CN105591524A - Permanent magnet rotating speed difference clutch and self-adaption nonsingular terminal slip form rotating speed control method thereof - Google Patents

Abstract

The invention discloses a permanent magnet rotating speed difference clutch and a self-adaption nonsingular terminal slip form rotating speed control method thereof. The method is characterized in that (1) an outer rotor of a permanent magnet rotating speed difference clutch is connected with an engine, and an inner rotor is connected with a steering pump, and then a permanent magnet rotating speed difference clutch type electronically controlled hydraulic power steering system can be formed; (2) a permanent magnet rotating speed difference clutch mathematic model can be established, and comprises a voltage equation, an electromagnetic torque equation, and a motion equation; (3)according to the mathematic mode, the self-adaption nonsingular terminal slip form surface can be designed by adopting the self-adaption nonsingular terminal slip form control method, and the control law can be deduced, and the self-adaption law of the parameter uncertain factors can be designed by adopting the Lyapunov stability theory, and the stability of the control system can be guaranteed. By adopting the self-adaption nonsingular terminal slip form control method, the problems of the system parameter perturbation and the external interference uncertainty can be overcome, the jitter can be reduced, the strong robustness can be provided, the accurate control over the permanent magnet rotating speed difference clutch output rotating speed can be realized, and the tracking error can be reduced to zero quickly.

Description

Permanent magnet slip clutch and self-adaptive nonsingular terminal sliding mode rotating speed control method thereof

Technical Field

The invention belongs to the field of automobile hydraulic power-assisted steering systems, and particularly relates to a self-adaptive nonsingular terminal sliding mode rotating speed control method for a permanent magnet slip clutch.

Background

With the progress and development of scientific technology and automobile industry, people not only meet the improvement of vehicle performance, but also pay more and more attention to the operation stability, safety and energy conservation during vehicle running. At present, most heavy vehicles use a traditional hydraulic power steering system (HPS) and can provide good power assistance at low speed, but the power assistance characteristics are single and cannot be changed along with the change of the vehicle speed, so that when the vehicle runs at high speed, the power assistance is overlarge, the 'road feel' of a driver is poor at the moment, the problem of floating of a steering wheel can be caused, and certain influence is generated on the operation stability and the safety of the vehicle. Meanwhile, data show that the running time of the vehicle in a steering state is not more than 20%, but the steering pump of the conventional HPS is directly connected with the engine, the steering pump is always in a running state in about 80% of non-steering time, and the energy loss of a hydraulic circuit is larger when the rotating speed of the steering pump is higher, so that the energy waste is caused.

On the basis of a traditional HPS system, a permanent magnet slip clutch is connected to the output end of an engine and the input end of a steering pump to form a permanent magnet slip clutch type electric control hydraulic power-assisted steering system (ECHPS). The slip of the driving part and the driven part can be controlled by adjusting the duty ratio of an external circuit IGBT of the permanent magnet slip clutch, so that the rotating speed and the torque of the steering pump are controlled. The permanent magnet slip clutch can realize stepless speed change and smooth torque transmission, so that the steering pump outputs hydraulic power as required under different working conditions, the steering portability of the heavy vehicle at low speed and good road feel at high speed are ensured, and the maneuverability, safety and energy conservation are improved. The electromagnetic slip clutch type electric control hydraulic steering system provided by the invention patent CN105109549A controls the slip of the driving part and the driven part by adjusting the exciting current, thereby controlling the rotating speed and the torque of the steering pump, but researches find that the electromagnetic slip clutch has the defects of large volume and large rotational inertia. The utility model patent CN204465317U teaches a permanent-magnet slip clutch, which is similar to the present invention in structure, wherein the outer rotor is a permanent-magnet rotor, the inner rotor is a winding rotor, and an electric switch is used to control the connection and disconnection of the permanent-magnet slip clutch. The outer rotor is a winding rotor, the inner rotor is a permanent magnet rotor, the speed regulation function of the permanent magnet slip clutch is realized by regulating the duty ratio of an external circuit IGBT, and a self-adaptive nonsingular terminal sliding mode control algorithm is applied, so that the control effect is better.

When the steering system is in steering, the permanent magnet slip clutch type ECHPS system has some uncertainties (such as fluctuation of the rotating speed of an engine) and external interference (such as side wind), the rotating speed fluctuation of a steering pump and the rotating angle/torque jumping of a steering wheel are caused, and the control quantity of the permanent magnet slip clutch is shaken, so that the rotating speed of the steering pump is changed accordingly.

The sliding mode control has the advantages of being insensitive to parameter change and disturbance, good in robustness and the like. The traditional sliding mode control selects a linear sliding mode surface, and the linear sliding mode surface has certain limitation for some complex nonlinear systems with higher control requirements.

Disclosure of Invention

Aiming at a permanent magnet slip clutch type ECHPS system, a self-adaptive nonsingular terminal sliding mode control method is provided, the problems of parameter perturbation and external interference uncertainty can be solved, the tracking error can be quickly converged to zero (namely the rotating speed of a steering pump quickly tracks an ideal value), and the robustness is better. The technical scheme for realizing the invention is as follows:

a permanent-magnet slip clutch comprises an outer rotor, an inner rotor and an outer control circuit; the outer rotor is internally embedded with a three-phase winding, the three-phase winding is connected with an outer control circuit through a slip ring and an electric brush, and the inner rotor is pasted with a permanent magnet to form a non-salient pole type inner rotor structure; when the outer rotor rotates, electromagnetic torque is generated between the inner rotor and the outer rotor, and the electromagnetic torque drives the inner rotor to rotate; the outer control circuit is a Boost circuit based on an IGBT and is used for accurately controlling the rotating speed of the inner rotor.

As a preferred scheme, the outer rotor is used as an input end and is connected with an engine through a driving shaft, and the engine drives the outer rotor to rotate; the inner rotor is used as an output end and is connected with the steering pump through a driven shaft, and the inner rotor drives the steering pump to rotate.

Based on the permanent magnet slip clutch, the invention also provides a self-adaptive nonsingular terminal sliding mode rotating speed control method of the permanent magnet slip clutch, which comprises the following steps:

step 1, on the basis of a traditional HPS structure, connecting an outer rotor of a permanent magnet slip clutch with an engine through a driving shaft, and connecting an inner rotor with a steering pump through a driven shaft to construct a permanent magnet slip clutch type electric control hydraulic power steering system;

step 2, establishing a state equation of the rotation speed error of the steering pump;

and 3, designing a self-adaptive nonsingular terminal sliding mode controller based on the Lyapunov function.

Preferably, the external control circuit of the permanent magnet slip clutch in step 1 is a Boost circuit based on an IGBT, and the current of the three-phase winding of the outer rotor is changed by adjusting the duty ratio of the IGBT, thereby changing the magnitude of the electromagnetic torque.

Preferably, the step 2 is realized by:

step 2-1, establishing a mathematical model of the permanent magnet slip clutch, comprising the following steps:

equation of voltage $\left\{\begin{array}{c}{U}_d-(1-D)U_c=L_d\stackrel{\·}{I_d}+{\mathrm{RI}}_d\\ U_d=k({\mathrm{\ω}}_1-{\mathrm{\ω}}_2)\\ U_c=\sqrt{L_d/c}{I}_d\end{array}\right.;$

Electromagnetic torque equation T_e＝C_mI_d；

Equation of motion $T_e-T_L-F_2{\mathrm{\ω}}_2=J_2\stackrel{\·}{{\mathrm{\ω}}_2};$

Wherein, U_dFor induced electromotive force, k is the induced electromotive force coefficient, D is the duty ratio, U_cIs the voltage at the capacitor terminal, L_dIs an equivalent inductance of an outer rotor rectifying circuit, I_dFor the winding current of the outer rotor rectification loop, R is the equivalent resistance of the outer rotor rectification loop, omega₁、ω₂Mechanical angular velocities of the outer and inner rotors, c is capacitance, T_eIs an electromagnetic torque, C_mIs a torque coefficient, T_LTo load torque, F₂For the damping coefficient of rotation of the inner rotor, J₂Is the rotational inertia of the inner rotor;

step 2-2, define the state variable E ═ E₁,e₂]^TI.e. by $\left\{\begin{array}{c}{e}_1={\mathrm{\ω}}_2-{\mathrm{\ω}}_d\\ e_2=\stackrel{\·}{e_1}=\stackrel{\·}{{\mathrm{\ω}}_2}-\stackrel{\·}{{\mathrm{\ω}}_d}\end{array}\right.;$ Wherein, ω is_dThe ideal rotating speed of the steering pump;

and 2-3, combining the step 2-1 with the step 2-2 to obtain a state equation of the rotation speed error of the steering pump, wherein the state equation is as follows:

$\left\{\begin{array}{c}\stackrel{\·}{e_1}=e_2\\ \stackrel{\·}{e_2}=f+gu+d\left(t\right)\end{array}\right.$

wherein, $f=-\frac{C_{m}k+\left(\sqrt{L_d/c}+R\right)F_2}{L_d{J}_2}{\mathrm{\ω}}_2-\frac{\left(\sqrt{L_d/c}+R\right)J_2+L_d{F}_2}{L_d{J}_2}\stackrel{\·}{{\mathrm{\ω}}_2}+\frac{C_m{\mathrm{k\ω}}_1-\left(\sqrt{L_d/c}+R\right)T_L-L_d\stackrel{\·}{T_L}}{L_d{J}_2},$ $g=\frac{\sqrt{L_d/c}(J_2\stackrel{\·}{{\mathrm{\ω}}_2}+T_L+F_2{\mathrm{\ω}}_2)}{L_d{J}_2},d\left(t\right)=-\stackrel{\·\·}{{\mathrm{\ω}}_d},$ u is a control amount.

And 2-4, obtaining a state equation of the rotation speed error of the steering pump containing the parameter perturbation and the external interference, wherein the state equation comprises the following steps:

$\left\{\begin{array}{c}\stackrel{\·}{e_1}=e_2\\ \stackrel{\·}{e_2}=f+gu+g\left(t\right)\end{array}\right.$

wherein g (t) is the total uncertainty, g (t) ═ Δ f + Δ gu + d (t), Δ f, Δ g are uncertainty factors, | g (t) | ≦ l_g，l_gIs the interference upper bound.

Preferably, the step 3 is realized as follows:

step 3-1, selecting nonsingular terminal sliding mode surfaces according to the state equation established in the step 2 as follows:

β therein>0, p and q are positive odd numbers, and 1<p/q<2；

Step 3-2, establishing a nonsingular terminal sliding mode control law by using the nonsingular terminal sliding mode surface, wherein the nonsingular terminal sliding mode control law is as follows:

$u=-\frac{1}{g}(f+\mathrm{\&beta;}\frac{q}{p}{e_2}^{2-\frac{p}{q}}+(l_g+\mathrm{\&eta;}\left)\mathrm{sgn}\right(s\left)\right);$ η therein>0；

Step 3-3, with l_gIs estimated value ofSubstitute for l_gAnd obtaining a self-adaptive nonsingular terminal sliding mode control law as follows:

$u=-\frac{1}{g}(f+\mathrm{\&beta;}\frac{q}{p}{e_2}^{2-\frac{p}{q}}+(\widehat{l_g}+\mathrm{\&eta;}\left)\mathrm{sgn}\right(s\left)\right);$

step 3-4, defining the Lyapunov function:

$V=\frac{1}{2}{s}^2+\frac{1}{2m}\widetilde{{l_g}^2};$ wherein $\widetilde{l_g}=l_g-\widehat{l_g},$ m is an adjustable parameter greater than 0;

step 3-5, designing an adaptive law: $\stackrel{\&CenterDot;}{\widehat{l_g}}=m\mathrm{\&epsiv;}\left|s\right|,\mathrm{\&epsiv;}=\frac{1}{\mathrm{\&beta;}}\frac{p}{q}{e_2}^{\frac{p}{q}-1},$ to obtain

$\begin{array}{c}\stackrel{\&CenterDot;}{V}=S\stackrel{\&CenterDot;}{S}-\frac{1}{m}\widetilde{l_g}\stackrel{\&CenterDot;}{\widehat{l_g}}=\frac{1}{\mathrm{\&beta;}}\frac{p}{q}{e_2}^{\frac{p}{q}-1}\&lsqb;sg\left(t\right)-\left(\widehat{l_g}+\mathrm{\&eta;}\right)\left|s\right|\&rsqb;-\frac{1}{m}\widetilde{l_g}\stackrel{\&CenterDot;}{\widehat{l_g}}\\ =\frac{1}{\mathrm{\&beta;}}\frac{p}{q}{e_2}^{\frac{p}{q}-1}\&lsqb;sg\left(t\right)-\left(\widehat{l_g}+\mathrm{\&eta;}\right)\left|s\right|\&rsqb;-\frac{1}{\mathrm{\&beta;}}\frac{p}{q}{e_2}^{\frac{p}{q}-1}\widetilde{l_g}\left|s\right|\\ \&le;-\frac{1}{\mathrm{\&beta;}}\frac{p}{q}{e_2}^{\frac{p}{q}-1}\mathrm{\&eta;}\left|s\right|\end{array}.$

The invention has the beneficial effects that:

(1) a novel steering system, namely a permanent magnet slip clutch type electric control hydraulic power-assisted steering system is constructed, the basic structure principle of the traditional HPS is inherited, the power output as required can be realized by controlling the rotating speed of the permanent magnet slip clutch (namely controlling the rotating speed of a steering pump), the variable power-assisted characteristic is realized, the steering portability of a vehicle at low speed and the good road feel at high speed are ensured, and the energy consumption is saved.

(2) The rotating speed of the permanent magnet slip clutch is controlled by combining nonsingular terminal slip mode control with self-adaptive control, and compared with common slip mode control, the control system can be quickly converged to a desired track within a limited time, is quick in dynamic response, has higher steady-state precision, can solve the problems of perturbation of system parameters and uncertainty of external interference, and has good robustness.

Drawings

FIG. 1 is a mechanical schematic diagram of a permanent magnet slip clutch;

FIG. 2 is a schematic view of a permanent magnet slip clutch type electric control hydraulic power steering system;

FIG. 3 is a control diagram of an external circuit of the permanent magnet slip clutch;

FIG. 4 is a control strategy diagram of a permanent magnet slip clutch type electric control hydraulic power steering system;

FIG. 5 is a rotation speed tracking error of adaptive nonsingular terminal sliding mode control during pivot steering;

FIG. 6 is a comparison of control effects of a self-adaptive nonsingular terminal sliding mode and a common sliding mode during pivot steering;

FIG. 7 is a diagram of the engine speed under a certain condition, wherein the engine speed is disturbed and changed within 1-1.5s, and the engine speed is kept at 1300r/min for the rest of time;

FIG. 8 is a diagram illustrating the control effect of adaptive nonsingular terminal sliding mode control on the rotating speed when the engine is disturbed under a certain condition (the ideal rotating speed under the certain condition is 450 r/min);

figure 9 is an enlarged view of the boost characteristic of figure 4.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

A permanent magnet slip clutch self-adaptive nonsingular terminal sliding mode rotating speed control method comprises the following specific steps:

the method comprises the following steps: electric control hydraulic power-assisted steering system for constructing permanent magnet slip clutch

As shown in fig. 1 and 2, the permanent-magnet slip clutch mainly comprises an outer rotor, an inner rotor and an outer control circuit. The outer rotor is embedded with a three-phase winding, the three-phase winding is connected with an outer control circuit through a slip ring and an electric brush, and the inner rotor is pasted with a permanent magnet to form a non-salient pole inner rotor structure. The outer rotor is an input end and is connected with an engine through a driving shaft, and the inner rotor is an output end and is connected with a steering pump through a driven shaft, so that the permanent magnet slip clutch type electric control hydraulic power-assisted steering system shown in figure 2 is formed.

Step two: equation of state for establishing error of rotating speed of steering pump

As shown in fig. 1, the working principle of the permanent magnet slip clutch is as follows: the permanent magnet establishes a constant main magnetic field in the magnetic pole of the inner rotor, when the engine drives the outer rotor to rotate, the armature part cuts the main magnetic field, the three-phase winding generates induced current to form an armature magnetic field which is interlinked with the main magnetic field, so that electromagnetic torque is generated between the inner rotor and the outer rotor, and the electromagnetic torque drives the inner rotor to rotate together with the steering pump.

As shown in fig. 3, the external control circuit of the permanent magnet slip clutch is a Boost circuit based on an IGBT, and by adjusting the duty ratio of the IGBT, the current of the three-phase winding of the outer rotor can be changed, so that the magnitude of the electromagnetic torque can be changed, and the accurate control of the rotation speed of the inner rotor and the steering pump can be realized. With reference to fig. 1-3, the process of establishing the equation of state for the steering pump speed error includes the following:

1. establishing a mathematical model of the permanent magnet slip clutch, wherein the mathematical model comprises a voltage equation, an electromagnetic torque equation and a motion equation:

equation of voltage $\left\{\begin{array}{c}{U}_d-(1-D)U_c=L_d\stackrel{\&CenterDot;}{I_d}+{\mathrm{RI}}_d\\ U_d=k({\mathrm{\&omega;}}_1-{\mathrm{\&omega;}}_2)\\ U_c=\sqrt{L_d/c}{I}_d\end{array}\right.$

Electromagnetic torque equation T_e＝C_mI_d

Equation of motion $T_e-T_L-F_2{\mathrm{\&omega;}}_2=J_2\stackrel{\&CenterDot;}{{\mathrm{\&omega;}}_2}$

Wherein, U_dFor induced electromotive force, k is the induced electromotive force coefficient, D is the duty ratio, U_cIs the voltage at the capacitor terminal, L_dIs an equivalent inductance of an outer rotor rectifying circuit, I_dFor the winding current of the outer rotor rectification loop, R is the equivalent resistance of the outer rotor rectification loop, omega₁、ω₂Mechanical angular velocities of the outer and inner rotors, c is capacitance, T_eIs an electromagnetic torque, C_mIs a torque coefficient, T_LTo load torque, F₂For the damping coefficient of rotation of the inner rotor, J₂Is the moment of inertia of the inner rotor.

2. Define state variable E ═ E₁,e₂]^TI.e. by $\left\{\begin{array}{c}{e}_1={\mathrm{\&omega;}}_2-{\mathrm{\&omega;}}_d\\ e_2=\stackrel{\&CenterDot;}{e_1}=\stackrel{\&CenterDot;}{{\mathrm{\&omega;}}_2}-\stackrel{\&CenterDot;}{{\mathrm{\&omega;}}_d}\end{array}\right..$

Wherein, ω is_dIn order to achieve the desired rotational speed of the steering pump,

3. according to the mathematical model of the permanent magnet slip clutch established above, the state equation of the rotation speed error of the steering pump is deduced as follows:

$\left\{\begin{array}{c}\stackrel{\&CenterDot;}{e_1}=e_2\\ \stackrel{\&CenterDot;}{e_2}=f+gu+d\left(t\right)\end{array}\right.$

wherein, $f=-\frac{C_{m}k+\left(\sqrt{L_d/c}+R\right)F_2}{L_d{J}_2}{\mathrm{\&omega;}}_2-\frac{\left(\sqrt{L_d/c}+R\right)J_2+L_d{F}_2}{L_d{J}_2}\stackrel{\&CenterDot;}{{\mathrm{\&omega;}}_2}+\frac{C_m{\mathrm{k\&omega;}}_1-\left(\sqrt{L_d/c}+R\right)T_L-L_d\stackrel{\&CenterDot;}{T_L}}{L_d{J}_2},$ $g=\frac{\sqrt{L_d/c}(J_2\stackrel{\&CenterDot;}{{\mathrm{\&omega;}}_2}+T_L+F_2{\mathrm{\&omega;}}_2)}{L_d{J}_2},d\left(t\right)=-\stackrel{\&CenterDot;\&CenterDot;}{{\mathrm{\&omega;}}_d},$ u is a control amount.

4. The uncertain factors of parameters in the permanent magnet slip clutch, including parameter perturbation, external interference and the like are considered, and at the momentCan be expressed as:

$\begin{array}{c}\stackrel{\&CenterDot;}{e_2}=(f+\mathrm{\&Delta;}f)+(g+\mathrm{\&Delta;}g)u+d\left(t\right)\\ =f+gu+\left(\mathrm{\&Delta;}f+\mathrm{\&Delta;}gu+d\left(t\right)\right)\end{array}$

where Δ f and Δ g are the uncertainties of the corresponding terms, respectively, and they are bounded. Note g (t) as the total uncertainty, and g (t) Δ f + Δ gu + d (t), the equation of state for the steering pump speed error can be expressed as:

$\left\{\begin{array}{c}\stackrel{\&CenterDot;}{e_1}=e_2\\ \stackrel{\&CenterDot;}{e_2}=f+gu+g\left(t\right)\end{array}\right.$

wherein g (t) is bounded, | g (t) | ≦ l_g，l_gIs the interference upper bound.

Step three, designing a self-adaptive nonsingular terminal sliding mode controller based on the Lyapunov function

In order to realize the mutual coordination of the operation stability, the safety and the energy saving performance of the permanent magnet slip clutch type electric control hydraulic power steering system, the control requirement that the hydraulic system maintains basic pressure when the steering is not performed, the maximum power is provided when the steering is performed on site, and the provided power is gradually reduced along with the increase of the vehicle speed is provided. In addition, in the actual operation process of the heavy vehicle, various uncertain factors and external interference exist, such as engine rotating speed fluctuation, road excitation and the like, aiming at the system, a self-adaptive nonsingular terminal sliding mode control method is provided for carrying out rotating speed control on the permanent magnet slip clutch, the control strategy is shown in figure 4, and the design process of the controller is as follows:

1. according to the established system state equation, selecting a nonsingular terminal sliding mode surface as follows:

$s=e_1+\frac{1}{\mathrm{\&beta;}}{e_2}^{\frac{p}{q}}$

wherein β >0, p and q are positive odd numbers, and 1< p/q < 2.

2. Establishing a nonsingular terminal sliding mode control law by using the nonsingular terminal sliding mode surface, wherein the nonsingular terminal sliding mode control law is as follows:

$u=-\frac{1}{g}(f+\mathrm{\&beta;}\frac{q}{p}{e_2}^{2-\frac{p}{q}}+(l_g+\mathrm{\&eta;}\left)\mathrm{sgn}\right(s\left)\right)$

wherein η > 0.

3. By a_gIs estimated value ofSubstitute for l_gAnd obtaining a self-adaptive nonsingular terminal sliding mode control law as follows:

$u=-\frac{1}{g}(f+\mathrm{\&beta;}\frac{q}{p}{e_2}^{2-\frac{p}{q}}+(\widehat{l_g}+\mathrm{\&eta;}\left)\mathrm{sgn}\right(s\left)\right)$

4. defining the Lyapunov function:

$V=\frac{1}{2}{s}^2+\frac{1}{2m}\widetilde{{l_g}^2}$

wherein,m is an adjustable parameter.

Therefore, the first and second electrodes are formed on the substrate, $\stackrel{\&CenterDot;}{V}=S\stackrel{\&CenterDot;}{S}-\frac{1}{m}\widetilde{l_g}\stackrel{\&CenterDot;}{\widehat{l_g}}=\frac{1}{\mathrm{\&beta;}}\frac{p}{q}{e_2}^{\frac{p}{q}-1}\&lsqb;sg\left(t\right)-\left(\widehat{l_g}+\mathrm{\&eta;}\right)\left|s\right|\&rsqb;-\frac{1}{m}\widetilde{l_g}\stackrel{\&CenterDot;}{\widehat{l_g}}$

5. designing an adaptive law: $\stackrel{\&CenterDot;}{\widehat{l_g}}=m\mathrm{\&epsiv;}\left|s\right|,\mathrm{\&epsiv;}=\frac{1}{\mathrm{\&beta;}}\frac{p}{q}{e_2}^{\frac{p}{q}-1},$ then there is

$\begin{array}{c}\stackrel{\&CenterDot;}{V}=S\stackrel{\&CenterDot;}{S}-\frac{1}{m}\widetilde{l_g}\stackrel{\&CenterDot;}{\widehat{l_g}}=\frac{1}{\mathrm{\&beta;}}\frac{p}{q}{e_2}^{\frac{p}{q}-1}\&lsqb;sg\left(t\right)-\left(\widehat{l_g}+\mathrm{\&eta;}\right)\left|s\right|\&rsqb;-\frac{1}{m}\widetilde{l_g}\stackrel{\&CenterDot;}{\widehat{l_g}}\\ =\frac{1}{\mathrm{\&beta;}}\frac{p}{q}{e_2}^{\frac{p}{q}-1}\&lsqb;sg\left(t\right)-\left(\widehat{l_g}+\mathrm{\&eta;}\right)\left|s\right|\&rsqb;-\frac{1}{\mathrm{\&beta;}}\frac{p}{q}{e_2}^{\frac{p}{q}-1}\widetilde{l_g}\left|s\right|\\ \&le;-\frac{1}{\mathrm{\&beta;}}\frac{p}{q}{e_2}^{\frac{p}{q}-1}\mathrm{\&eta;}\left|s\right|\end{array}$

Because of the fact thatη>0, thenAnd β>0, then(e₂Not equal to 0), push outSo when e₂When the signal is not equal to 0, the signal is transmitted,according to the Lyapunov stability theorem, the closed-loop control system is stable, and the system can converge to zero in a limited time.

Verification method provided by the invention under Simulink simulation environment

The parameters are selected as follows:

k＝0.6，L_d＝0.0003，c＝0.00004，J₂＝0.08，F₂＝0.03，R＝0.5，

β＝1000，p＝9，q＝7，η＝2500

when the steering is performed on the pivot, the steering system needs to provide the maximum power assistance, namely the rotating speed of the steering pump is the highest, and the ideal rotating speed is 600 r/min. As shown in FIG. 5, during pivot steering, the adaptive nonsingular terminal sliding mode control rotating speed tracking error map can be found to be almost converged to zero in a short time error curve. As shown in fig. 6, when the vehicle is steered in situ, the rotating speed control effect of the permanent magnet slip clutch is compared with that of a common slip mode by using the adaptive nonsingular terminal slip mode, and the problems of parameter perturbation and external interference can be solved by using the adaptive nonsingular terminal slip mode control. The ideal rotating speed under other different vehicle speed working conditions is obtained through the designed variable power-assisted characteristic along with the speed, and the rotating speed control effect is similar to that under the pivot steering working condition, and is not listed in the specification.

As shown in FIG. 7, under a certain working condition, the engine speed is maintained at 1300r/min (the ideal speed of the steering pump is 450r/min at this time), but the engine speed fluctuates due to interference in 1.0-1.5s, in this case, as shown in FIG. 8, the adaptive nonsingular terminal sliding mode control can well overcome the external interference, and the control system has good robustness.

The above description is only for the purpose of describing embodiments of the present invention, and is not intended to limit the scope of the present invention, and modifications and variations thereof without departing from the spirit of the present invention are intended to be included within the scope of the present invention.

Claims (6)

1. A permanent-magnet slip clutch is characterized by comprising an outer rotor, an inner rotor and an outer control circuit; the outer rotor is internally embedded with a three-phase winding, the three-phase winding is connected with an outer control circuit through a slip ring and an electric brush, and the inner rotor is pasted with a permanent magnet to form a non-salient pole type inner rotor structure; when the outer rotor rotates, electromagnetic torque is generated between the inner rotor and the outer rotor, and the electromagnetic torque drives the inner rotor to rotate; the outer control circuit is a Boost circuit based on an IGBT and is used for accurately controlling the rotating speed of the inner rotor.

2. The permanent magnet slip clutch of claim 1 wherein said outer rotor serves as an input and is connected to a motor via a drive shaft, said motor rotating said outer rotor; the inner rotor is used as an output end and is connected with the steering pump through a driven shaft, and the inner rotor drives the steering pump to rotate.

3. A permanent magnet slip clutch self-adaptive nonsingular terminal sliding mode rotating speed control method is characterized by comprising the following steps:

step 1, on the basis of a traditional HPS structure, connecting an outer rotor of a permanent magnet slip clutch with an engine through a driving shaft, and connecting an inner rotor with a steering pump through a driven shaft to construct a permanent magnet slip clutch type electric control hydraulic power steering system;

step 2, establishing a state equation of the rotation speed error of the steering pump;

and 3, designing a self-adaptive nonsingular terminal sliding mode controller based on the Lyapunov function.

4. The self-adaptive nonsingular terminal sliding-mode rotating speed control method of the permanent magnet slip clutch according to claim 3, characterized in that an outer control circuit of the permanent magnet slip clutch in the step 1 is a Boost circuit based on an IGBT, and the current of an outer rotor three-phase winding is changed by adjusting the duty ratio of the IGBT, so that the size of electromagnetic torque is changed.

5. The method for controlling the sliding mode rotating speed of the adaptive nonsingular terminal of the permanent magnet slip clutch according to claim 3, wherein the step 2 is realized by the following steps:

step 2-1, establishing a mathematical model of the permanent magnet slip clutch, comprising the following steps:

equation of voltage $\left\{\begin{array}{c}{U}_d-(1-D)U_c=L_d\stackrel{\&CenterDot;}{I_d}+{\mathrm{RI}}_d\\ U_d=k({\mathrm{\&omega;}}_1-{\mathrm{\&omega;}}_2)\\ U_c=\sqrt{L_d/c}{I}_d\end{array}\right.;$

Electromagnetic torque equation T_e＝C_mI_d；

Equation of motion $T_e-T_L-F_2{\mathrm{\&omega;}}_2=J_2\stackrel{\&CenterDot;}{{\mathrm{\&omega;}}_2};$

Wherein, U_dFor induced electromotive force, k is the induced electromotive force coefficient, D is the duty ratio, U_cIs the voltage at the capacitor terminal, L_dIs an equivalent inductance of an outer rotor rectifying circuit, I_dFor the winding current of the outer rotor rectification loop, R is the equivalent resistance of the outer rotor rectification loop, omega₁、ω₂Mechanical angular velocities of the outer and inner rotors, c is capacitance, T_eIs an electromagnetic torque, C_mIs a torque coefficient, T_LTo load torque, F₂For the damping coefficient of rotation of the inner rotor, J₂Is the rotational inertia of the inner rotor;

step 2-2, define the state variable E ═ E₁,e₂]^TI.e. by $\left\{\begin{array}{c}{e}_1={\mathrm{\&omega;}}_2-{\mathrm{\&omega;}}_d\\ e_2=\stackrel{\&CenterDot;}{e_1}=\stackrel{\&CenterDot;}{{\mathrm{\&omega;}}_2}-\stackrel{\&CenterDot;}{{\mathrm{\&omega;}}_d}\end{array}\right.;$ Wherein, ω is_dThe ideal rotating speed of the steering pump;

and 2-3, combining the step 2-1 with the step 2-2 to obtain a state equation of the rotation speed error of the steering pump, wherein the state equation is as follows:

$\left\{\begin{array}{c}\stackrel{\&CenterDot;}{e_1}=e_2\\ \stackrel{\&CenterDot;}{e_2}=f+gu+d\left(t\right)\end{array}\right.$

wherein, $f=-\frac{C_{m}k+(\sqrt{L_d/c}+R)F_2}{L_d{J}_2}{\mathrm{\&omega;}}_2-\frac{(\sqrt{L_d/c}+R)J_2+L_d{F}_2}{L_d{J}_2}\stackrel{\&CenterDot;}{{\mathrm{\&omega;}}_2}+\frac{C_m{\mathrm{k\&omega;}}_1-(\sqrt{L_d/c}+R)T_L-L_d\stackrel{\&CenterDot;}{T_L}}{L_d{J}_2},$ $g=\frac{\sqrt{L_d/c}(J_2\stackrel{\&CenterDot;}{{\mathrm{\&omega;}}_2}+T_L+F_2{\mathrm{\&omega;}}_2)}{L_d{J}_2},d\left(t\right)=-\stackrel{\&CenterDot;\&CenterDot;}{{\mathrm{\&omega;}}_d},$ u is a control amount.

And 2-4, obtaining a state equation of the rotation speed error of the steering pump containing the parameter perturbation and the external interference, wherein the state equation comprises the following steps:

$\left\{\begin{array}{c}\stackrel{\&CenterDot;}{e_1}=e_2\\ \stackrel{\&CenterDot;}{e_2}=f+gu+g\left(t\right)\end{array}\right.$

wherein g (t) is the total uncertainty, g (t) ═ Δ f + Δ gu + d (t), Δ f, Δ g are uncertainty factors, | g (t) | ≦ l_g，l_gIs the interference upper bound.

6. The method for controlling the sliding mode rotating speed of the adaptive nonsingular terminal of the permanent magnet slip clutch according to claim 5, wherein the step 3 is realized by the following steps:

step 3-1, selecting nonsingular terminal sliding mode surfaces according to the state equation established in the step 2 as follows:

β therein>0, p and q are positive odd numbers, and 1<p/q<2；

Step 3-2, establishing a nonsingular terminal sliding mode control law by using the nonsingular terminal sliding mode surface, wherein the nonsingular terminal sliding mode control law is as follows:

$u=-\frac{1}{g}(f+\mathrm{\&beta;}\frac{q}{p}{e_2}^{2-\frac{p}{q}}+(l_g+\mathrm{\&eta;}\left)\mathrm{sgn}\right(s\left)\right);$ η therein>0；

Step 3-3, with l_gIs estimated value ofSubstitute for l_gAnd obtaining a self-adaptive nonsingular terminal sliding mode control law as follows:

$u=-\frac{1}{g}(f+\mathrm{\&beta;}\frac{q}{p}{e_2}^{2-\frac{p}{q}}+(\widehat{l_g}+\mathrm{\&eta;}\left)\mathrm{sgn}\right(s\left)\right);$

step 3-4, defining the Lyapunov function:

$V=\frac{1}{2}{s}^2+\frac{1}{2m}\widetilde{{l_g}^2};$ wherein $\widetilde{l_g}=l_g-\widehat{l_g},$ m is an adjustable parameter greater than 0;

step 3-5, designing an adaptive law:to obtain

$\begin{array}{c}\stackrel{\&CenterDot;}{V}=S\stackrel{\&CenterDot;}{S}-\frac{1}{m}\widetilde{l_g}\stackrel{\&CenterDot;}{\widehat{l_g}}=\frac{1}{\mathrm{\&beta;}}\frac{p}{q}{e_2}^{\frac{p}{q}-1}\&lsqb;sg\left(t\right)-\left(\widehat{l_g}+\mathrm{\&eta;}\right)\left|s\right|\&rsqb;-\frac{1}{m}\widetilde{l_g}\stackrel{\&CenterDot;}{\widehat{l_g}}\\ =\frac{1}{\mathrm{\&beta;}}\frac{p}{q}{e_2}^{\frac{p}{q}-1}\&lsqb;sg\left(t\right)-\left(\widehat{l_g}+\mathrm{\&eta;}\right)\left|s\right|\&rsqb;-\frac{1}{\mathrm{\&beta;}}\frac{p}{q}{e_2}^{\frac{p}{q}-1}\widetilde{l_g}\left|s\right|\\ \&le;-\frac{1}{\mathrm{\&beta;}}\frac{p}{q}{e_2}^{\frac{p}{q}-1}\mathrm{\&eta;}\left|s\right|\end{array}.$