A control method, device, apparatus and readable storage medium for a polarity converter

Abstract

The present invention discloses a control method, device, equipment and computer-readable storage medium for a polarity converter. Considering that in a four-switch resonant polarity converter, the conduction loss of each switch tube is positively correlated with the effective value of the resonant circuit current value, and the magnitude of the effective value of the resonant current can be affected by adjusting the target control parameters in the PWM control signal, the present application can construct a preset mathematical model with the lowest resonant circuit current value as the target, and then use the mathematical model to calculate the target control signal parameters based on the current input voltage value and output voltage value of the four-switch resonant polarity converter. Finally, according to the target control signal parameters, a PWM control signal is constructed to control each switch tube, thereby achieving a reduction in the effective value of the resonant current, that is, reducing the conduction loss of the switch tube and improving the efficiency and life of the polarity converter.

Description

Technical Field

[0001] The present invention relates to the field of polarity converters, and in particular to a control method for a polarity converter. The present invention also relates to a control device, equipment, and computer-readable storage medium for a polarity converter. Background Art

[0002] A polarity converter can change the polarity of voltage. A current polarity converter consists of two half-bridge circuits and a resonant circuit, which can be called a four-switch resonant polarity converter. During operation, the internal switch tube of the polarity converter is controlled by the PWM (pulse width modulation) signal output by the controller to change the switching state, thereby realizing the conversion of voltage polarity. However, the existing technology lacks a mature control method for the polarity converter, resulting in large conduction losses of the switches in the four-switch resonant polarity converter during operation, thereby reducing the efficiency and life of the polarity converter.

[0003] Therefore, how to provide a solution to the above technical problems is a problem that those skilled in the art need to solve at present. Summary of the Invention

[0004] An object of the present invention is to provide a control method for a polarity converter, which achieves a reduction in the effective value of the resonant current, that is, reduces the conduction loss of the switching tube, and improves the efficiency and life of the polarity converter; another object of the present invention is to provide a control device, equipment and computer-readable storage medium for a polarity converter, which achieves a reduction in the effective value of the resonant current, that is, reduces the conduction loss of the switching tube, and improves the efficiency and life of the polarity converter.

[0005] To solve the above technical problems, the present invention provides a control method for a polarity converter, comprising:

[0006] Obtain the current input voltage value and output voltage value of the four-switch resonant polarity converter;

[0007] A closed-loop control algorithm is used to calculate a closed-loop control output according to the difference between the output voltage value and the target output voltage value;

[0008] Determining target control signal parameters based on the closed-loop control output, the input voltage value, and the output voltage value according to a preset mathematical model targeting a minimum resonant circuit current value;

[0009] Constructing a pulse width modulation (PWM) control signal according to the target control signal parameter, so as to control the operation of the four-switch resonant polarity converter by using the PWM control signal;

[0010] The target control signal parameters include a phase difference between the two PWM control signals of the four-switch resonant polarity converter and a duty cycle of each of the two PWM control signals.

[0011] Preferably, the target control signal parameters are determined based on the closed-loop control output, the input voltage value, and the output voltage value according to a preset mathematical model with the lowest resonant circuit current value as the goal:

[0012] In fixed frequency control mode:

[0013] Determining a current buck-boost mode of the four-switch resonant polarity converter according to a magnitude relationship between the input voltage value and the output voltage value;

[0014] Based on the closed-loop control output, the input voltage value, and the output voltage value, a target control signal parameter is determined according to a preset mathematical model corresponding to the current buck-boost mode and targeting a minimum resonant circuit current value;

[0015] The target control signal parameters include a phase difference between the two PWM control signals of the four-switch resonant polar converter and a duty cycle of each of the two PWM control signals;

[0016] Then the pulse width modulation (PWM) control signal is constructed according to the target control signal parameter as follows:

[0017] A pulse width modulation (PWM) control signal is constructed according to the target control signal parameter and the preset periods of the two PWM control signals.

[0018] Preferably, the preset mathematical model corresponding to the current buck-boost mode and aiming at minimizing the resonant circuit current value is specifically:

[0019] When the buck-boost mode is buck mode:

[0020] D1=PI Cal ,

[0021] When the buck-boost mode is the non-voltage regulation mode:

[0022] D1 and D2 are both 50% of the preset period, α2 = PI Cal ;

[0023] When the buck-boost mode is the boost mode:

[0024] D2=PI Cal ,

[0025] Wherein, D2 is the first duty cycle of the first PWM control signal of the bridge arm corresponding to the input voltage value V1, D1 is the second duty cycle of the second PWM control signal of the bridge arm corresponding to the output voltage value V2, PI Cal is the closed-loop control output, α1, α2, α3 and T4 are all the durations during which the rising edge of the first PWM control signal precedes the rising edge of the second PWM control signal.

[0026] Preferably, the determining of the target control signal parameters based on the closed-loop control output, the input voltage value, and the output voltage value according to a preset mathematical model with the goal of minimizing the resonant circuit current value further includes:

[0027] In variable frequency control mode:

[0028] Determining a current buck-boost mode of the four-switch resonant polarity converter according to a magnitude relationship between the input voltage value and the output voltage value;

[0029] Based on the closed-loop control output, the input voltage value, and the output voltage value, a target control signal parameter is determined according to a preset mathematical model corresponding to the current buck-boost mode and targeting a minimum resonant circuit current value;

[0030] The target control signal parameters include a duration during which the rising edge of the first PWM control signal precedes the rising edge of the second PWM control signal and the second duty cycle;

[0031] Then the pulse width modulation (PWM) control signal is constructed according to the target control signal parameter as follows:

[0032] Determining the first duty cycle and target cycle lengths of the first PWM control signal and the second PWM control signal according to a preset minimum resonant current value that causes the voltage of the switch tube in the four-switch resonant polarity converter to drop to zero within a preset dead time;

[0033] A pulse width modulation (PWM) control signal is constructed according to the duration that the rising edge of the first PWM control signal precedes the rising edge of the second PWM control signal, the second duty cycle, the first duty cycle, and a target cycle length.

[0034] Preferably, the first duty cycle and the target cycle lengths of the first PWM control signal and the second PWM control signal are determined based on a preset minimum resonant current value that causes the voltage of the switch tube in the four-switch resonant polar converter to drop to zero within the dead time as follows:

[0035] After the first PWM control signal rises to a high level, controlling the first PWM control signal to fall to a low level when the current value of the resonant circuit rises to the minimum resonant current value, so as to determine the first duty cycle;

[0036] After the second PWM control signal drops to a low level, the second PWM control signal is controlled to rise to a high level when the current value of the resonant circuit drops to the minimum resonant current value, so as to determine the target cycle length.

[0037] Preferably, the detection point of the current value of the resonant circuit is located in the bridge arm corresponding to the input voltage value, and is located at a switch tube connected in series with the resonant circuit.

[0038] Preferably, the closed-loop control algorithm is a proportional-integral (PI) control algorithm.

[0039] In order to solve the above technical problems, the present invention further provides a control device for a polarity converter, comprising:

[0040] An acquisition module is used to obtain the current input voltage value and output voltage value of the four-switch resonant polarity converter;

[0041] A first calculation module is used to perform a closed-loop control algorithm calculation based on the difference between the output voltage value and the target output voltage value to obtain a closed-loop control output;

[0042] a second calculation module, configured to determine target control signal parameters based on the closed-loop control output, the input voltage value, and the output voltage value according to a preset mathematical model with the goal of minimizing the resonant circuit current value;

[0043] A construction module, configured to construct a pulse width modulation (PWM) control signal according to the target control signal parameter, so as to control the operation of the four-switch resonant polarity converter by using the PWM control signal;

[0044] The target control signal parameters include a phase difference between the two PWM control signals of the four-switch resonant polarity converter and a duty cycle of each of the two PWM control signals.

[0045] To solve the above technical problems, the present invention further provides a control device for a polarity converter, comprising:

[0046] memory for storing computer programs;

[0047] A processor is configured to implement the steps of the polarity converter control method described above when executing the computer program.

[0048] To solve the above technical problems, the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the control method of the polarity converter as described above are implemented.

[0049] The present invention provides a control method for a polarity converter. Taking into account that in a four-switch resonant polarity converter, the conduction loss of each switch tube is positively correlated with the effective value of the resonant circuit current value, and the size of the effective value of the resonant current can be affected by adjusting the target control parameters in the PWM control signal, the present application can construct a preset mathematical model with the lowest resonant circuit current value as the target, and then use the mathematical model to calculate the target control signal parameters based on the current input voltage value and output voltage value of the four-switch resonant polarity converter. Finally, according to the target control signal parameters, a PWM control signal is constructed to control each switch tube, thereby achieving a reduction in the effective value of the resonant current, that is, reducing the conduction loss of the switch tube and improving the efficiency and life of the polarity converter.

[0050] The present invention also provides a control device, an apparatus and a computer-readable storage medium for a polarity converter, which have the same beneficial effects as the above control method for the polarity converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the prior art and the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0052] Figure 1 A schematic flow chart of a control method for a polarity converter provided by the present invention;

[0053] Figure 2 Schematic diagram of the structure of a four-switch resonant polarity converter;

[0054] Figure 3 The working waveform of the four-switch resonant polarity converter in non-voltage regulation mode;

[0055] Figure 4 The working waveform of the four-switch resonant polarity converter in buck mode;

[0056] Figure 5 The working waveform of the four-switch resonant polarity converter in boost mode;

[0057] Figure 6 The working mode diagram of the four-switch resonant polarity converter under light / heavy load;

[0058] Figure 7 A flow chart of a control method for a four-switch resonant polarity converter in a fixed frequency mode provided by the present invention;

[0059] Figure 8 A schematic diagram of a method for generating a PWM control signal provided by the present invention;

[0060] Figure 9 A schematic diagram illustrating the implementation principle of a control method for a four-switch resonant polarity converter in variable frequency mode provided by the present invention;

[0061] Figure 10 A flow chart of a control method for a four-switch resonant polarity converter in variable frequency mode provided by the present invention;

[0062] Figure 11 A schematic structural diagram of a control device for a polarity converter provided by the present invention;

[0063] Figure 12 A schematic structural diagram of a control device for a polarity converter provided by the present invention. DETAILED DESCRIPTION

[0064] The core of the present invention is to provide a control method for a polarity converter, which realizes the reduction of the effective value of the resonant current, that is, reduces the conduction loss of the switching tube, and improves the efficiency and life of the polarity converter; another core of the present invention is to provide a control device, equipment and computer-readable storage medium for a polarity converter, which realizes the reduction of the effective value of the resonant current, that is, reduces the conduction loss of the switching tube, and improves the efficiency and life of the polarity converter.

[0065] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0066] Please refer to Figure 1 , Figure 1 A flow chart of a control method for a polarity converter provided by the present invention, the control method for the polarity converter comprising:

[0067] S101: Obtaining a current input voltage value and an output voltage value of a four-switch resonant polarity converter;

[0068] To better illustrate the embodiments of the present invention, please refer to Figure 2 , Figure 2The schematic diagram of the structure of the four-switch resonant polarity converter is shown in FIG. 1 . In the figure, S1, S2, S3, and S4 represent the gate-level signals of Vgs1, Vgs2, Vgs3, and Vgs4, respectively. The switch tube Vgs1 corresponding to S1 and the switch tube Vgs2 corresponding to S2 form one bridge arm, the switch tube Vgs3 corresponding to S3 and the switch tube Vgs4 corresponding to S4 form the other bridge arm, and the inductor I Lr and capacitor V Cr Form a resonant circuit.

[0069] Specifically, taking into account the technical problems in the above background technology, and taking into account that in the four-switch resonant polarity converter, the conduction loss of each switch tube is positively correlated with the effective value of the resonant circuit current value, and the size of the effective value of the resonant current can be affected by adjusting the target control parameters in the PWM control signal, the present application intends to adjust the target control parameters in the PWM control signal by constructing a mathematical model, so as to achieve a reduction in the resonant current value (of course, the output voltage and output current requirements must be met at the same time in this process). Therefore, in this application, the current input voltage value and output voltage value of the four-switch resonant polarity converter are first obtained to serve as the data basis for subsequent steps.

[0070] The four-switch resonant polarity converter has an input voltage and an output voltage, and can realize three modes, namely a boost mode, a buck mode, and a non-voltage regulation mode in which the input and output voltages are equal.

[0071] S102: performing a closed-loop control algorithm calculation based on the difference between the output voltage value and the target output voltage value to obtain a closed-loop control output value;

[0072] Specifically, since the output voltage of the four-switch resonant polarity converter needs to be precisely controlled, the closed-loop control algorithm in this application can be used to calculate the closed-loop control output based on the difference between the output voltage value and the target output voltage value, so that the closed-loop control output can be applied to the mathematical model in the subsequent steps to calculate the target control signal parameters.

[0073] There are many types of closed-loop control algorithms, which are not limited in the embodiment of the present invention.

[0074] S103: Based on the closed-loop control output, the input voltage value, and the output voltage value, a target control signal parameter is determined according to a preset mathematical model with the goal of minimizing the resonant circuit current value;

[0075] Specifically, in this application, a preset mathematical model with the goal of minimizing the current value of the resonant circuit can be pre-constructed for application in this step. The closed-loop control output, input voltage value, and output voltage value can be used as inputs of the mathematical model, and the output is the target control signal parameter. After applying the obtained target control signal parameters, the effective value of the resonant current can be reduced.

[0076] Among them, the phase difference between the two PWM control signals of the four-switch resonant polarity converter and the adjustment of the duty cycle of each of the two PWM control signals can affect the size of the effective value of the resonant circuit current. Therefore, in this application, these three parameters are used as control variables to achieve the reduction of the effective value of the resonant current.

[0077] S104: constructing a pulse width modulation (PWM) control signal according to the target control signal parameter, so as to control the operation of the four-switch resonant polarity converter using the PWM control signal;

[0078] The target control signal parameters include a phase difference between two PWM control signals of the four-switch resonant polarity converter and a duty cycle of each of the two PWM control signals.

[0079] Specifically, after obtaining the target control signal parameters, a PWM control signal can be constructed based on them. Since these target control signal parameters are obtained through a mathematical model, using the PWM control signal to control the switch tube in the four-switch resonant polarity converter can reduce the effective value of the resonant current, that is, reduce the conduction loss of the switch tube and extend the service life of the switch tube.

[0080] The present invention provides a control method for a polarity converter. Taking into account that in a four-switch resonant polarity converter, the conduction loss of each switch tube is positively correlated with the effective value of the resonant circuit current value, and the size of the effective value of the resonant current can be affected by adjusting the target control parameters in the PWM control signal, the present application can construct a preset mathematical model with the lowest resonant circuit current value as the target, and then use the mathematical model to calculate the target control signal parameters based on the current input voltage value and output voltage value of the four-switch resonant polarity converter. Finally, according to the target control signal parameters, a PWM control signal is constructed to control each switch tube, thereby achieving a reduction in the effective value of the resonant current, that is, reducing the conduction loss of the switch tube and improving the efficiency and life of the polarity converter.

[0081] Based on the above embodiment:

[0082] As a preferred embodiment, based on the closed-loop control output, input voltage value, and output voltage value, the target control signal parameters are determined according to a preset mathematical model with the lowest resonant circuit current value as the goal:

[0083] In fixed frequency control mode:

[0084] Determine the current buck-boost mode of the four-switch resonant polarity converter based on the relationship between the input voltage value and the output voltage value;

[0085] Based on the closed-loop control output, input voltage, and output voltage, target control signal parameters are determined according to a preset mathematical model corresponding to the current buck-boost mode and targeting the lowest resonant circuit current value.

[0086] The target control signal parameters include a phase difference between two PWM control signals of the four-switch resonant polar converter and a duty cycle of each of the two PWM control signals;

[0087] The pulse width modulation PWM control signal is constructed according to the target control signal parameters as follows:

[0088] A pulse width modulation (PWM) control signal is constructed according to the target control signal parameter and the preset periods of the two PWM control signals.

[0089] Specifically, the PWM control signal for controlling the four-switch resonant polar converter can be fixed-frequency control or variable-frequency control. In fact, the difference between the two lies in whether the cycle length of the PWM control signal changes. First of all, for the fixed-frequency control mode in the embodiment of the present invention, the cycle of the PWM control signal is fixed to a preset cycle. Therefore, as long as the three parameters of the phase difference of the two PWM control signals of the four-switch resonant polar converter and the duty cycle of the two PWM control signals are calculated, the two PWM control signals can be constructed. It is worth noting that the target control signal parameters in different buck-boost modes are different. Therefore, this application configures a corresponding mathematical model for each buck-boost mode to calculate the target control signal parameters, which can accurately reduce the resonant current of each buck-boost mode.

[0090] As a preferred embodiment, the preset mathematical model corresponding to the current buck-boost mode and aiming at minimizing the resonant circuit current value is specifically:

[0091] When the buck-boost mode is buck mode:

[0092] D1=PI Cal ,

[0093] When the buck-boost mode is non-voltage regulation mode:

[0094] D1 and D2 are both 50% of the preset period, α2=PI Cal ;

[0095] When the buck-boost mode is boost mode:

[0096] D2=PI Cal ,

[0097] Wherein, D2 is the first duty cycle of the first PWM control signal of the bridge arm corresponding to the input voltage value V1, D1 is the second duty cycle of the second PWM control signal of the bridge arm corresponding to the output voltage value V2, PI Cal For closed-loop control of the output, α1, α2, α3 and T4 are all the durations during which the rising edge of the first PWM control signal precedes the rising edge of the second PWM control signal.

[0098] Specifically, the above mathematical model can accurately obtain the target control signal parameters that can reduce the effective value of the resonant current in each buck-boost mode, and it only applies the three control variables of closed-loop control output, input voltage value and output voltage value. The calculation process is relatively simple and efficient.

[0099] To better illustrate the embodiments of the present invention, please refer to Figure 3-Figure 5 , Figure 3 This is the operating waveform of the four-switch resonant polarity converter in non-voltage regulation mode. Figure 4 This is the working waveform of the four-switch resonant polarity converter in buck mode. Figure 5 The working waveform of the four-switch resonant polarity converter in boost mode, where α is the phase difference between the two PWM control signals, V ab express Figure 2 The resonant circuit voltage between points AB, I Lr represents the resonant current, ePWM1 represents one set of PWM control signals, ePWM2 represents another set of PEM control signals, T1-T4 are the four different stages when the two PWM control signals control the four switch tubes, and there are two open switch tubes in each stage. The above α also corresponds to T4. For the specific control stages, please refer to Table 1 below:

[0100] Table 1

[0101]

[0102]

[0103] Among them, T1-T4 represent a working mode of the four-switch resonant polarity converter respectively. Mode T1 is called resonant energy storage mode, mode T2 is called energy storage cycle mode, mode T3 is called resonant discharge mode, and mode T4 is called balance mode.

[0104] For details, please refer to Figure 6 , Figure 62 is a working mode diagram of the four-switch resonant polarity converter under light / heavy load, wherein, under light load, T3 ≥ 0.5 preset cycles, and under heavy load, T3 ≤ 0.5 preset cycles.

[0105] For details, please refer to Table 2 below, which shows the operating conditions of the four-switch resonant polarity converter in different buck-boost modes. In Table 2:

[0106] Mode 1: In buck-boost mode with V1 = V2, all three control schemes achieve the desired 1:1 ratio (the ratio of D1 to D2 can be adjusted arbitrarily). However, the simplest control scheme uses a phase shift angle α with two preset duty cycles fixed at 50%.

[0107] Mode 2: If the digital controller detects the buck operation mode, such as V1 is greater than V2, then according to Table 2, the duty cycle D1 is always greater than D2;

[0108] Mode 3: If the digital controller detects boost operation mode, such as V2 is greater than V1, then according to Table 2, the duty cycle D2 is always greater than D1.

[0109] Table 2

[0110]

[0111] To better illustrate the embodiments of the present invention, please refer to Figure 7 as well as Figure 8 , Figure 7 This is a flow chart of a control method for a four-switch resonant polarity converter in a fixed frequency mode provided by the present invention. Figure 8 A schematic diagram of a method for generating a PWM control signal provided by the present invention, wherein Figure 7 In order to prevent the two switching tubes on the same bridge arm from being turned on at the same time, dead time can be set between different operating modes T1-T4, and in order to ensure that zero voltage switching is implemented normally in each mode, the dead time is accurately calculated in advance.

[0112] Specifically, in Figure 8In the example, a PWM signal generation unit of a digital controller (such as a DSP (Digital Signal Process) or an FPGA (Field Programmable Gate Array)) can generate the required PWM control signal, which is then sent to a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) driver to drive the connected MOSFET. The PWM control signal modulation method is as follows:

[0113] exist Figure 7 In the previous chapter, we discussed the boost and buck operation modes. The simplified control strategy for calculating the duty cycles D1 and D2 (T1 and T2) is mainly based on the modulation signals PWM1 and PWM2. Figure 8 D1 is given to the comparison register CMP1 of the digital controller's PWM module. When the counter of the first channel, ePWM1, reaches 0, the output of ePWM1 is pulled up. When the D1 value of CMP1 is reached, the module will pull down the output of ePWM1. Similarly, duty cycle D2 (T4 + T1) is calculated using the ratio V2 / V1 and the value of D1. D2 is given to the comparison register CMP2 of the digital controller. When the counter of the first channel, ePWM2, reaches 0, the output of ePWM2 is pulled up. When the CMP2 value reaches D2, the PWM module will pull down ePWM2. A phase shift angle α is introduced between D1 and D2, with a value equal to the operating mode of T4, to increase the load current and output voltage. To simply achieve zero-voltage switching for all four switches, a dead time is added between each time interval.

[0114] Of course, in addition to the above mathematical models, the mathematical models used in the fixed-frequency control mode may also be of other types, which are not limited in the embodiment of the present invention.

[0115] As a preferred embodiment, based on the closed-loop control output, the input voltage value, and the output voltage value, determining the target control signal parameter according to a preset mathematical model with the lowest resonant circuit current value as the goal also includes:

[0116] In variable frequency control mode:

[0117] Determine the current buck-boost mode of the four-switch resonant polarity converter based on the relationship between the input voltage value and the output voltage value;

[0118] Based on the closed-loop control output, input voltage, and output voltage, target control signal parameters are determined according to a preset mathematical model corresponding to the current buck-boost mode and targeting the lowest resonant circuit current value.

[0119] The target control signal parameters include a duration during which the rising edge of the first PWM control signal precedes the rising edge of the second PWM control signal and a second duty cycle;

[0120] The pulse width modulation PWM control signal is constructed according to the target control signal parameters as follows:

[0121] Determining a first duty cycle and target cycle lengths of the first PWM control signal and the second PWM control signal based on a preset minimum resonant current value that causes the voltage of the switch tube in the four-switch resonant polarity converter to drop to zero within a preset dead time;

[0122] A pulse width modulation (PWM) control signal is constructed according to the duration that the rising edge of the first PWM control signal precedes the rising edge of the second PWM control signal, the second duty cycle, the first duty cycle, and the target cycle length.

[0123] Specifically, considering that there is room for reducing the effective value of the resonant current when each switch tube is turned off in the fixed-frequency control mode, and by detecting the resonant current value, some switch tubes can be turned off when the resonant current value reaches the minimum resonant current value (the minimum resonant current value that can reduce the voltage value of the switch tube in the four-switch resonant polarity converter to zero within the dead time), the turn-off current value of these switch tubes can be reduced, thereby further reducing the switching loss and extending the service life of the switch tube.

[0124] Specifically, in the above-mentioned variable frequency control mode, after determining the duration of the rising edge of the first PWM control signal ahead of the rising edge of the second PWM control signal and the second duty cycle, the present application wants to construct two PWM control signals, and then it is also necessary to determine the first duty cycle and the cycle length of the two PWM control signals. Therefore, in the present application, the first duty cycle and the target cycle lengths of the first PWM control signal and the second PWM control signal are determined by pre-calculating the minimum resonant current value, so as to construct the two PWM control signals.

[0125] To better illustrate the embodiments of the present invention, please refer to Figure 9 as well as Figure 10 , Figure 9 This is a schematic diagram of the implementation principle of the control method of the four-switch resonant polarity converter in the variable frequency mode provided by the present invention. Figure 10 The flow chart of the control method of the four-switch resonant polarity converter in the variable frequency mode provided by the present invention is specifically described as follows:

[0126] The control scheme of the embodiment of the present invention adds an additional sensor: the resonant current value, which can be specifically sampled periodically to obtain the current value I of the MOSFET S3. S3 And use it as the resonant current value to ensure the realization of ZVS (Zero Voltage Switch), three sensing elements (measuring V1, V2 and I S3 ) circuit diagram as shown Figure 9 As shown; the flowchart of this specific implementation is as follows Figure 10 As shown in the figure, the various steps of the control scheme are shown. In theory, the real-time control requires that the control variables and calculations are as simple as possible. This specific implementation uses a simplified three-dimensional control algorithm to continuously track V1, V2 and I S3 feedback signal.

[0127] The realization of the variable frequency control mode requires necessary electrical signal detection components, including V1, V2 and I S3 Voltage and current detection require a digital processor to connect and receive the above electrical signals (a digital processor with comprehensive detection functions can be used). The digital processor processes the above electrical signals to generate the required control value, and the PWM signal generation unit of the digital controller generates the required PWM signal, which is sent to the MOSFET driver to drive the connected MOSFET. After obtaining the switch drive signal and control system, Figure 9 The four-switch resonant polarity converter in the figure is composed of semiconductor components such as MOSFET and PCB circuit. The specific process is as follows:

[0128] The MOSFET S3 current is sensed by the current sensor and compared with the minimum resonant current I zvs Compare output an I comp Level, such as Figure 9 As shown, the V2 voltage is compared with its set reference value (target output voltage value) V Ref A comparison is made, generating an error that continuously updates the PI controller value. The digital controller obtains the latest updated values ​​of the V1 and V2 voltages through the voltage sensing element, and concludes that the polarity converter is currently operating in boost control mode, buck control mode, or 1:1 control mode. After distinguishing between buck, boost, or 1:1 operating modes, the digital controller generates four PWM signals for the converter to use. The control scheme follows the operating process shown in Table 2.

[0129] Specifically, to put it simply, the frequency conversion control scheme is divided into two cases:

[0130] Case 1: If the digital controller detects a buck or 1:1 operation mode (V1 ≥ V2), such as Figure 10As shown, in this working mode, D1≥D2, the time interval between T4 and T1 is calculated by the PI signal, and the time interval of T3 is calculated by the MOSFET S3 ZVS current I S3 Calculation shows that when the converter operates in step-down and 1:1 working mode, T2>T4 or T2≥T4.

[0131] Case 2: If the digital controller is based on Figure 10 Boost or 1:1 working mode (V2≥V1) is detected. In this working mode, D2≥D1, the time intervals of T4 and T1 are calculated by the PI signal, and the time interval of T3 is calculated by the MOSFET S3 ZVS current I S3 Calculation shows that when the converter operates in boost and 1:1 working modes, T4>T2 or T4≥T2, where both boost and buck are applicable to 1:1 working conditions.

[0132] Specifically, the PWM signal modulation method is as follows:

[0133] according to Figure 10 , discusses the operation of the two modes of operation, the duty cycle D2 is calculated by a simplified control strategy, which includes T4 and T1, and is used as the main modulation signal (D2 = T4 + T1). D2 is given to the comparison register CMP2 of the digital processor of the PWM module. When the ePWM2 counter of the first channel counts and the counter value is 0, the output of ePWM2 is pulled up. When the counter value reaches the CMP2 value, the module pulls down the ePWM2 output, introducing a phase difference α between D1 and D2, whose value is equal to the time interval of T4. It increases or decreases according to the voltage and load current, using the current I of MOSFET S3. S3 Calculate the duty cycle of D1. If the MOSFET current I S3 Greater than I ZVS , the comparator gives Figure 9 I shown comp Low-level signal output, this edge marks the end of T2 and the beginning of T3. When T2 ends, S4 is turned off, and when T3 starts, S3 is turned on.

[0134] Accordingly, the calculated value D1 is given to the comparison register CMP1 of the PWM module of the digital processor. When the ePWM1 counter of the first channel counts and the ePWM1 counter is 0, the output of ePWM1 is pulled up, and when the ePWM1 count value reaches CMP1A, the module pulls ePWM1 down.

[0135] As a preferred embodiment, based on a preset minimum resonant current value that causes the voltage value of the switch tube in the four-switch resonant polar converter to drop to zero within the dead time, the first duty cycle and the target cycle lengths of the first PWM control signal and the second PWM control signal are determined as follows:

[0136] After the first PWM control signal rises to a high level, when the current value of the resonant circuit rises to a minimum resonant current value, the first PWM control signal is controlled to fall to a low level to determine a first duty cycle;

[0137] After the second PWM control signal drops to a low level, the second PWM control signal is controlled to rise to a high level when the current value of the resonant circuit drops to a minimum resonant current value, so as to determine the target cycle length.

[0138] Specifically, the resonant current value can be continuously detected. When only the second duty cycle is known at the beginning, the second PWM control signal can be controlled to rise to a high level first. When the duration after the rising edge of the second PWM control signal reaches the phase difference (that is, the duration of the rising edge of the first PWM control signal is earlier than the rising edge of the second PWM control signal), the first PWM control signal can be controlled to rise to a high level. At this time, for the second PWM control signal, after the duration of its rising edge reaches the second duty cycle, it can be reduced to a low level. For the first PWM control signal, when the resonant current rises to the minimum resonant current value, the voltage can be controlled to be pulled down to a low level. Then, when the resonant current drops to the minimum resonant current value, the level of the second PWM control signal can be controlled to rise to start the next cycle.

[0139] This method can accurately ensure that the turn-off current value of each switch tube in each cycle is maintained at the minimum resonant current, thereby achieving the purpose of reducing switching losses.

[0140] Specifically, the solution in the embodiment of the present invention can be implemented based on Figure 9 The comparator shown is implemented as S3 The current value and the minimum resonant current value I ZVS The comparison is then performed through the comparator output I comp The falling edge and the rising edge of the waveform implement the control in the embodiment of the present invention.

[0141] As a preferred embodiment, the detection point of the current value of the resonant circuit is located in the bridge arm corresponding to the input voltage value, and is located at the switch tube connected in series with the resonant circuit.

[0142] Specifically, considering that the current value of the switching tube in series with the resonant circuit in the bridge arm corresponding to the input voltage value can be detected as the resonant current value, and the current detection difficulty of the switching tube is relatively low, the present application can reduce the difficulty of circuit design by setting the above-mentioned resonant current value detection point.

[0143] Of course, in addition to the above detection points, the detection points of the resonant current can also be other positions, which is not limited in the embodiment of the present invention.

[0144] As a preferred embodiment, the closed-loop control algorithm is a PI (Proportion Integral) control algorithm.

[0145] Specifically, the PI control algorithm has the advantages of a simple and fast parameter tuning process and high accuracy.

[0146] Of course, in addition to the PI control algorithm, the closed-loop control algorithm may also be other types, such as a PID (Proportion Integral Differential) algorithm, etc., which is not limited in the embodiment of the present invention.

[0147] Please refer to Figure 11 , Figure 11 This is a schematic structural diagram of a control device for a polarity converter provided by the present invention, wherein the control device for the polarity converter comprises:

[0148] An acquisition module 111 is configured to acquire a current input voltage value and an output voltage value of the four-switch resonant polarity converter;

[0149] A first calculation module 112 is configured to perform a closed-loop control algorithm calculation based on the difference between the output voltage value and the target output voltage value to obtain a closed-loop control output value;

[0150] The second calculation module 113 is configured to determine target control signal parameters based on the closed-loop control output, the input voltage value, and the output voltage value according to a preset mathematical model with the goal of minimizing the resonant circuit current value;

[0151] A construction module 114 is configured to construct a pulse width modulation (PWM) control signal according to the target control signal parameters, so as to control the operation of the four-switch resonant polarity converter using the PWM control signal;

[0152] The target control signal parameters include a phase difference between two PWM control signals of the four-switch resonant polarity converter and a duty cycle of each of the two PWM control signals.

[0153] For an introduction to the control device of the polarity converter in the embodiment of the present invention, please refer to the aforementioned embodiment of the control method of the polarity converter, and the embodiment of the present invention will not be described in detail here.

[0154] Please refer to Figure 12 , Figure 12 A schematic structural diagram of a control device for a polarity converter provided by the present invention, wherein the control device for the polarity converter comprises:

[0155] Memory 121, for storing computer programs;

[0156] The processor 122 is configured to implement the steps of the above method for controlling the polarity converter when executing a computer program.

[0157] For an introduction to the control device of the polarity converter in the embodiment of the present invention, please refer to the aforementioned embodiment of the control method of the polarity converter, and the embodiment of the present invention will not be described in detail here.

[0158] The present invention also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the above method for controlling a polarity converter are implemented.

[0159] For an introduction to the computer-readable storage medium in the embodiment of the present invention, please refer to the aforementioned embodiment of the control method of the polarity converter, and the embodiment of the present invention will not be described in detail here.

[0160] In this specification, the various embodiments are described in a progressive manner, with each embodiment focusing on the differences from the other embodiments. Similar or identical parts between the various embodiments may be referred to in conjunction with each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and for relevant parts, reference may be made to the method description. It should also be noted that, in this specification, relational terms such as first and second, etc., are used solely to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations. Furthermore, the terms "comprise," "include," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the process, method, article, or device comprising that element.

[0161] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method for a polarity converter, characterized in that: include: Obtain the current input voltage value and output voltage value of the four-switch resonant polarity converter; A closed-loop control algorithm is used to calculate a closed-loop control output according to the difference between the output voltage value and the target output voltage value; In fixed frequency control mode: Determining a current buck-boost mode of the four-switch resonant polarity converter according to a magnitude relationship between the input voltage value and the output voltage value; Based on the closed-loop control output, the input voltage value, and the output voltage value, a target control signal parameter is determined according to a preset mathematical model corresponding to the current buck-boost mode and targeting a minimum resonant circuit current value; The target control signal parameters include a phase difference between two PWM control signals of the four-switch resonant polar converter and a duty cycle of each of the two PWM control signals; constructing a pulse width modulation (PWM) control signal according to the target control signal parameter and the preset periods of the two PWM control signals, so as to control the operation of the four-switch resonant polarity converter by using the PWM control signal; The target control signal parameters include a phase difference between the two PWM control signals of the four-switch resonant polar converter and a duty cycle of each of the two PWM control signals; The preset mathematical model corresponding to the current buck-boost mode and aiming at minimizing the resonant circuit current value is specifically: When the buck-boost mode is buck mode: ， ， ； When the buck-boost mode is the non-voltage regulation mode: D1 and D2 are both 50% of the preset period, ; When the buck-boost mode is the boost mode: ， ， ； Wherein, D2 is the first duty cycle of the first PWM control signal of the bridge arm corresponding to the input voltage value V1, D1 is the second duty cycle of the second PWM control signal of the bridge arm corresponding to the output voltage value V2, PI Cal is the closed-loop control output, 、 、 T and T4 are both the duration during which the rising edge of the first PWM control signal precedes the rising edge of the second PWM control signal.

2. The control method of the polarity converter according to claim 1, characterized in that: The step of determining the target control signal parameter based on the closed-loop control output, the input voltage value, and the output voltage value according to a preset mathematical model targeting the lowest resonant circuit current value further includes: In variable frequency control mode: Determining a current buck-boost mode of the four-switch resonant polarity converter according to a magnitude relationship between the input voltage value and the output voltage value; Based on the closed-loop control output, the input voltage value, and the output voltage value, a target control signal parameter is determined according to a preset mathematical model corresponding to the current buck-boost mode and targeting a minimum resonant circuit current value; The target control signal parameters include a duration during which the rising edge of the first PWM control signal precedes the rising edge of the second PWM control signal and the second duty cycle; Then the pulse width modulation (PWM) control signal is constructed according to the target control signal parameter as follows: Determining the first duty cycle and target cycle lengths of the first PWM control signal and the second PWM control signal according to a preset minimum resonant current value that causes the voltage of the switch tube in the four-switch resonant polarity converter to drop to zero within a preset dead time; A pulse width modulation (PWM) control signal is constructed according to the duration that the rising edge of the first PWM control signal precedes the rising edge of the second PWM control signal, the second duty cycle, the first duty cycle, and a target cycle length.

3. The control method of the polarity converter according to claim 2, characterized in that: The first duty cycle and the target cycle lengths of the first PWM control signal and the second PWM control signal are determined based on the preset minimum resonant current value that causes the voltage of the switch tube in the four-switch resonant polar converter to drop to zero within the dead time as follows: After the first PWM control signal rises to a high level, controlling the first PWM control signal to fall to a low level when the current value of the resonant circuit rises to the minimum resonant current value, so as to determine the first duty cycle; After the second PWM control signal drops to a low level, the second PWM control signal is controlled to rise to a high level when the current value of the resonant circuit drops to the minimum resonant current value, so as to determine the target cycle length.

4. The control method of the polarity converter according to claim 3, characterized in that: The detection point of the current value of the resonant circuit is located in the bridge arm corresponding to the input voltage value, and is located at a switch tube connected in series with the resonant circuit.

5. The control method of the polarity converter according to any one of claims 1 to 4, characterized in that: The closed-loop control algorithm is a proportional-integral PI control algorithm.

6. A control device for a polarity converter, characterized in that: include: An acquisition module is used to obtain the current input voltage value and output voltage value of the four-switch resonant polarity converter; A first calculation module is used to perform a closed-loop control algorithm calculation based on the difference between the output voltage value and the target output voltage value to obtain a closed-loop control output; The second calculation module is used in the fixed frequency control mode: Determining a current buck-boost mode of the four-switch resonant polarity converter according to a magnitude relationship between the input voltage value and the output voltage value; Based on the closed-loop control output, the input voltage value, and the output voltage value, a target control signal parameter is determined according to a preset mathematical model corresponding to the current buck-boost mode and targeting a minimum resonant circuit current value; The target control signal parameters include a phase difference between the two PWM control signals of the four-switch resonant polar converter and a duty cycle of each of the two PWM control signals; a construction module is configured to construct a pulse width modulation (PWM) control signal according to the target control signal parameters and the preset periods of the two PWM control signals, so as to control the operation of the four-switch resonant polar converter using the PWM control signal; The target control signal parameters include a phase difference between the two PWM control signals of the four-switch resonant polar converter and a duty cycle of each of the two PWM control signals; The preset mathematical model corresponding to the current buck-boost mode and aiming at minimizing the resonant circuit current value is specifically: When the buck-boost mode is buck mode: ， ， ； When the buck-boost mode is the non-voltage regulation mode: D1 and D2 are both 50% of the preset period, ; When the buck-boost mode is the boost mode: ， ， ； Wherein, D2 is the first duty cycle of the first PWM control signal of the bridge arm corresponding to the input voltage value V1, D1 is the second duty cycle of the second PWM control signal of the bridge arm corresponding to the output voltage value V2, PI Cal is the closed-loop control output, 、 、 T and T4 are both the duration during which the rising edge of the first PWM control signal precedes the rising edge of the second PWM control signal.

7. A control device for a polarity converter, characterized in that: include: memory for storing computer programs; A processor, configured to implement the steps of the method for controlling a polarity converter according to any one of claims 1 to 5 when executing the computer program.

8. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for controlling the polarity converter according to any one of claims 1 to 5 are implemented.

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