The most common motor is the AC motor, used in over 70% of industrial applications globally. Known for its efficiency, an average AC motor operates at 85-95% efficiency, offering reliable performance in devices like pumps, fans, and conveyors with minimal maintenance.
AC Motors
About 85% of industrial motors are AC motors in the world, which account for 70% of total industrial electricity consumption in the world. In 2022, the industrial power consumption of China was up to 5.8 trillion kilowatt-hours, and more than 4 trillion kilowatt-hours were consumed by AC motors.
The general efficiency of AC motors is between 85% and 95%. For example, one three-phase asynchronous motor with rated power of 22 kilowatts has an efficiency of 91.5%. Compared to a DC motor of the same specification and 80% efficiency, this AC motor has a potential for saving 12,000 kilowatt-hours of electricity each year. Using the average industrial electricity price of 0.7 yuan per kilowatt-hour, the annual electricity cost savings of such a motor would reach 8,400 yuan.
The life of an AC motor is 15 to 25 years. In a dust-free environment, an AC motor may last up to 30 years. Even in harsh conditions, the average life of an AC motor is about 15 years, whereas a DC motor under similar conditions usually lasts only about 10 years.
An AC motor variable frequency converter enables a reduction in energy consumption by 20 percent to 30 percent. For example, in an industrial cooling tower, its variable frequency control system achieves annual electricity savings that can reach a maximum of 360,000 kilowatt-hours and decrease carbon dioxide by approximately 324 tons.
The large, industrially synchronized motors have withstood torques as high as over 1,000 ton-meters. When AC synchronous motors were adopted over the traditional DC motors for rolling at a specific steel factory, it resulted in rolling at an increase in speeds of from 30 to 50 m per minute, creating a production increase yearly to about 200,000 tonnes of steel.
The AC motor here can drive a common washing machine sufficiently, with power up to 200 watts. The power that it consumes per hour is around 0.2 kwh/h. Compared with the old-style washing machine using DC motors, with 0.4 kwh/h, 73 kwh power can be saved each year, which would save about 50 yuan electronically.
The Tesla Model 3 features a three-phase AC motor that has a maximum power output of 211 kilowatts with a peak efficiency of 97%. This engine loses only 10% as much energy as a conventional internal combustion engine can, yet it gives an acceleration from 0-100 km/h in just 4 seconds.
An industrial asynchronous motor usually costs between 5,000 and 10,000 yuan, with a maintenance cost of less than 2% of the whole every year. Taking a large manufacturing enterprise for example, the annual maintenance cost of 100 AC motors is about 300,000 yuan, which is 3,000 yuan on average for every single motor.
The intelligent AC motor management system can monitor real-time operational parameters such as temperature and vibration. Utilizing this system, one manufacturing enterprise reduced equipment failure rates by 50% and improved production efficiency by 15%.
DC Motors
Global DC motor market stood at approximately US$27 billion in 2023 and is projected to portray a CAGR of 4.8% by the end of the forecast period until 2030.
Take a permanent magnet DC motor rated at 10,000 watts for example: the output torque can be up to 40 Nm, the efficiency is above 90% when the speed is low at 1,000 RPM. In surgical robots used in medical devices, for instance, the control error by the DC motor shall not exceed 0.1 millimeters.
A 5-kilowatt DC motor is about 8,000 yuan, but an AC motor of the same power is only about 5,000 yuan. The service life of the brushless DC motor is generally between 20,000 and 50,000 hours, while the service life of the brush DC motor is between 2,000 and 10,000 hours. A brushless DC motor used in industrial automation equipment running 16 hours a day could have a life of over 10 years. In household appliances, like vacuum cleaners and blenders, brushed motors serve for only 2-3 years.
Several fuel valves in the SpaceX Falcon Heavy rocket are actuated by a number of brushless DC motors. Operating under very high temperatures, as high as 300 degrees Celsius, and with intense vibrations, the failure rate in such motors is less than 0.1%.
The Tesla Model S uses an advanced brushless DC motor with a peak power output of 615 horsepower, or about 450 kilowatts, with efficiencies above 96%. Calculations show that the energy consumption of the motor is only 0.18 kilowatt-hours per kilometer, reducing energy costs by over 80% compared to traditional fuel vehicles. DC motors can also achieve instantaneous startup speeds as high as 3,000 RPM.
It also means that a brushless DC motor with 1.5 kW power is just 60% in size and 30% in weight compared to an AC of the same power. This type of engine prolongs tool usage time for 25% and decreases failure rates for 20%.
The bearings of the Maglev DC motors rely completely on magnetic levitation. These kinds of motors have up to 98% efficiency, less than 40 decibels operating noise, and an improved life of over 50%.
Asynchronous Motors
The prices of a common three-phase asynchronous motor will range from 3,000 to 8,000 yuan. Motors of the same power but synchronous structure are usually 20% to 30% higher in price. Besides, each asynchronous motor is estimated to consume around 1% of its overall cost in maintenance every year. Assuming an average-sized factory with 100 asynchronous motors, the maintenance each year would be around 200,000 yuan, while the replacement costs account for only 5% of the total budget.
Generally, asynchronous motors operate within an efficiency of 85% to 93%. As such, for a three-phase asynchronous motor rated at 37 kilowatts, for instance, the highest efficiency could reach 92%. In comparison with DC motors and low-efficiency AC motors, almost 15% can be saved in energy consumption every year. At an industrial electricity price of 0.8 yuan per kilowatt-hour, a single asynchronous motor saves about 10,000 yuan in electricity costs every year.
A 45-kilowatt-rated asynchronous motor driving a pump system can realize a flow rate of 180 cubic meters per hour and a head of 50 meters. In one water supply company, replacing old motors with high-efficiency asynchronous motors has achieved an annual energy saving of nearly 5 million kilowatt-hours, which is about 4,500 tons of carbon dioxide emissions.
The lifespan of an asynchronous motor can be more than 20 years. If an asynchronous motor is used in a clean environment with stable temperature and humidity, it may live for 25 years. In one automobile manufacturing plant, asynchronous motors installed on the production lines ran for 22 continuous years and the failure rate was below 1% of the quantity.
High-efficiency asynchronous motors raise efficiency by 5% to 10%. One manufacturing company in Shanghai updated the outdated motors on its production line with high-efficiency asynchronous motors and saved up to 500,000 yuan in electricity costs per month.
The asynchronous single-phase motor used in the electrical pumping appliance is of 1.5 kilowatts and is able to lift up to 15 cubic meters of water in an hour. Operating costs will be more than 30% lower compared with the traditional diesel-powered pumps, almost without any maintenance cost. In this way, the farm will save over 200,000 yuan annually when fully transitioning to electrical pumping appliances.
A large three-phase asynchronous motor, with a rated power of 250 kilowatts, can provide more than 1,000 Newton-meters torque. A mining company that has adopted such high-power asynchronous motors increased its ore processing efficiency by 15%, generating an additional tens of millions of yuan in annual revenue.
The main disadvantages of asynchronous motors are speed fluctuations according to load changes. Nevertheless, this disadvantage has been largely improved by frequency converters. An asynchronous motor with a frequency converter can hold its speed within ±1% of the rated value.
Synchronous Motors
The global synchronous motor market size was about US$17 billion in 2022 and is expected to witness a compound annual growth rate of 4.5% up to 2030.
The efficiency usually lies between 90% and 98% for synchronous motors. For instance, a 100-kilowatt-rated synchronous motor could have an efficiency of up to 96%, consuming only 104 kilowatt-hours of electricity in an hour. In contrast, asynchronous motors of the same power usually have an efficiency of about 92%, and thus, the synchronous motor can save almost 4% of energy consumption every year. Based on the industrial electricity price of 0.8 yuan per kilowatt-hour, this synchronous motor operating 4,000 hours per year will save approximately 13,000 yuan in electricity costs.
For CNC machine tools, the synchronous motors have a speed error within the range of ±0.01%. While for an asynchronous motor, the speed error is between -1% and +1%. An aerospace manufacturing enterprise applied synchronous motors to drive machining equipment and increased the product qualification rate by 15%, creating an extra annual economic benefit of about 50 million yuan.
The operating life of synchronous motors can extend for 20-30 years. In generator sets, synchronous motors are designed for a service life of 25 years, although many have operated in service for up to 35 years. One synchronous motor installed in a hydropower plant began operating in 1978 and has continued to deliver reliable output for more than 40 years.
Large synchronous motors rated 500 kilowatts can provide torque well over 4,000 Newton-meters. A steel company that installed such high-power synchronous motors increased its rolling efficiency by 20%, boosting its steel production by almost 100,000 tons annually.
Advances in excitation technology have eliminated the need for additional excitation power in permanent magnet synchronous motors. One of the renowned automobile manufacturers used permanent magnet synchronous motors in their electric vehicles and achieved a motor efficiency of 97% with more than a 15% extension in the range of the vehicle compared to conventional electric vehicles.
A hydroelectric generator, for example, can realize an efficiency of 99% with 500 megawatts rated power and generate about 4.3 billion kilowatt-hours of electricity every year. The upgrade of a synchronous motor system in a certain wind farm increased the annual power generation by 12%, thus increasing the enterprise’s revenue by nearly 50 million yuan.
Large particle accelerators are powered by superconducting synchronous motors. The maximum speed of the rotation can reach up to 5,000 RPM and achieve as high as almost 100% in efficiency. An institution which applied such a motor reduced its experimental cost by more than 30%.
A synchronous motor of rated power of 50 kilowatts falls in a price range of 50,000-80,000 yuan, about 30% higher compared with an asynchronous motor of the same power.
Servo Motors
The global servo motor market reached US$14 billion in 2023 and is set to experience a compound annual growth rate of 6.5% through 2030.
The positioning accuracy for a servo motor used in the application of CNC machine tools can be as high as 0.01 millimeters, while for traditional motors, more than 0.5 millimeters of error is common. In chip manufacturing equipment, servo motors control the lithography machines with an error range less than 0.1 micrometers.
A rated power 5-kilowatt brushless servo motor usually has an efficiency of over 92% while asynchronous motors under the same specification have an efficiency of about 85%. So, servo motors can save almost 10% of annual energy consumption. If an equipment runs 8 hours each day, then it amounts to saving 1,460 kilowatt-hours annually. At an industrial electricity price of 0.8 yuan per kilowatt-hour, this amounts to a yearly cost saving of over 1,168 yuan.
A high-performance servo motor can accelerate from zero to its rated speed within 50 milliseconds, while traditional motors usually take over 200 milliseconds. In the case of industrial robots, the servo motors can realize rapid motion cycles of up to 150 pieces per minute.
The life of servo motors can last for 10 to 20 years. Servo motors used in medical equipment can easily live for more than 15 years, but their average life span in industrial areas is between 10 and 12 years. By regular maintenance, a manufacturing enterprise extended the average life span of its servo motors by 30% and saved considerably on equipment replacement costs.
With this, the servo motor weighs only 2.5 kg for 750 watts, volume 50% less compared to asynchronous motors of the same power. For example, the medical robotic arm uses the model of the servo motor which weighs just 1.8 kg but can already deliver up to 10 Newton-meters of torque.
Some well-known brands of electric vehicle servo motor drive systems are able to achieve 96% efficiency, reflecting more than a 20% increase in driving range. In wind power generation, servo motors are extensively used to control the angle of wind turbine blades.
IoT-integrated servo motors will be able to monitor the actual operating status in real time. By using this technology, an intelligent manufacturing enterprise reduced failure rates on the production line by 25%, saving over 1 million yuan in annual maintenance costs.
A 1-kilowatt servo motor is priced between 5,000 and 8,000 yuan, while an asynchronous motor of the same power is priced at only about 2,000 yuan. Once a semiconductor company improved the yield rate of its production line by using servo motors, additional annual revenue reached several tens of millions of yuan.
Brushless Motors
Characteristics are that the brushless motors boast high efficiency, a long life span, and low maintenance. In 2022, the global market for brushless motors reached about $18.7 billion, growing at a CAGR of 7.5% through 2030.
Efficiency for brushless motors generally ranges from 85% to 95%. For example, a 1-kilowatt brushless motor has an efficiency of 92%, while a brushed motor with the same power only achieves 75%. Assuming daily operation of 8 hours and 300 days per year, equipment using a brushless motor can save 408 kilowatt-hours of electricity annually. Based on the average industrial electricity cost of 0.8 yuan/kWh, the use of a single brushless motor can save approximately 326 yuan per year in electrical costs.
The lifespan of a brushless motor ranges between 20,000 to 50,000 hours, while a brushed motor runs for 2,000 to 10,000 hours. In some industrial automation applications, the brushless motor can run reliably for upwards of over 10 years, running 16 hours daily. A factory replaced all the brushed motors on its production lines with brushless motors and, in doing so, reduced yearly maintenance costs by almost 50% percent.
The 500-watt brushless motor weighs merely 1.5 kilograms, and its volume is 40% smaller compared with traditional brushed motors of the same power. Powered by a brushless motor, a model of DJI drones reaches the maximum lift of 3.5 kilograms, improves the efficiency of the motor by 15%, and prolongs the flight time by over 20%.
Tesla’s Model 3 applies a permanent magnet brushless motor, which is of 96% efficiency and has a maximum power output of 211 kilowatts, allowing the vehicle to achieve over 600 kilometers. This brushless motor system loses only 10% of the power compared with traditional internal combustion engines.
A canister vacuum cleaner driven by a brushless motor works at less than 65 decibels, or about 20 decibels lower than vacuum cleaners using brushed motors. Prevalence in using the brushless motors in air conditioners and washing machines helped a well-known home appliance brand reduce after-sales repair costs by over 30% every year.
A high-performance brushless motor can accelerate from zero to rated speed in 50 milliseconds, whereas the best brushed motors take over 200 milliseconds. An industrial robot fitted with brushless motors increased its operational cycle from 80 to 120 per minute, thus improving production efficiency by 50%.
IoT technology can also be installed on brushless motors for real-time monitoring of operational status. In one smart manufacturing enterprise, intelligent brushless motors reduced equipment failure rates by 30%, with a saving of over 2 million yuan per year in maintenance costs.
The price of one kilowatt brushless motor generally ranges from 3,000 to 5,000 yuan, while a brushed motor of the same power is only about 1,500 yuan.
One of the examples is a wind farm that, after upgrading the system with brushless motors, increased its annual power generation by 8% and added over 10 million yuan in annual revenue. Ultra-high-speed brushless motors have also found application in centrifuges and aerospace equipment, capable of maximum rotational speeds up to 100,000 RPM.
Stepper Motors
Stepper motors can precisely convert an electrical pulse signal into angular displacement. The global stepper motor market was valued at around US$3.2 billion in 2022 and is set to exhibit a growth rate of 6% CAGR through 2030.
The conventional two-phase stepper motor has 1.8-degree steps, dividing one full rotation into 200 steps, with a positioning error less than 0.09 degrees usually. For high-precision 3D printers, even as fine as 0.05-millimeter layer thickness can be achieved using the stepper motors.
The price for one stepper motor of 200 watts is generally between 500 to 1,000 yuan, while the servo of the same specification can be above 3,000 yuan. Once, a small and medium-sized enterprise upgraded an automation production line equipped with a stepper motor, and the cost of equipment was reduced by 30%, saving over 200,000 yuan every year.
The estimated usage life of stepper motors falls between 10,000 and 20,000 hours. In medical devices, a stepper motor can have an average lifetime of over 15 years. For industrial surroundings, their lifespan is usually between 5 to 10 years. A manufacturing company reduced stepper motor failure rates by 50% through regular maintenance and optimized use conditions.
The stepper motor rated for 2 amperes can achieve a holding torque of 1.2 Newton-meters and maintain 0.8 Newton-meters at its rated speed. A stepper motor is adopted for driving the robotic arms, and the production efficiency of an electronics factory increases by 15%, generating extra revenue of about 3 million yuan per year.
The hybrid stepper motor can realize about 85% efficiency, which is an improvement of about 10% compared to the traditional stepper motors. Hybrid stepper motors have greatly improved image quality and equipment stability in X-ray machines.
In drone gimbal systems, micro stepper motors weighing only 100 grams can deliver up to 0.5 Newton-meters of torque output while achieving precise positioning accuracy of ±0.02 degrees.
The maximum rotational speed for a standard stepper motor is usually under 2,000 RPM, while servo motors can easily reach over 5,000 RPM. A driver supporting 32 subdivisions can reduce stepper motor noise by more than 50% while improving its smoothness.
Further integration of IoT technology allows for real-time monitoring
