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。
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。
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。
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");
constant Real Pi = 3.1415926;
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";
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";
Angle phi"Electrical Angle of Rotor";
Angle phi_m"Mechnical Angle of Rotor";
AngularVelocity w"Angular Velocity of Rotor";
Torque Tl"Load Torque";
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";
initial equation
Psi_A = 0;
Psi_B = 0;
Psi_C = 0;
Psi_a = 0;
Psi_b = 0;
Psi_c = 0;
phi = 0;
w = 0;
equation
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);
0 = Rr * i_a + 1000 * der(Psi_a);
0 = Rr * i_b + 1000 * der(Psi_b);
0 = Rr * i_c + 1000 * der(Psi_c);
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;
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;
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));
w = 1000 * der(phi_m);
phi_m = phi/p;
n= w*60/(2*Pi);
Tm-Tl = (Jm+Jl) * 1000 * der(w);
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;
end SACIM;
simulate(SACIM,startTime=0,stopTime=10000)
plot(n)
plot(Tm)
结果图如下：
