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    • What are the selection criteria for selecting an electric motor?

      Electric motors make it possible to perform different types of movement: fast, precise, continuous, with or without gear shifting, etc. All of these applications require their own motor technology.

      1. First, you must choose between four main groups of electric motors:

      2. In order to select between these four groups, it is necessary to determine the type of application required as this will influence your choice:

        • For runing continuously and with few gear changes applications, you should select an AC Universal Motor.

        • For dynamic applications, a brushed DC motor or brushless DC motor is an inevitable choice.

        • For low-speed, high-load applications, a motor(AC/DC/BLDC) with a specific reduction ratio gearbox is an inevitable choice.

        • For applications that require precise control of speed and/or torque, you need to add the appropriate encoder to the motor(AC/DC/BLDC) solution.

        • For applications that require precise positioning, you should choose a stepper motor, but it is not within Power Motor's customized services.

      3. Depending on the movement your require, you will also need to determine the technical specifications and size of the motor:

        • To determine the technical specifications, it will be necessary to determine the power, torque and speed of the motor.

        • In order to determine the size, you must know how much space the motor will take up and how it is mounted (i.e.how it will be fixed in the syste).

        • When choosing the dimensions and solidity of the motor you must also take into account the industrial environment that the motor will operate in: There is a format adapted for every type of environment (explosive, damp, corrosive, high temperature, etc.)

        • For harsh environments there are motors with reinforced, waterproof, shock-resistant or dirt-resistant casings.

      4. Finally, in recent years, energy efficiency has become an important factor to take into account when selecting a motor:

        • An electric motor that uses less energy will have a low energy impact, which will reduce its energy cost.

    • How to select between an AC universal motor and a DC motor?

      These two types of motors are built differently:

      • The most fundamental difference is the power source: alternating current (single-phase or three-phase) and direct current (DC), for batteries for example.

      • Speed is another difference. The speed of an AC motor is controlled by varying the current in the motor while that of a DC motor is controlled by varying the frequency, usually with a frequency converter. As such, AC motors run faster than DC motors.

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      AC Universal Motors

      1. AC Universal Motors:

      AC universal motors are the most popular in the industry as they have several advantages:

      • They are simple to build

      • They are more economical due to lower start-up consumption

      • They are also sturdier and therefore generally have a longer lifespan

      • They require little maintenance

      Because of how they operate, which involves synchronization between the rotor rotation and current frequency, the speed of AC universal motors remains constant. They are particularly suited for applications requiring continuous movement and few gear changes. This type of motor is therefore perfectly adapted for use in household appliance, such as: blender, vacuum cleaner, hair dryer, pump and fan, etc.

      Power Motor provide two types of AC motors: Universal Motor, Shaded Pole Motor.

      • Our AC universal motor and shaded pole motor generally use single-phase current.

      • More power, determine more torque;

      • More poles, determine higher rotational speed.

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      Brushed DC motors

      2. DC motors:

      DC motors are also very common in home appliance, healthcare, automotive and industrial, because they have significant advantages:

      • Accurate and fast

      • High starting torque

      • Starting, stopping, accelerating and reversing are done quickly

      • Their speed can be controlled by varying the supply voltage

      • They are easy to install, even in mobile (battery-powered) systems

      They are very well suited for dynamic applications requiring high accuracy particularly in terms of speed, as in the case of hair dryeror in terms of position as in the case of robots or machine tools.

      They are less suitable for applications requiring high power.

      3. What are the market trends today?

      • Brushed DC motors are used less and less frequently in industrial applications, but more and more frequently in home appliance, healthcare and automotive applications. For lower power, AC motors are used instead as they require little maintenance for equivalent use.

      • Since DC motor parts are too expensive to replace, some manufacturers opt for AC motors in which they integrate an electric controller.
        >The combination of an AC motor and a frequency inverter has become a cost-effective solution for most applications requiring speed variations. Power Motor have done it professionally since 2001.

    • Should you select a brushless motor or a brushed motor?

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      Brushless DC motors

      The two most common types of DC motors are brushed motors and brushless motors.

      1.  Brushed motors

      Brushed motors are the simplest and most frequently used motors, especially for home appliance, automotive and low-budget applications.

      The advantages of brushed motors:

      • Easy to control and therefore have the ability to control many motors from a single controller.

      • High torque at low revs

      • Inexpensive

      There are four types of brushed motors depending on your intended use.

      • Permanent magnet:

        • This type of motor contains a permanent magnet that enables low torque.

        • This is useful for applications requiring precise control such as robotics or servo systems.

      • Series-wound:

        • In this type of motor, the stator is connected in series with the rotor and the speed is controlled by varying the supply voltage.

        • However, this type of speed control is rather poor: the speed drops as soon as the torque to the engine increases.

        • This type of engine is useful for applications requiring high starting torque, such as automotive power seat or AMT.

      • Shunt-wound:

        • In this type of motor, the stator is connected in parallel to the rotor, which allows for a higher torque without reducing the speed as the motor current increases.

        • This type of motor is suitable for applications with constant speeds such as vacuum cleaners or conveyors.

      • Compound wound:

        • This type of motor combines the structure of series-wound motors and shunt-wound motors.

        • As a result, it offers a high starting torque as well as a higher speed variation.

        • This type of motor is perfect for rotary presses, elevators, baggage carousels, centrifugal pumps and compressors.

      The disadvantages of brushed motors:

      • They are less efficient than brushless motors (75-80% compared to 85-90% for brushless motors).

      • Their service lifespan is short because the brushes, due to regular friction, wear out more quickly over time (between 1,000 and 10,000 operating hours depending on the frequency of use, power, speed, vibration, etc.)

      • The arc of the brushes and collector can generate electromagnetic noise that high noise.

      • Similarly, the risk of sparks due to friction makes using this type of motor in explosive environments undesirable.

      • The speed is generally limited due to the heating of the brushes.

      • Brushes made of graphite generate dust that can damage other devices, such as optical devices.

      • They need to be lubricated, which makes it impossible to use them in vacuum cleaners.

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       Brushless DC Motor

      2. Brushless motors

      The advantages of brushless motors:

      • They can operate at higher speeds (up to 100,000 rpm compared to 20,000 rpm for brushed motors).

      • They have a longer service life (over 10,000 hours of operation)

      • They are more reliable and efficient.

      • There are no wearing parts except for the bearings, which reduces maintenance operations.

      The fact that brushless motors are able operate at very high speeds makes them particularly suitable for hair dryer, fans, grinders or saws.

      Brushless motors are systematically equipped with an encoder, a sensor that allows for electronic switching and determination of the rotor position. These motors are therefore perfect for servomotor precision applications.

      The disadvantages of brushless motors:

      • The initial cost is high because it is necessary to integrate a dedicated switching device (controller), and would have required one controller per motor .

      • They also generally require a gear reducer in drive applications.


    • How to select a ideal gearbox for your motor?

      1. What is the selection criteria for selecting a gearbox?
       Before selecting a gearbox(also known as gearhead or gear reducer ), it's important to take several factors into account: Torque, Rotation Speed and Gearbox Type.

      • It is therefore appropriate to ask yourself about the torque first and foremost. A gearbox increases the torque of your motor and thus allows a receiving member to rotate under the impact of a new torque. The torque density varies according to the gearbox. For example, planetary gearboxes have a high torque density.

      • The other purpose of a gearbox is to reduce the motor speed and our engineer will select ideal reduction ratio for your product according to it's application. Based on the rotational speed of your motor, the reduction ratio is used to determine the output rotational speed.

      • you should ask yourself what kind of gearbox assembly is most appropriate for your application. The input and output shafts of your gearbox can be coaxial, parallel-shaft or orthogonal. This depends on your application.
        There are four main types of gearboxs: planetary gearbox, worm gearbox, spur gearbox and helical gearbox. Each gearbox has its advantages and disadvantages. You will have to choose the one that's the most adapted to your motor . For example, if you are looking for a good level of efficiency, perhaps you should consider a planetary gearbox rather than a helical gearbox.

      • Since2001, Power Motor provides custom engineering to design gear motors utilizing various motor type(brushless DC motor, brushed DC motor, universal motor and other motors),integrated control & sensing, gear type(spur & helical, worm and planetary) and gearbox material to meet customer specific performance requirements for applications.

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      Planetary Gearboxs

      2. When should you use a planetary gearbox?:

      One of the main characteristics of a planetary gearbox is the coaxial assembly. This type of assembly means that planetary gearboxes are compact.

      • The advantages of planetary gearboxes include their compact size, high efficiency, low clearance and high torque to weight ratio.

      • On the other hand, their complex and costly design requires specialized maintenance.

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      Worm Gearbox

      3. When should you use a worm gear reducer?:

      Worm gear reducers have perpendicular input and output shafts. They are generally used for applications requiring a very high transmission ratio. The advantages and disadvantages of worm gearbox:

      • The mechanism of worm gear reducers is non-reversible. This means that the worm wheel cannot drive the worm. The advantage of this non-reversible mechanism is that it ensures a greater level of security for the system. Worm gear reducers are less expensive than planetary gearboxes and are also quieter. Worm gear reducers do not vibrate, so they generate little noise and are more comfortable to use.

      • However, like planetary gearboxes, worm gear reducers heat up quickly due to how compact they are. They also have a variable performance level. You can however improve the performance by combining your worm gearbox with other gearboxes and gear trains. Power Motor have done it well.

      Spur Gearbox.jpg
      Spur Gearbox

      4. When should you use a spur gearbox?:

      Spur gearboxs with parallel axes are generally used for applications requiring a lot of power, such as conveyors. The simplicity of their technology will allow you to save on maintenance costs. Additionally, spur gearboxs have a very high performance level, close to 1. They have a low reduction ratio per gear.

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      Helical Gearbox

      5. When should you use a helical gearbox?:

      Helical gearbox's main characteristic is their angular bell crank, which allows the user to change the machine’s rotation system. This will allow you to switch from a transverse rotation system to a longitudinal rotation system. :

      • Helical gearboxs are compact. They are also robust and can handle a lot of power. As such, if you need a high torque we recommend that you choose this technology. The robustness of their teeth allows you to use them with AC universal motors, or brushed DC or brushless DC motors.

      • Helical gearboxs are quiet, making using them pleasant to use. Additionally, they offer a high performance level and are energy efficient. Their performance level remains lower than planetary gearboxes however. Helical gearboxs are also very expensive and require difficult maintenance.

      • Helical gearboxs are generally used for high-powered applications, but also for home appliance.

      6. Trend: Magnetic Gearbox

      • Magnetic gearboxs can advantageously replace conventional gear reducers to ensure speed and torque multiplication by using magnetic attraction instead of physical contact between moving parts. To date, complex assemblies, high weight and low torque have slowed the diffusion of this magnetic technology. However, magnetic gears eliminate the need for lubrication and therefore minimize maintenance costs. No lubrication also means that mechanisms can operate at extreme temperatures (currently tested from -200?C to 350?C). These advantages are particularly attractive for applications with high maintenance costs or for those working in extreme environments such as satellites and other aerospace devices.

      • Along with usage and corrosion, wear is one of the three main factors limiting the life and performance of mechanical components and technical systems. With magnetic gearboxs, the absence of friction not only eliminates wear of the system, it also has a direct impact on service life, which can be the key to maintaining mechanisms that cannot be easily replaced.Material detached from the worn surface in conventional transmissions cannot be easily removed, which can be a significant cause of contamination. Contamination is a particularly serious problem for equipment that cannot be constantly maintained. Advantages to a magnetic gearbox:No lubrication, No wear
        > Power Motor have been worked on this technology for few years.

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