阅读说明：本技术 一种基于磁链特性坐标变换的开关磁阻电机位置预估方法 (Switched reluctance motor position estimation method based on flux linkage characteristic coordinate transformation ) 是由 陈硕 李悦玮 李四保 熊官送 李晋生 于 2018-06-29 设计创作，主要内容包括：本发明属于传感器控制技术,具体为一种基于磁链特性坐标变换的开关磁阻电机位置预估方法,将开关磁阻电机磁链与转子位置的关系曲线划分为三个区域,检测边界四个位置的磁链特性数据,并确定当前的相磁链值,计算当前电流下区域Ⅱ两端处的磁链值,判定上述三个磁链值之间的关系,确定转子位置角,本方法计算过程简单,易于实现,仅需四个转子位置处的磁链特性数据,而且只占用少量的物理内存；通过多相预估法,减小了系统误差,精度高,鲁棒性强,分辨率高。(The invention belongs to the sensor control technology, in particular to a switched reluctance motor position estimation method based on flux characteristic coordinate transformation, which divides a relation curve of a switched reluctance motor flux and a rotor position into three regions, detects flux characteristic data of four positions on a boundary, determines a current phase flux value, calculates flux values at two ends of a region II under current, judges the relation between the three flux values and determines a rotor position angle, and has the advantages of simple calculation process, easy realization, only need flux characteristic data of four rotor positions and only small amount of physical memory occupation; by the aid of a multi-phase estimation method, system errors are reduced, and the method is high in precision, strong in robustness and high in resolution.)

1. A switched reluctance motor position estimation method based on flux linkage characteristic coordinate transformation is characterized by comprising the following steps:

step 1) dividing a relation curve of a phase flux linkage and a rotor position angle of a switched reluctance motor under a certain current into three regions, wherein the region is [ theta ]₀,θ₁]Is defined as region I, [ theta ]₁,θ_hr]Is defined as region II, [ theta ]_hr,θ_a]Is defined as region III

Step 2) detecting theta₀、θ₁、θ_hr、θ_aFour-position flux linkage characteristic data psi₀、ψ₁、ψ_hr、ψ_a

Will measure the obtained psi₀、ψ₁、ψ_hr、ψ_aSubstituting the following formula to determine 8 coefficients a, b, c, d, e, f, g, h

And 3) determining the current flux linkage value psi by using the following formula.

Wherein psi (0) is an initial flux linkage, and u, i and r are phase voltage, phase current and phase resistance of the switched reluctance motor, respectively;

step 4) determining theta under the current₁Magnetic linkage value psi₁(i) And theta at the present current_hrMagnetic linkage value psi_hr(i)；

Step 5) determining and determining the rotor position angle psi

When t is<Ψ₁(i) Indicating that the rotor position is in region I

ψ＝a(i)θ⁴+b(i)θ²+c(i)

When t is₁(i)<Ψ<Ψ_hr(i) Indicating that the rotor position is in region II

ψ＝d(i)θ+e(i)

When t is_hr(i)<Ψ indicating the rotor position is in region III

ψ(i)＝f(i)θ²+g(i)θ+h(i)

2. The switched reluctance motor position estimation method based on the coordinate transformation of the flux linkage characteristics as claimed in claim 1, wherein the step 1) is performed

θ₀In the non-aligned position, θ_aTo align the positions, θ₁And theta_hrIs determined by the following formula

Wherein, beta_sAnd beta_rStator pole arcs and rotor pole arcs, respectively.

3. The method for estimating the position of the switched reluctance motor based on the coordinate transformation of the flux linkage characteristics as claimed in claim 1, wherein ψ (0) is taken as 0 in the step 3).

4. The switched reluctance motor position estimation method based on the flux linkage characteristic coordinate transformation as claimed in claim 1, wherein the step 4) adopts a linear interpolation method to determine θ theta under the current₁Magnetic linkage value psi₁(i)。

5. The method as claimed in claim 1, wherein the coefficients a (i), b (i), c (i), d (i), e (i), f (i), g (i) and h (i) are obtained by linear interpolation in step 5).

Technical Field

The invention belongs to the sensor control technology, and particularly relates to a switched reluctance motor position estimation method based on flux linkage characteristic coordinate transformation.

Background

In a switched reluctance motor driving system, rotor position information is crucial to the implementation of a control method and the normal operation of the system, and the information is generally obtained by mechanical position sensors such as a photoelectric encoder and a rotary transformer. However, the presence of mechanical position sensors increases the complexity of the system architecture, increases manufacturing costs, and the sensor performance is susceptible to environmental influences. Therefore, it is necessary to develop a low-cost, high-precision, and high-reliability sensorless control method suitable for a switched reluctance motor.

In order to implement position sensorless control, researchers have proposed a number of position estimation methods. These methods are mainly divided into two categories: a non-conducting phase position estimation method and a conducting phase position estimation method.

The first method is mainly characterized in that voltage pulses are injected into a non-conducting phase of the switched reluctance motor, a winding generates low-amplitude detection current under the excitation of constant-frequency low-duty-cycle voltage, and the counter electromotive force of the motor can be ignored at the moment due to the fact that the detection current is small. According to the voltage balance equation, the amplitude of the detection current is inversely proportional to the phase inductance of the current position, so that the method can be used for position estimation. The method is characterized in that the initial position of the rotor can be detected, and continuous position information can be detected at medium and low speeds, but the method is not suitable for high-speed working conditions.

The second method is mainly based on flux linkage characteristics of the switched reluctance motor, stores or expresses flux linkage characteristic data obtained through measurement in the forms of a lookup table, a neural network and the like, and then obtains rotor position information according to on-line measured conduction phase current and flux linkage data. The method has higher estimation precision and wider rotating speed application range, but needs a large amount of flux linkage characteristic sample data which are usually obtained through detailed finite element analysis or experimental measurement, so that the complexity and the cost of the method are increased, and meanwhile, a larger physical memory is often occupied when the method is realized.

Disclosure of Invention

The invention aims to provide a switched reluctance motor position estimation method based on flux linkage characteristic coordinate transformation, which has higher precision and strong robustness and is simple and easy to realize.

The technical scheme of the invention is as follows:

a switched reluctance motor position estimation method based on flux linkage characteristic coordinate transformation comprises the following steps:

step 1) dividing a relation curve of a phase flux linkage and a rotor position angle of a switched reluctance motor under a certain current into three regions, wherein the region is [ theta ]₀,θ₁]Is defined as region I, [ theta ]₁,θ_hr]Is defined as region II, [ theta ]_hr,θ_a]Is defined as region III

Step 2) detecting theta₀、θ₁、θ_hr、θ_aFour-position flux linkage characteristic data psi₀、ψ₁、ψ_hr、ψ_a

Will measure the obtained psi₀、ψ₁、ψ_hr、ψ_aSubstituting the following formula to determine 8 coefficients a, b, c, d, e, f, g, h

And 3) determining the current flux linkage value psi by using the following formula.

Wherein psi (0) is an initial flux linkage, and u, i and r are phase voltage, phase current and phase resistance of the switched reluctance motor, respectively;

step 4) determining theta under the current₁Magnetic linkage value psi₁(i) And theta at the present current_hrMagnetic linkage value psi_hr(i)；

Step 5) determining and determining the rotor position angle psi

When t is<Ψ₁(i) Indicating that the rotor position is in region I

ψ＝a(i)θ⁴+b(i)θ²+c(i)

When t is₁(i)<Ψ<Ψ_hr(i) To indicate rotationWith the sub-position located in region II

ψ＝d(i)θ+e(i)

When t is_hr(i)<Ψ indicating the rotor position is in region III

ψ(i)＝f(i)θ²+g(i)θ+h(i)

In the step 1)

θ₀In the non-aligned position, θ_aTo align the positions, θ₁And theta_hrIs determined by the following formula

Wherein, beta_sAnd beta_rStator pole arcs and rotor pole arcs, respectively.

In the step 3), psi (0) is taken as 0.

Step 4) determining theta under the current by adopting a linear interpolation method₁Magnetic linkage value psi₁(i)。

In the step 5), coefficients a (i), b (i), c (i), d (i), e (i), f (i), g (i) and h (i) are obtained by linear interpolation.

The invention has the following remarkable effects: a relation curve of flux linkage and rotor position of the switched reluctance motor is divided into three regions, and the three regions are respectively expressed as a quadratic function, a linear function and a quadratic function in different regions, wherein a region I adopts the idea of flux linkage characteristic coordinate transformation. Based on the magnetic linkage, the rotor position can be solved. The method is simple and easy to realize. After coordinate transformation is carried out on the flux linkage characteristics, the position angle of the rotor can be quickly resolved; only the flux linkage characteristic data at the positions of four rotors are needed, and only a small amount of physical memory is occupied; through a multi-phase estimation method, system errors are reduced, and the method is high in precision, strong in robustness and high in resolution; the precision is good under the working conditions of angle position control, current chopping control and voltage PWM control, the method is also suitable for different switched reluctance motor topologies, and the applicability is good.

Drawings

Fig. 1 is a graph of a relationship between a phase flux linkage and a rotor position angle of a switched reluctance motor under a certain current.

Fig. 2 is a graph of the square of the rotor position angle of the switched reluctance motor in the area i under a certain current and the phase flux linkage.

Fig. 3 is a graph showing a relationship between a rotor position angle and a phase flux linkage of a switched reluctance motor in a region ii at a certain current.

Fig. 4 is a graph of a relation between a rotor position angle and a phase flux linkage of a switched reluctance motor in a region III under a certain current.

Detailed Description

The invention is described in further detail below with reference to the figures and the embodiments.

Step 1, dividing a relation curve of a phase flux linkage and a rotor position angle of a switched reluctance motor under a certain current into three regions

FIG. 1 shows a relationship curve between the flux linkage of the switched reluctance motor phase and the rotor position at a certain current, and the interval [ theta ] is₀,θ₁]Is defined as region I, [ theta ]₁,θ_hr]Is defined as region II, [ theta ]_hr,θ_a]Defined as region III, FIGS. 2-4, respectively.

At four boundary special positions theta defined above₀、θ₁、θ_hr、θ_aIn, theta₀In the non-aligned position, θ_aTo align the positions, θ₁And theta_hrCan be obtained from the formulae (1) and (2).

Wherein, beta_sAnd beta_rStator pole arcs and rotor pole arcs, respectively.

Step 2 detection of theta₀、θ₁、θ_hr、θ_aFour-position flux linkage characteristic data psi₀、ψ₁、ψ_hr、ψ_aThe flux linkage characteristics at four positions can be obtained by equation (3).

Will measure the obtained psi₀、ψ₁、ψ_hr、ψ_a8 coefficients a, b, c, d, e, f, g, h were obtained by substituting equation (4).

And 3, detecting the conducting phase voltage and current value, and calculating by using the formula (5) to obtain the current phase flux linkage value psi.

Where ψ (0) is an initial flux linkage, ψ (0) is generally taken as 0 because the silicon steel material has a small residual magnetism; u, i and r are phase voltage, phase current and phase resistance of the switched reluctance motor, respectively.

Step 4, linear interpolation is utilized to obtain theta under the current₁Magnetic linkage value psi₁(i) At the current of theta_hrMagnetic linkage value psi_hr(i)。

Step 5 if<Ψ₁(i) And calculating coefficients a (i), b (i) and c (i) by linear interpolation to indicate that the rotor position is in the region I. At the moment, the magnetic linkage and the square of the rotor position angle are in a quadratic function relationship as shown in the formula (6), and the rotor position angle can be obtained through the formula (7).

ψ＝a(i)θ⁴+b(i)θ²+c(i) (6)

Step 6 if Ψ₁(i)<Ψ<Ψ_hr(i) And indicating that the rotor position is in the area II, and calculating d (i) and e (i) by using linear interpolation. At this time, the flux linkage and the rotor position angle are in a linear function relationship as shown in the formula (8), and the rotor position angle can be obtained through the formula (9).

ψ＝d(i)θ+e(i) (8)

Step 7 if_hr(i)<Ψ, which indicates the rotor position in region III, and using linear interpolation to obtain f (i), g (i) and h (i). At this time, the flux linkage and the rotor position angle are in a quadratic function relationship as shown in formula (10), and the rotor position angle can be obtained through formula (11).

ψ(i)＝f(i)θ²+g(i)θ+h(i) (10)

And 8, if the system error introduced during the rotor position estimation under the low current needs to be further reduced, estimating by adopting the multi-phase flux linkage characteristic instead of the single-phase flux linkage characteristic. The phase selection principle is as follows: and selecting the phase with the maximum phase current for position estimation according to the magnitude of each phase current.