Control method, device and storage medium of power converter

Abstract

The present application discloses a control method, device and storage medium of a power converter, the method comprising: when the input voltage of the voltage input unit is greater than the output voltage of the voltage output unit, determining the target duty cycle of the second upper bridge arm switch tube, and controlling the conduction time of the first upper bridge arm switch tube according to the target duty cycle to adjust the duty cycle of the first upper bridge arm switch tube, wherein the duty cycle of the first lower bridge arm switch tube is complementary to the duty cycle of the first upper bridge arm switch tube, and the duty cycle of the second lower bridge arm switch tube is complementary to the duty cycle of the second upper bridge arm switch tube; when the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit, fixing the duty cycle of the first upper bridge arm switch tube, and controlling the conduction time of the second lower bridge arm switch tube until the input voltage is less than the output voltage and the output voltage no longer increases. By adopting the present application, seamless switching of a four-switch DC / DC power converter can be conveniently and efficiently realized, reducing switching losses.

Description

Technical Field

[0001] The present application relates to the field of power electronic control, and in particular to a control method, device and storage medium for a power converter. Background Art

[0002] The four-switch DC / DC power converter has been widely used in applications where isolation is not required because it has fewer switching devices and can achieve bidirectional energy flow. Although the four-switch DC / DC power converter has only four switching devices, the control strategy is extremely complex. For example, the entire control area can be divided into three modes: BUCK, BUCK-BOOST, and BOOST according to the relationship between the input voltage and the output voltage, and the output voltage is adjusted as the mode is switched. However, in this control strategy, there will be crossover parts when the three modes are switched, resulting in reduced control performance of the power converter. For another example, the four-switch DC / DC power converter can be regarded as a BUCK bridge arm and a BOOST bridge arm connected in series, and controlled according to the BUCK-BOOST (buck-boost) mode, and the output voltage is adjusted by adjusting the duty cycle. However, in this control strategy, since the four switch tubes are performing a large range of switching actions, the switching loss is large and the efficiency is low. Summary of the invention

[0003] Based on the above problems, the embodiments of the present application provide a control method, device and storage medium for a power converter, which can conveniently and efficiently realize seamless switching of a four-switch DC / DC power converter and reduce switching losses.

[0004] In a first aspect, an embodiment of the present application provides a control method for a power converter, wherein the power converter comprises: a buck unit, a boost unit, a voltage input unit, and a voltage output unit, wherein one end of the buck unit is connected to the voltage input unit, the other end of the buck unit is connected to the boost unit via an inductor, and the other end of the boost unit is connected to the voltage output unit, the buck unit comprises a first upper bridge arm switch tube and a first lower bridge arm switch tube connected in series, and the boost unit comprises a second upper bridge arm switch tube and a second lower bridge arm switch tube connected in series, and the method comprises:

[0005] When the input voltage of the voltage input unit is greater than the output voltage of the voltage output unit, a target duty cycle of the second upper bridge arm switch tube is determined, and the conduction time of the first upper bridge arm switch tube is controlled according to the target duty cycle to adjust the duty cycle of the first upper bridge arm switch tube, wherein the duty cycle of the first lower bridge arm switch tube is complementary to the duty cycle of the first upper bridge arm switch tube, and the duty cycle of the second lower bridge arm switch tube is complementary to the duty cycle of the second upper bridge arm switch tube;

[0006] When the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit, the duty cycle of the first upper bridge arm switch tube is fixed, and the conduction time of the second lower bridge arm switch tube is controlled until the input voltage is less than the output voltage and the output voltage no longer increases.

[0007] In combination with the first aspect, in a possible implementation manner, controlling the on-time of the first upper bridge arm switch tube according to the target duty cycle to adjust the duty cycle of the first upper bridge arm switch tube includes:

[0008] Determine an adjustment range of the duty cycle of the first upper bridge arm switch tube according to the target duty cycle, wherein the adjustment range of the duty cycle of the first upper bridge arm switch tube is greater than 0 and less than or equal to the duty cycle of the second upper bridge arm switch tube;

[0009] The on-time of the first upper bridge arm switch tube is controlled according to the adjustment range of the duty cycle of the first upper bridge arm switch tube to adjust the duty cycle of the first upper bridge arm switch tube.

[0010] In combination with the first aspect, in a possible implementation manner, fixing the duty cycle of the first upper bridge arm switch tube includes:

[0011] The duty cycle of the first upper bridge arm switch tube is fixed according to the target duty cycle, wherein the duty cycle of the first upper bridge arm switch tube is the same as the target duty cycle.

[0012] In combination with the first aspect, in a possible implementation manner, controlling the conduction time of the second lower bridge arm switch tube includes:

[0013] Determining the duty cycle of the second lower bridge arm switch tube according to the loop output duty cycle and the duty cycle coefficient of the power converter, wherein when the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit, the duty cycle coefficient is the difference between the duty cycle of the first upper bridge arm switch tube and the duty cycle of the first lower bridge arm switch tube, and the loop output duty cycle is equal to the duty cycle of the first upper bridge arm switch tube;

[0014] The conduction time length of the second lower bridge arm switch tube is controlled according to the duty cycle of the second lower bridge arm switch tube.

[0015] In combination with the first aspect, in a possible implementation manner, the duty cycle of the second lower bridge arm switch tube is less than the sum of the target duty cycle and the duty cycle coefficient, and is greater than or equal to the target duty cycle.

[0016] In combination with the first aspect, in a possible implementation manner, the method further includes:

[0017] The voltage gain of the output voltage is determined according to the duty cycle of the first upper bridge arm switch tube and the duty cycle of the second upper bridge arm switch tube.

[0018] In a second aspect, the present application provides a control device for a power converter, wherein the power converter includes: a buck unit, a boost unit, a voltage input unit, and a voltage output unit, wherein one end of the buck unit is connected to the voltage input unit, the other end of the buck unit is connected to the boost unit through an inductor, and the other end of the boost unit is connected to the voltage output unit, the buck unit includes a first upper bridge arm switch tube and a first lower bridge arm switch tube connected in series, the boost unit includes a second upper bridge arm switch tube and a second lower bridge arm switch tube connected in series, and the device includes:

[0019] A first determining module, configured to determine a target duty cycle of the second upper bridge arm switch tube when the input voltage of the voltage input unit is greater than the output voltage of the voltage output unit;

[0020] A first control module, configured to control the on-time of the first upper bridge arm switch tube according to the target duty cycle to adjust the duty cycle of the first upper bridge arm switch tube, wherein the duty cycle of the first lower bridge arm switch tube is complementary to the duty cycle of the first upper bridge arm switch tube, and the duty cycle of the second lower bridge arm switch tube is complementary to the duty cycle of the second upper bridge arm switch tube;

[0021] A fixing module, used for fixing the duty cycle of the first upper bridge arm switch tube when the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit;

[0022] The second control module is used to control the conduction time of the second lower bridge arm switch tube until the input voltage is less than the output voltage and the output voltage no longer increases.

[0023] In conjunction with the second aspect, in a possible implementation manner, the first control module is further configured to:

[0024] Determine the adjustment range of the duty cycle of the first upper bridge arm switch tube according to the target duty cycle, wherein the adjustment range of the duty cycle of the first upper bridge arm switch tube is greater than 0 and less than or equal to the duty cycle of the second upper bridge arm switch tube;

[0025] The on-time of the first upper bridge arm switch tube is controlled according to the adjustment range of the duty cycle of the first upper bridge arm switch tube to adjust the duty cycle of the first upper bridge arm switch tube.

[0026] In conjunction with the second aspect, in a possible implementation manner, the fixing module is used to:

[0027] The duty cycle of the first upper bridge arm switch tube is fixed according to the target duty cycle, wherein the duty cycle of the first upper bridge arm switch tube is the same as the target duty cycle.

[0028] In conjunction with the second aspect, in a possible implementation manner, the second control module is further configured to:

[0029] Determining the duty cycle of the second lower bridge arm switch tube according to the loop output duty cycle and the duty cycle coefficient of the power converter, wherein when the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit, the duty cycle coefficient is the difference between the duty cycle of the first upper bridge arm switch tube and the duty cycle of the first lower bridge arm switch tube, and the loop output duty cycle is equal to the duty cycle of the first upper bridge arm switch tube;

[0030] The conduction time length of the second lower bridge arm switch tube is controlled according to the duty cycle of the second lower bridge arm switch tube.

[0031] In combination with the second aspect, in a possible implementation manner, the duty cycle of the second lower bridge arm switch tube is less than the sum of the target duty cycle and the duty cycle coefficient, and is greater than or equal to the target duty cycle.

[0032] In conjunction with the second aspect, in a possible implementation manner, the above device further includes:

[0033] The second determination module is used to determine the voltage gain of the output voltage according to the duty cycle of the first upper bridge arm switch tube and the duty cycle of the second upper bridge arm switch tube.

[0034] In a third aspect, the present application provides a computer device, including: a processor, a memory, and a network interface;

[0035] The processor is connected to a memory and a network interface, wherein the network interface is used to provide a data communication function, the memory is used to store program code, and the processor is used to call the program code to execute the method executed by the above-mentioned first aspect and any possible implementation method of the first aspect in the present application.

[0036] In a fourth aspect, the present application provides a computer-readable storage medium, which stores a computer program, and the computer program includes program instructions. When the program instructions are executed by a processor, they execute the method performed by the above-mentioned first aspect of the present application and any possible implementation method of the first aspect.

[0037] In the present application, when the input voltage of the voltage input unit is greater than the output voltage of the voltage output unit, the target duty cycle of the second upper bridge arm switch tube is determined, and the conduction time of the first upper bridge arm switch tube is controlled according to the target duty cycle to adjust the duty cycle of the first upper bridge arm switch tube. When the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit, the duty cycle of the first upper bridge arm switch tube is fixed, and the duty cycle of the second lower bridge arm switch tube is determined according to the loop output duty cycle coefficient of the power converter, wherein the duty cycle coefficient is the difference between the duty cycle of the first upper bridge arm switch tube and the duty cycle of the first lower bridge arm switch tube, the loop output duty cycle is equal to the duty cycle of the first upper bridge arm switch tube, and the conduction time of the second lower bridge arm is controlled according to the duty cycle of the second lower bridge arm switch tube until the input voltage is less than the output voltage and the output voltage no longer increases, thereby realizing the function of boosting. This control strategy only has BUCK (step-down) mode and BOOST (step-up) mode, but no BUCK-BOOST (step-down-step-up) mode. It reduces switching losses, improves energy transmission efficiency, and realizes seamless switching of the working modes of the four-switch DC / DC power converter in a simpler and more convenient way. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a structural schematic diagram of a four-switch DC / DC power converter provided by the present application;

[0039] Figure 2 It is a waveform simulation schematic diagram provided by this application;

[0040] Figure 3 It is a flow chart of a control method of a power converter provided by this invention;

[0041] Figure 4 is another flow chart of a control method for a power converter provided by the present application;

[0042] Figure 5 It is a structural schematic diagram of a control device of a power converter provided by the present application;

[0043] Figure 6 is another structural schematic diagram of a control device for a power converter provided by the present application;

[0044] Figure 7 It is a structural schematic diagram of the computer device provided by this application. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in this application to clearly and completely describe the technical solutions in this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0046] The control method of the power converter provided in the present application can be applied to a four-switch DC / DC power converter. When the above-mentioned four-switch DC / DC power converter is used in an electric vehicle, it is mainly used to convert the frequently fluctuating battery pack voltage into a stable voltage to provide electric energy for the electric vehicle drive system, thereby enhancing the stability of the electric vehicle drive system. This is because the motor in the electric vehicle drive system is a typical active load, which can absorb the battery pack electric energy and convert it into mechanical energy output, and can also convert mechanical energy into electric energy and feed it back to the battery pack. However, since the speed range of the motor in the electric vehicle is very wide, the range of variation of the battery voltage during the operation of the electric vehicle is also very large. Under such conditions, if the battery pack is used to directly drive the motor to operate, it will cause the deterioration of the motor driving performance. The use of the above-mentioned four-switch DC / DC power converter can stabilize the voltage of the battery pack at a relatively high voltage value within a certain load range, thereby significantly enhancing the stability of the above-mentioned electric vehicle drive system. The electric vehicle adopts the above-mentioned four-switch DC / DC power converter to optimize the motor control and improve the overall driving performance of the electric vehicle. On this basis, an embodiment of the present application proposes a control method for a power converter, which is applicable to the above-mentioned four-switch DC / DC power converter. It can complete bidirectional energy transmission according to actual needs while keeping the polarity of the DC voltage at both ends of the four-switch DC / DC power converter unchanged, thereby reducing switching losses, improving the efficiency of energy transmission, and more simply and conveniently realizing seamless switching of the working mode of the four-switch DC / DC power converter.

[0047] See also Figure 1 , Figure 1 Schematic diagram of a four-switch DC / DC power converter. Figure 1As shown, the four-switch DC / DC power converter includes: a buck unit 1, a boost unit 2, a voltage input unit 3 and a voltage output unit 4, one end of the buck unit is connected to the voltage input unit, the other end of the buck unit is connected to the boost unit through an inductor 04, and the other end of the boost unit is connected to the voltage output unit. The buck unit includes a first upper bridge arm switch tube 031 and a first lower bridge arm switch tube 032 connected in series, and the boost unit includes a second upper bridge arm switch tube 034 and a second lower bridge arm switch tube 033 connected in series. In an optional embodiment of the present application, the four-switch DC / DC power converter can realize a bidirectional flow of energy, and there are two working modes, including a battery discharge mode (i.e., BUCK (buck) mode) and a battery charging mode (i.e., BOOST (boost) mode). Wherein, when the four-switch DC / DC power converter operates in BOOST mode, the voltage input unit may include a first DC power supply 011 and a first filter capacitor 021, and the voltage output unit may include a second DC power supply 012 and a second filter capacitor 022; when the four-switch DC / DC power converter operates in BUCK mode, the voltage input unit may include a second DC power supply 012 and a second filter capacitor 022, and the voltage output unit may include a first DC power supply 011 and a first filter capacitor 021. The first filter capacitor 021 and the second filter capacitor 022 are respectively connected in parallel to the output end of the first DC power supply 011 and the output end of the second DC power supply 012 to reduce the AC ripple coefficient and smooth the DC output. In a circuit that converts AC into DC power supply, the filter capacitor not only stabilizes the DC output of the power supply and reduces the influence of the alternating ripple on the circuit, but also absorbs the current fluctuation generated during the operation of the circuit and the interference connected through the AC power supply, so that the working performance of the circuit is more stable.

[0048] Please continue to see Figure 1 ,like Figure 1 As shown, when the four-switch DC / DC power converter operates in the BUCK (step-down) mode, the voltage applied by the second DC power supply 012 as a voltage input unit to the buck unit and the boost unit is greater than the steady-state voltage of the first DC power supply 011 in the voltage output unit. At this time, the current of the inductor 04 flows from the right end of the inductor 04 to the left end of the inductor 04, and the inductor 04 is in an energy storage state. When the four-switch DC / DC power converter operates in the BOOST (step-up) mode, the voltage applied by the first DC power supply 011 as a voltage input unit to the buck unit and the boost unit is less than the steady-state voltage of the second DC power supply 012 in the voltage output unit. At this time, the current of the inductor 04 flows from the left end of the inductor 04 to the right end of the inductor 04, and the inductor 04 is in an energy release state.

[0049] In an optional embodiment of the present application, the first upper bridge arm switch tube 031, the first lower bridge arm switch tube 032 in the step-down unit, and the second upper bridge arm switch tube 034, the second lower bridge arm switch tube 033 in the boost unit can be an insulated gate bipolar transistor or a power field effect transistor. The insulated gate bipolar transistor (IGBT) has a high operating frequency, small required driving power, small switching loss and fast switching speed, which can enable the DC step-up and step-down circuit to quickly realize the conversion between step-down and step-up. The power field effect tube has a fast switching speed, a simple driving circuit and a high operating frequency. Among them, the first upper bridge arm switch tube 031 in the step-down unit and the second lower bridge arm switch tube 033 in the boost unit can be turned on and off respectively under the action of the pulse width modulation signal applied by the controller. Optionally, the controller can be a pulse width modulation (PWM) controller (or pulse width modulator), which modulates the base or gate bias of the semiconductor power switch device (such as an insulated bipolar transistor) according to the change of the corresponding load to achieve a change in the conduction time, thereby achieving a change in the duty cycle. The pulse width modulator is also a very effective controller that uses the digital signal of a microprocessor to control an analog circuit. For example, by controlling the on and off of a semiconductor power switch device (such as an insulated bipolar transistor), a series of pulses with equal amplitudes can be obtained at the output end, and these pulses are used to replace the sine wave or the required waveform. That is, multiple pulses are generated in half a cycle of the output waveform, so that the equivalent voltage of each pulse is a sine waveform, and the obtained output waveform is smooth and has few low-order harmonics. By modulating the width of each pulse according to a certain rule, the size of the circuit output voltage can be changed, and the output frequency can also be changed.

[0050] It can be understood that in an optional embodiment of the present application, the controller realizes the conduction and shutdown of the above-mentioned switch tubes respectively by applying pulse width modulation signals to the first upper bridge arm switch tube in the above-mentioned buck unit and the second lower bridge arm switch tube in the above-mentioned boost unit to control the duty cycle of the above-mentioned first upper bridge arm switch tube and the above-mentioned second lower bridge arm switch tube, thereby realizing seamless switching of the above-mentioned four-switch DC / DC power converter from BUCK (buck) mode to BOOST (boost) mode, thereby changing the flow direction of the inductor current, making the inductor repeatedly switch between the energy storage state and the energy release state, completing the bidirectional transmission of energy, and the output voltage remains in a steady state, which can achieve the voltage stabilization of the above-mentioned battery pack within a certain range and the repeated charging function of the battery pack in the above-mentioned electric vehicle.

[0051] The following will be combined Figure 2 The control method of the power converter provided in the present application is described. Figure 2 It is a waveform simulation diagram, such as Figure 2 As shown in the figure, from top to bottom are the output voltage waveform and the inductor current waveform. Among them, the above output voltage waveform is a fixed value. In practical applications, the above output voltage reference value can be set according to different situations, and the input voltage is controlled by the above Figure 1 The step-down unit 1 and the above Figure 1 The switching on or off of each bridge arm switch tube in the boost unit 2 in the boost unit 2 reaches the output voltage reference value, and keeps the output voltage of the DC power supply constant when the working conditions change. It can be seen from the above inductor current waveform that the above pulse width modulator Figure 1 The step-down unit 1 and the above Figure 1 Each bridge arm switch tube in the boost unit 2 sends a pulse width modulation signal to control the above-mentioned bridge arm switch tubes to be turned on or off, thereby realizing the function of repeatedly charging and discharging the inductor.

[0052] The following will be combined Figure 3-Figure 7 A control method for a power converter, a control device for a power converter, and a computer device of the present application are described.

[0053] See also Figure 3 , Figure 3 1 is a flow chart of a control method of a power converter provided by the present application. The control method of a power converter provided by the embodiment of the present application is applicable to a four-switch DC / DC power converter, wherein the structure of the above four-switch DC / DC power converter can be found in Figure 1 The structural diagram is not described in detail here. A control method of a power converter provided in an embodiment of the present application may include the following steps:

[0054] S101, determining a target duty cycle of the second upper bridge arm switch tube.

[0055] In some feasible implementations, when the input voltage of the voltage input unit is greater than the output voltage of the voltage output unit, the four-switch DC / DC power converter operates in BUCK (step-down) mode; when the four-switch DC / DC power converter operates in BUCK (step-down) mode, the target duty cycle of the second upper bridge arm is determined. The target duty cycle is the upper limit of the duty cycle of the first upper bridge arm switch tube adjusted by the subsequent pulse width modulator.

[0056] Specifically, in an optional embodiment of the present application, when the above-mentioned four-switch DC / DC power converter operates in BUCK (step-down) mode, the target duty cycle of the second upper bridge arm switch tube in the above-mentioned boost unit can be set to a certain threshold (for example, 0.99), and 0.99 can be set as the conduction duration of the first upper bridge arm switch tube in the above-mentioned buck unit controlled by the subsequent pulse width modulator to adjust the upper limit of the duty cycle of the above-mentioned first upper bridge arm switch tube.

[0057] S102, controlling the on-time of the first upper bridge arm according to the target duty cycle to adjust the duty cycle of the first upper bridge arm.

[0058] In some feasible implementations, when the input voltage of the voltage input unit is greater than the output voltage of the voltage output unit, the four-switch power converter operates in BUCK mode, and the controller determines the adjustment range of the duty cycle of the first upper bridge arm switch tube according to the target duty cycle. The adjustment range of the duty cycle of the first upper bridge arm switch tube is greater than 0 and less than or equal to the target duty cycle of the second upper bridge arm switch tube. Within the adjustment range of the duty cycle of the first upper bridge arm switch tube, the conduction time of the first upper bridge arm switch tube is controlled to adjust the duty cycle of the first upper bridge arm switch tube.

[0059] Specifically, in an optional embodiment of the present application, when the above-mentioned four-switch DC / DC power converter operates in the BUCK (step-down) mode, the pulse width modulator determines the duty cycle range of the above-mentioned first upper bridge arm switch tube to be greater than 0 and less than or equal to 0.99 according to the above-mentioned target duty cycle. Optionally, the pulse width modulator sends a pulse width modulation signal to the above-mentioned first upper bridge arm switch tube to control the conduction time of the above-mentioned first upper bridge arm switch tube so as to adjust the duty cycle of the above-mentioned first upper bridge arm switch tube from 0 to 0.99. When the pulse width modulator controls the duty cycle of the above-mentioned first upper bridge arm switch tube to reach 0.99, the input voltage of the voltage input unit in the above-mentioned four-switch DC / DC power converter is equal to the output voltage of the above-mentioned voltage output unit. At this time, the pulse width modulator stops controlling the above-mentioned first upper bridge arm switch tube, the BUCK (step-down) mode ends, and the above-mentioned four-switch DC / DC power converter also realizes the conversion of the working mode and converts to the BOOST (boost) mode.

[0060] S103, fixing the duty cycle of the first upper bridge arm switch tube.

[0061] In some feasible implementations, when the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit, the controller fixes the duty cycle of the first upper bridge arm switch tube at a duty cycle adjusted according to the duty cycle of the second upper bridge arm switch tube. At this time, the BUCK (step-down) mode ends, and the four-switch DC / DC power converter enters the BOOST (boost) mode.

[0062] Specifically, in an optional embodiment of the present application, when the four-switch DC / DC power converter operates in the BUCK (step-down) mode, the pulse width modulator controls the conduction time of the first upper bridge arm switch tube to adjust the duty cycle of the first upper bridge arm switch tube to 0.99. And when the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit, the duty cycle of the first upper bridge arm switch tube is fixed at 0.99, and the control of the first upper bridge arm switch tube is stopped, and the BUCK (step-down) mode ends.

[0063] S104, controlling the conduction time of the second lower bridge arm switch tube until the input voltage is less than the output voltage and the output voltage no longer increases.

[0064] In some feasible implementations, when the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit, the four-switch DC / DC power converter enters the BOOST mode, and at this time, the duty cycle of the second lower bridge arm switch tube is determined according to the loop output duty cycle and duty cycle coefficient of the four-switch DC / DC power converter. Wherein, when the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit, the duty cycle coefficient is the difference between the duty cycle of the first upper bridge arm switch tube and the duty cycle of the first lower bridge arm switch tube, the loop output duty cycle is equal to the duty cycle of the first upper bridge arm switch tube, and the conduction time of the second lower bridge arm switch tube is controlled according to the duty cycle of the second lower bridge arm switch tube until the input voltage is less than the output voltage and the output voltage no longer increases. When the above-mentioned four-switch power DC / DC converter operates in BOOST mode, the controller controls the duty cycle adjustment range of the above-mentioned second lower bridge arm switch tube to be less than the sum of the above-mentioned target duty cycle and the above-mentioned duty cycle coefficient, and greater than or equal to the above-mentioned target duty cycle.

[0065] Specifically, in an optional embodiment of the present application, when the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit, the four-switch DC / DC power converter enters the BOOST mode, at which time the pulse width modulator begins to adjust the duty cycle of the second lower bridge arm switch tube. The duty cycle of the second lower bridge arm switch tube is determined by the loop output duty cycle and the duty cycle coefficient. The loop output duty cycle here is the fixed duty cycle of 0.99 of the first upper bridge arm switch tube when the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit. The duty cycle coefficient is the difference between the duty cycle of the first upper bridge arm switch tube and the duty cycle of the first lower bridge arm switch tube when the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit. Among them, the duty cycle of the above-mentioned first upper bridge arm switch tube is complementary to the duty cycle of the above-mentioned first lower bridge arm switch tube. Therefore, when the duty cycle of the above-mentioned first upper bridge arm switch tube is 0.99, the duty cycle of the above-mentioned first lower bridge arm switch tube is 0.01. It can be understood that the duty cycle coefficient here is 0.98. In an optional embodiment of the present application, when the input voltage of the voltage input unit is equal to the output voltage of the above-mentioned voltage output unit, the duty cycle of the above-mentioned second lower bridge arm switch tube is 0.01, which is the difference between the loop output 0.99 of the above-mentioned four-switch DC / DC power converter and the above-mentioned duty cycle coefficient 0.98. The above-mentioned pulse width modulator sends a pulse width modulation signal to the above-mentioned second lower bridge arm switch tube according to the duty cycle of the above-mentioned second lower bridge arm switch tube to control the conduction time of the above-mentioned second lower bridge arm switch tube until the above-mentioned input voltage is less than the above-mentioned output voltage and the above-mentioned output voltage no longer increases. When the pulse width modulator controls the duty cycle of the second lower bridge arm switch tube to gradually increase from 0.01, and the conduction time of the second lower bridge arm switch tube gradually increases, the output voltage of the voltage output unit also gradually increases. The four-switch DC / DC power converter enters the BOOST mode until the pulse width modulator reaches the upper limit of the adjustment range when working in the BOOST mode, and the pulse width modulator stops controlling the second lower bridge arm switch tube. At this time, the output voltage of the voltage output unit reaches the maximum value and no longer increases. In an optional embodiment of the present application, when the pulse width modulator works in the BOOST mode, the duty cycle adjustment range of the second lower bridge arm switch tube is greater than or equal to 0.99 and less than 1.97.

[0066] In the present application, when the input voltage of the voltage input unit is greater than the output voltage of the voltage output unit, the target duty cycle of the second upper bridge arm switch tube is determined, and the conduction time of the first upper bridge arm switch tube is controlled according to the target duty cycle to adjust the duty cycle of the first upper bridge arm switch tube. When the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit, the duty cycle of the first upper bridge arm switch tube is fixed, and the duty cycle of the second lower bridge arm switch tube is determined according to the loop output duty cycle coefficient of the power converter, wherein the duty cycle coefficient is the difference between the duty cycle of the first upper bridge arm switch tube and the duty cycle of the first lower bridge arm switch tube, the loop output duty cycle is equal to the duty cycle of the first upper bridge arm switch tube, and the conduction time of the second lower bridge arm is controlled according to the duty cycle of the second lower bridge arm switch tube until the input voltage is less than the output voltage and the output voltage no longer increases, thereby realizing the function of boosting. This control strategy only has BUCK (step-down) mode and BOOST (step-up) mode, but no BUCK-BOOST (step-down-step-up) mode. By sending pulse width modulation signals to the first upper bridge arm switch tube and the second lower bridge arm switch tube by the controller, seamless switching of the working mode of the four-switch DC / DC converter is quickly achieved. The implementation is simple, the switching loss is reduced, and the efficiency of energy transmission is improved.

[0067] See also Figure 4 , Figure 4 FIG. 1 is another flow chart of a control method for a power converter provided by the present application. The method can be executed by a computer device. Figure 4 The method shown may include the following steps:

[0068] S201, determining a target duty cycle of the second upper bridge arm switch tube.

[0069] The specific implementation of step S201 can be found in the above Figure 3 The description of step S101 in the corresponding embodiment will not be repeated here.

[0070] S202: Control the on-time of the first upper bridge arm according to the target duty cycle to adjust the duty cycle of the first upper bridge arm.

[0071] The specific implementation of step S202 can be found in the above Figure 3 The description of step S102 in the corresponding embodiment will not be repeated here.

[0072] S203, fixing the duty cycle of the first upper bridge arm switch tube.

[0073] The specific implementation of step S203 can be found in the above Figure 3 The description of step S103 in the corresponding embodiment will not be repeated here.

[0074] S204, controlling the conduction time of the second lower bridge arm switch tube until the input voltage is less than the output voltage and the output voltage no longer increases.

[0075] The specific implementation of step S204 can be found in the above Figure 3 The description of step S104 in the corresponding embodiment will not be repeated here.

[0076] S205 , determining a voltage gain of the output voltage according to the duty cycle of the first upper bridge arm switch tube and the duty cycle of the second upper bridge arm switch tube.

[0077] It can be understood that the voltage gain of the output voltage is the voltage of the output voltage unit divided by the voltage of the input voltage unit, and the first bridge arm voltage is the duty cycle of the first upper bridge arm switch tube multiplied by the voltage of the input voltage unit; the second bridge arm voltage is the duty cycle of the second upper bridge arm switch tube multiplied by the voltage of the output voltage unit. In summary, the voltage gain of the output voltage is the duty cycle of the first upper bridge arm switch tube divided by the duty cycle of the second upper bridge arm switch tube. Therefore, when the voltage of the above-mentioned input voltage unit is greater than the voltage of the above-mentioned output voltage unit, the duty cycle of the above-mentioned first upper bridge arm switch tube and the duty cycle of the above-mentioned second upper bridge arm switch tube are adjusted so that the voltage gain of the above-mentioned output voltage is less than 1 and greater than 0; when the voltage of the above-mentioned input voltage unit is equal to the voltage of the above-mentioned output voltage unit, the duty cycle of the above-mentioned first upper bridge arm switch tube and the duty cycle of the above-mentioned second upper bridge arm switch tube are adjusted so that the voltage gain of the above-mentioned output voltage is equal to 1; when the voltage of the above-mentioned input voltage unit is less than the voltage of the above-mentioned output voltage unit, the duty cycle of the above-mentioned first upper bridge arm switch tube and the duty cycle of the above-mentioned second upper bridge arm switch tube are adjusted so that the voltage gain of the output voltage is greater than 1.

[0078] For further information, see Figure 5 , Figure 5 1 is a schematic diagram of a structure of a control device of a power converter provided by the present application. The control device of the power converter may be a computer program (including program code) running in a computer device. For example, the control device of the power converter is an application software. The control device of the power converter may be used to execute the corresponding steps of the method provided by the present application. Figure 5As shown, the power converter includes: a buck unit, a boost unit, a voltage input unit and a voltage output unit, one end of the buck unit is connected to the voltage input unit, the other end of the buck unit is connected to the boost unit through an inductor, and the other end of the boost unit is connected to the voltage output unit, the buck unit includes a first upper bridge arm switch tube and a first lower bridge arm switch tube connected in series, the boost unit includes a second upper bridge arm switch tube and a second lower bridge arm switch tube connected in series, and the control device includes: a first determination module 10, a first control module 20, a fixing module 30, and a second control module 40.

[0079] A first determination module 10, configured to determine a target duty cycle of the second upper bridge arm switch tube when the input voltage of the voltage input unit is greater than the output voltage of the voltage output unit;

[0080] A first control module 20, configured to control the on-time of the first upper bridge arm switch tube according to the target duty cycle determined by the first determination module 10 to adjust the duty cycle of the first upper bridge arm switch tube, wherein the duty cycle of the first lower bridge arm switch tube is complementary to the duty cycle of the first upper bridge arm switch tube, and the duty cycle of the second lower bridge arm switch tube is complementary to the duty cycle of the second upper bridge arm switch tube;

[0081] A fixing module 30, used for fixing the duty cycle of the first upper bridge arm switch tube when the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit;

[0082] The second control module 40 is used to control the conduction time of the second lower bridge arm switch tube until the input voltage is less than the output voltage and the output voltage no longer increases.

[0083] In a possible implementation manner, the first control module 10 is further configured to:

[0084] Determine the adjustment range of the duty cycle of the first upper bridge arm switch tube according to the target duty cycle, wherein the adjustment range of the duty cycle of the first upper bridge arm switch tube is greater than 0 and less than or equal to the duty cycle of the second upper bridge arm switch tube;

[0085] The on-time of the first upper bridge arm switch tube is controlled according to the adjustment range of the duty cycle of the first upper bridge arm switch tube to adjust the duty cycle of the first upper bridge arm switch tube.

[0086] In a possible implementation manner, the fixing module 30 is used for:

[0087] The duty cycle of the first upper bridge arm switch tube is fixed according to the target duty cycle, wherein the duty cycle of the first upper bridge arm switch tube is the same as the target duty cycle.

[0088] In a possible implementation manner, the second control module 40 is further configured to:

[0089] Determining the duty cycle of the second lower bridge arm switch tube according to the loop output duty cycle and the duty cycle coefficient of the power converter, wherein when the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit, the duty cycle coefficient is the difference between the duty cycle of the first upper bridge arm switch tube and the duty cycle of the first lower bridge arm switch tube, and the loop output duty cycle is equal to the duty cycle of the first upper bridge arm switch tube;

[0090] The conduction time length of the second lower bridge arm switch tube is controlled according to the duty cycle of the second lower bridge arm switch tube.

[0091] In a possible implementation manner, the duty cycle of the second lower bridge arm switch tube is less than the sum of the target duty cycle and the duty cycle coefficient, and is greater than or equal to the target duty cycle.

[0092] In a possible implementation, please refer to Figure 6 , the above-mentioned device also includes:

[0093] The second determination module 50 is used to determine the voltage gain of the output voltage according to the duty cycle of the first upper bridge arm switch tube and the duty cycle of the second upper bridge arm switch tube.

[0094] The specific implementation of the first determination module 10, the first control module 20, the fixing module 30, the second control module 40, and the second determination module 50 can be referred to above. Figure 3 The description of steps S101 to S104 in the corresponding embodiment, and / or the above Figure 4 The description of steps S201 to S205 in the corresponding embodiment will not be repeated here. In addition, the description of the beneficial effects of the same method will not be repeated here either.

[0095] For further information, see Figure 7 , Figure 7 Schematic diagram of a computer device provided by this application. Figure 7As shown, the computer device 1000 may include: at least one processor 1001, such as a CPU, at least one network interface 1003, a memory 1004, and at least one communication bus 1002. The communication bus 1002 is used to realize the connection and communication between these components. The network interface 1003 may optionally include a standard wired interface, a wireless interface (such as a WI-FI interface). The memory 1004 may be a high-speed random access memory (RAM) memory, or a non-volatile memory (non-volatile memory), such as at least one disk storage. The memory 1004 may optionally also be at least one storage device located away from the aforementioned processor 1001. As shown in FIG. Figure 6 As shown, the memory 1004 as a computer storage medium may include an operating system, a network communication module, and a device control application.

[0096] exist Figure 7 In the computer device 1000 shown, the processor 1001 can be used to call the device control application stored in the memory 1004 to implement:

[0097] When the input voltage of the voltage input unit is greater than the output voltage of the voltage output unit, a target duty cycle of the second upper bridge arm switch tube is determined, and the conduction time of the first upper bridge arm switch tube is controlled according to the target duty cycle to adjust the duty cycle of the first upper bridge arm switch tube, wherein the duty cycle of the first lower bridge arm switch tube is complementary to the duty cycle of the first upper bridge arm switch tube, and the duty cycle of the second lower bridge arm switch tube is complementary to the duty cycle of the second upper bridge arm switch tube;

[0098] When the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit, the duty cycle of the first upper bridge arm switch tube is fixed, and the conduction time of the second lower bridge arm switch tube is controlled until the input voltage is less than the output voltage and the output voltage no longer increases.

[0099] In a possible implementation manner, controlling the on-time of the first upper bridge arm switch tube according to the target duty cycle to adjust the duty cycle of the first upper bridge arm switch tube includes:

[0100] Determine an adjustment range of the duty cycle of the first upper bridge arm switch tube according to the target duty cycle, wherein the adjustment range of the duty cycle of the first upper bridge arm switch tube is greater than 0 and less than or equal to the duty cycle of the second upper bridge arm switch tube;

[0101] The on-time of the first upper bridge arm switch tube is controlled according to the adjustment range of the duty cycle of the first upper bridge arm switch tube to adjust the duty cycle of the first upper bridge arm switch tube.

[0102] In a possible implementation manner, fixing the duty cycle of the first upper bridge arm switch tube includes:

[0103] The duty cycle of the first upper bridge arm switch tube is fixed according to the target duty cycle, wherein the duty cycle of the first upper bridge arm switch tube is the same as the target duty cycle.

[0104] In a possible implementation manner, the controlling the conduction time of the second lower bridge arm switch tube includes:

[0105] Determining the duty cycle of the second lower bridge arm switch tube according to the loop output duty cycle and the duty cycle coefficient of the power converter, wherein when the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit, the duty cycle coefficient is the difference between the duty cycle of the first upper bridge arm switch tube and the duty cycle of the first lower bridge arm switch tube, and the loop output duty cycle is equal to the duty cycle of the first upper bridge arm switch tube;

[0106] The conduction time length of the second lower bridge arm switch tube is controlled according to the duty cycle of the second lower bridge arm switch tube.

[0107] In a possible implementation manner, the duty cycle of the second lower bridge arm switch tube is less than the sum of the target duty cycle and the duty cycle coefficient, and is greater than or equal to the target duty cycle.

[0108] In a possible implementation, the above method further includes:

[0109] The voltage gain of the output voltage is determined according to the duty cycle of the first upper bridge arm switch tube and the duty cycle of the second upper bridge arm switch tube.

[0110] In addition, it should be pointed out here that: the present application also provides a computer-readable storage medium, and the computer-readable storage medium stores a computer program executed by the control device of the power converter mentioned above, and the computer program includes program instructions. When the processor executes the program instructions, it can execute the above Figure 3 and / or Figure 4 The description of the control method of the power converter in the corresponding embodiment, therefore, will not be repeated here. In addition, the description of the beneficial effects of adopting the same method will not be repeated. For technical details not disclosed in the computer-readable storage medium embodiment involved in this application, please refer to the description of the method embodiment of this application. As an example, the program instructions can be deployed to execute on a computing device, or execute on multiple computing devices located in one place.

[0111] A person of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a computer program. The above-mentioned program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, the above-mentioned computer-readable storage medium can be a control device of a power converter provided by any of the above-mentioned embodiments or an internal storage unit of the above-mentioned device, such as a hard disk or memory of an electronic device. The computer-readable storage medium can also be an external storage device of the electronic device, such as a plug-in hard disk, a smart memory card (smart media card, SMC), a secure digital (secure digital, SD) card, a flash card (flash card), etc. equipped on the electronic device. The above-mentioned computer-readable storage medium can also include a magnetic disk, an optical disk, a read-only memory (ROM) or a random access memory, etc. Further, the computer-readable storage medium can also include both the internal storage unit of the electronic device and an external storage device. The computer-readable storage medium is used to store the computer program and other programs and data required by the electronic device. The computer-readable storage medium can also be used to temporarily store data that has been output or is to be output.

[0112] The terms "first", "second", etc. in the claims, specification and drawings of the present invention are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. Mentioning "embodiment" in this article means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present invention. Displaying the phrase at various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. The term "and / or" used in the specification and the appended claims of the present invention refers to any combination of one or more of the items listed in association and all possible combinations, and includes these combinations.

[0113] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Professional and technical personnel may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0114] In the embodiments provided in the present application, the disclosed circuits and methods can also be implemented in other ways. For example, the device embodiments described above are schematic, for example, the division of circuit modules is only a logical function division, and there may be other division methods in actual implementation, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed.

[0115] Each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0116] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A control method for a power converter, the power converter comprising: A buck unit, a boost unit, a voltage input unit and a voltage output unit, wherein one end of the buck unit is connected to the voltage input unit, the other end of the buck unit is connected to the boost unit through an inductor, and the other end of the boost unit is connected to the voltage output unit, the buck unit comprises a first upper bridge arm switch tube and a first lower bridge arm switch tube connected in series, and the boost unit comprises a second upper bridge arm switch tube and a second lower bridge arm switch tube connected in series, characterized in that the method comprises: When the input voltage of the voltage input unit is greater than the output voltage of the voltage output unit, a target duty cycle of the second upper bridge arm switch tube is determined, and the conduction time of the first upper bridge arm switch tube is controlled according to the target duty cycle to adjust the duty cycle of the first upper bridge arm switch tube, wherein the duty cycle of the first lower bridge arm switch tube is complementary to the duty cycle of the first upper bridge arm switch tube, and the duty cycle of the second lower bridge arm switch tube is complementary to the duty cycle of the second upper bridge arm switch tube; When the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit, the duty cycle of the first upper bridge arm switch tube is fixed, and the conduction time of the second lower bridge arm switch tube is controlled until the input voltage is less than the output voltage and the output voltage no longer increases.

2. The method according to claim 1, characterized in that The controlling the on-time of the first upper bridge arm switch tube according to the target duty cycle to adjust the duty cycle of the first upper bridge arm switch tube includes: Determining an adjustment range of the duty cycle of the first upper bridge arm switch tube according to the target duty cycle, wherein the adjustment range of the duty cycle of the first upper bridge arm switch tube is greater than 0 and less than or equal to the duty cycle of the second upper bridge arm switch tube; The on-time of the first upper bridge arm switch tube is controlled according to the adjustment range of the duty cycle of the first upper bridge arm switch tube to adjust the duty cycle of the first upper bridge arm switch tube.

3. The method according to claim 1, characterized in that The fixing of the duty cycle of the first upper bridge arm switch tube comprises: The duty cycle of the first upper bridge arm switch tube is fixed according to the target duty cycle, wherein the duty cycle of the first upper bridge arm switch tube is the same as the target duty cycle.

4. The method according to claim 1 or 3, characterized in that: The controlling the conduction time of the second lower bridge arm switch tube includes: Determining the duty cycle of the second lower bridge arm switch tube according to the loop output duty cycle and the duty cycle coefficient of the power converter, wherein when the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit, the duty cycle coefficient is the difference between the duty cycle of the first upper bridge arm switch tube and the duty cycle of the first lower bridge arm switch tube, and the loop output duty cycle is equal to the duty cycle of the first upper bridge arm switch tube; The conduction time length of the second lower bridge arm switch tube is controlled according to the duty cycle of the second lower bridge arm switch tube.

5. The method according to claim 4, characterized in that The duty cycle of the second lower bridge arm switch tube is less than the sum of the target duty cycle and the duty cycle coefficient, and is greater than or equal to the target duty cycle.

6. The method according to claim 2 or 5, characterized in that: The method further comprises: The voltage gain of the output voltage is determined according to the duty cycle of the first upper bridge arm switch tube and the duty cycle of the second upper bridge arm switch tube.

7. A control device for a power converter, characterized in that: The power converter includes: a buck unit, a boost unit, a voltage input unit and a voltage output unit, one end of the buck unit is connected to the voltage input unit, the other end of the buck unit is connected to the boost unit through an inductor, and the other end of the boost unit is connected to the voltage output unit, the buck unit includes a first upper bridge arm switch tube and a first lower bridge arm switch tube connected in series, the boost unit includes a second upper bridge arm switch tube and a second lower bridge arm switch tube connected in series, and the device includes: A first determining module, configured to determine a target duty cycle of the second upper bridge arm switch tube when the input voltage of the voltage input unit is greater than the output voltage of the voltage output unit; A first control module, configured to control the on-time of the first upper bridge arm switch tube according to the target duty cycle to adjust the duty cycle of the first upper bridge arm switch tube, wherein the duty cycle of the first lower bridge arm switch tube is complementary to the duty cycle of the first upper bridge arm switch tube, and the duty cycle of the second lower bridge arm switch tube is complementary to the duty cycle of the second upper bridge arm switch tube; A fixing module, used for fixing the duty cycle of the first upper bridge arm switch tube when the input voltage of the voltage input unit is equal to the output voltage of the voltage output unit; The second control module is used to control the conduction time of the second lower bridge arm switch tube until the input voltage is less than the output voltage and the output voltage no longer increases.

8. The device according to claim 7, characterized in that The first control module is used for: Determining an adjustment range of the duty cycle of the first upper bridge arm switch tube according to the target duty cycle, wherein the adjustment range of the duty cycle of the first upper bridge arm switch tube is greater than 0 and less than or equal to the duty cycle of the second upper bridge arm switch tube; The on-time of the first upper bridge arm switch tube is controlled according to the adjustment range of the duty cycle of the first upper bridge arm switch tube to adjust the duty cycle of the first upper bridge arm switch tube.

9. A computer device, characterized in that: include: Processor, memory, and network interface; The processor is connected to a memory and a network interface, wherein the network interface is used to provide a data communication function, the memory is used to store program codes, and the processor is used to call the program codes to execute the method described in any one of claims 1-6.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, wherein the computer program includes program instructions. When the program instructions are executed by a processor, the method according to any one of claims 1 to 6 is executed.

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