A method for precise compensation of dead zone of SVPWM based on phase marker of oscilloscope

Abstract

The present application relates to the technical field of power electronics and motor control, and particularly relates to a SVPWM dead zone accurate compensation method based on an oscilloscope phase marker, comprising: in a frequency converter control software, setting a compensation angle to 0, and inserting an IO conversion flag bit at a 0 phase of a U phase wave; running the frequency converter, observing a position of the flag bit in a U phase current through an oscilloscope, and obtaining a position angle as the compensation angle; adding the compensation angle to the software to obtain a current compensation angle as: an angle of an output voltage waveform + an output current angle + the compensation angle; running the frequency converter again, observing the position of the flag bit in the U phase current through the oscilloscope, and judging whether the position is on a 0 phase angle of the current. The present application directly finds and determines an optimal compensation angle through an oscilloscope, so as to realize accurate compensation of a SVPWM dead zone.

Description

Technical Field

[0001] This invention relates to the technical field of power electronics and motor control, and in particular to a method for accurate compensation of SVPWM dead time based on oscilloscope phase marking. Background Technology

[0002] With the continuous improvement of microprocessor computing power and IGBT / MOS switching device performance, PWM-based voltage source converters are widely used in frequency converters, servo drives, inverters, new energy vehicle traction, and rail transit traction. Among them, space vector modulation (SVPWM) has become the mainstream solution due to its high DC bus utilization and controllable harmonic spectrum distribution. In three-phase half-bridge control, the upper and lower bridge arms are complementary drives. To avoid shoot-through of the same arm, a dead time must be introduced between drive pulses. However, the dead time introduces the average output voltage vector deviation and zero displacement, causing devices that should be turned on to fail to turn on for a short time and devices that should be turned off to fail to turn off for a short time. This is especially true at low frequencies, light loads, and near the current zero crossing, manifesting as phase current distortion and torque. Problems such as pulsation and low-speed creep exist; this deviation is related to device turn-on / turn-off delay, reverse recovery, temperature, bus voltage, load inductance, and parasitic parameters of the drive circuit, exhibiting significant nonlinearity and time-varying characteristics; traditional compensation paths mainly include: current-type feedback compensation based on current polarity, voltage-type feedback compensation based on output voltage estimation, and indirect compensation by extracting dead-zone error through high-frequency pulses; the above methods usually require the establishment of equivalent models and compensation transformation formulas that include device and load parameters, resulting in long algorithm chains and strong parameter sensitivity; furthermore, the synchronous calibration of compensation amount and compensation angle / phase is difficult, and the actual waveform angle, sampling delay, and zero-crossing drift can cause inaccurate selection of compensation corner points, leading to high debugging costs and poor reproducibility.

[0003] CN104065258A discloses a dead-time compensation method for SVPWM waveforms in frequency converters. This method determines the voltage space vector and current direction to concentrate the dead-time effect on the upper or lower bridge, and distinguishes between parts that need compensation and those that do not by calculating the current polarity. It also uses a freewheeling diode to advance or delay the dead-time. Although this method is relatively simple to implement and has low requirements for chip processing speed, its compensation accuracy is limited by the judgment of current polarity. Under low-speed and light-load conditions, the current signal is weak and easily affected by noise interference, resulting in poor compensation effect and inability to achieve accurate compensation.

[0004] CN111697897A discloses a dead-time compensation method for motor controllers based on predicted current. This method collects and predicts the instantaneous three-phase current of the motor, transforms the predicted current to the dq axis, and then calculates the dead-time error voltage compensation duty cycle. Although this method improves the real-time performance of compensation by predicting current, its algorithm is complex and computationally intensive, which places high demands on the processing performance of the controller. More importantly, these existing technical solutions all rely on complex mathematical models and internal parameter calculations, making it difficult to adjust and verify them intuitively.

[0005] Therefore, existing technologies have the following problems: complex algorithms, large computational load, and high hardware resource requirements; compensation accuracy is limited by the quality of the current signal, especially under low-speed and light-load conditions, the compensation effect is poor; and there is a lack of intuitive debugging and verification methods, making it difficult to perform accurate parameter correction in practical applications. In response to the problems of computational complexity, inaccurate compensation, and lack of intuitive debugging methods in existing dead-zone compensation methods, this invention proposes a precise SVPWM dead-zone compensation method based on oscilloscope phase marking. The aim is to use an oscilloscope to intuitively find and determine the optimal compensation angle, thereby achieving precise compensation of the SVPWM dead zone. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section, as well as in the abstract and title of the present application, to avoid obscuring the purpose of this section, the abstract and title of the invention. Such simplifications or omissions shall not be used to limit the scope of the present invention.

[0007] In view of the aforementioned existing problems, the present invention is proposed.

[0008] To solve the above technical problems, the present invention provides the following technical solution: Step S1: In software control, the compensation angle is set to 0, and the flag bit of IO transformation is inserted in the 0 phase of the U-phase wave.

[0009] Step S2: Run the frequency converter and observe the position of the flag in the U-phase current using an oscilloscope. The position angle obtained is the compensation angle.

[0010] Step S3: Add the compensation angle to the software to obtain the current compensation angle as: the angle of the output voltage waveform + the angle of the output current + the compensation angle;

[0011] Step S4: Run the inverter again and observe the position of the flag bit in the U-phase current using the oscilloscope to determine whether the position is at the 0-phase angle of the current.

[0012] If so, then the position at the 0-phase angle of the current is the dead zone compensation angle;

[0013] If not, continue to adjust the current compensation angle value and repeat step S3 until the flag is at the 0-point phase of the current waveform.

[0014] The beneficial effects of this invention are as follows: This invention achieves direct, fast, and accurate calibration of the dead zone compensation angle. On the one hand, it transforms the traditional compensation problem, which requires a fine model and multi-parameter identification, into a visualized phase alignment problem, significantly reducing computational complexity and parameter sensitivity. On the other hand, the compensation angle is calibrated in a closed loop under real operating conditions, which can fully absorb the combined errors of device dynamic characteristics and control link delay. Therefore, it reduces the THD of low-frequency and light-load current, reduces torque ripple, reduces the risk of zero-crossing oscillation and DC bias, and improves the controllability of weak magnetic region and low-speed creeping conditions. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0016] Figure 1 This is a flowchart illustrating the SVPWM dead-time accurate compensation method based on oscilloscope phase markers as shown in this invention.

[0017] Figure 2 The current waveform diagram of dead-zone-free compensation shown in this invention is shown.

[0018] Figure 3 The waveform diagrams of the upper and lower bridge arms under the ideal state shown in this invention are as follows;

[0019] Figure 4 This is a schematic diagram of the Clark transformation process shown in this invention;

[0020] Figure 5 This is a schematic diagram illustrating the process of converting three-phase current into a controllable d / d current as shown in this invention.

[0021] Figure 6 This is a waveform diagram of the output current of the insertion flag bit when the insertion angle is -90° as shown in this invention;

[0022] Figure 7 This is the output current waveform diagram of the inserted flag bit when the dead zone compensation angle is 0, as shown in this invention.

[0023] Figure 8 This is a schematic diagram of the no-load current output before 5Hz compensation as shown in this invention;

[0024] Figure 9 This is a waveform diagram of the output current after dead-zone compensation as shown in this invention;

[0025] Figure 10 The waveform of the rated 50Hz output current after dead-zone compensation is shown in the present invention. Detailed Implementation

[0026] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0027] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort should fall within the scope of protection of this invention.

[0028] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0029] It should be noted that the purpose of dead time is to allow for early turn-off when the MOSFET or IGBT is on, and to delay turn-on when the MOSFET or IGBT is off. This effectively avoids shoot-through between the upper and lower bridge arms due to turn-on or turn-off delays. However, due to the addition of dead time, some transistors that should be on are not, and some that should be off are not. This inevitably leads to a higher distortion rate in the current waveform when the motor is driven or the inverter load is light. Figure 2 This is the current waveform of the EV520 series frequency inverter at 5Hz without dead-time compensation. Figure 3 These are the waveforms of the upper and lower bridge arms under theoretical and ideal conditions.

[0030] Traditional dead-zone compensation methods include current-type feedback dead-zone compensation, voltage-type feedback dead-zone compensation, and dead-zone compensation based on high-frequency pulse extraction. These methods are often accompanied by complex compensation conversion formulas, making the entire compensation calculation obscure and difficult to understand. At the same time, due to the selection of the compensation angle point and the actual PWM waveform angle, it is difficult to accurately find a suitable compensation angle, making dead-zone compensation extremely difficult. Therefore, the core of dead-zone compensation lies in determining the compensation angle and the compensation amount.

[0031] According to an embodiment of the present invention, in combination Figure 1The flowchart shown illustrates a precise SVPWM dead-time compensation method based on oscilloscope phase markers, which specifically includes the following steps:

[0032] Step S1: In software control, set the compensation angle to 0 and insert the IO transformation flag bit at the 0 phase of the U-phase wave. Note that the following points should be noted in this step:

[0033] In the inverter control software, the dead zone compensation angle parameter is initialized to... ;

[0034] In the SVPWM algorithm, the zero-phase point of the U-phase output voltage modulation waveform is located, denoted as... ;

[0035] exist At the corresponding interrupt point, a digital I / O signal that can be captured externally is output. The I / O signal switches from high level to low level or from low level to high level at the 0 phase point, which serves as a flag bit that can be triggered by an oscilloscope.

[0036] Furthermore, the flags include:

[0037] Set the idle general-purpose I / O pins of the frequency converter to digital output mode;

[0038] In the main loop of the SVPWM algorithm, the U-phase output voltage modulation waveform is determined. phase angle Does it meet the requirements? or ;

[0039] When the trigger condition is met, the level state of the I / O pin is toggled and maintained for a preset pulse width. It then returns to its initial level to form a narrow pulse.

[0040] In a preferred embodiment, the U-phase output voltage modulation waveform is determined in the main loop of the SVPWM algorithm. phase angle Methods to determine if the triggering conditions are met include:

[0041] right The voltage reference component in the coordinate system is obtained by smoothing preprocessing. This smoothing uses an exponential moving average:

[0042]

[0043] in, For smoothing coefficients;

[0044] Calculate phase and amplitude:

[0045]

[0046]

[0047] And Normalized to the value by the wrap(⋅) function ;

[0048] Set an amplitude threshold, only when Phase determination is allowed at this time, where The preset ratio for the per-unit value of the DC bus;

[0049] Set an angled window with hysteresis, To trigger tolerance, To release tolerance and satisfy Defined separately:

[0050]

[0051] when When the trigger state is set to 0, Release the 0-triggered state at time;

[0052] when When the π trigger state is set, Release the π-triggered state at time;

[0053] Set the rotation direction and persistence criterion: Calculate ,when Confirmation is only made when the rotation direction is consistent with the desired direction and the condition is met for Q consecutive sampling periods within the window. or ;

[0054] When there is a fixed delay between sampling and updating At that time, feedforward compensation is used to correct the judgment:

[0055]

[0056] and with Alternative Participate in the above steps;

[0057] After confirmation or After the event, the I / O pin is toggled during the current control interrupt and the preset pulse width is maintained. This serves as a flag output that can be triggered by an oscilloscope.

[0058] in, , for The voltage reference component at the k-th sampling time in the coordinate system. , To , The smoothed component after performing an exponential moving average (EMA), where k is the index of the discrete sampling / control period. For the reference voltage vector in Instantaneous electrical phase angle in coordinate system For the reference voltage vector magnitude, Let be the angle normalization function. , The phase deviations are represented by the angular differences relative to 0 and relative to π, respectively. , The trigger / release threshold for the angular hysteresis window. Let Q be the discrete phase increment, and let Q be the sample size threshold for the persistence criterion. For electrical frequency, For electrical angular velocity, To account for the predicted phase with a fixed time delay, For reference amplitude threshold, This is the pulse width for the I / O flag bit.

[0059] Step S2: Run the frequency converter and observe the position of the flag bit in the U-phase current using an oscilloscope. The position angle obtained is the compensation angle. Note that the following should be noted in this step:

[0060] Connect oscilloscope channel CH1 to the U-phase current sensor output to observe the U-phase current. Connect channel CH2 to the I / O flag signal;

[0061] Set CH2 edge triggering as an external trigger source and collect at least one electrical cycle;

[0062] Measuring the trigger time of the CH2 flag The most recent zero-crossing moment of the U-phase current Time difference between ;

[0063] Based on the output frequency of the frequency converter Calculate the time difference The corresponding phase angle is used as the initial compensation angle. :

[0064]

[0065] And through the angle normalization function Constrain it to :

[0066]

[0067] Will As the initial compensation angle measurement value For subsequent compensation;

[0068] in, For the instantaneous current of phase U, It refers to the electrical frequency.

[0069] Step S3: Add the compensation angle to the software to obtain the current compensation angle as: output voltage waveform angle + output current angle + compensation angle. Note that the following should be noted in this step:

[0070] Will Write control software parameters ;

[0071] In each control cycle, the instantaneous voltage is obtained through Clarke / Park transformation. With current ,calculate ;

[0072] The current compensation angle is obtained according to the following formula and used to correct the SVPWM reference phase or sampling / update timing:

[0073]

[0074] When there is a fixed delay At that time, introduce Compensation will be provided.

[0075]

[0076] in, From the current compensation perspective, Let be the angle normalization function. The instantaneous phase angle for reference to the output voltage. It is the arctangent function in the fourth quadrant. The instantaneous phase angle of the output current. For dead zone compensation angle, Phase quantization for fixed equivalent time delay.

[0077] Step S4: Run the inverter again and observe the position of the flag bit in the U-phase current using an oscilloscope to determine if the position is at the 0-phase angle of the current.

[0078] The current compensation angle obtained from loading And restart the frequency converter;

[0079] Use the oscilloscope again to observe the I / O flag signal and the U-phase current waveform simultaneously;

[0080] By observing the alignment between the trigger point of the I / O flag signal and the zero-crossing point of the U-phase current waveform, and calculating the new time difference between them. ;

[0081] like ≤Preset error threshold If so, the compensation is successful. This is the final dead zone compensation angle; stop adjusting.

[0082] like >Error threshold If the compensation is inaccurate, it needs to be fine-tuned, i.e., based on the new time difference. Calculate the correction angle The calculation formula is:

[0083]

[0084] in, For electrical frequency, For the new time difference;

[0085] In the inverter control software, the original dead zone compensation angle parameter is... Add or subtract correction angle In order to obtain a new compensation perspective The direction of addition or subtraction depends on the new time difference. The positive and negative signs are determined, and then the inverter steps are run again. The above iterative process is repeated until the error threshold is met and the iteration stops.

[0086] In a preferred embodiment, based on the microprocessor clock frequency used by the inverter and SVPWM modulation frequency ,Will Set to satisfy a minimum SVPWM regulation period T min Among them, the minimum adjustment period T min Defined as 1 / With 1 / Integer multiples.

[0087] In a preferred embodiment, the method for determining the direction of addition or subtraction is as follows:

[0088] When the oscilloscope observes that the trigger point of the flag signal leads the zero-crossing point of the U-phase current, it indicates that the compensation amount is too large and needs to be reduced. The correction angle should be adjusted from the original dead-zone compensation angle parameter. Subtract from the middle;

[0089] When the oscilloscope observes that the trigger point of the flag signal lags behind the zero-crossing point of the U-phase current, it indicates that the compensation is insufficient and needs to be increased. The correction angle should be adjusted relative to the original dead-zone compensation angle parameter. Add them together.

[0090] In a preferred embodiment, the repeated iteration process specifically involves: obtaining a new compensation angle... Then, return the current compensation angle obtained from the loading process. This step involves re-running the inverter and observing until the new time difference is determined. Meets the error threshold The iteration stops when the time is right, and the final compensation angle is locked and saved to the inverter parameters.

[0091] Reference Figure 4 and Figure 5 This is a schematic diagram of the process of converting three-phase currents U, V, W into controllable d, q currents. First, it involves the Clark transformation, which converts the three-phase U, V, W currents into α and β currents, as shown below. Figure 4 The process from a) to b) can be expressed mathematically as follows:

[0092]

[0093] in, , , This corresponds to the output currents U, V, and W. This is the peak current. Output waveform angle / electrical angle;

[0094] Then, by performing the Park transformation on α and β, the dq-axis current can be obtained, which is... Figure 4 The process from b) to c) is as follows: Figure 5 As shown;

[0095] The transformation process of Park can be expressed mathematically as follows:

[0096]

[0097]

[0098] in, and The included angle is the current angle that needs to be obtained, through the... and The angle of the output current can be obtained by calculating using the inverse trigonometric function. :

[0099]

[0100] As can be seen from the above, dead zone compensation includes electrical angle, lagging current phase angle, and compensation angle.

[0101] It should be noted that dead-time compensation requires inserting the 0° and 180° phase angles of the current waveform. Therefore, this embodiment of the invention uses the dead-time compensation angle to mark the IO output as high at 0 degrees and low at other times. Because the control output waveform has a range, this embodiment uses a range within ±2 degrees. The output current waveform with the inserted flag is shown in the figure below. Figure 6 As shown, through Figure 6 The observation of the current waveform shows that the insertion angle is at -90 degrees.

[0102] When the dead zone compensation angle is 0, a flag bit is inserted. The output current waveform of the inserted flag bit at this time is shown in the figure below. Figure 7 As shown, through Figure 7 The observation shows that the flag is exactly at the 0-point phase of the output current waveform, which is the required dead zone compensation angle. If the flag is not at the 0-point of the current waveform, the compensation value is adjusted until the flag is at the 0-point phase of the current waveform.

[0103] It's easy to understand that when a phase of a sine wave outputs a zero point, the current is 0, meaning it should be in the off state. During normal output, the current should increase or decrease according to a sine law in the non-zero state. Therefore, the waveform outside the dead time should compensate for the turn-on time loss of the IGBT or MOS caused by the dead time. Within the dead time, it should be compensated according to a sine transformation. Because the time is very short, it can also be approximated as a linear compensation.

[0104] Furthermore, Figure 8 This is the no-load current output of the EV520 frequency converter before 5Hz compensation; Figure 9 This is the output current waveform after dead-time compensation; Figure 10 The waveform is the rated 50Hz output current waveform after dead-zone compensation. It can be seen intuitively that the method of this invention uses an oscilloscope to intuitively find and determine the optimal compensation angle, thereby achieving accurate compensation for the SVPWM dead zone, reducing the THD of low-frequency and light-load current, reducing torque ripple, and reducing the risk of zero-crossing oscillation and DC bias.

[0105] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for accurate dead-time compensation of SVPWM based on oscilloscope phase marking, characterized in that, include: Step S1: In the inverter control software, set the compensation angle to 0 and insert the IO conversion flag bit in the 0 phase of the U-phase wave. Step S2: Run the frequency converter and observe the position of the flag in the U-phase current using an oscilloscope. The position angle obtained is the compensation angle. Step S3: Add the compensation angle to the software to obtain the current compensation angle as: the angle of the output voltage waveform + the angle of the output current + the compensation angle; Step S4: Run the inverter again and observe the position of the flag bit in the U-phase current using the oscilloscope to determine whether the position is at the 0-phase angle of the current. If so, then the position at the 0-phase angle of the current is the dead zone compensation angle; If not, continue adjusting the current compensation angle value and repeat step S3 until the flag is at the 0-point phase of the current waveform.

2. The SVPWM dead-time accurate compensation method based on oscilloscope phase markers according to claim 1, characterized in that, Step S1 includes: In the inverter control software, the dead zone compensation angle parameter is initialized to... ; In the SVPWM algorithm, the zero-phase point of the U-phase output voltage modulation waveform is located, denoted as... ; exist At the corresponding interrupt time, a digital I / O signal that can be captured externally is output. The I / O signal switches from high level to low level or from low level to high level at the 0 phase point as a flag bit that can be triggered by an oscilloscope.

3. The SVPWM dead-time accurate compensation method based on oscilloscope phase markers according to claim 2, characterized in that, The flag bits include: Set the idle general-purpose I / O pins of the frequency converter to digital output mode; In the main loop of the SVPWM algorithm, the U-phase output voltage modulation waveform is determined. phase angle Does it meet the requirements? or ; When the trigger condition is met, the level state of the I / O pin is toggled and maintained for a preset pulse width. It then returns to its initial level to form a narrow pulse.

4. The SVPWM dead-time accurate compensation method based on oscilloscope phase markers according to claim 3, characterized in that, The method of observing the position of the marker bit in the U-phase current using an oscilloscope to obtain the position angle, which is the compensation angle, includes: Connect oscilloscope channel CH1 to the U-phase current sensor output to observe the U-phase current. Connect channel CH2 to the I / O flag signal; Set CH2 edge triggering as an external trigger source and collect at least one electrical cycle; Measuring the trigger time of the CH2 flag The most recent zero crossing time of the U-phase current Time difference between ; Based on the output frequency of the inverter Calculate the time difference The corresponding phase angle is used as the initial compensation angle. : And through the angle normalization function Constrain it to : Will As the initial compensation angle measurement value For subsequent compensation; in, For the instantaneous current of phase U, It refers to the electrical frequency.

5. The SVPWM dead-time accurate compensation method based on oscilloscope phase markers according to claim 4, characterized in that, Adding the compensation angle to the software to obtain the current compensation angle includes: Will Write control software parameters ; In each control cycle, the instantaneous voltage is obtained through Clarke / Park transformation. With current ,calculate ; The current compensation angle is obtained according to the following formula and used to correct the SVPWM reference phase or sampling / update timing: When there is a fixed delay At that time, introduce Provide compensation: in, From the current compensation perspective, Let be the angle normalization function. The instantaneous phase angle for reference to the output voltage. It is the arctangent function in the fourth quadrant. The instantaneous phase angle of the output current. For dead zone compensation angle, Phase quantization for fixed equivalent time delay.

6. The SVPWM dead-time accurate compensation method based on oscilloscope phase markers according to claim 5, characterized in that, By observing the position of the flag bit in the U-phase current using the oscilloscope, and determining whether the position is at the 0-phase angle of the current, the following steps are taken: The current compensation angle obtained from loading And restart the frequency converter; Use the oscilloscope again to simultaneously observe the I / O flag signal and the U-phase current waveform; By observing the alignment between the trigger point of the I / O flag signal and the zero-crossing point of the U-phase current waveform, and calculating the new time difference between them. ; If the above ≤Preset error threshold If so, the compensation is successful. This is the final dead zone compensation angle; stop adjusting. If the above >The error threshold If the compensation is inaccurate, it needs to be fine-tuned, i.e., based on the new time difference. Calculate the correction angle The calculation formula is: in, For electrical frequency, For the new time difference; In the inverter control software, the original dead zone compensation angle parameter is... Add or subtract the correction angle In order to obtain a new compensation perspective The direction of addition or subtraction depends on the new time difference. The positive and negative values ​​are then determined, and the inverter steps are rerun, repeating the above iterative process until the error threshold is met, at which point the iteration stops.

7. The SVPWM dead-time accurate compensation method based on oscilloscope phase markers according to claim 6, characterized in that, The preset error threshold ,include: Based on the clock frequency of the microprocessor used by the frequency converter and SVPWM modulation frequency , will the Set to satisfy a minimum SVPWM regulation period T min Wherein, the minimum adjustment period T min Defined as 1 / With 1 / Integer multiples.

8. The SVPWM dead-time accurate compensation method based on oscilloscope phase markers according to claim 6, characterized in that, The method for determining the direction of addition and subtraction is as follows: When the oscilloscope observes that the trigger point of the flag signal leads the zero-crossing point of the U-phase current, it indicates that the compensation amount is too large and needs to be reduced. The correction angle should be adjusted from the original dead-zone compensation angle parameter. Subtract from the middle; When the oscilloscope observes that the trigger point of the flag signal lags behind the zero-crossing point of the U-phase current, it indicates that the compensation is insufficient and needs to be increased. The correction angle should be adjusted relative to the original dead-zone compensation angle parameter. Add them together.

9. The SVPWM dead-time accurate compensation method based on oscilloscope phase markers according to claim 6, characterized in that, The repeated iteration process is specifically as follows: Obtaining a new compensation perspective Then, return the current compensation angle obtained from the loading process. This step involves re-running the inverter and observing until the new time difference is determined. Satisfying the error threshold The iteration stops when the time is right, and the final compensation angle is locked and saved to the inverter parameters.

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