A novel half-bridge unit and its control method

Abstract

The present invention relates to a novel half-bridge unit and a control method thereof, belonging to the field of power electronic converters. The novel half-bridge unit includes two electrically interconnected controllable switch units, each of which is composed of no less than two controllable switch tubes connected in parallel. In each switching cycle of the novel half-bridge unit, the two controllable switch units are alternately turned on, and the controllable switch tubes therein are also alternately turned on accordingly. By using the alternating conduction mode of the novel half-bridge unit, the present invention can increase the equivalent output switching frequency of the converter, reduce the volume of passive components, lower the junction temperature of the switch tube, and improve the power density.

Description

Technical Field

[0001] The invention belongs to the field of power electronic converters and relates to a novel half-bridge unit and a control method thereof. Background Art

[0002] Half-bridge cells are widely used in bidirectional DC-DC converters, single-phase full-bridge converters, and three-phase full-bridge converters. Increasing the switching frequency of the semiconductors in half-bridge cells is the primary means of achieving high power density in power electronic converters. However, due to limitations in the switching speed and switching losses of the semiconductor switching devices, further increases in switching frequency are difficult. Summary of the Invention

[0003] In view of this, the object of the present invention is to provide a novel half-bridge unit and a control method thereof, which are used to replace the half-bridge unit in the power electronic converter, so that the semiconductor device can achieve an increase in the equivalent switching frequency of the power electronic converter at a lower switching frequency.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] Solution 1: A new type of half-bridge unit includes a first controllable switch unit and a second controllable switch unit electrically connected to each other. The first controllable switch unit includes controllable switch tubes Q1 to Q2 connected in parallel. n The second controllable switch unit includes controllable switch tubes connected in parallel The controllable switch tube can be MOSFET or IGBT.

[0006] Alternatively, the new half-bridge unit can be applied to a power electronic converter that already has a half-bridge unit structure, replacing the existing half-bridge unit in the converter with the new half-bridge unit. When the converter contains at least two new half-bridge units, each new half-bridge unit is independently controlled without affecting the other.

[0007] Solution 2: Control method of the new half-bridge unit, specifically:

[0008] In each switching cycle, the first controllable switch unit and the second controllable switch unit are turned on alternately. When the first controllable switch unit or the second controllable switch unit is turned on, only one controllable switch tube therein is turned on, and the controllable switch tubes Q1 to Q n as well as Alternating conduction, the phase difference is π / n, as shown in the following formula:

[0009]

[0010] In the formula, 1 indicates that the controllable switch tube is turned on, and 0 indicates that the controllable switch tube is turned off.

[0011] The beneficial effects of the present invention are:

[0012] (1) When the switching tubes operate at the same switching frequency, the equivalent output switching frequency of the replaced converter is n times that of the converter before replacement (n is the number of switching tubes in parallel), which reduces the volume of passive components and improves the system power density;

[0013] (2) At the same equivalent output switching frequency, the switching frequency of the switching tube of the replaced converter is 1 / n of that of the converter before replacement (n is the number of switching tubes in parallel), which reduces the junction temperature of the switching tube, reduces the volume of the heat sink, and improves the power density.

[0014] Other advantages, objects, and features of the present invention will be described in part in the following description and, in part, will be apparent to those skilled in the art upon examination of the following description or may be learned from practice of the present invention. The objects and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0016] Figure 1 Schematic diagram of the new half-bridge unit structure;

[0017] Figure 2 Schematic diagram of the bidirectional DC-DC converter after replacement;

[0018] Figure 3 To replace the previous bidirectional DC-DC converter simulation model;

[0019] Figure 4 This is the simulation model of the bidirectional DC-DC converter after replacement;

[0020] Figure 5 To replace the previous bidirectional DC-DC converter, the inductor current and U an Simulated waveform of voltage;

[0021] Figure 6 The inductor current and U of the bidirectional DC-DC converter after replacement are shown in Figure 1. an Simulated waveform of voltage;

[0022] Figure 7 This is a circuit diagram of a new half-bridge unit applied to a single-phase full-bridge converter;

[0023] Figure 8 This is the circuit structure diagram of the new half-bridge unit applied to the three-phase full-bridge converter. DETAILED DESCRIPTION

[0024] The following describes the embodiments of the present invention by means of specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0025] Figure 1 The figure shows the structure of the new half-bridge unit of the present invention, which includes two controllable switch units. The first controllable switch unit includes controllable switch tubes Q1 to Q2 connected in parallel. n , Q1~Q n The source terminal and the drain terminal are connected in parallel, and the gate terminal is used to access the control signal; the second controllable switch unit includes The parallel connection mode is consistent with that of the first controllable switch unit.

[0026] The control method of the new half-bridge unit is: in each switching cycle, the first controllable switch unit and the second controllable switch unit are turned on alternately. When the first controllable switch unit or the second controllable switch unit is turned on, only one controllable switch tube therein is turned on, and the controllable switch tubes Q1 to Q n as well as Alternate conduction, phase difference π / n. That is, after Q1 is turned on, is turned on, then Q2 is turned on, then On, Q3, …, Q n-1 , Q n , As shown in the following formula:

[0027]

[0028] In the formula, 1 indicates that the controllable switch tube is turned on, and 0 indicates that the controllable switch tube is turned off.

[0029] The present invention can be applied to power electronic converters such as bidirectional DC-DC converters, single-phase full-bridge converters, and three-phase full-bridge converters. Figure 2 、 7As shown in Figures 8 and 9, replacing the original half-bridge unit in the converter with the new half-bridge unit of the present invention can increase the equivalent output switching frequency of the converter to n times that before replacement (n is the number of parallel switching tubes). When applied to converters requiring two or more half-bridge units, such as single-phase and three-phase full-bridge converters, the control of each new half-bridge unit does not affect each other and is controlled independently. This embodiment uses the replacement of the half-bridge unit in a bidirectional DC-DC converter with the new half-bridge unit of the present invention as an example to illustrate the working principle of the new half-bridge unit.

[0030] like Figure 2 The figure shows a bidirectional DC-DC converter after replacing with a new half-bridge unit. In this bidirectional DC-DC converter, when the controllable switch tubes Q1 to Q n All off, and When any switch is turned on, the voltage U between the bridge arm midpoint a and the DC bus negative pole n is an Equal to 0; when the controllable switch tube Q1 ~ Q n Any one of them is turned on and the controllable switch tube When all are turned off, the voltage U from the bridge arm midpoint a to the DC bus negative pole n is an = is equal to the first DC power supply E1. Therefore, in each switching cycle, the controllable switch tubes Q1 to Q n as well as When the conduction sequence is controlled in the above manner, the voltage U an The voltage jumps from 0 to E1 and from E1 to 0 n times in one switching cycle, that is, the frequency of the voltage is n times the operating frequency of the switch tube. f The current ripple frequency is also n times the operating frequency of the switch tube, and the equivalent switching frequency of the circuit is increased by n times.

[0031] In this embodiment, simulation models of the bidirectional DC-DC converter before and after replacement are built in SIMULINK, as shown in FIG. Figure 3 and Figure 4 As shown, the number of controllable switch tubes in the new half-bridge unit is 4, with two in each of the first and second controllable switch units.

[0032] Under the same simulation parameter conditions, when the switching frequency of the semiconductor switching device of the bidirectional DC-DC converter before replacement is f=10KHz, the inductor current and voltage U an The simulation waveform is as follows Figure 5 As shown in the figure, when the switching frequency of the replaced bidirectional DC-DC converter semiconductor switch device is f=10KHz, the inductor current and voltage U an The simulation waveform is as follows Figure 6 As shown. Figure 5 and Figure 6 It can be seen that, under the same switching frequency, the equivalent output switching frequency of the bidirectional DC-DC converter after replacement is twice that before replacement.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions, which should all be included in the scope of the claims of the present invention.

Claims

1. A new half-bridge unit, characterized by: It includes a first controllable switch unit and a second controllable switch unit electrically connected to each other; the first controllable switch unit includes controllable switch tubes Q1 to Q n , Q1~Q n connected in parallel; the second controllable switch unit includes a controllable switch tube connected in parallel; wherein n≥2; the gate of each controllable switch tube is independently connected to the control signal; In each switching cycle, the first controllable switch unit and the second controllable switch unit are turned on alternately; when the first controllable switch unit or the second controllable switch unit is turned on, only one controllable switch tube therein is turned on, and the controllable switch tubes Q1 to Q n as well as Alternating conduction, the phase difference is π / n, as shown in the following formula: In the formula, 1 means the controllable switch is on, and 0 means the controllable switch is off; The controllable switch tube is MOSFET or IGBT.

2. The novel half-bridge unit according to claim 1, characterized in that: The novel half-bridge unit is applied to a power electronic converter having a half-bridge unit structure.

3. The novel half-bridge unit according to claim 2, characterized in that: When the number of the new half-bridge units in the power electronic converter is not less than two, the controls between the new half-bridge units do not affect each other and are controlled independently.

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