设计直流脉宽调速电动机系统的机械特性

1、1.1直流电动机pwm控制系统原理。pwm控制技术一直 是变频技术的核心技术之一。它通过分辨率计数器的使 用，方波的占空比被调制用来对一个具体模拟信号的电平 进行编码。principle of de motor PWM control system. PWM control technology has been one of the core technologyof frequency conversion technology. It through the use of resolution counter, the square wave duty ratio is modulate

2、d to encode a specific analog signal level.直流电动机pwm控制系统有可逆和不可逆系统之分。可 逆系统是指电动机可以正反两个方向旋转； 不可逆系统是 指电动机只能单方向旋转。 对于可逆系统，又可分为单极 性驱动和双极性驱动两种方式。这里只研究双极性驱动。Dc motor PWM control system can be reversible and irreversible systems. Reversible system is refers to the motor can be positive and negative two direct

3、ion; Irreversible system refers to the motor can only single direction. For reversible system and can be divided into single polar driving and double polar driving in two ways. Here only the bipolar drive.h型双极性可逆pwm驱动系统控制原理。h”型是双极性驱动电路的一种， 也称为桥式电路。如图1所示。其电路是由四个开关管和四个续流二极管组成，单电源供电。 四个开关管分为两组，v1和v4为一组

4、，v2和v3为另一 组。同一组的开关管同步导通或关断，不同组的开关管的导通和关断正好相反。h bipolar reversible PWM drive system control theory. H type is one of the bipolar drive circuit, also known as the bridge circuit. As shown in figure 1. The circuit is made up of four switch tube and four of the fly-wheel diode, single power supply. Four

5、 switch tube is divided into two groups, v1 and v4 as a group, v2 and v3 for another group. The same set of synchronous conduction or shut off the switch tube, different group of conduction and shut off the switch tube of just the opposite.在每个pwm周期里，当控制信号vi1高电平时，开关管v1和v4导通，此时vi2为低电平，因此 v2和v3截止。 电枢绕组

6、承受从a到b的正向电压；当控制信号vi1为低 电平时，开关管v1和v4截止，此时vi2为高电平，因此 v2和v3导通，电枢绕组承受从b到a的反向电压，这就 是所谓的“双极”In each PWM cycle, when the control signal vi1 high electricity at ordinary times, switch tube v1 and v4 conduction, vi2 at this time for the low level, therefore the v2 and v3. The armature winding under the posit

7、ive voltage from a to b; Vi1 when the control signal for low electricity at ordinary times, switch tube v1 and v4 as, vi2 for high level right now, so the v2 and v3 conduction, armature winding inherit from b to a reverse voltage, this is the so-called bipolar.可见，双极性可逆pwm驱动时，电枢绕组所承受的平均电压取决于占空比a大小。当a

8、 =0时，u0=-us，电动机反 转，且转速最大；当a =1时，u0=us，电动机正转，转速 最大；当 时,a = 1/2时u0=0 ,电动机不转，但电枢绕组 中仍然有交变电流流动，使电动机产生高频振荡，这种振荡有利于克服电动机负载的静摩擦，提高动态性能。Visible, bipolar reversible PWM driver, the armature winding of the average voltage depends on the size of duty ratio alpha. When alpha = 0 u0 = - us, motor reversal, and t

9、he maximum speed; U0 when alpha = 1 =us, motor is turned, the maximum speed; When, when alpha = 1/2 u0 = 0, motor does not turn, but there is still a alternating current in the armature winding flow, make the motor produces high frequency oscillation, theoscillation is beneficial to overcome the mot

10、or load static friction, improve the dynamic performance.2调速系统的设计2 speed control system design对于一个控制系统而言，最关键的是控制器的设计，控制器设计的好坏关系到控制系统性能的优劣。控制器要求实时性强，通用性强，具有较强的智能，在满足性能指标的 前提下应尽可能的简单。For a control system, the key is the design of controller, the controller design is good or bad is related to the merit

11、s of the control system performance. Controller requires strong real-time performance, strong commonality, strong intelligence, in meet the under the premise of performance indicators should be as simple as possible.pi控制器相当于在系统中增加了一个位于原点的开环极 点，同时也增加了一个位于s左半平面的开环零点。位于原点的极点可以提高系统的型别，以消除或提高系统的稳 态误差，改善系

12、统的稳态性能。而增加酿酒设备的负实零点则用来提高系统的阻尼度，缓和pi控制器极点对系统稳定性产生的不利影响。只要积分时间常数ti足够大，pi控制器对系统稳定性的不利影响可大为减弱。在控制系统中，pi控制器主要用于改善控制系统的稳态性能2。PI controller is equivalent to in the system adds an open-loop poles are located at the origin, but also added a in s left half plane of the open-loop zeros. Pole can improve the sy

13、stem of the origin, in order to eliminate or improve the steady-state error of the system, improve the steady-state performance of the system. And increase the negative real zero is used to improve the system damping, moderate PI controller poles have adverse effects on system stability. As long as

14、the integral time constant ti is large enough, the negative impact of the PI controller on the system stability can be greatly reduced. In the control system, control system of PI controller is mainly used to improve the steady state performance 2.闭环调速系统的转速和电流调节器都米用pi调节器。米用pi调节器的自动控制系统。Closed loop s

15、peed regulation system of speed and current regulator USES PI regulator. Automatic control system of PI regulator.从传递函数看，自动调节系统为：From the transfer function of automatic regulatingsystem for:=wp1 (s) =kp kp+ B(2)S = wp1 KP KP + s = s (s) = (2)u1可分成比例部分ulp，和积分部分uli，其中，比例部 分和偏差成正比积分部分同偏差的积分有关，把两部分加起来，就

16、是调节器的输出信号 u1。U1 u1p proportion can be divided into parts, and integral part of u1i, among them, the proportion is proportional to the deviation integral parts associated with deviation integral, add two parts together, is the controller output signal u1.当偏差信号&是阶跃信号时，比例部分会突然加大，而积 分部分则按线性增长，经过一定时间后，u1

17、输出达到限幅值。而实际系统中，偏差信号&只是一开始突跳，随着 输出信号use的增长，偏差信号&便逐渐降低，u1是否能 够升到限幅值，就要看u1的增长和&的衰减哪一方更快。如果调节对象的时间常数远大于调节器的时间常数，则& 下降较慢，由于调节器的积分作用，海吉布尽管在下降， u1仍继续增长，在&衰减到零以前 u1还来得及升到限幅 值3。如果调节对象的时间常数较小，则&衰减较快，当 积分量还来不及把u1抬高到限幅值以前，&已经衰减到零，u1也就不能再增长，这时积分器不会饱和。When epsilon zero deviation signal is step signal, proportiona

18、l part will suddenly increase, while integral part according to the linear growth, after a certain time, the product output reaches limit values. And practical system, the deviation signal relay, epsilon is just the beginning, as the growth of the output signal of usc, epsilon zero deviation signal

19、will reduce gradually, u1 can rise to the limiting value, depends on the growth of u1 and epsilon attenuation which one is faster. If time constant of regulating object than controller time constant, the slower the epsilon is reduced, due to the effect of integration of the regulator, in spite of th

20、e drop, u1 is still continue to grow, before the epsilon decay to zero u1 still can rise to the limiting value 3. If the adjusting object smaller time constant, the epsilon decay quickly, when the product component could u1 before pushing up to the limiting value, epsilon has decay to zero, u1 also

21、cant again growth, the integrator will not saturated.在动态过程中，pi调节器输出电压u1是否饱和对系统的 输出波形很有影响。若u1 一旦饱和，只有&变负，即use usr时，才有可能使它退出饱和，因此必然超凋。In the process of dynamic, PI regulator output voltage u1 is saturated output waveform has influence on the system. If u1 once saturated, only epsilon becomes negative,

22、 namely the usc usr, is likely to make it out of saturation, therefore the depth.3直流脉宽调速系统的机械特性The mechanical properties of 3 dc pulse width speed regulation system由于采用了脉宽调制，严格地说，即使在稳态情况下，脉宽调速系统的转矩和转速也都是脉动的4。所谓稳态，是指电动机的平均电磁转矩和负载转矩相平衡的状态，机械特性是平均转速和平均转矩(电流)的关系。With pulse width modulation, strictly spe

23、aking, even under steady state conditions, pulse width speed regulation system of pulsation of torque and rotational speed are also 4. Steady state, refers to the average electromagnetic torque and load torque of motor phase equilibrium condition, mechanical characteristics is the average speed and average torque (current).采用不同形式的pwm变换器，系统的机械特性也不一样。对于双极式控制的可逆电路， 电流的方向是可逆的， 无论 是重载还是轻载，电流波形都是连续的，因而机械特性关系式比较简单。Using different forms of PWM converter, mechanical properties of the system is also different. For bipolar reversible type control circuit, the current direction is revers