A non-inductive DC / DC conversion circuit

Abstract

The present invention discloses a non-inductive DC / DC conversion circuit. The circuit includes: a first capacitor, a second capacitor, a third capacitor, a first switch tube, a second switch tube, a third switch tube and a fourth switch tube; the output end of the first switch tube is connected to the input end of the second switch tube; the output end of the second switch tube is connected to the input end of the third switch tube; the output end of the third switch tube is connected to the input end of the fourth switch tube; one end of the first capacitor is connected to the output end of the first switch tube, and the other end of the first capacitor is connected to the output end of the third switch tube; one end of the second capacitor is connected to the input end of the first switch tube, and the other end of the second capacitor and the other end of the third capacitor are both connected to the output end of the second switch tube; one end of the third capacitor is connected to the output end of the fourth switch tube. The non-inductive circuit reduces the weight of the device, takes into account a variety of working conditions by adjusting the on and off of the switch tube, and makes the adjustment and control of the duty cycle of the switch tube simple.

Description

Technical Field

[0001] The invention relates to the technical field of DC / DC converters, and in particular to an inductive DC / DC conversion circuit. Background Art

[0002] DC / DC converters are divided into isolated and non-isolated types. Non-isolated DC / DC converters do not have high-frequency transformers, so the power is not limited by high-frequency transformers. They are small in size and can tolerate high power. When designing non-isolated DC / DC converter circuits, the industry mostly improves and combines Buck circuits and Boost chopper circuits. Unidirectional DC / DC converters are mostly improved on the basis of Buck circuits to achieve step-down, and improved on the basis of Boost circuits to achieve step-up. Bidirectional DC / DC converters can not only maintain the voltage polarity at both ends of the converter unchanged, but also realize the bidirectional flow of DC power. They are widely used in hybrid power systems, new energy power generation and other fields. They are mainly achieved by combining Buck and Boost circuits. Generally, two switch tubes are connected in parallel with diodes and distributed in the upper and lower bridge arms of the converter. The two switch tubes are in complementary working states, corresponding to the forward Boost and reverse Buck circuits, respectively, so as to realize the bidirectional flow of power flow.

[0003] However, the above circuit has the following shortcomings in design: 1. There is an inductor in the circuit. The heavier iron core in the inductor makes the whole device bulky. When applied in a motion system, it will seriously affect the dynamic performance of the whole system; 2. The duty cycle of the switch tube in the circuit is achieved by controlling the PWM signal. A slight change in the duty cycle of the switch tube will affect the change in voltage and current gain. Therefore, the adjustment of the switch tube is more complicated; 3. Most circuit designs are only suitable for one of the boost, buck and bidirectional working conditions, and cannot take into account multiple working conditions, which has certain limitations. Summary of the invention

[0004] In view of the above problems, the present invention provides a non-inductive DC / DC conversion circuit.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A non-inductive DC / DC conversion circuit comprises: a first capacitor, a second capacitor, a third capacitor, a first switch tube, a second switch tube, a third switch tube and a fourth switch tube;

[0007] The output end of the first switch tube is connected to the input end of the second switch tube; the output end of the second switch tube is connected to the input end of the third switch tube; the output end of the third switch tube is connected to the input end of the fourth switch tube;

[0008] One end of the first capacitor is connected to the output end of the first switch tube, and the other end of the first capacitor is connected to the output end of the third switch tube;

[0009] One end of the second capacitor is connected to the input end of the first switch tube, the other end of the second capacitor and the other end of the third capacitor are both connected to the output end of the second switch tube; one end of the third capacitor is connected to the output end of the fourth switch tube.

[0010] Optionally, the first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all in self-locking mode.

[0011] Optionally, when the sensorless DC / DC conversion circuit operates under a step-down condition, the second switch tube and the third switch tube are interlocked and turned on alternately.

[0012] Optionally, when the sensorless DC / DC conversion circuit operates under a boost condition, the first switch tube and the fourth switch tube are interlocked and turned on alternately.

[0013] Optionally, when the inductive DC / DC converter circuit operates under a bidirectional condition, the first switch tube and the third switch tube are synchronized as a group, the second switch tube and the fourth switch tube are synchronized as a group, and the two groups are interlocked and switched on alternately.

[0014] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0015] (1) A non-inductive circuit is designed. There is no inductance in the circuit, which effectively reduces the weight of the device;

[0016] (2) The switch tube is designed in self-locking mode. Only by adopting staggered control with the same duty cycle can the voltage at the high voltage end be basically twice that of the low voltage end, thereby simplifying sampling and control;

[0017] (3) By adjusting the alternating on and off of each switch tube, various operating conditions such as boost, buck, and bidirectional operation are achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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 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.

[0019] Figure 1 Schematic diagram of a sensorless DC / DC converter circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. 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.

[0021] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] like Figure 1 As shown, the inductive DC / DC converter circuit provided by the present invention includes: a first capacitor C1, a second capacitor C2, a third capacitor C3, a first switch tube SIC-1, a second switch tube SIC-2, a third switch tube SIC-3 and a fourth switch tube SIC-4.

[0023] The output end of the first switch tube SIC-1 is connected to the input end of the second switch tube SIC-2; the output end of the second switch tube SIC-2 is connected to the input end of the third switch tube SIC-3; the output end of the third switch tube SIC-3 is connected to the input end of the fourth switch tube SIC-4.

[0024] One end of the first capacitor C1 is connected to the output end of the first switch tube SIC-1, and the other end of the first capacitor C1 is connected to the output end of the third switch tube SIC-3;

[0025] One end of the second capacitor C2 is connected to the input end of the first switch tube SIC-1, and the other end of the second capacitor C2 and the other end of the third capacitor C3 are both connected to the output end of the second switch tube SIC-2; one end of the third capacitor C3 is connected to the output end of the fourth switch tube SIC-4.

[0026] The first switch tube SIC-1, the second switch tube SIC-2, the third switch tube SIC-3 and the fourth switch tube SIC-4 are all in self-locking mode.

[0027] The present invention adopts the method of alternately opening a single switch and alternately opening a group of switches, so that the present invention has the effect of working under different working conditions such as a step-down working condition, a step-up working condition, and a bidirectional working condition.

[0028] Boost working condition:

[0029] SIC-2 and SIC-3 are interlocked and opened alternately. When SIC-2 is turned on, C1 charges C3, and when SIC-3 is turned on, C1 charges C2. Then the voltages of CI, C2, and C3 are basically the same, and the voltage at the high-voltage end is basically twice that of the low-voltage end. When there is a demand for electricity at the high-voltage end, power flows from the low-voltage end to the high-voltage end, and the system is naturally cut off when the high-voltage end is fed;

[0030] Step-down condition:

[0031] SIC-1 and SIC-4 are interlocked and opened alternately. When SIC-1 is turned on, C2 charges C1. When SIC-4 is turned on, C3 charges C1. Then the voltages of CI, C2, and C3 are basically the same, and the voltage at the high-voltage end is basically twice that of the low-voltage end. When there is a demand for electricity at the low-voltage end, power flows from the high-voltage end to the low-voltage end. When the low-voltage end is fed with power, the system is naturally cut off;

[0032] Bidirectional working conditions:

[0033] SIC-1 and SIC-3 form a group of synchronization, and SIC-2 and SIC-4 form a group of synchronization. When the two groups of interlocks are opened alternately, the voltage at the high-voltage end is basically twice that of the low-voltage end, and the power flow can flow in both directions.

[0034] For boost and buck conditions, the present invention adopts a method of alternately opening interlocking switch tubes to charge the capacitor in sequence so that the voltage at the high voltage end is basically twice that at the low voltage end, thereby enabling the present invention to have a boost and buck effect.

[0035] For bidirectional working conditions, the present invention designs a circuit structure so that a group of switch tubes are turned on at the same time, meeting the requirement that the circuit can work in both directions. The present invention also adopts a method of alternately turning on this group of switch tubes and another group of switch tubes, so that the present invention can not only work in both directions, but also has the effect of stepping up and down the voltage.

[0036] The present invention designs a non-inductive circuit, which greatly reduces the weight of the device. By adjusting the on-off of four switch tubes, multiple working conditions such as boost, buck and bidirectional working conditions are taken into account, and the adjustment and control of the duty cycle of the switch tubes become simple.

[0037] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0038] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A non-inductive DC / DC conversion circuit, characterized in that: include: A first capacitor, a second capacitor, a third capacitor, a first switch tube, a second switch tube, a third switch tube and a fourth switch tube; The output end of the first switch tube is connected to the input end of the second switch tube; the output end of the second switch tube is connected to the input end of the third switch tube; the output end of the third switch tube is connected to the input end of the fourth switch tube; One end of the first capacitor is connected to the output end of the first switch tube, and the other end of the first capacitor is connected to the output end of the third switch tube; One end of the second capacitor is connected to the input end of the first switch tube, and the other end of the second capacitor and the other end of the third capacitor are both connected to the output end of the second switch tube; one end of the third capacitor is connected to the output end of the fourth switch tube; When the inductive DC / DC converter circuit works under the step-down condition, the first switch tube and the fourth switch tube are interlocked and turned on alternately; the first switch tube SIC-1 and the fourth switch tube SIC-4 are interlocked and turned on alternately, when SIC-1 is turned on, the second capacitor C2 charges the first capacitor C1, and when SIC-4 is turned on, the third capacitor C3 charges C1, then the voltages of CI, C2, and C3 are consistent, then the voltage at the high-voltage end is twice the voltage at the low-voltage end, when the low-voltage end has a power demand, power flows from the high-voltage end to the low-voltage end, and the system is naturally cut off when the low-voltage end is fed; When the inductive DC / DC converter circuit works under the boost condition, the second switch tube and the third switch tube are interlocked and turned on alternately; the second switch tube SIC-2 and the third switch tube SIC-3 are interlocked and turned on alternately. When SIC-2 is turned on, C1 charges C3, and when SIC-3 is turned on, C1 charges C2. Then, the voltages of CI, C2, and C3 are consistent, and the voltage at the high-voltage end is twice the voltage at the low-voltage end. When the high-voltage end has a power demand, power flows from the low-voltage end to the high-voltage end, and the system is naturally cut off when the high-voltage end is fed with power. When the inductive DC / DC converter circuit operates in a bidirectional condition, the first switch tube and the third switch tube form a group of synchronization, the second switch tube and the fourth switch tube form a group of synchronization, and the two groups are interlocked and opened alternately.

2. The inductive DC / DC converter circuit according to claim 1, characterized in that: The first switch tube, the second switch tube, the third switch tube and the fourth switch tube are all in self-locking mode.

Images