An AC Drive is an electronic device that converts a fixed frequency and voltage to an adjustable frequency and AC voltage source. It controls the speed, torque, horsepower and direction of an AC motor. AC Drive is also a term used for an AC inverter and is sometimes used to describe a particular section of an AC drive. The section uses the DC voltage from a previous circuit stage (DC Bus) to produce an AC current or voltage having the desired frequency. AC Drives are also referred to as Variable Frequency Drives (VFD's) or Adjustable Speed Drives (ASD's). These drives are gaining in popularity due to the energy savings that can be obtained related to the AC technology. In addition, AC motors are simpler than DC and usually an "off-the-shelf" item compared to DC motors. Advances in technology have made the size, cost, reliability and performance of AC drives very appealing in industrial variable speed applications.
AC Drive Advantages
●Versatile - more than motor control, this device has self-diagnostics, current status, multi-use programming ability, and precise speed control
●Energy Savings - reduces peak energy demands by ramping up power drawn from the motor & maximizes energy put through the unit
●Performance - simple operation, fast motor load change response (small set-point for precise operation)
●Reliability - solid-state unit, no external controls
●Size - lighter and smaller than most other methods of speed control
AC Drive Applications
●Conveyors, belts, chains, screws, bulk/packaged material handlers
●Fans, blowers, compressors, pumps
●Machine tools, grinders, lathes, stamping presses
●Custom machines, label makers, bottle washers, wire drawing, textiles, etc.
●Extruders, process machinery, kilns, grinders, blenders, agitators
What are the fundamentals of AC drives?
An AC Drive is an electronic device that converts a fixed frequency and voltage to an adjustable frequency and AC voltage source. It controls the speed, torque, horsepower and direction of an AC motor. AC Drive is also a term used for an AC inverter and is sometimes used to describe a particular section of an AC drive.
What is one of the most important considerations when installing an AC drive?
Correct installation of variable frequency drives demands attention to vital factors such as location and environment, electrical connections grounding, supply voltage, and protective devices. Over 50% of VFD failures are a result of improper installation and start-up.
Products and reference designs of AC drive communication module
Design requirements
AC drive communication modules often require:
●Flexibility to execute a variety of industry standards and proprietary protocols.
●Support for different real-time protocol stacks.
●Low-latency, low-bit-error, EMC immune interfaces.
●High-efficiency, sequenced and supervised voltage rails for reliable operation.
Non-isolated DC/DC power supply
Non-isolated DC/DC power supply is used to generate the various supply rails needed by the system to function. In general it comprises of DC/DC converters and linear regulators. Power supply supervisors are used to monitor the supply health. Complex systems require very specific power-up and power-down sequencing in order to guarantee reliable operation, better efficiency and overall system health. Power supply sequencers are required for this function. Non-isolated DC/DC power supply includes Buck converters (integrated switch)、Linear & low-dropout (LDO) regulators、Multi-channel ICs (PMICs)、Buck modules (integrated inductor)、Supervisor & reset ICs、eFuses & hot swap controllers、Boost converters (integrated switch)、Sequencers, the Corresponding products are LMR50410、TPS745、TPS65219、TPSM82821A、TLV803E、TPS2482、TPS61041、LM3881
Isolated DC/DC interface
Input and output interfaces are often isolated to avoid ground loops. The local power supply requires an isolated DC/DC converter to generate isolated rails for these isolated interfaces. Isolated DC/DC interface includes Isolated DC/DC converters & modules、PWM controllers、Shunt voltage references、Flyback controllers、Transformer drivers, the Corresponding products are LM25019、TL2844B、TLV431A、UCC28740、SN6505B
Wireless interface
In motor drives typical wireless communication protocols are NFC & BLE (for service or maintenance interfaces). Sub-1 GHz is used for long distance communication. Wireless interface includes Low-power 2.4-GHz products、Wi-Fi products、Other wireless products, the Corresponding products are CC2674R10、CC3301、WL1837MOD、RF430CL331H
Board-to-board protection
Either protection steering diodes or TVS is needed to clamp the voltage during an ESD or surge event to avoid damage to electrical circuits behind the protection. Board-to-board protection includes ESD protection diodes, the Corresponding products are TPD4S009、TPD2E007、TPD4S012
Board-to-board interface
Wired signal interfaces like LVDS, RS485, CAN, interface translators or buffer transceivers are important for robust communication between the communication module and the control module. Board-to-board interface includes RS-485 & RS-422 transceivers、LVDS, M-LVDS & PECL ICs、Fixed-direction voltage translators、Inverting buffers & drivers、Direction-controlled voltage translators、Noninverting buffers & drivers, the Corresponding products are THVD1450、SN65LVDT33、SN74LV1T126、SN74AHC1G14、SN74ALVC164245、SN74ACT244
Digital processing
Host processor should support multiple Ethernet and Fieldbus communication protocols. Ethernet/IP, EtherCAT, Profinet, Profibus, PowerLink, Sercos 3 and more, both in master and slave configurations. Digital processing includes Arm-based processors、Arm Cortex-R MCUs, the Corresponding products are AM3352、AM2432
Industrial Ethernet interface
Wired signal interfaces like 10/100 Ethernet or Gigabit Ethernet are important for deterministic, secure and reliable communication between the drive and external systems like PLC, motion controllers or other drives on the factory floor. Many industrial drives need to support multi-protocol Ethernet and meet the IEC61800-3 EMC immunity requirements for robust communication in harsh industrial environment. Industrial Ethernet interface includes Ethernet PHYs, the Corresponding products are DP83867IR、DP83867E
Ethernet protection
Either protection steering diodes or TVS is needed to clamp the voltage during an ESD or surge event to avoid damage to electrical circuits behind the protection. Ethernet protection includes ESD protection diodes, the Corresponding products are TPD4S009、TPD2E007、TPD4S012
Clocking
High timing accuracy is required for real time communication protocols. Running several clock sources for different devices results in phase shift between the clocks, which accumulates over time. This can be avoided by adding a clock distribution network. Clocking includes Oscillators、Clock generators、Clock buffers, the Corresponding products are LMK6C、CDCE913、LMK1C1104、CDCLVC1102
Memory
Double Data Rate (DDR) memory has become more common in electronic systems as they provide faster data transfer and overall higher system performance. Conventional passive bus termination resistance is used for matching DDR termination line impedance to source impedance and thus reduces the amplitude of reflection to 0. ; ;Active DDR termination is used not only to reduce power dissipation (50% at 50% duty cycling,) but also improves data read/write accuracy & integrity. Memory includes Protocol-specific switches & muxes, the Corresponding product is TS3V330
Fieldbus interface
Wired signal interfaces like RS485, CAN or interface translators are important for deterministic, secure and reliable communication between drive and external systems like PLC, motion controllers or other drives on the factory floor. Many industrial drives need to support Fieldbus solutions like Profibus, Modbus, Sercos or vendor specific protocols and need to meet the IEC61800-3 EMC immunity requirements for robust communication in harsh industrial environment. Isolated communication link is sometimes required to prevent ground loops. Fieldbus interface includes RS-485 & RS-422 transceivers、LVDS, M-LVDS & PECL ICs、Isolated CAN transceivers、Digital isolators、Isolated RS-485 transceivers, the Corresponding products are THVD1450、SN65LVDT33、ISO1050、ISO7742、ISO3082
Fieldbus protection
Either protection steering diodes or TVS is needed to clamp the voltage during an ESD or surge event to avoid damage to electrical circuits behind the protection. Fieldbus protection includes ESD protection diodes、LVDS, M-LVDS & PECL ICs, the Corresponding products are TPD4E1U06、SN65LVDT33
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