CN103595324B - A kind of mixed excitation electric machine field weakening control method - Google Patents

Abstract

The invention discloses a kind of mixed excitation electric machine field weakening control method, when motor speed is higher than rated speed, motor enters invariable power district, weak magnetic algorithm is now adopted to improve motor speed further, concrete grammar is: ignore armature resistance, and keeping motor synthesis back electromotive force constant is motor terminal voltage maximum, utilizes exciting current to weaken air-gap flux and carries out motor raising speed, distribute armature supply and exciting current accordingly, motor torque fan-out capability can be improved.The inventive method can realize mixed excitation electric machine high speed wide speed regulating range and run, and effectively improves the torque output capability of motor simultaneously, has a good application prospect in the straight drive system of Wheel hub for electric automobile formula.

Description

A Field Weakening Control Method for Hybrid Excitation Motor

technical field

The invention relates to a field-weakening control method for a hybrid excitation motor, which belongs to the motor control technology.

Background technique

Permanent magnet motors have the advantages of simple structure, high power density, large torque-to-mass ratio, and high efficiency. However, the main air gap magnetic field of permanent magnet motors is generated by permanent magnets installed on the rotor or stator, which is difficult to achieve during the operation of the motor. adjust. The hybrid excitation motor has two kinds of excitation sources, one is permanent magnet and the other is electric excitation, which has a strong magnetic field adjustment capability; when the motor is started, a positive excitation current is introduced to generate a positive electromagnetic torque, which can increase the motor starting. When running at high speed, the reverse excitation current can effectively improve the motor's field-weakening speed-up capability. Compared with permanent magnet motors, hybrid excitation motors have the advantages of large output torque and wide speed regulation range, and have good application prospects in in-wheel direct drive systems for electric vehicles.

At present, most hybrid excitation motors adopt the vector control algorithm based on partition control. The constant torque area is below the rated speed, and the constant power area is above the rated speed. In the constant power area, the control strategy of keeping the q-axis back EMF at a constant value is mostly adopted. Excitation current field weakening; Compared with the method of using d-axis current field weakening for ordinary permanent magnet synchronous motors, the hybrid excitation motor using this type of algorithm has a wider speed regulation range. However, the cost of field-weakening speed-up is to sacrifice the load-carrying capacity of the motor. As the speed increases, the torque output capacity of the motor decreases inversely.

In practical applications, the battery voltage drops sharply after the electric vehicle has been running for a long time, which will reduce the speed range of the constant torque zone; in addition, when the load is large, the increased forward excitation current will generate additional back electromotive force, which will also reduce the The speed range in the small constant torque area; on the other hand, in the high-speed field weakening area, the d-axis back EMF is relatively small when the load is small. At this time, the traditional current distribution algorithm that keeps the q-axis back EMF at a constant value can ensure the synthesis The back electromotive force does not exceed the DC bus voltage, but when the load is large, the d-axis back electromotive force will increase significantly, and there will be a large error when using this algorithm.

Contents of the invention

Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a field-weakening control method for a hybrid excitation motor, which adopts a field-weakening control strategy that keeps the synthetic back EMF at a constant value, and realizes the purpose of high-speed and wide-range operation of the hybrid excitation motor .

Technical scheme: in order to achieve the above object, the technical scheme adopted in the present invention is:

A field-weakening control method for a hybrid excitation motor. When the motor speed is higher than the rated speed, the motor enters the constant power region. At this time, the field-weakening algorithm is used to further increase the motor speed. The maximum value of the motor terminal voltage is constant, and the excitation current is used to weaken the air-gap flux to increase the speed of the motor. Based on this, the armature current and the excitation current are distributed, which can improve the torque output capability of the motor.

The method specifically includes the following steps:

(1) When the motor enters the constant power region, keep the synthesized back electromotive force of the motor constant at the maximum value of the motor terminal voltage, and the armature current and excitation current satisfy the following formula:

${\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; back</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}\sqrt{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&psi;</span>}}_{\mathrm{<span\; class="notranslate">\; pm</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, E _back is the synthesized back electromotive force of the motor, ω _e is the electrical angular velocity of the motor, ψ _pm is the permanent magnet flux of the motor, M _sf is the mutual inductance between the armature winding and the field winding, if is the excitation current, L _d is the _d -axis inductance , L _q is the q-axis inductance, id is the _d -axis component of the armature current, i _q is the q-axis component of the armature current, and U _max is the maximum value of the motor terminal voltage.

(2) i _q is the q-axis component of the armature current, and the combined value of the armature current cannot exceed the rated value. Setting i _d = 0 can make the armature current have a larger torque component; on the other hand, for the salient pole motor , the reverse _d -axis current will generate negative reluctance torque, which will reduce the output capability of motor torque; therefore, in order to make the torque component of armature current as large as possible and avoid negative reluctance torque, keep id = 0, the excitation current is used for field-weakening speed-up, and the motor torque T _e is calculated by the following formula:

${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&psi;</span>}}_{\mathrm{<span\; class="notranslate">\; pm</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Among them, p is the number of pole pairs of the motor;

(3) Under the premise of not exceeding their respective rated values, substitute _{i q} and if satisfying formula (1) into formula (2), and obtain the corresponding armature current given value and excitation current when T _e is the maximum value The given values are:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; fref</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&psi;</span>}}_{\mathrm{<span\; class="notranslate">\; pm</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}{\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; dref</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; qref</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}{\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Take the calculated armature current given value and excitation current given value as the control quantity of hybrid excitation motor.

Beneficial effects: the field-weakening control method of the hybrid excitation motor provided by the present invention adopts a field-weakening control strategy that keeps the combined back EMF at a constant value according to the structural characteristics of the hybrid excitation motor, and realizes the purpose of high-speed and wide-range operation of the hybrid excitation motor; Compared with the traditional algorithm that keeps the q-axis back EMF at a constant value, Benfen Amin's drive system has higher control accuracy and stability. In the field weakening area, the current distribution strategy is formulated with the output torque as the optimization goal, which improves the high-speed operation of the motor. torque output capability.

Description of drawings

Fig. 1 is a control system block diagram of the present invention;

Figure 2 is the torque-excitation current waveform;

Figure 3 is the torque-speed waveform.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

A field-weakening control method for a hybrid excitation motor. When the motor speed is higher than the rated speed, the motor enters the constant power region. At this time, the field-weakening algorithm is used to further increase the motor speed. The maximum value of the motor terminal voltage is constant, and the excitation current is used to weaken the air-gap flux to increase the speed of the motor. Based on this, the armature current and the excitation current are distributed, which can improve the torque output capability of the motor.

As shown in Figure 1, it is a block diagram of a control system based on the present invention, the system is composed of a main circuit, a detection circuit and a control circuit; the main circuit consists of a hidden pole hybrid excitation motor (HESM motor), a PWM inverter, a current distributor, It is composed of excitation regulator and excitation inverter; the detection circuit is composed of voltage and current sensors and incremental photoelectric encoder. The position sensor detects the rotation angle signal θ of the motor, and θ obtains the actual speed n of the motor through the differential link. Motor given speed n _ref and actual speed n get torque given value T _ref through PI link. Send T _ref and n into the current divider to calculate the given values _idref and i _qref of the armature current dq axis components and the given value i _fref of the excitation current. The actual values of the armature and excitation currents measured by the current sensor are i _a , i _b and i _{freal respectively} , where i _a and i _b undergo coordinate changes to obtain the actual values of the dq axis components of the armature current i _dreal and i _qreal , The dq-axis current given values i _dref and i _qref and their respective actual values i _dreal and i _qreal respectively pass through the PI link, the coordinate exchange module and the space vector module SVPWM to generate a three-phase duty ratio signal, and the three-phase duty ratio The ratio signal acts on the hybrid excitation motor through a three-phase inverter. The excitation current given value i _fref and actual value i _freal are generated by the excitation regulator to act on the hybrid excitation motor through the excitation inverter.

The method of the present invention is mainly embodied in the lower part of the current distributor. The Fangming method can also be referred to as the working principle of the current distributor, and mainly includes the following steps:

(1) When the motor enters the constant power region, keep the synthesized back electromotive force of the motor constant at the maximum value of the motor terminal voltage, and the armature current and excitation current satisfy the following formula:

${\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; back</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}\sqrt{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&psi;</span>}}_{\mathrm{<span\; class="notranslate">\; pm</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, E _back is the synthesized back electromotive force of the motor, ω _e is the electrical angular velocity of the motor, ψ _pm is the permanent magnet flux of the motor, M _sf is the mutual inductance between the armature winding and the field winding, if is the excitation current, L _d is the _d -axis inductance , L _q is the q-axis inductance, id is the _d -axis component of the armature current, i _q is the q-axis component of the armature current, and U _max is the maximum value of the motor terminal voltage.

(2) i _q is the q-axis component of the armature current, and the combined value of the armature current cannot exceed the rated value. Setting i _d = 0 can make the armature current have a larger torque component; on the other hand, for the salient pole motor , the reverse _d -axis current will generate negative reluctance torque, which will reduce the output capability of motor torque; therefore, in order to make the torque component of armature current as large as possible and avoid negative reluctance torque, keep id = 0, the excitation current is used for field-weakening speed-up, and the motor torque T _e is calculated by the following formula:

${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&psi;</span>}}_{\mathrm{<span\; class="notranslate">\; pm</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Among them, p is the number of motor pole pairs;

(3) Under the premise of not exceeding their respective rated values, substitute _{i q} and if satisfying formula (1) into formula (2), and obtain the corresponding armature current given value and excitation current when T _e is the maximum value Given values, specifically:

The expression of i _q obtained from formula (1) is:

${\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; =</span>\frac{\sqrt{{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&psi;</span>}}_{\mathrm{<span\; class="notranslate">\; pm</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Putting the expression of i _q into formula (2), the expression of T _e is obtained as:

${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&psi;</span>}}_{\mathrm{<span\; class="notranslate">\; pm</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span>\frac{\sqrt{{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}{{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&psi;</span>}}_{\mathrm{<span\; class="notranslate">\; pm</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

Equation (4) is a one-dimensional quadratic function with a downward opening, which has a maximum value, as shown in Figure 2; when T _e is the maximum value, the corresponding armature current given value and excitation current given value are:

$\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; fref</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&psi;</span>}}_{\mathrm{<span\; class="notranslate">\; pm</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}{\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; sf</span>}}}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; dref</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; qref</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}{\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

The calculated armature current given value and excitation current given value are used as the control quantity of the hybrid excitation motor to control the hybrid excitation motor.

According to the system shown in Figure 1, the simulation model is built in the MATLAB/SIMULINK environment, and the motor parameters are shown in Table 1:

Table 1 motor parameters

parameter value Permanent magnet flux amplitude ψ _pm (Wb) 0.11348 number of pole pairs p 4 Armature winding resistance R _s (Ω) 2.7 Excitation winding resistance R _f (Ω) 10 Direct axis inductance L _d (mH) 24.1 Quadrature axis inductance L _q (mH) 19.6 Mutual inductance of armature and field winding M _sf (mH) 52 Rated torque T _e (N) 3.4 Rated speed N (rpm) 1500 Bus voltage U _dc (V) 300 Armature current rating (A) 5 Excitation current rating (A) 1

Simulation results are shown in Figure 3.

Figure 3 is the maximum output torque waveform of the motor at different speeds. It can be seen from the figure that the algorithm can effectively increase the torque output capacity of the hybrid excitation motor.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications are also possible. It should be regarded as the protection scope of the present invention.

Claims (1)

1. A field-weakening control method for a hybrid excitation motor, characterized in that: when the motor speed is higher than the rated speed, the motor enters a constant power zone, and at this moment, the field-weakening algorithm is used to further increase the motor speed, and the specific method is: ignore the armature resistance , keep the combined back electromotive force of the motor constant at the maximum value of the motor terminal voltage, use the excitation current to weaken the air gap flux to increase the speed of the motor, and distribute the armature current and the excitation current accordingly; the method specifically includes the following steps: (1) When the motor enters the constant power region, keep the synthetic counter electromotive force of the motor constant at the maximum value of the motor terminal voltage, and the armature current and excitation current satisfy the following formula: ${\mathrm{<span\; class="notranslate">\; E.</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}\sqrt{{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&psi;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$ Among them, E _back is the synthesized back electromotive force of the motor, ω _e is the electrical angular velocity of the motor, ψ _pm is the permanent magnet flux of the motor, M _sf is the mutual inductance between the armature winding and the field winding, if is the excitation current, L _d is the _d -axis inductance , L _q is the q-axis inductance, id is the _d -axis component of the armature current, i _q is the q-axis component of the armature current, and U _max is the maximum value of the motor terminal voltage. (2) Keep i _d = 0, use the excitation current to increase the speed by weakening the field, and the motor torque is calculated by the following formula: ${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 3</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&psi;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; f</span>}}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$ Among them, p is the number of motor pole pairs; (3) Substituting _{i q} and if satisfying formula (1) into formula (2), the armature current given value and excitation current given value corresponding to the maximum value of _Te are obtained: $\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&psi;</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; -</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}{\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}}}{{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; f</span>}}}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; e</span>}\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}}{\sqrt{\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; e</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; q</span>}}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$ Take the calculated armature current given value and excitation current given value as the control quantity of hybrid excitation motor.