r Design and analysis of power losses in micromotor cup rotors Shi Sizheng (Hubei University of Technology, Wuhan 430068, Hubei, China) When the current Jds flows through the conductor, the cross-sectional dimension of the conductor is much smaller than its length. If the distance from the survey point is r, then Its value: AC servo motor has two stators made of ferromagnetic material and an aluminum cup rotor. The magnetic field in the air gap in the motor's different working states The solution of equations (4), (5) gives the composite expression of the I, and the three partial vector positions in the diagram as:.
Here, from the definition of the sagittal position B = rotA, we have: (turning to page 34) the power loss in the micromotor cup rotor, the expression of the magnetic position function in the rotor, the integral constant determined by the boundary conditions, and the determination of the magnetic position function. Write the expression of power loss in the rotor, and finally derive the relationship between the loss of the cup rotor in the rotating magnetic field and the loss in the pulsating magnetic field, so that the former can be calculated from the latter.
Both the AC servo motor and the AC tachogenerator have the structure of a cup rotor. The cup rotor is mostly cast aluminum or copper. All of them are non-magnetic materials. The loss accounts for a large proportion and is worthy of further study.
In a non-magnetic (linear) medium, if the distribution of the current density j is known, the magnetic induction B generated by the current can be calculated by means of an auxiliary vector A (magnetic vector), which satisfies the following equation: Thus the magnetic induction B can be According to the continuity of the magnetic induction line: divB = 0, or calculated by the identity of the magnetic bit vector divrotA = 0. Given the distribution of the current density J, the value of the magnetic bit vector A can be calculated according to the following formula: from the alternating magnetic field that does not move to the elliptical or circular rotating magnetic field. This is a vertical section in the middle of the axial direction of the motor (xoz plane in the figure).
The rotor-type micromotor calculation diagram of the cup-shaped rotor is infinitely thin, and the surface current density is Jl (in the y-axis direction). The line load in the stator forms a standing wave that alternates with time on its surface. According to the symbol method, it can be expressed as: According to the relationship between the magnetic vector function and the current density of the wire, substituting the equation (3) into the Poisson equation can obtain: considering the Ohm's law J=7E for the current carrying rotor, : Sensorless Brushless DC Motor Stable Operation Control 34 SPEEDCOMP voltage is compared with a ramp oscillator to generate a PWM duty cycle for PWM pulse width modulation control. The ramp oscillator generates a sawtooth wave of 1.7 to 3.9V. The 1.7V clamp diode performs the sawtooth wave down-clamping. The frequency is determined by the grounding capacitor Ct. The PIL phase-locked loop is composed of the back-potential sampling, the voltage-controlled crystal, and the commutation control to ensure the stable operation of the motor.
Table 1 is the driving state of the six switching power tubes normally rotated by the motor, and the on-off triggering clock of the switch tube is provided by the oscillation frequency of the voltage-controlled crystal oscillator VCO.
Table Status Output Input and Output Sampling 2.5 It is necessary to ensure that the PWM speed is normal. The PWM operation mode can realize stepless smooth speed regulation. The PWM speed regulation directly affects the stable operation of the motor.
The same ML4425 as an example, the control method is: First, the use of 10kn adjustable potentiometer connected between Vre: and GND, the adjustable end connected SPEEDSET end, adjust the potentiometer speed control; second is the addition of digital-to-analog converter After DACs, microprocessors are used for speed control.
The speed control loop compensation connection is as shown. The speed setting signal from the SPEEDSET pin and the speed feedback signal from the SPEEDFB pin are compared and amplified by the error amplifier and the voltage is output to the SPEEDCOMP pin. This voltage is simultaneously applied by the 3.9V pull-up clamp diode and a 1.7V pull-down clamp diode. , clamped between 1~4.6V, the protection speed control loop will not be too tight.
(Continued from page 21) The normal component values ​​of the intensities are equal and the tangential component values ​​of the magnetic induction are zero.
The current density in the rotor is determined by: = 7E = - With the aid of the Poynting vector, the power loss in the rotor can be written as follows: value.
As the magnetic field rotates, its maximum value sequentially passes through the four-phase and C-phase terminal voltage waveforms of the rotor circumference. 4 phase, upper and lower arm drive waveform 4 conclusions from the above analysis shows that to maintain the position sensorless brushless DC motor in the start, operation, overload and other conditions of stable operation, we must ensure that the voltage control crystal to generate the appropriate operating frequency, With proper start-up procedures, the PLL phase-locked loop network and the PWM speed feedback network work properly.
A Semi-Flush Mount is a type of Lighting Fixture that is installed on the ceiling and hangs down slightly, but not as far as a Pendant Light. It is a popular choice for rooms with low ceilings, as it provides ample Lighting Product without taking up too much vertical space. Semi-Flush Mount Lighting come in a variety of styles and designs, from modern and sleek to more traditional and ornate. Semi-Flush Light are typically easy to install and can be used in a variety of settings, including bedrooms, living rooms, and kitchens.
Semi-Flush,Semi-Flush Mount,Semi-Flush Light,Semi Flush Mount,Semi-Flush Mount Lighting,Ceiling Mount Lighting,Ceiling Flush Mount Light Fixture,Led Ceiling Flush Mount Light
Zhengdong Lighting Co., Ltd. , https://www.sundint.com