Direct current conversion circuit

Abstract

The invention provides a DC conversion circuit, which comprises a DC power supply and a Boost converter, and is characterized in that the Boost converter comprises a high-frequency transformer T1, a chopper power switch S1, a follow current power switch S2, a power MOSFET S3, a DC capacitor C1 and a load resistor R1; the high-frequency transformer T1 is respectively connected with the chopping power switch S1 and the follow current power switch S2, and the high-frequency transformer T1 comprises a primary side winding W1 and a secondary side winding W2; the chopping power switch S1 is used for controlling charging of a primary side winding W1 of the high-frequency transformer T1; the follow current power switch S2 is used for providing a follow current loop for a primary side winding W1 of the high-frequency transformer T1, and the chopping power switch S1 and the follow current power switch S2 are connected and disconnected in a complementary mode. According to the invention, the high-frequency transformer is introduced to continuously supply power to the load resistor, the output ripple is reduced, the boost capability of the Boost converter is improved, and the precision of the output voltage is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of power electronic converters, and in particular, to a DC conversion circuit. Background Art

[0002] The boost converter (Boost converter) is one of the typical DC-DC converters, and its boost inductor is located on the input side, playing the role of storing and transferring energy. When the chopping power switch is turned on, the power supply voltage is entirely applied to the boost inductor, and the inductor current linearly increases, storing energy in the inductor, and the output-side capacitor supplies power to the load; when the chopping power switch is turned off, the inductor current flows through the diode to the output side, and the power supply power and the inductor energy are transferred to the load and the capacitor, storing energy in the capacitor.

[0003] As the most basic DC-DC converter, the Boost converter has been widely studied and applied, and many new converter topologies have been derived. However, the working principle of the Boost converter results in a large ripple in its output voltage. When the chopping power switch is turned on, the output-side diode current is zero, and the load current is provided by the capacitor; when the chopping power switch is turned off, the diode current suddenly rises to the maximum value and then starts to linearly decrease, providing current to the capacitor and the load. If all the ripple components of the diode current flow through the capacitor and the average value of the diode current flows through the load, the capacitor will experience charge and discharge phenomena during the above-mentioned switch-on and switch-off processes, resulting in output voltage pulsation and unable to provide a stable DC voltage as a precision power supply. Summary of the Invention

[0004] Aiming at the deficiencies in the prior art, the purpose of the present disclosure is to provide a DC conversion circuit.

[0005] To achieve the above object, according to one aspect of the present disclosure, a DC conversion circuit is provided, including:

[0006] A DC power supply and a Boost converter, the DC power supply is connected to the Boost converter, and the DC power supply is used to provide a DC voltage;

[0007] The Boost converter includes a high-frequency transformer T1, a chopping power switch S1, a freewheeling power switch S2, a power MOSFET S3, a DC capacitor C1, and a load resistor R1;

[0008] The high-frequency transformer T1 is respectively connected to the chopping power switch S1 and the freewheeling power switch S2. The high-frequency transformer T1 includes a primary winding W1 and a secondary winding W2, and the high-frequency transformer T1 is used to supply energy to the load resistor R1;

[0009] The chopping power switch S1 is used to control the charging of the primary winding W1 of the high-frequency transformer T1;

[0010] The chopping power switch S1 and the freewheeling power switch S2 cooperate to provide a freewheeling circuit for the primary winding W1 of the high-frequency transformer T1.

[0011] Optionally, one end of the primary winding W1 of the high-frequency transformer T1 is connected to the opposite-named end of the secondary winding W2.

[0012] Optionally, the switching states of the chopping power switch S1 and the freewheeling power switch S2 are complementary.

[0013] Optionally, one end of the primary winding W1 of the high-frequency transformer T1 is respectively connected to the positive pole of the DC power supply, the opposite-named end of the secondary winding W2, and the cathode of the chopping power switch S1. The other end of the primary winding W1 of the high-frequency transformer T1 is respectively connected to the anode of the chopping power switch S1 and the cathode of the freewheeling power switch S2. The anode of the freewheeling power switch S2 is respectively connected to the negative pole of the DC power supply, the negative pole of the DC capacitor C1, and the grounding end of the load resistor R1. The other end of the secondary winding W2 of the high-frequency transformer T1 is connected to the anode of the power MOSFET S3. The cathode of the power MOSFET S3 is respectively connected to the positive pole of the DC capacitor C1 and the other end of the load resistor R1.

[0014] Optionally, when the freewheeling power switch S2 is turned on, the chopping power switch S1 is turned off, and the input voltage of the DC power supply is applied across the primary winding W1 of the high-frequency transformer T1. The primary winding W1 is charged, and the DC power supply and the secondary winding W2 are used to supply power to the DC capacitor C1 and the load resistor R1.

[0015] Optionally, when the freewheeling power switch S2 is turned off, the chopping power switch S1 is turned on, the primary winding W1 of the high-frequency transformer T1 freewheels through the chopping power switch S1, the power MOSFET S3 is turned on, and the DC power supply and the secondary winding W2 are used to supply power to the DC capacitor C1 and the load resistor R1.

[0016] In a second aspect of the present disclosure, a DC conversion circuit is provided, including: an AC power supply, a diode rectification circuit, and a Boost circuit. The AC power supply is connected to the diode rectification circuit, and the diode rectification circuit is connected to the Boost circuit. The AC power supply is used to provide an AC voltage, and the diode rectification circuit is used to convert the AC voltage into a DC voltage;

[0017] The Boost circuit includes a high-frequency transformer T1, a chopping power switch S1, a freewheeling power switch S2, a load resistor R1, a diode D5, a DC capacitor C1, and a load resistor R1. The Boost circuit is used to boost the input voltage and output a voltage.

[0018] Optionally, the diode rectifier circuit includes diodes D1, D2, D3, D4, a filter inductor L1, a filter capacitor C2, and a pull-down resistor R2.

[0019] Optionally, one end of the filter inductor L1 is connected to the live wire L of the AC power supply. The other end of the filter inductor L1 is respectively connected to one end of the filter capacitor C2, the anode of the diode D1, and the cathode of the diode D2. The other end of the filter capacitor C2 is respectively connected to the neutral wire N of the AC power supply, the anode of the diode D3, and the cathode of the diode D4.

[0020] The cathode of the diode D1 is connected to the cathode of the diode D3, and the anode of the diode D2 is connected to the anode of the diode D4.

[0021] One end of the pull-down resistor R2 is respectively connected to the cathode of the diode D1 and the cathode of the diode D3 to form the output positive terminal. The other end of the pull-down resistor R2 is respectively connected to the anode of the diode D2 and the anode of the diode D4 to form the output negative terminal.

[0022] Optionally, one end of the primary-side winding W1 of the high-frequency transformer T1 is connected to the output positive terminal of the diode rectifier circuit, the opposite-named end of the secondary-side winding W2, and the cathode of the freewheeling power switch S2. The other end of the primary-side winding W1 of the high-frequency transformer T1 is respectively connected to the anode of the freewheeling power switch S2 and the cathode of the chopping power switch S1. The anode of the chopping power switch S1 is respectively connected to the output negative terminal of the diode rectifier circuit, the negative electrode of the DC capacitor C1, and the grounded end of the load resistor R1. The other end of the secondary-side winding W2 of the high-frequency transformer T1 is connected to the anode of the diode D5. The cathode of the diode D5 is respectively connected to the positive electrode of the DC capacitor C1 and the other end of the load resistor R1.

[0023] Compared with the prior art, the embodiments of the present disclosure have at least one of the following beneficial effects:

[0024] Through the above technical solution, a high-frequency transformer T1 is introduced into the DC conversion circuit, the traditional Boost converter is improved, the voltage boosting ability of the Boost transformer is enhanced, a larger power load can be driven, the Buck converter is integrated, the chopping power switch S1 is used to control the charging of the primary winding W1 of the high-frequency transformer T1, and the chopping power switch S1 and the freewheeling power switch S2 are used in cooperation to provide a freewheeling circuit for the primary winding W1 of the high-frequency transformer T1, so as to realize continuous power supply to the load resistor R1, thereby reducing the output current ripple, effectively suppressing the output voltage ripple, realizing high-precision voltage output, and moreover, the freewheeling circuit can also effectively reduce the conduction loss and harmonic current, improve the working efficiency and reduce the electromagnetic interference. The circuit structure is simple, the performance is excellent, and it has a wide application. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other features, objects, and advantages of the present disclosure will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0026] Figure 1 FIG. is a schematic diagram of the circuit topology structure of a DC conversion circuit shown according to an exemplary embodiment.

[0027] Figure 2 FIG. is a schematic diagram of the circuit structure of the simulation verification of a traditional Boost converter circuit and the DC conversion circuit of the present disclosure shown according to an exemplary embodiment.

[0028] Figure 3 FIG. is a schematic diagram of the circuit topology structure of another DC conversion circuit shown according to an exemplary embodiment.

[0029] Figure 4 FIG. is a schematic diagram of the circuit structure of the simulation verification of another DC conversion circuit shown according to an exemplary embodiment.

[0030] FIG. 5 is a waveform schematic diagram of the diode current waveform and the output voltage waveform of a traditional Boost converter and an improved Boost converter under the same turns ratio shown according to an exemplary embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The present disclosure will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present disclosure, but do not limit the present disclosure in any form. It should be noted that those of ordinary skill in the art can make several modifications and improvements without departing from the concept of the present disclosure. These all belong to the protection scope of the present disclosure.

[0032] Figure 1 FIG. is a schematic diagram of the circuit topology structure of a DC conversion circuit shown according to an exemplary embodiment. Figure 2It is a schematic diagram of a simulation verification circuit structure of a traditional Boost converter circuit and the DC conversion circuit of the present disclosure shown according to an exemplary embodiment.

[0033] As Figure 1 、 Figure 2 shown, the present disclosure provides a DC conversion circuit, including a DC power supply u i and a Boost converter. The DC power supply u i is connected to the Boost converter, and the DC power supply u i is used to provide a DC voltage.

[0034] The Boost converter includes a high-frequency transformer T1, a chopping power switch S1, a freewheeling power switch S2, power MOSFETS3, a DC capacitor C1, and a load resistor R1.

[0035] Among them, the chopping power switch S1 can adopt switch types such as power MOSFET.

[0036] The Boost converter of the present disclosure is a Boost converter improved from a traditional Boost converter.

[0037] The high-frequency transformer T1 is respectively connected to the chopping power switch S1 and the freewheeling power switch S2. The high-frequency transformer T1 includes a primary winding W1 and a secondary winding W2, and the high-frequency transformer T1 is used to supply energy to the load resistor R1.

[0038] The chopping power switch S1 is used to control the charging of the primary winding W1 of the high-frequency transformer T1.

[0039] The chopping power switch S1 and the freewheeling power switch S2 cooperate to work to provide a freewheeling circuit for the primary winding W1 of the high-frequency transformer T1.

[0040] Compared with the freewheeling circuit composed of a diode, the cooperation of the chopping power switch S1 and the freewheeling power switch S2 can effectively reduce the conduction loss and harmonic current, improve the working efficiency of the circuit and reduce the electromagnetic interference.

[0041] Through the above technical solution, a high-frequency transformer T1 is introduced into the DC conversion circuit, the traditional Boost converter is improved, the boosting ability of the Boost transformer is enhanced, a larger-power load can be driven, the Buck converter is integrated, the chopping power switch S1 is used to control the charging of the primary winding W1 of the high-frequency transformer T1, and the chopping power switch S1 and the freewheeling power switch S2 cooperate to provide a freewheeling circuit for the primary winding W1 of the high-frequency transformer T1, so as to realize continuous power supply to the load resistor R1, thereby reducing the output current ripple, effectively suppressing the output voltage ripple, achieving high-precision voltage output, and moreover, the freewheeling circuit can also effectively reduce the conduction loss and harmonic current, improve the working efficiency and reduce the electromagnetic interference. The circuit structure is simple, the performance is excellent, and it has a wide range of applications.

[0042] In a possible embodiment, one end of the primary winding W1 of the high-frequency transformer T1 is connected to the opposite-name end of the secondary winding W2 to realize continuous power supply to the load resistor R1. The primary winding W1 is used as a boosting inductor, and the secondary winding W2 is used to generate an induced current. The high-frequency transformer T1 can supply power to the load resistor R1 both when the switch is on and off.

[0043] In a possible embodiment, the switching states of the chopping power switch S1 and the freewheeling power switch S2 are complementary, one on and one off, that is, when the chopping power switch S1 is on, the freewheeling power switch S2 is off; when the chopping power switch S1 is off, the freewheeling power switch S2 is on.

[0044] Among them, the power MOSFET S3 is triggered to conduct during the operation of the circuit and remains off during the standby of the circuit to realize synchronous rectification and further improve the DC conversion efficiency.

[0045] As Figure 1 shown, the circuit connection relationship of a DC conversion circuit includes:

[0046] One end of the primary winding W1 of the high-frequency transformer T1 is respectively connected to the positive pole of the DC power supply, the opposite-name end of the secondary winding W2, and the cathode of the chopping power switch S1. The other end of the primary winding W1 of the high-frequency transformer T1 is respectively connected to the anode of the chopping power switch S1 and the cathode of the freewheeling power switch S2. The anode of the freewheeling power switch S2 is respectively connected to the negative pole of the DC power supply, the negative pole of the DC capacitor C1, and the grounding end of the load resistor R1. The other end of the secondary winding W2 of the high-frequency transformer T1 is connected to the anode of the power MOSFET S3. The cathode of the power MOSFET S3 is respectively connected to the positive pole of the DC capacitor C1 and the other end of the load resistor R1.

[0047] In this embodiment, when the freewheeling power switch S2 is turned on, the chopping power switch S1 is turned off, and the input voltage of the DC power supply is applied across both ends of the primary winding W1 of the high-frequency transformer T1. The primary winding W1 is charged, and the DC power supply and the secondary winding W2 are used to supply power to the DC capacitor C1 and the load resistor R1.

[0048] Among them, the primary winding W1 is charged and stores energy, and the current rises. The secondary winding W2 generates an induced voltage and an induced current. When the power MOSFET S3 is turned on, at this time, the DC power supply and the secondary winding W2 are used to supply power to the DC capacitor C1 and the load resistor R1.

[0049] When the freewheeling power switch S2 is turned on, the voltage across both ends of the primary winding W1 is the input voltage u in , and the induced voltage of the secondary winding W2 is:

[0050]

[0051] Since the voltage across both ends of the secondary winding W2 is always clamped to u o -u in , ignoring the resistance of the secondary winding W2, the voltage across the leakage inductance of the secondary winding W2 is:

[0052]

[0053] In this embodiment, when the freewheeling power switch S2 is turned off, the chopping power switch S1 is turned on. The primary winding W1 of the high-frequency transformer T1 freewheels through the chopping power switch S1, the power MOSFET S3 is turned on, and the DC power supply and the secondary winding W2 are used to supply power to the DC capacitor C1 and the load resistor R1.

[0054] Among them, when the freewheeling power switch S2 is turned off and the chopping power switch S1 is turned on, it is approximately a superconducting mode. The current of the primary winding W1 decreases, and the secondary winding W2 generates an induced current through the power MOSFET S3. At this time, the DC power supply and the secondary winding W2 are used to supply power to the DC capacitor C1 and the load resistor R1.

[0055] When the freewheeling power switch S2 is turned off, the voltage across both ends of the primary winding W1 is approximately zero, the induced voltage of the secondary winding W2 is zero, and the voltage across the leakage inductance of the secondary winding W is the clamping voltage u o -u in . Applying the volt-second balance principle to the leakage inductance of the secondary winding W2, the boost ratio of the Boost converter of the DC conversion circuit of the present disclosure can be obtained as:

[0056]

[0057] Wherein, D represents the conduction duty ratio of the chopping power switch S1, and n2 / n1 represents the turns ratio of the high-frequency transformer T1.

[0058] It can be obtained from the boost ratio of the Boost converter with an optimized DC circuit that the larger the turns ratio of the high-frequency transformer T1, the stronger the boost ability of the Boost converter; the duty ratio of the chopping power switch S1 affects the boost ability of the Boost converter, and the larger the duty ratio of the chopping power switch S1, the stronger the boost ability of the Boost converter.

[0059] The boost ability of the Boost converter in the DC conversion circuit is jointly determined by the turns ratio n2 / n1 of the high-frequency transformer T1 and the duty ratio D of the chopping power switch S1. Compared with having n2 / n1 traditional Buck converters connected in series with the DC output voltage, its boost ratio is:

[0060]

[0061] Therefore, the improved Boost converter topology can improve the boost ability by using high-frequency transformers with different turns ratios.

[0062] A DC conversion circuit provided by the present disclosure, in which the chopping power switch S1 and the freewheeling power switch S2 conduct and turn off complementarily. When the secondary winding W2 of the high-frequency transformer T1 conducts or turns off the chopping power switch S1 and the freewheeling power switch S2, the power MOSFET S3 is always conducting, greatly reducing the output current ripple, effectively suppressing the output voltage ripple, and achieving high-precision voltage output.

[0063] In a possible embodiment, a DC conversion circuit is experimentally set with the following parameters:

[0064] DC input voltage: 12V

[0065] Output voltage reference value: 48V

[0066] Output power: 150W

[0067] High-frequency transformer T1: W1:W2 = 1:5, saturation current 20A;

[0068] DC capacitor C1: 220 μF

[0069] Load resistor R1: 15 Ω

[0070] MOSFET S3: 25A @ 85 °C, 600V

[0071] MOSFET S1~S2: 35A @ 85 °C, 600V

[0072] Switching frequency: 100 kHz.

[0073] Among them, MOSFET S1 represents the chopping power switch S1, and MOSFET S2 represents the freewheeling power switch S2.

[0074] Experiments show that a DC conversion circuit provided by this embodiment can introduce a high-frequency transformer to continuously supply power to a load resistor, reduce the output ripple, improve the boost capability of the Boost converter, and improve the output voltage accuracy.

[0075] Figure 3 It is a schematic diagram of the circuit topology of another DC conversion circuit shown according to an exemplary embodiment. Figure 4 It is a schematic diagram of the simulation verification circuit structure of another DC conversion circuit shown according to an exemplary embodiment.

[0076] Such as Figure 3 、 Figure 4 shown, the present disclosure also provides another DC conversion circuit, including an AC power supply, a diode rectification circuit, and a Boost circuit. The AC power supply is connected to the diode rectification circuit, and the diode rectification circuit is connected to the Boost circuit. The AC power supply is used to provide an AC voltage, and the diode rectification circuit is used to convert the AC voltage into a DC voltage.

[0077] The Boost circuit includes a high-frequency transformer T1, a chopping power switch S1, a freewheeling power switch S2, a load resistor R1, a diode D5, a DC capacitor C1, and a load resistor R1. The Boost circuit is used to boost the input voltage and output a voltage.

[0078] The Boost converter of the present disclosure is a Boost converter improved from a traditional Boost converter.

[0079] Through the above technical solution, a high-frequency transformer T1 is introduced into the DC conversion circuit to improve the traditional Boost converter and enhance the boost capability of the Boost transformer, enabling it to drive a larger-power load. By integrating the Buck converter, the chopping power switch S1 is used to control the charging of the primary winding W1 of the high-frequency transformer T1, and the chopping power switch S1 and the freewheeling power switch S2 cooperate to provide a freewheeling circuit for the primary winding W1 of the high-frequency transformer T1, realizing continuous power supply to the load resistor R1, thereby reducing the output current ripple, effectively suppressing the output voltage ripple, achieving high-precision voltage output. Moreover, the freewheeling circuit can also effectively reduce the conduction loss and harmonic current, improve the working efficiency and reduce the electromagnetic interference. The circuit structure is simple, with excellent performance and wide application.

[0080] In a possible embodiment, the diode rectification circuit includes diodes D1, D2, D3, D4, a filter inductor L1, a filter capacitor C2, and a pull-down resistor R2.

[0081] As Figure 3 shown, the circuit connection relationship of a DC conversion circuit includes:

[0082] One end of the filter inductor L1 is connected to the live wire L of the AC power supply, and the other end of the filter inductor L1 is respectively connected to one end of the filter capacitor C2, the anode of the diode D1, and the cathode of the diode D2. The other end of the filter capacitor C2 is respectively connected to the neutral wire N of the AC power supply, the anode of the diode D3, and the cathode of the diode D4.

[0083] The cathode of the diode D1 is connected to the cathode of the diode D3, and the anode of the diode D2 is connected to the anode of the diode D4.

[0084] Among them, the diodes D1 and D3 are connected in common cathode, and the diodes D2 and D4 are connected in common anode.

[0085] One end of the pull-down resistor R2 is respectively connected to the cathode of the diode D1 and the cathode of the diode D3 to form the output positive terminal, and the other end of the pull-down resistor R2 is respectively connected to the anode of the diode D2 and the anode of the diode D4 to form the output negative terminal.

[0086] One end of the primary side winding W1 of the high-frequency transformer T1 is connected to the output positive terminal of the diode rectifier circuit, the opposite-named end of the secondary side winding W2, and the cathode of the freewheeling power switch S2. The other end of the primary side winding W1 of the high-frequency transformer T1 is respectively connected to the anode of the freewheeling power switch S2 and the cathode of the chopping power switch S1. The anode of the chopping power switch S1 is respectively connected to the output negative terminal of the diode rectifier circuit, the negative electrode of the DC capacitor C1, and the grounded end of the load resistor R1. The other end of the secondary side winding W2 of the high-frequency transformer T1 is connected to the anode of the diode D5, and the cathode of the diode D5 is respectively connected to the positive electrode of the DC capacitor C1 and the other end of the load resistor R1.

[0087] In a possible embodiment, the working principle of a DC conversion circuit includes:

[0088] The diode rectifier circuit rectifies the sinusoidal voltage input from the AC power supply into a sinusoidal half-wave. When the chopping power switch S1 is turned on, the freewheeling power switch S2 is turned off, and the sinusoidal half-wave voltage is applied across the two ends of the primary side winding W1 of the high-frequency transformer T1. The primary side winding W1 charges and stores energy, and the current rises. The secondary side winding W2 generates an induced voltage and an induced current, and supplies current to the DC capacitor C1 and the load resistor R1 through the diode D5. The sinusoidal half-wave voltage and the secondary side winding W2 jointly supply energy to the DC capacitor C1 and the load resistor R1.

[0089] The diode rectifier circuit rectifies the sinusoidal voltage input from the AC power supply into a sinusoidal half-wave voltage. When the chopping power switch S1 is turned off, the freewheeling power switch S2 is turned on, and the primary winding W1 of the high-frequency transformer T1 freewheels through the freewheeling power switch S2, in an approximate superconducting mode. The current in the primary winding W1 decreases, and an induced current is generated in the secondary winding W2, which provides current for the DC capacitor C1 and the load resistor R1 through the diode D5. The input voltage and the secondary winding W2 jointly supply energy to the capacitor C1 and the load resistor R1.

[0090] In this embodiment, the on / off states of the chopping power switch S1 and the freewheeling power switch S2 are determined by a double-closed-loop structure, so as to achieve the same frequency and phase of the input current and the input voltage, and output a stable DC voltage.

[0091] In this embodiment, the boost ratio of the Boost circuit is:

[0092]

[0093] where, n2 / n1 represents the turns ratio of the high-frequency transformer T1, and D ave represents the duty cycle of the chopping power switch S1.

[0094] Thus, the boost capability of the Boost converter in the DC conversion circuit is jointly determined by the turns ratio n2 / n1 of the high-frequency transformer T1 and the duty cycle D of the chopping power switch S1. The larger the turns ratio of the high-frequency transformer T1, the stronger the boost capability of the Boost converter; the duty cycle n2 / n1 of the chopping power switch S1 affects the boost capability of the Boost converter, and the larger the duty cycle D of the chopping power switch S1, ave the stronger the boost capability of the Boost converter. ave

[0095] In this embodiment, the current pulsation flowing through the diode D5 is caused by the on / off states of the chopping power switch S1 and the freewheeling power switch S2. Then, in addition to the characteristic sub-harmonics, the voltage ripple in the output voltage is extremely small, so as to achieve a high-precision output voltage.

[0096] In a possible embodiment, a DC conversion circuit is set up for experiments with the following parameters:

[0097] Single-phase AC input voltage: effective value 220V, power frequency 50Hz

[0098] DC output voltage reference value: 385V

[0099] Output power: 1kW

[0100] Load resistor R1: 148Ω

[0101] DC capacitor C1: 4x680μF

[0102] Filter inductor L1: 0.1 mH

[0103] Filter capacitor C2: 0.47 μF

[0104] Pull - down resistor R2: 50 kΩ

[0105] High - frequency transformer T1: W1:W2 = 1:1, saturation current 10 A

[0106] Diode rectifier D1 - D4: 25 A @ 85 °C, 600 V

[0108] MOSFET S1 - S2: 35 A @ 85 °C, 600 V

[0109] Switching frequency: 40 kHz.

[0110] Among them, MOSFET S1 represents the chopping power switch S1, and MOSFET S2 represents the free - wheeling power switch S2.

[0111] Experiments show that a DC conversion circuit provided in this embodiment can introduce a high - frequency transformer to continuously supply power to the load resistor, reduce the output ripple, improve the boost ability of the Boost converter, and improve the output voltage accuracy.

[0112] Both of the two DC conversion circuits provided above in this disclosure adopt an improved Boost converter. By replacing the boost inductor with a high - frequency transformer T1, the boost ability can be improved and the output voltage ripple can be reduced. A matching free - wheeling circuit and a new connection topology are also designed to enable the secondary winding current of the secondary winding W2 of the high - frequency transformer T1 to supply power to the DC capacitor C1 and the load resistor R2 through the power MOSFET S3 or the diode D5 both when the switch is on and off. The power MOSFET S3 or the diode D5 is in the conducting state, and the current of the power MOSFET S3 or the diode D5 becomes continuous, similar to the power - on situation of the load in a Buck converter, effectively suppressing the output voltage ripple and achieving high - precision voltage output.

[0113] FIG. 5 is a waveform schematic diagram of the diode current waveform and the output voltage waveform of a traditional Boost converter and an improved Boost converter at the same turns ratio according to an exemplary embodiment.

[0114] As shown in FIG. 5, FIG. 5(a) shows a schematic diagram of the diode current waveform of a traditional Boost converter and an improved Boost converter at the same turns ratio; FIG. 5(b) shows a waveform schematic diagram of the output voltage waveform of a traditional Boost converter and an improved Boost converter at the same turns ratio.

[0115] As shown in Fig. 5(a), the current flowing through the diode in the circuit of the traditional Boost converter switches between zero and the inductor discharge current, resulting in a relatively large current ripple. In the improved Boost converter topology provided by the present disclosure, the current flowing through the diode is always the current of the secondary winding W2 of the high-frequency transformer T1. The current ripple is caused by the on / off of the switch and is relatively small.

[0116] As shown in Fig. 5(b), the ripple part of the diode current flows through the DC capacitor C1. After being filtered by the DC capacitor C1 with a relatively large capacitance value, the voltage ripple across both ends is relatively small, and the output voltage is approximately constant. If the turns ratio n2 / n1 of the high-frequency transformer is further reduced, the induced current ripple generated by the secondary winding W2 is even smaller, and the accuracy of the output voltage is further improved.

[0117] The improved Boost converter provided by the present disclosure has a simple circuit structure, excellent performance, clear control idea, and wide application range. It can be applied to scenarios that require high-precision voltage output and have a high boost ratio.

[0118] The specific embodiments of the present disclosure have been described above. It should be understood that the present disclosure is not limited to the above specific embodiments. Those skilled in the art can make various deformations or modifications within the scope of the claims, which do not affect the essence of the present disclosure. The above preferred features can be used in any combination without conflict.

Claims

1. A DC conversion circuit, characterized in that: include: A DC power supply and a Boost converter, wherein the DC power supply is connected to the Boost converter, and the DC power supply is used to provide a DC voltage; The Boost converter includes a high-frequency transformer T1, a chopper power switch S1, a freewheeling power switch S2, a power MOSFET S3, a DC capacitor C1 and a load resistor R1; The high-frequency transformer T1 is connected to the chopper power switch S1 and the freewheeling power switch S2 respectively, and the high-frequency transformer T1 includes a primary winding W1 and a secondary winding W2, and the high-frequency transformer T1 is used to supply energy to the load resistor R1; The chopper power switch S1 is used to control the charging of the primary winding W1 of the high-frequency transformer T1; The chopper power switch S1 and the freewheeling power switch S2 cooperate to provide a freewheeling loop for the primary winding W1 of the high-frequency transformer T1.

2. The DC conversion circuit according to claim 1, characterized in that: One end of the primary winding W1 of the high-frequency transformer T1 is connected to an opposite-name end of the secondary winding W2 .

3. The DC conversion circuit according to claim 2, characterized in that: The switching states of the chopping power switch S1 and the freewheeling power switch S2 are complementary.

4. The DC conversion circuit according to claim 3, characterized in that: One end of the primary winding W1 of the high-frequency transformer T1 is respectively connected to the positive electrode of the DC power supply, the opposite end of the secondary winding W2, and the cathode of the chopper power switch S1; the other end of the primary winding W1 of the high-frequency transformer T1 is respectively connected to the anode of the chopper power switch S1 and the cathode of the freewheeling power switch S2; the anode of the freewheeling power switch S2 is respectively connected to the negative electrode of the DC power supply, the negative electrode of the DC capacitor C1, and the ground end of the load resistor R1; the other end of the secondary winding W2 of the high-frequency transformer T1 is connected to the anode of the power MOSFET S3; the cathode of the power MOSFET S3 is respectively connected to the positive electrode of the DC capacitor C1 and the other end of the load resistor R1.

5. The DC conversion circuit according to claim 4, characterized in that: When the freewheeling power switch S2 is turned on, the chopper power switch S1 is turned off, the input voltage of the DC power supply is applied to both ends of the primary winding W1 of the high-frequency transformer T1, the primary winding W1 is charged, and the DC power supply and the secondary winding W2 are used to power the DC capacitor C1 and the load resistor R1.

6. The DC conversion circuit according to claim 4, characterized in that: When the freewheeling power switch S2 is turned off, the chopper power switch S1 is turned on, the primary winding W1 of the high-frequency transformer T1 is freewheeling through the chopper power switch S1, the power MOSFET S3 is turned on, and the DC power supply and the secondary winding W2 are used to supply power to the DC capacitor C1 and the load resistor R1.

7. A DC conversion circuit, characterized in that: It includes an AC power supply, a diode rectifier circuit and a Boost circuit, wherein the AC power supply is connected to the diode rectifier circuit, the diode rectifier circuit is connected to the Boost circuit, the AC power supply is used to provide an AC voltage, and the diode rectifier circuit is used to convert the AC voltage into a DC voltage; The Boost circuit includes a high-frequency transformer T1, a chopper power switch S1, a freewheeling power switch S2, a load resistor R1, a diode D5, a DC capacitor C1 and a load resistor R1. The Boost circuit is used to boost the input voltage and output the voltage.

8. The DC conversion circuit according to claim 7, characterized in that: The diode rectifier circuit includes a diode D1, a diode D2, a diode D3, a diode D4, a filter inductor L1, a filter capacitor C2 and a pull-down resistor R2.

9. The DC conversion circuit according to claim 8, characterized in that: One end of the filter inductor L1 is connected to the live wire L of the AC power supply, the other end of the filter inductor L1 is respectively connected to one end of the filter capacitor C2, the anode of the diode D1, and the cathode of the diode D2, and the other end of the filter capacitor C2 is respectively connected to the neutral wire N of the AC power supply, the anode of the diode D3, and the cathode of the diode D4; The cathode of the diode D1 is connected to the cathode of the diode D3, and the anode of the diode D2 is connected to the anode of the diode D4; One end of the pull-down resistor R2 is respectively connected to the cathode of the diode D1 and the cathode of the diode D3 to form an output positive electrode, and the other end of the pull-down resistor R2 is respectively connected to the anode of the diode D2 and the anode of the diode D4 to form an output negative electrode.

10. The DC conversion circuit according to claim 9, characterized in that: One end of the primary winding W1 of the high-frequency transformer T1 is connected to the output positive electrode of the diode rectifier circuit, the opposite end of the secondary winding W2, and the cathode of the freewheeling power switch S2. The other end of the primary winding W1 of the high-frequency transformer T1 is respectively connected to the anode of the freewheeling power switch S2 and the cathode of the chopper power switch S1. The anode of the chopper power switch S1 is respectively connected to the output negative electrode of the diode rectifier circuit, the negative electrode of the DC capacitor C1, and the ground end of the load resistor R1. The other end of the secondary winding W2 of the high-frequency transformer T1 is connected to the anode of the diode D5. The cathode of the diode D5 is respectively connected to the positive electrode of the DC capacitor C1 and the other end of the load resistor R1.

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