A compensation and adjustment method for non-ideal factors of self-synchronous voltage source

Abstract

The present invention provides a compensation and adjustment method for non-ideal factors of a self-synchronous voltage source, belonging to the field of self-synchronous voltage source control. The method comprises the following steps: step 1, measuring dead time, on-off delay time and off-off delay time, and performing compensation; step 2, compensating control delay; step 3, testing power tube voltage drop, and performing compensation; step 4, testing inductor current in grid connection, judging whether the compensation for dead time, on-off delay time and off-off delay time, and power tube voltage drop is reasonable; if the inductor current is equal to zero, it is reasonable, and the method proceeds to step 5; if it is not equal to zero, it is unreasonable, and the method returns to step 1; step 5, testing parasitic resistance of the power tube and the transmission line, and performing compensation; step 6, testing inductor current in grid connection, judging whether the compensation for parasitic resistance of the power tube and the transmission line is reasonable; if the inductor current is equal to zero, it is reasonable, and the method proceeds to step 7; if it is not equal to zero, it is unreasonable, and the method returns to step 5; step 7, correcting differential controller parameters; and step 8, judging whether the correction is completed, thereby reducing the influence of various non-ideal factors on grid connection performance.

Description

Technical Field

[0001] The present invention relates to the technical field of self-synchronous voltage source control, and in particular to a compensation and adjustment process for non-ideal factors of a self-synchronous voltage source. Background Art

[0002] The Chinese invention patent application with publication number CN108448613A, "A current sensorless grid-connected current control method for grid-connected inverters," proposes an open-loop differential controller, which has the advantages of fast dynamic characteristics and simple parameter design compared to existing controllers.

[0003] However, the self-synchronous voltage source is a strongly nonlinear system containing various non-ideal factors, such as dead time, drive delay, control delay, tube voltage drop, parasitic resistance, etc. These non-ideal factors will affect the control effect and reduce the quality of the grid current, especially in systems using open-loop control. As a result, differential-based open-loop controllers are difficult to be widely used in practical systems. Importantly, the above non-ideal factors are coupled together, making it difficult to measure and compensate for them. Existing technologies do not provide decoupling and systematic compensation measures. If these non-ideal factors can be decoupled and measured, compensated, and verified one by one, it will help reduce their impact on grid-connected performance and improve the quality of grid current. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a compensation and adjustment method for non-ideal factors of a self-synchronous voltage source, so as to reduce the influence of various non-ideal factors in the self-synchronous voltage source on the grid-connected performance.

[0005] The present invention solves the above technical problems through the following technical solutions: a method for compensating and adjusting the non-ideal factors of a self-synchronous voltage source, comprising the following steps:

[0006] Step 1: Measure the dead time, turn-on and turn-off delay times, and perform fixed amount compensation.

[0007] Step 2: Compensate for control delay;

[0008] Step 3: Test the power tube voltage drop and perform linear quantitative compensation;

[0009] Step 4: Grid-connected test current filter inductor L1 inductor current i L , judge whether the dead time, turn-on and turn-off delay time, and compensation of power tube voltage drop are reasonable. If the inductor current i L If the inductor current i L If it is not equal to zero, it is unreasonable and returns to step 1;

[0010] Step 5: Test the parasitic resistance of the power tube and the transmission line and compensate for it;

[0011] Step 6: Grid-connected test current filter inductor L1 inductor current i L , judge whether the parasitic resistance compensation of the power tube and the transmission line is reasonable. If the inductor current i L If the inductor current i L If it is not equal to zero, it is unreasonable and returns to step 5;

[0012] Step 7: Short-circuit the inverter output and calibrate the differential controller parameters;

[0013] Step 8: Determine whether the differential controller parameter calibration is completed. If completed, the process ends. If not, return to step 7.

[0014] Preferably, a test platform is used to measure the dead time, turn-on and turn-off delay time, and the test platform includes a DC power supply V in , power tubes S1-S6, diodes D1-D6, filter inductor L1, filter inductor L2, filter capacitor C, relay K1, relay K2, load R load , DC power supply V in The positive electrode is connected to the collector of the power tube S1, the cathode of the diode D1, the collector of the power tube S3, and the cathode of the diode D3. The emitter of the power tube S1 is connected to the anode of the diode D1 and then connected to the collector of the power tube S2, the cathode of the diode D2, the emitter of the power tube S3, the anode of the diode D3, the collector of the power tube S6, the cathode of the diode D6, and one end of the filter inductor L1. The emitter of the power tube S6 is connected to the anode of the diode D6 and then connected to the emitter of the power tube S5 and the anode of the diode D5. The collector of the power tube S5 is connected to the cathode of the diode D5 and then connected to one end of the filter inductor L1, one end of the filter inductor L2, the collector of the power tube S4, and the cathode of the diode D4. The emitter of the power tube S2, the anode of the diode D2, the emitter of the power tube S4, and the anode of the diode D4 are all connected to the DC power supply V un The negative pole of the filter inductor L1 is connected to one end of the filter capacitor C and one end of the relay K1. The other end of the relay K1 is connected to the load R load One end of the filter inductor L2 is connected to the other end of the filter capacitor C, one end of the relay K2, and the other end of the relay K2 is connected to the load R load the other end.

[0015] Preferably, the step 1 includes: adjusting the load R load , control load R loadThe current is near the expected value. The output signal of the digital control is compared with the gate drive signal of the power tube. The dead time DT1 and DT2 are measured at the rated power level of the power tubes S1-S6. The average value of the dead time DT1 and DT2 is calculated and a fixed amount compensation is performed.

[0016] Preferably, the step 2 uses interpolation prediction to compensate for the control delay, and the specific expression is:

[0017] u g_F (k+1.5)=u g (k)+1.5(u g (k)-u g (k-1))

[0018] Where u g (k) represents the current grid voltage sampling value, u g (k-1) represents the grid voltage sampling value in the previous switching cycle, u g_F (k+1.5) represents the predicted grid voltage.

[0019] Preferably, the process of testing the power tube voltage drop in step 3 includes:

[0020] 3.1.1、Adjust the load R in the test platform load Large enough, relay K1 and relay K2 are closed;

[0021] 3.1.2. Set the power grid simulator to output different AC voltages and measure them with a high-precision meter;

[0022] 3.1.3. Sample the AC voltage output by the power grid simulator and use interpolation prediction to eliminate control delays while compensating for dead time, turn-on and turn-off delays.

[0023] 3.1.4. Test the voltage of the filter capacitor C and compare it with the voltage output by the measured power grid simulator to obtain the deviation voltage between the two and perform fitting.

[0024] Preferably, the process of performing linear quantitative compensation on the power tube voltage drop in step 3 includes:

[0025] 3.2.1. Use the predicted grid voltage as the modulation wave;

[0026] 3.2.2. Compensate for dead time, turn-on and turn-off delay time;

[0027] 3.2.3. Compensate the measured power tube voltage drop to the modulation wave.

[0028] Preferably, the step 5 comprises:

[0029] 5.1. Use the feedforward grid voltage as the modulation wave to compensate for control delay, dead time, turn-on and turn-off delay time, and power tube voltage drop;

[0030] 5.2. Change the load R load , the voltage u of the filter capacitor C is measured C , calculate the capacitor current i C ;

[0031] 5.3、Measured load current i load , calculate the inductor current i L , inductor current i L With the load current i load The angle between them is θ;

[0032] 5.4. Measure the actual current flowing through the inductor, calculate the voltage of the filter inductor, and convert the grid voltage u g Add the angle θ, the grid voltage u g Perpendicular to the inductor voltage, the inverter voltage u is calculated inv .

[0033] Preferably, in step 7, the dead time, turn-on and turn-off delay time, power tube voltage drop, on-resistance and parasitic resistance are compensated, and there is no need to feed forward the grid voltage. The inverter output is short-circuited, that is, it is not connected to the grid and does not carry a load. The loop only includes a differential controller and a non-ideal factor compensation amount.

[0034] Preferably, the control equation of the differential controller is:

[0035]

[0036] Where i L (s) represents the inductor current, K1 and K2 represent the proportional coefficients of the differential controller, K pwm Indicates the inverter power magnification, G d (s) represents the delay link transfer function, L is the filter inductance value, R is the equivalent parasitic resistance value, i ref (k+1.5) represents the inductor current reference value at the control sampling time k.

[0037] Preferably, the parasitic resistance of the power tube and the transmission line includes: the on-resistance of the power tube, the parasitic resistance of the filter inductor and the resistance of the transmission line.

[0038] The advantages provided by the present invention are:

[0039] The proposed method for compensating and adjusting the non-ideal factors of a self-synchronous voltage source decouples non-ideal factors by assigning a sequence for testing and compensating non-ideal factors. It also improves the effectiveness of non-ideal compensation by correcting the parameters of a differential controller. This method can achieve parameter compensation and decoupling for multiple non-ideal factors, helping to reduce the impact of non-ideal factors on the quality of incoming grid current and improve the grid-connected performance of the inverter. This method can be used not only for open-loop control but also for closed-loop control to reduce the burden on the controller, thereby improving the grid-connected power quality of the self-synchronous voltage source. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Flowchart of the compensation and adjustment method for the non-ideal factors of the self-synchronous voltage source of the present invention;

[0041] Figure 2 A circuit diagram of a test platform for measuring dead time, turn-on and turn-off delay times in the compensation and adjustment method for non-ideal factors of a self-synchronous voltage source of the present invention;

[0042] Figure 3 A schematic diagram illustrating the driving of each power tube within a power grid cycle and including the dead time in the compensation and adjustment method for the non-ideal factors of the self-synchronous voltage source of the present invention;

[0043] 4(a) and (b) are waveform diagrams of the dead time tested at rated current in the compensation and setting method for the non-ideal factor of the self-synchronous voltage source of the present invention;

[0044] Figure 5 This is a circuit diagram of a test platform for measuring the voltage drop of a power tube in the compensation and adjustment method for the non-ideal factors of a self-synchronous voltage source of the present invention;

[0045] Figure 6 This is a diagram showing the compensation effect of the power tube voltage drop in the compensation and adjustment method for the non-ideal factors of the self-synchronous voltage source of the present invention;

[0046] FIG7(a) is a diagram showing the relationship between the inductor current and the grid voltage vector during overcompensation in the compensation and setting method for the non-ideal factors of the self-synchronous voltage source according to the present invention;

[0047] FIG7( b ) is a diagram showing the relationship between the inductor current and the grid voltage vector when under-compensated in the compensation and setting method for the non-ideal factors of the self-synchronous voltage source according to the present invention;

[0048] 8(a) and (b) are waveform diagrams of the inductor current and the grid voltage during overcompensation and undercompensation in the compensation and setting method for the non-ideal factors of the self-synchronous voltage source according to the present invention;

[0049] 9(a) and (b) are waveform diagrams of the current displayed when the inverter is not running and the current measured when the inverter is running after the tube voltage drop is properly compensated in the compensation and adjustment method for the non-ideal factors of the self-synchronous voltage source of the present invention;

[0050] Figure 10 The vector relationship of each physical quantity in the compensation and setting method of the non-ideal factor of the self-synchronous voltage source of the present invention;

[0051] Figure 11 Schematic diagram of a parameter tuning platform for a differential controller in a method for compensating for non-ideal factors of a self-synchronous voltage source according to the present invention;

[0052] Figure 12 A control block diagram of a system in a method for compensating and adjusting non-ideal factors of a self-synchronous voltage source according to the present invention;

[0053] FIG13( a ) is an experimental waveform diagram of the compensation and setting method for the non-ideal factors of the self-synchronous voltage source of the present invention when the DC side voltage is 350 V;

[0054] FIG13( b ) is a diagram of the inductor current waveform sampled and obtained in the compensation and adjustment method for the non-ideal factors of the self-synchronous voltage source according to the present invention;

[0055] 14(a) and (b) are comparisons of the effects before and after compensation for the non-ideal factors in the self-synchronous voltage source non-ideal factor compensation setting method of the present invention under steady-state conditions;

[0056] 15( a ) and ( b ) are comparisons of the effects before and after compensation for non-ideal factors in a dynamic situation in the compensation and adjustment method for non-ideal factors of a self-synchronous voltage source according to the present invention. DETAILED DESCRIPTION

[0057] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the following describes the technical solutions of the present invention clearly and completely with reference to specific embodiments and the accompanying drawings. It is obvious that the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0058] like Figure 1 As shown, this embodiment provides a compensation and adjustment method for non-ideal factors of a self-synchronous voltage source, including the following steps:

[0059] Step 1: Measure the dead time, turn-on and turn-off delay times, and perform fixed amount compensation.

[0060] The dead time, turn-on and turn-off delay time are measured using a test platform. The circuit of the test platform is as follows: Figure 2 As shown, including DC power supply V in , power tubes S1-S6, diodes D1-D6, filter inductor L1, filter inductor L2, filter capacitor C, relay K1, relay K2, load R load , DC power supply Vin The positive electrode is connected to the collector of the power tube S1, the cathode of the diode D1, the collector of the power tube S3, and the cathode of the diode D3. The emitter of the power tube S1 is connected to the anode of the diode D1 and then connected to the collector of the power tube S2, the cathode of the diode D2, the emitter of the power tube S3, the anode of the diode D3, the collector of the power tube S6, the cathode of the diode D6, and one end of the filter inductor L1. The emitter of the power tube S6 is connected to the anode of the diode D6 and then connected to the emitter of the power tube S5 and the anode of the diode D5. The collector of the power tube S5 is connected to the cathode of the diode D5 and then connected to one end of the filter inductor L1, one end of the filter inductor L2, the collector of the power tube S4, and the cathode of the diode D4. The emitter of the power tube S2, the anode of the diode D2, the emitter of the power tube S4, and the anode of the diode D4 are all connected to the DC power supply V in The negative pole of the filter inductor L1 is connected to one end of the filter capacitor C and one end of the relay K1. The other end of the relay K1 is connected to the load R load One end of the filter inductor L2 is connected to the other end of the filter capacitor C, one end of the relay K2, and the other end of the relay K2 is connected to the load R load the other end.

[0061] Using this test platform, the schematic diagram of the drive of power tubes S1-S6 and dead time in one grid cycle is as follows: Figure 3 As shown, the positive half cycle is analyzed as an example, where DT1 represents the dead time between the falling edge of the power tube S6 drive signal and the rising edge of the power tube S1 / S4 drive signal, and DT2 represents the dead time between the falling edge of the power tube S1 / S4 drive signal and the rising edge of the power tube S6 drive signal. Figure 4 shows the waveforms of the dead time DT1 and DT2 tested at rated current. It can be seen that when the drive signal falls and rises, it does not change vertically, resulting in a delay in turn-on and turn-off. By adjusting the load R load , control load R load The current is near the expected value. The output signal of the digital control is compared with the gate drive signal of the power tube. The dead time DT1 and DT2 are measured at the rated power level of the power tubes S1-S6. The average value of the dead time DT1 and DT2 is calculated and a fixed amount compensation is performed.

[0062] Step 2: Compensate for control delay.

[0063] Since the control delay is generally 1.5 switching cycles and usually does not change, taking the compensation of grid voltage feedforward as an example, interpolation prediction is used to compensate for the control delay. The specific expression is:

[0064] u g_F (k+1.5)=u g(k)+1.5(u g (k)-u g (k-1))(1)

[0065] In formula (1), u g (k) represents the current grid voltage sampling value, u g (k-1) represents the grid voltage sampling value in the previous switching cycle, u g_F (k+1.5) represents the predicted grid voltage.

[0066] Step 3: Test the power tube voltage drop and perform linear quantitative compensation on the power tube voltage drop.

[0067] The test platform is used to test the power tube voltage drop, and the load R load Make it large enough, that is, R load =R max , the circuit of the test platform is as follows Figure 5 As shown, it is ensured that after relays K1 and K2 are closed, the load current is small enough when the inverter is running.

[0068] The process of testing the power tube voltage drop includes:

[0069] 3.1.1、Adjust the load R in the test platform load is large enough, and relays K1 and K2 are closed.

[0070] 3.1.2. Set the power grid simulator to output different AC voltages and measure them with a high-precision meter.

[0071] 3.1.3. Sample the AC voltage output by the power grid simulator and use interpolation prediction to eliminate control delays while compensating for dead time, turn-on and turn-off delays.

[0072] 3.1.4. Test the voltage of the filter capacitor C and compare it with the voltage output by the measured power grid simulator to obtain the deviation voltage between the two and perform fitting.

[0073] like Figure 6 As shown in FIG, the process of linear quantitative compensation for the power tube voltage drop includes:

[0074] 3.2.1. Use the predicted grid voltage as the modulation wave.

[0075] 3.2.2. Compensate for dead time, turn-on and turn-off delay times.

[0076] 3.2.3. Compensate the measured power tube voltage drop to the modulation wave.

[0077] Step 4: Grid-connected test current filter inductor L1 inductor current i L, judge whether the dead time, turn-on and turn-off delay time, and compensation of power tube voltage drop are reasonable. If the inductor current i L If the inductor current i L If it is not equal to zero, it is unreasonable and returns to step 1.

[0078] When the compensation is reasonable, the inductor current should be zero in theory. Figure 7 shows the inductor current i under over-compensation and under-compensation. L With the grid voltage u g The vector relationship, when the tube voltage drop compensation is reasonable, the inverter voltage u inv With the grid voltage u g The magnitude and direction of the inductor current i are equal. L When the tube voltage drop compensation is too large, the inverter voltage u inv The amplitude of the inductor current is greater than the grid voltage, and the inductor current flows from the inverter to the grid. L Lagging grid voltage u g When the voltage drop compensation of the power tube is insufficient, the inductor current flows from the grid to the inverter, and the inductor current i L Leading grid voltage u g Figure 8 shows the inductor current i under overcompensation and undercompensation. L With the grid voltage u g waveform.

[0079] Taking into account the measurement errors of the oscilloscope head, Figure 9 shows the current displayed when the inverter is not running and the current measured when the inverter is running after reasonable compensation for the power tube voltage drop: It can be seen that the measured current when the inverter is not running is 0.341A, while the current measured after compensating for the power tube voltage drop is 0.530A. The actual deviation current is 0.189A, accounting for 0.9% of the current amplitude, which meets the requirements.

[0080] Step 5: Test the parasitic resistance of the power tube and the transmission line and compensate for it.

[0081] Use Figure 2 The test platform shown is used to test the parasitic resistance of power tubes and transmission lines at different current levels. The parasitic resistance of power tubes and transmission lines includes the on-resistance of the power tubes, the parasitic resistance of the filter inductor, and the resistance of the transmission line. The testing and compensation of the parasitic resistance of power tubes and transmission lines specifically include the following process:

[0082] 5.1. Use the feedforward grid voltage as the modulation wave to compensate for the control delay, dead time, turn-on and turn-off delay time, and power tube voltage drop.

[0083] 5.2. Change the load R load , the voltage u of the filter capacitor C is measured C, calculate the capacitor current i C .

[0084] 5.3、Measured load current i load , calculate the inductor current i L Capacitor current i C , load current i load , inductor current i L The vector relationship between Figure 10 As shown, the inductor current i L With the load current i load The angle between them is θ.

[0085] 5.4. Measure the actual current flowing through the inductor, calculate the voltage of the filter inductor, and convert the grid voltage u g Add the angle θ, the grid voltage u g Perpendicular to the inductor voltage, the inverter voltage u is calculated inv .

[0086] In practice, if the sampled voltage output by the grid simulator is used as the modulation wave, and other non-ideal factors, including power tube voltage drop, dead time, turn-on and turn-off delays, are compensated, the following relationship holds:

[0087] u inv =u g -ri L (2)

[0088] Therefore, if ri is added in advance to the grid voltage used for modulation wave L , then theoretically the influence of the above-mentioned on-resistance and parasitic resistance can be eliminated, and the following relationship is established:

[0089]

[0090] In the formula This includes the angle θ and the angle that controls the delay compensation.

[0091] Step 6: Grid-connected test current filter inductor L1 inductor current i L , judge whether the parasitic resistance compensation of the power tube and the transmission line is reasonable. If the inductor current i L If the inductor current i L If it is not equal to zero, it is unreasonable and returns to step 5.

[0092] Step 7: Short-circuit the inverter output and calibrate the differential controller parameters.

[0093] From the previous parameter tuning process, we can see that multiple physical quantities need to be measured when tuning the parameters. Considering the accuracy of the measuring equipment and the fact that the values ​​of some physical quantities are small and easy to change, there will be errors in measurement and tuning. Therefore, it is also necessary to tune and fine-tune the differential controller parameters as a whole. Figure 11 A method for tuning the parameters of the differential controller is given.

[0094] The dead time, turn-on and turn-off delay time, power tube voltage drop, on-resistance and parasitic resistance are compensated, but grid voltage feedforward is not required. The inverter output is short-circuited, that is, it is not connected to the grid and there is no load. At this time, the loop only contains the differential controller and the non-ideal factor compensation. The control block diagram of the system at this time is as follows: Figure 12 As shown. The control equation of the differential controller is:

[0095]

[0096] In formula (4), i L (s) represents the inductor current, K1 and K2 represent the proportional coefficients of the differential controller, K pwm Indicates the inverter power magnification, G d (s) represents the delay link transfer function, L is the filter inductance value, R is the equivalent parasitic resistance value, i ref (k+1.5) represents the inductor current reference value at the control sampling time k.

[0097] Considering the problem of inaccurate compensation for non-ideal factors in actual situations, taking the measured resistance as an example, if the actual parasitic resistance is greater than the parasitic resistance used for calculation, the generated current will be less than the given current; conversely, the generated current will be greater than the given reference current. Parameters K1 / K2 need to be fine-tuned based on the actual measured response current. Figure 13(a) shows the experimental results for a DC link voltage of 350V. Figure 13(b) shows the sampled inductor current, which was stored using the DSP storage function and then replotted in Matlab and compared with the reference current. It can be seen that after compensating for static non-ideal factors and fine-tuning the PPD controller parameters, the response current can better track the reference current, demonstrating the effectiveness of the above parameter compensation method.

[0098] Step 8: Determine whether the differential controller parameter calibration is completed. If completed, the process ends. If not, return to step 7.

[0099] Figures 14 and 15 show the experimental waveforms before and after proper compensation for static non-ideal factors, respectively. It can be seen that before static non-ideal factors are effectively compensated, the grid current exhibits significant steady-state errors and distortion, both in steady-state and dynamic conditions. However, after implementing the aforementioned static non-ideal factor compensation measures, the steady-state error of the grid current is effectively eliminated, and the grid current waveform becomes more sinusoidal, significantly improving the grid current quality. The experimental results demonstrate that the proposed compensation strategy, including accurate static non-ideal factor parameter tuning and static non-ideal factor compensation, can effectively eliminate the impact of static non-ideal factors on grid current quality.

[0100] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for compensating for non-ideal factors of a self-synchronous voltage source, characterized by: The following steps are involved: Step 1: Measure the dead time, turn-on and turn-off delay times, and perform fixed amount compensation. Step 2: Compensate for control delay; Step 3: Test the power tube voltage drop and perform linear quantitative compensation; Step 4: Grid-connected test current filter inductor L1 inductor current i L , judge whether the dead time, turn-on and turn-off delay time, and compensation of power tube voltage drop are reasonable. If the inductor current i L If the inductor current i L If it is not equal to zero, it is unreasonable and returns to step 1; Step 5: Test the parasitic resistance of the power tube and the transmission line and compensate for it; Step 6: Grid-connected test current filter inductor L1 inductor current i L , judge whether the parasitic resistance compensation of the power tube and the transmission line is reasonable. If the inductor current i L If the inductor current i L If it is not equal to zero, it is unreasonable and returns to step 5; Step 7: Short-circuit the inverter output and calibrate the differential controller parameters; Step 8: Determine whether the differential controller parameter calibration is completed. If completed, the process ends. If not, return to step 7.

2. The method for compensating for non-ideal factors of a self-synchronous voltage source according to claim 1, wherein: The dead time, turn-on and turn-off delay time are measured using a test platform, which includes a DC power supply V in , power tubes S1-S6, diodes D1-D6, filter inductor L1, filter inductor L2, filter capacitor C, relay K1, relay K2, load R load , DC power supply V in The positive electrode is connected to the collector of the power tube S1, the cathode of the diode D1, the collector of the power tube S3, and the cathode of the diode D3. The emitter of the power tube S1 is connected to the anode of the diode D1 and then connected to the collector of the power tube S2, the cathode of the diode D2, the emitter of the power tube S3, the anode of the diode D3, the collector of the power tube S6, the cathode of the diode D6, and one end of the filter inductor L1. The emitter of the power tube S6 is connected to the anode of the diode D6 and then connected to the emitter of the power tube S5 and the anode of the diode D5. The collector of the power tube S5 is connected to the cathode of the diode D5 and then connected to one end of the filter inductor L1, one end of the filter inductor L2, the collector of the power tube S4, and the cathode of the diode D4. The emitter of the power tube S2, the anode of the diode D2, the emitter of the power tube S4, and the anode of the diode D4 are all connected to the DC power supply V in The negative pole of the filter inductor L1 is connected to one end of the filter capacitor C and one end of the relay K1. The other end of the relay K1 is connected to the load R load One end of the filter inductor L2 is connected to the other end of the filter capacitor C, one end of the relay K2, and the other end of the relay K2 is connected to the load R load the other end.

3. The method for compensating for non-ideal factors of a self-synchronous voltage source according to claim 2, wherein: The step 1 includes: adjusting the load R load , control load R load The current is near the expected value. The output signal of the digital control is compared with the gate drive signal of the power tube. The dead time DT1 and DT2 are measured at the rated power level of the power tubes S1-S6. The average value of the dead time DT1 and DT2 is calculated and a fixed amount compensation is performed.

4. The method for compensating for non-ideal factors of a self-synchronous voltage source according to claim 1, wherein: In step 2, interpolation prediction is used to compensate for the control delay. The specific expression is: in g_F (k+1.5)=u g (k)+1.5(u g (k)-u g (k-1)) Where u g (k) represents the current grid voltage sampling value, u g (k-1) represents the grid voltage sampling value in the previous switching cycle, u g_F (k+1.5) represents the predicted grid voltage.

5. The method for compensating and adjusting the non-ideal factors of a self-synchronous voltage source according to claim 2, wherein: The process of testing the power tube voltage drop in step 3 include: 3.1.1、Adjust the load R in the test platform load Large enough, relay K1 and relay K2 are closed; 3.1.

2. Set the power grid simulator to output different AC voltages and measure them with a high-precision meter; 3.1.

3. Sample the AC voltage output by the power grid simulator and use interpolation prediction to eliminate control delays while compensating for dead time, turn-on and turn-off delays. 3.1.

4. Test the voltage of the filter capacitor C and compare it with the voltage output by the measured power grid simulator to obtain the deviation voltage between the two and perform fitting.

6. The method for compensating and adjusting the non-ideal factors of a self-synchronous voltage source according to claim 5, characterized in that: The process of performing linear quantitative compensation for the power tube voltage drop in step 3 includes: 3.2.

1. Use the predicted grid voltage as the modulation wave; 3.2.

2. Compensate for dead time, turn-on and turn-off delay time; 3.2.

3. Compensate the measured power tube voltage drop to the modulation wave.

7. The method for compensating and adjusting the non-ideal factors of a self-synchronous voltage source according to claim 2, wherein: The step 5 comprises: 5.

1. Use the feedforward grid voltage as the modulation wave to compensate for control delay, dead time, turn-on and turn-off delay time, and power tube voltage drop; 5.

2. Change the load R load , the voltage u of the filter capacitor C is measured C , calculate the capacitor current i C ; 5.3、Measured load current i load , calculate the inductor current i L , inductor current i L With the load current i load The angle between them is θ; 5.

4. Measure the actual current flowing through the inductor, calculate the voltage of the filter inductor, and convert the grid voltage u g Add the angle θ, the grid voltage u g Perpendicular to the inductor voltage, the inverter voltage u is calculated inv .

8. The method for compensating and adjusting the non-ideal factors of a self-synchronous voltage source according to claim 1, wherein: In step 7, the dead time, turn-on and turn-off delay time, power tube voltage drop, on-resistance and parasitic resistance are compensated. No grid voltage feedforward is required. The inverter output is short-circuited, that is, it is not connected to the grid and has no load. The loop only includes the differential controller and the non-ideal factor compensation amount.

9. The method for compensating and adjusting the non-ideal factors of a self-synchronous voltage source according to claim 1, wherein: The control equation of the differential controller is: Where i L (s) represents the inductor current, K1 and K2 represent the proportional coefficients of the differential controller, K pwm Indicates the inverter power magnification, G d (s) represents the delay link transfer function, L is the filter inductance, R is the equivalent parasitic resistance, i ref (k+1.5) represents the inductor current reference value at the control sampling time k.

10. The method for compensating and adjusting the non-ideal factors of a self-synchronous voltage source according to claim 1, characterized in that: The parasitic resistance of the power tube and the transmission line includes: the on-resistance of the power tube, the parasitic resistance of the filter inductor and the resistance of the transmission line.

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