Control method of resonant conversion circuit and resonant conversion circuit
By performing delay control on both sides of the opening and closing of the passive lower bridge arm of the resonant conversion circuit and combining it with the binary function of setting voltage and frequency, the problems of limited gain and inaccurate control of the resonant conversion circuit are solved, and the gain range is expanded and the control accuracy is improved.
Patent Information
- Application Number
- CN202510871389.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-26
- Publication Date
- 2025-09-12
AI Technical Summary
When traditional resonant converter circuits control output voltage and power by changing frequency under specific topology and load conditions, the gain is limited, and the existing delay control cannot accurately set the voltage, resulting in hard switching of the switch tube and damaging the device.
By performing delay control on both sides of the opening and closing of the lower bridge arm of the passive tube, the overlapping conduction time of the switch tube control signal is doubled, the inductive energy storage is increased, and the set voltage is introduced as the control variable to construct a binary function of delay time and frequency, and the delay time is solved at high frequency, medium frequency and low frequency respectively.
The gain range of the resonant conversion circuit is expanded to meet the output requirements, while avoiding the hard switching damage to the switch tube caused by excessive delay and improving the control accuracy.
Smart Images
Figure CN120638868A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of electric energy conversion, and in particular to a control method of a resonant conversion circuit and a resonant conversion circuit. Background Art
[0002] Traditional resonant converter (LLC) circuit control controls the output voltage and power of a power supply by varying the frequency. However, under certain topologies and load conditions, the resonant converter circuit is limited by its inherent gain, and frequency variation alone cannot meet output requirements. Therefore, delay control must be introduced into the resonant converter circuit control to increase line gain to meet output requirements. However, excessive delay can cause hard switching of the switch, thereby damaging the device. Due to the limitation of delay size, the gain that can be achieved by delay control in existing technologies is limited.
[0003] In addition, the existing delay control only considers the relationship between the delay size and frequency, and cannot accurately control the set voltage output by the resonant conversion circuit, and its usage scenarios are limited. Summary of the Invention
[0004] The present application aims to provide a control method and a resonant conversion circuit that expand the gain range while taking into account the relationship between the delay size, frequency and set voltage.
[0005] To achieve the above objectives, the technical solution of this application is:
[0006] A control method for a resonant conversion circuit is applied to a resonant conversion circuit, wherein the resonant conversion circuit includes a primary-side conversion module, a resonant conversion module, and a secondary-side conversion module; the primary-side conversion module, the resonant conversion module, and the secondary-side conversion module are connected in sequence;
[0007] The control method of the resonant conversion circuit includes:
[0008] The switch tube of the lower bridge arm of the second bridge arm of the passive tube and the switch tube of the upper bridge arm of the first bridge arm of the active tube are controlled to be turned on at the same time, and the switch tube of the lower bridge arm of the second bridge arm of the passive tube is turned off with a time delay compared with the switch tube of the upper bridge arm of the first bridge arm of the active tube; the switch tube of the lower bridge arm of the first bridge arm of the passive tube and the switch tube of the lower bridge arm of the first bridge arm of the active tube are controlled to be turned on at the same time, and the switch tube of the lower bridge arm of the first bridge arm of the passive tube is turned off with a time delay compared with the switch tube of the lower bridge arm of the first bridge arm of the active tube;
[0009] Introducing the set voltage as the control variable and fixing the variable frequency, we can get the relationship between the set voltage and the maximum delay time.
[0010] The frequency is solved quadratically at high frequency, medium frequency and low frequency respectively to obtain the relationship between the delay time and the maximum delay time and the frequency, and a control method for the resonant conversion circuit is constructed with the set voltage and frequency as the control variables.
[0011] Optionally, the relationship between the set voltage and the maximum delay time is expressed as follows:
[0012] T 最大延时 =0.25×set voltage value-9
[0013] Among them, T 最大延时 Indicates the maximum delay time.
[0014] Optionally, in the case of high frequency, medium frequency and low frequency, the relationship between the delay time and the maximum delay time and the frequency is expressed as follows:
[0015] high frequency:
[0016] IF:
[0017] Low frequency:
[0018] Among them, T 延时 Indicates the delay time.
[0019] Optionally, it is determined whether to use a high frequency, a medium frequency or a low frequency case for calculation according to the load characteristics of the resonant conversion circuit.
[0020] Optionally, a pulse width modulation signal is used to control the switching states of the passive tube and the active tube, and the switching tube controls the time of delayed shutdown according to the control signal.
[0021] A resonant conversion circuit executes the control method of the resonant conversion circuit as described in any one of the above items, wherein the resonant conversion circuit includes a primary-side conversion module, a resonant conversion module, and a secondary-side conversion module; the primary-side conversion module, the resonant conversion module, and the secondary-side conversion module are connected in sequence; a first end of the primary-side conversion module is connected to an input voltage, and a second end of the secondary-side conversion module is connected to an output voltage.
[0022] Optionally, the resonant conversion module includes: a first capacitor, a first inductor and a transformer, the transformer includes: a primary winding and a secondary winding; the first capacitor, the first inductor and the primary winding are connected in series, and the two ends of the series connection are the first ends of the resonant conversion module; the two ends of the secondary winding are the second ends of the resonant conversion module.
[0023] Optionally, the secondary side conversion module includes: a first bridge arm of the passive tube and a second bridge arm of the passive tube, the first bridge arm of the passive tube and the second bridge arm of the passive tube are connected in parallel, and the two ends after the parallel connection constitute the second end of the secondary side conversion module, and the midpoint of the bridge arm of the first bridge arm of the passive tube and the midpoint of the bridge arm of the second bridge arm of the passive tube constitute the first end of the secondary side conversion module.
[0024] Optionally, the primary side conversion module includes: a first bridge arm of the active tube and a second bridge arm of the active tube, the first bridge arm of the active tube and the second bridge arm of the active tube are connected in parallel, and the two ends after the parallel connection constitute the first end of the primary side conversion module, and the midpoint of the bridge arm of the first bridge arm of the active tube and the midpoint of the bridge arm of the second bridge arm of the active tube constitute the second end of the primary side conversion module.
[0025] Optionally, the primary side conversion module includes: a first bridge arm of the active transistor, a first terminal of the first bridge arm of the active transistor and a second terminal of the first bridge arm of the active transistor constitute a first end of the primary side conversion module, and a midpoint of the first bridge arm of the active transistor and the second terminal of the first bridge arm of the active transistor constitute a second end of the primary side conversion module.
[0026] The control method and resonant conversion circuit of the present application perform delay control on both sides of the opening and closing of the lower bridge arm of the passive tube, so that the time of overlapping conduction of the control signals of the switch tubes of the lower bridge arm of the two passive tubes is doubled, and the energy storage of the inductor Lr is increased, thereby improving the gain of the resonant conversion circuit, expanding the voltage regulation range, and meeting the output requirements. At the same time, delay control is performed on both sides of the opening and closing of the lower bridge arm of the passive tube, thereby avoiding excessive delay causing hard switching on the switch tube, thereby damaging the device. Furthermore, the problem that delay control only considers the relationship between delay time and frequency is solved, and the set voltage is introduced as a control variable to construct a binary function of the delay time with respect to the set voltage and frequency. The delay time is solved by piecewise linear fitting at three sections: high frequency, medium frequency, and low frequency, thereby improving the control accuracy of the resonant conversion circuit.
[0027] In order to make the above features and advantages of the application more obvious and easy to understand, the following embodiments are given and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 This is a circuit diagram of the first specific embodiment of the resonant conversion circuit proposed in this application.
[0029] Figure 2 This is a circuit diagram of the second specific embodiment of the resonant conversion circuit proposed in this application.
[0030] Figure 3 This is a flow chart of a control method for a resonant conversion circuit provided in this application.
[0031] Figure 4 This is a schematic diagram of the control signal waveforms received by the four switching tubes of the resonant conversion circuit. DETAILED DESCRIPTION
[0032] To make the purpose and technical solutions of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be clearly and completely described below in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0033] This application provides a control method for a resonant conversion circuit, which is applied to the resonant conversion circuit. Figure 1 , Figure 1 This is a circuit diagram of the first specific embodiment of the resonant conversion circuit proposed in this application. The resonant conversion circuit includes a primary-side conversion module 11, a resonant conversion module 12 and a secondary-side conversion module 13; the primary-side conversion module 11, the resonant conversion module 12 and the secondary-side conversion module 13 are connected in sequence.
[0034] As an example, the first terminal of the primary side conversion module 11 is connected to the input voltage V in The second end of the secondary side conversion module 13 is connected to the output voltage V out .
[0035] The resonant converter circuit also includes a capacitor C o With resistor R o , capacitor C o In parallel with the output voltage V out The two ends of the capacitor C o With resistor R o in parallel.
[0036] The resonant conversion module 12 includes: a capacitor C r 、Inductor L r and transformer T1( Figure 1 The transformer T1 includes: the primary winding N1 and the secondary winding N2 ( Figure 1 Capacitor C r 、Inductor L r The two ends of the series connection are the first end of the resonant conversion module 12, which is connected to the second end of the primary conversion module 11; the two ends of the secondary winding N2 are the second end of the resonant conversion module 12, which is connected to the first end of the secondary conversion module 13. The resonant conversion module 12 also includes: an inductor L m , inductance L m Connected in parallel at both ends of the primary winding N1. Among them, the inductor L m is the magnetizing inductance.
[0037] The secondary conversion module 13 has a full-bridge rectifier structure, and its switching transistors are passive transistors. The secondary conversion module 13 includes a first passive transistor bridge arm 131 and a second passive transistor bridge arm 132. The first passive transistor bridge arm 131 and the second passive transistor bridge arm 132 are connected in parallel, forming the second end of the secondary conversion module 13. The midpoints of the first passive transistor bridge arm 131 and the second passive transistor bridge arm 132 form the first end of the secondary conversion module 13. The first passive transistor bridge arm 131 includes switches S1 and S2, and the second passive transistor bridge arm 132 includes switches S3 and S4. The first terminal of switch S1 is connected to the first terminal of switch S3, the second terminal of switch S1 is connected to the first terminal of switch S2 and the first terminal of secondary winding N2, the second terminal of switch S2 is connected to the second terminal of switch S4, and the first terminal of switch S4 is connected to the second terminal of switch S3 and the second terminal of secondary winding N2.
[0038] Among them, the switch tube S2 is the switch tube of the lower bridge arm of the passive tube first bridge arm 131, and the switch tube S1 is the switch tube of the upper bridge arm of the passive tube first bridge arm 131; the switch tube S4 is the switch tube of the lower bridge arm of the passive tube second bridge arm 132, and the switch tube S3 is the switch tube of the upper bridge arm of the passive tube second bridge arm 132.
[0039] The primary-side conversion module 11 of the resonant conversion circuit adopts a full-bridge inverter structure. The switching transistors of the primary-side conversion module 11 are active transistors. The primary-side conversion module 11 includes: an active transistor first bridge arm 111 and an active transistor second bridge arm 112. The first and second active transistor bridge arms 111 and 112 are connected in parallel. The two ends of the parallel connection constitute the first end of the primary-side conversion module 11. The midpoint of the first active transistor bridge arm 111 and the midpoint of the second active transistor bridge arm 112 constitute the second end of the primary-side conversion module 11. The first active transistor bridge arm 111 includes: switching transistors S5 and S6. The second active transistor bridge arm 112 includes: switching transistors S7 and S8. The first terminal of the switching transistor S5 is connected to the first terminal of the switching transistor S7, and the second terminal of the switching transistor S5 is connected to the first terminal of the switching transistor S6 and the inductor L. r The first terminal of the switch tube S6 is connected to the second terminal of the switch tube S8, and the first terminal of the switch tube S8 is connected to the second terminal of the switch tube S7 and the second terminal of the primary winding N1.
[0040] Among them, the switch tube S5 is the switch tube of the upper bridge arm of the first bridge arm 111 of the active transistor, the switch tube S6 is the switch tube of the lower bridge arm of the first bridge arm 111 of the active transistor; the switch tube S7 is the switch tube of the upper bridge arm of the second bridge arm 112 of the active transistor, and the switch tube S8 is the switch tube of the lower bridge arm of the second bridge arm 112 of the active transistor.
[0041] See also Figure 2 , Figure 2This is a circuit diagram of the second specific embodiment of the resonant conversion circuit proposed in this application. In this specific embodiment, the switch tube of the secondary side conversion module 23 is a passive tube. The secondary side conversion module 23 includes: a passive tube first bridge arm 231 and a passive tube second bridge arm 232. The passive tube first bridge arm 231 and the passive tube second bridge arm 232 are connected in parallel. The two ends after parallel connection constitute the second end of the secondary side conversion module 23. The bridge arm midpoint of the passive tube first bridge arm 231 and the bridge arm midpoint of the passive tube second bridge arm 232 constitute the first end of the secondary side conversion module 23. The passive tube first bridge arm 231 includes: a switch tube S9 and a diode D1. The passive tube second bridge arm 232 includes: a switch tube S 10 , diode D2; the cathode of diode D1 is connected to the cathode of diode D2, the anode of diode D1 is connected to the first terminal of switch tube S9 and the first terminal of secondary winding N2, the second terminal of switch tube S9 is connected to switch tube S 10 The second terminal of the switch tube S 10 The first terminal of is connected to the anode of the diode D2 and the second terminal of the secondary winding N2.
[0042] The switch tube S9 is the switch tube of the lower bridge arm of the first bridge arm 231 of the passive tube. 10 It is the switch tube of the lower bridge arm of the second bridge arm 232 of the passive tube.
[0043] The primary side conversion module 21 of the resonant conversion circuit adopts a half-bridge inverter structure. The switch tube of the primary side conversion module 21 is an active tube. The primary side conversion module 21 includes an active tube first bridge arm 211. The first terminal of the active tube first bridge arm 211 and the second terminal of the active tube first bridge arm 211 constitute the first end of the primary side conversion module 21. The bridge arm midpoint of the active tube first bridge arm 211 and the second terminal of the active tube first bridge arm 211 constitute the second end of the primary side conversion module 21. The active tube first bridge arm 211 includes a switch tube S 11 , switch tube S 12 ; Switching tube S 11 The second terminal is connected to the switch tube S 12 The first terminal and the inductor L r The first terminal of the switch tube S 11 The first terminal of the active transistor first bridge arm 211 is the first terminal of the switch transistor S 12 The second terminal of is the second terminal of the first bridge arm 211 of the active transistor.
[0044] Among them, the switch tube S 11 is the switch tube of the upper bridge arm of the first bridge arm 211 of the active transistor, the switch tube S 12 It is the switch tube of the lower bridge arm of the first bridge arm 211 of the active tube.
[0045] As an example, the switch tubes used in the resonant conversion circuit are all N-type MOSFETs; wherein the first terminal of the switch tube is the drain of the N-type MOSFET, and the second terminal of the switch tube is the source of the N-type MOSFET.
[0046] See also Figure 3 , Figure 3 This is a flow chart of a control method for a resonant conversion circuit provided in the present application. The control method for a resonant conversion circuit provided in the present application includes: steps S1 to S3.
[0047] Step S1: Controlling the switch tube of the lower bridge arm of the second bridge arm of the passive tube and the switch tube of the upper bridge arm of the first bridge arm of the active tube to be turned on simultaneously, and the switch tube of the lower bridge arm of the second bridge arm of the passive tube is turned off later than the switch tube of the upper bridge arm of the first bridge arm of the active tube; Controlling the switch tube of the lower bridge arm of the first bridge arm of the passive tube and the switch tube of the lower bridge arm of the first bridge arm of the active tube to be turned on simultaneously, and the switch tube of the lower bridge arm of the first bridge arm of the passive tube is turned off later than the switch tube of the lower bridge arm of the first bridge arm of the active tube;
[0048] Step S2: Introduce the set voltage as the control variable, fix the variable frequency, and obtain the relationship between the set voltage and the maximum delay time;
[0049] Step S3: performing secondary solutions for the frequency at high frequency, medium frequency and low frequency respectively to obtain the delay time corresponding to the specific frequency under the set voltage, and constructing a control method for the resonant conversion circuit with the set voltage and frequency as control variables.
[0050] As an example, a pulse width modulation (PWM) signal is used to control the switching states of the passive transistors and the active transistors.
[0051] In step S1, please refer to Figure 3 In step S1, the switch tube of the lower bridge arm of the second bridge arm of the passive tube and the switch tube of the upper bridge arm of the first bridge arm of the active tube are controlled to be turned on at the same time, and the switch tube of the lower bridge arm of the second bridge arm of the passive tube is turned off with a delay compared with the switch tube of the upper bridge arm of the first bridge arm of the active tube; the switch tube of the lower bridge arm of the first bridge arm of the passive tube and the switch tube of the lower bridge arm of the first bridge arm of the active tube are controlled to be turned on at the same time, and the switch tube of the lower bridge arm of the first bridge arm of the passive tube is turned off with a delay compared with the switch tube of the lower bridge arm of the first bridge arm of the active tube.
[0052] See also Figure 4 , Figure 4 This is a schematic diagram of the control signal waveforms received by the four switching tubes of the resonant conversion circuit of the present application, wherein the switching tube of the upper bridge arm of the first bridge arm of the active tube receives the control signal P1, the switching tube of the lower bridge arm of the first bridge arm of the active tube receives the control signal P2, the switching tube of the lower bridge arm of the second bridge arm of the passive tube receives the control signal P3, and the switching tube of the lower bridge arm of the first bridge arm of the passive tube receives the control signal P4.
[0053] Next, continue to combine Figure 1 and Figure 4 The working principle of the control method of the resonant conversion circuit of the present application is introduced. The switch tubes of the traditional full-bridge rectifier structure and the full-bridge inverter structure are diagonally cross-conducted, that is, the switch tubes S5, S8, S1 and S4 are turned on at the same time, and the switch tubes S6, S7, S2 and S3 are turned on at the same time; after adopting the control method of the present application, the switch tube S4 of the lower bridge arm of the second bridge arm of the passive tube and the switch tube S5 of the upper bridge arm of the first bridge arm of the active tube are controlled to be turned on at the same time, and the switch tube S4 of the lower bridge arm of the second bridge arm of the passive tube is delayed in turning off than the switch tube S5 of the upper bridge arm of the first bridge arm of the active tube. In one control cycle, there is a moment when the switch tubes S2, S3 and S4 are turned on at the same time. At this time, the second bridge arm of the passive tube and the resistor R o The circuit is short-circuited.
[0054] Furthermore, the switch tube S2 of the lower bridge arm of the first bridge arm of the passive tube and the switch tube S6 of the lower bridge arm of the first bridge arm of the active tube are controlled to be turned on at the same time. The switch tube S2 of the lower bridge arm of the first bridge arm of the passive tube is turned off later than the switch tube S6 of the lower bridge arm of the first bridge arm of the active tube. In one control cycle, there is a moment when the switch tubes S1, S2 and S4 are turned on at the same time. At this time, the first bridge arm of the passive tube and the resistor R o The circuit is short-circuited.
[0055] At the moment of short circuit, the secondary current tends to increase sharply, causing the primary current to tend to increase sharply. According to the law of electromagnetic induction of inductance, the inductor Lr will generate a reverse induced voltage to hinder the current mutation. At the same time, energy is stored in the inductor Lr. When this energy is subsequently released, it helps the resonant conversion circuit resonate, enhances the energy transfer efficiency, and improves the gain of the resonant conversion circuit.
[0056] As an example, the control signal is received by the switch tube so that Figure 4 Gray overlapping areas are generated on both sides of the on and off of the control signal P4 received by the switch tube S2 of the lower bridge arm of the first bridge arm of the passive transistor and the control signal P3 received by the switch tube S4 of the lower bridge arm of the second bridge arm of the passive transistor. When the switch tube S4 of the lower bridge arm of the second bridge arm of the passive transistor is turned off later than the switch tube S5 of the upper bridge arm of the first bridge arm of the active transistor, the control signals P3 and P4 generate overlapping areas 31 to 3M (not shown in the figure). The overlapping areas 31 to 3M are within a control cycle. o The circuit is short-circuited.
[0057] Furthermore, when the switch tube S2 of the lower bridge arm of the first bridge arm of the passive tube is turned off later than the switch tube S6 of the lower bridge arm of the first bridge arm of the active tube, the control signals P3 and P4 generate overlapping areas 41 to 4M (not shown in the figure). The overlapping areas 41 to 4M are within the first bridge arm of the passive tube and the resistor R in one control cycle. o The circuit is short-circuited.
[0058] The method of delay control by short-circuiting on both sides of the switch tube control signal during on and off does not generate excessive delay to cause hard switching of the switch tube, while increasing the gain range of the resonant conversion circuit and protecting the components of the resonant conversion circuit.
[0059] Figure 2 The working principle of the specific embodiment is Figure 1 The same as in , no further description is given here.
[0060] In step S2, please refer to Figure 3 In step S2, the set voltage is introduced as the control variable, the variable frequency is fixed, and the relationship between the set voltage and the maximum delay time is obtained.
[0061] As an example, the output voltage V out The set voltage is used as the control variable of the delay control, and a binary function of the delay time with respect to the set voltage and frequency is constructed, which is expressed as follows:
[0062] T 延时 =F(set voltage, frequency)
[0063] Furthermore, the variable frequency is fixed to obtain the relationship between the maximum delay time and the set voltage.
[0064] In one embodiment of the present application, the output voltage V out The output voltage is 36V. Using the method provided in this application for delay control by short-circuiting the on and off sides of the switch control signal, the output voltage regulation range reaches 10% of the original output voltage within a short delay time without damaging the device, that is, the maximum output voltage is 40V. The relationship between the maximum delay time and the set voltage is expressed as follows:
[0065] T 最大延时 =0.25×set voltage value-9
[0066] Among them, T 最大延时 Indicates the maximum delay time in microseconds; set voltage ∈ [36V, 40V], set voltage value ∈ [36, 40]. When the resonant circuit is fully loaded and outputs a maximum output voltage of 40V, both control signals P3 and P4 need to be delayed for 1.0 microsecond.
[0067] In step S3, please refer to Figure 3 In step S3, the frequency is solved twice at high frequency, medium frequency, and low frequency respectively to obtain the delay time corresponding to the specific frequency under the set voltage, and a control method for the resonant converter circuit is constructed with the set voltage and frequency as control variables.
[0068] As an example, the load characteristics of the resonant conversion circuit determine that high frequency (160KHz~140KHz) represents light load, while low frequency (110KHz~65KHz) represents full load; in the delay control of the resonant conversion circuit, under light load conditions, there is basically no need to delay to increase the gain of the resonant conversion circuit, while under full load conditions, a longer delay is required to increase the gain of the resonant conversion circuit.
[0069] As an example, the relationship between the maximum delay time and frequency for high frequency, medium frequency (140KHz to 110KHz), and low frequency is shown as follows:
[0070] high frequency:
[0071] IF:
[0072] Low frequency:
[0073] Among them, T 延时 represents the delay time in microseconds. At high frequencies, the frequency is [140 kHz, 160 kHz], and the frequency value is [140, 160]. At medium frequencies, the frequency is [110 kHz, 140 kHz], and the frequency value is [110, 140]. At low frequencies, the frequency is [65 kHz, 110 kHz], and the frequency value is [65, 110]. Furthermore, based on the relationship between the maximum delay time and the set voltage, a control method for a resonant converter circuit with the set voltage and frequency as control variables is obtained.
[0074] In one embodiment of the present application, the output voltage V out The set voltage is 38V, and the maximum delay time is 0.5 microseconds. Under the high frequency of 150KHz and full load conditions, to obtain the set voltage of 38V, the control signal P3 and the control signal P4 must be delayed for 0.015 microseconds. Under the medium frequency of 120KHz, to obtain the set voltage of 38V, the control signal P3 and the control signal P4 must be delayed for 0.07 microseconds. Under the low frequency of 80KHz and light load conditions, to obtain the set voltage of 38V, the control signal P3 and the control signal P4 must be delayed for 0.315 microseconds.
[0075] The present application also provides a resonant conversion circuit that executes the control method of the resonant conversion circuit as described above.
[0076] As an example, the resonant conversion circuit includes a primary-side conversion module, a resonant conversion module and a secondary-side conversion module; the primary-side conversion module, the resonant conversion module and the secondary-side conversion module are connected in sequence; the secondary-side conversion module adopts a full-bridge rectifier structure.
[0077] The switch tube of the secondary side conversion module is a passive tube. The two switch tubes close to one end of the resonant conversion module constitute the first bridge arm of the passive tube; the two switch tubes far from one end of the resonant conversion module constitute the second bridge arm of the passive tube.
[0078] The switch tube of the primary side conversion module is called an active tube. The two switch tubes far away from one end of the resonant conversion module constitute the first bridge arm of the active tube; the two switch tubes close to one end of the resonant conversion module constitute the second bridge arm of the active tube.
[0079] The control method and resonant conversion circuit of the present application perform delay control on both sides of the opening and closing of the lower bridge arm of the passive tube, so that the time of overlapping conduction of the control signals of the switch tubes of the lower bridge arm of the two passive tubes is doubled, and the energy storage of the inductor Lr is increased, thereby improving the gain of the resonant conversion circuit, expanding the voltage regulation range, and meeting the output requirements. At the same time, delay control is performed on both sides of the opening and closing of the lower bridge arm of the passive tube, thereby avoiding excessive delay causing hard switching on the switch tube, thereby damaging the device. Furthermore, the problem that delay control only considers the relationship between delay time and frequency is solved, and the set voltage is introduced as a control variable to construct a binary function of the delay time with respect to the set voltage and frequency. The delay time is solved by piecewise linear fitting at three sections: high frequency, medium frequency, and low frequency, thereby improving the control accuracy of the resonant conversion circuit.
[0080] Although the present application has been disclosed above with reference to the embodiments, they are not intended to limit the present application. Anyone with ordinary knowledge in the technical field may make slight changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be determined by the scope of the appended patent application.
Claims
1. A control method for a resonant converter circuit, characterized in that: Applied to a resonant conversion circuit, the resonant conversion circuit includes a primary-side conversion module, a resonant conversion module and a secondary-side conversion module; the primary-side conversion module, the resonant conversion module and the secondary-side conversion module are connected in sequence; The control method of the resonant conversion circuit includes: The switch tube of the lower bridge arm of the second bridge arm of the passive tube and the switch tube of the upper bridge arm of the first bridge arm of the active tube are controlled to be turned on at the same time, and the switch tube of the lower bridge arm of the second bridge arm of the passive tube is turned off with a time delay compared with the switch tube of the upper bridge arm of the first bridge arm of the active tube; the switch tube of the lower bridge arm of the first bridge arm of the passive tube and the switch tube of the lower bridge arm of the first bridge arm of the active tube are controlled to be turned on at the same time, and the switch tube of the lower bridge arm of the first bridge arm of the passive tube is turned off with a time delay compared with the switch tube of the lower bridge arm of the first bridge arm of the active tube; Introducing the set voltage as the control variable and fixing the variable frequency, we can get the relationship between the set voltage and the maximum delay time. The frequency is solved quadratically at high frequency, medium frequency and low frequency respectively to obtain the relationship between the delay time and the maximum delay time and the frequency, and a control method for the resonant conversion circuit is constructed with the set voltage and frequency as the control variables.
2. The control method of the resonant converter circuit according to claim 1, wherein: The relationship between the set voltage and the maximum delay time is shown as follows: T 最大延时 =0.25×set voltage value-9 Among them, T 最大延时 Indicates the maximum delay time.
3. The control method of the resonant converter circuit according to claim 2, wherein: In the case of high frequency, medium frequency and low frequency, the relationship between the delay time and the maximum delay time and frequency is shown as follows: Among them, T 延时 Indicates the delay time.
4. The control method of the resonant converter circuit according to claim 3, wherein: The calculation is performed using high frequency, medium frequency or low frequency according to the load characteristics of the resonant conversion circuit.
5. The control method of the resonant converter circuit according to claim 1, wherein: The pulse width modulation signal is used to control the switching state of the passive tube and the active tube, and the switch tube controls the delayed shutdown time according to the control signal.
6. A resonant converter circuit, executing the control method of the resonant converter circuit according to any one of claims 1 to 5, characterized in that: The resonant conversion circuit includes a primary-side conversion module, a resonant conversion module and a secondary-side conversion module; the primary-side conversion module, the resonant conversion module and the secondary-side conversion module are connected in sequence; the first end of the primary-side conversion module is connected to the input voltage, and the second end of the secondary-side conversion module is connected to the output voltage.
7. The resonant converter circuit according to claim 6, wherein: The resonant conversion module includes: a first capacitor, a first inductor and a transformer, and the transformer includes: a primary winding and a secondary winding; the first capacitor, the first inductor and the primary winding are connected in series, and the two ends of the series connection are the first ends of the resonant conversion module; the two ends of the secondary winding are the second ends of the resonant conversion module.
8. The resonant converter circuit according to claim 7, wherein: The secondary side conversion module includes: a first bridge arm of a passive tube and a second bridge arm of a passive tube. The first bridge arm of the passive tube and the second bridge arm of the passive tube are connected in parallel. The two ends of the parallel connection constitute the second end of the secondary side conversion module. The midpoint of the bridge arm of the first bridge arm of the passive tube and the midpoint of the bridge arm of the second bridge arm of the passive tube constitute the first end of the secondary side conversion module.
9. The resonant converter circuit according to claim 7, wherein: The primary side conversion module includes: a first bridge arm of the active transistor and a second bridge arm of the active transistor. The first bridge arm of the active transistor and the second bridge arm of the active transistor are connected in parallel. The two ends of the parallel connection constitute the first end of the primary side conversion module. The midpoint of the bridge arm of the first bridge arm of the active transistor and the midpoint of the bridge arm of the second bridge arm of the active transistor constitute the second end of the primary side conversion module.
10. The resonant converter circuit according to claim 7, wherein: The primary side conversion module includes: a first bridge arm of the active transistor, a first terminal of the first bridge arm of the active transistor and a second terminal of the first bridge arm of the active transistor constitute a first end of the primary side conversion module, and a midpoint of the first bridge arm of the active transistor and the second terminal of the first bridge arm of the active transistor constitute a second end of the primary side conversion module.