Predictive model and switching method for smooth switching of different pulse patterns

Abstract

The present application relates to DTP-PMSM pulse width modulation technical field, disclose a kind of for different pulse mode smooth switching prediction model, on the basis of the unified modeling of the output voltage of SVPWM and OPP pulse mode, with the current impact mathematical model of DTP-PMSM system in different pulse mode switching process and the current prediction model of DTP-PMSM system, current impact mathematical model is based on the voltage-current relationship of the ABC three-phase winding and XYZ three-phase winding of DTP-PMSM under two-phase rotating coordinate system Construction, current prediction model is based on the transfer function of DTP-PMSM system containing single L filter is established, and adopts bilinear discretization method to carry out discretization processing, ignore common-mode voltage component, obtain the current iterative calculation formula under two-phase rotating coordinate system.The present application also discloses a kind of for different pulse mode smooth switching method.The present application is used for different pulse mode smooth switching prediction model and switching method, minimizes the current impact when switching, improves system performance and reliability.

Description

Technical Field

[0001] This invention relates to the field of DTP-PMSM pulse width modulation technology, specifically to a prediction model and switching method for smooth switching between different pulse modes. Background Technology

[0002] The dual three-phase permanent magnet synchronous motor (DTP-PMSM) driven by a three-level active midpoint clamp converter has better harmonic characteristics than traditional SPWM and SVPWM when using optimized pulse pattern (OPP) as the modulation strategy at medium and high speeds. This helps to reduce harmonic losses, lower rotor temperature rise, and effectively improve the overall performance of the system.

[0003] However, during system operation, switching between different pulse modulation modes (such as between SVPWM and OPP, and between OPP modes with different carrier ratios) is unavoidable. However, when the number of OPP switching angles N>1, the optimal switching angle exhibits discontinuity within the modulation ratio range. The switching between these discontinuous switching angles, as well as the switching process between SVPWM synchronous modulation and OPP modes, can easily trigger significant current surges at the moment of switching, seriously threatening system reliability. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of the above-mentioned technologies by providing a prediction model and switching method for smooth switching between different pulse modes, minimizing the current surge during switching, and improving system performance and reliability.

[0005] To achieve the above objectives, the prediction model for smooth switching between different pulse modes involved in this invention includes, based on a unified modeling of the output voltage of SVPWM and OPP pulse modes, a mathematical model of current impact during the switching process of the DTP-PMSM system in different pulse modes and a current prediction model of the DTP-PMSM system. The mathematical model of current impact is constructed based on the voltage-current relationship of the ABC three-phase winding and the XYZ three-phase winding of the DTP-PMSM in a two-phase rotating coordinate system. The current prediction model is established based on the transfer function of the DTP-PMSM system including a single L filter, and is discretized using a bilinear discretization method, ignoring the common-mode voltage component, to obtain the iterative calculation formula of current in a two-phase rotating coordinate system.

[0006] Preferably, the unified modeling of the output voltage of SVPWM and OPP pulse mode is as follows: , In the formula, , , , , , These represent the output voltages of phases A, B, C, X, Y, and Z of the inverter, respectively. The voltage phase angle of the ABC three-phase windings. The voltage phase angle of the XYZ three-phase windings. U n Let n be the amplitude of the nth harmonic. Let the phase angle of the nth voltage harmonic be:

[0007] In the formula, It is the phase voltage within the period from 0 to 2π.

[0008] Preferably, in the mathematical model of current impact, the mathematical relationship between the output current and voltage of the ABC three-phase windings of the DTP-PMSM in a two-phase rotating coordinate system is as follows: , In the formula, For leakage inductance in the winding, For the dq axis principal self-inductance, For the self-inductance of a single L filter, It is a permanent magnet flux linkage. Let be the angle between the phase voltage vector of winding ABC and the d-axis. Electric angular velocity; , In the formula, This is the DC bus voltage. N The number of switching angles between 0° and 90° corresponds to a carrier ratio of 2. N +1, For the first i Switching angle of the next switching event Let be the phase angle of the nth voltage harmonic; Due to the voltage phase angle of the XYZ three-phase windings satisfy: , The current in the XYZ three-phase winding in a two-phase rotating coordinate system is: , Define current surge for: , in: , In the formula, This is the current reference value for the DTP-PMSM system. This refers to the predicted current value for the DTP-PMSM system. In a two-phase rotating coordinate system d shaft and q Reference value for shaft current.

[0009] Preferably, in the current prediction model, the system transfer function derived using a single L-filter is as follows: , in, The phase voltage vector of the DTP-PMSM. The phase current vector of the DTP-PMSM The resistor matrix of DTP-PMSM. The inductor matrix is ​​a DTP-PMSM. For a single L-filter, the resistor matrix is... For the inductor matrix of a single L filter, F For the electromotive force of the motor: , Using the bilinear discretization method, the system transfer function is discretized as follows: , in: , In the formula, T s For the iteration period, neglecting the common-mode voltage component, in the two-phase rotating coordinate system, we have: , in, This represents the output voltage vector of the inverter relative to its midpoint O. The current vector of the DTP-PMSM in a two-phase stationary coordinate system. Here is the Clarke transformation matrix: , in, If it is a 3rd order zero matrix, then The iterative calculation formula is: .

[0010] A method for smooth switching between different pulse modes involves using a prediction model for smooth switching between different pulse modes to calculate the current surge magnitude at different voltage phase angles within a 1 / 6 cycle length when switching pulse modes, obtaining the optimal ABC three-phase winding voltage phase angle when the current surge is minimized, and switching pulse modes when the ABC three-phase winding voltage phase angle of the dual three-phase permanent magnet synchronous motor is at the optimal ABC three-phase winding voltage phase angle.

[0011] Preferably, when the pulse mode is switched to OPP, the carrier ratio is switched synchronously.

[0012] Preferably, during prediction, the closed-loop control consists of speed control and current control, which in turn generates control commands. The modulation ratio and voltage phase angle are calculated based on the control commands, and the switching angle is obtained by looking up a table. Combined with the high-precision phase angle obtained by PLL reconstruction, pulse PWM2 is finally generated. At the same time, the control commands are processed by IPark and pulse PWM1 is generated by the SVPWM algorithm. Pulse PWM1 or pulse PWM2 controls the switching of the inverter power devices.

[0013] Preferably, define T c For the control period of the prediction model, T s For the iteration period, N 1 / 6 cycle length and T s The ratio, when switching to OPP, the swiPreFlag flag is valid, and the prediction and switching process includes the following steps: A) Each interval T c The system retrieves input parameters in time and initializes them accordingly. B) Based on the stator current sampling value i s and rotor position signal i e Calculate the current time t Current in a two-phase rotating coordinate system i dq ( t ); C) m =1,2,…, M , with step size oh e T s renew: i e ( m ), i 1( m ), i2( m ), oh e It is the electric angular frequency. i 1 represents the phase angle of the voltage of the ABC three-phase windings. i 2 represents the phase angle of the XYZ three-phase winding voltage; D) To switch to OPP, based on the optimal switching angle α to be used and i 1( m ), i 2( m Generate voltage pulses to obtain voltage vectors. Otherwise, based on the switching frequency F pwm The triangular carrier counter (trigCnt) and the rising or falling state of the triangular carrier (upOrDn) generate voltage pulses, thus obtaining the voltage vector. ; E) Calculate the motor electromotive force using a current prediction model F ( m ); F) Update the current vector of DTP-PMSM in the two-phase stationary coordinate system using the iterative current calculation formula in the two-phase rotating coordinate system. And calculate the current in the two-phase rotating coordinate system. i dq ( m ); G) Calculate current impact using a mathematical model of current impact. To record its maximum error E Max ; H) Update the smallest value within the most recent 1 / 6 cycle. E Max and the corresponding voltage vector angle i 0; I) Calculate the optimal phase angle of the ABC three-phase winding voltage. i * = i 0+60°; J) When the phase angle of the voltage of the three-phase windings ABC reaches i * Furthermore, if the pulse mode switching flag swiPreFlag is valid, that is, if a switch to OPP is required, the switching allow flag swiAllowFlag is set to 1 and the carrier ratio needs to be switched synchronously; otherwise, it is set to 0 and the carrier ratio is not switched.

[0014] Preferably, the table used for the lookup method and the selected PWM are determined by enabling the switching flag swiAllowFlag.

[0015] Compared with the prior art, the present invention has the following advantages: by predicting the magnitude of the current surge during the switching of different pulse modes, a switching strategy with the minimum current surge is formulated, thereby minimizing the current surge during switching, effectively suppressing the current surge, and improving system performance and reliability. Attached Figure Description

[0016] Figure 1 This is a block diagram of a DTP-PMSM system using a 3L-ANPC converter and an L filter in an embodiment of the present invention. Figure 2 This is a block diagram of the transfer function of a DTP-PMSM system using a single L filter in an embodiment of the present invention; Figure 3 This is a block diagram of the control algorithm for the DTP-PMSM drive system in an embodiment of the present invention. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0018] In the above implementation examples, the descriptions of each embodiment have different focuses. For parts that are not described or recorded in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0019] A prediction model for smooth switching between different pulse modes is proposed. Based on the unified modeling of the output voltage of SVPWM and OPP pulse modes, a mathematical model of current impact and a current prediction model of DTP-PMSM system during the switching process of different pulse modes are provided. The mathematical model of current impact is based on the voltage-current relationship of the ABC three-phase winding and XYZ three-phase winding of DTP-PMSM in a two-phase rotating coordinate system. The current prediction model is based on the transfer function of DTP-PMSM system including a single L filter and is discretized by a bilinear discretization method. The common-mode voltage component is ignored, and the iterative calculation formula of current in the two-phase rotating coordinate system is obtained.

[0020] The unified modeling of the output voltage for SVPWM and OPP pulse modes is as follows: , In the formula, , , , , , These represent the output voltages of phases A, B, C, X, Y, and Z of the inverter, respectively. The voltage phase angle of the ABC three-phase windings. The voltage phase angle of the XYZ three-phase windings. Un Let n be the amplitude of the nth harmonic. Let the phase angle of the nth voltage harmonic be:

[0021] In the formula, It is the phase voltage within the period from 0 to 2π.

[0022] Specifically, for the mathematical model of current impact, such as Figure 1 The diagram shows a DTP-PMSM system block diagram using a 3L-ANPC converter and an L-filter. The DTP-PMSM consists of ABC windings and XYZ windings. Both sets of windings are Y-connected with isolated, ungrounded center points. The windings in each set of three-phase windings are spatially 120° apart, with phase A leading phase X by 30°. Based on the voltage-current relationship of the topology, the 1 / 4 cycle symmetry of the OPP voltage waveform, and the half-wave symmetry of the SVPWM synchronous modulation voltage waveform, the mathematical relationship between the output current and voltage of the ABC three-phase windings of the DTP-PMSM in a two-phase rotating coordinate system can be derived as follows: , In the formula, For leakage inductance in the winding, For the dq axis principal self-inductance, For the self-inductance of a single L filter, It is a permanent magnet flux linkage. Let be the angle between the phase voltage vector of winding ABC and the d-axis. Electric angular velocity; , In the formula, This is the DC bus voltage. N The number of switching angles between 0° and 90° corresponds to a carrier ratio of 2. N +1, For the first i Switching angle of the next switching event Let be the phase angle of the nth voltage harmonic; Due to the voltage phase angle of the XYZ three-phase windings satisfy: , The current in the XYZ three-phase winding in a two-phase rotating coordinate system is: , Define current surge for: , in: , In the formula, This is the current reference value for the DTP-PMSM system. This refers to the predicted current value for the DTP-PMSM system. In a two-phase rotating coordinate system d shaft and q Reference value for shaft current.

[0023] For current prediction models, such as Figure 2 As shown, the system transfer function using a single L-filter is derived as follows: , in, The phase voltage vector of the DTP-PMSM. The phase current vector of the DTP-PMSM The resistor matrix of DTP-PMSM. The inductor matrix is ​​a DTP-PMSM. For a single L-filter, the resistor matrix is... For the inductor matrix of a single L filter, F For the electromotive force of the motor: , Using the bilinear discretization method, the system transfer function is discretized as follows: , in: , In the formula, T s For the iteration period, neglecting the common-mode voltage component, in the two-phase rotating coordinate system, we have: , in, This represents the output voltage vector of the inverter relative to its midpoint O. The current vector of the DTP-PMSM in a two-phase stationary coordinate system. Here is the Clarke transformation matrix: , in, If it is a 3rd order zero matrix, then The iterative calculation formula is: .

[0024] Another method for smooth switching between different pulse modes involves using the prediction model for smooth switching between different pulse modes to calculate the current surge magnitude at different voltage phase angles within 1 / 6 cycle length when switching pulse modes, and obtaining the optimal ABC three-phase winding voltage phase angle when the current surge is minimized. When the ABC three-phase winding voltage phase angle of the dual three-phase permanent magnet synchronous motor is at the optimal ABC three-phase winding voltage phase angle, the pulse mode is switched.

[0025] When the pulse mode is switched to OPP, the carrier ratio is switched synchronously.

[0026] When making predictions, such as Figure 3 The diagram shown is a block diagram of the control algorithm for the DTP-PMSM drive system. The closed-loop control consists of speed control and current control, which in turn yields control commands. According to control commands The modulation ratio m and voltage phase angle θ are calculated, the switching angle α is obtained by looking up a table, and combined with the high-precision phase angle obtained by PLL reconstruction, the final pulse PWM2 is generated, and the control command is simultaneously processed. IPark is performed and pulse PWM1 is generated using the SVPWM algorithm. Pulse PWM1 or pulse PWM2 controls the switching on and off of the inverter power devices.

[0027] In this embodiment, the input and output parameters for different pulse mode switching algorithms are defined in the following table:

[0028] Combination Figure 3 As shown, the control algorithm of the DTP-PMSM drive system is as follows: First define... T c For the control period of the prediction model, T s For the iteration period, N 1 / 6 cycle length and T s The ratio, when switching to OPP, the swiPreFlag flag is valid, and the prediction and switching process includes the following steps: A) Each interval T c The system retrieves input parameters in time and initializes them accordingly. B) Based on the stator current sampling value i s and rotor position signal i e Calculate the current time t Current in a two-phase rotating coordinate system i dq ( t ); C) m =1,2,…, M , with step size oh e T s renew: i e ( m ), i 1( m ), i 2( m ), oh e It is the electric angular frequency. i 1 represents the phase angle of the voltage of the ABC three-phase windings. i 2 represents the phase angle of the XYZ three-phase winding voltage; D) To switch to OPP, based on the optimal switching angle α to be used and i 1( m ), i 2( m Generate voltage pulses to obtain voltage vectors. Otherwise, based on the switching frequency F pwm The triangular carrier counter (trigCnt) and the rising or falling state of the triangular carrier (upOrDn) generate voltage pulses, thus obtaining the voltage vector. ; E) Calculate the motor electromotive force using a current prediction model F ( m ); F) Update the current vector of DTP-PMSM in the two-phase stationary coordinate system using the iterative current calculation formula in the two-phase rotating coordinate system. And calculate the current in the two-phase rotating coordinate system. i dq ( m ); G) Calculate current impact using a mathematical model of current impact. To record its maximum error E Max ; H) Update the smallest value within the most recent 1 / 6 cycle. E Max and the corresponding voltage vector angle i 0; I) Calculate the optimal phase angle of the ABC three-phase winding voltage. i * = i 0+60°; J) When the phase angle of the voltage of the three-phase windings ABC reaches i *Furthermore, if the pulse mode switching flag swiPreFlag is valid, that is, if a switch to OPP is required, the switching allow flag swiAllowFlag is set to 1 and the carrier ratio needs to be switched synchronously; otherwise, it is set to 0 and the carrier ratio is not switched.

[0029] Specifically, the table used for the lookup method and the selected PWM are determined by enabling the switching flag swiAllowFlag.

[0030] This invention provides a prediction model and switching method for smooth switching between different pulse modes. By predicting the magnitude of the current surge during the switching of different pulse modes, a switching strategy with the minimum current surge is formulated, thereby minimizing the current surge during switching, effectively suppressing the current surge, and improving system performance and reliability.

[0031] The embodiments described above are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the embodiments described above, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A prediction model for smooth switching between different pulse modes, characterized in that: Based on the unified modeling of the output voltage of SVPWM and OPP pulse modes, a mathematical model of current impact and a current prediction model of DTP-PMSM system during the switching process of different pulse modes are set. The mathematical model of current impact is based on the voltage-current relationship of the ABC three-phase winding and XYZ three-phase winding of DTP-PMSM in a two-phase rotating coordinate system. The current prediction model is based on the transfer function of DTP-PMSM system including single L filter and is discretized by bilinear discretization method. Common mode voltage component is ignored to obtain the current iterative calculation formula in two-phase rotating coordinate system. The unified modeling of the output voltage for SVPWM and OPP pulse modes is as follows: ， In the formula, , , , , , These represent the output voltages of phases A, B, C, X, Y, and Z of the inverter, respectively. The voltage phase angle of the ABC three-phase windings. The voltage phase angle of the XYZ three-phase windings. U n Let n be the amplitude of the nth harmonic. Let the phase angle of the nth voltage harmonic be: In the formula, The phase voltage within the period from 0 to 2π; In the mathematical model of current impact, the mathematical relationship between the output current and voltage of the ABC three-phase windings of the DTP-PMSM in a two-phase rotating coordinate system is as follows: ， In the formula, For leakage inductance in the winding, For the dq axis principal self-inductance, For the self-inductance of a single L filter, It is a permanent magnet flux linkage. Let be the angle between the phase voltage vector of winding ABC and the d-axis. Electric angular velocity, A coefficient related to inductance parameters. Let be the d-axis current of the ABC winding in the dq rotating coordinate system. Let be the q-axis current of the ABC winding in the dq rotating coordinate system; ， Due to the voltage phase angle of the XYZ three-phase windings satisfy: ， The current in the XYZ three-phase winding in a two-phase rotating coordinate system is: ， Define current surge for: ， in: ， In the formula, This is the current reference value for the DTP-PMSM system. This refers to the predicted current value for the DTP-PMSM system. In a two-phase rotating coordinate system d shaft and q Shaft current reference value, Let XYZ be the d-axis current of the winding in the dq rotating coordinate system. Let q be the q-axis current of the XYZ winding in the dq rotating coordinate system; In the current prediction model, the system transfer function using a single L-filter is derived as follows: ， in, The phase voltage vector of the DTP-PMSM. The phase current vector of the DTP-PMSM The resistor matrix of DTP-PMSM. The inductor matrix is ​​a DTP-PMSM. For a single L-filter, the resistor matrix is... For the inductor matrix of a single L filter, F For the electromotive force of the motor: ， Given the rotor position signal, using the bilinear discretization method, the system transfer function is discretized as follows: ， in: ， In the formula, T s For the iteration period, neglecting the common-mode voltage component, in the two-phase rotating coordinate system, we have: ， in, This represents the output voltage vector of the inverter relative to its midpoint O. The current vector of the DTP-PMSM in a two-phase stationary coordinate system. Here is the Clarke transformation matrix: ， in, If it is a 3rd order zero matrix, then The iterative calculation formula is: 。 2. A method for smooth switching between different pulse modes, characterized in that: When different pulse modes are to be switched, the current impact magnitude when switching pulse modes is calculated using the prediction model for smooth switching of different pulse modes as described in claim 1 within 1 / 6 cycle length at different voltage phase angles. The optimal ABC three-phase winding voltage phase angle is obtained when the current impact is minimized. When the ABC three-phase winding voltage phase angle of the dual three-phase permanent magnet synchronous motor is at the optimal ABC three-phase winding voltage phase angle, the pulse mode is switched.

3. The method for smooth switching between different pulse modes as described in claim 2, characterized in that: When the pulse mode is switched to OPP, the carrier ratio is switched synchronously.

4. The method for smooth switching between different pulse modes as described in claim 2, characterized in that: During prediction, the closed-loop control consists of speed control and current control, which in turn generates control commands. Based on the control commands, the modulation ratio and voltage phase angle are calculated, and the switching angle is obtained by looking up a table. Combined with the high-precision phase angle obtained by PLL reconstruction, pulse PWM2 is finally generated. At the same time, the control commands are processed by IPark and pulse PWM1 is generated through the SVPWM algorithm. Pulse PWM1 or pulse PWM2 controls the switching of the inverter power devices.

5. The method for smooth switching between different pulse modes as described in claim 4, characterized in that: definition T c For the control period of the prediction model, T s For the iteration period, N 1 / 6 cycle length and T s The ratio, when switching to OPP, the swiPreFlag flag is valid, and the prediction and switching process includes the following steps: A) Each interval T c The system acquires input parameters in real time and initializes them accordingly. B) Based on the stator current sampling value i s and rotor position signal θ e Calculate the current time t Current in a two-phase rotating coordinate system i dq ( t ); C) m =1,2,…, M , with step size ω e T s renew: θ e ( m ), θ 1( m ), θ 2( m ), ω e It is the electric angular frequency. θ 1 represents the phase angle of the voltage of the ABC three-phase windings. θ 2 represents the phase angle of the XYZ three-phase winding voltage; D) To switch to OPP, based on the optimal switching angle α to be used and θ 1( m ), θ 2( m Generate voltage pulses to obtain voltage vectors. Otherwise, based on the switching frequency F pwm The triangular carrier counter (trigCnt) and the rising or falling state of the triangular carrier (upOrDn) generate voltage pulses, thus obtaining the voltage vector. ; E) Calculate the motor electromotive force using a current prediction model F ( m ); F) Update the current vector of DTP-PMSM in the two-phase stationary coordinate system using the iterative current calculation formula in the two-phase rotating coordinate system. And calculate the current in the two-phase rotating coordinate system. i dq ( m ); G) Calculate current impact using a mathematical model of current impact. To record its maximum error E Max ; H) Update the smallest value within the most recent 1 / 6 cycle. E Max and the corresponding voltage vector angle θ 0; I) Calculate the optimal phase angle of the ABC three-phase winding voltage. θ = θ 0 + 60°; J) When the phase angle of the voltage of the three-phase windings ABC reaches θ Furthermore, if the pulse mode switching flag swiPreFlag is valid, that is, if a switch to OPP is required, the switching allow flag swiAllowFlag is set to 1 and the carrier ratio needs to be switched synchronously; otherwise, it is set to 0 and the carrier ratio is not switched.

6. The method for smooth switching between different pulse modes as described in claim 5, characterized in that: The table used for the lookup method and the selected PWM are determined by the swiAllowFlag flag.

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