Static scherbius drives are capable of bidirectional power flow, with both positive and negative injected voltages possible, in phase with or opposing. Abstractthe growing need for efficient drive systems has given the static kramer drive system a position of importance among variable speed drives. The slip power control drive that permits only a sub synchronous range of speed control through a converter cascade is known as a modified static kramer drive, so we use modified static kramer drive system. Occasions pre wedding v2 party v2 baby v2 social stationery holiday v2 classics classic mitzvah classic wedding signature mitzvah signature wedding. However, the variablefrequency of a twophase machine drive principle is similar to a threephase drive. Kramer system is a system or a method that uses to control speed of induction motors. The static kramer drives fed back the wasted power into the main supply.
By changing the injected voltage, the resistance and speed of an induction motor are controlled. Rotor induction motor an overview sciencedirect topics. The slip power controlled drive that permits only a sub synchronous range of speed control through a converter cascade is know as static kramer drive. The voltage at the slip rings is forced to be in phase with the rotor currents by the diode rectifier. A static drive used in conjunction with a line transformer operates with 95% to 97% rectifiertransformer efficiency. May 03, 2018 slip energy recovery scheme using static scherbius drive system the rotor current to have a required value of current i. In this paper, a new scheme for static scherbius drives, which results in improvement of power factor of the drive, has been proposed. Static induction thyristor symbol static induction. Just fill out the form on the right and we will be in touch soon. For example, in a sewage lift station sewage usually flows through sewer pipes under the force of gravity to a wet well location. The speed automatically varies to bring in balance. It creates a shortcut on the desktop for easy access. The drive system is very efficient and the converter power rating is low, because it has to handle only the slip power.
The stator side control is applicable to both squirrel cage and slip ring induc tion motors. It has a chopper inserted between the rectifier and inverter modules. What are the advantages and disadvantages of static scherbius drive. Scherbius drive pdf a static kramer drive is a method to obtain an injected voltage that is in phase with the rotor current. Dsp based static kramer drive i o n alce a t rt n if i r c et a t e n i regist ra l t d.
Static kramer drive or slip power recovery is discussed here with easy explanation. The drive system is very efficient and the converted power rating is low because t has to handle only the slip power, in fact, the power rating becomes lower with a more. The static kramer drive variablespeed drive system shown in fig. The slip power is the air gap power between the stator and the rotor of an induction motor which is not converted into mechanical power. Slip power recovery instead of wasting the slip power in the rotor circuit resistance, a better approach is to convert it to ac line power and return it back to the line. For tcpipv4 you can use any ip address in the range 192.
A system employed for motion control by using electric motor as a primemover. The slip power controlled drive that permits only a subsynchronous speed control through a converter cascade is called a static kramer drive. The static kramerdrive converts the slip power of an induction motor into ac power and supply back to the line. The growing need for efficient drive systems has given the static kramer drive system a position of importance among variable speed drives. Cortina improved static kramer isk is a highly efficient means of speed control of wound rotor motors typically in the 500kw to 10mw range. Slip power recovery system in three phase slip ring induction. In large power pump and fan type drives, where speed control within narrow range and below synchronous speed. The input and output conditions in a naturally commutated thyristorbridge inverter can be improved in most respects by adopting the controlled flywheeling technique. The power to drive industry eaton lighting systems. A variablefrequency single phase motor drive is difficult to achieve because of its large pulsating torque. A combination of prime mover, transmission equipment and mechanical working load is called a drive electric drive.
Select use the following ip address for static ip addressing and fill in the details as shown in figure 6. It is different from original static kramer drive where rotating machines were used for slip energy recovery. The kramer low profile electric unit cooler is the ideal solution for problem areas with limited head room. Alternatively, you can open your web browser on your mobile device and enter the ip address for your via connect pro unit. The magnitude of the slip ring voltage is set by the dc link voltage, which is in turn set by the. The static kramerdrive is the method of controlling the speed of an induction motor by injecting the oppositephase voltage in the rotor circuit. Pdf mathematical model of asynchronous machine in matlab. A static kramer drive is a method to obtain an injected voltage that is in phase with the rotor current. Harmonic analysis in power systems is a challenge that is always evolving due to a constantly changing power grid. The controlled rectifier works as an inverter and converts the dc power back into ac and feeds it back to the ac source.
Static kramer and static scherbius drives have been used in industry for limited range speed control near the synchronous speed. Slip energy recovery scherbius drive static kramer drive. The static kramer drive has been very popular in large power pump and fantype drives, where the range of speed control is limited near, but below the synchronous speed. Application of controlled flywheeling to the recovery bridge. The drive comprises a slipring wound rotor induction motor together with an uncontrolled converter, d. The static scherbius drive provides the speed control of a wound rotor motor below synchronous speed. Instead of wasting the slip power in the rotor circuit resistance, it can be converted to 60 hz a. By substituting a solid state dc drive for a motorgenerator set, drive efficiency can be improved from 18% to 33%.
The portion of rotor ac power is converted into dc by a diode bridge. The slip power recovery takes place through the rectifier and the auxiliary dc motor. The development of the optimal techniques for estimation of harmonics, interharmonics and subharmonics for that static kramer drive will aid in estimation of harmonics, interharmonics and subharmonics in similar motor drive systems. Similar device, known as fieldcontrolled thyristors fct or fieldcontrolled diode fcd, were developed in usa. The performance of a static kramer drive is substantially affected by the dc voltage waveform of the thyristor recovery bridge and the inductance of the dc link smoothing reactor. If the control application cannot work with an ethernet driver, use the kramer virtual port driver as follows. Static scherbius drives are capable of bidirectional power flow, with both positive and negative injected voltages possible, in. A rigorous analysis of the static kramer drive under steadystate conditions is described in which stator variables are transformed on to a frame of reference which is stationary with respect to the rotor. Maximum advantage is gained at low dc side voltages, and this makes the technique especially suitable for use with the static kramer drive. An static induction thyristor or sithyristor is a selfcontrolled gtolike onoff device commercially introduced in japan in 1988. Modeling and speed control scheme for the static kramer drive. Speed control of 3 phase induction motor by slip power recovery is the main focus here. Dsp based static krammer drive it consist of three major parts.
E electronically commutated motor s shaded pole voltage code. Advances in power electronics have led to the installation of many new nonlinear power loads, such as power converters, arc furnaces and motor drive systems, which in turn change the existing infrastructure and inject new types of harmonics. The design considerations of such a scheme have been discussed in detail. The experimental results on a scherbius drive using the proposed. The schematic circuit for a static kramer drive is shown below. Slip energy recovery scherbius drive static kramer. Analysis and simulation of static kramer drive under steady. Calculation of slip energy recovery induction motor drive. Power semiconductor drives pdf notes psd pdf notes. The static kramer drive has been very popular in large power pump and fan type drives, where the range of speed control is limited near, but less than the. The very low losses and harmonic content is a distinct advantage over other speed control systems. A particular system employed for motion control is called drive. The so called dc equivalent circuit ec, approach 41 and the ac ec 51 are simplified methods which consist in essence, of transferring the system parameters on to.
Slip energy recovery scheme using static scherbius drive system the rotor current to have a required value of current i. Static drives vs motor generators motion control engineering. Because of more advantages, squirrel cage motor is always preferred. This drive has the ability of flow the power both in the positive as well as the negative direction of.
The kramer system is only applicable for sub synchronous speed o peration. Estimation of harmonics, interharmonics and subharmonics in. Static kramer drive instead of wasting the slip power in the rotor circuit resistance, a better approach is to convert it to ac line power and return it back to the line. The static kramer drive converts the slip power of an induction motor into ac power and supply back to the line. It is particularly suited to centrifugal loads such as pumps and fans. Static rotor resistance control slip power recovery static scherbius drive static kramer drive their performance and speed torque characteristics advantages applications problems. With a low profile drawthru design, uniform air distribution is achieved. A static scherbius drive with chopper ieee journals. Kramer drive power inverter electrical engineering. An adjustable speed drive can often provide smoother operation compared to an alternative fixed speed mode of operation. The injected voltage increases the resistance of the rotor, thus controlled the speed of the motor.
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