阅读说明：本技术 无刷直流电机无传感器控制装置与控制方法 (Sensorless control device and control method for brushless direct current motor ) 是由 卜云 魏海峰 王浩陈 张懿 于 2019-10-31 设计创作，主要内容包括：本发明公开了一种无刷直流电机无传感器控制装置,包括：分压滤波模块、比较器模块、控制器、驱动器模块、逆变器模块,其中：分压滤波模块和无刷直流电机三相绕组相连；比较器模块和分压滤波模块相连；控制器分别和分压滤波模块、比较器模块以及驱动器模块相连；驱动器模块和逆变器模块相连；逆变器模块和无刷直流电机三相绕组相连。本发明通过改进电路将因消磁产生的假过零点剥离出,并单独送入控制器处理,这种方法适应性强、对电路改动要求小。(The invention discloses a sensorless control device of a brushless direct current motor, which comprises: partial pressure filtering module, comparator module, controller, driver module, inverter module, wherein: the voltage division filtering module is connected with a three-phase winding of the brushless direct current motor; the comparator module is connected with the voltage division filtering module; the controller is respectively connected with the voltage division filtering module, the comparator module and the driver module; the driver module is connected with the inverter module; the inverter module is connected with the three-phase winding of the brushless direct current motor. The invention strips out the false zero crossing point generated by demagnetization by improving the circuit and independently sends the false zero crossing point to the controller for processing, and the method has strong adaptability and small requirement on circuit modification.)

1. A sensorless control apparatus for a brushless dc motor, comprising: partial pressure filtering module, comparator module, controller, driver module, inverter module, wherein:

the voltage division filtering module is connected with the three-phase winding of the brushless direct current motor and is used for outputting the collected terminal voltage of the three-phase winding of the brushless direct current motor after voltage division filtering; the comparator module is connected with the voltage division filtering module and is used for converting the output signal of the voltage division filtering module into a square wave signal to be output; the controller is respectively connected with the voltage division filtering module, the comparator module and the driver module and is used for analyzing and processing an output signal of the voltage division filtering module and an output signal of the comparator module, and the controller outputs a driving signal to the driver module based on the output signal of the voltage division filtering module and the output signal of the comparator module; the driver module is connected with the inverter module and is used for driving the power device in the inverter module to be switched on and off; and the inverter module is connected with the three-phase winding of the brushless direct current motor and is used for realizing the phase change operation of the brushless direct current motor.

2. The sensorless control apparatus of a brushless dc motor of claim 1 wherein the controller inputs comprise a first set of IO ports and a second set of IO ports; the first group of IO ports are connected with the output of the voltage division filtering module, and the functions of the first group of IO ports are set as external interrupt capture functions and used for capturing the rising edge and the falling edge of the output signal of the voltage division filtering module; and the second group of IO ports are connected with the output of the comparator module, and the function of the second group of IO ports is set as a common input function and is used for acquiring the high and low level change of the output signal of the comparator module.

3. The sensorless control apparatus of a brushless dc motor of claim 1 wherein the comparator module is selected as a general purpose comparator having a propagation delay greater than 5 μ β.

4. The sensorless control apparatus of a brushless dc motor according to claim 1 or 3, wherein a reference voltage of the comparator module is 0.05V to 0.1V larger than the controller-captured external-capture interrupt trigger voltage.

5. A sensorless control method of a brushless direct current motor is characterized by comprising the following steps:

step 1: acquiring an output signal of a comparator module and an output signal of a voltage division filtering module within a preset time;

step 2: judging whether the output signal level of the comparator module changes, and executing the step 31 when the output signal level of the comparator module changes; when the output signal level of the comparator module is not changed, executing the step 1;

judging whether the edge signal of the output signal of the partial pressure filtering module is captured or not, and executing the step 32 when the edge signal of the output signal of the partial pressure filtering module is captured; when the edge signal of the output signal of the voltage division filtering module is not captured, executing the step 1;

step 31: judging whether to change the phase according to the phase change flag bit, and executing phase change and executing the step 1 when the phase change flag bit allows phase change; when the commutation flag bit is not allowed to commutate, not executing commutation and executing step 1;

step 32: and switching the commutation flag bit between allowing commutation and not allowing commutation and executing the step 1.

6. The sensorless control method of a brushless dc motor according to claim 5, wherein the specific method of switching the commutation flag between allowable commutation and unallowable commutation in step 32 is as follows:

in a preset time, when an edge signal of an output signal of the voltage division filtering module is captured for the first time, the phase change flag bit is switched to disallow phase change; and when the edge signal of the output signal of the voltage division filtering module is captured for the second time, the phase change flag bit is switched to allow phase change.

7. The sensorless control method of a brushless dc motor according to claim 5 or 6, wherein the preset time is 50 μ s to 100 μ s.

Technical Field

The invention relates to the field of brushless direct current motor control. And more particularly, to a control method and apparatus for a brushless dc motor to overcome the influence of demagnetization in sensorless control.

Background

The brushless direct current motor is a permanent magnet synchronous motor and has the advantages of high efficiency, fast response, low noise and the like. Therefore, brushless dc motors have been widely used in more and more industries.

When the brushless direct current motor is driven and controlled by adopting sensorless square waves, the rotor position information is obtained by means of back electromotive force or collected phase voltage, and the phase change information is obtained by means of the zero crossing point of the back electromotive force. When the brushless direct current motor works in a loading mode, the inductive characteristic of the stator winding enables the floating phase to have electric energy, so that demagnetization can be generated; and the demagnetization phenomenon can bring false zero crossing points, so that the phase change information generates errors and influences the control performance. At present, the common practice is to eliminate the false zero crossing point through hardware filtering, or eliminate the false zero crossing point through software filtering; when the load of the brushless direct current motor is increased to cause the demagnetization phenomenon to be aggravated, the situation that false zero-crossing points cannot be completely eliminated can occur in hardware filtering, the false zero-crossing points cannot be eliminated if filtering parameters cannot be accurately adjusted through software filtering, and the difficulty in accurately adjusting the filtering parameters is high.

Aiming at the problem, the invention strips out the false zero crossing point generated by demagnetization by improving the circuit, and independently sends the false zero crossing point to the controller for processing, and controls that the phase commutation is not allowed when the demagnetization event acts, so as to avoid the impression of the phase commutation from the false zero crossing point.

Disclosure of Invention

The invention provides a sensorless control device and a sensorless control method for a brushless direct current motor, which are used for solving the problem that in sensorless control of the brushless direct current motor in the existing production, a false zero crossing phenomenon is generated due to demagnetization to interfere phase change of the brushless direct current motor.

The invention provides a sensorless control device of a brushless direct current motor, which comprises: partial pressure filtering module, comparator module, controller, driver module, inverter module, wherein:

the voltage division filtering module is connected with the three-phase winding of the brushless direct current motor and is used for outputting the collected terminal voltage of the three-phase winding of the brushless direct current motor after voltage division filtering; the comparator module is connected with the voltage division filtering module and is used for converting the output signal of the voltage division filtering module into a square wave signal to be output; the controller is respectively connected with the voltage division filtering module, the comparator module and the driver module and is used for analyzing and processing an output signal of the voltage division filtering module and an output signal of the comparator module, and the controller outputs a driving signal to the driver module based on the output signal of the voltage division filtering module and the output signal of the comparator module; the driver module is connected with the inverter module and is used for driving the power device in the inverter module to be switched on and off; and the inverter module is connected with the three-phase winding of the brushless direct current motor and is used for realizing the phase change operation of the brushless direct current motor.

Optionally, the input of the controller includes a first group of IO ports and a second group of IO ports; the first group of IO ports are connected with the output of the voltage division filtering module, and the functions of the first group of IO ports are set as external interrupt capture functions and used for capturing the rising edge and the falling edge of the output signal of the voltage division filtering module; and the second group of IO ports are connected with the output of the comparator module, and the function of the second group of IO ports is set as a common input function and is used for acquiring the high and low level change of the output signal of the comparator module.

Optionally, the comparator module is a general comparator with a propagation delay greater than 5 μ s.

Optionally, the reference voltage of the comparator module is 0.05V to 0.1V greater than the controller capture external capture interrupt trigger voltage.

The invention provides a sensorless control method of a brushless direct current motor, which comprises the following steps:

step 1: acquiring an output signal of a comparator module and an output signal of a voltage division filtering module within a preset time;

step 2: judging whether the output signal level of the comparator module changes, and executing the step 31 when the output signal level of the comparator module changes; when the output signal level of the comparator module is not changed, executing the step 1;

judging whether the edge signal of the output signal of the partial pressure filtering module is captured or not, and executing the step 32 when the edge signal of the output signal of the partial pressure filtering module is captured; when the edge signal of the output signal of the voltage division filtering module is not captured, executing the step 1;

step 31: judging whether to change the phase according to the phase change flag bit, and executing phase change and executing the step 1 when the phase change flag bit allows phase change; when the commutation flag bit is not allowed to commutate, not executing commutation and executing step 1;

step 32: and switching the commutation flag bit between allowing commutation and not allowing commutation and executing the step 1.

Optionally, a specific method for switching the commutation flag bit between allowing commutation and disallowing commutation is as follows:

in a preset time, when an edge signal of an output signal of the voltage division filtering module is captured for the first time, the phase change flag bit is switched to disallow phase change; and when the edge signal of the output signal of the voltage division filtering module is captured for the second time, the phase change flag bit is switched to allow phase change.

Optionally, the preset time is 50 μ s to 100 μ s.

The invention at least comprises the following beneficial effects:

1. through the improvement of the traditional sensorless acquisition circuit of the device, the signal after filter pressing is sent to the comparator module for processing and is also directly sent to the controller for processing, and the degaussing pulse signal extraction is realized.

2. The degaussing pulse signal can be extracted by the controller by using an external interrupt capture function through the characteristic that the pulse signal of the degaussing phenomenon can be captured by external interrupt while the normal zero-crossing phenomenon cannot be captured by the external interrupt.

3. Through the serial working characteristics of the controller, the demagnetization pulse signal can be extracted by using the external interruption capturing function, the phase-changing function is locked in the action time of the demagnetization pulse signal, the influence of demagnetization is effectively avoided, and the demagnetization condition under different load conditions can be treated. In a word, the device has the advantages of simple circuit modification, no addition of any component, simple control method and strong adaptability.

Drawings

The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and not to be construed as limiting the invention in any way, and in which:

FIG. 1 is a schematic circuit diagram of a sensorless control apparatus for a brushless DC motor according to an embodiment of the present invention;

FIG. 2 is a flow chart of a sensorless control method for a brushless DC motor according to an embodiment of the present invention;

fig. 3 is a diagram showing various points of a specific circuit of the brushless dc motor according to the embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

As shown in fig. 1, the present invention provides a sensorless control apparatus for a brushless dc motor, comprising: a voltage division filter module 51, a comparator module 52, a controller 53, a driver module 54, an inverter module 55, wherein:

the voltage division filtering module 51 is connected with the three-phase winding of the brushless direct current motor and is used for dividing and filtering the acquired terminal voltage of the three-phase winding of the brushless direct current motor and outputting the voltage; the comparator module 52 is connected to the voltage division filtering module 51, and is configured to convert an output signal of the voltage division filtering module 51 into a square wave signal for output; the controller 53 is respectively connected to the voltage division filtering module 51, the comparator module 52 and the driver module 54, and is configured to analyze and process an output signal of the voltage division filtering module 51 and an output signal of the comparator module 52, and output a driving signal to the driver module 54; the driver module 54 is connected to the inverter module 55, and is configured to drive the power devices in the inverter module 55 to be turned on or off; the inverter module 55 is connected to the three-phase winding of the brushless dc motor for implementing a phase-change operation of the brushless dc motor.

Optionally, the input of the controller 53 includes a first group of IO ports and a second group of IO ports; the first group of IO ports is connected to the output of the voltage division filtering module 51, and the first group of IO ports is set to be an external interrupt capture function, and is used to capture a rising edge and a falling edge of an output signal of the voltage division filtering module 51; the second group of IO ports is connected to the output of the comparator module 52, and the function of the second group of IO ports is set as a normal input function, and is used for detecting the high-low level change of the output signal of the comparator module 52.

The test point CS1 is connected to the W-phase input end of the voltage division filter module 51; the test point CS2 is connected with the W-phase output end of the voltage division filter module 51; test point CS3 is connected to the W-phase output of comparator block 52.

As shown in fig. 2, the present invention provides a sensorless control method for a brushless dc motor, comprising:

step S1: acquiring an output signal of a comparator module and an output signal of a voltage division filtering module within a preset time;

step S2: judging whether the output signal level of the comparator module changes, and executing step S31 when the output signal level of the comparator module changes; when the output signal level of the comparator module is not changed, executing step S1;

judging whether the edge signal of the output signal of the partial pressure filtering module is captured or not, and executing the step S32 when the edge signal of the output signal of the partial pressure filtering module is captured; when the edge signal of the output signal of the partial pressure filtering module is not captured, executing step S1;

step S31: judging whether to change the phase according to the phase change flag bit, and executing phase change and executing step S1 when the phase change flag bit is phase change allowed; when the commutation flag is not allowed to commute, not performing commutation and performing step S1;

step S32: the commutation flag is switched between the permission of commutation and the non-permission of commutation and step S1 is executed.

The degaussing pulse signal can be extracted by the controller by using an external interrupt capture function through the characteristic that the pulse signal of the degaussing phenomenon can be captured by external interrupt while the normal zero-crossing phenomenon cannot be captured by the external interrupt. The degaussing pulse is composed of a rising edge signal and a falling edge signal, and the phase commutation is not allowed between the two edge signals, so that the influence of the degaussing phenomenon on the phase commutation can be avoided.

Fig. 3 is a diagram showing various points of a specific circuit of the brushless dc motor according to the embodiment of the present invention. Fig. 3(a) is an output waveform of test point CS1, corresponding to a phase voltage waveform of a W-phase stator winding; fig. 3(b) is an output waveform of the test point CS2, which corresponds to the output waveform of the voltage-dividing filter module 51 of the W-phase stator winding; fig. 3(c) is an output waveform of the test point CS3, corresponding to the output waveform of the comparator block 52 for the W-phase stator winding.