电流控制器实现成了 PI 控制器，具有 P 增益和积分时间参数，两个参数可以独立设置。P 和 I 分量还可以停用（纯 P 控制器或纯 I 控制器）。实际电流值使用三相侧的电流互感器来感测，并通过一个负载电阻和模数转换之后的整流馈送给电流控制器。额定电流的分辨率是 10 位。限流输出用于电流设定值。

电流控制器输出会把触发角传输给选通装置 - 预控制功能同时有效。

 电流控制环上的预控制可以提高闭环控制的动态性能。这允许在电流控制环上有 6 到 9ms 的上升时间。预控制的有效性取决于电流设定值和电机的 EMF，确保了（对于间歇和连续电流或当转矩方向反向时）所需的触发角能够作为设定值快速的传输给选通装置。 

选通装置为与线路供电电压同步的电源部分晶闸管生成触发脉冲。同步与速度和电子器件供电无关，在电源部分感测。触发脉冲的时序由电流控制器和预控制的输出值限定。可以用参数设置触发角度限制。

在 45 到 65 Hz 频率范围上，选通装置会自动适应实际工频。

Globalization and incessantly increasing competitive pressures are forcing companies to continuously increase productivity and shorten product time to market. To this end, it is necessary to continuously optimize engineering procedures and the process, and to simultaneously consider new industrial requirements and directives.

Today, many systems and plants must be expanded and modernized to ensure that companies can continue to provide products meeting market requirements. However, since the installed basis of hardware, application software and know-how of the operating and maintenance engineers represents an enormous value, the safeguarding of investments for companies operating the plants is always assigned a high priority during all modernization plans.

Experience has shown that the success of migration is largely determined by providing a technical solution that optimally matches the customer requirements and the customer’s plant. Minimization of the technical and financial risks together with safeguarding of investments for as long a period as possible are always fundamental aspects. The different lifecycles of the various system components must also be considered, which currently vary from 5 years for PC-based workstations, 15 years for controllers, up to 25 years or more for input/output components and wiring. Therefore Siemens does not consider its task to simply be the complete replacement of an existing system, but in close collaboration together with customers and their system integrators of an individual, future-oriented solution based on the state-of-the-art SIMATIC PCS 7 process control system - always under the directives:

Step-by-step system innovation

Adaptable to the specific conditions of the plant

Flexible according to production requirements