Voltage converter and method, device and voltage conversion apparatus for controlling the same

Abstract

The application relates to a voltage converter and a control method and device thereof and a voltage conversion device, which comprises a first capacitor, a second capacitor, a first inductor, a second inductor, a first switch tube, a second switch tube, a third switch tube and a fourth switch tube, the first end of the first capacitor is connected with the first end of the first switch tube, the first end of the first inductor and the first end of the third switch tube are both connected with the second end of the first switch tube, the first end of the fourth switch tube and the second end of the second switch tube are both connected with the second end of the first inductor, the second end of the third switch tube is connected with the second end of the second inductor, the second end of the fourth switch tube is connected with the first end of the second inductor, the first end of the second switch tube is connected with the first end of the second capacitor, and the second end of the second capacitor is connected with the second end of the second inductor. The voltage converter has simple structure and symmetry, can realize high-output-gain step-up conversion and low-output-gain step-down conversion, has good working performance and is reliable in use.

Description

Technical Field

[0001] This application relates to the field of voltage transformation technology, and in particular to a voltage converter and its control method, apparatus and voltage transformation equipment. Background Technology

[0002] Voltage converters have wide applications in many industrial settings, such as new energy power generation, electric vehicles, and DC power distribution networks. There are many types of voltage converters; for example, the DC-DC converter can transform the input voltage and effectively output a fixed voltage.

[0003] Traditional DC-DC converters include isolated and non-isolated types. Isolated DC-DC converters can effectively extend the step-up / step-down ratio by adjusting the transformer turns ratio, but the added transformer inevitably increases the converter size, reduces power density, and the transformer's leakage inductance may introduce larger peak voltages to the switching transistors. For traditional non-isolated DC-DC converters, the duty cycle of the switching transistors is limited in practical applications, thus restricting the output voltage gain range. Therefore, traditional DC-DC converters have poor performance and are unreliable in use. Summary of the Invention

[0004] Therefore, it is necessary to provide a voltage converter and its control method, device, and voltage conversion equipment to address the problems of poor performance and unreliability of traditional DC-DC converters.

[0005] A voltage converter includes a first capacitor, a second capacitor, a first inductor, a second inductor, a first switching transistor, a second switching transistor, a third switching transistor, and a fourth switching transistor. A first terminal of the first capacitor is connected to a first terminal of the first switching transistor. The first terminals of the first inductor and the third switching transistor are both connected to the second terminals of the first switching transistor. The first terminal of the fourth switching transistor and the second terminal of the second switching transistor are both connected to the second terminals of the first inductor. The second terminal of the third switching transistor is connected to the second terminal of the second inductor. The second terminal of the fourth switching transistor is connected to the first terminal of the second inductor. The first terminal of the second switching transistor is connected to the first terminal of the second capacitor. The second terminal of the second capacitor is connected to the second terminal of the second inductor.

[0006] A control method for a voltage converter, based on the aforementioned voltage converter, includes the following steps:

[0007] When a step-down command is received, the second switch is kept on and the first and third switches are controlled to perform complementary switching actions. The conduction state of the fourth switch is matched with the conduction state of the third switch.

[0008] When a boost command is received, the first switch is kept on and the second and third switches are controlled to perform complementary switching actions. The conduction state of the fourth switch is matched with the conduction state of the third switch.

[0009] A control device for a voltage converter, comprising:

[0010] The step-down control module is used to control the second switch to be constantly on when a step-down command is received, and to control the first switch and the third switch to perform complementary switching actions, wherein the conduction state of the fourth switch matches the conduction state of the third switch.

[0011] The boost control module is used to control the first switch to be constantly on when a boost command is received, and to control the second and third switches to perform complementary switching actions, wherein the conduction state of the fourth switch is matched with the conduction state of the third switch.

[0012] A voltage conversion device includes a voltage converter as described above, and a control device for the voltage converter as described above.

[0013] The aforementioned voltage converter and its control method, device, and equipment include a first capacitor, a second capacitor, a first inductor, a second inductor, a first switching transistor, a second switching transistor, a third switching transistor, and a fourth switching transistor. The first terminal of the first capacitor is connected to the first terminal of the first switching transistor. The first terminals of the first inductor and the third switching transistor are both connected to the second terminals of the first switching transistor. The first terminals of the fourth switching transistor and the second terminals of the second switching transistor are both connected to the second terminals of the first inductor. The second terminal of the third switching transistor is connected to the second terminal of the second inductor. The second terminal of the fourth switching transistor is connected to the first terminal of the second inductor. The first terminal of the second switching transistor is connected to the first terminal of the second capacitor, and the second terminal of the second capacitor is connected to the second terminal of the second inductor. This voltage converter has a simple and symmetrical structure. By changing the conduction states of the first, second, third, and fourth switching transistors, the voltage converter can operate in boost mode or buck mode, achieving bidirectional operation. Furthermore, it can achieve high-output-gain boost conversion and low-output-gain buck conversion, exhibiting excellent performance and reliable operation.

[0014] In one embodiment, the voltage converter further includes a controller, wherein the control terminals of the first switch, the second switch, the third switch, and the fourth switch are all connected to the controller.

[0015] In one embodiment, the controller is configured to, upon receiving a buck command, control the second switch to remain on, and control the first and third switches to perform complementary switching actions, and control the conduction state of the fourth switch to match the conduction state of the third switch; and is further configured to, upon receiving a boost command, control the first switch to remain on, and control the second and third switches to perform complementary switching actions, and control the conduction state of the fourth switch to match the conduction state of the third switch.

[0016] In one embodiment, the third switch and the fourth switch operate synchronously.

[0017] In one embodiment, the inductance of the first inductor and the second inductor are matched.

[0018] In one embodiment, the first switch, the second switch, the third switch, and the fourth switch are all MOSFETs.

[0019] In one embodiment, the first switch, the second switch, the third switch, and the fourth switch are all N-channel MOSFETs. Attached Figure Description

[0020] Figure 1 This is a structural diagram of a voltage converter in one embodiment;

[0021] Figure 2 The diagram shows the switching pulses of the four switching transistors of the voltage converter in buck mode in one embodiment.

[0022] Figure 3 This is an equivalent circuit diagram of the voltage converter in buck mode in one embodiment;

[0023] Figure 4 The equivalent circuit diagram of the voltage converter in buck mode in another embodiment is shown.

[0024] Figure 5 The diagram shows the switching pulses of the four switching transistors of the voltage converter in boost mode in one embodiment.

[0025] Figure 6 This is an equivalent circuit diagram of the voltage converter in boost mode in one embodiment;

[0026] Figure 7 The equivalent circuit diagram of the voltage converter in boost mode in another embodiment is shown.

[0027] Figure 8 This is a comparison of the boost gain and buck gain of a voltage converter and a conventional ground switching circuit in one embodiment.

[0028] Figure 9 This is a flowchart of a control method for a voltage converter in one embodiment. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the following description, in conjunction with embodiments and accompanying drawings, provides a more comprehensive overview of the application. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the application.

[0030] In one embodiment, a voltage converter is provided; see [link to relevant documentation]. Figure 1 It includes a first capacitor C1, a second capacitor C2, a first inductor L1, a second inductor L2, a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4. The first terminal of the first capacitor C1 is connected to the first terminal of the first switch S1. The first terminals of the first inductor L1 and the third switch S3 are both connected to the second terminal of the first switch S1. The first terminal of the fourth switch S4 and the second terminal of the second switch S2 are both connected to the second terminal of the first inductor L1. The second terminal of the third switch S3 is connected to the second terminal of the second inductor L2. The second terminal of the fourth switch S4 is connected to the first terminal of the second inductor L2. The first terminal of the second switch S2 is connected to the first terminal of the second capacitor C2. The second terminal of the second capacitor C2 is connected to the second terminal of the second inductor L2. This voltage converter has a simple and symmetrical structure. By changing the conduction state of the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4, the voltage converter can operate in either boost or buck mode, achieving bidirectional operation. Furthermore, it can achieve boost conversion with high output gain and buck conversion with low output gain, exhibiting excellent performance and reliable operation.

[0031] Specifically, the first inductor L1 and the second inductor L2 can store and release energy. The first capacitor C1, the second capacitor C2, and the first and second inductors L1 and L2 work together to enable the voltage converter to perform different functions when the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 are in different conduction states. When the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 are in the on or off state, the current path in the voltage converter is different, thereby achieving functions such as boosting or bucking. The first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 can be manual switches, allowing manual control of their opening and closing. Alternatively, the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 can also be electric switches, allowing different control signals to turn the first switch S1, the second switch S2, the third switch S3, or the fourth switch S4 on or off, resulting in a high degree of automation.

[0032] For example, when the second switch S2 is closed, the first switch S1, the third switch S3, and the fourth switch S4 perform complementary switching operations. That is, when the first switch S1 is closed, the third switch S3 and the fourth switch S4 are off, and when the first switch S1 is off, the third switch S3 and the fourth switch S4 are closed. For the switching pulses of the four switches, please refer to [link to relevant documentation]. Figure 2 At this time, the voltage converter operates in buck mode. Please refer to the equivalent circuit diagram for details. Figure 3 and 4 .

[0033] Furthermore, when the first switch S1 is closed, the second switch S2, the third switch S3, and the fourth switch S4 perform complementary switching operations. That is, when the second switch S2 is closed, the third switch S3 and the fourth switch S4 are off, and when the second switch S2 is off, the third switch S3 and the fourth switch S4 are closed. For the switching pulses of the four switches, please refer to [link to relevant documentation]. Figure 5 At this time, the voltage converter operates in boost mode. Please refer to the equivalent circuit diagram for details. Figure 6 and 7 .

[0034] In one embodiment, the voltage converter further includes a controller. The control terminals of the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 are all connected to the controller. The controller can send different control signals to the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 through the control terminals of the switches, thereby controlling the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 to be turned on or off, realizing the control of the voltage converter's operation with a high degree of automation. The type of control signal is not unique; for example, it can be a PWM (Pulse Width Modulation) signal. PWM includes high and low levels. The first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 are in an on or off state when receiving different level signals, thereby realizing convenient adjustment and control of the voltage converter's operating mode.

[0035] In one embodiment, the controller, upon receiving a step-down command, controls the second switch S2 to remain constantly on, controls the first switch S1 and the third switch S3 to perform complementary switching actions, and controls the conduction state of the fourth switch S4 to match the conduction state of the third switch S3. Specifically, "the second switch S2 remains constantly on" means that the second switch S2 is always in a conducting state; "controlling the first switch S1 and the third switch S3 to perform complementary switching actions" and "controlling the conduction state of the fourth switch S4 to match the conduction state of the third switch S3" can mean that the conduction state of the fourth switch S4 is the same as the conduction state of the third switch S3. That is, when the first switch S1 is closed, the third switch S3 and the fourth switch S4 are open; when the first switch S1 is open, the third switch S3 and the fourth switch S4 are closed. For the switching pulses of the four switches, please refer to [link to relevant documentation]. Figure 2 At this time, the voltage converter operates in buck mode. Please refer to the equivalent circuit diagram for details. Figure 3 and 4 .

[0036] The controller is also used to, upon receiving a boost command, control the first switch S1 to remain constantly on, control the second switch S2 and the third switch S3 to perform complementary switching actions, and control the conduction state of the fourth switch S4 to match the conduction state of the third switch S3. Specifically, "the first switch S1 remains constantly on" means that the first switch S1 is always in a conducting state; "controlling the second switch S2 and the third switch S3 to perform complementary switching actions" and "controlling the conduction state of the fourth switch S4 to match the conduction state of the third switch S3" mean that when the second switch S2 is closed, the third switch S3 and the fourth switch S4 are open, and when the second switch S2 is open, the third switch S3 and the fourth switch S4 are closed. For the switching pulses of the four switches, please refer to [link to relevant documentation]. Figure 5 At this time, the voltage converter operates in boost mode. Please refer to the equivalent circuit diagram for details. Figure 6 and 7 .

[0037] In one embodiment, the third switch S3 and the fourth switch S4 operate synchronously. Synchronous operation means that at the same time, or when the difference between two times is within an allowable error range, the conduction state of the third switch S3 is the same as that of the fourth switch S4; that is, when the third switch S3 is on, the fourth switch S4 is also on, and when the third switch S3 is off, the fourth switch S4 is also off. Further, synchronous operation can be achieved by sending the same type of level signal to the third switch S3 and the fourth switch S4. It is understood that in other embodiments, other methods can also be used to achieve synchronous operation of the third switch S3 and the fourth switch S4, as long as those skilled in the art deem it feasible.

[0038] In one embodiment, the inductance values ​​of the first inductor L1 and the second inductor L2 are matched. Specifically, matching the inductance values ​​of the first inductor L1 and the second inductor L2 can mean that the inductance values ​​of the first inductor L1 and the second inductor L2 are equal, or that the difference between the inductance values ​​of the first inductor L1 and the second inductor L2 is within an allowable error range. When the inductance values ​​of the first inductor L1 and the second inductor L2 are matched, after the two inductors are charged in parallel during the same time period, the currents of the two inductors are matched, which helps to improve the stability of the voltage converter operation.

[0039] Furthermore, when the inductances of the first inductor L1 and the second inductor L2 are matched, if the voltage converter operates in buck mode, see [reference needed]. Figure 2 It can be seen that during the [t0~t1] stage: the first switch S1 is turned on, the third switch S3 and the fourth switch S4 are turned off, and the first inductor L1 and the second inductor L2 are connected in series to store energy, as follows: Figure 3 As shown in the diagram, the dashed lines represent the current flow paths in the circuit. During this stage, the currents in the first inductor L1 and the second inductor L2 increase. The increase in current in each inductor is expressed as follows:

[0040]

[0041] in, This represents the increase in inductor current of the first inductor L1 from t0 to t1; This represents the increase in inductor current of the second inductor L2 from t0 to t1; V i V represents the input voltage of the voltage converter. o The voltage at the output terminal of the voltage converter is represented by L; L represents the inductance value of the first inductor L1 and the second inductor L2; d1 represents the value of the voltage in one switching cycle T. s The proportion of the conduction time of the switching transistor S1.

[0042] During the [t1~t2] stage: the first switch S1 is turned off, the third switch S3 and the fourth switch S4 are turned on, and the first inductor L1 and the second inductor L2 are connected in parallel to release energy, such as Figure 4 As shown. During this stage, the current in the first inductor L1 and the second inductor L2 decreases, and the amount of current decrease is expressed as:

[0043]

[0044] in, This represents the decrease in inductor current of the first inductor L1 from t1 to t2; This represents the decrease in inductor current of the second inductor L2 from t1 to t2; V o The voltage at the output terminal of the voltage converter is represented by L; L represents the inductance value of the first inductor L1 and the second inductor L2; d1 represents the value of the voltage in one switching cycle T. s The proportion of the conduction time of the first switching transistor S1.

[0045] When the switching circuit of the voltage converter is operating stably, the change in inductor current within one switching cycle eventually reaches zero, meaning the increase in current through the inductor and the decrease in current through the inductor are equal. Therefore, satisfying the volt-second balance ensures stable circuit operation. Applying the volt-second balance equation to the first inductor L1 and the second inductor L2 yields:

[0046]

[0047] Substituting equations (1) and (2) into equation (3), we get:

[0048]

[0049] Among them, V i V represents the input voltage of the voltage converter. o The voltage at the output terminal of the voltage converter is represented by L; L represents the inductance value of the first inductor L1 and the second inductor L2; d1 represents the value of the voltage in one switching cycle T. s The proportion of the conduction time of the first switching transistor S1.

[0050] From equation (4), we can obtain the voltage gain formula for the voltage converter in buck mode as follows:

[0051]

[0052] Among them, V i V represents the input voltage of the voltage converter. o The voltage at the output terminal of the voltage converter is represented by L; L represents the inductance value of the first inductor L1 and the second inductor L2; d1 represents the value of the voltage in one switching cycle T. s Within, the conduction time t of the first switch S1on1 The proportion. Equation (5) is the voltage formula of the voltage converter in buck mode. Since the range of d1 is 0 to 1, and d1 < (2-d1), the voltage gain G must be less than 1, that is, the output voltage is less than the input voltage, so the working mode of the voltage converter is buck.

[0053] When the voltage converter is operating in boost mode, see Figure 5 It can be seen that during the [t0~t1] stage: the third switch S3 and the fourth switch S4 are turned on, the second switch S2 is turned off, and the first inductor L1 and the second inductor L2 are connected in parallel to store energy, as follows: Figure 6 As shown. During this stage, the current in the first inductor L1 and the second inductor L2 increases, and the increase in current is expressed as:

[0054]

[0055] in, This represents the increase in inductor current of the first inductor L1 from t0 to t1; This represents the increase in inductor current of the second inductor L2 from t0 to t1; V i The input voltage of the voltage converter is represented by d2; L represents the inductance value of the first inductor L1 and the second inductor L2; d2 represents the value of the input voltage of the voltage converter in one switching cycle T. s The proportion of the conduction time of the second switch S2.

[0056] During the [t1~t2] phase: the third switch S3 and the fourth switch S4 are turned off, the second switch S2 is turned on, and the first inductor L1 and the second inductor L2 are connected in series to release energy, such as Figure 7 As shown. During this stage, the current in the first inductor L1 and the second inductor L2 decreases, and the amount of current decrease is expressed as:

[0057]

[0058] in, This represents the decrease in inductor current of the first inductor L1 from t1 to t2; This represents the decrease in inductor current of the second inductor L2 from t1 to t2; V i V represents the input voltage of the voltage converter. o The voltage at the output terminal of the voltage converter is represented by d2; L represents the inductance value of the first inductor L1 and the second inductor L2; d2 represents the voltage across the output terminal of the voltage converter in one switching cycle T. sThe switching frequency is the proportion of the conduction time of the second switching transistor S2. The switching frequency is determined by many factors, such as system performance requirements (dynamic, steady-state, harmonics, etc.), the loss characteristics of the switching device itself, the heat dissipation method (water cooling / air cooling), the operating environment, and the load conditions. Generally, the higher the frequency, the lower the current harmonics of the circuit, but the greater the switching losses. After weighing the switching losses and ripple magnitude (inductor size, volume), the frequency needs to be determined based on the actual situation and experience.

[0059] By applying the volt-second balance equations for the first inductor L1 and the second inductor L2, we can obtain:

[0060]

[0061] Substituting equations (6) and (7) into equation (8), we get:

[0062]

[0063] V i V represents the input voltage of the voltage converter. o The voltage at the output terminal of the voltage converter is represented by d2; L represents the inductance value of the first inductor L1 and the second inductor L2; d2 represents the voltage across the output terminal of the voltage converter in one switching cycle T. s The proportion of the conduction time of the second switch S2.

[0064] From equation (9), we can obtain the voltage gain formula for the voltage converter in boost mode:

[0065]

[0066] V i V represents the input voltage of the voltage converter. o d2 represents the output voltage of the voltage converter; d2 represents the voltage across the circuit in one switching cycle T. s The proportion of the conduction time of the second switch S2.

[0067] Table 1 compares the voltage gain of the voltage converter of this application with that of a conventional four-switch circuit. According to the definition of the duty cycle of a switching transistor, the duty cycle can vary within the range of 0 to 1. Therefore, the range of variation of the output voltage to input voltage ratio between this voltage converter and the conventional four-switch converter in boost and buck modes is as follows: Figure 8 As shown, in boost or buck mode, with the same duty cycle, the voltage converter proposed in this application has a larger boost gain and a smaller buck gain compared to the traditional four-switch circuit, enabling a wider range of voltage regulation.

[0068]

[0069] Table 1

[0070] In one embodiment, the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 are all MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors). MOSFETs offer numerous advantages, such as voltage control, convenient control methods, small size, light weight, long lifespan, high input resistance, low noise, good thermal stability, strong anti-interference capability, and low power consumption. It is understood that in other embodiments, the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 can be of other types, as long as those skilled in the art deem it feasible.

[0071] In one embodiment, the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 are all N-channel MOSFETs. Correspondingly, the connections of the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 with other devices are as follows: the two ends of the first capacitor C1 serve as the input terminal of the voltage converter, and the two ends of the second capacitor C2 serve as the output terminal of the voltage converter. The positive terminal of the input terminal is connected to the drain of the first switch S1, and the positive terminal of the output terminal is connected to the drain of the second switch S2. The first inductor L1, the second inductor L2, the third switch S3, and the fourth switch S4 constitute a switching voltage unit, and the inductance of the first inductor L1 and the second inductor L2 are the same. The drain of the third switch S3 is connected to the first terminal of the first inductor L1 and the source of the first switch S1, and the source of the third switch S3 is connected to the second terminal of the second inductor L2 and the negative terminal of the output terminal. The source of the fourth switch S4 is connected to the first terminal of the second inductor L2 and the negative terminal of the input. The drain of the fourth switch S4 is connected to one terminal of the first inductor L1 and the source of the second switch S2. The drain of the second switch S2 is connected to the positive terminal of the output. By inputting PWM pulses to the gates of the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4, the circuit mode can be changed and controlled.

[0072] To better understand the above embodiments, a detailed explanation is provided below with reference to a specific embodiment. In one embodiment, the voltage converter includes a first capacitor C1, a second capacitor C2, a first inductor L1, a second inductor L2, a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, and a controller. The first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 are all N-channel MOSFETs.

[0073] The input of this voltage converter is typically connected to a voltage source with unstable voltage that fluctuates within a certain range, while the output is connected to a battery. The specific circuit of the voltage converter includes an input terminal, an output terminal, switching transistors S1-S4, a first inductor L1, a second inductor L2, a first capacitor C1, and a second capacitor C2. The input terminal V... i The positive terminal is connected to the drain of the switching transistor S1, and the output terminal V o The positive terminal of the transistor is connected to the drain of the second switching transistor S2. The two inductors L1 and L2, along with the switching transistors S3 and S4, form a switching voltage unit, with the two inductors having the same value: L1 = L2 = L. The drain of switching transistor S3 is connected to one end of inductor L1 and the source of switching transistor S1. The source of switching transistor S3 is connected to one end of inductor L2 and the output terminal V. o The negative terminal is connected. The drain of the switching transistor S4 is connected to the other end of the inductor L1 and the output terminal V. o The positive terminal of the transistor S4 is connected to the source of the inductor L2 and the other end of the input terminal V. i The negative terminals are connected. The controller changes and controls the circuit mode by inputting PWM pulses to the gates of switching transistors S1 to S4. Switches S3 and S4 operate synchronously, and their on / off states are determined jointly by switching transistors S1 and S2. In one switching cycle T... s The conduction time t of switch S1 on1 The proportion is represented by the duty cycle d1, i.e., d1 = t on1 / T s Similarly, in a switching cycle T s The conduction time t of switch S2 on2 The proportion is represented by the duty cycle d2, i.e., d2 = t on2 / T s By combining the on / off states of these four switching transistors, the voltage converter can operate in both boost mode and boost mode.

[0074] When the converter operates in buck mode, switch S2 is always on, while switches S1, S3, and S4 perform complementary switching operations. The switching pulses of the four transistors are as follows: Figure 2 As shown, when the switching pulse is high, the corresponding switch is in the on state; when the switching pulse is low, the corresponding switch is in the off state. The corresponding converter equivalent circuit is as follows: Figure 3 and 4 As shown.

[0075] During the [t0~t1] stage: the first switch S1 is turned on, the third switch S3 and the fourth switch S4 are turned off, and the first inductor L1 and the second inductor L2 are connected in series to store energy, such as Figure 3As shown in the diagram, the dashed lines represent the current flow paths in the circuit. During this stage, the currents in the first inductor L1 and the second inductor L2 increase. The increase in current in each inductor is expressed as follows:

[0076]

[0077] in, This represents the increase in inductor current of the first inductor L1 from t0 to t1; This represents the increase in inductor current of the second inductor L2 from t0 to t1; V i V represents the input voltage of the voltage converter. o The voltage at the output terminal of the voltage converter is represented by L; L represents the inductance value of the first inductor L1 and the second inductor L2; d1 represents the value of the voltage in one switching cycle T. s The proportion of the conduction time of the switching transistor S1.

[0078] During the [t1~t2] stage: the first switch S1 is turned off, the third switch S3 and the fourth switch S4 are turned on, and the first inductor L1 and the second inductor L2 are connected in parallel to release energy, such as Figure 4 As shown. During this stage, the current in the first inductor L1 and the second inductor L2 decreases, and the amount of current decrease is expressed as:

[0079]

[0080] in, This represents the decrease in inductor current of the first inductor L1 from t1 to t2; This represents the decrease in inductor current of the second inductor L2 from t1 to t2; V o The voltage at the output terminal of the voltage converter is represented by L; L represents the inductance value of the first inductor L1 and the second inductor L2; d1 represents the value of the voltage in one switching cycle T. s The proportion of the conduction time of the first switching transistor S1.

[0081] When the switching circuit of the voltage converter is operating stably, the change in inductor current within one switching cycle eventually reaches zero, meaning the increase in current through the inductor and the decrease in current through the inductor are equal. Therefore, satisfying the volt-second balance ensures stable circuit operation. Applying the volt-second balance equation to the first inductor L1 and the second inductor L2 yields:

[0082]

[0083] Substituting equations (1) and (2) into equation (3), we get:

[0084]

[0085] Among them, V i V represents the input voltage of the voltage converter.o The voltage at the output terminal of the voltage converter is represented by L; L represents the inductance value of the first inductor L1 and the second inductor L2; d1 represents the value of the voltage in one switching cycle T. s The proportion of the conduction time of the first switching transistor S1.

[0086] From equation (4), we can obtain the voltage gain formula for the voltage converter in buck mode as follows:

[0087]

[0088] Among them, V i V represents the input voltage of the voltage converter. o The voltage at the output terminal of the voltage converter is represented by L; L represents the inductance value of the first inductor L1 and the second inductor L2; d1 represents the value of the voltage in one switching cycle T. s Within, the conduction time t of the first switch S1 on1 The proportion. Equation (5) is the voltage formula of the voltage converter in buck mode. Since the range of d1 is 0 to 1, and d1 < (2-d1), the voltage gain G must be less than 1, that is, the output voltage is less than the input voltage, so the working mode of the voltage converter is buck.

[0089] When the converter operates in boost mode, switch S1 is always on, while switches S2, S3, and S4 perform complementary switching operations. The switching pulses of the four transistors are as follows: Figure 5 As shown, the corresponding converter equivalent circuit is as follows: Figure 6 and 7 As shown.

[0090] During the [t0~t1] stage: the third switch S3 and the fourth switch S4 are turned on, the second switch S2 is turned off, and the first inductor L1 and the second inductor L2 are connected in parallel to store energy, such as Figure 6 As shown. During this stage, the current in the first inductor L1 and the second inductor L2 increases, and the increase in current is expressed as:

[0091]

[0092] in, This represents the increase in inductor current of the first inductor L1 from t0 to t1; This represents the increase in inductor current of the second inductor L2 from t0 to t1; V i The input voltage of the voltage converter is represented by d2; L represents the inductance value of the first inductor L1 and the second inductor L2; d2 represents the value of the input voltage of the voltage converter in one switching cycle T. s The proportion of the conduction time of the second switch S2.

[0093] During the [t1~t2] phase: the third switch S3 and the fourth switch S4 are turned off, the second switch S2 is turned on, and the first inductor L1 and the second inductor L2 are connected in series to release energy, such as Figure 7 As shown. During this stage, the current in the first inductor L1 and the second inductor L2 decreases, and the amount of current decrease is expressed as:

[0094]

[0095] in, This represents the decrease in inductor current of the first inductor L1 from t1 to t2; This represents the decrease in inductor current of the second inductor L2 from t1 to t2; V i V represents the input voltage of the voltage converter. o The voltage at the output terminal of the voltage converter is represented by d2; L represents the inductance value of the first inductor L1 and the second inductor L2; d2 represents the voltage across the output terminal of the voltage converter in one switching cycle T. s The switching frequency is the proportion of the conduction time of the second switching transistor S2. The switching frequency is determined by many factors, such as system performance requirements (dynamic, steady-state, harmonics, etc.), the loss characteristics of the switching device itself, the heat dissipation method (water cooling / air cooling), the operating environment, and the load conditions. Generally, the higher the frequency, the lower the current harmonics of the circuit, but the greater the switching losses. After weighing the switching losses and ripple magnitude (inductor size, volume), the frequency needs to be determined based on the actual situation and experience.

[0096] By applying the volt-second balance equations for the first inductor L1 and the second inductor L2, we can obtain:

[0097]

[0098] Substituting equations (6) and (7) into equation (8), we get:

[0099]

[0100] V i V represents the input voltage of the voltage converter. o The voltage at the output terminal of the voltage converter is represented by d2; L represents the inductance value of the first inductor L1 and the second inductor L2; d2 represents the voltage across the output terminal of the voltage converter in one switching cycle T. s The proportion of the conduction time of the second switch S2.

[0101] From equation (9), we can obtain the voltage gain formula for the voltage converter in boost mode:

[0102]

[0103] V i V represents the input voltage of the voltage converter. od2 represents the output voltage of the voltage converter; d2 represents the voltage across the circuit in one switching cycle T. s The proportion of the conduction time of the second switch S2.

[0104] Table 1 compares the voltage gain of the voltage converter of this application with that of a conventional four-switch circuit. According to the definition of the duty cycle of a switching transistor, the duty cycle can vary within the range of 0 to 1. Therefore, the range of variation of the output voltage to input voltage ratio between this voltage converter and the conventional four-switch converter in boost and buck modes is as follows: Figure 8 As shown, in both boost and buck modes, with the same duty cycle, the voltage converter proposed in this application has a higher boost gain and a lower buck gain compared to a traditional four-switch circuit, enabling a wider range of voltage regulation. This voltage converter is a non-isolated DC-DC converter with a wide boost / buck range. It has a symmetrical structure and can operate bidirectionally. Compared to a traditional four-switch converter, this converter can achieve higher boost gain and lower buck gain with the same duty cycle in both boost and buck modes.

[0105] The voltage converter described above includes a first capacitor C1, a second capacitor C2, a first inductor L1, a second inductor L2, a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4. The first terminal of the first capacitor C1 is connected to the first terminal of the first switch S1. The first terminals of the first inductor L1 and the third switch S3 are both connected to the second terminal of the first switch S1. The first terminal of the fourth switch S4 and the second terminal of the second switch S2 are both connected to the second terminal of the first inductor L1. The second terminal of the third switch S3 is connected to the second terminal of the second inductor L2. The second terminal of the fourth switch S4 is connected to the first terminal of the second inductor L2. The first terminal of the second switch S2 is connected to the first terminal of the second capacitor C2. The second terminal of the second capacitor C2 is connected to the second terminal of the second inductor L2. This voltage converter has a simple and symmetrical structure. By changing the conduction state of the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4, the voltage converter can operate in either boost or buck mode, achieving bidirectional operation. Furthermore, it can achieve boost conversion with high output gain and buck conversion with low output gain, exhibiting excellent performance and reliable operation.

[0106] In one embodiment, a control method for a voltage converter is provided, based on the voltage converter described above. Please refer to [link to relevant documentation]. Figure 9 The control method for the voltage converter includes the following steps:

[0107] Step S100: When a step-down command is received, the second switch is kept on and the first and third switches are controlled to perform complementary switching actions.

[0108] The conduction state of the fourth switch S4 is matched with the conduction state of the third switch S3.

[0109] Step S200: When a boost command is received, the first switch is kept on and the second and third switches are controlled to perform complementary switching actions.

[0110] The conduction state of the fourth switch S4 is matched with the conduction state of the third switch S3.

[0111] The control method of the voltage converter mentioned above includes a first capacitor C1, a second capacitor C2, a first inductor L1, a second inductor L2, a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4. The first terminal of the first capacitor C1 is connected to the first terminal of the first switch S1. The first terminals of the first inductor L1 and the third switch S3 are both connected to the second terminal of the first switch S1. The first terminal of the fourth switch S4 and the second terminal of the second switch S2 are both connected to the second terminal of the first inductor L1. The second terminal of the third switch S3 is connected to the second terminal of the second inductor L2. The second terminal of the fourth switch S4 is connected to the first terminal of the second inductor L2. The first terminal of the second switch S2 is connected to the first terminal of the second capacitor C2. The second terminal of the second capacitor C2 is connected to the second terminal of the second inductor L2. This voltage converter has a simple and symmetrical structure. By changing the conduction state of the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4, the voltage converter can operate in either boost or buck mode, achieving bidirectional operation. Furthermore, it can achieve boost conversion with high output gain and buck conversion with low output gain, exhibiting excellent performance and reliable operation.

[0112] In one embodiment, a control device for a voltage converter is provided, including a buck control module and a boost control module. The buck control module is used to control the second switch S2 to be constantly on when a buck command is received, and to control the first switch S1 and the third switch S3 to perform complementary switching operations, with the conduction state of the fourth switch S4 matching the conduction state of the third switch S3. The boost control module is used to control the first switch S1 to be constantly on when a boost command is received, and to control the second switch S2 and the third switch S3 to perform complementary switching operations, with the conduction state of the fourth switch S4 matching the conduction state of the third switch S3.

[0113] The control device of the aforementioned voltage converter includes a first capacitor C1, a second capacitor C2, a first inductor L1, a second inductor L2, a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4. The first terminal of the first capacitor C1 is connected to the first terminal of the first switch S1. The first terminals of the first inductor L1 and the third switch S3 are both connected to the second terminal of the first switch S1. The first terminal of the fourth switch S4 and the second terminal of the second switch S2 are both connected to the second terminal of the first inductor L1. The second terminal of the third switch S3 is connected to the second terminal of the second inductor L2. The second terminal of the fourth switch S4 is connected to the first terminal of the second inductor L2. The first terminal of the second switch S2 is connected to the first terminal of the second capacitor C2. The second terminal of the second capacitor C2 is connected to the second terminal of the second inductor L2. This voltage converter has a simple and symmetrical structure. By changing the conduction state of the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4, the voltage converter can operate in either boost or buck mode, achieving bidirectional operation. Furthermore, it can achieve boost conversion with high output gain and buck conversion with low output gain, exhibiting excellent performance and reliable operation.

[0114] In one embodiment, a voltage conversion device is provided, including a voltage converter as described above, and a control device for the voltage converter as described above.

[0115] The voltage conversion device described above includes a first capacitor C1, a second capacitor C2, a first inductor L1, a second inductor L2, a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4. The first terminal of the first capacitor C1 is connected to the first terminal of the first switch S1. The first terminals of the first inductor L1 and the third switch S3 are both connected to the second terminal of the first switch S1. The first terminal of the fourth switch S4 and the second terminal of the second switch S2 are both connected to the second terminal of the first inductor L1. The second terminal of the third switch S3 is connected to the second terminal of the second inductor L2. The second terminal of the fourth switch S4 is connected to the first terminal of the second inductor L2. The first terminal of the second switch S2 is connected to the first terminal of the second capacitor C2. The second terminal of the second capacitor C2 is connected to the second terminal of the second inductor L2. This voltage converter has a simple and symmetrical structure. By changing the conduction state of the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4, the voltage converter can operate in either boost or buck mode, achieving bidirectional operation. Furthermore, it can achieve boost conversion with high output gain and buck conversion with low output gain, exhibiting excellent performance and reliable operation.

[0116] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0117] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A voltage converter, characterized in that, It includes a first capacitor, a second capacitor, a first inductor, a second inductor, a first switching transistor, a second switching transistor, a third switching transistor, and a fourth switching transistor. The first terminal of the first capacitor is connected to the first terminal of the first switching transistor. The first terminals of the first inductor and the third switching transistor are both connected to the second terminals of the first switching transistor. The first terminal of the fourth switching transistor and the second terminal of the second switching transistor are both connected to the second terminals of the first inductor. The second terminal of the third switching transistor is connected to the second terminal of the second inductor. The second terminal of the fourth switching transistor is connected to the first terminal of the second inductor. The first terminal of the second switching transistor is connected to the first terminal of the second capacitor. The second terminal of the second capacitor is connected to the second terminal of the second inductor. It also includes a controller, and the control terminals of the first switch, the second switch, the third switch, and the fourth switch are all connected to the controller; The controller is configured to, upon receiving a buck command, control the second switch to remain constantly on, and control the first and third switches to perform complementary switching actions, and control the conduction state of the fourth switch to match the conduction state of the third switch; it is also configured to, upon receiving a boost command, control the first switch to remain constantly on, and control the second and third switches to perform complementary switching actions, and control the conduction state of the fourth switch to match the conduction state of the third switch. The voltage gain formula for the voltage converter in buck mode is: Among them, V i V represents the input voltage of the voltage converter. o d1 represents the output voltage of the voltage converter; d1 represents the voltage in one switching cycle T. s Within, the proportion of the conduction time of the first switching transistor; The voltage gain formula for the voltage converter in boost mode is: Among them, V i V represents the input voltage of the voltage converter. o d2 represents the output voltage of the voltage converter; d2 represents the voltage across the circuit in one switching cycle T. s Within, the proportion of the conduction time of the second switching transistor.

2. The voltage converter according to claim 1, characterized in that, The third and fourth switches operate synchronously.

3. The voltage converter according to claim 1, characterized in that, The inductance of the first inductor and the second inductor are matched.

4. The voltage converter according to claim 1, characterized in that, The first switch, the second switch, the third switch, and the fourth switch are all MOSFETs.

5. The voltage converter according to claim 4, characterized in that, The first switch, the second switch, the third switch, and the fourth switch are all N-channel MOSFETs.

6. A control method for a voltage converter, characterized in that, Based on the voltage converter according to any one of claims 1-5, the control method of the voltage converter includes the following steps: When a step-down command is received, the second switch is kept on and the first and third switches are controlled to perform complementary switching actions. The conduction state of the fourth switch is matched with the conduction state of the third switch. When a boost command is received, the first switch is kept on and the second and third switches are controlled to perform complementary switching actions. The conduction state of the fourth switch is matched with the conduction state of the third switch.

7. A control device for a voltage converter, characterized in that, Based on the voltage converter according to any one of claims 1-5, the control device of the voltage converter includes: The step-down control module is used to control the second switch to be constantly on when a step-down command is received, and to control the first switch and the third switch to perform complementary switching actions, wherein the conduction state of the fourth switch matches the conduction state of the third switch. The boost control module is used to control the first switch to be constantly on when a boost command is received, and to control the second and third switches to perform complementary switching actions, wherein the conduction state of the fourth switch is matched with the conduction state of the third switch.

8. A voltage conversion device, characterized in that, It includes the voltage converter as described in any one of claims 1-5, and further includes the control device of the voltage converter as described in claim 7.

Images