How much do you know about air conditioner motors

How much do you know about air conditioner motors

1. The principle of air conditioner compressor motor

　　1, single-phase asynchronous motor

　　 The single-phase compressor for air conditioner has two windings, namely the start winding and the running winding (main winding), and three terminals, which are the common end, the start end, and the running end. Generally, it is driven by the capacitor operation type and implements constant speed control.

　　From the start of the motor to the normal operation, a capacitor is always connected in series to the secondary winding circuit, so that the electrical appliance has good operating performance, high efficiency and power factor, and reliable operation.

　　2, three-phase asynchronous motor

　　 Its structure is similar to that of a single-phase motor. The difference is that the stator of a three-phase motor is composed of 3 sets of completely symmetrical windings. These three windings are embedded in the stator core slots and are spaced apart by 120° in electrical degrees.

The three windings can be connected into a Y-shape or a △-shape. When three-phase symmetrical current is passed into the stator winding (that is, the three-phase current differs by 120° in electrical degrees in time and phase), the stator, The air gap between the rotors generates a rotating magnetic field, which causes the rotor to generate electromagnetic torque due to electromagnetic induction.

　　Three-phase asynchronous motor has a simple structure and excellent performance. Its torque, efficiency and power factor are higher than single-phase asynchronous motors. Therefore, the compressors of larger power air conditioners, such as cabinet air conditioners, mostly use three-phase asynchronous motors.

　　3, frequency conversion motor

　　 As long as the power frequency of the asynchronous motor is changed, different motor speeds can be obtained.

　　 Frequency conversion speed regulation can not only realize smooth speed regulation, but also has a wide range of speed regulation, high efficiency, fast response, low starting current, little impact on the power grid, and good comfort performance. It is an energy-saving ideal speed regulation method.

　　Especially heat pump type air conditioners, which can control the amount of heat produced by the heat pump through variable frequency speed regulation, without being restricted by the outdoor temperature, thus greatly improving its heating capacity.

　　 Inverter working process: Inverter generally adopts indirect frequency conversion (AC-DC-AC) mode, which consists of two processes, rectification and inverter.

　　 The power frequency (50Hz) grid current is preprocessed by power supply filtering, etc., and then sent to a rectifier module (such as a diode rectifier bridge), and the rectified DC power is directly input to the inverter module (such as an IPM module with IGBT as the basic component).

　　 The inverter module converts the DC power into AC power of different frequencies under the action of the drive signal of the CPU chip, and supplies the compressor to work.

　　IPM inverter module working principle: IPM module uses IGBT (insulated gate bipolar transistor) as the switching element. 　　 The six drive signals sent by the CPU (that is, as IGBT base signals) respectively control the on and off of the six IGBT switches of the three-phase inverter circuit.

　　 In each cycle, every 60° in turn controls the on and off of each IGBT in a certain order, so as to obtain a certain frequency of three-phase alternating current at the output of the inverter circuit.

　　 By controlling the length of the IGBT switch on and off time (that is, controlling the pulse width of the positive half cycle and negative half cycle of each phase), alternating current of different frequencies can be obtained at the output of the three phases.

　　 2. The principle of air conditioner fan motor

　　 The air conditioner fan motor is generally a single-phase asynchronous motor, using PSC connection mode.

　　According to the needs of use, the fan motor can be adjusted in speed. The speed adjustment methods include: stator winding tapped speed control, thyristor speed control, etc.

　　 1. Tap-type speed regulation

　　The working voltage on the main winding is changed by changing the number of turns of the motor stator winding, so as to achieve the purpose of changing the magnetic flux and adjusting the speed. The stator winding of the PSC motor with tapped speed regulation consists of three parts: the main winding, the secondary winding and the middle winding (speed regulating winding).

　　2, SCR speed regulation

Thyristor, also known as thyristor, has two kinds of unidirectional thyristor and bidirectional thyristor. It has the characteristics of unidirectional thyristor. When the thyristor bears the positive anode voltage, the positive voltage is applied to the gate and there is a certain gate current When the component is turned on.

　　 When the tube is on, the gate will lose its function. When the thyristor is turned on, only when the positive anode voltage decreases to a certain value or the anode voltage becomes negative, the tube is cut off.

　　 Triac characteristics, when the tube is turned on, when the voltage drops below the minimum voltage to maintain the conduction or becomes reverse, the tube will be cut off and will not be turned on again until the next trigger signal (pulse signal) arrives.

　　Solid State Relay: SSR for short, it is a non-contact semiconductor relay using bidirectional thyristor.

　　 When a trigger signal is applied to the input terminal, the photo thyristor controls the load on and off.

In the speed regulation of the fan motor of the air conditioner, the high and low level output by the single-chip microcomputer is used as the trigger signal of the solid state relay, and the zero-crossing point of the power frequency sinusoidal current is detected through the auxiliary circuit, and the timing is controlled by the program, and then the load is turned on at a certain time的current.

　　 The thyristor is automatically cut off when the power current crosses the zero point, so that the load can obtain the required effective voltage. If this voltage is supplied to the motor, the voltage of the motor winding can be changed to obtain the corresponding speed.

　　 3. Principles of motors used in other air conditioners

　　1, stepping motor

　　Stepper motor is an actuator that converts electrical pulse signals into linear displacement or angular displacement, that is, when a pulse signal is applied to the motor, the motor moves by one step.

　　The rotor is a cylindrical two-pole permanent magnet rotor made of permanent magnets. The inner circle of the stator is eccentric to the outer circle of the rotor, so the air gap is uneven, and the air gap is the smallest, that is, the magnetic resistance is the smallest.

　　 There is a concentrated winding in the stator armature, the two ends of the winding are added with electric pulse signal by the special power supply. When the stator winding is not energized, there is magnetic flux generated by the permanent magnet rotor in the magnetic circuit of the motor.

　　This magnetic flux will make the axis of the rotor poles tend to the position where the magnetic resistance is the smallest in the magnetic circuit.

　　When the power supply adds a pulse to the motor windings, the two magnetic poles of the stator and the two magnetic poles of the rotor repel each other, and the rotor rotates counterclockwise about 180° in the direction of arrow n until the stator magnetic poles are opposite to the opposite poles of the rotor magnetic poles.

　　2, permanent magnet synchronous motor

　　The micromotor used on the swing blade device of the air outlet grille of the air conditioner is a permanent magnet synchronous claw pole self-starting synchronous motor.

　　The motor drive voltage is ~220V/50Hz. Its stator is composed of a cup-shaped casing, a toroidal single-phase coil and a claw pole piece; the rotor is a ferrite ring with high coercivity.

　　 The claw poles are evenly distributed along the circumference, and the number of claw pole pairs (magnetic pole pairs) is determined by the required synchronous speed. The swing motor has many claw pole pairs, low speed, large torque, low output power, simple structure and no fixed steering.

　　The master switch is usually installed on the control panel of the air conditioner. It is a power switch for turning on compressors, fans and other executive equipment, and it is also a selection switch for switching the operating state of the air conditioner.