Control method and control device of non-isolated converter

Abstract

The invention discloses a control method and a control device of a non-isolated converter, the non-isolated converter comprises an energy conversion circuit and a rectification filter circuit, the energy conversion circuit comprises an inverter circuit, a resonance circuit and a coupling circuit; the control method comprises the steps that the duty ratio of a power tube in an inverter circuit is controlled in an inverter circuit control mode, and then the output voltage gain of the non-isolated converter is controlled; when the voltage drop at the two ends of the power tube in the rectification filter circuit is low level, the power tube in the rectification filter circuit is controlled to be switched on, and when the voltage drop at the two ends of the power tube in the rectification filter circuit is about to rise to high level, the power tube in the rectification filter circuit is controlled to be switched off. According to the invention, the soft switching control of the non-isolated converter can be realized, and the turn-on loss and peak stress of the power tube are reduced, so that the model selection difficulty and material cost of the power tube are greatly reduced, the power conversion efficiency and reliability of the converter are improved, and the device localization is facilitated.

Description

Technical Field

[0001] The present invention relates to the field of switched-mode power supplies, and particularly to a control method and a control device for a non-isolated converter. Background Art

[0002] With the rapid growth of energy consumption in data centers, the problems of high multi-stage energy conversion loss and poor flexibility and controllability of power supply conversion in traditional AC power supply systems for data centers have become increasingly prominent. The DC power supply system is an important development direction for the energy supply system of data centers due to its advantages of fast and flexible control, high system efficiency, and large power supply capacity.

[0003] With the improvement of the computing power of server GPUs, data centers have higher requirements for power efficiency, power density, and the response speed of transient current to reduce energy consumption and improve computing power. To meet the application requirements, the isolation requirements between the input voltage and the secondary output voltage of the DC-DC power converter have been cancelled in some application scenarios. This concession enables some isolated converter topologies to be modified and applied to non-isolated scenarios, and at the same time

[0004] the performance of the converter can be greatly improved on the original basis.

[0005] However, since the current non-isolated topology modified from the isolated converter topology usually uses hard-switching control, when the power density is increased, device loss and temperature rise become the biggest limiting points for the application of the solution. Summary of the Invention

[0006] In view of the technical defects of the existing hybrid bridge converters, the technical problem to be solved by the present invention is to provide a control method and a control device for a non-isolated converter, which can reduce the device loss and temperature rise of the converter and improve the converter efficiency and power density without adding extra devices.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a control method for a non-isolated converter, the non-isolated converter including an energy conversion circuit and a rectifier filter circuit, the energy conversion circuit including an inverter circuit, a resonant circuit, and a coupling circuit;

[0009] The first end of the inverter circuit is connected to the first end of the resonant circuit, the second end of the resonant circuit is connected to the first end of the coupling circuit, the second end of the inverter circuit is connected to the second end of the coupling circuit, the third end of the inverter circuit, the third end of the coupling circuit are connected to the first end of the rectifier filter circuit, the fourth end of the inverter circuit, the fourth end of the coupling circuit are connected to the second end of the rectifier filter circuit, and the fifth end of the inverter circuit, the third end of the rectifier filter circuit are connected to the power ground.

[0010] The control method includes:

[0011] Controlling the duty cycle of the power tubes in the inverter circuit through an inverter circuit control method, thereby controlling the output voltage gain of the non-isolated converter; wherein, the inverter circuit control method includes frequency conversion control, fixed-frequency phase-shift control, fixed-frequency complementary PWM control or fixed-frequency same pulse-width PWM control;

[0012] When the voltage drop across the power tubes in the rectifier and filter circuit is at a low level, control the power tubes in the rectifier and filter circuit to turn on, and when the voltage drop across the power tubes in the rectifier and filter circuit is about to rise to a high level, control the power tubes in the rectifier and filter circuit to turn off.

[0013] Optionally, when the inverter circuit includes a full-bridge circuit, the inverter circuit includes an input filter capacitor Cin, power tubes S1, S2, S5, and S6;

[0014] The negative pole of the input power supply Vin, the first end of the input filter capacitor Cin are connected to the fifth end of the inverter circuit, the second end of the input filter capacitor Cin, the first end of the power tube S1, and the first end of the power tube S5 are connected to the positive pole of the input power supply Vin, the second end of the power tube S1, the first end of the power tube S2 and the second end of the inverter circuit are connected, and the second end of the power tube S2 and the third end of the inverter circuit are connected; the second end of the power tube S5, the first end of the power tube S6 and the first end of the inverter circuit are connected, and the second end of the power tube S6 and the fourth end of the inverter circuit are connected;

[0015] Wherein, the power tubes S5 and S2 are both first main power tubes, and the power tubes S6 and S1 are both second main power tubes.

[0016] Optionally, when the inverter circuit includes a half-bridge circuit, the inverter circuit includes an input filter capacitor Cin, capacitors C1, C2, power tubes S5, and S6;

[0017] The negative electrode of the input power supply Vin, the first terminal of the input filter capacitor Cin are connected to the fifth terminal of the inverter circuit. The second terminal of the input filter capacitor Cin, the first terminal of the capacitor C1, and the first terminal of the power transistor S5 are connected to the positive electrode of the input power supply Vin. The second terminal of the capacitor C1, the first terminal of the capacitor C2, and the second terminal of the inverter circuit are connected. The second terminal of the capacitor C2 and the third terminal of the inverter circuit are connected. The second terminal of the power transistor S5, the first terminal of the power transistor S6, and the first terminal of the inverter circuit are connected. The second terminal of the power transistor S6 and the fourth terminal of the inverter circuit are connected.

[0018] Among them, the power transistor S5 is the first main power transistor, and the power transistor S6 is the second main power transistor.

[0019] Optionally, when the inverter circuit adopts variable frequency control, the driving duty cycles of the first main power transistor and the second main power transistor are equal, the duty cycles of the first main power transistor and the second main power transistor are both less than 50%, the duty cycles of the first main power transistor and the second main power transistor are 180° out of phase, and the driving of the first main power transistor and the second main power transistor has a dead time.

[0020] When it is necessary to increase the output voltage gain of the non-isolated converter, the driving frequencies of the first main power transistor and the second main power transistor decrease; when it is necessary to decrease the output voltage gain of the non-isolated converter, the driving frequencies of the first main power transistor and the second main power transistor increase.

[0021] Optionally, when the inverter circuit adopts fixed-frequency phase-shifted control, the duty cycles of the power transistor S1 and the power transistor S2 are equal and less than 50%, and the duty cycles of the power transistor S1 and the power transistor S2 are 180° out of phase; the duty cycles of the power transistor S5 and the power transistor S6 are equal and less than 50%, and the duty cycles of the power transistor S5 and the power transistor S6 are 180° out of phase; there is a phase difference between the power transistor S1 and the power transistor S6, and the phase difference is variable.

[0022] Optionally, when the inverter circuit adopts fixed-frequency complementary PWM control, the duty cycles of the power transistor S1 and the power transistor S5 are less than 50%, the duty cycles of the power transistor S1 and the power transistor S5 are 180° out of phase, and the driving of the power transistor S1 and the power transistor S5 has a dead time; the driving of the power transistor S2 is complementary to the driving of the power transistor S1, and the driving of the power transistor S6 is complementary to the driving of the power transistor S5;

[0023] When it is necessary to increase the output voltage gain of the non-isolated converter, increase the duty cycle of the power transistor S1 and the duty cycle of the power transistor S5; when it is necessary to decrease the output voltage gain of the non-isolated converter, decrease the duty cycle of the power transistor S1 and the duty cycle of the power transistor S5.

[0024] Optionally, when the inverter circuit adopts fixed-frequency and same-pulse-width PWM control, the duty cycle of the first main power transistor and the duty cycle of the second main power transistor are less than 50%, the duty cycle of the first main power transistor and the duty cycle of the second main power transistor have a phase difference of 180°, and there is a dead time in the driving of the first main power transistor and the second main power transistor;

[0025] When it is necessary to increase the output voltage gain of the non-isolated converter, increase the duty cycle of the first main power transistor and the duty cycle of the second main power transistor; when it is necessary to decrease the output voltage gain of the non-isolated converter, decrease the duty cycle of the first main power transistor and the duty cycle of the second main power transistor.

[0026] In a second aspect, the present invention also provides a control method for a non-isolated converter, the non-isolated converter including an energy conversion circuit and a rectifier filter circuit, and the energy conversion circuit including an inverter circuit and a coupling circuit;

[0027] The first end of the inverter circuit is connected to the first end of the coupling circuit, the second end of the inverter circuit is connected to the second end of the coupling circuit, the third end of the inverter circuit, the third end of the coupling circuit and the first end of the rectifier filter circuit are connected, the fourth end of the inverter circuit, the fourth end of the coupling circuit and the second end of the rectifier filter circuit are connected, and the fifth end of the inverter circuit, the third end of the rectifier filter circuit and the power ground are connected.

[0028] The control method includes:

[0029] Controlling the duty cycle of the power transistors in the inverter circuit through an inverter circuit control method, thereby controlling the output voltage gain of the non-isolated converter; wherein, the inverter circuit control method includes fixed-frequency phase-shifted control, fixed-frequency complementary PWM control or fixed-frequency same-pulse-width PWM control

[0030] When the voltage drop across the power transistor in the rectifier filter circuit is at a low level, control the power transistor in the rectifier filter circuit to turn on, and when the voltage drop across the power transistor in the rectifier filter circuit is about to rise to a high level, control the power transistor in the rectifier filter circuit to turn off.

[0031] In a third aspect, the present invention further provides a control device for a non-isolated converter. The non-isolated converter includes an energy conversion circuit and a rectifier filter circuit. The energy conversion circuit includes an inverter circuit, a resonant circuit, and a coupling circuit;

[0032] A first end of the inverter circuit is connected to a first end of the resonant circuit, a second end of the resonant circuit is connected to a first end of the coupling circuit, a second end of the inverter circuit is connected to a second end of the coupling circuit, a third end of the inverter circuit, a third end of the coupling circuit, and a first end of the rectifier filter circuit are connected, a fourth end of the inverter circuit, a fourth end of the coupling circuit, and a second end of the rectifier filter circuit are connected, and a fifth end of the inverter circuit, a third end of the rectifier filter circuit, and a power ground are connected.

[0033] The control device includes:

[0034] An inverter control unit for controlling the duty cycle of a power transistor in the inverter circuit by an inverter circuit control method, thereby controlling the output voltage gain of the non-isolated converter; wherein, the inverter circuit control method includes frequency conversion control, fixed-frequency phase-shifted control, fixed-frequency complementary PWM control, or fixed-frequency same pulse-width PWM control;

[0035] A rectifier control unit for controlling a power transistor in the rectifier filter circuit to turn on when the voltage drop across the power transistor in the rectifier filter circuit is at a low level, and controlling the power transistor in the rectifier filter circuit to turn off when the voltage drop across the power transistor in the rectifier filter circuit is about to rise to a high level.

[0036] In a fourth aspect, the present invention further provides a control device for a non-isolated converter. The non-isolated converter includes an energy conversion circuit and a rectifier filter circuit. The energy conversion circuit includes an inverter circuit and a coupling circuit;

[0037] A first end of the inverter circuit is connected to a first end of the coupling circuit, a second end of the inverter circuit is connected to a second end of the coupling circuit, a third end of the inverter circuit, a third end of the coupling circuit, and a first end of the rectifier filter circuit are connected, a fourth end of the inverter circuit, a fourth end of the coupling circuit, and a second end of the rectifier filter circuit are connected, and a fifth end of the inverter circuit, a third end of the rectifier filter circuit, and a power ground are connected.

[0038] The control device includes:

[0039] The inverter control unit is used to control the duty cycle of the power transistors in the inverter circuit through an inverter circuit control method, thereby controlling the output voltage gain of the non-isolated converter; wherein, the inverter circuit control method includes fixed-frequency phase-shift control, fixed-frequency complementary PWM control, or fixed-frequency same-pulse-width PWM control;

[0040] The rectifier control unit is used to control the power transistor in the rectifier filter circuit to turn on when the voltage drop across the power transistor in the rectifier filter circuit is at a low level, and to control the power transistor in the rectifier filter circuit to turn off when the voltage drop across the power transistor in the rectifier filter circuit is about to rise to a high level.

[0041] The working principle of the present invention will be analyzed in combination with specific embodiments and will not be elaborated here. Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] 1) Soft switching of power devices can be achieved, reducing device losses and temperature rise, and improving the efficiency and power density of the converter;

[0043] 2) The peak stress and reverse recovery loss of power devices can be reduced, which is beneficial for the selection of power devices and cost reduction. Description of the Drawings

[0044] Figure 1 It is a schematic block diagram of the resonant type of the non-isolated converter of the present invention;

[0045] Figure 2 It is a schematic block diagram of the non-resonant type of the non-isolated converter of the present invention;

[0046] Figure 3 It is a schematic diagram of the principles of the first, second, and third embodiments of the non-isolated converter of the present invention;

[0047] Figure 4 It is a schematic diagram of the principles of the fourth and fifth embodiments of the non-isolated converter of the present invention;

[0048] Figure 5 It is a timing waveform diagram of the first embodiment of the control method of the non-isolated converter of the present invention;

[0049] Figure 6 It is a timing waveform diagram of the second embodiment of the control method of the non-isolated converter of the present invention;

[0050] Figure 7 It is a timing waveform diagram of the third embodiment of the control method of the non-isolated converter of the present invention;

[0051] Figure 8 It is a timing waveform diagram of the fourth embodiment of the control method of the non-isolated converter of the present invention;

[0052] Figure 9It is the timing waveform diagram of the fifth embodiment of the control method of the non-isolated converter of the present invention;

[0053] Figure 10 It is the timing waveform diagram of the sixth embodiment of the control method of the non-isolated converter of the present invention. Detailed implementation manners

[0054] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0055] The control method of the non-isolated converter of the present invention mainly divides the control objects into two categories: one is a resonant non-isolated converter, including an energy conversion circuit and a rectifying and filtering circuit. The energy conversion circuit includes an inverter circuit, a resonant circuit and a coupling circuit. For the principle block diagram, please refer to Figure 1 Another is a non-resonant converter, including an energy conversion circuit and a rectifying and filtering circuit. The energy conversion circuit includes an inverter circuit and a coupling circuit. For the principle block diagram, please refer to Figure 2 .

[0056] For the resonant non-isolated converter, the inverter circuit can include a full-bridge circuit or a half-bridge circuit. The resonant circuit can be composed of a series connection of an inductor and a capacitor, or can be composed of an inductor. The coupling circuit includes a primary winding of a transformer and a secondary winding of a transformer. The rectifying and filtering circuit can include a full-bridge rectifying circuit, a full-wave rectifying circuit, a double-current rectifying circuit or a voltage-doubling rectifying circuit. When the rectifying and filtering circuit includes full-wave rectification, there is also a fifth terminal in the coupling circuit and a fourth terminal in the rectifying and filtering circuit, which are connected to each other. Embodiments 1 to 3 of the present invention are control methods for resonant non-isolated converters. Taking the inverter circuit including a full-bridge circuit and the rectifying and filtering circuit including a full-bridge rectifying circuit as an example, different control methods of the non-isolated converter of the present invention are described. For the topological principle schematic diagram, please refer to Figure 3 .

[0057] For the non-resonant non-isolated converter, the inverter circuit includes a full-bridge circuit, the coupling circuit includes a primary winding of a transformer and a secondary winding of a transformer, and the rectifying and filtering circuit can include a full-bridge rectifying circuit, a full-wave rectifying circuit, a double-current rectifying circuit or a voltage-doubling rectifying circuit. Embodiments 4 to 6 of the present invention are control methods for non-resonant non-isolated converters. Taking the inverter circuit including a full-bridge circuit and the rectifying and filtering circuit including a full-bridge rectifying circuit as an example in the embodiments, different control methods of the non-isolated converter of the present invention are described. For the topological principle schematic diagram, please refer to Figure 4 .

[0058] The inventive concept of this application is as follows: After controlling the voltage drop across the power device to a low level, it is then turned on through control. Through the control method of the present invention, the power device of the non-isolated converter can achieve soft switching, reduce device losses and temperature rise, improve the efficiency and power density of the converter, and at the same time reduce the peak stress and reverse recovery loss of the power device, which is beneficial to the selection of power devices and cost reduction.

[0059] The first embodiment

[0060] Figure 3 is a schematic diagram of the topological principle of the first embodiment of the present invention. Figure 5 is the control timing and waveform of the switching converter in the first embodiment of the present invention, mainly explaining the variable-frequency control method of the resonant non-isolated converter. Now, in combination with Figure 5 the four stages described for each cycle period (from time t0 to time t4, denoted as T) are explained as follows:

[0061] Stage T0 - T1: At the starting moment T0, the power transistors S2 and S5 are turned off, and at this time, the current ip flowing through the primary winding Np of the transformer is not zero. At the moment of turning off, the voltages across the parasitic capacitances Coss2 of the power transistor S2 and Coss5 of the power transistor S5 are 0V; the voltages across the parasitic capacitances Coss1 of the power transistor S1 and Coss6 of the power transistor S6 are the input voltage Vin. At this time, the current ip flowing through the primary winding Np of the transformer will charge the parasitic capacitances Coss1 and Coss6, causing the voltages across them to gradually decrease from Vin to 0V, and then the power transistors S1 and S6 are turned on. At this time, the power transistors S1 and S6 are turned on with zero voltage and have no turn-on loss. This moment is the moment T1.

[0062] Stage T1 - T2: The power transistors S1 and S6 are turned on, and the input voltage Vin magnetizes the primary winding Np of the transformer. The duty cycles of the power transistors S1 and S6 are equal and less than 50%.

[0063] T2 - T3 stage: At the starting moment T2, the power transistors S1 and S6 are turned off. At this time, the current ip flowing through the primary winding Np of the transformer is not zero. At the moment of turn-off, the voltages across the parasitic capacitances Coss2 of the power transistor S2 and Coss5 of the power transistor S5 are Vin; the voltages across the parasitic capacitances Coss1 of the power transistor S1 and Coss6 of the power transistor S6 are the input voltage 0V. At this time, the current ip flowing through the primary winding Np of the transformer will discharge the parasitic capacitances Coss2 and Coss5, causing the voltages across them to gradually decrease from Vin to 0V, at which time the power transistors S2 and S5 are turned on. At this time, the power transistors S2 and S5 are turned on with zero voltage and have no turn-on loss. This moment is the moment T3.

[0064] T3 - T4 stage: The power transistors S2 and S5 are turned on, and the input voltage Vin magnetizes the primary winding Np of the transformer. The duty cycles of the power transistors S1 and S6 are equal and less than 50%.

[0065] So far, one cycle of the first embodiment of the present invention ends.

[0066] Since there are a resonant capacitor Cr and a resonant inductor Lr in the power loop, when the switching frequencies of the power transistors S1, S6, S2, and S5 change within a certain range, the output voltage gain of the resonant non-isolated converter decreases as the frequency increases. Therefore, the output voltage gain of the resonant non-isolated converter can be adjusted by adjusting the switching frequencies of the power transistors S1, S6, S2, and S5.

[0067] Second Embodiment

[0068] Figure 3 is a schematic diagram of the topological principle of the second embodiment of the present invention. Figure 6 is the control timing and waveform of the switching converter in the second embodiment of the present invention, mainly for explaining the fixed-frequency phase-shift control method of the resonant non-isolated converter. Now, in combination with Figure 6 each cycle (from the moment t0 to the moment t8, denoted as T) of the eight stages will be described as follows:

[0069] T0 - T1 stage: At the starting moment T0, the power transistor S1 is turned on, and the power transistor S6 remains in the on state. The input voltage Vin magnetizes the primary winding Np of the transformer until the moment T1.

[0070] T1 - T2 stage: At the starting moment T1, the power transistor S6 is turned off, and the power transistor S1 remains turned on. At this time, the current ip flowing through the primary winding Np of the transformer is not zero, causing the body diode of the power transistor S5 to conduct. The voltage across the power transistor S5 is the same as its body diode conduction voltage drop and is at a low level. At the moment T2, turn on the power transistor S5, which is zero - voltage turn - on and has no turn - on loss.

[0071] T2 - T3 stage: The power transistors S1 and S5 are in the on state, and the primary current ip of the transformer is gradually decreasing.

[0072] T3 - T4 stage: At the starting moment T3, the power transistor S1 is turned off, and the power transistor S5 remains turned on. At this time, the current path of the primary current ip of the transformer is: power transistor S5 - input voltage Vin - power transistor S4 - power transistor S2 - primary winding Np of the transformer - resonant inductor Lr and resonant capacitor Cr, which causes the body diode of the power transistor S2 to conduct. The voltage across the power transistor S2 is the same as its body diode conduction voltage drop and is at a low level. At the moment T4, turn on the power transistor S2, which is zero - voltage turn - on and has no turn - on loss.

[0073] T4 - T5 stage: The power transistors S2 and S5 are in the on state, and the input voltage Vin magnetizes the primary winding Np of the transformer until the moment T5.

[0074] T5 - T6 stage: At the starting moment T5, the power transistor S5 is turned off, and the power transistor S2 remains turned on. At this time, the current ip flowing through the primary winding Np of the transformer is not zero, causing the body diode of the power transistor S6 to conduct. The voltage across the power transistor S6 is the same as its body diode conduction voltage drop and is at a low level. At the moment T6, turn on the power transistor S6, which is zero - voltage turn - on and has no turn - on loss.

[0075] T6 - T7 stage: The power transistors S2 and S6 are in the on state. At the moment T7, the power transistor S2 is turned off, and the primary current ip of the transformer is gradually decreasing.

[0076] T7 - T8 stage: At the starting moment T7, the power transistor S2 is turned off, and the power transistor S6 remains turned on. At this time, the current path of the primary current ip of the transformer is: power transistor S1 - input voltage Vin - power transistor S3 - power transistor S6 - resonant capacitor Cr, resonant inductor Lr, and primary winding Np of the transformer, which causes the body diode of the power transistor S1 to conduct. The voltage across the power transistor S1 is the same as its body diode conduction voltage drop and is at a low level. At the moment T8, turn on the power transistor S1, which is zero - voltage turn - on and has no turn - on loss.

[0077] Thus, one cycle of the second embodiment of the present invention ends.

[0078] The above-mentioned fixed-frequency phase-shift control method, wherein the driving duty cycles of the power transistors S1 and S2 are equal and less than 50%, and the phase difference is 180°. The driving duty cycles of the power transistors S5 and S6 are equal and less than 50%, and the phase difference is 180°. There is a phase difference between the power transistor S1 and the power transistor S6, and this phase difference is variable.

[0079] When the phase difference between the power transistor S1 and the power transistor S6 is 0° or 360°, that is, the driving rising edge moments of the power transistor S1 and the power transistor S6 are the same, the converter has the maximum output voltage gain. When the phase difference between the power transistor S1 and the power transistor S6 is 180°, that is, the rising edge of the power transistor S1 and the driving falling edge moment of the power transistor S6 are the same, the converter has the minimum output voltage gain.

[0080] The third embodiment

[0081] Figure 3 is a schematic diagram of the topological principle of the third embodiment of the present invention. Figure 7 is the control timing and waveform of the switching converter of the third embodiment of the present invention, mainly for explaining the fixed-frequency phase-shift control method of the resonant non-isolated converter. Now in combination with Figure 7 explain the following eight stages for each cycle period (from the moment t0 to the moment t8, denoted as T): specifically as follows:

[0082] The T0-T1 stage: At the starting moment T0, the power transistor S1 is turned on, and the power transistor S6 remains in the on state. The input voltage Vin magnetizes the primary winding Np of the transformer until the moment T1.

[0083] The T1-T2 stage: At the starting moment T1, the power transistor S1 is turned off, and the power transistor S6 remains in the on state. At this time, the current ip flowing through the primary winding Np of the transformer is not zero, so that the body diode of the power transistor S2 conducts, and the voltage across the power transistor S2 is the same as its body diode conduction voltage drop, which is a low level. At the moment T2, turn on the power transistor S2, which is zero-voltage turn-on and has no turn-on loss.

[0084] The T2-T3 stage: The power transistors S2 and S6 are in the on state, and the primary current ip of the transformer is gradually decreasing..

[0085] The T3-T4 stage: At the starting moment T3, the power transistor S6 is turned off, and the power transistor S2 remains in the on state. At this time, the current ip flowing through the primary winding Np of the transformer is not zero, so that the body diode of the power transistor S5 conducts, and the voltage across the power transistor S5 is the same as its body diode conduction voltage drop, which is a low level. At the moment T4, turn on the power transistor S5, which is zero-voltage turn-on and has no turn-on loss.

[0086] T4 - T5 stage: The power transistors S2 and S5 are in the on state, and the input voltage Vin magnetizes the primary winding Np of the transformer until time T5.

[0087] T5 - T6 stage: At the starting time T5, the power transistor S5 turns off, and the power transistor S2 remains in the on state. At this time, the current ip flowing through the primary winding Np of the transformer is not zero, causing the body diode of the power transistor S6 to conduct. The voltage across the power transistor S6 is the same as the conduction voltage drop of its body diode and is at a low level. At time T6, the power transistor S6 is turned on, which is a zero - voltage turn - on with no turn - on loss.

[0088] T6 - T7 stage: The power transistors S2 and S6 are in the on state. At time T7, the power transistor S2 turns off, and the primary current ip of the transformer is gradually decreasing.

[0089] T7 - T8 stage: At the starting time T7, the power transistor S2 turns off, and the power transistor S6 remains in the on state. At this time, the current loop of the primary current ip of the transformer is: power transistor S1 - input voltage Vin - power transistor S3 - power transistor S6 - resonant capacitor Cr, resonant inductor Lr, and primary winding Np of the transformer, which causes the body diode of the power transistor S1 to conduct. The voltage across the power transistor S1 is the same as the conduction voltage drop of its body diode and is at a low level. At time T8, the power transistor S1 is turned on, which is a zero - voltage turn - on with no turn - on loss.

[0090] Thus, one cycle of the third embodiment of the present invention ends.

[0091] In the above - mentioned fixed - frequency complementary PWM control method, the driving duty cycles of the power transistors S1 and S5 are less than 50%, with a phase difference of 180°. The driving of the power transistors S1 and S5 has a dead time. The driving of the power transistor S2 is complementary to that of the power transistor S1, and the driving of the power transistor S6 is complementary to that of the power transistor S5.

[0092] When it is necessary to increase the output voltage gain of the converter, the duty cycles of the power transistors S1 and S5 increase; when it is necessary to decrease the output voltage gain of the converter, the duty cycles of the power transistors S1 and S5 decrease.

[0093] Fourth Embodiment

[0094] Figure 4 This is the schematic diagram of the topological principle of the fourth embodiment of the present invention. Figure 8 This is the control timing and waveform of the switching converter in the fourth embodiment of the present invention, mainly explaining the fixed - frequency phase - shift control method for non - resonant non - isolated converters.

[0095] The working principle of the fourth embodiment is the same as that of the second embodiment. The difference is that the second embodiment includes a resonant capacitor Cr and a resonant inductor Lr, and the waveform of the current ip flowing through the primary winding Np of the transformer is different from that of the fourth embodiment, so it will not be elaborated here.

[0096] Fifth Embodiment

[0097] Figure 4 This is a schematic diagram of the topological principle of the fifth embodiment of the present invention. Figure 9 This is the control timing and waveform of the switching converter of the fifth embodiment of the present invention, mainly explaining the fixed-frequency complementary PWM control method for the non-resonant non-isolated converter.

[0098] The working principle of the fifth embodiment is the same as that of the third embodiment. The difference is that the third embodiment includes a resonant capacitor Cr and a resonant inductor Lr, and the waveform of the current ip flowing through the primary winding Np of the transformer is different from that of the fifth embodiment, so it will not be elaborated here.

[0099] Sixth Embodiment

[0100] Figure 4 This is a schematic diagram of the topological principle of the sixth embodiment of the present invention. Figure 10 This is the control timing and waveform of the switching converter of the sixth embodiment of the present invention, mainly explaining the fixed-frequency phase-shift control method for the non-resonant non-isolated converter. Now, in combination with Figure 10 the following four stages of each cycle period (from time t0 to time t4, denoted as T) will be described in detail as follows:

[0101] T0 - T1 stage: At the starting moment T0, the power transistor S1 and the power transistor S6 are turned on. At this time, the input voltage Vin magnetizes the primary winding Np of the transformer until the moment T1.

[0102] T1 - T2 stage: At the starting moment T2, the power transistor S1 and the power transistor S6 are turned off. The current ip flowing through the primary winding Np of the transformer begins to decrease and stabilizes at 0A.

[0103] T2 - T3 stage: At the starting moment T2, the power transistor S2 and the power transistor S5 are turned on. At this time, the input voltage Vin magnetizes the primary winding Np of the transformer until the moment T3.

[0104] T3 - T4 stage: At the starting moment T3, the power transistor S2 and the power transistor S5 are turned off. The current ip flowing through the primary winding Np of the transformer begins to decrease and stabilizes at 0A.

[0105] So far, a cycle of the first embodiment of the present invention ends. Since the current ip flowing through the primary winding Np of the transformer is not clamped during the dead zone, the soft turn-on of the primary power transistor cannot be achieved by this scheme. However, its advantage lies in the simple control scheme, where the drivers of power transistors S1 and S6 are the same, the drivers of power transistors S2 and S5 are the same, and the driving phases of power transistors S1 and S5 differ by 180°.

[0106] When it is necessary to increase the output voltage gain of the converter, the duty cycles of power transistors S1 and S5 increase; when it is necessary to decrease the output voltage gain of the converter, the duty cycles of power transistors S1 and S5 decrease.

[0107] The above are only the preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be regarded as limiting the present invention, and the protection scope of the present invention should be subject to the scope defined by the claims. For those of ordinary skill in the art, several improvements and refinements can be made without departing from the spirit and scope of the present invention, and these improvements and refinements should also be regarded as within the protection scope of the present invention.

Claims

1. A control method for a non-isolated converter, characterized in that: The non-isolated converter includes an energy conversion circuit and a rectifying and filtering circuit. The energy conversion circuit includes an inverter circuit, a resonant circuit, and a coupling circuit; The first end of the inverter circuit is connected to the first end of the resonant circuit, the second end of the resonant circuit is connected to the first end of the coupling circuit, the second end of the inverter circuit is connected to the second end of the coupling circuit, the third end of the inverter circuit, the third end of the coupling circuit are connected to the first end of the rectifying and filtering circuit, the fourth end of the inverter circuit, the fourth end of the coupling circuit are connected to the second end of the rectifying and filtering circuit, and the fifth end of the inverter circuit, the third end of the rectifying and filtering circuit are connected to the power ground. The control method includes: Controlling the duty cycle of the power transistors in the inverter circuit through an inverter circuit control method, thereby controlling the output voltage gain of the non-isolated converter; wherein, the inverter circuit control method includes frequency conversion control, fixed-frequency phase-shift control, fixed-frequency complementary PWM control, or fixed-frequency same pulse-width PWM control; When the voltage drop across the power transistor in the rectifying and filtering circuit is at a low level, controlling the power transistor in the rectifying and filtering circuit to turn on, and when the voltage drop across the power transistor in the rectifying and filtering circuit is about to rise to a high level, controlling the power transistor in the rectifying and filtering circuit to turn off.

2. The control method of a non-isolated converter according to claim 1, characterized in that: When the inverter circuit includes a full-bridge circuit, the inverter circuit includes an input filter capacitor Cin, power transistors S1, S2, S5, and S6; The negative pole of the input power supply Vin, the first end of the input filter capacitor Cin are connected to the fifth end of the inverter circuit, the second end of the input filter capacitor Cin, the first end of the power transistor S1, the first end of the power transistor S5 are connected to the positive pole of the input power supply Vin, the second end of the power transistor S1, the first end of the power transistor S2 are connected to the second end of the inverter circuit, and the second end of the power transistor S2 is connected to the third end of the inverter circuit; the second end of the power transistor S5, the first end of the power transistor S6 are connected to the first end of the inverter circuit, and the second end of the power transistor S6 is connected to the fourth end of the inverter circuit; Wherein, the power transistors S5 and S2 are both first main power transistors, and the power transistors S6 and S1 are both second main power transistors.

3. The control method of a non-isolated converter according to claim 1, wherein: When the inverter circuit includes a half-bridge circuit, the inverter circuit includes an input filter capacitor Cin, capacitors C1, C2, power transistors S5, and S6; The negative electrode of the input power supply Vin, the first terminal of the input filter capacitor Cin are connected to the fifth terminal of the inverter circuit. The second terminal of the input filter capacitor Cin, the first terminal of the capacitor C1, and the first terminal of the power transistor S5 are connected to the positive electrode of the input power supply Vin. The second terminal of the capacitor C1, the first terminal of the capacitor C2, and the second terminal of the inverter circuit are connected. The second terminal of the capacitor C2 and the third terminal of the inverter circuit are connected; The second terminal of the power transistor S5, the first terminal of the power transistor S6, and the first terminal of the inverter circuit are connected. The second terminal of the power transistor S6 and the fourth terminal of the inverter circuit are connected. Among them, the power transistor S5 is the first main power transistor, and the power transistor S6 is the second main power transistor.

4. The control method of a non-isolated converter according to claim 2 or 3, characterized in that: When the inverter circuit adopts variable frequency control, the driving duty cycles of the first main power transistor and the second main power transistor are equal. The duty cycles of the first main power transistor and the second main power transistor are both less than 50%, and the duty cycles of the first main power transistor and the second main power transistor are out of phase by 180°. The driving of the first main power transistor and the second main power transistor has a dead time. When it is necessary to increase the output voltage gain of the non-isolated converter, the driving frequencies of the first main power transistor and the second main power transistor decrease; when it is necessary to decrease the output voltage gain of the non-isolated converter, the driving frequencies of the first main power transistor and the second main power transistor increase.

5. A control method for a non-isolated converter according to claim 2 or 3, characterized in that: When the inverter circuit adopts fixed-frequency phase-shifted control, the duty cycles of the power transistor S1 and the power transistor S2 are equal and less than 50%, and the duty cycles of the power transistor S1 and the power transistor S2 are out of phase by 180°; The duty cycles of the power transistor S5 and the power transistor S6 are equal and less than 50%, and the duty cycles of the power transistor S5 and the power transistor S6 are out of phase by 180°; There is a phase difference between the power transistor S1 and the power transistor S6, and the phase difference is variable.

6. The control method of a non-isolated converter according to claim 2 or 3, characterized in that: When the inverter circuit adopts fixed-frequency complementary PWM control, the duty cycles of the power transistor S1 and the power transistor S5 are less than 50%, and the duty cycles of the power transistor S1 and the power transistor S5 are out of phase by 180°. The driving of the power transistor S1 and the power transistor S5 has a dead time; The driving of the power transistor S2 is complementary to the driving of the power transistor S1, and the driving of the power transistor S6 is complementary to the driving of the power transistor S5; When it is necessary to increase the output voltage gain of the non-isolated converter, increase the duty cycles of the power transistor S1 and the power transistor S5; when it is necessary to decrease the output voltage gain of the non-isolated converter, decrease the duty cycles of the power transistor S1 and the power transistor S5.

7. The control method of a non-isolated converter according to claim 2 or 3, characterized in that: When the inverter circuit adopts fixed-frequency and same-pulse-width PWM control, the duty cycles of the first main power transistor and the second main power transistor are less than 50%, the duty cycles of the first main power transistor and the second main power transistor are 180° out of phase, and there is a dead time in the driving of the first main power transistor and the second main power transistor; When it is necessary to increase the output voltage gain of the non-isolated converter, increase the duty cycles of the first main power transistor and the second main power transistor; when it is necessary to reduce the output voltage gain of the non-isolated converter, reduce the duty cycles of the first main power transistor and the second main power transistor.

8. A control method for a non-isolated converter, characterized in that: The non-isolated converter includes an energy conversion circuit and a rectifier filter circuit, and the energy conversion circuit includes an inverter circuit and a coupling circuit; The first end of the inverter circuit is connected to the first end of the coupling circuit, the second end of the inverter circuit is connected to the second end of the coupling circuit, the third end of the inverter circuit, the third end of the coupling circuit are connected to the first end of the rectifier filter circuit, the fourth end of the inverter circuit, the fourth end of the coupling circuit are connected to the second end of the rectifier filter circuit, and the fifth end of the inverter circuit, the third end of the rectifier filter circuit are connected to the power ground. The control method includes: Controlling the duty cycle of the power transistor in the inverter circuit through an inverter circuit control method, thereby controlling the output voltage gain of the non-isolated converter; wherein, the inverter circuit control method includes fixed-frequency phase-shifted control, fixed-frequency complementary PWM control or fixed-frequency same-pulse-width PWM control When the voltage drop across the power transistor in the rectifier filter circuit is at a low level, control the power transistor in the rectifier filter circuit to turn on, and when the voltage drop across the power transistor in the rectifier filter circuit is about to rise to a high level, control the power transistor in the rectifier filter circuit to turn off.

9. A control device for a non-isolated converter, characterized in that, The non-isolated converter includes an energy conversion circuit and a rectifier filter circuit, and the energy conversion circuit includes an inverter circuit, a resonant circuit and a coupling circuit; The first end of the inverter circuit is connected to the first end of the resonant circuit, the second end of the resonant circuit is connected to the first end of the coupling circuit, the second end of the inverter circuit is connected to the second end of the coupling circuit, the third end of the inverter circuit, the third end of the coupling circuit are connected to the first end of the rectifier filter circuit, the fourth end of the inverter circuit, the fourth end of the coupling circuit are connected to the second end of the rectifier filter circuit, and the fifth end of the inverter circuit, the third end of the rectifier filter circuit are connected to the power ground. The control device includes: An inverter control unit for controlling the duty cycle of the power transistor in the inverter circuit through an inverter circuit control method, thereby controlling the output voltage gain of the non-isolated converter; wherein, the inverter circuit control method includes variable-frequency control, fixed-frequency phase-shifted control, fixed-frequency complementary PWM control or fixed-frequency same-pulse-width PWM control; A rectification control unit, which is used to control the power tube in the rectification and filtering circuit to turn on when the voltage drop across the power tube in the rectification and filtering circuit is at a low level, and to control the power tube in the rectification and filtering circuit to turn off when the voltage drop across the power tube in the rectification and filtering circuit is about to rise to a high level.

10. A control device for a non-isolated converter, characterized in that, The non-isolated converter includes an energy conversion circuit and a rectification and filtering circuit, and the energy conversion circuit includes an inverter circuit and a coupling circuit; The first end of the inverter circuit is connected to the first end of the coupling circuit, the second end of the inverter circuit is connected to the second end of the coupling circuit, the third end of the inverter circuit, the third end of the coupling circuit are connected to the first end of the rectification and filtering circuit, the fourth end of the inverter circuit, the fourth end of the coupling circuit are connected to the second end of the rectification and filtering circuit, and the fifth end of the inverter circuit, the third end of the rectification and filtering circuit are connected to the power ground. The control device includes: An inverter control unit, which is used to control the duty cycle of the power tube in the inverter circuit through an inverter circuit control method, so as to control the output voltage gain of the non-isolated converter; wherein, the inverter circuit control method includes fixed-frequency phase-shift control, fixed-frequency complementary PWM control or fixed-frequency same-pulse-width PWM control; A rectification control unit, which is used to control the power tube in the rectification and filtering circuit to turn on when the voltage drop across the power tube in the rectification and filtering circuit is at a low level, and to control the power tube in the rectification and filtering circuit to turn off when the voltage drop across the power tube in the rectification and filtering circuit is about to rise to a high level.

Images