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