Download document () of 20
Send email
Download
You have exceeded the download limit
A success story of standardization is the introduction of efficiency classes for motors, the so-called IE code (International Efficiency). This makes it easy to see how energy-efficient an electric motor is - IE4 motors currently have the highest efficiency. This classification was expanded in the following years. Today, there is a consistent standard for evaluating the energy efficiency of the components through to the entire drive system. The energy efficiency of components (e.g. motor, variable speed drive) is described by IE codes, that of the entire drive system by the so-called IES code (International Efficiency System).
A total of four efficiency classes – from IE1 to IE4 – are currently specified for asynchronous motors in IEC 60034-30-1. The IE classes for drive controllers and variable speed drive in a power range from 0.12 to 1000 kW are described in IEC 61800-9-2. It “only” defines three IE classes for these devices: IE0 (low) to IE2 (high).
Regulation (EU) 2019/1781 on electric motors and speed controls, which came into force on 1 July 2021, stipulates that a wide range of motors must meet efficiency class IE3 and the variable speed drives required to control the speed and torque of the motors must meet energy efficiency class IE2. To this end, the regulation defines minimum efficiency values both for low-voltage motors for direct mains connection and for variable-speed drives.
Get every important blog post or new information Eaton is pulishing for machine and systembuilders.
To determine the energy efficiency class, the relative losses of the variable speed drive in relation to its rated apparent output power are used. The evaluation takes place at 90 percent of the output voltage and 100 percent of the torque-generating current. The relative losses are then compared with a so-called reference variable speed drive: Class IE1 is used as a technical standard as a reference for determining the other classes. In relation to the value of a variable speed drive with efficiency class IE1, a class IE2 device has 25 percent lower losses and a class IE0 device has 25 percent higher losses.
In general, variable speed drive already have a high degree of efficiency rating of over 95 percent, which means that almost all the power consumed is released and is available to the motor. Nevertheless, there is always a certain percentage of power loss, typically in the form of heat.
Various aspects have an influence on the heat dissipation: In addition to the basic structure, the pulse frequency also plays a role. Their choice is a compromise between the losses in the variable speed drive and the losses in the mains and motor caused by harmonics.
A variable speed drive and motor nominal power that is correctly matched to the through-drive capability is also important for high efficiency rating. If the power falls far below the nominal operating point (< 30 percent), the efficiency rating drops sharply.
In general, variable speed drive already have a high degree of efficiency rating of over 95 percent, which means that almost all the power consumed is released and is available to the motor. Nevertheless, there is always a certain percentage of power loss, typically in the form of heat.
Various aspects have an influence on the heat dissipation: In addition to the basic structure, the pulse frequency also plays a role. Their choice is a compromise between the losses in the variable speed drive and the losses in the mains and motor caused by harmonics.
A variable speed drive and motor nominal power that is correctly matched to the through-drive capability is also important for high efficiency rating. If the power falls far below the nominal operating point (< 30 percent), the efficiency rating drops sharply.
The power semiconductors used also have a significant influence on the losses in variable speed drives. A highly efficient converter technology uses power switches made of silicon carbide (SiC) or gallium nitride (GaN) instead of the conventional silicon power semiconductors. SiC and GaN are semiconductor materials with a wide band gap. Thanks to them, power switches can operate at a higher temperature, higher frequency and at higher voltages compared to conventional silicon-based power switches such as IGBTs or silicon MOSFETs. This means that efficiency rating of 98 percent and more are now possible.
In conjunction with an IE3 or IE4 Motor, it is important that the variable speed drive is designed for operation on these highly efficient motors. In order to control these types of motors, the variable frequency drives need to be equipped with appropriate control algorithms. If the variable speed drive is not suitable for operating IE4 motors, this may have various effects: In the worst case, the motor may not start at all. and even if it does, it may not operate properly – in other words, it will not work efficiently. All variable speed drive of Eaton's PowerXL family are designed for operation with IE4 motors. In addition, Eaton variable speed starters and variable speed drives correspond to the highest efficiency class for CDMs (Complete Drive Modules) IE2 according to IEC 61800-9-2.
Variable speed drives are increasingly being used to increase energy efficiency. In order to achieve the highest possible overall efficiency in the drive system made up of motor and variable speed driver, the variable speed drive should also have a high energy efficiency class. However, it is important not to look at the Drive Controller in isolation, but in connection with all other components of the drive system and always in connection with the application. More detailed information about (EU) 2019/1781 is provided in the white paper "Successfully increasing energy efficiency in drive technology" by the energy management company Eaton, which is available for download on the company's website
Contact our team or sign up to ask questions and stay up-to-date on news, product updates and industry trends.
