Switched capacitor resonant converter

Abstract

The application discloses a switched capacitor resonant converter. The switched capacitor resonant converter comprises an input end, an output end, a plurality of switching elements connected between the input end and the output end, a resonant capacitor and at least one resistor; the switching elements comprise at least one of a controllable switch tube and a diode; when the input end is powered, the resistor and the at least one switching element form a soft start loop for charging the resonant capacitor. The embodiment of the application only needs to add at least one resistor on the basis of the switched capacitor resonant converter circuit, so that the soft start pre-charging of the resonant capacitor is realized, and the problems of the existing soft start circuit of the switched capacitor resonant converter, such as complex circuit, redundant devices and high hardware cost, are overcome. Compared with the existing resonant capacitor pre-charging scheme through an external circuit and the like, the application simplifies the structure of the soft start circuit, simplifies the devices constituting the soft start circuit, and effectively reduces the hardware cost of the soft start circuit.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit, and particularly relates to a switched capacitor resonant converter. BACKGROUND

[0002] Compared with a conventional converter topology, the resonant converter has many advantages such as low switching loss, small voltage and current stress of switching devices, and is widely used in high-voltage and high-power scenarios.

[0003] At present, in the existing switched capacitor resonant converter, the resonant capacitor generally needs to be pre-charged by an additional external circuit or the like before normal work. It can be seen that the soft start circuit of the existing switched capacitor resonant converter has technical problems such as complex circuit, redundant devices and high hardware cost. SUMMARY

[0004] The present application provides a switched capacitor resonant converter to simplify the soft start circuit structure, reduce the devices constituting the soft start circuit, and reduce the hardware cost of the soft start circuit.

[0005] The present application provides a switched capacitor resonant converter, comprising an input end, an output end, a plurality of switching elements connected between the input end and the output end, a resonant capacitor and at least one resistor; the switching elements comprise at least one of a controllable switch tube and a diode;

[0006] When the input end is powered on, the resistor and at least one of the switching elements form a soft start loop for charging the resonant capacitor.

[0007] Optionally, after the circuit is stabilized, the resistor is configured to be in an open circuit state.

[0008] Optionally, after the circuit is stabilized, the resistor is configured to be short-circuited by the switching element.

[0009] Optionally, the input end comprises a positive input end and a negative input end, and the switched capacitor resonant converter further comprises a first voltage dividing capacitor and a second voltage dividing capacitor; the first voltage dividing capacitor and the second voltage dividing capacitor are connected in series between the positive input end and the negative input end.

[0010] When the input end is powered on, the common connection end between the first voltage dividing capacitor and the second voltage dividing capacitor and the resistor form a soft start loop for charging the resonant capacitor.

[0011] Optionally, at least one of the soft start resistors comprises a first soft start resistor.

[0012] The plurality of switching elements further include a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a first diode, a second diode, a third diode, and a fourth diode;

[0013] The switched capacitor resonant converter also includes an inductor;

[0014] The first, second, third, and fourth switching transistors are connected in series between the first terminal of the first voltage divider capacitor and the second terminal of the second voltage divider capacitor. The anode of the first diode is connected between the first and second voltage divider capacitors, the cathode of the first diode is connected between the first and second switching transistors, the anode of the second diode is connected between the third and fourth switching transistors, and the cathode of the second diode is connected to the anode of the first diode. The third and fourth diodes are connected in series between the negative output terminal and the positive output terminal, and the cathode of the fourth diode is connected to the second terminal of the fourth switching transistor. The first terminal of the resonant capacitor is connected between the second and third switching transistors, and the second terminal of the resonant capacitor is connected between the third and fourth diodes through the inductor. The first terminal of the first soft-start resistor is used to connect at least one of the switching elements, and the second terminal of the first soft-start resistor is connected to the first terminal of the resonant capacitor.

[0015] Optionally, the first terminal of the first soft-start resistor is connected to the cathode of the first diode;

[0016] When the input terminal is powered on, the common connection terminal, the first diode, the first soft-start resistor, the resonant capacitor, the inductor, and the fourth diode constitute the soft-start circuit.

[0017] Optionally, at least one of the resistors further includes a second soft-start resistor;

[0018] The first end of the first soft-start resistor is connected to the first end of the first switching transistor;

[0019] The first end of the second soft-start resistor is connected to the second end of the first soft-start resistor, and the second end of the second soft-start resistor is connected to the second end of the fourth switching transistor.

[0020] When the input terminal is powered on, the positive input terminal, the first soft-start resistor, the resonant capacitor, the inductor, and the fourth diode constitute the soft-start circuit.

[0021] Optionally, a soft start switch may also be included;

[0022] The first terminal of the first soft-start resistor is connected to the common connection terminal via the soft-start switch;

[0023] When the input end is powered on and the soft start switch is turned on, the common connection end, the soft start switch, the first soft start resistor, the resonant capacitor, the inductor and the fourth diode form the soft start loop.

[0024] Optionally, the first freewheeling diode, the second freewheeling diode, the third freewheeling diode, the fourth freewheeling diode and the output capacitor are further included.

[0025] The first freewheeling diode is connected in parallel between the first end and the second end of the first switch tube, the second freewheeling diode is connected in parallel between the first end and the second end of the second switch tube, the third freewheeling diode is connected in parallel between the first end and the second end of the third switch tube, and the fourth freewheeling diode is connected in parallel between the first end and the second end of the fourth switch tube; and the output capacitor is connected in parallel between the anode of the third diode and the cathode of the fourth diode.

[0026] Optionally, the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are insulated gate bipolar transistors; and the first voltage dividing capacitor and the second voltage dividing capacitor have the same capacitance.

[0027] The technical scheme provided by the embodiment of the application comprises an input end, an output end, a plurality of switch elements connected between the input end and the output end, a resonant capacitor and at least one resistor, the switch elements comprising at least one of controllable switch tubes and diodes, and when the input end is powered on, the resistor and at least one switch element can be used to form a soft start loop for charging the resonant capacitor.

[0028] As a typical non-magnetic element converter, a switched capacitor resonant converter generally comprises a certain number of switch elements and a resonant capacitor, the resonant capacitor serving as an energy storage element, and the switched capacitor resonant converter controls the charging and discharging time of the resonant capacitor through the switch elements, thereby realizing the conversion of electric energy.

[0029] Therefore, the embodiment of the present application realizes soft start pre-charging of the resonant capacitor by adding one or more resistors at the connection node of the plurality of switching elements in the switched capacitor resonant converter and pre-charging the resonant capacitor by using the soft start circuit composed of the switching elements and the soft start resistor. As can be seen, the embodiment of the present application only needs to add at least one resistor on the basis of the switched capacitor resonant converter circuit, so as to realize soft start pre-charging of the resonant capacitor, overcome the problems of complex circuit, redundant devices and high hardware cost of the soft start circuit of the existing switched capacitor resonant converter, simplify the structure of the soft start circuit, simplify the devices constituting the soft start circuit, and effectively reduce the hardware cost of the soft start circuit.

[0030] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present application, nor is it used to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0032] Figure 1 is a structure diagram of a switched capacitor resonant converter provided by the embodiment of the present application;

[0033] Figure 2 is a structure diagram of another switched capacitor resonant converter provided by the embodiment of the present application;

[0034] Figure 3 is a structure diagram of another switched capacitor resonant converter provided by the embodiment of the present application;

[0035] Figure 4 is a structure diagram of another switched capacitor resonant converter provided by the embodiment of the present application. DETAILED DESCRIPTION

[0036] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0037] It is to be understood that the terminology "first", "second", and the like used in the specification and the claims of the application as well as the appended drawings is merely used for distinguishing between similar objects and does not necessarily imply a particular order or chronology. It is to be understood that the use of the term "act" in the description and the claims of the application has been replaced herein with the term "operation" to avoid any ambiguity. It is to be understood that the data thus used in the specification and the claims of the application as well as the appended drawings is intended to be merely illustrative and is non-limiting; the scope of the application is not to be understood to be limited as long as the application can be practiced within the scope of the claims.

[0038] The switched-capacitor resonant converter is a typical non-magnetic element converter, and the circuit thereof is generally composed of a certain number of switching elements and a resonant capacitor. The resonant capacitor mainly plays a role of energy storage. The switched-capacitor resonant converter controls the charging and discharging time of the resonant capacitor through the switching elements, and thus realizes the conversion of electric energy. However, the inventor finds that in the existing switched-capacitor resonant converter, the resonant capacitor generally needs to be pre-charged by an additional external circuit or the like before normal operation. This soft start mode has technical problems such as complex circuit, device redundancy, and high hardware cost.

[0039] Therefore, in the embodiments of the application, one or more soft start resistors are added at the connection nodes of the multiple switching elements or unidirectional conductive devices in the switched-capacitor resonant converter, and the soft start circuit composed of the switching elements and the soft start resistors is used to pre-charge the resonant capacitor, so that the soft start boost of the resonant capacitor can be realized. Based on the above technical concept, the technical scheme of the application is as follows:

[0040] The soft start circuit of the switched-capacitor resonant converter comprises an input end, an output end, multiple switching elements connected between the input end and the output end, a resonant capacitor, and at least one resistor. The switching elements comprise at least one of a controllable switch tube and a diode. When the input end is powered, the resistor and the at least one switching element form a soft start loop for charging the resonant capacitor.

[0041] The controllable switch tube can be but is not limited to an Insulated Gate Bipolar Transistor (IGBT) or a Metal Oxide Semiconductor Field Effect Transistor (MOSFET).

[0042] Optionally, the switched-capacitor resonant converter further comprises an inductor.

[0043] Optionally, when the controllable switch in the switched-capacitor resonant converter commutates, the resonant circuit is in a resonant state, forcing the voltage or current on the controllable switch to be zero, thereby providing a zero-voltage or zero-current switching environment for the controllable switch.

[0044] It can be understood that when the input is powered on, the input, the connection nodes of the plurality of switching elements in the switched-capacitor resonant converter, the resistor, the resonant capacitor, the inductor, and the output can collectively form a soft start loop for charging the resonant capacitor, and automatically implement soft start boost of the resonant capacitor.

[0045] Therefore, according to the embodiment of the present application, at least one resistor is added to the switched-capacitor resonant converter circuit, thereby achieving soft start pre-charging of the resonant capacitor, overcoming the problems of complex circuit, redundant devices, and high hardware cost of the soft start circuit of the existing switched-capacitor resonant converter. Compared with the existing resonant capacitor pre-charging scheme through an external circuit, the structure of the soft start circuit is simplified, the devices constituting the soft start circuit are simplified, and the hardware cost of the soft start circuit is effectively reduced.

[0046] It should be noted that the specific types and characteristic parameters of the resonant capacitor, the inductor, and the resistor can be adaptively adjusted according to the actual application environment of the soft start circuit of the switched-capacitor resonant converter, and the embodiment of the present application does not limit this. For example, the resistor can be a surface mount resistor.

[0047] Based on the above embodiment, the inventor found that after the circuit is stabilized, the switched-capacitor resonant converter adjusts the charging and discharging time of the resonant capacitor by controlling the on-off of the switching element, thereby realizing conversion of electric energy. In this process, the on-off of the switching element can be used to configure the state of the resistor, thereby avoiding the influence of the resistor on the on-off of the switching element and the efficiency of the switched-capacitor resonant converter.

[0048] Specifically, optionally, after the circuit is stabilized, the resistor is configured to be in an open circuit state.

[0049] Wherein, it is known that in the working process of the switched-capacitor resonant converter, the switching elements are in a high-frequency switching state. If the resistor is not processed, the current flowing through the resistor will be converted into heat, reducing the efficiency and service life of the switched-capacitor resonant converter. Based on this, after the circuit is stable, the resistor configured as an open circuit state has no current flowing through it, which is difficult to affect the efficiency and service life of the switched-capacitor resonant converter. It can be understood that, for the same technical considerations, the resistor is optionally configured to be short-circuited by the switching element after the circuit is stable.

[0050] Optionally, the input end includes a positive input end and a negative input end, and the switched-capacitor resonant converter soft start circuit further includes a first voltage dividing capacitor and a second voltage dividing capacitor. The first voltage dividing capacitor and the second voltage dividing capacitor are connected in series between the positive input end and the negative input end. When the input end is powered on, the common connection end between the first voltage dividing capacitor and the second voltage dividing capacitor forms a soft start loop with the resistor to charge the resonant capacitor.

[0051] Wherein, the power-on of the input end refers to the existence of a voltage difference between the positive input end and the negative input end.

[0052] It is known that, since the first voltage dividing capacitor and the second voltage dividing capacitor are connected in series between the positive input end and the negative input end, when the positive input end is powered on, the first voltage dividing capacitor and the second voltage dividing capacitor divide the voltage according to the ratio of the capacitance values of the two capacitors. The common connection end between the first voltage dividing capacitor and the second voltage dividing capacitor, the connection node of the plurality of switching elements in the switched-capacitor resonant converter, the resistor, the resonant capacitor, the inductor, and the output end together form a soft start loop to charge the resonant capacitor. The voltage on the resonant capacitor is basically the same as the voltage on the common connection end, which can achieve soft start boost of the resonant capacitor.

[0053] In summary, the embodiment of the present application only needs to add at least one resistor to the switched-capacitor resonant converter circuit to achieve soft start pre-charging of the resonant capacitor, overcoming the problems of complex circuit, device redundancy, and high hardware cost of the existing soft start circuit of the switched-capacitor resonant converter. Compared with the existing resonant capacitor pre-charging scheme through external circuits and the like, the present application simplifies the structure of the soft start circuit, reduces the devices constituting the soft start circuit, and effectively reduces the hardware cost of the soft start circuit. In addition, after the soft start circuit of the switched-capacitor resonant converter is stable, the resistor is configured as an open circuit or a disconnected state to avoid the influence of the resistor on the on-off of the switching device and the efficiency of the switched-capacitor resonant converter as much as possible.

[0054] It should be noted that the specific types and characteristic parameters of the first voltage dividing capacitor and the second voltage dividing capacitor can be adaptively changed according to the actual application conditions of the soft start circuit of the switched-capacitor resonant converter, and the embodiment of the present application does not limit this. For example, both the first voltage dividing capacitor and the second voltage dividing capacitor can be ceramic capacitors.

[0055] On the basis of the above-mentioned embodiments, the soft start circuit structure of the switched capacitor resonant converter is further described below by taking a three-level switched capacitor resonant converter as an example, but the present application is not limited thereto.

[0056] Figure 1 is a structure diagram of a switched capacitor resonant converter provided by an embodiment of the present application. Referring to Figure 1 Optionally, the at least one resistor comprises a first soft start resistor R1.

[0057] The plurality of switching elements further comprise a first switch T1, a second switch T2, a third switch T3, a fourth switch T4, a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4. The first switch T1, the second switch T2, the third switch T3 and the fourth switch T4 are connected in series between the first end of the first voltage dividing capacitor C1 and the second end of the second voltage dividing capacitor C2.

[0058] The anode of the first diode D1 is connected between the first voltage dividing capacitor C1 and the second voltage dividing capacitor C2, the cathode of the first diode D1 is connected between the first switch T1 and the second switch T2, the anode of the second diode D2 is connected between the third switch T3 and the fourth switch T4, the cathode of the second diode D2 is connected to the anode of the first diode D1, the third diode D3 and the fourth diode D4 are connected in series between the negative output end and the positive output end, and the cathode of the fourth diode D4 is connected to the second end of the fourth switch T4.

[0059] The first end of the resonant capacitor Cf is connected between the second switch T2 and the third switch T3, and the second end of the resonant capacitor Cf is connected between the third diode D3 and the fourth diode D4 through the inductor Lf.

[0060] The first end of the first soft start resistor R1 is used to connect at least one of the switching elements, and the second end of the first soft start resistor R1 is connected to the first end of the resonant capacitor Cf.

[0061] The first end of the first soft start resistor R1 is used to connect at least one of the switching elements, and the second end of the first soft start resistor R1 is connected to the first end of the resonant capacitor Cf.

[0062] Optionally, the first freewheeling diode, the second freewheeling diode, the third freewheeling diode, the fourth freewheeling diode and the output capacitor C0 are further included; the first freewheeling diode is connected in parallel between the first end and the second end of the first switch tube T1, the second freewheeling diode is connected in parallel between the first end and the second end of the second switch tube T2, the third freewheeling diode is connected in parallel between the first end and the second end of the third switch tube T3, and the fourth freewheeling diode is connected in parallel between the first end and the second end of the fourth switch tube T4; the output capacitor C0 is connected in parallel between the anode of the third diode D3 and the cathode of the fourth diode D4.

[0063] The first freewheeling diode, the second freewheeling diode, the third freewheeling diode and the fourth freewheeling diode are respectively used to prevent the first switch tube T1, the second switch tube T2, the third switch tube T3 and the fourth switch tube T4 from being reversely broken down by the induced current generated by the inductor Lf.

[0064] It is known that the first switch tube T1, the second switch tube T2, the third switch tube T3 and the fourth switch tube T4 can be selected from one or more transistors, and the first switch tube T1, the second switch tube T2, the third switch tube T3 and the fourth switch tube T4 are respectively connected in parallel between the first end and the second end of the first soft start resistor R1. Figure 3 Optionally, the first switch tube T1, the second switch tube T2, the third switch tube T3 and the fourth switch tube T4 are insulated gate bipolar transistors.

[0065] It can be understood that there are many ways to connect the input voltage V1 to the first end of the first soft start resistor R1, and the following will be described by taking a specific three-level switch capacitor resonant converter soft start circuit as an example.

[0066] Figure 2 is another structure diagram of a switch capacitor resonant converter provided by the embodiment of the present application. Referring to Figure 2 , the switch capacitor resonant converter includes a positive input end, a negative input end, a positive output end, a negative output end, a first voltage dividing capacitor C1, a second voltage dividing capacitor C2, a first soft start resistor R1, an inductor Lf, a resonant capacitor Cf, a first switch tube T1, a second switch tube T2, a third switch tube T3, a fourth switch tube T4, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first freewheeling diode, a second freewheeling diode, a third freewheeling diode, a fourth freewheeling diode and an output capacitor C0.

[0067] The first voltage dividing capacitor C1 and the second voltage dividing capacitor C2 are connected in series between the positive input end and the negative input end. The first switch tube T1, the second switch tube T2, the third switch tube T3 and the fourth switch tube T4 are connected in series between the first end of the first voltage dividing capacitor C1 and the second end of the second voltage dividing capacitor C2. The anode of the first diode D1 is connected between the first voltage dividing capacitor C1 and the second voltage dividing capacitor C2, the cathode of the first diode D1 is connected between the first switch tube T1 and the second switch tube T2, the anode of the second diode D2 is connected between the third switch tube T3 and the fourth switch tube T4, the cathode of the second diode D2 is connected with the anode of the first diode D1, the third diode D3 and the fourth diode D4 are connected in series between the negative output end and the positive output end, and the cathode of the fourth diode D4 is connected with the second end of the fourth switch tube T4. The first end of the resonance capacitor Cf is connected between the second switch tube T2 and the third switch tube T3, and the second end of the resonance capacitor Cf is connected between the third diode D3 and the fourth diode D4 through the inductor Lf. The second end of the first soft start resistor R1 is connected with the first end of the resonance capacitor Cf. The first freewheeling diode is connected in parallel between the first end and the second end of the first switch tube T1, the second freewheeling diode is connected in parallel between the first end and the second end of the second switch tube T2, the third freewheeling diode is connected in parallel between the first end and the second end of the third switch tube T3, and the fourth freewheeling diode is connected in parallel between the first end and the second end of the fourth switch tube T4; and the output capacitor C0 is connected in parallel between the anode of the third diode D3 and the cathode of the fourth diode D4.

[0068] Continuing to refer to Figure 2 Optionally, the first end of the first soft start resistor R1 is connected with the cathode of the first diode D1; when the input end is powered, the common connection end, the first diode D1, the first soft start resistor R1, the resonance capacitor Cf, the inductor Lf and the fourth diode D4 form a soft start loop.

[0069] When the input end is powered or the input end is suddenly applied with a voltage, the first voltage dividing capacitor C1 and the second voltage dividing capacitor C2 divide the voltage of the input end, and optionally, the capacitance of the first voltage dividing capacitor C1 and the second voltage dividing capacitor C2 is the same, and at this time, the voltage of the common connection end between the first voltage dividing capacitor C1 and the second voltage dividing capacitor C2 is half of the voltage of the input end. In the soft start circuit, due to the unidirectional conductivity of the diode, the common connection end, the first diode D1, the first soft start resistor R1, the resonance capacitor Cf, the inductor Lf and the fourth diode D4 together form a soft start loop, and automatically realize soft start voltage rise of the resonance capacitor Cf. After the circuit is stable, the voltage across the resonance capacitor Cf is equal to half of the voltage of the input end.

[0070] It can be seen that, by adding the first soft start resistor, the soft start pre-charging of the resonance capacitor can be realized, and the problems of complex circuit, redundant devices and high hardware cost of the existing soft start circuit of the switched capacitor resonance converter are overcome. Compared with the existing resonance capacitor pre-charging scheme through an external circuit, the structure of the soft start circuit is effectively simplified, the devices constituting the soft start circuit are simplified, and the hardware cost of the soft start circuit is reduced.

[0071] It should be noted that, in the soft start circuit of the switched capacitor resonance converter as shown in Figure 2 , the resistance of the first soft start resistor R1 is large, and can be preferably set to tens of kilo-ohms to hundreds of kilo-ohms.

[0072] Figure 3 is another structure diagram of a switched capacitor resonance converter provided by the embodiment of the application. Referring to Figure 3 , the switched capacitor resonance converter includes a positive input end, a negative input end, a positive output end, a negative output end, a first voltage dividing capacitor C1, a second voltage dividing capacitor C2, a first soft start resistor R1, an inductor Lf, a resonance capacitor Cf, a first switch T1, a second switch T2, a third switch T3, a fourth switch T4, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first freewheeling diode, a second freewheeling diode, a third freewheeling diode, a fourth freewheeling diode, and an output capacitor C0.

[0073] The first voltage division capacitor C1 and the second voltage division capacitor C2 are connected in series between the positive input end and the negative input end. The first switch tube T1, the second switch tube T2, the third switch tube T3 and the fourth switch tube T4 are connected in series between the first end of the first voltage division capacitor C1 and the second end of the second voltage division capacitor C2. The anode of the first diode D1 is connected between the first voltage division capacitor C1 and the second voltage division capacitor C2, the cathode of the first diode D1 is connected between the first switch tube T1 and the second switch tube T2, the anode of the second diode D2 is connected between the third switch tube T3 and the fourth switch tube T4, the cathode of the second diode D2 is connected with the anode of the first diode D1, the third diode D3 and the fourth diode D4 are connected in series between the negative output end and the positive output end, and the cathode of the fourth diode D4 is connected with the second end of the fourth switch tube T4. The first end of the resonance capacitor Cf is connected between the second switch tube T2 and the third switch tube T3, and the second end of the resonance capacitor Cf is connected between the third diode D3 and the fourth diode D4 through the inductor Lf. The second end of the first soft start resistor R1 is connected with the first end of the resonance capacitor Cf. The first freewheeling diode is connected in parallel between the first end and the second end of the first switch tube T1, the second freewheeling diode is connected in parallel between the first end and the second end of the second switch tube T2, the third freewheeling diode is connected in parallel between the first end and the second end of the third switch tube T3, and the fourth freewheeling diode is connected in parallel between the first end and the second end of the fourth switch tube T4; and the output capacitor C0 is connected in parallel between the anode of the third diode D3 and the cathode of the fourth diode D4.

[0074] Continuing to refer to Figure 3 Optionally, the at least one resistor further comprises a second soft start resistor R2; the first end of the first soft start resistor R1 is connected with the first end of the first switch tube T1; the first end of the second soft start resistor R2 is connected with the second end of the first soft start resistor R1, and the second end of the second soft start resistor R2 is connected with the second end of the fourth switch tube T4; when the input end is powered on, the positive input end, the first soft start resistor R1, the resonance capacitor Cf, the inductor Lf and the fourth diode D4 form a soft start loop.

[0075] When the input end is powered on or a voltage is suddenly added to the input end, the input end voltage flows to the output end through the first soft start resistor R1, the resonance capacitor Cf, the inductor Lf and the fourth diode D4, thereby achieving soft start voltage boosting of the resonance capacitor Cf. In addition, the first soft start resistor R1 and the second soft start resistor R2 divide the input end voltage, and if the resistance values of the first soft start resistor R1 and the second soft start resistor R2 are the same, the voltage across the resonance capacitor Cf is equal to half of the input end voltage after the circuit is stabilized.

[0076] Therefore, by adding the first soft start resistor and the second soft start resistor, the soft start pre-charging of the resonant capacitor can be realized, and the problems of complex circuit, redundant devices and high hardware cost of the existing soft start circuit of the switched capacitor resonant converter are overcome. Compared with the existing resonant capacitor pre-charging scheme through an external circuit, the structure of the soft start circuit is simplified, the devices constituting the soft start circuit are reduced, and the hardware cost of the soft start circuit is effectively reduced.

[0077] Figure 4 is another structure diagram of a switched capacitor resonant converter provided by the embodiment of the present application. Referring to Figure 4 , the switched capacitor resonant converter comprises a positive input end, a negative input end, a positive output end, a negative output end, a first voltage dividing capacitor C1, a second voltage dividing capacitor C2, a first soft start resistor R1, an inductor Lf, a resonant capacitor Cf, a first switch T1, a second switch T2, a third switch T3, a fourth switch T4, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a first freewheeling diode, a second freewheeling diode, a third freewheeling diode, a fourth freewheeling diode and an output capacitor C0.

[0078] The first voltage dividing capacitor C1 and the second voltage dividing capacitor C2 are connected in series between the positive input end and the negative input end. The first switch T1, the second switch T2, the third switch T3 and the fourth switch T4 are connected in series between a first end of the first voltage dividing capacitor C1 and a second end of the second voltage dividing capacitor C2. An anode of the first diode D1 is connected between the first voltage dividing capacitor C1 and the second voltage dividing capacitor C2, a cathode of the first diode D1 is connected between the first switch T1 and the second switch T2, an anode of the second diode D2 is connected between the third switch T3 and the fourth switch T4, a cathode of the second diode D2 is connected with the anode of the first diode D1, the third diode D3 and the fourth diode D4 are connected in series between the negative output end and the positive output end, and a cathode of the fourth diode D4 is connected with the second end of the fourth switch T4. A first end of the resonant capacitor Cf is connected between the second switch T2 and the third switch T3, and a second end of the resonant capacitor Cf is connected between the third diode D3 and the fourth diode D4 through the inductor Lf. A second end of the first soft start resistor R1 is connected with the first end of the resonant capacitor Cf. The first freewheeling diode is connected in parallel between the first end and the second end of the first switch T1, the second freewheeling diode is connected in parallel between the first end and the second end of the second switch T2, the third freewheeling diode is connected in parallel between the first end and the second end of the third switch T3, and the fourth freewheeling diode is connected in parallel between the first end and the second end of the fourth switch T4; and the output capacitor C0 is connected in parallel between the anode of the third diode D3 and the cathode of the fourth diode D4.

[0079] Continuing to refer to Figure 4Optionally, the soft start circuit of the switched capacitor resonant converter further comprises a soft start switch S; a first end of the first soft start resistor R1 is connected to the common connection end through the soft start switch S; when the input end is powered on and the soft start switch S is turned on, the common connection end, the soft start switch S, the first soft start resistor R1, the resonant capacitor Cf, the inductor Lf and the fourth diode D4 form a soft start loop.

[0080] When the input end is powered on or a voltage is suddenly added to the input end, the first voltage dividing capacitor C1 and the second voltage dividing capacitor C2 divide the voltage of the input end, and if the capacitance values of the first voltage dividing capacitor C1 and the second voltage dividing capacitor C2 are the same, the voltage of the common connection end between the first voltage dividing capacitor C1 and the second voltage dividing capacitor C2 is half of the voltage of the input end.

[0081] It can be understood that, in the soft start circuit, when the input end is powered on or a voltage is suddenly added to the input end, the soft start switch S is turned on, at this time, the common connection end, the soft start switch S, the first soft start resistor R1, the resonant capacitor Cf, the inductor Lf and the fourth diode D4 form a soft start loop, and soft start voltage boosting of the resonant capacitor Cf is automatically realized. After the circuit is stable, the voltage across the resonant capacitor Cf is equal to half of the voltage of the input end, at the same time, the soft start switch S is turned off, that is, the first soft start resistor is configured as an open circuit state, and the influence of the first soft start resistor R1 on the on-off of each switch tube in the soft start circuit and the efficiency of the switched capacitor resonant converter is effectively avoided.

[0082] It can be seen that, by adding the soft start switch and the first soft start resistor, the soft start pre-charging of the resonant capacitor is realized, the problems of complex circuit, redundant devices and high hardware cost of the existing soft start circuit of the switched capacitor resonant converter are overcome, the structure of the soft start circuit is simplified, the devices constituting the soft start circuit are simplified, and the hardware cost of the soft start circuit is reduced compared with the existing resonant capacitor pre-charging scheme through external circuits and the like.

[0083] It should be noted that, in the above-mentioned soft start circuit of the switched capacitor resonant converter, the specific model and characteristic parameters of the soft start circuit components such as the first diode D1 and the soft start switch S can be adaptively selected according to the actual application needs of the soft start circuit, and the embodiments of the present application do not limit this.

[0084] It should be understood that various forms of the flow shown above can be used to reorder, add or delete steps. For example, each step described in the present application can be executed in parallel, sequentially or in different order, as long as the desired results of the technical solutions of the present application can be achieved, and the present application does not limit this.

[0085] The above detailed description does not limit the scope of the application. Various modifications, combinations, sub-combinations and alternatives can be made to the detailed description. Any modification, equivalent replacement and improvement etc. made within the spirit and principle of the application shall be included in the scope of the application.

Claims

1. A switched-capacitor resonant converter, characterized in that, It includes an input terminal, an output terminal, a plurality of switching elements connected between the input terminal and the output terminal, a resonant capacitor, and at least one resistor; the switching elements include at least one of a controllable switching transistor and a diode; When the input terminal is powered on, the resistor and at least one of the switching elements form a soft-start circuit for charging the resonant capacitor; The input terminal includes a positive input terminal and a negative input terminal, and the switched capacitor resonant converter further includes a first voltage divider capacitor and a second voltage divider capacitor; the first voltage divider capacitor and the second voltage divider capacitor are connected in series between the positive input terminal and the negative input terminal. When the input terminal is powered on, the common connection terminal between the first voltage divider capacitor and the second voltage divider capacitor forms a soft-start circuit with the resistor to charge the resonant capacitor. The at least one resistor includes a first soft-start resistor, a first end of which is used to connect to at least one of the switching elements, and a second end of which is connected to the first end of the resonant capacitor.

2. The switched capacitor resonant converter according to claim 1, characterized in that, After the circuit stabilizes, the resistor is configured to be in an open-circuit state.

3. The switched capacitor resonant converter according to claim 1, characterized in that, After the circuit stabilizes, the resistor is configured to be short-circuited by the switching element.

4. The switched capacitor resonant converter according to claim 1, characterized in that, The output terminal includes a positive output terminal and a negative output terminal; the plurality of switching elements further include a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a first diode, a second diode, a third diode, and a fourth diode; The switched capacitor resonant converter also includes an inductor; The first, second, third, and fourth switching transistors are connected in series between the first terminal of the first voltage-dividing capacitor and the second terminal of the second voltage-dividing capacitor. The anode of the first diode is connected between the first and second voltage-dividing capacitors, the cathode of the first diode is connected between the first and second switching transistors, the anode of the second diode is connected between the third and fourth switching transistors, and the cathode of the second diode is connected to the anode of the first diode. The third and fourth diodes are connected in series between the negative output terminal and the positive output terminal, and the cathode of the fourth diode is connected to the second terminal of the fourth switching transistor. The first terminal of the resonant capacitor is connected between the second and third switching transistors, and the second terminal of the resonant capacitor is connected between the third and fourth diodes through the inductor.

5. The switched capacitor resonant converter according to claim 4, characterized in that, The first terminal of the first soft-start resistor is connected to the cathode of the first diode; When the input terminal is powered on, the common connection terminal, the first diode, the first soft-start resistor, the resonant capacitor, the inductor, and the fourth diode constitute the soft-start circuit.

6. The switched capacitor resonant converter according to claim 4, characterized in that, At least one of the resistors further includes a second soft-start resistor; The first end of the first soft-start resistor is connected to the first end of the first switching transistor; The first end of the second soft-start resistor is connected to the second end of the first soft-start resistor, and the second end of the second soft-start resistor is connected to the second end of the fourth switching transistor. When the input terminal is powered on, the positive input terminal, the first soft-start resistor, the resonant capacitor, the inductor, and the fourth diode constitute the soft-start circuit.

7. The switched capacitor resonant converter according to claim 4, characterized in that, It also includes a soft start switch; The first terminal of the first soft-start resistor is connected to the common connection terminal via the soft-start switch; When the input terminal is powered on and the soft start switch is turned on, the common connection terminal, the soft start switch, the first soft start resistor, the resonant capacitor, the inductor, and the fourth diode constitute the soft start circuit.

8. The switched-capacitor resonant converter according to any one of claims 4-7, characterized in that, It also includes a first freewheeling diode, a second freewheeling diode, a third freewheeling diode, a fourth freewheeling diode, and an output capacitor; The first freewheeling diode is connected in parallel between the first and second terminals of the first switching transistor; the second freewheeling diode is connected in parallel between the first and second terminals of the second switching transistor; the third freewheeling diode is connected in parallel between the first and second terminals of the third switching transistor; and the fourth freewheeling diode is connected in parallel between the first and second terminals of the fourth switching transistor. The output capacitor is connected in parallel between the anode of the third diode and the cathode of the fourth diode.

9. The switched capacitor resonant converter according to claim 8, characterized in that, The first, second, third, and fourth switching transistors are insulated-gate bipolar transistors; the first and second voltage-dividing capacitors have the same capacitance value.

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