WO2023045555A1 - Three-phase current reconstruction method and apparatus, device and storage medium - Google Patents

Abstract

The present application provides a three-phase current reconstruction method and apparatus, a device and a storage medium. The method comprises: calculating a three-phase duty cycle of a current PWM cycle on the basis of a three-phase current value of a previous PWM cycle; on the basis of the three-phase duty cycle, determining that the current PWM cycle enters an unobservable region; on the basis of the mechanical angle of a motor rotor of the current PWM cycle, the rotation angular velocity and the peak value of a current vector amplitude before entering the unobservable region, determining a current vector amplitude of the current PWM cycle; and on the basis of the current vector amplitude of the current PWM cycle and the electrical angle of the motor rotor, reconstructing a three-phase current value of the current PWM cycle.

Description

Three-phase current reconstruction method, device, equipment and storage medium

Cross References to Related Applications

This application is based on a Chinese patent application with application number 202111134223.3 and a filing date of September 27, 2021, and claims the priority of this Chinese patent application. The entire content of this Chinese patent application is hereby incorporated by reference into this application.

technical field

The present application relates to the technical field of motor control, and in particular to a three-phase current reconstruction method, device, equipment and storage medium.

Background technique

With the active promotion of energy-saving technology, the energy-saving technology of motor control has been paid more and more attention. For example, an inverter air conditioner uses a permanent magnet synchronous motor (Permanent Magnetic Synchronous Machine, PMSM) with 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 by SVPWM (Space Vector Pulse Width Modulation, Space Vector Pulse Width Modulation). SVPWM originates from the idea of AC motor stator flux linkage tracking, which is easy to realize by digital controller, and has the advantages of good output current waveform and high DC link voltage utilization rate.

In the traditional SVPWM control system, since it is necessary to measure the three-phase AC signal as feedback to realize the closed-loop control of the current, that is, three current sensors need to be installed on the AC side of the inverter, resulting in high cost, complex structure and large volume, which is not conducive to Integrated. Using a single current sensor to complete the reconstruction of three-phase current has become 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, it is often necessary to use overmodulation technology. However, because the space vector falls in the unobservable region when the overmodulation phenomenon occurs, it is difficult to realize the related method of three-phase current reconstruction based on a single current sensor.

Contents of the invention

In view of this, the embodiments of the present application provide a three-phase current reconstruction method, device, device and storage medium, aiming at satisfying the three-phase current reconstruction under SVPWM control in the case of single current sensor acquisition.

The technical scheme of the embodiment of the application is realized in this way:

In the first aspect, the embodiment of the present application provides a three-phase current reconstruction method, including:

Calculate the three-phase duty cycle of the current PWM cycle based on the three-phase current value of the previous Pulse Width Modulation (PWM) cycle;

determining that the current PWM cycle enters an unobservable region based on the three-phase duty ratio;

Determine the current vector amplitude of the current PWM cycle based on the mechanical angle of the motor rotor of the current PWM cycle, the rotational angular velocity, and the peak value of the current vector amplitude before entering the unobservable region;

Reconstructing the three-phase current values of the current PWM cycle based on the current vector magnitude of the current PWM cycle and the electrical angle of the motor rotor;

Wherein, the unobservable area refers to that bus current values corresponding to two non-zero voltage vectors cannot be collected in the current PWM period.

In some implementations, before the current vector amplitude of the current PWM cycle is determined based on the mechanical angle of the motor rotor, the rotational angular velocity, and the peak value of the current vector amplitude before entering the unobservable region, the The method also includes:

Record the peak value of the current vector magnitude;

Determine the electrical angle of the motor rotor in the current PWM cycle based on the electrical angle of the motor rotor in the previous PWM cycle, the electrical angular velocity, and the duration of the PWM cycle;

determining the mechanical angle of the motor rotor in the current PWM cycle based on the electrical angle of the motor rotor in the current PWM cycle;

The rotational angular velocity of the motor rotor in the current PWM period is determined based on the electrical angular velocity of the motor rotor in the last PWM period.

In some implementations, the current vector amplitude of the current PWM cycle is determined based on the mechanical angle of the motor rotor of the current PWM cycle, the rotational angular velocity, and the peak value of the current vector amplitude before entering the unobservable region, using the following formula:

Im=Imax*sin(ωt+θm);

Wherein, Im is the current vector amplitude of the current PWM cycle, Imax is the peak value of the current vector amplitude, ω is the rotational angular velocity, t is the duration of the PWM cycle, and θm is the mechanical angle of the motor rotor of the current PWM cycle .

In some implementations, the determining that the current PWM cycle enters an unobservable region based on the three-phase duty cycle includes:

determining the high-level duration of each phase line based on the three-phase duty cycle and the duration of the PWM cycle;

It is determined 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.

In some implementations, the determination that the current PWM cycle enters the 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 includes one of the following:

determining that the difference between the high-level duration of the largest 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 cycle and the high-level duration of the intermediate phase is less than the minimum sampling duration;

Determine that the difference between the high-level duration of the largest 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 duration;

Determine that the difference between the high-level duration of the largest 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 cycle and the high-level duration of the intermediate phase is greater than or equal to the minimum sampling duration;

Wherein, 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 cycle in the three-phase line, and the intermediate phase is the phase with the duty cycle in the three-phase line. middle phase.

In the second aspect, the embodiment of the present application provides a three-phase current reconstruction device, including:

The duty cycle calculation module is configured to calculate the three-phase duty cycle of the current PWM cycle based on the three-phase current value of the previous PWM cycle;

The first determination module is configured to determine that the current PWM cycle enters an unobservable region based on the three-phase duty ratio;

The second determination module is configured to determine the current vector magnitude of the current PWM cycle based on the mechanical angle of the motor rotor, the rotational angular velocity, and the peak value of the current vector magnitude before entering the unobservable region;

The current reconstruction module is configured to reconstruct the three-phase current value of the current PWM cycle based on the current vector magnitude of the current PWM cycle and the electrical angle of the motor rotor;

Wherein, the unobservable area refers to that bus current values corresponding to two non-zero voltage vectors cannot be collected in the current PWM period.

In some embodiments, the three-phase current reconstruction device also includes:

a recording module configured to record a peak current vector magnitude;

The conversion module is configured to determine the electrical angle of the motor rotor in the current PWM cycle based on the electrical angle of the motor rotor in the previous PWM cycle, the electrical angular velocity and the duration of the PWM cycle; the electrical angle of the motor rotor based on the current PWM cycle determining the mechanical angle of the motor rotor in the current PWM cycle; determining the rotational angular speed of the motor rotor in the current PWM cycle based on the electrical angular speed of the motor rotor in the last PWM cycle.

In some embodiments, the second determination module adopts the following formula:

Im=Imax*sin(ωt+θm);

Wherein, Im is the current vector amplitude of the current PWM cycle, Imax is the peak value of the current vector amplitude, ω is the rotational angular velocity, t is the duration of the PWM cycle, and θm is the mechanical angle of the motor rotor of the current PWM cycle .

In some implementations, the first determination module is specifically configured as:

determining the high-level duration of each phase line based on the three-phase duty cycle and the duration of the PWM cycle;

It is determined 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.

In some implementations, the first determination module determines that the current PWM cycle enters the 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, including one of the following :

Determine 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 cycle and the high level duration of the intermediate phase is less than the minimum sampling duration;

Determine that the difference between the high-level duration of the largest 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 duration;

Determine that the difference between the high-level duration of the largest 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 cycle and the high-level duration of the intermediate phase is greater than or equal to the minimum sampling duration;

Wherein, 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 cycle in the three-phase line, and the intermediate phase is the phase with the duty cycle in the three-phase line. middle phase.

In a third aspect, an embodiment of the present application provides a three-phase current reconstruction device, including: a processor and a memory configured to store a computer program that can run on the processor, wherein,

The processor is configured to execute the steps of the method described in the embodiments of the present application when running the computer program.

In some embodiments, the three-phase current reconstruction device further includes: a bus current acquisition device configured to acquire a sampled value of the bus current and send the sampled value to the processor.

In a fourth aspect, the embodiment of the present application provides a storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the method described in the embodiment of the present application are implemented.

In the technical solution provided by the embodiment of the present application, if it is determined that the current PWM cycle enters the unobservable area, then the current PWM cycle is determined based on the mechanical angle, rotational angular velocity of the motor rotor of the current PWM cycle, and the peak value of the current vector amplitude before entering the unobservable area. Current vector magnitude: based on the current vector magnitude of the current PWM cycle and the electrical angle of the motor rotor, reconstruct the three-phase current value of the current PWM cycle. It can realize the reconstruction of the three-phase current when the space vector falls in the unobservable area, especially in the over-modulation area, and can realize the reconstruction of the three-phase current on the basis of satisfying the effective voltage vector, and then can Under such circumstances, increase the output torque of the motor and improve the utilization rate of the power supply voltage.

Description of drawings

FIG. 1 is a schematic structural diagram of a system applying a three-phase current reconstruction method according to an embodiment of the present application;

Fig. 2 is the distribution diagram of space voltage vector;

Figure 3 is a schematic diagram of the principle of the unobservable area of the space voltage vector in the embodiment of the present application;

FIG. 4 is a schematic diagram of a principle based on phase-shifting processing in the related art;

FIG. 5 is a schematic flow diagram of a three-phase current reconstruction method according to an embodiment of the present application;

Fig. 6 is a schematic diagram of motor torque variation of a single-rotor compressor in an embodiment of the present application;

Fig. 7 is a schematic diagram of the relationship between the carrier wave and the modulation in the motor control of the embodiment of the present application;

FIG. 8 is a schematic flow diagram of a three-phase current reconstruction method in an application example 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;

FIG. 10 is a schematic structural diagram of a three-phase current reconstruction device according to an embodiment of the present application.

Detailed ways

The application will be further described in detail below in conjunction with the accompanying drawings and embodiments.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used herein in the specification of the application are only for the purpose of describing specific embodiments, and are not intended to limit the application.

Before describing the three-phase current reconfiguration method according to the embodiment of the present application, a system to which the three-phase current reconfiguration method is applied is exemplarily described.

As shown in FIG. 1 , the system includes: a motor M, a three-phase bridge inverter 101 , a DC power supply DC and a bus current acquisition device 102 .

Exemplarily, a capacitor C1 is further connected between the positive pole and the negative pole of the direct current power supply DC. The direct current supplied by the direct current power source DC is converted by the three-phase bridge inverter 101 into the three-phase power supply of the motor M, and the motor M may be a PMSM. The three-phase bridge inverter 101 can be controlled by a frequency converter using SVPWM. Among them, the bus current acquisition device 102 can adopt a typical single-resistor sampling circuit, for example, including a resistor R1 connected to the negative pole of the direct current power supply DC and the three-phase bridge inverter 101, and the voltage at both ends of the resistor R1 is calculated The amplifier is transmitted to the AD conversion circuit, and the bus current is converted by the AD conversion circuit, and the bus current is used for subsequent reconstruction of the three-phase current, and then the reconstructed three-phase AC current is used as feedback to realize closed-loop control of the current.

It can be understood that the three-phase bridge inverter is controlled by SVPWM modulation, and has 8 switch working states, including 6 non-zero voltage vectors (V ₁ -V ₆ ) and 2 zero-voltage vectors (V ₀ and V ₇ ), which divides the voltage space plane into hexagons as shown in Figure 2. The basic principle of phase current reconstruction is to use the bus current sampled at different times within a PWM cycle to obtain each phase current. 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
V 1	I c	V 5	-I b
V 2	I b	V 6	-I c
V 3	-I a	V 0	0
V 4	I a	V 7	0

In practical applications, considering that the sampling of the bus current needs to meet the sampling window, that is, the non-zero voltage vector must last for a minimum sampling time T _min , T _min = T _d + T _set + T _AD , where T _d represents up and down The length of the dead zone of the bridge arm, T _set indicates the establishment time of the bus current, and T _AD indicates the sampling conversion time.

As shown in Figure 3, when the output voltage vector is in the low modulation area or near the non-zero voltage vector, there may be a situation where the duration of the non-zero voltage vector is less than T _min in one PWM cycle. This situation renders the sampled bus current meaningless. In the embodiment of the present application, the area where two phases and different phase currents (that is, bus DC corresponding to two non-zero voltage vectors) cannot be sampled within one PWM period is collectively referred to as an unobservable area.

In related technologies, in order to ensure that two-phase currents can be sampled in each PWM cycle, it is necessary to perform phase shift processing in an unobservable region to ensure that two-phase currents can be sampled within one PWM cycle. For example, as shown in Fig. 4, the three-phase lines include: a-phase, b-phase and c-phase lines, and the sampling window of the original T1 is smaller than T _min , and the high voltage of the b-phase will be processed by phase shifting. Shifting T _shift to the right can make the sampling window of T1 equal to T _min after phase shifting.

When the unobservable area is an overmodulation area, for example, the area outside the inscribed circle of the hexagon shown in Figure 3, there will be a problem that the phase shift is shifted out of the PWM cycle and the effective vector voltage cannot be satisfied. However, if in order to ensure In the PWM cycle of the vector voltage, the sampling window cannot be provided, resulting in the inability to collect two-phase phase currents in one PWM cycle. Therefore, the related three-phase current reconstruction method based on phase-shift processing cannot meet the requirements of overmodulation. The reconstruction requirements of the three-phase current in the area.

Based on this, in various embodiments of the present application, a three-phase current reconstruction method capable of adapting to an overmodulation area is proposed, so that three-phase current reconstruction can be implemented based on the bus current in the overmodulation area.

As shown in Figure 5, the three-phase current reconstruction method of the embodiment of the present application includes:

Step 501, calculate the three-phase duty cycle of the current PWM cycle based on the three-phase current values of the previous PWM cycle.

Exemplarily, the calculation process of the three-phase duty cycle is as follows:

1) Obtain the three-phase current values ia, ib, and ic of the previous PWM cycle, where ia is the phase current corresponding to the a-phase line, ib is the phase current corresponding to the b-phase line, and ic is the phase current corresponding to the c-phase line ;

2), determine the magnetic field angle θ and speed ω of the motor rotor through the speed position estimation module;

3), the three-phase current values ia, ib, ic are obtained by clark (Clark) transformation and park (Parker) transformation to obtain id, iq, wherein, the clark transformation is used to transform the abc three-axis coordinate system into a stationary αβ coordinate system, The park transformation is used to transform the stationary αβ coordinate system into a rotating dq coordinate system, id is the current value of the converted d-axis, and iq is the current value of the converted q-axis;

4), based on the magnetic field angle θ and speed ω conversion of the motor rotor to obtain the given current value of the d-axis and q-axis, based on the given current value and the id and iq obtained in step 3), through PID (proportional integral differential) Calculate and obtain Vd and Vq, wherein, Vd is the modulation voltage of the d-axis, and Vq is the modulation voltage of the q-axis;

5) Vd and Vq are subjected to inverse park transformation to obtain Vα and Vβ, wherein Vα is the modulation voltage of the α axis, and Vβ is the modulation voltage of the β axis;

6) Va, Vb, and Vc are obtained by SV vector calculation for Vα and Vβ, wherein Va is the modulation voltage of the a-axis, Vb is the modulation voltage of the a-axis, and Vc is the modulation voltage of the a-axis;

7) Calculate the three-phase duty cycle duty _a , duty _b , and duty _c through the bus voltage and Va, Vb, and Vc, wherein, duty _a is the duty cycle of phase a, and duty _b is the duty cycle of phase b , duty _c is the duty cycle of phase c.

In step 502, it is determined that the current PWM period enters an unobservable region based on the three-phase duty cycle.

Step 503 : Determine the current vector magnitude of the current PWM cycle based on the mechanical angle and rotational angular velocity of the motor rotor in the current PWM cycle and the peak value of the current vector magnitude before entering the unobservable region.

Step 504: Reconstruct the three-phase current values of the current PWM cycle based on the current vector magnitude of the current PWM cycle and the electrical angle of the motor rotor.

Here, the unobservable area means that the bus current values corresponding to two non-zero voltage vectors cannot be collected in the current PWM cycle, that is, the currents of two phases and different phases cannot be sampled in one PWM cycle, resulting in the failure to complete the three-phase current PWM cycle. current reconstruction.

In the embodiment of the present application, if it is determined that the current PWM cycle enters the unobservable area, the current vector amplitude of the current PWM cycle is determined based on the mechanical angle, rotational angular velocity of the motor rotor of the current PWM cycle, and the peak value of the current vector amplitude before entering the unobservable area Value; based on the current vector magnitude of the current PWM cycle and the electrical angle of the motor rotor, reconstruct the three-phase current value of the current PWM cycle. It can realize the reconstruction of the three-phase current when the space vector falls in the unobservable area, especially in the over-modulation area, and can realize the reconstruction of the three-phase current on the basis of satisfying the effective voltage vector, and then can Under such circumstances, increase the output torque of the motor and improve the utilization rate of the power supply voltage.

Exemplarily, before determining the current vector magnitude of the current PWM cycle based on the mechanical angle of the motor rotor, the rotational angular velocity, and the peak value of the current vector magnitude before entering the unobservable region, the method further includes:

Record the peak value of the current vector magnitude;

Determine the electrical angle of the motor rotor in the current PWM cycle based on the electrical angle of the motor rotor in the previous PWM cycle, the electrical angular velocity and the duration of the PWM cycle;

determining the mechanical angle of the motor rotor of the current PWM cycle based on the electrical angle of the motor rotor of the current PWM cycle;

The rotational angular velocity of the motor rotor in the current PWM period is determined based on the electrical angular velocity of the motor rotor in the previous PWM period.

In the embodiment of the present application, the motor is a motor of a single-rotor compressor. Since the single-rotor compressor works based on single-cycle compression, the torque of the motor has large fluctuations in a single rotation cycle, as shown in Figure 6 , the torque T is within the rotation period of 0-2π, the minimum torque is T _min , the maximum torque is T _max , and the corresponding average torque is T _avg . The sine wave simulation method can be used to simulate the fluctuating state of the torque.

Here, the peak value of the recorded current vector amplitude may be the maximum value of the detected current vector amplitude before the motor runs to an unobservable region.

It can be understood that when the motor runs to the unobservable region and the speed of the motor rotor is higher than the rated speed, it can be considered that the motor speed remains unchanged during two PWM cycles, that is, the speed remains stable, but the torque of the motor changes dynamically. Considering the characteristic of maintaining stable rotation speed, in the embodiment of the present application, the electrical angle of the motor rotor in the current PWM cycle can be determined based on the electrical angle of the motor rotor in the previous PWM cycle, the electrical angular velocity and the duration of the PWM cycle.

Exemplarily, as shown in FIG. 7, the formula for calculating the electrical angle of the current PWM cycle is as follows:

θe2=θe1+(Ts*Fs)/2π

Among them, θe1 is the electrical angle of the previous PWM cycle, θe2 is the electrical angle of the current PWM cycle, Ts is the duration of the PWM cycle, and Fs is the electrical angular velocity (also called the electrical frequency) of the previous PWM cycle. In this way, the electrical angle of the current PWM cycle can be calculated based on the principle that the rotational speed of the motor is assumed to be constant.

Here, the electrical angle of the motor rotor is related to the number of pole pairs of the motor. If the motor has a pair of poles, the electrical angle of the motor is 360°; if the motor has two poles, the electrical angle of the motor is 720°; the motor is three For opposite poles, the electrical angle of the motor is 1080°, and so on. Assume that the number of pole pairs of the motor is P, and the total electrical angle of the motor=360°*P. It can be understood that the electrical angle of the motor=mechanical angle*P, and the electrical angular velocity of the motor=rotational angular velocity*P.

Based on the conversion relationship between the electrical angle and the mechanical angle, the mechanical angle of the motor rotor in the current PWM cycle can be determined based on the electrical angle of the motor rotor in the current PWM cycle. In addition, considering that the motor speed remains stable, the electrical angular velocity of the motor rotor in the last PWM period can be used as the electrical angular velocity of the motor rotor in the current PWM period, and then the rotational angular velocity of the motor rotor in the current PWM period can be determined.

Exemplarily, based on the mechanical angle of the motor rotor in the current PWM cycle, the rotational angular velocity, and the peak value of the current vector amplitude before entering the unobservable region, the current vector amplitude in the current PWM cycle is determined using the following formula:

Im=Imax*sin(ωt+θm);

Among them, Im is the current vector amplitude of the current PWM cycle, Imax is the peak value of the current vector amplitude, ω is the rotational angular velocity, t is the duration of the PWM cycle, and θm is the mechanical angle of the motor rotor in the current PWM cycle.

It can be understood that the mechanical angle θm is estimated and converted based on the electrical angle and electrical angular velocity of the previous PWM cycle, and the mechanical angle θm can be understood as the current rotational position of the motor rotor.

After obtaining the current vector amplitude Im of the current PWM cycle, and then based on the calculation formula of the three-phase current shown below, the current value of each phase of the current PWM cycle can be determined:

Among them, I _m is the vector current amplitude, I _a is the current value of phase a, I _b is the current value of phase b, I _c is the current value of phase c, and θe is the electrical angle. In this way, the reconstruction of the three-phase current is realized.

It can be understood that, in the three-phase current reconstruction method of the embodiment of the present application, in the unobservable area, the current PWM three-phase current reconstruction can be realized without collecting the bus current value of the current PWM period.

In some embodiments, determining that the current PWM cycle enters an unobservable region based on the three-phase duty cycle includes:

Determine the high-level duration of each phase line based on the three-phase duty cycle and the duration of the PWM cycle;

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, it is determined that the current PWM cycle enters the unobservable region.

Exemplarily, assuming that Tp is the duration of the PWM cycle, then the high-level duration of phase a is Ta=Tp*duty _a , the high-level duration of phase b is Tb=Tp*duty _b , and the high-level duration of phase c is Tc= Tp*duty _c .

Exemplarily, 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, it is determined that the current PWM cycle enters the unobservable region, including one of the following:

Determine that the difference between the high-level duration of the largest 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 cycle and the high-level duration of the intermediate phase is less than the minimum sampling duration;

Determine that the difference between the high-level duration of the largest 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;

Determine that the difference between the high-level duration of the largest 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 cycle and the high-level duration of the intermediate phase is greater than or equal to the minimum sampling duration;

Among them, the largest phase is the phase with the largest duty ratio in the three-phase line, the smallest phase is the phase with the smallest duty ratio in the three-phase line, and the middle phase is the phase with the duty ratio in the middle of the three-phase line.

It can be understood that when the difference between the high-level duration of the largest 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 cycle and the high-level duration of the intermediate phase is less than the minimum sampling duration, the three-phase In the duty ratio, there is a situation where the duty ratios of the two phases are both large; when the difference between the high-level duration of the largest phase and the high-level duration of the middle phase is greater than or equal to the minimum sampling duration and the high-level duration of the middle phase and the minimum When the high-level durations of the phases are less than the minimum sampling duration, the duty ratios of two phases among the three-phase duty ratios are smaller. At this time, the acquisition of the two-phase currents cannot be achieved through phase-shifting processing. Based on the method of the embodiment of the present application, it is not necessary to collect the two-phase current, but to reconstruct the three-phase current value of the current PWM cycle based on the current vector amplitude of the current PWM cycle and the electrical angle of the motor rotor, so as to realize the vector control of the motor .

It can be understood that when the difference between the high-level duration of the largest 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 cycle and the high-level duration of the intermediate phase is greater than or equal to the minimum sampling duration, It can be based on the phase-shift processing of the intermediate phase, so that the two-phase phase current can be sampled in the PWM cycle, and the reconstruction of the three-phase current can be realized, and the reconstruction of the three-phase current can also be realized based on the method of the embodiment of the application. Examples are not limited to this.

The three-phase current reconfiguration method in the embodiment of the present application will be illustrated below with reference to an application example.

As shown in Figure 8, the three-phase current reconstruction method may include:

Step 801, calculate the three-phase duty cycle and the size of the sampling window of the current PWM period.

Exemplarily, the three-phase duty cycle of the current PWM cycle can be calculated based on the three-phase current values of the previous PWM cycle. For details, reference can be made to the foregoing description, which will not be repeated here.

Here, the size of the sampling window is the minimum sampling duration T _min for which the non-zero voltage vector must last, T _min = T _d + T _set + T _AD , where T _d represents the dead zone duration of the upper and lower bridge arms, and T _set represents the bus current Set up time, T _AD represents the sampling conversion time.

Step 802, judge whether to enter the unobservable area, if not, execute step 803, then execute step 806, if yes, execute step 804 and step 805, then execute step 806;

Exemplarily, the high-level duration of each phase line can be determined based on the three-phase duty cycle and the duration of the PWM cycle; and then the current Whether the PWM period enters the unobservable region.

In step 803, the normal three-phase current is reconstructed, and the peak value of the current vector amplitude is recorded.

If it is determined that the current PWM cycle does not enter the unobservable area, the two-phase current can be collected normally to obtain the three-phase current, and the peak value Imax of the current vector amplitude can be recorded.

Step 804, based on the mechanical angle of the motor rotor in the current PWM cycle, the rotational angular velocity, and the peak value of the current vector amplitude before entering the unobservable region, determine the current vector amplitude in the current PWM cycle.

If it is determined that the current PWM period enters the unobservable region, the mechanical angle and rotational angular velocity of the motor rotor of the current PWM period can be determined based on the method of the embodiment of the present application, and then based on the mechanical angle, rotational angular velocity and the peak value of the current vector amplitude, determine For the current vector magnitude of the current PWM cycle, reference may be made to the foregoing description for details, and details will not be repeated here.

Step 805: Reconstruct the three-phase current values of the current PWM cycle based on the current vector amplitude of the current PWM cycle and the electrical angle of the motor rotor.

Step 806, vector control of the motor.

Motor vector operation control can be performed based on the three-phase current value of the current PWM cycle, for example, the motor can 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, in the unobservable region, the reconstruction of the current PWM three-phase current can be realized without collecting the bus current value of the current PWM cycle. In this way, the requirement of three-phase current reconstruction based on the bus current in the over-modulation area can be met, and then the output torque of the motor can be increased and the utilization rate of the power supply voltage can be improved under the condition that the bus voltage remains unchanged.

In order to realize the method of the embodiment of the present application, the embodiment of the present application also provides a three-phase current reconstruction device, the three-phase current reconstruction device corresponds to the above-mentioned three-phase current reconstruction method, the above-mentioned three-phase current reconstruction method embodiment Each step in is also fully applicable to this embodiment of the three-phase current reconstruction device.

As shown in FIG. 9 , the three-phase current reconstruction device includes: a duty cycle calculation module 901 , a first determination module 902 , a second determination module 903 and a current reconstruction module 904 .

The duty cycle calculation module 901 is configured to calculate the three-phase duty cycle of the current PWM cycle based on the three-phase current values of the previous PWM cycle;

The first determination module 902 is configured to determine that the current PWM cycle enters the unobservable region based on the three-phase duty ratio;

The second determination module 903 is configured to determine the current vector magnitude of the current PWM cycle based on the mechanical angle of the motor rotor, the rotational angular velocity, and the peak value of the current vector magnitude before entering the unobservable region;

The current reconstruction module 904 is configured to reconstruct the three-phase current value of the current PWM cycle based on the current vector magnitude of the current PWM cycle and the electrical angle of the motor rotor;

Wherein, the unobservable area refers to that the bus current values corresponding to two non-zero voltage vectors cannot be collected in the current PWM period.

In some embodiments, the three-phase current reconstruction device also includes:

The recording module 905 is configured to record the peak value of the current vector magnitude;

The conversion module 906 is configured to determine the electrical angle of the motor rotor in the current PWM cycle based on the electrical angle of the motor rotor in the previous PWM cycle, the electrical angular velocity, and the duration of the PWM cycle; determine the current PWM based on the electrical angle of the motor rotor in the current PWM cycle. The mechanical angle of the motor rotor in the period; the rotational angular velocity of the motor rotor in the current PWM period is determined based on the electrical angular velocity of the motor rotor in the previous PWM period.

In some embodiments, the second determination module 903 adopts the following formula:

Im=Imax*sin(ωt+θm);

Among them, Im is the current vector amplitude of the current PWM cycle, Imax is the peak value of the current vector amplitude, ω is the rotational angular velocity, t is the duration of the PWM cycle, and θm is the mechanical angle of the motor rotor in the current PWM cycle.

In some implementations, the first determination module 902 is specifically configured to:

Determine the high-level duration of each phase line based on the three-phase duty cycle and the duration of the PWM cycle;

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, it is determined that the current PWM cycle enters the unobservable region.

In some embodiments, the first determination module 902 determines that the current PWM cycle enters the 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, including one of the following:

Determine that the difference between the high-level duration of the largest 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 cycle and the high-level duration of the intermediate phase is less than the minimum sampling duration;

Determine that the difference between the high-level duration of the largest 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;

Determine that the difference between the high-level duration of the largest 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 cycle and the high-level duration of the intermediate phase is greater than or equal to the minimum sampling duration;

Among them, the largest phase is the phase with the largest duty ratio in the three-phase line, the smallest phase is the phase with the smallest duty ratio in the three-phase line, and the middle phase is the phase with the duty ratio in the middle of the three-phase line.

In actual application, the duty cycle calculation module 901, the first determination module 902, the second determination module 903, the current reconstruction module 904, the recording module 905 and the conversion module 906 can be implemented by the processor of the three-phase current reconstruction device . Of course, a processor needs to run a computer program in memory to carry out its functions.

It should be noted that when the three-phase current reconstruction device provided in the above-mentioned embodiment performs three-phase current reconstruction, the division of the above-mentioned program modules is used as an example for illustration. In practical applications, the above-mentioned processing can be allocated by Different program modules are completed, that is, the internal structure of the device is divided into different program modules to complete all or part of the processing described above. In addition, the three-phase current reconfiguration device provided in the above embodiment and the three-phase current reconfiguration method embodiment belong to the same idea, and its specific implementation process is detailed in the method embodiment, and will not be repeated here.

Based on the hardware implementation of the above program modules, 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. 10 only shows an exemplary structure of the three-phase current reconfiguration device but not the entire structure, and some or all of the structures shown in FIG. 10 can be implemented as required.

As shown in FIG. 10 , the three-phase current reconstruction device 1000 provided by the embodiment of the present application includes: at least one processor 1001 , a memory 1002 and a user interface 1003 . Various components in the three-phase current reconstruction device 1000 are coupled together through the bus system 1004 . It can be understood that the bus system 1004 is used to realize connection and communication between these components. In addition to the data bus, the bus system 1004 also includes a power bus, a control bus and a status signal bus. However, the various buses are labeled as bus system 1004 in FIG. 10 for clarity of illustration.

Exemplarily, the three-phase current reconstruction device 1000 further includes: a bus current acquisition device configured to acquire a sampled value of the bus current and send the sampled value to the processor 1001 . For example, the bus current acquisition device may be a single-resistor sampling circuit as shown in FIG. 1 .

Wherein, the user interface 1003 may include a display, a keyboard, a mouse, a trackball, a click wheel, keys, buttons, a touch panel or a touch screen, and the like.

The memory 1002 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 operation on a three-phase current reconstruction device.

The three-phase current reconstruction method disclosed in the embodiment of the present application may be applied to the processor 1001 or implemented by the processor 1001 . The processor 1001 may be an integrated circuit chip with signal processing capabilities. During implementation, each step of the three-phase current reconfiguration method may be completed by an integrated logic circuit of hardware in the processor 1001 or instructions in the form of software. The aforementioned processor 1001 may be a general-purpose processor, a digital signal processor (DSP, Digital Signal Processor), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, and the like. The processor 1001 may implement or execute various methods, steps, and logic block diagrams 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 can be located in the storage medium, the storage medium is located in the memory 1002, the processor 1001 reads the information in the memory 1002, and combines its hardware to complete the steps of the three-phase current reconstruction method provided by the embodiment of the present application.

In an exemplary embodiment, the three-phase current reconstruction device may be implemented by one or more Application Specific Integrated Circuits (ASIC, Application Specific Integrated Circuit), DSP, Programmable Logic Device (PLD, Programmable Logic Device), complex programmable logic Device (CPLD, Complex Programmable Logic Device), field programmable logic gate array (FPGA, Field Programmable Gate Array), general processor, controller, microcontroller (MCU, Micro Controller Unit), microprocessor (Microprocessor), Or implemented by other electronic components for performing the aforementioned method.

It can be understood that the memory 1002 may be a volatile memory or a non-volatile memory, and may also include both volatile and non-volatile memories. Among them, the non-volatile memory can be read-only memory (ROM, Read Only Memory), programmable read-only memory (PROM, Programmable Read-Only Memory), erasable programmable read-only memory (EPROM, Erasable Programmable Read-Only Memory) Only Memory), Electrically Erasable Programmable Read-Only Memory (EEPROM, Electrically Erasable Programmable Read-Only Memory), Magnetic Random Access Memory (FRAM, ferromagnetic random access memory), Flash Memory (Flash Memory), Magnetic Surface Memory , CD, or CD-ROM (Compact Disc Read-Only Memory); magnetic surface storage can be disk storage or tape storage. The volatile memory may be random access memory (RAM, Random Access Memory), which is used as an external cache. By way of illustration and not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM, Static Random Access Memory), Synchronous Static Random Access Memory (SSRAM, Synchronous Static Random Access Memory), Dynamic Random Access Memory Memory (DRAM, Dynamic Random Access Memory), synchronous dynamic random access memory (SDRAM, Synchronous Dynamic Random Access Memory), double data rate synchronous dynamic random access memory (DDRSDRAM, Double Data Rate Synchronous Dynamic Random Access Memory), enhanced Synchronous Dynamic Random Access Memory (ESDRAM, Enhanced Synchronous Dynamic Random Access Memory), Synchronous Link Dynamic Random Access Memory (SLDRAM, SyncLink Dynamic Random Access Memory), Direct Memory Bus Random Access Memory (DRRAM, Direct Rambus Random Access Memory ). The memories described in the embodiments of the present application are intended to include, but are not limited to, these and any other suitable types of memories.

In an exemplary embodiment, the embodiment of the present application also provides a storage medium, that is, a computer storage medium, specifically, it may be a computer-readable storage medium, for example, including a memory 1002 storing a computer program. The processor 1001 of the structural device is executed to complete the steps of the method in the embodiment of the present application. The computer-readable storage medium may be memory such as ROM, PROM, EPROM, EEPROM, Flash Memory, magnetic surface memory, optical disc, or CD-ROM.

It should be noted that: "first", "second", etc. are used to distinguish similar objects, and not necessarily used to describe a specific order or sequence.

In addition, the technical solutions described in the embodiments of the present application can be combined arbitrarily if there is no conflict.

The above is only the specific implementation of the application, but the scope of protection of the application is not limited thereto. Anyone familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the application. Should be covered within the protection scope of this application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims (13)

1. A three-phase current reconstruction method, comprising:

   Calculate the three-phase duty cycle of the current PWM cycle based on the three-phase current value of the previous PWM cycle;

   determining that the current PWM cycle enters an unobservable region based on the three-phase duty ratio;

   Determine the current vector amplitude of the current PWM cycle based on the mechanical angle of the motor rotor of the current PWM cycle, the rotational angular velocity, and the peak value of the current vector amplitude before entering the unobservable region;

   Reconstructing the three-phase current values of the current PWM cycle based on the current vector magnitude of the current PWM cycle and the electrical angle of the motor rotor;

   Wherein, the unobservable area refers to that bus current values corresponding to two non-zero voltage vectors cannot be collected in the current PWM period.
2. The method according to claim 1, wherein the current vector of the current PWM cycle is determined based on the mechanical angle of the motor rotor of the current PWM cycle, the rotational angular velocity, and the peak value of the current vector amplitude before entering the unobservable region Before the magnitude, the method also includes:

   Record the peak value of the current vector magnitude;

   Determine the electrical angle of the motor rotor in the current PWM cycle based on the electrical angle of the motor rotor in the previous PWM cycle, the electrical angular velocity, and the duration of the PWM cycle;

   determining the mechanical angle of the motor rotor in the current PWM cycle based on the electrical angle of the motor rotor in the current PWM cycle;

   The rotational angular velocity of the motor rotor in the current PWM period is determined based on the electrical angular velocity of the motor rotor in the last PWM period.
3. The method according to claim 1, wherein the current vector of the current PWM cycle is determined based on the mechanical angle of the motor rotor of the current PWM cycle, the rotational angular velocity, and the peak value of the current vector amplitude before entering the unobservable region Amplitude, using the following formula:

   Im=Imax*sin(ωt+θm);

   Wherein, Im is the current vector amplitude of the current PWM cycle, Imax is the peak value of the current vector amplitude, ω is the rotational angular velocity, t is the duration of the PWM cycle, and θm is the mechanical angle of the motor rotor of the current PWM cycle .
4. The method according to claim 1, wherein said determining that said current PWM cycle enters an unobservable region based on said three-phase duty cycle comprises:

   determining the high-level duration of each phase line based on the three-phase duty cycle and the duration of the PWM cycle;

   It is determined 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.
5. The method according to claim 4, wherein the determination that the current PWM cycle enters the 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 includes the following one:

   determining that the difference between the high-level duration of the largest 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 cycle and the high-level duration of the intermediate phase is less than the minimum sampling duration;

   Determine that the difference between the high-level duration of the largest 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 duration;

   Determine that the difference between the high-level duration of the largest 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 cycle and the high-level duration of the intermediate phase is greater than or equal to the minimum sampling duration;

   Wherein, 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 cycle in the three-phase line, and the intermediate phase is the phase with the duty cycle in the three-phase line. middle phase.
6. A three-phase current reconstruction device, comprising:

   The duty cycle calculation module is configured to calculate the three-phase duty cycle of the current PWM cycle based on the three-phase current value of the previous PWM cycle;

   The first determination module is configured to determine that the current PWM cycle enters an unobservable region based on the three-phase duty ratio;

   The second determination module is configured to determine the current vector magnitude of the current PWM cycle based on the mechanical angle of the motor rotor, the rotational angular velocity, and the peak value of the current vector magnitude before entering the unobservable region;

   The current reconstruction module is configured to reconstruct the three-phase current value of the current PWM cycle based on the current vector magnitude of the current PWM cycle and the electrical angle of the motor rotor;

   Wherein, the unobservable area refers to that bus current values corresponding to two non-zero voltage vectors cannot be collected in the current PWM period.
7. The three-phase current reconstruction device according to claim 6, wherein the three-phase current reconstruction device further comprises:

   a recording module configured to record a peak current vector magnitude;

   The conversion module is configured to determine the electrical angle of the motor rotor in the current PWM cycle based on the electrical angle of the motor rotor in the previous PWM cycle, the electrical angular velocity and the duration of the PWM cycle; the electrical angle of the motor rotor based on the current PWM cycle determining the mechanical angle of the motor rotor in the current PWM cycle; determining the rotational angular speed of the motor rotor in the current PWM cycle based on the electrical angular speed of the motor rotor in the last PWM cycle.
8. The three-phase current reconstruction device according to claim 6, wherein the second determination module adopts the following formula:

   Im=Imax*sin(ωt+θm);

   Wherein, Im is the current vector amplitude of the current PWM cycle, Imax is the peak value of the current vector amplitude, ω is the rotational angular velocity, t is the duration of the PWM cycle, and θm is the mechanical angle of the motor rotor of the current PWM cycle .
9. The three-phase current reconstruction device according to claim 6, wherein the first determination module is specifically configured as:

   determining the high-level duration of each phase line based on the three-phase duty cycle and the duration of the PWM cycle;

   It is determined 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.
10. The three-phase current reconstruction device according to claim 9, wherein the first determination module determines the current PWM 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. Periods enter the unobservable region, including one of the following:

    determining that the difference between the high-level duration of the largest 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 cycle and the high-level duration of the intermediate phase is less than the minimum sampling duration;

    Determine that the difference between the high-level duration of the largest 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 duration;

    Determine that the difference between the high level duration of the largest 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 cycle and the high level duration of the intermediate phase is greater than or equal to the minimum sampling duration duration;

    Wherein, 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 smallest duty cycle in the three-phase line. middle phase.
11. A three-phase current reconstruction device, comprising: a processor and a memory configured to store a computer program capable of running on the processor, wherein,

    The processor is configured to execute the steps of the method according to any one of claims 1 to 5 when running the computer program.
12. The three-phase current reconstruction device according to claim 11, further comprising:

    The bus current acquisition device is configured to acquire a sampled value of the bus current and send the sampled value to the processor.
13. A storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the method described in any one of claims 1 to 5 are realized.

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