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How motor control can be achieved "to power the motor at the right time"?

Views: 165     Author: Site Editor     Publish Time: 2022-08-03      Origin: Site

电机控制如何实现在“对的时间供电给电机”

电机,无论其类型如何,都需匹配某种类型的控制器,这些控制器的特性和复杂性可能有所不同,这主要取决于特定电机的功能。电机控制机构最简单的例子是一个将电机与其电源相连的常规开关,此开关可以是手动控制器,也可以是连接到自动传感器的继电器,用于启动和停止电机。 

 

控制电路设计的准备

面对”对的时间”之前,还有一项“送电”的事前工作需准备,也就是需要确定驱动电路。它所担任的角色是如何设计可控制的供电系统,它需要具以下信息,以确保可线路板设计和散热设计,电子元器件等硬件满足系统需要。


供电能力大小,需与电机的规格相匹配。接收控制命令操作,需与控制器搭配。电源传输效率,信号及电源可正常传输,不受到其他信号或电磁波干扰。系统置于操作环境下,是否可以正常运作。安全防护能力。 

 

有了完善的驱动电路后,才能确定“对的时间”,虽然使用时间是名词,但其真正表示的意思为“位置”,即为电机转子的旋转的相对位置,或可称为角度。

Τ=1/2π·I·L·D^2·N·Sin(δ)

以上方程式为电机转矩公式,其中Sin(δ)表示电机的电流与磁场的夹角,当Sin(90°) =1为最大值,Sin(0°)=0为最小值,在”对的夹角位置“输送”电流“给电机,才可达到最佳的输出效果。

 

如何做到“对的时间”

要做到”对的时间”,第一关是获得电机转子正确的位置,即需依赖位置传感器的运用。然而位置判断会受到传感器解析度、安裝位置、信号处理、资料传输、编程计算等产生误差的现象,其可能原因分析如下:

分辨率度不足会导致传感器无法直接标示出该送电的位置点,需要再经由信号处理的技巧间接求得。若具备有充分解析度的传感器,则无须担心安裝问题,反之若安裝位置偏差亦无法直接标示正确位置点。传感器所提供的为电子信号,使用上是以观察电压位准变化来判断位置变化,然而所有电压位准的变化,事实上都是依赖电流传输來达成的。传感器电路中,常加入电容來进行滤波及稳压等工作,稳定电压位准,但亦会影响电流工作时间,使电压位准需要较长的变化时间,产生延迟的现象。经由传感器所获得之电子信号,需传输至控制器方可使用,然后,在控制电路板上会具有电容及电感元件,影响电子信号进入控制器的时间。位置信号进入控制器后,可能还需要经过运算或是处理,或是要等其它程序先跑完等因素,导致无法立即性对位置信号做出反应。

 

以上列出几项较常见之发生原因作为参考,获得正确的位置信息后,则要送入”电流”进入电机,需注意”对的时间”是指电流进入电机运作的时间,电机可视为电感性元件,会导致电流进入电机的时间大幅延后。事实上,电机內的电感值,会受到流入电流大小及电源切换频率(转速)而改变,因此在不同的转速下,电流延迟时间亦会产生变化。

 

另外也要注意从控制器接收位置信号,到处理完成输出控制命令的所需时间,还有开关元件的响应时间及频宽问题,都有可能导致送入电流的时间受到影响。

 

如何做到好的驱动

确保信号的传速速率:信号的延迟已为必然的結果,但若延迟的速率为固定且已知,则可由硬体或是软件方式去补偿;由于方程式中的计算函数为Sin(δ),故差异角度不大,则其计算值仍非常接近1,影响并不大。能有效地确保信号传速,则需依靠电路设计之能力,包括各项电子元件的选配、电源能量配置及电路布线规划等等。

 

软件编程能力:电机驱动程式对于控制器的负担并不大,但控制器同时需处理许多工作,因此权重、顺序及注意掌握运算的时间。若选择高階的控制器,其运算反应速度快,不需要担心彼此拖累时间的問題。对于低階的控制器,则连程式编译需注意,可能需要直接使用组合语言撰写程式码,以达到最短的程式执行时间。

 

电机系统整体理解性:做电机驱动仍需对电机要有深刻性的理解,目前电子电路系統大多是针对电压信号作控制及处理,一来电流值并不大,二来考虑电流产生的损失及电磁波影响。电机系统中,电流才是转矩力量的直接來源,观察电流的变化重要性远远超过电压。电机內的电感及产生的电磁波都远大于电子电路系统,若考虑不适当,很有可能反灌至驱动电路中直接造成不良影响。再者,电机所处的使用环境较为严苛,若要将电路直接置于电机內部时,需特別注意。

 

结论

根据电机的应用,控制器可以提供不同的功能,它们有助于电机在低电压条件下启动,允许多种速度或反向控制操作,防止过电流和过载故障,并执行各种其他功能。一些复杂的电机控制装置也有助于有效控制电机的速度和扭矩,也可能是负责电机驱动机器精确定位的闭环控制系统的一部分。

 



How motor control can be achieved "to power the motor at the right time"?

Motors, regardless of their type, are matched with some type of controller, which can vary in characteristics and complexity, depending on the capabilities of the particular motor. The simplest example of a motor control mechanism is a conventional switch that connects the motor to its power source. This switch can be a manual controller or a relay connected to an automatic sensor to start and stop the motor.

Preparation of control circuit design

Before facing the "right time", there is still a pre-work of "power transmission" that needs to be prepared, that is, the drive circuit needs to be determined. Its role is how to design a controllable power supply system. It needs the following information to ensure that the circuit board design and heat dissipation design, electronic components and other hardware meet the system needs.


The power supply capacity needs to match the specifications of the motor. To receive control commands to operate, it needs to be matched with the controller. Power transmission efficiency, signals and power can be transmitted normally without interference from other signals or electromagnetic waves. Whether the system can operate normally under the operating environment. security protection capability.

With a perfect drive circuit, the "right time" can be determined. Although the use of time is a noun, its real meaning is "position", that is, the relative position of the rotation of the motor rotor, or it can be called an angle.


Τ=1/2π·I·L·D^2·N·Sin(δ)


The above equation is the motor torque formula, where Sin(δ) represents the angle between the current of the motor and the magnetic field, when Sin(90°)=1 is the maximum value, and Sin(0°)=0 is the minimum value. The angle position "transmits "current" to the motor to achieve the best output effect.



How to do the "right time"

To achieve the "right time", the first step is to obtain the correct position of the motor rotor, which requires the use of position sensors. However, position judgment will be affected by the phenomenon of sensor resolution, installation position, signal processing, data transmission, programming calculation, etc., and the possible reasons are analyzed as follows:


Insufficient resolution will cause the sensor to be unable to directly mark the position of the power transmission, which needs to be obtained indirectly through signal processing techniques. If there is a sensor with sufficient resolution, there is no need to worry about the installation problem. On the contrary, if the installation position is deviated, the correct position cannot be directly marked. The sensor provides an electronic signal, which is used to judge the position change by observing the voltage level change. However, all voltage level changes are actually achieved by current transmission. In the sensor circuit, capacitors are often added for filtering and voltage regulation to stabilize the voltage level, but it will also affect the current working time, so that the voltage level needs a long time to change, resulting in a delay. The electronic signal obtained by the sensor needs to be transmitted to the controller before it can be used. Then, there will be capacitive and inductive elements on the control circuit board, which will affect the time when the electronic signal enters the controller. After the position signal enters the controller, it may still need to be calculated or processed, or wait for other programs to run first, which makes it impossible to respond to the position signal immediately.

The most common causes are listed above as a reference. After obtaining the correct position information, the "current" must be fed into the motor. It should be noted that the "correct time" refers to the time when the current enters the motor. The motor can be regarded as Inductive components, which can cause a significant delay in the time when the current enters the motor. In fact, the inductance value in the motor will be changed by the size of the inflow current and the switching frequency (speed) of the power supply. Therefore, the current delay time will also change at different speeds.


In addition, pay attention to the time required from receiving the position signal from the controller to processing the output control command, as well as the response time and bandwidth of the switching element, which may affect the time to send the current.


How to be a good driver

Ensure the speed of the signal: the delay of the signal is an inevitable result, but if the delay rate is fixed and known, it can be compensated by hardware or software; since the calculation function in the equation is Sin(δ), Therefore, if the difference angle is not large, the calculated value is still very close to 1, and the influence is not large. To effectively ensure the speed of signal transmission, it depends on the ability of circuit design, including the selection of various electronic components, power supply energy configuration and circuit wiring planning.


Software programming ability: The motor driver does not have a large burden on the controller, but the controller needs to handle a lot of work at the same time, so the weight, sequence and the time to master the operation should be paid attention to. If you choose a high-level controller, its operation response speed is fast, and you don't need to worry about the problem of dragging each other's time. For low-level controllers, it is necessary to pay attention to the continuous program compilation, and it may be necessary to directly use the assembly language to write the code to achieve the shortest program execution time.


The overall understanding of the motor system: It is still necessary to have a deep understanding of the motor to drive the motor. At present, most electronic circuit systems are controlled and processed for the voltage signal. First, the current value is not large, and secondly, the loss caused by the current and the loss of the current are considered. effects of electromagnetic waves. In the motor system, the current is the direct source of the torque force, and the importance of observing the change of the current is far more important than the voltage. The inductance in the motor and the electromagnetic waves generated are much larger than the electronic circuit system. If it is not considered properly, it is very likely that the back-feeding will directly cause adverse effects in the driving circuit. Furthermore, the use environment of the motor is relatively harsh, and special attention should be paid when placing the circuit directly inside the motor.


Conclusion

Depending on the application of the motor, the controllers can provide different functions, they help the motor start under low voltage conditions, allow multiple speed or reverse control operations, prevent overcurrent and overload faults, and perform various other functions. Some sophisticated motor control devices also help to effectively control the speed and torque of the motor, and may also be part of a closed-loop control system responsible for precise positioning of the motor-driven machine.