Method, computer program and device for controlling a multi-phase rotating field machine in the event of an interruption of the current in at least one phase of the rotating field machine

Abstract

Method (200) for controlling a multiphase rotating field machine in the event of an interruption of the current in at least one phase of the rotating field machine, comprising: Receiving (220) control parameters of the rotating field machine control and a direction of rotation of the rotor; Calculating (230) a position parameter corresponding to a plurality of possible rotor positions of the rotor based on the control parameters, wherein the calculation (230) of the position parameter is based on the equation: 1 3 ⋅ ψ PM ∫ [ ( PWM 2 − PWM 3 ) ⋅ U dc − 2 ⋅ R s ⋅ I s 2 − 2 ⋅ L s ⋅ d I s 2 dt ] dt = sin ( θ el ) This occurs when the first of three phases of the rotating field machine fails, or based on the equation: 1 3 ⋅ ψ PM ∫ [ ( PWM 1 − PWM 3 ) ⋅ U dc − 2 ⋅ R s ⋅ I s 1 − 2 ⋅ L s ⋅ d I s 1 dt ] dt = cos ( θ el − π 6 ) This occurs when a second of the three phases of the rotating field machine fails, or based on the equation: 1 3 ⋅ ψ PM ∫ [ ( PWM 1 − PWM 2 ) ⋅ U dc − 2 ⋅ R s ⋅ I s 1 − 2 ⋅ L s ⋅ d I s 1 dt ] dt = cos ( θ el + π 6 ) This occurs when a third of three phases of the rotating field machine fails, where each Ψ PM a rotor flux, PWMi a pulse-width modulated signal for the i-th phase, Udc an intermediate circuit voltage of an inverter, R s a stator resistor, I si a phase current of the i-th phase, and L s a stator inductance of the rotating field machine; and Determining (240) an actual rotor position based on the position parameter and the direction of rotation.

Description

The following exemplary embodiments are in the field of methods and devices for controlling a polyphase rotating field machine in the event of a current of at least one phase of the rotating field machine being interrupted.For converting electrical energy into kinetic energy, so-called rotating field or three-phase machines are used, among other designs of electric motors. Rotating field machines can comprise a stator with an annular arrangement of so-called phases, which can generate magnetic fields that are variable over time, and can thereby set a magnetic rotor, for example a rotor with a permanent magnet, in rotation. Rotating field machines, for example permanently excited synchronous machines (PSM or PMSM) or asynchronous machines (ASM), are used in different applications, e.g. hybrid car, electric car, servo drives, machine tools, etc. Fault conditions that may occur during operation of the machine, e.g., failure of a phase, may require control operation. In this case, in the case of some types of machines, in particular those with three phases, it may be the case that an alternating field arises in the event of failure of one phase. If problems arise during a rotor position measurement, this could possibly not be detected and could possibly lead to undesired machine behavior and, in the worst case, to a reversal of a rotational direction of the rotor. However, conventional methods for estimating rotor position may only be used during fault-free operation of the machine.In this context, DE 10 2013 219 908 A1 discloses an emergency operation for a three-phase machine in the event of a phase interruption, wherein the motor can be operated "sensorless".It is therefore desirable to provide an improved concept for position monitoring of a rotor of a rotating field machine during a control operation of the machine.This need is addressed by an apparatus and a method for controlling a polyphase rotating field machine in the event of a current of at least one phase of the rotating field machine being interrupted, according to the independent patent claims.According to a first aspect, exemplary embodiments relate to a method for controlling a polyphase rotating field machine in the event of a current of at least one phase of the rotating field machine being interrupted. The method includes receiving control parameters of the control of the rotating field machine and a rotational direction of the rotor. The method also comprises calculating a position parameter corresponding to a plurality of possible rotor positions of the rotor on the basis of the control parameters. The method also includes determining an actual rotor position based on the position parameter and the rotational direction. Control parameters can be, for example, in connection with pulse width modulation, electrical variables in a phase of the machine, or also parameters inherent in the machine, for example stator inductance or stator resistance. Control parameters can also include, for example, a pole wheel flux or manipulated variables such as voltage or current specifications. The direction of rotation can be given, for example, by a sign of an angular speed. The position parameter can be e.g. a function of the actual rotor position or characterized by it. The position parameter can also permit ambiguous or ambiguous conclusions about the rotor position, for example, if the position parameter is a trigonometric function of a rotor position angle. It can thus be made possible to perform a mathematical determination of the rotor position even when the machine is in a control mode, or in other words, when operating a closed control loop is omitted. In addition, the determination could be made with higher reliability.In some exemplary embodiments, the method further comprises receiving at least one position measurement value of a rotor of the rotating field machine and comparing the actual rotor position with the position measurement value. It can thus be made possible to use a comparison of the measured and calculated position in order to detect possible faults of a position sensor for the rotor.In some embodiments, the method further comprises generating a reference signal if a result of the comparing is greater than a threshold value. Disturbances in the position measurement of the rotor can thus be communicated to a user or to a system controlling the rotating field machine, which can considerably facilitate timely taking of corresponding countermeasures.In some exemplary embodiments, the control parameters comprise a first value group and a second value group different from the first value group. In this case, the calculation of the position parameter comprises a first characterization of an input voltage for ready-to-use phases of the rotating field machine on the basis of the first value group and a second characterization of the input voltage on the basis of the second value group. As a result, a mathematical rule can be found by means of which the position parameter can be isolated and determined from known variables. This can provide a basis for a unique determination of the rotor position.In some exemplary embodiments, the first value group comprises a pulse-width-modulated signal for an operational phase and an intermediate circuit voltage of a pulse inverter for generating the phase currents for the rotating field machine.In some exemplary embodiments, the second value group comprises a phase current for an operational phase of the rotating field machine, an angular speed of the rotor, an electrical resistance and an inductance of a stator of the rotating field machine.In the present case, the calculation of the position parameter takes place based on the equation: if a first of three phases of the rotary field machine fails, or based on the equation: if a second of three phases of the rotary field machine fails, or based on the equation: if a third of three phases of the rotary field machine fails. In this case, Ψ PM is a pole wheel flux, PWMi is a pulse-width-modulated signal for the ithphase, Udc is an intermediate circuit voltage of an inverter, R s is a stator resistor, I si is a phase current of the ithphase, and L s is a stator inductance of the rotating field machine.In some embodiments, calculating the position parameter provides a trigonometric function of the rotor position. This can comprise in particular a sine or a cosine of the rotor position or a variable associated therewith.In some exemplary embodiments, a position of the rotor is restricted to the first or second quadrants of a Cartesian coordinate system with a zero point on the rotor axis of rotation by a positive sign of the position parameter, if the trigonometric function is a sine, or is restricted to the first or fourth quadrants if the trigonometric function is a cosine. If the sign is negative, this can accordingly be the third or fourth quadrant for sine, or the second or third quadrant for cosine. It can thus be possible to limit the plurality of possible rotor positions to at most two.In some exemplary embodiments, the determination of the actual rotor position takes place in such a way that, by a positive sign of the rotational direction and an increase of the position parameter during a time period, a position of the rotor within the time period is restricted to the first or fourth quadrants of the Cartesian coordinate system if the trigonometric function is a sine, or is restricted to the third or fourth quadrant if the trigonometric function is a cosine. The same restriction can also apply in the case of a negative sign and additionally a reduction of the position parameter. With a negative sign and an increase of the position parameter, this can accordingly be the second or third quadrant for sine, or the first or second quadrant for cosine. The same restriction can also apply in the case of a positive sign of the direction of rotation and additionally a reduction of the position parameter. This allows any ambiguity in the rotor position that may still be present to be resolved.According to a further aspect, embodiments relate to a program having a program code for carrying out the method when the program code is executed on a computer, a processor or a programmable hardware component.According to yet another aspect, exemplary embodiments relate to a device for controlling a polyphase rotating field machine in the event of a current of at least one phase of the rotating field machine being interrupted. The apparatus includes an input for receiving control parameters of the control of the rotating field machine and a rotational direction of the rotor. The device is designed to calculate a position parameter corresponding to a plurality of possible rotor positions of the rotor on the basis of the control parameters, and to unambiguously determine an actual rotor position on the basis of the position parameter and the direction of rotation. For this purpose, the device can comprise an angle diagnostic module or network, for example. Thus, angle monitoring for a rotor position can be performed with higher reliability even when controlling the rotating field machine.In some exemplary embodiments, the device further comprises a further input for receiving at least one position measurement value of a rotor of the rotating field machine. The device is designed to compare the actual rotor position with the position measurement value. The apparatus also comprises an output for providing a reference signal if a result of the comparison is greater than a predefined limit value. This can offer a possibility of creating additional redundancy and thus preventing possible interference in the rotor position measurement.In some embodiments, the apparatus further comprises a rotating field machine. The rotating field machine is a three-phase permanent-excited synchronous machine.Further advantageous embodiments are described in more detail below with reference to exemplary embodiments illustrated in the drawings, to which exemplary embodiments are, however, not restricted. The following are shown: FIG. 1 shows a pulse inverter at a break of a phase for a three-phase rotating field machine according to a comparative example; FIG. 2 shows a flow diagram of a method for controlling a polyphase rotating field machine in the event of a current of at least one phase of the rotating field machine being interrupted, according to one exemplary embodiment; FIG. 3 shows a coordinate system for illustrating a relationship between position parameter, rotor position and rotational direction according to an exemplary embodiment; FIG. 4 shows a device for controlling a polyphase rotating field machine in the event of a current of at least one phase of the rotating field machine being interrupted, according to one exemplary embodiment; FIG. 5 shows a flow chart for an algorithm for monitoring a rotor position in the case of different phase failures according to one exemplary embodiment; FIG. 6 shows a profile of phase currents, induced input voltage of the machine, electrical angle, sine of the electrical angle, difference of actual and measured sine of the rotational angle according to one exemplary embodiment; FIG. 7 shows a profile of phase currents, induced input voltage of the machine, electrical angle, sine of the electrical angle, difference of actual and measured sine of the rotational angle according to a further exemplary embodiment; and FIG. 8 shows a profile of phase currents, induced input voltage of the machine, electrical angle, sine of the electrical angle, difference of actual and measured sine of the rotational angle according to a further exemplary embodiment.Various embodiments will now be described in more detail with reference to the accompanying drawings, in which some embodiments are illustrated. In the figures, the thickness dimensions of lines, layers and / or regions may be exaggerated for clarity.In the following description of the accompanying figures, which show only some exemplary embodiments, the same reference numerals may denote the same or comparable components. Furthermore, summary reference signs can be used for components and objects that occur multiple times in an exemplary embodiment or in a drawing, but are described together with regard to one or more features. Components or objects which are described with the same or summarizing reference numerals can be embodied identically, but optionally also differently, with regard to individual, multiple or all features, for example their dimensions, unless the description explicitly or implicitly reveals otherwise.Although embodiments may be modified and modified in various ways, embodiments are shown by way of example in the figures and will be described in detail herein. It is to be understood, however, that there is no intention to limit embodiments to the particular forms disclosed, but rather that embodiments are intended to cover all functional and / or structural modifications, equivalents, and alternatives falling within the scope of the invention. Identical reference numerals designate identical or similar elements throughout the description of the figures.Note that an element referred to as being "connected" or "coupled" to another element may be directly connected or coupled to the other element or intervening elements may be present. On the other hand, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. Other terms used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.).The terminology used herein is for describing particular embodiments only and is not intended to be limiting of the embodiments. As used herein, the singular forms "a", "an", and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It is further understood that the terms such as "includes," "including," "has," and / or "having," as used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more features, integers, steps, operations, elements, components, and / or groups thereof.Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having the meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly defined herein.In the case of rotary field machines (PSM or ASM) which can be used in different applications (e.g. hybrid car, electric car, servo drives, machine tools), voltage intermediate circuit inverters (WR) can be used for generating manipulated variables (e.g. voltages). As the semiconductor in the WR, IGBT, MOSFET, GTO can be used. In the voltage intermediate circuit inverter (WR), the desired voltages (for example for a rotating field machine) are set at its output by different modulation methods. The modulation method used is often the sub-oscillation method pulse width modulation (PWM) or space vector modulation.An inverter for generating the desired voltages from pulse width modulated signals is described in more detail in FIG. 1. An inverter 100 having MOSFETs 110, 120, and 130 is shown as an example of a voltage supply for a three-phase rotating field machine. With the MOSFETs 110, 120 and 130, the current can be switched on in both directions. Further exemplary embodiments may also use other power semiconductors, for example IGBTs (insulated gate bipolar transistors) or GTOs (gate turn-off thyristors). Only during the off-time between the upper MOSFET 110- 1; 120- 1 and 130- 1 and the lower MOSFET 110- 2; 120- 2 and 130- 2 can the return diodes 115; 125 and 135 take over the current in each phase U, V or W in this phase U, V or W. Depending on the sign of the current, the current may be conducted via the lower (e.g., 115-1) or the upper diode (e.g., 115-2) of a phase. The upper MOSFET (e.g., 110-1) or the upper diode (e.g., 115-2) of a phase U, V or W is always connected to +U dc and the lower MOSFET (e.g., 110-2) or the lower diode (e.g., 115-2) is always connected to -U dc. In the voltage intermediate circuit inverter 100 shown in FIG. 1, the desired voltages (e.g. for a rotating field machine) at its output can be set by different modulation methods. As the modulation method, for example, a sub-oscillation method, pulse width modulation (PWM), or space vector modulation can be used.The generated PWM values from the control or the control for generating a specific voltage vector change with the desired voltage frequency and voltage amplitude. The magnitude of the voltage amplitude is a measure of the length of the voltage vector set at the WR.In the normal case, field-oriented regulation (FOR) is used for the actuation of a permanently excited synchronous machine (PSM). For the current measurement, a current sensor 140- 1; 140- 2 is used in each phase or, as shown in FIG. 1, in at least two of the phases, which current sensor is embodied here as a measuring resistor (shunt), for example.The regulated voltages make it possible to generate currents I s1, I s2 and I s3 in the phases U, V and W. The phases are comprised by a machine stator with the stator resistor R s and the stator inductance L s. In the phases, the voltages E 1, E 2 and E 3 are induced by the currents I s1, I s2 and I s3 flowing there and the rotational speed.In the event of faults in the machine or in the inverter, one of the three phases of the machine can be interrupted. By way of example, an interruption 150 of phase U is illustrated in FIG. 1. One cause can be, for example, a failure of one or two MOSFETs of the inverter in one phase or contact problems between inverter and machine. The machine may thus not be correctly regulated, because the desired voltage vector can no longer be correctly adjusted because of the failure of a phase. An alternating field can be generated in the machine instead of a rotating field, which can lead to variations in the torque. However, it may be possible to continue to actuate the machine without redundancy in the inverter or in the machine, and without additional complexity, despite a failure of a phase of a PSM. The torque yield, and thus also the power yield of the machine, can be improved under certain circumstances in the event of a fault.For the regulation (FOR) or control (FOS) of the machine, a determination of the rotor position may be necessary. For the FOS, this can be achieved by using a rotor position sensor. Incorrect information about the rotor position (or the electrical angle θ el) can lead to an incorrect transformation of the phase currents in the d,q coordinate system fixed to the rotor, which in turn can lead to a corruption of the required torque. In the extreme case, a change in the sign of the torque can take place in the machine. This can lead to undesirable machine behavior. For example, an electric car to be accelerated forward could be accelerated rearward. Or in the case of steering, the steering wheel can be rotated in the wrong direction because the force (or the torque) accelerates the machine in the wrong direction.If the rotor position sensor functions correctly, the FOR or FOS can correspondingly set the desired torque well. If a fault occurs in the rotor position sensor, the functionality of the FOR or FOS can be impaired. In order to prevent an unnoticed rotor position sensor fault from occurring, it may be desirable to immediately detect a fault in position.To achieve this, a redundant structure (or, in other words, a second rotor position sensor) or an estimation model for the position of the machine may be used. The two variants may offer a possibility for monitoring the rotor position sensor. For cost and space reasons in a drive, the redundant structure with the second rotor position sensor may not be able to be executed for the rotor position diagnosis. Alternatively, the estimation model for the rotor position and the rotational speed can be used. Conventional methods may provide numerous methods for calculating rotor position and speed for rotating field machine (e.g., PSM), but these cannot be used in phase separation.In the event of a fault in the phase interruption, an alternating field can arise in the machine rather than a rotating field. The conventional methods for rotor position estimation cannot be applied directly to a phase-locked machine. Nevertheless, it is desirable to find a way to estimate the rotor position of the PSM machine in order that a diagnostic for monitoring the rotor position sensor can be established.The following exemplary embodiments show a concept as can be made possible to ascertain information about the rotor position in the event of a phase in the machine failing. By evaluating this rotor position sensor information, fault cases in the sensor can be detected and risks in the functionality of the drive can be avoided in good time.Exemplary embodiments may provide the possibility of monitoring the functionality of the rotor position sensor for a PSM in the event of a phase failure, such that disturbances which cause errors in the functionality of the rotor position sensor are detected and corresponding countermeasures can be taken.An exemplary embodiment for monitoring the rotor position sensor is based on monitoring the electrical angle (mechanical angle multiplied by number of pole pairs) of the machine. The rotor position may be measured and calculated via a machine model of the machine in a second path. The two pieces of information about the electrical angle can be compared with one another. Information about additional errors in the drive can be obtained with the comparison.The calculation of the input voltages of the machine can be carried out in a drive, for example without further errors, via two different paths. This can form the machine model of the machine, which reproduces information about the rotor position of the machine. The following steps show the procedure for obtaining the machine rotor position information. As a result of the failure of one phase, the machine is biphasic, for example as shown in FIG. 1, and an alternating field is formed in the machine. For the current measurement in FOR, at least two current sensors (for example shunts in low-cost drives) can be used. In the event of a failure of one phase, at least one of the two current sensors can thus still remain intact and the phase current of a still connected phase can thus be measured.FIG. 2 shows a flow chart for a method 200 for controlling a polyphase rotating field machine in the event of a current of at least one phase of the rotating field machine being interrupted. The method 200 comprises receiving 220 control parameters of the control of the rotating field machine and a direction of rotation of the rotor. The method 200 also comprises calculating 230 a position parameter corresponding to a plurality of possible rotor positions of the rotor on the basis of the control parameters. The method 200 also comprises ascertaining 240 an actual rotor position based on the position parameter and the rotational direction. Control parameters can be, for example, in connection with pulse width modulation, electrical variables in a phase of the machine, or also parameters inherent in the machine, for example stator inductance or stator resistance. Control parameters can also include, for example, a pole wheel flux or manipulated variables such as voltage or current specifications. The direction of rotation can be given, for example, by a sign of an angular speed. The position parameter can be e.g. a function of the actual rotor position or characterized by it. The position parameter can also permit ambiguous or ambiguous conclusions about the rotor position, for example, if the position parameter is a trigonometric function of a rotor position angle. As an example, consider the case where phase U is interrupted. The phase current in phase U is thus equal to zero. Due to the node rule in the stator or star of the machine, the sum of all three currents is equal to zero. Because of I s1=0 this yields the relationship between the currents of the two still connected phases of the machine:In some exemplary embodiments, the control parameters comprise a first value group and a second value group different from the first value group. In this case, the calculation 230 of the position parameter comprises a first characterization 232 of an input voltage for ready-to-use phases of the rotating field machine based on the first value group and a second characterization 232 of the input voltage based on the second value group. As a result, a mathematical rule can be found by means of which the position parameter can be isolated and determined from known variables.In one exemplary embodiment, the first characterization 232 of the input voltage of the machine is carried out via measured variables of the machine (e.g. the machine current and the machine rotational speed) and via the machine parameters which can be included by the first value group. The input voltage of the machine U s23 is calculated here via:In this case, the following are used:R s: the stator resistance,L s: the stator inductance,E 2: the induced voltage in phase V,E 3: the induced voltage in phase W.The induced voltages E 2 and E 3 can be obtained, for example, from the transformation of the induced voltages from the d,q coordinate system E d and E q into the stator-fixed u,v,w coordinate system. The input voltage of the machine can thus be determined with the measured machine measurement variables and parameters by:The second characterization 234 of the input voltage U s23 of the machine can be effected via setpoint values by the PWM values and the intermediate circuit voltage U dc which can be comprised by the second value group:If no further errors are present in the drive, the two input equations GL can be used. 3 and GL. 4 of the machine; the machine model is obtained:Receiving 220 control parameters of the control of the rotating field machine comprises, for example, those in GL. PWM values occurring in FIG. 5, the intermediate circuit voltage U dc, phase currents I s2, I s3, the stator resistance R s, the stator inductance L s, the induced voltage in phase VE 2 and the induced voltage in phase WE 3. Calculating 230 a position parameter corresponding to a plurality of possible rotor positions of the rotor based on the control parameters may further be performed by transforming the GL. 5:The term on the right side is a residual (induced) voltage after subtracting the ohmic and inductive losses from the input voltage of the machine U s23Rest:Further simplifications are given:The equation can now be integrated on both sides according to time:By integrating the remaining induced voltage of the machine, the calculation 230 (see FIG. 2 ) of the sine of the electrical angle can thus be carried out. In other words, calculating 230 the position parameter provides a trigonometric function of the rotor position. The sine can thus correspond to the position parameter, which can correspond to a plurality of possible position positions of the rotor. The sine results in:FIG. 3 shows the sine and cosine of an angle θ el in a period of 2π in a cartesian coordinate system centered on the rotor rotation axis. The sine value is the same for values in the first quadrant Q1 of the coordinate system and the second quadrant Q2 (or in the third quadrant Q3 and the fourth quadrant Q4), respectively. The sine can thus provide information as to whether the angle is on the upper side or on the lower side. In some exemplary embodiments, a position of the rotor is thus restricted to the first or second quadrants of a Cartesian coordinate system with zero point on the rotor axis of rotation by a positive sign of the position parameter, if the trigonometric function is a sine, or is restricted to the first or fourth quadrants if the trigonometric function is a cosine. If the sign is negative, this can accordingly be the third or fourth quadrant for sine, or the second or third quadrant for cosine.As already mentioned, the method 200 comprises receiving 220 a rotational direction of the rotor. For this purpose, a method for a voltage diagnosis can be used, for example. If the speed is positive (ω el >0), the electrical angle will traverse the individual quadrants in the order Q1, Q2, Q3, Q4 and then back to Q1. In other words, the machine electrical angle may travel from θ el1 to a larger angle θ el3 at positive speed for each scan step. If the speed is negative (ω el<0), then the electrical angle will traverse the individual quadrants in the order Q1, Q4, Q3, Q2 and then back to Q1. The electrical angle of the machine may otherwise travel from θ el1 to a smaller angle θ el2 at negative speed for each sampling step. The d,q coordinate system rotates accordingly relative to the α,β coordinate system. The sign of the engine speed can thus be monitored via the voltage diagnosis. If the diagnosis does not detect an error, the machine has the correct rotational speed and thus also the correct rotational speed sign. By means of this additional information (speed monitoring via voltage diagnosis), a sine can be used as a monitoring signal for the electrical angle (or rotor position). Analogously, the cosine of the electrical angle can be used for monitoring the electrical angle (or rotor position).In yet other words, the determination 220 of the actual rotor position takes place in such a way that, by a positive sign of the rotational direction and an increase of the position parameter during a time period, a position of the rotor within the time period is restricted to the first or fourth quadrants of the Cartesian coordinate system if the trigonometric function is a sine, or is restricted to the third or fourth quadrant if the trigonometric function is a cosine. The same restriction can also apply in the case of a negative sign and additionally a reduction of the position parameter. With a negative sign and an increase of the position parameter, this can accordingly be the second or third quadrant for sine, or the first or second quadrant for cosine. The same restriction can also apply in the case of a positive sign of the direction of rotation and additionally a reduction of the position parameter.Analogously to GL.16, which applies to a phase break of phase U, the following cosine can be determined from the residual voltage for the case of the phase break in phase V:In the case of phase separation in phase W, the following cosine can be determined from the residual voltage:In some exemplary embodiments, method 200 further includes receiving 210 at least one position measurement value of a rotor of the rotating field machine and comparing 250 the actual rotor position with the position measurement value. The position measurement value can be determined, for example, by means of a position sensor. It can thus be made possible to use a comparison of the measured and calculated position in order to detect possible faults of a position sensor for the rotor.In some embodiments, the method 200 further comprises generating 260 a reference signal if a result of the comparing is greater than a threshold value. Disturbances in the position measurement of the rotor can thus be communicated to a user or to a system controlling the rotating field machine, which can considerably facilitate timely taking of corresponding countermeasures. This will be explained in more detail in the following exemplary embodiment.FIG. 4 shows a block diagram for a device 400 for controlling machine 402 in the event of a phase failure. The device 400 comprises a torque adjustment module 404 which receives a target torque M Ref as an input value (for example user-defined) and can adjust it to a new target torque M RefN. A current generator 406 generates desired current values I sdRef, and I sqRef, which can be represented as vector components of a desired current in d,q coordinates, on the basis of the new desired torque M RefN. These values can be passed on to a modulator 408 and converted into modified setpoint current values I sdRefN, and I sqRefN. An FOS algorithm 410 can comprise, for example, a decoupling module which can calculate manipulated variables, for example voltage specifications U sd_k and U sq_k in d,q coordinates, on the basis of the modified setpoint current values I sdRefN, and I sqRefN. For this purpose, the discrete equations GL.19 and GL can be used. 20 for the two required voltages in the d- and q-axes U sd_k and U sq_k can be used:Here, ω el(= ω s) is the electrical angular velocity, θ m is the mechanical angle, θ el is the electrical angle, Z p is the number of pole pairs of the machine, U sα, U sβ is the voltages in the α,β coordinate system, U sd_k, U sq_k is the required voltages in the d,q coordinate system (at a current sampling time step), U sd_k-1, Usq_k-1 is the required voltages in the d,q coordinate system (at a sampling time step immediately preceding the current sampling time step), wherein the voltage U sq_k-1 can correspond to an immediately preceding voltage of U sq_k without the term (W PM* ω el) I sd_k, I sq_k the desired currents in the d,q coordinate system (at a current sampling time step), I sd_k-1, I sq_k-1 the desired currents in the d,q coordinate system coordinate system (at a sampling time step immediately preceding the current sampling time step), R (=R s) the stator resistance of the machine, Ψ (= Ψ PM) the pole wheel flux of the machine, T Ed the electrical time constant of the machine in the d-axis (=L sd / R), T Eq the electrical time constant of the machine in the q-axis (=L sq / R), T 1 the desired time constant in the d-axis, T 2 the desired time constant in the q-axis, T the sampling time used, U dc the intermediate circuit voltage (corresponds to the battery voltage in some applications in the automotive industry), and PWM 1,2,3 the PWM values for driving the inverter.After conversion of the manipulated variables into the α,β coordinate system to the voltages U sα and U sβ by means of a coordinate transformer 412, a vector modulator 414 generates a pulse-width modulated signal for each phase on the basis of the voltage specifications U sα and U sβ that is to say PWM 1, PWM 2 and PWM 3 for a three-phase machine 402, for example. The pulse inverter 416, which may be constructed and function, for example, in accordance with the pulse inverter 100 shown in FIG. 1, generates the phase currents for the phases U, V and W of the rotating field machine 402, illustrated here as a three-phase PSM by way of example. Further, upon failure of a phase, the pulse inverter 416 may provide a phase failure signal 418 (phase failure) to the torque adjustment module 404, the current generator 406, and the FOS algorithm 410. The effect of the phase failure signal 418 will be explained in more detail below.As already explained, the mechanical angle θ mech of the rotor can be measured by means of a position sensor 420, and can further be converted into the electrical angle θ el by multiplication 422 by the pole pair number Z p. Time derivative 424 supplies mechanical angular velocity ω mech, and after a further multiplication 426 by pole pair number Z p it supplies electrical angular velocity ω el. The electrical angular velocity ω el may be used for calculations by the torque adjustment module 404, the current generator 406, and the FOS algorithm 410 in another sampling step.The device 400 can be used for controlling a polyphase rotating field machine 402 in the event of a current of at least one phase of the rotating field machine 402 being interrupted. In one exemplary embodiment, the device 400 comprises an angle diagnostic module 428 or network for this purpose. The apparatus 400, or angle diagnostic module 428, includes an input for receiving control parameters of the rotary machine controller and a direction of rotation of the rotor. The device 400 is configured, for example by means of the angle diagnostic module 428, to calculate a position parameter corresponding to a plurality of possible rotor positions of the rotor on the basis of the control parameters, and to unambiguously determine an actual rotor position on the basis of the position parameter and the direction of rotation. In FIG. 4, the control parameters can comprise, for example, the occurring PWM values, the intermediate circuit voltage U dc, phase currents I s2, I s3. The direction of rotation of the rotor can be given by the electrical angular speed ω el.In this exemplary embodiment, the angle diagnostic module 428 furthermore comprises a further input for receiving at least one position measurement value of a rotor of the rotating field machine, corresponding for example to an electrical angle θ el. In this case, the angle diagnostic module 428 is configured to compare the actual rotor position with the position measurement value. The apparatus 400 also comprises an output for providing a reference signal if a result 430 of the comparison is greater than a predefined limit value. This can offer a possibility of creating additional redundancy and thus preventing possible interference in the rotor position measurement. The result 430 of the comparison can be, for example, a difference between the sine or cosine of the position measurement value and the sine or cosine of the determined actual rotor position.The angle diagnostic module 428 determines the machine electrical angle sine and cosine depending on the interrupted phase in two ways and then compares them to each other, resulting in a difference 430 of the machine electrical angle sines. This difference 430 can be evaluated by the passing level (e.g. the difference 430 can be integrated and a warning signal can be set when a threshold is exceeded) and on the basis of which the corresponding measure is carried out (e.g. switching off the drive).FIG. 5 shows a flowchart of the FOS algorithm 410 for monitoring the PSM machine taking into account the phase break. After a start 502 of the algorithm 410, the phase interrupt signal 418 (phase failure, cf. FIG. 4 ) which represents information about the interrupted phase is used in this case to monitor the phase interrupt error. In the normal or fault-free case without phase break, the FOR runs and the angle diagnostic 504- 1 for biphasic operation is disabled. Upon phase suspension, the system immediately switches from FOR to FOS (such as FIG. 4 ) and angle diagnostic 504- 2 may be enabled from a minimum speed amount n DiagMin onward. This may be helpful, if necessary, since under certain circumstances an induced voltage is set only starting from the minimum rotational speed value n DiagMin in the machine, which voltage can possibly be evaluated better. For the angle diagnosis 504- 2, the corresponding angle diagnosis module 428 (cf. FIG. 4 ) may receive the control parameters ω el, I s123, U dc and PWM 123 already enumerated.It is followed by a determination 506 as to which phase is interrupted. Upon interruption of phase U 508- 1, an electrical angle calculation 510- 1 is performed via GL. 16. Upon interrupting phase V 508-2, an electrical angle calculation 510-2 is performed via GL.17. Upon interruption of phase W 508- 3, an electrical angle calculation 510- 3 is performed via GL. 18. Here, on the one hand, a phase current of the two continuous phases, the electric angle of the machine θ el, the electric angular velocity ω el, the machine parameters, the PWM values of the two phases that have not been interrupted, and the DC link voltage of the inverter U dc may be used. These quantities are used in the machine model of the machine with interrupted phase for the calculation of the sine / cosine of the electrical angle. On the other hand, the sine / cosine of the measured electrical angle θ elMess is calculated. By calculating the difference 512 between the two calculations of the sine / cosine of the electrical angle, the difference Sin / Cos-Diff is obtained. A result of an evaluation 514 of the difference is forwarded to a monitoring level 516 in order to initiate the corresponding measures when a fault is detected. The following is an end 518 of the algorithm for monitoring the PSM machine taking into account a phase failure.FIGS. 6, 7 and 8 show the simulation results for the case of a phase break in U. In detail, the curves of phase currents 610; 710; 810, induced input voltage of machine 620; 720; 820, electrical angle 630; 730; 830, sine of electrical angle 640; 740; 840, and difference of actual and measured sine of rotational angle 650; 750; 850 are shown here. The results are recorded with the sinusoidal torque profile at acceleration up to 2000 rpm. Until t=0.03 s, the machine is normally controlled with FOR. Starting from t=0.03 s, a fault case of the interruption of phase U is simulated in all FIGS. 6, 7 and 8. At this time, the FOR is immediately switched to the FOS drive. Phase current 610; 710; 810 in phase U is equal to zero due to the phase break in all FIGS. 6, 7 and 8. The two calculated electrical angle sines 640 are approximately coincident in FIG. 6, indicating substantially fault free biphasic operation. If the two electric angle sines 650 look different, it could be concluded that there is a faulty behavior of the machine (e.g. position sensor fault, asymmetry, winding short circuit) in two-phase operation. In FIGS. 7 and 8, at the time t=0.15 s, an error in the form of an offset of the electrical angle of 90 degrees (FIG. 7 ) or 180 degrees (FIG. 8 ) has additionally been simulated. Because of the angle offset, deviations can arise in the torque, which can lead to a change in the sign of the torque at high rotational speeds. This could pose a risk for the drive (e.g. self-steering in power steering). The monitoring of the sine 740 of the electrical angle shows a large deviation in FIG. 7 starting from the time t=0.15 and an even larger deviation in FIG. 8 at a larger offset (180 degrees). During the evaluation, this difference can lead to a diagnosis with incorrect behavior of the drive.In the case of a trapezoidal torque profile, the results during the sign change of the phase currents may not be taken into account in order not to use incorrect diagnostic results. This transition region can take place in a small part of the electrical period of the machine (=period of the phase current).The monitoring of the voltage in the remaining part of the electrical period (without phase current alternating ranges) may be sufficient in this case.By way of exemplary embodiments, in the event of a phase interruption, the PSM machine can continue to be operated with more than half the power. This can be helpful, for example, in the case of a vehicle steering system or an electric car for a trip to the next workshop. Under certain circumstances, an already existing design of the drive can be used, and the use of additional hardware can be dispensed with. Exemplary embodiments could provide a possibility for monitoring the PSM machine in the event of a phase failure of position sensor errors, winding short circuits, phase breaks, etc. In conventional methods, on the other hand, a position sensor error in PSMs can lead to deviations in the torque, and possibly even to sign changes of the torque, which can mean an undesired machine behavior (e.g. self-steering in power steering, reverse acceleration in the case of an intended forward acceleration in the electric car). Embodiments may also avoid short circuits in the windings that could otherwise result in excessive currents, add additional damage to the drive, and draw much current from the battery, which may impair functionality of other electrical devices in the car. In other words, embodiments may also provide an improvement in the service life of a battery. The required power for a desired action (e.g. steering with auto power steering, acceleration with traction machine in the electric car) may not be provided in the event of an additional phase failure. By means of the diagnosis according to exemplary embodiments, this can be identified more quickly under certain circumstances and taken according to the necessary measures.The features disclosed in the preceding description, the following claims and the appended figures can be important and implemented both individually and in any combination for the realization of an exemplary embodiment in its various configurations.Although some aspects have been described in connection with a device, it is understood that these aspects also represent a description of the corresponding method, so that a block or a component of a device is also to be understood as a corresponding method step or as a feature of a method step. Analogously, aspects described in connection with or as a method step also represent a description of a corresponding block or detail or feature of a corresponding device.Depending on certain implementation requirements, embodiments of the invention may be implemented in hardware or in software. The implementation can be carried out using a digital storage medium, for example a floppy disk, a DVD, a Blu-ray disk, a CD, a ROM, a PROM, an EPROM, an EEPROM or a FLASH memory, a hard disk or another magnetic or optical memory, on which electronically readable control signals are stored, which can cooperate or cooperate with a programmable hardware component such that the respective method is carried out.A programmable hardware component may be formed by a processor, a computer processor (CPU= C Processing Unit), a graphics processor (GPU= Graph Processing Unit), a computer, a computer system, an application specific integrated circuit (ASIC= Appli-Specific Integrated Circuit), an integrated circuit (IC= Integr Circuit), a system-on-chip (SOC=System on Chip), a programmable logic element, or a field programmable gate array including a microprocessor (FPGA=Field Programmable Gate Array).The digital storage medium can therefore be machine- or computer-readable. Some exemplary embodiments thus comprise a data carrier having electronically readable control signals which are capable of interacting with a programmable computer system or a programmable hardware component in such a way that one of the methods described herein is carried out. An embodiment is thus a data carrier (or a digital storage medium or a computer-readable medium) on which the program for carrying out one of the methods described herein is recorded.In general, embodiments can be implemented as a program, firmware, computer program or computer program product having a program code or as data, wherein the program code or the data is or are effective to carry out one of the methods when the program runs on a processor or a programmable hardware component. The program code or the data can, for example, also be stored on a machine-readable carrier or data carrier. The program code or the data can be present, inter alia, as source code, machine code or bytecode and as another intermediate code.A further embodiment is further a data stream, a signal sequence or a sequence of signals representing the program for carrying out one of the methods described herein. The data stream, signal sequence or sequence of signals may be configured, for example, to be transferred over a data communication link, for example, over the Internet or other network. Exemplary embodiments are thus also signal sequences representing data, which are suitable for transmission via a network or a data communication connection, the data representing the program.A program according to an exemplary embodiment can implement one of the methods during its execution, for example, by reading out memory locations or writing a datum or a plurality of data into these locations, as a result of which switching processes or other processes are possibly caused in transistor structures, in amplifier structures or in other electrical, optical, magnetic components or components operating according to another functional principle. Accordingly, data, values, sensor values or other information can be acquired, determined or measured by a program by reading a memory location. A program can therefore capture, determine or measure variables, values, measured variables and other information by reading out one or more memory locations, and can bring about, cause or perform an action by writing into one or more memory locations and can actuate other devices, machines and components.The above-described embodiments are merely illustrative of the principles of the present invention. It is to be understood that modifications and variations of the arrangements and details described herein will be apparent to others skilled in the art. Therefore, it is intended that the invention be limited only by the scope of the following claims and not by the specific details presented herein by way of description and explanation of the embodiments.Reference numerals denote reference numerals100 Inverter 110- 1; 110- 2 phase U MOSFETs 115- 1; 115- 2 phase U retrace diode 120- 1; 120- 2 phase V MOSFETs 125- 1; 125- 2 phase V retrace diode 130- 1; 130- 2 phase W MOSFETs 135- 1; 135- 2 phase W retrace diode 140- 1; 140-2 current sensor 150 phase U interruption 200 method 210 receiving 220 receiving 230 calculating 232 characterizing 234 characterizing 240 ascertaining 250 comparing 260 generating 400 device 402 rotating field machine 404 module for torque adaptation 406 current generator 408 modulator 410 FOS algorithm 412 coordinate transformer 414 vector modulator 416 pulse inverter 418 phase failure signal 420 position sensor 422 multiplication 424 time derivative 426 further multiplication 428 angle diagnostic module 430 result / difference 502 start of algorithm 504-1; 504-2 angle diagnostic 506 ascertaining 508-1; 508-2; 508-3 phase 510-1; 510-2 interruption; 510-3 Calculation of the electrical angle 512 Difference 514 Result of an evaluation 516 Monitoring plane 518 End of the algorithm 610 Phase currents 620 Induced input voltage of the machine 630 Electrical angle 640 Sine of the electrical angle 650 Difference of actual and measured sine of the rotational angle 710 Phase currents 720 Induced input voltage of the machine 730 Electrical angle 740 Sine of the electrical angle 750 Difference of actual and measured sine of the rotational angle 810 Phase currents 820 Induced input voltage of the machine 830 Electrical angle 840 Sine of the electrical angle 850 Difference of actual and measured sine of the rotational angle

Claims

A method (200) for controlling a polyphase rotating field machine in the event of a break in a current of at least one phase of the rotating field machine, comprising: receiving (220) control parameters of the control of the rotating field machine and a direction of rotation of the rotor; calculating (230) a position parameter corresponding to a plurality of possible rotor positions of the rotor on the basis of the control parameters, wherein the calculation (230) of the position parameter takes place on the basis of the equation: 1 3 ⋅ ψ P M FOLLOWING [ ( P W M 2 - P W M 3 ) ⋅ U d c - 2 ⋅ R s ⋅ I s 2 - 2 ⋅ L s ⋅ d I s 2 d t ] d t = sin ( θ e l ) if a first of three phases of the rotating field machine fails, or is based on the equation: 1 3 ⋅ ψ P M FOLLOWING [ ( P W M 1 - P W M 3 ) ⋅ U d c - 2 ⋅ R s ⋅ I s 1 - 2 ⋅ L s ⋅ d I s 1 d t ] d t = cos ( θ e l - π 6 ) if a second of three phases of the rotating field machine fails, or is based on the equation: 1 3 ⋅ ψ P M FOLLOWING [ ( P W M 1 - P W M 2 ) ⋅ U d c - 2 ⋅ R s ⋅ I s 1 - 2 ⋅ L s ⋅ d I s 1 d t ] d t = cos ( θ e l + π 6 ) , if a third of three phases of the rotating field machine fails, wherein Ψ PM is a pole wheel flux, PWMi is a pulse width modulated signal for the ithphase, Udc is an intermediate circuit voltage of an inverter, R s is a stator resistor, I si is a phase current of the ithphase, and L s is a stator inductance of the rotating field machine; and determining (240) an actual rotor position based on the position parameter and the direction of rotation.Method (200) according to claim 1, further comprising receiving (210) at least one position measurement value of a rotor of the rotating field machine and comparing (250) the actual rotor position with the position measurement value.The method (200) of claim 2, further comprising generating (260) a reference signal if a result of the comparing is greater than a threshold.Method (200) according to one of the preceding claims, wherein the control parameters comprise a first value group and a second value group different from the first value group, and wherein the calculation (230) of the position parameter comprises a first characterization (232) of an input voltage for operational phases of the rotating field machine based on the first value group and a second characterization (234) of the input voltage based on the second value group.Method (200) according to claim 4, wherein the first value group comprises a pulse width modulated signal for an operational phase and an intermediate circuit voltage of a pulse inverter for generating the phase currents for the rotating field machine.The method (200) according to any one of claims 4 or 5, wherein the second value group comprises a phase current for an operational phase of the rotating field machine, an angular speed of the rotor, an electrical resistance and an inductance of a stator of the rotating field machine.The method (200) according to any one of the preceding claims, wherein the calculating (230) of the position parameter provides a trigonometric function of the rotor position.The method (200) according to claim 7, wherein a position of the rotor is limited to the first or second quadrants of a Cartesian coordinate system with zero point on the rotor axis of rotation if the trigonometric function is a sine, or is limited to the first or fourth quadrants if the trigonometric function is a cosine, by a positive sign of the position parameter.The method (200) according to claim 8, wherein the determining (240) of the actual rotor position is carried out such that: by a positive sign of the rotational direction and an increasing of the position parameter during a time period, a position of the rotor within the time period is restricted to the first or fourth quadrants of the Cartesian coordinate system if the trigonometric function is a sine, or is restricted to the third or fourth quadrants if the trigonometric function is a cosine; or by a negative sign of the rotational direction and a decreasing of the position parameter during a time period, a position of the rotor within the time period is restricted to the first or fourth quadrants of the Cartesian coordinate system if the trigonometric function is a sine, or is restricted to the third or fourth quadrants if the trigonometric function is a cosine; or by a negative sign of the direction of rotation and increasing the position parameter during a period of time, a position of the rotor within the period of time is restricted to the second or third quadrant of the Cartesian coordinate system if the trigonometric function is a sine, or is restricted to the first or second quadrant if the trigonometric function is a cosine; or by a positive sign of the direction of rotation and decreasing the position parameter during a period of time, a position of the rotor within the period of time is restricted to the second or third quadrant of the Cartesian coordinate system if the trigonometric function is a sine, or is restricted to the first or second quadrant if the trigonometric function is a cosine.A program comprising program code for performing the method of any one of claims 1 to 9, when the program code is executed on a computer, a processor or a programmable hardware component.Device (400) for controlling a polyphase rotating field machine (402) in the event of a break in a current of at least one phase of the rotating field machine (402), comprising: an input for receiving control parameters of the control of the rotating field machine (402) and a direction of rotation of the rotor; wherein the device (400) is designed to calculate a position parameter corresponding to a plurality of possible rotor positions of the rotor on the basis of the control parameters, and to unambiguously determine an actual rotor position on the basis of the position parameter and the direction of rotation, wherein the calculation (230) of the position parameter is carried out based on the equation: 1 3 ⋅ ψ P M NONYL [ ( P W M 2 - P W M 3 ) ⋅ U d c - 2 ⋅ R s ⋅ I s 2 - 2 ⋅ L s ⋅ d I s 2 d t ] d t = sin ( θ e l ) if a first of three phases of the rotating field machine fails, or based on the equation: 1 3 ⋅ ψ P M NONYL [ ( P W M 1 - P W M 3 ) ⋅ U d c - 2 ⋅ R s ⋅ I s 1 - 2 ⋅ L s ⋅ d I s 1 d t ] d t = cos ( θ e l - π 6 ) , if a second of three phases of the rotating field machine fails, or based on the equation: 1 3 ⋅ ψ P M FOLLOWING FOLLOWING [( P W M 1 - P W M 2 ) ⋅ U d c - 2 ⋅ R s ⋅ I s 1 - 2 ⋅ L s ⋅ d I s 1 d t ] d t = cos ( θ e l + π 6 ) if a third of three phases of the rotating field machine fails, wherein ψ PM in each case, a pole wheel flux, PWMi, a pulse-width-modulated signal for the ithphase, Udc, an intermediate circuit voltage of an inverter, R s a stator resistor, I si a phase current of the ithphase, and L s is a stator inductance of the rotating field machine.The apparatus (400) according to claim 11, further comprising: a further input for receiving at least one position measurement value of a rotor of the rotating field machine (402), wherein the apparatus is configured to compare the actual rotor position with the position measurement value, and an output for providing a reference signal if a result (430) of the comparison is greater than a predefined limit value.The apparatus (400) of any of claims 11 or 12, further comprising the rotating field machine (402), wherein the rotating field machine (402) is a three-phase permanent-excited synchronous machine.

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