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Inverter is capable to smoothly starting AC motors (ramp from 0 up to 100% of the load) as well as the energy saving will be achieved, accordingly. Also may I confirmed that frequency inverter also acting as AC Motor starting means among (Star/Delta, Soft Starter, Auto Transformer, Electrolyte, series resistance - wound rotor- etc,). The starting factor of frequency inverter is usually 1 up to 1.2 with respect to the rated load current while for Direct On line about 5-6.
Moreover and as you know the inverter can control the speed of the AC motors in accordance to the formula N=120f/P rpm
where f = the supply frequency and P = number of the Poles.
According to this formula, Motor Speed can be changed either by changing/control the frequency or by changing the number of Poles of the Motor by which step changed in the RPM will be given, while the former gives continuous variable speed as per application demand.
However, as per newly developed power Semi Conductor IGCT based on PWM frequency inverter became the most smart, effective and efficient control device in Industries since is associated also with protective and monitoring means.
Moreover and as you know the inverter can control the speed of the AC motors in accordance to the formula N=120f/P rpm
where f = the supply frequency and P = number of the Poles.
According to this formula, Motor Speed can be changed either by changing/control the frequency or by changing the number of Poles of the Motor by which step changed in the RPM will be given, while the former gives continuous variable speed as per application demand.
However, as per newly developed power Semi Conductor IGCT based on PWM frequency inverter became the most smart, effective and efficient control device in Industries since is associated also with protective and monitoring means.
I started more than 20 years ago using Simulation software connected to PLC's to "Emulate" a system in real-time and use it to verify the PLC code and electro-mechanical design of automation systems used in the manufacturing industry.
Since that time, the term 'Emulation for Logic Validation', also referred to as "Virtual Commissioning", has been to used to differentiate between Simulation and Emulation.
Although a simulation and an Emulation may look to all intents and purposes the same, and may be built largely with the same building blocks or models, there are significant differences in usage and operation.
Simulation models are used to test and develop different solutions in order to arrive at a best solution, based on an accepted set of pre-defined metrics.
Emulation models are not used for experimentation in the same way that simulation models are; they are unsuited to this function as they often execute only in real time.
Since that time, the term 'Emulation for Logic Validation', also referred to as "Virtual Commissioning", has been to used to differentiate between Simulation and Emulation.
Although a simulation and an Emulation may look to all intents and purposes the same, and may be built largely with the same building blocks or models, there are significant differences in usage and operation.
Simulation models are used to test and develop different solutions in order to arrive at a best solution, based on an accepted set of pre-defined metrics.
Emulation models are not used for experimentation in the same way that simulation models are; they are unsuited to this function as they often execute only in real time.
Tags: Simulation, Definition
IGBT die are most commonly designed without an integral (monolithic) anti-parallel diode because they can be better optimized for particular forward parameters that way. Separate antiparallel diode die can then co-packaged for topologies that require it. This makes it easier to fully optimize the forward and reverse characteristics of the compound device. The disadvantage is that the co-packaging takes-up some extra room, and the wirebonds add a small amount of parasitic inductance. But co-packaged IGBTs like this are still the dominant devices used in motor drives and other inverter applications. One additional benefit of IGBTs is that they can be designed to survive a direct short-circuit across the bus, for several microseconds (Short Circuit SOA capability), versus Superjunction FETs do not have this capability.
Superjunction FETs on the other hand have a parasitic body diode (like all vertical FETs), whether you like it or not. The advantage of the superjunction process is that it can produce a very low ON resistance at high voltage using less silicon area than other methods. However, the big disadvantage of superjunction is that the body diode dynamic performance is poor. Even with special doping and irradiation - it might get a little better, but it is in a completely different league compared to an optimized fast diode or SiC Schottky.
Superjunction FETs on the other hand have a parasitic body diode (like all vertical FETs), whether you like it or not. The advantage of the superjunction process is that it can produce a very low ON resistance at high voltage using less silicon area than other methods. However, the big disadvantage of superjunction is that the body diode dynamic performance is poor. Even with special doping and irradiation - it might get a little better, but it is in a completely different league compared to an optimized fast diode or SiC Schottky.
Tags: Definition, inverter
Power factor is a measurement of reactive power. Reactive power is the VA used to establish the magnetic field in a motor. For permanent magnet motor, most time you see power factor being unity, which means all VAs are used to generate torque (minus the loss, of course). Under the condition of field weakening operation though, you will see the PM motor gets less than unity power factor because some VAs are used to counter the perm magnet field. In induction motor, the power factor indicates the portion of VAs used to generate the field comparing to the VAs that generate torque (and loss), which is related to the v/hz in scalar controller or Id in vector control. So under light load condition, you can improve the power factor of an induction motor by lowering the field a bit.
The motor power factor does not make a big difference other than giving an idea of loading. In regards to the inverter fixing power factor everyone is mostly correct. An inverter will always show a DPF (Displacement Power Factor) near unity. DPF is what a utility company traditionally monitors and is the measure of lag looking at current and voltage of power at 60hz or fundamental only. The true power factor on an frequency inverter will change with loading etc and includes current and voltage inclusive of harmonics.
The motor power factor does not make a big difference other than giving an idea of loading. In regards to the inverter fixing power factor everyone is mostly correct. An inverter will always show a DPF (Displacement Power Factor) near unity. DPF is what a utility company traditionally monitors and is the measure of lag looking at current and voltage of power at 60hz or fundamental only. The true power factor on an frequency inverter will change with loading etc and includes current and voltage inclusive of harmonics.
Tags: Definition, Energy saving
Normal start
At normal start status, inverter will start and operate at given frequency in open loop mode, or operate at the expected value of the controlled object in closed loop mode.
Soft start
At soft start status, inverter will start and accelerate to the frequency of power grid regardless of the given frequency. When the output frequency of inverter reaches the frequency of power grid (set in main interface), then the output of inverter will become 0, at the same time inverter sends 'transfer to power grid' command. This command can make the control circuit to transfer the power supply of the motor from inverter to the power grid. During the transient transfer, there is a big inrush current.
For synchronous transfer (OPTIONAL FUNCTION, synchronous transfer reactor is required), both inverter and power grid will supply the power to the motor during the transient transfer, there is very small inrush current.
At normal start status, inverter will start and operate at given frequency in open loop mode, or operate at the expected value of the controlled object in closed loop mode.
Soft start
At soft start status, inverter will start and accelerate to the frequency of power grid regardless of the given frequency. When the output frequency of inverter reaches the frequency of power grid (set in main interface), then the output of inverter will become 0, at the same time inverter sends 'transfer to power grid' command. This command can make the control circuit to transfer the power supply of the motor from inverter to the power grid. During the transient transfer, there is a big inrush current.
For synchronous transfer (OPTIONAL FUNCTION, synchronous transfer reactor is required), both inverter and power grid will supply the power to the motor during the transient transfer, there is very small inrush current.
Tags: inverter, Definition
An inverter can operate down to its minimum designed frequency, however the motor design and load characteristics determine the minimum PRACTICAL frequency. If the motor is force cooled and the frequency inverter is operated in vector mode, as long as there is encoder feedback, and the load is not excessive, it is possible to achieve 100% torque at zero frequency.
Tags: inverter, Definition