Basic Elements of a Control System11/24/2016There are four basic elements of a typical motion control system. These are the controller, amplifier, actuator, and feedback. The complexity of each of these elements will vary depending on the types of applications for which they are designed and built. Rockwell Automation manufacturers a wide variety of these products under the Allen Bradley brand name.The controller section of the AC drive is the brain if the system. It typically consists of a microprocessor based CPU and memory that is used to process data once it is collected and stored. This controller section of the AC drive will process information received from the inputs of the drive and also from the feedback signals that will usually be a representation of the position or speed of the actuator. The controller will then issue commands to the amplifier section based on this information.The amplifier section of the drive receives the commands from the control section. The amplifier then generates the power signal necessary for the actuator to drive the load with the correct speed and direction. The amplifier section of the AC drive is usually able to be further broken down into three sections of its own. The rectifier circuit, DC circuit, and inverter circuit. Most of the Allen Bradley AC drive repairs that we perform use a rectifier or SCR pre-charge circuit to reduce the instantaneous incoming current at power up, and supply continuous current while in operation. The DC circuit will contain both current and voltage filter components including a choke and parallel bus capacitors and may have some type of regenerative discharge circuitry. The inverter section of the AC drive will typically be comprised of insulated gate bipolar transistors or IGBTs. The switching control for the inverter circuit is provided by the control section of the AC drive. Using the switching control, the DC voltage supplied by the DC circuit, is changed in the inverter circuit to a pulse width modulated output that feeds the actuator of the motion control system.The actuator portion of the system will most often be an induction AC motor or permanent magnet AC motor with windings and insulation that are specially designed to handle the heat and stress generated by a pulse width modulated output.The feedback element of the motion control system may be handled by the system in a number of ways depending on the information needed. Encoders or resolvers can be used to provide feedback signals from the actuator in a closed loop control or hall effect sensors can provide feedback from the output of the AC drive in an open loop control. These feedback signals as previously mentioned will be a representation of the speed or position of the actuator and are used by the control section of the drive to determine what commands to provide to the other sections of the drive. Back To Blog
Basic Elements of a Control System11/24/2016There are four basic elements of a typical motion control system. These are the controller, amplifier, actuator, and feedback. The complexity of each of these elements will vary depending on the types of applications for which they are designed and built. Rockwell Automation manufacturers a wide variety of these products under the Allen Bradley brand name.The controller section of the AC drive is the brain if the system. It typically consists of a microprocessor based CPU and memory that is used to process data once it is collected and stored. This controller section of the AC drive will process information received from the inputs of the drive and also from the feedback signals that will usually be a representation of the position or speed of the actuator. The controller will then issue commands to the amplifier section based on this information.The amplifier section of the drive receives the commands from the control section. The amplifier then generates the power signal necessary for the actuator to drive the load with the correct speed and direction. The amplifier section of the AC drive is usually able to be further broken down into three sections of its own. The rectifier circuit, DC circuit, and inverter circuit. Most of the Allen Bradley AC drive repairs that we perform use a rectifier or SCR pre-charge circuit to reduce the instantaneous incoming current at power up, and supply continuous current while in operation. The DC circuit will contain both current and voltage filter components including a choke and parallel bus capacitors and may have some type of regenerative discharge circuitry. The inverter section of the AC drive will typically be comprised of insulated gate bipolar transistors or IGBTs. The switching control for the inverter circuit is provided by the control section of the AC drive. Using the switching control, the DC voltage supplied by the DC circuit, is changed in the inverter circuit to a pulse width modulated output that feeds the actuator of the motion control system.The actuator portion of the system will most often be an induction AC motor or permanent magnet AC motor with windings and insulation that are specially designed to handle the heat and stress generated by a pulse width modulated output.The feedback element of the motion control system may be handled by the system in a number of ways depending on the information needed. Encoders or resolvers can be used to provide feedback signals from the actuator in a closed loop control or hall effect sensors can provide feedback from the output of the AC drive in an open loop control. These feedback signals as previously mentioned will be a representation of the speed or position of the actuator and are used by the control section of the drive to determine what commands to provide to the other sections of the drive.