CN107171605A - A BLDCM two-two conduction and three-three conduction switching method - Google Patents

Abstract

The invention discloses a switching method of two-second conduction and three-third conduction of a BLDCM (brushless direct current motor). The driving signals of the two-second conduction and the three-third conduction of the brushless direct current motor are respectively formed by carrying out logic operation on an inherent Hall position signal of the motor by utilizing a DSP (digital signal processor) and a CPLD (complex programmable logic device). And then, the DSP sends out a path of step signal, and the step signal is sent into the CPLD to be used as a switching signal of two-two conduction and three-three conduction programs. And (3) building a module on the CPLD, enabling the step signal and the two-two conduction program module to be partially ANDed, enabling the non-AND three-three conduction program module of the signal to be ANDed, and then performing OR logic on the results after the two logics, wherein the signal outputs a two-two conduction drive when the step signal is at a high level, outputs a three-three conduction drive when the step signal is at a low level, and has natural program switching. The invention provides a switching method for two-to-two conduction and three-to-three conduction of a brushless direct current motor. The method can realize the natural switching of two conduction modes of the brushless direct current motor under the condition of not increasing hardware equipment.

Description

A BLDCM two-two conduction and three-three conduction switching method

technical field

The invention relates to the field of brushless direct current (BLDCM: BrushLess DC Motor) motor control, in particular to a method for realizing stable switching between two-two conduction modes and three-three conduction modes of brushless motors by using step signals.

Background technique

Electric vehicles have the advantages of energy saving, high efficiency, no pollution, and a wide range of energy sources, so there are more and more electric vehicles driven by brushless DC motors. At present, scholars' research on brushless motors is mostly two-two conduction mode, and there are few studies on three-three conduction, so scholars have little research on the switching method of brushless DC motors in two conduction modes. At present, a method is needed to realize the natural switching of the two modulation modes by means of software programming. Therefore, the two-two conduction and three-three conduction switching methods using the step signal as the switching signal came into being.

Contents of the invention

The purpose of the present invention is to provide a BLDCM two-two conduction and three-three conduction switching method applicable to the field of high-precision control of brushless DC motors through software programming.

In order to achieve the above object, the following technical solutions are adopted: the present invention mainly includes a brushless DC motor with a position sensor, a DSP chip, and a CPLD module. In three seconds, after the speed of the brushless DC motor is stable, switch to the three-three conduction mode. The specific steps are as follows:

Step 1, use the Hall position signal of the brushless DC motor, the DSP chip, and the CPLD module to logically calculate the program modules for two-two conduction and three-three conduction; the main logic modules are programmed in the CPLD.

Step 2, let the brushless DC motor switch from two-two conduction to three-three conduction operation mode at 3s, write a delay function in the main function of the DSP chip, so that the DSP chip sends a high level for the first three seconds, A step signal that continues to be low level after three seconds;

Step 3, sending the step signal sent by the DSP chip in step 2 to the CPLD module as the switching signal of the two conduction modes;

Step 4, two-two conduction program module and step signal in step 2 do AND logic, three-three conduction program module and step signal in step 2 do AND logic, and then do the result after the above logic Or logic; the first three seconds of the result of the or logic is the two-two conduction drive signal, and three seconds later it is the three-three conduction drive signal. This drive signal is output on the CPLD module as the drive signal of the motor inverter.

Compared with the prior art, the inventive method has the following advantages:

1. In order to realize the switching between the two conduction modes only by software programming, it saves the development cost.

2. The step signal is used as the switching control signal of the two conduction signals, so that the switching between the two is natural and the motor jitter is small.

3. By adjusting the number of changes in the high and low levels of the step signal, the brushless DC motor can be switched arbitrarily in the two conduction modes.

Description of drawings

Fig. 1 is a sector division diagram of the brushless DC motor of the present invention.

Fig. 2 is a diagram of two conduction modes formed by the Hall position signal DSP and CPLD of the present invention.

Fig. 3 is a step signal diagram of a brushless DC motor driven by a three-phase inverter of the present invention.

Fig. 4 is a diagram of the step signal sent by the DSP of the present invention.

detailed description

The present invention will be further described below in conjunction with accompanying drawing:

The purpose of the present invention is to utilize DSP and Hall signal on the basis of existing brushless direct current motor control system, make it form two groups of program modules in CPLD through the direct logic of Hall signal and the timing and operation of DSP, two Two conduction program modules and three three conduction program modules. Then use the step signal as logic to realize switching between the above two conduction modes.

Specific steps are as follows:

Step 1, use the Hall position signal of the brushless DC motor, the DSP chip, and the CPLD module to logically calculate the program modules for two-two conduction and three-three conduction; the main logic modules are programmed in the CPLD.

Step 2, let the brushless DC motor switch from two-two conduction to three-three conduction operation mode at 3s, write a delay function in the main function of the DSP chip, so that the DSP chip sends a high level for the first three seconds, A step signal that continues to be low level after three seconds;

Step 3, sending the step signal sent by the DSP chip in step 2 to the CPLD module as the switching signal of the two conduction modes;

Step 4, two-two conduction program module and step signal in step 2 do AND logic, three-three conduction program module and step signal in step 2 do AND logic, and then do the result after the above logic Or logic; the first three seconds of the result of the or logic is the two-two conduction drive signal, and three seconds later it is the three-three conduction drive signal. This drive signal is output on the CPLD module as the drive signal of the motor inverter.

As shown in Figure 1, two conduction mode program modules are formed by Hall position signals DSP and CPLD. Through the simulation analysis, it can be known that the optimal switching time between the two-two conduction and the three-three conduction of the brushless DC motor is at the commutation off time, so that the minimum torque ripple can be obtained. This switching point can be the starting point of any one of the six sectors. At the same time, in order to keep the motor running smoothly after starting, choose to switch between two and three conduction when the motor has just started and the speed is close to the rated speed. When the electrical angle rotates one circle, it rotates 2π to return to the second and third conduction switching points, and then calculates from the electrical angle 0 position, and cycles in turn.

As shown in Figure 2, the brushless DC motor is driven by a three-phase inverter, with a total of six switching tubes, each of which is controlled individually. The program module of the two-two conduction mode and the program module of the three-three conduction mode shown in FIG. 1 output six signals.

As shown in Figure 3, the DSP sends out a step signal that is high level for the first three seconds and low level after three seconds. And send this step signal into CPLD.

As shown in Figure 4, the step signal sent by DSP and the program modules of two-two conduction mode and three-three conduction mode are implemented in CPLD as logic. Since the three-phase inverter has a total of six switching tubes, and each switching tube is controlled independently, the program module of the two-two conduction mode and the program module of the three-three conduction mode shown in Figure 4 actually output six signals, here Use one signal instead.

The above-mentioned embodiments are only descriptions of preferred implementations of the present invention, and are not intended to limit the scope of the present invention. All such modifications and improvements should fall within the scope of protection defined by the claims of the present invention.

Claims (1)

1. A kind of BLDCM two two conduction and three three conduction switching methods, mainly comprise the brushless DC motor with position sensor, DSP chip, CPLD module, it is characterized in that, described method is to allow brushless DC motor earlier During the three seconds of running in the two-two conduction mode, after the speed of the brushless DC motor is stable, switch to the three-three conduction mode. The specific steps are as follows: Step 1, use the Hall position signal of the brushless DC motor, the DSP chip, and the CPLD module to logically calculate the program modules for two-two conduction and three-three conduction; Step 2, let the brushless DC motor switch from two-two conduction to three-three conduction operation mode at 3s, write a delay function in the main function of the DSP chip, so that the DSP chip sends a high level for the first three seconds, A step signal that continues to be low level after three seconds; Step 3, sending the step signal sent by the DSP chip in step 2 to the CPLD module as the switching signal of the two conduction modes; Step 4, two-two conduction program module and the step signal in step 2 do AND logic, three-three conduction program module and step signal in step 2 do NAND logic, and then do the result after the above logic Or logic; the first three seconds of the result of the or logic is the two-two conduction drive signal, and three seconds later it is the three-three conduction drive signal. This drive signal is output on the CPLD module as the drive signal of the motor inverter.