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Recommended starting methods for LSPM motors (Line Started Permanent Magnet)

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Recommended starting methods for LSPM motors (Line Started Permanent Magnet)

Recommended starting methods for LSPM motors (Line Started Permanent Magnet)

S_S_IBRAHIM

(Electrical)

(OP)

20 Mar 23 18:08

DO these types of motor (Line Started Permanent Magnet ) can work efficiently with VFD ?

Replies continue below

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RE: Recommended starting methods for LSPM motors (Line Started Permanent Magnet)

BrianPetersen

(Mechanical)

20 Mar 23 20:04

It would help if you explained the application. Is this a tiny synchronous motor that operates the hands of an old fashioned clock through an extremely high-ratio (but low-inertia) gear reduction, or is it a massive motor the size of a house that operates something (?) synchronously, or somewhere in between, or what is it? Explain yourself.

Permanent magnet motors in my field of understanding are also called "brushless DC" motors or "servo" motors, and in this day and age, they are electronically commutated. There's an example of such a motor, and a highly specialised drive that operates it, in my driveway, in the form of the drive unit for my Chevrolet Bolt.

So. Explain yourself.

RE: Recommended starting methods for LSPM motors (Line Started Permanent Magnet)

waross

(Electrical)

20 Mar 23 23:09
They would not work with a VFD.
Echoing Brian;
We need more information.

Most of the "line started" (12 V DC line) DC motors that I am familiar with move things like seats and mirrors in my car.They would not work with a VFD.Echoing Brian;We need more information.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

RE: Recommended starting methods for LSPM motors (Line Started Permanent Magnet)

FacEngrPE

(Mechanical)

20 Mar 23 23:30
From the standpoint of using a VFD with a LSPMSM, it should be similar to any AC motor having a Permanent magnet roter. If the VFD is suitable, the documentation will indicate that a setting for PM mode is available.
PM motors are reported to have very fast accelerations when started across the line.
http://www.vfds.org/why-does-a-permanent-magnet-ac...
The LSPMSM likely is similar to a PM motor but designed to have an acceleration that is tolerable when started across the line.

So if the plan is to use a PM mode VFD why not use the more available PM AC motors intended for use with a VFD?

An attempted web search for "line-start permanent-magnet synchronous motor (LSPMSM)" finds mostly research papers, demonstration videos, a few nitch products, and some hopeful postings about products in R&D.From the standpoint of using a VFD with a LSPMSM, it should be similar to any AC motor having a Permanent magnet roter. If the VFD is suitable, the documentation will indicate that a setting for PM mode is available.PM motors are reported to have very fast accelerations when started across the line.The LSPMSM likely is similar to a PM motor but designed to have an acceleration that is tolerable when started across the line.So if the plan is to use a PM mode VFD why not use the more available PM AC motors intended for use with a VFD?

RE: Recommended starting methods for LSPM motors (Line Started Permanent Magnet)

Gr8blu

(Electrical)

21 Mar 23 12:11 SS Ibrahim The "industrial grade" line-start permanent-magnet motors (up to several hundred kW) are out there: at least one North American and a couple of European manufacturers have patents on the internal design of both the rotor and stator. The bottom line is that the rotor design has to be a cross between an old-school squirrel-cage induction machine and a modern (interior) permanent magnet machine. The (copper) cage creates the initial starting / break-away torque to get the rotor moving in a line-start application. If the machine is designed (and manufactured) correctly, it will certainly operate on an adjustable speed drive - pretty much the same way as a squirrel-cage induction from standstill, with a switch in control scheme to permanent-magnet mode at some fairly low frequency condition (below 10 Hz, I believe).

Then again - why choose this design if you're using a VFD in the first place? Why not just a squirrel cage induction or a (solely) permanent magnet design? Both are cheaper, more reliable, and more readily available compared to the combination required for LSPM.

The "industrial grade" line-start permanent-magnet motors (up to several hundred kW) are out there: at least one North American and a couple of European manufacturers have patents on the internal design of both the rotor and stator. The bottom line is that the rotor design has to be a cross between an old-school squirrel-cage induction machine and a modern (interior) permanent magnet machine. The (copper) cage creates the initial starting / break-away torque to get the rotor moving in a line-start application. If the machine is designed (and manufactured) correctly, it will certainly operate on an adjustable speed drive - pretty much the same way as a squirrel-cage induction from standstill, with a switch in control scheme to permanent-magnet mode at some fairly low frequency condition (below 10 Hz, I believe).Then again - why choose this design if you're using a VFD in the first place? Why not just a squirrel cage induction or a (solely) permanent magnet design? Both are cheaper, more reliable, and more readily available compared to the combination required for LSPM.

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News

 The preceding post discussed why PMSM motors are so interesting and how they improve and make EVs more cheap. This article delves further into the PMSM's design and operation. It will discuss how intriguing the laws of physics work with various sorts of motor construction. 

 A permanent magnet synchronous motor (PMSM) is a hybrid of an induction motor and a brushless DC motor, and it has a better power density than an induction motor. It features a permanent magnet rotor and windings on the stator, just like a brushless DC motor. However, the stator construction with windings designed to create a sinusoidal flux density in the machine's air gap is similar to that of an induction motor. Due to their advantages, permanent synchronous motors are a very popular solution in electrical drives. PMSM exhibits best performance because of its characteristics such as high power density, high efficiency, lower mass and lower moment of inertia. 

 Working Principle :  

The PMSM motor operates on the same principle as the synchronous motor. PMSM motors begin as squirrel-cage induction motors. A rotating magnetic field is created in the air-gap when the three-phase winding of the stator is energised by the three-phase power source. At synchronous speed, the rotor field magnetically locks with the stator poles, producing torque and allowing the rotor to continue rotating.        

                             

Motor Construction and Types 

A permanent magnet synchronous motor, like any rotating electric motor, consists of a rotor and a stator. The stator is the fixed part. The rotor is the rotating part. The permanent magnets are mounted on the rotor and the rotor doesn&#;t have any field winding.  

The permanent magnets are used to create field poles. The permanent magnets used in the motor are made up of samarium-cobalt and medium, iron, and boron because of their higher permeability. The most widely used permanent magnet is neodymium-boron-iron because of its effective cost and ease of availability. 

1. Classification of PMSM Motors based on Rotor Design 

The rotor consists of permanent magnets. Materials with high coercive force are used as permanent magnets. 

According to the rotor design, synchronous motors are divided into: 

• electric motors with salient pole rotor; 
• electric motors with non-salient pole rotor. 

They are also be classified  into: 

• interior permanent magnet synchronous motor 

In this type of construction, the permanent magnet is embedded into the rotor as shown in the figure below. It is suitable for high-speed applications and gets robustness. Reluctance torque is due to the saliency of the motor. 

• surface permanent magnet synchronous motor: 

In this construction, the magnet is mounted on the surface of the rotor. It is suited for high-speed applications, as it is not robust. It provides a uniform air gap because the permeability of the permanent magnet and the air gap is the same. No reluctance torque, high dynamic performance, and suitable for high-speed devices like robotics and tool drives. 

 

                                                                                                      

2. Classification of PMSM Motors based on Stator Design 

The stator consists of an outer frame and a core with windings. The most common design with two- and three-phase winding. 

Depending on the stator design, a permanent magnet synchronous motor can be: 

• with distributed winding; 
• with concentrated winding. 

 Working 

• The working of PMSM depends on the rotating magnetic field of the stator and the constant magnetic field of the rotor. The permanent magnets are used as the rotor to create constant magnetic flux that operates and locks at synchronous speed.  
• The phasor groups are formed by joining the windings of the stator with one another. These phasor groups are joined together to form different connections like a star, Delta, double and single phases. To reduce harmonic voltages, the windings should be wound shortly with each other. 
• When the 3-phase AC supply is given to the stator, it creates a rotating magnetic field and the constant magnetic field is induced due to the permanent magnet of the rotor. This rotor operates in synchronism with the synchronous speed. The whole working of the PMSM depends on the air gap between the stator and rotor with no load. 
• If the air gap is large, then the windage losses of the motor will be reduced. The field poles created by the permanent magnet are salient. The permanent magnet synchronous motors are not self-starting motors. So, it is necessary to control the variable frequency of the stator electronically. 

Wrapping Up 

With recent advancements in solid state electronics, processors, and intelligent computing, the permanent magnet synchronous motor (PMSM) is gaining traction in the field of high performance drives. The advantages of permanent magnet synchronous motors are their simple structure, compact size, great efficiency, and high power factor. The benefits of PM machines have lately made them very appealing candidates for 'direct drive' applications such as hybrid electric vehicles (HEV) and electric cars (EV). 

It's no surprise that PMSM motors have swiftly risen to prominence in EVs today. They provide everything an electric vehicle needs, from higher power to enhanced safety and efficiency. 

If you are looking for more details, kindly visit Permanent Magnet Motor Manufacturer for Large Chemical Plants.