Latest ArticlesSimilar to synchronous generators, the grid-forming converter mostly uses power synchronization or inertial synchronization control strategies, which can provide inertia and damping support to the grid. However, the similar external characteristics of the grid-forming converter and synchronous generator result in its susceptibility to sub-synchronous oscillations when connected to the grid through aseries capacitor compensation line. In view of this, this paper carries out a comprehensive research work on the stability analysis and sub-synchronous oscillation suppression strategy for the grid-forming converter connected to the grid via a series capacitor compensation line.
Firstly, the self-impedance and the accompanying impedance models of the grid-forming converter are established by using the complex variable representation method. The self-impedance and the accompanying impedance are verified using the frequency scanning method, and the scanning results were consistent with the analytical model, verifying the correctness of both. The established the self-impedance and the accompanying impedance models can accurately explain and characterize the single-frequency input and dual-frequency output of the grid-forming converter. Afterwards, the equivalent impedance model of the system with single input and single output of the grid-forming converter is derived, taking into account the frequency coupling effect and the influence of the series complementary lines.
Secondly, the stability of the grid-connected system at different series compensation degrees is analysed by using the Nyquist stability criterion based on an equivalent impedance model that accounts for thefrequency coupling effect. It is found that the larger series compensation degree is, the worse the system stability is. In addition, the impedance stability analysis taking into account the frequency coupling effect is more accurate under certain operating conditions.
Then, a current feedback-based impedance reshaping strategy is proposed for the phenomenon of sub-synchronous oscillations generated by the interaction between the grid-forming converter and the series-complementary line. The strategy is that the grid-connected current passes through the notch filter and the feedback coefficient as part of the modulation wave output to achieve system impedance reshaping. The function of the trap filter is to maintain the fundamental frequency output impedance and avoid the working point offset of the converter. And the current feedback coefficient was introduced into the equivalent impedance model, the feedback coefficient-frequency binary equivalent impedance model was established, and the amplitude-phase contour stability criterion was used to parameterize the current feedback coefficients. It is found that the larger the feedback coefficient k is, the larger the phase margin of the system is, and the more stable the system is. In addition, after the system is shaped by impedance, the phase-frequency curve moves down as a whole, especially in the frequency band below 50 Hz, the phase-frequency curve moves down greatly, resulting in the phase difference at the resonance point less than 180°, and the oscillation is suppressed.
Finally, the grid-connected system model of the grid-forming converter via series-complementary line is built through simulation and experiment, and the impedance remodeling control strategy is implemented on the damping controller to verify the correctness of the theoretical analysis as well as the parameter design. This study draws the following conclusions. (1) The interaction between the grid-forming converter and the series compensation line is easy to cause sub-synchronous oscillation, and the greater the series compensation degree, the higher the oscillation risk. In addition, under certain operating conditions, impedance analyses that take into account frequency coupling effect are more accurate and their influence cannot be ignored. (2) The amplitude-phase contour plot can be used to determine intuitively the influence of the feedback coefficient k on the operating characteristics of the system and to derive the range of values of the feedback coefficient k parameter when the system is in a stable or unstable state.
Accurate prediction of the battery state of charge (SOC) is of great significance to improve the utilization efficiency and safety performance of the battery, and the monitoring of the battery state of charge is very important to help prevent overcharge and overdischarge accidents. The traditional SOC prediction methods are highly dependent on the mechanism model and statistical model, and have problems such as sensitive outliers and limited practical accuracy. In this study, a CNN-LSTM-AM (convolutional neural network - long short term memory neural network - attention mechanism) model is proposed to predict SOC variation trend through battery measurable variables.
The model first uses a one-dimensional convolutional neural network to extract spatial features of measurable variables, including battery current, voltage, temperature and average voltage, and then sends them to bidirectional long and short time memory for time series analysis. Finally, the attention mechanism is introduced to screen key features, reduce the redundancy of feature data, and improve the accuracy and generalization of the model. In addition, CNN-LSTM-AM model adopts rime optimization algorithm to optimize the hyperparameters in the training process, which effectively improves the training efficiency and reduces the training cost.
The actual evaluation on CALCE (Center for Advanced Life Cycle Engineering) data set of lithium iron phosphate shows that the attention mechanism can effectively improve the training performance of the prediction model, and the rime optimization algorithm adopted can help reduce the model hyperparameters, so as to obtain higher prediction accuracy. The performance of CNN-LSTM-AM model was tested under different temperature conditions, and both RMSE and MAE were less than 1%, which was sufficient to confirm the feasibility of the model to predict SOC. In addition, even if the initial SOC is uncertain, the proposed CNN-LSTM-AM model can still accurately track SOC trend changes, and the overall prediction accuracy reaches RMSE<1.5% and MAE<1.5%. The RMSE and MAE results of the network proposed in this study are smaller than those of CNN-LSTM and CNN-LSTM-AM. It shows strong robustness and generalization ability. Finally, in order to comprehensively compare the performance of different SOC prediction methods, the CNN-LSTM-AM model proposed in this study is compared with other experimental results. It can be seen that the method proposed in this study has significantly lower RMSE compared with AT-CNN-LSTM. At the same time, considering that the proposed method uses less training set data, we can also see the advantages of the designed network. Compared with EI-LSTM-CO(extended input-LSTM-constrained output), it can be found that the error is close. In addition, EI-LSTM-CO performs some post-processing on the predicted SOC, which can also reflect the superiority of the proposed method.
The following conclusions are drawn from the simulation analysis: (1) A CNN-LSTM-AM model is proposed and applied to the SOC prediction task of battery, which can effectively capture important input features and improve the prediction accuracy. (2) Design a rime optimization algorithm, which can automatically search the optimal solution of CNN-LSTM-AM model, effectively reduce the time cost of hyperparameter optimization. (3) The influence of different ambient temperatures and initial SOC values on the prediction accuracy of CNN-LSTM-AM was studied, and the performance of CNN-LSTM-AM was compared with that of traditional prediction models to verify its strong robustness and high generalization ability.
As an important parameter in power electronic converters, the leakage inductance of high-frequency transformers is of great significance in improving the operating mode and power transmission characteristics of isolated DC-DC converters. Compared with the solid round wire, the Litz wire can reduce eddy current losses in high-frequency magnetic components. However, the complicated structure of the Litz-wire windings poses a serious challenge to predicting leakage inductance in high-frequency transformers. On the one hand, it is difficult to precisely extract the magnetic field energy in various regions of the core window. On the other hand, it is hard to accurately characterize the multi-stranded and twisting structures of the Litz wires. Therefore, this paper presents a fast calculation method of leakage inductance in the high-frequency transformer with Litz-wire winding.
Firstly, a homogenized equivalent process for Litz wire is proposed to enhance the flexibility of modeling and the efficiency of computation. The magnetic field energy variation with frequency inside the Litz-wire conductors are analyzed. Then, the 2-D magnetic field energy inside the core window is extracted based on the method of images to eliminate the impact of the edge effect. The internal and external magnetic fields at different locations in the winding are accurately characterized by introducing the meshing into the method of images, and a coordinate transformation method is proposed to consider the twisting structure of the Litz wires. Finally, two high-frequency transformer prototypes with different structures are designed and fabricated. Compared with the measurement results and two existing methods, the accuracy and efficiency of the proposed approach are verified.
The following conclusions can be drawn. (1) A homogenized equivalent model of the Litz-wire twisting structure is developed by introducing the relative complex permeability, which simplifies the model building and reduces the computational cost. The variation of the magnetic field energy in the Litz wires with frequency is analyzed, and the magnetic field energy stored in the Litz wires gradually decreases with the frequency increase. (2) The meshing process is introduced into the method of images, and the coordinate transformation method is proposed to characterize the twisting structure of the Litz wire. It can counteract a part of the external magnetic field and reduce the magnetic field energy in the conductors. (3) Considering the twisting characteristics of the Litz wire and the high-frequency effect, a leakage inductance prediction model is developed based on the magnetic field energy variation with frequency. (4) The accuracy and efficiency of the proposed method are verified compared with the measurement and the current two analytical methods. The maximum error does not exceed 4% throughout the measurement frequency range, and the calculation time is about 20 seconds. Moreover, the proposed method can be effectively applied to fast iterative calculations in the optimal design of high-frequency transformers.
During the charging process of flywheel driving by permanent magnet synchronous motor, the three-level converter operates in a low modulation index for a long time, and the traditional virtual space vector pulse width modulation (VSVPWM) strategy frequently generates narrow pulses. Due to the discrete nature of digital control, the sector boundaries in the traditional VSVPWM strategy can shift, exacerbating the narrow pulse issue. These narrow pulses lead to significant distortion in the voltage and current waveforms of the converter and even damage the power devices.
This paper proposed an analysis method considering the discreteness of motor digital control and a hybrid VSVPWM strategy based on vector sequence optimization. Firstly, the variation characteristics of the voltage reference vector and its influence on sector boundary under digital control were studied based on the steady-state mathematical model of the motor. Then, the minimum pulse width function was established to quantitatively analyze the distribution of narrow pulses in the traditional VSVPWM within the low modulation index region. Consequently, according to the narrow pulse distribution law, a hybrid VSVPWM strategy based on vector sequence optimization was proposed.
The traditional VSVPWM (Seg9_VSVPWM), the thirteen-segment VSVPWM (Seg13_VSVPWM), and the proposed hybrid VSVPWM (LH_VSVPWM) were compared. The simulation results show that when the modulation index is 0.1 and 0.3, Seg9_VSVPWM continuously presents narrow pulses less than 2 μs at the boundary between sectors F and A with 672 and 219 times within 1 s. When the modulation index is 0.5, Seg13_VSVPWM would produce the narrowest pulses and accumulate 1 102 times within 1s. However, when the modulation index is 0.1, the proposed LH_VSVPWM eliminates the narrow pulse by optimizing the vector sequence. In addition, LH_VSVPWM has the fewest switching action times in the modulation index of 0.3 and 0.5, which is 5 836 and 5 875 times in 1s, respectively. Meanwhile, the proposed strategy performs well in limiting narrow pulses, occurring only 11 and 32 times within 1 s. The experimental results further demonstrate that LH_VSVPWM can effectively suppress the narrow pulse and keep the minimum pulse width above 6 μs in low modulation index region. Moreover, LH_VSVPWM improves the three-level converter’s output current waveform quality, with THD values of 22.24%, 13.78%, and 17.47% in the modulation index of 0.1, 0.3, and 0.5, respectively. It is the lowest among the three modulation strategies. Compared with Seg9_VSVPWM, the proposed LH_VSVPWM keeps the neutral-point potential balanced during motor start.
The following conclusions can be drawn. (1) The discreteness of motor digital control affects the variation characteristics of the voltage reference voltage and sector boundary of VSVPWM, which aggravates the narrow pulse problem. (2) In the low modulation index region of three-level converters, the effective vector durations are short, and the first vector of switching sequence changes between sectors F and A, B and C, and D and E. Therefore, the traditional VSVPWM maximum coding vectors are prone to narrow pulses at the boundary of these sectors. (3) The proposed method effectively suppresses the narrow pulse and reduces the switching times of power devices. Besides, LH_VSVPWM improves output waveform quality and solves the problem of neutral-point potential imbalance during motor startup.
The bipolar DC distribution network offers high power supply reliability, extensive transmission capacity, and adaptable voltage levels. Developing a bipolar DC distribution network represents an effective strategy for constructing a new type of distribution network. Voltage unbalance constitutes a distinctive power quality issue within bipolar DC distribution networks. Power flow calculation serves as the fundamental tool for analyzing voltage imbalance. Nevertheless, conventional power flow calculation methods merely illustrate the transfer outcomes of voltage unbalance, failing to depict its transfer process within the network. Furthermore, in practical engineering, power is often the measured electrical quantity rather than current, making the existing power flow model based on injected current unsuitable for meeting the application requirements. Hence, this paper proposes a power-injection equation to analyze and quantify the transfer characteristics associated with voltage unbalance.
Initially, the generation and transfer mechanism of voltage unbalance within the bipolar DC distribution network is studied. The voltage unbalance transfer matrix grounded on sensitivity is established to depict the transfer characteristics of voltage unbalance factors at individual nodes. Furthermore, the analytical formulations for each component of the voltage unbalance transfer matrix are derived, and a power flow calculation technique based on the Newton-Raphson method is proposed for determining the matrix. The suggested method employs a power-injection equation for power flow modeling and integrates droop control and comprehensive load models of distributed generation. Finally, the effectiveness of the proposed approach is validated via the modified IEEE 33-node test system. Three case studies are conducted.
Numerical results reveal the following findings. (1) The proposed power flow calculation method exhibits a negligible sacrifice in accuracy, with no more than a 0.83% deviation and a calculation efficiency enhancement of 44%. Additionally, it offers the advantage of accommodating constant power loads, which is suitable for high prevalence power load or load data readily available scenarios. (2) The voltage unbalance transfer matrix effectively illustrates voltage unbalance factors’ alterations and transfer conditions at each node under disturbance conditions. Disturbances induce voltage unbalances that propagate throughout the network following the direction of power flow. Measures must be implemented to block or suppress it at critical network nodes. For instance, strategies such as load switching and energy storage scheduling encourage multi-point loads to adjust in a more balanced manner simultaneously, curtailing unbalanced transfer. Moreover, incorporating a power spring in series with a constant resistance load near the line's terminus can introduce intelligent load management, affording greater flexibility in system voltage unbalance adjustment. The deployment of voltage-regulating equipment, such as DC transformers and voltage balancers, is instrumental in obstructing unbalanced voltage transfer.
The equivalent circuit is valuable for designing an induction machine and its driving system, and its parameters are essential for analyzing the electromagnetic performance and establishing the driving model, especially the magnetizing inductance that characterizes the main flux distribution in the machine. The finite element analysis can precisely determine the magnetizing inductance. However, it is unsuitable for the initial design stage when the design parameters need frequent adjustment. Traditional analytical calculations like the flux linkage method neglect the influence factors, such as core saturation, tooth-slot effect, and rotor movement in the actual operation, causing accuracy issues. The improved analytical calculation method can significantly enhance the accuracy. However, the magnetic circuit in each core segment still needs to be more accurate, and the local saturation points are easily ignored. Besides, the solving process contains nonlinear iterations of multi-segment of the magnetic circuit, which has repeating calculations under different slips.
This paper proposes an elementary layer method based on the main and leakage magnetic circuits to calculate the magnetizing inductance. Firstly, the magnetic voltage drop of each pole of the main magnetic circuit under different air-gap flux densities is calculated, and the magnetic voltage drop and the air-gap flux density are converted into the electromotive force and the magnetizing current to obtain the objective function. Secondly, the distribution of the leakage flux in the stator slot and the current induced in the rotor bar is analyzed to calculate the slot leakage inductance of the stator and rotor, together with the rotor AC resistance. The stator terminal voltage expression is constructed as the constraint condition. Finally, each set of the electromotive force and the magnetizing current on the objective function are substituted into the constraint condition to make the results equal to the rated phase voltage of the stator. The ratio of the set is the value of the magnetizing reactance, and therefore, the magnetizing inductance is obtained. In the main and leakage flux circuits, the irregular and nonlinear magnetic and electric circuits are regularized and linearized using the thin layer elements to substitute theoretical integral. Hence, the tooth-slot structure and the nonlinear material properties can be considered more accurately when calculating the magnetic voltage drop and leakage inductance.
A wet submersible induction machine is an example of the analytical calculation of the magnetizing inductance using the proposed elementary layer method and the traditional flux leakage method. Besides, the steady-state outputs of the equivalent circuit are obtained. The prototype test and the finite element simulation under the magnetic saturation of the stator teeth are conducted. The results show that the elementary layer method considers the distribution of the magnetic voltage drop in the core segment, which is more effective than the flux linkage method when the tooth magnetic circuit is saturated. Therefore, the calculation of the magnetizing inductance is more accurate, and in the steady-state outputs of the equivalent circuit, the stator current, input power, and power factor curves are consistent with the finite element analysis. The error is less than 0.5% when the finite element results are used as the reference. The proposed method links the design parameters and the magnetizing inductance, providing convenience for the initial design and optimization of the submersible induction machine and other types of machines.
In wireless power transfer (WPT) systems, achieving accurate voltage regulation and efficient operation are critical. Current research achieves constant voltage output and zero voltage switch (ZVS) with additional DC-DC converters and variable resonant networks. However, these approaches increase system losses and costs. Therefore, this paper proposes a two-sided LCL phase-shifting control strategy. The internal phase shift angle of the inverter and active rectifier (AR) is used to achieve constant voltage output and maximum efficiency tracking, and the external phase shift angle between the two converters achieves ZVS of all switching tubes. By analyzing the power loss, the constraint condition between the internal phase shift angle is obtained. The minimum external phase shift angle δopt of ZVS is further determined, and the system’s high efficiency is realized. In addition, the power angle θpower is introduced as the intermediate variable, and the frequency synchronization of the primary and secondary sides is realized using the voltage-controlled oscillator (VCO).
Firstly, utilizing the fundamental wave equivalent model, the constant voltage characteristics of the system and the constraint conditions of the inverter output voltage and AR input voltage pulse-width ratio D1 and D2 are analyzed. The results show that transmission efficiency peaks when the AC voltage ratio α =1. With load variations, achieving constant voltage output and maximum efficiency tracking is feasible by adjusting D1 and D2. Secondly, based on the time-domain harmonics model, the derivation and simplification of the time-domain expression of inductance current are conducted. The simplified model is then analyzed to determine the external phase shift angle δ. By comparing δ of the inverter and AR, the δopt is obtained. Thirdly, the overall control strategy is introduced. The constant voltage output is achieved by adjusting D1 and D2. The introduction of θpower as an intermediate variable establishes the relationship between δ and θpower, enabling indirect control of δ through the regulation of θpower. Subsequently, the frequency synchronization of the primary and secondary sides is realized using a VCO, effectively solving the synchronization challenge associated with an active rectifier.
Finally, system simulations and experiments were conducted. The experimental results show that the system can achieve ZVS for all MOSFETs and maintain a constant voltage output regardless of load variations. Moreover, the proposed synchronous control strategy can effectively track the switching frequency of the inverter and precisely adjust the required δopt. As D1 and D2 consistently adhere to the maximum efficiency constraints during system adjustments, the system also achieves maximum efficiency tracking. When the coupling coefficient k is 0.31, the transmission efficiency of the system is the highest, and the maximum efficiency is 93.8%.
Fractional-order elements (FOEs) serve as fundamental components in fractional-order circuits, forming the cornerstone of research into fractional-order circuit systems. Unlike single-component counterparts, the multi-component method offers greater flexibility in selecting constituent elements, enabling the adjustment of order and impedance coefficients for enhanced practicality. This paper provides a comprehensive overview of prevailing construction methods to facilitate the selection of appropriate multi-component FOEs for specific application needs. These methods are classified into three categories based on the type of constituent devices: passive devices, operational amplifiers, and power electronic converters.
In the construction method based on passive devices, two approaches involving Foster RLC ladder circuits are discussed. Passive RLC networks are used to create circuits that match the impedance characteristics of the transfer function. Reducing phase error requires increasing the order and using numerous components, leading to complex structures and cumbersome calculations. When standard off-the-shelf components cannot be used, replacing analytical parameters with standard ones increases the phase angle deviation. Adjusting the FOE order or impedance coefficients requires replacing all circuit components. This method is most suitable for fixed FOE order and impedance coefficients, which are effective in medium to low-frequency scenarios.
Next, the paper introduces the construction method based on operational amplifiers. The method of constructing FOEs based on generalized impedance converter (GIC) circuits can realize FOEs with orders varying from -2 to 2. However, the limited open-loop gain and gain instability of operational amplifiers often result in significant deviations of the obtained FOE performance from its ideal characteristics. Therefore, exploring how to use other active devices, such as operational transconductance amplifiers (OTA) and current feedback operational amplifiers (CFOA), to construct FOEs is an exploration direction. GIC circuits offer great integration and functionality, making them suitable for applications where precise impedance and phase characteristics are crucial.
The construction method based on power electronic converters is also discussed in detail. Multi-component FOEs based on power electronic converters have wide applications because their power level depends on the inverter, and their order and impedance can be adjusted by changing the control parameters. However, different structures of filters affect the operating performance of fractional-order elements. Therefore, exploring the application of different filter structures on multi-component FOEs and optimizing the parameters of the filters become the direction of development for power electronic converter-based FOEs. Power electronic converters provide the advantage of handling higher power levels and dynamic adaptability. The ability to digitally control the fractional order and impedance in real-time makes these elements highly versatile.
Lastly, this paper proposes a three-phase fractional-order electrical spring (TPFES). TPFES controls the order of the equivalent fractional-order capacitance of each phase and the pseudo-capacitance. The effect of stabilizing the load voltage is realized, the power factor is improved, and the power is balanced. The application in grid power compensation demonstrates that multi-component FOEs can effectively enhance the performance of practical circuit systems. This work provides a reference for future applications of fractional order components in electrical engineering.
The single-stage Totem pole dual active bridge (DAB) AC-DC converter has the advantages of low component count, high power density, and low cost, which has a broad application prospect in the field of on-board chargers (OBC). However, in the available research, the traditional single phase shift (SPS) and extended phase shift (EPS) modulation strategies are unable to optimize the quality of grid-connected current and efficiency of the Totem pole DAB AC-DC converter at the same time due to the problem of insufficient modulation degrees of freedom, limiting the further application in on-board chargers.
This paper introduces the asymmetric modulation based on the extended phase shift modulation strategy when the duty cycle of the secondary side switching tubes is no longer 50%. An asymmetric extended phase shift (AEPS) modulation strategy with three degrees of freedom is proposed. Accordingly, a multi-objective optimal modulation strategy is solved by considering the simultaneous optimization of the grid-connected current quality and efficiency of the Totem pole DAB AC-DC converter.
Firstly, the steady-state analytical model of AEPS modulation is established by using the time domain analysis method. The initial value decoupling constraint of the inductor current is considered to optimize the quality of grid-connected current, and the peak-to-peak inductor current is taken as the optimization objective. According to the Lagrange algorithm and Karush Kuhn Tucker conditions, the above multi-objective optimization problem is transformed into mathematical equations to solve the optimization solution of modulation variables. Matlab simulations show that the inductor current’s initial value decoupling and peak-to-peak value optimization are realized under the AEPS optimization modulation strategy. Compared with the SPS and EPS modulation, the proposed AEPS optimization modulation strategy reduces the peak-to-peak and RMS levels of the inductor current in the full power band, which reduces the conduction loss of the converter. Moreover, the optimized solutions in different operating modes under APES modulation are continuous, making seamless switching between different operating modes available.
An experimental prototype of a totem pole DAB AC-DC converter with a rated power of 800 W is constructed. Experimental results show that the converter achieves a peak efficiency of 93.5% under the proposed AEPS optimized modulation strategy, 5% and 14.7% higher than the SPS strategy at full load and light load, respectively; 1.5% and 14.7% higher than the EPS modulation strategy at full load and light load, respectively. The converter's grid-connected current THD is significantly reduced in the full power range, improving its grid-connected current quality. Simulation and experimental results verify the effectiveness of the proposed AEPS-optimized modulation strategy.
In order to realize the freedom of placing pots, the free zone induction cooker with multiple induction heating coils is gradually developing. It can perform user-customized heating of different pots, greatly improving the flexibility of using the induction cooker. In actual work, the induction heating coil in the corresponding area needs to be triggered based on the real-time position. Therefore, the correct identification of the pot position affects the working status and heating performance of the free zone induction cooker system. As a result, pot position identification has become a key factor that needs to be solved urgently. Traditional pot position identification methods are easily affected by fluctuations in external factors, require a large amount of sample data, and need to improve the accuracy and speed of pot position identification. This paper indicates that the misalignment of the pot affects the mutual inductance M between the pot and the induction heating coil, thereby affecting the impedance and current phase of the system. An identification method is proposed using the current phase to control the switch array, which achieves positioning and heating of the pot. The proposed pot position identification strategy requires a small amount of sample data, and the branch current phase is only related to the position of the pot. It is not easily affected by system voltage and current fluctuations, so the position of the pot can be judged in real-time.
Secondly, regarding the impact of pot misalignment on current and power, this paper introduces a power regulation strategy based on an adjustable capacitor circuit. Under the misaligned working condition of the pot, the disturbance observation method of maximum current search is used to adaptively adjust the adjustable capacitor. The maximum power output of the induction cooker is obtained, and the heating speed of the pot is improved. The pot position identification strategy and the power regulation strategy coordinate to ensure accurate identification of the pot position and rapid heating, which only needs to collect the current information of the system branch. Thus, the sampling circuit is simplified.
Finally, an experimental prototype of a free zone induction cooker based on three coils was built. Experimental results show that in the pot position identification strategy, the accuracy of the theoretical and experimental phases is over 96%, and the identification speed is 0.8 ms. The maximum temperature rise within three minutes is 17.3℃ using the power regulation strategy, higher than without the power regulation strategy. The proposed pot position identification strategy can correctly identify the exact position of the pot and achieve the maximum power output of the induction cooker after the power regulation strategy. The correctness of the pot position identification strategy and the power regulation strategy are verified.