Method for Reconstructing Control of Output Torque of Permanent Magnet Synchronous Motor Based on Busbar Current

Abstract

The present application discloses a method for controlling the output torque of a permanent magnet synchronous motor based on bus current reconstruction, which relates to the technical field of permanent magnet synchronous motor control and includes the following steps: reconstructing the bus three-phase current obtained to obtain the bus current I dc , and calculating the DC power P of the permanent magnet synchronous motor dc ; determining the loss power P1 of the permanent magnet synchronous motor and the loss power P2 of the permanent magnet synchronous motor controller; according to the DC power P dc , and obtaining the corrected output torque T of the permanent magnet synchronous motor based on the loss power P1 and the loss power P2 e . The present application aims to solve the technical problems of insufficient torque estimation accuracy or the need for external hardware facilities in the related art.

Description

Technical Field

[0001] The present application relates to the technical field of permanent magnet synchronous motor control, and particularly relates to a method for controlling the output torque of a permanent magnet synchronous motor based on bus current reconstruction. Background Art

[0002] In the main drive motor of new energy vehicles, permanent magnet synchronous motors have gradually become the first choice for main drive motors due to advantages such as high power density and wide speed regulation range. As one of the most basic and important requirements for new energy vehicles, safety and stability require the permanent magnet synchronous motor controller to accurately execute the vehicle torque command to maintain the safe operation of the vehicle. To prevent unexpected torque output, it is necessary to accurately estimate and monitor the actual output torque of the permanent magnet synchronous motor controller in real time to reduce the safety hazards caused by unexpected torque output.

[0003] In Related Art 1, there is a motor torque estimation scheme based on power flow, which requires the vehicle to feedback bus current information and finally calculates the real-time torque according to the loss model; however, this scheme requires a bus current sensor to obtain the vehicle feedback bus current information, which additionally increases the hardware cost.

[0004] As an improvement, in Related Art 2, there is also an improved power flow torque estimation scheme, which takes the product of the output voltage of the current PI (Proportional Integral) regulator and the feedback current as the output electric power, and finally calculates the output torque according to the motor loss model. Although this scheme does not require obtaining the vehicle feedback bus current information, due to the modulation depth saturation characteristic, the output voltage calculated by the PI regulator is non-linear, resulting in the inconsistency between the calculated output voltage and the actual output voltage, and finally resulting in the reduction of the calculated torque accuracy.

[0005] Based on this, the problems of insufficient torque estimation accuracy or the need for external hardware facilities in the related art still need to be solved. Summary of the Invention

[0006] The embodiments of the present application provide a method for controlling the output torque of a permanent magnet synchronous motor based on bus current reconstruction to solve the technical problems of insufficient torque estimation accuracy or the need for external hardware facilities in the related art.

[0007] In a first aspect, a method for controlling the output torque of a permanent magnet synchronous motor based on bus current reconstruction is provided, including the following steps:

[0008] Reconstruct the bus current I according to the obtained three-phase bus currents, and calculate the DC power P of the permanent magnet synchronous motor dc , and calculate the loss power P1 of the permanent magnet synchronous motor and the loss power P2 of the permanent magnet synchronous motor controller; dc ;

[0009] Determine the loss power P1 of the permanent magnet synchronous motor and the loss power P2 of the permanent magnet synchronous motor controller;

[0010] According to the DC power P dc , and based on the loss power P1 and the loss power P2, obtain the corrected output torque T of the permanent magnet synchronous motor e .

[0011] In some embodiments, the specific steps of reconstructing the bus current I from the acquired three-phase bus currents include: dc :

[0012] Obtain the two-phase currents Iα and Iβ in the stationary coordinate system from the bus currents Ia, Ib, and Ic acquired by abc / αβ transformation;

[0013] Perform αβ / dq transformation on the two-phase currents Iα and Iβ to obtain the two-phase currents Id and Iq in the rotating coordinate system;

[0014] The two-phase currents Id and Iq output two-phase voltages Ud and Uq through a PI regulator;

[0015] Perform dq / αβ transformation on the two-phase voltages Ud and Uq and perform an advance compensation of 1.5 carrier cycles to obtain the two-phase voltages Uα and Uβ in the rotating coordinate system;

[0016] The two-phase voltages Uα and Uβ are modulated by the SVPWM control algorithm to output three-phase duty ratios Da, Db, and Dc;

[0017] Perform dq / abc transformation on the two-phase currents Id and Iq and perform an advance compensation of 0.5 carrier cycle to obtain the three-phase currents Ia′, Ib′, and Ic′ in the stationary coordinate system;

[0018] According to the three-phase currents Ia′, Ib′, Ic′ and the three-phase duty ratios Da, Db, Dc, and using each of the three-phase duty ratios as the weighting coefficient of the three-phase currents, perform weighted summation on the three-phase currents to obtain the reconstructed bus current I dc .

[0019] In some embodiments, the specific steps of reconstructing the bus current I from the acquired three-phase bus currents dc , and calculating the DC power P of the permanent magnet synchronous motor dc include:

[0020] After obtaining the bus voltage U dc , multiply the bus current I dc by the bus voltage U dc to obtain the DC power P of the permanent magnet synchronous motor dc .

[0021] In some embodiments, according to the DC power P dc, and obtain the corrected output torque T of the permanent magnet synchronous motor based on the loss power P1 and the loss power P2 e The specific steps include:

[0022] Subtract the loss power P1 from the DC power P dc , and also subtract the loss power P2, to obtain the corrected output mechanical power P of the permanent magnet synchronous motor e ;

[0023] According to the ratio of the output mechanical power P e to the angular velocity ω of the rotor of the permanent magnet synchronous motor obtained, obtain the corrected output torque T of the permanent magnet synchronous motor e .

[0024] In some embodiments, the loss power P2 includes the IGBT switching loss power P 21 , and the specific steps for determining the loss power P2 of the permanent magnet synchronous motor include:

[0025] Solve for the effective value of the three-phase current, and determine the IGBT switching frequency and the delay time of the IGBT switch;

[0026] According to the obtained bus voltage U dc and the effective value of the three-phase current, the IGBT switching frequency, and the delay time of the IGBT switch, calculate to obtain the IGBT switching loss power P 21 .

[0027] In some embodiments, where the IGBT switch satisfies the condition:

[0028] The turn-on time is equal to the turn-off time of the IGBT;

[0029] And when the IGBT is in the on state, the current change rate between the gate and the corresponding emitter in the IGBT is equal to the voltage change rate.

[0030] In some embodiments, the loss power P2 further includes the IGBT conduction internal resistance loss power P 22 and the IGBT conduction voltage drop loss power P 23 , and the specific steps for determining the loss power P2 of the permanent magnet synchronous motor include:

[0031] Determine the conduction internal resistance and the conduction voltage drop;

[0032] According to the effective value of the three-phase current and the conduction internal resistance, calculate to obtain the IGBT conduction internal resistance loss power P 22 ;

[0033] According to the effective value of the three-phase current and the conduction voltage drop, calculate to obtain the IGBT conduction voltage drop loss power P 23 .

[0034] In some embodiments, the IGBT conduction satisfies the condition that:

[0035] The on-state voltage drop of the diode connected in anti-parallel with the IGBT is the same as the conduction voltage drop, and the on-resistance is the same as the on-state internal resistance.

[0036] In some embodiments, the loss power P1 includes the copper loss power P 11 , and the specific steps for determining the loss power P1 of the permanent magnet synchronous motor include:

[0037] Solve for the effective value of the three-phase current, and calculate the copper loss power P according to the resistance value R of the three-phase winding of the permanent magnet synchronous motor 11 11 .

[0038] In some embodiments, the loss power P1 further includes the iron loss power P 12 , and the specific steps for determining the loss power P1 of the permanent magnet synchronous motor include:

[0039] Calculate the iron loss power P according to the effective value of the three-phase current and the rotational speed N of the permanent magnet synchronous motor 12 12 .

[0040] The beneficial effects brought by the technical solution provided in this application include: no need to add external hardware facilities and higher estimation accuracy.

[0041] The embodiment of this application provides a method for controlling the output torque of a permanent magnet synchronous motor based on bus current reconstruction. This method reconstructs the bus current according to the acquired three-phase bus current to obtain the DC power P of the permanent magnet synchronous motor dc , and at the same time, also considers the loss power P1 of the permanent magnet synchronous motor and the loss power P2 of the permanent magnet synchronous motor controller, so as to obtain the corrected output torque T of the permanent magnet synchronous motor according to each power e . By means of bus current reconstruction, there is no need to additionally set up hardware facilities such as bus current sensors, and it also avoids the reduction in the estimation accuracy of the output torque of the permanent magnet synchronous motor due to the non-linearity of the output voltage caused by the modulation depth saturation characteristic. It can be seen that the embodiment of this application can reduce costs while taking into account the torque estimation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to these drawings.

[0043] ​​Figure 1 Flow chart of a method for controlling the output torque of a permanent magnet synchronous motor based on bus current reconstruction provided by an embodiment of the present application;

[0044] Figure 2 Specific flow chart for reconstructing the bus current I from the acquired three-phase bus currents in an embodiment of the present application dc ;

[0045] Figure 3 Simulation result graph of an embodiment of the present application and that without a compensation strategy;

[0046] Figure 4 Simulation result graph of an embodiment of the present application and related art 2.

[0047] The realization, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0048] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Apparently, the described embodiments are some but not all of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0049] The flow charts shown in the accompanying drawings are only illustrative, not necessarily including all the contents and operations / steps, nor necessarily executed in the described order. For example, some operations / steps can also be decomposed, combined or partially merged, so the actual execution order may be changed according to the actual situation.

[0050] In a related art, the output torque of a permanent magnet synchronous motor is obtained by solving the steady-state mathematical model equation of the interior permanent magnet synchronous motor (IPMSM). The steady-state mathematical model equation is as follows:

[0051]

[0052] In the formula, T e is the output torque, p is the number of pole pairs of the motor, is the rotor flux linkage, L d is the stator d-axis inductance, L q is the stator q-axis inductance, i q is the stator d-axis current, i d is the stator q-axis current.

[0053] Since the stator inductance and rotor flux are significantly disturbed by the magnitude and direction of the stator current and there is also mutual coupling, it can be determined from the steady-state mathematical model equation that when obtaining the output torque T e Before that, the stator d-axis inductance L needs to be calibrated in advance. d , stator q-axis inductance L q and rotor permanent magnet flux It can be seen that the amount of data processing is very large, the workload is cumbersome, and the accuracy of torque estimation is difficult to control.

[0054] Based on this, an embodiment of the present application provides a method for controlling the output torque of a permanent magnet synchronous motor based on bus current reconstruction, which can reduce costs while taking into account the torque estimation accuracy.

[0055] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0056] like Figure 1 As shown, the embodiment of the present application provides a method for controlling the output torque of a permanent magnet synchronous motor based on bus current reconstruction, comprising the following steps:

[0057] S1: Reconstruct the bus current I according to the obtained bus three-phase current dc , and calculate the DC power P of the permanent magnet synchronous motor dc ;

[0058] S2: Determine the power loss P1 of the permanent magnet synchronous motor and the power loss P2 of the permanent magnet synchronous motor controller;

[0059] S3: According to the DC power P dc , and based on the power loss P1 and the power loss P2, the corrected output torque T of the permanent magnet synchronous motor is obtained e .

[0060] In this embodiment, the bus current is reconstructed according to the acquired bus three-phase current to obtain the DC power P of the permanent magnet synchronous motor. dc , and also consider the power loss P1 of the permanent magnet synchronous motor and the power loss P2 of the permanent magnet synchronous motor controller, so as to estimate the DC power P with slightly lower estimation accuracy based on the power loss P1 and the power loss P2. dc Correction compensation is performed to obtain the corrected output torque T of the permanent magnet synchronous motor. e ,By reconstructing the bus current, no additional hardware facilities such as bus current sensors are required, and the output voltage nonlinearity caused by the modulation depth saturation characteristics may be avoided, which may reduce the accuracy of the estimated permanent magnet synchronous motor output torque.

[0061] likeFigure 2 As shown, in the step S1, the bus current I is reconstructed based on the acquired three-phase bus currents dc The specific steps include:

[0062] The three-phase bus currents Ia, Ib, and Ic obtained through abc / αβ transformation are used to obtain the two-phase currents Iα and Iβ in the stationary coordinate system;

[0063] The two-phase currents Iα and Iβ are subjected to αβ / dq transformation to obtain the two-phase currents Id and Iq in the rotating coordinate system;

[0064] The two-phase currents Id and Iq are output as two-phase voltages Ud and Uq through a PI regulator;

[0065] The two-phase voltages Ud and Uq are subjected to dq / αβ transformation and advanced compensation by 1.5 carrier cycles to obtain the two-phase voltages Uα and Uβ in the rotating coordinate system;

[0066] The two-phase voltages Uα and Uβ are modulated through an SVPWM control algorithm to output the three-phase duty ratios Da, Db, and Dc;

[0067] The two-phase currents Id and Iq are subjected to dq / abc transformation and advanced compensation by 0.5 carrier cycle to obtain the three-phase currents Ia′, Ib′, and Ic′ in the stationary coordinate system;

[0068] According to the three-phase currents Ia′, Ib′, and Ic′ and the three-phase duty ratios Da, Db, and Dc, with each of the three-phase duty ratios serving as the weighting coefficient for the three-phase currents, the three-phase currents are weighted and summed to obtain the reconstructed bus current I dc . That is, the reconstructed bus current I dc The calculation formula is:

[0069] I dc = I a ′·D a + I b ′·D b + I c ′·D c .

[0070] Furthermore, the step of reconstructing the bus current I based on the acquired three-phase bus currents dc , and calculating the DC power P of the permanent magnet synchronous motor dc The specific steps include:

[0071] After acquiring the bus voltage U dc , multiply the bus current I dc by the bus voltage U dc to obtain the DC power P of the permanent magnet synchronous motor dc .

[0072] Preferably, the specific steps of step S3 include:

[0073] Subtract the loss power P1 and also subtract the loss power P2 from the DC power P to obtain the corrected output mechanical power P of the permanent magnet synchronous motor dc ; e ;

[0074] According to the ratio of the output mechanical power P e to the angular velocity ω of the rotor of the permanent magnet synchronous motor obtained, obtain the corrected output torque T of the permanent magnet synchronous motor e .

[0075] In this embodiment, the output torque T e = P e / ω = (P dc - P1 - P2) / ω, where ω is the angular velocity of the rotor of the permanent magnet synchronous motor, P e is the output mechanical power of the permanent magnet synchronous motor, P1 is the loss power of the permanent magnet synchronous motor, and P1 is the loss power of the permanent magnet synchronous motor controller.

[0076] Verifyingly, a simulation model is built in MATLAB software, and the simulation conditions are: motor speed 9550 rpm, bus voltage 350 V, stator resistance 10 mΩ, d-axis inductance 0.12 mH, q-axis inductance 0.24 mH, rotor flux linkage 0.06 Wb, and the given d-axis current i d = -200 A, q-axis current i q = 50 A. The simulation results are as Figure 3 shown. The Idc_A line is the real bus current curve, and the real bus current is approximately 73.5 A. The Idc_R line uses the control strategy of this embodiment for compensation before 0.25 s, and the estimated bus current is approximately 74 A. After 0.25 s, the compensation strategy is cancelled, and the traditional bus current reconstruction strategy is used, and the estimated bus current is approximately 84.5 A. Obviously, if the compensation strategy is not added, it will seriously affect the authenticity of the bus current estimation.

[0077] During the process of bus current reconstruction, due to the discrete wave delay and phase current sampling delay, the duty ratio of the modulation output, that is, the center point of the modulation voltage, is inconsistent with the center point of the phase current sampling. If the correction compensation strategy is not adopted, it will inevitably lead to a large difference between the estimated output torque and the actual one, as shown by the curve of the Idc_R line in Figure 3 .

[0078] It can be seen that the embodiment of the present application improves the estimation accuracy of the output torque of the permanent magnet synchronous motor by correcting the DC current of the bus, and further improves the safety and reliability of the vehicle operation.

[0079] Preferably, the loss power P1 includes copper loss power P 11 , and the specific steps for determining the loss power P1 of the permanent magnet synchronous motor include:

[0080] Solve for the effective value of the three-phase current, and calculate the copper loss power P according to the resistance value R of the three-phase winding resistance of the permanent magnet synchronous motor 11 11 .

[0081] Furthermore, the loss power P1 also includes iron loss power P 12 , and the specific steps for determining the loss power P1 of the permanent magnet synchronous motor include:

[0082] Calculate the iron loss power P according to the effective value of the three-phase current and the rotational speed N of the permanent magnet synchronous motor 12 12 .

[0083] In the embodiment of the present application, the loss power P1 of the permanent magnet synchronous motor includes copper loss power P 11 and iron loss power P 12 , where the copper loss power model is equivalent to: P 11 = 3I 2 rms ·R 11 ; the iron loss power model is equivalent to: P 12 = k·N 12 ·I rms ; where, I rms is the effective value of the three-phase current, R 11 is the resistance value of the three-phase winding resistance, N 12 is the rotational speed of the permanent magnet synchronous motor, and k is the calibration coefficient obtained by testing.

[0084] Among them, for the copper loss model of the permanent magnet synchronous motor, it is also necessary to make the resistance values of the three-phase winding resistances equal, and without considering the change of the three-phase winding resistance with temperature, the resistance value of the three-phase winding resistance can be measured by using a milliohm meter under the condition that the permanent magnet synchronous motor is heated to 65°C.

[0085] Preferably, the loss power P2 includes IGBT switching loss power P 21 , and the specific steps for determining the loss power P2 of the permanent magnet synchronous motor include:

[0086] Solve for the effective value of the three-phase current, and determine the IGBT switching frequency and the delay time of the IGBT switch;

[0087] According to the obtained bus voltage U dc ​​Calculate the IGBT switching loss power P based on the effective values of the three-phase currents, the IGBT switching frequency, and the delay time of the IGBT switch. 21 .

[0088] Furthermore, the IGBT switch satisfies the conditions:

[0089] The turn-on time is equal to the turn-off time of the IGBT;

[0090] And when the IGBT is in the on state, the rate of change of the current between the gate and the corresponding emitter in the IGBT is equal to the rate of change of the voltage.

[0091] Even further, the loss power P2 further includes the IGBT conduction internal resistance loss power P 22 and the IGBT conduction voltage drop loss power P 23 . The specific steps to determine the loss power P2 of the permanent magnet synchronous motor include:

[0092] Determine the conduction internal resistance and the conduction voltage drop;

[0093] Calculate the IGBT conduction internal resistance loss power P based on the effective value of the three-phase current and the conduction internal resistance 22 ;

[0094] Calculate the IGBT conduction voltage drop loss power P based on the effective value of the three-phase current and the conduction voltage drop 23 .

[0095] Even further, the IGBT conduction satisfies the conditions:

[0096] The on-state voltage drop of the diode anti-parallel to the IGBT is the same as the conduction voltage drop, and the on-resistance is the same as the conduction internal resistance.

[0097] In the embodiments of the present application, the loss power P2 of the permanent magnet synchronous motor includes the IGBT switching loss power P 21 and the IGBT conduction loss power. The IGBT conduction loss power specifically includes the IGBT conduction internal resistance loss power P 22 and the IGBT conduction voltage drop loss power P 23 . The IGBT switching loss power model is equivalent to: P 21 = 1.5U dc ·I rms ·t·f; The IGBT conduction internal resistance loss power is equivalent to: P 22 = 3I 2 rms ·R in ; The IGBT conduction voltage drop loss power is equivalent to: P 23 = 3I rms ·Uin ; where I rms is the effective value of the three-phase current, U dc is the DC bus voltage, t is the delay time of the IGBT switch, f is the IGBT switching frequency, R in is the on-resistance, U in is the on-voltage drop. Also, the delay time, on-resistance, and on-voltage drop of the IGBT switch can be obtained by referring to the IGBT user manual and determined through test calibration.

[0098] Specifically, the above current change rate being equal to the voltage change rate specifically means in this embodiment that the current increases with an equal slope and the voltage decreases with an equal slope.

[0099] In a specific embodiment, the output torque T e = P e / ω, and the specific solution formula for the corrected output mechanical power P e of the permanent magnet synchronous motor is:

[0100] P e = P dc - P 11 - P 12 - P 21 - P 22 - P 23 ,

[0101] In the formula, P dc is the DC power, P 11 is the copper loss power, P 12 is the iron loss power, P 21 is the IGBT switching loss power, P 22 is the IGBT on-resistance loss power, P 23 is the IGBT on-voltage drop loss power.

[0102] And the solutions for the DC power P dc , copper loss power P 11 , iron loss power P 12 , IGBT switching loss power P 21 , IGBT on-resistance loss power P 22 , and IGBT on-voltage drop loss power P 23 have been described in the above specific embodiments and will not be elaborated in detail here.

[0103] For verification, take the busbar current calculated in this embodiment and related art 2 as an example. A simulation model was built in software MATLAB, and the simulation conditions were as follows: motor speed 9550 rpm, busbar voltage 350 V, stator resistance 10 mΩ, d-axis inductance 0.12 mH, q-axis inductance 0.24 mH, rotor magnetic flux 0.06 Wb, given d-axis current id = -100 A, q-axis current iq = 97 A. The simulation results are as Figure 4 shown. The Idc_A line is the real busbar current curve, and the real busbar current is roughly between 118 and 119 A; the Idc_R line is the busbar current curve reconstructed using the embodiment of the present application, and its busbar current is also roughly between 118 and 119 A; the Idc_P line is the busbar current curve reconstructed using related art 2, and its busbar current is roughly between 157 and 158 A. Among them, the actual output phase voltage is 211 V, in the overmodulation region 1. By comparing the Idc_R line and the Idc_P line, it can be seen that the embodiment of the present application is closer to the real value than the busbar current obtained by using the product of the output voltage of the current PI (proportional integral) regulator and the feedback current as the output electric power in related art 2 and then back-calculated.

[0104] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation to the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal connection of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0105] It should be noted that in the present application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0106] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for controlling the output torque of a permanent magnet synchronous motor based on bus current reconstruction, characterized in that, Including the following steps: Reconstruct the bus current I based on the obtained three-phase currents dc , and calculate the DC power P of the permanent magnet synchronous motor dc ; Determine the loss power P1 of the permanent magnet synchronous motor and the loss power P2 of the permanent magnet synchronous motor controller; According to the DC power P dc , and based on the loss power P1 and the loss power P2, the corrected output torque T of the permanent magnet synchronous motor is obtained e ; The bus current I reconstructed based on the acquired three-phase currents dc The specific steps are as follows: Obtain the three-phase currents Ia, Ib, and Ic through abc / αβ transformation to get the two-phase currents Iα and Iβ in the stationary coordinate system; Perform αβ / dq transformation on the two-phase currents Iα and Iβ to obtain the two-phase currents Id and Iq in the rotating coordinate system; The two-phase currents Id and Iq output the two-phase voltages Ud and Uq through a PI regulator; Perform dq / αβ transformation on the two-phase voltages Ud and Uq and perform an advance compensation of 1.5 carrier cycles to obtain the two-phase voltages Uα and Uβ in the rotating coordinate system; The two-phase voltages Uα and Uβ are modulated by the SVPWM control algorithm to output the three-phase duty ratios Da, Db, and Dc; Perform dq / abc transformation on the two-phase currents Id and Iq and perform an advance compensation of 0.5 carrier cycle to obtain the three-phase currents Ia′, Ib′, and Ic′ in the stationary coordinate system; According to the three-phase currents Ia′, Ib′, Ic′ and the three-phase duty ratios Da, Db, Dc, taking each of the three-phase duty ratios as the weighting factor of the three-phase currents, the weighted sum of the three-phase currents is calculated to obtain the reconstructed bus current I dc ; The loss power P2 includes the IGBT switching loss power P 21 , and the specific steps for determining the IGBT switching loss power include: Solve the effective values of the three-phase currents and determine the IGBT switching frequency and the delay time of the IGBT switch; According to the obtained bus voltage U dc and the effective values of the three-phase currents, the IGBT switching frequency, and the delay time of the IGBT switch, calculate the IGBT switching loss power P 21 ; The IGBT switching loss power model is equivalent to: P 21 = 1.5U dc ·I rms ·t·f; Among them, I rms is the effective value of the three-phase current, U dc is the DC bus voltage, t is the delay time of the IGBT switch, and f is the IGBT switching frequency.

2. The method for controlling the output torque of a permanent magnet synchronous motor based on bus current reconstruction according to claim 1, wherein The busbar current I is reconstructed based on the obtained three-phase currents dc and the DC power P of the permanent magnet synchronous motor is calculated dc The specific steps are as follows: After obtaining the bus voltage U dc then multiply the bus current I dc by the bus voltage U dc to obtain the DC power P of the permanent magnet synchronous motor dc .

3. The method for controlling the output torque of a permanent magnet synchronous motor based on bus current reconstruction according to claim 1, wherein The said based on the DC power P dc , and obtaining the corrected output torque T of the permanent magnet synchronous motor based on the loss power P1 and the loss power P2 e The specific steps are as follows: Subtract the loss power P1 and the loss power P2 from the DC power P to obtain the corrected output mechanical power P of the permanent magnet synchronous motor dc e ;​ According to the ratio of the output mechanical power P e to the obtained angular velocity ω of the rotor of the permanent magnet synchronous motor, the corrected output torque T of the permanent magnet synchronous motor is obtained e .

4. The method for controlling the output torque of a permanent magnet synchronous motor based on bus current reconstruction according to claim 1, wherein Wherein, The IGBT switch satisfies the conditions: The turn-on time is equal to the turn-off time of the IGBT; And when the IGBT is in the on state, the current change rate between the gate and the corresponding emitter in the IGBT is equal to the voltage change rate.

5. The method for controlling the output torque of a permanent magnet synchronous motor based on bus current reconstruction according to claim 1, wherein The loss power P2 further includes the IGBT conduction internal resistance loss power P 22 and the IGBT conduction voltage drop loss power P 23 , and the specific steps for determining the loss power P2 of the permanent magnet synchronous motor include: Determine the on-resistance and on-state voltage drop; The IGBT conduction internal resistance loss power P is calculated based on the effective value of the three-phase current and the conduction internal resistance 22 ; The IGBT conduction voltage drop loss power P is calculated based on the effective value of the three-phase current and the conduction voltage drop 23 .

6. The method for controlling the output torque of a permanent magnet synchronous motor based on bus current reconstruction according to claim 1, wherein, Wherein, The IGBT conduction satisfies the conditions: The on-state voltage drop of the diode connected in anti-parallel with the IGBT is the same as the on-state voltage drop, and the on-resistance is the same as the on-resistance.

7. The method for controlling the output torque of a permanent magnet synchronous motor based on bus current reconstruction according to claim 1, characterized in that, The loss power P1 includes the copper loss power P 11 , and the specific steps for determining the copper loss power P 11 are as follows: Solve for the effective value of the three-phase current and calculate the copper loss power P based on the resistance value R of the three-phase winding of the permanent magnet synchronous motor 11 11 .​ 8. The method for reconstructing and controlling the output torque of a permanent magnet synchronous motor based on busbar current as claimed in claim 6, wherein The loss power P1 further includes the iron loss power P 12 , and the specific steps for determining the iron loss power P 12 include: According to the effective value of the three-phase current and the rotational speed N of the permanent magnet synchronous motor 12 the iron loss power P is calculated 12 .

Images