Motor, phase current determination method and device thereof, storage medium and program product

Abstract

The invention discloses a motor and a phase current determination method and device thereof, a storage medium and a computer program product, and the method comprises the steps: determining a reference voltage vector of the motor according to the operation parameters of the motor; according to the reference voltage vector of the motor, a complementary effective voltage vector is inserted in SVPWM modulation of the motor; within the action time of the inserted complementary effective voltage vector, currents, detected by a single current sensor, of the direct-current bus are obtained doubly and recorded as first currents and second currents; and based on the first current and the second current, correcting and reconstructing the sampling value of the first phase current and the sampling value of the second phase current to obtain the sampling value of the third phase current of the motor so as to determine the phase current of the motor. According to the scheme, the complementary effective voltage vector is inserted in the SVPWM modulation, and dynamic double sampling is performed on the direct current bus current, so that error compensation of two-phase current sampling values is realized, and the accuracy of third-phase current reconstruction is improved.

Description

Technical Field

[0001] The present invention belongs to the field of power electronics technology, and specifically relates to a method, device, motor, storage medium and computer program product for determining the phase current of a motor, and more particularly to a method, device, motor, storage medium and computer program product for DC bus voltage and current sampling and error compensation based on self-correction of zero drift error of a DC bus single current sensor with complementary effective voltage vector. Background Art

[0002] In power electronics systems, inverters (such as three-phase two-level inverters) are widely used in motor drive, power conversion and other fields. In order to achieve precise control of the motor, it is necessary to accurately measure the three-phase current output by the inverter. In three-phase two-level inverters, DC bus single current sensors (SCS) are widely used to reconstruct the phase current of the motor. In addition, in the process of reconstructing the phase current, operational amplifiers and voltage reference chips in the inverter hardware circuit are required. However, due to the zero drift phenomenon of current sensors, operational amplifiers and voltage reference chips, errors occur in current sampling, and the accuracy of current reconstruction is affected by the error magnification effect.

[0003] The above contents are only used to assist in understanding the technical solution of the present invention and do not constitute an admission that the above contents are prior art. Summary of the invention

[0004] The purpose of the present invention is to provide a method, device, motor, storage medium and computer program product for determining the phase current of a motor, so as to solve the problem that in the process of reconstructing the phase current of the motor, the current sampling error occurs due to the zero drift phenomenon of the current sensor, operational amplifier and voltage reference chip, thereby affecting the accuracy of the current reconstruction. By inserting a complementary effective voltage vector in SVPWM modulation and dynamically double sampling the DC bus current, the error compensation of the two-phase current sampling values ​​is realized, and the accuracy of the reconstruction of the third-phase current is improved.

[0005] The present invention provides a method for determining the phase current of a motor, wherein a power supply control end of the motor has a direct current bus; a single current sensor is arranged at the direct current bus for detecting the current of the direct current bus; the method for determining the phase current of the motor comprises: when the motor is running, obtaining the operation parameters of the motor and obtaining the phase current parameters of the motor; wherein the phase current parameters of the motor comprise: a sampling value of a first phase current among three-phase currents of the motor and a sampling value of a second phase current among three-phase currents of the motor; determining a reference voltage vector of the motor according to the operation parameters of the motor; inserting a complementary effective voltage vector into the SVPWM modulation of the motor according to the reference voltage vector of the motor; obtaining the current of the direct current bus detected by the single current sensor twice within the time when the inserted complementary effective voltage vector acts, and recording them as a first current and a second current; based on the first current and the second current, correcting and reconstructing the sampling value of the first phase current and the sampling value of the second phase current to obtain the sampling value of the third phase current of the motor, thereby determining the phase current of the motor.

[0006] In some embodiments, according to the reference voltage vector of the motor, a complementary effective voltage vector is inserted in the SVPWM modulation of the motor, including: according to the sector position of the reference voltage vector of the motor in the basic voltage vector diagram of the SVPWM modulation, four effective voltage vectors of the sector position are selected from the basic voltage vector; a pair of complementary effective voltage vectors are selected from the four effective voltage vectors, recorded as complementary effective voltage vectors; and the complementary effective voltage vector is inserted in the self-calibration area of ​​the reference voltage vector of the motor, so as to determine the action time of the inserted complementary effective voltage vector as the time of the current observation time window of the motor.

[0007] In some embodiments, within the time when the inserted complementary effective voltage vector acts, the current of the DC bus detected by the single current sensor is obtained twice, recorded as a first current and a second current, including: obtaining a minimum sampling time determined in advance according to the hardware performance of the motor; within the time when the inserted complementary effective voltage vector acts, the current of the DC bus detected by the single current sensor is obtained twice according to the minimum sampling time, recorded as a first current and a second current.

[0008] In some embodiments, based on the first current and the second current, the sampling value of the first phase current and the sampling value of the second phase current are corrected and reconstructed to obtain the sampling value of the third phase current of the motor, thereby determining the phase current of the motor, including: based on the first current and the second current, the sampling value of the first phase current and the sampling value of the second phase current are corrected to obtain a first corrected current and a second corrected current, which are recorded as the corrected value of the first phase current of the motor and the corrected value of the second phase current of the motor; current is reconstructed according to the corrected value of the first phase current of the motor and the corrected value of the second phase current of the motor to obtain the sampling value of the third phase current of the motor.

[0009] In some embodiments, based on the first current and the second current, the sampling value of the first phase current and the sampling value of the second phase current are corrected to obtain a first corrected current and a second corrected current, including: taking the sum of the first current and the second current as the zero-point drift; taking the difference between the sampling value of the first phase current and the zero-point drift as the first correction current; and taking the difference between the sampling value of the second phase current and the zero-point drift as the second correction current.

[0010] In some embodiments, current reconstruction is performed according to the correction value of the first phase current of the motor and the correction value of the second phase current of the motor to obtain a sampling value of the third phase current of the motor, including: based on Kirchhoff's current law, determining the relationship between the correction value of the first phase current of the motor, the correction value of the second phase current of the motor, and the sampling value of the third phase current of the motor, and calculating the sampling value of the third phase current of the motor according to the relationship; wherein the calculated sampling value of the third phase current of the motor includes: the average value of the sampling values ​​of the third phase current of the motor calculated more than twice.

[0011] Matching the above method, the present invention provides a device for determining the phase current of a motor on the other hand, wherein the power supply control end of the motor has a DC bus; a single current sensor is arranged at the DC bus for detecting the current of the DC bus; the method for determining the phase current of the motor comprises: an acquisition unit configured to acquire the operating parameters of the motor and the phase current parameters of the motor when the motor is running; wherein the phase current parameters of the motor comprise: a sampling value of the first phase current of the three-phase current of the motor, and a sampling value of the second phase current of the three-phase current of the motor; a control unit configured to determine the phase current of the motor according to the operating parameters of the motor The reference voltage vector of the motor; the control unit is further configured to insert a complementary effective voltage vector in the SVPWM modulation of the motor according to the reference voltage vector of the motor; the acquisition unit is further configured to acquire the current of the DC bus detected by the single current sensor twice within the time when the inserted complementary effective voltage vector acts, recorded as the first current and the second current; the control unit is further configured to correct and reconstruct the sampling value of the first phase current and the sampling value of the second phase current based on the first current and the second current, obtain the sampling value of the third phase current of the motor, and determine the phase current of the motor.

[0012] In some embodiments, the control unit inserts a complementary effective voltage vector in the SVPWM modulation of the motor according to the reference voltage vector of the motor, including: selecting four effective voltage vectors at the sector position from the basic voltage vector according to the sector position of the reference voltage vector of the motor in the basic voltage vector diagram of the SVPWM modulation; selecting a pair of complementary effective voltage vectors from the four effective voltage vectors, recorded as complementary effective voltage vectors; and inserting the complementary effective voltage vector within the self-calibration area of ​​the reference voltage vector of the motor, so as to determine the action time of the inserted complementary effective voltage vector as the time of the current observation time window of the motor.

[0013] In some embodiments, the acquisition unit acquires the current of the DC bus detected by the single current sensor twice within the time when the inserted complementary effective voltage vector acts, and records it as a first current and a second current, including: acquiring a minimum sampling time determined in advance according to the hardware performance of the motor; and acquiring the current of the DC bus detected by the single current sensor twice according to the minimum sampling time within the time when the inserted complementary effective voltage vector acts, and records it as a first current and a second current.

[0014] In some embodiments, the control unit, based on the first current and the second current, corrects and reconstructs the sampled value of the first phase current and the sampled value of the second phase current to obtain the sampled value of the third phase current of the motor, thereby determining the phase current of the motor, including: correcting the sampled value of the first phase current and the sampled value of the second phase current based on the first current and the second current to obtain a first corrected current and a second corrected current, recorded as the corrected value of the first phase current of the motor and the corrected value of the second phase current of the motor; reconstructing the current according to the corrected value of the first phase current of the motor and the corrected value of the second phase current of the motor to obtain the sampled value of the third phase current of the motor.

[0015] In some embodiments, the control unit, based on the first current and the second current, corrects the sampling value of the first phase current and the sampling value of the second phase current to obtain a first corrected current and a second corrected current, including: taking the sum of the first current and the second current as the zero-point drift; taking the difference between the sampling value of the first phase current and the zero-point drift as the first correction current; and taking the difference between the sampling value of the second phase current and the zero-point drift as the second correction current.

[0016] In some embodiments, the control unit performs current reconstruction according to the correction value of the first phase current of the motor and the correction value of the second phase current of the motor to obtain the sampling value of the third phase current of the motor, including: determining the relationship between the correction value of the first phase current of the motor, the correction value of the second phase current of the motor, and the sampling value of the third phase current of the motor based on Kirchhoff's current law, and calculating the sampling value of the third phase current of the motor according to the relationship; wherein the sampling value of the third phase current of the motor calculated by the control unit includes: the average value of the sampling values ​​of the third phase current of the motor calculated more than twice.

[0017] Matching the above-mentioned device, the present invention further provides a motor on the other hand, including: the phase current determination device of the motor mentioned above.

[0018] In accordance with the above method, the present invention provides a storage medium on the other hand, wherein the storage medium includes a stored program, wherein when the program is running, the device where the storage medium is located is controlled to execute the steps of the above-mentioned method for determining the phase current of the motor.

[0019] Matching the above method, the present invention further provides a computer program product on the other hand, including a computer program, which implements the steps of the above-mentioned method for determining the phase current of the motor when executed by a processor.

[0020] Therefore, the scheme of the present invention samples the three-phase current provided by the power supply control end of the motor (such as the three-phase current output by the motor controller or the inverter in the frequency converter), and determines the reference voltage vector (such as the reference voltage vector Vref) of the motor according to the operating parameters of the motor when the motor is running; selects a pair of complementary effective voltage vectors in the corresponding basic voltage vector according to the sector position of the reference voltage vector of the motor (that is, the position of the reference voltage vector Vref in the basic voltage vector diagram of SVPWM); inserts a complementary effective voltage vector in the self-calibration area of ​​the reference voltage vector of the machine to replace the zero vector in the SVPWM modulation method; , determine the time of the current observation window (that is, the duration of the current observation window is greater than the minimum sampling time Tmin); within the current observation window, use the DC bus single current sensor to dynamically double sample the DC bus current according to the minimum sampling time to obtain two sampling currents; correct the two sampling currents to obtain the two-phase current; reconstruct the two-phase current to obtain the third-phase current, so as to determine the three-phase current of the motor; thus, by inserting the complementary effective voltage vector in the SVPWM modulation and dynamically double sampling the DC bus current, the error compensation of the two-phase current sampling value is realized, and the accuracy of the reconstruction of the third-phase current is improved.

[0021] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic flow chart of an embodiment of a method for determining a phase current of a motor of the present invention;

[0024] Figure 2 A schematic diagram of a flow chart of an embodiment of inserting a complementary effective voltage vector in a method of the present invention;

[0025] Figure 3 A schematic diagram of a flow chart of an embodiment of obtaining the current of the DC bus detected by the single current sensor twice in the method of the present invention;

[0026] Figure 4 A flow chart of an embodiment of the method of the present invention for correcting and reconstructing the sampled value of the first phase current and the sampled value of the second phase current based on the first current and the second current to obtain the sampled value of the third phase current of the motor;

[0027] Figure 5A schematic diagram of a flow chart of an embodiment of correcting a sampled value of the first phase current and a sampled value of the second phase current based on the first current and the second current in the method of the present invention;

[0028] Figure 6 It is a structural schematic diagram of an embodiment of a device for determining phase current of a motor of the present invention;

[0029] Figure 7 It is a structural schematic diagram of a three-phase bridge inverter circuit;

[0030] Figure 8 It is a schematic diagram of the basic voltage vector synthesis modulation area;

[0031] Fig. 9 A schematic diagram for inserting complementary effective voltage vectors;

[0032] Fig.10 The present invention is a flow chart of a DC bus voltage and current sampling and error compensation method based on complementary effective voltage vector and self-correction of zero drift error of a DC bus single current sensor.

[0033] In conjunction with the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows:

[0034] 102 - acquisition unit; 104 - control unit. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0036] Considering that in the process of reconstructing the phase current of the motor, the current sampling error occurs due to the zero drift phenomenon of the current sensor, operational amplifier and voltage reference chip, which in turn affects the accuracy of the current reconstruction. Although the method of using multiple current sensors in related schemes can improve the accuracy, it increases the complexity and cost of the system.

[0037] Some schemes use a three-resistance current sampling method for a frequency converter based on current prediction. In each pulse width modulation (PWM) cycle, after current closed-loop PID (i.e., proportional-integral-differential) control and space vector pulse width modulation (SVGEN) modulation, the three-phase PWM comparison values ​​T1, T2, and T3 of A, B, and C are obtained. The size of T1, T2, and T3 is compared with the shortest time Tmin required for complete sampling in real time, and different current acquisition methods are adopted according to different size relationships. The problem that the zero voltage vector duration is insufficient under high modulation ratios in the traditional three-resistance sampling technology of three-phase frequency converters, resulting in the inability to accurately sample the three-phase current, can be solved. The current closed-loop control of a wide area under three-resistance sampling can be realized, the modulation ratio is improved, and the motor load capacity is increased. The cost is low, the sampling is simple, and it is reliable. Although this scheme solves the problem of insufficient zero voltage vector duration under high modulation ratios in the three-resistance sampling technology, it requires multiple resistors, which increases the hardware cost and complexity.

[0038] Some solutions also provide a new hybrid space vector pulse width modulation (SVPWM) method for optimizing the torque pulsation of a permanent magnet synchronous motor (PMSM) powered by a four-switch inverter, which alternates between two different modulation methods in different sectors and introduces a new method for deriving the effective value of torque pulsation, so that the sector division is not affected by the motor parameters. At the same time, a novel sector division method is proposed to make the sector division simpler. This new hybrid SVPWM method improves the original modulation method, which can effectively reduce the computing intensity of the digital signal processor and has engineering use value; and when the motor parameters change, the PMSM torque pulsation can still be effectively reduced. Although the above patent proposes a new sector division method, the introduction of two different modulation methods may increase the complexity of the system, especially in software implementation and hardware design. This may lead to an extension of the development cycle and an increase in costs. Due to the use of two different modulation methods, system debugging may become more difficult. In particular, in practical applications, it is necessary to ensure smooth switching between the two modulation methods to avoid performance degradation or instability. However, the introduction of two different modulation methods increases the complexity of the system, which may lead to an extension of the development cycle and an increase in costs, as well as increased difficulty in system debugging.

[0039] Other solutions propose a three-level inverter indirect vector control system based on simplified SVPWM, which uses the simplified SVPWM algorithm under the 60° coordinate system to simplify the vector control process, reduce trigonometric function operations and sector judgment, and improve real-time control capabilities. This patent requires that the basic space regular hexagonal vector diagram of the three-level inverter be replaced by a non-orthogonal 60° coordinate system instead of the traditional orthogonal coordinate system, and the basic space vector diagram be normalized. Using a 60° coordinate system instead of a traditional orthogonal coordinate system may result in a decrease in the accuracy of vector control. Although the calculation process is simplified, it may not be able to fully and accurately represent all working states, especially when the reference voltage is in an unobservable area such as overmodulation. This patent solves the problem of inaccurate sampling in the unobservable area of ​​the traditional SVPWM method by inserting a complementary effective voltage vector instead of a zero vector. The use of complementary effective voltage vectors ensures that the current observation window duration is greater than the minimum sampling time, thereby improving the accuracy of current sampling. However, using a 60° coordinate system instead of a traditional orthogonal coordinate system may result in a decrease in the accuracy of vector control, especially when the reference voltage is in an unobservable area such as overmodulation.

[0040] It can be seen that although the method of using multiple current sensors in related schemes can improve the measurement accuracy, it increases the complexity and cost of the system. Therefore, the single current sensor (SCS) phase current reconstruction technology has become a research hotspot. However, the zero drift phenomenon of SCS will cause current sampling errors, which in turn affects the accuracy of phase current reconstruction.

[0041] Therefore, an effective self-correction strategy is needed to solve the above problems. Therefore, the solution of the present invention proposes a method for determining the phase current of a motor, specifically a DC bus voltage and current sampling and error compensation method based on the self-correction of the zero drift error of a DC bus single current sensor of a complementary effective voltage vector, adopting a self-correction strategy for the zero drift error of a DC bus single current sensor, especially a self-correction strategy for the zero drift error of a DC bus single current sensor in a three-phase two-level inverter, by inserting a complementary effective voltage vector and a dynamic current dual current sampling technology, the self-detection and self-correction of the current zero drift amount are realized, and the accuracy of phase current reconstruction is improved.

[0042] According to an embodiment of the present invention, a method for determining the phase current of a motor is provided. Figure 1 The flow chart of an embodiment of the method of the present invention is shown in FIG. The power supply control end of the motor (such as a frequency converter or a motor controller) has a DC bus; a single current sensor is arranged at the DC bus to detect the current of the DC bus. Figure 7 It is a structural diagram of a three-phase bridge inverter circuit. Figure 7As shown, the three-phase bridge inverter circuit is arranged between the DC bus and the motor (PMSM). The three-phase bridge inverter circuit includes: switch tube M1, switch tube M2, switch tube M3, switch tube M4, switch tube M5, and switch tube M6; each switch tube can be an insulated gate bipolar transistor (IGBT), the gate of the IGBT serves as the control end of each switch tube, the collector of the IGBT serves as the first connection end of each switch tube, and the emitter of the IGBT serves as the second connection end of each switch tube. The positive end of the bus voltage V of the DC bus is respectively connected to the first connection end of the switch tube M1, the first connection end of the switch tube M2, and the first connection end of the switch tube M3; the negative end of the bus voltage V of the DC bus is respectively connected to the second connection end of the switch tube M4, the second connection end of the switch tube M5, and the second connection end of the switch tube M6; the second connection end of the switch tube M1 is connected to the first connection end of the switch tube M4, the second connection end of the switch tube M2 is connected to the first connection end of the switch tube M5, and the second connection end of the switch tube M3 is connected to the first connection end of the switch tube M6. The switch tube M1 and the switch tube M4 constitute the first phase bridge arm of the three-phase bridge arm, and the common end of the switch tube M1 and the switch tube M4 is connected to the first phase winding of the three-phase winding of the motor; the switch tube M2 and the switch tube M5 constitute the second phase bridge arm of the three-phase bridge arm, and the common end of the switch tube M2 and the switch tube M5 is connected to the second phase winding of the three-phase winding of the motor; the switch tube M3 and the switch tube M6 constitute the third phase bridge arm of the three-phase bridge arm, and the common end of the switch tube M3 and the switch tube M6 is connected to the third phase winding of the three-phase winding of the motor.

[0043] In the scheme of the present invention, Figure 1 As shown, the method for determining the phase current of the motor includes: steps S110 to S150.

[0044] At step S110, when the motor is running, the running parameters of the motor are obtained, and the phase current parameters of the motor are obtained; wherein the phase current parameters of the motor include: the sampling value of the first phase current of the three-phase current of the motor, and the sampling value of the second phase current of the three-phase current of the motor. The phase current parameters of the motor can be obtained by sampling from the output end of the power supply control end of the motor (such as the output end of the inverter in the frequency converter or motor controller).

[0045] In step S120 , a reference voltage vector of the motor is determined according to the operating parameters of the motor. Fig.10 The figure is a flow chart of DC bus voltage and current sampling and error compensation based on the self-correction of zero drift error of DC bus single current sensor with complementary effective voltage vector. Fig.10 As shown, the voltage and current sampling and error compensation method of the DC bus includes:

[0046] Step 1: Calculate the reference voltage vector Vref according to the running state of the motor, and then execute step 2.

[0047] In step 1, the reference voltage vector Vref is calculated according to the running state of the motor, which specifically includes:

[0048] Step 11, obtaining the operating parameters of the motor, the obtained operating parameters of the motor include the motor speed, load current, temperature, etc., and then executing step 12.

[0049] Among them, during the operation of the motor, the load current refers to the actual current drawn from the power supply when the motor drives the load. The load current reflects the actual working intensity of the motor, that is, the work done by the motor to overcome the load resistance; the load current will change with the change of the load. When the load increases, the motor needs a greater torque to drive the load, so the load current will also increase accordingly; conversely, when the load decreases, the load current will also decrease. Phase current: For a three-phase AC motor, the phase current refers to the current flowing through each phase winding; in a balanced three-phase system, the three-phase currents are equal in magnitude and 120 degrees apart in phase; the phase current is mainly used to analyze the internal working state of the motor, such as judging whether the motor is in normal operation and whether there is a fault.

[0050] Step 12: determine a control target, such as maintaining stable operation of the motor, optimizing efficiency, etc., and then execute step 13.

[0051] Step 13, calculate the reference voltage vector Vref: calculate the required reference voltage vector Vref according to the mathematical model of the motor and the control target. For example, the reference voltage vector Vref can be calculated using a vector control algorithm based on the voltage equation, flux equation and torque equation in the mathematical model of the motor.

[0052] At step S130 , a complementary effective voltage vector is inserted into the SVPWM modulation of the motor according to the reference voltage vector of the motor.

[0053] In step S140, within the time when the inserted complementary effective voltage vector acts, the current of the DC bus detected by the single current sensor is acquired twice and recorded as a first current and a second current.

[0054] In step S150, based on the first current and the second current, the sampled value of the first phase current and the sampled value of the second phase current are corrected and reconstructed to obtain the sampled value of the third phase current of the motor, thereby determining the phase current of the motor.

[0055] The scheme of the present invention proposes a DC bus voltage and current sampling and error compensation scheme for self-correction of zero drift error of a DC bus single current sensor based on complementary effective voltage vector. By inserting complementary effective voltage vector and dynamic current dual current sampling technology, self-detection and self-correction of current zero drift are realized, and the accuracy of phase current reconstruction is improved. The scheme improves the accuracy of third-phase current reconstruction, reduces the influence of error magnification effect, and maintains the simplicity and economy of the system. It shows good performance in different modulation areas and working conditions, and can meet the performance requirements of motor control systems.

[0056] In some implementations, the specific process of inserting a complementary effective voltage vector in the SVPWM modulation of the motor according to the reference voltage vector of the motor in step S130 is described in the following exemplary embodiments.

[0057] Combine the following Figure 2 The flowchart of an embodiment of inserting a complementary effective voltage vector in the method of the present invention is shown, which further illustrates the specific process of inserting a complementary effective voltage vector in step S130, including: steps S210 to S230.

[0058] Step S210 , according to the sector position of the reference voltage vector of the motor in the basic voltage vector diagram of SVPWM modulation, four effective voltage vectors at the sector position are selected from the basic voltage vector.

[0059] In step S220 , a pair of complementary effective voltage vectors are selected from the four effective voltage vectors and recorded as complementary effective voltage vectors.

[0060] Step S230, inserting the complementary effective voltage vector in the self-calibration region of the reference voltage vector of the motor, so as to determine the time when the inserted complementary effective voltage vector acts as the time of the current observation time window of the motor.

[0061] Figure 8 The schematic diagram of the basic voltage vector synthesis modulation area. The inverter control adopts space vector pulse width modulation (SVPWM) technology. Through the linear combination of the basic voltage space vector, the stator flux inside the motor is made into a vector circle, thus ensuring the stable electromagnetic torque output by the motor. Figure 8 In the figure, the self-calibration area includes: low modulation area, overmodulation area and sector boundary; the sectors include: sector I, sector II, sector III, sector IV, sector V, sector VI; the unobservable area includes: the area within the dotted line; the basic voltage vectors include: vector V0, vector V1, vector V2, vector V3, vector V4, vector V5, vector V6, vector V7, and vector V0 and vector V7 are located in the center circle ( Figure 8 not shown).

[0062] like Figure 8 As shown, corresponding to the switching state of the upper bridge arm (000, 001, 010, 011, 100, 101, 110, 111), there are 8 basic voltage space vectors of the motor: V0, V1, V2, V3, V4, V5, V6, V7. Corresponding to the switching state 000 of the upper bridge arm, the basic voltage space vector of the motor is V0; corresponding to the switching state 001 of the upper bridge arm, the basic voltage space vector of the motor is V1; corresponding to the switching state 010 of the upper bridge arm, the basic voltage space vector of the motor is V2; corresponding to the switching state 011 of the upper bridge arm, the basic voltage space vector of the motor is V3; corresponding to the switching state 100 of the upper bridge arm, the basic voltage space vector of the motor is V4; corresponding to the switching state 101 of the upper bridge arm, the basic voltage space vector of the motor is V5; corresponding to the switching state 110 of the upper bridge arm, the basic voltage space vector of the motor is V6; corresponding to the switching state 111 of the upper bridge arm, the basic voltage space vector of the motor is V7. Among them, V1, V2, V3, V4, V5, V6 are valid vectors, V0 and V7 are zero vectors, corresponding to Figure 8 The most central circle area (in Figure 8 The reference voltage vector Vref can be mapped to Figure 8 In the figure, Vref takes the center as the origin, starts from V1, and rotates counterclockwise. The rotation trajectory is Figure 8 For the circle in the figure, the Vref amplitude will not exceed the radius of the circle.

[0063] Fig. 9 Schematic diagram for inserting complementary effective voltage vectors. Fig. 9 In , the solid line is the basic voltage vector, the dashed line is the sector boundary, and the red line is the component that decomposes the reference voltage into the basic voltage vector. Fig. 9 In the figure, Vref is decomposed and synthesized by the basic voltage vectors in the figure; that is, the reference voltage vector Vref obtained by the volt-second balance theory can be synthesized by 4 basic voltage vectors, namely:

[0064] Vref(cosθ+jsinθ)Ts=V1T1+V2T2+V3T0 / 2+V6T0 / 2.

[0065] Among them, θ represents the rotation angle of Vref in the space vector plane, Ts represents the carrier period of the modulation system, T1 represents the duration of the V1 voltage vector, T2 represents the duration of the V2 voltage vector, and T0 represents the duration of the voltage vectors V3 and V6.

[0066] See also Figure 7 , Figure 8 and Fig. 9In the example shown, the motor control algorithm calculates vd and vq, and then calculates Vref. Vref has magnitude and direction. According to the magnitude and direction of Vref, it is determined that Vref is Figure 8 If it is in sector I, then Fig. 9 As shown, Vref is decomposed into the basic voltage vector Vref(cosθ+jsinθ)Ts=V1T1+V2T2+V3T0 / 2+V6T0 / 2. Among them, V1, V2, V3, V6 are actually Figure 7 The switch state of the upper bridge arm of the three-phase inverter circuit indicates that the upper bridge arm is turned on, and T1, T2, T3, and T6 are the turn-on times. Thus, the hardware circuit is controlled by software algorithms to achieve the generation and control of the reference voltage, and further control the operation of the motor.

[0067] In the SVPWM modulation method, the basic voltage vector action time of each sector determines the duration of the current observation window. In order to ensure accurate current sampling, it is necessary to analyze the duration of the current observation window of each sector. Specifically, Figure 8 and Fig. 9 As shown, when the reference voltage vector Vref is located in an unobservable area (ie, a sector boundary or an overmodulation area), the action time of the effective voltage vector may be less than the minimum sampling time Tmin, resulting in the inability to accurately collect the current.

[0068] In order to extend the time of the current observation window, the solution of the present invention proposes to insert a complementary effective voltage vector in the SVPWM modulation method, replacing the insertion of a zero vector in the SVPWM modulation method in the related solution. In the solution of the present invention, the use of the complementary effective voltage vector: by inserting the complementary effective voltage vector instead of the zero vector, the problem of inaccurate sampling in the unobservable area of ​​the SVPWM method in the related solution is solved, and the use of the complementary effective voltage vector ensures that the current observation window duration is greater than the minimum sampling time, thereby improving the accuracy of current sampling.

[0069] like Fig.10 As shown, the voltage and current sampling and error compensation method of the DC bus also includes:

[0070] Step 2: Select a suitable basic voltage vector according to the position of the reference voltage vector Vref, and then execute step 3.

[0071] In step 2, according to the position of the reference voltage vector Vref, a suitable basic voltage vector is selected, which specifically includes:

[0072] Step 21, determine the position of the reference voltage vector Vref, and then execute step 22. In step 21, the reference voltage vector Vref is projected onto the basic voltage vector diagram of SVPWM, such as Figure 8As shown in FIG. 1 , the sector where the reference voltage vector Vref is located is determined. When the reference voltage vector Vref is in the first sector, the projection of Vref is as follows: Fig. 9 shown.

[0073] Step 22, select a basic voltage vector: select a suitable basic voltage vector according to the position of the reference voltage vector Vref in the basic voltage vector diagram of SVPWM, and then execute step 23.

[0074] like Figure 8 As shown, the basic voltage vector diagram of SVPWM is divided into six sectors, and each sector corresponds to a group of basic voltage vectors. For example: if the reference voltage vector Vref is located in the first sector (i.e., sector I), vector V6, vector V1, vector V2, and vector V3 are selected as basic voltage vectors. If the reference voltage vector Vref is located in the second sector (i.e., sector II), vector V1, vector V2, vector V3, and vector V4 are selected as basic voltage vectors. If the reference voltage vector Vref is located in the third sector (i.e., sector III), vector V2, vector V3, vector V4, and vector V5 are selected as basic voltage vectors. If the reference voltage vector Vref is located in the fourth sector (i.e., sector IV), vector V3, vector V4, vector V5, and vector V6 are selected as basic voltage vectors. If the reference voltage vector Vref is located in the fifth sector (i.e., sector V), vector V4, vector V5, vector V6, and vector V1 are selected as basic voltage vectors. If the reference voltage vector Vref is located in the sixth sector (ie, sector VI), vector V5, vector V6, vector V1, and vector V2 are selected as basic voltage vectors.

[0075] Step 23, calculating the action time: according to the position of the reference voltage vector Vref and the modulation algorithm of SVPWM, calculating the action time of each basic voltage vector in the selected basic voltage vectors.

[0076] Step 3: inserting a complementary effective voltage vector in the selected basic voltage vector into the self-correction region of the reference voltage vector Vref, and then executing step 4.

[0077] In step 3, two adjacent effective voltage vectors (i.e., complementary effective voltage vectors) are used to replace the sporadic vectors (i.e., vector V0 and vector V7) to ensure that the duration of the current observation window is greater than the minimum sampling time Tmin. The duration of the current observation window is as follows: Figure 8 The time Ts is shown.

[0078] In step 3, a complementary effective voltage vector in the selected basic voltage vector is inserted into the self-correction region of the reference voltage vector Vref, specifically including:

[0079] Step 31, determine the self-correction region of the reference voltage vector Vref, and then execute step 32. Figure 8 As shown, the self-correction area of ​​the reference voltage vector Vref includes: a low modulation area, an overmodulation area, and a sector boundary. In the SVPWM modulation process, when the reference voltage vector Vref is located in an unobservable area (such as a sector boundary or an overmodulation area), the zero vector action time in the relevant scheme may be less than the minimum sampling time Tmin, so it is necessary to use two adjacent effective voltage vectors (i.e., complementary effective voltage vectors) to replace the sporadic vectors (i.e., vector V0 and vector V7) to ensure that the duration of the current observation window is greater than the minimum sampling time Tmin.

[0080] Step 32, in the self-correction region of the reference voltage vector Vref, select a complementary effective voltage vector, and then execute step 33. In step 32, in the self-correction region of the reference voltage vector Vref, select two adjacent effective voltage vectors to replace the zero vector (ie, vector V0 and vector V7).

[0081] For example: if the self-correction area of ​​the reference voltage vector Vref is in the first sector (i.e., sector I), then the complementary effective voltage vectors such as vector V6 and vector V3 are selected from the basic voltage vectors such as vector V6, vector V1, vector V2, and vector V3. If the self-correction area of ​​the reference voltage vector Vref is in the second sector (i.e., sector II), then the complementary effective voltage vectors such as vector V1 and vector V4 are selected from the basic voltage vectors such as vector V1, vector V2, vector V3, and vector V4. If the self-correction area of ​​the reference voltage vector Vref is in the third sector (i.e., sector III), then the complementary effective voltage vectors such as vector V2 and vector V5 are selected from the basic voltage vectors such as vector V2, vector V3, vector V4, and vector V5. If the self-correction area of ​​the reference voltage vector Vref is in the fourth sector (i.e., sector IV), then the complementary effective voltage vectors such as vector V3 and vector V6 are selected from the basic voltage vectors such as vector V3, vector V4, vector V5, and vector V6. If the self-correction region of the reference voltage vector Vref is in the fifth sector (i.e., sector V), then the complementary effective voltage vectors such as vector V4 and vector V1 are selected from the basic voltage vectors such as vector V4, vector V5, vector V6, and vector V1. If the self-correction region of the reference voltage vector Vref is in the sixth sector (i.e., sector VI), then the complementary effective voltage vectors such as vector V5 and vector V2 are selected from the basic voltage vectors such as vector V5, vector V6, vector V1, and vector V2.

[0082] Step 33, allocating the action time: dividing the action time T0 of the zero vector equally into two complementary effective voltage vectors. For example, if the self-correction region of the reference voltage vector Vref is in the first sector (i.e., sector I), then selecting the complementary effective voltage vectors such as vector V6 and vector V3 from the basic voltage vectors such as vector V6, vector V1, vector V2, and vector V3, and dividing the action time T0 of the zero vector equally into two complementary effective voltage vectors such as vector V6 and vector V3, as follows:

[0083] V0*T0=V3*T0 / 2+V6*T0 / 2 (2).

[0084] In the solution of the present invention, by inserting a complementary effective voltage vector in the selected basic voltage vector into the self-correction area of ​​the reference voltage vector Vref, the action time T0 of the zero vector can be equally divided into two complementary effective voltage vectors such as vector V6 and vector V3, ensuring that the duration of the current observation window is greater than the minimum sampling time Tmin, thereby improving the accuracy of current sampling.

[0085] Specifically, taking sector I as an example, in the self-correction region of the reference voltage vector Vref, the zero vectors V0 and V7 in the SVPWM switching sequence in the relevant scheme are replaced by two adjacent effective voltage vectors V3 and V6, as shown in FIG. Figure 8 As shown. In this way, the action time T0 of the zero vector is equally divided into two complementary effective voltage vectors, that is, formula (2).

[0086] In different sectors, the switching sequence for inserting complementary effective voltage vectors is shown in Table 1:

[0087] Table 1

[0088] Sector Effective vector Switching sequence Ⅰ V1, V2, V3, V6 V6,V1,V2,V3-V3,V2,V1,V6 Ⅱ V1, V2, V3, V4 V4,V3,V2,V1-V1,V2,V3,V4 Ⅲ V2, V3, V4, V5 V2,V3,V4,V5-V5,V4,V3,V2 Ⅳ V3, V4, V5, V6 V6,V5,V4,V3-V3,V4,V5,V6 Ⅴ V1, V4, V5, V6 V5,V4,V6,V1-V1,V6,V4,V5 Ⅵ V1, V2, V5, V6 V2,V1,V6,V5-V5,V6,V1,V2

[0089] For example, in Table 1, the switch sequence is V6, V1, V2, V3-V3, V2, V1, V6, which means that the switch status changes according to V6, V1, V2, V3 and then opens according to V3, V2, V1, V6.

[0090] In some embodiments, in step S140, within the time when the inserted complementary effective voltage vector acts, the current of the DC bus detected by the single current sensor is acquired twice, and recorded as the first current and the second current. For the specific process, see the following exemplary description.

[0091] Combine the following Figure 3The flowchart of an embodiment of the method of the present invention for obtaining the current of the DC bus detected by the single current sensor twice is shown, which further illustrates the specific process of obtaining the current of the DC bus detected by the single current sensor twice in step S140, including: step S310 to step S320.

[0092] Step S310, obtaining a minimum sampling time pre-determined according to the hardware performance of the motor.

[0093] Step S320, within the time when the inserted complementary effective voltage vector acts, the current of the DC bus detected by the single current sensor is acquired twice according to the minimum sampling time, and recorded as the first current and the second current; that is, within the time of the current observation time window of the motor, the current of the DC bus sampled twice by the single current sensor is acquired according to the predetermined minimum sampling time, and recorded as the first current and the second current. For example: within the time when the inserted complementary effective voltage vector acts, the current of the DC bus detected by the single current sensor according to the minimum sampling time is acquired for the first time, and recorded as the first current; and, still within the time when the inserted complementary effective voltage vector acts, the current of the DC bus detected by the single current sensor according to the minimum sampling time is acquired for the second time, and recorded as the second current. Wherein, the sum of the sampling time of the first current and the sampling time of the second current is less than the time when the inserted complementary effective voltage vector acts.

[0094] like Fig.10 As shown, the voltage and current sampling and error compensation method of the DC bus also includes: step 4, in the self-correction area of ​​the reference voltage vector Vref, after inserting the complementary effective voltage vector in the selected basic voltage vector, the DC bus current is double sampled based on the inserted complementary voltage vector to obtain the sampled currents I1 and I2, and then executing step 5.

[0095] In step 4, the DC bus current is double sampled based on the inserted complementary voltage vector to obtain the sampled currents I1 and I2. The specific sampling method is as follows:

[0096] Step 41, calculate the minimum sampling time Tmin: calculate the minimum sampling time Tmin according to the performance of the hardware device, and then execute step 42. For example: according to the performance of the hardware device, the minimum sampling time Tmin of the current sampling AD conversion chip used is 12ns.

[0097] Step 42, perform double current sampling on the DC bus current: within the inserted complementary voltage vector action time (such as time Ts), use a single current sensor and based on the minimum sampling time Tmin, perform two samplings on the DC bus current to obtain sampling currents I1 and I2.

[0098] In the solution of the present invention, the dynamic current double current sampling technology is used to realize the self-detection and self-correction of the current zero drift, thereby improving the accuracy of the reconstruction of the third phase current.

[0099] In some embodiments, in step S150, based on the first current and the second current, the sampling value of the first phase current and the sampling value of the second phase current are corrected and reconstructed to obtain the sampling value of the third phase current of the motor, thereby realizing the specific process of determining the phase current of the motor. Please refer to the following exemplary description.

[0100] Combine the following Figure 4 The method of the present invention shown in FIG. 1 is a flow chart of an embodiment of the method of correcting and reconstructing the sampling value of the first phase current and the sampling value of the second phase current based on the first current and the second current to obtain the sampling value of the third phase current of the motor, further illustrating the specific process of correcting and reconstructing the sampling value of the first phase current and the sampling value of the second phase current based on the first current and the second current in step S150 to obtain the sampling value of the third phase current of the motor, including: steps S410 to S420.

[0101] Step S410, based on the first current and the second current, correct the sampling value of the first phase current and the sampling value of the second phase current to obtain a first corrected current and a second corrected current, which are recorded as the corrected value of the first phase current of the motor and the corrected value of the second phase current of the motor.

[0102] Step S420, performing current reconstruction according to the correction value of the first phase current of the motor and the correction value of the second phase current of the motor to obtain a sampling value of the third phase current of the motor.

[0103] In the scheme of the present invention, an error self-correction strategy is proposed by analyzing the duration of the current observation window of each sector, which can effectively reduce the influence of zero point drift on phase current reconstruction under different modulation areas and working conditions.

[0104] In some embodiments, in step S410, based on the first current and the second current, the sampling value of the first phase current and the sampling value of the second phase current are corrected to obtain a first corrected current and a second corrected current, which are recorded as the corrected value of the first phase current of the motor and the corrected value of the second phase current of the motor. For the specific process, please refer to the following exemplary description.

[0105] Combine the following Figure 5The method of the present invention is shown as a flow chart of an embodiment of correcting the sampling value of the first phase current and the sampling value of the second phase current based on the first current and the second current, further illustrating the specific process of correcting the sampling value of the first phase current and the sampling value of the second phase current based on the first current and the second current in step S410, including: steps S510 to S520.

[0106] Step S510: taking the sum of the first current and the second current as the zero drift.

[0107] Step S520, taking the difference between the sampled value of the first phase current and the zero drift as the first correction current; and taking the difference between the sampled value of the second phase current and the zero drift as the second correction current.

[0108] like Fig.10 As shown, the voltage and current sampling and error compensation method of the DC bus also includes: step 5, correcting the sampled currents I1 and I2 to perform error compensation, and then executing step 6.

[0109] In step 5, the sampling currents I1 and I2 are calibrated, specifically including:

[0110] Step 51 , calculating the zero point drift Ie: calculating the zero point drift Ie according to the sampled current: 2Ie=I1+I2, and then executing step 52.

[0111] Step 52, correcting the sampling current: correcting the sampling current using the zero drift Ie to obtain corrected phase currents Ic1 and Ic2.

[0112] In the scheme of the present invention, dynamic current dual current sampling: using complementary effective voltage vector dynamic current dual current sampling, self-detection and self-correction of current zero drift are realized, and the influence of zero drift on current reconstruction accuracy is effectively reduced without adding additional hardware equipment.

[0113] In some embodiments, in step S420, current reconstruction is performed according to the correction value of the first phase current of the motor and the correction value of the second phase current of the motor to obtain the sampling value of the third phase current of the motor, including: based on Kirchhoff's current law, determining the relationship between the correction value of the first phase current of the motor, the correction value of the second phase current of the motor, and the sampling value of the third phase current of the motor, and calculating the sampling value of the third phase current of the motor according to the relationship; wherein, the sampling value of the first phase current is such as the a-phase current Ia, the correction value of the first phase current is such as the correction value of the a-phase current Ic1, the sampling value of the second phase current is such as the b-phase current Ib, the correction value of the second phase current is such as the correction value of the b-phase current Ic2, and the sampling value of the third phase current is such as the c-phase current Ic.

[0114] The calculated sampling value of the third phase current of the motor includes: an average value of the sampling values ​​of the third phase current of the motor calculated more than twice. Specifically, after repeatedly performing the step of acquiring the current of the DC bus detected by the single current sensor to obtain the first current and the second current more than twice, and repeatedly performing the step of correcting and reconstructing the sampling value of the first phase current and the sampling value of the second phase current based on the first current and the second current to obtain the sampling value of the third phase current of the motor more than twice, the average value of the sampling values ​​of the third phase current of the motor calculated more than twice.

[0115] In the solution of the present invention, based on a three-phase two-level inverter, a digital signal processing (DSP) chip of model TMS320F28335 is used as a control chip to drive a three-phase induction motor. In the three-phase two-level inverter, there is a corresponding relationship between the DC bus current Idc and the three-phase load currents Ia, Ib, and Ic. The relationship between the three-phase load currents Ia, Ib, and Ic can be expressed by Kirchhoff's current law:

[0116] I a +I b +I c =0 (1).

[0117] Among them, Ia is the a-phase current, Ib is the b-phase current, and Ic is the c-phase current.

[0118] By Figure 7 In the example shown, the DC bus current is sampled under different switching states of the switch tubes M1, M2, M3, M4, M5, and M6, and information on two-phase currents (such as a-phase current Ia and b-phase current Ib) can be obtained, and then the three-phase current (such as c-phase current Ic) can be reconstructed.

[0119] like Fig.10 As shown, the voltage and current sampling and error compensation method of the DC bus also includes: Step 6, reconstructing the three-phase current: reconstructing the three-phase currents Ia, Ib, and Ic according to the corrected phase currents and formula (1).

[0120] Step 7, multiple sampling and correction: By repeating steps 4, 5 and 6 for multiple sampling and correction and finally taking the average value, the influence of zero drift on phase current reconstruction can be gradually reduced, and the accuracy of third phase current reconstruction can be improved.

[0121] In the solution of the present invention, through the above steps, the zero drift can be detected and corrected in real time in each SVPWM modulation cycle, thereby improving the accuracy of the third phase current reconstruction and meeting the performance requirements of the motor control system. Specifically, the phase current error after correction is significantly reduced, which can meet the performance requirements of the motor control system.

[0122] In a three-phase two-level inverter, the zero drift phenomenon of a DC bus single current sensor (SCS) will cause the accuracy of phase current reconstruction to decrease, thereby affecting the performance of a motor control system. Although the use of a multi-current sensor method in a related scheme can improve the accuracy, it increases the complexity and cost of the system. The scheme of the present invention, therefore, aims to provide a DC bus single current sensor zero drift error self-correction scheme based on a complementary effective voltage vector, insert a complementary effective voltage vector during modulation, use a single sensor for double current sampling, and perform error compensation to improve the accuracy of the third phase current reconstruction, while maintaining the simplicity and economy of the system, and has certain practical value. The scheme of the present invention is not only applicable to three-phase two-level inverters, but can also be extended to other types of inverters, such as three-phase multi-level inverters, single-phase inverters, etc.; in addition, the scheme of the present invention can also be applied to other power electronic systems that require accurate current measurement, such as power converters, motor drive systems, etc.

[0123] The solution of the present invention adopts a single current sensor for current sampling to solve the problem that the three-phase current cannot be accurately sampled due to insufficient zero voltage vector duration. Compared with the three-resistance current sampling in the related solution, the need for multiple resistors is reduced, thereby reducing the hardware cost. For large-scale production equipment, this cost reduction is very significant. The use of a single sensor means that the installation process is simpler and faster, and there is no need to configure a resistor for each phase separately, which reduces the installation time and complexity. The probability of failure in long-term operation will also be relatively low. At the same time, when replacement or maintenance is required, the operation is also more convenient.

[0124] By adopting the technical solution of this embodiment, by sampling the three-phase current provided by the power supply control end of the motor (such as the three-phase current output by the motor controller or the inverter in the frequency converter), when the motor is running, the reference voltage vector (such as the reference voltage vector Vref) of the motor is determined according to the operating parameters of the motor; according to the sector position of the reference voltage vector of the motor (that is, the position of the reference voltage vector Vref in the basic voltage vector diagram of SVPWM), a pair of complementary effective voltage vectors in the corresponding basic voltage vector is selected; in the self-calibration area of ​​the reference voltage vector of the machine, a complementary effective voltage vector is inserted to replace zero in the SVPWM modulation method. vector, determine the time of the current observation window (that is, the duration of the current observation window is greater than the minimum sampling time Tmin); within the current observation window, use the DC bus single current sensor to dynamically double sample the DC bus current according to the minimum sampling time to obtain two sampling currents; correct the two sampling currents to obtain the two-phase current; reconstruct the two-phase current to obtain the third-phase current, so as to determine the three-phase current of the motor; thus, by inserting the complementary effective voltage vector in the SVPWM modulation and dynamically double sampling the DC bus current, the error compensation of the two-phase current sampling value is realized, and the accuracy of the reconstruction of the third-phase current is improved.

[0125] According to an embodiment of the present invention, a motor phase current determination device corresponding to the motor phase current determination method is also provided. Figure 6 The schematic diagram of the structure of an embodiment of the device of the present invention is shown in FIG. The power supply control end of the motor (such as a frequency converter or a motor controller) has a DC bus; a single current sensor is arranged at the DC bus to detect the current of the DC bus. Figure 7 It is a structural diagram of a three-phase bridge inverter circuit. Figure 7As shown, the three-phase bridge inverter circuit is arranged between the DC bus and the motor (PMSM). The three-phase bridge inverter circuit includes: switch tube M1, switch tube M2, switch tube M3, switch tube M4, switch tube M5, and switch tube M6; each switch tube can be selected from IGBT, the gate of the IGBT is used as the control end of each switch tube, the collector of the IGBT is used as the first connection end of each switch tube, and the emitter of the IGBT is used as the second connection end of each switch tube. The positive end of the bus voltage V of the DC bus is respectively connected to the first connection end of the switch tube M1, the first connection end of the switch tube M2, and the first connection end of the switch tube M3; the negative end of the bus voltage V of the DC bus is respectively connected to the second connection end of the switch tube M4, the second connection end of the switch tube M5, and the second connection end of the switch tube M6; the second connection end of the switch tube M1 is connected to the first connection end of the switch tube M4, the second connection end of the switch tube M2 is connected to the first connection end of the switch tube M5, and the second connection end of the switch tube M3 is connected to the first connection end of the switch tube M6. The switch tube M1 and the switch tube M4 constitute the first phase bridge arm of the three-phase bridge arm, and the common end of the switch tube M1 and the switch tube M4 is connected to the first phase winding of the three-phase winding of the motor; the switch tube M2 and the switch tube M5 constitute the second phase bridge arm of the three-phase bridge arm, and the common end of the switch tube M2 and the switch tube M5 is connected to the second phase winding of the three-phase winding of the motor; the switch tube M3 and the switch tube M6 constitute the third phase bridge arm of the three-phase bridge arm, and the common end of the switch tube M3 and the switch tube M6 is connected to the third phase winding of the three-phase winding of the motor.

[0126] In the scheme of the present invention, Figure 6 As shown, the method for determining the phase current of the motor includes: an acquisition unit 102 and a control unit 104 .

[0127] Wherein, the acquisition unit 102 is configured to acquire the operating parameters of the motor and the phase current parameters of the motor when the motor is running; wherein the phase current parameters of the motor include: the sampling value of the first phase current among the three-phase currents of the motor, and the sampling value of the second phase current among the three-phase currents of the motor. The phase current parameters of the motor can be sampled from the output end of the power supply control end of the motor (such as the output end of the inverter in the frequency converter or motor controller). For the specific functions and processing of the acquisition unit 102, see step S110.

[0128] The control unit 104 is configured to determine a reference voltage vector of the motor according to the operating parameters of the motor. The specific functions and processing of the control unit 104 refer to step S120. Fig.10 The figure is a flow chart of DC bus voltage and current sampling and error compensation based on the self-correction of zero drift error of DC bus single current sensor with complementary effective voltage vector. Fig.10As shown, the voltage and current sampling and error compensation method of the DC bus includes:

[0129] Step 1: Calculate the reference voltage vector Vref according to the running state of the motor, and then execute step 2.

[0130] In step 1, the reference voltage vector Vref is calculated according to the running state of the motor, which specifically includes:

[0131] Step 11, obtaining the operating parameters of the motor, the obtained operating parameters of the motor include the motor speed, load current, temperature, etc., and then executing step 12.

[0132] Step 12: determine a control target, such as maintaining stable operation of the motor, optimizing efficiency, etc., and then execute step 13.

[0133] Step 13: Calculate the reference voltage vector Vref: Calculate the required reference voltage vector Vref based on the mathematical model of the motor and the control target. Usually, this involves the electromagnetic equations of the motor and the control algorithm, such as vector control.

[0134] The control unit 104 is further configured to insert a complementary effective voltage vector into the SVPWM modulation of the motor according to the reference voltage vector of the motor. The specific functions and processing of the control unit 104 are also shown in step S130.

[0135] The acquisition unit 102 is further configured to acquire the current of the DC bus detected by the single current sensor twice within the time when the inserted complementary effective voltage vector acts, and record them as the first current and the second current. The specific function and processing of the acquisition unit 102 can also be seen in step S140.

[0136] The control unit 104 is further configured to correct and reconstruct the sampled value of the first phase current and the sampled value of the second phase current based on the first current and the second current, obtain the sampled value of the third phase current of the motor, and determine the phase current of the motor. The specific functions and processing of the control unit 104 are also shown in step S150.

[0137] The scheme of the present invention proposes a DC bus voltage and current sampling and error compensation scheme for self-correction of zero drift error of a DC bus single current sensor based on complementary effective voltage vector. By inserting complementary effective voltage vector and dynamic current dual current sampling technology, self-detection and self-correction of current zero drift are realized, and the accuracy of phase current reconstruction is improved. The scheme improves the accuracy of third-phase current reconstruction, reduces the influence of error magnification effect, and maintains the simplicity and economy of the system. It shows good performance in different modulation areas and working conditions, and can meet the performance requirements of motor control systems.

[0138] In some implementations, the control unit 104 inserts a complementary effective voltage vector in the SVPWM modulation of the motor according to the reference voltage vector of the motor, including:

[0139] The control unit 104 is further configured to select four effective voltage vectors at the sector position from the basic voltage vector according to the sector position of the reference voltage vector of the motor in the basic voltage vector diagram of SVPWM modulation. The specific functions and processing of the control unit 104 are also shown in step S210.

[0140] The control unit 104 is further configured to select a pair of complementary effective voltage vectors from the four effective voltage vectors, which are recorded as complementary effective voltage vectors. The specific functions and processing of the control unit 104 are also shown in step S220.

[0141] The control unit 104 is further configured to insert the complementary effective voltage vector in the self-calibration region of the reference voltage vector of the motor, so as to determine the time when the inserted complementary effective voltage vector acts as the time of the current observation time window of the motor. The specific functions and processing of the control unit 104 are also shown in step S230.

[0142] Figure 8 The schematic diagram of the basic voltage vector synthesis modulation area. The inverter control adopts space vector pulse width modulation (SVPWM) technology. Through the linear combination of the basic voltage space vector, the stator flux inside the motor is made into a vector circle, thus ensuring the stable electromagnetic torque output by the motor. Figure 8 In the figure, the self-calibration area includes: low modulation area, overmodulation area and sector boundary; the sectors include: sector I, sector II, sector III, sector IV, sector V, sector VI; the unobservable area includes: the area within the dotted line; the basic voltage vectors include: vector V0, vector V1, vector V2, vector V3, vector V4, vector V5, vector V6, vector V7, and vector V0 and vector V7 are located in the center circle ( Figure 8 not shown).

[0143] like Figure 8 As shown, corresponding to the switching state of the upper bridge arm (000, 001, 010, 011, 100, 101, 110, 111), there are 8 basic voltage space vectors of the motor: V0, V1, V2, V3, V4, V5, V6, V7. Corresponding to the switching state 000 of the upper bridge arm, the basic voltage space vector of the motor is V0; corresponding to the switching state 001 of the upper bridge arm, the basic voltage space vector of the motor is V1; corresponding to the switching state 010 of the upper bridge arm, the basic voltage space vector of the motor is V2; corresponding to the switching state 011 of the upper bridge arm, the basic voltage space vector of the motor is V3; corresponding to the switching state 100 of the upper bridge arm, the basic voltage space vector of the motor is V4; corresponding to the switching state 101 of the upper bridge arm, the basic voltage space vector of the motor is V5; corresponding to the switching state 110 of the upper bridge arm, the basic voltage space vector of the motor is V6; corresponding to the switching state 111 of the upper bridge arm, the basic voltage space vector of the motor is V7. Among them, V1, V2, V3, V4, V5, V6 are valid vectors, V0 and V7 are zero vectors, corresponding to Figure 8 The most central circle area (in Figure 8 not shown).

[0144] Fig. 9 Schematic diagram for inserting complementary effective voltage vectors. Fig. 9 In the figure, the solid line is the basic voltage vector, the dashed line is the sector boundary, and the red line is the component that decomposes the reference voltage into the basic voltage vector.

[0145] In the SVPWM modulation method, the basic voltage vector action time of each sector determines the duration of the current observation window. In order to ensure accurate current sampling, it is necessary to analyze the duration of the current observation window of each sector. Specifically, Figure 8 and Fig. 9 As shown, when the reference voltage vector Vref is located in an unobservable area (ie, a sector boundary or an overmodulation area), the action time of the effective voltage vector may be less than the minimum sampling time Tmin, resulting in the inability to accurately collect the current.

[0146] In order to extend the time of the current observation window, the solution of the present invention proposes to insert a complementary effective voltage vector in the SVPWM modulation method, replacing the insertion of a zero vector in the SVPWM modulation method in the related solution. In the solution of the present invention, the use of the complementary effective voltage vector: by inserting the complementary effective voltage vector instead of the zero vector, the problem of inaccurate sampling in the unobservable area of ​​the SVPWM method in the related solution is solved, and the use of the complementary effective voltage vector ensures that the current observation window duration is greater than the minimum sampling time, thereby improving the accuracy of current sampling.

[0147] like Fig.10As shown, the voltage and current sampling and error compensation method of the DC bus also includes:

[0148] Step 2: Select a suitable basic voltage vector according to the position of the reference voltage vector Vref, and then execute step 3.

[0149] In step 2, according to the position of the reference voltage vector Vref, a suitable basic voltage vector is selected, which specifically includes:

[0150] Step 21, determine the position of the reference voltage vector Vref, and then execute step 22. In step 21, the reference voltage vector Vref is projected onto the basic voltage vector diagram of SVPWM, such as Figure 8 As shown, the sector where the reference voltage vector Vref is located is determined.

[0151] Step 22, select a basic voltage vector: select a suitable basic voltage vector according to the position of the reference voltage vector Vref in the basic voltage vector diagram of SVPWM, and then execute step 23.

[0152] like Figure 8 As shown, the basic voltage vector diagram of SVPWM is divided into six sectors, and each sector corresponds to a group of basic voltage vectors. For example: if the reference voltage vector Vref is located in the first sector (i.e., sector I), vector V6, vector V1, vector V2, and vector V3 are selected as basic voltage vectors. If the reference voltage vector Vref is located in the second sector (i.e., sector II), vector V1, vector V2, vector V3, and vector V4 are selected as basic voltage vectors. If the reference voltage vector Vref is located in the third sector (i.e., sector III), vector V2, vector V3, vector V4, and vector V5 are selected as basic voltage vectors. If the reference voltage vector Vref is located in the fourth sector (i.e., sector IV), vector V3, vector V4, vector V5, and vector V6 are selected as basic voltage vectors. If the reference voltage vector Vref is located in the fifth sector (i.e., sector V), vector V4, vector V5, vector V6, and vector V1 are selected as basic voltage vectors. If the reference voltage vector Vref is located in the sixth sector (ie, sector VI), vector V5, vector V6, vector V1, and vector V2 are selected as basic voltage vectors.

[0153] Step 23, calculating the action time: according to the position of the reference voltage vector Vref and the modulation algorithm of SVPWM, calculating the action time of each basic voltage vector in the selected basic voltage vectors.

[0154] Step 3: inserting a complementary effective voltage vector in the selected basic voltage vector into the self-correction region of the reference voltage vector Vref, and then executing step 4.

[0155] In step 3, two adjacent effective voltage vectors (i.e., complementary effective voltage vectors) are used to replace the sporadic vectors (i.e., vector V0 and vector V7) to ensure that the duration of the current observation window is greater than the minimum sampling time Tmin. The duration of the current observation window is as follows: Figure 8 The time Ts is shown.

[0156] In step 3, a complementary effective voltage vector in the selected basic voltage vector is inserted into the self-correction region of the reference voltage vector Vref, specifically including:

[0157] Step 31, determine the self-correction region of the reference voltage vector Vref, and then execute step 32. Figure 8 As shown, the self-correction area of ​​the reference voltage vector Vref includes: a low modulation area, an overmodulation area, and a sector boundary. In the SVPWM modulation process, when the reference voltage vector Vref is located in an unobservable area (such as a sector boundary or an overmodulation area), the zero vector action time in the relevant scheme may be less than the minimum sampling time Tmin, so it is necessary to use two adjacent effective voltage vectors (i.e., complementary effective voltage vectors) to replace the sporadic vectors (i.e., vector V0 and vector V7) to ensure that the duration of the current observation window is greater than the minimum sampling time Tmin.

[0158] Step 32, in the self-correction region of the reference voltage vector Vref, select a complementary effective voltage vector, and then execute step 33. In step 32, in the self-correction region of the reference voltage vector Vref, select two adjacent effective voltage vectors to replace the zero vector (ie, vector V0 and vector V7).

[0159] For example: if the self-correction area of ​​the reference voltage vector Vref is in the first sector (i.e., sector I), then the complementary effective voltage vectors such as vector V6 and vector V3 are selected from the basic voltage vectors such as vector V6, vector V1, vector V2, and vector V3. If the self-correction area of ​​the reference voltage vector Vref is in the second sector (i.e., sector II), then the complementary effective voltage vectors such as vector V1 and vector V4 are selected from the basic voltage vectors such as vector V1, vector V2, vector V3, and vector V4. If the self-correction area of ​​the reference voltage vector Vref is in the third sector (i.e., sector III), then the complementary effective voltage vectors such as vector V2 and vector V5 are selected from the basic voltage vectors such as vector V2, vector V3, vector V4, and vector V5. If the self-correction area of ​​the reference voltage vector Vref is in the fourth sector (i.e., sector IV), then the complementary effective voltage vectors such as vector V3 and vector V6 are selected from the basic voltage vectors such as vector V3, vector V4, vector V5, and vector V6. If the self-correction region of the reference voltage vector Vref is in the fifth sector (i.e., sector V), then the complementary effective voltage vectors such as vector V4 and vector V1 are selected from the basic voltage vectors such as vector V4, vector V5, vector V6, and vector V1. If the self-correction region of the reference voltage vector Vref is in the sixth sector (i.e., sector VI), then the complementary effective voltage vectors such as vector V5 and vector V2 are selected from the basic voltage vectors such as vector V5, vector V6, vector V1, and vector V2.

[0160] Step 33, allocating the action time: dividing the action time T0 of the zero vector equally into two complementary effective voltage vectors. For example, if the self-correction region of the reference voltage vector Vref is in the first sector (i.e., sector I), then selecting the complementary effective voltage vectors such as vector V6 and vector V3 from the basic voltage vectors such as vector V6, vector V1, vector V2, and vector V3, and dividing the action time T0 of the zero vector equally into two complementary effective voltage vectors such as vector V6 and vector V3, as follows:

[0161] V0*T0=V3*T0 / 2+V6*T0 / 2 (2).

[0162] In the solution of the present invention, by inserting a complementary effective voltage vector in the selected basic voltage vector into the self-correction area of ​​the reference voltage vector Vref, the action time T0 of the zero vector can be equally divided into two complementary effective voltage vectors such as vector V6 and vector V3, ensuring that the duration of the current observation window is greater than the minimum sampling time Tmin, thereby improving the accuracy of current sampling.

[0163] Specifically, taking sector I as an example, in the self-correction region of the reference voltage vector Vref, the zero vectors V0 and V7 in the SVPWM switching sequence in the relevant scheme are replaced by two adjacent effective voltage vectors V3 and V6, as shown in FIG. Figure 8As shown. In this way, the action time T0 of the zero vector is equally divided into two complementary effective voltage vectors, that is, formula (2).

[0164] In different sectors, the switching sequence for inserting complementary effective voltage vectors is shown in Table 1.

[0165] In some implementations, the acquisition unit 102 acquires the current of the DC bus detected by the single current sensor twice within the time when the inserted complementary effective voltage vector acts, and records them as a first current and a second current, including:

[0166] The acquisition unit 102 is further configured to acquire a minimum sampling time pre-determined according to the hardware performance of the motor. The specific functions and processing of the acquisition unit 102 are also referred to step S310.

[0167] The acquisition unit 102 is also specifically configured to acquire the current of the DC bus detected by the single current sensor twice according to the minimum sampling time within the time when the inserted complementary effective voltage vector acts, and record it as the first current and the second current; that is, within the time of the current observation time window of the motor, acquire the current of the DC bus sampled twice by the single current sensor according to the predetermined minimum sampling time, and record it as the first current and the second current. For example: within the time when the inserted complementary effective voltage vector acts, the current of the DC bus detected by the single current sensor according to the minimum sampling time is acquired for the first time, and is recorded as the first current; and, still within the time when the inserted complementary effective voltage vector acts, the current of the DC bus detected by the single current sensor according to the minimum sampling time is acquired for the second time, and is recorded as the second current. Among them, the sum of the sampling time of the first current and the sampling time of the second current is less than the time when the inserted complementary effective voltage vector acts. The specific functions and processing of the acquisition unit 102 can also be found in step S320.

[0168] like Fig.10 As shown, the voltage and current sampling and error compensation method of the DC bus also includes: step 4, in the self-correction area of ​​the reference voltage vector Vref, after inserting the complementary effective voltage vector in the selected basic voltage vector, the DC bus current is double sampled based on the inserted complementary voltage vector to obtain the sampled currents I1 and I2, and then executing step 5.

[0169] In step 4, the DC bus current is double sampled based on the inserted complementary voltage vector to obtain the sampled currents I1 and I2. The specific sampling method is as follows:

[0170] Step 41, calculate the minimum sampling time Tmin: calculate the minimum sampling time Tmin according to the performance of the hardware device, and then execute step 42.

[0171] Step 42, perform double current sampling on the DC bus current: within the inserted complementary voltage vector action time (such as time Ts), use a single current sensor and based on the minimum sampling time Tmin, perform two samplings on the DC bus current to obtain sampling currents I1 and I2.

[0172] In the solution of the present invention, the dynamic current double current sampling technology is used to realize the self-detection and self-correction of the current zero drift, thereby improving the accuracy of the reconstruction of the third phase current.

[0173] In some implementations, the control unit 104 corrects and reconstructs the sampled value of the first phase current and the sampled value of the second phase current based on the first current and the second current to obtain the sampled value of the third phase current of the motor, thereby determining the phase current of the motor, including:

[0174] The control unit 104 is further configured to correct the sampled value of the first phase current and the sampled value of the second phase current based on the first current and the second current to obtain a first corrected current and a second corrected current, which are recorded as the corrected value of the first phase current of the motor and the corrected value of the second phase current of the motor. The specific functions and processing of the control unit 104 are also shown in step S410.

[0175] The control unit 104 is further configured to perform current reconstruction according to the correction value of the first phase current of the motor and the correction value of the second phase current of the motor to obtain a sampling value of the third phase current of the motor. The specific functions and processing of the control unit 104 are also shown in step S420.

[0176] In the scheme of the present invention, an error self-correction strategy is proposed by analyzing the duration of the current observation window of each sector, which can effectively reduce the influence of zero point drift on phase current reconstruction under different modulation areas and working conditions.

[0177] In some implementations, the control unit 104 corrects the sampled value of the first phase current and the sampled value of the second phase current based on the first current and the second current to obtain a first corrected current and a second corrected current, including:

[0178] The control unit 104 is further configured to use the sum of the first current and the second current as the zero drift. The specific functions and processing of the control unit 104 are also shown in step S510.

[0179] The control unit 104 is further configured to use the difference between the sampled value of the first phase current and the zero drift as the first correction current; and use the difference between the sampled value of the second phase current and the zero drift as the second correction current. The specific functions and processing of the control unit 104 are also shown in step S520.

[0180] like Fig.10 As shown, the voltage and current sampling and error compensation method of the DC bus also includes: step 5, correcting the sampled currents I1 and I2 to perform error compensation, and then executing step 6.

[0181] In step 5, the sampling currents I1 and I2 are calibrated, specifically including:

[0182] Step 51 , calculating the zero point drift Ie: calculating the zero point drift Ie according to the sampled current: 2Ie=I1+I2, and then executing step 52.

[0183] Step 52, correcting the sampling current: correcting the sampling current using the zero drift Ie to obtain corrected phase currents Ic1 and Ic2.

[0184] In the scheme of the present invention, dynamic current dual current sampling: using complementary effective voltage vector dynamic current dual current sampling, self-detection and self-correction of current zero drift are realized, and the influence of zero drift on current reconstruction accuracy is effectively reduced without adding additional hardware equipment.

[0185] In some embodiments, the control unit 104 performs current reconstruction according to the correction value of the first phase current of the motor and the correction value of the second phase current of the motor to obtain the sampling value of the third phase current of the motor, including: the control unit 104 is specifically configured to determine the relationship between the correction value of the first phase current of the motor, the correction value of the second phase current of the motor, and the sampling value of the third phase current of the motor based on Kirchhoff's current law, and calculate the sampling value of the third phase current of the motor according to the relationship; wherein the sampling value of the first phase current is such as the a-phase current Ia, the correction value of the first phase current is such as the correction value of the a-phase current Ic1, the sampling value of the second phase current is such as the b-phase current Ib, the correction value of the second phase current is such as the correction value of the b-phase current Ic2, and the sampling value of the third phase current is such as the c-phase current Ic.

[0186] The sampling value of the third phase current of the motor calculated by the control unit 104 includes: the control unit 104 is specifically configured to be the average value of the sampling values ​​of the third phase current of the motor calculated more than twice. Specifically, the acquisition unit 102 repeats the step of acquiring the current of the DC bus detected by the single current sensor to obtain the first current and the second current more than twice, and the control unit 104 repeats the step of correcting and reconstructing the sampling value of the first phase current and the sampling value of the second phase current based on the first current and the second current to obtain the sampling value of the third phase current of the motor more than twice, and then the average value of the sampling values ​​of the third phase current of the motor calculated more than twice.

[0187] In the solution of the present invention, based on a three-phase two-level inverter, a digital signal processing (DSP) chip of model TMS320F28335 is used as a control chip to drive a three-phase induction motor. In the three-phase two-level inverter, there is a corresponding relationship between the DC bus current Idc and the three-phase load currents Ia, Ib, and Ic. The relationship between the three-phase load currents Ia, Ib, and Ic can be expressed by Kirchhoff's current law:

[0188] I a +I b +I c =0 (1).

[0189] Among them, Ia is the a-phase current, Ib is the b-phase current, and Ic is the c-phase current.

[0190] By Figure 7 In the example shown, the DC bus current is sampled under different switching states of the switch tubes M1, M2, M3, M4, M5, and M6, and information on two-phase currents (such as a-phase current Ia and b-phase current Ib) can be obtained, and then the three-phase current (such as c-phase current Ic) can be reconstructed.

[0191] like Fig.10 As shown, the voltage and current sampling and error compensation method of the DC bus also includes: Step 6, reconstructing the three-phase current: reconstructing the three-phase currents Ia, Ib, and Ic according to the corrected phase currents and formula (1).

[0192] Step 7, multiple sampling and correction: By repeating steps 4, 5 and 6 for multiple sampling and correction and finally taking the average value, the influence of zero drift on phase current reconstruction can be gradually reduced, and the accuracy of third phase current reconstruction can be improved.

[0193] In the solution of the present invention, through the above steps, the zero drift can be detected and corrected in real time in each SVPWM modulation cycle, thereby improving the accuracy of the third phase current reconstruction and meeting the performance requirements of the motor control system. Specifically, the phase current error after correction is significantly reduced, which can meet the performance requirements of the motor control system.

[0194] In a three-phase two-level inverter, the zero drift phenomenon of a DC bus single current sensor (SCS) will cause the accuracy of phase current reconstruction to decrease, thereby affecting the performance of a motor control system. Although the use of a multi-current sensor method in a related scheme can improve the accuracy, it increases the complexity and cost of the system. The scheme of the present invention, therefore, aims to provide a DC bus single current sensor zero drift error self-correction scheme based on a complementary effective voltage vector, insert a complementary effective voltage vector during modulation, use a single sensor for double current sampling, and perform error compensation to improve the accuracy of the third phase current reconstruction, while maintaining the simplicity and economy of the system, and has certain practical value. The scheme of the present invention is not only applicable to three-phase two-level inverters, but can also be extended to other types of inverters, such as three-phase multi-level inverters, single-phase inverters, etc.; in addition, the scheme of the present invention can also be applied to other power electronic systems that require accurate current measurement, such as power converters, motor drive systems, etc.

[0195] The solution of the present invention adopts a single current sensor for current sampling to solve the problem that the three-phase current cannot be accurately sampled due to insufficient zero voltage vector duration. Compared with the three-resistance current sampling in the related solution, the need for multiple resistors is reduced, thereby reducing the hardware cost. For large-scale production equipment, this cost reduction is very significant. The use of a single sensor means that the installation process is simpler and faster, and there is no need to configure a resistor for each phase separately, which reduces the installation time and complexity. The probability of failure in long-term operation will also be relatively low. At the same time, when replacement or maintenance is required, the operation is also more convenient.

[0196] Since the processing and functions implemented by the device of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments, and no further elaboration will be made here.

[0197] According to an embodiment of the present invention, a motor corresponding to the phase current determination device of the motor is also provided. The motor may include: the phase current determination device of the motor described above.

[0198] Since the processing and functions implemented by the motor of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned device, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0199] According to an embodiment of the present invention, a computer program product corresponding to the method for determining the phase current of a motor is also provided, comprising a computer program, which implements the steps of the method for determining the phase current of the motor described above when executed by a processor.

[0200] Since the processing and functions implemented by the product of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments, and no further elaboration will be made here.

[0201] According to an embodiment of the present invention, a storage medium corresponding to a method for determining a phase current of a motor is also provided, wherein the storage medium includes a stored program, wherein when the program is running, the device where the storage medium is located is controlled to execute the steps of the method for determining the phase current of the motor described above.

[0202] Since the processing and functions implemented by the storage medium of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for the details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments, and no further elaboration will be made here.

[0203] In summary, it is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0204] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A method for determining the phase current of a motor, characterized in that: The power supply control end of the motor has a DC bus; a single current sensor is arranged at the DC bus for detecting the current of the DC bus; The method for determining the phase current of the motor comprises: When the motor is running, the running parameters of the motor are obtained, and the phase current parameters of the motor are obtained; wherein the phase current parameters of the motor include: a sampled value of a first phase current among the three-phase currents of the motor, and a sampled value of a second phase current among the three-phase currents of the motor; Determining a reference voltage vector of the motor according to operating parameters of the motor; inserting a complementary effective voltage vector in SVPWM modulation of the motor according to a reference voltage vector of the motor; Acquire the current of the DC bus detected by the single current sensor twice within the time when the inserted complementary effective voltage vector acts, and record them as a first current and a second current; Based on the first current and the second current, the sampling value of the first phase current and the sampling value of the second phase current are corrected and reconstructed to obtain the sampling value of the third phase current of the motor, thereby determining the phase current of the motor.

2. The method for determining the phase current of a motor according to claim 1, characterized in that: Inserting a complementary effective voltage vector in the SVPWM modulation of the motor according to the reference voltage vector of the motor comprises: According to the sector position of the reference voltage vector of the motor in the basic voltage vector diagram of SVPWM modulation, four effective voltage vectors at the sector position are selected from the basic voltage vector; Select a pair of complementary effective voltage vectors from the four effective voltage vectors and record them as complementary effective voltage vectors; The complementary effective voltage vector is inserted in the self-calibration region of the reference voltage vector of the motor, so that the time when the inserted complementary effective voltage vector acts is determined as the time of the current observation time window of the motor.

3. The method for determining the phase current of a motor according to claim 1 or 2, characterized in that: Acquiring the current of the DC bus detected by the single current sensor twice during the time when the inserted complementary effective voltage vector acts, recorded as a first current and a second current, including: Obtaining a minimum sampling time pre-determined according to the hardware performance of the motor; During the time when the inserted complementary effective voltage vector acts, the current of the DC bus detected by the single current sensor is acquired twice according to the minimum sampling time, and is recorded as a first current and a second current.

4. The method for determining the phase current of a motor according to any one of claims 1 to 3, characterized in that: Based on the first current and the second current, the sampled value of the first phase current and the sampled value of the second phase current are corrected and reconstructed to obtain the sampled value of the third phase current of the motor, so as to determine the phase current of the motor, including: Based on the first current and the second current, the sampled value of the first phase current and the sampled value of the second phase current are corrected to obtain a first corrected current and a second corrected current, which are recorded as a corrected value of the first phase current of the motor and a corrected value of the second phase current of the motor; Current reconstruction is performed according to the correction value of the first phase current of the motor and the correction value of the second phase current of the motor to obtain a sampling value of the third phase current of the motor.

5. The method for determining the phase current of a motor according to claim 4, characterized in that: Based on the first current and the second current, correcting the sampled value of the first phase current and the sampled value of the second phase current to obtain a first corrected current and a second corrected current, including: Taking the sum of the first current and the second current as the zero point drift; The difference between the sampling value of the first phase current and the zero drift is used as the first correction current; and the difference between the sampling value of the second phase current and the zero drift is used as the second correction current.

6. The method for determining the phase current of a motor according to claim 4, characterized in that: Current reconstruction is performed according to the correction value of the first phase current of the motor and the correction value of the second phase current of the motor to obtain a sampling value of the third phase current of the motor, including: Based on Kirchhoff's current law, determine the relationship between the correction value of the first phase current of the motor, the correction value of the second phase current of the motor, and the sampled value of the third phase current of the motor, and calculate the sampled value of the third phase current of the motor according to the relationship; The calculated sampling value of the third phase current of the motor includes: an average value of the sampling values ​​of the third phase current of the motor calculated more than twice.

7. A device for determining phase current of a motor, characterized in that: The power supply control end of the motor has a DC bus; a single current sensor is arranged at the DC bus for detecting the current of the DC bus; the method for determining the phase current of the motor includes: an acquisition unit, configured to acquire the operation parameters of the motor and the phase current parameters of the motor when the motor is running; wherein the phase current parameters of the motor include: a sampled value of a first phase current among the three-phase currents of the motor, and a sampled value of a second phase current among the three-phase currents of the motor; a control unit configured to determine a reference voltage vector of the motor according to an operating parameter of the motor; The control unit is further configured to insert a complementary effective voltage vector in the SVPWM modulation of the motor according to the reference voltage vector of the motor; The acquisition unit is further configured to acquire the current of the DC bus detected by the single current sensor twice within the time when the inserted complementary effective voltage vector acts, and record them as a first current and a second current; The control unit is also configured to correct and reconstruct the sampling value of the first phase current and the sampling value of the second phase current based on the first current and the second current, obtain the sampling value of the third phase current of the motor, and determine the phase current of the motor.

8. A motor, characterized in that: include: The phase current determining device of the motor as claimed in claim 7.

9. A storage medium, characterized in that: The storage medium includes a stored program, wherein when the program is executed, the device where the storage medium is located is controlled to execute the method for determining the phase current of the motor according to any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method for determining the phase current of the motor according to any one of claims 1 to 6 are implemented.

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