阅读说明：本技术 电机反电势采样模块及采样方法 (Motor counter potential sampling module and sampling method ) 是由 李运生 邓海燕 陈晶杰 田丰 于 2019-12-13 设计创作，主要内容包括：本发明公开了一种电机反电势采样模块包括：电机驱动单元根据控制占空比输出PWM至驱动电路,驱动电路输出预设波形电机驱动电压,收到反电势采样中断信号停止输出PWM并持续Tbreak时长,Tbreak时长结束后输出PWM恢复预设波形电机驱动电压；电机控制单元根据目标转速和反电势计算的实际转速计算所需的控制占空比,将占空比输送至于电机驱动单元,每间隔(Twork+Tbreak)产生反电势采样中断信号至电机驱动单元和中断采样单元；中断采样单元计时Twait时长后进行电机端电压采样。本发明还公开了一种电机反电势采样方法。本发明使电机反电势采样不再受反电势采样频率限制和占空比限制,给车身稳定系统NVH问题的解决提供了更多空间。(The invention discloses a motor counter potential sampling module, which comprises: the motor driving unit outputs PWM to the driving circuit according to the control duty ratio, the driving circuit outputs preset waveform motor driving voltage, the back electromotive force sampling interrupt signal is received to stop outputting PWM and last for Tbreak time, and after the Tbreak time is over, the PWM is output to recover the preset waveform motor driving voltage; the motor control unit calculates a required control duty ratio according to the target rotating speed and the actual rotating speed calculated by the counter electromotive force, the duty ratio is transmitted to the motor driving unit, and counter electromotive force sampling interruption signals are generated to the motor driving unit and the interruption sampling unit every interval (Tway + Tbreak); and the interruption sampling unit samples the terminal voltage of the motor after timing Twait time. The invention also discloses a motor counter potential sampling method. The invention ensures that the back electromotive force sampling of the motor is not limited by the back electromotive force sampling frequency and the duty ratio any more, and provides more space for solving the NVH problem of the vehicle body stabilizing system.)

1. A motor back emf sampling module, comprising:

the motor driving unit is suitable for outputting PWM to the driving circuit according to the control duty ratio, the driving circuit outputs preset waveform motor driving voltage, the driving circuit stops outputting PWM after receiving a counter electromotive force sampling interrupt signal, the preset waveform motor driving voltage is reduced to zero and lasts for the Tbreak time length, and the PWM is output to recover the preset waveform motor driving voltage after the Tbreak time length is finished;

a motor control unit adapted to calculate a required control duty ratio from a target rotation speed and an actual rotation speed calculated from a back electromotive force, to supply the duty ratio to the motor driving unit, and adapted to generate a back electromotive force sampling interrupt signal to the motor driving unit and the interrupt sampling unit every interval (Twork + tbree);

the system comprises an interrupt sampling unit, a sampling unit and a sampling unit, wherein the interrupt sampling unit is suitable for sampling the terminal voltage of a motor after timing Twait duration;

wherein T is Twork + tbream, tbream is twoit + tsamping, T is a sampling period, Twork is a preset waveform motor driving voltage operating duration, tbream is an interruption duration, i.e., a duration of stopping outputting the preset waveform motor driving voltage, Twait is a back-potential sampling waiting duration, and tsamping is a back-potential sampling duration.

2. The motor back-emf sampling module of claim 1, wherein: the motor is a direct current brush motor.

3. The motor back-emf sampling module of claim 1, wherein: the motor back electromotive force sampling module is used for sampling the back electromotive force of the direct current brush motor of the vehicle body stabilizing system.

4. The motor back-emf sampling module of claim 1, wherein the motor drive circuit comprises:

the anode of the power supply is connected with the input end of the switching device through a load, and the cathode of the power supply is connected with the ground;

the output end of the switching device is respectively connected with the motor and the follow current device;

and the other end of the follow current device is connected with the ground.

5. The motor back-emf sampling module of claim 4, wherein: the switching device is a MOSFET, the load is a resistor, and the freewheeling device is a diode.

6. A counter potential sampling method of a motor is characterized by comprising the following steps:

s1, calculating a required control duty ratio according to the target rotating speed and the actual rotating speed calculated by the counter electromotive force;

s2, outputting PWM according to the control duty ratio to form preset waveform motor driving voltage;

s3, generating a back-emf sampling interrupt signal every interval (Twork + tbream);

s4, stopping outputting the preset waveform motor driving voltage after receiving the counter potential sampling interrupt signal, and continuing for Tbreak duration;

s5, sampling the terminal voltage of the motor after timing Twait duration;

s6, recovering to output the preset waveform motor driving voltage after Tbreak time is over;

wherein T is Twork + tbream, tbream is twoit + tsamping, T is a sampling period, Twork is a preset waveform motor driving voltage operating duration, tbream is an interruption duration, i.e., a duration of stopping outputting the preset waveform motor driving voltage, Twait is a back-potential sampling waiting duration, and tsamping is a back-potential sampling duration.

7. The motor back-emf sampling method of claim 6, wherein: the motor back electromotive force sampling method is used for a direct current brush motor.

8. The motor back-emf sampling method of claim 6, wherein: the motor back electromotive force sampling method is used for a direct current brush motor of a vehicle body stabilizing system.

9. The motor back-emf sampling method of claim 6, wherein: the preset waveform motor driving voltage is formed by switching on and off of a switching device of a PWM (pulse-width modulation) wave driving motor driving circuit.

Technical Field

The invention relates to the field of automobiles, in particular to a motor back electromotive force sampling module for a direct current brush motor of a vehicle body stabilizing system. The invention further relates to a motor back electromotive force sampling method for the direct current brush motor of the vehicle body stabilizing system.

Background

The vehicle body stabilization system (ESC) is composed of a controller, a valve block and a motor, wherein the valve block is provided with two oil inlets which are respectively communicated with two cavities of a brake master cylinder, and is also provided with four oil outlets which are respectively communicated with brake wheel cylinders of four wheels, and the ESC is shown in fig. 1. The main working principle of the vehicle body stabilizing system is that the stability of a vehicle is judged according to driver input (a brake pedal and a steering wheel corner) and sensor signals (master cylinder pressure, wheel speed, acceleration and yaw angular velocity), and when the vehicle is close to a destabilization state, an ESC controls the brake fluid pressure of four wheels independently by controlling an electromagnetic valve and a direct current brush motor in a valve block, so that the vehicle can keep stable running. Therefore, the control of the dc brushed motor is a crucial link for the vehicle body stabilization system.

Generally, a vehicle body stabilization system requires that a dc brushed motor be controlled to be able to control the rotation speed, and in order to control the rotation speed of the motor, it is necessary to sample the counter electromotive force of the motor. The conventional vehicle body stabilization system motor control is based on a low-frequency PWM control method in which back emf sampling is performed in the Toff interval of the PWM output. As shown in fig. 2, for a dc brushed motor, when the PWM is controlled to switch from a high level to a low level, the terminal voltage thereof is rapidly decreased, and then after a period of time Twait, the voltage is increased to a stable level Us, where the terminal voltage Us is the back electromotive force to be sampled, and Um is the motor operating voltage. The sampling time can be controlled by calibrating the Twait time of the motor, so that the sampling time is after the Twait time after the PWM falling edge, and the counter potential is correctly sampled. The method has two disadvantages, one is that the PWM frequency of the motor control cannot be higher than 1/Twait, otherwise, the voltage of the motor terminal cannot recover to a stable back electromotive force within the time of Toff; secondly, the PWM duty ratio of the motor control cannot be higher than Ton/(Ton + Twait), otherwise, the terminal voltage cannot recover to the stable back electromotive force, which affects the performance of the motor control. With the improvement of NVH (Noise, Vibration and Harshness) requirements of a vehicle body stabilizing system, the frequency of PWM (pulse width modulation) controlled by a motor is gradually improved, and the traditional back electromotive force sampling method cannot meet the requirement of high-frequency control.

Disclosure of Invention

In this summary, a series of simplified form concepts are introduced that are simplifications of the prior art in this field, which will be described in further detail in the detailed description. This summary of the invention is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

The invention aims to provide a motor back electromotive force sampling module which enables the sampling of the back electromotive force of a motor not to be limited by the back electromotive force sampling frequency and the duty ratio.

The invention provides a motor back electromotive force sampling method which enables the sampling of the back electromotive force of a motor not to be limited by the back electromotive force sampling frequency and the duty ratio.

In order to solve the technical problem, the invention provides a counter potential sampling module of a motor, which comprises:

the motor driving unit is suitable for outputting PWM to the driving circuit according to the control duty ratio, the driving circuit outputs preset waveform motor driving voltage, the driving circuit stops outputting PWM after receiving a counter electromotive force sampling interrupt signal, the preset waveform motor driving voltage is reduced to zero and lasts for the Tbreak time length, and the PWM is output to recover the preset waveform motor driving voltage after the Tbreak time length is finished;

a motor control unit adapted to calculate a required control duty ratio from a target rotation speed and an actual rotation speed calculated from a back electromotive force, to supply the duty ratio to the motor driving unit, and adapted to generate a back electromotive force sampling interrupt signal to the motor driving unit and the interrupt sampling unit every interval (Twork + tbree); the system comprises an interrupt sampling unit, a sampling unit and a sampling unit, wherein the interrupt sampling unit is suitable for sampling the terminal voltage of a motor after timing Twait duration;

the control duty ratio is calculated and obtained by adopting the following method:

the calculation method for controlling the duty cycle can be designed using common engineering control methods, for example using the PID method, the control voltage is calculated as follows:

the control duty ratio is:

wherein, U_ctrlIs the control voltage, k_p、k_iAnd k_dIs the PID coefficient, k motor back emf coefficient, U_batSupply voltage, omega_tgtIs the target rotational speed of the motor, U_sIs the back-emf.

Wherein T is Twork + tbream, tbream is twoit + tsamping, T is a sampling period, Twork is a preset waveform motor driving voltage operating duration, tbream is an interruption duration, i.e., a duration of stopping outputting the preset waveform motor driving voltage, Twait is a back-potential sampling waiting duration, and tsamping is a back-potential sampling duration.

Optionally, the motor back electromotive force sampling module is applied to a direct current brush motor.

Optionally, the motor back electromotive force sampling module is used for sampling the back electromotive force of the direct current brush motor of the vehicle body stabilizing system.

Optionally, the motor back electromotive force sampling module is further improved, and the motor driving circuit includes:

the anode of the power supply is connected with the input end of the switching device through a load, and the cathode of the power supply is connected with the ground;

the output end of the switching device is respectively connected with the motor and the follow current device;

and the other end of the follow current device is connected with the ground.

Alternatively, the switching device is a MOSFET, the load is a resistor, and the freewheeling device is a diode.

The invention provides a motor counter potential sampling method, which comprises the following steps:

s1, calculating a required control duty ratio according to the target rotating speed and the actual rotating speed calculated by the counter electromotive force;

s2, outputting PWM according to the control duty ratio to form preset waveform motor driving voltage;

s3, generating a back-emf sampling interrupt signal every interval (Twork + tbream);

s4, stopping outputting the preset waveform motor driving voltage after receiving the counter potential sampling interrupt signal, and continuing for Tbreak duration;

s5, sampling the terminal voltage of the motor after timing Twait duration;

s6, recovering to output the preset waveform motor driving voltage after Tbreak time is over;

wherein T is Twork + tbream, tbream is twoit + tsamping, T is a sampling period, Twork is a preset waveform motor driving voltage operating duration, tbream is an interruption duration, i.e., a duration of stopping outputting the preset waveform motor driving voltage, Twait is a back-potential sampling waiting duration, and tsamping is a back-potential sampling duration.

Optionally, the motor back electromotive force sampling method is used for a direct current brush motor.

Optionally, the motor back electromotive force sampling method is used for a direct current brush motor of a vehicle body stabilizing system.

Optionally, the preset waveform motor driving voltage is formed by switching on and off a switching device of a PWM wave driving motor driving circuit.

The working principle of the invention is as follows:

the drive of the dc brush motor drives the MOSFET switches on and off by PWM waves, generating a motor drive voltage waveform as shown in fig. 3. And calculating a required control duty ratio according to the target rotating speed and the actual rotating speed estimated by the counter electromotive force, and sending the duty ratio to a motor high-frequency driving program, wherein the motor driving program sends out actual control PWM to a hardware driving circuit according to the input duty ratio. Meanwhile, as shown in fig. 3, the motor control program generates a back electromotive force sampling interrupt signal every (Twork + tbree) time, and sends the back electromotive force sampling interrupt signal to the motor high-frequency driving program and the motor interrupt sampling program, and when receiving the back electromotive force sampling interrupt signal, the motor high-frequency control program stops outputting the PWM control waveform to the hardware circuit, reduces the motor driving voltage to 0V, and continues for the tbree time; meanwhile, after the Twait time is timed, the motor interruption sampling program samples the terminal voltage of the motor, and the result of the sampling is the back electromotive force of the motor. After the Tbreak time is over, the motor high-frequency driving program resumes driving the motor, and the motor driving is still performed according to the duty ratio command of the motor control program.

The method can meet the requirement of the motor control of the vehicle body stabilization system on back emf sampling, can adapt to the traditional click low-frequency control method, and can solve the problem that the back emf is difficult to sample when the motor is controlled at high frequency.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention, are incorporated in and constitute a part of this specification. The drawings are not necessarily to scale, however, and may not be intended to accurately reflect the precise structural or performance characteristics of any given embodiment, and should not be construed as limiting or restricting the scope of values or properties encompassed by exemplary embodiments in accordance with the invention. The invention will be described in further detail with reference to the following detailed description and accompanying drawings:

FIG. 1 is a schematic view of a vehicle body stabilization system configuration.

Fig. 2 is a diagram illustrating a conventional driving voltage waveform.

Fig. 3 is a schematic diagram of the driving voltage waveform of the present invention.

Fig. 4 is a schematic diagram of the back emf sampling principle of the present invention.

Fig. 5 is a schematic diagram of the motor driving circuit of the present invention.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and technical effects of the present invention will be fully apparent to those skilled in the art from the disclosure in the specification. The invention is capable of other embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the general spirit of the invention. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict. The following exemplary embodiments of the present invention may be embodied in many different forms and should not be construed as limited to the specific embodiments set forth herein. It is to be understood that these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the technical solutions of these exemplary embodiments to those skilled in the art. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

Referring to fig. 3 in conjunction with fig. 4, a first embodiment of a back electromotive force sampling module of a motor provided by the present invention includes:

the motor driving unit is suitable for outputting PWM to the driving circuit according to the control duty ratio, the driving circuit outputs preset waveform motor driving voltage, the driving circuit stops outputting PWM after receiving a counter electromotive force sampling interrupt signal, the preset waveform motor driving voltage is reduced to zero and lasts for the Tbreak time length, and the PWM is output to recover the preset waveform motor driving voltage after the Tbreak time length is finished;

a motor control unit adapted to calculate a required control duty ratio from a target rotation speed and an actual rotation speed calculated from a back electromotive force, to supply the duty ratio to the motor driving unit, and adapted to generate a back electromotive force sampling interrupt signal to the motor driving unit and the interrupt sampling unit every interval (Twork + tbree); the system comprises an interrupt sampling unit, a sampling unit and a sampling unit, wherein the interrupt sampling unit is suitable for sampling the terminal voltage of a motor after timing Twait duration;

wherein T is Twork + tbream, tbream is twoit + tsamping, T is a sampling period, Twork is a preset waveform motor driving voltage operating duration, tbream is an interruption duration, i.e., a duration of stopping outputting the preset waveform motor driving voltage, Twait is a back-potential sampling waiting duration, and tsamping is a back-potential sampling duration.

Optionally, the motor back electromotive force sampling module is used for sampling the back electromotive force of the direct current brush motor of the vehicle body stabilizing system.

As shown in fig. 5, a possible embodiment of the motor driving circuit is provided, which includes:

the anode of the power supply is connected with the input end of the switching device through a load, and the cathode of the power supply is connected with the ground;

the output end of the switching device is respectively connected with the motor and the follow current device;

and the other end of the follow current device is connected with the ground.

Alternatively, the switching device is a MOSFET, the load is a resistor, and the freewheeling device is a diode.

The invention provides a first embodiment of a motor counter potential sampling method, which comprises the following steps:

s1, calculating a required control duty ratio according to the target rotating speed and the actual rotating speed calculated by the counter electromotive force;

s2, outputting PWM according to the control duty ratio to form preset waveform motor driving voltage;

s3, generating a back-emf sampling interrupt signal every interval (Twork + tbream);

s4, stopping outputting the preset waveform motor driving voltage after receiving the counter potential sampling interrupt signal, and continuing for Tbreak duration;

s5, sampling the terminal voltage of the motor after timing Twait duration;

s6, recovering to output the preset waveform motor driving voltage after Tbreak time is over;

wherein T is Twork + tbream, tbream is twoit + tsamping, T is a sampling period, Twork is a preset waveform motor driving voltage operating duration, tbream is an interruption duration, i.e., a duration of stopping outputting the preset waveform motor driving voltage, Twait is a back-potential sampling waiting duration, and tsamping is a back-potential sampling duration.

Optionally, the motor back electromotive force sampling method is used for a direct current brush motor of a vehicle body stabilization system, and the preset waveform motor driving voltage is formed by switching on and off of a switching device of a PWM (pulse-width modulation) wave driving motor driving circuit.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The present invention has been described in detail with reference to the specific embodiments and examples, but these are not intended to limit the present invention. Many variations and modifications may be made by one of ordinary skill in the art without departing from the principles of the present invention, which should also be considered as within the scope of the present invention.