RU2715213C1 - Method for determination of rotor angular position of electric motors of synchronous machines class with excitation winding - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering and can be used for determination of rotor angular position of electric motors of synchronous machines class with excitation winding. Method for determining rotor angular position of electric motors of a class of synchronous machines with excitation winding is realized by performing steps on which high-frequency signal is injected into stator winding, obtaining a signal response from the excitation winding, comparing the phase of the injected signal and the response phase in the excitation winding, the difference of which determines the angular position of the electric motor rotor.

EFFECT: technical result is provision of high-accuracy determination of rotor position of electric motors of synchronous machines class with excitation winding at zero and low speeds.

1 cl, 4 dwg

Description

FIELD OF TECHNOLOGY

The claimed solution relates to the field of electrical engineering and is intended to determine the angular position of the rotor of the electric motors of the class of synchronous machines with an excitation winding.

BACKGROUND

Methods for determining the position of the rotor for synchronous motors based on the principles of extracting the emf of rotation of the electric motor or based on injection (addition / introduction) into the supply voltage or current of a high-frequency signal and calculating the magnetic anisotropy of the machine are widely known from the prior art. The anti-EMF method is used at medium and high speeds. The injection-based method works at low speeds, but the accuracy of the measurement substantially depends on the load and the operating mode of the electric motor. In addition, for synchronous machines with field windings, methods for determining the initial position by injection into the rotor winding are known [4].

Injection-based self-sensor methods are divided into many subclasses, such as current injection or voltage injection. The voltage injection, as the most commonly used, in turn is divided into the injection of a pulsating signal and the injection of a rotating signal. In most cases, the frequency of the injected signal lies in the range from 300 Hz to 1 kHz or uses the enumeration of the inverter states in the PWM process and measures the current response to each of the states [1].

In a valve-induction electric motor of independent excitation (VIDNV), like an explicitly polar synchronous machine with an excitation winding, the rotor has magnetic anisotropy. Therefore, the injection of a high-frequency signal into the stator winding will lead to a response in the form of stator currents and the amplitude of the response will depend on the angular position of the rotor. The angular position is estimated at one injection period; therefore, this method is implemented only for low speeds. At high speeds, the change in the angle during the injection period is significant, therefore, with increasing speed, the control system switches to the method of estimation by rotation EMF.

In [2] it is shown how, for an induction generator with a phase rotor, due to the injection of a signal into the rotor winding and due to the inductive coupling between the stator and the rotor, the angular position of the rotor can be obtained from the response in the stator current, however, this method is applicable only to asynchronous motors with phase rotor.

Various solutions are also known, described in patent information sources, which are aimed at determining the position of the rotor at medium or high speeds by injecting a signal into the stator winding. For example, such solutions are described in sources [3] - [5].

As the closest analogue, we can consider the source [4], which describes a known method for determining the position of the rotor by injection into the stator winding and receiving a response also from the stator winding, which makes it possible to determine the position of the rotor at medium or high speeds.

Thus, a significant drawback of the solutions known from the prior art is the lack of a method for reliable and accurate determination of the position of the rotor of an electric motor of a class of synchronous machines with an excitation winding at zero and low speeds.

SUMMARY OF THE INVENTION

The technical solution to be solved by the claimed solution is to eliminate the disadvantages inherent in existing analogues in the art.

The technical result is the provision of high-precision determination of the position of the rotor of the electric motors of the class of synchronous machines with an excitation winding at zero and low speeds.

The claimed method is implemented by performing the steps in which: high-frequency signal is injected into the stator winding; receive a signal response from the field winding;

compare the phase of the injected signal and the response phase in the field winding, the difference of which determines the angular position of the rotor of the electric motor. In a particular embodiment, the electric motor is a valve-inductor electric motor of independent excitation.

DESCRIPTION OF DRAWINGS

FIG. 1 illustrates an assessment of the position of an observer in response to stator current. FIG. 2 illustrates a response in a field current.

FIG. 3 illustrates a block diagram of an observer response in an excitation current.

FIG. 4 illustrates the determination of the angular position of the rotor during start-up with an observer from the response in the excitation current.

DETAILED DESCRIPTION OF THE INVENTION

The induction motor-induction motor of independent excitation has an additional channel for measuring the excitation winding, which can also be used to estimate the position. If high-frequency injection is introduced into the stator windings, then a change in the current of the longitudinal axis (directed in the direction of flow) leads to a change in the current of the field winding with constant flow along the longitudinal axis. Accordingly, injection into the stator winding is observed in the field winding. The phase difference between the injected signal and the observed in the field winding determines the angular position of the rotor. An example implementation of the proposed method is presented below:

The field current is controlled by a relay controller. If the current is less than the specified value, then the DC link voltage (DCB) is applied to the field winding, otherwise a short circuit occurs on the winding, which is equivalent to the application of zero voltage. The operation of the field current regulator simultaneously with high-frequency injection into the stator winding for two opposite angles is shown in FIG. 2. The responses in the field current have the same amplitude, but different phases.

The current in the field winding contains a component from the operation of the relay current regulator, which introduces a distortion in the response from injection into the stator windings. These distortions can be eliminated by the perturbation observer, who must predict the behavior of the current in the field winding in accordance with the control signals coming from the relay controller.

интегрируется, и вычисляется оценка тока обмотки возбуждения

Из-за большого изменения температуры, сопротивление обмотки возбуждения в процессе работы электропривода меняется значительно, и разница между оценкой и измеренным значением используется чтобы скорректировать оценку сопротивления с помощью наблюдателя, представленного интегральным звеном с малым коэффициентом усиления K_сопр. Когда параметры модели соответствуют параметрам объекта, разница между измеренным и оцененным током представляет собой чистый отклик от инжектированного сигнала i_{f inj}.The block diagram of the observer is shown in FIG. 3. It contains an integrator, which replaces the inductance of the field winding L _f . Applied voltage minus drop in winding resistance

integrates and calculates the field current estimate

Due to the large change in temperature, the resistance of the field winding during the operation of the electric drive changes significantly, and the difference between the estimate and the measured value is used to correct the estimate of the resistance using an observer represented by an integral link with a small gain K _res . When the parameters of the model correspond to the parameters of the object, the difference between the measured and estimated current is the net response from the injected signal i _{f inj} .

The response in the field current changes its phase depending on the position of the rotor. To determine the phase of the signal, it is multiplied by sinusoidal and cosine signals, in phase with the injection signals into the stator. The moving average filter has a window equal to the injection period, and after it the sinusoidal and cosine components of the angular position are obtained. These two signals are processed by a PLL filter that removes noise from the extracted signals. Thus, the phase difference between the injected signal and the response phase in the field winding allows you to accurately determine the angular position of the rotor of the electric motor. In FIG. Figure 4 shows the waveform of the start of the VIDNV with the developed position observer. The accuracy of the restoration of the position was checked using the DPR based on Hall elements. His signal was interpolated after some minimum speed. The error between the restored position and the measured one is small and the result obtained has high accuracy for the operation of the vector control system. Sources of literature:

1. Briz F., Degner M.W. Rotor Position Estimation // IEEE Industrial Electronics Magazine, 2011. Vol. 5, no. 2, P. 24-36.

2. Reigosa D.D., Briz F., Blanco C., Guerrero J.M. Sensorless Control of Doubly Fed Induction Generators Based on Stator High-Frequency Signal Injection. // IEEE Transactions on Industry Applications. 2014, Vol. 50, no. 5. - P. 3382-3391.

3. CN 107070345 A, BEIJING LEADER & HARVEST ELECTRIC TECH CO LTD, 08/18/2017.

4. US 20050184698 A1, Honeywell International Inc., 08.25.2005.

Claims (4)

1. The method of determining the angular position of the rotor of an electric AC machine containing a stator winding and an excitation winding, including the injection of a high-frequency signal into the stator winding, characterized in that receive a signal response from the field winding, and compare the phase of the injected signal and the response phase in the field winding, the difference of which determines the angular position of the rotor of the electric motor. 2. The method according to p. 1, characterized in that the electric motor is a valve-inductor electric motor of independent excitation.

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