Maximize Your Energy Savings With High-Efficiency PMSM

In May 2020, China announced the latest motor energy efficiency standard "GB18613-2020 Electric Motor Energy Efficiency Limits and Energy Efficiency Grades". The standard is officially implemented on June 1, 2021. Energy efficiency motors below IE3 (international standard) is forced to stop production. And the domestic motor industry will fully enter the IE3 high-efficiency era.

The difference between motor energy efficiency labels after the implementation of the new national standard GB 18613-2020 is as follows:

1. 10 Reasons Why Permanent Magnet Motors Are Highly Efficient

High-efficiency motors refer to motors with higher efficiency, and their efficiency values can reach the second level of GB18613-2012 standard. High-efficiency motors use new motor designs, new processes and new materials to improve output efficiency by reducing the loss of electromagnetic energy, thermal energy and mechanical energy. Compared with standard motors, their efficiency is increased by 4% on average.

The reasons for the high efficiency of PMSM are mainly attributed to the following aspects:

(1)High magnetic energy density: PMSM uses permanent magnets to generate magnetic fields. These magnets are able to provide high magnetic energy density, thereby generating a strong magnetic field with a small size and weight.

(2)Reduce energy loss: Due to the high efficiency of permanent magnets, the motor requires less current to produce the same torque, which reduces copper losses (I²R losses) caused by current flow.

(3)High-efficiency operating area: The design of PMSM enables them to maintain high efficiency over a wide operating range. This is because the magnetic field strength of the permanent magnet is relatively constant and will not fluctuate greatly due to changes in the motor load.

(4)Simple structure: PMSM usually do not require the excitation winding found in electrically excited motors, which reduces energy losses inside the motor and simplifies the structure of the motor.

(5)High power density: Due to the high magnetic energy density of permanent magnets, permanent magnet motors can achieve high power output in a smaller volume, which means they can provide high efficiency in a compact space.

(6)Good thermal performance: The design of PMSM generally allows for better heat dissipation because they have fewer conductive parts and lower heat generation.

(7)Reduce maintenance: PMSM generally require less maintenance due to their simple structure, which helps reduce downtime and improve overall operating efficiency.

(8)High control accuracy: PMSM combined with modern control technology can achieve more precise speed and position control, which improves the overall efficiency of the system in applications that require precise control.

(9)Energy feedback: In some applications, PMSM can also realize braking energy feedback, further improving the energy efficiency of the system.

(10)Long-term stability: The magnetic properties of permanent magnet materials are more stable over time, which means that the motor can maintain high efficiency in long-term operation.

2.High-efficiency Energy-saving Motors Can Actually Save so Much Electricity!

Energy saving of motors is a systematic project, involving the entire life cycle of motors, from motor design and manufacturing to motor selection, operation, adjustment, maintenance and scrapping. The effects of energy-saving measures should be considered from the entire life cycle of the motor. In this regard, domestic and foreign researchers mainly consider improving the efficiency of motors from the following aspects.

The design of energy-saving motors refers to the use of modern design methods such as optimization design technology, new material technology, control technology, integration technology, and test and detection technology to reduce the power loss of the motor, improve the efficiency of the motor, and design a high-efficiency motor.

While converting electrical energy into mechanical energy, the motor also loses some energy. Typical AC motor losses can generally be divided into three parts: fixed loss, variable loss, and stray loss. Variable loss changes with the load, including stator resistance loss (copper loss), rotor resistance loss, and brush resistance loss; fixed loss is independent of the load, including core loss and mechanical loss. Iron loss is composed of hysteresis loss and eddy current loss, which is proportional to the square of the voltage, and hysteresis loss is inversely proportional to the frequency; other stray losses are mechanical losses and other losses, including bearing friction loss and wind-age loss caused by rotation of fans and rotors.

So, how much electricity can high-efficiency energy-saving motors save? Here is an example to briefly explain:

A company used ordinary 7.5KW motors before. There were 10 motors in the factory, running 8 hours a day and 300 days a year. This year, the company upgraded its equipment and replaced 10 high-efficiency motors . The power is still the same, but it saves a lot of electricity.

For the same power of 7.5KW, the efficiency of ordinary motor is 87%, and the efficiency one is 90.1%, so the whole year:

◆ The power consumption of ordinary 7.5KW motor in one year is: (7.5/0.87)*8*300=20,689.6 kW·h

◆ The power consumption of high-efficiency 7.5KW motor in one year is: (7.5/0.901)*8*300=19,977.8 kW·h

◆ After using high-efficiency energy-saving motor, one unit can save electricity in the whole year: 20689.6-19977.8=711.8 kW·h

The company uses 10 7.5KW high-efficiency energy-saving motors, which can save 7118 kW·h of electricity a year!