ACM6753 motor driver chip - advantages of sine wave control
Time:2023-02-15
Views:1324
ACM6753 is a 18V/3A three-phase non-inductive BLDC (brushless DC) motor drive IC, 180 ˚ Sine, integrated drive algorithm+pre-drive+MOS, built-in current detection, fully integrated SOC scheme, no external MOS, only a few resistors and capacitors for peripheral devices. It is widely used in efficient and silent applications such as fans, water pumps and cooling fans.
What is the difference between sine wave control and square wave control?
01 What is a DC brushless motor?
Brushless DC motor is developed on the basis of brushless DC motor. It has the advantages of stepless speed regulation, wide speed regulation range, strong overload capacity, good linearity, long service life, small size, light weight, large output, and solves a series of problems existing in the brushless motor. Because the brushless motor has no brush for automatic commutation, it needs to use an electronic commutator for commutation. Brushless DC motor driver realizes the function of this electronic commutator.
02 Control mode of brushless motor
At present, the control of brushless DC motor is mainly divided into two categories: square wave control (trapezoidal wave control) and sine wave control. What are the principles of these two types of control methods?
(1) Square wave control: obtain the position of the motor rotor through the Hall sensor, and then conduct 6 commutations (once every 60 ° commutation) in 360 ° electrical cycle according to the position of the rotor. Each commutation position motor outputs a force in a specific direction, so it can be said that the position accuracy of square wave control is electrical 60 °. Because the phase current waveform of the motor is close to square wave under this control mode, it is called square wave control.
(2) Sine wave control: SVPWM wave is used, 3-phase sine wave voltage is output, and motor phase current is sine wave current. It can be considered that many continuous commutations have been carried out in one electrical cycle without sudden change of commutation current. Obviously, compared with square wave control, sine wave control has less torque fluctuation and less current harmonics, which makes it more "delicate" to control.
03 Characteristics of square wave and sine wave
Square wave control features
(1) The price is cheap. The driver algorithm is simple, the development difficulty is low, the development cost is low, and the hardware cost is lower than the chord wave control cost;
(2) Acceleration and deceleration are simple and rough, similar to slamming the accelerator, but also easy to overshoot;
(3) The matching motor is simple, with low requirements for motor Hall phase, phase inductance and phase resistance;
Chord wave control features
(1) Stable operation and small torque fluctuation. Similar to servo control, the operation effect is smooth, and it is not easy to fluctuate due to load changes;
(2) More stable and reliable, with long service life. The sine wave control can avoid the impact of peak current, while the square wave control can easily generate peak current, which will impact the mos tube and motor, and easily affect the service life;
(3) Quiet, low noise. When the motor is running, the square wave control can obviously hear the "squeaking" current sound, and the chord wave control current sound is very small;
(4) High efficiency, energy saving and emission reduction. The sine wave control is more effective than the square wave control, and the current required to output the same power is lower;
(5) The algorithm is difficult and the cost is higher than that of square wave control;
04 How to choose square wave and sine wave drive
Since there are two control modes of brushless motor: sine wave and square wave, how to choose?
(1) There is no high requirement for operation effect, performance, stability and reliability, and the pursuit of low cost and selection of square wave driver;
(2) If you want to have good operation effect, high stability and reliability, mute, low power consumption and high efficiency, select the sine wave driver;
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