A DC-DC isolation conversion power circuit with wide input range and control method thereof

Abstract

The present invention discloses a DC-DC isolation conversion power circuit with a wide input range and a control method thereof, comprising a coupled inductor Sepic circuit and a push-pull isolation circuit. The coupled inductor Sepic circuit comprises a pair of voltage input terminals Vin, a coupled inductor L11-1 and a coupled inductor L11-2 are connected between the pair of voltage input terminals, a polar capacitor C22 is bridged across both ends of the coupled inductor L11-2, two poles of the polar capacitor C22 are connected to a USB power supply terminal Vbus and are connected to a push-pull isolation circuit through the USB power supply terminal Vbus; the push-pull isolation circuit comprises a polar capacitor C1 whose two poles are connected to the USB power supply terminal Vbus, and a transformer T1 is connected to the anode of the polar capacitor C1.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and in particular to a DC-DC isolation conversion power circuit with a wide input range and a control method thereof. Background Art

[0002] With the development of power electronics technology, there are more and more types of power electronic devices with DC output, and the voltage range is getting wider and wider. The popularization and application of DC output power electronic devices has promoted the development of the energy storage industry, effectively meeting the mobility, flexibility and continuity of energy needs, and the market capacity is getting larger and larger. The corresponding energy feedback load needs to be compatible with a wider input voltage range to have greater flexibility and convenience, thereby reducing equipment investment in the aging link and saving customer expenses.

[0003] Currently, most common energy feedback loads that support a wide voltage input range use Figure 1 The Boost circuit with auxiliary winding shown in the figure can achieve a smaller duty cycle change to support a larger gain change, thereby achieving a wide voltage range input, but there is a problem of excessive stress on the diode D1, and it can only boost but not buck. The subsequent DC-DC isolation circuit must use high-voltage devices, which is very costly. Summary of the invention

[0004] In order to overcome the above-mentioned shortcomings, the present invention aims to provide a technical solution that can solve the above-mentioned problems.

[0005] A DC-DC isolation conversion power circuit with wide input range includes a coupled inductor Sepic circuit and a push-pull isolation circuit. The coupled inductor Sepic circuit includes a pair of voltage input terminals Vin, a coupled inductor L11-1 and a coupled inductor L11-2 are connected between the pair of voltage input terminals, a polar capacitor C22 is connected across the two ends of the coupled inductor L11-2, a USB power supply terminal Vbus is connected to the two poles of the polar capacitor C22, and the USB power supply terminal Vbus is connected to the push-pull isolation circuit.

[0006] The push-pull isolation circuit includes a polar capacitor C1 with two poles connected to the USB power supply terminal Vbus, and a transformer T1 is connected to the anode of the polar capacitor C1. The transformer T1 includes a transformer primary T1-1 and a transformer primary T1-2 connected in parallel to the anode of the polar capacitor C1, and a transformer secondary T1-3 which forms a transformer with the transformer primary T1-1 and the transformer primary T1-2. The two ends of the transformer secondary T1-3 are respectively connected to a capacitor C3 and a coupled inductor L1-1 to form a resonant network, and the transformer secondary T1-3 is connected to a voltage output terminal Vout through the resonant network.

[0007] Furthermore, a diode D11 is connected between the anode of the polar capacitor C22 and the coupling inductor L11 - 2 , and the cathode of the diode D11 is connected to the anode of the polar capacitor C22 .

[0008] Furthermore, a capacitor C33 is connected between the coupling inductor L11-1 and the coupling inductor L11-2, a polar capacitor C11 is connected across the voltage input terminal Vin, an anode of the polar capacitor C11 is connected to the coupling inductor L11-1, and a MOS switch Q11 is connected between the capacitor C33 and the cathode of the polar capacitor C11.

[0009] Further, a polar capacitor C2 is connected across both ends of the voltage output terminal in the push-pull isolation circuit, a diode D1 is connected between the anode of the polar capacitor C2 and the coupling inductor L1-1, and a diode D3 is connected between the anode of the polar capacitor and the capacitor C3, wherein the cathodes of the diode D1 and the diode D3 are both connected to the anode of the polar capacitor C3;

[0010] A diode D2 is connected between the cathode of the polar capacitor C2 and the coupling inductor L1 - 1 , and a diode D4 is connected between the cathode of the polar capacitor and the capacitor C3 , wherein the anodes of the diode D1 and the diode D3 are both connected to the cathode of the polar capacitor C3 .

[0011] Furthermore, the turns ratio of the coupled inductor L11 - 1 and the coupled inductor L11 - 2 is 1:1.

[0012] A control method for a wide-range input DC-DC isolation conversion power circuit is applied to the above-mentioned wide-range input DC-DC isolation conversion power circuit, comprising the following steps:

[0013] S1: According to the voltage relationship between the voltage input terminal Vin and the USB power supply terminal Vbus in the coupled inductor Sepic circuit:

[0014]

[0015] Among them, Vbus is the voltage at the USB power supply terminal Vbus,

[0016] Vin is the voltage at the voltage input terminal Vin,

[0017] D is the duty cycle of MOS start Q11,

[0018] Setting the voltage threshold at the voltage input terminal Vin;

[0019] S2: Establish a frequency-gain relationship chart of the push-pull isolation circuit, and select the operating frequency fs of the push-pull isolation circuit according to the voltage required by the voltage output terminal Vout.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the patent of the present invention adopts a combination of a coupled inductor Sepic circuit and an improved push-pull isolation circuit, and Sepic can realize the buck-boost function, and there is no need to set the Sepic output voltage Vbus to be greater than the maximum input voltage, so there is no need to use high-voltage devices, which reduces costs. At the same time, a control method of changing the Sepic output voltage is adopted to avoid the Sepic circuit working in a state of maximum and minimum duty cycle, achieve good dynamic characteristics and efficiency, and reduce the design difficulty of the drive circuit. The improved push-pull isolation circuit realizes soft switching technology by introducing a resonant network, reduces switching losses, improves conversion efficiency, and eliminates the original output inductor, controlling costs.

[0021] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0023] Figure 1 It is a circuit schematic diagram of the coupled inductor Sepic circuit in the present invention.

[0024] Figure 2 It is a circuit principle diagram of the push-pull isolation circuit in the present invention.

[0025] Figure 3 This is a frequency-gain relationship chart of the push-pull isolation circuit in the present invention. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] See also Figure 1-2A DC-DC isolation conversion power circuit with a wide input range includes a coupled inductor Sepic circuit and a push-pull isolation circuit. The coupled inductor Sepic circuit includes a pair of voltage input terminals Vin, a coupled inductor L11-1 and a coupled inductor L11-2 are connected between the pair of voltage input terminals, a polar capacitor C22 is connected across both ends of the coupled inductor L11-2, a USB power supply terminal Vbus is connected to both poles of the polar capacitor C22, and the USB power supply terminal Vbus is connected to the push-pull isolation circuit.

[0028] The push-pull isolation circuit includes a polar capacitor C1 with two poles connected to the USB power supply terminal Vbus, and a transformer T1 is connected to the anode of the polar capacitor C1. The transformer T1 includes a transformer primary T1-1 and a transformer primary T1-2 connected in parallel to the anode of the polar capacitor C1, and a transformer secondary T1-3 which forms a transformer with the transformer primary T1-1 and the transformer primary T1-2. The two ends of the transformer secondary T1-3 are respectively connected to a capacitor C3 and a coupled inductor L1-1 to form a resonant network, and the transformer secondary T1-3 is connected to a voltage output terminal Vout through the resonant network.

[0029] Furthermore, a diode D11 is connected between the anode of the polar capacitor C22 and the coupling inductor L11 - 2 , and the cathode of the diode D11 is connected to the anode of the polar capacitor C22 .

[0030] Furthermore, a capacitor C33 is connected between the coupling inductor L11-1 and the coupling inductor L11-2, a polar capacitor C11 is connected across the voltage input terminal Vin, an anode of the polar capacitor C11 is connected to the coupling inductor L11-1, and a MOS switch Q11 is connected between the capacitor C33 and the cathode of the polar capacitor C11.

[0031] Further, a polar capacitor C2 is connected across both ends of the voltage output terminal in the push-pull isolation circuit, a diode D1 is connected between the anode of the polar capacitor C2 and the coupling inductor L1-1, and a diode D3 is connected between the anode of the polar capacitor and the capacitor C3, wherein the cathodes of the diode D1 and the diode D3 are both connected to the anode of the polar capacitor C3;

[0032] A diode D2 is connected between the cathode of the polar capacitor C2 and the coupling inductor L1 - 1 , and a diode D4 is connected between the cathode of the polar capacitor and the capacitor C3 , wherein the anodes of the diode D1 and the diode D3 are both connected to the cathode of the polar capacitor C3 .

[0033] Furthermore, the turns ratio of the coupled inductor L11 - 1 and the coupled inductor L11 - 2 is 1:1.

[0034] A control method for a wide-range input DC-DC isolation conversion power circuit is applied to the above-mentioned wide-range input DC-DC isolation conversion power circuit, comprising the following steps:

[0035] S1: According to the voltage relationship between the voltage input terminal Vin and the USB power supply terminal Vbus in the coupled inductor Sepic circuit:

[0036] Vbus=D / (1-D)Vin

[0037] Among them, Vbus is the voltage at the USB power supply terminal Vbus,

[0038] Vin is the voltage at the voltage input terminal Vin,

[0039] D is the duty cycle of MOS start Q11,

[0040] Setting the voltage threshold at the voltage input terminal Vin;

[0041] S2: Establish the frequency-gain relationship chart of the push-pull isolation circuit (such as Figure 3 As shown), the operating frequency fs of the push-pull isolation circuit is selected according to the voltage required by the voltage output terminal Vout.

[0042] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A DC-DC isolation conversion power circuit with wide input range, characterized in that: The coupled inductor Sepic circuit includes a pair of voltage input terminals Vin, a coupled inductor L11-1 and a coupled inductor L11-2 are connected between the pair of voltage input terminals, a polar capacitor C22 is connected across the two ends of the coupled inductor L11-2, a USB power supply terminal Vbus is connected to the two poles of the polar capacitor C22, and the push-pull isolation circuit is connected to the USB power supply terminal Vbus through the USB power supply terminal Vbus; The push-pull isolation circuit includes a polar capacitor C1 with two poles connected to the USB power supply terminal Vbus, a transformer T1 is connected to the anode of the polar capacitor C1, and the transformer T1 includes a transformer primary T1-1 and a transformer primary T1-2 connected in parallel to the anode of the polar capacitor C1, and a transformer secondary T1-3 which forms a transformer with the transformer primary T1-1 and the transformer primary T1-2, and the two ends of the transformer secondary T1-3 are respectively connected to a capacitor C3 and a coupling inductor L1-1 to form a resonant network, and the transformer secondary T1-3 is connected to a voltage output terminal Vout through the resonant network; A diode D11 is connected between the anode of the polar capacitor C22 and the coupling inductor L11-2, and the cathode of the diode D11 is connected to the anode of the polar capacitor C22; A capacitor C33 is connected between the coupling inductor L11-1 and the coupling inductor L11-2, a polar capacitor C11 is connected across both ends of the voltage input terminal Vin, an anode of the polar capacitor C11 is connected to the coupling inductor L11-1, and a MOS switch Q11 is connected between the capacitor C33 and the cathode of the polar capacitor C11; A polar capacitor C2 is connected across both ends of the voltage output terminal in the push-pull isolation circuit, a diode D1 is connected between the anode of the polar capacitor C2 and the coupling inductor L1-1, and a diode D3 is connected between the anode of the polar capacitor and the capacitor C3, wherein the cathodes of the diode D1 and the diode D3 are both connected to the anode of the polar capacitor C3; A diode D2 is connected between the cathode of the polar capacitor C2 and the coupling inductor L1 - 1 , and a diode D4 is connected between the cathode of the polar capacitor and the capacitor C3 , wherein the anodes of the diode D1 and the diode D3 are both connected to the cathode of the polar capacitor C3 .

2. A DC-DC isolation conversion power circuit with wide input range according to claim 1, characterized in that: The turns ratio of the coupled inductor L11 - 1 and the coupled inductor L11 - 2 is 1:

1.

3. A control method for a wide-range input DC-DC isolation conversion power circuit, applied to a wide-range input DC-DC isolation conversion power circuit as claimed in any one of claims 1 to 2, characterized in that: The following steps are involved: S1: According to the voltage relationship between the voltage input terminal Vin and the USB power supply terminal Vbus in the coupled inductor Sepic circuit: Among them, Vbus is the voltage at the USB power supply terminal Vbus, Vin is the voltage at the voltage input terminal Vin, D is the duty cycle of MOS start Q11, Setting a voltage threshold at the voltage input terminal Vin; S2: Establish a frequency-gain relationship chart of the push-pull isolation circuit, and select the operating frequency fs of the push-pull isolation circuit according to the voltage required by the voltage output terminal Vout.

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