CN115833688A

CN115833688A - Dead zone compensation method, dead zone compensation device, computer equipment and computer readable storage medium

Info

Publication number: CN115833688A
Application number: CN202111549169.9A
Authority: CN
Inventors: 郑雄; 潘先喜; 但志敏
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2021-12-17
Filing date: 2021-12-17
Publication date: 2023-03-21
Anticipated expiration: 2041-12-17
Also published as: CN115833688B; WO2023109421A1

Abstract

The present application relates to a dead zone compensation method, apparatus, computer device, computer readable storage medium and computer program product, the method comprising: acquiring a dead zone compensation time set value and an action time sequence of each phase of switch unit in the inverter; determining the phase current polarity change condition of each phase according to the action time sequence and the corresponding relation between the preset action time sequence and the phase current polarity change condition; and obtaining the target conduction time of the corresponding phase switch unit according to the polarity change condition of each phase current and the dead zone compensation time set value. By adopting the method, the target conduction time capable of weakening the dead zone effect can be obtained without detecting the phase current polarity of the inverter, so that the dead zone compensation precision of the inverter can be improved, and the compensation effect can be improved.

Description

Dead zone compensation method, dead zone compensation device, computer equipment and computer readable storage medium

Technical Field

The present application relates to the field of motor control technologies, and in particular, to a dead-zone compensation method, apparatus, computer device, computer readable storage medium, and computer program product.

Background

An inverter is a converter that converts dc power into ac power of a constant frequency, a constant voltage, or a frequency and voltage modulation, and is generally used as a driving unit in a motor system. In order to prevent the upper half bridge and the lower half bridge of the same bridge arm in the inverter from being simultaneously conducted to cause the burning of power elements, a certain dead time needs to be added in the control process of the upper switch unit and the lower switch unit of the bridge arm. However, the introduction of the dead time causes a reduction in the fundamental component of the inverter output voltage, distortion in the waveform of the output current, and output torque ripple. Therefore, some compensation measures are required to reduce the influence of the dead zone effect.

According to the traditional dead-zone compensation method, the polarity of each phase of bridge arm current of the inverter is detected in real time, and the on-off time of the switch unit is correspondingly adjusted according to the polarity. However, due to the influence of PWM (Pulse width modulation) noise, zero current clamping effect, software delay, and other factors, the detection accuracy of the current polarity is limited, and the conventional dead-zone compensation method is often used to generate the error compensation. Therefore, the conventional dead zone compensation method has a disadvantage of poor compensation effect.

Disclosure of Invention

In view of the above, it is desirable to provide a dead-time compensation method, apparatus, computer device, computer readable storage medium and computer program product for improving the dead-time compensation effect of the inverter.

In a first aspect, the present application provides a dead zone compensation method. The method comprises the following steps:

acquiring a dead zone compensation time set value and an action time sequence of each phase of switch unit in the inverter;

determining the phase current polarity change condition of each phase according to the action time sequence and the corresponding relation between the preset action time sequence and the phase current polarity change condition;

and obtaining the target conduction time of the corresponding phase switch unit according to the change condition of the polarity of each phase current and the dead zone compensation time set value.

According to the dead zone compensation method, the corresponding relation between the action time sequence and the phase current polarity change condition is established, the phase current polarity change condition is determined according to the action time sequence of each phase of switching unit, the phase current polarity change condition and the dead zone compensation time set value are combined, the target conduction time of the corresponding phase of switching unit is obtained, the target conduction time capable of weakening the dead zone effect can be obtained without detecting the phase current polarity of the inverter, the dead zone compensation accuracy of the inverter is improved, and the compensation effect is improved.

In one embodiment, the phase current polarity change condition includes any one of the following three conditions:

the polarity of the phase current is not changed, and the polarity of the phase current is positive;

the polarity of the phase current is not changed, and the polarity of the phase current is negative;

the phase current polarity changes.

In the embodiment, various forms of phase current polarity change conditions are provided, so that a user can flexibly establish the corresponding relation between the action time sequence and the phase current polarity change conditions according to the structural characteristics of the inverter, and the application scene of the dead zone compensation method can be expanded.

In one embodiment, the phase current polarity change condition includes: the phase current polarity is unchanged, and the phase current polarity is positive, and the phase current polarity is unchanged, and the phase current polarity is negative; the obtaining of the target on-time of the corresponding phase switch unit according to the change condition of the polarity of each phase current and the dead-time compensation time setting value includes:

if the phase current polarity is not changed and the phase current polarity is positive, adding the dead zone compensation time set value on the basis of the original conduction time to obtain the target conduction time of the corresponding phase switch unit;

and if the phase current polarity is not changed and the phase current polarity is negative, subtracting the dead-time compensation time set value on the basis of the original conduction time to obtain the target conduction time of the corresponding phase switch unit.

In the above embodiment, when the phase current polarity is not changed, the target on-time of the corresponding phase switching unit is determined according to the phase current polarity and the dead-time compensation time setting value, which is equivalent to performing dead-time compensation differentially according to the actual conditions of each phase, and is beneficial to improving the compensation effect of the dead-time compensation method.

In one embodiment, the inverter is a three-phase inverter, and the phase current polarity change condition includes a change in phase current polarity; the obtaining of the target on-time of the corresponding phase switch unit according to the change condition of the polarity of each phase current and the dead zone compensation time setting value includes:

determining adjacent non-zero basic space voltage vectors acting on corresponding phases based on a space vector pulse width modulation method;

and acquiring the action time of each nonzero basic space voltage vector, and acquiring the target conduction time of the corresponding phase switch unit according to the action time of each nonzero basic space voltage vector and the dead zone compensation time set value.

In the above embodiment, based on the space vector pulse width modulation method, the target on-time of the corresponding phase switching unit is determined according to the action time of the adjacent non-zero basic space voltage vector acting on the corresponding phase, on one hand, the method is simple, and is beneficial to improving the working efficiency of dead zone compensation; on the other hand, the corresponding phase with the changed phase current polarity is gradually compensated, so that the dead zone compensation effect is improved, and the running stability of the motor system is maintained.

In one embodiment, before obtaining the dead time compensation time setting value, the method further includes:

and determining a dead-time compensation time set value based on the working parameters of the motor system.

In the above embodiment, before the dead-time compensation time set value is obtained, the dead-time compensation time set value is determined based on the working parameters of the motor system, so that the matching degree between the dead-time compensation time set value and the actual dead-time can be ensured, and the effect of dead-time compensation is further improved.

In one embodiment, the inverter is applied to a permanent magnet synchronous motor system; the dead-time compensation time setting value is determined based on the working parameters of the motor, and the dead-time compensation time setting value comprises the following steps:

acquiring working parameters of a permanent magnet synchronous motor system, and calculating to obtain the actual voltage of the permanent magnet synchronous motor according to the working parameters;

acquiring the command voltage of the permanent magnet synchronous motor system, and calculating to obtain error voltage according to the actual voltage and the command voltage;

and determining a dead zone compensation time set value according to the error voltage.

In the above embodiment, based on the disturbance observer, in combination with the working condition of the permanent magnet synchronous motor, the dead-zone compensation time set value is determined according to the error voltage, which is equivalent to comprehensively considering the influence of the delay time of the on/off of the switch unit, the tube voltage drop, the temperature, and the like, and is beneficial to further improving the matching degree of the dead-zone compensation time set value and the actual dead-zone time and improving the compensation precision of the dead-zone compensation.

In one embodiment, the actual voltage of the permanent magnet synchronous motor system refers to a q-axis voltage of a permanent magnet synchronous motor in the permanent magnet synchronous motor system.

In the above embodiment, the dead-time compensation time setting value is determined using the q-axis voltage, and the calculation accuracy of the dead-time compensation time setting value can be ensured thanks to the stability of the q-axis voltage.

In a second aspect, the present application provides a dead band compensation apparatus. The device comprises:

the acquisition module is used for acquiring a dead zone compensation time set value and an action time sequence of each phase of switch unit in the inverter;

the phase current polarity determining module is used for determining the phase current polarity change condition of each phase according to the action time sequence and the corresponding relation between the preset action time sequence and the phase current polarity change condition;

and the target conduction time determining module is used for obtaining the target conduction time of the corresponding phase switch unit according to the phase current polarity change condition and the dead zone compensation time set value.

In one embodiment, the phase current polarity change condition includes any one of the following three conditions: the polarity of the phase current is not changed, and the polarity of the phase current is positive; the polarity of the phase current is not changed, and the polarity of the phase current is negative; the phase current polarity changes.

In one embodiment, the phase current polarity change condition includes: the phase current polarity is unchanged, and the phase current polarity is positive, and the phase current polarity is unchanged, and the phase current polarity is negative; the target on-time determination module is specifically configured to:

In one embodiment, the inverter is a three-phase inverter, and the phase current polarity change condition includes a change in phase current polarity; the target on-time determination module is further configured to: determining adjacent non-zero basic space voltage vectors acting on corresponding phases based on a space vector pulse width modulation method; and acquiring the action time of each nonzero basic space voltage vector, and acquiring the target conduction time of the corresponding switch unit according to the action time of each nonzero basic space voltage vector and the dead zone compensation time set value.

In one embodiment, the dead zone compensation apparatus further includes:

and the dead zone compensation time set value determining module is used for determining a dead zone compensation time set value based on the working parameters of the motor system.

In one embodiment, the inverter is applied to a permanent magnet synchronous motor system; the dead time compensation time set value determination module is specifically configured to: acquiring working parameters of a permanent magnet synchronous motor system, and calculating to obtain the actual voltage of the permanent magnet synchronous motor according to the working parameters; acquiring the command voltage of the permanent magnet synchronous motor system, and calculating to obtain error voltage according to the actual voltage and the command voltage; and determining a dead zone compensation time set value according to the error voltage.

In a third aspect, the application also provides a computer device. The computer device comprises a memory storing a computer program and a processor implementing the following steps when executing the computer program:

In a fourth aspect, the present application further provides a computer-readable storage medium. The computer-readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of:

In a fifth aspect, the present application further provides a computer program product. The computer program product comprising a computer program which when executed by a processor performs the steps of:

Drawings

FIG. 1 is a flow diagram of a dead band compensation method in one embodiment;

FIG. 2 is a flow chart of a dead band compensation method in another embodiment;

FIG. 3 is a flowchart illustrating obtaining a target on-time of a corresponding phase switching unit according to a change of polarity of each phase current and a dead-time compensation time setting value in an embodiment;

FIG. 4 is a schematic voltage vector space diagram based on the SVPWM modulation method in one embodiment;

FIG. 5 is a flow chart of a dead-zone compensation method in yet another embodiment;

FIG. 6 is a flow diagram of determining a dead time compensation time set point based on operating parameters of the motor system in one embodiment;

FIG. 7 is a schematic diagram of the control scheme of a permanent magnet synchronous motor system in one embodiment;

FIG. 8 is a waveform illustrating a calculated value of actual dead time in one embodiment;

FIG. 9 is a phase current waveform diagram before dead band compensation in one embodiment;

FIG. 10 is a phase current waveform after dead band compensation in one embodiment;

FIG. 11 is a block diagram showing the components of a dead zone compensation device according to an embodiment;

FIG. 12 is a diagram illustrating an internal structure of a computer device according to an embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of and not restrictive on the broad application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application; the terms "including" and "having," and any variations thereof, in the description and claims of this application and the description of the above figures are intended to cover non-exclusive inclusions.

The dead zone compensation method, apparatus, computer device, computer readable storage medium, and computer program product provided herein may be applied to systems using an inverter as a driving part, including but not limited to various types of motor systems. Such as a permanent magnet synchronous motor system or a reluctance synchronous motor system, etc.

In one embodiment, as shown in fig. 1, a dead zone compensation method is provided, including step S102 to step S106.

Step S102: and acquiring a dead zone compensation time set value and the action time sequence of each phase of switching unit in the inverter.

The dead-time compensation time setting value refers to preset dead-time compensation time. The action time sequence of each phase of switch unit in the inverter refers to the sequence of the output drive signals of the drive units corresponding to each phase of switch unit in the inverter. The driving signal is used for driving the corresponding switch unit to be switched on or switched off.

Specifically, dead time that upper and lower switch units of the same bridge arm are turned off simultaneously in one control cycle can be determined based on historical data or control signal delay characteristics, and a dead time compensation time set value is determined according to the dead time. For example, the dead time may be equal to the dead time compensation time setting value, or the dead time compensation time setting value may be obtained by setting a deviation value or a deviation coefficient in consideration of a safety margin on the basis of the dead time.

Furthermore, the action time sequence of the corresponding phase switch unit can be determined according to the output time of the driving signal of each phase driving unit in the inverter. In addition, the control device may obtain the dead time compensation setting value and the specific manner of the action timing sequence of each phase of the switching unit in the inverter, and the dead time compensation setting value may be obtained actively or may be received passively.

The inverter in the present application is a multi-phase inverter including a plurality of arms, for example, a two-phase inverter or a three-phase inverter. For convenience of understanding, the following description will be given taking a case where the inverter is a three-phase inverter as an example.

Step S104: and determining the phase current polarity change condition of each phase according to the action time sequence and the corresponding relation between the preset action time sequence and the phase current polarity change condition.

The phase current polarity change condition comprises a phase current polarity and a change condition of the phase current polarity. Phase current polarities including positive and negative; the change of the polarity of the phase current comprises that the polarity of the phase current is not changed and is changed. Further, the phase current polarity may refer to an upper arm phase current polarity or a lower arm phase current polarity. As described above, the upper and lower switch units of the same bridge arm are not turned on at the same time, and based on this, the phase current polarity of the phase can be represented by the upper bridge arm phase current polarity or the lower bridge arm phase current polarity.

Specifically, the phase current polarity change condition of each phase can be determined according to the action time sequence of each phase of switch unit and the corresponding relationship between the preset action time sequence and the phase current polarity change condition.

In one embodiment, the phase current polarity change condition comprises any one of the following three conditions: the polarity of the phase current is not changed, and the polarity of the phase current is positive; the polarity of the phase current is not changed, and the polarity of the phase current is negative; the phase current polarity changes.

It can be understood that in one control period, if the driving unit always drives the upper bridge arm switch unit to be conducted, the phase current polarity of the corresponding phase is positive; if the driving unit always drives the upper bridge arm switch unit to be turned off, the phase current polarity of the corresponding phase is negative; if the driving unit drives the upper bridge arm switch unit to change the conducting state, the phase current polarity of the corresponding phase will also change.

Specifically, the correspondence between the action timing and the phase current polarity change condition may be established according to the structural characteristics of the inverter. For example, in the case of a three-phase inverter, a corresponding phase having a positive current polarity may be set as the first operating phase, a corresponding phase having a changed current polarity may be set as the second operating phase, and a corresponding phase having a negative current polarity may be set as the third operating phase.

Step S106: and obtaining the target conduction time of the corresponding phase switch unit according to the polarity change condition of each phase current and the dead zone compensation time set value.

The corresponding phase switch unit may refer to an upper bridge arm switch unit or a lower bridge arm switch unit of the corresponding phase. The conducting state of the upper bridge arm switch unit is complementary with the conducting state of the lower bridge arm switch unit. Therefore, dead zone compensation can be realized by controlling the conduction time of the upper arm switch unit or the lower arm switch unit.

Specifically, according to the polarity change condition of each phase current, the influence of the dead time insertion on the conduction time of the phase switch unit can be obtained, and if the dead time insertion causes the conduction time of the phase switch unit to be reduced, the dead time compensation time setting value is added on the basis of the original conduction time to obtain the target conduction time; if the dead time is set to prolong the conduction time of the phase switch unit, the dead time compensation time set value is subtracted on the basis of the original conduction time to obtain the target conduction time. And then on-off control is carried out on the corresponding switch unit based on the target conduction time, so that the influence of the dead zone effect can be reduced. It is understood that the original on-time in the above is the on-time without considering the dead zone compensation.

In one embodiment, step S106 includes: determining the duration of positive and negative phase currents according to the polarity change condition of each phase current; and obtaining the target conduction time of the corresponding phase switch unit according to the duration time of the positive and negative phase currents and the dead zone compensation time set value.

The duration of the positive and negative phase currents refers to the duration that a phase current in the inverter is positive and the duration that the phase current is negative under the action of the driving signal in one period.

Specifically, the duration of the positive and negative phase currents can be determined according to the polarity change condition of each phase current: if the phase current polarity is not changed and the phase current polarity is positive, the duration of the positive phase current is 1 (the corresponding duration is less than or equal to the duration of one period), and the duration of the negative phase current is 0; if the polarity of the phase current is not changed and the polarity of the phase current is negative, the duration time of the positive phase current is 0 and the duration time of the negative phase current is 1; if the polarity of the phase current changes, the duration of the positive and negative phase currents needs to be determined according to the polarity change trend and the change time.

Furthermore, a dynamic compensation parameter can be calculated according to the duration time of the positive and negative phase currents, and then the product of the dead-time compensation time setting value and the dynamic compensation parameter is added on the basis of the original conduction time according to the dynamic compensation parameter and the dead-time compensation time setting value, so that the target conduction time of the corresponding switch unit can be obtained. The calculation formula of the dynamic compensation parameter K is as follows: k = (t 1-t 2)/(t 1+ t 2). Where t1 is the positive phase current duration and t2 is the negative phase current duration.

The method of acquiring the action time of the positive and negative phase currents is not exclusive, and may be determined, for example, by acquiring a driving signal and determining the action time according to the type and change time of the driving signal, or may be determined according to the action time of an adjacent non-zero voltage vector based on a space vector pulse width modulation method.

In the above embodiment, the target on-time of the corresponding phase switching unit is determined according to the duration of the positive and negative phase currents and the dead-time compensation time setting value, which is equivalent to performing dynamic dead-time compensation according to the actual condition of each phase, and is beneficial to improving the compensation effect of the dead-time compensation method.

In one embodiment, as shown in FIG. 2, step S106 includes step S202 and step S204.

Step S202: and if the polarity of the phase current is not changed and the polarity of the phase current is positive, adding a dead-time compensation time set value on the basis of the original conduction time to obtain the target conduction time of the corresponding phase switch unit.

Step S204: if the polarity of the phase current is not changed and the polarity of the phase current is negative, the dead-time compensation time setting value is subtracted on the basis of the original conduction time to obtain the target conduction time of the corresponding phase switch unit.

Specifically, a case where the corresponding-phase switch unit is the upper arm switch unit of the corresponding phase is taken as an example. After the dead time is set, for any phase in the inverter, when the polarity of the phase current is positive, the on-time of the corresponding phase switch unit is shortened, that is, the upper arm switch unit and the lower arm switch unit of the phase are simultaneously turned off in the dead time. During the period that the switch units are simultaneously turned off, the phase current can follow current through the diodes in the lower bridge arm switch units, and the conduction time of the upper bridge arm switch units is actually shortened, so that the influence of the dead zone effect can be reduced only by adding dead zone compensation time on the basis of the original conduction time of the upper bridge arm switch units. When the polarity of the phase current is negative, the phase current can follow current through a diode in the upper bridge arm switch unit within the dead time when the upper bridge arm switch unit and the lower bridge arm switch unit are simultaneously turned off, and the conduction time of the upper bridge arm switch unit is actually prolonged, so that the influence of the dead time effect can be reduced only by subtracting a dead time compensation time set value from the original conduction time of the upper bridge arm switch unit.

Based on this, differential dead-zone compensation can be performed according to the phase current polarity change condition of each phase determined in step S104: if the polarity of the phase current is not changed and the polarity of the phase current is positive, adding a dead-time compensation time set value on the basis of the original conduction time to obtain the target conduction time of the corresponding phase switch unit; if the polarity of the phase current is not changed and the polarity of the phase current is negative, the dead-time compensation time setting value is subtracted on the basis of the original conduction time to obtain the target conduction time of the corresponding phase switch unit.

In the above embodiment, when the phase current polarity is not changed, the target on-time of the corresponding phase switching unit is determined according to the phase current polarity and the dead-time compensation time setting value, which is equivalent to performing dead-time compensation differently according to the actual condition of each phase, and is beneficial to improving the compensation effect of the dead-time compensation method.

In one embodiment, the inverter is a three-phase inverter and the phase current polarity change comprises a change in phase current polarity. In the case of this embodiment, as shown in fig. 3, step S106 includes step S302 and step S304.

Step S302: and determining adjacent non-zero basic space voltage vectors acting on the corresponding phases based on a space vector pulse width modulation method.

The Space Vector Pulse Width Modulation (SVPWM) method directly generates a three-phase PWM wave by using a Space voltage Vector, and is simple in calculation and widely applied to a motor system.

Specifically, three bridge arms of the three-phase inverter have six switching units, and the six switching units are combined (the signals of the upper half bridge and the lower half bridge of the same bridge arm are opposite) to have 8 safe switching states. Wherein, 1 represents that the upper bridge arm switch unit is switched on and the corresponding lower bridge arm switch unit is switched off; and 0 represents that the upper bridge arm switch unit is turned off and the corresponding lower bridge arm switch unit is turned on. (000) And (111) the two switching states do not generate effective current in motor driving and are zero vectors, and the other six switching states respectively correspond to six non-zero basic space voltage vectors. As shown in fig. 4, six non-zero fundamental spatial voltage vectors divide a 360 degree voltage space into six sectors, each sector having a central angle of 60 degrees. With these six basic effective vectors and two zero quantities, any voltage vector within the voltage space can be synthesized.

In the working process, the position information of the motor rotor can be obtained, the position of the current voltage vector in the voltage space is determined according to the position information of the motor rotor, and then the adjacent non-zero basic space voltage vector acting on the corresponding phase is determined. For example, when the position information of the rotor of the motor corresponds to sector i, the adjacent non-zero fundamental space voltage vectors applied to the corresponding phases are V4 and V6. The position information of the motor rotor may be angle information of the motor rotor.

Step S304: and acquiring the action time of each nonzero basic space voltage vector, and acquiring the target conduction time of the corresponding switch unit according to the action time of each nonzero basic space voltage vector and the dead zone compensation time set value.

Specifically, the real-time position of the current voltage vector Vs in the voltage space can be determined according to the position information of the motor rotor, and then the relative positions of the voltage vector Vs and two adjacent non-zero basic space voltage vectors are determined, so as to obtain the action time of each non-zero basic space voltage vector. And determining the duration of the positive and negative phase currents of the corresponding phase by combining the change condition of the switch state of the corresponding phase in the adjacent non-zero basic space voltage vector: and determining the acting time of the non-zero basic space voltage vector with the switching state of 1 in the corresponding phase as the duration of the positive phase current, and determining the acting time of the non-zero basic space voltage vector with the switching state of 0 in the corresponding phase as the duration of the negative phase current. And finally, obtaining the target conduction time of the corresponding phase of switch unit based on the influence of the positive and negative phase currents on the actual conduction time of the switch unit and the dead zone compensation time set value.

Take the case where the voltage vector Vs is in sector i as an example. When the phase current is rotated anticlockwise, the action time of the basic space voltage vector V4 (100) is gradually reduced, the action time of the basic space voltage vector V6 (110) is gradually increased, the switching state of the upper bridge arm of the phase B is from 0 to 1, the effective opening time is gradually increased, and the polarity of the phase current is gradually changed from negative to positive; when the rotor rotates clockwise, the action time of the basic space voltage vector V6 (110) is gradually reduced, the action time of the basic space voltage vector V4 (100) is gradually increased, the switch state of the bridge arm on the phase B is from 1 to 0, the effective opening time is gradually reduced, and the current is gradually changed from positive to negative. Based on the dynamic compensation coefficient, the product of the dead zone compensation time set value and the dynamic compensation coefficient is added on the basis of the original conduction time according to the dynamic compensation coefficient and the dead zone compensation time set value, and the target conduction time of the corresponding switch unit can be obtained.

Wherein the dynamic compensation coefficient is calculated according to the action time of the adjacent non-zero basic space voltage vector. For example, when the voltage vector Vs is in the i-th sector, the dynamic compensation coefficient P is calculated as: p = (T6-T4)/(T6 + T4). Where T4 is the action time of the voltage vector V4, and T6 is the action time of the voltage vector V6.

In the above embodiment, based on the space vector pulse width modulation method, the target on-time of the corresponding phase switching unit is determined according to the action time of the adjacent non-zero basic space voltage vector acting on the corresponding phase, on one hand, the method is simple, and is beneficial to improving the working efficiency of dead zone compensation; on the other hand, by introducing a dynamic compensation coefficient, the corresponding phase with changed phase current polarity is gradually compensated, so that the dead zone compensation effect is improved, and the running stability of the motor system is maintained.

In one embodiment, as shown in fig. 5, before obtaining the dead time setting value, the method further includes step S101: and determining a dead-time compensation time set value based on the working parameters of the motor system.

The motor system includes a motor itself, a control unit, an inverter as a motor drive unit, and the like. Correspondingly, the working parameters of the motor system comprise the working parameters of the motor, the control part and the inverter.

Specifically, the specific manner of determining the dead-time compensation time set value based on the operating parameters of the motor system is not unique. For example, the dead time setting value may be determined according to the rising time of the drive signal by acquiring the waveform of the drive signal, or may be determined according to the delay characteristic of the drive chip in the inverter.

Further, the timing of determining the dead-time compensation time set value is also not unique based on the operating parameters of the motor system. For example, the dead time setting value may be updated once per week, day, or hour, or may be updated in real time. Under the condition of updating the dead-time compensation time set value in real time, the dead-time compensation time set value of the current period can be determined based on the working parameters of the motor system in the last PWM control period.

In one embodiment, the inverter is applied to a permanent magnet synchronous motor system. In the case of this embodiment, as shown in fig. 6, step S101 includes step S602 to step S606.

Step S602: and acquiring working parameters of the permanent magnet synchronous motor system, and calculating to obtain the actual voltage of the permanent magnet synchronous motor according to the working parameters.

The actual voltage of the permanent magnet synchronous motor can be characterized by d-axis voltage or q-axis voltage.

Specifically, the voltage equation of the permanent magnet synchronous motor in the synchronous rotating coordinate system is as follows:

in the formula u _d And u _q D-axis voltage and q-axis voltage, respectively; i.e. i _d And i _q D-axis current and q-axis current, respectively; l is _d And L _q D-axis inductance and q-axis inductance respectively; r is a stator winding phase resistance; omega is the angular speed of the rotor; psi _f Is a rotor permanent magnet flux linkage. The d axis is also called a straight axis and is the central axis of a rotor magnetic pole of the permanent magnet synchronous motor, and the direction of the d axis points to the N pole from the S pole; the q-axis, also called the quadrature axis, is perpendicular to the d-axis.

In one embodiment, the actual voltage of the permanent magnet synchronous motor system refers to a q-axis voltage of a permanent magnet synchronous motor in the permanent magnet synchronous motor system. In the actual operation process, the d-axis voltage of the permanent magnet synchronous motor fluctuates more than the q-axis voltage, and in the surface-mounted motor control process, the actual d-axis voltage generally fluctuates near zero at low speed and light load, which causes a large calculation error, so that in order to ensure the calculation accuracy of the dead-zone compensation time set value, the q-axis voltage is used for determining the dead-zone compensation time set value.

Step S604: and acquiring the command voltage of the permanent magnet synchronous motor system, and calculating to obtain the error voltage according to the actual voltage and the command voltage.

The motor control part generally includes a control module and a modulation module. The SVPWM referred to above belongs to the modulation module and the current loop PI regulation belongs to the control module. The control module is used for obtaining the command voltage and determining the amplitude and the phase of the output voltage vector. The modulation module is used for converting the output voltage vector into a PWM signal through modulation and outputting the PWM signal to the motor. Based on this, the command voltage of the permanent magnet synchronous motor system refers to the command voltage of a PI controller in the permanent magnet synchronous motor system.

Specifically, in the current loop, the PI controller generates an error voltage u to eliminate the dead zone _qerr And u _derr And will u _derr Applied to d-axis command voltage

Above, u is to _qerr Applying a command voltage to the q-axis

Upper, i.e. d-axis voltage command

And the actual d-axis voltage u _d Has an error voltage u between _derr Q-axis voltage command

With actual q-axis voltage u _q Has an error voltage u between _qerr From this, the error voltage can be calculated:

in the formula u _derr And u _qerr Respectively, a d-axis error voltage and a q-axis error voltage.

Step S606: and determining a dead-time compensation time set value according to the error voltage.

Specifically, the error voltage is subjected to proportional-integral control to calculate the actual dead time of the previous control period, and then the updated dead time compensation time set value can be determined according to the actual dead time. For example, the dead zone compensation time setting value may be equal to the actual dead zone time, or the dead zone compensation time setting value may be obtained by setting a deviation value or a deviation coefficient in consideration of a safety margin on the basis of the actual dead zone time.

Further, taking q-axis error voltage as an example, the formula for calculating the actual dead time according to the error voltage is as follows:

Td ₀ ＝Kp*u _qerr +(Ki*u _qerr +Z(k-1)) (5)

Z(k-1)＝Ki*u _qerr (k-1)+Z(k-2) (6)

wherein, td ₀ Is the actual dead time; kp is a proportionality coefficient; ki is an integral coefficient; kp, ki>0; z (k-1) is the integral value at the k-1 st time, and the initial value Z (0) =0 of Z.

For the sake of understanding, the dead zone compensation method will be described in detail below with reference to fig. 4, 7 to 10.

In one embodiment, the inverter is a three-phase inverter applied to a permanent magnet synchronous motor system. As shown in fig. 7, the permanent magnet synchronous motor system includes a control part and a driving part connected to the permanent magnet synchronous motor, and a direct current power supply DC and a voltage stabilizing capacitor C1 connected to the driving part.

Wherein, the control part comprises a control module and a modulation module. The control module comprises a PI controller, a sampling unit and a coordinate transformation unit, wherein the sampling unit corresponds to parameters such as A-phase current Ia, B-phase current Ib, a rotor angle theta of a motor, rotor angular speed omega and the like, and the abc-alpha-beta coordinate transformation unit and the alpha-beta-dq coordinate transformation unit. Specifically, coordinate transformation from the three-phase coordinate abc to the two-phase stationary coordinate α β is performed on Ia and Ib, and the stationary currents i α and i β can be obtained. Coordinate transformation from two-phase stationary coordinate alpha beta to two-phase rotating coordinate dq is carried out on i alpha and i beta, and rotating coordinate current i can be obtained _d And i _q . Then i is put _d And i _q Respectively corresponding to given command current

Comparing, respectively providing the errors to the PI controllers of corresponding axes, and outputting the errors by the PI controllersCorresponding command voltage

And

will command the voltage

And

actual rotating current i _d And i _q And the angular speed omega of the motor rotor is sent into an error voltage calculation unit, and the error voltage u can be calculated according to the formulas (1) to (4) _derr And u _qerr Due to motor parameters R, L _d 、L _q And psi _f The motor parameter calculating unit can acquire and calculate the parameters of the motor in real time for calculating the error voltage.

After the real-time error voltage is obtained through calculation, the error voltage u can be obtained _derr And u _qerr Respectively injecting the instruction voltages corresponding to the next control cycle

And

and (5) performing dead zone compensation. The error voltage u can also be adjusted _derr And u _qerr Sending the data to a dead time calculation unit, and calculating the actual dead time Td according to the equations (5) and (6) ₀ And the actual dead time Td ₀ A dead-time compensation time set point for the next control cycle is determined. As shown in fig. 8, the calculated value of the actual dead time is in the us order and varies periodically as can be seen from fig. 8. The above-mentioned actual dead time Td ₀ The calculation process comprehensively considers the influence of factors such as delay time of on-off of the switch unit, tube voltage drop, temperature and the like, and is favorable for improving the dead zone compensation time settingThe value and the dead zone time matching degree can accurately compensate the dead zone, and therefore the dead zone compensation effect is improved.

Furthermore, the modulation module is based on the SVPWM principle and is used for conducting dead-zone compensation by controlling the conduction of each bridge arm switch unit of the three-phase inverter.

Specifically, three bridge arms of the three-phase inverter have six switching units, so that the six switching units are combined (the signals of the upper half bridge and the lower half bridge of the same bridge arm are opposite) to have 8 safe switching states. Wherein, 1 represents that the upper bridge arm switch unit is turned on and the corresponding lower bridge arm switch unit is turned off; and 0 represents that the upper bridge arm switch unit is turned off and the corresponding lower bridge arm switch unit is turned on. (000) And (111) the two switching states do not generate effective current in motor driving and are zero vectors, and the other six switching states respectively correspond to six non-zero basic space voltage vectors. As shown in fig. 4, six non-zero fundamental spatial voltage vectors divide a 360 degree voltage space into six sectors, each sector having a central angle of 60 degrees. With these six basic effective vectors and two zero quantities, any voltage vector within the voltage space can be synthesized. According to the angle of the motor rotor, the position of the current voltage vector in the voltage space can be determined, and then the adjacent non-zero basic space voltage vector acting on the corresponding phase is determined.

Taking the case where the voltage vector Vs is in sector i as an example, in the case of this embodiment, the adjacent non-zero fundamental space voltage vectors applied to the corresponding phases are V4 and V6.

Based on the volt-second equilibrium principle:

V4*T4+V6*T6＝Vs*Ts (7)

wherein T4 and T6 are the action times of two non-zero basic space voltage vectors V4 and V6, respectively, within one PWM period Ts. Under the ideal condition, the conduction time Ta, tb and Tc of the upper arm switch unit of each phase of the inverter in one PWM period are respectively:

when a dead time Td is added, for phase a, when the phase current polarity is positive, the on-time of the upper arm switch unit S1 is shortened by Td, that is: the upper bridge arm switch unit S1 and the lower bridge arm switch unit S4 are turned off simultaneously in the time Td, in the period of turning off simultaneously, the phase current continues flowing through the diode in the time S4, the turn-on time of the S1 is actually shortened by the time Td, and therefore, a dead zone compensation time set value Td is added on the basis of the original turn-on time Ta ₀ And performing dead zone compensation. When the a-phase current is negative, the current freewheels through the diode in the S1 driving unit during the Td time when S1 and S4 are simultaneously turned off, the actual on time of S1 is extended by Td, and thus the dead time compensation time setting value Td is subtracted from the original on time Ta ₀ And performing dead zone compensation. The compensation of the phase B and the phase C is similar to the phase A, and the description is omitted here. It can be understood that Td ₀ The smaller the difference from Td, the better the compensation effect. Actual dead time Td of the previous period ₀ As the dead zone compensation time set value of the current period, the matching degree of the dead zone compensation time set value and the actual dead zone time can be improved, and the compensation precision of the dead zone compensation is improved.

In order to avoid the difficulty in detecting the current polarity during low-frequency light load, the action time sequence of each phase of switch unit is designed, and the corresponding relation between the action time sequence and the phase current polarity change condition is established: the phase current polarity of the bridge arm where the switching unit of the first action is positioned is not changed, and the phase current polarity is positive; the phase current polarity of the bridge arm where the switch unit of the second action is positioned is changed; the phase current polarity of the bridge arm where the switching unit of the third action is located is not changed, and the phase current polarity is negative. In the control process, the action time sequence of each phase of switch unit is obtained, and the phase current polarity change condition of each phase can be determined according to the action time sequence and the corresponding relation between the preset action time sequence and the phase current polarity change condition.

For the second actuated switch element, the polarity of the phase current may be determined based on the time of application of the adjacent non-zero basis space voltage vector.

Taking sector i as an example, in this sector, the adjacent non-zero basic space voltage vectors are V4 (100) and V6 (110), and the corresponding operation sequence is: the phase A upper bridge arm switch unit is firstly switched on, the phase B upper bridge arm switch unit is secondly switched on, and the phase C upper bridge arm switch unit is finally switched on. And the action time of the adjacent non-space voltage vectors is T4 and T6 respectively, and then T4+ T6< = Ts. And when T4+ T6= Ts, the duty ratio of the C-phase upper arm is 0, and the C-phase upper arm is always turned off. When T4+ T6 is less than Ts, the duty ratio of the C-phase upper bridge arm is more than 0, and the action time of zero vectors (000) and (111) is Tc. That is, the original on-time of the corresponding phase switching unit can be determined according to the action time of the adjacent non-zero basic space voltage vector and the zero vector.

Furthermore, the polarity of the phase current B is changed in the sector, the changed point is near the middle point of the sector I, and the corresponding polarity of the phase current can be judged according to the action time of V4 and V6. According to the rotating direction of the voltage vector Vs, when the voltage vector Vs rotates anticlockwise, the acting time of the basic space voltage vector V4 (100) is gradually reduced, the acting time of the voltage vector V6 (110) is gradually increased, the switching state of the upper bridge arm of the phase B is from 0 to 1, the effective opening time is gradually increased, and the polarity of the phase current is gradually changed from negative to positive; when the rotor rotates clockwise, the action time of the basic space voltage vector V6 (110) is gradually reduced, the action time of the basic space voltage vector V4 (100) is gradually increased, the switch state of the bridge arm on the phase B is from 1 to 0, the effective opening time is gradually reduced, and the current is gradually changed from positive to negative. Based on this, a dynamic compensation coefficient P can be introduced, and after dead-zone compensation is considered, the target on-time of the three phases is:

Ta′＝Ta+Td (11)

Tb′＝Tb+P*Td (12)

Tc′＝Tc-Td (13)

wherein P = (T6-T4)/(T6 + T4). It is easy to determine that, -1< = P < =1, that is, for the corresponding phase with changed phase current polarity, in order to avoid torque fluctuation caused by directly changing the sign of Td during polarity change, progressive compensation is performed by introducing a dynamic compensation coefficient, so that the dead zone compensation effect can be improved, and at the same time, the operation stability of the motor system can be maintained.

As shown in fig. 9 and 10, the phase current waveforms before and after the dead zone compensation are performed. It can be seen that before dead zone compensation, phase current has distortion and current clamping, which may cause torque ripple and is not beneficial to stable operation of a motor system.

It should be understood that, although the steps in the flowcharts related to the embodiments as described above are sequentially displayed as indicated by arrows, the steps are not necessarily performed sequentially as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least a part of the steps in the flowcharts related to the embodiments described above may include multiple steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, and the execution order of the steps or stages is not necessarily sequential, but may be rotated or alternated with other steps or at least a part of the steps or stages in other steps.

Based on the same inventive concept, the embodiment of the present application further provides a dead-time compensation device for implementing the dead-time compensation method mentioned above. The implementation scheme for solving the problem provided by the apparatus is similar to the implementation scheme described in the above method, so specific limitations in one or more embodiments of the dead zone compensation apparatus provided below may refer to the limitations on the dead zone compensation method in the foregoing, and details are not described herein again.

In one embodiment, as shown in fig. 11, a dead-band compensation apparatus 1100 is provided, comprising an obtaining module 1102, a phase current polarity determining module 1104, and a target on-time determining module 1106, wherein:

an obtaining module 1102, configured to obtain a dead-time compensation time setting value and an action timing sequence of each phase of switching unit in the inverter;

a phase current polarity determining module 1104, configured to determine a phase current polarity change condition of each phase according to the action time sequence and a preset correspondence between the action time sequence and the phase current polarity change condition;

and a target on-time determining module 1106, configured to obtain a target on-time of the corresponding phase switching unit according to the change condition of the polarity of each phase current and the dead-time compensation time setting value.

In one embodiment, the phase current polarity change condition includes: the phase current polarity is unchanged, and the phase current polarity is positive, and the phase current polarity is unchanged, and the phase current polarity is negative; the target on-time determining module 1103 is specifically configured to:

In one embodiment, the inverter is a three-phase inverter, and the phase current polarity change condition comprises a change in phase current polarity; the target on-time determination module is further configured to: determining adjacent non-zero basic space voltage vectors acting on corresponding phases based on a space vector pulse width modulation method; and acquiring the action time of each nonzero basic space voltage vector, and acquiring the target conduction time of the corresponding switch unit according to the action time of each nonzero basic space voltage vector and the dead zone compensation time set value.

In one embodiment, the dead zone compensation apparatus further comprises: and the dead zone compensation time set value determining module is used for determining a dead zone compensation time set value based on the working parameters of the motor system.

In one embodiment, the inverter is applied to a permanent magnet synchronous motor system; the dead time compensation time set value determination module is specifically configured to: acquiring working parameters of a permanent magnet synchronous motor system, and calculating according to the working parameters to obtain the actual voltage of the permanent magnet synchronous motor; acquiring the command voltage of a permanent magnet synchronous motor system, and calculating to obtain error voltage according to the actual voltage and the command voltage; and determining a dead-time compensation time set value according to the error voltage.

In one embodiment, the actual voltage of the permanent magnet synchronous motor system refers to the q-axis voltage of the permanent magnet synchronous motor in the permanent magnet synchronous motor system.

The modules in the dead zone compensation device can be wholly or partially realized by software, hardware and a combination thereof. The modules can be embedded in a hardware form or independent from a processor in the computer device, and can also be stored in a memory in the computer device in a software form, so that the processor can call and execute operations corresponding to the modules.

In one embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as shown in fig. 12. The computer device includes a processor, a memory, a communication interface, a display screen, and an input device connected by a system bus. Wherein the processor of the computer device is configured to provide computing and control capabilities. The memory of the computer device comprises a nonvolatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of an operating system and computer programs in the non-volatile storage medium. The communication interface of the computer device is used for carrying out wired or wireless communication with an external terminal, and the wireless communication can be realized through WIFI, a mobile cellular network, NFC (near field communication) or other technologies. The computer program is executed by a processor to implement a dead-zone compensation method. The display screen of the computer equipment can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer equipment can be a touch layer covered on the display screen, a key, a track ball or a touch pad arranged on the shell of the computer equipment, an external keyboard, a touch pad or a mouse and the like.

Those skilled in the art will appreciate that the architecture shown in fig. 12 is merely a block diagram of some of the structures associated with the disclosed aspects and is not intended to limit the computing devices to which the disclosed aspects apply, as particular computing devices may include more or less components than those shown, or may combine certain components, or have a different arrangement of components.

In one embodiment, a computer device is provided, comprising a memory and a processor, the memory having stored therein a computer program, the processor implementing the steps of the above-described method embodiments when executing the computer program.

In an embodiment, a computer-readable storage medium is provided, on which a computer program is stored which, when being executed by a processor, carries out the steps of the above-mentioned method embodiments.

In an embodiment, a computer program product is provided, comprising a computer program which, when being executed by a processor, carries out the steps of the above-mentioned method embodiments.

It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, database, or other medium used in the embodiments provided herein may include at least one of non-volatile and volatile memory. The nonvolatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical Memory, high-density embedded nonvolatile Memory, resistive Random Access Memory (ReRAM), magnetic Random Access Memory (MRAM), ferroelectric Random Access Memory (FRAM), phase Change Memory (PCM), graphene Memory, and the like. Volatile Memory can include Random Access Memory (RAM), external cache Memory, and the like. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM), among others. The databases involved in the embodiments provided herein may include at least one of relational and non-relational databases. The non-relational database may include, but is not limited to, a block chain based distributed database, and the like. The processors referred to in the embodiments provided herein may be general purpose processors, central processing units, graphics processors, digital signal processors, programmable logic devices, quantum computing based data processing logic devices, etc., without limitation.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, and these are all within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A dead zone compensation method, comprising:

2. The method of claim 1, wherein the phase current polarity change condition comprises any one of the following three conditions:

the phase current polarity changes.

3. The method of claim 2, wherein the phase current polarity change condition comprises: the phase current polarity is unchanged, and the phase current polarity is positive, and the phase current polarity is unchanged, and the phase current polarity is negative; the obtaining of the target on-time of the corresponding phase switch unit according to the change condition of the polarity of each phase current and the dead-time compensation time setting value includes:

4. The method of claim 2, wherein the inverter is a three-phase inverter, and the phase current polarity change comprises a change in phase current polarity; the obtaining of the target on-time of the corresponding phase switch unit according to the change condition of the polarity of each phase current and the dead-time compensation time setting value includes:

and acquiring the action time of each nonzero basic space voltage vector, and acquiring the target conduction time of the corresponding switch unit according to the action time of each nonzero basic space voltage vector and the dead zone compensation time set value.

5. The method according to any one of claims 1 to 4, wherein before obtaining the dead-time compensation time set value, the method further comprises:

6. The method of claim 5, wherein the inverter is applied to a permanent magnet synchronous motor system; the dead-time compensation time setting value is determined based on the working parameters of the motor, and the dead-time compensation time setting value comprises the following steps:

7. The method of claim 6, wherein the actual voltage of the PMSM system is a q-axis voltage of a PMSM in the PMSM system.

8. A dead-zone compensation apparatus, comprising:

9. A computer device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor, when executing the computer program, implements the steps of the method of any of claims 1 to 7.

10. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the method of any one of claims 1 to 7.