Control unit and method for controlling the operation of a three-phase machine, computer program product and drive train

Abstract

Control unit (1) for controlling the operation of a three-phase machine (4), in particular a three-phase motor, with: a current controller (2) which is configured to output a three-phase setpoint signal (i Soll ) and a three-phase measurement signal (i mess ) to receive and generate and output a three-phase control signal (u) from it in order to control the three-phase machine (4) accordingly, and a PLL filter (5) that is configured, a current value that has a time course (iu) and a phase angle (phi) el ) exhibits, to receive from one phase of the three-phase machine (4) and to rotate the current value by predetermined phase angles in order to obtain the current values ​​of the remaining phases, or Current values, each representing a time course (iu) and a phase angle (phi) el) to receive current values ​​from two phases of the three-phase machine (4) and to rotate one of the current values ​​or a current value combined from the two current values ​​by a predetermined phase angle in order to obtain the current value of the remaining phase, and the obtained current values ​​together with the received current value or the received current value together with the received current values ​​as the three-phase measurement signal (i mess to spend.

Description

[0001] The invention relates to a control unit for controlling the operation of a three-phase machine, in particular a three-phase motor, comprising a current controller configured to receive a three-phase setpoint signal and a three-phase measurement signal and to generate and output a three-phase control signal therefrom in order to control the three-phase machine accordingly. Furthermore, the invention relates to a method for controlling the operation of a three-phase machine, a computer program product, and a drive train.

[0002] In a field-oriented control method, current values ​​from the phases of a three-phase machine are recorded to obtain the controlled variables id and iq using Clarke and Park transformations. A loss of a current value from one or two phases can result in the controlled variables id or iq not being able to be determined. In addition, expensive current sensors are required to record the current values ​​in order to measure the currents of all phases. This leads to high implementation and control effort, as well as increased installation space requirements.

[0003] In the state of the art, various possible applications of PLL filters or PLL controllers in connection with current measurement or processing in control units for operating electrical machines are known: From DE 10 2017 222 420 A1 it is known to control an electrical machine by checking three phase currents using a PLL filter, which determines a current in a non-measured phase and compares it with measured currents for plausibility purposes.

[0004] From DE 11 2018 006 745 T5 it is known to use PLL filters to evaluate phase currents of two electrical machines connected in parallel and, if necessary, to monitor them for faults.

[0005] EP 3 681 035 A1 discloses a PLL filter that generates a filtered speed signal from α / β current values.

[0006] EP 1 655 828 A1 discloses feeding a rotor current value of a doubly fed asynchronous machine to a control system via a PLL filter. In one embodiment, a phase shift is performed by a separate element.

[0007] It is therefore an object of the present invention to reduce or at least mitigate these disadvantages of the prior art.

[0008] This object is achieved by the subject matter having the features of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.

[0009] A control unit according to the invention for controlling the operation of a three-phase machine, which may in particular be a three-phase motor, has a current controller which is designed to receive a three-phase setpoint signal and a three-phase measurement signal and to generate and output a three-phase control signal therefrom in order to control the three-phase machine accordingly.

[0010] The control unit further comprises a PLL filter configured to receive a current value, which has a time profile and a phase angle, from one phase of the three-phase machine and to rotate the current value, i.e. the time profile of the current value, by predetermined phase angles in order to obtain the current values ​​of the remaining phases. The PLL filter is further configured to output the received current values ​​together with the received current value as the three-phase current measurement signal. Since the PLL filter is capable of determining the current values ​​of the other two phases from the current value of one phase, it is sufficient to provide only one current sensor. Furthermore, the PLL filter can also determine the current values ​​in a case in which the current values ​​of the other two phases cannot be detected due to loss, e.g., due to sensor faults. Consequently, the control unit enables efficient and fail-safe control of the three-phase machine.

[0011] Alternatively, the PLL filter can be configured to receive current values, each having a time profile and a phase angle, from two phases of the three-phase machine. The PLL filter can then be configured to rotate one of the current values ​​by a predetermined angle to obtain the current value of the remaining phase. Furthermore, the PLL filter can be configured to rotate a current value combined from the two current values ​​by a predetermined phase angle to obtain the current value of the remaining phase. For example, an average of the two time profiles can be formed by shifting them to the same phase angle. The PLL filter is then configured to output the received current value together with the received current value as the three-phase current measurement signal. Consequently, the loss of a current value can be easily compensated. Furthermore, the number of current sensors can be reduced here as well.

[0012] Preferably, the current values ​​can be complex current values. Thus, rotation and determination of the missing current values ​​can be easily performed by rotating an effective value of the complex current values. In this case, the PLL filter can be configured to determine the complex current value from the received current value.

[0013] Advantageously, the current controller can be configured to output the three-phase control signal in the form of a PWM control signal, in particular as a PWM duty cycle. Accordingly, a converter can apply PWM voltages to the phases of the three-phase machine.

[0014] Preferably, the PLL filter can be configured to rotate the current value by 120° and 240°. Alternatively, the PLL filter can be configured to rotate the single current value or the combined current value by 120° or 240°. Consequently, the missing current value(s) can be easily obtained.

[0015] The detected current value(s) may contain a noise signal component. The PLL filter can then advantageously be configured to filter out the noise signal component from the current value(s). Consequently, the noise signal component is not rotated, so that the obtained current value(s) is / are free of the noise signal component.

[0016] A method according to the invention for controlling the operation of a three-phase machine, which may in particular be a three-phase motor, comprises the following steps: receiving a three-phase setpoint signal and receiving a three-phase measurement signal; generating a three-phase control signal from the three-phase setpoint signal and the three-phase measurement signal; and outputting the three-phase control signal.

[0017] Furthermore, before the step of receiving the three-phase current measurement signal, the method further comprises the following steps: receiving a current value, which has a time profile and a phase angle, from one phase of the three-phase machine and rotating the current value by predetermined phase angles to obtain the current values ​​of the remaining phases; and outputting the obtained current values ​​together with the received current value as the three-phase current measurement signal. Accordingly, it is sufficient to acquire only one current value of one phase of the three-phase machine, and the current values ​​of the remaining phases are then generated from the received current value. Consequently, efficient and fail-safe control of the three-phase machine is achieved.

[0018] Alternatively, the method further comprises the following steps before the step of receiving the three-phase current measurement signal: receiving current values, each having a time profile and a phase angle, from two phases of the three-phase machine and rotating one of the current values ​​or a current value combined from the current values ​​by a predetermined phase angle to obtain the current value of the remaining phase; and outputting the obtained current value together with the received current values ​​as the three-phase current measurement signal. Consequently, the loss of a current value can be easily compensated.

[0019] Preferably, the process is performed repeatedly. This ensures continuous provision of the three-phase current measurement signal.

[0020] Advantageously, the three-phase control signal can be output in the form of a PWM control signal, particularly as a PWM duty cycle. This allows a converter to apply appropriate PWM voltages to the phases of the three-phase motor.

[0021] Preferably, the received current value can be rotated by 120° and 240°. Alternatively, the single current value or the combined current value can be rotated by 120° or 240°. Consequently, the missing current value(s) can be easily obtained.

[0022] The detected current value or values ​​may contain a noise signal component. The method may then include a step of filtering the noise signal component from the current value or values ​​before the rotation step. Consequently, the noise signal component is not rotated, so that the obtained current value or values ​​are free of the noise signal component.

[0023] A computer program product according to the invention comprises instructions that, when executed by a computer, cause the computer to perform the steps of the method according to the invention. The computer can thus be easily configured as the control unit according to the invention.

[0024] The computer program product according to the invention can be stored on a computer-readable storage medium. Consequently, the program can be easily executed by the computer.

[0025] A drive train according to the invention comprises a three-phase machine, a converter configured to operate the three-phase machine according to a three-phase control signal, and a current sensor configured to detect a current value, which has a temporal profile and phase angle, from one phase of the three-phase machine. Alternatively, the drive train comprises two current sensors configured to detect current values, each having a temporal profile and phase angle, from two phases of the three-phase machine. Furthermore, the drive train comprises the control unit according to the invention. Consequently, the loss of one current value or two current values ​​can be easily compensated. Furthermore, the number of current sensors can be reduced.

[0026] The invention is explained in more detail below with reference to the figure: Fig. 1 shows a schematic equivalent circuit diagram of a drive train according to the invention.

[0027] The figure is purely schematic and serves solely to facilitate understanding of the invention. The same elements are provided with the same reference numerals.

[0028] Fig. 1 shows a schematic equivalent circuit diagram of a drive train 8 according to the invention. The drive train 8 comprises a control unit 1, which is designed to control the operation of a three-phase machine 4, in particular a three-phase motor. For this purpose, the control unit 1 comprises a current regulator 2, which is designed to generate a three-phase target signal i Soll and a three-phase measuring signal i messand generate a three-phase control signal u therefrom. The current controller 2, ie the control unit 1, then outputs the three-phase control signal u to a converter 3. The three-phase control signal u is preferably a PWM control signal, in particular a PWM duty cycle. The converter 3 then applies PWM voltages u pwm1 , and pwm2 and u pwm3 according to the PWM control signal to the stator windings of the three-phase machine 4.

[0029] According to one embodiment of the invention, a phase rotator 6 of a PLL filter 5 is designed to receive a current value from a phase of the three-phase machine 4. As in Fig. As shown in Figure 1, the current value consists of a time profile iu and a phase angle phi el After reception, the current value, ie the time course i uof the current value, by predetermined phase angles, ie a first predetermined phase angle and a second predetermined phase angle, by the phase rotator 6 of the PLL filter 5 to obtain the current values ​​of the remaining two phases of the three-phase machine 4. In particular, the phase angle phi el of the received current value 120° and 240° are added to obtain the phase angles of the current values ​​of the other two phases of the three-phase machine 4. Subsequently, the PLL filter 5 outputs the current values ​​of the two remaining phases obtained by rotation together with the received current value as the three-phase measurement signal i mess to current controller 2.

[0030] The recorded current value, ie the time course of the current value, can, as in Fig.1, a noise signal component 7 may be superimposed. The PLL filter 5 can then be designed to filter out the noise signal component 7 from the current value, ie, the time profile.

[0031] It should be noted that the PLL filter 5 can also be designed to calculate a complex current from the received current value and then rotate an effective value of the complex current by the predetermined phase angles.

[0032] The current controller 2 is then, as already mentioned, able to calculate from the received three-phase current measurement signal i Mess to determine and output the three-phase control signal u using a known field-oriented control method or vector control method.

[0033] According to a second embodiment of the invention, the phase rotator 6 of the PLL filter 5 is configured to receive current values ​​from two phases of the three-phase machine 4. The current values ​​are again composed of a time profile and a phase angle.

[0034] The PLL filter 5 can then be configured to rotate only one of the two current values ​​by a predetermined phase angle. Depending on the selected current value and its phase shift relative to the other received current value, the predetermined phase angle by which the time profile of the selected current value is rotated can be 120° or 240°.

[0035] Alternatively, the PLL filter 5 can also be configured to calculate a combined current value from the two current values ​​and rotate this combined current value by a predetermined angle. For example, a current value can be rotated by the phase difference between the two received current values. This means that the two current values ​​are superimposed in phase. Subsequently, an average value between the two current values—i.e., the time profiles of the two current values—can be calculated to obtain the combined current value. The combined current value is then rotated by the predetermined angle to obtain the current value of the remaining phase.

[0036] The present invention thus enables the reduction of the number of current sensors and the control of a three-phase machine in the event of a loss of a current value of one phase or in the event of a loss of current values ​​of two phases. List of reference symbols 1 control unit 2 current regulators 3 inverters 4 three-phase machine 5 PLL filters 6 phase shifters 7 Noise signal component 8 Drivetrain

Claims

[1] Control unit (1) for controlling the operation of a three-phase machine (4), in particular a three-phase motor, comprising: a current controller (2) which is designed to generate a three-phase current setpoint signal (i Soll ) and a three-phase measuring signal (i mess ) and to generate and output a three-phase control signal (u) therefrom in order to control the three-phase machine (4) accordingly, and a PLL filter (5) which is designed a current value that has a time profile (iu) and a phase angle (phi el ) from one phase of the three-phase machine (4) and to rotate the current value by predetermined phase angles in order to obtain the current values ​​of the remaining phases, or Current values, each with a time profile (iu) and a phase angle (phi el) from two phases of the three-phase machine (4) and to rotate one of the current values ​​or a current value combined from the two current values ​​by a predetermined phase angle in order to obtain the current value of the remaining phase, and the received current values ​​together with the received current value or the received current value together with the received current values ​​as the three-phase current measurement signal (i mess ) to be issued. [2] Control unit (1) according to claim 1, wherein the current regulator (2) is designed to output the three-phase control signal (u) in the form of a PWM control signal. [3] Control unit (1) according to claim 1 or 2, wherein the PLL filter (5) is designed to rotate the current value by 120° and 240° or to rotate the one current value or the combined current value by 120° or 240°. [4] Control unit (1) according to one of claims 1 to 3, wherein the current value or the current values ​​have a noise signal component (7) and the PLL filter (5) is designed to filter out the noise signal component (7) from the current value or the current values. [5] Method for controlling the operation of a three-phase machine (4) comprising the following steps: Receiving a three-phase current setpoint signal (i Soll ) and receiving a three-phase current measuring signal (i mess ); Generating a three-phase control signal (u) from the three-phase setpoint signal (i Soll ) and the three-phase measuring signal (i mess ); and Output of the three-phase control signal (u), where the procedure before the step of receiving the three-phase measuring signal (i mess ) further comprises: Receiving a current value that has a time profile (iu) and a phase angle (phi el) from one phase of the three-phase machine (4) and rotating the current value by predetermined phase angles to obtain the current values ​​of the remaining phases, or Receiving current values, each with a time profile (iu) and a phase angle (phi el ) of two phases of the three-phase machine (4) and rotating one of the two current values ​​or a current value combined from the two current values ​​by a predetermined phase angle in order to obtain the current value of the remaining phase, and Outputting the received current values ​​together with the received current value or the received current value together with the received current values ​​as the three-phase current measurement signal (i mess ). [6] The method according to claim 5, wherein the method is carried out repeatedly. [7] Method according to claim 5 or 6, wherein the three-phase control signal (u) is output in the form of a PWM control signal. [8] Method according to one of claims 5 to 7, wherein the received current value is rotated by 120° and 240° or the one current value or the current value combined from the two current values ​​is rotated by 120° or 240°. [9] A computer program product comprising instructions which, when executed by a computer, cause the computer to carry out the steps of the method according to any one of claims 5 to 8. [10] Drivetrain (8) with: a three-phase machine (4), a converter (3) which is designed to operate the three-phase machine (4) in accordance with a three-phase control signal, a current sensor which is designed to measure a current value having a time profile (iu) and a phase angle (phi el ) from a phase of the three-phase machine (4), or two current sensors which are designed to measure current values, each of which has a time profile (iu) and a phase angle (phi el ) of two phases of the three-phase machine (4), and the control unit (1) according to one of claims 1 to 4.

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