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第四周作业

时间:2016-03-21 01:36:05      阅读:281      评论:0      收藏:0      [点我收藏+]

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第四周作业

这周复习了第四章中三相异步电动机的工作原理及其机械特性,以此为依据巩固了三相异步电机的启动、调速及制动。

这周课外比赛的琐事较多,没有额外增加阅读内容。

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仿真作业

基本要求:

结合本周学习的交流电机原理及启动、调速、制动特性,用Modelica设计和仿真一个用三相交流异步电机带动起重机起升机构运行。具体要求如下:

1)实现如下机械运动周期:

  • 控制电机带重物上升,从静止加速到800r/min
  • 保持800r/min匀速运动0.5s
  • 减速到静止,保持静止状态0.5s
  • 带重物下降,从静止达到600r/min
  • 保持600r/min匀速运动0.6s
  • 减速到静止。
    (
    为了便于仿真,匀速和静止持续时间较短)

2) 升降机构和重物折算到到电机转子轴上的等效负载惯量为1Kg.m^2,折算到到电机转子轴上的等效负载转矩是15N.m

3)使用统一的电机模型,如果控制策略中用到转子串电阻,允许将该电机的转子改为绕线式转子(参数不变)。

4)参照教材中给出的交流电机启动、调速和制动方法,设计控制策略,用Modelica实现控制策略并与电机模型实现联合仿真。

5)可以采用定子串电阻、转子串电阻、定子调压、定子调频等手段,但必须具备工程上的可实施性。

6)评价指标:快速启动、制动,冲击转矩和冲击电流小,能耗小,兼顾实施的经济性。

7)方案最佳同学获本周"控制之星"称号。

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仿真过程:

首先调整了负载惯量值,同时,考虑到启动时转矩不能过大,根据书中所述异步电动机固有机械特性,当施加在定子每相绕组上的电压降低时,启动转矩会明显减小,当转子电阻适当增大时,启动转矩会增大,启动时采取降压启动。

制动时,为追求效率,采用反接制动,由于反接制动时电流很大,所以酌情在定子电路中串接附加电阻。

调整转速时,根据

可知转速变化的比率与频率及电压的变化率相同,电机原模型转速1500 r/min,通过调整频率f及电压可以实现调速。

设定速度为800 r/min 时,注意到直接乘系数 800/1500 不能得到最终稳定切合800 r/min 速度的曲线,由于额定转速 ,取系数 800/(1500*0.985),结果曲线良好。但对于反向600 r/min 的速度,调整效果劣于原数值,故直接取系数 600/1500 。

停止部分,由于电机仍受15 N.m 转矩,因此仍需设定一不大的频率及电压值。

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代码如下:

model SACIM "A Simple AC Induction Motor Model"

type Voltage=Real(unit="V");

type Current=Real(unit="A");

type Resistance=Real(unit="Ohm");

type Inductance=Real(unit="H");

type Speed=Real(unit="r/min");

type Torque=Real(unit="N.m");

type Inertia=Real(unit="kg.m^2");

type Frequency=Real(unit="Hz");

type Flux=Real(unit="Wb");

type Angle=Real(unit="rad");

type AngularVelocity=Real(unit="rad/s");

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constant Real Pi = 3.1415926;

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Current i_A"A Phase Current of Stator";

Current i_B"B Phase Current of Stator";

Current i_C"C Phase Current of Stator";

Voltage u_A"A Phase Voltage of Stator";

Voltage u_B"B Phase Voltage of Stator";

Voltage u_C"C Phase Voltage of Stator";

Current i_a"A Phase Current of Rotor";

Current i_b"B Phase Current of Rotor";

Current i_c"C Phase Current of Rotor";

Frequency f_s"Frequency of Stator";

Torque Tm"Torque of the Motor";

Speed n"Speed of the Motor";

Resistance Rs"Stator Resistance";

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Flux Psi_A"A Phase Flux-Linkage of Stator";

Flux Psi_B"B Phase Flux-Linkage of Stator";

Flux Psi_C"C Phase Flux-Linkage of Stator";

Flux Psi_a"a Phase Flux-Linkage of Rotor";

Flux Psi_b"b Phase Flux-Linkage of Rotor";

Flux Psi_c"c Phase Flux-Linkage of Rotor";

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Angle phi"Electrical Angle of Rotor";

Angle phi_m"Mechnical Angle of Rotor";

AngularVelocity w"Angular Velocity of Rotor";

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Torque Tl"Load Torque";

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parameter Resistance Rr = 0.408"Rotor Resistance";

parameter Inductance Ls = 0.00252"Stator Leakage Inductance";

parameter Inductance Lr = 0.00252"Rotor Leakage Inductance";

parameter Inductance Lm = 0.00847"Mutual Inductance";

parameter Frequency f_N = 50"Rated Frequency of Stator";

parameter Voltage u_N = 220"Rated Phase Voltage of Stator";

parameter Real p =2"number of pole pairs";

parameter Inertia Jm = 0.1"Motor Inertia";

parameter Inertia Jl = 1"Load Inertia";

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initial equation

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Psi_A = 0;

Psi_B = 0;

Psi_C = 0;

Psi_a = 0;

Psi_b = 0;

Psi_c = 0;

phi = 0;

w = 0;

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equation

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u_A = Rs * i_A + 1000 * der(Psi_A);

u_B = Rs * i_B + 1000 * der(Psi_B);

u_C = Rs * i_C + 1000 * der(Psi_C);

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0 = Rr * i_a + 1000 * der(Psi_a);

0 = Rr * i_b + 1000 * der(Psi_b);

0 = Rr * i_c + 1000 * der(Psi_c);

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Psi_A = (Lm+Ls)*i_A + (-0.5*Lm)*i_B + (-0.5*Lm)*i_C + (Lm*cos(phi))*i_a + (Lm*cos(phi+2*Pi/3))*i_b + (Lm*cos(phi-2*Pi/3))*i_c;

Psi_B = (-0.5*Lm)*i_A + (Lm+Ls)*i_B + (-0.5*Lm)*i_C + (Lm*cos(phi-2*Pi/3))*i_a + (Lm*cos(phi))*i_b + (Lm*cos(phi+2*Pi/3))*i_c;

Psi_C = (-0.5*Lm)*i_A + (-0.5*Lm)*i_B + (Lm+Ls)*i_C + (Lm*cos(phi+2*Pi/3))*i_a + (Lm*cos(phi-2*Pi/3))*i_b + (Lm*cos(phi))*i_c;

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Psi_a = (Lm*cos(phi))*i_A + (Lm*cos(phi-2*Pi/3))*i_B + (Lm*cos(phi+2*Pi/3))*i_C + (Lm+Lr)*i_a + (-0.5*Lm)*i_b + (-0.5*Lm)*i_c;

Psi_b = (Lm*cos(phi+2*Pi/3))*i_A + (Lm*cos(phi))*i_B + (Lm*cos(phi-2*Pi/3))*i_C + (-0.5*Lm)*i_a + (Lm+Lr)*i_b + (-0.5*Lm)*i_c;

Psi_c = (Lm*cos(phi-2*Pi/3))*i_A + (Lm*cos(phi+2*Pi/3))*i_B + (Lm*cos(phi))*i_C + (-0.5*Lm)*i_a + (-0.5*Lm)*i_b + (Lm+Lr)*i_c;

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Tm =-p*Lm*((i_A*i_a+i_B*i_b+i_C*i_c)*sin(phi)+(i_A*i_b+i_B*i_c+i_C*i_a)*sin(phi+2*Pi/3)+(i_A*i_c+i_B*i_a+i_C*i_b)*sin(phi-2*Pi/3));

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w = 1000 * der(phi_m);

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phi_m = phi/p;

n= w*60/(2*Pi);

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Tm-Tl = (Jm+Jl) * 1000 * der(w);

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if time <= 100 then

u_A = 0;

u_B = 0;

u_C = 0;

f_s = 0;

Tl = 0;

Rs = 0.531;

else

if time <= 200 then

f_s = f_N * 800/(1500 * 0.985);

u_A = u_N * 1.414 * sin(2*Pi*f_s*time/1000) * 800/(1500 * 0.985) * 0.85;

u_B = u_N * 1.414 * sin(2*Pi*f_s*time/1000-2*Pi/3) * 800/(1500 * 0.985) * 0.85;

u_C = u_N * 1.414 * sin(2*Pi*f_s*time/1000-4*Pi/3) * 800/(1500 * 0.985) * 0.85;

Tl = 15;

Rs = 0.531;

else

if time <= 1850 then

f_s = f_N * 800/(1500 * 0.985);

u_A = u_N * 1.414 * sin(2*Pi*f_s*time/1000) * 800/(1500 * 0.985);

u_B = u_N * 1.414 * sin(2*Pi*f_s*time/1000-2*Pi/3) * 800/(1500 * 0.985);

u_C = u_N * 1.414 * sin(2*Pi*f_s*time/1000-4*Pi/3) * 800/(1500 * 0.985);

Tl = 15;

Rs = 0.531;

else

if time <= 4300 then

f_s = f_N;

u_A = u_N * 1.414 * sin(2*Pi*f_s*time/1000-4*Pi/3);

u_B = u_N * 1.414 * sin(2*Pi*f_s*time/1000-2*Pi/3);

u_C = u_N * 1.414 * sin(2*Pi*f_s*time/1000);

Tl = 15;

Rs = 2.531;

else

if time <= 4800 then

f_s = f_N * 0.0705;

u_A = u_N * 1.414 * sin(2*Pi*f_s*time/1000) * 0.0705;

u_B = u_N * 1.414 * sin(2*Pi*f_s*time/1000-2*Pi/3) * 0.0705;

u_C = u_N * 1.414 * sin(2*Pi*f_s*time/1000-4*Pi/3) * 0.0705;

Tl = 15;

Rs = 0.531;

else

if time <= 4900 then

f_s = f_N * 600/1500;

u_A = u_N * 1.414 * sin(2*Pi*f_s*time/1000-4*Pi/3) * 600/1500 * 0.85;

u_B = u_N * 1.414 * sin(2*Pi*f_s*time/1000-2*Pi/3) * 600/1500 * 0.85;

u_C = u_N * 1.414 * sin(2*Pi*f_s*time/1000) * 600/1500 * 0.85;

Tl = 15;

Rs = 0.531;

else

if time <= 6450 then

f_s = f_N * 600/1500;

u_A = u_N * 1.414 * sin(2*Pi*f_s*time/1000-4*Pi/3) * 600/1500 ;

u_B = u_N * 1.414 * sin(2*Pi*f_s*time/1000-2*Pi/3) * 600/1500 ;

u_C = u_N * 1.414 * sin(2*Pi*f_s*time/1000) * 600/1500;

Tl = 15;

Rs = 0.531;

else

if time <= 9150 then

f_s = f_N;

u_A = u_N * 1.414 * sin(2*Pi*f_s*time/1000);

u_B = u_N * 1.414 * sin(2*Pi*f_s*time/1000-2*Pi/3);

u_C = u_N * 1.414 * sin(2*Pi*f_s*time/1000-4*Pi/3);

Tl = 15;

Rs = 1.531;

else

f_s = f_N * 0.0705;

u_A = u_N * 1.414 * sin(2*Pi*f_s*time/1000) * 0.0705;

u_B = u_N * 1.414 * sin(2*Pi*f_s*time/1000-2*Pi/3) * 0.0705;

u_C = u_N * 1.414 * sin(2*Pi*f_s*time/1000-4*Pi/3) * 0.0705;

Tl = 15;

Rs = 0.531;

end if;

end if;

end if;

end if;

end if;

end if;

end if;

end if;

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end SACIM;

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simulate(SACIM,startTime=0,stopTime=10000)

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plot(n)

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plot(Tm)

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结果图如下:

技术分享

技术分享

第四周作业

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原文地址:http://www.cnblogs.com/christiana/p/5300426.html

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