使用软件大小动作设计是有益的because engineers can efficiently predict which products are suitable for the application at hand. But key considerations (sometimes missed) when selecting a servo amplifier are those of dynamic braking and regenerative resistor braking.
By六是莫拉斯• Regional Motion Engineer
菲尔德克塞勒•区域运动工程师|Yaskawa America Inc.
Design engineers who are running sizing calculations for a servo application should consider dynamic braking as well as regenerative braking requirements when selecting a servomotor and digital amplifier for that design. The terms are sometimes used interchangeably, as both types of braking involve processing regenerative energy.But as we’ll explore, there is a subtle difference between dynamic braking and regenerative braking.
我们还将探索如何利用伺服放大器包括动态制动条款的好处。
什么是动态制动？
If the servo axis suddenly turns off while the servomotor is operating and the axis is running at some non-zero velocity — for example, due to loss of power or an emergency stop triggered by an alarm — the digital servo amplifier can no longer control the servomotor. That means unless there’s some mechanism to prevent coasting, that axis will indeed coast until all of the kinetic energy from the load and its own rotating inertia is expended.
动态制动是通过在伺服电动机端子之间的电阻之间的电阻快速停止旋转伺服电动机。
由于系统中的机械损失通常仅消耗少量能量，因此滑行距离可能很长。这种长的停止距离可以刺激设备损坏和/或人身伤害。
Here, dynamic braking is helpful. It uses the regenerative power produced by the rotating servomotor to brake the servomotor. The servomotor’s kinetic energy converts to electrical energy and is expended as heat (through resistors) to stop the servomotor. In short, dynamic braking is the quick stopping of a spinning servomotor by connecting resistance between the servomotor’s terminals U, V, and W.
With default parameter settings, the digital servo amplifier will apply dynamic braking to stop the servomotor when a Group 1 alarm occurs. The user can modify the setting of this parameter by using Yaskawa’s free SigmaWin+ Version 7 software.
Consider some examples of when the dynamic braking circuit might be activated.
伺服警报：With default parameter settings, the digital servo amplifier will apply dynamic braking to stop the servomotor when a Group 1 alarm occurs. In some cases, users can modify the setting of this parameter by using drive-manufacturer software.
过度旅行：以前向或相反的方向击中过度行程限制开关。
主电源关闭：Turning off the main power supply to the digital servo-amplifier circuit or servomotor.
Shown here are a couple examples of where regeneration is helpful — where gravity and tension come into play.
什么是再生能量？
In a servomotor system under the control of a digital servo amplifier, when the output torque of the servomotor is opposite the direction of the shaft rotation, the motor acts as a generator … and the resulting energy flows back into the drive. The energy returned to the drive is regenerative energy. Three examples of when regeneration occurs during motor operation are decelerating a moving load; lowering a vertical load; and an overdriven nip roll.
Shown here is how Yaskawa’s networkable Sigma-7 Series Servopack digital amplifiers can handle the energy from a backdriven motor.
这导致了下一个问题 - 什么是再生电阻制动？这里，在减速期间再生能量返回到驱动器，因为电动机必须施加与旋转方向相对的扭矩以停止负载。
例如，当在没有配重的情况下降低负载时，重力的力驱动负载，电动机必须施加扭矩与向下旋转方向相对以控制负载。
Shown here is a sample regeneration profile upon axis deceleration.
同样，在过脱辊的辊隙辊的情况下，电动机必须施加与旋转方向相对的扭矩。在这两种情况下，再生能量返回驱动器。每当再生能量返回到数字伺服放大器时，总线电容器都会吸收能量......并且直流母线电压升高。
Of course, if there’s a large amount of energy, the energy must dissipate to protect the drive. A braking transistor turns on to let current flow from the bus through a braking resistor. This process is known as regenerative resistor braking.
Digital servo amplifiers from some manufacturers have built-in resistors to dissipate some regenerative energy … though if the amount of regenerative energy processed by the built-in resistor is exceeded, the design will need an external regenerative resistor.
Word to the wise: Use (full-featured) servo-sizing software
使用来自一些制造商的伺服尺寸软件尺寸运动应用让工程师验证特定于应用的再生和动态制动参数。这里工程师可以输入有关系统力学，运动轮廓和其他细节的详细信息，例如输入电压和伺服电机制动参数。这种软件最终识别将在手头的应用中工作的一个或多个伺服电机和数字伺服放大器组合。一些这样的软件甚至可以返回每台计算机构建选项的速度扭矩曲线和再生值。
点击放大。This example of sizing software (on the Yaskawa SigmaSelect software’s regeneration tab) shows how such tools can identify whether the design will need additional components such as external resistors.
Though no one size fits all, servo systems verified upfront for dynamic braking and regenerative resistor braking will deliver longer life. Yaskawa’s networkable digital amplifiers (Sigma-7 Series Servopacks) include dynamic braking provisions in their amplifiers. For more information, visityaskawa.com/products/motion/sigma-7-servo-products.
Figure 7:When the servomotor operates as a generator, power returns to the amplifier — often to charge the drive’s bus-smoothing capacitor. Beyond this capacitor’s capacity, a regenerative resistor goes into action to consume the remaining power. But where such an approach is still insufficient (or the drive doesn’t have regenerative resistors) an external regenerative resistor must connect to the drive to handle the remaining power. That’s common for axes with high load-to-motor-inertia mismatches. External regenerative resistor units such as the one shown here connect between drive terminals; then software configuration of the amplifier allows identification and handling of the external resistor unit’s power capacity.
提起：运动控制提示,电容器
你好
Thanks for guiding us the concept about dynamic braking and regenerative resistor braking.
我想确认一件事..
Actually , there is only one braking structure (switch circuit and resistor) in driver, right? when servo off , it works as dynamic braking , when servo on and output torque is opposite to the rotating direction, it works as regenerative resistor braking, is it correct?
Thanks