CN108450053A - Method and device for rotor position estimation in a multi-motor system - Google Patents

Abstract

The invention relates to a method for determining the position of a rotor in a system (10) with a plurality of electric machines (20, 30, 40), which transmit their torque to a common transmission (50), so that The method includes the steps of: detecting the rotor position of at least one rotor (22) of the first motor (20) through a position sensor (23); parameters, wherein based on the rotor position of at least one rotor (22) of the first electric machine (20) and at least one measured parameter of the at least another electric machine (30, 40), the at least one other electric machine (30, 40) can be estimated The rotor position of the rotor (32, 42). Furthermore the invention relates to a system with a plurality of electric motors (20, 30, 40) which transmit their torque to a common transmission (50), wherein the system has a controller (70), the A controller is used to implement the method according to the invention. Furthermore, the invention relates to a controller (70) for carrying out the method according to the invention and/or for controlling and/or regulating the system (10) according to the invention.

Description

Method and device for rotor position estimation in a multi-motor system

The invention relates to a method and a device for determining the position of a rotor in a multimotor system, that is to say a system with a plurality of electric motors, for example a plurality of electric motors, which can transmit their torque to a common transmission device. The measured rotor position of the electrical machine is used for the control and/or regulation system. Methods and devices for detecting the rotor position in electric machines are known, for example, from DE 44 37 793 A1 or DE 10 2007 049 788 A1.

Known systems for rotor position determination in multi-motor systems are characterized by the use of rotational angle sensors or position sensors for each motor, so that the position of the rotor, for example relative to the stator, can be detected for each motor by the position sensor . The data on the rotor position are used to control and/or regulate the system. The use of sensors for each machine is characterized by a high control and/or regulation quality, but also entails high costs and a high expenditure on installation space.

Furthermore, systems for sensorless control and/or regulation are known. A sensorless system is characterized by a correspondingly lower outlay and a lower construction space cost, however, this leads to problems at low rotational speeds and in the field weakening region. Furthermore, in a sensorless system, especially when the system is rotated, it can cause the problem of inaccurate position detection.

The technical problem to be solved by the present invention is to at least partially solve the above problems. The technical problem to be solved by the present invention is, inter alia, to provide a method and a device for determining the rotor position in a multi-motor system, by means of which method or device it is possible to detect all rotors in a multi-motor system cost-effectively and reliably Location.

The above technical problems are solved by the claims. Other technical characteristics and details of the present invention are given by the description and drawings. The technical features described here in conjunction with the method obviously also apply in the case of the system according to the invention and the controller for carrying out the method, and vice versa, so that the individual inventive aspects can always refer to each other in terms of disclosure.

According to a first aspect of the invention, a method is provided for detecting the position of a rotor in a system having a plurality of electric machines which transmit their torques to a common transmission. The method according to the invention has the following steps in particular:

- detecting the rotor position of at least one rotor of the first electrical machine by means of a position sensor,

- estimating at least one parameter of at least one other electric machine by means of a parameter estimating device.

According to the invention, the rotor position of the rotor of the at least one further electric machine can be determined from the rotor position of the at least one rotor of the first electric machine and at least one measured parameter of the at least one other electric machine.

The position of the rotor relative to the stator of the respective electric machine is preferably detected. The first and/or the at least one further electric machine are each preferably designed as a three-phase synchronous machine, for example as a corresponding electric machine. However, the present invention is not limited thereto. It is then also conceivable that the first and/or at least one other electric machine is designed as a machine with any number of phases. The implementation of the method according to the invention is preferably, but not restricted to, detecting the rotor position in systems with rotationally synchronous or substantially rotationally synchronous electric machines.

A system with a plurality of electric motors which transmit their torque to a common transmission is understood to be a multi-motor system, in which the target of a torque addition is formed during the transmission of the torques so that on the common transmission form a relatively high torque. The plurality of electric machines and in particular the respective individual rotors of the electric machines are preferably mechanically coupled here.

During the detection of at least one parameter of the at least one further electric machine, the rotor position of the rotor of the at least one other electric machine is preferably not directly detected, ie the use of corresponding position sensors or position sensors can be dispensed with here. Within the scope of the present invention, at least one parameter is preferably understood to mean at least one operating parameter of at least one further electric machine. A position sensor according to the invention is understood in particular to be a sensor, such as a SIN/COS sensor or a resolver for the permanent detection of the rotor position.

Based on the rotor position of the at least one rotor of the first electric machine, the rotor position of the rotor of at least one other electric machine in the near future can be roughly deduced or estimated. The detection of the rotor position of the rotor of the at least one further electric machine can be continuously evaluated by introducing at least one parameter of the at least one other electric machine.

By means of the method according to the invention, it is possible to determine the rotor positions of all rotors in the system with a reduced number of position sensors. This makes it possible, for example, to determine a plurality of rotor positions of a respective plurality of rotors in an electric machine from only a single position sensor by which the rotor position of the rotor of the first electric machine is continuously detected. In other words, fewer position sensors than rotors are always required according to the invention. Costs for unnecessary position sensors can thus be saved. Furthermore, since fewer position sensors are required, the installation space required in the system can also be reduced. Despite the omission of position sensors, the invention also enables a high control quality over the entire speed range of the individual electric motors.

The parameter evaluation device preferably has one or more sensors by means of which, in particular, an operating parameter of at least one other electric machine can be determined. In this case, it is possible for the parameter evaluation device to be coupled, for example, to a commutator, via which operating parameters, such as phase currents, pulse mode and/or traction supply voltage, can be obtained.

The method according to the invention can be used, for example, in motor vehicles, in which, for example, the addition of the torques along the travel path takes place via two electric drive shafts (Achsen or Welle). The rotor position of the first electric machine of one shaft can be determined directly by means of a position sensor, wherein the rotor position of the second electric machine of the other shaft can be determined by the method according to the invention.

According to a further development of the invention, it is possible for the rotor position to be detected by respective individual position sensors of a plurality of rotors of a plurality of corresponding electrical machines. By providing a plurality of position sensors on a plurality of rotors, that is to say one position sensor on each respective rotor, the position of the rotor of at least one other electrical machine can be determined more precisely with reduced computational effort for the system. rotor position. In this case, the rotor position of the rotor of at least one other electric machine can be determined from the rotor position of the respective electric machine measured by means of a corresponding position sensor. A more precise and faster determination of the rotor position of the rotor of at least one further electric machine can be achieved by the direct detection of a plurality of rotor positions by means of corresponding position sensors.

Furthermore, it is also possible according to the invention to determine at least one parameter of a plurality of electric machines. That is to say, at least one parameter can be measured and calculated respectively in one of the plurality of electric machines. Through a possible combination of separately measured parameters of a plurality of electrical machines, a rotor position of a rotor of at least another electrical machine or a plurality of rotor positions of rotors of at least another electrical machine can be determined more precisely.

Furthermore, it may be advantageous to detect as at least one parameter a control mode for a power electronics component of at least one other electric machine. In this case, a control mode is to be understood in particular as a method and a measure for controlling power electronics components of at least one other electric machine, which control mode is defined, for example, by a defined current and/or voltage profile or a defined switching process.

It is particularly advantageous within the scope of the invention to detect as at least one parameter a phase current and a phase voltage of at least one further electric machine. For this purpose, the parameter evaluation device can have current sensors for detecting the individual phase currents. The phase voltages can either be measured directly or derived from pulse-width-modulated control signals for at least one other electric machine. Through one or more phase currents or one or more phase voltages of the respective further electric machine, the rotor position can be calculated directly or indirectly via the inductance of at least one other electric machine, and the corresponding rotor position can be derived therefrom. From this calculated rotor position of the at least one further electric machine and the measured rotor position of the first electric machine, a calibration angle can be determined by means of which at least The rotor position of the other motor.

Furthermore, it is also possible according to the invention to detect as at least one parameter the rotor speed of at least one further electric machine. As a result, the slip of the at least one further electric machine relative to the first electric machine can be detected, and the rotor position of the at least one other electric machine can be determined therefrom. From the slip angle, a calibration angle can be determined, by means of which the rotor position of at least one other electric machine can be continuously and precisely determined. To determine the rotor position, the parameter determination device can have, for example, a rotational speed sensor.

Furthermore, according to the invention, it can also be achieved that at least one parameter can be measured by an incremental encoder, such as a speed incremental encoder or a Hall sensor, which is connected to at least one other motor Signals are generated at one or more fixed rotation angles. As a result, the calibration angle of the at least one further electric machine can be precisely determined at continuously recurring times, and thus the rotor position of the at least one other electric machine can be continuously and precisely determined.

Furthermore, in a refinement it is also possible to detect as at least one parameter the alignment angle of the rotor of at least one further electric machine. A calibration angle is here understood to be an angle that describes the difference in the rotor position angles of the first electric machine and at least one other electric machine. The calibration angle is influenced by the slip and backlash of the first electric machine and at least one other electric machine. The rotor position of the rotor of the at least one further electric machine can eg be determined from the rotor position of the rotor of the first electric machine and a calibrated angle estimate of the rotor of the at least one other electric machine, wherein the at least one other electric machine is continuously tracked after the calibrated angle determination. A particularly precise determination of the rotor position of the rotor of the at least one further electric machine can be achieved by determining the alignment angle of the rotor of the at least one further electric machine.

With regard to the parameters enumerated above, such as the control mode for the power electronics, the phase currents, the rotor rotational speed and the calibration angle, it should be mentioned that said parameters can be applied individually or in combination with each other to the Calculation of the rotor position of the rotor. Furthermore, it is possible according to the invention to carry out the following steps for determining the rotor position of the rotor of the at least one further electric machine:

- store the calibration angle when the system is turned off, and

- Use of the calibration angle when the system is switched on in order to determine the rotor position of the rotor of at least one other electric machine.

This makes it possible to initialize the calibration angle for determining the rotor position particularly quickly and easily during switch-on. To this end, the at least one further electric motor can first be driven or energized so that it rotates to a known calibration angle in order to take full advantage of the torque transmission slip.

Subsequently, a known calibration angle can be used as an initial value. When the system or at least one other electric machine is switched off, a known calibrated angle of the rotor of the at least one other electric machine is stored and used as an initial value when the system or at least one other electric machine is switched on again. By initializing the calibration angle of the rotor of at least one further electrical machine, a fast and accurate provision of the calibration angle can be ensured.

If the calibration angle of at least one other motor cannot be determined in the preparatory phase when at least one other motor is switched on, this motor can be operated with sensorless control during the first revolution until the rotor position is determined and thus determined relative to the calibration angle of the position sensor of the first motor.

According to another aspect of the invention there is provided a system with a plurality of electric motors transmitting their torque to a common transmission, wherein the system has a controller designed to implement the method described above . The system according to the invention thus brings about the same advantages as described in particular in connection with the device according to the invention. For this purpose, the system has a position sensor for detecting a rotor position of at least one rotor of a first electric machine and a parameter evaluation device for ascertaining at least one parameter of at least one other electric machine.

Furthermore, within the scope of the present invention is a controller which is designed to carry out the method described above and/or to control and/or regulate the system described above. The controller preferably has a rotor position determination device for determining the rotor position of the rotor of the at least one further electric machine as a function of the rotor position of the rotor of the first electric machine and at least one measured variable of the at least one other electric machine. The controller according to the invention thus brings about the same advantages as described in particular in connection with the method according to the invention.

Further measures for improving the invention are given by the following description of various exemplary embodiments of the invention, which are shown schematically in the drawings. All technical features and/or advantages given by the claims, the description or the drawings (including structural details and spatial arrangements) can be essential to the invention either by themselves or in different combinations.

Respectively schematically show:

Figure 1 is a block diagram illustrating a system according to one embodiment of the present invention, and

Fig. 2 is a flowchart for illustrating a method according to an embodiment of the present invention.

FIG. 1 is a system 10 with a plurality of electric machines 20 , 30 , 40 , specifically a first electric machine 20 , a second electric machine (another electric machine) 30 and a third electric machine (another electric machine) 40 . However, the present invention is not limited thereto. In fact, systems with any number of motors can also be considered. The first electric machine 20 has a first rotor 22 and a first stator 21 , wherein the first rotor 22 is arranged movable or rotatable relative to the first stator 21 . The second electric machine 30 has a second rotor 32 and a second stator 31 , wherein the second rotor 32 is arranged movable or rotatable relative to the second stator 31 . The third electric machine 40 has a third rotor 42 and a third stator 41 , wherein the third rotor 42 is arranged movable or rotatable relative to the third stator 41 . According to the embodiment shown in FIG. 1 , electric machines 20 , 30 , 40 are designed as three-phase synchronous electric machines.

The electric machines 20 , 30 , 40 shown in FIG. 1 transmit their torques to a common transmission 50 by means of torque summing. Correspondingly higher torques can thus be achieved via the transmission 50 . Furthermore, the system 10 has a position sensor 23 for detecting the rotor position of the first rotor 20 of the first electric machine 20 . In addition, the system 10 shown in FIG. 1 also has two parameter measuring devices 60, wherein one parameter measuring device 60 is configured to measure at least one parameter of the second electric machine, and the other parameter measuring device 60 is configured to measure a third At least one parameter of the motor. For example, the control modes of the power electronics components for the respective electric machines 30 , 40 , the phase currents and phase voltages of the respective electric machines 30 , 40 , the rotor speeds of the respective electric machines 30 , 40 and/or the respective electric machines can be determined by means of corresponding parameter evaluation devices 60 . 30 , 40 the calibration angle of the rotor 32 , 42 .

Furthermore, the system shown in FIG. 1 has a controller 70 which is designed for the control of the system. More precisely, a controller 70 is provided to process the signals from the parameter measuring device 60 and the position sensor 23 and to estimate the rotor position of the second rotor 32 of the second electric machine and the rotor position of the third rotor 42 of the third electric machine accordingly . More precisely, the controller 70 is configured and arranged so that at least one parameter and the first The measured at least one parameter of the three motors 40 can measure and calculate the accurate rotor positions of the second rotor 32 and the third rotor 42 .

A method for determining the rotor position in the above-described system with a plurality of electric machines 20 , 30 , 40 according to an embodiment of the invention is described below with reference to FIG. 2 . More precisely, a method is described with reference to FIG. 2 , by means of which the rotor positions of the second electric machine 30 and the third electric machine 40 are determined without position sensors being provided for this purpose.

In step S1 , the rotor position of first rotor 22 of first electric machine 20 is detected for this purpose by means of position sensor 23 . In step S10 and subsequent steps that can be implemented in parallel with step S1 or after step S1 , parameters of the second electric machine 30 are detected by the parameter measuring device 60 . To this end, in step S10 , firstly second rotor 32 is driven with phase currents and optionally corresponding pulse width modulation. Due to the slip and play, the rotors 23 , 32 and 42 can thus be rotated significantly differently. In the following step S11, by identifying the known rotor position based on the results of the parameter measuring device 60, for example by means of a Hall sensor or an incremental speed encoder, a calibration angle is calculated, which corresponds specifically to The angular difference between the known rotor position of rotor 32 and the rotor position of rotor 22 determined by sensor 23 . In the subsequent step S12, the calibration angle can also be filtered by a low-pass filter. In the subsequent step S13 , the rotor position of the second rotor 32 of the second motor 30 can be calculated according to the rotor position of the first rotor 22 and the calculated calibration angle.

In addition to this embodiment, alternative embodiments are also conceivable. In step S10 , then firstly second rotor 32 is driven with phase currents and optionally corresponding pulse width modulation. As described above, the rotors 23, 32 and 42 can be rotated significantly differently by the slip and the clearance. In a subsequent step S11 , the inductance ratio Ld/Lq is determined for the second rotor 32 based on the phase currents obtained by the parameter determination device 60 and the pulse width modulation is determined. In a subsequent step S12, the rotor position of the second rotor 32 is determined from the phase currents and the phase voltages, optionally based on the phase current-dependent ratio Ld/Lq, and then a calibration angle is determined which corresponds to the The angular difference between the calculated rotor position and the rotor position of the rotor 22 determined by the sensor 23 is obtained. The calibration angles can then also optionally be filtered by a low-pass filter. In the subsequent step S13 , the rotor position of the second rotor 32 of the second motor 30 can be calculated according to the rotor position of the first rotor 22 and the calculated calibration angle.

The steps S20 to S23 for measuring the rotor position of the third rotor 42 of the third motor 40 are basically equivalent to the steps S10 to S13 for measuring the rotor position of the second rotor 32 of the second motor 30, so the same steps are omitted. specific description.

list of reference signs

10 systems

20 First motor

21 first stator

22 First rotor

23 position sensor

30 Second motor

31 Second stator

32 Second rotor

40 Third motor

41 Third stator

42 Third rotor

50 drive shaft

60 parameter measurement equipment

70 controller

Claims (10)

1. A method for measuring the position of a rotor in a system (10) having a plurality of electric motors (20, 30, 40) which transmit their torque to a common transmission (50), said The method includes the steps of: - detecting the rotor position of at least one rotor (22) of the first electric machine (20) by means of a position sensor (23), - measuring at least one parameter of at least one other electric machine (30, 40) by means of a parameter measuring device (60), It is characterized in that, The rotor (32, 40) of the at least one other electric machine (30, 40) can be determined from the rotor position of the at least one rotor (22) of the first electric machine (20) and at least one measured parameter of the at least one other electric machine (30, 40). 42) of the rotor position. 2. The method of claim 1, wherein, The rotor position is detected by each position sensor (23) of a plurality of rotors (22, 32) of a corresponding plurality of motors (20, 30). 3. The method according to any one of the preceding claims, characterized in that, At least one parameter of a plurality of motors (30, 40) is measured and calculated respectively. 4. The method according to any one of the preceding claims, characterized in that, A control mode for a power electronics component of at least one further electric machine (30, 40) is determined as at least one parameter. 5. The method according to any one of the preceding claims, characterized in that, As at least one parameter, phase currents and phase voltages of at least one further electric machine (30, 40) are determined. 6. The method according to any one of the preceding claims, characterized in that, The rotor speed of at least one further electric machine (30, 40) is determined as at least one parameter. 7. The method according to any one of the preceding claims, characterized in that, A calibration angle of a rotor (32, 42) of at least another electric machine (30, 40) is determined as at least one parameter. 8. The method of claim 7, wherein, In order to determine the rotor position of the rotor (32, 42) of at least one further electric machine (30, 40), the following steps are also carried out: - storing the calibration angle when the system (10) is switched off, and - Using the calibration angle when the system (10) is switched on, in order to determine the rotor position of the rotor (32, 42) of at least one other electric machine (30, 40). 9. A system (10) with a plurality of motors (20, 30, 40) which transmit their torque to a common drive (50), wherein the system has a controller (70) , the controller is designed to implement the method according to any one of claims 1-8. 10. A controller (70) for implementing the method according to any one of claims 1 to 8 and/or for controlling and/or regulating the system (10) according to claim 9 ).