Variable frequency modulation method and device of single-stage matrix-type dual active bridge converter

Abstract

The application discloses a frequency conversion modulation method and device of a single-stage matrix-type dual active bridge converter, and the method comprises the following steps: collecting a direct-current side voltage and an alternating-current side voltage of the single-stage matrix-type dual active bridge converter; calculating an expected value of an outward moving phase angle based on the direct-current side voltage and the alternating-current side voltage, wherein the expected value of the outward moving phase angle satisfies the condition that the zero-voltage turn-on coverage of a secondary-stage switching tube is kept at a theoretical maximum value; obtaining an expected value of transmission power of the converter, calculating an expected value of a switching frequency by using a preset power transmission model based on the expected value of the transmission power and the expected value of the outward moving phase angle, and the power transmission model is configured to represent a mapping relationship between the transmission power of the converter and the switching frequency and the outward moving phase angle; and generating a switching tube driving signal according to the expected value of the outward moving phase angle and the expected value of the switching frequency. The method can maximize the zero-voltage turn-on coverage range, reduce the turn-on and switching losses, and improve the full-load efficiency.

Description

Technical Field

[0001] This application relates to the field of AC / DC power conversion, and in particular to a frequency conversion modulation method and apparatus for a single-stage matrix dual active bridge converter. Background Technology

[0002] To meet the requirements of V2G for high power density and high efficiency, compared with the traditional two-stage conversion structure of AC-DC in the front stage and DC-DC in the back stage (which has large internal electrolytic capacitors that result in large size, short life and high loss), the single-stage matrix resonant dual active bridge (DAB) converter shows significant advantages by eliminating the intermediate DC bus capacitor.

[0003] However, the input voltage of the resonant cavity in a single-stage matrix dual active bridge converter is pulsating DC at the power frequency. This causes traditional modulation strategies suitable for DC inputs (such as fixed-frequency extended phase-shift modulation) to induce extensive hard switching of the secondary-side switches, resulting in severe losses. Although existing technologies can achieve power control, the zero-voltage turn-on (ZVS) coverage of the secondary-side switches is significantly reduced under light loads, leading to a sharp increase in switching losses and limiting the converter's efficiency and reliability across the entire load range. Summary of the Invention

[0004] This application provides a frequency conversion modulation method and apparatus based on a single-stage matrix dual active bridge converter. This method can maximize the zero-voltage turn-on coverage range and reduce conduction and switching losses.

[0005] In a first aspect, this application provides a frequency conversion modulation method for a single-stage matrix-type dual active bridge converter, comprising: Collect the DC-side voltage and AC-side voltage of a single-stage matrix dual active bridge converter; Based on the DC side voltage and AC side voltage, the expected value of the outward phase angle is calculated. The expected value of the outward phase angle satisfies the requirement that the zero-voltage turn-on coverage of the secondary switch is kept at the theoretical maximum value. The expected value of the transmission power of the converter is obtained. Based on the expected value of the transmission power and the expected value of the outward phase shift angle, the expected value of the switching frequency is calculated using a preset power transmission model. The power transmission model is configured to characterize the mapping relationship between the transmission power of the converter and the switching frequency and the outward phase shift angle. Based on the expected values ​​of the external phase shift angle and the switching frequency, the drive signal for the switching transistor is generated.

[0006] In one embodiment, the desired value of the outward phase shift angle is calculated based on the DC-side voltage and the AC-side voltage, including: Obtain the transformer turns ratio of a single-stage matrix dual active bridge converter; The voltage conversion ratio is calculated based on the DC-side voltage and AC-side voltage, combined with the transformer turns ratio. Based on the voltage conversion ratio and the critical constraint condition of zero power return, the desired value of the outward phase angle that maximizes the zero-voltage turn-on coverage is determined.

[0007] In one embodiment, the desired value of the outward phase angle is obtained by taking the reciprocal of the voltage conversion ratio and performing an arcsine operation on the reciprocal.

[0008] In one embodiment, the desired value of the inner phase shift angle is calculated based on the DC-side voltage, AC-side voltage, and the desired value of the outer phase shift angle. The desired value of the inner phase shift angle satisfies the requirement that the high-frequency AC voltage and the high-frequency resonant current of the primary side of the converter are in phase.

[0009] In one embodiment, the desired value of the inward phase shift angle is calculated using the following formula: ; In the formula, This represents the expected value of the inward phase shift angle. Indicates the transformer turns ratio. Indicates the AC side voltage. Indicates the DC side voltage. This represents the expected value of the outward shift phase angle.

[0010] In one embodiment, the expected transmission power of the converter is obtained, and based on the expected transmission power and the expected outward phase shift angle, the expected switching frequency is calculated using a preset power transmission model, including: Substitute the desired value of the outward phase angle into the power transfer model, and then tune the control parameters of the closed-loop controller based on the substituted power transfer model. Based on the power transmission direction, the actual value of the converter's transmission power is collected; Based on the power error between the expected value of the transmission power and the actual value of the transmission power, a closed-loop controller is used to perform closed-loop control calculations on the power error to obtain the expected value of the switching frequency.

[0011] In one embodiment, the power transfer model is expressed by the following formula: ; In the formula, Indicates the transmission power of the converter. This represents the output voltage of the converter. Indicates the voltage conversion ratio. , Indicates switching frequency f sw With resonant frequency f r The ratio, Z 0 represents the characteristic impedance of the resonant cavity. This indicates the outward phase shift angle.

[0012] Secondly, this application also provides a frequency conversion modulation device for a single-stage matrix-type dual active bridge converter, comprising: The acquisition module is configured to acquire the DC-side voltage and AC-side voltage of a single-stage matrix dual active bridge converter; The ZVS optimization module is configured to calculate the desired value of the outward phase angle based on the DC side voltage and the AC side voltage. The desired value of the outward phase angle satisfies the requirement that the zero-voltage turn-on coverage of the secondary switch is kept at the theoretical maximum value. The bidirectional power control module is configured to obtain the expected value of the converter's transmission power, and calculate the expected value of the switching frequency based on the expected value of the transmission power and the expected value of the outward phase shift angle using a preset power transmission model. The power transmission model is configured to characterize the mapping relationship between the converter's transmission power and the switching frequency and the outward phase shift angle. The PWM wave generation module is configured to generate a switching transistor drive signal based on the desired value of the outward phase shift angle and the desired value of the switching frequency.

[0013] In one embodiment, the frequency conversion modulation device further includes: The zero-power return current control module is configured to calculate the desired inner phase angle based on the DC-side voltage, AC-side voltage, and the desired outer phase angle. The desired inner phase angle satisfies the requirement that the high-frequency AC voltage and high-frequency resonant current of the primary side of the converter are in phase.

[0014] In one embodiment, the bidirectional power control module is configured to substitute the desired value of the outward phase angle into the power transmission model, and tune the control parameters of the closed-loop controller based on the substituted power transmission model. Based on the power transmission direction, the actual value of the converter's transmission power is collected; Based on the power error between the expected value of the transmission power and the actual value of the transmission power, a closed-loop controller is used to perform closed-loop control calculations on the power error to obtain the expected value of the switching frequency.

[0015] The aforementioned frequency conversion modulation method for a single-stage matrix-type dual active bridge converter involves: acquiring the DC-side and AC-side voltages of the converter; calculating the desired outward phase angle based on the acquired voltages; obtaining the desired power transmission value of the converter; and combining the desired outward phase angle with the desired power transmission value to calculate the desired switching frequency using a preset power transmission model; finally, generating the final switching transistor drive signal based on the desired outward phase angle and the desired switching frequency. This method, by determining the desired outward phase angle and adjusting the active power using the switching frequency, enables the secondary switching transistor to maintain an extremely high zero-voltage turn-on coverage rate across the entire load range, especially under light load conditions, thereby reducing switching losses. It effectively solves the problem of efficiency degradation under light load in traditional fixed-frequency modulation and broadens the high-efficiency operating range of the converter. Attached Figure Description

[0016] Figure 1 This is a flowchart of a frequency conversion modulation method for a single-stage matrix dual active bridge converter in one embodiment; Figure 2 This is a circuit topology diagram of a single-stage matrix dual active bridge converter in one embodiment; Figure 3 This is a schematic diagram of the ZVS coverage of the secondary switch in one embodiment; Figure 4 This is a closed-loop control circuit diagram of a PI controller in one embodiment; Figure 5 The following is a timing waveform diagram of the frequency conversion modulation method of a single-stage matrix dual active bridge converter in one embodiment; Figure 6 This is a comparison curve of ZVS coverage for the frequency conversion modulation method of a single-stage matrix dual active bridge converter in one embodiment. Figure 7 This is a frame diagram of a frequency conversion modulation device for a single-stage matrix dual active bridge converter in one embodiment. Detailed Implementation

[0017] The present application will be described in detail below with reference to the specific embodiments shown in the accompanying drawings. However, these embodiments do not limit the present application. Any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the protection scope of the present application.

[0018] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0019] In one embodiment, such as Figure 1 As shown, a frequency conversion modulation method for a single-stage matrix-type dual active bridge converter is provided. The frequency conversion modulation method includes the following steps: Step 101: Collect the DC-side voltage and AC-side voltage of the single-stage matrix dual active bridge converter; Specifically, the circuit topology of a single-stage matrix-type dual active bridge converter is as follows: Figure 2 As shown, the left side is the AC input filter circuit, including the AC side voltage. AC side current Input filter inductor and parallel input filter capacitors .

[0020] The AC input filter circuit is used to filter out high-frequency harmonics and provide a stable AC input voltage. The middle section is the primary full-bridge switching transistor (consisting of eight switching transistors with anti-parallel diodes). - (This constitutes a full-bridge structure) responsible for converting the pulsating DC power from the front-stage rectifier into high-frequency AC power to drive the transformer for energy transfer. The current flowing through the primary full-bridge switching transistor is... The voltage before the transformer transforms is After the transformer transforms the voltage, the voltage is .

[0021] The right side shows the secondary full-bridge switching transistors, consisting of four transistors Q1, Q2, Q3, and Q4. These transistors are used to rectify the high-frequency AC power into DC output. The current flowing through the secondary full-bridge switching transistors is... The voltage flowing through the secondary full-bridge switch is The resonant cavity is composed of a resonant inductor. and resonant capacitor It is composed of series components and utilizes resonant characteristics to achieve power transmission and soft switching.

[0022] The rightmost part is the DC output filter circuit, including the output filter inductor. and output filter capacitor The DC output filter circuit is used to smooth the DC output voltage. The load current is marked as Specifically, collecting the DC-side voltage involves collecting the capacitance of the rightmost DC bus. voltage at both ends (i.e., DC side voltage) ).

[0023] Step 102: Based on the DC side voltage and AC side voltage, calculate the expected value of the outward phase angle. The expected value of the outward phase angle satisfies the requirement that the zero-voltage turn-on coverage of the secondary switch is kept at the theoretical maximum value. Specifically, using the collected DC-side and AC-side voltage amplitudes, combined with the known transformer turns ratio, the voltage conversion ratio, reflecting the current input-output voltage relationship, is calculated. Furthermore, the voltage conversion ratio is substituted into a preset formula to solve for the corresponding expected value of the outward phase shift angle.

[0024] It should be noted that this desired external phase angle can minimize the resonant current to reduce conduction losses, and also enable the secondary full-bridge switch to maintain a near-theoretical maximum zero-voltage turn-on coverage rate across the entire power range, thereby reducing switching losses and improving control efficiency.

[0025] Step 103: Obtain the expected transmission power of the converter. Based on the expected transmission power and the expected external phase shift angle, calculate the expected switching frequency using a preset power transmission model. The power transmission model is configured to characterize the mapping relationship between the converter's transmission power and the switching frequency and the external phase shift angle. Specifically, a power transmission model is pre-established that describes the mapping relationship between transmitted power, switching frequency, and outward phase shift angle. Then, the acquired expected transmitted power value and the expected outward phase shift angle value calculated in the previous steps are substituted into this power transmission model to calculate the expected switching frequency value required to achieve the power target.

[0026] Step 104: Generate the switching transistor drive signal based on the expected value of the external phase shift angle and the expected value of the switching frequency.

[0027] Specifically, based on the expected switching frequency and the expected external phase angle, PWM drive signals are generated to drive all switching transistors of the primary and secondary full-bridge circuits.

[0028] The PWM drive signal enables the primary full-bridge converter to generate a square wave with the desired switching frequency on one side of the resonant cavity, while simultaneously enabling the secondary full-bridge converter to generate a stepped wave with the same frequency but a specific internal pulse width, and ensuring that the stepped wave as a whole has a fixed phase difference relative to the primary square wave, determined by the desired outward phase angle.

[0029] In this embodiment, by determining the desired value of the outward phase shift angle and adjusting the active power using the switching frequency, the method enables the secondary switch to maintain an extremely high zero-voltage turn-on coverage rate across the entire load range, especially under light load conditions, thereby reducing switching losses. This effectively solves the problem of efficiency degradation under light load in traditional fixed-frequency modulation and broadens the high-efficiency operating range of the converter.

[0030] In one embodiment, the expected value of the outward phase shift angle is calculated based on the DC-side voltage and the AC-side voltage, including: Obtain the transformer turns ratio of a single-stage matrix dual active bridge converter; The voltage conversion ratio is calculated based on the DC-side voltage and AC-side voltage, combined with the transformer turns ratio. Based on the voltage conversion ratio and the critical constraint condition of zero power return, the desired value of the outward phase angle that maximizes the zero-voltage turn-on coverage is determined.

[0031] Specifically, the turns ratio of the high-frequency transformer in a single-stage matrix-type dual active bridge converter is obtained. The turns ratio These are the inherent structural parameters of the converter, which are usually known constants.

[0032] Furthermore, based on the real-time acquired DC-side voltage and the amplitude of AC side voltage Based on the transformer turns ratio n, and using the formula Calculate the voltage conversion ratio of the converter .

[0033] Furthermore, utilizing this voltage conversion ratio Based on the critical constraint condition of zero-power return, the desired value of the outward phase shift angle is calculated and determined. Among them, the expected value of the outward shift phase angle. By taking the voltage conversion ratio The reciprocal of the given value is obtained by performing an arcsine operation on the reciprocal, and the expected value of the outward shift phase angle is then calculated. The calculation formula is: .

[0034] At this point, the calculated expected value of the outward phase angle It can maximize zero-voltage turn-on coverage.

[0035] Zero-voltage turn-on coverage of the secondary switching transistor The calculation formula is: .

[0036] Zero-voltage turn-on coverage of the secondary switching transistor Schematic diagram as follows Figure 3 As shown. Figure 3 Divided into three parts by solid and dashed black lines. The blue area represents the secondary full-bridge switch being in a hard-switching state throughout the entire power frequency cycle, resulting in significant switching losses. The red area represents the converter failing to achieve zero-power return, leading to significant conduction losses. To maximize the ZVS coverage of the secondary full-bridge switch, the phase angle should be shifted outwards. Locked onto a specific dashed line, which corresponds to any given voltage conversion ratio. Below, the optimal operating point is the point at which the converter can make the ZVS coverage of the secondary switch close to the theoretical maximum value (in order to minimize switching losses).

[0037] In one embodiment, the desired value of the inner phase shift angle is calculated based on the DC-side voltage, AC-side voltage, and the desired value of the outer phase shift angle. The desired value of the inner phase shift angle satisfies the requirement that the high-frequency AC voltage and high-frequency resonant current of the primary side of the converter are in phase.

[0038] Specifically, based on DC side voltage and AC side voltage amplitude Expected value of outward shift phase angle and transformer turns ratio Calculate the expected value of the inner phase shift angle. D 2. Expected value of the inward shift phase angle D The formula for calculating 2 is as follows: .

[0039] Among them, the expected value of the inner phase shift angle D 2 is defined as the ratio of the high-level time of the secondary full-bridge output voltage to the switching cycle within one switching cycle, and is proportional to the inner phase shift angle of the secondary full-bridge. Due to the AC side voltage amplitude... Since it is a sinusoidal voltage at power frequency, the calculated inner phase shift angle D2 will follow... It is dynamically adjusted according to the instantaneous changes in the phase angle. It should be noted that the expected value of the outward phase angle at this time... To maximize the ZVS coverage of the secondary full-bridge switching transistors.

[0040] When the desired value of the inner phase shift angle D 2. When the above calculation relationship is satisfied, it can be ensured that the high-frequency AC voltage and high-frequency resonant current of the primary full-bridge switch are in phase, thereby realizing zero-power return current control, minimizing the resonant current, reducing conduction losses, and improving the overall efficiency of the converter.

[0041] In one embodiment, the expected transmission power of the converter is obtained, and based on the expected transmission power and the expected outward phase shift angle, the expected switching frequency is calculated using a preset power transmission model, including: Substitute the desired value of the outward phase angle into the power transfer model, and then tune the control parameters of the closed-loop controller based on the substituted power transfer model. Based on the power transmission direction, the actual value of the converter's transmission power is collected; Based on the power error between the expected value of the transmission power and the actual value of the transmission power, a closed-loop controller is used to perform closed-loop control calculations on the power error to obtain the expected value of the switching frequency.

[0042] Specifically, the calculation formula for the preset power transfer model is as follows: ; in, r Defined as switching frequency f sw With resonant frequency f r The ratio. Resonant frequency. f r Defined as . Z0 is the characteristic impedance of the resonant cavity, defined as . It is a resonant inductor. It is a resonant capacitor.

[0043] The expected value of the outward shift phase angle and voltage conversion ratio Substituting into the power transfer model, we can obtain: .

[0044] Substituting the expected value of the outward phase angle and voltage conversion ratio Then, the power transfer model is simplified to power transfer. Regarding the switching frequency of a single control variable f sw The functional relationship. Based on this functional relationship, the closed-loop controller used for power closed-loop control (such as...) can be... Figure 4 The control parameters of the PI controller (shown) are tuned.

[0045] The closed-loop controller acquires the AC side voltage of the converter in real time. With AC side current and DC side voltage With DC side current Based on the current operating mode (i.e., the direction of power transmission, such as charging the vehicle from the grid or feeding energy back to the grid from the vehicle), the actual value of the converter's current transmission power is calculated using the corresponding power calculation formula.

[0046] The expected transmission power of the converter is obtained and compared with the calculated actual transmission power to obtain the power error between the two. This power error is then input as follows: Figure 4 The PI controller shown is used to calculate and adjust the power error in real time based on an internal control algorithm (such as proportional-integral operation). The output is the desired switching frequency. f sw .

[0047] It should be noted that when the actual transmitted power is lower than the expected transmitted power, the closed-loop controller will increase the switching frequency to increase the transmitted power; conversely, it will decrease the switching frequency to reduce the transmitted power. Through the closed-loop control process, the converter's transmitted power can be accurately tracked to the expected value.

[0048] In one embodiment, the frequency conversion modulation method of the single-stage matrix dual active bridge converter provided in this application is used for performance verification and analysis. For example... Figure 5 The timing waveform diagram shown represents a switching cycle T. sInternally, specific energy transfer and soft-switching characteristics are achieved by controlling the driving timing of each switching transistor.

[0049] By S 1b / S 4b and S 2b / S 3b The high-frequency switching group is alternately turned on, and an inner phase shift angle D2T is generated during the intermediate dead time. s From Q1 The secondary full bridge, consisting of Q4, has a capacity of 0.5T. s It operates with a fixed duty cycle. The transformer primary voltage V... p2 (Blue solid line) and AC power supply voltage V s (Black solid line) Maintain the expected value of the outward shifted phase angle between them .

[0050] At this time, the resonant current i s It exhibits sinusoidal ripple characteristics, and the current waveform matches the voltage waveform during time periods such as t1 to t2 and t3 to t4, achieving zero power return, eliminating reactive circulating current in traditional phase-shift control, and reducing conduction losses.

[0051] Furthermore, such as Figure 6 The ZVS coverage comparison curve shown verifies the actual performance of the frequency conversion modulation method of the single-stage matrix dual active bridge converter described above. The horizontal axis represents the average transmission power P. av The vertical axis represents the zero-voltage turn-on (ZVS) coverage η of the secondary-side switching transistor.

[0052] Comparing the two curves, it can be seen that the traditional fixed-frequency phase-shift control has a ZVS coverage of 0% under light load (e.g., 5000W), and even under full load (8000W), it can only achieve a coverage of about 67%. The frequency conversion modulation method proposed in this application exhibits excellent full-range ZVS characteristics, with the coverage almost maintained at around 72%. In the low-to-medium load range (around 6500W), the coverage reaches as high as 71.94%, which is a significant improvement compared to the 52.97% of the traditional method at this power point.

[0053] The frequency conversion modulation method disclosed in this application demonstrates that the ZVS coverage of the secondary switching transistor under light load conditions is improved by approximately 72% compared to traditional EPS modulation, which essentially eliminates the hard switching phenomenon under light load and ensures soft switching of the switching transistor over a wide power range, thereby reducing switching losses.

[0054] Based on the same concept, such as Figure 7 This application also provides a frequency conversion modulation device for a single-stage matrix-type dual active bridge converter, comprising: The acquisition module is configured to acquire the DC-side voltage and AC-side voltage of a single-stage matrix dual active bridge converter; The ZVS optimization module is configured to calculate the desired value of the outward phase angle based on the DC side voltage and the AC side voltage. The desired value of the outward phase angle satisfies the requirement that the zero-voltage turn-on coverage of the secondary switch is kept at the theoretical maximum value. The bidirectional power control module is configured to obtain the expected value of the converter's transmission power, and calculate the expected value of the switching frequency based on the expected value of the transmission power and the expected value of the outward phase shift angle using a preset power transmission model. The power transmission model is configured to characterize the mapping relationship between the converter's transmission power and the switching frequency and the outward phase shift angle. The PWM wave generation module is configured to generate a switching transistor drive signal based on the desired value of the outward phase shift angle and the desired value of the switching frequency.

[0055] In one embodiment, the frequency modulation device further includes: The zero-power return current control module is configured to calculate the desired inner phase angle based on the DC-side voltage, AC-side voltage, and the desired outer phase angle. The desired inner phase angle satisfies the requirement that the high-frequency AC voltage and high-frequency resonant current of the primary side of the converter are in phase.

[0056] Preferably, the AC power supply outputs AC side voltage. AC side current It should be noted that the AC side voltage and AC side current It needs to be filtered by an EMI filter module to suppress electromagnetic interference.

[0057] Furthermore, the AC side voltage after filtering AC side current Entering the switching transistor S xa S xb A primary full-bridge switching transistor (where x = 1, 2, 3, 4) converts AC to high-frequency AC. This is achieved through an intermediate high-frequency isolation transformer with a turns ratio of 1:n. The secondary winding of this transformer is connected to a resonant inductor. and resonant capacitor The resonant cavity is formed by these components. The secondary side of the transformer is connected to a full-bridge switching transistor group consisting of transistors Q1-Q4, responsible for rectifying the high-frequency AC power. The rightmost component is a DC-side filter (composed of inductors and capacitors), which outputs DC power to supply the DC-side voltage of the DC power supply. DC side current .

[0058] The acquisition module collects the AC side voltage of the AC power supply of the single-stage matrix dual active bridge converter in real time through sensors. AC side current and the DC side voltage of the DC power supply DC side current .

[0059] The area within the dashed box represents the controller, which receives feedback signals from both AC and DC power sources, including AC side voltage. and AC side current (Red line input), and DC side voltage and DC side current (Blue line input). The controller includes a bidirectional power control module, a zero-power return control module, and a ZVS optimization module.

[0060] The ZVS optimization module receives AC side voltage at its input. and DC side voltage . use and Based on the known transformer turns ratio n, the voltage conversion ratio is calculated. Furthermore, by taking the voltage conversion ratio... The reciprocal of the given value is obtained by performing an arcsine operation on the reciprocal, and the expected value of the outward shift phase angle is then calculated. Expected value of the outward shift phase angle Designed to lock the converter's operating point onto an optimal trajectory that allows the secondary switch's zero-voltage turn-on (ZVS) coverage to approach its theoretical maximum. The ZVS optimization module's output displays the calculated desired outward phase shift angle. Simultaneously, the signal is sent to the PWM wave generation module, the bidirectional power control module, and the zero-power return control module.

[0061] The input terminal of the bidirectional power control module receives the AC side voltage output from the AC power supply. and AC side current DC side voltage of DC power supply output and DC side current Expected transmission power and expected outward phase angle The power error is obtained by comparing the expected power value with the actual power value, and this error signal is input into a closed-loop controller. The closed-loop controller is adjusted based on a preset power transfer model, which defines the mapping relationship between the transferred power, switching frequency, and outward phase shift angle. Through the closed-loop operation of the controller, the bidirectional power control module dynamically generates the expected switching frequency value. f sw Expected switching frequency f sw It can be used as a direct control variable to adjust the transmission power. The output of the bidirectional power control module will then... f sw The value is sent to the PWM wave generation module.

[0062] The input of the zero-power return current control module receives the AC side voltage. and DC side voltage and the expected value of the outward shift phase angle The desired value of the inner phase shift angle D2 is calculated based on the received parameters. This is due to the AC side voltage... Since it is a sinusoidal quantity at the power frequency, the expected value of the inner phase shift angle D2 will change with its instantaneous value, thereby ensuring that the high-frequency voltage and current of the transformer primary are in phase, thus achieving zero-power return current control to minimize resonant current and conduction losses. The output of the zero-power return current control module sends this calculated expected value of the inner phase shift angle D2 to the PWM wave generation module.

[0063] The PWM wave generation module receives the desired value of the outward phase shift angle. Switching frequency f sw After the desired phase shift angle D2 is obtained, a specific pulse signal is generated to drive the switching action of the primary full bridge and the secondary full bridge, thereby achieving high-efficiency operation of the converter.

[0064] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means.

[0065] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. The above are merely preferred embodiments of this application and are not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application are included within the scope of protection of this application.

Claims

1. A frequency conversion modulation method for a single-stage matrix-type dual active bridge converter, characterized in that, The frequency conversion modulation method includes: The DC-side voltage and AC-side voltage of the single-stage matrix dual active bridge converter are collected; Based on the DC side voltage and AC side voltage, the expected value of the outward phase angle is calculated, which satisfies the requirement that the zero-voltage turn-on coverage of the secondary switch be kept at the theoretical maximum value. Obtain the expected transmission power of the converter. Based on the expected transmission power and the expected outward phase angle, calculate the expected switching frequency using a preset power transmission model. The power transmission model is configured to characterize the mapping relationship between the converter's transmission power and the switching frequency and the outward phase angle. Based on the expected value of the outward phase angle and the expected value of the switching frequency, a switching transistor drive signal is generated.

2. The frequency conversion modulation method for a single-stage matrix-type dual active bridge converter according to claim 1, characterized in that, Based on the DC-side voltage and AC-side voltage, the expected value of the outward phase shift angle is calculated, including: Obtain the transformer turns ratio of the single-stage matrix dual active bridge converter; Based on the DC-side voltage and AC-side voltage, and in conjunction with the transformer turns ratio, the voltage conversion ratio is calculated. Based on the voltage conversion ratio, and according to the critical constraint condition of zero power return, the desired value of the outward phase angle that maximizes the zero voltage turn-on coverage is determined.

3. The frequency conversion modulation method for a single-stage matrix-type dual active bridge converter according to claim 2, characterized in that, The desired value of the outward phase angle is obtained by taking the reciprocal of the voltage conversion ratio and performing an arcsine operation on the reciprocal.

4. The frequency conversion modulation method for a single-stage matrix-type dual active bridge converter according to claim 1 or 2, characterized in that, The frequency conversion modulation method further includes: Based on the DC-side voltage, the AC-side voltage, and the expected value of the outer phase shift angle, the expected value of the inner phase shift angle is calculated. The expected value of the inner phase shift angle satisfies the requirement that the high-frequency AC voltage and the high-frequency resonant current of the primary side of the converter are in phase.

5. The frequency conversion modulation method for a single-stage matrix-type dual active bridge converter according to claim 4, characterized in that, The desired value of the inner phase shift angle is calculated using the following formula: ； In the formula, This represents the expected value of the inward phase shift angle. Indicates the transformer turns ratio. This indicates the AC side voltage. This represents the DC-side voltage. This represents the expected value of the outward shift phase angle.

6. The frequency conversion modulation method for a single-stage matrix-type dual active bridge converter according to claim 1, characterized in that, The step of obtaining the expected transmission power value of the converter, and calculating the expected switching frequency value based on the expected transmission power value and the expected outward phase shift angle using a preset power transmission model, includes: Substitute the desired value of the outward phase angle into the power transmission model, and tune the control parameters of the closed-loop controller based on the substituted power transmission model; Based on the power transmission direction, the actual value of the converter's transmission power is collected; Based on the power error between the expected transmission power and the actual transmission power, the closed-loop controller is used to perform closed-loop control calculations on the power error to obtain the expected switching frequency.

7. The frequency conversion modulation method for a single-stage matrix-type dual active bridge converter according to claim 6, characterized in that, The power transfer model is expressed by the following formula: ； In the formula, Indicates the transmission power of the converter. This represents the output voltage of the converter. Indicates the voltage conversion ratio. , This represents the ratio of the switching frequency to the resonant frequency. Z 0 represents the characteristic impedance of the resonant cavity. This indicates the outward phase shift angle.

8. A frequency conversion modulation device for a single-stage matrix-type dual active bridge converter, characterized in that, include: The acquisition module is configured to acquire the DC-side voltage and AC-side voltage of the single-stage matrix dual active bridge converter; The ZVS optimization module is configured to calculate the desired value of the outward phase angle based on the DC side voltage and the AC side voltage. The desired value of the outward phase angle satisfies the requirement that the zero-voltage turn-on coverage of the secondary switch is kept at the theoretical maximum value. A bidirectional power control module is configured to acquire the expected transmission power of the converter, and based on the expected transmission power and the expected outward phase angle, calculate the expected switching frequency using a preset power transmission model. The power transmission model is configured to characterize the mapping relationship between the transmission power of the converter and the switching frequency and the outward phase angle. The PWM wave generation module is configured to generate a switching transistor drive signal based on the expected value of the outward phase shift angle and the expected value of the switching frequency.

9. The frequency conversion modulation device for a single-stage matrix-type dual active bridge converter according to claim 8, characterized in that, The frequency conversion modulation device further includes: The zero-power return current control module is configured to calculate the desired inner phase angle based on the DC side voltage, the AC side voltage, and the desired outer phase angle, wherein the desired inner phase angle satisfies the requirement that the high-frequency AC voltage and the high-frequency resonant current of the primary side of the converter are in phase.

10. The frequency conversion modulation device for a single-stage matrix-type dual active bridge converter according to claim 8, characterized in that, The bidirectional power control module is configured to substitute the desired value of the outward phase angle into the power transmission model, and tune the control parameters of the closed-loop controller based on the substituted power transmission model. Based on the power transmission direction, the actual value of the converter's transmission power is collected; Based on the power error between the expected transmission power and the actual transmission power, the closed-loop controller is used to perform closed-loop control calculations on the power error to obtain the expected switching frequency.

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