A method for estimating the position of a PMSG non-controlled rectifier based on a quasi-resonant extended state observer

Abstract

The application relates to a PMSG non-controlled rectification position estimation method based on a quasi-resonant extended state observer, and relates to the technical field of motor position sensorless control. According to current sampling information under the non-controlled rectification state, the motor static shaft system voltage is calculated, a quasi-resonant controller QR is embedded in view of the low-pass filtering characteristics and the problem of being easily disturbed by low-frequency disturbance existing in the traditional linear extended state observer ESO, so that an improved quasi-resonant extended state observer QR-ESO is obtained, the current and the calculated voltage are input into the observer, the motor back electromotive force is observed, and the motor position information is obtained through a phase-locked loop PLL. On the basis of the diode rectification model method, the static shaft system voltage is calculated by using the sampling current under the non-controlled rectification state, the motor back electromotive force information is observed by using the voltage and the sampling current in combination with the quasi-resonant extended state observer, the rotor position information is synchronously obtained, the estimation precision is high, and the grid-connected surge current is reduced.

Description

Technical Field

[0001] This invention relates to the field of sensorless motor control technology, specifically a PMSG uncontrolled rectifier position estimation method based on a quasi-resonant extended state observer. Background Technology

[0002] Permanent magnet synchronous generators (PMSGs) are widely used in new energy power generation and industrial drives due to their advantages such as high power density, high operating efficiency, and reliable structure. Rotor position information is a necessary condition for achieving high-performance closed-loop control of PMSGs. However, in some applications with harsh installation environments and limited sensor installation, the use of mechanical position sensors is restricted. Therefore, sensorless control technology for PMSGs has become a key research focus in the industry, and the starting problem of sensorless motor control is one of the core key aspects of this technology.

[0003] Currently, commonly used position acquisition methods for sensorless start-up of permanent magnet synchronous generators mainly include phase voltage detection, high-frequency voltage injection, zero-voltage pulse injection, and diode rectification model methods. Among these, phase voltage detection requires additional voltage sensors to sample the motor phase voltage, increasing system hardware costs. High-frequency voltage injection obtains position information by injecting high-frequency voltage and extracting the high-frequency current response, but it is only suitable for low-speed motor applications and cannot adapt to high-speed conditions. Zero-voltage pulse injection requires injecting zero-voltage pulses into the motor and estimating position information through short-circuit current response; however, excessively high short-circuit current amplitudes can easily burn out the driver, posing a safety hazard. Furthermore, these methods only acquire motor position information and cannot simultaneously estimate the motor back EMF, making it difficult to meet the requirements for smooth grid connection during motor start-up. Additionally, the diode rectification model method obtains motor position information through current sampling information under uncontrolled rectification conditions, requiring no additional hardware; however, this method generally suffers from low position estimation accuracy and also struggles to simultaneously estimate the motor back EMF, failing to effectively reduce inrush current during grid connection.

[0004] To address the shortcomings of the existing technologies, the inventors conducted research based on the diode rectification model method and proposed a PMSG uncontrolled rectification position estimation method based on the quasi-resonant extended state observer QR-ESO. By combining the sampled current and calculated voltage with the improved observer, high-precision rotor position and motor back EMF information can be obtained simultaneously. Summary of the Invention

[0005] To address the shortcomings of the prior art, this invention provides a PMSG uncontrolled rectifier position estimation method based on a quasi-resonant extended state observer. Building upon the diode rectification model method, it calculates the stationary shaft voltage using the sampled current under uncontrolled rectification conditions. This voltage and sampled current are then combined with the quasi-resonant extended state observer to observe the motor back EMF information, simultaneously obtaining rotor position information. This method offers high estimation accuracy and helps reduce grid-connected inrush current.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A PMSG uncontrolled rectifier position estimation method based on a quasi-resonant extended state observer includes the following steps:

[0008] Step 1: Obtaining the voltage and current in a two-phase stationary coordinate system under uncontrolled rectification conditions:

[0009] The three-phase current of the permanent magnet synchronous generator under uncontrolled rectification is sampled, and the current components in the two-phase stationary α-β coordinate system are obtained through coordinate transformation. and Based on the diode rectification model, the conduction state of the diodes is determined by the sign of the three-phase currents, and the switching state of the diodes is described by the switching function. The voltage components in the two-phase stationary α-β coordinate system are then calculated. and ;

[0010] Step 2, Design of the Quasi-Resonant Controller QR:

[0011] Design a quasi-resonant controller QR with sinusoidal signal tracking capability, whose transfer function is:

[0012]

[0013] In the formula, This represents the gain of the quasi-resonant controller. This indicates the cutoff frequency of the quasi-resonant controller. This represents the resonant frequency of the quasi-resonant controller, and its value is equal to the estimated operating electric angular velocity of the motor.

[0014] Step 3: Construction of the quasi-resonant extended state observer QR-ESO:

[0015] By embedding the quasi-resonant controller QR designed in step 2 into the traditional linear extended state observer ESO, the quasi-resonant extended state observer QR-ESO is constructed, and its expression is:

[0016]

[0017] In the formula, This indicates the α-β axis current estimation error. Represents the α-β axis current components. Represents the observed values ​​of the α-β axis currents. This represents the observed back EMF of the α-β axis motor. Indicates the quadrature-axis inductance of the motor. Describes the differential operator. This indicates known disturbance terms in the system. Represents the α-β axis voltage components. Indicates the observer gain. This indicates the stator phase resistance of the motor;

[0018] Step 4: Motor back EMF observation and rotor position information extraction:

[0019] The current component obtained in step 1 and voltage components Input the quasi-resonant extended state observer QR-ESO constructed in step 3 to observe the motor back EMF in the two-phase stationary coordinate system. and The input is processed by the phase-locked loop (PLL) to obtain the estimated electrical angle of the motor rotor. Compared with the estimated speed Complete the position estimation under the uncontrolled rectification state of PMSG.

[0020] Furthermore, in step 1, the voltage component and Calculated using the following formula:

[0021]

[0022] In the formula, This represents the DC bus voltage of the rectifier circuit. This represents the switching variables corresponding to the three-phase bridge arms a, b, and c. The rules for the values ​​of these switching variables are as follows:

[0023]

[0024] in The sampling current is for the corresponding phase, and the sign of the current is determined using generator conventions.

[0025] Furthermore, in step 3, the observed back EMF transfer function of the quasi-resonant extended state observer QR-ESO is derived by combining the mathematical model of the motor as follows:

[0026]

[0027] In the formula, For the Laplace operator.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. This invention is based on the diode rectification model method, which does not require additional voltage sensors. The voltage components of the two-phase stationary coordinate system can be calculated only through current sampling information, thus reducing the system hardware cost.

[0030] 2. This invention embeds a quasi-resonant controller into a traditional linear extended state observer. The improved quasi-resonant extended state observer has bandpass filtering characteristics and high DC attenuation, which can effectively filter out the DC component and glitches in the calculated voltage and observe the motor back EMF with strong sinusoidal characteristics. At the same time, it solves the problems of low-pass filtering characteristics and susceptibility to low-frequency disturbances in the observation of back EMF by traditional linear extended state observers.

[0031] 3. This invention can simultaneously acquire the rotor position information and back EMF information of the motor. Under steady-state conditions, the estimated position accuracy is high, which can meet the requirements of controllable rectification starting of the generator. It helps to achieve a smooth transition from uncontrolled rectification to controllable rectification of the motor, reduce grid-connected surge current, and prevent the driver from burning out.

[0032] 4. This invention has good dynamic performance under sudden changes in motor speed. The position error can be quickly restored to the steady-state value after transient changes. At the same time, the observer bandwidth can be adjusted according to actual use requirements to adapt to different operating conditions.

[0033] 5. This invention can be implemented in standard digital control chips (such as DSP or FPGA) without additional hardware modifications. It is applicable to sensorless control of permanent magnet synchronous generators and permanent magnet starter systems and has high engineering application value. Attached Figure Description

[0034] Figure 1 This is a principle block diagram of the method of the present invention;

[0035] Figure 2 This is a waveform diagram of α-β axis voltage and current under steady-state operating conditions of the present invention, wherein part a) is the α-β axis current waveform and part b) is the calculated α-β axis voltage waveform;

[0036] Figure 3 This is a block diagram of the quasi-resonant controller QR in this invention;

[0037] Figure 4 This is a block diagram of the quasi-resonant extended state observer QR-ESO in this invention;

[0038] Figure 5 This is the observation of the back electromotive force transfer function in this invention. Bode plot;

[0039] Figure 6The diagram shows the observed back EMF and position waveforms under steady-state conditions in the embodiment, where part a) is the observed position and position error waveform, and part b) is the observed back EMF waveform.

[0040] Figure 7 This is a waveform diagram of the position error under the condition of sudden change in the speed of the prime mover in the embodiment. Detailed Implementation

[0041] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0042] A PMSG uncontrolled rectifier position estimation method based on a quasi-resonant extended state observer, its overall principle block diagram combined with Figure 1 As shown, the core is to calculate the stationary shaft voltage by sampling the current, combine this with the improved quasi-resonant extended state observer QR-ESO to observe the motor back EMF, and then use a phase-locked loop to solve for the rotor position and speed information. The specific implementation steps are as follows:

[0043] Step 1: Obtaining the voltage and current in the two-phase stationary coordinate system under uncontrolled rectification conditions;

[0044] First, sample the three-phase stator current of the permanent magnet synchronous generator under uncontrolled rectification conditions. , and The three-phase currents obtained from the sampling are transformed into coordinates to obtain the current components in the two-phase stationary α-β coordinate system. and .

[0045] Based on the diode rectification model, the conduction state of the corresponding bridge arm diodes is determined by the sign of the three-phase current. The switching functions describe the turn-on and turn-off states of the diodes. For an ideal diode rectifier circuit, the voltage components in the two-phase stationary α-β coordinate system... and Calculated using the following formula:

[0046]

[0047] In the formula, This represents the DC bus voltage of the rectifier circuit. This represents the switching variables corresponding to the three-phase bridge arms a, b, and c. The rules for the values ​​of these switching variables are as follows:

[0048]

[0049] It should be noted that the above currents are determined using generator conventions, and the sign of the currents should be carefully considered during voltage calculations.

[0050] The steady-state α-β axis current waveforms obtained in this step are combined with the calculated voltage waveforms. Figure 2 As shown, part a) represents the α-β axis current. and The waveform, part b) is the voltage calculated along the α-β axis. and The waveform shows that the two-phase calculated voltage is obtained by detecting the zero-crossing points of the three phases of the motor and performing algebraic calculations. However, for current sensors, the zero-crossing point detection itself is inaccurate, and the current may repeatedly cross the zero point, resulting in many spikes in the calculated voltage waveform. But as can be seen from the subsequent results, the spikes do not affect the effectiveness of the method of this invention.

[0051] Step 2: Design of the quasi-resonant controller QR;

[0052] To address the issues of low-pass filtering characteristics and susceptibility to low-frequency disturbances in traditional linear extended state observers (ESOs) for back EMF observation, this invention embeds a quasi-resonant controller (QR) into the traditional ESO to improve the observer's performance.

[0053] The quasi-resonant controller QR designed in this step has the ability to track sinusoidal signals. Its principle block diagram is combined with... Figure 3 As shown, the transfer function expression is:

[0054]

[0055] In the formula, This represents the gain of the quasi-resonant controller. This indicates the cutoff frequency of the quasi-resonant controller. This indicates the resonant frequency of the quasi-resonant controller.

[0056] In practical applications, the resonant frequency The value should be equal to the estimated operating electric angular velocity of the motor. ,Right now This is to achieve accurate tracking of the sinusoidal signal of the motor's back electromotive force.

[0057] Step 3: Construction of the Quasi-Resonant Extended State Observer (QR-ESO);

[0058] By embedding the quasi-resonant controller QR designed in step two into a traditional linear extended state observer (ESO), a quasi-resonant extended state observer QR-ESO is constructed. Its principle block diagram is combined with… Figure 4As shown, the mathematical expression for the quasi-resonant extended state observer QR-ESO is:

[0059]

[0060] In the formula, This indicates the α-β axis current estimation error. Represents the α-β axis current components. Represents the observed values ​​of the α-β axis currents. This represents the observed back EMF of the α-β axis motor. Indicates the quadrature-axis inductance of the motor. Describes the differential operator. This indicates known disturbance terms in the system. Represents the α-β axis voltage components. Indicates the observer gain. This indicates the stator phase resistance of the motor.

[0061] Based on the mathematical model of the permanent magnet synchronous generator, the transfer function of the observed back electromotive force (EMF) is derived using the quasi-resonant extended state observer (QR-ESO):

[0062]

[0063] In the formula, For the Laplace operator.

[0064] As can be seen from the above equation, the quasi-resonant extended state observer QR-ESO proposed in this invention is a third-order back EMF observer. The resonant frequency is selected... Observe the back electromotive force transfer function under different parameters. Bode diagram combined Figure 5 As shown in the Bode plot, the quasi-resonant extended state observer QR-ESO exhibits bandpass filtering characteristics in observing the back EMF. Its high DC attenuation effectively filters out the influence of DC bias in the voltage component under uncontrolled rectification, resulting in a higher sinusoidal observation of the back EMF. Consequently, it can effectively extract the motor's speed and position information.

[0065] Step 4: Motor back EMF observation and rotor position information extraction;

[0066] The two-phase stationary coordinate system current components obtained in step one and and voltage components and Input the quasi-resonant extended state observer QR-ESO constructed in step three, and through observer calculations, output the observed values ​​of the motor back EMF in the two-phase stationary coordinate system. and .

[0067] The observed back potential and The input is processed by the phase-locked loop (PLL), which tracks and calculates the phase to obtain the estimated electrical angle of the motor rotor. Compared with the estimated speed Thus, the back EMF observation and position estimation of the permanent magnet synchronous generator under uncontrolled rectification state are completed.

[0068] In summary, this invention calculates the stationary shaft voltage of the motor based on current sampling information under uncontrolled rectification. Addressing the low-pass filtering characteristics and susceptibility to low-frequency disturbances inherent in traditional linear extended state observers (ESOs) for back EMF observation, a quasi-resonant controller (QR) is embedded to obtain an improved quasi-resonant extended state observer (QR-ESO). The current and calculated voltage are input into the observer to observe the motor's back EMF, and the motor's position information is further obtained through a phase-locked loop (PLL). Subsequently, based on the obtained motor back EMF and position information, the sensorless starting problem of PMSG controlled rectification can be solved, and grid-connected inrush current can be reduced, preventing driver burnout.

[0069] Example

[0070] To verify the effectiveness of the method of the present invention, relevant experiments were conducted in this embodiment. The experimental conditions and results are as follows:

[0071] 1. Steady-state experimental verification

[0072] In the experiment, the prime mover speed was stabilized at 600 r / min. The quasi-resonant extended state observer QR-ESO of this invention was used to observe the back EMF and position of the motor, including the actual position of the generator. Estimated location Position error And estimating the back potential Waveform and steady-state experimental results combined Figure 6 As shown, part a) is the waveform of the observed position and position error. It can be seen that the peak-to-peak value of the estimated position error of the method of the present invention is 12.65°, which can meet the requirements of the generator controllable rectifier start-up; part b) is the waveform of the observed back EMF. It can be seen that although the calculated voltage of the uncontrolled rectifier has glitches and a considerable DC component, after being filtered by the observer of the present invention, a back EMF with strong sinusoidal characteristics can be observed, which verifies the effectiveness of the method of the present invention.

[0073] 2. Dynamic experimental verification

[0074] In the experiment, the prime mover speed was controlled to undergo a step change between 600 r / min-720 r / min-600 r / min. The quasi-resonant extended state observer QR-ESO of this invention was used to observe the back EMF and position of the motor. The dynamic experimental results were combined with... Figure 7 As shown in the waveform, it can be seen that, in order to enable the observer to obtain a sinusoidal back-EMF waveform with a large DC bias in the calculated voltage, the bandwidth selection of the filter and the observer is relatively conservative. Therefore, when the prime mover speed changes abruptly, the position error exhibits some transient changes, but it can still quickly recover to the steady-state value, demonstrating relatively good dynamic performance. In specific engineering applications, the bandwidth can be adjusted according to actual needs to achieve the desired control effect.

[0075] It should be noted that the method proposed in this invention can be implemented in standard digital control chips (such as DSP or FPGA) without additional hardware modifications. It is applicable to sensorless control of permanent magnet synchronous generators and permanent magnet starter generator systems, and can help the above generators achieve a smooth transition from uncontrolled rectification to controlled rectification, effectively reduce grid-connected inrush current, and prevent the driver from burning out.

[0076] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0077] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A PMSG uncontrolled rectifier position estimation method based on a quasi-resonant extended state observer, characterized in that: Includes the following steps: Step 1: Obtaining the voltage and current in a two-phase stationary coordinate system under uncontrolled rectification conditions: The three-phase current of the permanent magnet synchronous generator under uncontrolled rectification is sampled, and the current components in the two-phase stationary α-β coordinate system are obtained through coordinate transformation. and Based on the diode rectification model, the conduction state of the diodes is determined by the sign of the three-phase currents, and the switching state of the diodes is described by the switching function. The voltage components in the two-phase stationary α-β coordinate system are then calculated. and ; Step 2, Design of the Quasi-Resonant Controller QR: Design a quasi-resonant controller QR with sinusoidal signal tracking capability, whose transfer function is: In the formula, This represents the gain of the quasi-resonant controller. This indicates the cutoff frequency of the quasi-resonant controller. This represents the resonant frequency of the quasi-resonant controller, and its value is equal to the estimated operating electric angular velocity of the motor. Step 3: Construction of the quasi-resonant extended state observer QR-ESO: By embedding the quasi-resonant controller QR designed in step 2 into the traditional linear extended state observer ESO, the quasi-resonant extended state observer QR-ESO is constructed, and its expression is: In the formula, This indicates the α-β axis current estimation error. Represents the α-β axis current components. Represents the observed values ​​of the α-β axis current. This represents the observed back EMF of the α-β axis motor. Indicates the quadrature-axis inductance of the motor. Describes the differential operator. This indicates known disturbance terms in the system. Represents the α-β axis voltage components. Indicates the observer gain. This indicates the stator phase resistance of the motor; Step 4: Motor back EMF observation and rotor position information extraction: The current component obtained in step 1 and voltage components Input the quasi-resonant extended state observer QR-ESO constructed in step 3 to observe the motor back EMF in the two-phase stationary coordinate system. and The input is processed by the phase-locked loop (PLL) to obtain the estimated electrical angle of the motor rotor. Compared with the estimated speed Complete the position estimation under the uncontrolled rectification state of PMSG.

2. The PMSG uncontrolled rectifier position estimation method based on a quasi-resonant extended state observer according to claim 1, characterized in that: In step 1, the voltage component and Calculated using the following formula: In the formula, This represents the DC bus voltage of the rectifier circuit. This represents the switching variables corresponding to the three-phase bridge arms a, b, and c. The rules for the values ​​of these switching variables are as follows: in The sampling current is for the corresponding phase, and the sign of the current is determined using generator conventions.

3. The PMSG uncontrolled rectifier position estimation method based on a quasi-resonant extended state observer according to claim 1, characterized in that: In step 3, the observed back EMF transfer function of the quasi-resonant extended state observer QR-ESO is derived by combining the mathematical model of the motor as follows: In the formula, For the Laplace operator.

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