The DCSD servo amplifiers developed and manufactured by DARPAMotion Ltd. do not include a rectifier unit, thus the drive’s DC bus connectors can only be powered by a separate power supply module providing filtered direct current. The dimensions of our CPS (power supply) and DCSD (servo amplifier) modules are equal and the connectors are located on their front panels. This way they can be mounted in a row and their wiring can be done easily. The design of the modules allows for simple, modular construction, easy replacement and later expansion. Due to their construction, it is possible to connect the power supply with the servo amplifier modules using a DC rail. The order of the modules can be arbitrary – they can even be sorted into multiple rows.
The CPS power supply’s main job is to power the servo amplifiers. The servo amplifiers require DC voltage on their input. The output of the DC rail provides rectified and controlled voltage from the one or three phase isolating transformer connected to its input. The waveform of the rectified voltage is almost completely smoothed out by the high capacity capacitors located on the DC rail.
The CPS power supply features a soft start system that restricts the magnetization current of the isolating transformer using external ballast resistors. Without soft starting, the overcurrent protection of the power supply would kick in immediately upon power-on. The soft start function switches on/off and charges the capacitors depending on the voltage of the DC rail and the state of the CPS power supply.
The voltage of the DC rail is determined by the rectified voltage of the isolating transformer and the CPS power supply’s internal buck converter (switching voltage regulator). Due to the configuration of the converter, the output voltage is always lower than the rectified voltage of the isolating transformer. The control algorithms used in our power supplies provide fast voltage control on the DC rail with subordinate current control. This allows the DC rail’s output current to be limited and thus protects the isolating transformer.
The power supply generates the output voltage with the help of the built-in buck converter, using pulse width modulation (PWM). The high current switching devices are IGBTs located on the heatsink. Control tasks are performed by a single microprocessor (DSPic). The power supply has a UDP/IP communication channel that is used for data queries (output current, output voltage). Parameter setting is also done on this channel.