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

Abstract

The present application discloses a three-phase current reconstruction method, device, equipment and storage medium. The method includes: calculating 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 the unobservable area based on the three-phase duty cycle; reconstructing the three-phase current value of the current PWM cycle based on the bus current value collected in the unobservable area of ​​the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle; wherein the unobservable area refers to the bus current value corresponding to only one non-zero voltage vector that can be collected in the current PWM cycle. It can be realized that when the space vector falls in the unobservable area, the three-phase current reconstruction is realized based on the sampling value of the bus current, especially in the overmodulation area, the three-phase current reconstruction can be realized on the basis of satisfying the effective voltage vector, and then the output torque of the motor can be increased and the power supply voltage utilization rate can be improved under the condition that the bus voltage remains unchanged.

Description

Technical Field

[0001] The present application relates to the field of motor control technology, and in particular to a three-phase current reconstruction method, device, equipment and storage medium. Background Art

[0002] With the active promotion of energy-saving and consumption-reducing technologies, energy-saving technologies for motor control are increasingly valued. For example, variable frequency air conditioners use permanent magnetic synchronous motors (PMSM) with low loss and high efficiency.

[0003] When the inverter drives a permanent magnet synchronous motor, the three-phase bridge inverter of the inverter can be controlled by SVPWM (Space Vector Pulse Width Modulation). SVPWM is based on the idea of ​​stator flux tracking of AC motors, is easy to implement with digital controllers, and has the advantages of good output current waveform and high DC link voltage utilization.

[0004] In the traditional SVPWM control system, the three-phase AC signal needs to be measured as feedback to achieve closed-loop control of the current. That is, three current sensors need to be set on the AC side of the inverter, which leads to high cost, complex structure and large volume, which is not conducive to integration. Using a single current sensor to complete the reconstruction of the three-phase current has become a hot topic in research.

[0005] In practical applications, in order to increase the output voltage of the three-phase bridge inverter and increase the maximum output torque of the motor in motor control, overmodulation technology is often required. However, since the space vector falls into the unobservable area when overmodulation occurs, the related method of completing three-phase current reconstruction based on a single current sensor is difficult to implement. Summary of the invention

[0006] In view of this, embodiments of the present application provide a three-phase current reconstruction method, apparatus, device and storage medium, which are intended to meet the three-phase current reconstruction requirements of SVPWM control under the condition of single current sensor acquisition.

[0007] The technical solution of the embodiment of the present application is implemented as follows:

[0008] In a first aspect, an embodiment of the present application provides a three-phase current reconstruction method, comprising:

[0009] Calculate the three-phase duty cycle of the current pulse width modulation (PWM) cycle based on the three-phase current values ​​of the previous PWM cycle;

[0010] Determining that the current PWM cycle enters an unobservable region based on the three-phase duty cycle;

[0011] Reconstructing the three-phase current values ​​of the current PWM cycle based on the bus current value collected in the unobservable area during the current PWM cycle and the electrical angle of the motor rotor during the current PWM cycle;

[0012] The unobservable area refers to a bus current value corresponding to only one non-zero voltage vector that can be collected in the current PWM cycle.

[0013] In some embodiments, before reconstructing the three-phase current value of the current PWM cycle based on the bus current value collected in the unobservable area of ​​the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle, the method further includes:

[0014] Make sure the motor is in constant torque control mode;

[0015] The electrical angle of the motor rotor in the current PWM cycle is determined based on the electrical angle of the motor rotor in the previous PWM cycle, the duration of the PWM cycle, and the electrical angular velocity of the motor rotor in the previous PWM cycle.

[0016] In some embodiments, reconstructing the three-phase current value of the current PWM cycle based on the bus current value collected in the unobservable area of ​​the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle includes:

[0017] Determine the current vector amplitude of the current PWM cycle based on the bus current value and the electrical angle of the motor rotor of the current PWM cycle;

[0018] The phase current values ​​of the remaining two phases other than the bus current value are determined based on the current vector magnitude of the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle.

[0019] In some embodiments, determining that the current PWM cycle enters an unobservable region based on the three-phase duty cycle includes:

[0020] Determine the high level duration of each phase line based on the three-phase duty cycle and the duration of the PWM cycle;

[0021] It is determined that the current PWM cycle enters the unobservable area 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.

[0022] In some implementation schemes, determining 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:

[0023] Determine that the difference between the high level duration of the maximum phase and the high level duration of the middle 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 middle phase is less than the minimum sampling duration;

[0024] Determine that the difference between the high level duration of the maximum 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 high level duration of the minimum phase are both less than the minimum sampling duration;

[0025] Determine that the difference between the high level duration of the maximum phase and the high level duration of the middle 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 middle phase is greater than or equal to the minimum sampling duration;

[0026] Among them, the maximum phase is the phase with the largest duty cycle in the three-phase circuit, the minimum phase is the phase with the smallest duty cycle in the three-phase circuit, and the middle phase is the phase with the middle duty cycle in the three-phase circuit.

[0027] In a second aspect, an embodiment of the present application provides a three-phase current reconstruction device, comprising:

[0028] A duty cycle calculation module, used to calculate the three-phase duty cycle of the current PWM cycle based on the three-phase current values ​​of the previous PWM cycle;

[0029] A determination module, configured to determine whether the current PWM cycle enters an unobservable region based on the three-phase duty cycle;

[0030] A current reconstruction module, used to reconstruct the three-phase current value of the current PWM cycle based on the bus current value collected in the unobservable area of ​​the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle;

[0031] The unobservable area refers to a bus current value corresponding to only one non-zero voltage vector that can be collected in the current PWM cycle.

[0032] In some embodiments, the determining module is further configured to:

[0033] Make sure the motor is in constant torque control mode;

[0034] The electrical angle of the motor rotor in the current PWM cycle is determined based on the electrical angle of the motor rotor in the previous PWM cycle, the duration of the PWM cycle, and the electrical angular velocity of the motor rotor in the previous PWM cycle.

[0035] In some embodiments, the current reconstruction module is specifically used to:

[0036] Determine the current vector amplitude of the current PWM cycle based on the bus current value and the electrical angle of the motor rotor of the current PWM cycle;

[0037] The phase current values ​​of the remaining two phases other than the bus current value are determined based on the current vector magnitude of the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle.

[0038] In some embodiments, the determination module is specifically used to:

[0039] Determine the high level duration of each phase line based on the three-phase duty cycle and the duration of the PWM cycle;

[0040] It is determined that the current PWM cycle enters the unobservable area 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.

[0041] In some implementation schemes, the 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:

[0042] Determine that the difference between the high level duration of the maximum phase and the high level duration of the middle 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 middle phase is less than the minimum sampling duration;

[0043] Determine that the difference between the high level duration of the maximum 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 high level duration of the minimum phase are both less than the minimum sampling duration;

[0044] Determine that the difference between the high level duration of the maximum phase and the high level duration of the middle 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 middle phase is greater than or equal to the minimum sampling duration;

[0045] Among them, the maximum phase is the phase with the largest duty cycle in the three-phase circuit, the minimum phase is the phase with the smallest duty cycle in the three-phase circuit, and the middle phase is the phase with the middle duty cycle in the three-phase circuit.

[0046] In a third aspect, an embodiment of the present application provides a three-phase current reconstruction device, comprising: a processor and a memory for storing a computer program that can be run on the processor, wherein:

[0047] The processor is used to execute the steps of the method described in the embodiment of the present application when running a computer program.

[0048] In some embodiments, the three-phase current reconstruction device further includes: a bus current acquisition device, which is used to obtain a sampled value of the bus current and send the sampled value to the processor.

[0049] In a fourth aspect, an embodiment of the present application provides a storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described in the embodiment of the present application are implemented.

[0050] The technical solution provided in the embodiment of the present application reconstructs the three-phase current value of the current PWM cycle based on the bus current value collected in the unobservable area of ​​the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle. When the space vector falls in the unobservable area, three-phase current reconstruction can be achieved based on the sampled value of the bus current. Especially in the overmodulation area, three-phase current reconstruction can be achieved on the basis of satisfying the effective voltage vector, thereby increasing the output torque of the motor and improving the power supply voltage utilization rate under the condition that the bus voltage remains unchanged. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 A schematic diagram of the structure of a system using the three-phase current reconstruction method of an embodiment of the present application;

[0052] Figure 2 is a schematic diagram of the distribution of the space voltage vector;

[0053] Figure 3 This is a schematic diagram of the principle of the unobservable region of the spatial voltage vector in the embodiment of the present application;

[0054] Figure 4 It is a schematic diagram of the principle based on phase shifting processing in the related art;

[0055] Figure 5 This is a flow chart of a three-phase current reconstruction method according to an embodiment of the present application;

[0056] Figure 6 This is a schematic diagram of the relationship between carrier and modulation in motor control in an embodiment of the present application;

[0057] Figure 7 This is a flow chart of a three-phase current reconstruction method according to an application example of the present application;

[0058] Figure 8 This is a schematic diagram of the structure of a three-phase current reconstruction device according to an embodiment of the present application;

[0059] Fig. 9 It is a schematic diagram of the structure of the three-phase current reconstruction device according to an embodiment of the present application. DETAILED DESCRIPTION

[0060] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0061] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0062] Before describing the three-phase current reconstruction method according to the embodiment of the present application, a system to which the three-phase current reconstruction method is applied is first described by way of example.

[0063] like Figure 1 As shown, the system includes: a motor M, a three-phase bridge inverter 101 , a direct current power supply DC and a bus current acquisition device 102 .

[0064] Exemplarily, a capacitor C1 is also connected between the positive and negative electrodes of the DC power supply DC. The DC power supplied by the DC power supply DC is converted into a three-phase power supply for the motor M via the three-phase bridge inverter 101, and the motor M may be a PMSM. The three-phase bridge inverter 101 may be controlled by a frequency converter using an SVPWM method. Among them, the bus current acquisition device 102 may use a typical single resistor sampling circuit, for example, including a resistor R1 connected between the negative electrode of the DC power supply DC and the three-phase bridge inverter 101, the voltage across the resistor R1 is transmitted to the AD conversion circuit via an operational amplifier, and the AD conversion circuit converts the bus current, which is used for subsequent three-phase current reconstruction, and then the reconstructed three-phase AC current is used as feedback to achieve closed-loop control of the current.

[0065] It can be understood that the three-phase bridge inverter is controlled by SVPWM modulation, which has 8 switching 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 hexagonal shapes such as 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 DC bus current and the three-phase current is determined by the state of the instantaneous switch quantity, as shown in Table 1.

[0066] Table 1

[0067] Voltage Vector Phase current Voltage Vector Phase current <![CDATA[V 1 ]]> <![CDATA[I c ]]> <![CDATA[V 5 ]]> <![CDATA[-I b ]]> <![CDATA[V 2 ]]> <![CDATA[I b ]]> <![CDATA[V 6 ]]> <![CDATA[-I c ]]> <![CDATA[V 3 ]]> <![CDATA[-I a ]]> <![CDATA[V 0 ]]> 0 <![CDATA[V 4 ]]> <![CDATA[I a ]]> <![CDATA[V 7 ]]> 0

[0068] In practical applications, considering that the sampling of bus current must 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 Indicates the dead time of the upper and lower bridge arms, T set Indicates the time it takes for the bus current to build up, T AD Indicates the sampling conversion time.

[0069] like Figure 3 As shown in FIG. 1 , when the output voltage vector is in the low modulation area or near the non-zero voltage vector, the duration of the non-zero voltage vector may be less than T in one PWM cycle. min This situation makes the sampled bus current meaningless. In the embodiment of the present application, the area where two-phase out-of-phase currents (i.e., bus DC corresponding to two non-zero voltage vectors) cannot be sampled within one PWM cycle is collectively referred to as an unobservable area.

[0070] In the related art, in order to ensure that two-phase currents can be sampled in each PWM cycle, it is necessary to perform phase shifting processing in the unobservable area to ensure that two-phase currents are sampled in one PWM cycle. Figure 4 As shown, exemplarily, the three-phase line includes: phase a, phase b and phase c lines, and the original sampling window of T1 is smaller than T min , the high level of phase b is shifted right by T shift , the sampling window of T1 after phase shift can be made equal to T min .

[0071] When the unobservable region is an overmodulation region, for example, Figure 3 In the area outside the inscribed circle of the hexagon shown, the phase shift will be out of the PWM cycle, resulting in the problem of not being able to meet the effective vector voltage. However, if the PWM cycle of the vector voltage is guaranteed, the sampling window cannot be provided, resulting in the inability to collect two-phase currents within one PWM cycle. Therefore, the related three-phase current reconstruction method based on phase shifting processing cannot meet the reconstruction requirements of the three-phase current in the overmodulation area.

[0072] Based on this, in various embodiments of the present application, a three-phase current reconstruction method that can adapt to the overmodulation area is proposed, so that three-phase current reconstruction can be achieved based on the bus current in the overmodulation area.

[0073] like Figure 5 As shown, the three-phase current reconstruction method of the embodiment of the present application includes:

[0074] Step 501, calculating the three-phase duty ratio of the current PWM cycle based on the three-phase current values ​​of the previous PWM cycle.

[0075] Exemplarily, the calculation process of the three-phase duty cycle is as follows:

[0076] 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;

[0077] 2) Determine the magnetic field angle θ and speed ω of the motor rotor through the speed position estimation module;

[0078] 3) The three-phase current values ​​ia, ib, and ic are obtained by Clark transformation and Park transformation to obtain ID and IQ, wherein Clark transformation is used to transform the ABC three-axis coordinate system into the stationary αβ coordinate system, and Park transformation is used to transform the stationary αβ coordinate system into the rotating dq coordinate system, ID is the current value of the d-axis after transformation, and IQ is the current value of the q-axis after transformation;

[0079] 4) Based on the magnetic field angle θ and speed ω of the motor rotor, the given current values ​​of the d-axis and q-axis are converted, and based on the given current value and the id and iq obtained in step 3), PID (proportional integral differential) operation is performed to obtain Vd and Vq, where Vd is the modulation voltage of the d-axis and Vq is the modulation voltage of the q-axis;

[0080] 5) Through inverse park transformation of Vd and Vq, Vα and Vβ are obtained, where Vα is the modulation voltage of the α axis and Vβ is the modulation voltage of the β axis;

[0081] 6) Perform SV vector operation on Vα and Vβ to obtain Va, Vb, and Vc, where 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;

[0082] 7) Calculate the three-phase duty ratio through the bus voltage and Va, Vb, and Vc a 、duty b 、duty c , among which, duty a is the duty cycle of phase a, duty b is the duty cycle of phase b, duty c is the duty cycle of phase c.

[0083] Step 502: determine whether the current PWM cycle enters the unobservable region based on the three-phase duty cycle.

[0084] Step 503, reconstructing the three-phase current values ​​of the current PWM cycle based on the bus current value collected in the unobservable area of ​​the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle.

[0085] Here, the unobservable area means that only one bus current value corresponding to a non-zero voltage vector can be collected in the current PWM cycle, that is, two different phase currents cannot be sampled in one PWM cycle, resulting in the inability to complete the reconstruction of the three-phase current of the current PWM cycle.

[0086] In an embodiment of the present application, the three-phase current value of the current PWM cycle is reconstructed based on the bus current value collected in the unobservable area of ​​the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle. When the space vector falls in the unobservable area, three-phase current reconstruction can be achieved based on the sampled value of the bus current. Especially in the overmodulation area, three-phase current reconstruction can be achieved on the basis of satisfying the effective voltage vector, thereby increasing the output torque of the motor and improving the power supply voltage utilization rate while keeping the bus voltage unchanged.

[0087] In some embodiments, before reconstructing the three-phase current value of the current PWM cycle based on the bus current value collected in the unobservable area of ​​the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle, the method further includes:

[0088] Make sure the motor is in constant torque control mode;

[0089] The electrical angle of the motor rotor in the current PWM cycle is determined based on the electrical angle of the motor rotor in the previous PWM cycle, the duration of the PWM cycle, and the electrical angular velocity of the motor rotor in the previous PWM cycle.

[0090] It can be understood that when the motor runs to the unobservable area, the speed of the motor rotor is higher than the rated speed. If the motor is in constant torque control mode, it can be considered that the torque and speed of the motor are unchanged within two PWM cycles. Therefore, the electrical angle of the current PWM cycle can be calculated based on the electrical angular velocity (also called electrical frequency) and electrical angle of the motor rotor in the previous PWM cycle.

[0091] Here, the electrical angle of the motor rotor is related to the number of pole pairs of the motor. If the motor has one pair of poles, then the motor has an electrical angle of 360° in one revolution; if the motor has two pairs of poles, then the motor has an electrical angle of 720° in one revolution; if the motor has three pairs of poles, then the motor has an electrical angle of 1080° in one revolution, and so on. Assuming that the number of pole pairs of the motor is P, the total electrical angle of the motor = 360°*P. It can be understood that the electrical angular velocity of the motor = angular velocity*P.

[0092] For example, Figure 6 As shown, the formula for calculating the electrical angle of the current PWM cycle is as follows:

[0093] θ2=θ1+(Ts*Fs) / 2π

[0094] Wherein, θ1 is the electrical angle of the previous PWM cycle, θ2 is the electrical angle of the current PWM cycle, Ts is the duration of the PWM cycle, and Fs is the electrical angular velocity of the previous PWM cycle.

[0095] In this way, the electrical angle of the current PWM cycle can be calculated based on the principle that the motor speed remains unchanged.

[0096] In some embodiments, based on the bus current value collected in the unobservable area of ​​the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle, the three-phase current value of the current PWM cycle is reconstructed, including:

[0097] Determine the current vector amplitude of the current PWM cycle based on the bus current value and the electrical angle of the motor rotor of the current PWM cycle;

[0098] The phase current values ​​of the remaining two phases other than the bus current value are determined based on the current vector magnitude of the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle.

[0099] It is understandable that, in the unobservable area, a bus current value corresponding to a non-zero voltage vector can be collected based on the bus current collection 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.

[0100] Based on the three-phase current calculation formula shown below, the current vector amplitude of the current PWM cycle can be determined:

[0101]

[0102] Among them, I m is the current vector magnitude, I a is the current value of phase a, I b is the b-phase current value, I c is the c-phase current value, and θ is the electrical angle.

[0103] For example, assuming that the bus current value corresponds to the a-phase current value, then based on I a and θ to obtain I m , then based on I m and θ, calculate I b and I c , thus realizing the reconstruction of three-phase current.

[0104] In some embodiments, determining that the current PWM cycle enters the unobservable region based on the three-phase duty cycle includes:

[0105] Determine the high level duration of each phase line based on the three-phase duty cycle and the duration of the PWM cycle;

[0106] 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 area.

[0107] For example, assuming that Tp is the duration of the PWM cycle, the high level duration of phase a Ta = Tp*duty a , the high level duration of phase b Tb=Tp*duty b , the high level duration of phase c Tc=Tp*duty c .

[0108] Exemplarily, determining that the current PWM cycle enters the unobservable area 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:

[0109] Determine that the difference between the high level duration of the maximum phase and the high level duration of the middle 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 middle phase is less than the minimum sampling duration;

[0110] Determine that the difference between the high level duration of the maximum 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 high level duration of the minimum phase are both less than the minimum sampling duration;

[0111] Determine that the difference between the high level duration of the maximum phase and the high level duration of the middle 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 middle phase is greater than or equal to the minimum sampling duration;

[0112] Among them, the maximum phase is the phase with the largest duty cycle in the three-phase line, the minimum phase is the phase with the smallest duty cycle in the three-phase line, and the middle phase is the phase with the middle duty cycle in the three-phase line.

[0113] It can be understood that when the difference between the high-level duration of the maximum phase and the high-level duration of the middle 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 middle phase is less than the minimum sampling duration, there are two phases in the three-phase duty cycle with large duty cycles; when the difference between the high-level duration of the maximum 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 high-level duration of the minimum phase are both less than the minimum sampling duration, there are two phases in the three-phase duty cycle with small duty cycles, and at this time, the two-phase current cannot be collected by phase shifting. Based on the method of the embodiment of the present application, it is not necessary to collect the two-phase current, but based on the collected bus current value (corresponding to one-phase current value) and the electrical angle of the motor rotor in the current PWM cycle, the three-phase current value of the current PWM cycle is reconstructed, thereby realizing the vector control of the motor.

[0114] It can be understood that when the difference between the high-level duration of the maximum phase and the high-level duration of the middle 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 middle phase is greater than or equal to the minimum sampling duration, the middle phase can be phase-shifted to sample two-phase currents within the PWM cycle to achieve reconstruction of the three-phase current. The three-phase current can also be reconstructed based on the method of the embodiment of the present application, and the embodiment of the present application is not limited to this.

[0115] The three-phase current reconstruction method of the embodiment of the present application is illustrated below with reference to an application example.

[0116] like Figure 7 As shown, the three-phase current reconstruction method may include:

[0117] Step 701, calculating the three-phase duty cycle and the size of the sampling window of the current PWM cycle.

[0118] Exemplarily, the three-phase duty cycle of the current PWM cycle may be calculated based on the three-phase current values ​​of the previous PWM cycle. For details, please refer to the above description, which will not be repeated here.

[0119] Here, the size of the sampling window is the minimum sampling time T that the non-zero voltage vector must last. min , T min =T d +T set +T AD , where T d Indicates the dead time of the upper and lower bridge arms, T set Indicates the time it takes for the bus current to build up, T AD Indicates the sampling conversion time.

[0120] Step 702, determine whether to enter the unobservable area, if so, execute step 704, and then execute step 705; if not, execute step 703, and then execute step 705.

[0121] 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; then, 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 whether the current PWM cycle enters the unobservable area.

[0122] Step 703: normal three-phase current reconstruction.

[0123] 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.

[0124] Step 704 : reconstruct the three-phase current values ​​of the current PWM cycle based on the bus current values ​​collected in the unobservable area of ​​the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle.

[0125] If it is determined that the current PWM cycle enters the unobservable area, the three-phase current values ​​of the current PWM cycle can be reconstructed based on the method of the embodiment of the present application. For details, please refer to the above description and will not be repeated here.

[0126] Step 705: motor vector calculation control.

[0127] The 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.

[0128] It can be understood that in this application example, when the voltage vector is in the overmodulation area, the three-phase current value of the current PWM cycle can be reconstructed based on the electrical angle of the motor rotor in the current PWM cycle while only collecting the current value of one phase. This can meet the demand for three-phase current reconstruction based on the bus current in the overmodulation area, and further increase the output torque of the motor and improve the power supply voltage utilization rate while keeping the bus voltage unchanged.

[0129] In order to implement the method of the embodiment of the present application, the embodiment of the present application also provides a three-phase current reconstruction device, which corresponds to the above-mentioned three-phase current reconstruction method, and each step in the above-mentioned three-phase current reconstruction method embodiment is also fully applicable to the embodiment of the three-phase current reconstruction device.

[0130] like Figure 8 As shown, the three-phase current reconstruction device includes: a duty cycle calculation module 801, a determination module 802 and a current reconstruction module 803.

[0131] The duty cycle calculation module 801 is used to calculate the three-phase duty cycle of the current PWM cycle based on the three-phase current values ​​of the previous PWM cycle;

[0132] The determination module 802 is used to determine whether the current PWM cycle enters the unobservable region based on the three-phase duty cycle;

[0133] The current reconstruction module 803 is used to reconstruct the three-phase current value of the current PWM cycle based on the bus current value collected in the unobservable area of ​​the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle;

[0134] The unobservable area refers to a bus current value corresponding to only one non-zero voltage vector that can be collected in the current PWM cycle.

[0135] In some embodiments, the determination module 802 is further configured to:

[0136] Make sure the motor is in constant torque control mode;

[0137] The electrical angle of the motor rotor in the current PWM cycle is determined based on the electrical angle of the motor rotor in the previous PWM cycle, the duration of the PWM cycle, and the electrical angular velocity of the motor rotor in the previous PWM cycle.

[0138] In some embodiments, the current reconstruction module 803 is specifically used to:

[0139] Determine the current vector amplitude of the current PWM cycle based on the bus current value and the electrical angle of the motor rotor of the current PWM cycle;

[0140] The phase current values ​​of the remaining two phases other than the bus current value are determined based on the current vector magnitude of the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle.

[0141] In some embodiments, the determining module 802 is specifically configured to:

[0142] Determine the high level duration of each phase line based on the three-phase duty cycle and the duration of the PWM cycle;

[0143] It is determined that the current PWM cycle enters the unobservable area 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.

[0144] In some implementation schemes, the determination module 802 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:

[0145] Determine that the difference between the high level duration of the maximum phase and the high level duration of the middle 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 middle phase is less than the minimum sampling duration;

[0146] Determine that the difference between the high level duration of the maximum 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 high level duration of the minimum phase are both less than the minimum sampling duration;

[0147] Determine that the difference between the high level duration of the maximum phase and the high level duration of the middle 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 middle phase is greater than or equal to the minimum sampling duration;

[0148] Among them, the maximum phase is the phase with the largest duty cycle in the three-phase circuit, the minimum phase is the phase with the smallest duty cycle in the three-phase circuit, and the middle phase is the phase with the middle duty cycle in the three-phase circuit.

[0149] In actual application, the duty cycle calculation module 801, the determination module 802 and the current reconstruction module 803 can be implemented by a processor of the three-phase current reconstruction device. Of course, the processor needs to run the computer program in the memory to realize its function.

[0150] It should be noted that: the three-phase current reconstruction device provided in the above embodiment only uses the division of the above program modules as an example when performing three-phase current reconstruction. In actual applications, the above processing can be assigned to different program modules as needed, 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 reconstruction device provided in the above embodiment and the three-phase current reconstruction method embodiment belong to the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0151] 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 also provides a three-phase current reconstruction device. Fig. 9 Only an exemplary structure of the three-phase current reconstruction device is shown, not all structures, and it can be implemented as needed. Fig. 9 Partial or complete structure shown.

[0152] like Fig. 9 As shown, the three-phase current reconstruction device 900 provided in the embodiment of the present application includes: at least one processor 901, a memory 902 and a user interface 903. The various components in the three-phase current reconstruction device 900 are coupled together through a bus system 904. It can be understood that the bus system 904 is used to realize the connection and communication between these components. In addition to the data bus, the bus system 904 also includes a power bus, a control bus and a status signal bus. However, for the sake of clarity, in Fig. 9 Various buses are labeled as bus system 904.

[0153] Exemplarily, the three-phase current reconstruction device 900 further includes: a bus current acquisition device, which is used to obtain a sampled value of the bus current and send the sampled value to the processor 901. For example, the bus current acquisition device can be as follows: Figure 1 The single resistor sampling circuit shown.

[0154] The user interface 903 may include a display, a keyboard, a mouse, a trackball, a click wheel, keys, buttons, a touch pad or a touch screen.

[0155] 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 used to operate on the three-phase current reconstruction device.

[0156] The three-phase current reconstruction method disclosed in the embodiment of the present application can be applied to the processor 901, or implemented by the processor 901. The processor 901 may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the three-phase current reconstruction method can be completed by the hardware integrated logic circuit in the processor 901 or the instructions in the form of software. The above-mentioned processor 901 can be a general-purpose processor, a digital signal processor (DSP, Digital Signal Processor), or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The processor 901 can implement or execute the various methods, steps and logic block diagrams disclosed in the embodiment of the present application. The general-purpose processor can be a microprocessor or any conventional processor, etc. In combination with the steps of the method disclosed in the embodiment of the present application, it can be directly embodied as a hardware decoding processor to execute, or it can be executed by a combination of hardware and software modules in the decoding processor. The software module can be located in a storage medium, which is located in the memory 902. The processor 901 reads the 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 its hardware.

[0157] In an exemplary embodiment, the three-phase current reconstruction device can be implemented by one or more application specific integrated circuits (ASIC), DSP, programmable logic device (PLD), complex programmable logic device (CPLD), field programmable gate array (FPGA), general processor, controller, microcontroller (MCU), microprocessor, or other electronic components to execute the aforementioned method.

[0158] It can be understood that the memory 902 can be a volatile memory or a non-volatile memory, and can also include both volatile and non-volatile memories. Among them, the non-volatile memory can 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, a magnetic surface memory, an optical disk, or a compact disc read-only memory (CD-ROM); the magnetic surface memory can be a disk memory or a tape memory. The volatile memory can be a random access memory (RAM), which is used as an external cache. By way of example 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), synchronous link dynamic random access memory (SLDRAM, SyncLink Dynamic Random Access Memory), and direct RAM 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.

[0159] In an exemplary embodiment, the present application also provides a storage medium, namely a computer storage medium, which may be a computer-readable storage medium, for example, a memory 902 storing a computer program, and the computer program may be executed by a processor 901 of a three-phase current reconstruction device to complete the steps described in the method of the present application embodiment. The computer-readable storage medium may be a memory such as a ROM, a PROM, an EPROM, an EEPROM, a Flash Memory, a magnetic surface memory, an optical disk, or a CD-ROM.

[0160] It should be noted that: "first", "second", etc. are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0161] In addition, the technical solutions described in the embodiments of the present application can be combined arbitrarily without conflict.

[0162] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A three-phase current reconstruction method, It is characterized in that include: Calculate the three-phase duty cycle of the current PWM cycle based on the three-phase current values ​​of the previous PWM cycle; Determining that the current PWM cycle enters an unobservable region based on the three-phase duty cycle; Reconstructing the three-phase current values ​​of the current PWM cycle based on the bus current value collected in the unobservable area during the current PWM cycle and the electrical angle of the motor rotor during the current PWM cycle; The unobservable area refers to the bus current value corresponding to only one non-zero voltage vector that can be collected in the current PWM cycle; The reconstructing the three-phase current value of the current PWM cycle based on the bus current value collected in the unobservable area of ​​the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle includes: Determine the current vector amplitude of the current PWM cycle based on the bus current value and the electrical angle of the motor rotor of the current PWM cycle; The phase current values ​​of the remaining two phases other than the bus current value are determined based on the current vector magnitude of the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle.

2. The method according to claim 1, It is characterized in that Before reconstructing the three-phase current value of the current PWM cycle based on the bus current value collected in the unobservable area of ​​the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle, the method further includes: Make sure the motor is in constant torque control mode; The electrical angle of the motor rotor in the current PWM cycle is determined based on the electrical angle of the motor rotor in the previous PWM cycle, the duration of the PWM cycle, and the electrical angular velocity of the motor rotor in the previous PWM cycle.

3. The method according to claim 1, It is characterized in that The determining that the current PWM cycle enters the 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; It is determined that the current PWM cycle enters the unobservable area 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.

4. The method according to claim 3, It is characterized in that The determining that the current PWM cycle enters the unobservable area 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: Determine that the difference between the high level duration of the maximum phase and the high level duration of the middle 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 middle phase is less than the minimum sampling duration; Determine that the difference between the high level duration of the maximum 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 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 maximum phase and the high level duration of the middle 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 middle phase is greater than or equal to the minimum sampling duration; Among them, the maximum phase is the phase with the largest duty cycle in the three-phase circuit, the minimum phase is the phase with the smallest duty cycle in the three-phase circuit, and the middle phase is the phase with the middle duty cycle in the three-phase circuit.

5. A three-phase current reconstruction device, It is characterized in that include: A duty cycle calculation module, used to calculate the three-phase duty cycle of the current PWM cycle based on the three-phase current values ​​of the previous PWM cycle; A determination module, configured to determine whether the current PWM cycle enters an unobservable region based on the three-phase duty cycle; A current reconstruction module, used to reconstruct the three-phase current value of the current PWM cycle based on the bus current value collected in the unobservable area of ​​the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle; The unobservable area refers to the bus current value corresponding to only one non-zero voltage vector that can be collected in the current PWM cycle; The current reconstruction module is specifically used for: Determine the current vector amplitude of the current PWM cycle based on the bus current value and the electrical angle of the motor rotor of the current PWM cycle; The phase current values ​​of the remaining two phases other than the bus current value are determined based on the current vector magnitude of the current PWM cycle and the electrical angle of the motor rotor of the current PWM cycle.

6. The three-phase current reconstruction device according to claim 5, It is characterized in that The determining module is also used for: Make sure the motor is in constant torque control mode; The electrical angle of the motor rotor in the current PWM cycle is determined based on the electrical angle of the motor rotor in the previous PWM cycle, the duration of the PWM cycle, and the electrical angular velocity of the motor rotor in the previous PWM cycle.

7. The three-phase current reconstruction device according to claim 5, It is characterized in that The determination module is specifically used for: Determine 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 the unobservable area 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.

8. The three-phase current reconstruction device according to claim 7, It is characterized in that The determining module determines that the current PWM cycle enters the unobservable area 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 middle 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 middle phase is less than the minimum sampling duration; Determine that the difference between the high level duration of the maximum 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 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 maximum phase and the high level duration of the middle 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 middle phase is greater than or equal to the minimum sampling duration; Among them, the maximum phase is the phase with the largest duty cycle in the three-phase circuit, the minimum phase is the phase with the smallest duty cycle in the three-phase circuit, and the middle phase is the phase with the middle duty cycle in the three-phase circuit.

9. A three-phase current reconstruction device, It is characterized in that include: A processor and a memory for storing a computer program that can be executed on the processor, wherein: The processor is used to execute the steps of the method according to any one of claims 1 to 4 when running a computer program.

10. The three-phase current reconstruction device according to claim 9, It is characterized in that Also includes: The bus current acquisition device is used to obtain the sampled value of the bus current and send the sampled value to the processor.

11. A storage medium having a computer program stored thereon, It is characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 4 are implemented.

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