Why can a DC motor be both an electric motor and a generator

General DC motors.

There are parallel excitation, series excitation and compound excitation, and we will not say much about the use of DC motors; Now let's talk about the use of generators, in fact, it uses the remanence principle of the motor rotor; When the DC motor rotates at high speed under the drag of an external force, the magnetic field lines of the magnetic field generated by the remanence of the rotor.

The cutting nail coil generates a voltage, which in turn further excites the rotor, creating a stronger magnetic field and therefore a higher voltage until the output voltage reaches equilibrium. This is how DC motors are used as generators. FYI.

Still wondering if you can satisfy your curiosity about this topic?

The structure of the electric motor is the same as that of the generator.

The motor uses electricity to generate force, that is, electricity generates magnetism.

The generator uses force to generate electricity, which is magnetic electricity.

The difference between AC and DC is commutators, which are generally used in DC motors and generators.

When the coil is turned at a certain angle (e.g. 90), the function of the commutator is to change the current direction of the coil, so that the direct current can be continuously supplied and the motor rotates.

When the coil turns at a certain angle (90), the direction of the generated magnetic field (which can be assumed to be a bar magnet) also changes due to the change in the direction of the coil current, so that the coil will continue to be stressed, so that the motor rotates.

When it is critical, it turns by inertia.

The generator principle is the reverse process of an electric motor.

1. The working principle is different:

The alternator is made according to the principle of electromagnetic induction, that is, whether it is the movement of the conductor (coil), the rental of the diesel generator or the movement of the magnetic field, as long as there is a relative movement between the conductor (coil) and the magnetic field, and the conductor (coil) cuts the magnetic field lines, it will generate electromotive force in the conductor (coil), that is, it can be called electricity generation when it moves; The DC motor is made according to the principle that the current-carrying conductor (coil) moves under force in the magnetic field, that is, it can be called electric only when it is energized.

2. The structure is different

The alternator coil is connected to a copper ring (slip ring) at each end, that is, the brush; The DC motor coil is connected to a copper half-ring at both ends called a commutator, which plays a reversing role in the current of each winding, so that the alternating current becomes direct current.

3. The direction judgment is different

The alternator induces the direction of the electromotive force, which is determined by the right-hand rule; The direction of rotation of the DC motor is determined by the left-handed rule.

4. The conversion of energy is different

The alternator inputs mechanical energy and outputs electrical energy; Diesel generator rental is a rotating machine that converts mechanical energy into electrical energy; The DC motor inputs electrical energy and outputs mechanical energy, that is, the transfer motor that converts electrical energy into mechanical energy.

DC motor performance correlation.

1. DC separately excited motor: there is no electric connection between the excitation winding and the armature, and the excitation circuit is supplied by another DC power supply. Therefore, the excitation current is not affected by the armature terminal voltage or the armature current.

2. DC parallel excitation motor: the circuit is parallel, shunt, and the voltage at both ends of the parallel excitation winding is the voltage at both ends of the armature, but the excitation winding is wound with a thin wire, and its turns are many, so it has a large resistance, so that the excitation current through him is smaller.

3. DC series excitation motor: the current is connected in series, the voltage divider, and the excitation winding are connected in series with the armature, so the magnetic field in this motor changes significantly with the change of armature current. In order to prevent large losses and voltage drops in the excitation winding, the smaller the resistance of the excitation winding, the better, so the DC series motor is usually wound with a thicker wire, and his turns are less.

4. DC compound excitation motor: The magnetic flux of the motor is generated by the excitation current in the two windings.

The above content refers to Encyclopedia - DC Motor.

Encyclopedia - Generator.

When the DC power supply is supplied to the armature winding through the brush, the conductor under the n pole on the surface of the armature can flow through the current in the same direction, and the conductor will be subjected to the torque in the counterclockwise direction according to the left-hand rule; The conductor under the S pole on the surface of the armature also flows through the current in the same direction, and the conductor will also be subjected to a moment in the counterclockwise direction according to the left-handed rule.

In this way, the entire armature winding, i.e. the rotor, will rotate counterclockwise, and the input DC energy will be converted into the mechanical energy output on the rotor shaft.

Hello, 1. The motor and generator are composed of magnets, coils, commutators, brushes, etc., and the connection between the components is basically the same, and the components are connected in series by connecting the circuit. 2. There are magnets in the composition of the motor and the generator, so both will be affected by the direction of the magnetic field, and the direction of the current is related to the direction of the magnetic field, so the direction of the force of the coil in the motor and the generator is related to the direction of the magnetic field. 3. Their working principle is different, first of all, the generator is made according to the electromagnetic induction phenomenon, and the generator is made according to the principle of force movement of the energized conductor in the magnetic field, and secondly, the judgment method of the motor and the generator is different, the judgment of the current direction in the general generator usually uses the right-hand rule, and the direction of the conductor's force movement in the magnetic field in the motor is generally the left-hand rule.

4. The purpose of work and the conversion of energy are different, the generator generally needs to do work from the outside world, so as to convert mechanical energy into electrical energy, while the motor is the opposite, it needs to work on the outside world, so as to convert electrical energy into mechanical energy. 5. Summary: The structure is the same.

The components are connected in the same way. Each component is connected in series to form a circuit. All are affected by the direction of the magnetic field, and the direction of the current generated in the generator is related to the direction of the magnetic field; The direction of force on the coil in the motor is related to the direction of the magnetic field.

The principle is different. The method of judging is different. The purpose of work and the transformation of energy are different.

The former is an energized conductor that rotates under force in a magnetic field; The latter is a rotating conductor that cuts the magnetic field lines in a magnetic field to produce an electric potential. DC motor: the control principle of the brushless DC motor, in order to make the motor rotate, the first control part must be based on the position of the motor rotor sensed by the hall-sensor, and then decide the order of opening (or closing) the power transistor in the inverter according to the stator winding, AH, BH, CH (these are called upper arm power transistors) and AL, BL, CL (these are called lower DC brushless motor arm power transistors), The current flows sequentially through the motor coil to generate a forward (or reverse) rotating magnetic field, and interacts with the rotor's magnet, so that the motor rotates clockwise and counter-clockwise.

When the motor rotor rotates to the position where the hall-sensor induces another set of signals, the control unit turns on the next set of power transistors, so that the circulating motor can continue to rotate in the same direction until the control department decides to stop the motor rotor and then turn off the power transistors (or only open the lower arm power transistor); If the motor rotor is reversed, the power transistor will be turned on in the opposite order. Hey hey

There is no difference in structure between DC generators and DC motors. A DC generator is a machine where the prime mover drags the armature to rotate and emits direct current, which will be fed.

Mechanical energy is converted into direct current energy; The DC motor inputs DC electrical energy, which makes the armature rotate and drag other machinery to convert electrical energy into mechanical energy. If driven by a prime mover, the DC motor will generate electricity; If you connect the DC generator to.

DC power supply, it is equivalent to an electric motor.

DC motors are divided into excitation magnetism and self-excitation magnetism. The structure of the DC motor is an excitation coil, an armature coil. The excitation coil is also the stator winding. The armature coil is the rotor winding. When two voltages are applied at the same time, the tinplate effect is generated, and the reaction force operates.

It excites the magnet, that is, it provides voltage to the excitation winding externally. Generally, it is only used by motors with relatively large power to excite magnets.

Self-excited magnetism is to provide an excitation magnetic field internally. (Induction) Generally, the motor with relatively small power uses self-excited magnets.

The DC motors are all carbon brushed. In order for the armature voltage to be transmitted to the rotor of the motor to make the rotor turn, then carbon brushes are required. Like the small motor in ***, it just doesn't have carbon brushes, but it has two pieces of metal copper touching the rotor.

This is done to the voltage and current.

Therefore, the DC motor must have carbon brushes. It's just a difference in size, and the way it comes into contact with the material.

It excites the magnetic DC motor to generate a large amount of electricity.

The self-excited magnetic DC motor generates a relatively small amount of electricity.

Because it excites the magnet and the excitation voltage is externally supplied. Generally, it excites the magnetic DC motor to provide a voltage of 180V externally. When you turn the motor quickly with your hands, then the armature circuit becomes a generator, and the voltage can reach about 100V.

The voltage of the power generation is obtained by the individual test. The voltage of the power generation is affected by the speed of the rotor of the rotating motor. The motor rotates stably.

Then the voltage is stable.

Naturally, the power generation of DC motors cannot be compared with professional generators. Because the internal magnetic field loss of the motor is large. The output duty cycle is naturally also high. Therefore, it is unreliable to use DC motor as a generator. It's okay to do experiments and solve the problem of temporary power shortage.

DC motors are divided into brushed and brushless motors! The brushless is magnetic, and the power generation efficiency is a little higher! The structure of the brushless DC motor is basically the same as that of the generator, except that the generator has a cooling fan!

DC motors are inherently reversible.

It's just that each has its own focus on the structure.

If you're trying to experiment or use it temporarily, just find the right motive force.

Structure comparison: The structure of DC generator and DC motor is exactly the same.

The operating conditions are different: the DC generator is to turn the alternating electromotive force induced in the armature coil into a DC electromotive force from the brush end by the commutator and the commutation action of the brush. Whereas, a DC motor is a rotating device that converts direct current energy into mechanical energy.

The stator of the motor provides the magnetic field, the DC power supply provides the current to the windings of the rotor, and the commutator keeps the direction of the rotor current and the torque generated by the magnetic field.

Different brush positions: In order to improve the commutation and minimize the influence of electric sparks on the commutator, the brush positions of DC generators and DC motors are different. If you want to change the generator to an electric motor, you must readjust the position of the brushes; In the same way, if you want to change the motor to a generator, you must also readjust the position of the brushes.

Adjustment of brushes: The position of the brushes should be on the physical centerline at an angle offset from the geometric centerline.

=Please refer to it.

The internal structure of DC motor and generator is basically the same, theoretically it is possible to use it upside down, but it is too heavy to be used when manufacturing, and it is definitely not easy to use when used upside down. Many things can be used upside down, such as a speaker can be used as a microphone, and when the microphone is powered on, it will also produce sound. This is called reversibility.