CN113872483A - Three-phase current reconstruction method, device, equipment and storage medium - Google Patents
Three-phase current reconstruction method, device, equipment and storage medium Download PDFInfo
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- CN113872483A CN113872483A CN202111134102.9A CN202111134102A CN113872483A CN 113872483 A CN113872483 A CN 113872483A CN 202111134102 A CN202111134102 A CN 202111134102A CN 113872483 A CN113872483 A CN 113872483A
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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
- H02P21/22—Current control, e.g. using a current control loop
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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
- H02P21/13—Observer control, e.g. using Luenberger observers or Kalman filters
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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
- H02P27/12—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 pulsing by guiding the flux vector, current vector or voltage vector on a circle or a closed curve, e.g. for direct torque control
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Abstract
The application discloses a three-phase current reconstruction method, a three-phase current reconstruction device, three-phase current reconstruction equipment and a storage medium. The method comprises the following steps: calculating the three-phase duty ratio of the current PWM period based on the three-phase current value of the previous PWM period; determining that the current PWM cycle enters an unobservable region based on the three-phase duty ratio; reconstructing a three-phase current value of the current PWM period based on a bus current value acquired in an unobservable area by the current PWM period and the electric angle of the motor rotor of the current PWM period; the unobservable region is a bus current value corresponding to only one nonzero voltage vector in the current PWM period. When the space vector falls in the unobservable region, three-phase current reconstruction can be realized based on the sampling value of the bus current, particularly in the overmodulation region, three-phase current reconstruction can be realized on the basis of meeting the effective voltage vector, and then the output torque of the motor can be increased under the condition that the bus voltage is not changed, and the utilization rate of the power supply voltage is improved.
Description
Technical Field
The present application relates to the field of motor control technologies, and in particular, to a three-phase current reconstruction method, apparatus, device, and storage medium.
Background
With the active popularization of energy-saving and consumption-reducing technologies, the energy-saving technology of motor control is increasingly paid attention. For example, a variable frequency air conditioner employs a Permanent Magnet Synchronous Motor (PMSM) having low loss and high efficiency.
When the frequency converter drives the permanent magnet synchronous motor, the three-phase bridge inverter of the frequency converter can be controlled in a Space Vector Pulse Width Modulation (SVPWM) mode. SVPWM is derived from the idea of AC motor stator flux linkage tracking, is easy to realize by a digital controller, and has the advantages of good output current waveform, high voltage utilization rate of a DC link and the like.
In traditional SVPWM control system, because need measure the alternating current signal of three-phase as the feedback, realize the closed-loop control of electric current, the interchange side of converter need set up three current sensor promptly, leads to with high costs, the structure is complicated and bulky, is unfavorable for integrating. The single current sensor is adopted to complete the reconstruction of the three-phase current, which becomes a research hotspot.
In practical applications, in order to increase the output voltage of the three-phase bridge inverter to increase the maximum output torque of the motor in motor control, an overmodulation technique is often required. However, since the space vector falls in an unobservable region when the overmodulation phenomenon occurs, the related method for completing the three-phase current reconstruction based on the single current sensor is difficult to realize.
Disclosure of Invention
In view of this, embodiments of the present application provide a three-phase current reconstruction method, apparatus, device, and storage medium, which aim to satisfy the three-phase current reconstruction under the single current sensor acquisition condition of SVPWM control.
The technical scheme of the embodiment of the application is realized as follows:
in a first aspect, an embodiment of the present application provides a three-phase current reconstruction method, including:
calculating a three-phase duty ratio of a current Pulse Width Modulation (PWM) period based on a three-phase current value of a previous PWM period;
determining that the current PWM cycle enters an unobservable zone based on the three-phase duty cycle;
reconstructing a three-phase current value of the current PWM period based on a bus current value acquired in the unobservable region in the current PWM period and an electrical angle of a motor rotor in the current PWM period;
the unobservable region is a bus current value corresponding to only one nonzero voltage vector in the current PWM period.
In some embodiments, before reconstructing the three-phase current values for the current PWM cycle based on the bus current values collected for the current PWM cycle in the non-observable region and the electrical angle of the motor rotor for the current PWM cycle, the method further comprises:
determining that the motor is in a constant torque control mode;
and determining the electric angle of the motor rotor in the current PWM period based on the electric angle of the motor rotor in the previous PWM period, the duration of the PWM period and the electric angular speed of the motor rotor in the previous PWM period.
In some embodiments, reconstructing the three-phase current values for the current PWM cycle based on the bus current values collected in the unobservable region for the current PWM cycle and the electrical angle of the motor rotor for the current PWM cycle includes:
determining a current vector magnitude of the current PWM cycle based on the bus current value and an electrical angle of a motor rotor of the current PWM cycle;
and determining phase current values of the other two phases except the bus current value based on the current vector amplitude of the current PWM period and the electric angle of the motor rotor of the current PWM period.
In some embodiments, the determining that the current PWM period enters an unobservable region based on the three-phase duty cycles comprises:
determining the high level time length of each phase circuit based on the three-phase duty ratio and the time length of the PWM period;
and determining that the current PWM period enters an unobservable region based on the high level time length of each phase line, the time length of the PWM period and the minimum sampling time length of the bus current.
In some embodiments, the determining that the current PWM cycle enters an unobservable region based on the high level duration of the respective phase line, the duration of the PWM cycle, and the minimum sampling duration of the bus current comprises one of:
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is less than the minimum sampling duration and the difference between the duration of the PWM period and the high level duration of the intermediate phase is less than the minimum sampling duration;
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is greater than or equal to the minimum sampling duration and the high level duration of the intermediate phase and the high level duration of the minimum phase are both less than the minimum sampling duration;
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is less than the minimum sampling duration and the difference between the duration of the PWM period and the high level duration of the intermediate phase is greater than or equal to the minimum sampling duration;
the maximum phase is the phase with the largest duty ratio in the three-phase line, the minimum phase is the phase with the smallest duty ratio in the three-phase line, and the intermediate phase is the phase with the middle duty ratio in the three-phase line.
In a second aspect, an embodiment of the present application provides a three-phase current reconstruction apparatus, including:
the duty ratio calculation module is used for calculating the three-phase duty ratio of the current PWM period based on the three-phase current value of the previous PWM period;
a determining module for determining that the current PWM cycle enters an unobservable region based on the three-phase duty cycle;
the current reconstruction module is used for reconstructing a three-phase current value of the current PWM period based on a bus current value acquired in the unobservable region in the current PWM period and an electrical angle of a motor rotor in the current PWM period;
the unobservable region is a bus current value corresponding to only one nonzero voltage vector in the current PWM period.
In some embodiments, the determining module is further configured to:
determining that the motor is in a constant torque control mode;
and determining the electric angle of the motor rotor in the current PWM period based on the electric angle of the motor rotor in the previous PWM period, the duration of the PWM period and the electric angular speed of the motor rotor in the previous PWM period.
In some embodiments, the current reconstruction module is specifically configured to:
determining a current vector magnitude of the current PWM cycle based on the bus current value and an electrical angle of a motor rotor of the current PWM cycle;
and determining phase current values of the other two phases except the bus current value based on the current vector amplitude of the current PWM period and the electric angle of the motor rotor of the current PWM period.
In some embodiments, the determining module is specifically configured to:
determining the high level time length of each phase circuit based on the three-phase duty ratio and the time length of the PWM period;
and determining that the current PWM period enters an unobservable region based on the high level time length of each phase line, the time length of the PWM period and the minimum sampling time length of the bus current.
In some embodiments, the determining module determines that the current PWM cycle enters an unobservable region based on a high level duration of each phase line, a duration of the PWM cycle, and a minimum sample duration of bus current, including one of:
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is less than the minimum sampling duration and the difference between the duration of the PWM period and the high level duration of the intermediate phase is less than the minimum sampling duration;
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is greater than or equal to the minimum sampling duration and the high level duration of the intermediate phase and the high level duration of the minimum phase are both less than the minimum sampling duration;
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is less than the minimum sampling duration and the difference between the duration of the PWM period and the high level duration of the intermediate phase is greater than or equal to the minimum sampling duration;
the maximum phase is the phase with the largest duty ratio in the three-phase line, the minimum phase is the phase with the smallest duty ratio in the three-phase line, and the intermediate phase is the phase with the middle duty ratio in the three-phase line.
In a third aspect, an embodiment of the present application provides a three-phase current reconstruction device, including: a processor and a memory for storing a computer program capable of running on the processor, wherein,
the processor is configured to execute the steps of the method according to the embodiment of the present application when running the computer program.
In some embodiments, the three-phase current reconstruction device further comprises: and the bus current acquisition device is used for acquiring a sampling value of the bus current and sending the sampling value to the processor.
In a fourth aspect, the present application provides a storage medium, where a computer program is stored, and when the computer program is executed by a processor, the steps of the method of the present application are implemented.
The technical scheme that this application embodiment provided, based on current PWM cycle is in the bus current value that can not observe the district collection with the electric angle of the electric motor rotor of current PWM cycle reconstructs the three-phase current value of current PWM cycle can realize that space vector falls in can not observe the district, realizes three-phase current reconstruction based on the sampling value of bus current, especially in the overmodulation district, can realize three-phase current reconstruction on the basis of satisfying the effective voltage vector, and then can increase the output torque of motor under the unchangeable situation of bus voltage, improve mains voltage utilization ratio.
Drawings
FIG. 1 is a schematic structural diagram of a system to which a three-phase current reconstruction method according to an embodiment of the present disclosure is applied;
FIG. 2 is a schematic diagram of the distribution of space voltage vectors;
FIG. 3 is a schematic diagram of an unobservable space voltage vector region in an embodiment of the present application;
FIG. 4 is a schematic diagram of a related art phase shift-based process;
FIG. 5 is a schematic flow chart of a three-phase current reconstruction method according to an embodiment of the present application;
FIG. 6 is a schematic diagram illustrating a relationship between carrier and modulation in motor control according to an embodiment of the present disclosure;
FIG. 7 is a schematic flow chart illustrating an exemplary three-phase current reconstruction method according to an application of the present application;
FIG. 8 is a schematic structural diagram of a three-phase current reconstruction device according to an embodiment of the present application;
fig. 9 is a schematic structural diagram of a three-phase current reconstruction device according to an embodiment of the present application.
Detailed Description
The present application will be described in further detail with reference to the following drawings and examples.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
Before describing the three-phase current reconstruction method in the embodiment of the present application, a system to which the three-phase current reconstruction method is applied will be exemplarily described.
As shown in fig. 1, the system includes: the system comprises a motor M, a three-phase bridge inverter 101, a direct current power supply DC and a bus current collecting device 102.
Illustratively, a capacitor C1 is also connected between the positive pole and the negative pole of the direct current power supply DC. The DC power supplied by the DC power source DC is converted to three-phase power for the motor M, which may be a PMSM, by a three-phase bridge inverter 101. The three-phase bridge inverter 101 may be controlled by a frequency converter in an SVPWM manner. The bus current collection device 102 may adopt a typical single-resistor sampling circuit, for example, the bus current collection device includes a resistor R1 connected between a negative electrode of the DC power supply DC and the three-phase bridge inverter 101, a voltage at two ends of the resistor R1 is transmitted to the AD conversion circuit through the operational amplifier, the AD conversion circuit converts the voltage into a bus current, the bus current is used for subsequent three-phase current reconstruction, and the reconstructed three-phase ac current is used as a feedback to realize closed-loop control of the current.
It can be understood that the three-phase bridge inverter is controlled by adopting an SVPWM (space vector pulse width modulation) modulation mode, and has 8 switch working states comprising 6 non-zero voltage vectors (V)1-V6) And 2 zero voltage vectors (V)0And V7) Which divides the voltage space plane into hexagons as shown in fig. 2. The basic principle of phase current reconstruction is to obtain each phase current by using the bus current sampled at different times in 1 PWM period. The relationship between the current of the dc bus and the three-phase current is determined by the state of the instantaneous switching value, and the relationship is shown in table 1.
TABLE 1
| Voltage vector | Phase current | Voltage vector | Phase current |
| V1 | Ic | V5 | -Ib |
| V2 | Ib | V6 | -Ic |
| V3 | -Ia | V0 | 0 |
| V4 | Ia | V7 | 0 |
In practical applications, the sampling window is satisfied in consideration of the sampling of the bus current, that is, the non-zero voltage vector is required to last for 1 minimum sampling time Tmin，Tmin＝Td+Tset+TADWherein, TdIndicating the dead time duration, T, of the upper and lower legssetIndicating the bus current settling time, TADIndicating the sample transition duration.
As shown in fig. 3, when the output voltage vector is in the low modulation region or the non-zero voltageWhen the vector is nearby, the duration of possible non-zero voltage vector in 1 PWM period is less than TminThe case (1). This condition makes the sampled bus current meaningless. In the embodiment of the present application, a region where two phases of different phase currents (i.e., bus direct currents corresponding to two non-zero voltage vectors) cannot be sampled in one PWM period is collectively referred to as an unobservable region.
In the related art, in order to ensure that two-phase current can be sampled in each PWM period, it is necessary to ensure that two-phase current is sampled in one PWM period through phase shift processing in an unobservable region. For example, as shown in fig. 4, exemplarily, a three-phase line includes: the original sampling window of T1 is smaller than TminThe high level of the b phase is shifted to the right by T through phase shift processingshiftThe sampling window of phase-shifted T1 may be made equal to Tmin。
When the unobservable region is an overmodulation region, for example, a region outside an inscribed circle of a hexagon shown in fig. 3, a problem that phase shifting is shifted out of a PWM cycle so that an effective vector voltage cannot be satisfied occurs, however, if the PWM cycle of the vector voltage is ensured, a situation that a sampling window cannot be provided occurs so that a two-phase current cannot be acquired in one PWM cycle, and therefore, a related phase current reconstruction method based on phase shifting cannot satisfy a reconstruction requirement of a three-phase current of the overmodulation region.
Based on this, in various embodiments of the present application, a three-phase current reconstruction method capable of adapting to an overmodulation region is provided, so that three-phase current reconstruction can be achieved in the overmodulation region based on a bus current.
As shown in fig. 5, the three-phase current reconstruction method according to the embodiment of the present application includes:
Illustratively, the calculation process of the three-phase duty ratio is as follows:
1) obtaining three-phase current values ia, ib and ic of the previous PWM period, wherein ia is the phase current corresponding to the phase a line, ib is the phase current corresponding to the phase b line, and ic is the phase current corresponding to the phase c line;
2) determining the magnetic field angle theta and the speed omega of the motor rotor through a speed position estimation module;
3) obtaining id and iq by performing clark conversion and park conversion on the three-phase current values ia, ib and ic, wherein the clark conversion is used for converting an abc three-axis coordinate system into a stationary alpha-beta coordinate system, the park conversion is used for converting the stationary alpha-beta coordinate system into a rotating dq coordinate system, id is a converted d-axis current value, and iq is a converted q-axis current value;
4) converting a magnetic field angle theta and a speed omega of a motor rotor to obtain given current values of a d axis and a q axis, and obtaining Vd and Vq by PID (proportional integral derivative) operation based on the given current values and id and iq obtained in the step 3), wherein the Vd is a modulation voltage of the d axis, and the Vq is a modulation voltage of the q axis;
5) obtaining V alpha and V beta by carrying out inverse park conversion on the Vd and the Vq, wherein the V alpha is the modulation voltage of an alpha axis, and the V beta is the modulation voltage of a beta axis;
6) obtaining Va, Vb and Vc by SV vector operation on the V alpha and the V beta, wherein Va is the modulation voltage of an a axis, Vb is the modulation voltage of the a axis, and Vc is the modulation voltage of the a axis;
7) and calculating the three-phase duty ratio duty through the bus voltage and Va, Vb and Vca、dutyb、dutycWherein, dutyaDuty ratio of a phasebDuty ratio of b phasecIs the duty cycle of the c phase.
And 503, reconstructing a three-phase current value of the current PWM period based on the bus current value acquired in the unobservable region in the current PWM period and the electric angle of the motor rotor in the current PWM period.
Here, the unobservable region means that only a bus current value corresponding to a non-zero voltage vector can be acquired in a current PWM period, that is, two different phase currents cannot be sampled in one PWM period, so that reconstruction of a three-phase current in the current PWM period cannot be completed.
In the embodiment of the application, the three-phase current value of the current PWM cycle is reconstructed based on the bus current value acquired by the current PWM cycle in the unobservable region and the electric angle of the motor rotor of the current PWM cycle, so that the reconstruction of the three-phase current based on the sampling value of the bus current can be realized when the space vector falls in the unobservable region, and particularly in the overmodulation region, the reconstruction of the three-phase current can be realized on the basis of meeting the effective voltage vector, so that the output torque of the motor can be increased under the condition that the bus voltage is not changed, and the utilization rate of the power supply voltage is improved.
In some embodiments, before reconstructing the three-phase current values of the current PWM cycle based on the bus current values of the current PWM cycle collected in the unobservable region and the electrical angle of the motor rotor of the current PWM cycle, the method further comprises:
determining that the motor is in a constant torque control mode;
and determining the electric angle of the motor rotor in the current PWM period based on the electric angle of the motor rotor in the previous PWM period, the duration of the PWM period and the electric angular speed of the motor rotor in the previous PWM period.
It can be understood that when the motor runs to the unobservable region, the rotation speed of the motor rotor is higher than the rated rotation speed, if the motor is in the constant torque control mode, the running torque and rotation speed of the motor in two PWM periods can be considered to be unchanged, so that the electrical angle of the current PWM period can be calculated according to the electrical angular speed (also called electrical frequency) and the electrical angle of the motor rotor in the previous PWM period.
Here, the electrical angle of the rotor of the motor is related to the number of pole pairs of the motor, and if the motor is a pair of poles, the electrical angle of 360 ° is formed in one circle of the motor; the motor has two opposite poles, and the electric angle of the motor is 720 degrees in a circle; the motor is three pairs of poles, and the motor rotates for 1080 electrical degrees in a circle, and so on. Assuming that the pole pair number of the motor is P, the total electrical angle of the motor is 360 ° P. It is understood that the electrical angular velocity of the motor is the angular velocity P.
Illustratively, as shown in fig. 6, the formula for calculating the electrical angle of the current PWM period is as follows:
θ2＝θ1+(Ts*Fs)/2π
wherein θ 1 is the electrical angle of the previous PWM period, θ 2 is the electrical angle of the current PWM period, Ts is the duration of the PWM period, and Fs is the electrical angular velocity of the previous PWM period.
In this way, the electrical angle of the current PWM period can be calculated based on the principle that the motor rotation speed is assumed to be constant.
In some embodiments, reconstructing the three-phase current values of the current PWM cycle based on the bus current values of the current PWM cycle collected in the non-observable region and the electrical angle of the motor rotor of the current PWM cycle includes:
determining the current vector amplitude of the current PWM period based on the bus current value and the electric angle of the motor rotor of the current PWM period;
and determining phase current values of the other two phases except the bus current value based on the current vector amplitude of the current PWM period and the electric angle of the motor rotor of the current PWM period.
It is understood that in the unobservable region, the bus current value corresponding to a non-zero voltage vector can be acquired based on the bus current acquisition device 102, and the corresponding relationship between the bus current value and the phase current can be determined based on the relationship shown in table 1.
And then based on a calculation formula of three-phase current as shown below, the current vector magnitude of the current PWM period can be determined:
wherein, ImIs the magnitude of the current vector, IaIs a phase current value, IbIs a b-phase current value, IcThe c-phase current value and θ are electrical angles.
For example, assuming that the bus current value corresponds to the a-phase current value, it may be based on IaAnd theta is converted to obtain ImIs then based on ImAnd theta, calculated to obtain IbAnd IcThereby realizing the reconstruction of the three-phase current.
In some embodiments, determining that the current PWM period enters the unobservable region based on the three-phase duty cycles comprises:
determining the high level time length of each phase circuit based on the three-phase duty ratio and the time length of the PWM period;
and determining that the current PWM period enters the unobservable region based on the high level time length of each phase line, the time length of the PWM period and the minimum sampling time length of the bus current.
For example, assuming that Tp is the duration of the PWM period, the high level duration Ta of the a-phase is Tp × dutyaThe high level time length Tb of the b-phase is Tp durationbAnd the high level duration Tc of the c phase is Tp durationc。
Illustratively, determining that the current PWM cycle enters the non-observable region based on the high level duration of each phase line, the duration of the PWM cycle, and the minimum sampling duration of the bus current includes one of:
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is less than the minimum sampling duration and the difference between the duration of the PWM period and the high level duration of the intermediate phase is less than the minimum sampling duration;
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is greater than or equal to the minimum sampling duration, and the high level duration of the intermediate phase and the high level duration of the minimum phase are both less than the minimum sampling duration;
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is less than the minimum sampling duration and the difference between the duration of the PWM period and the high level duration of the intermediate phase is greater than or equal to the minimum sampling duration;
the maximum phase is the phase with the largest duty ratio in the three-phase line, the minimum phase is the phase with the smallest duty ratio in the three-phase line, and the intermediate phase is the phase with the middle duty ratio in the three-phase line.
It can be understood that when the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is less than the minimum sampling duration and the difference between the duration of the PWM period and the high level duration of the intermediate phase is less than the minimum sampling duration, both the two-phase duty ratios in the three-phase duty ratios are large; when the difference between the high level time of the maximum phase and the high level time of the intermediate phase is greater than or equal to the minimum sampling time and both the high level time of the intermediate phase and the high level time of the minimum phase are less than the minimum sampling time, the two-phase duty ratio in the three-phase duty ratio is small, and the two-phase current collection cannot be realized through phase shifting processing at this time. Based on the method of the embodiment of the application, a three-phase current value of the current PWM period can be reconstructed based on the collected bus current value (corresponding to a phase current value) and the electric angle of the motor rotor of the current PWM period instead of collecting two-phase current, so that the vector control of the motor is realized.
It can be understood that, when the difference between the high-level time of the maximum phase and the high-level time of the intermediate phase is less than the minimum sampling time and the difference between the time of the PWM period and the high-level time of the intermediate phase is greater than or equal to the minimum sampling time, the intermediate phase may be subjected to phase shift processing, so that two-phase currents are sampled in the PWM period to implement reconstruction of three-phase currents, and the reconstruction of three-phase currents may also be implemented based on the method of the embodiment of the present application, which is not limited in the embodiment of the present application.
The three-phase current reconstruction method according to the embodiment of the present application is described below with reference to an application example.
As shown in fig. 7, the three-phase current reconstruction method may include:
For example, the three-phase duty ratio of the current PWM period may be calculated based on the three-phase current value of the previous PWM period, which may specifically refer to the foregoing description and is not described herein again.
Here, the size of the sampling window, i.e. the minimum sampling duration T for which a non-zero voltage vector must lastmin，Tmin＝Td+Tset+TADWherein, TdIndicating the dead time duration, T, of the upper and lower legssetIndicating the bus current settling time, TADIndicating the sample transition duration.
Illustratively, the high level time length of each phase line may be determined based on the three-phase duty ratio and the time length of the PWM period; and then judging whether the current PWM period enters an unobservable region or not based on the high level time length of each phase line, the time length of the PWM period and the minimum sampling time length of the bus current.
And step 703, reconstructing normal three-phase current.
If the current PWM period is determined not to enter the unobservable region, the two-phase current can be normally collected, and therefore the three-phase current is obtained.
And 704, reconstructing a three-phase current value of the current PWM period based on the bus current value acquired in the unobservable region in the current PWM period and the electric angle of the motor rotor in the current PWM period.
If it is determined that the current PWM cycle enters the unobservable region, the three-phase current value of the current PWM cycle may be reconstructed based on the method of the embodiment of the present application, which may specifically refer to the foregoing description and is not described herein again.
The motor vector operation control may be performed based on the three-phase current value of the current PWM period, for example, the motor may be controlled based on the SVPWM method.
It can be understood that, in this application example, when the voltage vector is in the overmodulation region, the three-phase current value in the current PWM period can be reconstructed based on the electrical angle of the motor rotor in the current PWM period on the premise of only collecting one-phase current value, so that the requirement that the overmodulation region reconstructs three-phase current based on the bus current can be met, and further, the output torque of the motor can be increased under the condition that the bus voltage is not changed, and the utilization rate of the power supply voltage can be improved.
In order to implement the method of the embodiment of the present application, an embodiment of the present application further provides a three-phase current reconstruction device, where the three-phase current reconstruction device corresponds to the three-phase current reconstruction method, and each step in the three-phase current reconstruction method is also completely applicable to the embodiment of the three-phase current reconstruction device.
As shown in fig. 8, the three-phase current reconstruction apparatus includes: a duty cycle calculation module 801, a determination module 802 and a current reconstruction module 803.
The duty ratio calculation module 801 is configured to calculate a three-phase duty ratio of a current PWM period based on a three-phase current value of a previous PWM period;
the determining module 802 is configured to determine that the current PWM period enters an unobservable region based on the three-phase duty cycle;
the current reconstruction module 803 is configured to reconstruct a three-phase current value of the current PWM period based on a bus current value acquired in the unobservable region in the current PWM period and an electrical angle of the motor rotor of the current PWM period;
the unobservable region is a bus current value corresponding to only one nonzero voltage vector in the current PWM period.
In some embodiments, the determining module 802 is further configured to:
determining that the motor is in a constant torque control mode;
and determining the electric angle of the motor rotor in the current PWM period based on the electric angle of the motor rotor in the previous PWM period, the duration of the PWM period and the electric angular speed of the motor rotor in the previous PWM period.
In some embodiments, the current reconstruction module 803 is specifically configured to:
determining a current vector magnitude of the current PWM cycle based on the bus current value and an electrical angle of a motor rotor of the current PWM cycle;
and determining phase current values of the other two phases except the bus current value based on the current vector amplitude of the current PWM period and the electric angle of the motor rotor of the current PWM period.
In some embodiments, the determining module 802 is specifically configured to:
determining the high level time length of each phase circuit based on the three-phase duty ratio and the time length of the PWM period;
and determining that the current PWM period enters an unobservable region based on the high level time length of each phase line, the time length of the PWM period and the minimum sampling time length of the bus current.
In some embodiments, the determining module 802 determines that the current PWM cycle enters an unobservable region based on the high level duration of the phase lines, the duration of the PWM cycle, and the minimum sampling duration of the bus current, including one of:
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is less than the minimum sampling duration and the difference between the duration of the PWM period and the high level duration of the intermediate phase is less than the minimum sampling duration;
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is greater than or equal to the minimum sampling duration and the high level duration of the intermediate phase and the high level duration of the minimum phase are both less than the minimum sampling duration;
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is less than the minimum sampling duration and the difference between the duration of the PWM period and the high level duration of the intermediate phase is greater than or equal to the minimum sampling duration;
the maximum phase is the phase with the largest duty ratio in the three-phase line, the minimum phase is the phase with the smallest duty ratio in the three-phase line, and the intermediate phase is the phase with the middle duty ratio in the three-phase line.
In practical applications, the duty ratio calculation module 801, the determination module 802, and the current reconstruction module 803 may be implemented by a processor of a three-phase current reconstruction device. Of course, the processor needs to run a computer program in memory to implement its functions.
It should be noted that: in the three-phase current reconstruction apparatus provided in the above embodiment, when performing three-phase current reconstruction, only the division of the program modules is illustrated, and in practical applications, the processing distribution may be completed by different program modules according to needs, that is, the internal structure of the apparatus may be divided into different program modules to complete all or part of the processing described above. In addition, the three-phase current reconstruction device and the three-phase current reconstruction method provided by the embodiments belong to the same concept, and specific implementation processes are detailed in the method embodiments and are not described herein again.
Based on the hardware implementation of the program module, and in order to implement the method of the embodiment of the present application, the embodiment of the present application further provides a three-phase current reconstruction device. Fig. 9 shows only an exemplary structure of the three-phase current reconstruction device, not the entire structure, and a part of or the entire structure shown in fig. 9 may be implemented as necessary.
As shown in fig. 9, a three-phase current reconstruction apparatus 900 provided in an embodiment of the present application includes: at least one processor 901, memory 902, and a user interface 903. The various components in the three-phase current reconstruction device 900 are coupled together by a bus system 904. It will be appreciated that the bus system 904 is used to enable communications among the components. The bus system 904 includes a power bus, a control bus, and a status signal bus in addition to a data bus. But for clarity of illustration the various buses are labeled as bus system 904 in figure 9.
Illustratively, the three-phase current reconstruction device 900 further includes: and the bus current acquisition device is used for acquiring a sampling value of the bus current and sending the sampling value to the processor 901. For example, the bus current collection device may be a single resistance sampling circuit as shown in fig. 1.
The user interface 903 may include a display, a keyboard, a mouse, a trackball, a click wheel, a key, a button, a touch pad, a touch screen, or the like, among others.
The memory 902 in the embodiment of the present application is used to store various types of data to support the operation of the three-phase current reconstruction device. Examples of such data include: any computer program for operating on a three-phase current reconstruction device.
The three-phase current reconstruction method disclosed by the embodiment of the application can be applied to the processor 901, or implemented by the processor 901. The processor 901 may be an integrated circuit chip having signal processing capabilities. In the implementation process, the steps of the three-phase current reconstruction method may be implemented by an integrated logic circuit of hardware or an instruction in the form of software in the processor 901. The Processor 901 may be a general purpose Processor, a Digital Signal Processor (DSP), or other programmable logic device, discrete gate or transistor logic device, discrete hardware components, or the like. The processor 901 may implement or perform the methods, steps and logic blocks disclosed in the embodiments of the present application. A general purpose processor may be a microprocessor or any conventional processor or the like. The steps of the method disclosed in the embodiments of the present application may be directly implemented by a hardware decoding processor, or implemented by a combination of hardware and software modules in the decoding processor. The software module may be located in a storage medium located in the memory 902, and the processor 901 reads information in the memory 902, and completes the steps of the three-phase current reconstruction method provided in the embodiment of the present application in combination with hardware thereof.
In an exemplary embodiment, the three-phase current reconstruction Device may be implemented by one or more Application Specific Integrated Circuits (ASICs), DSPs, Programmable Logic Devices (PLDs), Complex Programmable Logic Devices (CPLDs), Field Programmable Gate Arrays (FPGAs), general purpose processors, controllers, Micro Controllers (MCUs), microprocessors (microprocessors), or other electronic components for performing the aforementioned methods.
It will be appreciated that the memory 902 can be either volatile memory or nonvolatile memory, and can include both volatile and nonvolatile memory. Among them, the nonvolatile Memory may be a Read Only Memory (ROM), a Programmable Read Only Memory (PROM), an Erasable Programmable Read-Only Memory (EPROM), an Electrically Erasable Programmable Read-Only Memory (EEPROM), a magnetic random access Memory (FRAM), a Flash Memory (Flash Memory), a magnetic surface Memory, an optical disk, or a Compact Disc Read-Only Memory (CD-ROM); the magnetic surface storage may be disk storage or tape storage. Volatile Memory can be Random Access Memory (RAM), which acts as external cache Memory. By way of illustration and not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), Synchronous Static Random Access Memory (SSRAM), Dynamic Random Access Memory (DRAM), Synchronous Dynamic Random Access Memory (SDRAM), Double Data Rate Synchronous Dynamic Random Access Memory (DDRSDRAM), Enhanced Synchronous Dynamic Random Access Memory (ESDRAM), Enhanced Synchronous Dynamic Random Access Memory (Enhanced DRAM), Synchronous Dynamic Random Access Memory (SLDRAM), Direct Memory (DRmb Access), and Random Access Memory (DRAM). The memories described in the embodiments of the present application are intended to comprise, without being limited to, these and any other suitable types of memory.
In an exemplary embodiment, the present application further provides a storage medium, that is, a computer storage medium, which may be specifically a computer readable storage medium, for example, a memory 902 storing a computer program, where the computer program is executable by a processor 901 of a three-phase current reconstruction device to perform the steps described in the method of the present application. The computer readable storage medium may be a ROM, PROM, EPROM, EEPROM, Flash Memory, magnetic surface Memory, optical disk, or CD-ROM, among others.
It should be noted that: "first," "second," and the like are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.
The technical means described in the embodiments of the present application may be arbitrarily combined without conflict.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (13)
1. A three-phase current reconstruction method, comprising:
calculating the three-phase duty ratio of the current PWM period based on the three-phase current value of the previous PWM period;
determining that the current PWM cycle enters an unobservable zone based on the three-phase duty cycle;
reconstructing a three-phase current value of the current PWM period based on a bus current value acquired in the unobservable region in the current PWM period and an electrical angle of a motor rotor in the current PWM period;
the unobservable region is a bus current value corresponding to only one nonzero voltage vector in the current PWM period.
2. The method of claim 1, wherein prior to reconstructing the three-phase current values for the current PWM cycle based on the bus current values collected for the present PWM cycle in the non-observable region and the electrical angle of the motor rotor for the present PWM cycle, the method further comprises:
determining that the motor is in a constant torque control mode;
and determining the electric angle of the motor rotor in the current PWM period based on the electric angle of the motor rotor in the previous PWM period, the duration of the PWM period and the electric angular speed of the motor rotor in the previous PWM period.
3. The method of claim 1, wherein reconstructing the three-phase current values for the current PWM cycle based on the bus current values collected in the unobservable zone for the current PWM cycle and the electrical angle of the motor rotor for the current PWM cycle comprises:
determining a current vector magnitude of the current PWM cycle based on the bus current value and an electrical angle of a motor rotor of the current PWM cycle;
and determining phase current values of the other two phases except the bus current value based on the current vector amplitude of the current PWM period and the electric angle of the motor rotor of the current PWM period.
4. The method of claim 1, wherein the determining that the current PWM cycle enters an unobservable region based on the three-phase duty cycles comprises:
determining the high level time length of each phase circuit based on the three-phase duty ratio and the time length of the PWM period;
and determining that the current PWM period enters an unobservable region based on the high level time length of each phase line, the time length of the PWM period and the minimum sampling time length of the bus current.
5. The method of claim 4, wherein determining that the current PWM cycle enters an unobservable region based on the high level duration of each phase line, the duration of the PWM cycle, and the minimum sampling duration of the bus current comprises one of:
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is less than the minimum sampling duration and the difference between the duration of the PWM period and the high level duration of the intermediate phase is less than the minimum sampling duration;
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is greater than or equal to the minimum sampling duration and the high level duration of the intermediate phase and the high level duration of the minimum phase are both less than the minimum sampling duration;
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is less than the minimum sampling duration and the difference between the duration of the PWM period and the high level duration of the intermediate phase is greater than or equal to the minimum sampling duration;
the maximum phase is the phase with the largest duty ratio in the three-phase line, the minimum phase is the phase with the smallest duty ratio in the three-phase line, and the intermediate phase is the phase with the middle duty ratio in the three-phase line.
6. A three-phase current reconstruction device, comprising:
the duty ratio calculation module is used for calculating the three-phase duty ratio of the current PWM period based on the three-phase current value of the previous PWM period;
a determining module for determining that the current PWM cycle enters an unobservable region based on the three-phase duty cycle;
the current reconstruction module is used for reconstructing a three-phase current value of the current PWM period based on a bus current value acquired in the unobservable region in the current PWM period and an electrical angle of a motor rotor in the current PWM period;
the unobservable region is a bus current value corresponding to only one nonzero voltage vector in the current PWM period.
7. The three-phase current reconstruction device of claim 6, wherein the determination module is further configured to:
determining that the motor is in a constant torque control mode;
and determining the electric angle of the motor rotor in the current PWM period based on the electric angle of the motor rotor in the previous PWM period, the duration of the PWM period and the electric angular speed of the motor rotor in the previous PWM period.
8. The three-phase current reconstruction device according to claim 6, wherein the current reconstruction module is specifically configured to:
determining a current vector magnitude of the current PWM cycle based on the bus current value and an electrical angle of a motor rotor of the current PWM cycle;
and determining phase current values of the other two phases except the bus current value based on the current vector amplitude of the current PWM period and the electric angle of the motor rotor of the current PWM period.
9. The three-phase current reconstruction apparatus according to claim 6, wherein the determination module is specifically configured to:
determining the high level time length of each phase circuit based on the three-phase duty ratio and the time length of the PWM period;
and determining that the current PWM period enters an unobservable region based on the high level time length of each phase line, the time length of the PWM period and the minimum sampling time length of the bus current.
10. The three-phase current reconstruction device of claim 9, wherein the determination module determines that the current PWM cycle enters an unobservable region based on a high level duration of each phase line, a duration of the PWM cycle, and a minimum sampling duration of a bus current, comprising one of:
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is less than the minimum sampling duration and the difference between the duration of the PWM period and the high level duration of the intermediate phase is less than the minimum sampling duration;
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is greater than or equal to the minimum sampling duration and the high level duration of the intermediate phase and the high level duration of the minimum phase are both less than the minimum sampling duration;
determining that the difference between the high level duration of the maximum phase and the high level duration of the intermediate phase is less than the minimum sampling duration and the difference between the duration of the PWM period and the high level duration of the intermediate phase is greater than or equal to the minimum sampling duration;
the maximum phase is the phase with the largest duty ratio in the three-phase line, the minimum phase is the phase with the smallest duty ratio in the three-phase line, and the intermediate phase is the phase with the middle duty ratio in the three-phase line.
11. A three-phase current reconstruction device, comprising: a processor and a memory for storing a computer program capable of running on the processor, wherein,
the processor, when executing the computer program, is adapted to perform the steps of the method of any of claims 1 to 5.
12. The three-phase current reconstruction device of claim 11, further comprising:
and the bus current acquisition device is used for acquiring a sampling value of the bus current and sending the sampling value to the processor.
13. A storage medium having a computer program stored thereon, the computer program, when executed by a processor, implementing the steps of the method of any one of claims 1 to 5.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115313940A (en) * | 2022-08-19 | 2022-11-08 | 南通帝孚工具科技有限公司 | Current estimator for servo motor |
| CN117478012A (en) * | 2023-12-18 | 2024-01-30 | 北京立迈胜控制技术有限责任公司 | Current sampling method for vector control of stepping motor |
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2021
- 2021-09-27 CN CN202111134102.9A patent/CN113872483A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115313940A (en) * | 2022-08-19 | 2022-11-08 | 南通帝孚工具科技有限公司 | Current estimator for servo motor |
| CN115313940B (en) * | 2022-08-19 | 2023-12-19 | 重庆海控科技合伙企业(有限合伙) | Current estimator for servo motor |
| CN117478012A (en) * | 2023-12-18 | 2024-01-30 | 北京立迈胜控制技术有限责任公司 | Current sampling method for vector control of stepping motor |
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