DE202019101146U1 - Device for detecting the winding temperature - Google Patents

Abstract

Device (10) for determining the temperature TW of a winding of a stator and a rotor formed rotary field machine comprising at least a first Kalman filter (K1) for calculating the temperature and a rotating field control for vector control of the induction machine with at least one id-current controller formed is to impart to the winding voltage a high frequency voltage signal (HF) to obtain therefrom a winding current having a high frequency superimposed current component for the winding which is supplied to the Kalman filter (K1), the Kalman filter (K1) having a high frequency model of the motor in order to determine the high-frequency resistance of the winding therefrom and, in turn, the winding temperature TW therefrom by means of a computing function.

Description

The invention relates to a device detecting the winding temperature of a motor winding.

It is well known that during operation of an electric motor, such. B. a DC motor, the motor winding is heated substantially and therefore the heating of the winding must be paid particular attention at full load or under extreme conditions. For this purpose, various temperature measuring devices have become known.

One way to determine the winding temperature, for example, is to provide a temperature sensor in the winding and thus to measure the temperature of the winding directly. A disadvantage of this device, however, is that the temperature can only be measured at the point at which the sensor is located. This means that local temperature peaks in other areas of the winding, or the (overall) average temperature (temperature distribution) in the winding, can not be measured.

Another way to measure the winding temperature is to measure the ohmic resistance of the winding and from this measured resistance value and a comparison value, d. H. a resistance value of the winding when the engine is cold, to determine the temperature increase. In principle, the winding temperature could be determined by measuring the electrical resistance of the field winding. However, this leads to satisfactory results only in a stationary operation of a separately excited synchronous machine. In dynamic processes, however, such temperature measurements are so strongly distorted by armature reactions and currents in damper circuits that a temperature determination by means of resistance measurements is practically impossible.

Known methods for temperature detection are the installation of sensors in the winding, the determination of the winding temperature via state estimator (Kalman filter, gradient method) from the motor differential equations, the direct measurement of the winding resistance during operation by coupling a measuring voltage or the calculation of the motor temperature using thermal network models of the engine.

From the DE 10 2008 040 725 A1 For example, a method for determining a rotor temperature of a permanent-magnet synchronous machine is known in which an estimate for the rotor temperature is determined by means of a Kalman filter containing a thermal model of the synchronous machine.

From the EP 2977733 A1 Another method for determining a winding temperature of a field winding of a separately excited synchronous machine by means of a Kalman filter is known. In this case, a first temperature estimated value of the winding temperature is predetermined for an initial time; at different measurement times following the starting time, an electrical exciter voltage (uf (k)) applied to the exciter winding and an electrical exciter current (if (k)) flowing through the excitation winding are detected, and for every measuring time, an updated temperature estimated value (x (k)) is recursively determined as a function of the excitation voltage (uf (k)) detected at the measuring instant, the exciting current (if (k)) detected at the time of measurement and a previous temperature estimated value (x (x). k-1)).

The solutions known from the prior art use the fundamental vibration model in the Kalman filter and calculate the winding resistance from the manipulated variables terminal voltage and the measured variable of the winding currents. Since, however, quite inaccurate results still occur here and this method based on the basic vibration model is difficult, especially for larger engine designs, there is a need for an alternative temperature determination of the winding of a rotating field machine.

The invention is therefore based on the object to overcome the aforementioned disadvantages and to provide an optimized and improved device for determining a winding temperature of a winding of a rotating field machine.

The object is achieved by the features of claim 1.

A basic idea of the present invention relates to a device which is designed to utilize the utilization of the skin effect for determining the winding temperature at high-frequency currents.

The skin effect is the property of conductors in the presence of an alternating current, in which only the near-surface areas of a conductor for the transport of the charge carriers are available. When alternating current corresponding eddy currents and electric fields are generated in response to the specific frequency, which displace the charge carriers in the surface of the Leisters. The electric fields serve as carriers of energy. At the same time, however, the conductor cross-section which can be used for the charge carriers is reduced, whereby the effective resistance of the conductor increases the effective resistance. Since the resistance itself is a temperature dependent quantity, there is one immediate relationship between the high frequency resistance of the line and the temperature.

According to the invention, a device for determining the temperature T _{W of} a winding of a rotating field machine formed with a stator and a rotor comprises at least one first Kalman filter for determining the temperature. For this purpose, a rotating field control is first provided for vector control of the induction machine with at least one id-current controller, which is designed to provide a strand voltage for the winding and impose a high-frequency voltage signal of the strand voltage in order to obtain a winding current with a high-frequency superimposed current component for the winding ,

This current with the high-frequency component is supplied to the Kalman filter, wherein the Kalman filter provided for this purpose has a model, in particular a high-frequency model of the motor, in order to estimate and determine the high-frequency resistance of the winding from this in turn by means of a computing function.

The classic Kalman filter is in many cases not applicable because it is limited to linear state space models. The prevailing effects are nonlinear. Thus, a non-linear Kalman filter is used with particular advantage. For this purpose, non-linear extensions of the Kalman filter such as the extended Kalman filter (abbreviation EKF) or the unscented Kalman filter (abbreviation UKF) can be used. These Kalman filter variants approximate the nonlinear problem by a linear one using either analytical (EKF) or statistical (UKF) techniques. In terms of straightforward usage, these extensions are often referred to as the Kalman filter, as they also have a recursive and a predictor-corrector structure. In contrast to the simple Kalman filter, a free variable must be used for Kalman matrix and must be estimated during the entire filter operation.

According to the invention, it is further provided with advantage that the high-frequency Kalman filter is designed to evaluate the specific spectral components in the current signal. Correspondingly adapted algorithms for the realization of the corresponding simulation models can be used for this purpose.

The evaluation accuracy can be further improved if the winding wire of the winding has a thin iron coating or a coating with a high iron content.

In a preferred embodiment of the invention, it is further provided that a second Kalman filter is provided, which is designed with a basic engine model in order to estimate or determine the position of a rotor of the induction machine. In a preferred embodiment, it is provided that the second Kalman filter is designed to estimate or determine the rotational speed of the rotor of the induction machine.

In a likewise advantageous embodiment, it is provided that the high-frequency model is modeled in the first Kalman filter in the rotor-fixed coordinate system.

Another aspect of the present invention relates to a rotating field machine formed with a device as described above for determining the winding temperature.

1. a) Erzeugen einer Strangspannung mit einem hochfrequent überlagerten Spannungsanteil an wenigstens einer Wicklung der Drehfeldmaschine;
2. b) Zuführen der Strangspannung an wenigstens den Eingang des ersten Kalman-Filters (K1) und Ermitteln der Differenz zwischen dem Ist-Strangstrom und dem Soll-Strangstrom in der Wicklung basierend auf dem im Kalman-Filter (K1) hinterlegten Modell;
3. c) Schätzen bzw. Ermitteln des Hochfrequenzwiderstandes und
4. d) Ermitteln der Wicklungstemperatur aus dem Hochfrequenzwiderstand.

Yet another aspect of the present invention relates to the operation of the device for determining the winding temperature of a winding of a rotating field machine with the following steps:

1. a) generating a strand voltage with a high-frequency superimposed voltage component on at least one winding of the induction machine;
2. b) supplying the strand voltage to at least the input of the first Kalman filter ( K1 ) and determining the difference between the actual phase current and the nominal phase current in the winding based on that in the Kalman filter ( K1 ) deposited model;
3. c) estimating or determining the high-frequency resistance and
4. d) determining the winding temperature from the high frequency resistor.

It is particularly advantageous if the second Kalman filter estimates the rotor position of the rotor and the rotational speed of the rotary field machine from the difference between the actual phase current and the nominal phase current in the winding based on the model stored in the second Kalman filter or determined.

Furthermore, it is advantageously provided that the determination of the winding temperature in the aforementioned step d) takes place with the aid of the change of the resistance on the basis of the temperature coefficient of the winding wire of the winding.

Other advantageous developments of the invention are characterized in the subclaims or will be described in more detail below together with the description of the preferred embodiment of the invention with reference to FIG.

• 1 eine beispielhafte Vorrichtung zur Ermittlung der Wicklungstemperatur.

It shows:

• 1 an exemplary device for determining the winding temperature.

In the following, the invention will be described with reference to FIGS 1 explained in more detail, wherein the figure is a control device 1 comprising two Kalmann filters K1 . K2 shows in full the device according to the invention 10 ,

The control device 1 provides a vector control of a rotating field machine and for this purpose comprises a current regulator 11 with the iq current regulator and an id current regulator. A manipulated variable is the setpoint speed n_setpoint, which is the speed controller 12 supplied as a controlled variable at the input.

At the output of the current controller 11 or the Iq current controller and the id_Stromregler the voltage magnitudes uq and ud are provided for the winding.

The required control procedure goes directly from the 1 and based on otherwise known measures and transformations, which are therefore not explained in detail. The d / q transformation is a basis for vector control of three-phase machines and describes one of several possible space vector representations, such as the equally known Park and Inverse Park transform. Also shown are the two park transformers Park and Park-1 for transforming the corresponding quantities between space vector representation and three-axis (abc) representation.

Furthermore, the first Kalman filter is used K1 as a resistance estimator in the HF model. For this, the Kalman filter K1 the sizes i_dq and u_dq supplied in the room pointer representation on the input side. Based on the stored RF model, the RF resistance is estimated and stored in a computing module 14 For temperature calculation, the winding temperature is determined from this and output as temperature TW.

The second Kalman filter K2 receives as input variables the voltage values obtained from the d / q quantities by means of the transformation u_abc and current values i_abc as input value of the values shown here by way of example for a PMS motor as induction machine. The Kalman filter K2 acts as an angle estimator for position determination on the basis of a basic vibration model of the PMS engine.

At the exit of the Kalman filter K2 the estimation angle and the speed ( omega_el * ). The latter is connected to the speed controller 12 returned as a manipulated variable. The position determination is fed to the parking transformer.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008040725 A1 [0006]
• EP 2977733 A1 [0007]

Claims (11)

Device (10) for determining the temperature TW of a winding of a stator and a rotor formed rotary field machine comprising at least a first Kalman filter (K1) for calculating the temperature and a rotating field control for vector control of the induction machine with at least one id-current controller formed is to impart to the winding voltage a high frequency voltage signal (HF) to obtain therefrom a winding current having a high frequency superimposed current component for the winding which is supplied to the Kalman filter (K1), the Kalman filter (K1) having a high frequency model of the motor in order to determine the high-frequency resistance of the winding therefrom and, in turn, the winding temperature TW therefrom by means of a computing function. Device (1) according to Claim 1 , characterized in that the first Kalman filter (K1) is a Kalman non-linear filter. Device (1) according to Claim 1 or 2 , characterized in that the first Kalman filter (K1) is designed to evaluate the specific spectral components in the current signal. Device (1) according to Claim 1 . 2 or 3 , characterized in that the winding wire of the winding comprises a thin iron coating or a high iron content coating. Device (1) according to one of the preceding claims, characterized in that a second Kalman filter (K2) is provided, which is formed with a motor model to estimate or determine the position of a rotor of the induction machine. Device (1) according to Claim 5 , characterized in that the second Kalman filter (K2) is designed to estimate or determine the rotational speed of the rotor of the induction machine. Device (1) according to one of the preceding claims, characterized in that the high-frequency model in the first Kalman filter (K1) is modeled in the rotor-fixed coordinate system. Induction machine formed with a device according to one of Claims 1 to 7 , According to Claim 8 configured to perform the steps of: e) means for generating a strand voltage having a high frequency superimposed voltage component on at least one winding of the induction machine; f) means for supplying the strand voltage to at least the input of the first Kalman filter (K1) and determining the difference between the actual phase current and the nominal phase current in the winding based on the model stored in the Kalman filter (K1); g) means for estimating the high frequency resistance and h) means for determining the winding temperature from the high frequency resistance. Rotary field machine after Claim 9 , characterized in that the second Kalman filter (K2) from the difference between the actual phase current and the nominal phase current in the winding based on the second Kalman filter (K2) stored model, the rotor position of the rotor and the speed of Rotary field machine estimates or determined. Rotary field machine after Claim 9 , characterized in that the determination of the winding temperature in step d) takes place with the aid of the change of the resistance on the basis of the temperature coefficient of the winding wire of the winding.

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