阅读说明：本技术 利用间接测量对定子绕组的热监控 (Thermal monitoring of stator windings using indirect measurements ) 是由 L·鲁格 G·邦 于 2021-04-30 设计创作，主要内容包括：本发明涉及一种用于借助温度传感器(11)确定和/或监控电动马达(10)的绕组(6)的温度(T-(W))的方法,其中由温度传感器(11)测量的温度(T-(S))被传递至计算机单元(12),并且其中计算机单元(12)从由温度传感器(11)测量的温度(T-(S))计算出绕组温度(T-(W)),其中温度传感器(10)测量马达信号发生器(8)中的温度。(The invention relates to a method for determining and/or monitoring the temperature (T) of a winding (6) of an electric motor (10) by means of a temperature sensor (11) W ) In which the temperature (T) measured by the temperature sensor (11) S ) Is transmitted to the computer unit (12), and wherein the computer unit (12) derives the temperature (T) measured by the temperature sensor (11) S ) Calculating the winding temperature (T) W ) Wherein the temperature sensor (10) measures the temperature in the motor signal generator (8).)

1. For determining and/or monitoring the temperature (T) of the windings (5, 6, 7) of an electric motor (10) by means of a temperature sensor (11)_W) Wherein the temperature (T) measured by the temperature sensor (11)_S) Is transmitted to a computer unit (12)And wherein the computer unit (12) derives the temperature (T) measured by the temperature sensor (11)_S) Calculating the winding temperature (T)_W），

Characterized in that the temperature sensor (11) measures the temperature in the motor signal generator (8).

2. Method according to claim 1, characterized in that the temperature (T) of the stator winding of the synchronous machine is determined and/or monitored_W）。

3. Method according to at least any one of the preceding claims, characterized in that the computer unit (12) determines the temperature of the windings (5, 6, 7) of the electric motor (10) by means of a thermal simulation model of the electric motor.

4. Method according to at least any one of the preceding claims, characterized in that the temperature (T) is measured in addition to the temperature (T) measured by the temperature sensor (11)_S) In addition, the current rotational speed and phase currents are also transmitted to the thermal simulation model.

5. Method according to at least any one of the preceding claims, characterized in that the winding resistance is included in the calculation depending on the current winding temperature.

6. Method according to at least any of the preceding claims, characterized in that the calculation of the temperature (T) of the windings (5, 6, 7) of the electric motor (10) by means of the nodal potential method is performed by means of a thermal network_W）。

7. Method according to any one of claims 1 to 5, characterized in that the temperature (T) of the windings (5, 6, 7) of the electric motor (10) is calculated by means of an empirically known characteristic curve_W) Wherein the characteristic curve is the winding temperature (T)_W) And the temperature (T) measured by the temperature sensor (11)_S) And (4) associating.

8. The method of claim 7, wherein the calculation is performed by means of a regression model that has been trained by machine learning.

9. Electric motor (10), in particular a synchronous machine, having a stator (9) and a rotor (3), wherein the stator (9) and/or the rotor (3) have a multi-strand winding, preferably a three-strand winding, wherein the electric motor (10) furthermore has a motor signal generator (8) and at least one temperature sensor (11), wherein the electric motor is assigned a temperature (T) for calculating the temperature (T) of the windings (5, 6, 7) of the electric motor (10)_W) A computer unit (12) of (a),

characterized in that the temperature sensor (11) is arranged on the motor signal generator (8).

10. Electric motor (10) according to the preceding claim, characterized in that said temperature sensor (11) has a temperature-dependent resistance, in particular an NTC resistance.

Technical Field

The invention relates to a method for determining and/or monitoring the temperature of the windings of an electric motor and an electric motor according to the preamble of claims 1 and 9.

Background

During operation of the electric motor, it is necessary to monitor whether critical components of the motor are kept within an admissible temperature range for motor protection. This is important, for example, in particular for the insulation of the winding, since the service life of the insulation is significantly reduced with increasing temperature. For thermal monitoring of electric motors, it is common in the prior art to monitor the temperature of the motor windings. The winding temperature is usually monitored thermally by means of a temperature sensor arranged in the winding. However, such an arrangement of sensors is expensive based on the required mounting and wiring in the windings.

Disclosure of Invention

The object of the present invention is therefore to provide a method and a device for determining and/or monitoring the temperature of a winding of an electric motor, wherein the arrangement of a temperature sensor in the winding can be dispensed with.

In the method according to the invention for determining and/or monitoring the temperature of the windings of an electric motor by means of a temperature sensor, the temperature measured by the temperature sensor is transmitted to a computer unit, and the computer unit calculates the winding temperature from the temperature measured by the temperature sensor.

According to the invention, the temperature sensor measures the temperature in the motor signal generator (Motorgeber). It is therefore proposed to measure the temperature of the winding indirectly. Therefore, no measurement is carried out directly on the winding itself, and therefore a corresponding sensor device in the winding can be dispensed with. Alternatively, the temperature in the motor signal generator is determined. The winding temperature is calculated by means of a motor signal generator temperature measured by a temperature sensor. It is therefore proposed to determine and monitor the winding temperature in a manner supported by measurement technology using indirect measurements.

In an advantageous method, in particular the temperature of the stator winding of the synchronous machine is determined and/or monitored. The stator winding can also be a stator winding of a synchronous servomotor in particular. In particular in permanent-magnet synchronous machines, the heat source and the loss source are mostly located in the stator for operating points at low rotational speeds. For this reason, thermal determination and/or monitoring of the stator windings is particularly advantageous.

As the rotational speed increases, significant power losses (approximately 30-40% of the total power loss) also occur in the rotor due to eddy current losses and magnetic reversal losses. Since rotor losses also influence the temperature in the stator, rotor losses are also important for the calculation of the winding temperature and are therefore taken into account in an advantageous manner in order to avoid insulation damage to the windings in the event of excessive temperatures.

However, it is also conceivable in this method to advantageously determine and/or monitor the winding temperature of the asynchronous machine.

It is also possible to determine and/or monitor the temperature of the rotor winding. In this case, it is conceivable to determine and/or monitor either the temperature of the stator winding or the temperature of the rotor winding. However, it is also conceivable to determine and/or monitor the temperature of the stator winding and the temperature of the rotor winding.

In a further advantageous method, the computer unit determines the temperature of the windings of the electric motor by means of a thermal simulation model of the electric motor. Advantageously, at least the main structural elements of the electric motor, in particular at least the rotor and the stator, are taken into account within the scope of the thermal simulation in order to be able to calculate the winding temperature as precisely as possible. It is particularly preferred to also take structural elements such as bearings and housings into account in the thermal simulation, since this allows a more accurate calculation of the winding temperature.

Advantageously, the thermal simulation may be performed by a thermal network model. This present aspect is therefore advantageous because the thermal network model can be established quickly, in particular if the electrical machines to be simulated differ only slightly in their usual structure. This applies, for example, in particular to permanent-magnet-excited synchronous machines, so that the thermal network model is particularly advantageous here. On the other hand, thermal networks are characterized by relatively little computation time. Advantageously, a suitable thermal network may be derived and/or simplified from theoretical considerations and/or empirical knowledge.

In a further preferred method, in addition to the temperature measured by the temperature sensor, the current rotational speed and phase current are also transmitted to the thermal simulation model. Advantageously, the winding resistance is also included in the calculation as a function of the current winding temperature, since the copper losses depend on the winding resistance.

Preferably, the thermal simulation model calculates the current winding temperature from a plurality of input variables. The input variables can be, in particular, phase currents, rotational speed, winding resistance, temperature measured by a temperature sensor (signal generator temperature), thermal time constants and/or elapsed time. Advantageously, the input variables can be stored, in particular temporarily (zwischenspeicheric), in a memory unit.

In this case, it is possible to store all input variables used by the thermal simulation model. However, it is also possible to store only some of the input variables. The individual input variables can be stored, for example, in a memory unit and read out there for the thermal simulation model, while the other input variables are conducted directly further to the thermal simulation model. It is thus possible, for example, for the currently respectively measured signal generator temperature to be conducted directly further from the temperature sensor to the thermal simulation model, while the other input variables are read out of the memory unit.

The storage unit may be a storage unit integrated in the electric motor. The storage unit can be, for example, an electronic component integrated in the electric motor. However, it is also possible to provide an external memory unit.

In an advantageous method, the temperature of the windings of the electric motor is calculated by means of a nodal potential method (knottenthalpiverfahren) via the thermal network. This calculation method is therefore particularly advantageous because it has a very high accuracy. This calculation method is therefore preferably used when a temperature determination as precise as possible is important. In contrast, however, this calculation method has the disadvantage of a relatively high calculation effort required for this.

In an alternative calculation method for this purpose, the temperature of the windings of the electric motor is calculated using an empirically determined characteristic curve. Advantageously, the empirically known characteristic curve correlates the winding temperature and the temperature measured by the temperature sensor. Preferably, the empirically known characteristic curve relates the winding temperature to a plurality of input variables. Particularly preferably, the empirically determined characteristic curve shows a dependency of the winding temperature on all input variables which should be taken into account in the context of the thermal simulation model.

The advantage of the calculation method is the low calculation effort. However, the disadvantage is the lower accuracy of this calculation compared to the calculation by means of the node potential method.

Advantageously, the calculation can be performed by means of a regression model that has been trained by machine learning. The artificial intelligence is preferably learned by means of monitored learning.

Preferably, the thermal simulation furthermore makes it possible to simulate further temperatures in addition to the winding temperature. Advantageously, in addition to the temperature of the stator winding, it is also possible, for example, to simulate the bearing, rotor and ambient temperature. The simulation of the temperature may preferably be an intermediate step for determining the winding temperature. However, it is also preferably possible to infer the cause of the failure and/or wear from simulations of the respective temperatures.

The invention further relates to an electric motor having a stator and a rotor, wherein the stator and/or the rotor have a multi-strand winding. The electric motor furthermore has a motor signal generator and at least one temperature sensor. Furthermore, a computer unit for calculating the temperature of the windings of the electric motor is assigned to the electric motor.

According to the invention, the temperature sensor is arranged on the motor signal generator.

The electric motor described here is particularly designed and provided for carrying out the method described above, i.e. all features carried out for the method described above are likewise disclosed for the electric motor described here and vice versa.

Preferably, the electric motor may be a synchronous motor, in particular a synchronous servomotor. Particularly preferably a permanent magnet excited synchronous machine. However, it is also conceivable for the electric motor to be an asynchronous machine.

Advantageously, the stator of the electric motor has a multi-strand winding. Particularly preferably, the stator has a three-strand winding. Advantageously, the windings are symmetrical. Preferably, the windings are arranged offset in space by 120 ° in each case.

Preferably, the rotor carries permanent magnets. However, it is also conceivable for the rotor to carry a field winding which is supplied with direct current.

In a preferred embodiment, the temperature sensor has a temperature-dependent resistance. Particularly preferably, the temperature sensor has a temperature-dependent resistance with a negative temperature coefficient, which therefore conducts current better at high temperatures than at low temperatures. Particularly preferably, the temperature-dependent resistance is an NTC resistance.

In the motor signal generator, different embodiments are preferably considered. The motor signal generator can therefore advantageously use capacitive and/or optical scanning methods and/or magnetic methods. The output of the motor signal generator can preferably be realized analog and/or digitally. Particularly preferably, the parameter data are output at least digitally.

In an advantageous embodiment, the electric motor has a motor cooling device. It is conceivable here for the motor to be cooled only by means of a self-cooling device, i.e. for the dissipation of the lost heat to be achieved by natural convection and/or radiation into the ambient air and/or by conduction of the heat to the machine structure. In an advantageous embodiment, however, motor cooling and/or water cooling by external ventilation can also be provided for this purpose.

Drawings

Further advantages and embodiments are obtained from the figures. Wherein:

fig. 1 shows a schematic view of an electric motor according to the invention;

fig. 2 shows an example of a thermal network for an electric motor.

Detailed Description

Fig. 1 shows a schematic view of an electric motor 10 according to the invention. The embodiment selected for this purpose shows an inner pole machine known per se. Fig. 1 shows the external stator 9 and the internal rotor 3. The stator 9 has three winding wires 5, 6, 7, which are each arranged spatially offset by 120 °.

Furthermore, a motor signal generator 8 is schematically shown in fig. 1. The temperature sensor 11 is arranged on the motor signal generator 8. The temperature sensor 11 determines the temperature TS at the motor signal generator. The computer unit 12 is also only schematically shown. By means of the computer unit 12, the temperature T measured by the temperature sensor 11 can be determined_SIt is calculated what temperature T the winding wires 5, 6, 7 have_W. The drive regulator 13 is also shown schematically.

Fig. 2 shows an example of a thermal network for the electric motor 10. The nodes in this case each describe a section of the electric motor 10, the temperature of which should be simulated. The corresponding potential at the node resulting from the calculation corresponds to the temperature of the modeled component.

In fig. 2, the nodes are shown, which represent the environment 0, the housing 1, the bearing 2, the rotor 3, the lamination stack 4, the three winding wires 5, 6, 7 of the stator 9 and the motor signal generator 8.

T0 represents the value of the temperature of ambient 0 and thus defines the reference temperature of the system.

The power loss of the respective component, which is output essentially as heat flow, is symbolized by the symbol P. The numbers added to the symbols symbolize which component the corresponding power loss represents. Thus, P1 represents the power loss introduced into the system from the housing 1, P2 represents the power loss of the bearing 2, P3 represents the power loss of the rotor 3, P4 represents the power loss of the lamination stack 4, P5, P6 and P7 represent the power loss of the respective winding wires 5, 6, 7, and P8 represents the power loss of the motor signal generator 8.

The heat capacity is symbolized by the symbol C and describes the temperature change of the body according to the respectively delivered thermal energy (C = dQ/dT). The heat capacity therefore reflects the thermal inertia of the motor and in particular of the windings. In this heat capacity, the corresponding number to be added also indicates to which body the heat capacity is related. Therefore, C1 represents the heat capacity of the case 1, and C5 represents the heat capacity of the winding wire 5, and the like.

Advantageously, the respective heat capacities of the three winding wires are substantially equally large.

The symbol R represents the thermal resistance and thus describes the quality of the heat conduction between the two transition surfaces. The corresponding thermal resistances are each provided with two numbers in fig. 2 in order to illustrate which thermal transition the thermal resistance describes. Thus, the thermal resistance R01 between the node for environment 0 and the node for housing 1 describes, for example, the quality of the heat conduction between the housing and the environment (in most cases ambient air).

The thermal resistances R45, R46 and R47, i.e. the thermal resistance between the lamination stack 4 and one winding wire of each of the three winding wires 5, 6 or 7, are advantageously substantially equally large.

Since in practice overheating of the motor windings should be prevented, the thermal resistances R45, R46 and R47 are preferably as small as possible. The thermal resistance R14, i.e. the thermal resistance between the housing 1 and the lamination stack 4 and R01, is preferably also as small as possible.

Preferably, the thermal resistances R45, R46, R47, R14 and R01 are less than, for example, the thermal resistance R34, i.e. the thermal resistance between the rotor and the lamination stack. Advantageously, the values of the thermal resistances R45, R46, R47 and R14 are for example at most half the thermal resistance R34, preferably at most one quarter of the thermal resistance R34, and particularly preferably at most one eighth of the thermal resistance R34, respectively.

Advantageously, the thermal resistance R18, i.e. the thermal resistance between the housing 1 and the motor signal generator 8, is known for the calculation.

The temperature sensor 11 should track the temperature of the housing 1 as accurately as possible. Thus, an indirect measurement of the housing temperature is possible, from which the winding temperature T can be inferred_W. It is therefore advantageous for the temperature sensor 11 to be as free as possible from ambient temperature disturbances. Advantageously, the temperature sensor 11 is thus arranged such that it is not too greatly influenced by the ambient temperature of the electric motor 10.

The applicant reserves the requirement to claim all the features disclosed in the application documents as essential features for the invention, as long as they are novel individually or in combination with respect to the prior art. It is furthermore pointed out that features which may themselves be regarded as advantageous are also described in the respective figures. It is directly recognized by those skilled in the art that certain features depicted in the drawings may also be advantageous without the employment of additional features of the drawings. Furthermore, those skilled in the art will recognize that advantages may also result from a combination of features shown in separate or different figures.