An auxiliary power supply circuit for improving bus bias

Abstract

The application discloses an auxiliary power supply circuit for improving bus bias voltage, and relates to the technical field of power electronic conversion. The auxiliary power supply circuit comprises a positive half bus, a rectifier diode D8, a first winding composed of a transformer T1, a quality factor Q1 and a resistor R1, and constitutes a main circuit of a first reverse flyback power supply; a negative half bus, a second winding composed of a transformer T2, a rectifier diode D2, a quality factor Q2 and a resistor R2, and constitutes a main circuit of a second reverse flyback power supply. In the application, when the auxiliary power supply works, the half bus with higher voltage supplies power and charges the half bus with lower voltage, so that the bus voltage is actively balanced. Furthermore, the capacitor energy of the half bus with higher voltage is utilized, so that the bus bias voltage can be actively improved, and the efficiency of the bus balancing circuit is improved.

Description

Technical Field

[0001] This invention relates to the field of power electronic conversion technology, and more specifically to an auxiliary power supply circuit for improving bus bias. Background Technology

[0002] Three-level circuits are widely used in power electronic conversion fields such as charging piles and inverters. However, whether it is a Vienna rectifier or a T-type or I-type three-level circuit, due to component errors or load imbalance, this type of circuit is prone to imbalance of positive and negative buses, which can easily lead to problems such as poor output accuracy or even overmodulation.

[0003] Moreover, existing bus balancing circuits mostly consume the voltage of the higher-voltage bus directly with resistors, reducing efficiency and lacking the ability to actively balance bus voltage.

[0004] Based on the above, those skilled in the art have designed an auxiliary power supply circuit that can improve bus bias voltage. Furthermore, the auxiliary power supply circuit proposed in this invention achieves active bus voltage balancing by using the higher-voltage half of the bus to supply power and charging the lower-voltage half of the bus during auxiliary operation. This, in turn, improves the bus bias voltage problem in three-level circuits and enhances the efficiency of the bus balancing circuit. Summary of the Invention

[0005] To address the aforementioned deficiencies, the technical problem to be solved by this invention is to provide an auxiliary power supply circuit for improving bus bias, comprising: a first winding consisting of the positive half-section bus, rectifier diode D8, transformer T1, quality factor Q1, and resistor R1 forming the main circuit of a first flyback power supply; and a second winding consisting of the negative half-section bus, transformer T2, rectifier diode D2, quality factor Q2, and resistor R2 forming the main circuit of a second flyback power supply.

[0006] It also includes a third winding and a fourth winding for output winding. The third winding is connected in series with a rectifier diode D4 and a unipolar transistor Q3. This winding is controlled to charge the positive half of the bus. The fourth winding is connected in series with a rectifier diode D5 and a unipolar transistor Q4. This winding is controlled to charge the negative half of the bus.

[0007] This also includes a fifth winding, a sixth winding, and the remaining windings that provide independent power to the system.

[0008] In the above-mentioned technical solution of an auxiliary power supply circuit for improving bus bias, preferably, the parameters of the first winding and the second winding are completely identical.

[0009] In the above-mentioned technical solution of an auxiliary power supply circuit for improving bus bias, preferably, when the positive half-section bus voltage is too high, the first flyback power supply works. Since the first winding and the second winding share a magnetic core, the mutual inductance electromotive force on the second winding is higher than the input voltage, so the second flyback power supply does not work; and the third winding also does not work because the unipolar transistor Q3 is in the off state.

[0010] In the above-mentioned auxiliary power supply circuit for improving bus bias, preferably, the unipolar transistor Q4 in the fourth winding is in the on state, the fourth winding is connected to charge the positive half of the bus, which plays a role in balancing the bus voltage, and the other windings are all working normally.

[0011] In the above-mentioned technical solution of an auxiliary power supply circuit for improving bus bias, preferably, when the negative half-section bus voltage is high, the second flyback power supply works, the mutual inductance electromotive force on the first winding is opposite to the direction of the input voltage and is greater than the voltage, so the first flyback power supply cannot work; and the unipolar transistor Q3 is turned on, the third winding charges the positive half-section bus; the unipolar transistor Q4 is turned off, the fourth winding does not work; and the remaining windings work normally.

[0012] In the above-mentioned auxiliary power supply circuit for improving bus bias, preferably, the bus voltage circuit also includes a capacitor voltage C1 and a capacitor voltage C2 connected in parallel; wherein, when the capacitor voltage C1 is higher than the capacitor voltage C2, the unipolar transistor Q4 is driven, and when the capacitor voltage C2 is higher than the capacitor voltage C1, the unipolar transistor Q3 is driven, thereby charging the lower voltage half of the bus under controlled conditions.

[0013] As can be seen from the above technical solution, the auxiliary power supply circuit for improving bus bias provided by the present invention has the following beneficial effects compared with the prior art:

[0014] During auxiliary power operation, the higher-voltage half of the busbar supplies power and charges the lower-voltage half, thereby achieving active bus voltage balancing. Furthermore, the capacitive energy of the higher-voltage busbar is utilized, thus actively improving bus bias and increasing the efficiency of the bus balancing circuit. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments of the present invention or the prior art will be briefly introduced and explained below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1This is a schematic diagram of the power supply circuit for the positive half-section busbar and the negative half-section busbar.

[0017] Figure 2 This is a schematic diagram of the auxiliary power supply circuit. Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] To provide a clearer explanation and description of the technical solution and implementation of the present invention, several preferred specific embodiments for implementing the technical solution of the present invention are described below.

[0020] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly set on the other component; when a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to the other component.

[0021] Furthermore, the terms "inner" and "outer", "front" and "back", "left" and "right", "vertical" and "horizontal", "top" and "bottom" used in this document to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings are only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0022] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Specific Implementation

[0023] Reference Appendix Figure 1 To be continued Figure 2 ;

[0024] Detailed explanation of the auxiliary power supply circuit for improving bus bias.

[0025] This embodiment includes:

[0026] The first winding, consisting of the positive half busbar, rectifier diode D8, transformer T1, quality factor Q1, and resistor R1, constitutes the main circuit of the first flyback power supply; the second winding, consisting of the negative half busbar, transformer T2, rectifier diode D2, quality factor Q2, and resistor R2, constitutes the main circuit of the second flyback power supply, and the parameters of the first winding and the second winding are completely identical.

[0027] When the positive half-section bus voltage is too high, the first flyback power supply works. Since the first winding and the second winding share a magnetic core, the mutual inductance electromotive force on the second winding is higher than the input voltage, so the second flyback power supply does not work. At this time, the third winding is also not working because the unipolar transistor is in the off state at Q3.

[0028] In the fourth winding, the unipolar transistor Q4 is in the on state. The fourth winding is connected to charge the positive half of the bus, which plays a role in balancing the bus voltage. The other windings are all working normally.

[0029] When the negative half-section bus voltage is too high, the second flyback power supply operates. Similarly, the mutual inductance electromotive force on the first winding is opposite in direction to the input voltage and is greater than the voltage, so the first flyback power supply cannot operate. At this time, unipolar transistor Q3 is turned on, and the third winding charges the positive half-section bus; unipolar transistor Q4 is turned off, and the fourth winding does not operate; the remaining windings operate normally.

[0030] The bus voltage discrimination circuit can be implemented by hardware circuits (such as operational amplifiers and comparators). Its function is to drive unipolar transistor Q4 when the bus capacitor voltage C1 is higher than the capacitor voltage C2, and drive unipolar transistor Q3 when the capacitor voltage C2 is higher than the capacitor voltage C1. Under controlled conditions, it charges the half of the bus with the lower voltage. This method not only improves the bus bias state, but also uses the excess energy to power the system and charges the half of the bus with the lower voltage, which is highly efficient.

[0031] Finally, it should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

[0032] As used herein, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase “comprising one…” does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0033] This invention is not limited to the above-described preferred embodiments. Anyone should know that any structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention.

Claims

1. An auxiliary power supply circuit for improving bus bias voltage, characterized in that, The main circuit of the first flyback power supply consists of: the positive half-section bus DC+, rectifier diode D8, the first winding of transformer T2, diode D1, quality factor Q1, resistor R1, and neutral line N; the main circuit of the second flyback power supply consists of: the negative half-section bus DC-, the second winding of transformer T2, rectifier diode D2, quality factor Q2, resistor R2, diode D10, and neutral line N. It also includes a third winding and a fourth winding for output winding. The third winding is connected in series with a rectifier diode D4 and a unipolar transistor Q3. This winding is controlled to charge the positive half of the bus. The fourth winding is connected in series with a rectifier diode D5 and a unipolar transistor Q4. This winding is controlled to charge the negative half of the bus. The system includes a fifth winding, a sixth winding, and other windings that provide independent power to the system. The parameters of the first winding and the second winding are completely identical. When the voltage of the positive half-section bus is too high, the first flyback power supply operates. Since the first winding and the second winding share a magnetic core, the mutual inductance electromotive force on the second winding is higher than the input voltage, so the second flyback power supply does not operate. The third winding also does not operate because the unipolar transistor Q3 is in the off state. The unipolar transistor Q4 in the fourth winding is in the on state, and the fourth winding is connected to charge the negative half-section bus, which plays a role in balancing the bus voltage. The other windings operate normally. The opposite-named terminal of the third winding is connected to DC+ via diode D4, and the same-named terminal of the third winding is connected to the neutral line N via D3. The opposite-named terminal of the fourth winding is connected to the neutral line N via diodes D5 and Q4, and the same-named terminal of the fourth winding is connected to DC-.

2. The auxiliary power supply circuit for improving bus bias voltage according to claim 1, characterized in that, When the negative half-section bus voltage is too high, the second flyback power supply is working, the mutual inductance electromotive force on the first winding is opposite to the input voltage direction, and the first flyback power supply cannot work; and the unipolar transistor Q3 is turned on, the third winding is charging the positive half-section bus; the unipolar transistor Q4 is turned off, the fourth winding is not working; the remaining windings are working normally.

3. The auxiliary power supply circuit for improving bus bias voltage according to claim 1, characterized in that, The bus is also connected in parallel with capacitor voltage C1 and capacitor voltage C2 in series; when capacitor voltage C1 is higher than capacitor voltage C2, it drives unipolar transistor Q4, and when capacitor voltage C2 is higher than capacitor voltage C1, it drives unipolar transistor Q3, thus charging the lower voltage half of the bus under controlled conditions.

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