阅读说明：本技术 无刷电机及其控制系统及控制方法 (Brushless motor and control system and control method thereof ) 是由 秦锐锋 谢国权 曲涛 于 2018-07-23 设计创作，主要内容包括：本申请提供一种无刷电机及其控制系统及控制方法。该控制方法包括：根据输入指令获得向电机的功率驱动电路输出的脉宽调制信号所需要的输入占空比；若所述输入占空比大于第一阈值,向电机的功率驱动电路输出具有第一占空比的脉宽调制信号,所述第一占空比为100％。实施本发明,可降低电子开关的功率损耗,以及降低电机的成本。(The application provides a brushless motor and a control system and a control method thereof. The control method comprises the following steps: obtaining an input duty ratio required by a pulse width modulation signal output to a power driving circuit of the motor according to an input instruction; and if the input duty ratio is larger than a first threshold value, outputting a pulse width modulation signal with a first duty ratio to a power driving circuit of the motor, wherein the first duty ratio is 100%. The invention can reduce the power loss of the electronic switch and the cost of the motor.)

1. A control method of a brushless motor, comprising:

obtaining an input duty ratio required by a pulse width modulation signal output to a power driving circuit of the motor according to an input instruction;

and if the input duty ratio is larger than a first threshold value, outputting a pulse width modulation signal with a first duty ratio to a power driving circuit of the motor, wherein the first duty ratio is 100%.

2. The control method of a brushless motor according to claim 1, wherein the first threshold value is less than 99%.

3. The method of claim 1, wherein the pulse width modulation signal having the input duty ratio is outputted to a power driving circuit of the motor if the input duty ratio is between the first threshold and a second threshold, wherein the second threshold is smaller than the first threshold.

4. The method of claim 3, wherein a pulse width modulation signal having a second duty ratio is outputted to a power driving circuit of the motor if the input duty ratio is between the second threshold and a third threshold, wherein the third threshold is smaller than the second threshold, and the second duty ratio is 0.

5. The method of claim 4, wherein the pulse width modulation signal having a third duty cycle is output to a power driving circuit of the motor if the input duty cycle is between a third threshold and a fourth threshold, wherein the fourth threshold is less than the third threshold, and the third duty cycle is equal to or close to 100%.

6. A control system for a brushless motor, comprising:

the acquisition module is used for acquiring an input duty ratio required by a pulse width modulation signal output to a power driving circuit of the motor according to an input instruction;

the judging module is used for judging whether the input duty ratio is larger than a first threshold value or not;

and the adjusting module outputs a pulse width modulation signal with a first duty ratio to a power driving circuit of the motor if the input duty ratio is greater than a first threshold, wherein the first duty ratio is 100%.

7. The control system of a brushless motor of claim 6, wherein the first threshold is less than 99%.

8. The system of claim 7, wherein the adjustment module outputs a pulse width modulated signal having the input duty cycle to the power driver circuit of the motor if the input duty cycle is between the first threshold and a second threshold, wherein the second threshold is less than the first threshold.

9. The control system of claim 7, wherein the pulse width modulation signal having a second duty cycle is output to a power driving circuit of the motor if the input duty cycle is between the second threshold and a third threshold, wherein the third threshold is smaller than the second threshold, and the second duty cycle is 0.

10. The control system of claim 9, wherein a pulse width modulated signal having a third duty cycle is output to a power driving circuit of the motor if the input duty cycle is between the third threshold and a fourth threshold, wherein the fourth threshold is less than the third threshold, and wherein the third duty cycle is equal to or close to 100%.

11. A memory device having stored therein a plurality of instructions adapted to be loaded and executed by a processor:

obtaining an input duty ratio required by a pulse width modulation signal output to a power driving circuit of the motor according to an input instruction;

and if the input duty ratio is larger than a first threshold value, outputting a pulse width modulation signal with a first duty ratio to a power driving circuit of the motor, wherein the first duty ratio is 100%.

12. A brushless motor comprising:

a processor adapted to implement instructions; and

a storage device having stored therein a plurality of instructions adapted to be loaded and executed by a processor:

obtaining an input duty ratio required by a pulse width modulation signal output to a power driving circuit of the motor according to an input instruction;

and if the input duty ratio is larger than a first threshold value, outputting a pulse width modulation signal with a first duty ratio to a power driving circuit of the motor, wherein the first duty ratio is 100%.

[ technical field ] A method for producing a semiconductor device

The present invention relates to the field of control of brushless motors, and more particularly, to a control system and a control method of a brushless motor.

[ background of the invention ]

Brushless motors use electronic switches such as field effect transistors (mosfets) to effect commutation of the stator winding current. The average voltage and the average current of the motor can be controlled by a Pulse Width Modulation (PWM) method, thereby controlling the output of the motor, such as the output rotation speed, the output power, and the like of the motor. Because of the resistance of the electronic switch, there is conduction loss, i.e., heat is generated when conducting. Because the voltage and the current of the electronic switch are not abrupt change in the switching process, the electronic switch has switching loss. Conduction loss and switching loss both consume energy and increase temperature rise.

[ summary of the invention ]

Accordingly, there is a need for a control system and a control method that can reduce power loss of a brushless motor driving circuit.

A first aspect of the present invention provides a control method of a brushless motor, including:

obtaining an input duty ratio required by a pulse width modulation signal output to a power driving circuit of the motor according to an input instruction;

and if the input duty ratio is larger than a first threshold value, outputting a pulse width modulation signal with a first duty ratio to a power driving circuit of the motor, wherein the first duty ratio is 100%.

Further, the first threshold is less than 99%.

Further, if the input duty ratio is between the first threshold value and a second threshold value, outputting a pulse width modulation signal with the input duty ratio to a power driving circuit of the motor, wherein the second threshold value is smaller than the first threshold value.

Further, if the input duty ratio is between the second threshold and a third threshold, outputting a pulse width modulation signal with a second duty ratio to a power driving circuit of the motor, where the third threshold is smaller than the second threshold, and the second duty ratio is 0.

Further, if the input duty ratio is between the third threshold and a fourth threshold, outputting a pulse width modulation signal with a third duty ratio to a power driving circuit of the motor, where the fourth threshold is smaller than the third threshold, and the third duty ratio is equal to or close to 100%.

A second aspect of the present invention provides a control system of a brushless motor, comprising:

the acquisition module is used for acquiring an input duty ratio required by a pulse width modulation signal output to a power driving circuit of the motor according to an input instruction;

the judging module is used for judging whether the input duty ratio is larger than a first threshold value or not;

and the adjusting module outputs a pulse width modulation signal with a first duty ratio to a power driving circuit of the motor if the input duty ratio is greater than a first threshold, wherein the first duty ratio is 100%.

Further, the first threshold is between 60% -90%.

Further, if the input duty ratio is between the first threshold and a second threshold, the adjusting module outputs a pulse width modulation signal with the input duty ratio to a power driving circuit of the motor, wherein the second threshold is smaller than the first threshold.

Further, if the input duty ratio is between the second threshold and a third threshold, outputting a pulse width modulation signal with a second duty ratio to a power driving circuit of the motor, where the third threshold is smaller than the second threshold, and the second duty ratio is 0.

Further, if the input duty ratio is between the third threshold and a fourth threshold, outputting a pulse width modulation signal with a third duty ratio to a power driving circuit of the motor, where the fourth threshold is smaller than the third threshold, and the third duty ratio is equal to or close to 100%.

A third aspect of the invention provides a memory device having stored therein a plurality of instructions adapted to be loaded and executed by a processor:

obtaining an input duty ratio required by a pulse width modulation signal output to a power driving circuit of the motor according to an input instruction;

and if the input duty ratio is larger than a first threshold value, outputting a pulse width modulation signal with a first duty ratio to a power driving circuit of the motor, wherein the first duty ratio is 100%.

A fourth aspect of the present invention provides a brushless motor comprising:

a processor adapted to implement instructions; and

a storage device having stored therein a plurality of instructions adapted to be loaded and executed by a processor:

obtaining an input duty ratio required by a pulse width modulation signal output to a power driving circuit of the motor according to an input instruction;

and if the input duty ratio is larger than a first threshold value, outputting a pulse width modulation signal with a first duty ratio to a power driving circuit of the motor, wherein the first duty ratio is 100%.

By adopting the embodiment of the invention, when the input duty ratio is higher than the first threshold value, the motor is controlled to run at full speed, a high-energy-consumption area of the electronic switch can be avoided, and the power loss of the electronic switch is reduced, so that the energy-saving effect of the electronic switch is achieved, the packaging size of the electronic switch and the size of the radiator are reduced, the power density is improved, and the cost of the motor is reduced.

[ description of the drawings ]

Fig. 1 is a schematic flowchart of a control method of a brushless motor according to a first embodiment of the present invention;

fig. 2 is a flowchart illustrating a method for controlling a brushless motor according to a second embodiment of the present invention;

FIG. 3 is a graph of power loss of a Mosfet versus duty cycle of a PWM;

fig. 4 is a flowchart illustrating a method for controlling a brushless motor according to a third embodiment of the present invention;

FIG. 5 is a schematic diagram of motor speed versus input duty cycle for the embodiment shown in FIG. 4;

fig. 6 is a flowchart illustrating a method for controlling a brushless motor according to a fourth embodiment of the present invention;

FIG. 7 is a schematic diagram of motor speed versus input duty cycle for the embodiment of FIG. 6;

fig. 8 is a schematic block diagram of a control system of a brushless motor according to an embodiment of the present invention.

[ detailed description ] embodiments

The invention is further described below with reference to the figures and examples.

The control system of the present invention is suitable for controlling a brushless motor, such as a three-phase brushless dc motor, which may be suitable for use in pumps, fans, engine cooling modules, and the like. The power driving circuit of the motor generally includes a plurality of semiconductor switching elements, such as 4, 6, etc., and converts a voltage from a power source into an alternating current to supply to the motor under the control of the controller to drive the motor to operate.

Referring to fig. 1, a flowchart of a method for controlling a brushless motor according to a first embodiment of the present invention is shown. The control method comprises the following steps:

and step S101, obtaining an input duty ratio required by a pulse width modulation signal output to a power driving circuit of the motor according to the input instruction.

It will be appreciated by those skilled in the art that the input command may have different forms depending on the equipment to which the brushless motor is applied, for example, when the brushless motor is used to drive a fan, the input command may be the wind speed or the wind speed gear of the fan. When the brushless motor is adapted to a cooling module of an engine, the input command may correspond to a temperature of the engine.

And step S103, when the input duty ratio is larger than a first threshold value, outputting a pulse width modulation signal with a first duty ratio to a power driving circuit of the motor. The first duty cycle is greater than the input duty cycle, and preferably, the first duty cycle is 100%. The brushless motor operates at full speed when driven with the pulse width modulated signal at the first duty cycle. Alternatively, the first duty cycle is close to 100%, and in the present specification and claims, "close to 100%" refers to the following situation: between 99% and 100% (inclusive), such as 99%, 99.5%, 99.9%, etc.

In the present invention, the first threshold may be set to any value less than 99%, for example, may be generally set to any value between 60% and 90%, such as 60%, 65%, 70%, 75%, 80%, 85% or 90%, etc., although other suitable values, such as 40% and 50%, are also possible. In this embodiment, the first threshold is assumed to be 70%.

Fig. 2 is a flowchart of a control method of a brushless motor according to a second embodiment of the present invention. The control method comprises steps S201, S202, S203 and S205, wherein the step S201 is the same as the step S101 of the method shown in FIG. 1, namely, the input duty ratio required by the pulse width modulation signal output to the power driving circuit of the motor is obtained according to the input command.

Step S202, judging whether the input duty ratio is larger than a first threshold value, if so, the process goes to step S203; otherwise, the flow advances to step S205.

Step S203, a pulse width modulation signal having a first duty ratio is output to a power driving circuit of the motor. Preferably, the first duty cycle is 100%. The brushless motor operates at full speed when driven with the pulse width modulated signal at the first duty cycle.

Step S205 outputs a pulse width modulation signal having an input duty ratio to a power driving circuit of the motor.

Fig. 3 shows the relationship between the power loss of Mosfet and the duty ratio of the pulse width modulation signal (PWM) output to the power driving circuit of the motor, where the horizontal axis represents the duty ratio of the pulse width modulation signal, the vertical axis represents the power loss of Mosfet, the curve Lc represents the conduction loss of Mosfet, the curve Ls represents the switching loss of Mosfet, and the curve Lt represents the sum of the conduction loss and the switching loss of Mosfet.

As can be seen from fig. 3, when the input duty ratio is greater than the first threshold (e.g. 70%), since the brushless motor is driven with the first duty ratio (e.g. 100%), the switching loss Ls of the Mosfet is close to 0, and the overall power loss Lt of the Mosfet is substantially equal to the conduction loss Lc of the Mosfet, so as to avoid the high energy consumption region of the Mosfet (the region where the duty ratio ranges from 70% to 100%), thereby reducing the power loss of the electronic switch.

As can also be seen from fig. 3, by implementing the present invention, when the duty ratio required for the rotation speed of the motor is greater than the first threshold value, since the actual duty ratio is adjusted to 100% (i.e., the first duty ratio), the energy loss is smaller than that when the duty ratio is the first threshold value.

Fig. 4 is a flowchart of a control method of a brushless motor according to a third embodiment of the present invention. The control method comprises the following steps:

steps S301, S302, S303, S304, S305, and step S307, wherein steps S301, S302, S303, and S305 are respectively the same as steps S201, S202, S203, and S205 shown in fig. 2, and are not repeated here. In step S302, it is determined whether the input duty ratio is greater than a first threshold, and if the input duty ratio is greater than the first threshold, the process proceeds to step S303; otherwise, the flow advances to step S304.

Step S304, it is determined whether the input duty ratio is between a second threshold and a first threshold, where the second threshold is smaller than the first threshold. If so, the flow proceeds to S305, i.e., a pulse width modulation signal having an input duty ratio is output to a power driving circuit of the motor; if the input duty ratio is smaller than the second threshold value, the flow advances to step S307 to output a pulse width modulation signal having the second duty ratio to the power driving circuit of the motor. Preferably, the second duty cycle is 0. When the brushless motor is driven with the pulse width modulation signal of the second duty ratio, the brushless motor stops operating. In this embodiment, the interval in which the duty ratio is smaller than the second threshold provides a stop mode for the motor, and the motor is started only when the input duty ratio is larger than the second threshold, in this embodiment, the starting speed of the motor is 25%, in other embodiments, the starting speed of the motor may also be other suitable values, such as 20%, 30%, and the like.

In this embodiment, the relationship between the motor speed and the input duty ratio is shown in fig. 5.

Referring to fig. 5, when the input duty ratio is less than the second threshold value, a pulse width modulation signal having a second duty ratio (i.e., 0) is output to the power driving circuit of the motor, at which the motor rotation speed is 0. When the first duty is between the second threshold and the first threshold, a pulse width modulation signal having an input duty is output to a power driving circuit of the motor, and at this time, the motor rotation speed is changed with a change in the input duty. When the input duty cycle is greater than the first threshold, a pulse width modulated signal having a first duty cycle (i.e., 100%) is output to a power driving circuit of the motor, which is now rotating at full speed.

Fig. 6 is a flowchart of a method for controlling a brushless motor according to a fourth embodiment of the present invention. The control method comprises the following steps:

steps S401 to S407 and step S409, wherein steps S401 to S405 and S407 are respectively the same as steps S301 to S305 and S307 shown in fig. 4, and are not repeated here. Step S404, determining whether the input duty ratio is between a second threshold and a first threshold, wherein the second threshold is smaller than the first threshold. If so, the flow advances to S405; if not, the flow advances to step S406.

Step S406, determining whether the input duty ratio is between a third threshold and a second threshold, wherein the third threshold is smaller than the second threshold. If so, the flow advances to step S407. Otherwise, the flow advances to step S409.

Step S409, a pulse width modulation signal having a third duty ratio is output to the power driving circuit of the motor. Preferably, the third duty cycle is 100% and the brushless motor operates at full speed when the brushless motor is driven with the pulse width modulated signal of the third duty cycle. The interval in which the input duty cycle is smaller than the third threshold value provides an emergency mode for the motor, for example, in case the control signal of the motor is short-circuited to ground, the motor will be controlled to rotate at maximum speed.

In this embodiment, the relationship between the motor speed and the input duty ratio is shown in fig. 7.

In fig. 7, the horizontal axis represents an input duty ratio required to obtain a pulse width modulation signal output to a power drive circuit of the motor in accordance with an input command, and the vertical axis represents the motor rotation speed after the control method of the present invention is implemented. The input duty cycle and the speed of the brushless motor are both expressed in percentages.

It can be seen that when the input duty ratio is greater than the first threshold value, a pulse width modulation signal of a first duty ratio of 100% is output to the power driving circuit of the motor, and the brushless motor is driven with the pulse width modulation signal of the first duty ratio. When the brushless motor runs at full speed, the switching loss of the electronic switch tends to be 0, the whole power loss of the electronic switch is basically equal to the conduction loss, the high-energy-consumption area of the electronic switch can be avoided, and the power loss of the electronic switch and the motor driving circuit is reduced.

When the input duty ratio is between the second threshold value and the first threshold value, a pulse width modulation signal with the input duty ratio is output to a power driving circuit of the motor, and the brushless motor is driven by the pulse width modulation signal with the input duty ratio. As the input duty ratio increases, the rotational speed of the motor also increases, and as the input duty ratio decreases, the rotational speed of the motor also decreases.

When the input duty ratio is between the third threshold value and the second threshold value, a pulse width modulation signal of a second duty ratio (the duty ratio is 0) is output to a power driving circuit of the motor, and the brushless motor does not rotate.

When the input duty ratio is smaller than the third threshold value, the pulse width modulation signal with the third duty ratio is output to the power driving circuit of the motor, the value of the pulse width modulation signal is 100%, the brushless motor is driven by the pulse width modulation signal with the third duty ratio, and the motor rotates at full speed.

The invention can avoid the high energy consumption area of the electronic switch, reduce the power loss of the electronic switch, thereby achieving the energy-saving effect of the electronic switch.

Referring to fig. 8, a control system 100 for a brushless motor according to an embodiment of the present invention includes an obtaining module 10, a determining module 30, and an adjusting module 50. The control system 100 corresponds to a command execution mechanism, and is capable of receiving an input command and executing the input command, thereby realizing control of the operation of the motor, such as start, stop, and rotation speed adjustment, according to the input command. The input command may be generated by a control unit external to the electric machine, for example, in an engine cooling module, and the input command may be generated by an Engine Control Unit (ECU) and include desired motor state data, such as a desired speed range or a motor operating range.

The obtaining module 10 is configured to obtain an input duty ratio required by a pulse width modulation signal output to a power driving circuit of the motor according to an input instruction.

The determining module 30 is configured to determine a magnitude relationship between the input duty ratio and a preset threshold. The preset threshold value is related to the type of electronic switch (e.g. Mosfet) and/or the application scenario of the motor. In this embodiment, the preset threshold includes a first threshold, a second threshold, a third threshold, and a fourth threshold.

The adjusting module 50 is configured to perform corresponding processing according to the determination result of the determining module 30, for example, adjust a duty ratio required by a pulse width modulation signal output to a power driving circuit of the motor according to the determination result.

Specifically, the obtaining module 10 obtains an input duty ratio required by a pulse width modulation signal output to a power driving circuit of the motor according to the input instruction.

When the determining module 30 determines that the input duty ratio is greater than the first threshold, the adjusting module 50 adjusts a duty ratio required by the pulse width modulation signal output to the power driving circuit of the motor to be a first duty ratio, preferably, the first duty ratio is greater than the input duty ratio, and the first duty ratio is 100%. At this time, the brushless motor operates at full speed.

When the determining module 30 determines that the input duty ratio is between the second threshold and the first threshold, the adjusting module 50 adjusts the duty ratio required by the pulse width modulation signal output to the power driving circuit of the motor to be the input duty ratio, and at this time, the brushless motor operates with the pulse width modulation signal corresponding to the input duty ratio.

When the determining module 30 determines that the input duty ratio is between the third threshold and the second threshold, the adjusting module 50 adjusts the duty ratio required for the pulse width modulation signal output to the power driving circuit of the motor to be the second duty ratio, preferably, the second duty ratio is 0. At this time, the brushless motor corresponds to the stop mode, and does not operate.

When the determining module 30 determines that the input duty ratio is between the fourth threshold and the third threshold, the duty ratio required by the pulse width modulation signal output by the adjusting module 50 to the power driving circuit of the motor is a third duty ratio, preferably, the third duty ratio is 100%, and at this time, the brushless motor operates at full speed. At this time, the brushless motor is operated at full speed corresponding to the emergency mode.

It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes of the system and the module described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the several embodiments provided in the present application, it should be understood that the disclosed system and method may be implemented in other ways. For example, the above-described system embodiments are merely illustrative, and for example, the division of the modules is merely a logical division, and in actual implementation, there may be other divisions, for example, multiple modules or components may be combined or integrated into another system, or some features may be omitted, or not implemented. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The modules described as separate components may or may not be physically separate. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.

In addition, functional modules in the embodiments of the present invention may be integrated into one processing unit, or each module may exist alone physically, or two or more modules are integrated into one unit. The integrated module can be realized in a form of hardware or a form of a software functional unit.

The integrated module, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a processor to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.