CN112398413A - Frequency converter torque lifting system and method and frequency converter - Google Patents
Frequency converter torque lifting system and method and frequency converter Download PDFInfo
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- CN112398413A CN112398413A CN201910740088.3A CN201910740088A CN112398413A CN 112398413 A CN112398413 A CN 112398413A CN 201910740088 A CN201910740088 A CN 201910740088A CN 112398413 A CN112398413 A CN 112398413A
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- 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
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- 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
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- 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
- H02P21/24—Vector control not involving the use of rotor position or rotor speed sensors
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Abstract
The invention discloses a torque lifting system and method for a frequency converter and the frequency converter. This converter torque lift system includes: the current sampling unit is used for sampling a three-phase current of a motor electrically connected with the frequency converter and converting the three-phase current into a two-phase d-axis current and a two-phase q-axis current; the low-pass filtering unit is electrically connected with the current sampling unit and used for receiving the automatic torque compensation filtering gain and carrying out low-frequency filtering on the q-axis current input by the current sampling unit according to the automatic torque compensation filtering gain to obtain the filtered q-axis current; and the compensation voltage generating unit is electrically connected with the low-pass filtering unit and used for receiving the rated slip, the motor capacity of the motor, the automatic torque compensation voltage gain and related parameters of the motor and determining the automatic torque compensation voltage of the frequency converter according to the rated slip, the motor capacity of the motor, the automatic torque compensation voltage gain, the related parameters of the motor and the filtered q-axis current input by the low-pass filtering unit.
Description
Technical Field
The invention relates to the technical field of motor control, in particular to a system and a method for improving torque of a frequency converter and the frequency converter.
Background
Torque boost, also known as torque compensation, is a method to compensate for the increase in V/F in the low frequency range caused by the decrease in torque due to the resistance of the stator windings when the motor is operating at low speed. The frequency converter drives the motor from a static state to a certain running speed within a certain time, and needs to overcome the static torque resistance and the running acceleration torque resistance of a mechanical device. Because the excitation voltage of the motor is reduced during low-speed operation, the underexcitation state of the motor needs to be supplemented, so that the torque is increased during low-speed operation of the motor, and the resistance of two types of torque is overcome.
The torque lifting function is used for changing the low-speed performance of the frequency converter in the starting stage, so that the output torque of the motor meets the starting requirement of production machinery. When the inverter operates in a V/F manner, the output voltage of the inverter is changed in proportion to the output frequency. When the frequency converter operates in the low frequency region, the output voltage also becomes proportionally smaller. Due to the voltage division of the stator resistance and the leakage reactance, the excitation current decreases and the output torque decreases. For this reason, it is necessary to compensate for a voltage drop in a low frequency region due to the stator resistance voltage division. In addition to the leakage reactance of the motor being not only frequency dependent but also motor current dependent, accurate compensation is difficult.
At present, the frequency converter industry divides torque compensation into manual torque compensation and automatic torque compensation according to a voltage compensation mode.
Under the control method of manual torque compensation, due to the fact that the compensation amount is fixed, the situation that the exciting current is too large to cause overheating of the motor and even burning of the motor is easily caused at some moments.
Automatic torque compensation performs voltage compensation by resolving d-axis (flux) and q-axis (torque) voltage components. I.e. the compensation voltage VqseThe calculation is divided into two parts, one part is caused by the electronic resistor, and the part can pass through the resistance value R of the stator resistorsAnd q-axis current component IqseMultiplying to obtain; another part is caused by leakage reactance, which can pass through the d-axis current component IdseAnd stator inductance LsAnd electrical angular velocity ωeAnd multiplying the two to obtain the product. The two parts together constitute the compensation of the output voltage. In particular, the compensation voltage VqseCan be calculated according to the following equation (1):
Vqse＝Rs×Iqse+ωe×Ls×Idse (1)
although the torque compensation mode can enable the motor to automatically obtain proper torque improvement, the phenomena of over excitation and under excitation of the motor are effectively reduced. But this method needs to rely on precise motor parameters. If the motor parameters are not accurate enough, better control cannot be achieved. As can be seen from the above formula (1), it uses parameters such as the stator resistance and inductance of the motor. However, most motor nameplates have no related parameter information inside the motor, so that accurate product information cannot be obtained in debugging for many application occasions. The motor needs to be identified, and if the identified parameters are not accurate enough, the calculation of the compensation voltage is not accurate enough, so that the driving effect is influenced.
In addition, a PI controller is added in the compensation mode. Since the gain inside the PI controller is fixed, the gain of the PI controller cannot be adjusted according to the variation of the load, and thus, when the load decreases, a response delay may occur.
The above information disclosed in this background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not constitute prior art that is already known to a person of ordinary skill in the art.
Disclosure of Invention
In view of the above, the present invention provides a system and a method for increasing torque of a frequency converter, and a frequency converter.
Additional features and advantages of the invention will be set forth in the detailed description which follows, or may be learned by practice of the invention.
According to an aspect of the present invention, there is provided a frequency converter torque boost system, comprising: the current sampling unit is used for sampling a three-phase current of a motor electrically connected with the frequency converter and converting the three-phase current into two-phase d-axis current and q-axis current; the low-pass filtering unit is electrically connected with the current sampling unit and used for receiving an automatic torque compensation filtering gain and carrying out low-frequency filtering on the q-axis current input by the current sampling unit according to the automatic torque compensation filtering gain to obtain the filtered q-axis current; and the compensation voltage generating unit is electrically connected with the low-pass filtering unit and used for receiving the rated slip, the motor capacity of the motor, the automatic torque compensation voltage gain and the related parameters of the motor and determining the automatic torque compensation voltage of the frequency converter according to the rated slip, the motor capacity of the motor, the automatic torque compensation voltage gain, the related parameters of the motor and the filtered q-axis current input by the low-pass filtering unit.
According to an embodiment of the present invention, the compensation voltage generating unit includes: a first subunit for determining the automatic torque compensation voltage according to the following equation:
Vcomp＝fSlip*VMax*VGainAtb/fbase*Iq_filter/Irated
fSlip＝s*fout
s＝N/(60*fbase/p)
N＝(60*fbase/p)–n
VMax＝(1<<12)*2/1.732*Vmotor/Vinv
wherein, VcompCompensating the voltage for said automatic torque, fSlipIs slip frequency, s is slip ratio, foutIs the actual output frequency of the frequency converter, N is the rated slip, fbaseIs the fundamental frequency of the motor, p is the number of pole pairs of the motor, n is the rated rotation speed of the motor, VMaxIs the maximum output voltage, V, of the frequency convertermotorIs the rated voltage, V, of the motorinvIs the rated voltage, V, of the frequency converterGainAtbCompensating the voltage gain for said automatic torque, Iq_filterIs the filtered q-axis current, IratedIs rated for the motorA current, a rated current of the electric machine being related to a motor capacity of the electric machine.
According to an embodiment of the present invention, the automatic torque compensation voltage gain includes: the electric state torque compensation voltage gain and the generating state torque compensation voltage gain; the electric state torque compensation voltage gain is used as the automatic torque compensation voltage gain when the motor is in an electric state, and the automatic torque compensation voltage is calculated; and the generating state torque compensation voltage gain is used as the automatic torque compensation voltage gain when the motor is in a generating state, and the automatic torque compensation voltage is calculated.
According to an embodiment of the invention, the system further comprises: and the voltage instruction generating unit is electrically connected with the compensation voltage generating unit and used for receiving the given frequency of the frequency converter and generating voltage for driving the motor according to the given frequency of the frequency converter and the automatic torque compensation voltage input by the compensation voltage generating unit.
According to an embodiment of the present invention, the voltage command generating unit includes: a second subunit and a third subunit, the second subunit being configured to receive the given frequency after being manually compensated; and the third subunit is used for generating a voltage for driving the motor according to the given frequency after manual compensation and the automatic torque compensation voltage.
According to another aspect of the present invention, there is provided a method for increasing torque of a frequency converter, including: sampling three-phase current of a motor electrically connected with a frequency converter, and converting the three-phase current into two-phase d-axis current and q-axis current; receiving an automatic torque compensation filter gain, and performing low-frequency filtering on the q-axis current according to the automatic torque compensation filter gain to obtain a filtered q-axis current; and receiving a rated slip, a motor capacity of the motor, an automatic torque compensation voltage gain, relevant parameters of the motor and the filtered q-axis current, and determining an automatic torque compensation voltage of the frequency converter according to the rated slip, the motor capacity of the motor, the automatic torque compensation voltage gain, the relevant parameters of the motor and the filtered q-axis current.
According to an embodiment of the present invention, determining the automatic torque compensation voltage of the frequency converter according to the rated slip, the motor capacity of the electric machine, the automatic torque compensation voltage gain, the relevant parameters of the electric machine, and the filtered q-axis current comprises: determining the automatic torque compensation voltage according to the following equation:
Vcomp＝fSlip*VMax*VGainAtb/fbase*Iq/Irated
fSlip＝s*fout
s＝N/(60*fbase/p)
N＝(60*fbase/p)–n
VMax＝(1<<12)*2/1.732*Vmotor/Vinv
wherein, VcompCompensating the voltage for said automatic torque, fSlipIs slip frequency, s is slip ratio, foutIs the actual output frequency of the frequency converter, N is the rated slip, fbaseIs the fundamental frequency of the motor, p is the number of pole pairs of the motor, n is the rated rotation speed of the motor, VMaxIs the maximum output voltage, V, of the frequency convertermotorIs the rated voltage, V, of the motorinvIs the rated voltage, V, of the frequency converterGainAtbCompensating the voltage gain for said automatic torque, IqIs the filtered q-axis current, IratedThe rated current of the electric machine is related to the motor capacity of the electric machine.
According to an embodiment of the present invention, the automatic torque compensation voltage gain includes: the electric state torque compensation voltage gain and the generating state torque compensation voltage gain; the electric state torque compensation voltage gain is used as the automatic torque compensation voltage gain when the motor is in an electric state, and the automatic torque compensation voltage is calculated; and the generating state torque compensation voltage gain is used as the automatic torque compensation voltage gain when the motor is in a generating state, and the automatic torque compensation voltage is calculated.
According to an embodiment of the invention, the method further comprises: receiving a given frequency of the frequency converter; and generating a voltage for driving the motor according to the given frequency and the automatic torque compensation voltage.
According to an embodiment of the invention, receiving the given frequency of the frequency converter comprises: receiving the given frequency after manual compensation; and generating a voltage for driving the motor according to the given frequency and the automatic torque compensation voltage comprises: and generating a voltage for driving the motor according to the given frequency after the manual compensation and the automatic torque compensation voltage.
According to a further aspect of the present invention, there is provided a frequency converter comprising any one of the frequency converter torque boosting systems described above.
Compared with the existing automatic torque hoisting system, the frequency converter torque hoisting system provided by the embodiment of the invention does not need to use motor parameters which cannot be accurately obtained, such as stator resistance, stator inductance and the like, and avoids the problem of inaccurate compensation voltage calculation result caused by inaccurate parameters. In addition, since the PI controller is not used, it is not necessary to adjust the PI gain according to the load variation, and a better driving effect can be obtained under the same load condition.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.
FIG. 1 is a block diagram illustrating an inverter torque boost system in accordance with an exemplary embodiment.
FIG. 2 is a block diagram illustrating another frequency converter torque boost system according to an exemplary embodiment.
Fig. 3 is a block diagram of a frequency converter shown in accordance with an exemplary embodiment.
FIG. 4 is a flow chart illustrating a method of frequency converter torque boost according to an example embodiment.
Fig. 5 is a comparison graph of waveforms after two torque boosting methods are adopted.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The drawings are merely schematic illustrations of the invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus their repetitive description will be omitted.
Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention may be practiced without one or more of the specific details, or with other methods, components, devices, steps, and so forth. In other instances, well-known structures, methods, devices, implementations, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.
FIG. 1 is a block diagram illustrating an inverter torque boost system in accordance with an exemplary embodiment.
Referring to fig. 1, an inverter torque boost system 10 includes: a current sampling unit 12, a low-pass filtering unit 14 and a supplementary voltage generating unit 16.
The current sampling unit 12 is used for sampling a three-phase current of a motor electrically connected with the frequency converter and converting the three-phase current ia、ibAnd icD-axis (flux) current i converted into two phasesdWith q-axis (torque) current iq。
In order to drive the motor to work, three-phase voltage/current needs to be used. In the case of automatic torque compensation, it is necessary to perform voltage compensation by decomposing the d-axis and q-axis voltage components. Therefore, after the current sampling unit 12 collects the three-phase current of the motor, it needs to convert the three-phase current into two-phase d-axis current and q-axis current.
The low pass filter unit 14 is electrically connected to the current sampling unit 12, and is configured to receive the automatic torque compensation filter gain and input the q-axis current I to the current sampling unit 12 according to the automatic torque compensation filter gainqLow-frequency filtering is carried out to obtain the filtered q-axis current Iq_filter。
The Low Pass Filter unit 14 is, for example, a Low Pass Filter (LPF) for resisting the q-axis current IqThe high frequency signal of (2) passes through. I.e. high frequency disturbances therein are eliminated, so that a more accurate current component is obtained for calculating the subsequent automatic torque compensation voltage.
The automatic torque compensation filter gain may be a preset value, for example, manually entered into the low pass filter unit 14 by a human operator. In practical applications, the automatic torque filtering gain may be set according to requirements, or may be modified according to compensation effects, and the invention is not limited thereto.
The compensation voltage generating unit 16 is electrically connected to the low pass filtering unit 14, and is configured to receive the rated slip N, the motor capacity of the electric machine, and the automatic torque compensation voltage gain VGainAtbAnd motor related parameters, and compensating voltage gain V according to rated slip N, motor capacity of motor and automatic torqueGainAtbThe motor related parameters and the filtered q-axis current I input by the low-pass filtering unit 14q_filterDetermining the automatic torque compensation voltage V of the frequency convertercomp。
Wherein, the related parameters of the motor are all related parameters which can be acquired by the name plate of the motor, such as the basic frequency f of the motorbaseThe number p of pairs of the motor, the rated rotating speed n of the motor and the rated voltage V of the motormotorAnd the like.
Compared with the existing automatic torque hoisting system, the frequency converter torque hoisting system provided by the embodiment of the invention does not need to use motor parameters which cannot be accurately obtained, such as stator resistance, stator inductance and the like, and avoids the problem of inaccurate compensation voltage calculation result caused by inaccurate parameters. In addition, since the PI controller is not used, it is not necessary to adjust the PI gain according to the load variation, and a better driving effect can be obtained under the same load condition.
In some embodiments, the compensation voltage generation unit 16 includes a first subunit 162 for determining the automatic torque compensation voltage according to the following equation (1):
Vcomp＝fSlip*VMax*VGainAtb/fbase*Iq_filter/Irated (1)
wherein, VcompCompensating the voltage for the automatic torque; vGainAtbThe gain of the compensation voltage is used as the parameter input of the frequency converter for automatic torque compensation, the gain can be increased or decreased according to the actual effect during debugging, and the corresponding compensation voltage is increased proportionally when the parameter is increased; i isq_filterIs the filtered q-axis current; i isratedThe rated current of the motor is related to the motor capacity of the motor and can be determined by the motor capacity of the motor, and the motor capacity of the motor can be obtained by data on a name plate of the motor; f. ofSlipFor the slip frequency, it can be calculated according to the following equation (2):
fSlip＝s*fout
(2)
wherein f isoutIs the actual output frequency of the frequency converter; s is a slip ratio, and can be calculated according to the following formula (3):
s＝N/(60*fbase/p)
(3)
wherein f isbaseThe frequency converter is a motor basic frequency which can be obtained through data on a motor name board and is also used as a driving common parameter to be input into the frequency converter to be used as a motor driving parameter; p is the number of pole pairs of the motor and can be obtained through data on the name plate of the motor; n is a rated slip received by the compensation voltage generation unit 16, which can be calculated by the following equation (4):
N＝(60*fbase/p)–n (4)
and n is the rated rotating speed of the motor and can also be acquired through data on the name plate of the motor.
VMaxWhich is the maximum output voltage of the frequency converter, can be calculated by the following equation (5):
VMax＝(1<<12)*2/1.732*Vmotor/Vinv (5)
wherein, VmotorThe rated voltage of the motor can be obtained through name plate data on the motor; vinvThe rated voltage of the frequency converter can be obtained through internal parameters of the frequency converter.
The automatic torque compensation voltage calculated by the above formula uses the ratio of the q-axis torque current component to the rated current, and thus the compensation amount and the load amount can be matched.
In some embodiments, the automatic torque compensation voltage gain may further comprise: the motoring state torque compensation voltage gain and the generating state torque compensation voltage gain. The motor-driven state torque compensation voltage gain is used as an automatic torque compensation voltage gain when the motor is in a motor-driven state, and the automatic torque compensation voltage is calculated; and the torque compensation voltage gain in the power generation state is used as an automatic torque compensation voltage gain when the motor is in the power generation state, and the automatic torque compensation voltage is calculated. The motor is in two different states when the motor runs in different quadrants in the electric state and the power generation state. The two gains can be applied in the two states respectively, and can be set according to requirements, debugging effects and the like in practical application.
Furthermore, the frequency converter torque boost system 10 may further include: a voltage command generation unit 18. Voltage command generation unit 18 and compensation circuitThe voltage generating unit 16 is electrically connected to receive the given frequency f of the frequency converter*And according to a given frequency f of the frequency converter*And an automatic torque compensation voltage input by the compensation voltage generating unit for generating a voltage for driving the motor.
In practical applications, the given frequency of the frequency converter may be given internally, for example, by means of an operating panel; it may also be given by external means, such as current or voltage. The invention is not limited thereto.
It should be noted that the voltage for driving the motor is a two-phase voltage, and in order to meet the driving voltage requirement of the motor, the voltage can be converted into a three-phase voltage through a coordinate transformation operation.
It should be clearly understood that the present disclosure describes how to make and use particular examples, but the principles of the present disclosure are not limited to any details of these examples. Rather, these principles can be applied to many other embodiments based on the teachings of the present disclosure.
FIG. 2 is a block diagram illustrating another frequency converter torque boost system according to an exemplary embodiment.
Referring to fig. 2, the difference from the inverter torque boosting system 10 shown in fig. 1 is that the voltage command generating unit 28 of the inverter torque boosting system 20 may further include: a second sub-unit 282 and a third sub-unit 284. Wherein the second subunit 282 is used for receiving the given frequency f after manual compensation*(ii) a The third sub-unit 284 is used for determining the given frequency f after manual compensation*And an automatic torque compensation voltage generating a voltage for driving the motor.
As shown in FIG. 2, given frequency f*Compensation is performed by a manual compensation amount. The manual compensation amount is expressed in percentage by giving a given frequency f*Adding the compensation amount to obtain a manually compensated given frequency f*。
In addition, the manual compensation amount determines whether to use the forward manual compensation amount or the reverse manual compensation amount according to the torque direction to be compensated. The two compensation quantities are manually input and modified according to the debugging effect, and are used for occasions needing larger compensation quantities. For example, increasing the amount of manual compensation on a load application requiring power generation and starting torque (such as lifting a motor load) may ensure sufficient initial starting torque.
The current sampling unit 12, the low-pass filtering unit 14 and the complementary voltage generating unit 16 in the frequency converter torque boosting system 20 shown in fig. 2 are the same as the frequency converter torque boosting system 10 shown in fig. 1, and are not described again here.
Fig. 3 is a block diagram of a frequency converter shown in accordance with an exemplary embodiment.
Referring to fig. 3, the inverter 30 may further include a coordinate transformation unit 32, an Automatic Voltage Regulator (AVR) 34, a PWM input Voltage command unit 36, and a PWM (pulse width modulation) unit 38 connected to the motor 1, in addition to the inverter torque boosting system 10 described above.
The coordinate transformation unit 32, the automatic voltage regulator 34, the PWM input voltage command unit 36 and the PWM unit 38 are all the prior art, and are not described herein again to avoid obscuring the present invention.
It should be noted that the frequency converter 30 shown in fig. 3 is exemplified by the torque boost system 10, and may also include the torque boost system 20, that is, when manual compensation is needed, the manual compensation amount is increased so as to ensure sufficient initial starting torque.
According to the frequency converter provided by the embodiment of the invention, by adopting the torque lifting system 10, a better torque lifting effect can be obtained.
It is noted that the block diagrams shown in the above figures are functional entities and do not necessarily correspond to physically or logically separate entities. These functional entities may be implemented in the form of software, or in one or more hardware modules or integrated circuits, or in different networks and/or processor devices and/or microcontroller devices.
The following are embodiments of the method of the present invention, which may be applied to the above-described embodiments of the system of the present invention. For details which are not disclosed in the method according to the embodiment of the invention, reference is made to the system embodiment of the invention.
FIG. 4 is a flow chart illustrating a method of frequency converter torque boost according to an example embodiment. The inverter torque boosting method 40 shown in fig. 4 may be applied to the inverter torque boosting system 10 or 20 described above.
Referring to fig. 4, an inverter torque boost method 40 includes:
in step S42, a three-phase current of the motor electrically connected to the inverter is sampled and converted into two-phase d-axis and q-axis currents.
In step S44, the automatic torque compensation filter gain is received, and the q-axis current is low-frequency filtered according to the automatic torque compensation filter gain to obtain a filtered q-axis current.
In step S46, the nominal slip, the motor capacity of the electric motor, the automatic torque compensation voltage gain, the related parameters of the electric motor, and the filtered q-axis current are received, and the automatic torque compensation voltage of the frequency converter is determined according to the nominal slip, the motor capacity of the electric motor, the automatic torque compensation voltage gain, the related parameters of the electric motor, and the filtered q-axis current.
In some embodiments, determining the automatic torque compensation voltage of the frequency converter based on the nominal slip, the motor capacity of the electric machine, the automatic torque compensation voltage gain, the related parameters of the electric machine, and the filtered q-axis current comprises: the automatic torque compensation voltage is determined according to the following equation:
Vcomp＝fSlip*VMax*VGainAtb/fbase*Iq/Irated
fSlip＝s*fout
s＝N/(60*fbase/p)
N＝(60*fbase/p)–n
VMax＝(1<<12)*2/1.732*Vmotor/Vinv
wherein, VcompFor automatic torque compensation of voltage, fSlipIs slip frequency, s is slip ratio, foutIs a frequency converterN is the nominal slip, fbaseIs the fundamental frequency of the motor, p is the number of pole pairs of the motor, n is the rated rotation speed of the motor, VMaxIs the maximum output voltage, V, of the frequency convertermotorIs the rated voltage of the motor, VinvIs rated voltage, V, of the frequency converterGainAtbCompensating the voltage gain for automatic torque, IqIs the filtered q-axis current, IratedThe rated current of the electric machine is related to the motor capacity of the electric machine.
In some embodiments, the automatic torque compensation voltage gain comprises: the electric state torque compensation voltage gain and the generating state torque compensation voltage gain; the electric state torque compensation voltage gain is used as an automatic torque compensation voltage gain when the motor is in an electric state, and the automatic torque compensation voltage is calculated; the generation state torque compensation voltage gain is used as an automatic torque compensation voltage gain when the motor is in a generation state, and an automatic torque compensation voltage is calculated.
In some embodiments, the method 40 may further include: in step S48, a given frequency of the frequency converter is received; and generating a voltage for driving the motor according to the given frequency and the automatic torque compensation voltage.
In some embodiments, receiving the given frequency of the frequency converter comprises: receiving the given frequency after manual compensation; and generating a voltage for driving the motor according to the given frequency and the automatic torque compensation voltage includes: and generating a voltage for driving the motor according to the given frequency after the manual compensation and the automatic torque compensation voltage.
Compared with the existing automatic torque hoisting system, the frequency converter torque hoisting method provided by the embodiment of the invention does not need to use motor parameters which cannot be accurately obtained, such as stator resistance, stator inductance and the like, and avoids the problem of inaccurate compensation voltage calculation result caused by inaccurate parameters. In addition, since the PI controller is not used, it is not necessary to adjust the PI gain according to the load variation, and a better driving effect can be obtained under the same load condition.
Furthermore, it should be noted that the above-mentioned figures are only schematic illustrations of the processes involved in the method according to exemplary embodiments of the invention, and are not intended to be limiting. It will be readily understood that the processes shown in the above figures are not intended to indicate or limit the chronological order of the processes. In addition, it is also readily understood that these processes may be performed synchronously or asynchronously, e.g., in multiple modules.
Fig. 5 is a comparison graph of waveforms after two torque boosting methods are adopted. Wherein (a) is an improved waveform of the conventional automatic torque compensation method, and (b) is an improved waveform of the torque compensation method provided by the embodiment of the present invention.
A 150% on-load start-up test was performed by loading the two frequency converters with the same load, respectively. As can be seen from the waveforms in the two figures, in a test of 150% loaded start, the torque compensation method provided by the embodiment of the invention can obtain larger start current and start torque in a low frequency range after start.
Exemplary embodiments of the present invention are specifically illustrated and described above. It is to be understood that the invention is not limited to the precise construction, arrangements, or instrumentalities described herein; on the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
Claims (11)
1. A frequency converter torque boost system, comprising:
the current sampling unit is used for sampling a three-phase current of a motor electrically connected with the frequency converter and converting the three-phase current into two-phase d-axis current and q-axis current;
the low-pass filtering unit is electrically connected with the current sampling unit and used for receiving an automatic torque compensation filtering gain and carrying out low-frequency filtering on the q-axis current input by the current sampling unit according to the automatic torque compensation filtering gain to obtain the filtered q-axis current; and
and the compensation voltage generating unit is electrically connected with the low-pass filtering unit and used for receiving the rated slip, the motor capacity of the motor, the automatic torque compensation voltage gain and the related parameters of the motor and determining the automatic torque compensation voltage of the frequency converter according to the rated slip, the motor capacity of the motor, the automatic torque compensation voltage gain, the related parameters of the motor and the filtered q-axis current input by the low-pass filtering unit.
2. The system of claim 1, wherein the compensation voltage generation unit comprises: a first subunit for determining the automatic torque compensation voltage according to the following equation:
Vcomp＝fSlip*VMax*VGainAtb/fbase*Iq_filter/Irated
fSlip＝s*fout
s＝N/(60*fbase/p)
N＝(60*fbase/p)–n
VMax＝(1<<12)*2/1.732*Vmotor/Vinv
wherein, VcompCompensating the voltage for said automatic torque, fSlipIs slip frequency, s is slip ratio, foutIs the actual output frequency of the frequency converter, N is the rated slip, fbaseIs the fundamental frequency of the motor, p is the number of pole pairs of the motor, n is the rated rotation speed of the motor, VMaxIs the maximum output voltage, V, of the frequency convertermotorIs the rated voltage, V, of the motorinvIs the rated voltage, V, of the frequency converterGainAtbCompensating the voltage gain for said automatic torque, Iq_filterIs the filtered q-axis current, IratedThe rated current of the electric machine is related to the motor capacity of the electric machine.
3. The system of claim 2, wherein the automatic torque compensation voltage gain comprises: the electric state torque compensation voltage gain and the generating state torque compensation voltage gain; the electric state torque compensation voltage gain is used as the automatic torque compensation voltage gain when the motor is in an electric state, and the automatic torque compensation voltage is calculated; and the generating state torque compensation voltage gain is used as the automatic torque compensation voltage gain when the motor is in a generating state, and the automatic torque compensation voltage is calculated.
4. The system of any one of claims 1-3, further comprising: and the voltage instruction generating unit is electrically connected with the compensation voltage generating unit and used for receiving the given frequency of the frequency converter and generating voltage for driving the motor according to the given frequency of the frequency converter and the automatic torque compensation voltage input by the compensation voltage generating unit.
5. The system according to claim 4, wherein the voltage command generation unit includes: a second subunit and a third subunit, the second subunit being configured to receive the given frequency after being manually compensated; and the third subunit is used for generating a voltage for driving the motor according to the given frequency after manual compensation and the automatic torque compensation voltage.
6. A method for increasing torque of a frequency converter is characterized by comprising the following steps:
sampling three-phase current of a motor electrically connected with a frequency converter, and converting the three-phase current into two-phase d-axis current and q-axis current;
receiving an automatic torque compensation filter gain, and performing low-frequency filtering on the q-axis current according to the automatic torque compensation filter gain to obtain a filtered q-axis current; and
receiving a rated slip, a motor capacity of the motor, an automatic torque compensation voltage gain, a relevant parameter of the motor, and the filtered q-axis current, and determining an automatic torque compensation voltage of the frequency converter according to the rated slip, the motor capacity of the motor, the automatic torque compensation voltage gain, the relevant parameter of the motor, and the filtered q-axis current.
7. The method of claim 6, wherein determining the automatic torque compensation voltage of the frequency converter based on the nominal slip, the motor capacity of the electric machine, the automatic torque compensation voltage gain, the related parameters of the electric machine, and the filtered q-axis current comprises: determining the automatic torque compensation voltage according to the following equation:
Vcomp＝fSlip*VMax*VGainAtb/fbase*Iq/Irated
fSlip＝s*fout
s＝N/(60*fbase/p)
N＝(60*fbase/p)–n
VMax＝(1<<12)*2/1.732*Vmotor/Vinv
wherein, VcompCompensating the voltage for said automatic torque, fSlipIs slip frequency, s is slip ratio, foutIs the actual output frequency of the frequency converter, N is the rated slip, fbaseIs the fundamental frequency of the motor, p is the number of pole pairs of the motor, n is the rated rotation speed of the motor, VMaxIs the maximum output voltage, V, of the frequency convertermotorIs the rated voltage, V, of the motorinvIs the rated voltage, V, of the frequency converterGainAtbCompensating the voltage gain for said automatic torque, IqIs the filtered q-axis current, IratedThe rated current of the electric machine is related to the motor capacity of the electric machine.
8. The method of claim 7, wherein the automatic torque compensation voltage gain comprises: the electric state torque compensation voltage gain and the generating state torque compensation voltage gain; the electric state torque compensation voltage gain is used as the automatic torque compensation voltage gain when the motor is in an electric state, and the automatic torque compensation voltage is calculated; and the generating state torque compensation voltage gain is used as the automatic torque compensation voltage gain when the motor is in a generating state, and the automatic torque compensation voltage is calculated.
9. The method according to any one of claims 6-8, further comprising:
receiving a given frequency of the frequency converter; and
and generating a voltage for driving the motor according to the given frequency and the automatic torque compensation voltage.
10. The method of claim 9, wherein receiving the given frequency of the frequency converter comprises: receiving the given frequency after manual compensation; and generating a voltage for driving the motor according to the given frequency and the automatic torque compensation voltage comprises: and generating a voltage for driving the motor according to the given frequency after the manual compensation and the automatic torque compensation voltage.
11. Frequency converter, characterized in that it comprises a frequency converter torque boosting system according to any one of claims 1-5.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113659909A (en) * | 2021-08-23 | 2021-11-16 | 哈尔滨工业大学 | Method and device for suppressing torque/rotation speed pulsation and motor control system |
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| US20030020432A1 (en) * | 2001-07-24 | 2003-01-30 | Keijiro Sakai | Inverter apparatus |
| CN105591591A (en) * | 2014-11-12 | 2016-05-18 | Ls产电株式会社 | Apparatus for controlling inverter |
| CN105978438A (en) * | 2015-03-10 | 2016-09-28 | Ls产电株式会社 | Inverter for supplying load-adaptive boost voltage |
| CN110112941A (en) * | 2018-02-01 | 2019-08-09 | Ls产电株式会社 | Inverter |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20030020432A1 (en) * | 2001-07-24 | 2003-01-30 | Keijiro Sakai | Inverter apparatus |
| CN105591591A (en) * | 2014-11-12 | 2016-05-18 | Ls产电株式会社 | Apparatus for controlling inverter |
| CN105978438A (en) * | 2015-03-10 | 2016-09-28 | Ls产电株式会社 | Inverter for supplying load-adaptive boost voltage |
| CN110112941A (en) * | 2018-02-01 | 2019-08-09 | Ls产电株式会社 | Inverter |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113659909A (en) * | 2021-08-23 | 2021-11-16 | 哈尔滨工业大学 | Method and device for suppressing torque/rotation speed pulsation and motor control system |
| CN113659909B (en) * | 2021-08-23 | 2023-11-07 | 哈尔滨工业大学 | Method and device for suppressing torque/rotation speed pulsation and motor control system |
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