CN112701950A - Dead-zone clamping compensation method and compensation system for frequency converter - Google Patents

Dead-zone clamping compensation method and compensation system for frequency converter Download PDF

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CN112701950A
CN112701950A CN202011606697.9A CN202011606697A CN112701950A CN 112701950 A CN112701950 A CN 112701950A CN 202011606697 A CN202011606697 A CN 202011606697A CN 112701950 A CN112701950 A CN 112701950A
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compensation
current
angle
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value
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CN112701950B (en
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黎国才
徐益飞
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Suzhou Weichuang Electrical Technology Co ltd
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Suzhou Weichuang Electrical Technology Co ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/22—Current control, e.g. using a current control loop
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
    • H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
    • H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
    • H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P4/00—Arrangements specially adapted for regulating or controlling the speed or torque of electric motors that can be connected to two or more different electric power supplies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)
  • Control Of Ac Motors In General (AREA)

Abstract

The application relates to a dead-zone clamping compensation method and a dead-zone clamping compensation system for a frequency converter. The method comprises the following steps: acquiring a clamp vector current compensation angle; acquiring a current compensation duty ratio according to the actual dead zone time length and the carrier cycle time length; and acquiring a compensation value of the current compensation duty ratio corresponding to the phase current vector angle range according to the clamp vector current compensation angle and the current compensation duty ratio, wherein the compensation value is in a linear relation with the phase current vector angle in different phase current vector angle ranges. The clamping phenomenon when the current passes through zero is effectively restrained, and the technical problems that the current output quality is poor and the low-speed control performance of the electrode is poor due to the clamping phenomenon are solved.

Description

Dead-zone clamping compensation method and compensation system for frequency converter
Technical Field
The application relates to the technical field of frequency converters, in particular to a dead-zone clamping compensation method and system for a frequency converter.
Background
In the PWM driving of a three-phase inverter bridge of a frequency converter, in order to prevent short-circuit fault from occurring in the direct connection of upper and lower bridge arms, a dead time is usually inserted into the PWM driving waveform. The existence of the dead zone causes deviation between the output voltage and the command voltage, in the sensorless vector control occasion, the actual output voltage is generally required to be reconstructed by the motor command voltage to estimate the rotor magnetic field information, the motor command is smaller in low-speed operation, and the error can generate adverse effect on a flux linkage observation link. On the other hand, the dead zone causes the output voltage and current of the motor to generate distortion, and causes a zero current clamping phenomenon, so that the torque ripple of the motor is increased, and the influence of the phenomenon is more serious when the motor runs at a low speed.
Disclosure of Invention
In order to solve the technical problem or at least partially solve the technical problem, the application provides a dead-time clamp compensation method and a compensation system for a frequency converter.
In a first aspect, the present application provides a dead-time clamp compensation method for a frequency converter, the method including:
acquiring the actual dead time duration of the frequency converter in any equivalent previous current period;
acquiring a motor power factor angle in the current period before the current period is equivalent, and acquiring compensation voltage values corresponding to the motor power factor angle in different angle ranges;
obtaining an inductance value, wherein the inductance value is a preset value;
acquiring clamp compensation current values corresponding to the motor power factor angle in different angle ranges according to the compensation voltage value, the actual dead zone time length and the inductance value;
acquiring the current amplitude in the current period;
acquiring a clamp vector current compensation angle according to the clamp compensation current value and the ratio of the current amplitude;
acquiring a current compensation duty ratio according to the actual dead zone time length and the carrier cycle time length;
compensating an angle according to the clamp vector current, and the present compensation duty cycle,
obtaining a compensation value for the current compensation duty cycle corresponding to the phase current vector angle range,
the compensation value is in a linear relationship with the phase current vector angle over different ranges of the phase current vector angle, the linear relationship including:
when-2 thetacomp≤θiWhen the ratio is less than 0, the reaction mixture is,
Figure BDA0002873768190000021
when pi-2 thetacomp≤θiWhen the ratio is less than pi, the reaction solution is mixed,
Figure BDA0002873768190000022
wherein D istFor the current compensation duty cycle, DcompIs a compensation value of the current compensation duty ratio, thetaiIs the phase current vector angle, θcompCompensating an angle for the clamp vector current.
Optionally, the method further comprises: if the compensation value of the current compensation duty ratio is a negative value, the phase voltage compensation trend is reduced on the basis of the current phase voltage;
and if the compensation value of the current compensation duty ratio is a positive value, the phase voltage compensation trend is increased on the basis of the current phase voltage.
Optionally, the obtaining an actual dead-time duration of the frequency converter in any current cycle includes:
acquiring preset dead zone time of the frequency converter;
acquiring the time length required for turning on the power device and the time length required for turning off the power device,
acquiring a time length difference of time lengths required by the on and off of the power device according to the time length of the on power device and the time length of the off power device;
and acquiring the actual dead zone time length according to the dead zone time length and the time length difference.
Optionally, the obtaining the motor power factor angle in the phase current period includes:
acquiring a vector angle of the phase current;
acquiring a vector angle of the phase voltage;
and acquiring the power factor angle of the motor according to the vector angle of the phase voltage and the vector angle of the phase current.
Optionally, the compensation method further includes, during the current cycle, performing clamp compensation on three-phase voltages in sequence according to the compensation method.
In a second aspect, the present application provides a frequency converter dead-time clamp compensation system, the system comprising:
a parameter obtaining module for obtaining the actual dead time duration of the frequency converter in any phase current period,
used for obtaining the motor power factor angle in the phase current period and obtaining the compensation voltage values corresponding to the motor power factor angle in different angle ranges,
the current detection circuit is also used for obtaining the preset inductance value and the current phase current value;
the clamping compensation module is used for acquiring clamping compensation current values corresponding to the motor power factor angle in different angle ranges according to the compensation voltage value, the actual dead zone time length and the preset inductance value;
the parameter obtaining module is further configured to obtain a current amplitude value in the current period, and obtain a clamp vector current compensation angle according to the ratio of the clamp compensation current value to the current amplitude value;
the clamping compensation module is also used for acquiring the current compensation duty ratio according to the actual dead zone time length and the carrier period time length; and is further configured to obtain a compensation value for the current compensation duty cycle corresponding to the phase current vector angle range based on the clamp vector current compensation angle and the current compensation duty cycle,
the compensation value is in a linear relationship with the phase current vector angle over different ranges of the phase current vector angle, the linear relationship including:
when-2 thetacomp≤θiWhen the ratio is less than 0, the reaction mixture is,
Figure BDA0002873768190000031
when pi-2 thetacomp≤θiWhen the ratio is less than pi, the reaction solution is mixed,
Figure BDA0002873768190000032
wherein D istFor the current compensation duty cycle, DcompIs a compensation value of the current compensation duty ratio, thetaiIs the phase current vector angle, θcompCompensating an angle for the clamp vector current.
Optionally, the clamp compensation module is further configured to, if the compensation value of the current compensation duty ratio is a negative value, decrease the phase voltage compensation trend on the basis of a current phase voltage;
and if the compensation value of the current duty ratio is a positive value, the phase voltage compensation trend is increased on the basis of the current phase voltage.
Optionally, the parameter obtaining module is configured to obtain a preset dead time duration of the frequency converter; and for obtaining a desired duration for turning on the power device and a desired duration for turning off the power device,
acquiring a time length difference of time lengths required by the on and off of the power device according to the time length of the on power device and the time length of the off power device;
and acquiring the actual dead zone time length according to the dead zone time length and the time length difference.
Optionally, the parameter obtaining module is further configured to obtain a vector angle of the phase current;
acquiring a vector angle of the phase voltage;
and acquiring the power factor angle of the motor according to the vector angle of the phase voltage and the vector angle of the phase current.
Optionally, the clamping compensation module is further configured to, in the current cycle, clamp and compensate three-phase voltages in sequence according to the compensation method.
The application provides a frequency converter dead zone clamping compensation method, which comprises the steps of obtaining the actual dead zone time length of a frequency converter in any phase current period, obtaining a motor power factor angle in the phase current period, obtaining compensation voltage values and inductance values of the motor power factor angle in different angle ranges, obtaining clamping compensation current values corresponding to the motor power factor angle in different angle ranges, and obtaining a clamping vector current compensation angle according to the clamping compensation current value and the ratio of the current amplitude; acquiring a current compensation duty ratio according to the actual dead zone time length and the carrier cycle time length; according to the clamp vector current compensation angle and the current compensation duty ratio, a compensation value of the current compensation duty ratio corresponding to the phase current vector angle range is obtained, dead-zone clamp advanced compensation is performed on the frequency converter, and the compensation value is in a linear relation with the phase current vector angle within different phase current vector angle ranges, so that the clamp phenomenon when current passes through zero is effectively inhibited, and the output current quality of the frequency converter and the low-speed control performance of the motor are improved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.
FIG. 1 is a flow chart of a dead-time clamp compensation method for a frequency converter according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a three-phase inverter bridge of a frequency converter according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of clamping when the phase current of phase a crosses zero from negative to positive in the embodiment of the present invention;
FIG. 4 is a schematic diagram of clamping when the phase current of phase a crosses zero from positive to negative in the embodiment of the present invention;
FIG. 5 is a waveform diagram illustrating duty cycle compensation in an embodiment of the present invention;
FIG. 6 is a waveform diagram after dead-time clamp compensation in an embodiment of the present invention;
fig. 7 is a schematic structural diagram of a dead-time clamp compensation system of a frequency converter according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Referring to fig. 1, in an embodiment of the present application, there is provided a frequency converter dead-zone clamp compensation method, including:
step 101: acquiring the actual dead zone time length of the frequency converter in any phase current period;
step 102: acquiring a motor power factor angle in a phase current period, acquiring compensation voltage values corresponding to the motor power factor angle in different angle ranges, and acquiring an inductance value;
step 103: acquiring clamp compensation current values corresponding to the power factor angle of the motor in different angle ranges according to the compensation voltage value, the actual dead zone time length and a preset inductance value;
step 104: acquiring a current amplitude in a current period;
step 105: acquiring a clamp vector current compensation angle according to the ratio of the clamp compensation current value to the current amplitude;
step 106: acquiring a current compensation duty ratio according to the actual dead zone time length and the carrier cycle time length;
step 107: obtaining a compensation value of the current compensation duty ratio corresponding to the phase current vector angle range according to the clamp vector current compensation angle and the current compensation duty ratio, wherein the compensation value has a linear relation with the phase current vector angle in different phase current vector angle ranges, and the linear relation comprises:
when-2 thetacomp≤θiWhen the ratio is less than 0, the reaction mixture is,
Figure BDA0002873768190000061
when pi-2 thetacomp≤θiWhen the ratio is less than pi, the reaction solution is mixed,
Figure BDA0002873768190000062
wherein D istFor the current compensation duty cycle, DcompFor the compensation value of the current compensation duty ratio, thetaiIs the phase current vector angle, θcompThe angle is compensated for the clamp vector current.
In the embodiment of the application, referring to fig. 2, fig. 3 and fig. 4, fig. 2 is a three-phase inverter bridge of a frequency converter, and fig. 3 is a current clamp schematic diagram of a-phase current from negative to positive zero-crossing point;
the dead zone is a protection period set for preventing the upper and lower bridge arm power devices from being conducted simultaneously due to the problem of switching speed, and generally refers to a '0' zone of the output voltage and current of the power devices in a frequency converter; referring to fig. 3, there is an actual dead time between time a and C.
In the embodiment of the application, in the section A-B, VT4 is turned off, iaFollow current from D1, connect point a to positive bus, and actually output current iaAnd the actual output voltage uanEqual to the current and voltage under ideal condition, and has no error. At time B, iaAnd reduced to 0. In the B-C section, ideally, VT1 is conducted, the point a is connected with the positive bus, and the ideal current
Figure BDA0002873768190000071
Starting from 0 and increasing in the positive direction. Actually due to the dead zone, VT1 is now off, so the actual current iaClamped at 0 and a now floating, the actual output voltage uanEqual to the back-emf on winding a. Namely, the BC section generates errors in the actual output voltage and current and the ideal condition due to clamping.
In an embodiment of the application, the motor power factor angle
Figure BDA0002873768190000072
Thus voltage vector angle θvIs between 0 and 90 degrees. When 0 is not less than thetavWhen the voltage vector is in the I sector and the phase a is dead, the phase b and the phase c are both open lower bridge arms, namely the phase b current flows through VT6, the phase c current flows from D2, and at the moment, the phase b and the phase c current flow through VT6
Figure BDA0002873768190000073
When the angle is more than or equal to 60 degreesvWhen the voltage vector is in the sector II and the phase a is dead zone < 90 degrees, the upper bridge arm of the phase b is opened, the lower bridge arm of the phase c is opened, namely, the phase b current continues to flow from D3, the phase c current continues to flow from D2,
Figure BDA0002873768190000074
at low frequency, neglecting back electromotive force and resistance voltage drop, ideal voltage
Figure BDA0002873768190000075
Namely the error voltage when clamping the dead zone, namely the voltage needing compensation when clamping.
In the embodiment of the present application, the voltage expression in the stationary coordinate system is:
Figure BDA0002873768190000076
Figure BDA0002873768190000077
wherein Rs is stator resistance, uα，uβ，iα，iβVoltage, current, respectively, of the stator of the machine in the alpha and beta axes, EsαAnd EsβRespectively, the back-emf.
In the examples of the present application, LσEqual to leakage inductance σ L for asynchronous machinessFor a surface-mounted synchronous machine, equal to the q-axis inductance Lq。
In the case of low-frequency operation,
Figure BDA0002873768190000078
much larger than the resistive voltage drop and back-emf, negligible. The voltage equation can be approximated as
Figure BDA0002873768190000081
Setting the current at the start time of the dead zone as iaWhen the current is reduced to 0 for a time delta T, then
Figure BDA0002873768190000082
Namely, it is
Figure BDA0002873768190000083
At DeltaT < Td(i.e. the
Figure BDA0002873768190000084
) Clamping occurs. Order to
Figure BDA0002873768190000085
According to the above expression of the error voltage at the time of clamping when
Figure BDA0002873768190000086
When the temperature of the water is higher than the set temperature,
Figure BDA0002873768190000087
when the temperature of the water is higher than the set temperature,
Figure BDA0002873768190000088
therefore, the clamping current of the phase a meets the condition that the phase a current is from negative to positive, and the phase-I current is from negative to positiveth＜ia< 0, 0 < i when the phase current of a goes from positive to negativea＜Ith。
In the embodiment of the application, the stator side current i is obtaineda,ib,icThe current i under the two-phase static coordinate system is obtained through 3/2 transformationα，iβObtaining the current amplitude
Figure BDA0002873768190000089
Obtaining the compensation angle of the clamp vector current according to the current amplitude
Figure BDA00028737681900000810
Referring to fig. 5, the x-axis of fig. 5 represents the current period phase current, and the y-axis represents the compensation value of the current compensation duty ratio;
in the embodiments of the present application, let I ═ I be the currentmsin theta, sin theta is approximately equal to theta at zero crossing point and is equal to-2 thetacomp≤θiWhen the phase current is less than 0, the polarity of the phase current begins to change from negative to positive, which can be obtained according to the compensation angle, the duty ratio required to be compensated and the phase current vector angle are in a linear relation,
Figure BDA00028737681900000811
in the examples of the present application, in pi-2 thetacomp≤θiWhen the phase current is less than pi, the polarity of the phase current begins to change from positive to negative, which can be obtained according to the compensation angle, the duty ratio required to be compensated and the phase current vector angle are in a linear relation,
Figure BDA00028737681900000812
in the embodiment of the application, the inverter main circuit cannot accurately reproduce an ideal waveform generated by a pulse width modulation generator due to the dead zone effect, so that the voltage and the current are distorted during low-speed and light load, and torque ripple is causedAnd harmonic waves, therefore, according to the clamp compensation current value and the current phase current amplitude value, obtaining a clamp vector current compensation angle, and according to the current compensation duty ratio, obtaining a compensation value of the current compensation duty ratio, wherein the compensation ratio and the phase current vector angle are in a linear relation in different ranges, and performing linear compensation; the compensation value of the current compensation duty ratio is-2 thetacomp≤θi< 0 and π -2 θcomp≤θiThe value of the phase current vector angle range < pi is respectively
Figure BDA0002873768190000091
The clamping phenomenon of current zero crossing can be effectively inhibited, the output current quality and the low-speed running performance of the motor are improved, the current mutation phenomenon in the compensation process is reduced, and the reliability of the compensation process is improved; the precision of the system is improved; in addition, in the actual digital circuit control, the compensation error caused by floating point operation can be reduced by converting the compensation voltage into a compensation form of corresponding duty ratio.
In the examples of the present application, when- π ≦ θi＜-2θcompAnd 0. ltoreq. thetai＜π-2θcompAnd in time, the dead zone is compensated in a conventional duty ratio compensation mode: i.e. at-pi ≦ thetai＜-2θcompIn the time, the phase current is negative, the existence of the dead zone causes the actual voltage to be higher, therefore, a compensation mode of reducing the duty ratio is adopted, and the compensation value D of the current compensation duty ratio at the timecomp＝-Dt(ii) a Theta is more than or equal to 0i＜π-2θcompIn the time, the phase current is positive, the existence of the dead zone causes the actual voltage to be lower, therefore, a compensation mode of increasing the duty ratio is adopted, and the compensation value D of the current compensation duty ratio at the timecomp＝Dt。
Figure BDA0002873768190000101
In the embodiment of the application, if the obtained current compensation duty ratio compensation value is a positive value, it indicates that the voltage value to be compensated is in an increasing trend on the basis of the current phase voltage; if the obtained current compensation duty ratio compensation value is a negative value, the current compensation duty ratio compensation value indicates that the voltage value needing compensation is a trend of decreasing on the basis of the current phase voltage.
In the embodiment of the application, referring to fig. 6, the compensation time and the duty ratio obtained according to the method are input into simulation software to generate a current waveform diagram as shown in fig. 6, an ideal waveform with distortion removed at a current zero crossing point is obtained, and a clamping phenomenon of the current zero crossing point is effectively inhibited.
In the embodiment of the present application, obtaining the actual dead-time duration of the frequency converter in any current cycle includes:
acquiring preset dead zone time of a frequency converter;
acquiring the time length required for turning on the power device and the time length required for turning off the power device,
acquiring the time difference of the time required by the on and off of the power device according to the time for turning on the power device and the time for turning off the power device;
and acquiring the actual dead zone time length according to the dead zone time length and the time length difference.
In the embodiment of the application, as shown in fig. 2, in the phase a, the power devices are VT1 and VT4, and in practical application, there is a certain delay time for turning on and off of VT1 and VT4, and the delay time is often asynchronous, so that the difference between the time lengths required for turning on and off the power devices is added to the preset time length of the dead zone of the frequency converter, so that the dead zone time length has a more reference meaning in calculating the clamp current value.
Td＝Td_set+Ton-ToffWherein, TdFor the actual dead time duration, Td_setFor a predetermined dead time duration, T, of the frequency converteronRequired duration, T, for switching on the power deviceoffFor the desired duration of the power device being turned off.
In an embodiment of the present application, obtaining a motor power factor angle in a phase current period comprises:
acquiring a vector angle of phase current;
acquiring a vector angle of a phase voltage;
and acquiring a power factor angle of the motor according to the vector angle of the phase voltage and the vector angle of the phase current.
In the embodiment of the application, the stator side current i is obtaineda,ib,icThe current i under the two-phase static coordinate system is obtained through 3/2 transformationα，iβTo i, pairα，iβCarrying out park transformation to obtain the current i under a rotating coordinate systemd，iqTo suppress noise and high-frequency interference pairs id，iqAnd performing low-pass filtering processing. Then according to the filtered current idflt，iqfltObtaining current vector angle
Figure BDA0002873768190000111
Where θ is the rotor flux linkage angle, and θ ∈ [ - π, π).
Respectively obtain ia,ib,icThe phase angle of the three-phase stator currents,
Figure BDA0002873768190000112
Figure BDA0002873768190000113
obtaining voltage vector angle
Figure BDA0002873768190000114
Wherein u isdAnd uqRespectively d-axis voltage and q-axis voltage to obtain the power factor angle of the motor
Figure BDA0002873768190000115
In an embodiment of the present application, by converting a three-phase current to a two-phase rotating coordinate system, the polarity of the three-phase current can be obtained by obtaining a current vector angle.
In the embodiment of the application, three-phase voltages are sequentially subjected to clamp compensation according to the compensation method in a current period.
In an embodiment of the present application, referring to fig. 7, the present application provides a frequency converter dead-time clamp compensation system, comprising: the parameter obtaining module 301 is configured to obtain an actual dead time duration of the frequency converter in any phase current period, obtain a motor power factor angle in the phase current period, obtain compensation voltage values corresponding to the motor power factor angle in different angle ranges, and obtain a preset inductance value and obtain a current phase current value.
The clamp compensation module 302 is configured to obtain a clamp compensation current value corresponding to a power factor angle of the motor in different angle ranges according to the compensation voltage value, the actual dead time and a preset inductance value;
the parameter acquisition module is further used for acquiring a current amplitude value in a current period and acquiring a clamp vector current compensation angle according to a clamp compensation current value and the ratio of the current amplitude value;
the clamping compensation module is also used for acquiring the current compensation duty ratio according to the actual dead zone time length and the carrier period time length; and is further configured to obtain a compensation value for a current compensation duty cycle corresponding to the phase current vector angle range based on the clamp vector current compensation angle and the current compensation duty cycle,
the compensation value is in a linear relationship with the phase current vector angle within different phase current vector angle ranges, the linear relationship comprising:
when-2 thetacomp≤θiWhen the ratio is less than 0, the reaction mixture is,
Figure BDA0002873768190000121
when pi-2 thetacomp≤θiWhen the ratio is less than pi, the reaction solution is mixed,
Figure BDA0002873768190000122
wherein D istFor the current compensation duty cycle, DcompFor the compensation value of the current compensation duty ratio, thetaiIs the phase current vector angle, θcompCompensating an angle for the clamp vector current.
In the embodiment of the application, the parameter obtaining module 301 obtains the clamp compensation current value, and the clamp compensation module 302 performs advanced compensation on clamp in a dead zone according to the obtained compensation value of the current compensation duty ratio, so that the clamping phenomenon when the current passes through zero is effectively inhibited, and the control precision of the system and the low-speed running performance of the motor are improved.
A pulse width modulation module 303, configured to receive a compensation value of the current compensation duty cycle, where the compensation value includes a compensation value obtained according to the linear compensation manner and a conventional compensation manner; and superposing the compensation value with the current duty ratio to obtain the duty ratio of the next carrier period, generating the pulse width of the next carrier period, and adjusting the pulse width in the next carrier period.
In the embodiment of the application, the clamp compensation module 302 and the pulse width modulation module 303 which are arranged in the system inhibit the current distortion influence caused by the dead-zone clamp effect, improve the current quality output by the main circuit of the frequency converter, and further enable the motor to run more smoothly.
In the embodiment of the present application, the parameter obtaining module 301 is further configured to obtain a preset dead time duration of the frequency converter; and for obtaining the required time period for turning on the power device and the required time period for turning off the power device,
acquiring the time difference of the time required by the on and off of the power device according to the time for turning on the power device and the time for turning off the power device;
and acquiring the actual dead zone time length according to the dead zone time length and the time length difference.
In an embodiment of the present application, the parameter obtaining module 301 is further configured to obtain a vector angle of the phase current;
acquiring a vector angle of a phase voltage;
and acquiring a power factor angle of the motor according to the vector angle of the phase voltage and the vector angle of the phase current.
In an embodiment of the present application, the clamp compensation module 302 of the compensation system is further configured to clamp and compensate three-phase voltages in sequence according to the compensation method in the current cycle.
FIG. 1 is a flow chart illustrating a compensation method according to an embodiment. It should be understood that, although the steps in the flowchart of fig. 1 are shown in order as indicated by the arrows, the steps are not necessarily performed in order 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 portion of the steps in fig. 1 may include multiple sub-steps or multiple stages that are not necessarily performed at the same time, but may be performed at different times, and the order of performance of the sub-steps or stages is not necessarily sequential, but may be performed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.
It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The foregoing are merely exemplary embodiments of the present invention, which enable those skilled in the art to understand or practice the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A frequency converter dead-time clamp compensation method, the method comprising:
acquiring the actual dead time duration of the frequency converter in any equivalent previous current period;
acquiring a motor power factor angle in the current period before the current period is equivalent, and acquiring compensation voltage values corresponding to the motor power factor angle in different angle ranges;
obtaining an inductance value, wherein the inductance value is a preset value;
acquiring clamp compensation current values corresponding to the motor power factor angle in different angle ranges according to the compensation voltage value, the actual dead zone time length and the inductance value;
acquiring the current amplitude in the current period;
acquiring a clamp vector current compensation angle according to the clamp compensation current value and the ratio of the current amplitude;
acquiring a current compensation duty ratio according to the actual dead zone time length and the carrier cycle time length; obtaining a compensation value of the current compensation duty cycle corresponding to the phase current vector angle range according to the clamp vector current compensation angle and the current compensation duty cycle,
the compensation value is in a linear relationship with the phase current vector angle over different ranges of the phase current vector angle, the linear relationship including:
when-2 thetacomp≤θiWhen the ratio is less than 0, the reaction mixture is,
Figure FDA0002873768180000011
when pi-2 thetacomp≤θiWhen the ratio is less than pi, the reaction solution is mixed,
Figure FDA0002873768180000012
wherein D istFor the current compensation duty cycle, DcompFor the current compensationCompensation value of duty ratio thetaiIs the phase current vector angle, θcompCompensating an angle for the clamp vector current.
2. The compensation method of claim 1, wherein if the compensation value of the current compensation duty ratio is a negative value, the phase voltage compensation trend is decreased on the basis of the current phase voltage;
and if the compensation value of the current compensation duty ratio is a positive value, the phase voltage compensation trend is increased on the basis of the current phase voltage.
3. The compensation method of claim 1, wherein the obtaining the actual dead time duration of the frequency converter in any current period comprises:
acquiring preset dead zone time of the frequency converter;
acquiring the required time for turning on a power device and the required time for turning off the power device;
acquiring a time length difference of time lengths required by the on and off of the power device according to the time length of the on power device and the time length of the off power device;
and acquiring the actual dead zone time length according to the dead zone time length and the time length difference.
4. The compensation method of claim 1, wherein said deriving a motor power factor angle over the phase current period comprises:
acquiring a vector angle of the phase current;
acquiring a vector angle of the phase voltage;
and acquiring the power factor angle of the motor according to the vector angle of the phase voltage and the vector angle of the phase current.
5. The compensation method according to any one of claims 1 to 4, further comprising,
and in the current period, carrying out clamp compensation on the three-phase voltage in sequence according to the compensation method.
6. A frequency converter dead-time clamp compensation system, the system comprising:
a parameter obtaining module for obtaining the actual dead time duration of the frequency converter in any phase current period,
the compensation circuit is used for acquiring a motor power factor angle in the phase current period, acquiring compensation voltage values corresponding to the motor power factor angle in different angle ranges, and also acquiring the preset inductance value and the current phase current value;
the clamping compensation module is used for acquiring clamping compensation current values corresponding to the motor power factor angle in different angle ranges according to the compensation voltage value, the actual dead zone time length and the preset inductance value;
the parameter obtaining module is further configured to obtain a current amplitude value in the current period, and obtain a clamp vector current compensation angle according to the ratio of the clamp compensation current value to the current amplitude value;
the clamping compensation module is also used for acquiring the current compensation duty ratio according to the actual dead zone time length and the carrier period time length; and is further configured to obtain a compensation value for the current compensation duty cycle corresponding to the phase current vector angle range based on the clamp vector current compensation angle and the current compensation duty cycle,
the compensation value is in a linear relationship with the phase current vector angle over different ranges of the phase current vector angle, the linear relationship including:
when-2 thetacomp≤θiWhen the ratio is less than 0, the reaction mixture is,
Figure FDA0002873768180000031
when pi-2 thetacomp≤θiWhen the ratio is less than pi, the reaction solution is mixed,
Figure FDA0002873768180000032
wherein D istFor the current compensation duty cycle, DcompIs a compensation value of the current compensation duty ratio, thetaiIs the phase current vector angle, θcompCompensating an angle for the clamp vector current.
7. The compensation system of claim 6, wherein the clamp compensation module is further configured to decrease the phase voltage compensation trend on the basis of a current phase voltage if the compensation value of the current compensation duty cycle is a negative value;
and if the compensation value of the current compensation duty ratio is a positive value, the phase voltage compensation trend is increased on the basis of the current phase voltage.
8. The compensation system of claim 6,
the parameter acquisition module is further used for acquiring the preset dead zone time length of the frequency converter; and for obtaining a desired duration for turning on the power device and a desired duration for turning off the power device,
acquiring a time length difference of time lengths required by the on and off of the power device according to the time length of the on power device and the time length of the off power device;
and acquiring the actual dead zone time length according to the dead zone time length and the time length difference.
9. The compensation system of claim 6, wherein the parameter acquisition module is further configured to acquire a vector angle of the phase current;
acquiring a vector angle of the phase voltage;
and acquiring the power factor of the motor according to the vector angle of the phase voltage and the vector angle of the phase current.
10. The compensation system of any one of claims 6-9, wherein the clamp compensation module is further configured to clamp compensate three-phase voltages in sequence according to the compensation method during the current cycle.
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