the filtered feedback variable without harmonic content.

[0006] Field-oriented control systems are widely used to regulate electrical machines. In these systems, the alternating quantities of the phase currents to be regulated in the time domain, preferably sinusoidal, also called fundamental frequencies, are transformed mathematically into a coordinate system that rotates at the frequency of the alternating quantities. The frequency of the alternating quantities also determines the frequency of the magnetic field in the machine, so this coordinate system rotating at the frequency of the alternating quantities is also called a field-oriented system. In steady-state operation of the electrical machine, the alternating quantities in the time domain result in DC quantities in the field-oriented system, which can be controlled using standard control engineering methods. The field-oriented system is also called a d / q coordinate system. Its d-axis points in the direction of the rotor flux, and the q-axis is perpendicular to the d-axis.A sinusoidal phase current is represented as a stator current vector, characterized by its length and direction. This current vector rotates synchronously with the rotating stator or rotor flux of the electric machine. In the d / q coordinate system, the current vector can be represented according to its length and direction by two mutually perpendicular components, Id and Iq, which are DC quantities in the steady state.

[0007] To control an electric machine that can be connected to or attached to a harmonic controller, a feedback signal from the electric machine is acquired in the field-oriented system. This feedback signal comprises a fundamental frequency and a harmonic superimposed on the phase current, the fundamental frequency. In the field-oriented system, the phase current is a DC quantity, whereas the harmonic is an AC quantity. For harmonic control, the AC quantities from the field-oriented system are transformed into a harmonic-oriented system using a mathematical transformation with a harmonic frequency, similar to the transformation from the time domain to the field-oriented domain. Quantities represented as AC quantities in the field-oriented system are represented as DC quantities in the harmonic-oriented system during steady-state operation of the electric machine.These can be controlled using the usual methods of control engineering.

[0008] In a harmonic-oriented system, a filter input signal is determined. This signal is filtered by a second filter and, for further use, transformed back to a harmonic value in the field-oriented system via the filter output transformation. The second filter is preferably a low-pass or band-pass filter. Preferably, the cutoff frequency of the low-pass or band-pass filter is selected to correspond to the cutoff frequency of the closed harmonic control loop. Finally, a filtered feedback signal without harmonic content is determined as the difference between the feedback signal and the harmonic value. Subsequently, at least one winding of the electrical machine is energized depending on the filtered feedback signal without harmonic content.

[0009] According to the invention, a method is provided for an effective determination of a filtered feedback variable without harmonic content for a fundamental frequency controller.

[0010] The formulation that a control loop variable includes a harmonic or fundamental frequency means, within the scope of this application, that a control loop variable characterizes or describes at least one harmonic or fundamental frequency, whereby the respective control loop variable may also include further signal components, for example fundamental frequency and one or more harmonics, as well as any additional disturbances present.

[0011] For the control of electrical machines, target phase currents are commonly specified based on measured actual phase currents, depending on a torque specification, with phase voltages being set as manipulated variables. Consequently, preferably within the scope of this application, the feedback variable (Idq), the DC feedback variable (IHrmc), the DC control variable (IHrmc*), the machine feedback variable (labc), or the predefinable DC control variable (Idq*) each comprise a current value, and / or the DC control variable (UHrmc*), the manipulated variable (UdqHrmc*), the DC control variable, or the machine manipulated variable (Uabc*) each comprise a voltage value.

[0012] Preferably, the feedback variable in the field-oriented system comprises a harmonic with a positive frequency with a first amplitude and a first phase of a k-th order of an electrical frequency of the electrical machine and / or a harmonic with a negative frequency with a second amplitude and a second phase of a k-th order of an electrical frequency of the electrical machine.

[0013] The feedback variable in the field-oriented system includes at least one harmonic. With respect to the electrical frequency of the electrical machine, the harmonic(s) have a positive and / or negative frequency of the kth order, with a respective amplitude and phase. One order that represents a relevant disturbance variable, since its amplitudes are particularly large, is, for example, the 6th order, preferably in the positive and negative directions. For example, with an electrical frequency of the electrical machine, i.e., the fundamental frequency, of 450 Hz in the time domain, the frequency of the 6th order is 450 Hz + 450 Hz * 6 = 3150 Hz, and in the negative direction, it is 450 Hz - 6 * 450 Hz = -2250 Hz. In the field-oriented system, whose coordinate system rotates with the electrical frequency of the electrical machine, the electrical frequency of the electrical machine is mapped to 0 Hz, resulting in frequencies of +2700 Hz and -2700 Hz for the harmonics of the 6th order.Depending on the magnitude of the amplitudes and the phase angle, force waves arise between the rotor and stator of the electric machine. These force waves act on the stator teeth as tangential and radial tooth forces, causing the harmonic overtones of the torque. The more relevant orders of the feedback variables are considered for the control system, the more effectively the disturbances are corrected.

[0014] In another embodiment of the invention, a comparator parameter is specified as a filter parameter in the harmonic-oriented system.

[0015] Preferably, the predefinable equalization parameter of the harmonic-oriented system comprises a setpoint in the harmonic-oriented system for generating a harmonic on a sinusoidal phase current for energizing at least one winding of the electrical machine.

[0016] The equalization variable is preferably a setpoint for generating a harmonic of a predefinable frequency or k-th order of the electrical frequency of the electric machine for superimposing the sinusoidal phase current or the fundamental frequency for energizing the electric machine. This setpoint is specified analytically or by means of a characteristic map, in particular as a function of a torque specification, a (phase) current setpoint, an actual current value, or a determined phase current. For use in the harmonic controller in the harmonic-oriented system, it is already appropriately transformed before being specified.

[0017] Advantageously, a filter setpoint is provided for the effective determination of a filtered feedback variable without harmonic content. When considering the setpoint for generating a harmonic of a predefined order as the filter setpoint, only the respective harmonic without superimposed interference signals is advantageously taken into account in the difference. This results in a filtered feedback variable without harmonic content and without superimposed interference signals. Setpoint changes are also not superimposed with interference signals.

[0018] In another embodiment of the method for controlling an electrical machine with a first filter and a filter input transformation, the method comprises the following steps: Filtering a predefined feedback equalization quantity using the first filter; determining the filtered feedback quantity without fundamental wave component as the difference between the feedback quantity and the filtered feedback equalization quantity; transforming the filtered feedback quantity without fundamental wave component to the equalization feedback quantity in a harmonic-oriented system using the filter input transformation, where the equalization feedback quantity is specified as the filter preset quantity.

[0019] A predefined harmonic feedback variable is filtered using the first filter. Preferably, the filtered harmonic feedback variable corresponds to a modeled fundamental frequency component of the closed-loop field-oriented control system. A filtered feedback variable without a fundamental frequency component is determined as the difference between the feedback variable and the filtered harmonic feedback variable. To use this feedback variable without a fundamental frequency component in a harmonic controller, the feedback variable without a fundamental frequency component is transformed into a harmonic-oriented feedback variable using the filter input transformation. The harmonic feedback variable is specified as the filter input value.

[0020] To control a harmonic in a harmonic controller, a mathematical transformation similar to the transformation from the time domain to the field-oriented domain is performed using a filter input transformation. This transformation involves converting the harmonic frequency from the field-oriented system to a harmonic-oriented system. For this purpose, the feedback signal, excluding the fundamental frequency component, is transformed into a DC feedback signal in the harmonic-oriented system using a filter input transformation. Quantities represented as AC quantities in the field-oriented system are represented as DC quantities in the harmonic-oriented system during steady-state operation of the electrical machine. These can then be controlled using standard control engineering methods.

[0021] The transformation from the field-oriented system to the harmonic-oriented system involves a rotation using a rotation matrix. An alternating quantity in the field-oriented system thus becomes a direct quantity in the harmonic-oriented system. For this purpose, the feedback variable is rotated by an angle corresponding to k times the current rotor angle; that is, for the transformation of the 6th-order harmonic of the electrical frequency, by 6 times the current rotor angle. For the kth-order harmonics in the positive direction, the rotation is in the positive direction; for the kth-order harmonics in the negative direction, the rotation is in the negative direction. The resulting direct quantities in the harmonic-oriented system can be characterized or described using complex numbers or as complex parameters, e.g., as iPosReal, iPoslmag, or as iNegReal and iNeglmag.

[0022] Besides rotation, other transformations can also be used. For example, the complex components iDSin and IDCos can be calculated by multiplying the d-current with the sine function (depending on the k-fold rotor angle) and with the cosine function, and the complex components iQSin and IQCos can be calculated by multiplying the q-current with the sine function and with the cosine function (also called frequency mixing or heterodyning).

[0023] As another alternative description, complex harmonics with amplitude and phase can be used for the d-current and q-current, respectively. Similarly, the components can also be represented as an ellipse with height, width, rotation, and phase by superimposing two counter-rotating phasors with different amplitudes and phases, preferably for particularly efficient calibration.

[0024] Advantageously, an alternative filter setting parameter is provided for the effective determination of a filtered feedback parameter without harmonic content.

[0025] In another embodiment of the invention, the predefinable GW equalization variable of the field-oriented system comprises a setpoint for generating the fundamental wave of a sinusoidal phase current for energizing at least one winding of the electrical machine.

[0026] The fundamental frequency (FRF) equalization variable is a setpoint for generating a fundamental wave with the electrical frequency of the electric machine for powering the electric machine. This setpoint is specified analytically or by means of a characteristic map, in particular as a function of a torque specification, a (phase) current setpoint, or an actual current value, preferably a determined phase current. For use in a fundamental frequency controller in a field-oriented system, it is already appropriately transformed before being specified.

[0027] Advantageously, a GW equalization parameter is provided to determine an alternative filter preset parameter.

[0028] In another embodiment of the invention, filtering the predefinable GW equalization quantity by means of the filter includes a low-pass filtering of the GW equalization quantity.

[0029] Advantageously, an effective method for removing the fundamental wave component of the GW equalization quantity is provided.

[0030] In another embodiment of the invention, the steps of determining, filtering, and inversely transforming the filtered input parameter are performed for multiple and different orders of the input parameter. This results in a multitude of harmonics, each assigned to a different order. The multitude of harmonics is taken into account when determining a filtered feedback parameter without harmonic content as the difference between the feedback parameter and the multitude of harmonics.

[0031] Advantageously, an optimized determination of a filtered feedback variable without harmonic content is provided for a fundamental frequency controller.

[0032] In another embodiment of the method for controlling an electric machine, it further comprises a fundamental frequency controller, wherein the fundamental frequency controller includes a fundamental frequency input transformation, a fundamental frequency controller, and a fundamental frequency output transformation. The method further comprises the following steps: Determine a machine feedback variable, where the machine feedback variable comprises an actual value of the electrical machine; transform the machine feedback variable using the gateway input transformation to the feedback variable in the field-oriented system; determine the gateway control deviation as the difference between the specified gateway equalization variable and the filtered feedback variable without harmonic content in the field-oriented system; determine a gateway equalization variable using the gateway controller as a function of the gateway control deviation; transform the gateway equalization variable back into a machine control variable using the gateway output transformation; and energize at least one winding of the electrical machine as a function of the machine control variable.

[0033] Fundamental wave control is used to regulate the alternating quantities of the phase currents, preferably sinusoidal, which are to be controlled in the time domain. To control an electric machine that can be connected to or linked with the fundamental wave controller, a machine feedback variable, an actual value, from the electric machine is acquired in the time domain. The machine feedback variables are preferably the phase currents of an electric machine. This machine feedback variable comprises the phase current as the fundamental wave and, as disturbances, harmonics that are superimposed on the phase current through the electric machine. In the time domain, the phase current is an alternating quantity superimposed with other alternating quantities of harmonics. To control the fundamental wave, a transformation from the time domain to the field-oriented domain is performed. For this purpose, the machine feedback variable is transformed to the feedback variable in the field-oriented system by means of a fundamental wave input transformation.Preferably, "GW" in this application denotes the control steps and transformations used for controlling the fundamental frequency. During steady-state operation of the electric machine, alternating quantities in the time domain result in DC quantities in the field-oriented system. These can be controlled using standard control engineering methods. Accordingly, a GW control deviation is determined as the difference between the specified GW equalization variable and the filtered feedback variable without harmonic content in the field-oriented system. A GW equalization variable is determined as a function of the GW control deviation using a GW controller. For further use in controlling or energizing the electric machine in the time domain, the GW equalization variable is transformed back into a machine control variable in the time domain by means of the GW output transformation.In the time domain, the machine control variable comprises an alternating quantity, a fundamental frequency, and at least one further superimposed alternating quantity, a harmonic. Finally, the method includes a step for energizing the electrical machine depending on the machine control variable.

[0034] Advantageously, a method for an effective fundamental frequency controller is provided.

[0035] In another embodiment of the method for controlling an electric machine, it further comprises a harmonic controller with an input transformation, a controller, and an output transformation. The method includes the following additional steps: Transforming the filtered feedback variable without fundamental wave component into a real-time feedback variable in a harmonic-oriented system using the input transformation; determining a control deviation as the difference between a predefined real-time feedback variable and the real-time feedback variable in the harmonic-oriented system; determining a real-time control variable using the controller as a function of the control deviation; inverting the real-time control variable into a manipulated variable in the field-oriented system using the output transformation; superimposing the real-time control variable with the manipulated variable, whereby in the inverting step of transforming the real-time control variable into a machine manipulated variable using the real-time control output transformation, the output variable of the superposition of the real-time control variable with the manipulated variable is inverted into the machine manipulated variable.

[0036] To use the feedback variable without its fundamental component in a harmonic controller, the feedback variable without its fundamental component is transformed into a DC feedback variable in a harmonic-oriented system by means of the input transformation. The input transformation preferably corresponds to the filter input transformation described above. A control deviation is determined as the difference between a predefined DC control variable and the DC feedback variable in the harmonic-oriented system. A DC control variable is then determined as a function of the control deviation. This DC control variable, as a DC variable in the harmonic-oriented system, is transformed back into a manipulated variable in the field-oriented system by means of the output transformation for further use in the field-oriented control of the electric machine. In the field-oriented system, the manipulated variable comprises an AC variable, a harmonic.The manipulated variable, as the output signal of the harmonic controller, is superimposed or added to the harmonic equalization variable in the field-oriented system. This output variable of the superposition in the field-oriented system is then back-transformed by the harmonic output transformation to a machine manipulated variable in the time domain for further use in controlling or energizing the electrical machine. In the time domain, the machine manipulated variable comprises an AC quantity, a fundamental frequency, and at least one further superimposed AC quantity, a harmonic.

[0037] Advantageously, a method for an effective fundamental and harmonic controller is provided.

[0038] Furthermore, the invention relates to a computer program which includes instructions which, when executed by a computer, cause it to perform the steps of the method described so far.

[0039] Furthermore, the invention relates to a computer-readable storage medium comprising instructions which, when executed by a computer, cause it to perform the steps of the method described so far.

[0040] Furthermore, the invention relates to a device for controlling an electric machine, comprising a computing unit, a first filter, a filter input transformation, and a harmonic filter, wherein the harmonic filter includes a second filter and a filter output transformation. The device is configured to perform the steps of the described method.

[0041] Advantageously, a device is provided for the effective determination of a filtered feedback variable without harmonic content for a fundamental frequency controller.

[0042] In another embodiment of the invention, the device comprises a fundamental frequency controller, wherein the fundamental frequency controller includes a fundamental frequency input transformation, a fundamental frequency controller, and a fundamental frequency output transformation. The device is configured to perform the steps of the described method.

[0043] Advantageously, a device for effective fundamental frequency control of an electric machine is provided.

[0044] In another embodiment of the invention, the device comprises a harmonic controller, wherein the harmonic controller includes an input transformation, a controller, and an output transformation. The device is configured to perform the steps of the described method.

[0045] Advantageously, a device for effective, combined fundamental and harmonic control of an electric machine is provided.

[0046] Furthermore, the invention relates to an electric drive system comprising an electric machine and a described device. Such an electric drive system serves, for example, to power an electric vehicle. The method and the device enable optimized operation of the drive train.

[0047] Furthermore, the invention relates to a vehicle with a described drive system. Advantageously, a vehicle is thus provided which includes a device with which an electric machine is effectively controlled.

[0048] It is understood that the features, properties and advantages of the method according to the invention apply accordingly to the device or drive system and the vehicle and vice versa.

[0049] Further features and advantages of embodiments of the invention will become apparent from the following description with reference to the accompanying drawings. Brief description of the drawing

[0050] The invention will be explained in more detail below using some figures, including: Figure 1 a schematic control structure for determining a filtered feedback variable without harmonic content for a fundamental frequency controller Figure 2 a schematic rule structure for determining a constant feedback variable in a harmonic-oriented system Figure 3 a schematic control structure for controlling an electrical machine Figure 4 a schematic control structure of a harmonic controller Figure 5 A schematically represented flowchart for a method for controlling an electrical machine. Figure 6 a schematically depicted device for controlling an electric machine Figure 7a schematically represented vehicle with an electric drive system Embodiments of the invention

[0051] The Figure 1Figure 1 shows a schematic control structure for determining a filtered feedback variable without harmonic content, IdqFunda, for a fundamental frequency controller. A feedback variable, Idq, is determined. In a harmonic-oriented system, a filter setpoint, FV, is determined as the input for a harmonic filter 150. The filter setpoint, FV, is filtered by a second filter, 142. The filtered filter setpoint, FV, is transformed by the filter output transformation, 132, to a harmonic value, IdqHrmc, in the field-oriented system. Finally, a filtered feedback variable without harmonic content, IdqFunda, is determined as the difference between the feedback variable, Idq, and the harmonic value, IdqHrmc. Preferably, at least one winding of a connectable electrical machine, 190, is energized depending on the filtered feedback variable without harmonic content, IdqFunda.

[0052] The Figure 2Figure 1 shows a schematic control structure for determining a feedback variable in a harmonic-oriented system. A predefined feedback variable Idq* is filtered, preferably by low-pass filtering, using a first filter 140. A feedback variable Idq is then determined in a field-oriented system. The difference between the feedback variable Idq and the filtered feedback variable Idq* yields a filtered feedback variable without a fundamental component, IdqWoFunda. This filtered feedback variable without a fundamental component, IdqWoFunda, is then transformed into a feedback variable IHrmc in a harmonic-oriented system using a filter input transformation 112.

[0053] The Figure 3Figure 1 shows a schematic control structure for controlling an electric machine 190. The electric machine 190 is depicted as a unit consisting of an inverter 192 and an electric motor 194. The fundamental frequency controller 200 comprises a fundamental frequency input transform 210, a fundamental frequency controller 220, and a fundamental frequency output transform 230. A machine feedback variable labc of the electric machine is determined in the time domain and fed to the fundamental frequency input transform 210. The machine feedback variable labc is transformed into the field-oriented system by means of the fundamental frequency input transform 210 to the feedback variable Idq. The feedback variable Idq is fed to the harmonic filter 150. The filter setpoint variable FV is fed to the harmonic filter as a further input signal. The output signal of the harmonic filter is the filtered feedback variable without harmonic content, IdqFunda.A gate control deviation is determined as the difference between a predefined gate control variable Idq* and the filtered feedback variable without harmonic content IdqFunda in the field-oriented system. A gate control variable is determined by the gate controller 220 as a function of the gate control deviation. Preferably, the manipulated variable UdqHrmc* is determined as a function of the feedback variable Idq using a harmonic controller 100. Preferably, the gate control variable is superimposed with the manipulated variable UdqHrmc*. The gate control variable, or preferably the output variable of the superposition in the field-oriented system, is transformed into a machine manipulated variable Uabc* in the time domain by the gate output transformation 230. The machine manipulated variable Uabc*, preferably a phase voltage, is provided to the electrical machine 190 to supply current to at least one winding.The phase voltage is generated by means of the inverter 192 and applied to at least one winding of the electric motor 194.

[0054] The Figure 4Figure 1 shows a schematic control structure of a harmonic controller 100 with the first filter 140. The harmonic controller 100 comprises an input transformation 110. A predefined harmonic equalization variable Idq* is filtered by the filter 140, preferably using a low-pass filter. A feedback variable Idq is then determined in a field-oriented system. The difference between the feedback variable Idq and the filtered harmonic equalization variable Idq* yields a filtered feedback variable without a fundamental component, IdqWoFunda. This filtered feedback variable without a fundamental component, IdqWoFunda, is transformed by the input transformation 110 into a direct feedback variable IHrmc in a harmonic-oriented system. The harmonic controller 100 further comprises a controller 120 and an output transformation 130.A calculated difference between a predefined computational variable IHrmc* and the feedback variable IHrmc in the harmonic-oriented system is fed to the controller 120 as a control deviation and input variable. Using the controller 120, a computational variable UHrmc* is determined as a function of the control deviation. This computational variable UHrmc* in the harmonic-oriented system is transformed by means of the output transformation into a manipulated variable UdqHrmc* in the field-oriented system.

[0055] The Figure 5Figure 400 shows a schematic flowchart for a method 400 for controlling an electric machine 190. The method begins with step 401. Preferably, in step 402, a machine feedback variable labc of the electric machine is determined in the time domain. Preferably, in step 404, this machine feedback variable labc is transformed into the field-oriented system to the feedback variable Idq using the feedback input transformation 210. In step 410, a feedback variable Idq is determined. Preferably, in step 411, a predefinable feedback equalization variable Idq* is filtered using the first filter 140. Preferably, in step 412, the filtered feedback variable without fundamental frequency component IdqWoFunda is determined as the difference between the feedback variable Idq and the filtered feedback equalization variable Idq*.Preferably, in step 413, the filtered feedback variable without fundamental frequency component IdqWoFunda is transformed into a direct feedback variable IHrmc in a harmonic-oriented system using the filter input transformation 112. In step 414, a filter setpoint FV is determined in a harmonic-oriented system. Here, either a direct feedback variable IHrmc*, a target variable, is specified as the filter setpoint FV in the harmonic-oriented system, or the direct feedback variable IHrmc, an actual variable, is specified as the filter setpoint FV. In step 415, the filter setpoint FV is filtered using the second filter 142. In step 416, the filtered filter setpoint FV is back-transformed into a harmonic variable IdqHrmc in the field-oriented system using the filter output transformation 132.In step 417, a filtered feedback variable without harmonic content, IdqFunda, is determined as the difference between the feedback variable Idq and the harmonic IdqHrmc, or a plurality of harmonics IdqHrmc_k, each assigned to a different order. Preferably, in step 418, a feedback control deviation is determined as the difference between the specified feedback control variable Idq* and the filtered feedback variable without harmonic content, IdqFunda, in the field-oriented system. Preferably, in step 419, a feedback control variable is determined as a function of the feedback control deviation using the feedback controller 220. Preferably, in step 480, at least one winding of a connectable electrical machine 190 is energized as a function of the filtered feedback variable without harmonic content, IdqFunda.Preferably, in step 420, the filtered feedback variable without fundamental frequency component IdqWoFunda is transformed by the input transformation 110 to a DC feedback variable IHrmc in a harmonic-oriented system. Preferably, in step 480, at least one winding of an electrical machine 190 is energized depending on the DC feedback variable IHrmc. In step 430, a difference between a predefinable DC control variable IHrmc* and the DC feedback variable IHrmc is determined as the control deviation and fed to the controller 120 as an input variable. In step 440, a DC control variable UHrmc* is determined by the controller as a function of the control deviation. In step 450, this DC control variable UHrmc* in the harmonic-oriented system is transformed by the output transformation to a manipulated variable UdqHrmc* in the field-oriented system.Preferably, in step 480, at least one winding of an electric machine 190 is energized depending on the manipulated variable UdqHrmc*. Preferably, in step 460, the gate control variable is superimposed with the manipulated variable UdqHrmc*. Preferably, in step 470, the output variable of the superposition in the field-oriented system is transformed into a machine manipulated variable Uabc* in the time domain by means of the gate control output transformation 230. Preferably, in step 480, at least one winding of the electric machine 190 is energized depending on the machine manipulated variable Uabc*. The method ends with step 490.

[0056] The Figure 6Figure 1 shows a schematic representation of a device 300 for controlling an electric machine 190. The electric machine 190 is depicted as a unit consisting of an inverter 192 and an electric motor 194. The device 300 comprises a harmonic controller 100 and a processing unit 310 for controlling and implementing the structure of the harmonic controller 100. The device preferably includes a fundamental frequency controller 200, which is also controlled and implemented by means of the processing unit 310. The device is configured to perform the process steps described above and thus to operate and control the electric machine 190.

[0057] The Figure 5Figure 1 shows a schematic representation of a vehicle 600, which includes an electric drive system 500. The drive system 500 comprises the electric machine 190, which includes an inverter 192 and an electric motor 194, and a device 300 for controlling the electric machine, as shown in Figure 2. Figure 6 described. Preferably, the electric drive system comprises a battery for supplying the electric drive system 500 with electrical energy.

Claims

1. Method (400) for controlling an electric machine (190) having a fundamental controller (200, 220), having a harmonic filter (150), the harmonic filter (150) comprising a second filter (142) and a filter output transformer (132), comprising the steps of: ascertaining (410) a feedback variable (Idq) of the electric machine, the feedback variable comprising an actual variable of a fundamental and of a harmonic of a specified frequency in a field-oriented system; determining (414) a filter specification variable (FV) in a harmonic-oriented system, filtering (415) the filter specification variable (FV) by means of the second filter (142), back-transforming (416) the filtered filter specification variable (FV) by means of the filter output transformer (132) to form a harmonic variable (IdqHrmc) in the field-oriented system, ascertaining (417) a filtered feedback variable without a harmonic component (IdqFunda) as the difference between the feedback variable (Idq) and the harmonic variable (IdqHrmc); energizing (480) at least one winding of the electric machine (190) as a function of the filtered feedback variable without a harmonic component (IdqFunda), characterized in that the filtered feedback variable without a harmonic component (ldqFunda) is provided for the fundamental controller (200, 220).

2. Method according to Claim 1, wherein a DC reference variable (IHrmc*) in the harmonic-oriented system is specified as the filter specification variable (FV), and in particular the DC reference variable (IHrmc*) comprises a target variable in the harmonic-oriented system, for generating a harmonic on a sinusoidal phase current for energizing at least one winding of the electric machine (190).

3. Method according to Claim 1, having a first filter (140) and a filter input transformer (112), comprising the steps of: filtering (411) a specifiable fundamental DC reference variable (Idq*) by means of the first filter (140); ascertaining (412) the filtered feedback variable without a fundamental component (IdqWo-Funda) as the difference between the feedback variable (Idq) and the filtered fundamental DC reference variable (Idq*); transforming (413) the filtered feedback variable without a fundamental component (IdqWoFunda) by means of the filter input transformer (112) to form a DC feedback variable (IHrmc) in an harmonic-oriented system, wherein the DC feedback variable (IHrmc) is specified as the filter specification variable (FV).

4. Method according to Claim 3, wherein the specifiable fundamental DC reference variable (Idq*) of the field-oriented system comprises a target variable for generating the fundamental of a sinusoidal phase current for energizing at least one winding of the electric machine (190).

5. Method according to either of Claims 3 and 4, wherein filtering (411) the specifiable fundamental DC reference variable (Idq*) comprises low-pass filtering the fundamental DC reference variable (Idq*).

6. Method according to one of the preceding claims, wherein the steps of determining (414), filtering (415) and back-transforming (416) the filtered filter specification variable (FV) are carried out for several and different orders of the filter specification variable (FV) and lead to a large number of harmonic variables (IdqHrmc_k) which are respectively assigned to different orders, wherein the large number of harmonic variables (IdqHrmc_k) are taken into account when ascertaining (417) a filtered feedback variable without a harmonic component (IdqFunda) as the difference between the feedback variable (Idq) and the large number of harmonic variables (ldqHrmc_k).

7. Method according to one of the preceding claims, having the fundamental controller (200), the fundamental controller comprising a fundamental input transformer (210), a fundamental controller (220) and a fundamental output transformer (230), comprising the steps of: ascertaining (402) a machine feedback variable (labc), the machine feedback variable comprising an actual variable of the electric machine; transforming (404) the machine feedback variable (labc) by means of the fundamental input transformer (210) to form the feedback variable (Idq) in the field-oriented system; ascertaining (418) the fundamental control deviation as the difference between the specified fundamental DC reference variable (Idq*) and the filtered feedback variable without a harmonic component (IdqFunda) in the field-oriented system; ascertaining (419) a fundamental DC manipulated variable by means of the fundamental controller (220) as a function of the fundamental control deviation; back-transforming (470) the fundamental DC manipulated variable by means of the fundamental output transformer (230) to form a machine manipulated variable (Uabc*), and energizing (480) at least one winding of the electric machine (190) as a function of the machine manipulated variable (Uabc*).

8. Method (400) according to Claim 7, having a harmonic controller (100), the harmonic controller comprising an input transformer (110), a controller (120) and an output transformer (130), comprising the steps of: transforming (420) the filtered feedback variable without a fundamental component (IdqWoFunda) by means of the input transformer (110) to form a DC feedback variable (IHrmc) in a harmonic-oriented system; ascertaining (430) a control deviation as the difference between a specifiable DC reference variable (IHrmc*) and the DC feedback variable (IHrmc) in the harmonic-oriented system; ascertaining (440) a DC manipulated variable (UHrmc*) by means of the controller as a function of the control deviation; back-transforming (450) the DC manipulated variable (UHrmc*) by means of the output transformer to form a manipulated variable (UdqHrmc*) in the field-oriented system; superimposing (460) the fundamental DC manipulated variable with the manipulated variable (UdqHrmc*), wherein, in the step of back-transforming (470) by means of the fundamental output transformer (230) to form a fundamental manipulated variable (Uabc*), the output value of the superimposition (460) of the fundamental DC manipulated variable with the manipulated variable (UdqHrmc*) is back-transformed to form the fundamental manipulated variable (Uabc*).

9. Computer program, comprising commands which, when the program is executed by a device according to Claim 11, cause said device to execute the method / the steps of the method according to Claims 1 to 8.

10. Computer-readable storage medium, comprising commands which, when executed by a device according to Claim 11, cause said device to execute the method / the steps of the method according to Claims 1 to 8.

11. Device (300) for controlling an electric machine (190), comprising a fundamental controller (200), comprising a computer unit (310), a first filter (140), a filter input transformer (112) and a harmonic filter (150), the harmonic filter (150) comprising a second filter (142) and a filter output transformer (132), wherein the device is designed to execute the steps of the method according to one of Claims 1-6.

12. Device (300) according to Claim 11, comprising the fundamental controller (200), the fundamental controller comprising a fundamental input transformer (210), a fundamental controller (220) and a fundamental output transformer (230), wherein the device is designed to execute the steps of the method according to Claim 7.

13. Device (300) according to Claim 12, comprising a harmonic controller (100), the harmonic controller comprising an input transformer (110), a controller (120) and an output transformer (130), wherein the device is designed to execute the steps of the method according to Claim 8.

14. Electric drive system (500) comprising an electric machine (190) and a device (300) according to one of Claims 11 to 13.

15. Vehicle (600) comprising an electric drive system (500) according to Claim 14.