A resonant DC / DC converter, system and method, controller
By controlling the switching frequency according to the gain range during the startup process of the resonant DC/DC converter, it can achieve zero-current turn-off in both under-resonance and over-resonance states, thus solving the problem of high current stress on the primary circuit switching transistor, reducing losses and maintaining high transmission power.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUNGROW POWER SUPPLY CO LTD
- Filing Date
- 2026-03-30
- Publication Date
- 2026-06-26
AI Technical Summary
During the startup process of a resonant DC/DC converter, the switching transistors in the primary circuit are difficult to turn off with zero current, which causes the transistors to be subjected to large current stress and may be damaged. Increasing the switching frequency will increase switching losses and reduce transmission power.
During the startup process of the resonant DC/DC converter, the controller controls the switching frequency of the primary circuit according to different gain ranges. When the gain is less than 1, the primary circuit is in an under-resonant state with a switching frequency lower than the resonant frequency; when the gain is greater than 1, the primary circuit is in an over-resonant state with a switching frequency higher than the resonant frequency. This achieves zero-current turn-off of the primary circuit's switching transistors.
It achieves protection of the switching transistors, reduction of switching losses, and maintenance of high transmission power throughout the entire startup process of the resonant DC/DC converter.
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Figure CN122292899A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of DC power conversion technology, specifically to a resonant DC / DC converter, system, method, and controller. Background Technology
[0002] Resonant DC / DC converters can be applied in various scenarios. For example, in residential applications, they can boost the voltage of a battery cell to power the load or the next stage of the circuit. With the development of large-scale energy storage, large battery cells are widely used. However, due to the relatively small capacity of residential energy storage, the number of cells is reduced when using a single large cell, and the voltage generally cannot be very high, while the power rating still needs to remain constant. In this case, the primary circuit of the resonant DC / DC converter faces the requirement of low-voltage, high-current operation. To reduce the current stress on the switching transistors in the primary circuit and protect them, the switching transistors in the primary circuit need to achieve zero-current switching (ZCS).
[0003] In related technologies, the turn-off current of the primary circuit's switching transistors is reduced by increasing the switching frequency during the entire startup process of a resonant DC / DC converter. However, increasing the switching frequency increases switching losses, reduces transmission power, and cannot fully achieve the zero-current-strain (ZCS) of the switching transistors. This leaves the primary circuit's switching transistors still subjected to significant current stress, potentially leading to transistor damage. Summary of the Invention
[0004] In view of this, this application provides a resonant DC / DC converter, system, method, and controller that enables the switching transistors of the primary circuit of the resonant DC / DC converter to achieve zero-current turn-off during the startup process of the resonant DC / DC converter, thereby protecting the switching transistors.
[0005] This application provides a resonant DC / DC converter, including: a primary circuit, a resonant cavity, a secondary circuit, and a controller; The first end of the primary circuit is used to connect to a DC source, the second end of the primary circuit is connected to the first end of the resonant cavity, and the second end of the resonant cavity is connected to the secondary circuit. The controller is used to achieve zero-current turn-off of the primary circuit's switching transistors when the gain of the resonant DC / DC converter is less than 1 and the switching frequency of the resonant DC / DC converter is less than the resonant frequency of the resonant cavity; and to achieve zero-current turn-off of the primary circuit's switching transistors when the gain of the resonant DC / DC converter is greater than 1 and the switching frequency of the resonant DC / DC converter is greater than the resonant frequency of the resonant cavity.
[0006] One possible implementation is a controller used to achieve zero-current turn-off of the primary circuit's switching transistors when the gain of the resonant DC / DC converter is equal to 1 during startup, and the switching frequency of the resonant DC / DC converter is less than or equal to the resonant frequency of the resonant cavity.
[0007] In one possible implementation, the controller is also used to control the switching transistors of the primary and secondary circuits according to the switching frequency and the phase shift angle between the primary and secondary circuits, so that the switching transistor of the primary circuit is turned off with zero current; the gain, phase shift angle, switching frequency and resonant frequency satisfy the relationship that enables the switching transistor of the primary circuit to be turned off with zero current.
[0008] One possible implementation is that the controller is also used to obtain the switching frequency based on the gain and resonant frequency when the gain of the resonant DC / DC converter is less than 1; and to obtain the phase shift angle between the primary and secondary circuits based on the resonant frequency and the switching frequency.
[0009] One possible implementation is that the controller is also used to obtain the switching frequency based on the resonant frequency when the gain of the resonant DC / DC converter is greater than 1; and to obtain the phase shift angle between the primary and secondary circuits based on the gain, resonant frequency, and switching frequency.
[0010] One possible implementation is that after the resonant DC / DC converter has started up, the voltage at the first terminal of the primary circuit is lower than the voltage at the second terminal of the secondary circuit.
[0011] One possible implementation is that the primary-side circuit includes a first switch and a second switch, and the resonant cavity includes a transformer, a resonant inductor, and a capacitor bridge arm; the secondary-side circuit includes a third switch and a fourth switch. The first end of the primary winding of the transformer is connected to the positive terminal of the first terminal of the primary circuit, the second end of the primary winding of the transformer is connected to the negative terminal of the first terminal of the primary circuit through the first switching transistor, and the third end of the primary winding of the transformer is connected to the negative terminal of the first terminal of the primary circuit through the second switching transistor. The first terminal of the third switch is connected to the positive terminal of the second terminal of the secondary circuit, and the second terminal of the third switch is connected to the negative terminal of the second terminal of the secondary circuit through the fourth switch. The capacitor bridge arm is connected in parallel to the second terminal of the secondary circuit. The first terminal of the secondary winding of the transformer is connected to the common terminal of the third and fourth switches through the resonant inductor, and the second terminal of the secondary winding of the transformer is connected to the midpoint of the capacitor bridge arm.
[0012] This application also provides a power supply system, including the resonant DC / DC converter described above; the resonant DC / DC converter is used to connect to a DC source.
[0013] This application also provides a control method for a resonant DC / DC converter, comprising: during the startup process of the resonant DC / DC converter, when the gain of the resonant DC / DC converter is less than 1, controlling the switching frequency of the resonant DC / DC converter to be less than the resonant frequency of the resonant DC / DC converter to achieve zero-current turn-off of the switching transistor in the primary circuit of the resonant DC / DC converter; when the gain of the resonant DC / DC converter is greater than 1, controlling the switching frequency of the resonant DC / DC converter to be greater than the resonant frequency to achieve zero-current turn-off of the switching transistor in the primary circuit.
[0014] One possible implementation method further includes: during the startup process of the resonant DC / DC converter, when the gain of the resonant DC / DC converter is equal to 1, controlling the switching frequency of the resonant DC / DC converter to be less than or equal to the resonant frequency, thereby achieving zero-current turn-off of the switching transistor in the primary circuit.
[0015] One possible implementation method further includes: controlling the switching transistors of the primary and secondary circuits according to the switching frequency and the phase shift angle between the primary and secondary circuits, so that the switching transistor of the primary circuit is turned off with zero current; the gain, phase shift angle, switching frequency and resonant frequency satisfy the relationship that enables the switching transistor of the primary circuit to be turned off with zero current.
[0016] One possible implementation method further includes: obtaining the switching frequency based on the gain and resonant frequency when the gain of the resonant DC / DC converter is less than 1; and obtaining the phase shift angle between the primary circuit and the secondary circuit based on the resonant frequency and the switching frequency. When the gain of the resonant DC / DC converter is greater than 1, the switching frequency is obtained from the resonant frequency; the phase shift angle between the primary and secondary circuits is obtained from the gain, resonant frequency, and switching frequency.
[0017] This application also provides a controller for performing the methods described above.
[0018] The resonant DC / DC converter provided in this application includes a primary-side circuit, a resonant cavity, a secondary-side circuit, and a controller. The controller controls the switching frequency of the primary-side circuit's transistors to vary according to different gain ranges. When the gain of the resonant DC / DC converter is less than 1, the controller controls the switching frequency of the resonant DC / DC converter to be lower than the resonant frequency of the resonant cavity; when the gain of the resonant DC / DC converter is greater than 1, the controller controls the switching frequency of the resonant DC / DC converter to be greater than the resonant frequency of the resonant cavity. During the startup process of the resonant DC / DC converter, when the gain is less than 1, the resonant DC / DC converter is controlled to operate in an under-resonant state, which allows the primary-side circuit's transistors to achieve zero-current turn-off. When the gain is greater than 1, the resonant DC / DC converter is controlled to operate in an over-resonant state, which also allows the primary-side circuit's transistors to achieve zero-current turn-off. This protects the transistors throughout the startup process, reduces switching losses, and allows the resonant DC / DC converter to maintain high power transmission during startup. Attached Figure Description
[0019] Figure 1 A schematic diagram of a first type of resonant DC / DC converter provided in the embodiments of this application; Figure 2 A schematic diagram of a second type of resonant DC / DC converter provided in the embodiments of this application; Figure 3 A schematic diagram of a third type of resonant DC / DC converter provided in the embodiments of this application; Figure 4 A schematic diagram of a switch-driven square wave provided in an embodiment of this application; Figure 5 A flowchart illustrating a control method for a resonant DC / DC converter provided in this application embodiment; Figure 6 This is a schematic diagram of a controller provided in an embodiment of this application. Detailed Implementation
[0020] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the embodiments of this application will be further described in detail below with reference to the accompanying drawings and specific implementation methods.
[0021] The embodiments of this application do not specifically limit the application scenarios of the resonant DC / DC converter, but can be applied to residential energy storage scenarios.
[0022] See Figure 1 The figure is a schematic diagram of the first type of resonant DC / DC converter provided in the embodiments of this application.
[0023] The resonant DC / DC converter provided in this application includes: a primary circuit 101, a resonant cavity 102, a secondary circuit 103, and a controller 104.
[0024] The first terminal of the primary-side circuit 101 is connected to a DC source Vp, which may be a battery cell. The second terminal of the primary-side circuit 101 is connected to the first terminal of the resonant cavity 102, and the second terminal of the resonant cavity 102 is connected to the secondary-side circuit 103; for example, the resonant cavity 102 may include an inductor and a capacitor. In one possible implementation, the secondary-side circuit 103 is used to connect to a load or a next-stage circuit. Figure 1 Taking the secondary circuit 103 used to connect the load as an example.
[0025] Controller 104 is used to control the switching frequency f of the resonant DC / DC converter when the gain of the resonant DC / DC converter is less than 1 during the startup process of the resonant DC / DC converter. s The resonant frequency f of the resonant cavity 102 is less than r In the case of zero-current turn-off of the switching transistor in the primary circuit 101, when the gain of the resonant DC / DC converter is greater than 1, the switching frequency f of the resonant DC / DC converter is controlled. s The resonant frequency f of the resonant cavity 102 is greater than r In this case, the switching transistor of the primary circuit 101 is turned off with zero current.
[0026] This application does not specifically limit the structure of the primary circuit, resonant cavity, and secondary circuit of the resonant DC / DC converter. In one possible implementation, the resonant DC / DC converter can be a dual-bridge series resonant DC / DC converter.
[0027] See Figure 2 This figure is a schematic diagram of a full-bridge isolated resonant DC / DC converter provided in an embodiment of this application.
[0028] The primary circuit 101 and secondary circuit 103 of the resonant DC / DC converter provided in this application embodiment are both H-bridge structures. The primary circuit 101 includes a first bridge arm S1 and a second bridge arm S2 connected in parallel; the secondary circuit 103 includes a third bridge arm S3 and a fourth bridge arm S4 connected in parallel. The resonant cavity 102 includes a first transformer T1, an inductor L, and a capacitor C.
[0029] The two ends of the primary winding of the first transformer T1 are respectively connected to the midpoints of the first bridge arm S1 and the second bridge arm S2; the first end of the secondary winding of the first transformer T1 is connected to the midpoint of the third bridge arm S3 through an inductor L and a capacitor C, and the second end of the secondary winding of the first transformer T1 is connected to the midpoint of the fourth bridge arm S4. This application does not specifically limit the exact positions of the inductor L and capacitor C; for example, the inductor L and capacitor C can be connected in series with the primary winding of the first transformer T1, or they can be connected in series with the secondary winding of the first transformer T1.
[0030] Figure 2 A dual-bridge series resonant DC / DC converter has been introduced. Another possible implementation of the resonant DC / DC converter provided in the embodiments of this application is described below.
[0031] See Figure 3 The figure is a schematic diagram of a boost-isolated resonant DC / DC converter provided in an embodiment of this application.
[0032] The primary-side circuit 101 of the resonant DC / DC converter provided in this embodiment includes a first switch Q1 and a second switch Q2. The resonant cavity 102 includes a transformer T, a resonant inductor Lr, and a capacitor bridge arm SC. The capacitor bridge arm SC includes a first capacitor C1 and a second capacitor C2, and the common terminal of the first capacitor C1 and the second capacitor C2 is the midpoint of the bridge arm SC. The secondary-side circuit 103 includes a third switch Q3 and a fourth switch Q4.
[0033] The first terminal of the primary winding of transformer T is connected to the positive terminal of the first terminal of primary circuit 101. The second terminal of the primary winding of transformer T is connected to the negative terminal of the first terminal of primary circuit 101 through the first switch Q1. The third terminal of the primary winding of transformer T is connected to the negative terminal of the first terminal of primary circuit 101 through the second switch Q2. The positive terminal of the first terminal of primary circuit 101 is connected to the positive terminal of DC source Vp, and the negative terminal of the first terminal of primary circuit 101 is connected to the negative terminal of DC source Vp.
[0034] The first terminal of the third switch Q3 is connected to the positive terminal of the second terminal of the secondary circuit 103. The second terminal of the third switch Q3 is connected to the negative terminal of the second terminal of the secondary circuit 103 through the fourth switch Q4. The capacitor bridge arm SC is connected in parallel to the second terminal of the secondary circuit 103. The first terminal of the secondary winding of the transformer T is connected to the common terminal of the third switch Q3 and the fourth switch Q4 through the resonant inductor Lr. The second terminal of the secondary winding of the transformer T is connected to the midpoint of the bridge arm of the capacitor bridge arm SC.
[0035] Wherein, the resonant frequency f r The resonant frequency f is obtained from the inductor and capacitor connected in series in the resonant cavity 102. rIt is determined by the leakage inductance of transformer T, the resonant inductance Lr, and the equivalent capacitance of capacitor bridge arm SC. Specifically, Figure 3 In the resonant DC / DC converter shown, the resonant capacitor is the equivalent capacitance of the first capacitor C1 and the second capacitor C2 connected in parallel.
[0036] The gain M of a resonant DC / DC converter can be expressed as the ratio of the output voltage of the secondary circuit 103 to the input voltage of the primary circuit 101. For example, for... Figure 3 The resonant DC / DC converter shown has an output voltage of Vs in the secondary circuit 103, so the gain M is M = Vs / (2Vp). The most direct definition of gain is the ratio of the peak value of the square wave voltage on the secondary side of the resonant cavity to the peak value of the square wave voltage on the primary side of the resonant cavity. Therefore, for... Figure 3 In the topology shown, because the secondary side includes a first capacitor C1 and a second capacitor C2 connected in series, the peak value of the square wave voltage on the right side of the resonant cavity, i.e., the secondary side, is actually Vs / 2, while the peak value of the primary side voltage is Vp. N is the transformer turns ratio. Therefore, the gain M is Vs / (2NVp).
[0037] Figure 3 The topology shown has a low-voltage primary circuit and a high-voltage secondary circuit, achieving a relatively high boost ratio. This makes it suitable for applications with low DC source voltage and high low-voltage current. Furthermore, the capacitor bridge uses a split capacitor architecture, with the secondary voltage being twice that of the transformer secondary. The structure of the primary circuit enables a 2x voltage boost. With a constant transformer turns ratio, the high-voltage voltage is four times that of the low-voltage voltage, achieving a 4x boost. This simplifies transformer design, allowing for a 4x boost without requiring a very large transformer turns ratio. Simultaneously, the primary circuit structure allows only one switch to carry current at a time, making it suitable for high-current scenarios on the low-voltage side with low switching losses. This is particularly suitable for single-cell scenarios, i.e., low-voltage, high-current applications on the primary side requiring a high boost ratio.
[0038] In steady-state operation, for a boost converter, the gain M of a resonant DC / DC converter is relatively fixed, and the switching transistors in the primary-side circuit 101 can easily achieve ZCS (Zero-Cost-Side Response). However, during the startup process of the resonant DC / DC converter, the output voltage Vs of the secondary-side circuit 103 gradually rises from 0 to the normal operating voltage, and the gain M also gradually rises from 0 to its normal value; that is, the gain M is in a constantly changing process. Related technologies do not consider the impact of the change in gain M on the switching frequency f. s The effect of increasing the switching frequency f throughout the entire startup process of a resonant DC / DC converter is significant. sThis method reduces the turn-off current of the switching transistor. However, for the primary circuit of a resonant DC / DC converter, when the switching frequency is higher than the resonant frequency, the switching transistor of the primary circuit 101 cannot achieve ZCS, and a continuously high switching frequency f is required. s It will also reduce the transmission power of the resonant DC / DC converter and increase the switching loss.
[0039] Therefore, in the resonant DC / DC converter provided in this application embodiment, the controller 104 is used to control the switching transistors of the primary circuit 101 to use different switching frequencies according to different ranges of gain M. Specifically, when the gain M of the resonant DC / DC converter is less than 1, the controller 104 controls the switching frequency f of the resonant DC / DC converter. s The resonant frequency f of the resonant cavity 102 is less than r This means the resonant DC / DC converter is in an underresonant state; when the gain M of the resonant DC / DC converter is greater than 1, the controller 104 controls the switching frequency f of the resonant DC / DC converter. s The resonant frequency f of the resonant cavity 102 is greater than r This means that the resonant DC / DC converter is in an over-resonant state. When M<1 and the operation is in an under-resonant state, the switching transistors of the primary circuit can achieve ZCS. When M>1 and the operation is in an over-resonant state, the switching transistors of the primary circuit can also achieve ZCS.
[0040] The resonant DC / DC converter provided in this application includes a primary-side circuit, a resonant cavity, a secondary-side circuit, and a controller. The controller controls the switching frequency of the primary-side circuit's transistors to vary according to different gain ranges. When the gain of the resonant DC / DC converter is less than 1, the controller controls the switching frequency of the resonant DC / DC converter to be less than the resonant frequency of the resonant cavity; when the gain of the resonant DC / DC converter is greater than 1, the controller controls the switching frequency of the resonant DC / DC converter to be greater than the resonant frequency of the resonant cavity. During the startup process of the resonant DC / DC converter, when the gain is less than 1, the resonant DC / DC converter is controlled to operate in an under-resonant state, which allows the primary-side circuit's transistors to achieve zero-current turn-off; when the gain is greater than 1, the resonant DC / DC converter is controlled to operate in an over-resonant state, which also allows the primary-side circuit's transistors to achieve zero-current turn-off. This protects the transistors throughout the startup process, reduces switching losses, and allows the resonant DC / DC converter to maintain high power transmission during startup.
[0041] In one possible implementation, the controller 104 is used to control the switching frequency of the resonant DC / DC converter to be less than or equal to the resonant frequency of the resonant cavity when the gain of the resonant DC / DC converter is equal to 1 during the startup process of the resonant DC / DC converter, so that the switching transistor of the primary circuit is turned off with zero current.
[0042] To enable those skilled in the art to better understand the control logic of controller 104, the following will continue to use... Figure 3 Taking the resonant DC / DC converter shown as an example, the selection of switching frequency values will be introduced.
[0043] In one possible implementation, the controller 104 is used to control the switching transistors of the primary circuit 101 and the secondary circuit 103 according to the switching frequency fs and the phase shift angle x between the primary circuit 101 and the secondary circuit 103, so that the switching transistor of the primary circuit 101 is turned off with zero current; the gain M, the phase shift angle x, and the switching frequency fs are used to control the switching transistors of the primary circuit 101 and the secondary circuit 103. s and resonant frequency f r The relationship between them satisfies the condition that the switching transistor of the primary circuit 101 is turned off with zero current.
[0044] Wherein, the phase shift angle x between the primary circuit 101 and the secondary circuit 103 is the time difference dT between the driving square wave of the second switch Q2 and the driving square wave of the third switch Q3 divided by the total switching period Ts, that is, x = dT / Ts.
[0045] See Figure 4 The figure is a schematic diagram of a switch driving a square wave provided in an embodiment of this application.
[0046] When M is less than or equal to 1, in order to achieve ZCS for the switching transistor in the primary circuit 101, the gain M and the switching frequency f s Resonant frequency f r The phase shift angle x and the phase shift angle x need to satisfy the following relationship (1): (1).
[0047] The equation shown in formula (1) above represents the condition for the switch in the primary circuit 101 to achieve ZCS. When the gain M is small, for example, M < 1, if the switching frequency is greater than the resonant frequency (i.e., over-resonance operation), then no matter how the phase shift angle x is adjusted, the left and right sides of the equation in formula (1) cannot be made equal. Therefore, ZCS of the switch cannot be achieved when M < 1 and over-resonance occurs. However, if the switching frequency is less than the resonant frequency (i.e., under-resonance operation), then ZCS of the switch can be achieved.
[0048] The resonant DC / DC converter provided in this application provides a switching frequency and phase shift angle that enable zero-current turn-off of the primary circuit's switching transistors based on different gain values. The controller controls the switching transistors of the primary and secondary circuits according to the switching frequency and the phase shift angle between the primary and secondary circuits. This allows for zero-current turn-off of the primary circuit's switching transistors even with continuously changing gain during the resonant DC / DC converter's startup process.
[0049] The following examples illustrate the switching frequency f in equation (1). s The specific solution method for the phase shift angle x.
[0050] In one possible implementation, the controller 104 is configured to, when the gain M of the resonant DC / DC converter is less than 1, determine the relationship between the gain M and the resonant frequency f. r Obtain the switching frequency f s It is also used based on the resonant frequency f. r and switching frequency f s Obtain the phase shift angle x between the primary circuit 101 and the secondary circuit 103.
[0051] Specifically, in expression (1) ,in, Then we get the following equation (2): (2).
[0052] Since M < 1 and Therefore, by performing an inverse trigonometric function transformation on equation (2), the switching frequency f can be solved. s As shown in equation (3): (3).
[0053] Based on equations (1) and (3), the phase shift angle x can be obtained as shown in equation (4): (4).
[0054] In one possible implementation, the controller 104 is configured to, when the gain M of the resonant DC / DC converter is greater than 1, determine the resonant frequency f. r Obtain the switching frequency f s It is also used to determine the gain M and resonant frequency f. r and switching frequency f s Obtain the phase shift angle x between the primary circuit 101 and the secondary circuit 103.
[0055] The difference from the above embodiments where the gain M is less than 1 is that, when M is greater than 1, in order to make the gain M less than 1, the gain M is ... If the value range remains within 0 to 1, then we need to let the value in equation (1) be... ,in, Then we have the following equation (5): (5).
[0056] Since M>1 and Therefore, by performing an inverse trigonometric function transformation on equation (5), the switching frequency f can be solved. s As shown in equation (6): (6).
[0057] Based on equations (1) and (6), the phase shift angle x can be obtained as shown in equation (7): (7).
[0058] This application does not specifically limit the value of λ. As long as λ meets the above range, it can be selected according to the actual situation. In one possible implementation, when M is less than 1, λ can be 1.
[0059] Therefore, at the start of the resonant DC / DC converter, the gain M≤1. Using formulas (3) and (4) to determine the switching frequency and external phase shift angle, the ZCS of the primary circuit can be achieved, and power is continuously transferred to the secondary circuit, causing the voltage of the secondary circuit to continuously rise. When the voltage rises to M>1, using formulas (6) and (7) to determine the switching frequency and external phase shift angle, the ZCS of the primary circuit can also be achieved, and power is continuously transferred to the secondary circuit, causing the voltage of the secondary circuit to continuously rise until it reaches the target voltage, at which point the start-up ends.
[0060] The above embodiments take a boost resonant DC / DC converter as an example. That is, after the resonant DC / DC converter is started, the voltage at the first terminal of the primary circuit 101 is lower than the voltage at the second terminal of the secondary circuit 103.
[0061] Based on the resonant DC / DC converters provided in the above embodiments, this application also provides a power supply system. The power supply system provided in this application includes any of the above-described resonant DC / DC converters. In some examples, the power supply system may further include a DC source Vp.
[0062] This application does not specifically limit the type of switching transistor in the resonant DC / DC converter. The switching transistor can be a fully controllable switching transistor, that is, it can control the switching transistor to be turned on and off.
[0063] Based on the resonant DC / DC converter provided in the above embodiments, this application also provides a control method for the resonant DC / DC converter.
[0064] See Figure 5 The figure is a flowchart of a control method for a resonant DC / DC converter provided in an embodiment of this application.
[0065] The method includes: S501: During the startup process of the resonant DC / DC converter, when the gain of the resonant DC / DC converter is less than 1, the switching frequency of the resonant DC / DC converter is controlled to be less than the resonant frequency of the resonant DC / DC converter, and the switching transistor of the primary circuit is controlled to turn off with zero current.
[0066] For example, during the startup process of a resonant DC / DC converter, the gain of the resonant DC / DC converter gradually increases from 0. When the gain of the resonant DC / DC converter is less than 1, the controller controls the switching frequency of the resonant DC / DC converter to be less than the resonant frequency, so that the resonant DC / DC converter is in an under-resonant state, so that the switching transistor of the primary circuit can be turned off with zero current in this state.
[0067] S502: During the startup process of a resonant DC / DC converter, when the gain of the resonant DC / DC converter is greater than 1, and the switching frequency of the resonant DC / DC converter is greater than the resonant frequency, the switching transistor controlling the primary circuit is turned off with zero current.
[0068] For example, when the gain of a resonant DC / DC converter is greater than 1, the switching frequency of the resonant DC / DC converter is controlled to be greater than the resonant frequency, so that the resonant DC / DC converter is in an over-resonance state, in which the switching transistor of the primary circuit can be turned off with zero current.
[0069] The control method for a resonant DC / DC converter provided in this application controls the switching frequency of the primary circuit's switching transistors to vary according to different gain ranges. When the gain of the resonant DC / DC converter is less than 1, the switching frequency is controlled to be lower than the resonant frequency of the resonant cavity; when the gain is greater than 1, the switching frequency is controlled to be greater than the resonant frequency of the resonant cavity. During the startup process of the resonant DC / DC converter, when the gain is less than 1, the resonant DC / DC converter is controlled to operate in an under-resonant state, which allows the primary circuit's switching transistors to achieve zero-current turn-off; when the gain is greater than 1, the resonant DC / DC converter is controlled to operate in an over-resonant state, which also achieves zero-current turn-off. Therefore, throughout the startup process, the switching transistors are protected, switching losses are reduced, and the resonant DC / DC converter maintains high power transmission during startup.
[0070] In one possible implementation, the method further includes: during the startup process of the resonant DC / DC converter, when the gain of the resonant DC / DC converter is equal to 1, controlling the switching frequency of the resonant DC / DC converter to be less than or equal to the resonant frequency of the resonant cavity, so that the switching transistor of the primary circuit is turned off with zero current.
[0071] In one possible implementation, the method further includes: controlling the switching transistors of the primary and secondary circuits according to the switching frequency and the phase shift angle between the primary and secondary circuits, so that the switching transistor of the primary circuit is turned off with zero current; the gain, phase shift angle, switching frequency and resonant frequency satisfy a relationship that enables the switching transistor of the primary circuit to be turned off with zero current.
[0072] One possible implementation of the method further includes: When the gain of the resonant DC / DC converter is less than 1, the switching frequency is obtained based on the gain and the resonant frequency; the phase shift angle between the primary and secondary circuits is obtained based on the resonant frequency and the switching frequency. When the gain of the resonant DC / DC converter is greater than 1, the switching frequency is obtained from the resonant frequency; the phase shift angle between the primary and secondary circuits is obtained from the gain, resonant frequency, and switching frequency.
[0073] In one possible implementation, see Figure 6 The figure is a schematic diagram of a controller provided in an embodiment of this application.
[0074] The controller may include a memory 2011 and a processor 2012. The processor 2012 can be connected to the primary and secondary circuits of a resonant DC / DC converter and can drive the corresponding switching transistors. For example... Figure 6 As shown, the memory can be random access memory (RAM), flash memory, read-only memory (ROM), EPROM, non-volatile read-only memory (Electronic Programmable ROM), registers, hard disks, removable disks, etc.
[0075] The memory 2011 can store computer instructions. When the computer instructions stored in the memory 2011 are executed by the processor 2012, the processor 2012 can be used to perform the methods described above. The memory 2011 can also store data, such as formulas and other information involved in the above embodiments.
[0076] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape) or a semiconductor medium (e.g., solid-state disk (SSD)).
[0077] This application also provides a readable storage medium for storing the methods provided in the above embodiments. Examples include random access memory (RAM), flash memory, read-only memory (ROM), EPROM, non-volatile read-only memory (EPROM), registers, hard disks, removable disks, or any other form of storage medium in the art.
[0078] The controller provided in this application embodiment may include software to implement the control methods described above. Alternatively, the controller provided in this application embodiment may include hardware to implement the control methods described above. Or, the controller provided in this application embodiment may include both software and hardware, using a combination of software and hardware to execute the control methods described above.
[0079] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0080] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A resonant DC / DC converter, characterized in that, include: Primary circuit, resonant cavity, secondary circuit, and controller; The first end of the primary circuit is used to connect to a DC source, the second end of the primary circuit is connected to the first end of the resonant cavity, and the second end of the resonant cavity is connected to the secondary circuit. The controller is configured to, during the startup process of the resonant DC / DC converter, when the gain of the resonant DC / DC converter is less than 1, control the switching frequency of the resonant DC / DC converter to be less than the resonant frequency of the resonant cavity, thereby achieving zero-current turn-off of the switching transistor of the primary circuit. When the gain of the resonant DC / DC converter is greater than 1, and the switching frequency of the resonant DC / DC converter is controlled to be greater than the resonant frequency of the resonant cavity, the switching transistor of the primary circuit can be turned off with zero current.
2. The converter according to claim 1, characterized in that, The controller is configured to, during the startup process of the resonant DC / DC converter, when the gain of the resonant DC / DC converter is equal to 1, control the switching frequency of the resonant DC / DC converter to be less than or equal to the resonant frequency of the resonant cavity, thereby achieving zero-current turn-off of the switching transistor of the primary circuit.
3. The converter according to claim 1 or 2, characterized in that, The controller is further configured to control the switching transistors of the primary circuit and the secondary circuit according to the switching frequency and the phase shift angle between the primary circuit and the secondary circuit, so that the switching transistor of the primary circuit is turned off with zero current. The gain, the phase shift angle, the switching frequency, and the resonant frequency satisfy a relationship that enables the switching transistor of the primary circuit to turn off with zero current.
4. The converter according to claim 3, characterized in that, The controller is further configured to, when the gain of the resonant DC / DC converter is less than 1, obtain the switching frequency based on the gain and the resonant frequency; and obtain the phase shift angle between the primary circuit and the secondary circuit based on the resonant frequency and the switching frequency.
5. The converter according to claim 3, characterized in that, The controller is further configured to obtain the switching frequency based on the resonant frequency when the gain of the resonant DC / DC converter is greater than 1; and to obtain the phase shift angle between the primary circuit and the secondary circuit based on the gain, the resonant frequency and the switching frequency.
6. The converter according to any one of claims 1-5, characterized in that, After the resonant DC / DC converter is started, the voltage at the first terminal of the primary circuit is lower than the voltage at the second terminal of the secondary circuit.
7. The converter according to claim 6, characterized in that, The primary-side circuit includes a first switch and a second switch, and the resonant cavity includes a transformer, a resonant inductor, and a capacitor bridge arm; the secondary-side circuit includes a third switch and a fourth switch. The first end of the primary winding of the transformer is connected to the positive terminal of the first terminal of the primary circuit, the second end of the primary winding of the transformer is connected to the negative terminal of the first terminal of the primary circuit through the first switching transistor, and the third end of the primary winding of the transformer is connected to the negative terminal of the first terminal of the primary circuit through the second switching transistor. The first terminal of the third switch is connected to the positive terminal of the second terminal of the secondary circuit, and the second terminal of the third switch is connected to the negative terminal of the second terminal of the secondary circuit through the fourth switch. The capacitor bridge arm is connected in parallel to the second terminal of the secondary circuit. The first terminal of the secondary winding of the transformer is connected to the common terminal of the third switch and the fourth switch through the resonant inductor, and the second terminal of the secondary winding of the transformer is connected to the midpoint of the capacitor bridge arm.
8. A power supply system, characterized in that, Includes the resonant DC / DC converter according to any one of claims 1-7; the resonant DC / DC converter is used to connect to a DC source.
9. A control method for a resonant DC / DC converter, characterized in that, include: During the startup process of the resonant DC / DC converter, when the gain of the resonant DC / DC converter is less than 1, the switching frequency of the resonant DC / DC converter is controlled to be less than the resonant frequency of the resonant DC / DC converter, thereby achieving zero-current turn-off of the switching transistors in the primary circuit of the resonant DC / DC converter. When the gain of the resonant DC / DC converter is greater than 1, and the switching frequency of the resonant DC / DC converter is controlled to be greater than the resonant frequency, the switching transistor of the primary circuit is turned off with zero current.
10. The method according to claim 9, characterized in that, Also includes: During the startup process of the resonant DC / DC converter, when the gain of the resonant DC / DC converter is equal to 1, the switching frequency of the resonant DC / DC converter is controlled to be less than or equal to the resonant frequency, thereby achieving zero-current turn-off of the switching transistor of the primary circuit.
11. The method according to claim 9 or 10, characterized in that, Also includes: Based on the switching frequency and the phase shift angle between the primary circuit and the secondary circuit, the switching transistors of the primary circuit and the secondary circuit are controlled so that the switching transistor of the primary circuit is turned off with zero current. The gain, the phase shift angle, the switching frequency, and the resonant frequency satisfy a relationship that enables the switching transistor of the primary circuit to turn off with zero current.
12. The method according to claim 11, characterized in that, Also includes: When the gain of the resonant DC / DC converter is less than 1, the switching frequency is obtained based on the gain and the resonant frequency. The phase shift angle between the primary circuit and the secondary circuit is obtained based on the resonant frequency and the switching frequency; When the gain of the resonant DC / DC converter is greater than 1, the switching frequency is obtained based on the resonant frequency; the phase shift angle between the primary circuit and the secondary circuit is obtained based on the gain, the resonant frequency, and the switching frequency.
13. A controller, characterized in that, Used to perform the method as described in any one of claims 9-12.