What is the principle of motor braking for DC energy consumption?

Electric motor energy consumption braking principle:

The stator winding of the motor is cut off from the AC power supply, and its two terminals are immediately connected to the DC power supply (when Y, the two-phase stator winding is connected; When connected, a one-phase stator winding is connected, and the other two-phase series winding is connected), and the DC current generates a stationary magnetic field in the stator winding. The rotor is still turning due to mechanical inertia. As a result, the rotor windings induce an electromotive force and generate an induced current.

The motor is in the state of power generation, and its electromagnetic torque is opposite to the direction of rotation of the rotor, which plays a braking role.

Energy consumption braking is divided into energy consumption braking of DC motor and energy consumption braking of AC motor.

Energy consumption braking of DC motors:

If the external armature voltage U suddenly drops to zero when the motor is running in the electric state, and the armature is connected in series with an additional resistor R, that is, the two ends of the armature are disconnected from the grid and quickly connected to an appropriate resistor. The motor is in the generator running state, and the kinetic energy of the rotating part is converted into electrical energy and consumed on the resistor. With the consumption of kinetic energy, the speed decreases, and the braking torque is also getting smaller and smaller, so this braking method is relatively large when the speed is still relatively high, and with the decrease of the speed, the braking effect also decreases.

Energy consumption braking of AC motors:

In the normal operation of the motor, in order to stop quickly, not only disconnect the three-phase AC power supply, but also connect the DC power supply in the stator coil, and enter the DC current in the stator coil to form a magnetic field, the rotor continues to rotate and cut the magnetic field due to inertia, and the induced electromotive force and current are formed in the rotor, and the direction of torque generated is opposite to the rotation direction of the motor, which produces a braking effect, and finally stops the motor.

Hello The principle of AC motor energy consumption braking is that the stator winding of the motor is cut off from the AC, and its two terminals are immediately connected to the DC power supply (when Y is connected, the two-phase stator winding is connected; When connected, a one-phase stator winding is connected, and the other two-phase series winding is connected), and the DC current generates a stationary magnetic field in the stator winding. The rotor is still turning due to mechanical inertia. Therefore, the rotor induces an electromotive force around the hand vertical group, and generates an induced current, and the electric Bi Xun large machine is in a state of power generation, and its electromagnetic torque is opposite to the rotation direction of the rotor, which plays a braking role.

Energy consumption braking: After the motor is separated from the three-phase AC power supply, the stator winding is connected with a constant current voltage, that is, the stator winding is connected with a DC current, and the rotor induced current and the static magnetic field are used to achieve the purpose of braking.

Summary. When the three-phase asynchronous motor stops, a DC current not greater than the rated current is introduced at the input end of the stator two-phase power supply instantaneously, and a magnetic field is generated to make the rotor produce braking torque, which is the DC braking of the motor.

When the three-phase asynchronous motor stops, the three-phase asynchronous motor instantaneously enters the DC current of the rated current at the input end of the two-phase power supply of the stator, which generates a magnetic field to make the rotor produce braking torque, which is the DC braking of the motor. Travelers.

Brushless DC motor braking is usually the use of the motor itself for fast braking, there are two simple methods, one is energy consumption braking, the other is short-circuit braking, energy consumption braking is to consume the kinetic energy of the motor on the external braking resistor, short-circuit hungry braking is to consume the kinetic energy of the motor on the stator winding of the motor. Obviously, energy-powered braking is more beneficial for reducing the heat generated by the motor. However, short-circuit braking does not require any changes to the hardware, and simple and convenient is its outstanding advantage, so the focus is on short-circuit braking.

The so-called short-circuit braking means that the driving MOS tube of the motor can be made when braking, and the upper bridge arm (or lower bridge arm) is all turned on and the lower bridge arm (or upper bridge arm) is cut off, and the three-phase stator winding of the motor is all short-circuited. When a motor is in a state of power generation, it is equivalent to a short circuit in the power supply. Because the resistance of the winding is relatively small, it can generate a large short-circuit current, and the kinetic energy of the motor is quickly released, so that the motor instantaneously produces a large braking torque, which can achieve the effect of rapid braking.

The higher the speed of the motor, the greater the short-circuit current and the greater the braking force. However, it is necessary to consider that it is not possible to exceed the bearing capacity of the MOS tube, so it is common to wait for the motor speed to decrease to a certain extent before using short-circuit braking.

That's it<>

<> characteristics of three-phase asynchronous motor and three-phase new connection pattern.

The rotational speed formula for the three asynchronous motors and explains the definition of each symbol.

Wiring diagram. The speed formula of the three-phase asynchronous motor is n=60f p (1-s), where f is the power supply frequency, p is the pole pair, and s is the slip rate <>

Among the various braking methods of DC motors, the method that consumes the most electric energy is reverse braking.

Talking about braking method of DC motor:

1.Reverse braking: the power cords at both ends of the motor are reversed, so that the motor rotates in the opposite direction, and the rotating energy is dissipated through the resistance of the motor, so as to achieve braking.

2.Excitation degaussing braking: When the motor stops inputting electric power, disconnect the armature circuit and the excitation circuit, and commute the motor in time to rotate in situ, and the back electromotive force of the generator braking forms an additional resistance, and the electric energy is consumed in a relatively short period of time, so as to achieve braking.

3.Mechanical cornering braking: braking is achieved by means of brake shoes or clutches.

4.Electromagnetic braking: According to the principle of electromagnetic induction, when the motor speed is high, the electric energy is converted into mechanical energy through the electromagnetic circuit for braking.

Question: The use of DC motors:

1.Industrial field: including machine tools, cranes, conveyor belts, mixers, die-casting machines, injection molding machines, textiles, printing and dyeing, etc.

2.Agriculture: including pumps, fans, lawn mowers, harvesters, etc.

3.Transportation: including electric and hybrid vehicles, electric trains, elevators, escalators, etc.

4.Household appliances: including refrigerators, washing machines, range hoods, vacuum cleaners, etc.

5.Information technology field: including computers, printers, copiers, etc.

6.Military field: including aircraft, fighter jets, missiles, radar, navigation, etc.

First, the steps are different.

1. DC motor electric: the control department must be based on the position of the motor rotor sensed by the hall-sensor, and then turn on according to the stator winding decision, so that the current flows through the motor coil in order to generate a forward (or reverse) rotating magnetic field, and interacts with the magnet of the rotor, so that the motor can rotate clockwise and counter-clock.

2. DC motor braking: When the output frequency of the inverter is close to zero and the motor speed is reduced to a certain value, the inverter redirects to the stator winding of the asynchronous motor to pass DC to form a static magnetic field.

Second, the principle is different.

1. DC motor electric: because the resistance and inductance of the armature circuit of the motor are small, and the rotating body has a certain mechanical inertia, when the motor is connected to the power supply, the armature speed and the corresponding back electromotive force in the starting stage are very small, and the starting current is very large. Up to 15 to 20 times the rated current.

This current can cause disturbances to the power grid, mechanical shocks to the units, and sparks to the commutators.

2. DC motor braking: when DC current is introduced into the stator winding of the asynchronous motor, the generated magnetic field will be a constant magnetic field with constant spatial position, and the rotor continues to rotate at its original speed due to inertia, and the rotating rotor cuts the static magnetic field to produce braking torque, and the kinetic energy stored by the system is converted into electric energy and consumed in the rotor circuit of the motor, so as to achieve the effect of rapid braking of the motor.

x-bce-process=image%2fresize%2cm_lfit%2cw_600%2ch_800%2climit_1%2fquality%2cq_85%2fformat%2cf_auto"esrc="

3. Different applicability.

1. DC motor electric: all machinery that starts under heavy load or requires uniform adjustment of speed, such as large reversible rolling mills, winches, electric locomotives, trams, etc.

2. DC motor braking: it is required to be stable and impact-free, and the parking is accurate, such as knitting, sewing, lifting, hoisting, etc.; Braking the motor before starting to eliminate irregular rotation caused by external factors, such as large fans, etc.;

target="_blank"title="Encyclopedia - DC braking"Encyclopedia - DC braking

target="_blank"title="Encyclopedia - DC motor"Encyclopedia - DC motor

Briefly describe the realization method and principle of energy consumption braking of DC separately excited motor: dear, hello! Glad to answer for you!!

Energy consumption braking, that is, after the motor is separated from the three-phase AC power supply, a DC voltage is added to the stator winding, that is, DC current is introduced, and the rotor induced current and the effect of static magnetic field are used to achieve the purpose of braking. Energy braking is a widely used method of electrical braking. When the motor is separated from the three-phase AC power supply, the DC power supply is immediately connected to the two-phase winding of the stator, and the DC current flows through the winding, generating a stationary DC magnetic field.

At this time, the rotor of the motor cuts the DC magnetic flux and generates an induced current. Under the interaction between the stationary magnetic field and the induced current, a braking torque is generated that hinders the rotation of the rotor, so the speed of the motor decreases rapidly, so as to achieve the purpose of braking. When the speed drops to zero, there is no relative movement between the rotor conductor and the magnetic field, the induced current disappears, the motor stops, and then the DC power supply is cut and removed, and the braking is over.

The characteristics of energy consumption braking: reverse braking torque is large, braking effect is remarkable, but there is impact braking when braking is stable and energy loss is large, energy consumption braking is stable and accurate compared with reverse braking, braking is stable, accurate, energy consumption is small, but the braking distance is weak, especially at low speed, the braking effect is poor, and it is also hungry to provide DC power supply. I hope mine is helpful to you and I wish you a happy life.

Motor energy consumption braking principle: the stator winding of the motor is cut off from the AC power supply, and its two terminals are immediately connected to the DC power supply (when Y is connected, the two-phase stator winding is connected; When connected, a friend scatter-phase stator winding is connected, and the other two-phase series winding is connected), and the DC current generates a static magnetic field in the stator winding. Due to the inertia of the machine, the rotor is still rotating.

Therefore, the rotor induces an electromotive force around the combustion group and generates an induced current, and the motor is in a state of power generation, and its electromagnetic torque is opposite to the rotation direction of the rotor, which plays a braking role.

Answers]: a, c, d

According to the relevant content of P95 "Energy Consumption Braking" and Table 24-6 of the "Iron and Steel Enterprise Electric Power Design Pants Manual" (Volume II) and Table 24-6, the energy consumption braking of the asynchronous motor is to disconnect the stator winding of the motor in operation from the AC power supply and change it to the DC power supply for energy consumption braking. At this point, a constant magnetic field is generated in the stator windings, and an induced current is generated in the rotating rotor windings. The constant magnetic field of the stator interacts with the induced current of the rotor, which generates braking torque, which makes the motor stop quickly.

The characteristics are: the braking torque is smooth, and the braking torque can be easily changed; The braking torque decreases with the decrease of speed; It can make the production machinery stop more reliably; Energy cannot be fed back into the grid, and the efficiency is low.