How a drive will perform DC-Brake on an Induction motor?

In DC breaking VFD injects DC current in stator of Motor & with that DC current Stator will try to lock the rotor , Thee will be stationary field instead of rotating field in between stator & Rotor of Motor.

This is DC breaking i.e. DC injection, we have been used this application in cranes for increasing starting torque & in some handloom machine for breaking applications where mechanical breaks are not available or suitable.

DC Brake function is most commonly used to hold the motor in stand still position. Will not truly lock the rotor thus cannot replace for example mechanical brake in lifting applications. In horizontal movement it is often good enough for holding the mechanical system still for short period of time. Pls keep in mind the the induction motor without forced cooling will heat up.
Other place where DC injection is used is for example lifting application to secure the appropriate magnetization of the motor before releasing mechanicl brake. Without premagnetization of the motor, the remanent flux may result to inadequate torque and causing rotor not to follow the "new flux" immediately. This may cause dropping of load in lifting applications when opening the mechanical brake. Using DC injection will allow the AC Drive to know what the actual flux in motor is when starting to generate torque by introducing frequency to the stator.

In the DC Brakes, some of the factories use NdFeB magnets to help the brake to reache the high quality.

High performance drive make a measurment of the torque throught the current to control the brake, for other it's based on speed reference. Then it depend if you use the brake to stand still the motor or decelerate the motor and stop him....
When using a DC brake always clearly define what you want to do(stand still or decelerate), then if it's a safety material, then check drive control type.
Hope it help a bit !

Thank you for your Comments. I want to Know about IGBT commands and PWM algorithm during DC Injection currentFirst i want to know does DC current inject to 3 phase or only 2 phase of motor stator?

I assume that if you inject 2, 3rd returns the injected sum current to inveter.

It is interesting how many of the question can be interpreted so many different ways. This happens in so many of the posts. No wonder people are confused by machines and drives, we aren't very careful with our terms sometimes. Anyway, yes we tend to call lots of things DC braking. DC injection braking, which might be a better term for what you are asking about, can be done by chopping basically the half cycle, or if you can the DC bus, one polarity (DC) on one or 2 phases to the third. The voltage is going to be relatively low compared to rated voltage depending on torque you are looking for (and current rating of the modules). From memory, I think we are talking 1/4 or less voltage to keep the current down. (I don't commonly calculate that any more). You need to worry about the motor and the modules. The value of DC injection braking, as a means of braking, is questionable but maybe you have good reason for wanting it. Keep in mind it is NOT a holding brake. Torque decreases with speed. Initial current is high. Depending on duty cycle be careful using one phase because uneven heating in the motor, especially if you can drive the current wel above rated. Probably the advantage is that I don't think the DC bus is pumped up like it is if you simply decelerate by lowering the frequency. One way you dump heat energy into the motor and the other into a bracking resistor or regen it back to the grid. But at the same time you have limited torque for the device current available., either way I guess. This would be a good calculation study fornsomeone to determine which is more effective for a given current. I think you might get more torque decelerating. I hope i didnt confuse things. Good luck.

ِDuring DC injection Braking, one phase connected to +DC BUS or - DC Bus (IGBT command remain High or Low [for Example U Phase of motor]. and PWM perform on other phases. isn't it? if its OK,How is PWM done on two other phases?

If one "connects" the motor to the DC bus (devices "full" on) you cannot control current. The DC value applied to the motor is controlled by PWMing much like a DC drive. One can put voltage on 2 leads, with no voltage on the third or one can apply +DC to 2 leads with -DC on the third (or the opposite). Both events occur normally for an instant during normal sine wave operation. Both methods provide different results. Both are controlled.

Can you tell me more about this?

is there a tech. great at PLC's and drives, interested in working based in W. MA., and working thruoghout New England

If it is a holding break you could use an external relay controlled by the drive or a separate switch.